JP2016153716A - Boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust recirculation type boiler capable of suppressing increase in size of an air blower, and capable of reducing driving cost.SOLUTION: A boiler 1 includes: a boiler body 10 that combusts fuel and heats supply water; an exhaust passage 20 that discharges exhaust gas generated by combusting fuel in the boiler body; an air supply passage 30 of which a tip side is connected to the boiler body 10, and that supplies combustion air to the boiler 10; an air blower 40 that is connected to the base end side of the air supply passage 30, and feeds combustion air to the air supply passage 30; an exhaust circulation passage 50 that circulates part of exhaust gas circulating through the exhaust passage 20 to the air blower 40; and a heat exchanger 60 that performs heat exchange between exhaust gas circulating through the exhaust circulation passage 50 and combustion air circulating through the air supply passage 30.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a boiler device. More specifically, the present invention relates to an exhaust gas recirculation boiler device that circulates a part of exhaust gas to the supply air side and uses it as combustion air.

Conventionally, a part of the exhaust gas generated by combustion of fuel gas in the boiler body is circulated to the supply air side and mixed at a predetermined rate with the outside air (air), and the mixed gas is used as combustion air as fuel gas There has been proposed an exhaust gas recirculation boiler device that combusts (see, for example, Patent Document 1). According to such a boiler apparatus, the combustion temperature of the fuel gas can be lowered by recirculating the exhaust gas having a reduced oxygen concentration to the supply side, and as a result, the concentration of NO _x contained in the exhaust gas is reduced. Be made.

JP 2004-69140 A

  By the way, in a boiler apparatus, combustion air is sent into a boiler main body by a blower. Here, in the exhaust gas recirculation boiler device, the blower sucks the exhaust gas having a temperature higher than that of the outside air together with the outside air. Therefore, when supplying a predetermined amount (mass) of combustion air corresponding to the combustion amount of the fuel gas, the exhaust gas recirculation type boiler apparatus has a blower that is different from a boiler apparatus that uses only outside air as the combustion air. It is necessary to increase the output, which increases the size of the blower and increases the driving cost of the blower.

  Accordingly, an object of the present invention is to provide an exhaust gas recirculation type boiler apparatus that can suppress an increase in the size of a blower and reduce driving costs.

  The present invention includes a boiler body that burns fuel to heat feed water, an exhaust passage that discharges exhaust gas generated by the combustion of fuel in the boiler body, and a tip end side connected to the boiler body, and burns to the boiler body An air supply path for supplying air, a blower connected to the base end side of the air supply path and for sending combustion air to the air supply path, and a part of the exhaust gas flowing through the exhaust path is circulated to the blower The present invention relates to a boiler device including an exhaust circuit, and a heat exchanger that performs heat exchange between exhaust gas flowing through the exhaust circuit and combustion air flowing through the air supply path.

  Moreover, it is preferable that a boiler apparatus is further provided with the hydrogen gas supply line which supplies the fuel gas containing hydrogen gas to the said boiler main body.

  Further, the heat exchanger includes a plurality of heats arranged so as to be inclined such that the side on which the inlet and outlet for combustion air are arranged is located above and the side on which the exhaust gas inlet and outlet are located is located below. It is preferable to include a pipe.

  Moreover, it is preferable that the said heat exchanger is comprised with a plate-type heat exchanger.

  According to the boiler device of the present invention, the increase in size of the blower can be suppressed, and the driving cost can be reduced.

It is a figure showing a boiler device concerning one embodiment of the present invention. It is a perspective view showing one embodiment of a heat pipe type heat exchanger. It is a perspective view which shows one Embodiment of a plate-type heat exchanger.

  Hereinafter, a preferred embodiment of the boiler device 1 of the present invention will be described with reference to the drawings. The boiler device 1 of this embodiment is a steam boiler that generates steam by heating water, and supplies steam to load equipment (not shown). The boiler device 1 of the present embodiment is an exhaust gas recirculation boiler device 1 that circulates a part of exhaust gas to the supply air side and uses it as combustion air. The “line” in the present specification is a general term for lines capable of flowing a fluid such as a flow path, a path, and a pipeline.

  As shown in FIG. 1, the boiler device 1 of this embodiment includes a boiler body 10, an exhaust path 20, an air supply path 30, a blower 40, an exhaust circulation path 50, and an air heater as a heat exchanger. 60, a feed water line 70, a feed water heater 80, and a fuel supply line 90.

  The boiler body 10 generates steam by burning fuel and heating feed water. The boiler body 10 includes a cylindrical can body 11 constituting an outer shape, and a burner 12 disposed on the upper portion of the can body 11. The can 11 includes a plurality of water pipes, a lower header, an upper header, and a combustion chamber (all not shown).

  The exhaust path 20 discharges the exhaust gas generated by the combustion of fuel in the boiler body 10 to the outside. The proximal end side of the exhaust path 20 is connected to the peripheral surface of the can body 11. The front end side of the exhaust path 20 extends upward.

  The air supply path 30 supplies combustion air to the boiler body 10. The front end side of the air supply path 30 is connected to the upper part of the boiler body 10. The base end side of the air supply path 30 extends downward.

  The blower 40 is disposed at the lower part of the side portion of the boiler body 10. The blower 40 is connected to the proximal end side of the air supply path 30 and feeds combustion air into the air supply path 30. The blower 40 includes a fan, a motor that rotates the fan, and an inverter. The blower 40 can adjust the rotation speed of the motor according to the frequency input to the inverter.

The exhaust circulation path 50 connects the exhaust path 20 and the blower 40. The exhaust circulation path 50 circulates a part of the exhaust gas flowing through the exhaust path 20 to the blower 40 side. That is, in the present embodiment, the blower 40 sucks the outside air and the exhaust gas supplied from the exhaust circulation path 50, and sends the mixture of the outside air and the exhaust gas as combustion air to the air supply path 30.
A damper 51 is disposed in the exhaust circulation path 50. The damper 51 adjusts the flow rate of the exhaust gas circulated through the exhaust circulation path 50 and circulated to the blower 40 by changing the opening degree.

  The air heater 60 performs heat exchange between the exhaust gas flowing through the exhaust circulation path 50 and the combustion air flowing through the air supply path 30. In the present embodiment, as shown in FIG. 2, the air heater 60 includes a housing 61, a plurality of heat pipes 62 disposed inside the housing 61, and a partition wall 63 that partitions the inside of the housing 61. And comprising.

  The casing 61 forms the outer shape of the air heater 60 and is formed in a rectangular parallelepiped shape in plan view. An inlet 64 and an outlet 65 for combustion air are formed on one end side in the longitudinal direction of the casing 61. Further, an exhaust gas inlet 66 and an outlet 67 are formed on the other end side of the casing 61 in the longitudinal direction. The combustion air inlet 64 is formed on the lower surface of the housing 61, and the outlet 65 is formed on the upper surface of the housing 61. The exhaust gas inlet 66 is formed on the upper surface of the housing 61, and the outlet 67 is formed on the lower surface of the housing 61.

The plurality of heat pipes 62 include a cylindrical main body 621 whose both ends are closed, and a plurality of fins 622 that are attached to the outer periphery of the main body 621 at predetermined intervals in the longitudinal direction of the main body 621. A working fluid (volatile liquid) is sealed inside the main body 621.
The plurality of heat pipes 62 are disposed along the longitudinal direction of the casing 61 and inclined so that the side on which the combustion air inlet 64 and the outlet 65 are disposed is positioned upward.

  The partition wall 63 is disposed at the center in the longitudinal direction of the housing 61 and divides the internal space of the housing 61 into two in the longitudinal direction. A plurality of through holes into which the plurality of heat pipes 62 can be inserted are formed in the partition wall 63. That is, the inside of the housing 61 is partitioned by the partition wall 63 into a space where the combustion air circulates from the bottom to the top and a space where the exhaust gas circulates from the top to the bottom.

  According to the air heater 60 described above, the working fluid in a liquid state accommodated in the plurality of heat pipes 62 is heated and vaporized by the exhaust gas, and moves (rises) to the side through which the combustion air flows. . The vaporized working fluid is cooled and liquefied by the combustion air, and moves (lowers) to the side where the exhaust gas flows. Thereby, heat exchange between the combustion air and the exhaust gas is performed.

  The water supply line 70 has a proximal end connected to a water supply source (not shown) and a distal end connected to the boiler body 10 (lower header). The water supply line 70 supplies water for generating steam to the boiler body 10.

  The feed water heater 80 is disposed on the upstream side (downward) of the connection portion of the exhaust passage 20 with the exhaust circulation passage 50. The feed water heater 80 heats the feed water by exchanging heat between the exhaust gas discharged from the boiler body 10 and flowing through the exhaust passage 20 and the feed water flowing through the feed water line 70.

  The fuel supply line 90 supplies fuel gas to the boiler body 10. As the fuel gas supplied to the boiler body 10, hydrocarbon gas such as propane gas or city gas, hydrogen gas generated as a by-product during operation of a plant or the like, or a mixed gas thereof can be used. In the present embodiment, the fuel supply line 90 is configured by a hydrogen gas supply line through which a fuel gas containing hydrogen gas flows.

Next, operation | movement of the boiler apparatus 1 of this embodiment is demonstrated.
In the boiler device 1, combustion air is supplied into the boiler body 10 from the air supply passage 30, and fuel gas is supplied from the fuel supply line 90 to burn the fuel gas. In addition, water is supplied from a water supply line 70 to the plurality of water pipes arranged inside the can body 11, and the water is heated by the heat generated by burning the fuel gas to generate steam.

  Combustion gas generated by the combustion of the fuel gas flows through the exhaust path 20 as exhaust gas. The exhaust gas flowing through the exhaust path 20 from below to above performs heat exchange with water flowing through the water supply line 70 in the water supply heater 80 to heat the water supply. A part of the exhaust gas whose temperature has decreased due to heat exchange in the feed water heater 80 circulates in the exhaust circuit 50 and the rest is discharged to the outside.

The exhaust gas flowing through the exhaust circulation path 50 exchanges heat with the combustion air flowing through the air supply path 30 in the air heater 60 to heat the combustion air. The exhaust gas whose temperature has been further lowered by performing heat exchange in the air heater 60 is supplied to the blower 40 and sent to the air supply path 30 together with the outside air.
Thereby, the exhaust gas circulated to the air supply side and the outside air are mixed at a predetermined ratio, and the fuel gas is combusted using the mixed air-fuel mixture as combustion air.

  According to the boiler apparatus 1 of this embodiment demonstrated above, there exist the following effects.

  (1) An exhaust gas circulation path 50 that circulates a part of the exhaust gas flowing through the exhaust path 20 to the blower 40 in the boiler device 1, and an exhaust gas flowing through the exhaust gas circulation path 50 and combustion air that flows through the air supply path 30 And an air heater 60 for exchanging heat with each other. Thereby, the exhaust gas which distribute | circulates the exhaust circuit 50 is made to circulate to the air blower 40 in the state which carried out heat exchange with the combustion air, and reduced the temperature. Therefore, since the exhaust gas can be sucked into the blower 40 in a state in which the temperature is reduced and the volume of the exhaust gas is reduced, the increase in the size of the blower 40 can be suppressed in the exhaust gas recirculation boiler device 1. An increase in driving cost can be suppressed. Further, since the heat of the exhaust gas can be given to the combustion air, the boiler efficiency can be suitably maintained.

In particular, in the case of using hydrogen gas as the fuel gas, the combustion temperature becomes higher than the case of using a hydrocarbon gas such as city gas as a fuel gas, the concentration of NO _X in the exhaust gas tends to increase. Therefore, it is required to increase the amount of exhaust gas to be circulated to lower the NO _X concentration. However, when the circulation amount of the high-temperature exhaust gas is increased, it is necessary to increase the output of the blower 40, and the blower 40 is further increased in size. Thus, in the environment where the circulation amount of the exhaust gas increases, the boiler device 1 of the present invention that supplies the blower 40 with the temperature of the exhaust gas lowered by the air heater 60 increases the size of the blower 40. It can suppress more effectively.

  (2) The air heater 60 includes a plurality of heat pipes 62, and the plurality of heat pipes 62 are located on the upper side where the combustion air inlet and outlet are disposed, and the exhaust gas inlet and outlet It was inclined and placed so that the side on which it was placed was positioned below. As a result, the heat exchanger can be configured more compactly by using the heat pipe type air heater 60, and the combustion air and exhaust gas flow paths are complicated by arranging the heat pipe 62 at an inclination. This makes it possible to exchange heat efficiently.

The preferred embodiments of the boiler device 1 of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and can be modified as appropriate.
For example, in the present embodiment, the air heater 60 is configured by a heat pipe type heat exchanger, but is not limited thereto. That is, the air heater may be constituted by a plate heat exchanger 60A as shown in FIG.

  A plate heat exchanger 60A shown in FIG. 3 is a plate type air heater having an upper and lower flow pattern, and an inlet 64A and an outlet 65A for combustion air in the plate heat exchanger 60A are plate type heat exchangers. The exhaust gas inlet 66A and the outlet 67A are provided on one end side in the longitudinal direction of 60A, and are provided on the other end side in the longitudinal direction. In FIG. 3, the plate heat exchanger 60 </ b> A is schematically illustrated with the internal detailed structure omitted in order to explain the combustion air and exhaust gas flow paths.

  Thereby, even if an air heater is comprised by plate type heat exchanger 60A, the part which sandwiches plate type heat exchanger 60A in each of supply air path 30 and exhaust circulation path 50 can be arranged on a straight line. Therefore, the boiler apparatus 1 can be configured without complicating the piping of the air supply passage 30 and the exhaust circulation passage 50.

DESCRIPTION OF SYMBOLS 1 Boiler apparatus 10 Boiler main body 20 Exhaust path 30 Supply air path 40 Blower 50 Exhaust air circulation path 60 Air heater (heat exchanger)
60A Plate heat exchanger 62 Heat pipe 64 Combustion air inlet 65 Combustion air outlet 66 Exhaust gas inlet 67 Exhaust gas outlet

Claims (4)

A boiler body that burns fuel and heats the feed water;
An exhaust path for discharging exhaust gas generated by burning fuel in the boiler body;
A front end side is connected to the boiler body, and an air supply path for supplying combustion air to the boiler body,
A blower connected to the base end side of the air supply path and for sending combustion air into the air supply path;
An exhaust circulation path for circulating a part of the exhaust gas flowing through the exhaust path to the blower;
A boiler device comprising: a heat exchanger that exchanges heat between exhaust gas flowing through the exhaust circulation path and combustion air flowing through the air supply path.   The boiler device according to claim 1, further comprising a hydrogen gas supply line that supplies a fuel gas containing hydrogen gas to the boiler body.   The heat exchanger includes a plurality of heat pipes that are inclined so that the side on which the inlet and outlet for combustion air are arranged is located above and the side on which the inlet and outlet for exhaust gas are located is located below. The boiler apparatus of Claim 2 comprised including. The boiler device according to claim 2, wherein the heat exchanger is configured by a plate heat exchanger.

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