JP6075016B2 - Boiler system - Google Patents

Description

  The present invention relates to a boiler system. More specifically, the present invention relates to a closed boiler system that collects drain discharged from load equipment without supplying it to the atmosphere and supplies water to the boiler.

  Conventionally, steam generated by a boiler is supplied to the load equipment, and the drain generated by condensation of the steam used as a heat source in the load equipment is collected in a sealed drain tank with pressure resistance at high temperature and pressure. And the closed-type boiler system which supplies water to a boiler again is known (for example, refer patent document 1).

JP 2006-105442 A

By the way, in a closed boiler system, a steam trap that discharges drainage and prevents steam from being discharged to a drain supply line that connects a load device and a drain tank and supplies the drain from the load device to the drain tank. Is placed.
Here, since a pressure difference is generated before and after the steam trap in the drain supply line, flush steam is generated from the drain due to a decrease in pressure in the drain discharge line located downstream of the steam trap.
Therefore, in order to condense the flash vapor generated in the drain discharge line, fresh water is supplied to the drain tank on the downstream side of the drain discharge line. In this case, since the flash steam is cooled with fresh water, the heat recovery rate of the entire boiler system is reduced.

  The present invention is to solve the above-mentioned problems, and provides a closed boiler system that prevents the generation of flash steam in a drain supply line in which a steam trap is arranged and further improves the heat recovery rate. The purpose is to do.

  The present invention includes a boiler that generates steam and supplies the generated steam to a load device, and supplies the drain that is generated when the load device condenses by using the steam from the load device. The first drain supply line, the drain tank that collects the drain that flows through the first drain supply line without opening it to the atmosphere, the drain tank and the boiler connected to each other, and the drain accommodated in the drain tank is A second drain supply line for supplying water to the boiler, an evaporator for exchanging heat between the drain and refrigerant flowing through the first drain supply line, and heat between the refrigerant heated by the evaporator and water A heat pump having a condenser for generating steam by exchanging; a steam supply line for supplying steam generated by the condenser to the load device; and a first drain supply line. A steam trap disposed in the evaporator downstream of that relates boiler system of closed type comprising a.

  The boiler system preferably further includes an open tank that stores makeup water supplied to the boiler, and a makeup water supply line that supplies makeup water stored in the open tank to the condenser.

  Moreover, it is preferable that a boiler system is further equipped with the 3rd drain supply line which supplies the drain collect | recovered by the said drain tank to the said condenser.

  According to the boiler system of the present invention, it is possible to prevent the generation of flash steam in the drain supply line in which the steam trap is arranged, and to further improve the heat recovery rate.

It is a figure showing composition of a boiler system concerning a 1st embodiment of the present invention. It is a vertical direction sectional view of the can of a once-through boiler. It is the sectional view on the AA line of FIG. It is a figure which shows the structure of the boiler system which concerns on 2nd Embodiment of this invention.

(First embodiment)
Hereinafter, preferred embodiments of the boiler system of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of a boiler system 1 according to the first embodiment of the present invention.
As shown in FIG. 1, the boiler system 1 of the present embodiment includes a boiler device 70 that includes a plurality of once-through boilers 10, a closed drain recovery device 20, and a heat pump 80.

  As shown in FIG. 1, the boiler device 70 connects a plurality of once-through boilers 10, a steam header 71 where steam generated by the plurality of once-through boilers 10 is collected, and a plurality of once-through boilers 10 and the steam header 71. First connecting pipe 72.

  The once-through boiler 10 generates steam by heating the feed water supplied to the inside with combustion gas. In the present embodiment, the drain recovered by the drain recovery device 20 is supplied to the once-through boiler 10 as feed water. The steam generated in the plurality of once-through boilers 10 is supplied to the steam header 71 through the first connection pipe 72.

The steam header 71 stores the steam generated by the plurality of once-through boilers 10 and supplies the steam to the load device 50.
The load device 50 uses the steam generated by the once-through boiler 10 as a heat source, and performs heat exchange with the object to be heated.

The drain recovery device 20 recovers the drain generated by condensing the steam generated by the once-through boiler 10 in the load device 50 in a high-temperature and high-pressure state, and again uses the recovered drain as feed water to return to the once-through boiler. 10 is supplied.
The drain recovery device 20 includes a drain tank 21, an open tank 22, a first steam supply line L1, a first drain supply line L2, a second drain supply line L3, a second steam supply line L4, and flash steam. A discharge line L5 and a makeup water supply line L6 are provided.

  The drain tank 21 collects and stores the drain generated by condensation of a part of the steam used for heat exchange in the load device 50. The drain tank 21 is constituted by a pressure vessel that has pressure resistance and can be sealed.

  The open tank 22 is open to the atmosphere. The open tank 22 stores makeup water supplied to the once-through boiler 10. Further, the open tank 22 is introduced with flash steam generated from the drain in the drain tank 21.

  The first steam supply line L <b> 1 connects the steam header 71 and the load device 50, and supplies the steam generated by the once-through boiler 10 to the load device 50.

The first drain supply line L <b> 2 connects the load device 50 and the drain tank 21, and supplies the drain generated in the load device 50 to the drain tank 21. In the first drain supply line L2, an evaporator 85 of a heat pump 80 to be described later, a steam trap 61, a check valve 62, and a motor valve 63 are arranged in this order from the upstream side.
The steam trap 61 operates in a state where there is a pressure difference between the front and rear in the first drain supply line L2, discharges the drain generated in the load device 50, and prevents the steam from being discharged. The check valve 62 prevents the backflow of drain supplied from the load device 50 to the drain tank 21. The motor valve 63 adjusts the amount of drain supplied from the load device 50 to the drain tank 21.

The second drain supply line L3 connects the drain tank 21 and the once-through boiler 10, and supplies the drain accommodated in the drain tank 21 to the once-through boiler 10. The upstream end of the second drain supply line L3 is connected to the lower portion of the drain tank 21. Further, the downstream side of the second drain supply line L3 is branched so as to be connected to each of the plurality of cans 11.
A drain pump 64 and a drain supply valve 65 are disposed in the second drain supply line L3. The drain pump 64 boosts the drain supplied from the drain tank 21 and supplies it to the once-through boiler 10. The drain supply valve 65 is constituted by a motor valve and adjusts the amount of drain supplied from the drain tank 21 to the once-through boiler 10.

The second steam supply line L4 connects the steam header 71 and the drain tank 21. The second steam supply line L4 supplies the steam stored in the steam header 71 to the drain tank 21 and adjusts the pressure inside the drain tank 21.
A pressure adjustment valve 66 and a motor valve 67 are disposed in the second steam supply line L4.

The flash steam discharge line L5 connects the drain tank 21 and the open tank 22, and discharges the flash steam generated in the drain tank 21 to the open tank 22.
A pressure regulating valve 68 is disposed in the flash steam discharge line L5. When the pressure inside the drain tank 21 exceeds a predetermined pressure, the pressure regulating valve 68 releases the flash vapor to the open tank 22 side and reduces the pressure inside the drain tank 21.

The makeup water supply line L <b> 6 connects the open tank 22 and the drain tank 21, and supplies water stored in the open tank 22 to the drain tank 21.
A pump 69 is disposed in the makeup water supply line L6. The pump 69 boosts the makeup water supplied from the open tank 22 and supplies it to the drain tank 21.

Next, details of the once-through boiler 10 will be described.
FIG. 2 is a vertical sectional view of the can 11 of the once-through boiler 10. 3 is a cross-sectional view taken along line AA in FIG. 2 and is a horizontal cross-sectional view of the can 11.
As shown in FIGS. 2 and 3, the once-through boiler 10 includes a can body 11, a plurality of water pipes 12, a connecting wall 13, a lower header 14, an upper header 15, a duct 16, a burner 17, And a cylinder 18.

The can body 11 is configured in a rectangular parallelepiped shape in a plan view.
The plurality of water pipes 12 are arranged extending in the vertical direction inside the can body 11 and are arranged at predetermined intervals in the longitudinal direction and the width direction of the can body 11.
In the present embodiment, the plurality of water tubes 12 are disposed along the longitudinal direction at the outer water tube group 12 a disposed along the side portion extending in the longitudinal direction of the can body 11 and at the center portion in the width direction of the can body 11. The central water pipe group 12b and the intermediate water pipe group 12c disposed between the outer water pipe group 12a and the central water pipe group 12b are classified.
The connection wall 13 connects the water pipes 12 arranged adjacent to each other in the outer water pipe group 12a.

  The lower header 14 is configured by a rectangular parallelepiped container having a rectangular shape in plan view, and is disposed at the lower portion of the can 11. The lower header 14 is connected to lower ends of the plurality of water pipes 12. Drain is supplied to the lower header 14 from the drain recovery device 20, and drain is supplied from the lower header 14 to the plurality of water pipes 12.

  The upper header 15 is configured by a rectangular parallelepiped container having a rectangular shape in plan view, and is disposed on the upper portion of the can body 11. The upper header 15 is connected to the upper ends of the plurality of water pipes 12. Steam generated in the plurality of water pipes 12 is collected in the upper header 15. A first connecting pipe 72 (see FIG. 1) is connected to the upper header 15, and the steam collected in the upper header 15 is supplied to the steam header 71 through the first connecting pipe 72.

  The duct 16 is connected to a lower portion of the first side surface 11 a located on one end side in the longitudinal direction of the can body 11. On the upstream side of the duct 16, a fuel supply unit 161 to which fuel gas is supplied and an air supply line to which combustion air (not shown) is supplied are connected. The duct 16 mixes the fuel gas supplied from the fuel supply unit 161 and the combustion air supplied from the air supply line and supplies the mixed gas toward the inside of the can 11.

  The burner 17 is arrange | positioned in the connection part of the duct 16 and the can 11 in the 1st side surface 11a. The burner 17 ejects a mixed gas in which combustion air and fuel are mixed from the duct 16 into the can 11 and burns the mixed gas.

  The exhaust cylinder 18 is connected to the second side surface 11b located on the other end side in the longitudinal direction of the can body 11 (the side opposite to the side where the duct 16 is provided). The exhaust cylinder 18 discharges the combustion gas generated by burning the mixed gas inside the can 11.

Next, returning to FIG. 1, the heat pump 80 will be described.
The heat pump 80 is a vapor compression heat pump, and collects the heat of the drain by a refrigerant and generates steam from the makeup water using the heat collected by the refrigerant.
The heat pump 80 includes a second makeup water supply line L7, a second connection pipe (steam supply line according to the present invention) 81, a compressor 82, a condenser 83, an expansion valve 84, and an evaporator 85. Prepare.
Here, the compressor 82, the condenser 83, the expansion valve 84, and the evaporator 85 are connected in an annular shape. And a refrigerant | coolant circulates in the gaseous state or the liquid state through the compressor 82, the condenser 83, the expansion valve 84, and the evaporator 85 which were connected annularly.
As the refrigerant used for the heat pump 80, for example, a hydrofluorocarbon having 4 or more carbon atoms added with water or a fire extinguishing liquid, or a mixture of ethyl alcohol or methyl alcohol with water or a digestive liquid is preferably used.

The second makeup water supply line L7 connects the open tank 22 and the condenser 83, and supplies makeup water stored in the open tank 22 to the condenser 83.
A makeup water pump 86 and a makeup water supply valve 87 are disposed in the second makeup water supply line L7. The makeup water pump 86 boosts the makeup water supplied from the open tank 22 and supplies it to the condenser 83. The makeup water supply valve 87 is constituted by a motor valve and adjusts the amount of makeup water supplied from the open tank 22 to the condenser 83.

  The second connecting pipe 81 connects the condenser 83 and the steam header 71, and supplies the steam generated by the condenser 83 to the steam header 71.

The compressor 82 compresses the gaseous refrigerant to increase the temperature and pressure.
The compressor 82 includes, for example, a main body portion and a motor, and adjusts the amount of refrigerant compressed in the main body portion by controlling the motor with an inverter.

The condenser 83 is disposed between the second makeup water supply line L7 and the second connection pipe 81. The condenser 83 radiates the heat of the refrigerant supplied from the compressor 82 to the make-up water supplied from the second make-up water supply line L7 to generate steam from the make-up water, and condenses the gaseous refrigerant. Liquefy.
The steam generated from the makeup water in the condenser 83 is supplied to the steam header 71 through the second connection pipe 81.
As the condenser 83, for example, a plate heat exchanger, a shell and tube heat exchanger, or the like is used.

The expansion valve 84 is configured by a throttle valve. The expansion valve 84 allows the liquid refrigerant supplied from the condenser 83 to pass therethrough, thereby reducing the pressure and temperature of the refrigerant.
The evaporator 85 is disposed upstream of the steam trap 61 in the first drain supply line L2, and vaporizes the refrigerant supplied from the expansion valve 84 by removing heat from the drain.
As the evaporator 85, for example, a plate heat exchanger, a shell and tube heat exchanger, or the like is used.

  In the heat pump 80 having the above configuration, the refrigerant removes heat from the drain circulating in the first drain supply line L2 in the evaporator 85 and vaporizes, while the refrigerant is supplied in the condenser 83 from the second makeup water supply line L7. The make-up water is heated to produce steam.

Next, operation | movement of the boiler system 1 of this embodiment is demonstrated.
In the present embodiment, first, steam is generated in the once-through boiler 10. Specifically, first, the fuel gas and the combustion air are mixed in the duct 16, and the mixed gas of the combustion gas and the combustion air is ejected from the burner 17 into the inside of the can body 11 and combusted. Next, the plurality of water tubes 12 are heated by the combustion gas generated by the combustion of the mixed gas, and steam is generated from the drain supplied into the plurality of water tubes 12. The steam generated in the plurality of water pipes 12 is collected in the upper header 15 and then supplied to the steam header 71 through the first connection pipe 72.
On the other hand, the combustion gas used for generating steam inside the can 11 passes through the exhaust pipe 18 and is discharged to the outside.

  The steam supplied to the steam header 71 becomes drain after being used in the load device 50. Steam is generated in the heat pump using this drain. Specifically, the drain used in the load device 50 gives heat to the refrigerant in the evaporator 85 to vaporize the refrigerant. The refrigerant vaporized in the evaporator 85 heats makeup water in the condenser 83 to generate steam. The steam generated in the condenser 83 is supplied to the steam header 71 via the second connection pipe 81.

  As described above, the drain that has been used in the load device 50 and has given heat to the refrigerant in the evaporator 85 passes through the steam trap 61 and is stored in the drain tank 21. The drain stored in the drain tank 21 is supplied as feed water to the once-through boiler 10 through the second drain supply line L3.

As described above, in the present embodiment, the boiler system 1 includes the evaporator 85 that performs heat exchange between the drain that flows through the first drain supply line L2 and the refrigerant, the refrigerant that is heated by the evaporator 85, and makeup water. And a condenser 83 that generates steam by exchanging heat with the steam pump 61, and the steam trap 61 is disposed downstream of the evaporator 85 in the first drain supply line L2. . Thereby, heat can be recovered from the drain that flows through the first drain supply line L2, and steam can be generated and supplied to the load device 50. Therefore, the temperature of the drain that flows through the first drain supply line L2 can be lowered. Accordingly, by lowering the drain temperature, the drain temperature exceeds the saturation temperature of the reduced pressure even when the pressure is reduced downstream of the steam trap 61 in the first drain supply line L2. Therefore, it is possible to prevent flash steam from being generated in the first drain supply line L2. As a result, the thermal efficiency in the closed boiler system 1 can be further improved.
Further, since steam is generated by the heat pump 80, an auxiliary supply source of steam used in the load device 50 can be obtained.

  The boiler system 1 includes an open tank 22 and a second make-up water supply line L7 that supplies make-up water stored in the open tank 22 to the condenser 83. Thereby, steam can be generated by the heat pump 80 using makeup water.

  Further, the once-through boiler 10 is fueled from a rectangular parallelepiped can body 11, a plurality of water pipes 12 arranged in the can body 11 at predetermined intervals in the longitudinal direction and the width direction, and a side surface of the can body 11. And a burner 17 for injecting and burning gas. Thereby, compared with the boiler which has a combustion chamber in the center part of the can 11, the time after heat | fever is transmitted to the several water pipe 12 after a mixed gas burns in the burner 17 can be shortened. Therefore, since the combustion temperature (flame temperature) of the mixed gas in the burner 17 can be lowered, the combustion temperature of the mixed gas can be reduced even when the temperature of the combustion air supplied to the boiler becomes high. It can suppress that the generation amount of NOx increases by lowering the temperature.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. FIG. 4 is a diagram illustrating a configuration of a boiler system 1A according to the present embodiment.
In the second embodiment, the configuration of the heat pump 80A in the boiler system 1A is different from that of the first embodiment, but the other parts are the same. Therefore, the characteristic parts will be described, and the description of the same structure will be omitted.

  Specifically, in the second embodiment, the heat pump 80A includes a third drain supply line L8 instead of the second makeup water supply line L7 in the first embodiment.

  The third drain supply line L8 connects the drain tank 21 and the condenser 83, and supplies the drain stored in the drain tank 21 to the condenser 83. In addition, a drain pump 88 and a drain supply valve 89 are disposed in the third drain supply line L8.

  In the heat pump 80A having the above configuration, the refrigerant takes the heat from the drain flowing through the first drain supply line L2 in the evaporator 85 and is vaporized, while the refrigerant is supplied from the third drain supply line L8 in the condenser 83. The drain is heated to produce steam.

  In the second embodiment described above, the boiler system 1A is configured to include the third drain supply line L8 that supplies the drain recovered in the drain tank 21 to the condenser 83. Thereby, in heat pump 80A, since steam can be generated from high-temperature drain, the amount of steam generated by heat pump 80A can be increased.

As mentioned above, although one preferable embodiment of the boiler systems 1 and 1A of this invention was described, this invention is not restrict | limited to embodiment mentioned above and can change suitably.
For example, in the above-described embodiment, the case where the water supplied to the condenser 83 is the makeup water stored in the open tank 22 and the drain stored in the drain tank 21 has been described. .

  Moreover, in 1st Embodiment and 2nd Embodiment, although the vapor | steam produced | generated in heat pump 80,80A was supplied to the vapor | steam header 71, it is not restricted to this. That is, the second connecting pipe 81 may be connected to the first steam supply line L1, and the steam generated in the heat pump may be supplied to the first steam supply line L1.

1, 1A boiler system 10 once-through boiler 20 drain recovery device 21 drain tank 22 open tank 50 load equipment 61 steam trap 71 steam header 80, 80A heat pump 81 second connecting pipe 82 compressor 83 condenser 84 expansion valve 85 evaporator L1 first 1 steam supply line L2 1st drain supply line L3 2nd drain supply line L7 2nd makeup water supply line (makeup water supply line)
L8 3rd drain supply line

Claims (2)

A boiler having a can that generates steam and supplying the generated steam to a load device;
A first drain supply line for supplying drain generated from the load equipment by condensing the load equipment using steam;
A drain tank for collecting the drain flowing through the first drain supply line without opening it to the atmosphere;
A second drain supply line for connecting the drain tank and the boiler and supplying the boiler with the drain stored in the drain tank;
An evaporator for exchanging heat between the drain flowing through the first drain supply line and the refrigerant, and a condenser for generating steam by exchanging heat between the refrigerant and water heated by the evaporator A heat pump having
A steam supply line for supplying steam generated in the condenser to the load device;
A steam trap disposed downstream of the evaporator in the first drain supply line;
An open tank for storing makeup water to be supplied to the boiler;
A closed-type boiler system comprising: a makeup water supply line that supplies makeup water stored in the open tank to the condenser .   The closed boiler system according to claim 1, further comprising a third drain supply line that supplies the drain collected in the drain tank to the condenser.

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