Device for recovering waste heat of power plant to dry biomass fuel and using method

Abstract

The invention belongs to the technical field of energy, and particularly relates to a device for recycling waste heat of a power plant to dry biomass fuel and a using method. The device comprises an auxiliary steam header, a pressure matcher, a condenser hot well, a biomass fuel dryer and a flash tank. A gas outlet of the auxiliary steam header and a gas outlet of the condenser hot well are both communicated with a gas inlet of the pressure matcher; an air outlet of the pressure matcher is communicated with a thermal medium inlet of the biomass fuel dryer, a thermal medium outlet of the biomass fuel dryer is communicated with a water inlet of the flash tank, and an air outlet of the flash tank is communicated with an air inlet of the pressure matcher. According to the device, heat of gas generated by the auxiliary steam header and the condenser hot well is recycled to heat and dry wet biomass fuel, the comprehensive utilization rate of energy is increased, and the system operation cost is reduced; and waste heat energy generated by the power plant is utilized in a gradient mode, environmental pollution is reduced, and the environment-friendly energy development direction is met.

Description

Technical Field

[0001] This application belongs to the field of energy technology, specifically relating to a device and method for recovering waste heat from power plants to dry biomass fuel. Background Technology

[0002] Excessive moisture content in biomass power plants can lead to poor boiler combustion stability, low thermal efficiency, and may even cause low-temperature acid corrosion. Therefore, biomass fuel needs to be dried. Traditional drying methods, such as using coal or partially burning biomass, not only consume primary energy and reduce power plant efficiency but also increase SO2 and NO emissions. x And carbon emissions. Existing technologies also employ microwave drying, vacuum superconducting drying, etc., but these suffer from high investment and operating costs, and have poor applicability in the energy sector.

[0003] In power plants, the exhaust steam temperature of traditional condensing steam turbines is generally around 40°C, accounting for about 60% of the total heat input to the turbine. Currently, this exhaust steam is usually cooled by water-cooling or air-cooling systems, and the heat is ultimately released into the surrounding environment. At the same time, the cooling system also consumes a large amount of industrial water and electricity, resulting in a huge waste of energy. Summary of the Invention

[0004] This application provides an apparatus and method for recovering waste heat from power plants to dry biomass fuel, aiming to solve the problems of high cost, serious resource waste, and unenvironmentally unfriendly and uneconomical treatment of waste steam from power plants in existing biomass fuel drying processes.

[0005] The first aspect of this application provides an apparatus for recovering waste heat from power plants and drying biomass fuel, including an auxiliary steam header, a pressure matching device, a condenser hot water well, a biomass fuel dryer, and a flash tank;

[0006] The gas outlet of the auxiliary steam header and the gas outlet of the condenser hot water well are both connected to the air inlet of the pressure matcher; the air outlet of the pressure matcher is connected to the heat medium inlet of the biomass fuel dryer, the heat medium outlet of the biomass fuel dryer is connected to the water inlet of the flash tank, and the air outlet of the flash tank is connected to the air inlet of the pressure matcher.

[0007] According to some embodiments of the apparatus for recovering waste heat from power plants and drying biomass fuel as described in this application, it also includes a dry biomass fuel storage device, wherein the material outlet of the biomass fuel dryer is connected to the dry biomass fuel storage device.

[0008] The second aspect of this application provides a method for drying biomass fuel, which uses the apparatus for drying biomass fuel by recovering waste heat from power plants as described in the first aspect of this application.

[0009] According to some embodiments of the biomass fuel drying method described in this application, the method includes the following steps:

[0010] The auxiliary steam generated by the auxiliary steam header and the exhaust steam generated by the condenser hot water well are fed into the pressure matching device to generate low-pressure steam. The low-pressure steam is fed into the biomass fuel dryer to dry the biomass fuel. The condensate generated during the drying process enters the flash tank and is treated by the flash tank to form saturated steam. The saturated steam is fed into the air inlet of the pressure matching device for recycling.

[0011] According to some embodiments of the biomass fuel drying method described in this application, the temperature of the auxiliary steam generated by the auxiliary steam header is 280-320°C.

[0012] According to some embodiments of the biomass fuel drying method described in this application, the flow rate of the auxiliary steam introduced into the pressure matching device is 1.8-2.2 t / h.

[0013] According to some embodiments of the biomass fuel drying method described in this application, the pressure of the auxiliary steam introduced into the pressure matching device is 1-1.2 MPa.

[0014] According to some embodiments of the biomass fuel drying method described in this application, the temperature of the exhaust steam generated by the condenser hot water well is 38-45°C.

[0015] According to some embodiments of the biomass fuel drying method described in this application, the pressure of the exhaust steam introduced into the pressure matching device is 3-8 kPa.

[0016] According to some embodiments of the biomass fuel drying method described in this application, the flow rate of the exhaust steam introduced into the pressure matching device is 0.8-1.2 t / h.

[0017] According to some embodiments of the biomass fuel drying method described in this application, the temperature of the low-pressure steam introduced into the biomass fuel dryer is 180-220°C.

[0018] According to some embodiments of the biomass fuel drying method described in this application, the pressure of the low-pressure steam introduced into the biomass fuel dryer is 0.3-0.8 MPa.

[0019] According to some embodiments of the biomass fuel drying method described in this application, the flow rate of low-pressure steam introduced into the biomass fuel dryer is 2.6-3.4 t / h.

[0020] According to some embodiments of the biomass fuel drying method described in this application, the moisture content of the biomass fuel to be dried is 30-50%.

[0021] According to some embodiments of the biomass fuel drying method described in this application, the amount of biomass fuel to be dried fed into the biomass fuel dryer is 45-55 t / h.

[0022] According to some embodiments of the biomass fuel drying method described in this application, the temperature of the saturated steam is 90-110°C.

[0023] According to some embodiments of the biomass fuel drying method described in this application, the pressure of the saturated steam introduced into the pressure matching device is 0.08-0.12 MPa.

[0024] According to some embodiments of the biomass fuel drying method described in this application, the flow rate of the saturated steam introduced into the pressure matching device is 0.2-0.4 t / h.

[0025] According to some embodiments of the biomass fuel drying method described in this application, the moisture content of the biomass fuel obtained by drying in a biomass fuel dryer is 10%-15%.

[0026] The beneficial effects of this application include: the device for recovering waste heat from power plants to dry biomass fuel utilizes the heat from the gases generated by the auxiliary steam header and condenser hot water well to heat and dry the wet biomass fuel, thereby improving the comprehensive utilization rate of energy and reducing system operating costs. The device for recovering waste heat from power plants to dry biomass fuel enables the cascade utilization of waste heat energy generated by power plants, providing users with a stable heat supply, reducing environmental pollution, and aligning with the direction of green and environmentally friendly energy development. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the device for recovering waste heat from power plants and drying biomass fuel as described in this application. Detailed Implementation

[0028] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0029] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0030] This application provides an apparatus for recovering waste heat from power plants and drying biomass fuel, including an auxiliary steam header, a pressure matching device, a condenser hot water well, a biomass fuel dryer, and a flash tank;

[0031] The gas outlet of the auxiliary steam header and the gas outlet of the condenser hot water well are both connected to the air inlet of the pressure matcher; the air outlet of the pressure matcher is connected to the heat medium inlet of the biomass fuel dryer, the heat medium outlet of the biomass fuel dryer is connected to the water inlet of the flash tank, and the air outlet of the flash tank is connected to the air inlet of the pressure matcher.

[0032] The device for recovering waste heat from power plants to dry biomass fuel, as described in this application, recovers heat from the gases generated in the auxiliary steam header and condenser hot water well to heat and dry the wet biomass fuel, thereby improving the comprehensive utilization rate of energy and reducing system operating costs. This device enables the cascade utilization of waste heat energy generated by power plants, providing users with a stable heat supply, reducing environmental pollution, and aligning with the direction of green and environmentally friendly energy development.

[0033] In some embodiments of this application, a dry biomass fuel storage device is also included, wherein the material outlet of the biomass fuel dryer is connected to the dry biomass fuel storage device. The biomass fuel includes rice straw, agricultural and forestry waste, etc.

[0034] This application also provides a method for drying biomass fuel, which uses the apparatus for drying biomass fuel by recovering waste heat from power plants as described in the first aspect of this application.

[0035] In some embodiments of this application, the following steps are included: auxiliary steam generated by the auxiliary steam header and exhaust steam generated by the condenser hot water well are fed into a pressure matching device to generate low-pressure steam; the low-pressure steam is fed into a biomass fuel dryer to dry the biomass fuel, and the condensate generated during the drying process enters a flash tank, which is treated to form saturated steam, and the saturated steam is fed into the air inlet of the pressure matching device for recycling.

[0036] The auxiliary steam generated by the auxiliary steam header produces a high-speed airflow as it passes through the nozzles of the pressure matcher, creating a low-pressure zone at the nozzle outlet. In this zone, exhaust steam from the condenser hot water well is drawn in, ultimately forming low-pressure steam through mixing and diffusion. This low-pressure steam then enters the biomass fuel drying facility to dry the biomass fuel. During this process, the biomass fuel tumbles inside an inclined rotating drum, and the low-pressure steam indirectly heats the biomass fuel through the drum wall or internal heat exchange pipes, turning it into dry biomass fuel. Simultaneously, the low-pressure steam releases heat and becomes condensate.

[0037] After condensate enters the low-pressure flash tank, the sudden pressure drop causes the condensate to transform into saturated steam at that pressure, ultimately forming flash steam. The flash steam then enters the pressure matching unit, where it mixes with auxiliary steam to generate low-pressure steam, which is then recycled. During the initial startup phase of the device described in this application for recovering waste heat from power plants to dry biomass fuel, exhaust steam and auxiliary steam enter the pressure matching unit to produce low-pressure steam. Once the device is operating stably, auxiliary steam and flash steam simultaneously enter the pressure matching unit to produce low-pressure steam.

[0038] This application does not impose strict restrictions on the flash tank used. The key is to match the feed parameters (pressure, temperature, flow rate) with the operating pressure inside the tank to maximize the steam recovery while ensuring the stability and safety of the system.

[0039] As a preferred embodiment, the biomass fuel dryer used in this application is an intermittent heating dryer, which is safe, efficient, and energy-saving. A double-auger system is used to drive and agitate the straw, enhancing heat transfer between it and the heated wall surface.

[0040] In some embodiments of this application, the temperature of the auxiliary steam generated by the auxiliary steam header is 280-320°C; for example, 280°C, 300°C, 310°C, 318°C, 320°C, etc.

[0041] In some embodiments of this application, the flow rate of the auxiliary steam introduced into the pressure matching device is 1.8-2.2 t / h; for example, 1.8 t / h, 1.9 t / h, 2.0 t / h, 2.1 t / h, 2.2 t / h, etc.

[0042] In some embodiments of this application, the pressure of the auxiliary steam introduced into the pressure matching device is 1-1.2 MPa; for example, 1 MPa, 1.1 MPa, 1.2 MPa, etc.

[0043] The pressure matching device used in this embodiment mainly consists of three parts: a nozzle, a mixing chamber, and a diffuser. When the high-pressure fluid passes through the nozzle, the flow rate increases sharply and the pressure drops sharply, creating a vacuum that draws in the low-pressure fluid. After the two are fully mixed in the mixing chamber, the pressure is reduced and increased through the diffuser, and a medium-pressure mixed fluid is output.

[0044] In some embodiments of this application, the temperature of the exhaust steam generated by the condenser hot water well is 38-45°C; for example, 38°C, 40°C, 43°C, 45°C, etc.

[0045] In some embodiments of this application, the pressure of the exhaust steam inlet pressure matching device is 3-8 kPa; for example, 3 kPa, 5 kPa, 6 kPa, 8 kPa, etc.

[0046] In some embodiments of this application, the flow rate of the exhaust steam entering the pressure matching device is 0.8-1.2 t / h; for example, 0.8 t / h, 0.9 t / h, 1.0 t / h, 1.2 t / h, etc.

[0047] Waste heat from power plants comes from the exhaust steam from steam turbines. This exhaust steam typically enters the condenser, and the heat is carried away by circulating water through the cooling tower before finally being released into the atmosphere.

[0048] In some embodiments of this application, the temperature of the low-pressure steam introduced into the biomass fuel dryer is 180-220°C; for example, 180°C, 190°C, 200°C, 210°C, 220°C, etc.

[0049] In some embodiments of this application, the pressure of the low-pressure steam introduced into the biomass fuel dryer is 0.3-0.8 MPa; for example, 0.3 MPa, 0.5 MPa, 0.6 MPa, 0.8 MPa, etc.

[0050] In some embodiments of this application, the flow rate of low-pressure steam introduced into the biomass fuel dryer is 2.6-3.4 t / h; for example, 2.6 t / h, 2.8 t / h, 3.0 t / h, 3.2 t / h, 3.4 t / h, etc.

[0051] The device for drying biomass fuel by recovering waste heat from power plants described in this application uses a drum dryer. Inside the inclined rotating drum, the biomass tumbles with the drum and comes into contact with hot air / heated walls. It is suitable for granular and lumpy materials and has a large processing capacity. It adopts a co-current drying process, where the low-pressure steam flows in the same direction as the material, resulting in a fast initial drying speed and making it suitable for materials with high moisture content.

[0052] In some embodiments of this application, the moisture content of the biomass fuel to be dried is 30-50%; for example, 30%, 35%, 43%, 45%, 48%, 50%, etc.

[0053] In some embodiments of this application, the amount of biomass fuel to be dried fed into the biomass fuel dryer is 45-55 t / h; for example, 45 t / h, 48 t / h, 50 t / h, 53 t / h, 55 t / h, etc.

[0054] In some embodiments of this application, the temperature of the saturated steam is 90-110°C; for example, 90°C, 95°C, 98°C, 100°C, 110°C, etc.

[0055] In some embodiments of this application, the pressure of the saturated steam introduced into the pressure matching device is 0.08-0.12 MPa; for example, 0.08 MPa, 0.09 MPa, 0.10 MPa, 0.12 MPa, etc.

[0056] In some embodiments of this application, the flow rate of the saturated steam introduced into the pressure matching device is 0.2-0.4 t / h; for example, 0.2 t / h, 0.3 t / h, 0.4 t / h, etc.

[0057] In some embodiments of this application, the moisture content of the biomass fuel obtained by drying in a biomass fuel dryer is 10%-15%; for example, 10%, 12%, 13%, 15%, etc.

[0058] The technical solution of this application will be further described below with reference to specific embodiments.

[0059] Example 1

[0060] An apparatus for recovering waste heat from power plants and drying biomass fuel includes an auxiliary steam header, a pressure matching device, a condenser hot water well, a biomass fuel dryer, a flash tank, and a dry biomass fuel storage device.

[0061] The gas outlet of the auxiliary steam header and the gas outlet of the condenser hot water well are both connected to the inlet of the pressure matcher; the outlet of the pressure matcher is connected to the heat medium inlet of the biomass fuel dryer, the heat medium outlet of the biomass fuel dryer is connected to the water inlet of the flash tank, and the outlet of the flash tank is connected to the inlet of the pressure matcher; the material outlet of the biomass fuel dryer is connected to the dry biomass fuel storage device.

[0062] Example 2

[0063] A method for drying biomass fuel includes the following steps:

[0064] Auxiliary steam at 300℃ generated by the auxiliary steam header is introduced into the pressure matching device at a flow rate of 2t / h, so that the pressure of the auxiliary steam entering the pressure matching device is 1MPa; at the same time, exhaust steam at 40℃ generated by the condenser hot water well is introduced into the pressure matching device at a flow rate of 1t / h, so that the pressure of the exhaust steam entering the pressure matching device is 5kPa; the auxiliary steam and exhaust steam are mixed in the pressure matching device to generate low-pressure steam at 200℃.

[0065] Low-pressure steam is introduced into the biomass fuel dryer at a flow rate of 3 t / h, with the pressure of the low-pressure steam entering the dryer being 0.5 MPa. Simultaneously, biomass fuel with a moisture content of 40% is introduced into the biomass fuel dryer, and the flow rate of the biomass fuel to be dried is controlled at 50 t / h. The biomass fuel is dried using low-pressure steam, and the condensate generated during the drying process flows into a flash tank, where it is treated to form saturated steam at a temperature of 100°C. The above-mentioned saturated steam is introduced into a pressure matching device at a flow rate of 0.3 t / h, with the pressure of the saturated steam introduced into the pressure matching device being 0.1 MPa. The resulting dried biomass fuel with a moisture content of 15% is then transported to a dry biomass fuel storage device.

[0066] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A device for recovering waste heat from power plants to dry biomass fuel, characterized in that, This includes auxiliary steam headers, pressure matching devices, condenser hot water wells, biomass fuel dryers, and flash tanks; The gas outlet of the auxiliary steam header and the gas outlet of the condenser hot water well are both connected to the air inlet of the pressure matcher; the air outlet of the pressure matcher is connected to the heat medium inlet of the biomass fuel dryer, the heat medium outlet of the biomass fuel dryer is connected to the water inlet of the flash tank, and the air outlet of the flash tank is connected to the air inlet of the pressure matcher.

2. The apparatus for recovering waste heat from power plants and drying biomass fuel according to claim 1, characterized in that, It also includes a dry biomass fuel storage device, wherein the material outlet of the biomass fuel dryer is connected to the dry biomass fuel storage device.

3. A method for drying biomass fuel, characterized in that, The drying process is carried out using the apparatus for recovering waste heat from power plants and drying biomass fuel as described in any one of claims 1-2.

4. The method for drying biomass fuel according to claim 3, characterized in that, Includes the following steps: The auxiliary steam generated by the auxiliary steam header and the exhaust steam generated by the condenser hot water well are fed into the pressure matching device to generate low-pressure steam. The low-pressure steam is fed into the biomass fuel dryer to dry the biomass fuel. The condensate generated during the drying process enters the flash tank and is treated by the flash tank to form saturated steam. The saturated steam is fed into the air inlet of the pressure matching device for recycling.

5. The method for drying biomass fuel according to claim 4, characterized in that, The temperature of the auxiliary steam generated by the auxiliary steam header is 280-320℃; And / or, the flow rate of the auxiliary steam introduced into the pressure matching device is 1.8-2.2 t / h; And / or, the pressure of the auxiliary steam introduced into the pressure matching device is 1-1.2 MPa.

6. The method for drying biomass fuel according to claim 4, characterized in that, The temperature of the exhaust steam generated by the hot water well of the condenser is 38-45℃; And / or, the pressure of the exhaust steam introduced into the pressure matching device is 3-8 kPa; And / or, the flow rate of the exhaust steam into the pressure matching device is 0.8-1.2 t / h.

7. The method for drying biomass fuel according to claim 4, characterized in that, The temperature of the low-pressure steam introduced into the biomass fuel dryer is 180-220℃; And / or, the pressure of the low-pressure steam introduced into the biomass fuel dryer is 0.3-0.8 MPa; And / or, the flow rate of low-pressure steam introduced into the biomass fuel dryer is 2.6-3.4 t / h.

8. The method for drying biomass fuel according to claim 4, characterized in that, The moisture content of the biomass fuel to be dried is 30-50%; And / or, the amount of biomass fuel to be dried fed into the biomass fuel dryer is 45-55 t / h.

9. The method for drying biomass fuel according to claim 4, characterized in that, The temperature of the saturated steam is 90-110℃; And / or, the pressure at which the saturated steam is introduced into the pressure matching device is 0.08-0.12 MPa; And / or, the flow rate of the saturated steam introduced into the pressure matching device is 0.2-0.4 t / h.

10. The method for drying biomass fuel according to claim 4, characterized in that, The moisture content of biomass fuel obtained by drying in a biomass fuel dryer is 10%-15%.

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