JP3392951B2 - Thermal steam trap - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for trapping steam flowing out of a heat exchanger of a steam-using apparatus such as a steam heater so as not to leak the steam, and condensing the steam. It relates to a heat-sensitive steam trap that discharges only heat. 2. Description of the Related Art A heat-sensitive steam trap of this type is characterized in that when a high-temperature, high-pressure primary fluid containing steam flows into the trap chamber from an inlet, the heat-sensitive steam trap enters the trap chamber. In this trap chamber, the thermal expansion medium sealed by the flexible diaphragm receives heat from the primary fluid and expands, displacing the diaphragm. The valve body attached to the diaphragm sits on the valve seat to close the passage between the trap chamber and the outlet, preventing leakage of steam. On the other hand, when the temperature of the fluid falls below a predetermined value due to heat radiation, or when low-temperature condensate flows in from the inlet, the thermal expansion medium contracts, and the diaphragm is pressed by the pressure of the primary fluid. The valve element is separated from the valve seat, and only the condensate is discharged from the outlet. In the above-described heat-sensitive steam trap, since the flexible diaphragm having a small thickness is frequently deformed, the diaphragm may be broken. When the diaphragm is ruptured, the internal thermal expansion medium flows out of the damaged portion of the diaphragm, and the pressure difference between the space in which the thermal expansion medium is sealed and the external primary fluid disappears. The valve element is attracted to the valve seat by the negative pressure generated by the fluid passing through the narrow space between the valves, and the valve is closed. [0004] If the valve remains closed, the condensate cannot be discharged, so that the condensate accumulates in the heat exchanger on the upstream side and reduces the heat exchange efficiency. However, there is an inconvenience that a water hammer is generated due to sudden contraction caused by touching, and the heat exchanger and piping are damaged. Therefore, various thermally responsive steam traps have been proposed to solve such a problem (Japanese Patent Laid-Open No. Hei 4-2).
No. 62196, JP-A-4-370497, JP-A5-
No. 240399). However, any of the above steam traps is controlled to open the valve when the diaphragm is broken and to maintain the valve open state.
There are disadvantages in that the certainty of the valve opening state is insufficient and the reliability is lacking, and the configuration is complicated. Therefore, the present invention has a simplified and highly reliable structure and can reliably open the valve even if the thermal element enclosing the thermal expansion medium is broken, and can maintain the valve open state. It is intended to provide a mold steam trap. [0007] In order to achieve the above object, a heat-sensitive steam trap according to the present invention includes an inlet for a primary fluid containing steam and a condensate in a casing. outlet of the secondary side fluid, trap chamber, and a low-pressure chamber communicating with the outlet port is formed, further, the bag-like case
A thermal expansion medium for receiving heat from the primary fluid through the heat receiving surface of the case between the diaphragm and the diaphragm, and separating the trap chamber and the low pressure chamber from each other ;
Opposite side of the heat receiving surface of the casing mounted on the arm
And a valve element that opens and closes a communication port between the trap chamber and the low-pressure chamber, and the valve element is disposed in the low-pressure chamber . The heat-sensitive element is disposed so as to partition the space between the trap chamber and the low-pressure chamber with the heat-receiving surface of the case facing the trap chamber in order to receive heat from the primary fluid. The body is attached to a portion of the thermal element opposite to the heat receiving surface and is located in the low-pressure chamber, and opens and closes a communication port between the trap chamber and the low-pressure chamber. Therefore, since the valve body always receives the pressure of the primary fluid from the communication port in the valve opening direction, when the temperature of the primary fluid in the trap chamber is lower than a predetermined value, the heat received from the primary fluid is reduced. Since the expansion medium contracts and the volume decreases, the valve-closing force acting on the valve element from the heat-sensitive element decreases, and the valve element receives the pressure of the primary fluid, separates from the valve seat, and opens. Becomes When the primary fluid flowing into the trap chamber from the inlet is high-temperature steam obtained from water, the thermal expansion medium receives heat from the steam and expands, thereby increasing the volume of the thermal element. The heat-sensitive element displaces the valve body against the pressure of the primary fluid as the volume increases, and the valve body closes the communication port between the trap chamber and the low-pressure chamber. This prevents high-temperature steam from leaking from the outlet through the communication port. Next, when the temperature of the fluid in the trap chamber drops due to heat radiation and becomes lower than a predetermined value, or when low-temperature condensate flows in from the inlet, the thermal expansion medium contracts and the volume of the thermal element becomes smaller. At the time when the valve closing force acting on the valve element from the heat-sensitive element becomes smaller than the valve opening force due to the pressure of the primary fluid, the valve element receives the pressure of the primary fluid, and the valve element receives the pressure of the primary fluid from the valve seat at the communication port. When the valve is released, the condensate flows out from the outlet. In the case in which the thermal expansion medium of the thermosensitive element is sealed, the mounting portion of the valve body is formed of a flexible member for operating the valve body, for example, a diaphragm. If the diaphragm is damaged in the closed state, the thermal expansion medium leaks from the case into the low-pressure chamber, and the volume of the heat-sensitive element is reduced.Therefore, the valve-closing force acting on the valve body from the heat-sensitive element disappears, and the valve body becomes Upon receiving the pressure of the primary-side fluid, the valve separates from the valve seat of the communication port, and is opened. Thereafter, since the thermal expansion medium leaks out, the volume of the heat-sensitive element does not change due to the heat received from the primary fluid, and the valve-closing force cannot be applied to the valve element. Therefore, the valve body receives the pressure of the primary fluid and maintains the valve-open state separated from the valve seat. Further, when the diaphragm is broken when the valve is in the open state, the valve body also receives the pressure of the primary fluid to maintain the open state. In this heat-sensitive steam trap, the valve opening pressure is low because the passage area of the narrow communication passage is the pressure receiving area for opening the heat-sensitive element. Therefore, the valve closing force due to the pressure of the heat sensitive chamber for closing the valve by overcoming the valve opening pressure can be small, and the heat sensitive element can be downsized. Moreover,
Since the heat-sensitive element is arranged to partition between the trap chamber and the low-pressure chamber, as in the case where the heat-sensitive element is disposed in the trap chamber, for example, a support mechanism for the heat-sensitive element and an interlocking mechanism between the heat-sensitive element and the valve element. Are unnecessary, and the configuration is further simplified. Preferred embodiments of the present invention will be described below in detail with reference to the drawings. [First Embodiment] FIGS. 1A and 1B are simplified longitudinal sectional views of a heat-sensitive steam trap according to a first embodiment of the present invention. FIG. In a casing 1 constituting an exterior body, a lower casing member 2 and an upper casing member 3 are fitted to each other with a sealing material 4 interposed therebetween, and are fixed with bolts (not shown). The casing 1 has an inlet 6 for a high-temperature, high-pressure primary fluid containing steam flowing out of a heat exchanger or the like, and an outlet 7 for a low-temperature, low-pressure secondary fluid containing condensate. A trap chamber 5 at the center, an introduction passage 9 that communicates the introduction port 6 with the trap chamber 5, and an outlet passage 10 through which the secondary fluid flows through the outlet 7 are formed. Internal threads for connection are formed on the inner peripheral surfaces of the inlet 6 and the outlet 7. On the inner surface of the lower casing member 2, there is integrally formed a holding member 8 having a female screw formed on the inner peripheral surface of the cylindrical body. A valve seat member 11 is fixed to the holding member 8 by screw connection. Have been. The holding body 8 may be formed separately from the casing members 2 and 3 and fixed to one of the casing members 2 and 3 by means such as screwing or welding. The valve seat member 11 has a large-diameter portion 12 and a small-diameter portion 13 connected to each other, and a low-pressure chamber 16 described later is formed inside the large-diameter portion 12. Room 1
6 and a communication path 14. An opening end of the communication passage 14 on the low-pressure chamber 16 side is a communication port 17 between the trap chamber 5 and the low-pressure chamber 16, and a hole edge of the communication port 17 protrudes in a ring shape to form a valve seat 19. Have been. In addition, a communication hole 18 that communicates the low-pressure chamber 16 with the outlet passage 10 is formed in the large-diameter portion 12. An opening 20 is formed in the lower part of the holding body 8, and a ring-shaped support piece 25 is formed integrally with the periphery of the opening 20. A heat-sensitive element 26 is sandwiched and fixed between the support piece 25 and the large-diameter portion 12. The heat-sensitive element 26 is arranged to partition the trap chamber 5 from the inside of the large-diameter portion 12, and The low-pressure chamber 16 is surrounded by the heat-sensitive element 12 and the heat-sensitive element 26. The heat-sensitive element 26 has an exterior body formed by a bag-shaped case 24. The case 24 includes an upper first case body 22 having an open central portion and a lower container-like second case body 22.
The outer peripheral ends of the case body 23 are welded to each other to be fixed to each other. In the case 24, a diaphragm 30 is fixed with its outer peripheral end sandwiched between the case bodies 22 and 23. A thermal expansion medium 36 is sealed in a bag-shaped heat-sensitive chamber 35 surrounded by the diaphragm 30 and the second case body 23. The heat sensitive element 26 is fixed by sandwiching the outer peripheral end thereof between the support piece 25 and the large diameter portion 12 of the valve seat member 11. Here, the second case body 23 serves as a heat receiving surface for the thermal expansion medium 36 to receive heat from the primary fluid. Further, the gasket 27 seals the space between the heat-sensitive element 26 and the support piece 25, that is, the space between the trap chamber 5 and the low-pressure chamber 16. The thermal expansion medium 36 is a fluid having a saturated steam temperature lower than the saturated steam temperature of water and having a higher saturated pressure than water at the same temperature, for example, alcohol. The diaphragm 30 is made of a thin material having flexibility and corrosion resistance, for example, a stainless steel plate. As a material of the case 24, for example, stainless steel having excellent corrosion resistance and heat conductivity is used. A valve element 33 is attached to the center of the diaphragm 30 in the heat-sensitive element 26 by welding.
The valve body 33 faces the low-pressure chamber 16 through the opening of the first case body 22, and sits on or separates from the valve seat 19 to open and close the communication port 17. Next, the operation of the above embodiment will be described in detail. In FIG. 1, P1 is the pressure of the primary fluid, and P2 is 2
The pressure of the secondary fluid and P3 indicate the pressure in the heat-sensitive chamber 35 of the heat-sensitive element 26, respectively. Further, for example, when the pressure of the primary fluid is 5 kg (gauge pressure) and its saturated steam temperature is 158 ° C.
In this embodiment, for example, the thermal expansion medium 3
The thermal expansion is performed so that when the temperature of the sample No. 6 becomes 150 ° C. or more, the valve is completely closed as shown in FIG. The saturated steam temperature of the medium 36 and the curvature of the diaphragm 30 are set. The valve body 33 is disposed in the low-pressure chamber 16 and is a communication port 17 which is an opening of the communication passage 14 on the side of the low-pressure chamber 16.
Open and close. Since the low-temperature and low-pressure secondary fluid flows through the low-pressure chamber 16, the valve body 33 always receives the high-temperature and high-pressure primary fluid pressure P1 in the valve opening direction. When the temperature of the primary fluid in the trap chamber 5 is lower than a predetermined value (for example, 130 ° C.), the thermal expansion medium 36 that receives heat from the primary fluid through the second case body 23 is as shown in FIG. As shown, the volume shrinks and shrinks. The valve element 33 attached to the diaphragm 30 is separated from the valve seat 19 by the pressure P1 of the primary fluid and is opened. In the valve-open state shown in FIG. 1A, when a primary fluid containing high-temperature steam flows from the inlet 6,
Since the steam saturation temperature of the thermal expansion medium 36 is lower than the steam saturation temperature of the primary fluid, even if the primary fluid is condensed condensed steam and is at or below the steam saturation temperature of water, thermal expansion When the temperature is equal to or higher than the vapor saturation temperature of the medium 36, the thermal expansion medium 3
6 expands due to the heat reception, and the pressure P3 in the heat-sensitive chamber 35 becomes larger than the pressure P1 of the primary fluid. Therefore, the expansion of the thermal expansion medium 36 of the thermal element 26 increases the volume in the thermal chamber 35 and displaces the diaphragm 30 upward, so that the valve body 33 attached to the diaphragm 30 reduces the pressure of the primary fluid. The seat 17 is seated against the valve seat 19 and the communication port 17 for communicating the trap chamber 5 with the outlet port 7 is closed to close the valve, thereby preventing the high-temperature steam from leaking from the outlet port 7. Next, when the temperature of the fluid in the trap chamber 5 is condensed by heat radiation and becomes lower than a predetermined value (for example, 130 ° C.), or when low-temperature condensate flows in from the inlet 6, the thermal expansion medium At the time when the valve 36 contracts and the volume of the heat-sensitive element 26 in the heat-sensitive chamber 35 decreases, the valve-closing force acting on the valve body 33 from the heat-sensitive element 35 becomes lower than the valve-opening force due to the pressure P1 of the primary fluid. The valve element 33 receives the pressure P1 of the primary fluid and separates from the valve seat 19 to be in an open state, and condensate flows out from the outlet. If the diaphragm 30 is broken in the valve closed state shown in FIG. 1B, the thermal expansion medium 36
5 leaks into the low-pressure chamber 16 through the opening at the center of the first case body 22. Therefore, the valve element 3
3, the valve body 33 receives the pressure P1 of the primary fluid, and the valve body 19 receives the pressure P1.
And the valve is opened. Thereafter, the thermosensitive element 26
Since the thermal expansion medium 36 leaks, the volume does not change due to the heat received from the primary fluid, and the valve closing force cannot be applied to the valve body 33. Therefore, the valve element 3
Numeral 3 receives the pressure P1 of the primary fluid and maintains the valve-open state separated from the valve seat 19. If the diaphragm 30 is broken in the open state, the open state is maintained. This heat-sensitive steam trap is provided with a valve body 33.
Is disposed on the low pressure chamber 16 side, and the valve body 33 always receives the pressure P1 of the primary fluid in the valve opening direction. for that reason,
Since the thermal element 26 need only apply a valve closing force to the valve body 33 via the diaphragm 30 by expansion due to heat received from the primary fluid, the thermal element 26 is simpler and more reliable than the existing thermally responsive steam trap. High configuration. Further, the heat sensitive element 26 is arranged so as to partition between the trap chamber 5 and the low pressure chamber 16 and is simply sandwiched and fixed between the large diameter portion 12 and the support piece 25. For example, a support mechanism for the heat-sensitive element 26, such as a case where the heat-sensitive element 26 is disposed in the trap chamber 5, or a structure in which the heat-sensitive element 26
This eliminates the need for an interlocking mechanism or the like, and the configuration is further simplified from this point. In addition, the valve opening pressure is low because the passage area of the narrow communication passage is the pressure receiving area of the pressure for opening the thermal element. Therefore, the valve-opening force by the pressure of the heat-sensitive chamber for overcoming the valve-opening pressure and closing the valve can be small, and the heat-sensitive element 26 can be downsized. [Second Embodiment] FIGS. 2A and 2B are simplified cut-away side views of a heat-sensitive steam trap according to a second embodiment of the present invention in a valve open state and a valve closed state. In this embodiment, the casing 1 is divided into left and right parts, and the first casing body 28 and the second casing body 29 are combined. The heat-sensitive element 26 is composed of the two casing bodies 28, 2
The second case 23, which forms a heat receiving surface from the primary fluid, is opposed to the introduction passage 9 while being attached by a mechanism similar to that of the first embodiment. The primary fluid flowing from the inlet 6 flows from the introduction passage 9 through the lower passage to the communication passage 14, and is opened by opening the valve body 33.
It flows into the low-pressure chamber 16 as the secondary fluid, and further flows from the low-pressure chamber 16 through the outlet passage 10 and out of the outlet 7. In the second embodiment, the second case body 23 which forms a heat receiving surface from the primary fluid in the thermal element 26 is used.
Is opposed to the introduction passage 9, the thermal expansion medium 36
Heat is always received from a new primary fluid flowing in from the inlet 6. In addition, since the fluid on the primary side continuously and smoothly flows through the above-described path, the fluid does not stay at the bottom of the casing, that is, locally, and does not lower the temperature. Also,
Even if the condensed water stays at the bottom in the casing 1, the second case body 23 forming the heat receiving surface of the thermosensitive element 26 is separated from the bottom of the casing 1. There is little risk of accidental opening of the valve by direct contact with water. As a result, heat is efficiently conducted from the primary fluid to the thermal expansion medium 36, and the valve body 33 is opened and closed appropriately. Third Embodiment FIGS. 3A and 3B are simplified cut-away side views of a heat-sensitive steam trap according to a third embodiment of the present invention in a valve-open state and a valve-closed state. In this embodiment, the heat-sensitive element 26 of the second embodiment is placed horizontally. The thermal element 26 is mounted between the lower casing member 2 and the upper casing member 3 by the same mechanism as in the second embodiment. The lower casing member 2 is formed with an introduction passage 9 that guides the primary fluid flowing from the inlet 6 to the second case body 23 that forms the heat receiving surface of the thermosensitive element 26. Further, since the primary fluid flows continuously and smoothly to the outlet 7 through substantially the same path as that of the second embodiment, the primary fluid stays at the bottom of the casing 1. There is little risk of temperature drop. Therefore, substantially the same effects as in the second embodiment can be obtained. Further, in the third embodiment, a ring-shaped heat insulating sheet member 34 made of a material such as rubber is provided around the valve body 33. This heat insulating sheet material 34
The central hole edge is connected to the outer periphery of the valve body 33, and the outer peripheral end is sandwiched and fixed between the support piece 25 and the large-diameter cylindrical portion 12. Therefore, the diaphragm 30 is shielded by the heat insulating sheet member 34 so as not to be affected by the temperature of the secondary fluid in the low-pressure chamber 19. 1st, 2nd
In the embodiment, since the diaphragm 30 is in contact with the secondary fluid in the low-pressure chamber 19 when the valve is closed, the diaphragm 30 is cooled by the secondary fluid and may not expand sufficiently when the valve is closed. . Such inconvenience can be reliably prevented by the heat insulating sheet member 34.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A and 1B show a first embodiment of the present invention, in which FIG. 1A is a simplified longitudinal sectional view in a valve-opened state, and FIG. 2A and 2B show a second embodiment of the present invention, in which FIG. 2A is a simplified cut-away side view in a valve-opened state, and FIG. 3A and 3B show a third embodiment of the present invention, in which FIG. 3A is a simplified cut side view in a valve open state, and FIG. 3B is a simplified cut side view in a valve closed state. [Description of Signs] 1 ... Casing, 5 ... Trap chamber, 6 ... Inlet, 7 ... Outlet, 17 ... Communication port, 19 ... Low pressure chamber, 26 ... Thermal element,
33: valve body, 36: thermal expansion medium.

Claims (1)

(57) [Claim 1] A casing is connected to an inlet for a primary fluid containing steam, an outlet for a secondary fluid containing condensate, a trap chamber, and the outlet. A low-pressure chamber is formed, and a case is formed between the diaphragm and the inside of the bag-shaped case.
It has a thermal expansion medium to heat from the primary side fluid through the heat receiving surface of the thermal element which partitions between the low-pressure chamber and the trap chamber, in the case attached to the diaphragm
A heat- sensitive steam trap , comprising: a valve body located on a side opposite to a heat receiving surface, for opening and closing a communication port between the trap chamber and the low-pressure chamber , wherein the valve body is disposed in the low-pressure chamber .