JP7748711B2 - Steam Locking Elimination System - Google Patents

Description

The steam locking elimination system of this application relates to technology for eliminating steam locking, which occurs when only steam is trapped in a part of a steam trap or the like, blocking the flow of condensate and preventing the condensate from being properly discharged.

Industrial plants and other facilities often have piping systems that transport steam generated in boilers. The steam is sent through these piping systems to various pieces of equipment and used as a heat source. The steam condenses due to heat release during transport and heat exchange within each piece of equipment, resulting in drainage (condensed water) in the piping system.

A steam trap is installed in the piping system to discharge this condensate outside the system. Steam traps come in a variety of structures, but float traps have a hollow float built into the valve chamber. Under normal circumstances, this float blocks the condensate discharge port formed near the bottom of the valve chamber. However, when condensate flows into the valve chamber and the condensate water level rises, the float rises accordingly, automatically opening the condensate discharge port and opening the valve.

When the condensate discharge port is opened and the valve is opened, condensate is allowed to pass through the valve chamber, and the condensate that has accumulated in the valve chamber is automatically discharged from the condensate discharge port due to the force of the high pressure in the piping. After the condensate is discharged, the float descends and returns to its seat, once again blocking the condensate discharge port. The float repeatedly rises and falls in this manner to discharge the condensate, but because the condensate discharge port is always submerged in condensate, steam does not leak from the steam trap under normal conditions.

However, in steam traps, depending on the conditions of the inflowing steam and condensate, steam can get trapped in part of the valve chest or piping condensate, blocking the flow of condensate and causing steam locking, which prevents the condensate from being discharged properly.

One system for eliminating this type of steam locking is the technology disclosed in Patent Document 1, listed below. The heating cylinder 100 disclosed in Patent Document 1 comprises a cylinder body 10 into which steam is supplied, and a drain pipe 20 that discharges condensate using the pressure inside the cylinder body 10. Drain piping 31 is connected downstream of the drain pipe 20, and this drain piping 31 is equipped with a steam trap 40 for automatically discharging condensate.

Bypass pipes 32 are connected to drain pipes 31 upstream and downstream of the steam trap 40, and valves 50 are attached to these bypass pipes 32. Valves 50 open and close based on signals from a control unit 60, which controls the opening and closing of valves 50 according to the amount of drain stored in the cylinder body 10.

In other words, if steam locking occurs in the steam trap 40, the condensate will not be properly discharged, and the amount of condensate accumulated in the cylinder body 10 will increase. The control unit 60 detects this increase in the amount of condensate accumulated and opens the valve 50. This causes the condensate to bypass the steam trap 40 and be discharged through the bypass pipe 32, eliminating the steam locking.

Japanese Patent Application Laid-Open No. 2017-86248

The technology disclosed in the aforementioned Patent Document 1 installs a bypass pipe 32 to eliminate steam locking. This bypass pipe 32 must be branched off from the drain pipe 31, which increases equipment costs.

In addition, because the valve 50 on the bypass pipe 32 is opened to eliminate steam locking, there is a risk of steam loss occurring if steam leaks from inside the cylinder body 10 through the drain pipe 20 immediately after drainage.

The steam locking elimination system of this application aims to provide a simple steam locking elimination system that can reliably eliminate steam locking without causing steam loss.

The steam locking elimination system according to the present application comprises:
A flow path through which condensed water generated from steam flows from upstream to downstream.
a discharge valve provided in the flow passage for discharging the condensed water downstream;
a cooling means for cooling the flow passage upstream of the discharge valve or the discharge valve;
The present invention is characterized by the following features.

In the steam locking elimination system according to the present application, the cooling means cools the flow passage upstream of the discharge valve or the discharge valve. Therefore, even if steam locking of the discharge valve causes steam to be trapped and condensed water to be prevented from being properly discharged from the discharge valve, the cooling means can condense the steam trapped in the flow passage upstream of the discharge valve or in the discharge valve, turning it into condensed water. Therefore, despite the simple configuration, steam locking can be reliably eliminated without causing steam loss.

1 is a block diagram of the overall configuration of a steam-using device relating to a heating cylinder 1, illustrating a first embodiment of a steam-locking elimination system according to the present application. 2 is a graph showing a change over time in the temperature detected by the temperature sensor 41 shown in FIG. 1 .

[Terminology used in the embodiment]
The main terms used in the embodiments correspond to the following elements of the steam locking prevention system according to the present application:

Steam trap 2: discharge valve Drain pipe 16: flow path Cooling pipe 20: cooling means, cooling path Temperature sensor 41: temperature detection means Cooling valve 45: cooling path opening/closing valve Drain: condensed water Industrial water: cooling fluid

[First embodiment]
A first embodiment of a steam-locking elimination system according to the present application will be described with reference to Figures 1 and 2. In this embodiment, an example is given in which the steam-locking elimination system according to the present application is applied to a steam-using device related to a heating cylinder 1.

(Explanation of the overall configuration of the steam-using device related to the heating cylinder 1)
First, the overall configuration of the steam-using device related to the heating cylinder 1 will be described with reference to Figure 1. The heating cylinder 1 has a cylinder body 4, which is configured as a hollow column extending along a central axis L1. Shafts 4a and 4b extending in the direction of the central axis L1 are provided on both ends of the cylinder body 4, and the shafts 4a and 4b are rotatably supported by bearings (not shown).

A steam supply pipe 12 is connected to the shaft portion 4a of the cylinder body 4, and steam is supplied to the interior of the cylinder body 4 through this steam supply pipe 12. In other words, the heating cylinder 1 is a heater that uses steam as a heat source and can heat objects such as paper or laundry that come into contact with the outer surface of the cylinder body 4. Heating the object causes the steam to release heat, and this heat release causes the steam inside the cylinder body 4 to condense and liquefy into the drain 30, where it remains and is stored in the internal space of the cylinder body 4.

A drain pipe 14 is disposed within the internal space of the cylinder body 4. One end of this drain pipe 14 is located near the bottom of the internal space of the cylinder body 4, and the other end passes through the shaft portion 4a and is located outside the cylinder body 4. The drain pipe 14 is a siphon tube that receives steam pressure from the cylinder body 4 and discharges drain 30 to the outside of the cylinder body 4. In terms of the drain flow, the inside side of the drain pipe 14 within the cylinder body 4 is the upstream side, and the outside side of the cylinder body 4 is the downstream side.

Drain piping 16 is connected downstream of drain pipe 14. This drain piping 16 is equipped with a steam trap 2. Steam trap 2 is an automatic valve that discharges drain outside the piping as appropriate and operates to minimize steam leakage.

Steam traps come in a variety of structures, but the steam trap 2 in this embodiment is a float trap. A float trap has a hollow float built into the valve chest (not shown). Under normal circumstances, this float blocks the condensate discharge port formed near the bottom of the valve chest (closed valve state), blocking the passage of condensate through the valve chest. However, when condensate flows into the valve chest and the condensate level rises, the float rises accordingly, automatically opening the condensate discharge port and opening the valve.

When the condensate discharge port is opened, condensate is allowed to pass through the valve chamber, and any condensate accumulated in the valve chamber is automatically discharged from the condensate discharge port due to the force of the high pressure in the piping. After the condensate is discharged, the float descends and returns to its seat, once again blocking the condensate discharge port. Although the float repeatedly rises and falls in this way to discharge the condensate, steam does not leak from the steam trap because the condensate discharge port remains submerged in the condensate at all times. In this embodiment, the condensate discharged by the steam trap 2 flows into the condensate recovery pipe 18.

A water supply pipe 10 for transporting industrial water is located in the installation area of the heating cylinder 1. The water supply pipe 10 is provided with a cooling pipe 20 as a bypass pipe. In other words, both ends of the cooling pipe 20 are connected to the upstream and downstream parts of the water supply pipe 10, respectively, allowing industrial water to circulate through the cooling pipe 20.

The cooling pipe 20 has a coil portion 20a, which is arranged so that it is wrapped around the drain pipe 16 upstream of the steam trap 2. The winding diameter of the coil portion 20a is slightly larger than the outer diameter of the drain pipe 16, and the coil portion 20a wraps around the drain pipe 16 in close proximity. By wrapping the coil portion 20a around the drain pipe 16, efficient cooling is possible.

A cooling valve 45 is provided in the cooling pipe 20. This cooling valve 45 is, for example, an electromagnetic valve, and can open and close in accordance with a valve open signal or valve close signal from the controller 25. Note that under normal circumstances, the cooling valve 45 is closed. In addition, a temperature sensor 41 is provided in the drain pipe 16 downstream of the steam trap 2, and the temperature of the drain pipe 16 detected by the temperature sensor 41 is output to the controller 25 as a detection signal.

(Explanation of the steam locking elimination operation)
In a steam trap, depending on the conditions of the inflowing steam and condensate, re-evaporated steam may become trapped in the valve chest or part of the discharge pipe of the steam trap. In this case, even though condensate is generated upstream, the water level in the valve chest does not rise, so the float cannot rise and the valve remains closed, preventing proper condensate discharge. This is known as steam locking, and the operation to resolve this steam locking phenomenon is described below.

Since drain is liquefied condensate from high-temperature, high-pressure steam, the drain discharged from steam trap 2 is usually also at a high temperature. For this reason, when steam locking is not occurring, the temperature of drain piping 16 is maintained at a high temperature. However, if steam locking occurs and drain is no longer being properly discharged from steam trap 2, the temperature of drain piping 16 downstream of steam trap 2 will decrease over time.

Figure 2 is a graph showing, by curve x, the change over time in the detected temperature detected by the temperature sensor 41 installed in the drain pipe 16 downstream of the steam trap 2. As curve x shows, when steam locking occurs, the detected temperature drops, and eventually curve x falls below the low temperature threshold T1 at time P1. This low temperature threshold T1 is a value stored in advance in the controller 25, and is the temperature drop threshold at which it can be determined that steam locking has occurred.

At time P1 when the detected temperature reaches the low temperature threshold T1, the controller 25 sends an open signal to the cooling valve 45. This causes the cooling valve 45 to open, allowing industrial water to flow through the cooling pipe 20, and the coil portion 20a exchanges heat with the drain pipe 16 upstream of the steam trap 2. Because the industrial water is relatively low temperature, the drain pipe 16 is cooled by the heat exchange.

As the drain pipe 16 cools, the steam inside the drain pipe 16 or steam trap 2 that was causing the steam locking also releases heat, condenses, and liquefies, turning into drain. By turning the intervening steam into drain, the steam locking is resolved, high-temperature drain flows normally inside the drain pipe 16, and the discharge of high-temperature condensate from the steam trap 2 resumes.

As a result, the temperature of the drain pipe 16 downstream of the steam trap 2 rises and exceeds the high-temperature threshold value T2 at time P2, as shown by curve x in Figure 2. This high-temperature threshold value T2 is a value pre-stored in the controller 25, and is the temperature rise threshold at which it can be determined that steam locking has been resolved.

At time P2, when the detected temperature reaches the high temperature threshold T2, the controller 25 sends a valve closing signal to the cooling valve 45. This causes the cooling valve 45 to close, cutting off the flow of industrial water through the cooling pipe 20. Accordingly, cooling of the drain pipe 16 by the coil portion 20a also stops.

As described above, even if steam locking causes steam to get in and prevent condensate from being properly discharged from the steam trap 2, cooling by the coil portion 20a of the cooling pipe 20 condenses the steam in the condensate pipe 16 upstream of the steam trap 2 and in the steam trap 2, causing it to liquefy into condensate. Therefore, despite the simple configuration, steam locking can be reliably eliminated without causing steam loss.

[Other embodiments]
In the above-described embodiment, a float-type steam trap 2 is used as an example of a discharge valve, but this is not limited to this, and a valve with another configuration may be used as long as it discharges condensed water (drainage).

In addition, in the above-described embodiment, the cooling means and cooling path are exemplified as cooling pipes 20 having a coil portion 20a that encircles the drain pipe 16. However, this is not limited to this, and other shapes and structures can be used as long as they cool the flow path (e.g., drain pipe 16). For example, while an example has been shown in which the coil portion 20a of the cooling pipe 20 encircles the drain pipe 16 while being close to it, the coil portion 20a (cooling path) may also be configured to encircle the drain pipe 16 while being in contact with it. Furthermore, a straight pipe portion rather than a coil can be placed close to or in contact with the flow path (e.g., drain pipe 16) to cool the flow path (e.g., drain pipe 16).

In addition, while the cooling means and cooling path shown in the example is a water-cooled cooling pipe 20 using the flow of industrial water, the flow path (drain pipe 16, etc.) can also be cooled using a forced air cooling method in which a fan or other device is used to bring the flow of external air into contact with the cooling pipe.

Furthermore, in the above-described embodiment, an example was shown in which the drain pipe 16 (flow passage) upstream of the steam trap 2 (discharge valve) was cooled, but the discharge valve (steam trap 2, etc.) may also be cooled by arranging a cooling means (cooling pipe 20, etc.) in close proximity to or in contact with the discharge valve (steam trap 2, etc.).

In addition, in the above-described embodiment, the cooling valve 45, which is an electromagnetic valve, is used as the cooling path opening/closing valve, and the temperature sensor 41 is used as the temperature detection means, but these are not limited to these, and other configurations may also be used for each.

In addition, in the above-described embodiment, when steam locking occurs, a drop in the temperature of the drain pipe 16 is detected and the cooling valve 45 is opened to cool the drain pipe 16. However, steam locking may also be prevented by constantly flowing a cooling fluid (such as industrial water) through the cooling means and cooling path (such as the cooling pipe 20) to cool the pipe.

Furthermore, the steam locking elimination system according to the present application may be constructed by combining each of the above embodiments.

2: Steam trap 16: Drain pipe 20: Cooling pipe 41: Temperature sensor
45: Cooling valve

Claims (3)

A flow path through which condensed water generated from steam flows from upstream to downstream.
a discharge valve provided in the flow passage for discharging the condensed water downstream;
a cooling path for cooling the flow passage upstream of the discharge valve or the discharge valve, the cooling path having a cooling fluid flowing therethrough, the cooling path being disposed in contact with or in proximity to the flow passage upstream of the discharge valve or the discharge valve, and performing heat exchange with the flow passage upstream of the discharge valve or the discharge valve;
a cooling path on-off valve provided in the cooling path and performing an opening and closing operation to block or open the flow of the cooling fluid;
a temperature detection means for detecting the temperature of the flow passage downstream of the discharge valve;
It is equipped with
The cooling path opening/closing valve performs the opening/closing operation based on the temperature detected by the temperature detection means.
A steam locking elimination system characterized by the above . 2. The steam locking elimination system according to claim 1,
The cooling path has a coil portion that is wound around the flow passage upstream of the discharge valve in contact with or in close proximity to the flow passage.
A steam locking elimination system characterized by the above. In the steam locking elimination system according to claim 1 or 2,
The discharge valve is a steam trap.
A steam locking elimination system characterized by the above.