Steam is one of the most efficient coolants, which instantly transfers all thermal energy to the consumer upon contact with the heat transmitter. In addition, it is easy to give the gaseous phase the required characteristics - the required temperature and pressure. But during the interaction of steam and equipment, large number condensate, which leads to water hammer, a decrease in thermal power and a deterioration in the quality of the gaseous phase.
To combat water droplets falling on the surface of pipes, it is necessary to use steam trap. At foreign enterprises, such fittings are called “steam traps”, which fully reflects functional purpose device.
Steam traps
buy a condensate trap, which is one of the types of industrial pipeline fittings, which is designed to prevent condensate from falling out when using steam or more effective use its thermal energy. As a result of a series of experiments, it was proven that the introduction of a condensate trap into a complex of equipment saves up to 20% of the useful energy of live steam. Types of condensate drains Depending on the design and implemented operating principle, pipeline fittings may be mechanical, thermodynamic or thermostatic. Any type of steam condensate trap must meet two basic requirements: removal of condensate without loss of acute gaseous phase; automatic removal of air from the system. Condensation is formed due to heat loss by steam in heat exchangers, as well as during the heating of pipeline installations, when part of the gaseous phase turns into water. The loss of large amounts of moisture reduces the energy efficiency of equipment and accelerates its wear. That's why it's so important to fight it.
Mechanical steam traps
Mechanical fittings are the most reliable, and therefore popular, “steam trap”. Its operating principle is based on the difference in the densities of water vapor and condensate, and the main operating element is a float. Depending on the design of the float, the following types of fittings are distinguished: steam float trap, spherical, open or closed type; bell-type float element, or inverted closed steam trap. Each type of valve works according to its own specific scheme, has advantages and disadvantages, knowledge of which will allow you to implement the most effective scheme of work at the enterprise. Steam traps with spherical float The basis of the design of this type of fittings is a spherical float. It is located in the internal cavity of the exhaust valve and is connected to the lever valve. In addition, the condensate trap includes a thermostatic valve. The principle of operation of a steam condensate trap with a spherical float can be divided into two stages: Condensate enters the device through the pipe, fills the internal cavity and raises the float, which pulls the valve lever and opens a hole for removing water . When hot steam enters the device, the thermal valve is activated, steam begins to accumulate in the cavity and causes the float to sink to the bottom, and the outlet is blocked. This is how condensate is separated from steam. Due to the presence of a thermostatic valve in the design, automatic removal released gas, and also prevents the formation of an air film in the cavity, which jams the device.
Advantages and Disadvantages
A typical representative of fittings with a spherical float is the steam condensate trap FT-44. Let's look at the main pros and cons of the devices using its example. The main thing that experts note is the insensitivity of the device to variable loads. The device is capable of continuously removing condensate both at vapor saturation temperature and under heavy loads. Stable and continuous separation of non-condensable gases is another advantage of the valve. All this combined with for a long time service is due to the simple design of the device. The main disadvantage of the device is large sizes, which increases heat loss to non-insulated housing elements. High sensitivity to water hammer and demands on “steam purity” (possible silting of the valve) are two more disadvantages of condensate traps of this type. Bell Type Steam Traps As the name suggests, the main element of this type of steam trap is the bell, or inverted glass float. The device itself has cylindrical shape, quite bulky (more than the previous representative), but has a wide range of advantages. In the initial position, the inverted float is at the bottom of the valve and its bottom rests against the vertical tube. A spool lever is attached to the glass, which is located in the valve cover.
Condensate traps are used for draining steam lines, as well as for removing condensate from heat exchange devices.
Condensate traps are used to remove condensate that forms in a steam pipeline as a result of heat loss to the surrounding atmosphere. The use of thermal insulation partially solves the problem of heat losses, but does not completely eliminate them. Consequently, installation of condensate drainage units on various areas steam line is required.
It is preferable to install condensate drainage units no less than 30-50 m apart where the steam pipeline has horizontal sections. The condensate trap, which is installed first after the boiler, must be installed with a capacity of at least 20 percent of the capacity of the boiler itself. If the steam line is more than 1000 m long, the steam trap must have the same capacity as the boiler capacity. This is necessary to drain condensate in the event that boiler water is carried away.
Before all lifts, on manifolds and before control valves, the installation of a steam trap is essential.
Condensate is drained using settling tanks. The diameters of the pockets are equal to the diameter of the pipes up to the fiftieth diameter. If the diameter of the steam line exceeds 50mm, then pockets one or two diameters smaller are used. It is necessary to equip the sump pocket with a drain valve or plug at its lower part for cleaning or purging the system. As a rule, settling tanks are installed at some distance from the condensate drain to avoid clogging.
Condensate drain unit
To protect the condensate trap from contamination, you need to install a mesh filter in front of it, and to prevent the system from filling with condensate if the steam supply to the steam line is stopped, it is necessary to install a return filter after the condensate trap valve, and installed There are sight glasses on the pipeline, making it possible to control correct work systems.
Removing air
In order to reduce negative influence air, which reduces heat transfer in heat exchange devices, thermostatic condensate traps are installed on the steam pipeline, playing the role of automatic vents. They are installed directly near the heat exchange devices at the highest point of the system.
To prevent the formation of a vacuum in the system that occurs as a result of cooling the system when it is turned off, along with thermostatic condensate traps (“air vents”), vacuum breakers are installed. When the steam line is cooled, the steam condenses and the difference in the volumes of the emerging condensate and steam gives a rarefaction effect. Thus, installing a vacuum breaker becomes a necessity so that the seals of the equipment installed on the steam line are not damaged.
Reducing stations
In order to obtain steam at the required pressure, it is necessary to use pressure reducing valves. We offer you diaphragm and spring pressure reducing valves. Condensate drainage must be done before the pressure reducing valve in order to avoid water hammer.
Filters
If the pipelines are quite old, then there is a possibility that the steam supplied to the consumer is heavily contaminated, since average speed steam supply in the steam line is15-60 m/s, then at such speeds, the resulting dirt and scale from boilers can severely damage both the pipeline itself and the equipment installed on it. Control valves can especially suffer, since inside the valves, between the seat and the shut-off element, the steam speed can reach hundreds of meters per second. Therefore, it is simply necessary to install mesh filters in front of the control valves and, preferably, the cell size in the filter mesh is- 0.25 mm.
In steam systems, unlike water pipes, filters must be installed strictly with a mesh to the side, horizontally, to avoid the formation of another condensate pocket. In this case, condensate accumulating in the filter moistens the steam and there is a possibility of condensation plugs appearing.
Steam separators
To reduce the erosion resistance of pipeline fittings and the steam pipeline itself, steam separators are used. This is necessary in order to separate wet steam and a significant part of the dirt from dry steam, which are the causes of erosion. Since the condensate trap operates only on ready condensate, the use of steam separators that remove unnecessary suspended matter is strategically necessary. After separation, the consumer is supplied with high-quality, dry steam.
We present centrifugal separators for your consideration.
The centrifugal principle is based on the swirling of the steam-water mixture, which enters the separator through the inlet pipe.
Since the moisture particles in the steam have a denser structure and have mass, under the influence of centrifugal force they settle as a film on the side wall of the separator. After this film reaches the bumper at the top of the separator, it breaks off. Then, the water, once in the lower part of the steam separator, is discharged through a specially designed drainage hole. At the outlet pipe, dry steam is already obtained, free from water suspension. The separated water enters the condensate drainage unit, designed to avoid steam loss. In the upper part of the steam separator there is a technological hole for installing an automatic air vent. Separators should be installed in close proximity to the consumer, control valves and flow control devices. Guaranteed operating time of such separators. as a rule, longer operating time of the pipeline.
Safety valves
Our Company presents to your attention a spring safety valve with standard sizes from 10 to 400 mm.
We offer for consideration full-lift safety valves (PREGRAN 495/496) and proportional valves (Prescor Flamco, PREGRAN 095A/095C/095/096/097).
The valves presented may differ in the type of seals and their design.
The Prescor safety valve, due to the design of the diaphragm, has a high tightness along the stem.
In turn, the PREGRAN 095/097 valve is not sealed, since it has a metal/metal seal along the stem.
Choice safety valve should be based on taking into account the valve seals and its design features.
The main aspect of the requirements in relation to safety valves must be considered, in addition to the required valve response pressure, also the correct direction of discharge of the medium to be discharged.
The water safety valve must have a outlet from the outlet pipe to sewer system, that is, down. The steam safety valve must have an outlet at the outlet pipe upwards, to the roof of the building or to another place that is safe for people. In this regard, you need to know that after the valve is activated and steam is released, condensate is formed, which then accumulates in the outlet pipe at the valve outlet. As a result, additional pressure arises, which prevents the valve from subsequently operating and releasing steam at the planned relief pressure.
In other words, it must be taken into account that when the safety valve is set to an operation pressure of 0.5 MPa and the outlet pipeline directed upward is filled with water for ten meters, the relief pressure of the safety valve will be around 0.6 MPa. In this context, it should be understood that it is necessary to organize a drainage system for the outlet pipeline, otherwise, if the valve is not tightly sealed along the stem, water may rush through the cover.
Safety valve installation A
____________________________________________________________________________________________________________________
Shut-off valves
The fact that steam in the pipeline moves with high speed, must always be taken into account when choosing shut-off valves. Recommendations from European manufacturers for choosing the diameter of a steam pipeline may differ significantly from the recommendations Russian manufacturers. It is characteristic that when the pipeline fittings are closed, a condensate plug is formed in front of it. The danger of water hammer increases when the shut-off valves are opened. Therefore, it is completely risky to use it as a shut-off valve on a steam pipeline. ball valves. The best way out here is to use a saddle shut-off valve. The use of ball valves is sometimes justified by the fact that they do not require maintenance during operation. But this problem has long been solved, due to the fact that instead of saddle valves with stuffing box packing (type KV16 / KV40), which really requires service, it is possible to install shut-off valves with a bellows seal, which is much more durable.
A steel or cast iron bellows valve (KV45/234A), like a ball valve, is not maintained during operation, but despite the fact that it can open smoothly, it significantly reduces the likelihood of water hammer occurring. But there is technological processes, in which a sharp supply of steam is important. For such cases, you can consider ball valves BV16, BV17 or PEKOS ball valves type P0 (SSS). Well, of course, before the regulatory or shut-off valves will be installed, the pipeline must be blown and cleaned so that the working parts of the equipment are not damaged by slag or scale.
Control valves
Our Company invites you to familiarize yourself with a fairly large selection of control valves.
Control valves have a standardized connection, and thermostats can be installed on them (temperature regulator direct action), electric drives (this option can be supplied complete with a controller and sensors for weather-dependent and PID control) or pneumatic drives (it is possible to install pneumatic or electric pneumatic positioners, controllers, pneumatic cabinets). More detailed information ask our company engineers.
Steam is one of the most effective coolants, which instantly transfers all the thermal energy to the consumer upon contact with the heat transmitter. In addition, it is easy to give the gaseous phase the required characteristics - the required temperature and pressure.
But during the interaction of steam and equipment, a large amount of condensate is formed, which leads to water hammer, a decrease in thermal power and a deterioration in the quality of the gaseous phase. To combat water droplets falling on the surface of the pipes, it is necessary to use a steam condensate trap. At foreign enterprises, such fittings are called “steam traps,” which fully reflects the functional purpose of the device.
Steam traps
Condensate traps are one of the types of industrial pipeline fittings, which are designed to prevent condensate from falling out when using steam and more efficiently use its thermal energy.
As a result of a series of experiments, it was proven that the introduction of a condensate trap into a complex of equipment saves up to 20% of the useful energy of live steam.
Types of steam traps
Depending on the design and operating principle implemented, pipeline fittings can be mechanical, thermodynamic or thermostatic. Any type of steam trap must meet two basic requirements:
- removal of condensate without loss of acute gaseous phase;
- automatic removal of air from the system.
Condensation is formed due to heat loss by steam in heat exchangers, as well as during the heating of pipeline installations, when part of the gaseous phase turns into water. The loss of large amounts of moisture reduces the energy efficiency of equipment and accelerates its wear. That's why it's so important to fight it.
Mechanical steam traps
Mechanical fittings are the most reliable, and therefore popular, “steam trap”. Its operating principle is based on the difference in the densities of water vapor and condensate, and the main operating element is a float. Depending on the design of the float, the following types of fittings are distinguished:
- spherical float steam steam trap of open or closed type;
- bell-type float element, or inverted closed steam trap.
Each type of valve works according to its own specific scheme, has advantages and disadvantages, knowledge of which will allow you to implement the most effective scheme of work at the enterprise.
Spherical float steam traps
The basis of the design of this type of fittings is a spherical float. It is located in the internal cavity of the exhaust valve and is connected to the lever valve. In addition, the condensate trap includes
The operating principle of a ball float steam trap can be divided into two stages:
- Condensate enters the device through the pipe, fills the internal cavity and raises the float, which pulls the valve lever and opens a hole to remove water.
- When hot steam enters the device, the thermal valve is activated, steam begins to accumulate in the cavity and causes the float to sink to the bottom, and the outlet is blocked.
This is how condensate is separated from steam. Thanks to the presence of a thermostatic valve in the design, the released gas is automatically removed, and the appearance of an air film in the cavity, which jams the device, is also prevented.
Advantages and Disadvantages
A typical representative of fittings with a spherical float is the steam condensate trap FT-44. Let's look at the main pros and cons of the devices using its example. The main thing that experts note is the insensitivity of the device to variable loads.
The device is capable of continuously removing condensate both at vapor saturation temperatures and under heavy loads. Stable and continuous separation of non-condensable gases is another advantage of the valve. All this, combined with a long service life, is due to the simple design of the device.
The main disadvantage of the device is its large size, which increases heat loss to non-insulated housing elements. High sensitivity to water hammer and demands on “steam purity” (possible silting of the valve) are two more disadvantages of condensate traps of this type.
Bell type steam traps
As the name implies, the main element of this type of steam trap is the bell, or "inverted glass" float. The device itself has a cylindrical shape, is quite bulky (larger than the previous representative), but has a wide range of advantages.
In the initial position, the inverted float is at the bottom of the valve and its bottom rests against the vertical tube. A spool lever is attached to the glass, which is located in the valve cover. The separation of steam from condensate occurs in four steps:
- Through the inlet pipe, water enters the device, fills the internal cavity and, under pressure, pours out through the open spool.
- Steam entering the system begins to put pressure on the bottom of the float, causing it to float up in the condensate volume and close the spool.
- The steam, being inside the glass, begins to decompose into liquid and gaseous phases. The latter passes through a special channel in the bottom, enters the spool and moves it away.
- The condensate and the remaining gaseous phase leave the glass through the hole in the bottom, the float begins to release, reopening the spool.
By cyclically repeating the described operations, the live steam is completely and effectively separated from the condensate. This technology was patented in 1911, but remains relevant to this day.
Advantages and disadvantages
A prominent representative of the “inverted glass” type fittings is the Zamkon steam trap. Let's look at the pros and cons of devices in this category using its example.
Here, the large size is also considered a disadvantage, which significantly affects the loss of thermal energy on non-insulated elements. Experts call another disadvantage the limited throughput, which prevents the use of fittings on high-performance equipment.
The advantages of a condensate trap are much greater. Firstly, the spool is not subject to contamination, which increases the reliability of the device. Secondly, the fittings are not afraid of water hammer. Thirdly, condensate removal is possible even at high temperatures.
In the event of a failure, the outlet valve remains open, which saves the equipment complex from breakdown. Finally, all additional components and assemblies, such as filters or check valves, are installed directly into the steam trap body. This reduces thermal energy losses and reduces the dimensions of the whole set of devices.
"Thermal" fittings
Thermostatic and thermodynamic steam traps operate on the ability of various media to expand and contract as temperatures rise or fall. Along with an increase in temperature, for example, when steam enters, the shut-off element expands and blocks the channel that drains condensate.
The operating principle of other devices is based on changes in pressure inside the system as a result of the interaction of a dense (cold) and rarefied (hot) environment. The main elements in such devices are: In the photo, a steam condensate trap is shown with a bimetallic element.
This type of equipment has complex design and is rarely used in practice. Low popularity is also due to complex and often impossible repairs. Application of equipment of this type justified only in particularly critical industrial installations.
T. Gutsulyak, A. Kirilyuk
Due to the constant rise in price of energy resources, all industrial sectors are busy searching for alternative sources increasing energy efficiency. Water vapor, as a means of transferring thermal energy, is becoming increasingly popular
In addition to heat exchangers, condensate traps play an important role in the effective extraction of heat from steam. Their main task - extracting as much heat as possible from water vapor - is quite difficult and depends not only on the presence of the condensate traps themselves in the system, but also on how correctly they are selected. To select the correct steam trap for a specific production process, you need to know and understand well the principles of its operation and the specifics of using steam in this process.
Purpose of steam traps
The condensate trap must prevent the heat transfer coefficient from decreasing. The decrease occurs due to the formation of condensate at the steam consumer or in the steam pipeline. Task of this equipment- remove condensate, while preventing “flight” and release of steam.
Steam, losing the heat necessary for heat exchange processes, gives it to the walls of the pipeline, turning into condensate. If it is not diverted, the “quality” of the steam deteriorates, cavitation and water hammer occur. Best option when the steam trap is capable of removing condensate as well as air and other non-condensed gases.
There is no one-size-fits-all steam trap that is suitable for all applications and applications. All types of condensate traps differ in their operating principle, while having their own disadvantages and advantages. Always exists best solution for a specific application in a steam condensate system. The choice of steam trap depends on
temperature, pressure and amount of condensate formed.
Rice. 1. Main types:
a) - mechanical (float); b) - thermodynamic; c) - thermostatic
There are three fundamentally different types: mechanical, thermostatic and thermodynamic.
Operating principle mechanical based on the difference in density between steam and condensate. The valve is actuated by a ball float or an inverted glass float. Mechanical steam traps provide continuous removal of condensate at steam temperature, making this type of device well suited for heat exchangers with large heat exchange surfaces and intensive formation of large volumes of condensate.
Thermostatic steam traps determine the temperature difference between steam and condensate. Sensing element and actuator V in this case- thermostat. Before the condensate is removed, it must be cooled to a temperature below the dry saturated steam temperature.
Based on the operating principle thermodynamic steam trap lies the difference in the speed of passage of steam and condensate in the gap between the disk and the seat. When condensate passes through, due to the low speed, the disk rises and allows condensate to pass through. When steam enters the thermodynamic steam trap, the speed increases, leading to a drop static pressure, and the disc lowers onto the seat. The steam above the disk, thanks to larger area contact, holds the disc in closed position. As the steam condenses, the pressure above the disk drops, and the disk begins to rise again, allowing the condensate to pass through.
Table 1. Types of steam traps
Table 2. Comparison of steam traps and their types
Selecting a steam trap
For correct selection nominal diameter of the steam trap You must first determine the inlet pressure, see fig. 3.
If the steam trap is installed after a steam-consuming installation, the inlet pressure is 15% lower than the pressure at the inlet to the installation.
For an approximate calculation of back pressure, we assume that each meter of pipeline rise equals 0.11 bar of back pressure.
Pressure drop = Inlet pressure - Back pressure.
The amount of condensate can be calculated using technical documentation manufacturer of steam-consuming equipment, taking into account the safety factor for condensate consumption. On main steam lines, heat exchangers and similar equipment, reserve bandwidth you need to install 2.5 - 3 times more than calculated. In other cases, the reserve is 1.5 - 2 times greater.
After calculating the safety factor for condensate flow, the diameter of the condensate trap is selected according to the diagram
throughput (see Fig. 2), which is provided by the manufacturing plant.
Below, as an example, are the AYVAZ SK-51 throughput diagrams (data and recommendations provided by AYVAZ UKRAINE).
Rice. 2. Capacity diagram of SK-51 (1/2”-3/4”-1”)
Example of using a chart (see Fig. 2): the condensate flow rate for the condensate drain is set to 180 kg/hour.
The condensate is discharged from the heat exchanger at a pressure of 6 bar and a back pressure of 0.2 bar. Pressure drop 6 - 0.2 = 5.8 bar.
Condensate flow 180 x 3 = 540 kg/hour.
Safety factor: 3.
To drain 540 kg/hour of condensate at a drop of 5.8 bar, along the blue line in the diagram marked with the number 10 (the throughput in this case is 700 kg/hour), we select a condensate drain with a diameter of 1” (DN25). The number 10 indicates the size of the exhaust valve opening. As can be seen from the diagram (Fig. 2), condensate traps with a diameter of 1/2" and 3/4" cannot be selected in this case, because their condensate capacity is lower than required.
Use of flash steam energy
When heating water at constant pressure its temperature and heat content increases. This continues until the water boils. Having reached the boiling point, the temperature of the water does not change until the water completely turns into steam. And since it is necessary to make maximum use of the thermal energy of steam, steam traps are used, see Fig. 3.
Rice. 3. Use of condensate and flash steam for heat exchange
Condensate has the same temperature at a given pressure as steam. When the condensate after the steam trap enters the atmospheric pressure zone, it instantly boils and part of it evaporates, because the temperature of the condensate is higher than the boiling point of water at atmospheric pressure.
The steam that is formed when the condensate boils is called secondary boiling steam.
Those. This is steam that is formed as a result of condensate entering the atmosphere or environment with low pressure and temperature.
Calculation of the amount of flash steam:
Where:
Ek
: Enthalpy of condensate entering the steam trap at a given pressure (kJ/kg).
Ev
: Enthalpy of condensate after the steam trap at atmospheric pressure or at the current pressure in the condensate line (kJ/kg).
St
: The latent heat of vaporization at atmospheric pressure or at the current pressure in the condensate line (kJ/kg) of the pipeline is 0.11 bar back pressure.
As you can see, than more difference pressure, the more flash steam is formed. The type of steam trap used also affects the amount of condensate produced. Mechanical ones remove condensate at a temperature close to the steam saturation temperature. While thermostatic ones remove condensate with a temperature significantly lower than the saturation temperature, while the amount of flash steam decreases.
When selecting flash steam, it is necessary to take into account that:
- To obtain even a small amount of flash steam, a large amount of condensate will be required. Need to pay special attention on the throughput of the condensate trap. You also need to take into account that after the control valves the pressure is usually low.
- The scope of application must correspond to that for the use of flash steam. The amount of flash steam should be equal to or slightly greater than that required to ensure the technical process.
- The area where flash steam is used should not be located far from the equipment from which high-temperature condensate is removed.
For an example of calculating the amount of flash steam in a system where condensate is removed immediately after its formation, see below.
Let's take data from the table of saturated steam: at a pressure of 8 bar, 170.5 ° C, condensate enthalpy = 720.94 kJ/kg. At atmospheric pressure, 100°C, enthalpy of condensate = 419.00 kJ/kg. The enthalpy difference is 301.94 kJ/kg. Latent heat of vaporization at atmospheric pressure = 2,258 kJ/kg. Then the amount of secondary boiling steam will be:
Thus, if the steam consumption in the system is 1000 kg, then the amount of flash steam will be 134 kg.
Features of installation of condensate traps
When installing a condensate drain, make sure that the arrow on its body corresponds to the direction of flow, see Fig. 4, a).
Float-type steam traps must be installed strictly horizontally. Some, in special versions, can be installed vertically. The steam inlet into such condensate traps should be on the bottom side, see Fig. 4, b).
Steam traps should be located below the steam line connection to the equipment. Otherwise, the equipment may flood. In cases where installing condensate drains in this way is impossible, it is necessary to organize forced drainage of condensate, see Fig. 4, c).
Thermodynamic steam traps work in any position. However, horizontal position more preferably during installation, see Fig. 4, d).
Rice. 4. Correct installation of the steam trap
Steam traps must not be installed one behind the other under any circumstances. Otherwise, the second one will create pressure, which will negatively affect the operation of the first one, which is already installed, see fig. 5, a).
Filters installed in front of steam traps must be facing left or right. Otherwise, condensation will accumulate at the bottom of the filter, which can lead to water hammer, see fig. 5, b).
Rice. 5. Installation of a condensate trap in the system
Correct selection and use of equipment from the manufacturer AYVAZ - effective way increase the level of energy saving in steam systems.
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Views: 3,440Ministry of Education of the Russian Federation
Moscow State Academy of Fine Chemical Technology named after. M. V. Lomonosova
"Processes and apparatuses
chemical technology"
V. M. N/yasoedenkov
SELECTION OF CONDENSATE TRAPS
Educational manual
Moscow, 2000
www.mitht.ru/e-library
Reviewer Alekseev P.G.
Myasoedenkov V.M. Selection of CondeHcaTO~OB. -
M.: MITHT. 2000, 23 p.
Methodological instructions for the selection of condensate traps are a necessary addition to the methodological instructions
pits on calculation and design of various technological
installations using water heating steam as a coolant.
The instructions contain the necessary information about the design and operating principle of condensate traps, discharge.
our industry. Methodology for selecting condensate drains
kov allows you to correctly select the device type and its number.
The instructions are intended for 4th year students of all ages
cialities.
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INTRODUCTION
To remove condensate generated during heat operation exchangers, depending on the steam pressure, approx.
yay various types devices.
With an inlet pressure of at least 0.1 MPa (1 Krc/cr.i) and about
at a pressure of no more than 50% of the inlet pressure, stable operation
Thermodynamic steam traps melt. (Here and in
next we're talking about about excess steam pressure).
With an initial pressure of at least 0.06 MPa, I recommend
It is possible to install condensate drains with float couplings
high, which operate reliably at a pressure drop of more than 0.05 MPa under constant and variable flow conditions
At Ar from 0.03 to 1.3 MPa for automatic removal
condensate from various steam receivers suitable for condensation
tion pots with open float.
At steam pressure up to 0,03 MPa for condensate drainage hydraulic valves (loops) can be used.
1. CONDENSATE TRAPS
THERMODYNAMIC
Thermodynamic steam traps are used
for removal of unsupercooled condensate.
The operating principle of the condensate trap is next. When condensate arrives, the plate (Fig. 1) is under
by the action of working pressure it is pressed away from the seat, opening
passage of condensate through the annular chamber of the housing to the outlet
mu hole. When steam enters the condensate trap in
the gaps between the plate and the saddle steam flows at a higher speed,
rather than condensate. There is a decrease in statistical pressure leniya under the plate. The plate is pressed against the seat under the influence of the pressure difference, leaving a slight gap. Part of the steam enters the chamber above the plate through the gap. Due to the difference active forces(difference between the areas of the plate and the inlet hole) the plate is pressed tightly against the seat and
stops the passage of steam.
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Currently, the domestic industry produces 5 models of thermodynamic condensate traps.
The basic model is the thermodi steam trap
Namic coupling CHU"Unny 45ch12nzh (first two digits
indicate the type of fittings; the letters behind it indicate the material of the case;
numbers after letters - design features of the product in
within the limits of this type and type of drive; the last letters indicate
depending on the material of the sealing surface). Condensate drain chik 45ch12nzh is designed for automatic removal of water vapor condensate from steam receivers at operating temperatures up to
200 OS.
The 45ch15nzh condensate trap differs from the basic one in presence of a special device- bypass - for forced
th opening and purging of the system.
Condensate drains with welded connections, steel new 45s13nzh and 45nzh13nzh are intended for automatic
removal of steam condensate operating temperature up to 300
wasps from steam receivers.
Condensate trap Uffucerno - end steel
45s16nzh is designed for automatic condensate drainage
Rice. 1. Diagram of a thermodynamic condensate trap coupling Chu "Unnogo 45ch12nzh: 1 - body; 2 - lining; 3 - saddle; 4 - plate; 5 - lid.
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water vapor with operating temperature up to 250 °C.
Thermodynamic condensate drain nozzle - torus
The steel end cap 45s22nzh is designed to remove water vapor condensate with an operating temperature of up to 250 °C.
Within the framework of this work, the first two
steam trap models.
Thermodynamic steam trap selection diagram
where Gmax.calc. is the maximum calculated steam consumption, t/h.
2. The steam pressure in front of the condensate drain is estimated com R1. If the steam trap is installed in a non-
mediocre proximity to the heat-consuming appliance
rata, then
if condensate is squeezed out (for example: condensate flows from the heating chamber of the first housing into the heating chamber of the second housing).
When condensate drains freely, the pressure at the outlet
4. The conditional capacity KV is calculated y in
KVy = A.JAP |
where AP is the pressure drop across the condensate trap, kgf/cm2;
G - estimated amount of condensate, t/h;
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A-coefficient, which takes into account the temperature of the condensate and the pressure drop across the condensate trap (Fig. 2).
"- "" r--...
0,5 (5) | ||||
1.5 (15) dP, MPa (кrclCM2) |
||||
Rice. 2. Dependence of coefficient A on pressure drop across
steam trap for condensate temperature,
5 or 1 °C lower than the steam saturation temperature: tK - condensate temperature, °C;
tM - steam saturation temperature, OS.
5. According to the corresponding table, select a specific con
steam trap depending on the value found
conditional throughput.
SELECT a condensate drain for the 1st body of the 3-body
evaporation plant. If the heating steam consumption is
1500 kg/h, and its pressure is 5 ata. Condensate drain installed
is located in close proximity to the evaporator.
The pressure in the pipeline after the condensate trap is
It is 50% of the steam pressure after BblhapHoro apparatus.
The estimated amount of condensate after the evaporator
G = 1.2·5= 1.8t/h.
Steam pressure before the steam trap
~ = 0.95. 4= 3.88TN.
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Steam pressure after steam trap
P2 = 0.5. 3.8= 1.9ati.
Conditional Bandwidth
KV y = 1,~== 2.33 t/h.
According to the table 2 select thermodynamic condensate
driver depending on the conditional capacity. Nearest higher value throughput according to table.
2 is 2.5 t/h. The nominal diameter D y will be
veins 50 mm. Dimensions | steam trap are selected according to |
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table 1: L = 200 MM; | L 1 = 24mm: | N max= 103mm; | 60mm; |
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Do = 115MM. | ||||||||||||||||
Table 1 |
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Dimensions of thermodynamic steam trap | ||||||||||||||||
DIAMETER | Dimensions, mm | |||||||||||||||
passage Oh, | N tah | |||||||||||||||
Table 2 |
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Technical data of condensate trap 45ch12nzh | ||||||||||||||||
Diameter | Pressure, | Conditional | ||||||||||||||
checkpoint | ||||||||||||||||
passage Ov, | ||||||||||||||||
ity KVy, | ||||||||||||||||
R pr | t = 200os | |||||||||||||||
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Continuation
Table 3
Size... thermodynamic steam trap with contour 45ch16nzh (Fig. 3)
Diameter | Dimensions, mm | |||||||||||||
passage Oh, | N max | |||||||||||||