Low-temperature flue gas waste heat recovery device

Abstract

According to the low-temperature flue gas waste heat recovery device, an outlet of a liquid collector is connected with an inlet of a circulating pump through a first circulating pipeline, the inlet of the circulating pump is further connected with a supply pipeline, and the supply pipeline is used for supplying fresh intermediate water to a liquid holding mechanism and the circulating pump; an outlet of the circulating pump is connected with the evaporator through a second circulating pipeline, the second circulating pipeline is communicated with an inlet of the liquid distributor after passing through the evaporator, and a condensate water discharging branch pipeline is arranged before entering the liquid distributor; the generator is connected with a driving heat source pipeline, the absorber is connected with a heat supply network water return pipeline, the condenser is connected with a heat supply network water supply pipeline, and the driving heat source pipeline is used for conveying steam or hot water. The device can efficiently achieve low-temperature flue gas waste heat recovery, has the functions of saving water and eliminating white smoke, and has good economic benefits and environmental benefits.

Description

Technical Field

[0001] The present application relates to the field of energy conservation and environmental protection, and in particular to a low-temperature flue gas waste heat recovery device. Background Art

[0002] Most of the flue gas desulfurization in my country adopts the limestone-gypsum wet desulfurization process, which reduces the flue gas temperature to 45-55℃. These low-temperature saturated wet flue gases directly enter the atmosphere through the chimney. Due to the huge amount of flue gas, a large amount of heat energy is lost. In addition, the saturated wet flue gas in this temperature range contains a large amount of water. After entering the atmosphere, it condenses into tiny droplets when it encounters cold, producing white smoke plumes, which not only causes visual pollution, but also wastes a lot of water resources. If the heat energy of these low-temperature flue gases is recovered and reused, it can effectively save energy and reduce carbon emissions, creating economic and environmental benefits.

[0003] At present, the application of low-temperature flue gas heat recovery in the domestic power industry is in its infancy. Chinese patent CN 113339872A discloses a slurry waste heat recycling system, in which a heat exchanger is set on the desulfurization tower slurry circulation pipe to obtain heat, and then the circulating water temperature is raised by a heat pump for heating. The device indirectly obtains the waste heat of low-temperature flue gas by taking heat from the slurry, which can realize the waste heat utilization and flue gas deoxidation function. However, the heat exchanger is set in the slurry circulation pipeline, which is easy to cause pipeline wear and blockage during operation, affecting the normal operation of the desulfurization device. Chinese patent CN117759944A discloses a flue gas water collection and waste heat utilization coupling system and process, in which a water collection tower is set downstream of the desulfurization tower, and a condenser is set in the upper part of the water collection tower to absorb the heat of low-temperature flue gas through indirect heat exchange. The saturated water vapor condenses into liquid water on the outer surface of the condenser, and plays a water-saving function at the same time. However, the process requires a single water collection tower, which occupies a large area. In addition, the condenser and the low-temperature flue gas are indirectly heat exchanged, the heat exchange efficiency is low, and the material consumption is large. Utility Model Content

[0004] One of the purposes of the present application is to provide a low-temperature flue gas waste heat recovery device, aiming to solve the problem that the existing low-temperature flue gas heat energy recovery device adopts indirect heat exchange with low efficiency.

[0005] The technical solution of this application is:

[0006] A low-temperature flue gas waste heat recovery device comprises a liquid holding mechanism arranged in a wet flue gas desulfurization tower and an absorption heat pump outside the tower, the liquid holding mechanism comprises a liquid collector, an S-shaped gas-liquid mass transfer structure and a liquid distributor arranged in sequence from bottom to top in the upper part of the tower, the absorption heat pump comprises an evaporator, a generator, an absorber and a condenser; the outlet of the liquid collector is connected to the inlet of a circulation pump through a first circulation pipeline, and a supply pipeline is also connected to the inlet of the circulation pump, and the supply pipeline is used to supply fresh intermediate water to the liquid holding mechanism and the circulation pump; the outlet of the circulation pump is connected to the evaporator through a second circulation pipeline, and the second circulation pipeline is connected to the inlet of the liquid distributor after passing through the evaporator, and a condensed water discharge branch pipeline is provided before entering the liquid distributor; the generator is connected to a driving heat source pipeline, the absorber is connected to a heat network return water pipeline, the condenser is connected to a heat network water supply pipeline, and the driving heat source pipeline is used to transport steam or hot water.

[0007] As a technical solution of the present application, a horizontal flue gas inlet channel is arranged in the middle of one side of the wet desulfurization tower, and the flue gas inlet channel includes a cylindrical channel and a right-angled trapezoidal channel connected in sequence, and the small end of the right-angled trapezoidal channel is connected to the cylindrical channel, and the large end is connected to the inner cavity of the wet desulfurization tower.

[0008] As a technical solution of the present application, a flue gas outlet channel is arranged on the top of the wet desulfurization tower, and the flue gas outlet channel includes a vertical channel and a horizontal channel connected in sequence in an L shape, and a folded plate demister is arranged in the horizontal channel.

[0009] As a technical solution of the present application, the liquid collector includes a main conveying pipeline and multiple branch collecting pipelines; the main conveying pipeline is connected to the first circulation pipeline; the multiple branch collecting pipelines are installed on the main conveying pipeline at intervals and are connected to the bottom of the S-shaped gas-liquid mass transfer structure, for collecting the liquid flowing out of the S-shaped gas-liquid mass transfer structure.

[0010] As a technical solution of the present application, the S-shaped gas-liquid mass transfer structure is horizontally arranged and includes a plurality of long strip plates with S-shaped cross-sections. The plurality of long strip plates are horizontally arranged and arranged in a row in sequence, and the S-shaped ends of adjacent long strip plates are staggered and spaced apart, and the intervals formed between adjacent long strip plates constitute an airflow channel.

[0011] As a technical solution of the present application, the liquid distributor includes a reflux pipe and a plurality of nozzles; the reflux pipe is arranged directly above the S-shaped gas-liquid mass transfer structure and is connected to the first circulation pipe; the plurality of nozzles are installed at intervals on the reflux pipe for uniformly spraying the circulating liquid onto the S-shaped gas-liquid mass transfer structure.

[0012] As a technical solution of the present application, the nozzle is a single-head nozzle or a one-way double-head nozzle.

[0013] Beneficial effects of this application:

[0014] The low-temperature flue gas waste heat recovery device of the present application includes a liquid holding mechanism arranged in the wet flue gas desulfurization tower and an absorption heat pump outside the tower. The liquid holding mechanism serves as a direct contact heat exchanger, and uses circulating intermediate water to cool the flue gas at the outlet of the desulfurization tower from 45 to 55°C to 30 to 40°C, recovering low-grade heat from the flue gas, and obtaining condensed water in the flue gas at the same time, and then using the absorption heat pump to extract the waste heat in the intermediate water to produce medium-grade heat energy for heating the return water of the heat network and other scenarios. The device can realize the recovery of low-temperature flue gas waste heat, and has the functions of water saving and flue gas whitening. The liquid holding mechanism has high heat exchange efficiency, does not occupy additional space, and is flexible to adjust without affecting the normal operation of the desulfurization device, and has good economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the implementation methods of the present application, the drawings required for use in the implementation methods will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 Schematic diagram of the low-temperature flue gas waste heat recovery device provided in an embodiment of the present application.

[0017] Icons: 1-wet desulfurization tower; 2-flue gas inlet channel; 3-flue gas outlet channel; 4-folded plate demister; 5-main delivery pipeline; 6-branch collection pipeline; 7-first circulation pipeline; 8-long strip plate; 9-reflux pipeline; 10-nozzle; 11-evaporator; 12-generator; 13-absorber; 14-condenser; 15-supply pipeline; 16-circulation pump; 17-second circulation pipeline; 18-condensate discharge branch pipeline; 19-driving heat source pipeline; 20-heat network return water pipeline; 21-heat network water supply pipeline. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0020] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0021] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the utility model product is usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0022] In addition, in the present application, unless otherwise clearly specified and limited, the first feature being above or below the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through another feature between them. Moreover, the first feature being above, above, and above the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being below, below, and below the second feature includes the first feature being directly below and obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0023] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0024] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0025] Example:

[0026] Please refer to Figure 1 The present application provides a low-temperature flue gas waste heat recovery device, which includes a liquid holding mechanism arranged in a wet flue gas desulfurization tower 1 and an absorption heat pump outside the tower, the liquid holding mechanism includes a liquid collector, an S-shaped gas-liquid mass transfer structure and a liquid distributor arranged in sequence in the upper part of the tower from bottom to top, and the absorption heat pump includes an evaporator 11, a generator 12, an absorber 13 and a condenser 14; wherein, the outlet of the liquid collector is connected to the inlet of a circulation pump 16 through a first circulation pipeline 7, and the inlet of the circulation pump 16 is also connected to a supply pipeline 15, and the supply pipeline 15 is used to supply fresh intermediate water to the liquid holding mechanism and the circulation pump 16, and when the device is started When the generator 10 is running, the supply pipe 15 replenishes fresh intermediate water for the device. A large amount of condensed water is precipitated during operation, and there is no need to replenish intermediate water, which can also play a role in water saving and reuse. At the same time, the outlet of the circulating pump 16 is connected to the evaporator 11 through the second circulating pipe 17, and the second circulating pipe 17 is connected to the inlet of the liquid distributor after passing through the evaporator 11, and a condensed water discharge branch pipe 18 is provided before entering the liquid distributor. The generator 12 is connected to the driving heat source pipe 19, the absorber 13 is connected to the heat network return pipe 20, the condenser 14 is connected to the heat network water supply pipe 21, and the driving heat source pipe 19 is used to transport steam or hot water.

[0027] Furthermore, a horizontal flue gas inlet channel 2 is provided at the middle of one side of the wet desulfurization tower 1, and the flue gas inlet channel 2 includes a cylindrical channel and a right-angled trapezoidal channel connected in sequence, and the small end of the right-angled trapezoidal channel is connected to the cylindrical channel, and the large end is connected to the inner cavity of the wet desulfurization tower 1. At the same time, a flue gas outlet channel 3 is provided at the top of the wet desulfurization tower 1, and the flue gas outlet channel 3 includes a vertical channel and a horizontal channel connected in sequence in an L shape, and a folded plate demister 4 is provided in the horizontal channel.

[0028] Before starting the device, fresh intermediate water is added to the system through the supply pipe 15, and the circulation pump 16, the first circulation pipe 7, the liquid collector, and the bottom plate of the S-shaped gas-liquid mass transfer structure are all filled with water, and then the circulation pump 16 is started.

[0029] In addition, its liquid collector includes a main conveying pipeline 5 and multiple branch collecting pipelines 6; the main conveying pipeline 5 is connected to the first circulation pipeline 7; multiple branch collecting pipelines 6 are installed on the main conveying pipeline 5 at intervals, and are connected to the bottom of the S-shaped gas-liquid mass transfer structure, for collecting liquid flowing out of the S-shaped gas-liquid mass transfer structure.

[0030] At the same time, the S-shaped gas-liquid mass transfer structure is horizontally arranged and includes a plurality of long strip plates 8 with S-shaped cross-sections. The plurality of long strip plates 8 are horizontally arranged and staggered in a row in sequence, and the S-shaped ends of adjacent long strip plates 8 are staggered and spaced apart, and the intervals formed between adjacent long strip plates 8 constitute an airflow channel.

[0031] In addition, the liquid distributor includes a reflux pipe 9 and a plurality of nozzles 10; the reflux pipe 9 is arranged directly above the S-shaped gas-liquid mass transfer structure and is connected to the first circulation pipe 7; the plurality of nozzles 10 are installed on the reflux pipe 9 at intervals, and are used to evenly spray the circulating liquid onto the S-shaped gas-liquid mass transfer structure.

[0032] It should be noted that, in this embodiment, the nozzle 10 may be a single-head nozzle or a one-way double-head nozzle.

[0033] It should be noted that the principle of the device is:

[0034] The flue gas after desulfurization by the wet flue gas desulfurization tower 1 is saturated wet flue gas at 45-55°C. The low-temperature flue gas enters the liquid holding mechanism and performs direct contact heat exchange with the room-temperature intermediate water in the liquid holding mechanism. The flue gas temperature drops to 30-35°C. The intermediate water absorbs the heat of the flue gas and its temperature rises. At the same time, condensed water is precipitated from the flue gas during the cooling process, and the condensed water merges into the intermediate water. The intermediate water and condensed water with increased temperature after heat exchange by the liquid holding mechanism are collected by the liquid collector and sent to the evaporator 11 in the absorption heat pump through the circulation pump 16. The intermediate water and condensed water release heat and flow back to the liquid distributor. The excess intermediate water and condensed water are discharged to the desulfurization area through the condensed water discharge branch pipe 18 for reuse. ; The intermediate water and condensed water after releasing heat are evenly distributed to the S-type gas-liquid mass transfer structure by the liquid distributor. When the flue gas flows through the S-type gas-liquid mass transfer structure, the flue gas is fully mixed with the intermediate water inside to form a stable jet state. The intermediate water and the flue gas are in direct contact with each other for heat exchange, which is more efficient than indirect heat exchange such as tubular heat exchangers. Compared with the direct heat exchange of the spray cooling tower, the heat exchange of the liquid holding mechanism has both the spray heat exchange of the liquid distributor and the heat exchange of the S-type gas-liquid mass transfer structure, so the heat exchange efficiency is high. When the flue gas passes through the S-type gas-liquid mass transfer structure, it is violently stirred and fully mixed with the intermediate water, which improves the mass transfer effect, so the heat transfer efficiency is high in this state;

[0035] The driving heat source pipeline 19 transports steam or hot water to the generator 12 as a driving heat source. The driving heat source is a high-temperature heat source. Together with the intermediate water low-temperature heat source, this heat source converts energy into hot water in the heat transfer tubes of the absorber 13 and the condenser 14 through an absorption heat pump to heat the return water of the heating network. The heating network return water pipeline 20 is connected to the absorber 13, and the heating network water supply pipeline 21 is connected to the condenser 14. That is, 1 part of high-temperature driving heat source is used to recover about 0.7 parts of waste heat (intermediate water thermal energy) and provide about 1.7 parts of medium-temperature thermal energy for heating network water supply.

[0036] Therefore, running the device with a 300MW unit can extract about 40MW of heat and save about 55t / h of water, which has significant economic benefits.

[0037] In summary, the low-temperature flue gas waste heat recovery device of the present application includes a liquid holding mechanism arranged in the wet flue gas desulfurization tower 1 and an absorption heat pump outside the tower. The liquid holding mechanism serves as a direct contact heat exchanger, and uses circulating intermediate water to cool the flue gas at the outlet of the desulfurization tower from 45 to 55°C to 30 to 40°C, recovering low-grade heat from the flue gas, and obtaining condensed water in the flue gas at the same time, and then using the absorption heat pump to extract the waste heat in the intermediate water to produce medium-grade heat energy for heating the return water of the heat network and other scenarios. The device can realize the recovery of low-temperature flue gas waste heat, and has the functions of water saving and flue gas whitening. The liquid holding mechanism has high heat exchange efficiency, does not occupy additional space, and is flexible to adjust without affecting the normal operation of the desulfurization device, and has good economic and environmental benefits.

[0038] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A low-temperature flue gas waste heat recovery device, characterized in that: The invention comprises a liquid holding mechanism arranged in a wet flue gas desulfurization tower and an absorption heat pump outside the tower, wherein the liquid holding mechanism comprises a liquid collector, an S-shaped gas-liquid mass transfer structure and a liquid distributor arranged in sequence in the upper part of the tower from bottom to top, and the absorption heat pump comprises an evaporator, a generator, an absorber and a condenser; the outlet of the liquid collector is connected to the inlet of a circulation pump through a first circulation pipeline, and a supply pipeline is also connected to the inlet of the circulation pump, and the supply pipeline is used to supply fresh intermediate water to the liquid holding mechanism and the circulation pump; the outlet of the circulation pump is connected to the evaporator through a second circulation pipeline, and the second circulation pipeline is connected to the inlet of the liquid distributor after passing through the evaporator, and a condensate discharge branch pipeline is arranged before entering the liquid distributor; the generator is connected to a driving heat source pipeline, the absorber is connected to a heat network return water pipeline, the condenser is connected to a heat network water supply pipeline, and the driving heat source pipeline is used to transport steam or hot water.

2. The low-temperature flue gas waste heat recovery device according to claim 1, characterized in that: A horizontal flue gas inlet channel is arranged in the middle of one side of the wet desulfurization tower, and the flue gas inlet channel includes a cylindrical channel and a right-angled trapezoidal channel connected in sequence, the small end of the right-angled trapezoidal channel is connected to the cylindrical channel, and the large end is connected to the inner cavity of the wet desulfurization tower.

3. The low-temperature flue gas waste heat recovery device according to claim 1, characterized in that: A flue gas outlet channel is arranged on the top of the wet desulfurization tower. The flue gas outlet channel comprises a vertical channel and a horizontal channel which are connected in sequence in an L shape. A folded plate demister is arranged in the horizontal channel.

4. The low-temperature flue gas waste heat recovery device according to claim 1, characterized in that: The liquid collector includes a main delivery pipeline and multiple branch collection pipelines; the main delivery pipeline is connected to the first circulation pipeline; the multiple branch collection pipelines are installed on the main delivery pipeline at intervals and are connected to the bottom of the S-shaped gas-liquid mass transfer structure, so as to collect the liquid flowing out of the S-shaped gas-liquid mass transfer structure.

5. The low-temperature flue gas waste heat recovery device according to claim 1, characterized in that: The S-shaped gas-liquid mass transfer structure is horizontally arranged and includes a plurality of long strip plates with S-shaped cross-sections. The plurality of long strip plates are horizontally arranged and staggered in a row in sequence, and the S-shaped ends of adjacent long strip plates are staggered and spaced apart, and the intervals formed between adjacent long strip plates constitute an airflow channel.

6. The low-temperature flue gas waste heat recovery device according to claim 1, characterized in that: The liquid distributor includes a reflux pipe and a plurality of nozzles; the reflux pipe is arranged directly above the S-shaped gas-liquid mass transfer structure and is connected to the first circulation pipe; the plurality of nozzles are installed on the reflux pipe at intervals to evenly spray the circulating liquid onto the S-shaped gas-liquid mass transfer structure.

7. The low-temperature flue gas waste heat recovery device according to claim 6, characterized in that: The nozzle is a single-head nozzle or a one-way double-head nozzle.

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