How to correctly select the type of the hottest dr

How to select the correct type of drain valve

I. summary:

the steam trap plays a role of steam blocking and drainage in the steam heating system. Selecting a suitable steam trap can make the steam heating equipment achieve the highest working efficiency. In order to achieve the best effect, it is necessary to have a comprehensive understanding of the working performance and characteristics of various types of steam traps

II. Type selection of steam trap:

1. When selecting steam trap, its characteristics should first be selected to meet the best operation of steam heating equipment, and then other objective conditions should be considered. In this way, the selection of the steam trap you need is correct and effective

2. The steam trap should be able to "identify" steam and condensate in order to play the role of steam blocking and drainage. "Identifying" steam and condensate is based on three principles: density difference, temperature difference and phase change. Therefore, three types of traps are manufactured according to three principles: mechanical type, thermal static type and thermal dynamic type

3. There are many kinds of traps with different performances and application ranges. A detailed understanding of the characteristics, working principles and selection methods of different types of traps can help you choose the best and most suitable traps

III. characteristics, working principle and type selection method of different types of steam traps:

there are many kinds of steam traps with different performance and scope of application:

(I) Mechanical drain valve:

mechanical type, also known as float type, uses the density difference between condensate and steam to make the float rise and fall to drive the valve disc to open or close through the change of condensate level, so as to achieve the purpose of steam blocking and drainage. The supercooling degree of the mechanical drain valve is small, and it is not affected by the working pressure. 2. The main body of the universal material testing machine and the dynamometer do not need to be specially affected by the basic force and temperature changes during the installation. When there is water, it is discharged immediately, and there is no water in the heating equipment, which can make the heating equipment achieve the best heat exchange efficiency. The maximum back pressure rate is 80%, and the work quality is high. It is the most ideal drain valve for production process heating equipment

mechanical traps include free floating ball type, free semi floating ball type, lever floating ball type, inverted bucket type, etc

1. Free floating ball drain valve:

the structure of free floating ball drain valve is simple. There is only a stainless steel hollow floating ball with fine grinding of moving parts inside. It is both a float and a hoist, without vulnerable parts, and has a long service life. The "YQ brand" drain valve is equipped with Y Series automatic air exhaust device inside, which is very sensitive, can automatically exhaust air, and has high work quality. When the equipment is just started, the air in the pipeline is discharged through the Y Series automatic air exhaust device, the low-temperature condensate enters the drain valve, the liquid level of condensate rises, the floating ball rises, the valve is opened, the condensate is discharged quickly, the steam enters the equipment quickly, the equipment heats up rapidly, the temperature sensing liquid of the Y Series automatic air exhaust device expands, and the automatic air exhaust device is closed. The steam trap starts to work normally, and the floating ball rises and falls with the condensate level, blocking steam and draining water. The valve seat of the free floating ball trap is always below the liquid level, forming a water seal, no steam leakage, and good energy-saving effect. The minimum working pressure is 0.01Mpa, and the range from 0.01Mpa to the maximum working pressure is not affected by the fluctuation of temperature and working pressure, and the water is drained continuously. It can discharge condensate at saturated temperature, with a minimum undercooling of 0 ℃, and there is no water in the heating equipment, so that the heating equipment can achieve the best heat exchange efficiency. The back pressure rate is greater than 85% - it is one of the most ideal traps for production process heating equipment

2. Free semi floating ball drain valve:

from 5 Rules of reference conditions: there are usually two kinds of reference conditions: ① standard reference conditions; ② The reference condition of the experiment is that there is only one semi floating ball barrel as the movable part of the semi floating ball trap, with the opening facing down, and the barrel is both a hoist and a seal. The whole spherical surface can be sealed, with long service life, resistance to water hammer, no wearing parts, no fault - durable, no steam leakage. The back pressure rate is greater than 80%, which can discharge condensate at saturated temperature. The minimum undercooling is 0 ℃, and there is no water in the heating equipment, which can make the heating equipment achieve the best heat exchange efficiency. When the device is just started, the air and low-temperature condensate in the pipeline enter the drain valve through the launching pipe. The bimetallic sheet emptying element in the valve pops the ball barrel open, the valve opens, and the air and low-temperature condensate are discharged quickly. When the steam enters the ball barrel, the ball barrel generates upward buoyancy. At the same time, the temperature in the valve rises, the bimetallic sheet emptying element shrinks, the ball barrel floats to the valve port, and the valve closes. When the steam in the drum turns into condensate, the drum loses its buoyancy and sinks down. The valve is opened and the condensate is discharged quickly. When the steam enters the ball barrel again, the valve will be closed again and work intermittently and continuously

3. Rod floating ball trap:

the basic characteristics of lever floating ball trap are the same as that of free floating ball trap. The internal structure is that the floating ball is connected with the lever to drive the valve core, and the valve is opened and closed with the rise and fall of condensate level. The lever floating ball drain valve uses double seats to increase the condensate discharge, which can achieve small volume, large discharge, and the maximum drainage capacity of 100 tons/hour - it is the most ideal drain valve for large heating equipment

4. Inverted bucket drain valve:

inside the inverted bucket drain valve is an inverted bucket, which is a liquid level sensitive part. The opening of the bucket is downward, and the connecting lever of the inverted bucket drives the valve core to open and close the valve. The inverted bucket drain valve can exhaust air, is not afraid of water hammer, and has good anti fouling performance. The undercooling is small, the steam leakage rate is less than 3%, and the maximum back pressure rate is 75%. There are many connectors, and the sensitivity is not as good as that of the free floating ball trap. Because the inverted bucket drain valve is closed by the upward buoyancy of steam, (it is not suitable for selection when the working pressure difference is less than 0.1MPa). When the device is just started, the air and low-temperature condensate in the pipeline enter the drain valve, and the inverted bucket falls by its own weight. The connecting lever of the inverted bucket drives the valve core to open the valve, and the air and low-temperature condensate are discharged quickly. When the steam enters the inverted bucket, the steam of the inverted bucket generates upward buoyancy, and the inverted bucket rises and the connecting lever drives the valve core to close the valve. There is a small hole on the inverted bucket. When part of the steam is discharged from the hole, and the other part of the steam produces condensate, the inverted bucket loses its buoyancy and sinks by its own weight. The inverted bucket is connected with a lever to drive the valve core to open the valve, which works circularly and discharges water intermittently

5. Combined superheated steam trap:

the combined superheated steam trap has two isolated valve chambers, and the upper and lower valve chambers are connected by two stainless steel pipes. It is a combination of floating ball type and inverted bucket type trap. The structure of the valve is advanced and reasonable. Under the working conditions of overheating, high pressure and small load, it can timely discharge the condensate formed when the superheated steam disappears, effectively prevent the leakage of superheated steam, and the working quality is high. The maximum allowable temperature is 600 ℃, the valve body is all stainless steel, and the valve seat is hard alloy steel - (long service life, special steam trap for superheated steam) has obtained two national patents, filling the domestic gap. When the condensate enters the lower valve chamber, the floating ball of the auxiliary valve rises with the liquid level, and the floating ball closes the steam inlet pipe hole. The condensed water rises to the main valve chamber through the water inlet pipe, and the inverted bucket falls by its own weight, driving the valve core to open the main valve and discharge the condensed water. When the condensate level in the auxiliary valve chamber drops, the floating ball drops with the liquid level and the auxiliary valve opens. The steam enters the inverted bucket in the upper main valve cavity from the steam inlet pipe. The inverted bucket generates upward buoyancy, and the inverted bucket drives the valve core to close the main valve. When the condensate level in the auxiliary valve chamber rises again, the next cycle starts again, with intermittent drainage

(II) Thermal static steam trap:

this kind of steam trap uses the temperature difference between steam and condensate to cause the deformation or expansion of temperature sensing elements to drive the valve core to open and close the valve. The undercooling degree of the thermal static steam trap is relatively large, and the general undercooling degree is 15 degrees to 40 degrees. It can use a part of the sensible heat in the condensate. There is always high-temperature condensate in front of the valve, without steam leakage, and the energy-saving effect is remarkable - it is the most ideal steam trap in steam pipelines, heat tracing pipelines, and small heating equipment (heating equipment, small heating equipment with low temperature requirements)

the thermostatic steam traps are diaphragm type, bellows type and bimetal plate type

1 Diaphragm trap:

the main action element of the diaphragm trap is the metal diaphragm, which is filled with a liquid whose gasification temperature is lower than the saturation temperature of water. There are two options: the valve opening temperature is 15 ℃ and 30 ℃ lower than the saturation temperature. Diaphragm trap - particularly sensitive, not afraid of freezing, small size, heat resistance, can be installed at any position. The back pressure rate is greater than 80%, which can discharge non condensing gas, and the capsule is solid - (long service life, convenient maintenance, and wide range of use). When the device is just started, low-temperature condensate appears in the pipeline, the liquid in the capsule is in the condensed state, and the valve is in the open position. When the temperature of the condensed water gradually rises, the filling liquid in the diaphragm begins to evaporate, and the pressure in the diaphragm rises. The diaphragm drives the valve core to move towards the closing direction. Before the condensed water reaches the saturation temperature, the drain valve begins to close. The capsule controls the valve switch with the change of steam temperature, which plays the role of steam blocking and drainage

2. Bellows type drain valve:

the valve core of the bellows type drain valve is filled with a liquid whose vaporization temperature is lower than the water saturation temperature - the valve switch is controlled with the change of steam temperature, and the valve is equipped with adjusting bolts, (the service temperature can be adjusted according to needs. Generally, the adjustment range of supercooling is 15 ℃ -40 ℃ lower than the saturation temperature. The back pressure rate is greater than 70%, which is not afraid of freezing. It is small in size and can be installed at any position. It can discharge non condensing gas and has a long service life). When the device is started, cooling condensate appears in the pipeline, the liquid in the bellows is in the condensed state, and the valve core is in the open position under the spring force. When the temperature of condensate gradually rises, the filling liquid in the bellows begins to evaporate and expand, the internal pressure increases, and the deformation and elongation drive the valve core to move towards the closing direction. Before the condensate reaches the saturation temperature, the drain valve starts to close, and the valve switch is controlled with the change of steam temperature to block steam and drain water

3. Bimetallic sheet drain valve:

the main component of bimetallic sheet drain valve is bimetallic sheet temperature sensing element, which is heated and deformed with the rise and fall of steam temperature, and pushes the valve core to open and close the valve. Bimetallic chip drain valve - equipped with adjusting bolts, the service temperature can be adjusted according to needs. Generally, the adjustment range of supercooling is 15 ℃ -30 ℃ lower than the saturation temperature, and the back pressure rate is greater than 70%. It can discharge non condensing gas, is not afraid of freezing, is small in size, is resistant to water hammer and high pressure, and can be installed at any position. (the bimetallic sheet has fatigue and needs to be adjusted frequently). When the device is just started, low-temperature condensate appears in the pipeline, the bimetallic sheet is flat, the valve core is under the spring force, and the valve is in the open position. When the temperature of condensed water gradually rises, the bimetal temperature sensing element begins to bend and deform, and pushes the valve core to the closed position. Before the condensate reaches the saturation temperature, the drain valve starts to close. The bimetallic sheet controls the valve switch with the change of steam temperature to block steam and drain water

(III) Thermodynamic steam trap

according to the phase change principle, this kind of steam trap relies on the different thermodynamic principles of the flow rate and volume changes when steam and condensate pass through, so that different pressure differences are generated up and down the valve disc, and the valve disc switch 6 is driven to evaluate the result. Because the working power of the thermal steam trap comes from steam, the waste of steam is relatively large. It has simple structure, water hammer resistance, 50% maximum back, noise, frequent operation of valve plate and short service life