JP2008096087A - Steam boiler device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact steam boiler with a high exhaust heat recovery rate. <P>SOLUTION: The steam boiler device is a device for generating steam by heat of exhaust gas. It is provided with: a duct 32 forming an exhaust gas passage 33; a heat exchanger 30 having a plurality of heat transfer pipes extending through the exhaust gas passage; a water supply pump 41 supplying water to the plurality of heat transfer pipes; and a partition plate 50 arranged substantially vertically with respect to a longitudinal direction of the plurality of heat transfer pipes and partitioning the heat exchanger into an upstream side section 30A and a downstream side section 30B. The duct has an exhaust gas inlet 29, a deflecting part 35 deflecting a flow direction of the exhaust gas, and an exhaust gas outlet 31. The exhaust gas flowing through the exhaust gas passage changes the flow direction at the deflecting part and passes through the upstream side section after passing through the downstream side section. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a steam boiler device, and more particularly to a steam boiler device that generates steam by the heat of exhaust gas discharged from a gas turbine device or a gas engine.

  High-temperature exhaust gas is discharged from the gas turbine device and the gas engine. A steam boiler device is used as an exhaust heat recovery device for recovering the heat of the exhaust gas. This steam boiler device generates water by evaporating water by exchanging heat between exhaust gas and water. Recently, a micro gas turbine power generation device combining a steam boiler device and a gas turbine device has attracted attention as a cogeneration system with excellent energy efficiency.

  The micro gas turbine power generator is operated at a high speed of, for example, about 100,000 revolutions per minute by directly connecting a micro generator to a micro turbine and supplying combustion gas to the turbine. According to such a gas turbine power generator, it is possible to supply generated power of, for example, about 50 to 100 kW, although it is an extremely small facility. In addition to the advantages of being small and lightweight, the micro gas turbine power generator does not require a tank for storing liquid fuel in order to use gas fuel such as city gas, and the operating rate during a disaster is higher than that of conventional power generators. Has the advantage of being expensive. For these reasons, recently, there is an increasing demand for micro gas turbine power generation devices as emergency power sources.

JP 2003-322030 A

From the viewpoint of using the micro gas turbine power generator as a cogeneration system, it is preferable that the energy efficiency (exhaust heat recovery rate) be as high as possible. Further, from the viewpoint of using the micro gas turbine power generation device as an emergency power source, the overall size is preferably small and light.
The present invention has been made in view of such circumstances, and an object thereof is to provide a compact steam boiler apparatus having a high exhaust heat recovery rate.

  In order to achieve the above-described object, one aspect of the present invention is a steam boiler device that generates steam by the heat of exhaust gas, and includes a duct that forms an exhaust gas passage, and the inside of the exhaust gas passage. A heat exchanger having a plurality of heat transfer tubes, a water supply pump for supplying water to the plurality of heat transfer tubes, and arranged substantially perpendicular to a longitudinal direction of the plurality of heat transfer tubes; And a partition plate partitioning into a downstream section, and the duct has an exhaust gas inlet, a turning portion for turning the flow direction of the exhaust gas, and an exhaust gas outlet, and the exhaust gas flowing through the exhaust gas passage After passing through the downstream section, the gas is changed in the flow direction at the turning portion and passes through the upstream section.

In a preferred aspect of the present invention, lengths in the longitudinal direction of the upstream section and the downstream section are substantially the same.
In a preferred aspect of the present invention, a rectifying plate is disposed in the turning portion.
In a preferred aspect of the present invention, a bypass passage that bypasses the heat exchanger and connects the exhaust gas inlet and the exhaust gas outlet, and a bypass valve that adjusts a flow rate of the exhaust gas that bypasses the heat exchanger are provided. Further, it is provided.
A preferred aspect of the present invention further includes a pressure gauge that measures the pressure of the steam generated in the heat exchanger, and a control unit that controls the opening degree of the bypass valve, and the control unit is configured to output from the pressure gauge. Based on the output signal, the opening degree of the bypass valve is controlled so that the pressure of the steam generated in the heat exchanger is maintained at a preset value.
A preferred aspect of the present invention further includes a thermometer for measuring a temperature of the exhaust gas flowing through the exhaust gas flow path, and the heat exchange is performed by closing the bypass valve until the temperature of the exhaust gas reaches a predetermined value. The device is bypassed.
A preferred embodiment of the present invention includes a steam release valve that opens steam to the atmosphere when the pressure of the steam generated in the heat exchanger reaches a predetermined first value, and the pressure of the steam generated in the heat exchanger. Is further provided with a safety valve that opens the steam to the atmosphere when a predetermined second value larger than the first value is reached.

  Another aspect of the present invention is a gas turbine power generation system including the steam boiler device and a gas turbine device having a generator.

  According to the present invention, since the exhaust gas flow path is curved, the space for accommodating the duct can be reduced, and the entire steam boiler apparatus can be made compact. Further, the exhaust gas passes through the heat exchanger twice, so that the exhaust heat recovery rate can be improved.

  Hereinafter, an embodiment of a gas turbine power generation system including a steam boiler device according to the present invention will be described in detail with reference to FIGS. 1 to 5. The gas turbine power generation system described below includes a micro gas turbine power generation apparatus that generates power using a very small turbine.

  FIG. 1 is a system diagram schematically showing an overall configuration of a gas turbine power generation system including a steam boiler device according to an embodiment of the present invention. As shown in FIG. 1, the gas turbine power generation system includes a gas turbine device 1 that generates power by burning a mixture of compressed air and fuel gas, and the gas turbine device 1 includes natural gas and liquefied petroleum gas (LPG). And the like, and a steam compressor (steam boiler device) 3 that recovers exhaust heat from the exhaust gas discharged from the gas turbine device 1.

  The gas turbine device 1 combusts an air compressor 11 that compresses air sucked from an air suction port 10, and a mixture of compressed air compressed by the air compressor 11 and fuel gas from the gas compressor 2. An annular combustor 12, a turbine 13 having a plurality of rotating blades that receive combustion gas generated in the annular combustor 12 and rotate at high speed, a generator 14 that generates power by high-speed rotation of the turbine 13, and the turbine 13 And a regenerator 15 for heating the compressed air supplied to the annular combustor 12 using the heat of the exhaust gas discharged. The regenerator 15 in the present embodiment has a plate fin heat exchanger in which a compressed air flow path (low temperature medium flow path) and an exhaust gas flow path (high temperature medium flow path) are formed by plate fins. .

  The air compressor 11, the turbine 13, and the generator 14 are arranged coaxially via a rotating shaft 16, and the rotating shaft 16 is rotatably supported by a bearing (not shown). A generator 14 is connected to one end of the rotating shaft 16, and the turbine 13, the air compressor 11, and the generator 14 rotate together via the rotating shaft 16.

  The compressed air discharged from the air compressor 11 flows through the flow path 24 and is introduced into the regenerator 15. In the regenerator 15, heat exchange is performed between the compressed air and the exhaust gas from the turbine 13 to heat the compressed air. The heated compressed air is introduced into the annular combustor 12 through the flow path 25, where it is mixed with the fuel gas supplied from the gas compressor 2. As a result, a mixture of compressed air and fuel gas is formed inside the annular combustor 12. This air-fuel mixture is combusted inside the annular combustor 12, and combustion of this air-fuel mixture generates high-temperature and high-pressure combustion gas.

  The turbine 13 rotates at high speed in response to the combustion gas generated by the combustion in the annular combustor 12, and the generator 14 and the air compressor 11 are rotationally driven at high speed as the turbine 13 rotates at high speed. The AC current generated in the generator 14 is adjusted so that it can be used as a commercial AC current by a DC converter, a booster, an inverter device, etc. (not shown), and then output to the outside.

  The exhaust gas discharged from the turbine 13 is sent to the hot medium flow path of the regenerator 15 through the flow path 26. The exhaust gas flowing through the high temperature medium flow path in the regenerator 15 heats the compressed air flowing through the low temperature medium flow path in the regenerator 15, and then is supplied to the steam boiler 3 from the exhaust gas inlet 29.

  As shown in FIG. 1, the steam boiler 3 includes a heat exchanger 30 that performs heat exchange between exhaust gas from the turbine 13 and water, and water supplied from a water supply line 42 is supplied from the turbine 13. Steam is generated by heating with exhaust gas. The exhaust gas that has exchanged heat with water in the steam boiler 3 is exhausted to the outside from the exhaust gas outlet 31.

  FIG. 2 is a schematic diagram showing the steam boiler shown in FIG. As shown in FIG. 2, the steam boiler includes a duct 32 in which an exhaust gas passage 33 is formed, a heat exchanger 30 having a plurality of heat transfer tubes 36 extending across the exhaust gas passage 33, an exhaust A preheater (economizer) 40 disposed in the gas flow path 33 and a water supply pump 41 for supplying water to the heat transfer pipe 36 via the preheater 40 are provided. The exhaust gas discharged from the regenerator 15 shown in FIG. 1 is introduced into the exhaust gas flow path 33 from the exhaust gas inlet 29, passes through the heat exchanger 30 and the preheater 40 in this order, and then discharged from the exhaust gas outlet 31. The

  The heat transfer tubes 36 are linear water tubes extending in the vertical direction, and are arranged in parallel to each other. A plurality of fins 37 are fixed to the outer peripheral surface of each heat transfer tube 36. The lower ends of these heat transfer tubes 36 are connected to the lower header 45, and the upper ends are connected to the upper header 46.

  The preheater 40 is located downstream of the heat exchanger 30 in the exhaust gas flow direction. The inlet of the preheater 40 is connected to one end of the water supply line 42, and the outlet of the preheater 40 is connected to the lower header 45. The other end of the water supply line 42 is connected to a water supply pump 41, and water is sent to the preheater 40 via the water supply line 42 by the water supply pump 41. The water supply line 42 is provided with a check valve 43 and a water supply valve (solenoid valve) 44. A circulation line 71 is connected to the water supply line 42, and a pump circulation valve 72 is provided in the circulation line 71. In this configuration, when the pump circulation valve 72 is opened while the water supply valve 44 is closed, water circulates between the water supply pump 41 and the circulation line 71 and water supply to the heat exchanger 30 is stopped.

  In the preheater 40, water is heated by the exhaust gas to become hot water, and is supplied to the heat exchanger 30. In the heat exchanger 30, the hot water is heated by the exhaust gas flowing through the exhaust gas passage 33 while flowing through the heat transfer pipe 36 from the bottom to the top. A partition plate 50 perpendicular to the longitudinal direction of the heat transfer tube 36 is provided at a substantially central portion of the heat transfer tube 36, and the heat exchanger 30 is divided into an upstream section 30A and a downstream section 30B by the partition plate 50. Has been. In addition, the ratio of the length of the upstream section 30A and the downstream section 30B is not limited to 1: 1, and can be changed as necessary. The duct 32 has a turning portion 35 that turns the flow direction of the exhaust gas by about 180 degrees, and a rectifying plate 38 is disposed in the turning portion 35.

  According to the duct 32 having such a shape, after the exhaust gas passes through the downstream section 30B of the heat exchanger 30, the flow direction thereof is changed in the turning section 35, and the upstream section 30A of the heat exchanger 30 is changed. pass. As described above, the exhaust gas flowing through the exhaust gas passage 33 passes through the heat exchanger 30 twice, thereby improving the efficiency of exhaust heat recovery. Moreover, the duct 32 and the heat exchanger 30 can be made compact. Furthermore, since the number of the heat transfer tubes 36 can be reduced, the number of welding points is reduced, and as a result, the manufacturing cost can be reduced.

  The hot water flowing through the heat transfer tube 36 is heated by the exhaust gas flowing through the exhaust gas passage 33 to become steam. Steam is collected at the upper header 46 and introduced into the steam separator 60 via the first steam line 55. In the steam / water separator 60, the steam and water are separated from each other, and only the steam is supplied to the customer through the second steam line 56. The second steam line 56 is provided with a check valve 69 for preventing the backflow of steam.

  Here, the effect of providing the rectifying plate 38 in the turning portion 35 will be described with reference to FIGS. 3 (a) and 3 (b). As shown in FIG. 3A, by providing a rectifying plate 38 in the turning portion 35, the exhaust gas that has passed through the heat exchanging portion 30 is largely divided into a flow A and a flow B. As shown in FIG. 3 (b), there is a temperature distribution inside the heat exchanging unit 30, and it is divided into a low temperature hot water region, a middle temperature hot water region, a high temperature hot water region, and a high temperature steam region from the lower side to the upper side. .

  The exhaust gas that forms the flow A passes through the high temperature steam region of the heat exchange unit 30, and the exhaust gas that forms the flow B passes through the high temperature water region of the heat exchange unit 30, and thus passes through the heat exchange unit 30. The exhaust gas temperature of stream A is maintained higher than the exhaust gas temperature of stream B. The exhaust gas flow A having a high temperature passes through the low temperature hot water region of the heat exchange unit 30, and the exhaust gas flow B having a relatively low temperature passes through the medium temperature hot water region of the heat exchange unit 30. As described above, by providing the rectifying plate 38 in the flow path 32, it is possible to efficiently perform heat exchange between the exhaust gas heat and the hot water.

  As shown in FIG. 2, the water collected in the steam separator 60 is supplied to a liquid level gauge 61. Further, the water supplied to the liquid level gauge 61 is returned to the lower header 45 through a water recovery line 63 connected to the bottom of the liquid level gauge 61. The vertical position of the upper end of the liquid level gauge 61 is substantially the same as the vertical position of the upper end of the heat transfer pipe 36, and the water level position of the liquid level gauge 61 is approximately equal to the water level position of the water (hot water) in the heat transfer pipe 36. It has become.

  In the liquid level gauge 61, four electrode rods 62 having different lengths are arranged, and four water levels (H / H, H, L, L / L) can be detected. An output signal (water level) from the level gauge 61 is sent to the control unit 53, and the water supply valve 44 and the pump circulation valve 72 are opened and closed according to the water level. More specifically, when the water level is equal to or higher than the second lowest position L, the water supply valve 44 is opened and the pump circulation valve 72 is closed. Thereby, water is supplied to the heat exchanger 30. On the other hand, when the water level reaches the third lowest position H, the water supply valve 44 is closed and the pump circulation valve 72 is opened. Thereby, water is switched to the flow which circulates through the water supply pump 41 and the circulation line 71, and the water supply to the heat exchanger 30 is stopped. The electrode rod 62 for detecting the lowest water level L / L and the electrode rod 62 for detecting the highest water level H / H are provided for low water level alarm and high water level alarm, respectively.

  Thus, during steady operation, the opening / closing control of the water supply valve 44 and the pump circulation valve 72 is performed using the two electrode rods 62 out of the four, so that the water surface position in the heat transfer pipe 36 becomes substantially constant. Adjusted. The water surface position in the heat transfer pipe 36 may be adjusted by ON / OFF control of the water supply pump 41. According to this embodiment, since the dimension of the heat transfer tube 36 in the vertical direction can be increased, adjustment of the water surface position in the heat transfer tube 36 is easy.

  The water circulating through the feed water pump 41 and the circulation line 71 is heated by heat radiation from the feed water pump 41 and increases in temperature, which may damage the feed water pump 41 and the pump circulation valve 72. Therefore, in this apparatus, the temperature of the circulating water is measured by a thermocouple (thermometer) 73, and when the temperature exceeds a predetermined temperature, the pump circulation valve 72 is closed and the blow valve 75 is opened at the same time. The discharged water is discharged from the blow line 74. Thus, the gas turbine apparatus includes a safety mechanism that suppresses the temperature rise of the water circulating in the pump 41.

  The exhaust gas inlet 29 and the exhaust gas outlet 31 are disposed adjacent to each other. A bypass hole (bypass passage) 34 for bypassing the heat exchanger 30 is provided between the exhaust gas inlet 29 and the exhaust gas outlet 31. Further, a bypass valve 51 for adjusting the flow rate of exhaust gas for bypassing the heat exchanger 30 is provided on the upstream side of the exhaust gas outlet 31. FIG. 4 is a view showing a state in which the bypass valve 51 is opened 100%. In this state, the exhaust gas passes through the heat exchanger 30 and the preheater 40 without passing through the bypass hole 34 and heats the water. On the other hand, FIG. 5 is a view showing a state in which the bypass valve 51 is completely closed. In this state, the exhaust gas does not flow to the heat exchanger 30 and the preheater 40 but is discharged from the exhaust gas outlet 31 through the bypass hole 34. Thus, the opening degree of the bypass valve 51 is configured to be adjustable from 0% (state shown in FIG. 5) to 100% (state shown in FIG. 4). Therefore, the amount of steam generated in the heat exchanger 30 (that is, the steam pressure) can be adjusted by the opening degree of the bypass valve 51.

  A thermometer 65 is provided in the vicinity of the exhaust gas inlet 29, and the temperature of the exhaust gas before being introduced into the heat exchanger 30 is measured by the thermometer 65. The output signal of the thermometer 65 (exhaust gas temperature) is sent to the control unit 53, and the temperature of the exhaust gas is constantly monitored by the control unit 53.

  In the present embodiment, the start-up operation of the gas turbine device is performed based on the temperature of the exhaust gas. The specific operation is as follows. First, the bypass valve 51 is closed when the gas turbine device is started, so that the exhaust gas does not pass through the heat exchanger 30 and the preheater 40. At this time, the water supply pump 41 is stopped. When the temperature of the exhaust gas rises and reaches a predetermined value after the gas turbine device is started, the bypass valve 51 is opened and the exhaust gas starts to flow through the exhaust gas flow path 33, and at the same time, the operation of the water supply pump 41 is started. Then, water is supplied to the preheater 40 and the heat exchanger 30, thereby generating steam. According to such start-up operation, the exhaust pressure loss at the start of the gas turbine is minimized, and it is possible to maintain a state in which there is no fluctuation in the exhaust pressure, thereby reducing the load on the gas turbine device at the start-up. Can do.

  As shown in FIG. 2, a pressure gauge 66 is provided in the second steam line 56, and the pressure of steam generated in the heat exchanger 30 is measured by the pressure gauge 66. During steady operation, the opening of the bypass valve 51 is adjusted so that the pressure of the steam generated in the heat exchanger 30 maintains a preset value. The output signal (vapor pressure) of the pressure gauge 66 is transmitted to the control unit 53, and the bypass valve 51 is operated by the control unit 53 based on the output signal of the pressure gauge 66. More specifically, the control unit 53 operates the bypass valve 51 based on the output signal of the pressure gauge 66 so that the pressure of the steam passing through the second steam line 56 maintains the set value. This set value (target value) can be changed as necessary.

  In addition to the second steam line 56 described above, a steam release line 57 is connected to the steam separator 60. The second steam line 56 and the steam release line 57 communicate with each other via a bypass line 67. The bypass line 67 is provided with a steam release valve (solenoid valve) 68, and the steam release valve 68 is closed during normal operation. The pressure of the steam flowing through the second steam line 56 is constantly monitored by the control unit 53 via the pressure gauge 66. When the pressure of the steam flowing through the second steam line 56 increases and reaches a predetermined first value, the control unit 53 sends a command to the steam release valve 68 and opens the steam release valve 68. Yes. Thus, the steam flows from the second steam line 56 to the steam release line 57 via the bypass line 67 and is released to the atmosphere.

  The steam release line 57 is provided with a safety valve 70. When the pressure of the steam generated in the heat exchanger 30 rises excessively and reaches a predetermined second value, the safety valve 70 is automatically opened to supply steam. It comes to be released into the atmosphere. The position where the safety valve 70 is disposed is upstream of the location where the steam release line 57 is connected to the bypass line 67. The first value when the steam release valve 68 opens is set lower than the second value when the safety valve 70 opens. As described above, the bypass valve 51, the steam release valve 68, and the safety valve 70 operate based on the pressure value of the steam generated in the heat exchanger 30.

  Generally, it is necessary to take safety measures for the steam boiler so that the pressure of the steam generated in the steam boiler does not become excessively high. In this regard, the steam boiler according to the present embodiment has three steps of safety measures. That is, during steady operation, the pressure is adjusted by the bypass valve 51 (first stage), and when the steam pressure rises to reach the first value, the steam release valve 68 is opened (second stage), and When the vapor pressure further increases and reaches the second value, the safety valve 70 is opened (third stage). As described above, the steam boiler of the present embodiment has three steps of safety measures, so that safe operation can be ensured.

  Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.

It is a distribution diagram showing typically the whole composition of the gas turbine power generation system provided with the steam boiler device in one embodiment of the present invention. It is a schematic diagram which shows the steam boiler shown in FIG. FIG. 3A is a view for explaining the flow of exhaust gas formed by the rectifying plate, and FIG. 3B is a view showing the temperature gradient of the heat exchanger. It is a figure which shows a state when the bypass valve shown in FIG. 2 is opened. It is a figure which shows a state when the bypass valve shown in FIG. 2 is closed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas turbine apparatus 2 Gas compression apparatus 3 Steam boiler (exhaust heat recovery apparatus)
DESCRIPTION OF SYMBOLS 10 Air intake port 11 Air compressor 12 Annular combustor 13 Turbine 14 Generator 15 Regenerator 16 Rotating shaft 17 Casing 24 Channel 25 Channel 26 Channel 29 Exhaust gas inlet 30 Heat exchanger 30A Upstream section 30B Downstream section 31 Exhaust gas outlet 32 Duct 33 Exhaust gas flow path 34 Bypass hole (bypass flow path)
35 Turning section 36 Heat transfer tube 37 Fin 38 Rectifier plate 40 Preheater 41 Water supply pump 42 Water supply line 43 Check valve 44 Water supply valve 45 Lower header 46 Upper header 50 Partition plate 51 Bypass valve 53 Control unit 55 First steam line 56 Second Steam line 57 Steam release line 60 Steam / water separator 61 Liquid level gauge 62 Electrode rod 63 Water recovery line 65 Thermometer 66 Pressure gauge 67 Bypass line 68 Steam release valve 69 Check valve 70 Safety valve 71 Circulation line 72 Pump circulation valve 73 Thermoelectric Pair 74 Blow line 75 Blow valve

Claims (8)

A steam boiler device that generates steam by the heat of exhaust gas,
A duct forming an exhaust gas flow path;
A heat exchanger having a plurality of heat transfer tubes extending in the exhaust gas flow path;
A water supply pump for supplying water to the plurality of heat transfer tubes;
A partition plate arranged substantially perpendicular to the longitudinal direction of the plurality of heat transfer tubes, and partitioning the heat exchanger into an upstream section and a downstream section;
The duct has an exhaust gas inlet, a turning portion for turning the flow direction of the exhaust gas, and an exhaust gas outlet,
The steam boiler apparatus, wherein the exhaust gas flowing through the exhaust gas flow path passes through the upstream section while changing the flow direction at the turning section after passing through the downstream section.   The steam boiler device according to claim 1, wherein the upstream section and the downstream section have substantially the same length in the longitudinal direction.   The steam boiler device according to claim 1, wherein a current plate is disposed in the turning portion. A bypass passage that bypasses the heat exchanger and communicates the exhaust gas inlet and the exhaust gas outlet;
The steam boiler device according to any one of claims 1 to 3, further comprising a bypass valve that adjusts a flow rate of exhaust gas that bypasses the heat exchanger. A pressure gauge for measuring the pressure of the steam generated in the heat exchanger;
A controller for controlling the opening of the bypass valve;
The control unit controls the opening of the bypass valve based on an output signal from the pressure gauge so that the pressure of steam generated in the heat exchanger is maintained at a preset value. The steam boiler device according to claim 4. A thermometer for measuring the temperature of the exhaust gas flowing through the exhaust gas flow path;
The steam boiler device according to claim 5, wherein the heat exchanger is bypassed by closing the bypass valve until the temperature of the exhaust gas reaches a predetermined value. A steam release valve that opens the steam to the atmosphere when the pressure of the steam generated in the heat exchanger reaches a predetermined first value;
A safety valve that further opens the steam to the atmosphere when the pressure of the steam generated in the heat exchanger reaches a predetermined second value that is greater than the first value. The steam boiler apparatus as described in any one of 1 thru | or 6. A steam boiler device according to any one of claims 1 to 7,
A gas turbine power generation system comprising a gas turbine device having a generator.

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