JP2015190726A - Flash steam generating device and boiler system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the back flow of steam to a flash steam generating device with a simple and inexpensive construction.SOLUTION: A flash steam generating device includes a flash tank 6 evaporating again drain recovered from a steam use facility on the upstream side to separate it into flash steam and hot water and supplying the flash steam to a steam use facility 4 on the downstream side, opening adjusting means 16 provided in a supply line 15 connecting the flash tank 6 and the steam use facility 4 on the downstream side and adjusting an opening thereof, tank pressure detecting means 14 for detecting a steam pressure in the flash tank 6, and control means 25 for increasing the opening of the opening adjusting means 16 when the pressure detected by the tank pressure detecting means 14 is larger than a set pressure.

Description

  The present invention relates to a flash steam generator and a boiler system.

  2. Description of the Related Art Conventionally, as a flash steam generation apparatus, a system in which drain from an upstream steam utilization facility is collected in a flash tank and the obtained flash steam is supplied to another steam utilization facility is known (Patent Document 1). reference).

  However, in the conventional flash steam generator, when supplying the generated flash steam to other steam utilization equipment, not only the flow rate adjusting valve but also the check valve must be passed, and the pressure is greatly reduced. End up. In other words, the pressure loss is large, so that a sufficient amount of steam cannot be supplied to other steam-using equipment, the supply of steam is delayed, or the so-called hunting phenomenon occurs where the flow control valve is frequently opened and closed. There is a fear. Further, not only the flow rate adjusting valve but also the check valve may cause a failure, and a countermeasure for that is necessary, and the cost is increased.

JP 2009-198038 A

  An object of the present invention is to prevent the backflow of steam to the flash steam generator with a simple and inexpensive configuration.

  As a means for solving the above problems, the present invention re-evaporates the drain recovered from the upstream steam utilization facility and separates it into flash steam and hot water, and supplies the flash steam to the downstream steam utilization facility. A flash tank, an opening adjusting means for adjusting the opening of the flush tank and a supply line connecting the flash tank and the downstream steam utilization facility, and tank pressure detection for detecting the vapor pressure in the flash tank And a control means for increasing the opening degree of the opening degree adjusting means when the pressure detected by the tank pressure detecting means is larger than a set pressure. .

  With this configuration, since the opening degree of the opening adjustment means is increased only when the vapor pressure in the flash tank is large, it is not frequently opened and closed, and the backflow of steam into the flash tank is prevented. Can do. Further, since the flash steam supplied from the flash tank only passes through the opening degree adjusting means, there is little pressure loss, and a desired amount can be smoothly supplied to the downstream steam utilization facility without causing a delay. it can.

  It further comprises a line pressure detecting means for detecting the pressure opposite to the flash tank with respect to the opening adjusting means, and the control means detects the pressure detected by the tank pressure detecting means at the line pressure detecting means. If the detected pressure exceeds the set value, it is preferable to increase the opening of the opening adjusting means.

  With this configuration, the backflow of steam to the flash tank can be more appropriately prevented.

  Further, the present invention provides, as means for solving the problems, a flash steam generator having the above-described configuration, a boiler that supplies steam to the upstream steam utilization facility, and the upstream steam utilization facility or the flash. There is provided a boiler system comprising a drain tank for storing drain discharged from a steam generator.

  According to the present invention, since the opening degree of the opening degree adjusting means is increased only when the vapor pressure in the flash tank is large, the opening degree adjusting means is not frequently opened and closed, Steam backflow can be prevented. In addition, since there is no need to provide a check valve, a simple and inexpensive configuration can be achieved, the number of faults can be reduced, pressure loss can be suppressed, and a desired amount of steam can be delayed. It becomes possible to supply smoothly without making it.

It is a schematic explanatory drawing of the boiler system which concerns on this embodiment. It is a flowchart which shows the operation | movement content in the boiler system of FIG.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings. In addition, the following description is only illustrations essentially and does not intend restrict | limiting this invention, its application thing, or its use. Further, the drawings are schematic, and the ratio of each dimension is different from the actual one.

  FIG. 1 shows a boiler system according to this embodiment. In this boiler system, steam generated in the boiler 1 is supplied to a high-pressure device 3 and a low-pressure device 4 which are steam utilization facilities via a steam header 2. The drain generated in the high-pressure device 3 is recovered to the flash steam generator 6 via the steam trap 5, and the generated flash steam is reused in the low-pressure device 4. Further, the drain from the low-pressure device 4 is directly collected in the drain tank 7 through the steam trap 11 and is returned to the boiler 1.

  For the boiler 1, for example, a multi-tube once-through boiler is used, and an economizer 8 is attached. The economizer 8 is an example of a heat exchanger for preheating (preheating) the water supplied to the boiler 1 with the exhaust gas from the boiler 1.

  The steam header 2 is provided to temporarily store the steam generated in the boiler 1 and supply the steam to the high-pressure device 3 and the low-pressure device 4.

  The high-pressure device 3 is configured by a heat exchanger or the like that uses the heat of the high-pressure steam supplied from the boiler 1 and makes the heat available to other devices.

  The low-pressure equipment 4 is constituted by a heat exchanger or the like that can use the heat of the low-pressure steam obtained by reducing the pressure of the high-pressure steam from the boiler 1 as well as the heat of the flash steam generated by the flash steam generator 6 in other equipment. Has been. A self-reducing pressure reducing valve 9 is provided in the middle of the path from the steam header 2 to the low pressure device 4. As a result, the supply steam to the low-pressure device 4 is adjusted to a low pressure (here, 0.3 MPa).

  The flash steam generator 6 is for supplying steam to the high-pressure equipment 3 from the boiler 1, recovering high-temperature drain (hot water) generated there, and reusing the flash steam generated from the drain.

  The flash steam generator 6 includes a flash tank 10. A first drain recovery line 12 extending from the high-pressure device 3 is connected to the flash tank 10. Then, the recovered drain is decompressed to generate flash vapor, which is supplied to the low-pressure device 4. Note that flash steam refers to a part of condensed water that becomes steam when high-temperature and high-pressure condensed water (also called condensate or drain water) is exposed to a low-pressure atmosphere. be called.

  Moreover, the flash steam generator 6 includes a water level sensor 13 and a first pressure sensor 14 which is a pressure detection means according to the present invention. The water level sensor 13 detects the water level of the drain stored in the flash tank 10. The first pressure sensor 14 detects the vapor pressure in the space above the flash tank 10. The detected water level at the water level sensor 13 and the detected pressure at the first pressure sensor 14 are output to the control device 25.

  Further, the flash steam generator 6 includes a first flow rate adjustment valve 16 and a second pressure sensor 17 which are opening degree adjusting means according to the present invention. The first flow rate adjusting valve 16 and the second pressure sensor 17 are provided in the middle of a supply line that connects the upper surface of the flash tank 10 and the low pressure device 4, that is, the steam supply line 15. The pressure detected by the second pressure sensor 17 is output to the control device 25.

  Further, the flash steam generator 6 includes a second flow rate adjustment valve 19. The second flow rate adjusting valve 19 is provided in the middle of the second drain recovery line 18 that connects the lower surface of the flash tank 10 and the drain tank 7. The opening degree of the second flow rate adjustment valve 19 is adjusted based on the detected water level in the water level sensor 13. That is, the control device 25 performs on / off control for opening and closing the second flow rate adjustment valve 19 based on the detected pressure from the water level sensor 13 so that the detected water level becomes a preset water level (set water level). . Of course, not limited to on / off control, proportional control in which linear control is performed so as to be within a preset range (set range) may be employed.

  The drain tank 7 is an open type open type, and the drain tank 7 and the economizer 8 are connected by a water supply line 20. In the middle of the water supply line 20, a water supply pump 21 and a first check valve 22 are provided in order from the drain tank 7 side. The drain tank 7 is connected to a pipe having a water pump 23 and a second check valve 24. If the amount of drain used is large and the water level in the drain tank 7 falls below the lower limit water level, the water pump 23 can be driven to supply water to the drain tank 7.

  As described below, the control device 25 adjusts the opening of the first flow rate adjustment valve 16 based on the pressure detected by the first pressure sensor 14 and the second pressure sensor 17, and the steam from the steam header 2. Is prevented from flowing back into the flash tank 10. Further, the opening of the second flow rate adjusting valve 19 is adjusted based on the detected water level at the water level sensor 13, and the drain in the flash tank 10 flows smoothly to the drain tank 7.

  Next, the operation | movement with the flash steam generator 6 of the boiler system which consists of the said structure is demonstrated.

  In the flash steam generator 6, the drain is recovered from the high-pressure device 3, and the flash steam is generated by reducing the pressure. Then, the steam from the boiler 1 is supplied to the low pressure device 4 through the steam header 2 in a predetermined low pressure state.

  First, the pressure detected by the first pressure sensor 14 is read (step S1). Further, the pressure detected by the second pressure sensor 17 is read (step S2). Then, the detected pressure (first detected pressure) in the first pressure sensor 14 and the detected pressure (second detected pressure) in the second pressure sensor 17 are compared. Here, a predetermined range (set range) is determined in advance as a value to be added to the second detected pressure, and it is determined whether or not the first detected pressure exceeds the upper limit value of the set range (step S3). .

  When the first detected pressure is larger than the upper limit value, the first flow rate adjustment valve 16 is opened, and the flash steam in the flash tank 10 is supplied to the low-pressure device 4 through the steam supply line 15 (step S4).

  On the other hand, when the first detected pressure is smaller than the lower limit value of the set range, the first flow rate adjusting valve 16 is closed to prevent the steam from the steam header 2 from flowing back to the flash tank 10 (step S5). .

  Note that the lower limit value of the setting range is preferably a value larger than zero. This is because if the value is 0 (same) or a value in the vicinity thereof, there is a risk that the steam flows back to the flash tank 10 due to the influence of the detection accuracy of the sensor. Moreover, frequent opening and closing of the first flow rate adjusting valve 16 is prevented by providing the setting range. That is, if the first detected pressure is within the set range, the first flow rate adjustment valve 16 maintains the previous state (open if open, closed if closed).

  Thus, in the steam supply line 15, the first flow rate adjustment valve 16 is opened only under the condition that the steam does not flow back to the flash tank 10, so there is no need to provide a check valve. For this reason, pressure loss can be suppressed, the cause of failure can be reduced, and the configuration can be simplified and manufactured at low cost. Furthermore, it can be easily adopted for existing facilities.

  In addition, this invention is not limited to the structure described in the said embodiment, A various change is possible.

  Although not mentioned in the above embodiment, the first drain recovery line 12 is not only connected to the flash tank 10 but also connected to the middle of the second drain recovery line 18 (downstream of the second flow rate adjustment valve 19). One bypass line may be provided. Thereby, it is possible to cope with an emergency such as a case where the drain water level in the flash tank 10 may rise rapidly.

  Moreover, you may make it the 1st drain collection line 12 provide the 2nd bypass line connected to the boiler 1 side. Thereby, it is possible to prevent the low-pressure drain from flowing into the flash tank 10, and it is possible to generate the flash vapor more effectively.

  In the embodiment, the opening degree of the first flow rate adjustment valve 16 is adjusted by comparing the first detection pressure and the second detection pressure. However, the first detection pressure and a preset pressure (setting) (Pressure) may be compared. Thereby, the control itself can be simplified by omitting the second pressure sensor 17.

  In addition, the opening of the first flow rate adjusting valve 16 is only opened or closed, but the opening increases stepwise or steplessly as this value increases according to the difference in the first detected pressure. It is also possible to adjust to.

  In the above embodiment, an open type open type is used for the drain tank 7, but the above configuration can be adopted even with a closed type sealed type.

DESCRIPTION OF SYMBOLS 1 ... Boiler 2 ... Steam header 3 ... High-pressure equipment 4 ... Low-pressure equipment (steam utilization equipment)
DESCRIPTION OF SYMBOLS 5 ... Steam trap 6 ... Flash steam generator 7 ... Drain tank 8 ... Economizer 9 ... Pressure-reducing valve 10 ... Flash tank 11 ... Steam trap 12 ... First drain collection line 13 ... Water level sensor 14 ... First pressure sensor (tank pressure detection) means)
15. Steam supply line (supply line)
16 ... 1st flow control valve (opening adjustment means)
17 ... Second pressure sensor (line pressure detection means)
DESCRIPTION OF SYMBOLS 18 ... 2nd drain collection line 19 ... 2nd flow regulating valve 20 ... Water supply line 21 ... Water supply pump 22 ... 1st check valve 23 ... Water supply pump 24 ... 2nd check valve 25 ... Control apparatus (control means)

Claims (3)

A flash tank for re-evaporating drain collected from the upstream steam utilization facility and separating it into flash steam and hot water, and supplying the flash steam to the downstream steam utilization facility;
An opening degree adjusting means for adjusting the opening degree provided in a supply line connecting the flash tank and the steam utilization facility on the downstream side;
Tank pressure detecting means for detecting the vapor pressure in the flash tank;
Control means for increasing the opening of the opening adjusting means when the detected pressure in the tank pressure detecting means is larger than a set pressure;
A flash steam generator characterized by comprising: Further comprising a line pressure detecting means for detecting the pressure opposite to the flash tank with respect to the opening adjusting means,
The control means increases the opening of the opening adjusting means when the detected pressure in the tank pressure detecting means is larger than the detected pressure in the line pressure detecting means exceeding a set value. The flash steam generator according to claim 1. The flash steam generator according to claim 1 or 2,
A boiler for supplying steam to the upstream steam utilization facility;
A drain tank for storing drain discharged from the upstream steam utilization facility or the flash steam generator;
A boiler system characterized by comprising

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