Waste heat recovery device for boiler equipment

Abstract

To provide an exhaust heat reutilization device for a boiler facility which effectively uses discharge water generated from a heat exchanger of the boiler facility including the heat exchanger for cooling a water-cooled jacket structure of a hot blast generation furnace.SOLUTION: An exhaust heat reutilization device 10 for a boiler facility includes: a hot blast generation furnace 110 having a water-cooled jacket structure 114 provided on a wall surface thereof; a waste heat boiler 120 that generates primary steam by exchanging heat with combustion gas generated in the hot blast generation furnace 110; a dust collector 140 for collecting exhaust gas after the heat exchange; and a heat pump 20 that generates secondary steam by using discharge water of a heat exchanger 130 of the boiler facility 100 having the heat exchanger 130 exchanging heat with cooling water of the water-cooled jacket structure 114. The secondary steam is supplied to the dust collector 140.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a waste heat recovery device for a boiler facility equipped with a heat exchanger for cooling a water-cooled jacket structure of a hot air generator.

Background Art

[0002] Waste solid fuels such as RDF (Refuse Derived Fuel) made from waste such as food waste and plastic waste, or RPF (Refuse Paper & Plastic Fuel) whose chlorine content and calorific value are adjusted from paper, wood, and waste plastics are used as fuels for steam power generation, steam boilers, etc. (for example, disclosed in Patent Document 1).

[0003] FIG. 2 is an explanatory diagram of a conventional steam boiler facility. As shown in the figure, the boiler facility 100 includes a hot air generator 110 (hereinafter also referred to as a combustion furnace), a waste heat boiler 120, a heat exchanger 130, and a dust collector 140. The hot air generator 110 is heated by a burner for temperature rise. Combustion air is introduced into the hot air generator 110 from below the furnace by a primary air fan 112. Solid fuel is supplied into the furnace by a conveyor and burned while being stirred and conveyed by a grate (stoker), generating combustion gas. The combustion gas is sent to a waste heat boiler 120 installed at the upper outlet in the furnace after its combustion is promoted by a secondary air fan. The combustion gas exchanges heat with feed water in a flue arranged horizontally in the waste heat boiler 120 to generate hot steam. A water-cooled jacket structure 114 is formed on the wall surface of the combustion furnace, and cooling water for cooling to a predetermined temperature flows in. The cooling water of the water-cooled jacket structure 114 is circulated and exchanges heat with groundwater in the heat exchanger 130. Thereby, it is possible to reduce the low-temperature corrosion of the furnace body due to the influence of chlorine. In addition, the exhaust gas after heat recovery in the waste heat boiler 120 is introduced into the dust collector 140, and dust and reaction products in the gas are removed by a bag filter 142. Then, it is attracted by an induced draft fan and discharged into the atmosphere from a chimney 144. At this time, a part of it is sent to the primary air fan 112 of the hot air generator 110 via an exhaust gas duct 146 and reused.

[0004] As described above, in the water-cooled jacket structure 114 of the hot air generator 110, a heat exchanger 130 is installed in the cooling water circulation pipe to keep the cooling water at a predetermined temperature. This heat exchanger 130 exchanges heat between the cooling water and the external groundwater. After the heat exchange, the groundwater is heated to around 55°C and then discarded as it is. On the other hand, the steam generated by the waste heat boiler 120 is used not only for drying products and the like to improve productivity but also for maintaining the dust collection function of the dust collector 140. This is to prevent corrosion of the outer surface of the main body of the dust collector 140 by sulfur dioxide and hydrogen chloride in the exhaust gas by heating it to a predetermined temperature. Originally, the steam generated by the waste heat boiler 120 should be fully utilized for drying products and the like to improve productivity. However, in order to maintain the dust collection function and prevent the release of harmful substances into the atmosphere, a part of the steam had to be used for another purpose.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The problem to be solved by the present invention is, in view of the problems of the above prior art, to provide a waste heat reuse device for a boiler facility that effectively utilizes the drainage generated from the heat exchanger of a boiler facility equipped with a heat exchanger for cooling the water-cooled jacket structure of a hot air generator. Another problem is to provide a waste heat reuse device for a boiler facility that effectively utilizes the steam generated by a steam boiler.

Means for Solving the Problems

[0007] As a first means for solving the above problems, the present invention provides a hot air generator having a water-cooled jacket structure on a wall surface, a waste heat boiler that generates primary steam by exchanging heat with combustion gas generated in the hot air generator, a dust collector that collects exhaust gas after heat exchange, and a heat pump that generates secondary steam using the drained water of the heat exchanger of the boiler equipment having a heat exchanger that exchanges heat with the cooling water of the water-cooled jacket structure, and supplies the secondary steam to the dust collector. There is provided a waste heat recovery device for boiler equipment. According to the first means, hot water at a predetermined temperature generated in the heat exchanger, that is, drained water, can be used to generate secondary steam and reused to maintain the dust collection function of the dust collector. Therefore, the primary steam can be effectively utilized for its original purpose to improve productivity.

[0008] As a second means for solving the above problems, the present invention provides a waste heat recovery device for boiler equipment, characterized in that, in the first means, the secondary steam is supplied to the outer surface of the chimney of the dust collector. According to the second means, condensation of corrosive components in the chimney can be suppressed. Thereby, corrosion prevention of the chimney can be realized.

[0009] As a third means for solving the above problems, the present invention provides a waste heat recovery device for boiler equipment, characterized in that, in the first or second means, the secondary steam is used to warm the groundwater supply pipe of the heat exchanger. According to the third means, it is possible to prevent the groundwater supplied to the heat exchanger from freezing in winter. Thereby, groundwater can be stably supplied to the heat exchanger throughout the year.

[0010] As a fourth means for solving the above problems, the present invention provides a waste heat recovery device for boiler equipment, characterized in that, in any one of the first to third means, the secondary steam is used for heating the exhaust gas duct of the dust collector. According to the fourth means, it is possible to prevent a temperature drop when the hot air is supplied from the chimney to the primary air fan of the hot air generator, and to maintain high combustion efficiency. Also, condensation can be suppressed to achieve corrosion prevention.

[0011] As a fifth means for solving the above problems, the present invention provides a waste heat recovery device for a boiler facility, characterized in that, in any one of the first to fourth means, the secondary steam is supplied through a double pipe or a pipe wound with a heat-insulating tube. According to the fifth means, the temperature of the secondary steam can be kept high.

Effects of the Invention

[0012] According to the present invention, secondary steam can be generated from hot water at a predetermined temperature generated in a heat exchanger, that is, wastewater, and reused to maintain the dust collection function of a dust collector. Therefore, the primary steam can be effectively utilized for its original purpose to improve productivity.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0014] An embodiment of the waste heat recovery device for a boiler facility of the present invention will be described in detail below with reference to the drawings.

[0015] [Waste Heat Recovery Device 10 for Boiler Facility] FIG. 1 is a schematic configuration diagram of a waste heat recovery device for a boiler facility of the present invention. As shown in the figure, the waste heat recovery device 10 for a boiler facility of the present invention includes a hot air generator 110 provided with a water-cooled jacket structure 114 on a wall surface, a waste heat boiler 120 that generates primary steam by exchanging heat with combustion gas generated in the hot air generator 110, a dust collector 140 that collects exhaust gas after heat exchange, and a heat pump 20 that generates secondary steam using the drained water (hot water) of the heat exchanger 130 of a boiler facility 100 having a heat exchanger 130 that exchanges heat with the cooling water of the water-cooled jacket structure 114, and supplies the steam to the dust collector 140.

[0016] The waste heat recovery device 10 for a boiler facility of the present invention is a device provided in a boiler facility 100 including a hot air generator 110, a waste heat boiler 120, a heat exchanger 130, and a dust collector 140. The heat pump 20 includes a heat radiation side heat exchanger 22, a heat receiving side heat exchanger 24, a throttle valve 26, and a compressor 28, and generates secondary steam using the drained water of the heat exchanger 130. Inside the heat pump 20, a pipe L1 through which a heat pump medium circulates is formed, and it is connected in order from the outlet of the heat receiving side heat exchanger 24 to the compressor 28, the heat radiation side heat exchanger 22, the throttle valve 26, and the inlet of the heat receiving side heat exchanger 24.

[0017] The waste heat recovery device 10 for a boiler facility of the present invention includes a feed water preheating unit 30 that reuses the hot water heat-exchanged between the heat exchanger 130 and the heat pump 20. The feed water preheating unit 30 is a heat exchanger that preheats groundwater in advance before turning it into secondary steam. A pipe L2 through which a preheating medium circulates is formed between the feed water preheating unit 30, the heat exchanger 130, and the heat receiving side heat exchanger 24 of the heat pump, and it is connected in order from the outlet of the feed water preheating unit 30 to the pump 32, the heat exchanger 130, the heat receiving side heat exchanger 24 of the heat pump 20, and the inlet of the feed water preheating unit 30. In the heat exchanger 130, a pipe L3 through which the circulating water for the water-cooled jacket circulates is formed, and it is connected in order from the outlet of the heat exchanger 130 to the water-cooled jacket structure 114, the pump 132, and the inlet of the heat exchanger 130. The waste heat recovery device 10 for a boiler facility of the present invention is configured such that the heat pump medium, the preheating medium, and the water-cooled jacket circulating water circulate during the process of heat-exchanging groundwater to turn it into secondary steam, and no drained water is generated.

[0018] (Operation) The operation of the waste heat recovery device 10 for a boiler facility of the present invention having the above configuration will be described below. In the process of generating primary steam in the boiler facility, the cooling water jacket circulating water of the cooling water jacket structure 114 is heated (for example, to 80°C to 90°C). The cooling water jacket circulating water exchanges heat with the preheating medium in the heat exchanger 130. At this time, the preheating medium is heated to 80°C. The preheating medium is heat-exchanged in the heat receiving side heat exchanger 24 of the heat pump 20. The preheating medium cooled by the heat exchange (for example, to 70°C) is heat-exchanged with the groundwater (for example, 20°C) in the feed water preheating section 30 and further cooled, and then sent to the heat exchanger 130. The heat pump medium heat-exchanged with the preheating medium is adiabatically compressed by the compressor 28 and generates heat. Also, the groundwater preheated (for example, to 65°C) in the feed water preheating section 30 is heat-exchanged in the heat radiating side heat exchanger 22 to become secondary steam (for example, 120°C), and the heat pump medium radiates heat and liquefies under high pressure. The liquefied heat pump medium has its pressure reduced when passing through the throttle valve 26. The heat pump medium adiabatically expands and receives heat from the preheating medium in the heat receiving side heat exchanger 24 and vaporizes. The vaporized heat pump medium is compressed again by the compressor 28, and the process is repeated thereafter.

[0019] The secondary steam generated by the heat pump 20 is supplied to the dust collector 140. Specifically, the secondary steam is supplied to the pipe arranged on the outer surface of the dust collector 140 to heat the entire filter to a predetermined temperature. Thereby, condensation of corrosive components can be suppressed and corrosion can be prevented. Also, the secondary steam is supplied to the chimney 144 of the dust collector 140. Specifically, the secondary steam is supplied to the pipe arranged on the outer surface of the chimney 144 to heat the chimney body to a predetermined temperature. Thereby, condensation of corrosive components in the chimney can be suppressed and corrosion can be prevented. Also, the secondary steam is supplied to the groundwater supply pipe of the heat exchanger 130. Specifically, it is supplied to a tube covering the supply pipe or the like to heat the entire pipe. Thereby, in winter, it is possible to prevent the groundwater supply pipe from freezing, and stable supply of groundwater can be realized throughout the year.

[0020] In addition, the secondary steam is supplied to the exhaust gas duct 146 of the dust collector 140. Specifically, it is supplied through a tube or the like that covers the exhaust gas duct to heat the entire duct. This can prevent a temperature drop when supplying it to the hot air generator 110 and maintain a high combustion efficiency. Also, condensation can be suppressed and corrosion can be prevented. According to such a present invention, secondary steam can be generated from hot water at a predetermined temperature generated in the heat exchanger, that is, wastewater, and reused to maintain the dust collection function of the dust collector. Therefore, the primary steam can be effectively utilized for its original purpose to improve productivity.

[0021] As described above, the preferred embodiments of the present invention have been explained. However, the present invention is not limited to the above embodiments in any way, and various modifications are possible without departing from the gist of the present invention. In addition, the present invention is not limited to the combinations shown in the embodiments, and can be implemented by various combinations.

Description of Reference Numerals

[0022] 10 Waste heat recovery device for boiler equipment 20 Heat pump 22 Heat radiation side heat exchanger 24 Heat receiving side heat exchanger 26 Throttle valve 28 Compressor 30 Feed water preheating section 32 Pump 100 Boiler equipment 110 Hot air generator 112 Primary air fan 114 Water-cooled jacket structure 120 Waste heat boiler 130 Heat exchanger 132 Pump 140 Dust collector 142 Bag filter 144 Chimney 146 Exhaust gas duct

Claims

1. A heat generation furnace provided with a water-cooled jacket structure on a wall surface, a waste heat boiler that generates primary steam by exchanging heat with combustion gas generated in the heat generation furnace, a dust collector that collects dust from exhaust gas after heat exchange, and a heat pump that generates secondary steam using drainage from the heat exchanger of the boiler equipment having a heat exchanger that exchanges heat with cooling water of the water-cooled jacket structure, and characterized in that the secondary steam is supplied to the dust collector.

2. A waste heat recovery device for boiler equipment according to Claim 1, characterized in that the secondary steam is supplied to the outer surface of the chimney of the dust collector.

3. A waste heat recovery device for boiler equipment according to Claim 1 or 2, characterized in that the groundwater supply pipe of the heat exchanger is heated with the secondary steam.

4. A waste heat recovery device for boiler equipment according to any one of Claims 1 to 3, characterized in that the secondary steam is used for heating the exhaust gas duct of the dust collector.

5. A waste heat recovery device for boiler equipment according to any one of Claims 1 to 4, characterized in that the secondary steam is supplied through a double pipe or a pipe wound with a heat-insulating tube.

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