JP6975058B2 - Pressure drain recovery system - Google Patents

Description

The present invention is installed in a boiler system equipped with a flash tank for storing pressurized steam drain and a plurality of steam boilers, and the high-pressure steam generated in each steam boiler is used as a load device such as a heat exchanger. It relates to a pressure drain recovery system in which steam drain discharged from a load device is recovered without being released to the atmosphere and supplied to a predetermined steam boiler after being used in the above.

Generally, when the drain is recovered by a boiler with an exhaust gas economizer, that is, when the steam drain discharged from the load device is recovered and supplied to the boiler, the temperature of the boiler supply water W supplied to the boiler rises, so that the temperature of the boiler supply water W rises. The temperature of the discharged exhaust gas rises and the boiler efficiency decreases.

However, when drain recovery is performed, the amount of fuel used in the boiler can be significantly reduced, so that the efficiency of the boiler system as a whole can be improved. Further, by collecting the drain, it is possible to reduce the amount of make-up water and the amount of continuous blow, and it is economical to reduce the cost of water charges and chemical injection costs (see Non-Patent Document 1 and Non-Patent Document 2).

Conventionally, as a drain recovery system used for a boiler system, for example, those described in JP-A-2006-105442 (see Patent Document 1) and JP-A-2014-142114 (see Patent Document 2) are known. There is.

That is, although not shown, the drain recovery system described in Patent Document 1 includes a boiler that generates steam, a heat exchanger (load device) that discharges steam drain using the steam generated by the boiler, and a heat exchanger (load device). It is equipped with a drain tank that collects the steam drain discharged from the heat exchanger and a make-up water tank connected to the drain tank. When the amount of steam drain used is large and the water level in the drain tank becomes lower than the lower limit water level. When the amount of steam drain used is small and the water level in the drain tank becomes higher than the upper limit water level, the steam drain in the drain tank is replenished. I try to let it escape into the tank.

The drain recovery system has the advantage that it is possible to save energy and prevent the occurrence of cavitation because the high-temperature and high-pressure steam drain in the drain tank can be supplied to the boiler by a water supply pump. There is.

Further, although not shown, the drain recovery system described in Patent Document 2 is discharged from a boiler that generates steam, a load device that discharges steam drain using the steam generated by the boiler, and a load device. A flash tank that collects steam drain, a water level detector that detects the water level in the flash tank, a drain discharge valve that adjusts the amount of steam drain discharged from the flash tank, and a steam drain detected by the water level detector. It is equipped with a drain control device that controls the drain discharge valve based on the water level of the load device and the operation signal of the load device. I try to adjust the amount of drain.

Since the drain recovery system can discharge the steam drain from the flash tank according to the discharge status of the steam drain from the load device, the steam drain from the load device can be reliably discharged, and the steam drain can be discharged. There is an advantage that it is possible to suppress malfunction or decrease in efficiency of the load device due to stagnation.

However, since each of the drain recovery systems compensates for the shortage of boiler water supply by adding make-up water, the amount of steam supplied to the process side (load equipment side) is larger than the amount of steam drain. When a plurality of boilers are installed, it is necessary to add a large amount of make-up water to the steam drain, and as a result, the amount of heat retained in the boiler feed water decreases, which causes a problem of energy loss.

Further, when the steam drain is released to the make-up water tank, since the make-up water tank is an open type tank, flash steam is generated, which causes a problem of energy loss.

"Collection of Nomographs for Energy Conservation of Boilers", "7-1 Reduction of Fuel Consumption by Condensation Recovery", Japan Boiler Association, December 30, 2008, p. 134-135 Terushige Fujii, "Thermodynamic Effect of Drain Recovery in Boiler Steam Plants", "Boiler Research", Japan Boiler Association, October 2012, NO. 375, p. 10-16 Japanese Unexamined Patent Publication No. 2006-105442 Japanese Unexamined Patent Publication No. 2014-142114

The present invention has been made in view of such problems, and an object thereof is to steam the high energy of the pressure steam drain as it is regardless of the fluctuation of the pressure steam drain amount recovered from the load device. The purpose is to provide a pressure drain recovery system that can be supplied to the boiler.

In order to achieve the above object, the pressure drain recovery system according to claim 1 of the present invention includes a plurality of steam boilers that generate steam, a steam supply line that supplies the generated steam to a load device, and a load. The pressure drain recovery system is a pressure drain recovery system used in a boiler system equipped with a flash tank that recovers steam drain discharged from equipment without opening it to the atmosphere and stores the pressure steam drain. , The flash tank, the steam drain discharge line connecting the flash tank and the load equipment, and the flash tank and one steam boiler are connected to supply the pressurized steam drain in the flash tank to the one steam boiler. It is equipped with a pressurized drain supply line and a control unit that controls the fuel amount of the one steam boiler based on the boiler pressure of one steam boiler connected to the flash tank and the water level of the flash tank. , One steam boiler connected to the flash tank is a pressure drain recovery boiler that can output more evaporation than the pressure steam drain amount discharged from the load equipment, and the steam pressure set value of the pressure drain recovery boiler. Is set higher than the steam pressure of the steam supply line, and the pressure drain recovery boiler has a control output calculated from the boiler pressure of the pressure drain recovery boiler and a control output calculated from the water level of the flash tank. Among them, it is characterized in that the flow rate of the fuel is adjusted based on the control output of whichever is smaller.

The pressure drain recovery system according to claim 2 of the present invention comprises a plurality of steam boilers that generate steam, a steam supply line that supplies the generated steam to the load equipment, and a steam drain discharged from the load equipment. It is a pressure drain recovery system used for a boiler system provided with a flash tank that collects pressure steam drain without opening it to the atmosphere, and the pressure drain recovery system includes a flash tank and a flash tank. A steam drain discharge line connecting a load device, a pressure drain supply line connecting a flash tank and a plurality of steam boilers, and supplying the pressure steam drain in the flash tank to the plurality of steam boilers. A steam header that collects the steam generated by multiple steam boilers connected to the flash tank, and fuel for multiple steam boilers connected to the flash tank based on the steam pressure in the steam header and the water level of the flash tank. It is equipped with a control unit that controls the amount, and multiple steam boilers connected to the flash tank are used as pressure drain recovery boilers that can output more evaporation than the amount of pressure steam drain discharged from the load equipment. The steam pressure set value of each pressure drain recovery boiler is set higher than the steam pressure of the steam supply line, and each pressure drain recovery boiler has a control output calculated from the steam pressure of the steam header and a flash. It is characterized in that the flow rate of fuel is adjusted based on the smaller of the control outputs calculated from the water level of the tank.

In the pressure drain recovery system of the present invention, one or a plurality of steam boilers connected to the flash tank are used as a pressure drain recovery boiler capable of outputting an evaporation amount equal to or more than the pressure drain amount discharged from the load device. The steam pressure set value of the pressure drain recovery boiler is set higher than the steam pressure of the steam supply line, and the pressure drain recovery boiler is calculated from the boiler pressure of the pressure drain recovery boiler or the steam pressure of the steam header. The flow rate of the fuel is adjusted based on the smaller of the controlled output and the control output calculated from the water level of the flash tank.
That is, in the pressure drain recovery system of the present invention, since the pressure drain recovery boiler adjusts the fuel flow rate according to the water level of the flash tank, the pressure steam drain in the flash tank does not supply make-up water. Can be supplied to the pressure drain recovery boiler, and as a result, the high energy possessed by the pressure steam drain can be recovered without loss, and high system efficiency can be maintained.

Further, since the pressure drain recovery system of the present invention does not need to supply make-up water, the make-up water tank can be omitted, and the system can be simplified and the cost can be reduced. In particular, when the pressure drain recovery system of the present invention is installed in an existing boiler system that has a flash tank and a pressure steam drain but does not have a pressure drain recovery boiler and discards the pressure steam drain. , Capital investment can be relatively suppressed.

It is a schematic system diagram of the boiler system which installed the pressure drain recovery system which concerns on embodiment of this invention. It is a schematic system diagram of the boiler system which installed the pressure drain recovery system which concerns on other embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an example of a boiler system in which a pressure drain recovery system 1 according to an embodiment of the present invention is installed, and the boiler system includes a plurality of steam boilers 2A, 2B, ..., A load device 3, and a steam supply. The line L1, the fuel supply line L2, the boiler supply water supply line L3, and the pressure drain recovery system 1 are provided, and the steam drain D recovered from the load device 3 is transferred to one steam boiler 2A by the drain recovery system. I try to supply it.

Each of the steam boilers 2A, 2B, ... Burns fuel F (gas fuel such as city gas or liquid fuel such as heavy oil) to generate combustion gas, and the generated combustion gas causes the boiler bodies 2a, 2b, ... It is a combustion type boiler that heats and evaporates the pressurized steam drain D'and the boiler supply water W supplied inside to generate high-pressure steam.
For these steam boilers 2A, 2B, ..., For example, a once-through boiler, a furnace tube smoke tube boiler, a water pipe boiler and the like are used.

The load device 3 uses steam generated from each steam boiler 2A, 2B, ... As a heating source or a power source, and the load device 3 includes, for example, a steam turbine of a heat exchanger or the like or a power generation device. And so on.
The steam supplied to the load device 3 loses latent heat when passing through the load device 3, and a part of the steam is condensed to become a high-temperature and high-pressure steam drain D.

The steam supply line L1 supplies the steam S generated from each steam boiler 2A, 2B, ... To the load device 3, and the boiler main bodies 2a, 2b, ... Of each steam boiler 2A, 2B, ... And the load device. The steam supply pipe 4 connecting the steam boiler 2, the check valve 5 and the on-off valve 6 interposed in the steam supply pipe 4 on the outlet side of each steam boiler 2A, 2B, ..., And the appropriate position of the steam supply pipe 4 ( In this embodiment, the high pressure side pressure control valve 7 interposed in the steam supply pipe 4) located between the left steam boiler 2A and the right steam boiler 2B in FIG. 1 and the downstream of the high pressure side pressure control valve 7. It is equipped with a high-pressure steam pressure sensor 8 provided in the steam supply pipe 4 on the side.
The steam supply line L1 detects the steam pressure in the steam supply pipe 4 by the high-pressure steam pressure sensor 8, and based on this detection signal, the steam pressure is maintained at the set pressure by the control output from the arithmetic unit 9a. The high pressure side pressure control valve 7 is controlled.

The fuel supply line L2 supplies fuel F to the steam boilers 2A, 2B, ..., And fuels connecting the fuel tank (not shown) and the burners (not shown) of the steam boilers 2A, 2B, ... A supply pipe 10 and a fuel flow rate adjusting valve 11 and an on-off valve 12 interposed in a fuel supply pipe 10 in the vicinity of each of the steam boilers 2A, 2B, ... Are provided.
In this fuel supply line L2, except for one steam boiler 2A (steam boiler 2A on the left side of FIG. 1), the boiler pressure is increased by the boiler main body steam pressure sensor 13 provided in the boiler main body 2b of each steam boiler 2B, ... Is detected, and the fuel flow control valve 11 is controlled by the control output from the calculator 9b so that the boiler pressure becomes the boiler pressure set by the calculator 9b based on this detection signal, and the fuel amount is adjusted. ing.

The boiler supply water supply line L3 supplies boiler water supply W to the boiler main body 2b, ... Of each steam boiler 2B, ... Except for one steam boiler 2A (steam boiler 2A on the left side of FIG. 1). It is provided with a boiler water supply pipe 14 for connecting a water supply tank (not shown) and a boiler main body 2b, ... Of each steam boiler 2B, ..., A water supply pump 15 and an on-off valve 16 interposed in the boiler water supply pipe 14.
In this boiler water supply line L3, except for one boiler 2A (steam boiler 2A on the left side of FIG. 1), the boiler water level is determined by the boiler body water level sensor 17 provided in the boiler body 2b, ... of each steam boiler 2B, ... Is detected, and the water supply pump 15 is controlled by the control output from the calculator 9c so that the boiler water level becomes the boiler water level set by the calculator 9c based on this detection signal, and the boiler water supply amount is adjusted. There is.

In this embodiment, the boiler water supply amount is adjusted by controlling the rotation speed of the electric motor of the water supply pump 15 by an inverter, but the boiler water supply W amount may be adjusted by controlling the water supply control valve or the like. good.

Further, as the water supply control method, continuous water supply, ON-OFF water supply, or multi-position water supply may be used, but in this embodiment, continuous water supply is adopted because it is difficult to disturb the water level of the flash tank 18. doing.

The pressurized drain recovery system 1 includes a flash tank 18, a steam drain discharge line L4 connecting the flash tank 18 and the load device 3, a low pressure steam discharge line L5 connected to the flash tank 18, and a flash tank 18. It is connected to the flash tank 18 based on the pressure drain supply line L6 connecting one steam boiler 2A, the boiler pressure of one steam boiler 2A connected to the flash tank 18, and the water level of the flash tank 18. A control unit 19 for controlling the fuel amount of one steam boiler 2A is provided, and one steam boiler 2A connected to the flash tank 18 is used as a pressure drain recovery boiler.

Specifically, the flash tank 18 collects the steam drain D discharged from the load device 3 without opening it to the atmosphere and stores it as a pressure steam drain D'in the flash tank 18. , A flash tank water level sensor 20 for detecting the water level in the flash tank 18 is provided.
In the flash tank 18, low-pressure steam S'is generated from the steam drain D recovered in the flash tank 18.

The steam drain discharge line L4 supplies the steam drain D discharged from the load device 3 to the flash tank 18, and the steam drain discharge pipe 21 connecting the load device 3 and the flash tank 18 and the steam drain discharge. The pipe 21 is provided with a steam trap 22 that allows only the drain of the steam drain D discharged from the load device 3 to pass through.

The low pressure steam discharge line L5 keeps the pressure in the flash tank 18 at a set pressure, and when the pressure in the flash tank 18 becomes higher than the set pressure, the low pressure steam S'in the flash tank 18 becomes a low pressure steam line. A low-pressure steam discharge pipe 23 connected to the flash tank 18, a low-pressure steam pressure control valve 24 interposed in the low-pressure steam discharge pipe 23, and a flash tank steam pressure sensor provided in the low-pressure steam discharge pipe 23. It has 25 and.
The low pressure steam discharge line L5 detects the pressure in the flash tank 18 by the flash tank steam pressure sensor 25, and based on this detection signal, the pressure in the rush tank 18 is maintained at the set pressure from the calculator 9d. The low-pressure steam pressure control valve 24 is controlled by the control output of the above to supply the low-pressure steam S'in the flush tank 18 to the low-pressure steam supply line.

The pressure drain supply line L6 supplies the pressure steam drain D'in the flash tank 18 to one steam boiler 2A, and connects the flash tank 18 and the boiler body 2a of the one steam boiler 2A. The pressure drain supply pipe 26 to be connected, the pressure steam drain water supply pump 27 interposed in the pressure drain supply pipe 26, the booster pump 28 interposed in the pressure drain supply pipe 26, and the pressure drain supply pipe. It is provided with an on-off valve 29 interposed above the 26.
The pressure drain supply line L6 detects the boiler water level by the boiler body water level sensor 17 provided in the boiler body 2a of one steam boiler 2A, and the boiler water level is set by the calculator 9e based on this detection signal. The water supply pump 27 for pressure steam drain is controlled by the control output from the arithmetic unit 9e so that the water level becomes the boiler, and the pressure steam drain amount is adjusted.

One steam boiler 2A connected to the pressurized drain supply line L6 is a pressurized drain recovery boiler, and in addition to the boiler main body water level sensor 17, the boiler main body steam pressure sensor 13 that detects the boiler pressure Is provided.

The control unit 19 controls the fuel amount of one steam boiler 2A (pressured drain recovery boiler) based on the boiler pressure of one steam boiler 2A (pressured drain recovery boiler) and the water level of the flash tank 18. This is to be provided in the arithmetic unit 9f and the flash tank 18 in which the detection signal from the boiler main body steam pressure sensor 13 provided in one steam boiler 2A (pressured drain recovery boiler) is input and the control signal is output. A calculator 9g to which a detection signal from the flash tank water level sensor 20 is input and output a control signal, and a control signal output from the two boilers 9f and 9g are input respectively, and one of the boilers 9f is used. It is equipped with an output selector 30 that selects and outputs the lower of the control output set to the set boiler pressure and the control output set to the flash tank water level set by the other calculator 9g. ..
The control unit 19 controls the fuel flow rate adjusting valve 11 provided in one steam boiler 2A (pressured drain recovery boiler) based on the control output from the output selector 30 to adjust the fuel amount. ..

In the boiler system provided with the pressure drain recovery system 1 described above, the pressure settings are as follows (1) and (2).
(1) P1a> P2 >> P3
(2) P1b> P2
Here, P1a is the set pressure of one steam boiler 2A (pressured drain recovery boiler), P2 is the set pressure of the high pressure steam of the steam supply line L1, and P3 is the set pressure of the low pressure steam S'of the low pressure steam discharge line L5. , P1b are the set pressures of the other steam boilers 2B ,.

Further, in this boiler system, the relationship between the pressure steam drain amount and the rated steam generation amount of the pressure drain recovery boiler is as follows.
Pressure steam drain amount <Pressurized drain recovery boiler rated steam generation amount

Therefore, in the boiler system provided with the pressure drain recovery system 1 described above, the flow rate adjustment of the fuel F of each steam boiler 2A, 2B, ... Is performed as follows.

That is, except for one steam boiler 2A which is a pressurized drain recovery boiler, each of the other steam boilers 2B, ... Detects the boiler pressure by the boiler main body steam pressure sensor 13 provided in the boiler main body 2b, ... The fuel flow rate adjusting valve 11 is controlled by the control output from the calculator 9b so that the boiler pressure becomes the boiler pressure set by the calculator 9b based on the detection signal, and the fuel amount is adjusted.

On the other hand, one steam boiler 2A, which is a pressure drain recovery boiler, has a control output set to be the boiler pressure set by one calculator 9f of the control unit 19 and the other calculator 9g of the control unit 19. Of the control outputs set in the flash tank water level, the lower one is selected by the output selector 30 of the control unit 19, and the fuel flow control valve 11 is controlled by the selected control output to adjust the fuel amount. I am doing it.

When the steam load is sufficient, the boiler pressure of one steam boiler 2A serving as the pressure drain recovery boiler becomes lower than the set pressure P1a of the steam boiler 2A, and the set pressure P2 of the high pressure steam of the steam supply line L1. Therefore, the control output from the calculator 9f of the control unit 19 is always 100%, but when the flash tank water level is lower than the set water level, the control output from the boiler 9g of the controller 19 Becomes smaller. As a result, in the output selector 30 of the controller 19, the smaller control output (control output from the arithmetic unit 9g) is selected, the fuel flow rate is adjusted by the selected control output, and the steam boiler 2A is used. Since the amount of steam output is suppressed, as a result, the amount of pressure steam drain supplied to one steam boiler 2A (pressured drain recovery boiler) can be suppressed.

As described above, the fuel flow rate of one steam boiler 2A, which is usually a pressure drain recovery boiler, is controlled with priority given to the flush tank water level becoming the set water level. Therefore, the amount of steam generated by one steam boiler 2A (pressured drain recovery boiler) fluctuates regardless of the steam load, but in this pressure drain recovery system 1, one steam boiler 2A (pressured drain recovery boiler) The fluctuations in the amount of steam generated by the pressure drain recovery boiler) and the fluctuations in the amount of steam consumed by the load device 3 can be followed by the high-pressure side pressure control valve 7 and other steam boilers 2B, ....

In addition, if the boiler pressure of one steam boiler 2A (pressured drain recovery boiler) rises due to a sudden load reduction or an operation error of the low pressure steam pressure control valve 24, the control output from the controller 19 will be changed. When it becomes smaller than 100% and further smaller than the control output by the flash tank water level of the calculator 9g of the controller 19, the fuel flow rate can be adjusted by the control output from the boiler 9f. It is also possible to protect the steam boiler 2A (pressured drain recovery boiler) from an increase in boiler pressure.

As described above, in the pressure drain recovery system 1, one steam boiler 2A serving as the pressure drain recovery boiler adjusts the flow rate of the fuel F according to the water level of the flash tank 18, so that the make-up water is supplied. The pressure steam drain D'in the flash tank 18 can be supplied to one steam boiler 2A which is a pressure drain recovery boiler, and as a result, the high energy possessed by the pressure steam drain D'can be supplied. It can be recovered without loss, and high system efficiency can be maintained.

Further, in the boiler system provided with the above-mentioned pressure drain recovery system 1, the boiler water level control of each steam boiler 2A, 2B, ... Is controlled by the pressure drain supply line L6, the boiler supply water supply line L3, and the boiler body water level sensor 17. , The arithmetic unit 9c and the arithmetic unit 9e, respectively.

That is, the boiler water level control of each steam boiler 2A, 2B, ... Detects the boiler water level by the boiler main body water level sensor 17 provided in the boiler main body 2a, 2b, ... Of each steam boiler 2A, 2B, ..., And this detection is performed. The water supply pump 15 and the water supply pump 27 for pressure steam drain are controlled by the control output from the arithmetic unit 9c and the arithmetic unit 9e so that the boiler water level becomes the boiler water level set by the arithmetic unit 9c and the arithmetic unit 9e based on the signal. However, the amount of boiler water supply and the amount of pressurized steam drain are adjusted.

This boiler water level control is the same as the conventional control method, and one steam boiler 2A, which is a pressure drain recovery boiler, is not directly related to the flash tank water level, but follows the fluctuation of the flash tank water level. Since the fuel flow rate is also changing, the amount of water supply (pressured steam drain amount) is also changing.

Further, the low pressure steam pressure control in the flash tank 18 is designed so that the pressure in the flash tank 18 is maintained at the set pressure, and when the pressure in the flash tank 18 becomes higher than the set pressure, the flash tank steam pressure sensor. 25 detects this and controls the low pressure steam pressure control valve 24 based on this detection signal so that the low pressure steam S'in the flush tank 18 is supplied to the low pressure steam line.

FIG. 2 shows a boiler system in which a pressurized drain recovery system 1 according to another embodiment of the present invention is installed, and the boiler system includes a plurality of steam boilers 2A, 2B, 2C, ..., A load device 3, and the like. The steam supply line L1, the fuel supply line L2, the boiler supply water supply line L3, and the pressure drain recovery system 1 are provided, and the pressure steam drain D'recovered from the load device 3 is collected from the pressure drain recovery system 1. The steam boilers 2A and 2B are supplied to a plurality of steam boilers 2A and 2B.
In this embodiment, the pressure steam drain D'is supplied to the two steam boilers 2A and 2B, and the two steam boilers 2A and 2B are used as the pressure drain recovery boilers.

Further, in this boiler system, steam S generated from two steam boilers 2A and 2B, which are pressure drain recovery boilers, is once merged with the steam header 31. The steam header 31 is provided with a boiler steam pressure sensor 32 so that the fuel flow rates of the two steam boilers 2A and 2B, which are the pressure drain recovery boilers, can be adjusted at the same time.

The boiler system shown in FIG. 2 has the same structure as the boiler system shown in FIG. 1 except for two steam boilers 2A and 2B which are pressure drain recovery boilers and the pressure drain recovery system 1.
That is, each steam boiler 2C of the boiler system shown in FIG. 2, the load device 3, the fuel supply line L2 and the boiler supply water supply line L3 are the steam boiler 2B of the boiler system shown in FIG. 1, the load device 3, the fuel. It has the same structure as the supply line L2 and the boiler water supply line L3, and the same parts / members as those in FIG. 1 are designated by the same reference number, and detailed description thereof will be omitted.

In the two steam boilers 2A and 2B serving as the pressure drain recovery boilers, the generated steam S is once collected from the steam supply pipe 4 to the steam header 31, and the load equipment is provided from the steam header 31 via the steam supply pipe 4. It is designed to be supplied to 3. The steam header 31 is provided with a boiler steam pressure sensor 32.

The pressure drain recovery system 1 includes a flash tank 18, a steam drain discharge line L4 connecting the flash tank 18 and the load device 3, a low-pressure steam discharge line L5 connected to the flash tank 18, and a flash tank 18. The pressure drain supply line L6 connecting the two steam boilers 2A and 2B, and the two steam boilers 2A connected to the flash tank 18 based on the steam pressure of the steam header 31 and the water level of the flash tank 18. A control unit 19 for controlling the amount of fuel in 2B is provided, and two steam boilers 2A and 2B connected to the flash tank 18 are used as pressure drain recovery boilers.

The pressure drain recovery system 1 has the same structure as the pressure drain recovery system 1 shown in FIG. 1 except for the pressure drain supply line L6 and the control unit 19.
That is, the flash tank 18, the steam drain discharge line L4, and the low-pressure steam discharge line L5 of the pressure drain recovery system 1 have the same structure as the flash tank 18, the steam drain discharge line L4, and the low-pressure steam discharge line L5 shown in FIG. Since it is configured, detailed description thereof will be omitted here. The same reference numbers are assigned to the same parts / members as in FIG.

The pressure drain supply line L6 supplies the pressure steam drain D'in the flash tank 18 to the two steam boilers 2A and 2B which are the pressure drain recovery boilers, and the flash tank 18 and the two units. Pressure drain supply pipe 26 connecting the boiler bodies 2a and 2b of the steam boilers 2A and 2B (pressured drain recovery boiler) and water supply for pressure steam drain installed at the branch of the pressure drain supply pipe 26, respectively. A pump 27, a booster pump 28 interposed in the upstream portion of the pressure drain supply pipe 26, and an on-off valve 29 interposed in a branch portion of the pressure drain supply pipe 26 are provided.

The control unit 19 controls the fuel amount of the two steam boilers 2A and 2B (pressured drain recovery boilers) based on the steam pressure of the steam header 31 and the water level of the flash tank 18, and the steam header 31 An arithmetic unit 9f in which a detection signal from the boiler steam pressure sensor 32 provided in the above is input and a control signal is output, and a calculation in which a detection signal from a flash tank water level sensor provided in the flash tank 18 is input and a control signal is output. The control signals output from the unit 9g and the two arithmetic units 9f and 9g are input, respectively, and the control output is set so that the steam pressure is set by one arithmetic unit 9f and the other arithmetic unit 9g. It is provided with an output selector 30 that selects and outputs the lower of the control outputs so that the water level of the flash tank is reached.
The control unit 19 controls the fuel flow control valves 11 provided in the two steam boilers 2A and 2B (pressured drain recovery boilers) based on the control output from the output selector 30, and the two steam boilers 2A, The amount of fuel in 2B is adjusted at the same time.

The boiler system shown in FIG. 2 can also have the same effect as the boiler system shown in FIG.

1 is a pressure drain recovery system 2A, 2B, 2C, ... is a steam boiler 3 is a load device D is a steam drain D'is a pressure steam drain 18 is a flash tank 19 is a control unit 31 is a steam header L1 is a steam supply line L4 Is a steam drain discharge line L6 is a pressure steam supply line S is steam

Claims (2)

Multiple steam boilers that generate steam, a steam supply line that supplies the generated steam to the load equipment, and the steam drain discharged from the load equipment is recovered without opening to the atmosphere and the pressurized steam drain is stored. A pressure drain recovery system used for a boiler system including a flash tank, wherein the pressure drain recovery system includes a flash tank, a steam drain discharge line connecting the flash tank and a load device, a flash tank, and 1 A pressure drain supply line that connects to one steam boiler and supplies the pressurized steam drain in the flash tank to the one steam boiler, and the boiler pressure and flush of one steam boiler connected to the flash tank. It is equipped with a control unit that controls the fuel amount of the one steam boiler based on the water level of the tank, and one steam boiler connected to the flash tank is discharged from the load equipment under pressure steam drain. A pressure drain recovery boiler capable of outputting an amount of evaporation equal to or greater than the amount is used, the steam pressure set value of the pressure drain recovery boiler is set higher than the steam pressure of the steam supply line, and the pressure drain recovery boiler is present. It is characterized in that the flow rate of fuel is adjusted based on the smaller of the control output calculated from the boiler pressure of the pressure drain recovery boiler and the control output calculated from the water level of the flash tank. Pressure drain recovery system. Multiple steam boilers that generate steam, a steam supply line that supplies the generated steam to the load equipment, and the steam drain discharged from the load equipment is recovered without opening to the atmosphere and the pressurized steam drain is stored. It is a pressure drain recovery system used for a boiler system equipped with a flash tank, and the pressure drain recovery system includes a flash tank, a steam drain discharge line connecting the flash tank and a load device, and a plurality of flash tanks. The pressure drain supply line that connects the steam boilers and supplies the pressure steam drain in the flash tank to the multiple steam boilers, and the steam generated by the multiple steam boilers connected to the flash tank. It is equipped with a steam header that collects the fuel and a control unit that controls the fuel amount of multiple steam boilers connected to the flash tank based on the steam pressure in the steam header and the water level of the flash tank, and is connected to the flash tank. The multiple steam boilers are used as pressure drain recovery boilers that can output more evaporation than the pressure steam drain amount discharged from the load equipment, and the steam pressure set value of each pressure drain recovery boiler is steam supply. The pressure drain recovery boiler, which is set higher than the steam pressure of the line, is the smaller of the control output calculated from the steam pressure of the steam header and the control output calculated from the water level of the flash tank. A pressurized drain recovery system characterized by adjusting the flow rate of fuel based on the control output of.

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