How does the water delivery valve work?

　The trap plays a role in steam blocking and drainage in the steam heating system. Choosing the appropriate trap can make the steam heating equipment achieve the highest working efficiency. In order to achieve the best results, it is necessary to have a comprehensive understanding of the working performance and characteristics of various types of traps. 　　There are many types of traps, each with different performance. When selecting a trap, you should first select its characteristics to meet the optimal operation of the steam heating equipment, and then consider other objective conditions. In this way, choosing the trap you need is correct and effective. 　　The trap must be able to "identify" steam and condensate in order to function as a steam barrier and drainer. “Identifying steam and condensate is based on three principles: Density differences, temperature differences and phase changes. Therefore, three types of traps were manufactured based on three principles, classified into mechanical type, thermostatic type, and thermodynamic type. 　　1. Mechanical type trap, also called float type, uses the density difference between condensation water and steam to cause the float to rise and fall to drive the valve disc to open or close through changes in the condensation water level to achieve the purpose of steam blocking and drainage. Mechanical traps have a small degree of subcooling and are not affected by changes in working pressure and temperature. Water is discharged immediately and no water is stored in the heating equipment, allowing the heating equipment to achieve optimal heat exchange efficiency. The maximum back pressure rate is 80% and the working quality is high. It is the most ideal trap for production process heating equipment. 　　Mechanical traps include free float type, free semi-float type, lever float type, inverted bucket type, etc. 1. Free float type trap: 　　The structure of the free float type trap is simple. There is only one moving part inside, a finely ground stainless steel hollow float, which is both a float and an opening and closing part. It has no wearing parts and has a long service life. The "Yinqiu" brand trap has a Y series automatic air exhaust device inside, which is very sensitive, can automatically exhaust air, and has high working quality. 　　When the equipment first starts working, the air in the pipeline is discharged through the Y series automatic air exhaust device, low-temperature condensate water enters the trap, the liquid level of the condensate rises, the float rises, the valve opens, the condensate water is quickly discharged, steam quickly enters the equipment, the equipment heats up rapidly, the temperature-sensing liquid of the Y series automatic air exhaust device expands, and the automatic air exhaust device closes. The trap begins to work normally, and the float rises and falls with the condensate level, blocking steam and draining water. The valve seat of the free float type 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 it is not affected by fluctuations in temperature and working pressure within the range from 0.01Mpa to the maximum working pressure, and is continuously drained. It can drain condensation water at saturated temperature, and the minimum subcooling degree is 0℃. There is no water in the heating equipment, so the heating equipment can achieve the best heat exchange efficiency. With a back pressure rate greater than 85%, it is one of the most ideal traps for production process heating equipment. 　　2. Free semi-floating ball trap: 　　The free semi-float type trap has only one semi-float type ball barrel as a movable part, with the opening facing downwards. The ball barrel is both an opening and closing part and a sealing part. The entire spherical surface can be sealed, has a long service life, can resist water hammer, has no wearing parts, is trouble-free, durable and has no steam leakage. The back pressure rate is greater than 80%, and it can discharge condensation water at saturated temperature. The minimum subcooling degree is 0°C. There is no water in the heating equipment, so the heating equipment can achieve the best heat exchange efficiency. 　　When the device is just started, the air and low-temperature condensate in the pipeline enter the trap through the launch tube. The bimetallic emptying element in the valve pops open the ball barrel, the valve opens, and the air and low-temperature condensate are quickly discharged. When steam enters the ball barrel, the ball barrel generates upward buoyancy. At the same time, the temperature inside the valve increases, the bimetallic emptying element contracts, the ball barrel floats toward the valve port, and the valve closes. When the steam in the ball barrel turns into condensation water, the ball barrel loses buoyancy and sinks, the valve opens, and the condensation water is quickly discharged. When the steam enters the ball barrel again, the valve closes again, working intermittently and continuously. 　　3. Lever float trap: 　　The basic characteristics of the lever float type trap are the same as those of the free float type. The internal structure is that the float is connected to the lever to drive the valve core, and the valve is opened and closed as the condensate level rises and falls. The lever float type trap uses double valve seats to increase the condensate displacement, which can achieve a small volume and a large displacement, with a maximum drainage capacity of 100 tons/hour. It is the most ideal trap for large heating equipment. 　　4. Inverted bucket trap: 　　The inside of the inverted bucket trap is an inverted bucket that is a liquid level sensitive part. The bucket opens downward, and the connecting lever of the inverted bucket drives the valve core to open and close the valve. The inverted bucket trap can discharge air, is not afraid of water hammer, and has good anti-fouling performance. The degree of subcooling is small, the steam leakage rate is less than 3%, the maximum back pressure rate is 75%, there are many connecting parts, and the sensitivity is not as good as the free float trap. Since the inverted bucket trap relies on the upward buoyancy of steam to close the valve, it is not suitable for use 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 trap. The inverted bucket falls by its own weight. The lever connected to the inverted bucket drives the valve core to open the valve, and the air and low-temperature condensate are quickly discharged. When the steam enters the inverted bucket, the steam in the inverted bucket generates upward buoyancy, and the connecting lever of the inverted bucket rises to drive the valve core to close the valve. There is a small hole in the inverted bucket. When part of the steam is discharged from the small hole, and the other part of the steam generates condensation water, the inverted bucket loses its buoyancy and sinks under its own weight. The lever connected to the inverted bucket drives the valve core to open the valve, working in a cycle, and intermittent drainage. 　　5. Combined superheated steam trap: 　　The combined superheated steam trap has two isolated valve chambers. The upper and lower valve chambers are connected by two stainless steel pipes. It is a combination of a float type and an inverted bucket type trap. The valve has an advanced and reasonable structure. Under the working conditions of overheating, high pressure and small load, it can promptly discharge the condensate formed when the superheated steam disappears, effectively prevent the leakage of superheated steam, and has high working quality. The maximum allowable temperature is 600°C. The valve body is made of all stainless steel and the valve seat is made of hard alloy steel. It has a long service life. It is a special trap for superheated steam and has won two awards. * * The patent has filled the domestic gap. 　　When condensate enters the lower valve cavity, the float ball of the auxiliary valve rises with the liquid level, and the float seals the steam inlet pipe hole. The condensate water rises to the main valve cavity 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 condensate water. When the condensate level in the auxiliary valve cavity drops, the float ball drops with the liquid level and the auxiliary valve opens. Steam enters the inverted bucket in the upper main valve chamber 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 cavity rises again, the next cycle starts again with intermittent drainage. 　　2. Thermostatic type traps This type of trap uses the temperature difference between steam and condensed water to cause the deformation or expansion of the temperature-sensing element to drive the valve core to open and close the valve. The thermostatic trap has a relatively large degree of subcooling, generally ranging from 15 degrees to 40 degrees. It can utilize part of the sensible heat in the condensation water. There is always high-temperature condensation water in front of the valve. There is no steam leakage, and the energy saving effect is significant. It is the most ideal trap for steam pipes, heat tracing pipelines, small heating equipment, heating equipment, and small heating equipment with low temperature requirements. Thermostatic traps include diaphragm type, bellows type, and bimetallic sheet type 1. Diaphragm type traps: 　　The main operating element of the diaphragm trap is a metal diaphragm. The diaphragm is filled with a liquid whose vaporization temperature is lower than the saturation temperature of water. The valve opening temperature is 15°C or 30°C lower than the saturation temperature. The membrane box type trap is particularly responsive, not afraid of freezing, small in size, resistant to overheating, and can be installed in any position. The back pressure rate is greater than 80%, and it can discharge non-condensable gas. The membrane box is strong, has a long service life, is easy to maintain, and has a wide range of uses. 　　When the device is first started, low-temperature condensation water appears in the pipeline, the liquid in the membrane box is in a condensation state, and the valve is in the open position. When the temperature of the condensed water gradually increases, the liquid in the membrane box begins to evaporate, the pressure in the membrane box rises, and the diaphragm drives the valve core to move in the closing direction. Before the condensed water reaches the saturation temperature, the trap begins to close. The diaphragm box controls the opening and closing of the valve as the steam temperature changes, thereby blocking steam and draining water. 　　2. Bellows type drain valve: 　　The valve core of the bellows trap is a stainless steel bellows filled with a liquid whose vaporization temperature is lower than the water saturation temperature. The valve switch is controlled as the steam temperature changes. The valve is equipped with an adjustment bolt to adjust the operating temperature as needed. Generally, the subcooling adjustment range is 15°C-40°C lower than the saturation temperature. The back pressure rate is greater than 70%. It is not afraid of freezing. It is small in size and can be installed at any position. It can discharge non-condensable gas and has a long service life. 　　When the device is started, cooling condensate appears in the pipe, the liquid in the bellows is in a condensed state, and the valve core is in the open position under the elastic force of the spring. When the temperature of the condensate water gradually increases, the liquid in the bellows begins to evaporate and expand, the internal pressure increases, deforms and elongates, driving the valve core to move in the closing direction. Before the condensate water reaches the saturation temperature, the trap begins to close, and the valve switch is controlled with the change of steam temperature to block steam and drain water. 　　3. Bimetallic trap: 　　The main component of the bimetal trap is the bimetal temperature sensing element, which is heated and deformed as the steam temperature rises and falls, pushing the valve core to open and close the valve. Bimetallic traps are equipped with adjusting bolts, which can adjust the operating temperature as needed. Generally, the subcooling adjustment range is 15°C-30°C lower than the saturation temperature, and the back pressure rate is greater than 70%. It can discharge non-condensable gases, is not afraid of freezing, is small in size, can resist water hammer, and can withstand high pressure. It can be installed at any position. Bimetallic plates have fatigue properties and require frequent adjustments. 　　When the device is just started, low-temperature condensation water appears in the pipeline, the bimetallic sheet is flat, the valve core is in the open position under the elastic force of the spring. When the temperature of the condensate gradually rises, the bimetallic temperature sensing element begins to bend and deform, and pushes the valve core to the closed position. The trap begins to close before the condensate reaches saturation temperature. The bimetallic piece controls the opening and closing of the valve as the steam temperature changes, blocking steam and draining water. 　　3. Thermodynamic type traps This type of trap is based on the principle of phase change and the different thermodynamic principles of flow rate and volume changes when steam and condensate pass through, causing different pressure differences between the upper and lower parts of the valve plate to drive the valve plate to open and close the valve. Because the working power of the thermodynamic trap comes from steam, the waste of steam is relatively large. It has a simple structure, is resistant to water hammer, has a maximum backlash of 50%, is noisy, has frequent valve work, and has a short service life. 　　Thermodynamic steam traps include thermodynamic type (disc type), pulse type, orifice type 1. Thermodynamic steam trap: 　　There is a movable valve piece in the thermodynamic steam trap, which is both a sensitive part and an action actuator. According to the different thermodynamic principles of flow rate and volume changes when steam and condensate pass through, different pressure differences are generated up and down the valve plate, driving the valve plate to open and close the valve. The steam leakage rate is 3%, and the subcooling degree is 8℃-15℃. 　　When the device is started, cooling condensate appears in the pipeline, and the condensate is pushed open by the working pressure and discharged quickly. When the condensate water is discharged, the steam is subsequently discharged. Since the volume and flow rate of the steam are larger than the condensate water, a pressure difference is generated between the upper and lower parts of the valve plate, and the valve plate is quickly closed under the suction force of the steam flow rate. When the valve plate is closed, it is subject to pressure from both sides. The force-bearing area below the valve plate is smaller than the force-bearing area above. Since the pressure in the steam chamber of the trap comes from the steam pressure, the force on the upper surface of the valve plate is greater than the force below, and the valve plate is tightly closed. When the steam in the steam chamber of the trap cools down and turns into condensate, the pressure in the steam chamber disappears. The condensate water pushes open the valve plate by the working pressure, and the condensate water continues to be discharged, working in a cycle, and draining water intermittently. 　　2. Disc type steam heat preservation type trap: 　　The working principle of the disc steam insulated trap is the same as that of the thermodynamic trap. It adds a shell outside the steam chamber of the thermodynamic trap. The inner chamber of the shell is connected to the steam pipe, and the main steam chamber of the trap is insulated by the pipe's own steam. Make it difficult for the temperature of the main steam chamber to drop, maintain the steam pressure, and close the drain valve tightly. When condensation occurs in the pipeline, the trap shell cools down and the trap begins to drain water. ； If there is no condensate on the superheated steam pipeline, the trap will not open and the work quality will be high. The valve body is made of alloy steel and the valve core is made of carbide. The maximum allowable temperature of the valve is 550°C. It is durable and has a long service life. It is a special trap for high-pressure and high-temperature superheated steam. 　　3. Pulse trap: 　　The pulse trap has two orifice plates that adjust the valve opening and closing according to changes in steam pressure drop. Even if the valve is completely closed, the inlet and outlet are connected through the first and second small holes and are always in an incompletely closed state. The steam continues to overflow and the amount of steam leakage is large. This trap has a high operating frequency, severe wear, and short lifespan. It is small in size, resistant to water hammer, can discharge air and saturated temperature water, is close to continuous drainage, and has a maximum back pressure of 25%, so it has few users. 　　4. Orifice plate trap: 　　The orifice plate type drain valve selects orifice plates with different apertures according to different drainage volumes to achieve the purpose of controlling the drainage volume. The structure is simple, but improper selection may result in insufficient drainage or a large amount of steam leakage. It is not suitable for steam-using equipment with intermittent production or steam-using equipment with large fluctuations in condensate water volume.

The disc steam trap is based on the Bernoulli thermodynamic principle and utilizes the different thermodynamic characteristics of steam and condensate to cause dynamic and static pressure changes in kinetic energy and potential energy. The pressure difference between the upper and lower parts of the valve plate changes, and the valve plate is started to open and close, thereby achieving the purpose of steam blocking and drainage. There is a valve plate in this trap, which is both a sensitive part and an action actuator. When the device is started, cooling condensate appears in the pipeline, and the condensate is pushed open by the working pressure and discharged quickly. When the condensate water is discharged, steam enters the trap, and the volume of the steam expands rapidly. The flow rate of steam is greater than that of condensate water, causing a pressure difference between the upper and lower parts of the valve plate, and the valve plate is quickly closed under the suction force of the steam flow rate. When the valve plate is closed, it is subject to pressure from both sides. The force-bearing area below the valve plate is smaller than the force-bearing area above. Since the pressure in the steam chamber of the trap comes from the steam pressure, the force on the upper surface of the valve plate is greater than the force below, and the valve plate is tightly closed. When the steam in the steam chamber of the trap cools down and turns into condensate, the pressure in the steam chamber disappears. The condensate water pushes open the valve plate by the working pressure, and the condensate water continues to be discharged, working in a cycle, and draining water intermittently. The free semi-floating ball trap is one of the most reliable traps among mechanical traps. Its internal structure has only a semi-floating ball barrel as a movable part, with the opening facing downwards. The outer circle of the semi-floating ball barrel has been finely ground, and the entire spherical surface can be used as a sealing surface. It has a long service life, can resist water hammer, has no wearing parts, is trouble-free, is durable, has no steam leakage, and has good energy saving effect. This trap is widely used in steam heating equipment and steam pipe network condensate recovery systems. It is one of the most advanced traps in structure today. The free semi-float type trap has only one semi-float type ball barrel as a movable part, with the opening facing downwards. The ball barrel is both an opening and closing part and a sealing part. When the device is just started, the air and low-temperature condensate in the pipeline enter the trap through the launch tube. The bimetallic emptying element in the valve pops open the ball barrel, the valve opens, and the air and low-temperature condensate are quickly discharged. When steam enters the ball barrel, the ball barrel generates upward buoyancy. At the same time, the temperature inside the valve increases, the bimetallic emptying element shrinks, the ball floats toward the valve port, and the valve closes. When the steam in the ball barrel turns into condensation water, the ball barrel loses buoyancy and sinks, the valve opens, and the condensation water is quickly discharged. When the steam enters the ball barrel again, the valve closes again, working intermittently and continuously. Since the valve seat is in water-seal isolation, water vapor is separated, and there is no steam leakage during operation.