Waste steam and flue gas waste heat integrated recovery heat supply device for biomass power plant

Abstract

The invention discloses a biomass power plant dead steam and flue gas waste heat integrated recovery heat supply device which comprises the following components: a biomass boiler used for combusting biomass fuel and generating high-temperature steam, and a flue gas outlet of the biomass boiler is connected to a flue gas emission reduction and waste heat recovery integrated unit; a steam inlet of the steam turbine is connected with a high-temperature steam outlet of the biomass boiler, and a steam outlet of the steam turbine is connected to a high-temperature side inlet of the steam exhaust heat exchanger and a high-temperature side inlet of the condenser through valves; the steam exhaust heat exchanger is connected with the condenser. When the device is implemented, waste steam latent heat and flue gas sensible heat / latent heat are recovered in a stepped manner, so that the comprehensive heat efficiency is remarkably improved; seasonal mode switching is achieved through an arranged intelligent control system, namely flue gas waste heat is recycled preferentially in summer, and steam exhaust heat supply is combined in winter; fuel cost is counteracted through waste heat sales income, and the income during implementation of the device is increased.

Description

Technical Field

[0001] The present application relates to the field of waste heat recovery technology, and in particular to an integrated heat recovery and supply device for exhaust steam and flue gas waste heat from a biomass power plant. Background Art

[0002] With the booming development of green energy, biomass power plants, thanks to their renewable, low-carbon, and environmentally friendly properties, have become a vital component of the energy sector. However, during power generation, biomass power plants inevitably generate a large amount of low-grade waste heat, primarily from exhaust steam from steam turbines and waste heat from boiler flue gas. Turbine exhaust steam temperatures range from 40-80°C, while boiler flue gas waste heat temperatures range from 120-200°C.

[0003] Traditional technologies for handling this waste heat have significant shortcomings. Exhaust steam is often cooled directly to the environment using air or water cooling. This simple and direct approach overlooks the enormous thermal energy potential contained within the exhaust steam, resulting in the wasteful loss of this waste heat. While there is a degree of recovery and utilization of waste heat from boiler flue gas, the technology is limited, recovering only a portion of the heat, leaving a significant amount of waste heat unutilized.

[0004] This series of problems directly leads to unsatisfactory overall thermal efficiency in biomass power plants. Because the latent heat in exhaust steam and flue gases is not fully recovered, over 70% of the fuel's heat is lost in various forms during the power generation process. This is undoubtedly a huge waste of energy, not only increasing power generation costs but also defeating the original purpose of biomass power generation to save energy and reduce emissions.

[0005] Furthermore, current waste heat recovery technologies are severely limited in their adaptability. Existing waste heat recovery solutions are mostly designed for the large-scale, centralized operation of coal-fired power plants, making them difficult to directly adapt to the smaller, more decentralized biomass power plants. Small-scale biomass power plants differ significantly from coal-fired power plants in terms of equipment size, process flow, and operating parameters. This further complicates waste heat recovery and limits improvements in the energy efficiency of biomass power plants. Summary of the Invention

[0006] To this end, the present application provides an integrated heat recovery device for exhaust steam and flue gas waste heat from a biomass power plant to solve the problems of serious waste heat waste and insufficient technical adaptability in the existing technology.

[0007] In order to achieve the above objectives, this application provides the following technical solutions:

[0008] In a first aspect, a device for integrated heat recovery and supply of exhaust steam and flue gas waste heat from a biomass power plant comprises the following components:

[0009] A biomass boiler is used to burn biomass fuel and generate high-temperature steam. The flue gas outlet of the biomass boiler is connected to an integrated unit for flue gas emission reduction and waste heat recovery;

[0010] A steam turbine, wherein the steam inlet of the steam turbine is connected to the high-temperature steam outlet of the biomass boiler, and the steam outlet is connected to the high-temperature side inlet of the exhaust steam heat exchanger and the condenser respectively through valves;

[0011] The exhaust steam heat exchanger and the condenser, the high temperature side outlets merge and then return to the water inlet of the biomass boiler through the boiler feed water pressure pump and the boiler feed water heater in sequence, forming a boiler feed water cycle;

[0012] Integrated flue gas emission reduction and waste heat recovery unit: includes a desulfurization tower and a waste heat recovery tower. The desulfurization tower is connected to the spray pipe through a slurry circulation pump. The spray water outlet of the waste heat recovery tower is connected to the high-temperature side inlet of the flue gas spray water heat exchanger through a spray water circulation pump, and the low-temperature side inlet is connected to the heat network circulation pump.

[0013] Electric heat pump, the condenser water outlet of the electric heat pump merges with the low-temperature side water outlet of the exhaust steam heat exchanger and is then connected to the user heat exchanger, and the evaporator water outlet of the electric heat pump is connected to the low-temperature side of the flue gas spray water heat exchanger through a heat network circulation pump;

[0014] User-side mixed water system: The water outlet of the user's heat exchanger is divided into two routes, one of which returns to the water inlet of the electric heat pump condenser through the mixing water pump, and the other is connected to the water inlet of the electric heat pump evaporator;

[0015] Power grid: The steam turbine generates electricity and outputs it to the power grid, and the terminal electric heat pump is driven by electricity from the power grid;

[0016] Intelligent control system: Dynamically adjusts the exhaust steam and flue gas waste heat recovery ratio to match the heat load demand.

[0017] Preferably, a bypass line with a valve is provided between the evaporator of the terminal electric heat pump and the flue gas spray water heat exchanger. The bypass line is used to switch the waste heat recovery mode according to the season: in summer, the flue gas waste heat is recovered first, and in winter, exhaust steam is combined for heating.

[0018] Preferably, the waste heat recovery tower uses a corrosion-resistant fluoroplastic heat exchanger and integrates a self-cleaning structure.

[0019] Preferably, the steam turbine is provided with a multi-stage steam extraction port, the high-pressure side extraction steam is used to drive the boiler feed water heater, and the low-pressure side extraction steam is connected to the absorption heat exchange unit.

[0020] Preferably, the low-temperature side of the flue gas spray water heat exchanger is connected in series with the low-temperature side of the exhaust steam heat exchanger to form a heat network water circulation loop, and the recovered waste heat is transported to the user end through the heat network circulation pump.

[0021] Preferably, a heat storage tank is also included to buffer heat source fluctuations and optimize waste heat distribution through an intelligent control system.

[0022] Preferably, a water purification module is provided in the spray water cycle of the flue gas emission reduction and waste heat recovery integrated unit to remove particulate matter and acidic substances in the flue gas condensate water.

[0023] Preferably, the terminal electric heat pump is replaced by an absorption heat pump, which is driven by steam extraction from a steam turbine.

[0024] Preferably, the intelligent control system integrates AI algorithms to monitor the heat network load, ambient temperature and fuel characteristics in real time, dynamically adjust the heat pump power and heat exchanger valve opening, and achieve optimized operation under all working conditions.

[0025] Compared with the prior art, this application has at least the following beneficial effects:

[0026] 1. When this device is implemented, the comprehensive thermal efficiency is significantly improved by cascading the recovery of exhaust steam latent heat and flue gas sensible heat / latent heat;

[0027] 2. Seasonal mode switching is achieved through the intelligent control system, that is, priority is given to recovering flue gas waste heat in summer, and exhaust steam is combined for heating in winter;

[0028] 3. The profit from waste heat sales can offset the fuel cost, thus increasing the profit from the implementation of the device;

[0029] 4. Corrosion-resistant materials and modular design are suitable for biomass power plants of different sizes and support multi-energy complementarity with solar energy, ground-source heat pumps, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] To more intuitively illustrate the prior art and the present application, exemplary drawings are provided below. It should be understood that the specific shapes and structures shown in the drawings should not generally be considered as limiting conditions for implementing the present application; for example, based on the technical concepts disclosed in this application and the exemplary drawings, those skilled in the art are capable of easily making routine adjustments or further optimizations to the addition / reduction / attribution division, specific shapes, positional relationships, connection methods, dimensional ratios, etc. of certain units (components).

[0031] Figure 1 This is a schematic structural diagram of a biomass power plant exhaust steam and flue gas waste heat integrated recovery and heat supply device according to the present application;

[0032] Description of reference numerals:

[0033] 1. Biomass boiler; 2. Steam turbine; 3. Exhaust steam heat exchanger; 4. Condenser; 5. Boiler feed water booster pump; 6. Boiler feed water heater;

[0034] 7. Integrated unit for flue gas emission reduction and waste heat recovery; 7a. Desulfurization tower; 7b. Waste heat recovery tower;

[0035] 8. Flue gas spray water heat exchanger;

[0036] 10. Electric heat pump;

[0037] 11. User heat exchanger;

[0038] 13. Heating network circulation pump;

[0039] 16. Spray water circulation pump;

[0040] 19. Power grid;

[0041] 22. Absorption heat exchange unit. DETAILED DESCRIPTION

[0042] The present application will be further described below in detail through specific embodiments in conjunction with the accompanying drawings.

[0043] like Figure 1 As shown, a biomass power plant exhaust steam and flue gas waste heat integrated recovery and heat supply device includes the following components:

[0044] A biomass boiler 1 is used to burn biomass fuel and generate high-temperature steam, and a flue gas outlet of the biomass boiler 1 is connected to a flue gas emission reduction and waste heat recovery integrated unit 7;

[0045] Steam turbine 2, the steam inlet of steam turbine 2 is connected to the high-temperature steam outlet of biomass boiler 1, and the steam outlet is connected to the high-temperature side inlet of exhaust steam heat exchanger 3 and condenser 4 respectively through valves;

[0046] The exhaust steam heat exchanger 3 and the condenser 4, the high temperature side water outlet merges and then passes through the boiler feed water pressure pump 5 and the boiler feed water heater 6 in turn to return to the water inlet of the biomass boiler 1, forming a boiler feed water cycle;

[0047] The low-temperature exhaust steam (40-80°C) discharged from the steam turbine 2 is directly used to heat the circulating water in the heating network through the exhaust steam heat exchanger 3, or is heated to 80-90°C through the terminal electric heat pump 10 to meet the central heating demand;

[0048] Integrated flue gas emission reduction and waste heat recovery unit 7: includes a desulfurization tower 7a and a waste heat recovery tower 7b. The desulfurization tower 7a is connected to the spray pipe via a slurry circulation pump 18. The spray water outlet of the waste heat recovery tower 7b is connected to the high-temperature side inlet of the flue gas spray water heat exchanger 8 via a spray water circulation pump 16. The low-temperature side inlet is connected to the heat network circulation pump 13. After being purified by the desulfurization tower 7a, the boiler flue gas enters the waste heat recovery tower 7b. Through direct contact heat exchange between the spray water and the flue gas, the sensible heat and the latent heat of condensation of water vapor are recovered, and the flue gas temperature is reduced from 200°C to below 40°C, thereby improving the utilization rate of waste heat.

[0049] The electric heat pump 10, the condenser water outlet of the electric heat pump 10 is connected to the user heat exchanger 11 after merging with the low-temperature side water outlet of the exhaust steam heat exchanger 3, and the evaporator water outlet of the electric heat pump 10 is connected to the low-temperature side of the flue gas spray water heat exchanger 8 through the heat network circulation pump 13;

[0050] User-side mixed water system: The water outlet of the user heat exchanger 11 is divided into two routes, one of which returns to the water inlet of the condenser of the electric heat pump 10 through the mixing water pump 12, and the other is connected to the water inlet of the evaporator of the electric heat pump 10;

[0051] Grid 19: The steam turbine 2 generates electricity and outputs it to the grid, and the terminal electric heat pump 10 is driven by electricity from the grid;

[0052] Intelligent control system: Dynamically adjusts the recovery ratio of exhaust steam and flue gas waste heat to match the heat load demand. The intelligent control system dynamically matches the heat load demand. For example, in winter, the electric heat pump 10 is used to combine exhaust steam and flue gas waste heat for heating, while in summer, flue gas waste heat is preferentially used to supply process hot water, thereby maximizing the utilization of waste heat resources throughout the year.

[0053] This device achieves significant improvements in energy efficiency and environmental benefits by integrating the cascade recovery and coordinated heating of exhaust steam and flue gas waste heat from biomass power plants.

[0054] A bypass line with a valve is provided between the evaporator of the terminal electric heat pump 10 and the flue gas spray water heat exchanger 8. The bypass line is used to switch the waste heat recovery mode according to the season: in summer, the flue gas waste heat is recovered first, and in winter, exhaust steam is combined for heating. By setting the bypass line and the valve, seasonal operation mode switching is realized.

[0055] The waste heat recovery tower 7b uses a corrosion-resistant fluoroplastic heat exchanger with an integrated self-cleaning structure. The fluoroplastic can withstand an acidic environment of pH 2-12, extending the equipment life to more than 15 years. In addition, a rotating scraper is set in the spray water circulation to automatically remove fly ash from the heat exchange surface, greatly reducing the heat transfer efficiency attenuation rate.

[0056] The steam turbine 2 is provided with a multi-stage steam extraction port. The high-pressure side extraction steam is used to drive the boiler feed water heater 6, and the low-pressure side extraction steam is connected to the absorption heat exchanger unit 22. The high-pressure extraction steam (1.0-2.5MPa) drives the boiler feed water heater 6, reducing the boiler fuel consumption; the low-pressure extraction steam (0.1-0.5MPa) provides a driving heat source for the absorption heat pump, replacing part of the electricity consumption.

[0057] The low-temperature side of the flue gas spray water heat exchanger 8 is connected in series with the low-temperature side of the exhaust steam heat exchanger 3 to form a heat network water circulation loop. The recovered waste heat is transported to the user end through the heat network circulation pump 13. The flue gas waste heat (50-60°C) and the exhaust steam waste heat (40-50°C) heat the same heat network water flow in stages, and the water temperature increase gradient is more gentle; the heat network circulation pump 13 uniformly controls the flow rate to avoid pressure imbalance caused by multiple circuits.

[0058] It also includes a heat storage tank to buffer fluctuations in the heat source and optimizes waste heat distribution through an intelligent control system to ensure stable heating supply.

[0059] Store excess heat when the heat load is low (such as process hot water in summer) and release it to the user end during peak hours; when the biomass fuel supply is interrupted, the heat storage tank can maintain heating for 4-6 hours.

[0060] A water purification module is provided in the spray water cycle of the flue gas emission reduction and waste heat recovery integrated unit 7, with a filtration accuracy of 10 μm, to prevent heat exchanger blockage, remove particulate matter and acidic substances in flue gas condensate water, and prevent pipeline blockage.

[0061] The terminal electric heat pump 10 is replaced by an absorption heat pump, which uses low-pressure steam extraction (0.2 MPa) from the steam turbine as a heat source to reduce power consumption of the grid and is driven by steam extraction from the steam turbine.

[0062] The intelligent control system integrates AI algorithms to monitor the heat network load, ambient temperature and fuel characteristics in real time, dynamically adjust the heat pump power and heat exchanger valve opening, and achieve optimized operation under all working conditions. Based on historical data and meteorological parameters, the heat pump power and valve opening are adjusted in advance. It can also calculate the marginal benefits of waste heat recovery in real time and give priority to the most economical heat source combination.

[0063] The technical features of the above embodiments can be combined arbitrarily (as long as there is no contradiction in the combination of these technical features). In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described; these embodiments that are not explicitly written should also be considered to be within the scope of this specification.

Claims

1. A biomass power plant exhaust steam and flue gas waste heat integrated recovery and heat supply device, characterized in that: Includes the following components: A biomass boiler (1) is used to burn biomass fuel and generate high-temperature steam, and a flue gas outlet of the biomass boiler (1) is connected to a flue gas emission reduction and waste heat recovery integrated unit (7); A steam turbine (2), wherein the steam inlet of the steam turbine (2) is connected to the high-temperature steam outlet of the biomass boiler (1), and the steam outlet is connected to the high-temperature side inlets of the exhaust steam heat exchanger (3) and the condenser (4) respectively through valves; The exhaust steam heat exchanger (3) and the condenser (4) are joined at the high temperature side outlet and then return to the water inlet of the biomass boiler (1) through the boiler feed water pressure pump (5) and the boiler feed water heater (6) in sequence, forming a boiler feed water cycle; The flue gas emission reduction and waste heat recovery integrated unit (7) comprises a desulfurization tower (7a) and a waste heat recovery tower (7b), wherein the desulfurization tower (7a) is connected to a spray pipe via a slurry circulation pump (18), and the spray water outlet of the waste heat recovery tower (7b) is connected to a high-temperature side inlet of a flue gas spray water heat exchanger (8) via a spray water circulation pump (16), and the low-temperature side inlet is connected to a heat network circulation pump (13); An electric heat pump (10), wherein the condenser water outlet of the electric heat pump (10) is connected to the low-temperature side water outlet of the exhaust steam heat exchanger (3) and then connected to the user heat exchanger (11), and the evaporator water outlet of the electric heat pump (10) is connected to the low-temperature side of the flue gas spray water heat exchanger (8) through a heat network circulation pump (13); The user side water mixing system, the water outlet of the user heat exchanger (11) is divided into two paths, one path returns to the water inlet of the condenser of the electric heat pump (10) through the water mixing pump (12), and the other path is connected to the water inlet of the evaporator of the electric heat pump (10); The steam turbine (2) generates electricity and outputs it to the power grid, and the terminal electric heat pump (10) is driven by electricity from the power grid; Intelligent control system: Dynamically adjusts the exhaust steam and flue gas waste heat recovery ratio to match the heat load demand.

2. The integrated heat recovery and supply device for exhaust steam and flue gas waste heat from a biomass power plant according to claim 1 is characterized in that: A bypass pipeline with a valve is provided between the evaporator of the terminal electric heat pump (10) and the flue gas spray water heat exchanger (8), and the bypass pipeline is used to switch the waste heat recovery mode according to the season: in summer, the flue gas waste heat is recovered first, and in winter, exhaust steam is combined for heating.

3. The integrated heat recovery and supply device for exhaust steam and flue gas waste heat from a biomass power plant according to claim 1 is characterized in that: The waste heat recovery tower (7b) adopts a corrosion-resistant fluoroplastic heat exchanger and is integrated with a self-cleaning structure.

4. The integrated heat recovery and supply device for exhaust steam and flue gas waste heat from a biomass power plant according to claim 1 is characterized in that: The steam turbine (2) is provided with a multi-stage steam extraction port, the high-pressure side steam extraction is used to drive the boiler feed water heater (6), and the low-pressure side steam extraction is connected to the absorption heat exchange unit (22).

5. The integrated heat recovery and supply device for exhaust steam and flue gas waste heat from a biomass power plant according to claim 1 is characterized in that: The low-temperature side of the flue gas spray water heat exchanger (8) is connected in series with the low-temperature side of the exhaust steam heat exchanger (3) to form a heat network water circulation loop, and the recovered waste heat is transported to the user end through the heat network circulation pump (13).

6. The integrated heat recovery and supply device for exhaust steam and flue gas waste heat from a biomass power plant according to claim 1 is characterized in that: It also includes a heat storage tank to buffer fluctuations in the heat source and optimizes waste heat distribution through an intelligent control system.

7. The integrated heat recovery and supply device for exhaust steam and flue gas waste heat from a biomass power plant according to claim 1 is characterized in that: A water purification module is provided in the spray water cycle of the flue gas emission reduction and waste heat recovery integrated unit (7) to remove particulate matter and acidic substances in the flue gas condensate water.

8. The integrated heat recovery and supply device for exhaust steam and flue gas waste heat from a biomass power plant according to claim 1 is characterized in that: The terminal electric heat pump (10) is replaced by an absorption heat pump, which is driven by steam extraction from a steam turbine.

9. The integrated heat recovery and supply device for exhaust steam and flue gas waste heat from a biomass power plant according to claim 1 is characterized in that: The intelligent control system integrates AI algorithms to monitor the heat network load, ambient temperature and fuel characteristics in real time, and dynamically adjusts the heat pump power and heat exchanger valve opening.

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