Washing heating systems are carried out by specialized organizations after the preliminary conclusion of an appropriate agreement. Upon completion of flushing heating systems. Sample and appearance of this document depend on the complex of activities carried out by specialists.

Mandatory procedure

Heating systems are a set of equipment (pumps, boilers, pipelines and radiators) designed to heat rooms. Due to the fact that heated water is usually used as a coolant, all parts from the inside are covered with a dense layer of contaminants. Sometimes in pipes such deposits reach more than fifty percent of the cross-section. This reduces heat transfer and lowers the temperature inside the room itself. There are two ways to combat this phenomenon:

• replacement individual parts heating circuit;
• flushing the system.

The second option is considered more preferable, since it does not require serious constructive interventions. After necessary complex activities, a heating system flushing report must be drawn up, a sample of which is available to specialists in the form of prepared forms. They do not have to be ordered from a printing house. To do this, you can use any printing device. How to fill out a heating system flushing report? The sample is usually a standard text in which individual fields that are required to be filled out are deliberately omitted.

It is usually compiled by a representative of the organization involved in the cleanup. What does the act of flushing heating systems look like? A sample form begins with its name and date of preparation. The following information is presented sequentially:

1. Address of the object.
2. Information about the three obligatory participants in whose presence the event takes place this procedure(customer, service company representative, specialist from the cleaning organization).
3. Date of work.
4. From four options, you select the method by which the system was cleaned.
5. water before and after work. The amount used and temperature are indicated separately.
6. The quality of the work performed.

All data specified in the act ends with the signatures of three parties.

Additional work

After other equipment, it is advisable to do pressure testing. This additional procedure will allow you to check the tightness of the entire system and identify places where air or water may escape. Such actions are not mandatory, but highly desirable. They correspond to the interests of both the customer and the contractor. Upon completion, both will be able to verify the quality of the previous stage. The execution of work records the act of washing and its sample will look like a table that contains a list of all activities carried out during such a procedure.

Against each of the points, the specialist must make a note of completion. At the end, as usual, the customer and the contractor put their signatures, confirming the fact of the work. Experts sometimes call this procedure because most often such a test is carried out using water. It is believed that the air may be more dangerous when serious faults are detected. Therefore, many people prefer to take the easier path.

Reliability check

In the spring after graduation heating season the system is usually preserved for summer period. It should be checked before doing this. This measure is quite often used as a preventive measure by service organization specialists in multi-apartment buildings. residential buildings. It is called hydropneumatic testing. The only equipment required for the procedure is a pump with measuring instrument(pressure gauge). The work is carried out in the following sequence:

1. First, the system to be tested must be filled with water.
2. Then you need to connect the press.
3. Check the pressure gauge readings.

The test is usually carried out within thirty minutes. If the readings do not change during this time, then the system is considered sealed. Otherwise, it can be argued that there is a leak in it. Therefore, it is necessary to take measures to eliminate it. Upon completion of the work, a pre-prepared act is drawn up hydropneumatic flushing heating systems. Its sample is similar to all those described earlier.

This form also describes the entire procedure being carried out, indicating the specific value of the measurements taken. The act is signed by representatives of the parties and stored until the next test.

Chemical washingand cleaning of plate heat exchangers

Flushing heat exchangers is performed annually at the end of the heating season, or as necessary, if when checking the actual temperatures and pressure at the outlet of the heat exchanger, a large deviation from the calculated parameters is recorded. Heat transfer in heat exchangers may be reduced if there are large deposits of scale and other substances on the heat exchanger plates. What leads to coking of a collapsible plate heat exchanger, CIP - membrane washing reverse osmosis. Washing installations for washing heat exchangers, boilers, boilers and other technological and heat exchange equipment Connections 1/2“ IG + 1/2“ AG Mains connection 230 V/50 Hz Connected power W 120 Pressure height, max. m in.st. 4.5 Max, circulation rate l/hour 1200 Protection type IP 54 Capacity volume l 8 Temperature, max. °C 60 Empty weight kg 3.5 Delivery unit: 1 piece.

Connections 3/4 AG

Connected power W 120

Head height, max. m in.st. 4.5

Max, circulation rate l/hour 1200

Protection type IP 54

Capacity volume l 20

Amount of acid to be filled, max, l

Temperature, max. °С 60

Empty weight kg 8.5

Delivery unit: 1 piece. Connections 3/4 AG

Mains connection V/Hz 230/50

Connected power W 170

Head height, max. m in.st. 8

Max, circulation rate l/hour 2400

Protection type IP 54

Capacity volume l 20

Amount of acid to be filled, max, l

Temperature, max. °С 60

Empty weight kg 8

Delivery unit: 1 piece.

Mains connection V/Hz 230/50

Connected power W 400

Head height, max. m in.st. 15

Max, circulation rate l/hour 2100

Protection type IP 54

Capacity volume l 40

Amount of acid to be filled, max, l 25

Temperature, max. °С 60

Empty weight kg 15

Delivery unit: 1 piece.

Hose connection diameter: 32 mm

Return stroke 1 = 32 mm

Return stroke 2 = 16 mm

Mains connection V/Hz 230-240/50

Power consumption kilowatt 1.41

Cleaning container volume l 200

Lifting volumes of the station pump 8000 liters/hour

The lifting height of the station pump is 15 meters

Filter fineness pm 5

Length 1100 mm

Width 700 mm

Height 1350 mm

Tare weight kg

Operating temperature, min. Max. C* 5-40

Delivery unit: 1 piece. Reagents solutions for washing heat exchangers CILLIT.Kalkloser P Limescale remover Kalkloser R used in instantaneous water heaters, heat exchangers, boilers, pipelines, coffee makers, dishwashers and washing machines as well as flushing heating systems, etc. Cillit-Kalkloser P can also be used for cleaning reverse osmosis and UV disinfection systems. Kalkloser P White powder, used in installations made of aluminum, silumin, copper, brass, lead, galvanized and tin-plated materials, of stainless steel, chromium, nickel, cast iron (EN-GJL, EN-GJS), unalloyed and low-alloyed iron alloys, as well as for cleaning polysulfone reverse osmosis membranes.

Also a reagent CILLIT.Kalkloser P

CILLIT.Kalkloser P- An environmentally friendly substance - therefore it can be used for washing food equipment.
Reagent CILLIT.Kalkloser P is a white crystalline powder made from organic acids. 1 kg of reagent is capable of dissolving 0.48 kg lime deposits. pH of an aqueous 5% solution is 1–1.5. The fact that the reagent is supplied in dry powder form makes it easy to transport and store without losing its properties for 5 years. Recommended washing time is 2–6 hours. Reagent Kalkloser P supplied in 1 kg bags.
Packaging unit 5 bags per cardboard box.
Delivery unit: Kalkloser P 5 x 1000 g in a cardboard box CILLIT.Kalkloser PCillit-Kalklöser P (5x1000G) Cillit-Kalkloser To remove limestone in flow heaters, boilers, pipelines, washing machines, dishwashers, coffee makers, teapots, etc. Also used in drinking water supply systems. Liquid with low viscosity, used in installations made of aluminum, silumin, lead, galvanized and non-galvanized materials, stainless steel, chromium, nickel, cast iron (EN-GJL, EN-GJS), unalloyed and low-alloyed iron alloys, copper and brass

Also reagent solution CILLIT.Kalkloser designed for removing lime deposits from plate (primarily brazed), shell-and-tube and spiral heat exchangers, boilers, hot water accumulators, boilers and pipelines, reverse osmosis and ultraviolet disinfection units.
CILLIT-Kalkloser is an environmentally friendly substance - therefore can be used for cleaning food equipment .
Delivery unit: 20 kg canisterBWT CILLIT.ZN/I The reagent is intended for removing rust, metal oxides and lime deposits from plate shell-and-tube and spiral heat exchangers, boilers,
hot water accumulators, boilers and pipelines.
CILLIT.ZN/I is a light brown liquid with pH=1. Applicable in
as 10% aqueous solution. Recommended washing time is 1–4 hours, depending on the thickness of the deposits. CILLIT.ZN/I not sensitive to low temperatures.
Reagent Cillit-ZN/I designed for removing limestone and rust deposits in domestic water heaters, instantaneous water heaters, heat exchangers, boilers, circulation circuits. Boiler installations, superheaters. Coolers and condensers. Low-viscosity liquid, used in installations made of cast iron (EN-GJL, EN-GJS), unalloyed and low-alloy alloys of iron, copper, brass and galvanized and tin-plated materials. Delivery unit: 20 kg canister
Additional processing and protection of equipment (passivation) CILLIT.NAW The reagent is intended for additional processing (passivation) of metal
surfaces in plate shell-and-tube and spiral heat exchangers CILLIT.NAW is
is a greenish solution with low viscosity, pH value = 13. Used in the form
5% aqueous solution. The recommended treatment time is 0.5–1 hour, after which the equipment is washed and immediately put into operation.
The reagent is supplied in 20 liter canisters.
Reagent CILLIT.NAW For additional corrosion-preventing treatment (passivation) metal surfaces boilers, direct-flow heaters, pipelines, circulation circuits, boilers, coolers, heaters, superheaters and condensers after chemical cleaning. Low viscosity liquid, used in installations made of various materials, except aluminum, and purified chemicals. substances.
Delivery unit 20 kg canisterNeutralization of used solvents Cillit CILLIT.Neutra P
CILLIT.Kalkloser P and CILLIT.ZN/I before draining them into the sewer, as well as for neutralizing various acidic wastes.
Reagent CILLIT.Neutra P It is a white crystalline powder, slightly soluble in water, used in the form of an aqueous suspension. 300 g of reagent can neutralize 1 kg of CILLIT.Kalkloser P solvent. The fact that the reagent is supplied in dry powder form provides convenience
its transportation and storage in the original packaging, without loss of its properties,
for an unlimited time.
The reagent is supplied in 0.3 kg bags. Packaging unit 5 bags in a cardboard box
box. CILLIT.Neutra P
CILLIT.Neutra The reagent is designed to completely neutralize used solvents
CILLIT before draining them into the sewer, as well as to neutralize various acidic wastes. When disposing of waste solution into the sewer, comply with local treatment requirements. Wastewater. The solution should be diluted with plenty of water or neutralized with Cillit-Neutra or Cillit-Neutra P. Typically, the solvent can be discharged into the central sewer if it has a pH value between 6.5 and 10.0.
Delivery unit: 5 x 300 g in cardboard box Indicator stickspH 0-14 (100 pcs.) Application: Used to determine pH before discharging into the sewer after using a neutralizer CILLIT.Neutra P and CILLIT.Neutra designed for complete neutralization of reagents and solutions Cillit after using these solutions Unit of delivery: 100 pcs. in a plastic box SEK Test Box Test kit for determining the dissolving ability of Cilit reagents
Spare tester for CILLIT solutions – for quick definition scale concentration and efficiency of scale dissolution with this solution. Reusable. Volumetric pipette, glass, test tablets approx. 50 tests, description and rules for conducting the test.
Delivery unit: 1 piece. The technology for washing heat exchange equipment is both simple and effective:
-Attach the washing unit to the heat exchanger;
-Prepare a solution of the required reagent and heat it to the specified temperature;
-Turn the washer unit into circulation mode according to the operating instructions;
-Make sure all the sediment has dissolved,
- (special test kits are included for this purpose);
-Neutralize and drain the spent solution;
-Rinse the heat exchanger;
-Disconnect the sink installation from the heat exchanger;
After this, you will be convinced that the heat exchanger has completely returned to its original characteristics. In addition to significantly increasing the operating efficiency of any type of heat exchanger, installations and reagents produced by the BWT concern increase total time their operation without damaging the plates and sealing gaskets. For economic benefit. It is more profitable to service heating or refrigeration equipment, air conditioning systems, and so on yourself. To do this, you need to buy a unit and reagents. Since the price is this type services are quite high. By comparing the cost of flushing a heat exchanger or other equipment and purchasing maintenance equipment, you can see the difference in price. You also have the opportunity to do annual maintenance or maintenance as needed at your facilities, refrigeration or heating equipment.

Washing machines (installations) as well as equipment for washing collapsible plate heat exchangers, as well as for washing brazed heat exchangers, boilers, boilers, heating systems, as well as hot water supply systems (DHW). There are several models of washing machines for cleaning heat exchangers, as well as other heat exchange equipment, the choice of installations depends primarily on the volume of the container being washed, but in practice it is advisable to buy an installation with a power reserve of the installation itself. Since in the practice of servicing objects, the problem almost always arises in cleaning a larger volume of the washed container. Method of cleaning heat exchangers: dismountable cleaning, washing of heat exchangers, in-place washing of heat exchangers. These installations are designed for non-dismountable cleaning of heat exchangers and other equipment. s using BWT a. The question often arises of how and with what you can rinse and clean the heat exchanger without damaging the sealing plates in the heat exchanger itself. How to perform seasonal maintenance of a heat exchanger, boiler, boiler, or service other heat exchange equipment. How to choose a product, solution, composition, reagent for cleaning the heat exchanger. How and with what to rinse and clean the boiler.

To carry out the process of washing and servicing heat exchange equipment, the BWT concern produces a series of units of different capacities, allowing for the washing of heat exchangers and pipelines of any volume. All BWT washless units are made from industrial plastic and are primarily used in HVAC systems to remove limescale and other types of deposits from the surface of the plates without the need for disassembly or opening plate heat exchanger. Some of these devices are equipped with a system capable of changing the direction of flow of the cleaning solution. These installations are well suited for service organizations that service boiler houses and various facilities where there is a problem with cleaning equipment when working in technological process, the installation can be used to flush the boiler, and the heating system can be easily cleaned, the collapsible plate heat exchanger, as well as the brazed heat exchanger. Washing installations can be used both in industrial and household use Application: for private use in private cottages, when servicing heating systems.

Scale is solid deposits that form on the inner walls of the pipes of steam boilers, water economizers, superheaters, evaporators and other heat exchangers in which water containing certain salts is evaporated or heated. An example of scale is hard deposits inside teapots.

Types of scale. In terms of chemical composition, scale is predominantly found: carbonate (carbon dioxide salts of calcium and magnesium - CaCO3, MgCO3), sulfate (CaSO4) and silicate (silicic acid compounds of calcium, magnesium, iron, aluminum).

Damage from scale The thermal conductivity of scale is tens and often hundreds of times less than the thermal conductivity of the steel from which heat exchangers are made. Therefore, even the thinnest layer of scale creates a large thermal resistance and can lead to such overheating of the pipes of steam boilers and superheaters that bulges and fistulas form in them, often causing rupture of the pipes.

Fighting scale The formation of scale is prevented by chemical treatment of water entering boilers and heat exchangers.

Disadvantage chemical treatment water is the need to select a water chemistry regime and constantly monitor the composition of the source water. Also, when using this method, it is possible to generate waste that requires disposal.

IN last years Methods of physical (reagent-free) water treatment are actively used. One of them is a technology that repels hardness salt ions dissolved in water from the walls of equipment pipes. In this case, instead of a crust of hard scale, suspended microcrystals are formed on the walls, which are carried out of the system by the flow of water. With this method chemical composition water does not change. No harm to environment, there is no need for constant monitoring of the system.

Remove scale mechanically and by chemical means. Acetic acid dissolves scale perfectly; it essentially reacts with the salt on the walls of the kettle and forms other salts, but these are freely floating in the water. For example, scale in a kettle. It needs to be mixed with water in a ratio of 1:10 and the kettle boiled over low heat. The scale will dissolve before your eyes. Lemon acid good for dissolving impurities deposited on water purification filters. Of course, it must be dissolved in water. Adipic acid is usually used in production and it is the basis of most household descaling products.

At mechanical cleaning there is a danger of damage protective layer metal or even the equipment itself, since the boiler or heat exchanger must be completely or partially disassembled for cleaning. Without a doubt, this is a very expensive method, because... Often the cost of equipment downtime is much higher than the cost of cleanup.

Chemical cleaning can be used without completely disassembling the boiler or heat exchanger. But there is a danger that too long exposure to acid can damage the metal of the boiler, and shorter exposure will not sufficiently clean the surfaces.

RUSSIAN JOINT STOCK COMPANY
ENERGY AND ELECTRIFICATION
"UES OF RUSSIA"

DEPARTMENT OF SCIENCE AND TECHNOLOGY

STANDARD INSTRUCTIONS
ON PERFORMANCE CHEMICALS
CLEANING WATER BOILERS

RD 34.37.402-96

ORGRES

Moscow 1997

DevelopedJSC Firm ORGRES

PerformersV.P. SEREBRYAKOV, A.YU. BULAVKO (JSC Firm ORGRES), S.F. SOLOVIEV(JSC Rostenergo), HELL. EFREMOV, N.I. SHADRINA(OJSC "Kotloochistka")

ApprovedDepartment of Science and Technology of RAO UES of Russia 01/04/96

Boss A.P. BERSENEV

STANDARD INSTRUCTIONS PERFORMANCE CHEMICAL CLEANING WATER BOILERS

RD 34.37.402-96

Expiration date set

from 01.10.97

INTRODUCTION

1. Standard instructions(hereinafter referred to as the Instructions) is intended for personnel of design, installation, commissioning and operating organizations and is the basis for designing schemes and selecting technology for cleaning hot water boilers at specific sites and drawing up local work instructions (programs).

2. The instructions are drawn up on the basis of experience in carrying out operational chemical cleaning of hot water boilers, accumulated in recent years of their operation, and defines general order and conditions for the preparation and conduct of operational chemical cleaning of hot water boilers.

The Instructions take into account the requirements of the following regulatory and technical documents:

Technical Operation Rules power stations and networks of the Russian Federation (M.: SPO ORGRES, 1996);

Standard instructions for operational chemical cleaning of hot water boilers (M.: SPO Soyuztekhenergo, 1980);

Instructions for analytical control during chemical cleaning of thermal power equipment (M.: SPO Soyuztekhenergo, 1982);

Guidelines for water treatment and water chemistry regime of water heating equipment and heating networks: RD 34.37.506-88 (M.: Rotaprint VTI, 1988);

Consumption standards for reagents for pre-start and operational chemical cleaning of thermal power equipment of power plants:HP 34-70-068-83(M.: SPO Soyuztekhenergo, 1985);

Guidelines for the use of calcium hydroxide for the conservation of thermal power and other industrial equipment at the facilities of the USSR Ministry of Energy (M.: SPO Soyuztekhenergo, 1989).

3. When preparing and carrying out chemical cleaning of boilers, you should also comply with the documentation requirements of the equipment manufacturers involved in the cleaning scheme.

4. With the release of this Instruction, the “Standard Instructions for Operational Chemical Cleaning of Hot Water Boilers” (Moscow: SPO Soyuztekhenergo, 1980) becomes invalid.

1. GENERAL PROVISIONS

1.1. During the operation of hot water boilers at internal surfaces deposits form in the water path. Subject to compliance with the regulated water regime the deposits consist mainly of iron oxides. In case of violations of the water regime and use for recharging networks poor quality water or blowdown water from power boilers, deposits may also contain (in amounts from 5% to 20%) hardness salts (carbonates), compounds of silicon, copper, and phosphates.

If the water and combustion regimes are observed, deposits are evenly distributed along the perimeter and height of the screen pipes. A slight increase in them can be observed in the burner area, and a decrease in the hearth area. With a uniform distribution of heat flows, the amount of deposits on individual screen pipes is basically approximately the same. On pipes of convective surfaces, deposits are also generally evenly distributed around the perimeter of the pipes, and their quantity is, as a rule, less than on pipes of screens. However, unlike convective surfaces on individual pipes, the difference in the amount of deposits can be significant.

1.2. Determination of the amount of deposits formed on heating surfaces during boiler operation is carried out after each heating season. To do this from various areas pipe samples with a length of at least 0.5 m are cut out from heating surfaces. The number of these samples should be sufficient (but not less than 5 - 6 pieces) to assess the actual contamination of the heating surfaces. It is mandatory to cut samples from the screen pipes in the area of ​​the burners, from the top row of the upper convective package and bottom row lower convective packet. The need to cut an additional number of samples is specified in each individual case depending on the operating conditions of the boiler. Definition specific amount deposits (g/m2) can be carried out in three ways: by the loss of mass of the sample after etching it in an inhibited acid solution, by the loss of mass after cathodic etching and by weighing the deposits removed mechanically. The most accurate method listed is cathodic etching.

The chemical composition is determined from an average sample of deposits removed from the sample surface mechanically, or from a solution after etching the samples.

1.3. Operational chemical cleaning is designed to remove deposits formed from the inner surface of pipes. It should be carried out when the contamination of the heating surfaces of the boiler is 800 - 1000 g/m2 or more or when the hydraulic resistance of the boiler increases by 1.5 times compared to the hydraulic resistance of a clean boiler.

The decision on the need for chemical cleaning is made by a commission chaired by the chief engineer of the power plant (head of the heating boiler room) based on the results of analyzes of the specific contamination of heating surfaces, determining the condition of the pipe metal, taking into account boiler operation data.

Chemical cleaning is usually carried out in the summer, when the heating season is over. In exceptional cases, it can be performed with winter if it is violated safe work boiler

1.4. Chemical cleaning must be carried out using a special installation, including equipment and pipelines ensuring the preparation of flushing and passivating solutions, their pumping through the boiler path, as well as the collection and neutralization of waste solutions. Such an installation must be carried out according to the design and linked with general plant equipment and schemes for neutralization and neutralization of power plant waste solutions.

2. REQUIREMENTS TECHNOLOGY AND CLEANING SCHEME

2.1. Washing solutions must provide high-quality cleaning of surfaces, taking into account the composition and amount of deposits present in the boiler screen pipes and to be removed.

2.2. It is necessary to evaluate the corrosion damage to the pipe metal of the heating surfaces and select cleaning conditions with a washing solution with the addition of effective inhibitors to reduce pipe metal corrosion during cleaning to acceptable values ​​and limit the occurrence of leaks during chemical cleaning of the boiler.

2.3. The cleaning scheme must ensure the efficiency of cleaning heating surfaces and the complete removal of solutions, sludge and suspended matter from the boiler. Cleaning boilers using a circulation scheme should be carried out at speeds of movement of the washing solution and water that ensure specified conditions. In this case, the design features of the boiler, the location of convective packets in the water path of the boiler and the presence of large quantity horizontal pipes small diameter with multiple bends of 90 and 180°.

2.4. It is necessary to neutralize the remaining acid solutions and post-wash passivation of the heating surfaces of the boiler to protect against corrosion during boiler downtime from 15 to 30 days or subsequent conservation of the boiler.

2.5. At When choosing a technology and treatment scheme, environmental requirements must be taken into account and installations and equipment for neutralization and decontamination of waste solutions must be provided.

2.6. All technological operations should be carried out, as a rule, by pumping cleaning solutions through the boiler water path along closed loop. The speed of movement of washing solutions when cleaning hot water boilers must be at least 0.1 m/s, which is acceptable, as it ensures uniform distribution of the washing reagent in the pipes of the heating surfaces and a constant supply of fresh solution to the surface of the pipes. Water washes must be carried out at discharge speeds of at least 1.0 - 1.5 m/s.

2.7. Spent washing solutions and the first portions of water during water washing should be sent to the station-wide neutralization and decontamination unit. Water is drained into these installations until a pH value of 6.5 - 8.5 is reached at the boiler outlet.

2.8. When performing all technological operations (with the exception of final water washing with network water according to the standard scheme), process water is used. It is permissible to use network water for all operations, if possible.

3. SELECTION OF CLEANING TECHNOLOGY

3.1. For all types of deposits found in hot water boilers, you can use hydrochloric or sulfuric acid, sulfuric acid with ammonium hydrofluoride, sulfamic acid, low molecular weight acid concentrate (LMAC) as a washing reagent.

The choice of cleaning solution is made depending on the degree of contamination of the boiler heating surfaces to be cleaned, the nature and composition of deposits. To develop a technological cleaning regime, samples of pipes cut from the boiler with deposits are treated in laboratory conditions with the selected solution while maintaining optimal performance of the cleaning solution.

3.2. Hydrochloric acid is mainly used as a cleaning agent. This is explained by her high cleaning properties, allowing you to clean heating surfaces from any type of deposits, even with high specific contamination, as well as the non-scarcity of the reagent.

Depending on the amount of deposits, cleaning is carried out in one (for contamination up to 1500 g/m2) or in two stages (for greater contamination) with a solution with a concentration of 4 to 7%.

3.3. Sulfuric acid is used to clean heating surfaces from iron oxide deposits with a calcium content of no more than 10%. In this case, the concentration of sulfuric acid, in order to ensure its reliable inhibition during solution circulation in the cleaning circuit, should be no more than 5%. When the amount of deposits is less than 1000 g/m2, one stage of acid treatment is sufficient; for contamination up to 1500 g/m2, two stages are required.

When only vertical pipes (heating screen surfaces) are subject to cleaning, it is permissible to use the etching method (without circulation) with a sulfuric acid solution with a concentration of up to 10%. When the amount of deposits is up to 1000 g/m2, one acid stage is required, with greater contamination - two stages.

As a washing solution for removing iron oxide (in which calcium is less than 10%) deposits in an amount of no more than 800 - 1000 g/m2, we can also recommend a mixture of a dilute solution of sulfuric acid (concentration less than 2%) with ammonium hydrofluoride (of the same concentration). the mixture is characterized by an increased rate of deposit dissolution compared to sulfuric acid. A feature of this cleaning method is the need to periodically add sulfuric acid to maintain the pH of the solution at an optimal level of 3.0 - 3.5 and to prevent the formation of Fe hydroxide compounds ( III).

The disadvantages of methods using sulfuric acid include the formation of a large amount of suspension in the cleaning solution during the cleaning process and a lower rate of dissolution of deposits compared to hydrochloric acid.

3.4. If heating surfaces are contaminated with carbonate-iron oxide deposits in amounts up to 1000 g/m2, sulfamic acid or NMC concentrate can be used in two stages.

3.5. When using all acids, it is necessary to introduce corrosion inhibitors into the solution, protecting the metal of the boiler from corrosion under the conditions of use of this acid (acid concentration, solution temperature, presence of movement of the washing solution).

For chemical cleaning, as a rule, inhibited hydrochloric acid is used, into which one of the corrosion inhibitors PB-5, KI-1, B -1 (B-2). When preparing a washing solution of this acid, the inhibitor urotropine or KI-1 must be additionally introduced.

For solutions of sulfuric and sulfamic acids, ammonium hydrofluoride, and MNC concentrate, mixtures of catapine or catamine AB with thiourea or thiuram or captax are used.

3.6. If the contamination is above 1500 g/m2 or if there is more than 10% silicic acid or sulfates in the deposits, it is recommended to carry out alkalization before acid treatment or between acid stages. Alkalinization is usually carried out between acid stages with a solution of sodium hydroxide or a mixture of it with soda ash. Addition to caustic soda soda ash in an amount of 1 - 2% increases the effect of loosening and removing sulfate deposits.

If there are deposits in the amount of 3000 - 4000 g/m2, cleaning heating surfaces may require sequential alternation of several acid and alkaline treatments.

To intensify the removal of solid iron oxide deposits, which are located in the lower layer, and if there are more than 8 - 10% silicon compounds in the deposits, it is advisable to add fluorine-containing reagents (fluoride, ammonium or sodium hydrofluoride) to the acid solution, added to the acid solution after 3 - 4 hours after the start of processing.

In all these cases, preference should be given to hydrochloric acid.

3.7. For post-flush passivation of the boiler, in cases where it is necessary, one of the following treatments is used:

a) treatment of cleaned heating surfaces with a 0.3 - 0.5% solution of sodium silicate at a solution temperature of 50 - 60 ° C for 3 - 4 hours while circulating the solution, which will provide protection against corrosion of the boiler surfaces after draining the solution in humid conditions in for 20 - 25 days and in a dry atmosphere for 30 - 40 days;

b) treatment with a solution of calcium hydroxide in accordance with the guidelines for its use for the preservation of boilers.

4. CLEANING SCHEME

4.1. The chemical cleaning scheme for a hot water boiler includes the following elements:

boiler to be cleaned;

a tank intended for the preparation of cleaning solutions and simultaneously serving as an intermediate container when organizing the circulation of cleaning solutions in a closed circuit;

a flushing pump for mixing solutions in the tank along the recirculation line, supplying the solution to the boiler and maintaining the required flow rate when pumping the solution through a closed circuit, as well as for pumping the waste solution from the tank to the neutralization and neutralization unit;

pipelines connecting the tank, pump, boiler into a single cleaning circuit and ensuring pumping of solution (water) through closed and open circuits;

neutralization and neutralization unit, where used cleaning solutions and contaminated water are collected for neutralization and subsequent neutralization;

hydraulic ash removal channels (GZU) or industrial storm drainage channels (PLC), where they are allocated conditionally clear waters(with pH 6.5 - 8.5) when cleaning the boiler from suspended substances;

tanks for storing liquid reagents (primarily hydrochloric or sulfuric acid) with pumps for supplying these reagents to the cleaning circuit.

4.2. The flushing tank is intended for preparing and heating cleaning solutions; it is a averaging tank and a place for removing gas from the solution in the circulation circuit during cleaning. The tank must have anti-corrosion coating, must be equipped with a loading hatch with a mesh with mesh size 10´ 10 ÷ 15 ´ 15 mm or with a perforated bottom with holes of the same size, level glass, thermometer sleeve, overflow and drainage pipelines. The tank must have a fence, a ladder, a device for lifting bulk reagents, and lighting. Pipelines for supplying liquid reagents, steam, and water must be connected to the tank. Heating of solutions with steam is carried out through a bubbling device located in the lower part of the tank. It is advisable to bring it into the tank hot water from the heating network (with return line). Process water can be supplied both to the tank and to the suction manifold of the pumps.

The capacity of the tank must be at least 1/3 of the volume of the flushing circuit. When determining this value, it is necessary to take into account the capacity of the network water pipelines included in the cleaning circuit, or those that will be filled during this operation. As practice shows, for boilers with a thermal productivity of 100 - 180 Gcal/h, the tank volume must be at least 40 - 60 m 3.

To ensure uniform distribution and facilitate the dissolution of bulk reagents, it is advisable to run a 50 mm diameter pipeline with a rubber hose from the recirculation pipeline inserted into the tank for mixing solutions into the loading hatch.

4.3. A pump designed to pump the cleaning solution through the cleaning circuit must provide a movement speed of at least 0.1 m/s in the pipes of the heating surfaces. The selection of this pump is made according to the formula

Q= (0.15 ÷ 0.2) S 3600,

Where Q- pump flow, m 3 / h;

0.15 ÷ 0.2 - minimum solution speed, m/s;

S- maximum cross-sectional area of ​​the boiler water path, m2;

3600 - conversion factor.

For chemical cleaning of hot water boilers with a thermal output of up to 100 Gcal/h, pumps with a flow rate of 350 - 400 m 3 /h can be used, and for cleaning boilers with a thermal output of 180 Gcal/h - 600 - 700 m 3 /h. The pressure of the flushing pumps must be no less than the hydraulic resistance of the flushing circuit at a speed of 0.15 - 0.2 m/s. For most boilers, this speed corresponds to a pressure of no higher than 60 m of water. Art. To pump washing solutions, two pumps are installed, designed for pumping acids and alkalis.

4.4. Pipelines intended for organizing the pumping of cleaning solutions in a closed circuit must have diameters no less than the diameters of the suction and pressure pipes of the flushing pumps, respectively; pipelines for discharging spent washing solutions from the cleaning circuit to the neutralizer tank can have diameters significantly smaller than the diameters of the main pressure-return pipes ( waste) collectors.

The cleaning circuit must be capable of draining all or most of the cleaning solution into the tank.

The diameter of the pipeline intended for drainage of washing water into the industrial storm canal or gas treatment system must take into account the throughput of these pipelines. The boiler cleaning circuit pipelines must be stationary. Their routing must be chosen in such a way that they do not interfere with the maintenance of the main equipment of the boiler during operation. The fittings on these pipelines must be located in accessible places, and the routing of the pipelines must ensure their emptying. If there are several boilers at a power plant (heating boiler house), common pressure-return (discharge) manifolds are installed, to which pipelines are connected, intended for cleaning a separate boiler. Shut-off valves must be installed on these pipelines.

4.5. The collection of cleaning solutions coming from the tank (via the overflow line, drain line), from sampler troughs, from pump leaks through seals, etc., must be carried out in a pit, from where they are sent to the neutralization unit by a special pump.

4.6. When carrying out acid treatments, fistulas often form in the heating surfaces of the boiler and in the pipelines of the flushing circuit. A violation of the density of the cleaning circuit can occur at the beginning of the acid stage, and the amount of loss of the cleaning solution will not allow further execution of the operation. To speed up the emptying of the defective area of ​​the boiler heating surface and subsequent safe repair work to eliminate leaks, it is advisable to top part supply nitrogen to the boiler or compressed air. For most boilers, a convenient connection point is the boiler vents.

4.7. The direction of movement of the acid solution in the boiler circuit must take into account the location of the convective surfaces. It is advisable to organize the direction of movement of the solution in these surfaces from top to bottom, which will facilitate the removal of exfoliated sediment particles from these boiler elements.

4.8. The direction of movement of the washing solution in the screen pipes can be any, since with an upward flow at a speed of 0.1 - 0.3 m/s, tiny suspended particles will pass into the solution, which at these speeds will not settle in the coils of convective surfaces when moving from above down. Large sediment particles, for which the movement speed is less than the soaring speed, will accumulate in the lower collectors of the screen panels, so their removal from there must be done by intensive water washing at a water speed of at least 1 m/s.

For boilers in which convective surfaces are the outlet sections of the water path, it is advisable to organize the flow direction so that they are the first in the direction of movement of the washing solution when pumping along a closed circuit.

The cleaning circuit should have the ability to change the direction of flow to the opposite, for which a jumper must be provided between the pressure and discharge pipelines.

Ensuring the speed of movement of the cleaning water above 1 m/s can be achieved by connecting the boiler to the heating mains, and the circuit should provide for pumping water through a closed circuit with constant removal of cleaning water from the boiler circuit while simultaneously supplying water to it. The amount of water supplied to the purification circuit must correspond bandwidth discharge channel.

In order to constantly remove gases from individual sections of the water path, the boiler air vents are combined and discharged into a flushing tank.

The connection of the pressure-return (discharge) pipelines to the water path should be made as close to the boiler as possible. To clean sections of the network water pipeline between the sectional valve and the boiler, it is advisable to use the bypass line of this valve. In this case, the pressure in the water path should be less than in the network water pipeline. In some cases, this line can serve as an additional source of water entering the cleaning circuit.

4.9. To increase the reliability of the cleaning circuit and greater safety during its maintenance, it must be equipped with steel reinforcement. In order to eliminate the overflow of solutions (water) from pressure pipeline in the return line along the jumper between them, passing them into the discharge channel or neutralizing tank and to be able to install a plug if necessary, the fittings on these pipelines, as well as on the recirculation line to the tank, must be flanged. The principle (general) diagram of the installation for chemical cleaning of boilers is shown in Fig. .

4.10. When chemically cleaning PTVM-30 and PTVM-50 boilers (Fig. , ), the flow area of ​​the water path when using pumps with a flow rate of 350 - 400 m 3 / h ensures a solution movement speed of about 0.3 m/s. The sequence of passage of the cleaning solution through the heating surfaces may coincide with the movement of network water.

When cleaning the PTVM-30 boiler Special attention it is necessary to pay attention to the organization of gas removal from the upper collectors of the screen panels, since the direction of movement of the solution has multiple changes.

For the PTVM-50 boiler, it is advisable to supply the cleaning solution into the direct network water pipeline, which will allow organizing the direction of its movement in the convective package from top to bottom.

4.11. When chemically cleaning the KVGM-100 boiler (Fig.), the supply and return pipelines for cleaning solutions are connected to the return and direct network water pipelines. The movement of the medium is carried out in the following sequence: front screen - two side screens - intermediate screen - two convective beams - two side screens - rear screen. When passing through the water path, the washing flow repeatedly changes the direction of movement of the medium. Therefore, when cleaning this boiler, special attention should be paid to organizing the constant removal of gases from the upper screen surfaces.

4.12. When chemically cleaning a PTVM-100 boiler (Fig.), the movement of the medium is organized either according to a two- or four-pass scheme. When using a two-pass scheme, the speed of the medium will be about 0.1 - 0.15 m/s when using pumps with a flow rate of about 250 m 3 /h. When organizing a two-way movement pattern, the supply and discharge pipelines for the cleaning solution are connected to the return and direct network water pipelines.

When using a four-pass scheme, the speed of movement of the medium when using pumps of the same flow rate is doubled. The connection of the supply and discharge pipelines of the cleaning solution is organized into bypass pipelines from the front and rear screens. Setting up a four-way circuit requires installing a plug on one of these pipelines.

Rice. 1. Installation diagram for chemical cleaning of the boiler:

1 - flushing tank; 2 - flushing pumps ;

Rice. 2. Scheme for chemical cleaning of the PTVM-30 boiler:

1 - rear additional screens; 2 - convective beam; 3 - side screen of the convective shaft; 4 - side screen; 5 - front screens; 6 - rear screens;

Valve closed

Rice. 3. Scheme of chemical cleaning of the PTVM-50 boiler :

1 - right side screen; 2 - upper convective beam; 3 - lower convective beam; 4 - rear screen; 5 - left side screen; 6 - front screen;

Valve closed

Rice. 4. Scheme for chemical cleaning of the boiler KVGM-100 (main mode):

1 - front screen; 2 - side screens; 3 - intermediate screen; 4 - side screen; 5 - rear screen; 6 - convective beams;

Valve closed

Rice. 5. Scheme for chemical cleaning of the PTVM-100 boiler:

a - two-way; b - four-way;

1 - left side screen; 2 - rear screen; 3 - convective beam; 4 - right side screen; 5 - front screen;

The movement of the medium when using a two-pass scheme corresponds to the direction of movement of water in the water path of the boiler during its operation. When using a four-pass scheme, the washing solution passes through the heating surfaces in the following sequence: front screen - convective packages of the front screen - side (front) screens - side (rear) screens - convective packages of the rear screen - rear screen.

The direction of movement may be reversed when changing the purpose of temporary pipelines connected to the boiler bypass pipelines.

4.13. When chemically cleaning a PTVM-180 boiler (Fig. , ), the movement of the medium is organized either according to a two- or four-pass scheme. When organizing medium pumping according to a two-pass scheme (see Fig.), the pressure and discharge pipelines are connected to the return and direct network water pipelines. With this scheme, the preferred direction of the medium in convective packets is from top to bottom. To create a movement speed of 0.1 - 0.15 m/s, it is necessary to use a pump with a flow rate of 450 m 3 /h.

When pumping the medium using a four-pass scheme, the use of a pump of this type will provide a movement speed of 0.2 - 0.3 m/s.

The organization of a four-way circuit requires the installation of four plugs on the bypass pipelines from the upper distribution manifold of network water to the two-way and side screens, as shown in Fig. . The connection of the pressure and discharge pipelines in this scheme is carried out to the return network water pipeline and to all four bypass pipes disconnected from the return network water chamber. Considering that the bypass pipes haveD at 250 mm and most of its routing consists of rotary sections; connecting pipelines to organize a four-way circuit requires a lot of labor.

When using a four-pass scheme, the direction of movement of the medium along the heating surfaces is as follows: the right half of the two-light and side screens - the right half of the convective part - the rear screen - the direct network water chamber - the front screen - the left half of the convective part - the left half of the side and two-light screens.

Rice. 6. Scheme for chemical cleaning of the PTVM-180 boiler (two-way scheme):

1 - rear screen; 2 - convective beam; 3 - side screen; 4 - two-light screen; 5 - front screen;

Valve closed

Rice. 7. Scheme for chemical cleaning of the PTVM-180 boiler (four-way scheme):

1 - rear screen; 2- convective beam; 3- side screen; 4 - two-light screen; 5 - front screen ;

4.14. During chemical cleaning of the KVGM-180 boiler (Fig.), the movement of the medium is organized according to a two-pass scheme. The speed of movement of the medium in the heating surfaces at a flow rate of about 500 m 3 /h will be about 0.15 m/s. The pressure and return pipelines are connected to the return and direct network water pipelines (chambers).

The creation of a four-pass flow diagram for the medium in relation to this boiler requires much more modifications than for the PTVM-180 boiler, and therefore its use when performing chemical cleaning is impractical.

Rice. 8. Chemical cleaning scheme for the KVGM-180 boiler:

1 - convective beam; 2 - rear screen; 3 - ceiling screen; 4 - intermediate screen; 5 - front screen;

Valve closed

The direction of movement of the medium in the heating surfaces should be organized taking into account the change in flow direction. During acid and alkaline treatments, it is advisable to direct the movement of the solution in convective bags from bottom to top, since these surfaces will be the first in the circulation circuit along a closed loop. During water washes, it is advisable to periodically reverse the flow movement in convective packets.

4.15. Cleaning solutions are prepared either in portions in a washing tank and then pumping them into the boiler, or by adding a reagent to the tank while circulating heated water through a closed cleaning circuit. The amount of the prepared solution must correspond to the volume of the cleaning circuit. The amount of solution in the circuit after organizing pumping in a closed circuit should be minimal and determined by the required level for reliable operation pump, which is ensured by maintaining a minimum level in the tank. This allows you to add acid during processing to maintain the required concentration or pH value. Each of the two methods is acceptable for all acid solutions. However, when performing cleaning using a mixture of ammonium hydrofluoride and sulfuric acid, the second method is preferred. It is better to dose sulfuric acid into the cleaning circuit at the top of the tank. The acid can be introduced either by a plunger pump with a supply of 500 - 1000 l/h, or by gravity from a tank installed at a level above the flushing tank. Corrosion inhibitors for cleaning solutions based on hydrochloric or sulfuric acid do not require special conditions for their dissolution. They are loaded into the tank before acid is introduced into it.

The mixture of corrosion inhibitors used for washing solutions of sulfuric and sulfamic acids, a mixture of ammonium hydrofluoride with sulfuric acid and NMC, is prepared in a separate container in small portions and poured into the tank hatch. Installation of a special tank for this purpose is not necessary, since the amount of the prepared inhibitor mixture is small.

5. TECHNOLOGICAL CLEANING MODES

Approximate technological modes used to clean boilers from various deposits, in accordance with section. are given in table. .

Table 1

	Type and quantity of deposits removed	Technological operation	Composition of the solution	Technological operation parameters				Note
				Reagent concentration, %	Temperature environment, °C	Duration, h	End Criteria
1. Hydrochloric acid during circulation	No limits	1.1 Water rinsing			20 and above	1 - 2
		1.2. Bucking	NaOH Na 2 CO 3	1,5 - 2 1,5 - 2	80 - 90	8 - 12	By time	The need for an operation is determined when choosing a cleaning technology depending on the amount and composition of deposits
		1.3. Washing process water			20 and above	2 - 3	The pH value of the discharged solution is 7 - 7.5
		1.4. Preparation in the circuit and circulation of the acid solution	Inhibited HCl Urotropine (or KI-1)	4 - 6 (0,1)	60 - 70	6 - 8		When removing carbonate deposits and reducing the acid concentration, periodically add acid to maintain the concentration of 2 - 3%. When removing iron oxide deposits without adding acid
		1.5. Washing with technical water			20 and above	1 - 1,5	Clarification of discharged water	When carrying out two or three acid stages, it is allowed to drain the washing solution by filling the boiler once with water and draining it
		1.6. Re-treatment of the boiler with an acid solution during circulation	Inhibited HCl Urotropine (or KI-1)	3 - 4 (0,1)	60 - 70	4 - 6		Performed when the amount of deposits is more than 1500 g/m2
		1.7. Washing with technical water			20 and above	1 - 1,5	Clarification of wash water, neutral environment
		1.8. Neutralization during solution circulation	NaOH (or Na 2 CO 3)	2 - 3	50 - 60	2 - 3	By time
		1.9. Drainage of alkaline solution
		1.10. Pre-washing with industrial water			20 and above		Clarification of discharged water
		1.11. Final cleaning with network water into the heating network			20-80			Carried out immediately before putting the boiler into operation
2. Sulfuric acid in circulation	<10 % при количестве отложений до 1500 г/м 2	2.1. Water rinsing			20 and above	1 - 2	Clarification of discharged water
		2.2. Filling the boiler with an acid solution and circulating it in the circuit	H2SO4	3 - 5	40 - 50	4 - 6	Stabilization of iron concentration in the circuit, but not more than 6 hours	No additional acid dosage
			KI-1 (or katamin)	0,1 (0,25)
			Thiuram (or thiourea)	0,05 (0,3)
		2.3. Performing the operation according to clause.
		2.4. Re-treatment of the boiler with acid during circulation	H2SO4	2 - 3	40 - 50	3 - 4	Stabilization of iron concentration	Performed when the amount of deposits exceeds 1000 g/m3
			KI-1
			Tiuram	0,05
		2.5. Performing operations according to paragraphs. 1.7 - 1.11
3. Sulfuric acid etching	Same	3.1. Water rinsing			20 and above	1 - 2	Clarification of discharged water
		3.2. Filling boiler screens with solution and etching them	H2SO4	8 - 10	40 - 55	6 - 8	By time	It is possible to use inhibitors: catapina AB 0.25% With thiuram 0.05%. When using less effective inhibitors (1% methenamine or formaldehyde), the temperature should not exceed 45 °C
			KI-1
			Thiuram (or thiourea)	0,05 (0,3)
		3.3. Performing the operation according to clause.
		3.4. Repeated acid treatment	H2SO4	4 - 5	40 - 55	4 - 6	By time	Performed when the amount of deposits exceeds 1000 g/m2
			KI-1
			Tiuram	0,05
		3.5. Performing the operation according to clause 1.7
		3.6. Neutralization by filling screens with solution	NaOH (or Na 2 CO 3)	2 - 3	50 - 60	2 - 3	By time
		3.7. Drainage of alkaline solution
		3.8. Performing the operation according to clause 1.10						Filling and draining the boiler two or three times until a neutral reaction is allowed
		3.9. Performing the operation according to clause 1.11
4. Ammonium hydrofluoride with sulfuric acid in circulation	Iron oxide containing calcium<10 % при количестве отложений не более 1000 г/м 2	4.1. Water rinsing			20 and above	1 - 2	Clarification of discharged water
		4.2. Preparation of the solution in the circuit and its circulation	NH 4 HF 2	1,5 - 2	50 - 60	4 - 6	Stabilization of iron concentration	It is possible to use inhibitors: 0.1% OP-10 (OP-7) with 0.02% captax. When pH increases above 4.3 - 4.4, add sulfuric acid to pH 3 - 3.5
			H 2 SO 4	1,5 - 2
			KI-1
			Thiuram (or captax)	0,05 (0,02)
		4.3. Performing the operation according to clause 1.5
		4.4. Re-treatment with cleaning solution	NH 4 HF 2	1 - 2	50 - 60	4 - 6	Stabilization of iron concentration in the circuit at pH 3.5-4.0
			H2SO4	1 - 2
			KI-1
			Thiuram (or captax)	0,05 (0,02)
		4.5. Performing operations according to paragraphs. 1.7 - 1.11
5. Sulfamic acid in circulation	Carbonate-iron oxide in quantities up to 1000 g/m2	5.1. Water rinsing			20 and above	1 - 2	Clarification of discharged water
		5.2. Filling the circuit with solution and circulating it	Sulfamic acid	3 - 4	70 - 80	4 - 6	Stabilization of hardness or iron concentration in the circuit	No additional dosage of acid. It is advisable to maintain the solution temperature by igniting one burner
			OP-10 (OP-7)
			Captax	0,02
		5.3. Performing the operation according to clause 1.5
		5.4. Repeated acid treatment as in paragraph 5.2
		5.5. Performing operations according to paragraphs. 1.7 - 1.11
6. NMK concentrate during circulation	Carbonate and carbonate-iron oxide deposits in quantities up to 1000 g/m2	6.1. Water flushing			20 and above	1 - 2	Clarification of discharged water
		6.2. Cooking in solution circuit and its circulation	NMC in terms of acetic acid	7 - 10	60 - 80	5 - 7	Stabilization of iron concentration in the circuit	No additional acid dosage
		8.3. Performing the operation according to clause 1.5	OP-10 (OP-7)
		6.4. Repeated acid treatment as in paragraph 6.2 6.5. Performing operations according to paragraphs. 1.7 - 1.11	Captax	0,02

Radiation surface of screens, m 2

Surface of convective packets, m 2

Boiler water volume, m 3

ptvm -30

128,6

PTVM-50

1110

PTVM-100

2960

PTVM-180

5500

kvgm -30

KVGM-50

1223

KVGM-100

2385

KVGM-180

5520

80 - 100

Data on the surface area of ​​pipes to be cleaned and their water volume for the most common boilers are given in table. . The actual volume of the cleaning circuit may differ slightly from that indicated in the table. and depends on the length of the return and direct network water pipelines filled with the cleaning solution.

7.5. Consumption of sulfuric acid to obtain a pH value of 2.8 - 3.0 in mixtures with ammonium hydrofluoride are calculated based on the total concentration of the components at their mass ratio of 1: 1.

From stoichiometric ratios and based on the practice of purification, it has been established that per 1 kg of iron oxides (in terms of F e 2 O 3) about 2 kg of ammonium hydrofluoride and 2 kg of sulfuric acid are consumed. When cleaning with a solution of 1% ammonium hydrofluoride with 1% sulfuric acid, the concentration of dissolved iron (in terms of F e 2 O 3) can reach 8 - 10 g/l.

8. MEASURES IN COMPLIANCE WITH SAFETY RULES

8.1. When preparing and carrying out work on chemical cleaning of hot water boilers, it is necessary to comply with the requirements of the “Safety Rules for the Operation of Thermal Mechanical Equipment of Power Plants and Heating Networks” (M.: SPO ORGRES, 1991).

8.2. Technological operations for chemical cleaning of the boiler begin only after all preparatory work has been completed and repair and installation personnel have been removed from the boiler.

8.3. Before carrying out chemical cleaning, all personnel of the power plant (boiler house) and contracting organizations involved in chemical cleaning undergo safety training when working with chemical reagents with an entry in the training log and signature of those instructed.

8.4. An area is organized around the boiler to be cleaned, the wash tank, pumps, pipelines, and appropriate warning posters are posted.

8.5. Protective handrails are manufactured on the tanks for preparing reagent solutions.

8.6. Good lighting is provided for the boiler being cleaned, pumps, fittings, pipelines, stairs, platforms, sampling points and the duty shift workplace.

8.7. A water supply is organized through hoses to the reagent preparation unit and to the personnel’s place of work to wash off spilled solutions or solutions that spill through leaks.

8.8. Means are provided for neutralizing cleaning solutions in case of a violation of the density of the flushing circuit (soda, bleach, etc.).

8.9. The workplace of the duty shift is provided with a first aid kit with medications necessary for first aid (individual bags, cotton wool, bandages, tourniquet, boric acid solution, acetic acid solution, soda solution, weak solution of potassium permanganate, petroleum jelly, towel).

8.10. Persons not directly involved in chemical cleaning are not allowed to be present in hazardous areas near the equipment being cleaned and the area where washing solutions are discharged.

8.11. Hot work is prohibited near the chemical cleaning site.

8.12. All work on receiving, transferring, draining acids, alkalis, and preparing solutions is carried out in the presence and under the direct supervision of technical managers.

8.13. Personnel directly involved in chemical cleaning work are provided with woolen or canvas suits, rubber boots, rubberized aprons, rubber gloves, goggles, and a respirator.

8.14. Repair work on the boiler and reagent tank is permitted only after thorough ventilation.

Application

CHARACTERISTICS OF REAGENTS USED IN CHEMICAL CLEANING OF WATER BOILERS

1. Hydrochloric acid

Technical hydrochloric acid contains 27 - 32% hydrogen chloride, has a yellowish color and a suffocating odor. Inhibited hydrochloric acid contains 20 - 22% hydrogen chloride and is a yellow to dark brown liquid (depending on the inhibitor introduced). PB-5, V-1, V-2, catapin, KI-1, etc. are used as inhibitors. The inhibitor content in hydrochloric acid is in the range of 0.5 ÷ 1.2%. The dissolution rate of St 3 steel in inhibited hydrochloric acid does not exceed 0.2 g/(m 2 h).

The freezing point of a 7.7% hydrochloric acid solution is minus 10 °C, and a 21.3% solution is minus 60 °C.

Concentrated hydrochloric acid smokes in the air and forms a fog that irritates the upper respiratory tract and the mucous membrane of the eyes. Dilute 3 - 7% hydrochloric acid does not smoke. The maximum permissible concentration (MPC) of acid vapor in the working area is 5 mg/m 3 .

Exposure of the skin to hydrochloric acid can cause severe chemical burns. If hydrochloric acid gets on the skin or in the eyes, it must be immediately washed off with plenty of water, then the affected area of ​​the skin should be treated with a 10% solution of sodium bicarbonate, and the eyes with a 2% solution of sodium bicarbonate and go to a medical center.

Personal protective equipment: coarse wool suit or cotton suit with acid-resistant impregnation, rubber boots, acid-resistant rubber gloves, safety glasses.

Inhibited hydrochloric acid is transported in non-gummed steel railway tanks, tank trucks, and containers. Tanks for long-term storage of inhibited hydrochloric acid must be lined with diabase tiles on acid-resistant silicate putty. The shelf life of inhibited hydrochloric acid in iron containers is no more than one month, after which additional administration of the inhibitor is required.

2. Sulfuric acid

Technical concentrated sulfuric acid has a density of 1.84 g/cm3 and contains about 98% H 2 SO 4 ; It mixes with water in any proportions, releasing a large amount of heat.

When sulfuric acid is heated, sulfuric anhydride vapor is formed, which, when combined with water vapor in the air, forms acid fog.

Sulfuric acid upon contact with the skin causes severe burns, which are very painful and difficult to treat. When inhaling sulfuric acid vapors, the mucous membranes of the upper respiratory tract are irritated and cauterized. Contact of sulfuric acid in the eyes can result in loss of vision.

Personal protective equipment and first aid measures are the same as when working with hydrochloric acid.

Sulfuric acid is transported in steel rail tanks or road tankers and stored in steel containers.

3. Caustic soda

Caustic soda is a white, very hygroscopic substance, highly soluble in water (1070 g/l dissolves at a temperature of 20 °C). Freezing point of a 6.0% solution minus 5° C, 41.8% - 0 °C. Both solid caustic soda and its concentrated solutions cause severe burns. Contact of alkali in the eyes can lead to severe eye diseases and even loss of vision.

If alkali gets on the skin, it is necessary to remove it with dry cotton wool or pieces of cloth and wash the affected area with a 3% solution of acetic acid or a 2% solution of boric acid. If alkali gets into your eyes, rinse them thoroughly with a stream of water, followed by treatment with a 2% solution of boric acid and go to a medical center.

Personal protective equipment: cotton suit, safety glasses, rubberized apron, rubber gloves, rubber boots.

Caustic soda in solid crystalline form is transported and stored in steel drums. Liquid alkali (40%) is transported and stored in steel containers.

4. Concentrate and condensate of low molecular weight acids

Purified NMK condensate is a light yellow liquid with the odor of acetic acid and its homologues and contains at least 65% C 1 - C 4 acids (formic, acetic, propionic, butyric). In water condensate these acids are contained in the range of 15 ÷ 30%.

Purified NMK concentrate is a flammable product with a self-ignition temperature of 425 °C. To extinguish a fire, foam and acid fire extinguishers, sand, and felt should be used.

NMK vapors cause irritation to the mucous membrane of the eyes and respiratory tract. The maximum permissible concentration for vapors of purified NMK concentrate in the working area is 5 mg/m 3 (in terms of acetic acid).

If NMK concentrate and its diluted solutions come into contact with the skin, they cause burns. Personal protective equipment and first aid measures are the same as when working with hydrochloric acid; in addition, a gas mask of grade A should be used.

Uninhibited purified NMK concentrate is supplied in railway tanks and steel barrels with a capacity of 200 to 400 liters, made of high-alloy steels 12Х18Н10Т, 12Х21Н5Т, 08Х22Н6Т or bimetals (St3 + 12Х18Н10Т, St3 + Х17Н13М2Т), and is stored in from the same steel or in containers , made of carbon steel and lined with tiles.

5. Urotropin

Hexamine in its pure form is colorless hygroscopic crystals. The technical product is a white powder, highly soluble in water (31% at a temperature of 12° WITH). Highly flammable. In a solution of hydrochloric acid, it gradually decomposes into ammonium chloride and formaldehyde. The dehydrated pure product is sometimes referred to as dry alcohol. When working with methenamine, strict compliance with fire safety regulations is necessary.

If it comes into contact with the skin, methenamine can cause eczema with severe itching, which quickly disappears after stopping work. Personal protective equipment: safety glasses, rubber gloves.

Hexamine is supplied in paper bags. Must be stored in a dry place.

6. Wetting agents OP-7 and OP-10

They are neutral oily liquids of yellow color, highly soluble in water; When shaken with water, they form a stable foam.

If OP-7 or OP-10 gets on the skin, they must be washed off with a stream of water. Personal protective equipment: safety glasses, rubber gloves, rubberized apron.

Supplied in steel barrels and can be stored outdoors.

7. Captax

Captax is a yellow, bitter powder with an unpleasant odor, practically insoluble in water. Dissolves in alcohol, acetone and alkalis. It is most convenient to dissolve captax in OP-7 or OP-10.

Long-term exposure to captax dust causes headaches, poor sleep, and a bitter feeling in the mouth. Contact with skin can cause dermatitis. Personal protective equipment: respirator, safety glasses, rubberized apron, rubber gloves or silicone protective cream. At the end of work, you must thoroughly wash your hands and body, rinse your mouth, and shake out your overalls.

Captax is supplied in rubber bags with paper and polyethylene liners. Stored in a dry, well-ventilated area.

8. Sulfamic acid

Sulfamic acid is a white crystalline powder, highly soluble in water. When sulfamic acid is dissolved at a temperature of 80 °C and above, it hydrolyzes with the formation of sulfuric acid and the release of a large amount of heat.

Personal protective equipment and first aid measures are the same as when working with hydrochloric acid.

9. Sodium silicate

Sodium silicate is a colorless liquid with strong alkaline properties; contains 31 - 32% SiO 2 and 11 - 12% Na 2 O ; density 1.45 g/cm3. Sometimes called liquid glass.

Personal protective equipment and first aid measures are the same as when working with caustic soda.

It is received and stored in steel containers. In an acidic environment it forms a silicic acid gel.



The boiler is flushed when the device stops functioning normally. At the same time, most users turn to specialists who, for money, will clean the boilers and make all the necessary adjustments. But few people think that they can cope with this task on their own. But in vain.

Time to clean the boiler

Cleaning is done in three cases:

1. For prevention. This type of boiler cleaning is carried out by the home owner once or twice a year. In this case, a minimum of money and effort is spent.
2. When the heat exchanger is contaminated with scale or soot, its efficiency will be reduced. In this case, you can fix the problem yourself or call a technician.
3. The heat generator has broken down. He just stops. In this case, you cannot do without a specialist. He gets the system working and flushes it.

Boiler flushing options

There are only three ways to flush a gas boiler for repair purposes:

• mechanical;
• hydraulic;
• complex.

The second and third methods are the most effective. If preventive or regular cleaning of the boiler can be done with your own hands, then it is better to entrust repairs to professionals.

The mechanical method involves using physical force and tools to remove scale from boilers. These can be scrapers or brushes, as well as modern spreading heads with various types of drive. Tools must be selected correctly and used with care. If the walls of the boiler are damaged, this will lead to increased corrosion, and then to rapid failure of the entire system. The least dangerous for the device is flushing using hydraulics. Pressurized water removes scale from all parts of the boiler.

With the complex option, boilers are washed using water pressure using tools. Most often this happens if there is too much contamination in some part of the device.

What is a heat exchanger

A gas boiler has an element in its design that is located above the firebox and consists of connected tubes. The coolant circulates in them. Its location is not accidental; combustion of gas in the boiler must heat the coolant, which is located in the heat exchanger.

The coolant is water. It heats up and passes further through the system. But untreated water contains many impurities that can settle in the tubes when heated. Most often these are salts and lime particles. When large, it is difficult to pass through the tubes, which leads to malfunctions.

Time to clean the heat exchanger

There are many contradictions about when it is necessary to flush the heat exchanger of a gas boiler. There are signs that will tell you that it's time for cleaning. The most important of them:

• constantly switched on in the boiler;
• the circulation pump began to make noise, which indicates that it was overloaded;
• heating radiators take much longer to heat up;
• gas consumption has increased, although the boiler operating mode has not changed;
• the water pressure has weakened (pay attention to this sign when you need to flush a double-circuit boiler).

Procedure for flushing the heat exchanger with a booster

A booster is a special device for chemical cleaning. It allows the reagent solution to circulate autonomously in the heat exchanger.

1. The first step is to disconnect both pipes of the device from the heating system.
2. One of them is connected to the booster hose, through which the reagent will be supplied.
3. The second pipe is also connected to the booster hose, but with a different one. The spent solution will come out into it. It turns out that the system will close and circulation will occur, and without additional participation.
4. The spent solution will remain in the booster and must be drained. Rinse the heat exchanger with water.

It is better to clean with a booster several times, since the reagent gradually reduces its properties, and a new solution will increase the cleaning efficiency.

Methods for flushing the boiler and heat exchanger

Flushing the boiler is carried out to preserve the throughput of the apparatus and its thermal qualities.

Devices may differ in the type of heat exchanger and the quality of the water used; depending on this, they should be washed in different ways. There are three reliable and proven methods:

• chemical;
• mechanical;
• combined.

flushing the heat exchanger

Boilers are cleaned using reagents, mainly acids, and a special installation is required.

Using such an installation, the acid is dissolved to the desired consistency and heated. Temperature significantly affects the quality of washing. After preparing the solution, it is supplied to the heat exchanger and then removed.

Cleaning of heat exchangers occurs due to the presence and circulation of acid in it. Finish washing with plenty of water.

There is a possibility that the scale consists of various chemical components, so cleaning must be carried out using additional flushing of the boilers with other chemicals.

There are advantages to acid washing:

• there is no need to remove and disassemble the device, which significantly saves time;
• after such cleaning, the most common contaminants - hardness salts and magnesium hydroxide - will not remain in the heat exchanger.

There are also disadvantages:

• it is used for minor contamination;
• those contaminants that are formed due to corrosion cannot be removed by this method;
• safety measures are required, since the reagents are very toxic and dangerous;
• The solution after washing must be neutralized and disposed of.

Wash reagents

Manufacturers of various types of chemicals provide a choice of several options for means with which gas boilers are flushed.

Several parameters should be taken into account when choosing a particular product:

• pollution levels;
• the material from which the boiler and heat exchanger are made, their reaction to the purchased chemical.

The following substances are suitable for cleaning a home boiler:

• - its effectiveness in removing scale is very high;
• and adipic - effective for preventive cleaning and regular washing, with light contamination;
• - this product is used to eliminate very severe contamination;
• various gels - they need to be dissolved in water (the effectiveness is in no way inferior to previous products).

Chemical washing of boilers and heat exchangers is carried out only in compliance with special safety measures.

Mechanical method of washing the heat exchanger

The main difference from the chemical method is the disassembly of the entire heat exchanger.

After this, each of the parts is washed separately with a stream of water under high pressure. This method is used in very rare cases when the contamination is not amenable to other types of cleaning.

Advantages:

• effective for severe contamination, even corrosion products can be washed only with this method;
• the use of chemicals is excluded - this is an absolutely safe method;
• no need for additional disposal of the washing solution.

Flaws:

• The main disadvantage of mechanical flushing remains the disassembly of the entire unit. This is very difficult to do, and some devices do not even have disassembly instructions. In any case, it will require a lot of effort and a lot of time.
• In order for the water pressure to be strong enough, you need to use an additional device.
• The cost of mechanical flushing will significantly exceed chemical flushing due to high labor costs.

Second option of the mechanical method:

• The first step is to disconnect the boiler from the power supply.
• Disassemble it and carefully remove the heat exchanger.
• Immerse the element in a container with a low concentration acid solution for a period of 3 to 7 hours, depending on the degree of contamination.
• Rinse the heat exchanger under running water and install it in its original place.

Experts advise that when rinsing with water, tap the device a little to improve cleaning. The most effective method is to soak the parts when cleaning a double-circuit boiler.

Method of combined flushing of the heat exchanger

Serious and advanced contamination cannot be cleaned using only one method, so a combined method is used.

There may be several types of chemical contaminants in the heat exchanger, as well as corrosion products. When washing using any of the methods, you can add special balls to the solution, which will create additional pressure and be able to remove scale from the walls of the device.

Conclusion

Washing boilers and cleaning them from soot is possible without outside help. But it’s a completely different matter with flushing the heat exchanger. Here you will need confidence in success - if you don’t have it, then you can call a specialist for the first time. At the same time, carefully monitor its actions so that when cleaning it again, you can be sure that you can handle it yourself.