Thread Content
Thermostatic valves play a role in preventing steam from entering and draining water in steam heating systems; by selecting the appropriate thermostatic valve, steam heating equipment can achieve its highest efficiency. To achieve the most optimal results, it is necessary to have a comprehensive understanding of the operating performance and characteristics of various types of steam traps. There are many types of pressure relief valves, each with different properties. When selecting a steam trap, it is first necessary to ensure that its properties meet the requirements for optimal operation of steam heating equipment; only after that should other objective factors be considered. This approach ensures that the steam trap chosen is the right one and effective. For a steam trap to function by preventing steam from passing through while allowing water to drain, it must be able to “identify” steam from condensed water. “The detection of steam and condensate is based on three principles: density difference, temperature difference, and phase change. Thus, three types of steam traps were developed based on these three principles: mechanical, thermostatic, and thermodynamic. I. Mechanical type steam traps: The mechanical type, also known as the float type, takes advantage of the density difference between condensed water and steam. Changes in the level of condensed water cause the float to rise or fall, which in turn drives the valve disc to open or close, thereby achieving the purpose of preventing steam from passing while allowing water to flow out. Mechanical steam traps have a low degree of subcooling; they are not affected by changes in operating pressure and temperature. Water is discharged as soon as it appears, preventing water from remaining in the heating equipment, which allows the heating equipment to achieve optimal heat exchange efficiency. With a maximum back pressure ratio of 80% and high operating efficiency, it is the ideal steam trap for heating equipment in manufacturing processes. Mechanical steam traps come in various types such as the free-floating ball type, free semi-floating ball type, lever-ball type, and inverted bucket type. 1. Free-floating ball steam trap: This type of steam trap has a simple structure; it contains only one moving component – a finely ground stainless steel hollow ball that serves both as a float and as the valve element. There are no vulnerable parts, so its service life is very long. The “HG” steam traps are equipped with a Y-series automatic air release device, which is highly sensitive and capable of automatically releasing air, ensuring high performance. When the equipment starts operating, the air in the pipes is expelled through the Y-series automatic air exhaust devices. Low-temperature condensate enters the drain valve; as the level of this condensate rises, the float rises as well, causing the valve to open and the condensate to be discharged rapidly. Steam then enters the equipment quickly, resulting in a rapid rise in its temperature. The temperature-sensitive fluid in the Y-series automatic air exhaust devices expands, which causes these devices to shut off. The steam trap begins to function properly; the float rises and falls with the level of condensed water, thereby preventing steam from passing through while allowing water to drain. In a free-floating ball type steam trap, the valve seat is always below the liquid level, creating a water seal that prevents steam leakage and results in good energy-saving effects. The minimum operating pressure is 0.01 Mpa; continuous drainage is possible within the range from 0.01 Mpa up to the maximum operating pressure, without being affected by fluctuations in temperature or operating pressure. It can discharge saturated-temperature condensate water, with a minimum subcooling of 0°C; no water remains in the heating equipment, thereby enabling it to achieve optimal heat exchange efficiency. With a backpressure ratio of over 85%, it is one of the most ideal steam traps for heating equipment in manufacturing processes. 2. Free semi-floating ball type steam trap: The free semi-floating ball type steam trap has only one semi-floating ball chamber as the moving component; this chamber is open downward, and it serves both as the opening/closing element and as the sealing element. The entire sphere can be sealed, offering a long service life; it is resistant to water hammer, has no vulnerable components, operates without failures, is durable, and prevents steam leakage. With a backpressure ratio of over 80%, it is capable of discharging condensate at saturation temperature; the minimum subcooling degree is 0°C, and no water remains in the heating equipment, thereby enabling the heating equipment to achieve optimal heat exchange efficiency. When the device is first started, the air and low-temperature condensate in the pipeline enter the drain valve through the discharge tube. The bimetallic disc within the valve pushes the ball apart, opening the valve and allowing the air and low-temperature condensate to be discharged rapidly. When steam enters the ball tank, the tank experiences an upward buoyant force; at the same time, the temperature inside the valve rises, causing the bimetallic strip in the discharge element to contract. As a result, the ball tank moves toward the valve opening, and the valve closes. When the steam in the drum turns into condensed water, the drum loses its buoyancy and sinks; the valve opens, allowing the condensed water to be discharged rapidly. When steam re-enters the ball tank, the valve closes again, enabling intermittent and continuous operation. 3. Lever-ball type steam trap: The basic characteristics of the lever-ball type steam trap are the same as those of the free-ball type; its internal structure features a ball connected to a lever that drives the valve core, enabling the valve to open and close as the level of condensed water changes. The lever float type steam trap utilizes dual valve seats to increase the discharge volume of condensate, resulting in a compact design with high discharge capacity; its maximum steam discharge rate can reach 100 tons per hour, making it the ideal steam trap for large heating systems. 4. Inverted bucket type steam trap: The inverted bucket type steam trap uses an inverted bucket as the level-sensitive element; the opening of this bucket faces downward, and it is connected to a lever that drives the valve core to open and close the valve. The inverted bucket type steam trap can discharge air, is not susceptible to water hammer, and has good anti-fouling properties. The subcooling is low, the steam leakage rate is less than 3%, the maximum backpressure ratio is 75%, and there are many connecting parts; therefore its sensitivity is lower than that of a free-floating ball type steam trap. Since the inverted bucket type steam trap closes due to the upward buoyancy of steam, it is not suitable for use when the operating pressure difference is less than 0.1 MPa. When the device is first started, air and low-temperature condensate in the pipeline enter the drain valve; the inverted bucket drops due to its own weight, and the lever connected to the bucket drives the valve core to open, allowing the air and low-temperature condensate to be discharged quickly. When steam enters the inverted bucket, the steam in the bucket generates an upward buoyant force, causing the bucket to rise; this in turn moves the connecting lever and closes the valve. The inverted bucket has a small hole in it; as some of the steam escapes through this hole, the remaining steam condenses into water. This causes the inverted bucket to lose its buoyancy and to sink due to its own weight. The lever connected to the inverted bucket then operates to open the valve, allowing for continuous circulation and intermittent drainage. 5. Combined superheated steam trap: The combined superheated steam trap features two separate valve chambers, which are connected to each other by two stainless steel pipes. It is a combination of a float-type trap and an inverted bucket type trap. Its structure is advanced and rational; it enables timely discharge of the condensate water formed when superheated steam disappears under conditions of superheating, high pressure, and low load, effectively preventing the leakage of superheated steam and ensuring high performance. The maximum allowable temperature is 600°C; the valve body is made of all-stainless steel, while the valve seat is made of cemented carbide steel, ensuring a long service life. It is a specialized steam trap for superheated steam, and it holds two **patents, filling a gap in domestic technology. When the condensate enters the lower valve chamber, the float ball of the auxiliary valve rises as the liquid level increases, and the float ball closes off the steam inlet hole. The condensate rises to the main valve chamber through the inlet conduit; the hanging bucket drops due to its own weight, which in turn causes the valve core to open the main valve and allow the condensate to be discharged. When the condensate level in the secondary valve chamber drops, the float descends along with the level, and the secondary valve opens. Steam enters the upside-down bucket inside the upper main valve chamber through the steam inlet pipe; this bucket generates an upward buoyant force, which drives the valve core to close the main valve. When the condensate level in the secondary valve chamber rises again, the next cycle begins, with intermittent drainage.