High-temperature flue gas waste heat recovery system in front of boiler tail flue desulfurizing tower

Abstract

The utility model relates to the technical field of boiler waste heat recovery, in particular to a high-temperature flue gas waste heat recovery system in front of a boiler tail flue desulfurizing tower, which comprises a desulfurizing tower, a gas inlet of the desulfurizing tower is connected with a slurry heat exchanger through a pipeline, and a spraying pipeline of the desulfurizing tower is connected with a heat pump evaporator; the heat pump evaporator is connected in series with the slurry heat exchanger through a pipeline; the slurry heat exchanger comprises an evaporator, an absorber, a condenser and a generator. High-temperature flue gas in front of the desulfurizing tower serves as a driving heat source to be used for heat recycling, on one hand, the exhaust gas temperature is reduced, the boiler efficiency is improved, on the other hand, the spraying water amount of the desulfurizing tower is reduced, and water resources are saved. The waste heat of the slurry is used for heating circulating water to serve as a low-temperature heat source, the waste heat of low-grade smoke which is difficult to use is utilized, and the energy grade of the waste heat is improved. Compared with other forms of gas-liquid heat exchangers, the slurry heat exchanger is used for heating low-temperature circulating water, so that the investment cost is low, and the system is easy to maintain.

Description

TECHNICAL FIELD

[0001] The utility model relates to a boiler waste heat recovery technical field, specifically a kind of high-temperature flue gas waste heat recovery system before boiler tail flue desulfurization tower. BACKGROUND

[0002] In active service thermal power generating unit, in order to prevent the low-temperature corrosion of boiler tail part, boiler exhaust temperature is generally designed as 120~150 ℃, in actual operation, due to the change of working condition, coal variety, heating surface ash pollution and other reasons, the actual exhaust temperature of part of power plant is often 10~40 ℃ higher than design value. And exhaust heat loss is the largest one in the various heat losses of boiler, about 60%~70% of balance calculation heat loss, research results show that: the boiler efficiency is improved 1% when exhaust temperature drops 20 ℃. Therefore, reducing the exhaust temperature of boiler, maximum utilization of flue gas waste heat, has become an important way to improve the thermal economy of unit.

[0003] At present, the heat recovery in the prior art still cannot meet the thermal recovery requirement of thermal power generating unit, and a high-temperature flue gas waste heat recovery system capable of recycling needs to be developed in combination with the existing structure and equipment. UTILITY MODEL CONTENT

[0004] The utility model aims at providing a kind of high-temperature flue gas waste heat recovery system before boiler tail flue desulfurization tower to solve the problems raised in the above background.

[0005] To achieve the above object, the utility model provides the following technical scheme:

[0006] A kind of high-temperature flue gas waste heat recovery system before boiler tail flue desulfurization tower, including desulfurization tower, desulfurization tower gas inlet is connected with slurry heat exchanger by pipeline, and the spray pipeline of desulfurization tower is connected with heat pump evaporator;Heat pump evaporator is connected with slurry heat exchanger by pipeline in series connection;Slurry heat exchanger includes evaporator, absorber, condenser and generator.

[0007] Preferably, the circulating water inlet of evaporator is connected with the circulating water outlet of heat pump evaporator by pipeline;The circulating water outlet of evaporator is connected with circulating pump, the circulating water inlet of heat pump evaporator in series connection by pipeline;Evaporator is connected with absorber by pipeline. Evaporator heats the coolant in slurry heat exchanger by circulating water to absorb heat.

[0008] Preferably, absorber includes primary heating water inlet and primary heating water outlet;Absorber also includes dilute solution discharge outlet, and solution heat exchanger, throttling valve, generator are connected in series connection by pipeline with solution discharge outlet;The concentrated solution discharge outlet of generator is connected with first water pump, solution heat exchanger, absorber in series connection by pipeline. Heating water includes heat network water, desalted water and the like, and absorber is used to heat heat network water, desalted water.

[0009] Preferably, the generator comprises a high-temperature flue gas inlet and a low-temperature flue gas outlet; the low-temperature flue gas outlet is connected with the desulfurization tower gas inlet; the generator is connected with the condenser through a pipeline. The generator heats the cold agent by high-temperature flue gas for absorbing the heat of high-temperature flue gas.

[0010] Preferably, the condenser comprises a secondary heating water inlet and a secondary heating water outlet, and the secondary heating water inlet is connected with the primary heating water outlet through a pipeline; the condenser is connected with the second water pump and the evaporator in series through a pipeline. The condenser cools the cold agent and provides the evaporator with secondary heating hot network water and desalted water.

[0011] Compared with the prior art, the utility model has the advantages that:

[0012] 1. The high-temperature flue gas before the desulfurization tower is used as a driving heat source for heat recycling, which reduces the exhaust gas temperature and improves the boiler efficiency, and reduces the spraying water amount of the desulfurization tower and saves water resources;

[0013] 2. The circulating water is heated by the slurry waste heat as a low-temperature heat source, which utilizes the waste heat of low-grade flue gas that is difficult to utilize and improves the energy grade of waste heat;

[0014] 3. The low-temperature circulating water is heated by the slurry heat exchanger, which has lower investment cost than other forms of gas-liquid heat exchangers and is easy to maintain. BRIEF DESCRIPTION OF DRAWINGS

[0015] Fig. 1 It is a structural schematic view of the utility model.

[0016] Fig. 2 It is a structural schematic view of the slurry heat exchanger in the utility model.

[0017] In the drawing: 1, desulfurization tower, 2, slurry heat exchanger, 3, heat pump evaporator, 4, evaporator, 5, absorber, 6, condenser, 7, generator, 8, circulating pump, 9, first water pump, 10, second water pump, 41, circulating water inlet, 42, circulating water outlet, 51, primary heating water inlet, 52, primary heating water outlet, 53, solution heat exchanger, 54, throttling valve, 71, high-temperature flue gas inlet, 72, high-temperature flue gas outlet, 61, secondary heating water inlet, 62, secondary heating water outlet. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the utility model.

[0019] Please refer to Figs. 1-2 The utility model provides a kind of high-temperature flue gas waste heat recovery system before boiler tail flue desulfurization tower, including desulfurization tower 1, and the inlet of desulfurization tower 1 is connected with slurry heat exchanger 2 by pipeline, and the spray pipeline of desulfurization tower 1 is connected with heat pump evaporator 3;Heat pump evaporator 3 is connected with slurry heat exchanger 2 by pipeline in series connection;Slurry heat exchanger 2 includes evaporator 4, absorber 5, condenser 6 and generator 7.

[0020] Wherein, the circulating water inlet 41 of evaporator 4 is connected with heat pump evaporator 3 by pipeline;The circulating water outlet 42 of evaporator 4 is connected with circulating pump 8, heat pump evaporator 3 in series connection by pipeline;Evaporator 4 is connected with absorber 5 by pipeline.Evaporator 4 heats the coolant in slurry heat exchanger 2 by circulating water, to absorb heat.

[0021] Wherein, absorber 5 includes primary heating water inlet 51 and primary heating water outlet 52;Absorber 5 also includes dilute solution discharge outlet, and solution discharge outlet is connected with solution heat exchanger 53, throttling valve 54, generator 7 in series connection by pipeline;The concentrated solution discharge outlet of generator 7 is connected with first water pump 9, solution heat exchanger 53, absorber 5 in series connection by pipeline.Heating water includes heat network water, desalted water etc., and absorber is used to heat heat network water, desalted water once.

[0022] Wherein, generator 7 includes high-temperature flue gas inlet 71 and low-temperature flue gas outlet 72;Low-temperature flue gas outlet 72 is connected with the inlet of desulfurization tower 1;Generator 7 is connected with condenser 6 by pipeline.Generator 7 heats coolant by high-temperature flue gas, to absorb high-temperature flue gas heat.

[0023] Further, condenser 6 includes secondary heating water inlet 61 and secondary heating water outlet 62, and secondary heating water inlet 61 is connected with primary heating water outlet 52 by pipeline;Condenser 6 is connected with second water pump 10, evaporator 4 in series connection by pipeline.Coolant is cooled by condenser 6 and provided to evaporator 4, and heat network water, desalted water is heated secondarily.

[0024] Specific operation mode is as follows:

[0025] The heat source of the embodiment system comes from high-temperature flue gas before desulfurization and desalted water, heat network water etc.

[0026] The system takes circulating water from slurry heat exchanger as heating medium in heat pump evaporator, and in evaporator, coolant water outside pipe is heated by circulating water in pipe and evaporated into coolant steam, then enters absorber, and is absorbed by lithium bromide solution from generator, and the heat released in absorption process is used to heat desalted water or heat network water etc.

[0027] The dilute solution obtained after absorbing the refrigerant vapor leaves the absorber, enters the generator through a solution heat exchanger and a throttle valve, is heated by high-temperature flue gas to generate refrigerant vapor again, and the solution is concentrated into a concentrated solution, the first water pump sends the concentrated solution to the absorber through a heat exchanger to absorb the refrigerant vapor again. The low-pressure refrigerant vapor generated in the generator enters the condenser to heat the demineralized water or hot network water again, and the condensed refrigerant water is sent to the evaporator by the second water pump to be evaporated again, thereby completing the cycle.

[0028] The contents not described in detail in the description belong to the prior art known to those skilled in the art.

[0029] Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or make equivalent replacement to part of the technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the utility model shall be included in the protection scope of the utility model.

Claims

1. A high-temperature flue gas waste heat recovery system in front of a boiler back pass desulfurization tower, comprising a desulfurization tower, characterized in that: The desulfurization tower gas inlet is connected with the slurry heat exchanger through a pipeline, and the spray pipeline of the desulfurization tower is connected with the heat pump evaporator; the heat pump evaporator is connected with the slurry heat exchanger in series through a pipeline; and the slurry heat exchanger comprises an evaporator, an absorber, a condenser and a generator.

2. A system for recovering waste heat from high-temperature flue gas before a desulfurization tower of a boiler backpass according to claim 1, characterized in that: The circulating water inlet of the evaporator is connected with the heat pump evaporator through a pipeline; the circulating water outlet of the evaporator is connected with the circulating pump and the heat pump evaporator in series through a pipeline; and the evaporator is connected with the absorber through a pipeline.

3. A system for recovering waste heat from high temperature flue gases before a desulphurization tower of a boiler back pass according to claim 1, characterized in that: The absorber comprises a primary heating water inlet and a primary heating water outlet; the absorber further comprises a dilute solution discharge outlet, and the solution discharge outlet is connected with the solution heat exchanger, the throttling valve and the generator in series through a pipeline; the concentrated solution discharge outlet of the generator is connected with the first water pump, the solution heat exchanger and the absorber in series through a pipeline.

4. A system for recovering waste heat from high temperature flue gases before a desulphurization tower of a boiler back pass according to claim 1, characterized in that: The generator comprises a high-temperature flue gas inlet and a low-temperature flue gas outlet; the low-temperature flue gas outlet is connected with the desulfurization tower gas inlet; and the generator is connected with the condenser through a pipeline.

5. A system for recovering waste heat from high temperature flue gases before a desulphurization tower of a boiler back pass according to claim 3, characterized in that: The condenser comprises a secondary heating water inlet and a secondary heating water outlet, and the secondary heating water inlet is connected with the primary heating water outlet through a pipeline; and the condenser is connected with the second water pump and the evaporator in series through a pipeline.

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