JP7610826B2 - Nozzle type steam trap - Google Patents

Description

The present invention relates to a nozzle-type steam trap that separates and discharges condensed water (hereinafter referred to as "drain") generated by heat exchange with steam.

In factories and other facilities that use steam as a heating source, steam traps are used to discharge drainage generated in heat exchangers and steam transport routes outside the system to ensure stable and safe operation. There are various types of moving steam traps, but in recent years nozzle-type steam traps, which have no moving parts, have come into use.

Nozzle-type steam traps take advantage of the fact that water has a lower kinetic viscosity than steam when passing through fine passages, and the mass flow rate of water is greater than that of steam. The mechanism is that a nozzle is attached inside the main body, and the drain discharge hole in the nozzle prevents steam from passing through, allowing only the drain to pass.

In a steam trap, the drain flow rate needs to be adjusted according to the drain discharge volume. In a conventional nozzle-type steam trap, several nozzles with different drain discharge hole diameters are prepared, and the nozzle with the appropriate drain discharge hole diameter is selected and installed.

With such conventional nozzle-type steam traps, adjusting the drain flow rate requires removing the lid and other components that seal the internal space, replacing the nozzle, and then resealing the trap. Therefore, in order to adjust the drain flow rate to the appropriate level, it is necessary to determine whether the nozzle is appropriate while observing the drain discharge rate, and to make adjustments by repeatedly attaching and detaching the nozzle, which is a time-consuming and labor-intensive process. In addition, it is dangerous to come into contact with high-temperature steam and the drain.

The invention described in Patent Document 1 solves the problems with nozzle-type steam traps, and has a needle that moves from one end of the nozzle toward the drain discharge hole of the nozzle. This needle moves forward and backward by external operation, and together with the nozzle, forms a needle valve that adjusts the flow rate of the drain.

According to the invention described in Patent Document 1, the drain discharge volume can be finely adjusted easily and quickly by adjusting the needle valve without having to open the internal space and replace the nozzle.

JP 2019-196807 A

The present invention aims to improve on the invention described in Patent Document 1 and provide a nozzle-type steam trap that can more accurately and quickly fine-tune the drain discharge volume.

The present invention relates to
A nozzle-type steam trap having a first nozzle in a path from a drain inlet to a drain outlet,
The first nozzle communicates with an expansion chamber downstream of the drain, and the expansion chamber communicates with the drain outlet through a second nozzle;
a needle that can be moved forward and backward relative to the second nozzle by an external operation to adjust the flow rate of the drain passing through the second nozzle;
a first pressure gauge for detecting a pressure on the drain inlet side and a second pressure gauge for detecting a pressure on the drain outlet side of the first nozzle;
The most important feature is that the flow rate of the drain can be adjusted by adjusting the difference in pressure detected by the first pressure gauge and the second pressure gauge with the needle.

The flow rate of the drain discharged through the nozzle-type steam trap of the present invention is determined by the detected pressure difference and the flow area of the second nozzle. Once the target value of the flow rate is determined, the detected pressure difference is also determined, and the position of the needle relative to the second nozzle is adjusted so that this detected pressure difference becomes the target value. This needle adjustment can be performed based on the detected pressures by the first and second pressure gauges, making it possible to fine-tune the drain discharge rate more easily, safely, and in a shorter time than the invention described in Patent Document 1.

FIG. 1 is a cross-sectional view taken along a drain flow path, showing an embodiment of a nozzle-type steam trap according to the present invention. FIG. 4 is a vertical sectional view showing a modified example of the needle in the embodiment. FIG. 11 is a vertical sectional view showing another modified example of the needle in the embodiment.

Below, an embodiment of a nozzle-type steam trap according to the present invention will be described with reference to the drawings.

[composition]
As shown in Fig. 1, the nozzle type steam trap is mainly composed of a housing 1 made of a metal forging or the like. The housing 1 has a drain inlet 5 connected to, for example, a drain outlet of a heat exchanger that uses steam, and a drain outlet 8 that communicates with the drain inlet 5 via a communication passage 7. A strainer 6 is located between the drain inlet 5 and the communication passage 7. The housing 1 is molded integrally with the housing of the strainer 6.

In FIG. 1, the communication passage 7 runs from the bottom to the top of the housing, then folds back and runs from the top to the bottom, then bends horizontally at a right angle to connect to the drain outlet 8. The top end of the housing 1 is open, and this open end is closed by the lid 2, which is tightly attached to the housing 1 by a fastening member.

The strainer 6 has a mesh filter spaced at regular intervals in the vertical and horizontal directions, and prevents foreign matter such as rust and impurities larger than the size of the mesh from flowing into the communication passage 7. A cap 14 is attached to the end of the strainer 6. The filter can be removed and cleaned by removing the cap 14.

A first nozzle 10 is provided in the communication passage 7 at a portion where the drain flows from bottom to top in FIG. 1. The first nozzle 10 is configured by arranging a first nozzle member 11, a second nozzle member 12, and a third nozzle member 13 in series from bottom to top.

Each nozzle member 11, 12, 13 has a nozzle hole, which is a small hole that allows the drain to pass through, and has an expansion chamber 14, 15, 16 downstream of the drain from each nozzle hole. The expansion chamber 16 downstream of the third nozzle member 13 is connected to an expansion chamber 17 formed between the housing 1 and the lid 2.

A second nozzle 20 is attached to the portion of the communication passage 7 that is folded back at the top of the housing 1 and faces downward. The second nozzle 20 has a drain hole 21 that narrows the drain passage. The drain hole 21 is a hole with a perfectly circular cross section. The communication passage 7 located below the second nozzle 20 forms an expansion chamber 22. The expansion chamber 17 is connected to the expansion chamber 22 via the drain hole 21 of the second nozzle 20. The expansion chamber 22 is connected to the drain outlet 8.

As described above, the first nozzle 10 is connected to the expansion chamber 17 on the downstream side of the drain, and the expansion chamber 17 is connected to the drain outlet 8 via the second nozzle 20.

In the embodiment shown in FIG. 1, the first nozzle 10 is composed of multiple nozzle members 11, 12, and 13 arranged in series, but the first nozzle 10 may be composed of a single nozzle member. Furthermore, when the first nozzle 10 is composed of multiple nozzle members, the number of nozzle members is arbitrary. When the first nozzle 10 is composed of multiple nozzle members, the nozzle hole diameters may be the same or different. The nozzle hole diameter will be explained further below.

A needle 4 is attached to the lid 2 in the vertical direction via a sleeve 31 above the second nozzle 20. The tip of the needle 4, i.e., the lower end 41 in FIG. 1, is formed in a conical shape, and this conical lower end 41 faces the upper end of the nozzle hole 21 of the second nozzle 20. The sleeve 31 is screwed into the threaded hole of the lid 2. The needle 4 is inserted into the sleeve 31 in the direction of its central axis, and the male thread formed on the outer periphery is screwed into the female thread formed on the inner periphery of the sleeve 31.

The maximum diameter of the lower end 41 of the needle 4 is approximately equal to the diameter of the nozzle hole 21 of the second nozzle 20. When the needle 4 is rotated around its central axis, the male thread is led by the female thread of the sleeve 3, and the conical lower end 41 moves forward and backward relative to the nozzle hole 21 of the second nozzle 20. As the needle 4 moves forward and backward, the drain inlet area to the nozzle hole 21, i.e., the area of the ring-shaped gap formed by the nozzle hole 21 on the upper end surface of the nozzle 20 and the tip 41 of the needle 4, increases and decreases. The second nozzle 20 and the needle 4 form a needle valve.

The joint between the lid 2 and the sleeve 31 and the joint between the sleeve 31 and the needle 4 are sealed to maintain airtightness. A cap 32 is screwed onto the upper end of the sleeve 31, and the upper end of the needle 4 passes through the cap 32. A handle 48 is attached to the upper end of the needle 4 for rotating the needle 4.

The nozzle type steam trap has a first pressure gauge 51 on the drain inlet 5 side that detects the pressure on the drain inlet 5 side, and a thermometer that detects the temperature of the drain flowing into the drain inlet 5. It also has a second pressure gauge 52 that detects the pressure on the drain outlet side of the first nozzle 10, i.e., the pressure of the expansion chamber 17. Furthermore, it has a third pressure gauge 53 on the drain outlet 8 side that detects the pressure on the drain outlet 8 side. The needle 4 is adjusted according to the pressure difference detected by these pressure gauges, making it possible to adjust the flow rate of the drain. Flow rate adjustment will be explained in detail later.

The flow rate of the drain is adjusted by the needle 4 according to the values detected by the pressure gauges 51, 52, 53 and the thermometer. This flow rate adjustment may be performed manually or automatically. FIG. 1 shows an example of automatic control, in which a motor 70 that drives the needle 4 and a control unit 60 that controls the motor 70 are provided. The pressure P1 detected by the first pressure gauge 51, the pressure P2 detected by the second pressure gauge 52, the pressure P3 detected by the third pressure gauge 53, and the temperature T detected by the thermometer are input to the control unit 60.

[Action]
The operation of the nozzle type steam trap explained so far will now be described. In the nozzle type steam trap, the drain inlet 5 is connected to a heat exchanger and a steam transport path, and the drain is discharged from the drain outlet 8 via the strainer 6, the first nozzle 10, and the second nozzle 20. When the drain passes through the first nozzle 10 and the second nozzle 20, the flow path is narrowed by the nozzle holes of each nozzle, causing an increase in pressure, and the pressure is reduced by expansion in the expansion chamber, repeating this process.

The first nozzle 10 is composed of three nozzle members 11, 12, and 13 arranged in series, and pressure buildup and expansion are repeated through each nozzle hole and each expansion chamber 14, 15, and 16. The steam strap effect is exerted in the multiple nozzle members 11, 12, and 13, enhancing the steam strap effect. This allows only the drain to pass through, and prevents steam from passing through.

In the nozzle-type steam trap according to the embodiment of the present invention shown in FIG. 1, when the needle 4 is rotated to cause its tip 41 to enter the nozzle hole 21 of the second nozzle 20, the amount of drain entering the nozzle hole 21 decreases. The detected pressure P2 of the pressure gauge 52 installed in the expansion chamber 17, i.e., downstream of the first nozzle 10, increases. Since the pressure on the drain inlet 5 side is almost constant, the detected pressure P1 of the first pressure gauge 51 is almost constant. Therefore, the detected pressure difference P1-P2 between the first pressure gauge 51 and the second pressure gauge 52 becomes small.

When the detected pressure difference P1-P2 is smaller than the predetermined pressure difference, it is because the drain flow rate through the second nozzle 20 is too low. In such a case, the needle 4 is rotated in the opposite direction to retract the second nozzle 20, thereby expanding the area of the gap formed between the nozzle hole 21 and the tip 41 of the needle 4.

The flow rate of the drain passing through the second nozzle 20 varies in proportion to the square root of the pressure difference between the inlet side of the second nozzle 20 and the drain outlet 8 side, i.e., the difference between P2 and P3. If the area of the gap formed by the nozzle hole 21 and the tip 41 of the needle 4 is enlarged, the flow rate of the drain passing through the second nozzle 20 increases, the pressure P2 decreases, and the detected pressure difference P1-P2 increases.

According to an embodiment of the present invention, the drain flow rate of the second nozzle 20 can be appropriately adjusted based on the detected pressure difference P1-P2 between the drain inlet 5 and the drain outlet side of the first nozzle 10.

In conventional nozzle-type steam traps, the drain flow rate is determined by the nozzle hole diameter of the nozzle. Therefore, the drain discharge volume is theoretically calculated, and the nozzle hole diameter is determined based on the calculated discharge volume. However, when the device is operated, problems can arise, such as the drain not being discharged efficiently or steam leaking through the steam trap. In such cases, the appropriate flow rate is set by replacing the nozzle with one of a different nozzle hole diameter. As this device handles high-temperature, high-pressure steam, this type of adjustment work is difficult.

In this regard, the nozzle-type steam trap described in Patent Document 1 can continuously adjust the flow rate by adjusting the needle valve from the outside without replacing the nozzle. However, the nozzle-type steam trap described in Patent Document 1 does not have a guide for adjusting the needle valve, so adjustments must be made by feel while visually checking the drain flow.

In the above embodiment of the nozzle-type steam trap according to the present invention, the flow rate of the drain from the second nozzle 20 is adjusted based on a clear indicator, the difference in detected pressure P1-P2 between the drain inlet 5 and the drain outlet side of the first nozzle 10. Therefore, the generated drain can be discharged accurately and precisely according to its amount. The drain discharge amount can be continuously adjusted by a needle valve, and there is no need to adjust while replacing nozzles with different nozzle hole diameters, so adjustments can be made safely and quickly.

The diameter of the nozzle hole 21 of the second nozzle 20 is set to be larger than the theoretically calculated hole diameter. It is also set to be significantly larger than the nozzle holes of the nozzle members 11, 12, and 13 that make up the first nozzle 10. The actual opening area of the nozzle hole 21 of the second nozzle 20 is limited by the tip 41 of the needle 4. The flow rate of the drain that flows through the second nozzle 20 is fine-tuned by the needle 4.

When the drain flow rate is automatically controlled, the control unit 60 controls the motor 70 to adjust the needle valve opening based on the pressures P1, P2, and P3 detected by the first, second, and third pressure gauges 51, 52, and 53, and the temperature T on the drain inlet 5 side. If there are many drains on the drain inlet 5 side, the temperature T drops, so the control unit 60 controls the motor 70 to increase the needle valve opening and increase the flow rate of the drain passing through the second nozzle 20.

When the difference between the detected pressures P1 and P2 is small, it can be determined that the needle valve opening is small relative to the amount of drain, so the control unit 60 controls the motor 70 to increase the needle valve opening.

By installing the nozzle-type steam trap according to the illustrated embodiment in a steam transport path that generates little drain, it is possible to obtain significant energy savings. This is because the first nozzle 10 is composed of multiple continuous nozzle members 11, 12, and 13 to enhance the steam strap effect, and the steam strap action can be appropriately adjusted by fine-tuning the needle valve. Specifically, in a steam transport path that generates little drain, the needle valve is fine-tuned so that the difference between the detected pressures P1 and P2 is small.

As mentioned above, the amount of drain generated in the steam transport path is small, so even if steam straps are installed in the steam transport path, adjustment of the amount of drain discharged by the steam straps has been neglected. If adjustments were made, they were only performed by replacing nozzles with nozzles of different diameters. By installing a nozzle-type steam trap according to the illustrated embodiment in the steam transport path, it is possible to efficiently prevent steam discharge and to increase energy saving effects.

[Modifications of Needle]
In a nozzle-type steam trap, a strainer 6 is placed upstream of the nozzle to prevent the nozzle hole from being blocked by foreign matter. As mentioned above, the strainer 6 is fitted with mesh filters spaced at regular intervals in the vertical and horizontal directions, which capture foreign matter larger than the mesh and prevent the nozzle hole from being blocked.

However, foreign matter larger than the mesh of the filter may flow in and block the nozzle hole. In particular, in the present embodiment, where the needle valve is formed by the tip 41 of the needle 4 and the upper end of the second nozzle 20, the gap in the needle valve becomes extremely narrow, and this gap may become blocked by foreign matter, causing clogging.

Figure 2 shows one modified example of the needle 4 that prevents the gap from being blocked by foreign matter. In Figure 2, the needle 4 has a conical tip 41, a male screw 42 that screws into the female screw of the sleeve 31, and a fitting portion 43 of the handle 48. The needle 4 has a slit 45 that runs along the length of the needle 4 from a part of the tip 41 to the male screw 42 on the surface facing the nozzle hole 21 of the second nozzle 20.

The width or depth of the slit 45 is set to be greater than the diagonal length of the mesh of the filter, i.e. the mesh size multiplied by the square root of 2. The filter of the strainer 6 is permeable to foreign matter up to the diagonal length of its mesh, so foreign matter of this size must pass through the nozzle hole 21 of the second nozzle 20. If the width or depth of the slit 45 of the needle 4 is set as described above, foreign matter that has slipped through the mesh of the filter in the diagonal direction can pass along the slit 45, preventing clogging of the needle valve portion.

Figure 3 shows another example of the needle 4. The needle 4 shown in Figure 3 differs from the needle 4 shown in Figure 2 in that it has two slits 451, 452 along the length of the needle 4. The two slits 451, 452 are located diametrically opposite each other across the central axis of the needle 4. The width or depth of the slits 451, 452 is set in the same way as the slit 45 in Figure 2. The other configuration is the same as the needle 4 in Figure 2, so common reference symbols are used and explanations are omitted.

If the needle 4 shown in Figure 3 is used as the needle 4 of the nozzle-type steam trap shown in Figure 2, clogging of the needle valve due to foreign matter can be prevented even more effectively.

Instead of the slits 45, 451, 452 of the needle 4, one or more slits may be provided on the nozzle hole 21 side of the second nozzle 20 through which the needle 4 advances and retreats. Alternatively, in addition to the slits 45, 451, 452 of the needle 4, one or more slits may also be provided on the nozzle hole 21 side of the second nozzle 20 through which the needle 4 advances and retreats.

REFERENCE SIGNS LIST 1 housing 2 lid 4 needle 5 drain inlet 6 strainer 7 communication passage 8 drain outlet 10 first nozzle 11 first nozzle member 12 second nozzle member 13 third nozzle member 17 expansion chamber 20 second nozzle 21 nozzle hole 22 expansion chamber 51 first pressure gauge 52 second pressure gauge 53 third pressure gauge

Claims (7)

A nozzle-type steam trap having a first nozzle in a path from a drain inlet to a drain outlet,
The first nozzle communicates with an expansion chamber downstream of the drain, and the expansion chamber communicates with the drain outlet through a second nozzle;
a needle that can be moved forward and backward relative to the second nozzle by an external operation to adjust the flow rate of the drain passing through the second nozzle;
a first pressure gauge for detecting a pressure on the drain inlet side and a second pressure gauge for detecting a pressure on the drain outlet side of the first nozzle;
The flow rate of the drain can be adjusted by adjusting the difference in pressure detected by the first pressure gauge and the second pressure gauge with the needle ,
The first nozzle is a nozzle-type steam trap composed of a plurality of nozzle members arranged in series . 2. A nozzle-type steam trap according to claim 1 , wherein each of said nozzle members has an expansion chamber downstream of the drain. 3. The nozzle-type steam trap according to claim 1, wherein the nozzle holes of the plurality of nozzle members have different diameters. 3. The nozzle-type steam trap according to claim 1, wherein the nozzle holes of the plurality of nozzle members have the same diameter. 5. A nozzle-type steam trap according to claim 1 , wherein the needle has a slit extending along a length of the needle on a surface facing the nozzle hole of the second nozzle. 6. The nozzle-type steam trap according to claim 5 , further comprising a strainer on the drain inlet side, and the slit has a width or depth that allows foreign matter passing through the strainer to pass therethrough. 7. A nozzle-type steam trap according to claim 5 , further comprising a slit on the nozzle hole side of the second nozzle through which the needle advances and retreats, in place of the slit in the needle or in addition to the slit in the needle.

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