CN111578303A - Purification system and method for recycling flue gas waste heat in stepped mode - Google Patents
Purification system and method for recycling flue gas waste heat in stepped mode Download PDFInfo
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- CN111578303A CN111578303A CN202010463364.9A CN202010463364A CN111578303A CN 111578303 A CN111578303 A CN 111578303A CN 202010463364 A CN202010463364 A CN 202010463364A CN 111578303 A CN111578303 A CN 111578303A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/06—Arrangements of devices for treating smoke or fumes of coolers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
- F22D1/00—Feed-water heaters, i.e. economisers or like preheaters
- F22D1/50—Feed-water heaters, i.e. economisers or like preheaters incorporating thermal de-aeration of feed-water
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/02—Arrangements of devices for treating smoke or fumes of purifiers, e.g. for removing noxious material
- F23J15/04—Arrangements of devices for treating smoke or fumes of purifiers, e.g. for removing noxious material using washing fluids
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28B—STEAM OR VAPOUR CONDENSERS
- F28B9/00—Auxiliary systems, arrangements, or devices
- F28B9/08—Auxiliary systems, arrangements, or devices for collecting and removing condensate
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/30—Technologies for a more efficient combustion or heat usage
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Abstract
The application discloses a purification system and a method for recovering flue gas waste heat in a stepped manner, wherein the purification system comprises a purification tower, a slurry heat taking pump, a purified flue gas heat taking pump, a waste heat recoverer and a deaerator water replenishing pump; a rectification heat-taking layer, a purification spraying layer, a desizing layer, a water-collecting layer and a purified flue gas heat-taking layer are sequentially arranged in the purification tower from bottom to top; the waste heat recoverer comprises a shell, and a current equalizer, a preheater and a reheater which are arranged in the shell along the water flow direction; a heat taking circulation loop is formed among the slurry heat taking pump, the rectification heat taking layer and the reheater; a heat extraction circulation loop is formed among the clean flue gas heat extraction pump, the clean flue gas heat extraction layer and the preheater; and a hot water outlet of the air preheater is connected with a deaerator through a deaerator water replenishing pump. This application sprays the thick liquid and purifies saturated flue gas and carries out the two-stage and get heat, realizes the high-efficient recovery of low-grade waste heat in the wet flue gas desulfurization tower to will take out the two-stage heating that the heat is used for boiler oxygen-eliminating device moisturizing, promote the oxygen-eliminating device and intake the water temperature, reduce the oxygen-eliminating device operation energy consumption.
Description
Technical Field
The application relates to the field of new energy and energy conservation, in particular to a purification system and method for recovering flue gas waste heat in a gradient manner.
Background
The energy consumption of the industrial field of China accounts for about 70 percent of the total energy consumption of China, and the unit energy consumption of main industrial products is higher than the international advanced level by about 30 percent on average. Except for factors such as relatively backward production process, unreasonable industrial structure and the like, the low utilization rate of industrial waste heat is an important reason for high output value and energy consumption of unit industry, the energy utilization rate of China is only about 33%, which is about 10% lower than that of developed countries, and at least 50% of industrial energy consumption is directly discharged or discarded by waste heat in various forms. Among the waste heat which is directly discharged or discarded, the ratio of the waste heat discharged and entering in the form of high-temperature industrial tail gas is the largest, and the ratio of the waste heat to the waste heat exceeds 60 percent of the total amount of the waste heat. The industrial waste heat resources in China are rich and widely exist in the production process of various industrial industries, the waste heat resources account for 17% -67% of the total fuel consumption, the recoverable waste heat accounts for 60% of the discharged waste heat, the waste heat utilization rate is large in promotion space, and the energy-saving potential is huge. The industrial waste heat recycling is considered as a new energy source and becomes an important content of energy conservation and emission reduction work in China in recent years.
At present, the Flue Gas Desulfurization method (FGD for short) applied to domestic large-scale coal-fired power plants mostly adopts a lime/limestone-gypsum wet Desulfurization process, and the optimal working temperature is about 50 ℃. The exhaust gas temperature of the power station boiler is generally designed to be 120-140 ℃, and the exhaust gas temperature lower than 120 ℃ is rarely adopted. After the boiler discharges fume and enters an absorption tower of FGD, the temperature of the fume is reduced to the working temperature in a spraying mode, a large amount of water resources are consumed, the fume emission is increased, and energy in a fume cooling interval is wasted. For the purposes of energy conservation and efficiency improvement, a flue gas heat exchanger is arranged on a flue between an air preheater and an FGD in many power plants, the temperature of flue gas is reduced to 100-80 ℃, and then the flue gas enters an FGD absorption tower to recycle part of the flue gas waste heat. More, install flue gas heat exchanger in electrostatic precipitator (ESP) population, retrieve the flue gas waste heat and compromise and reduce the gas temperature and improve dust collection efficiency. The method has the advantages that the energy-saving and emission-reducing effects are realized, and meanwhile, the risk of low-temperature corrosion on heating surfaces of a flue and a heat exchanger is brought, wherein the acid dew point temperature of the flue gas is the most main influence factor. The temperature difference between the exhaust gas temperature of the boiler without temperature reduction and the working temperature of the FGD absorption tower is 80-60 ℃, and if the exhaust gas temperature is totally reduced by water spraying evaporation, the water consumption is considerable. At present, the outlet smoke temperature of most of the design of the smoke coolers is generally about 90 ℃, and only part of heat in the smoke can be recovered.
The heat in the flue gas with the temperature lower than 90 ℃ after the cooler is recovered in the wet desulphurization tower can effectively avoid the problems of corrosion of the heat exchanger due to acid dew point and large water consumption of the wet desulphurization tower, but has the following problems: 1. the existing wet desulphurization system mainly undertakes the function of flue gas purification, and is difficult to realize low-grade waste heat extraction on the premise of not influencing the flue gas purification efficiency; 2. the gas-liquid two-phase flow in the wet desulphurization tower is strong, the distribution of the washing liquid is extremely uneven and the wearability is strong, and the conventional heat exchanger is difficult to adapt to long-period stable operation; 3. the grade of the heat-taking waste heat in the wet desulphurization tower is low, and the heat-taking waste heat is difficult to recycle. At present, the field of efficiently recovering low-grade waste heat in flue gas in a wet desulphurization tower is still blank.
Disclosure of Invention
The application provides a purification system and a method for recovering flue gas waste heat in a gradient manner, which are used for carrying out two-stage heat extraction on purified spraying slurry and purified saturated flue gas, realizing efficient recovery of low-grade waste heat in the flue gas in a wet desulphurization tower, and using the extracted heat for two-stage heating of water supplement of a boiler deaerator, so that the water inlet temperature of the deaerator is increased, and the operation energy consumption of the deaerator is reduced.
A purification system for recovering flue gas waste heat in a gradient manner comprises a purification tower, a slurry heat taking pump, a purified flue gas heat taking pump, a waste heat recoverer, a deaerator water replenishing pump and a connecting pipeline;
a flue gas inlet is formed in the tower wall of the purification tower, a flue gas outlet is formed in the top of the purification tower, and a rectification heat-taking layer, a purification spraying layer, a de-sizing layer, a water-receiving layer and a purified flue gas heat-taking layer are sequentially arranged in the tower body between the flue gas inlet and the flue gas outlet from bottom to top;
the waste heat recoverer comprises a shell, a current equalizer, a preheater and a reheater, wherein one end of the shell is provided with a water inlet of the waste heat recoverer, the other end of the shell is provided with a water outlet of the waste heat recoverer, the current equalizer, the preheater and the reheater are sequentially arranged in the shell along the water flow direction, and the preheater and the reheater are respectively and independently provided with a water inlet and a water outlet;
an inlet of the slurry heat pump is communicated with a water outlet of the reheater through a pipeline, an outlet of the slurry heat pump is communicated with a water inlet of the rectification heat layer through a pipeline, and a water outlet of the rectification heat layer is communicated with a water inlet of the reheater through a pipeline;
the inlet of the clean flue gas heat pump is communicated with the water outlet of the preheater through a pipeline, the outlet of the clean flue gas heat pump is communicated with the water inlet of the clean flue gas heat collector through a pipeline, and the water outlet of the clean flue gas heat collector is communicated with the water inlet of the preheater through a pipeline;
an inlet of the deaerator water replenishing pump is communicated with a water outlet of the waste heat recoverer through a pipeline, and an outlet of the deaerator water replenishing pump is connected to a water inlet of the deaerator through a pipeline.
Several alternatives are provided below, but not as an additional limitation to the above general solution, but merely as a further addition or preference, each alternative being combinable individually for the above general solution or among several alternatives without technical or logical contradictions.
Optionally, the rectification and heat extraction layer comprises a rectification pore plate and a plurality of slurry heat extraction units; and the slurry heat taking units are arranged above the rectifying pore plate.
Optionally, the aperture of the rectification pore plate is 20mm-40mm, and the aperture ratio is 25% -40%.
Optionally, the slurry heat-extracting unit comprises a water inlet cavity, a water outlet cavity and a plurality of metal pipes connecting the water inlet cavity and the water outlet cavity; the water inlet cavity is provided with a water inlet communicated with the water inlet of the rectification heat-taking layer, and the water outlet cavity is provided with a water outlet communicated with the water outlet of the rectification heat-taking layer.
Optionally, the metal pipe is provided with N layers, wherein N is more than or equal to 2; the layers are distributed at equal intervals, and the metal pipes in the same layer are distributed at equal intervals; the metal pipes between the adjacent layers are distributed in a staggered way; the pipe diameter of the metal pipe is 15mm-40 mm; the gap distance between two adjacent metal pipes in the same layer is 50mm-100mm, and the gap distance between layers is 60mm-150 mm; the thickness of the tube wall of the metal tube is 0.3mm-1.5mm, and the distance between the lowest point of the bottom layer metal tube and the top surface of the rectification pore plate is 60mm-120 mm.
Optionally, the purified flue gas heat extraction layer comprises a plurality of layers of metal finned tubes; the water inlet of each metal finned tube is communicated with the water inlet of the purified flue gas heat taking layer, and the water outlet of each metal finned tube is communicated with the water outlet of the purified flue gas heat taking layer; the tube diameter of the base tube of the metal finned tube is 15mm-35mm, the height of the metal fin is 0.5-1.0 time of the diameter of the base tube, and the gap between the metal fins is 0.5mm-4.0 mm.
Optionally, the water inlets of the waste heat recoverers are uniformly distributed on the water inlet end face of the shell of the waste heat recoverer, and the water flow speed in the waste heat recoverer is 0.2-0.8 m/s.
Optionally, relative to the water flow direction in the housing, the water inlet of the preheater is located downstream of the water outlet, and the water inlet of the reheater is located downstream of the water outlet.
This application still provides a clean system of flue gas waste heat is retrieved to step, preferably adopts this application system ancient playing city, includes:
(1) high-temperature flue gas carrying pollutants enters the purification tower from a flue gas inlet and flows upwards, and high-temperature airflow passes through the rectification heat-taking layer at high speed in the form of uniform upward airflow after being rectified by the rectification pore plate; the washing slurry is atomized from the purification spraying layer into slurry liquid drops which move downwards to enter the rectification heat extraction layer, and the high-speed airflow and the spraying liquid drops form a gas-liquid turbulent flow zone with a certain thickness in a tray area of the rectification heat extraction layer;
(2) the slurry heat taking pump sends low-temperature hot water into a slurry heat taking unit of the rectification heat taking layer, mass transfer and heat exchange are carried out on high-temperature flue gas and spraying slurry in a gas-liquid turbulent flow region through a metal pipe wall of the slurry heat taking unit, pollutants in part of the flue gas are removed, and the hot high-temperature hot water which is heated is sent to a reheater water inlet in the waste heat recoverer through a pipeline;
(3) the flue gas continuously flows upwards to enter a purification spraying layer to remove pollutants in the flue gas, water in part of the purification washing slurry is evaporated into steam in the gas-liquid turbulent flow area and the spraying area in the heat exchange process, and the flue gas passing through the purification spraying layer reaches a saturated state; removing washing slurry liquid drops in the saturated flue gas through a desizing layer, and then passing through a water receiving layer to enter a clean flue gas heat taking layer;
(4) the purified flue gas heat taking pump sends low-temperature hot water into the purified flue gas heat taking layer, indirect heat exchange is carried out on saturated purified flue gas through the metal finned tube, most of water vapor in the purified flue gas is condensed through heat exchange to form liquid condensate water which falls into the water receiving layer under the action of gravity and is discharged out of the tower through the water receiving layer drainage pipeline for recycling, and the hot water which finishes the heat taking of the purified flue gas is sent to a water inlet of a preheater in the waste heat recovery device through a water outlet of the purified flue gas heat taking layer through a pipeline;
(5) the water of the boiler deaerator enters the waste heat recoverer from a water inlet of the waste heat recoverer, flows through the preheater and the reheater in sequence after being rectified uniformly by the flow equalizer, and is sent to the deaerator by a deaerator water supplementing pump for deaerating after being subjected to two-stage heat exchange and temperature rise with high-temperature water taking in the preheater and the reheater, so that the operation energy consumption of the deaerator is reduced, and the waste heat of tail gas is recycled; the low-temperature water-taking in the preheater for completing the water-supplementing preheating of the deaerator is sent to the water inlet of the clean flue gas heat-taking device by the clean flue gas heat-taking pump for circularly taking heat; and the low-temperature hot water in the reheater for supplementing water and reheating the deaerator is conveyed to a water inlet of the rectifying heat-taking layer by the slurry heat-taking pump for circularly taking heat.
Compared with the prior art, the method has at least one of the following advantages:
(1) the application provides a solution for recovering flue gas waste heat in a step-by-step mode in a flue gas purification system, hot water is adopted to carry out two-stage heat extraction on purified spray slurry and purified saturated flue gas respectively, the extracted heat is used for two-stage heating of water supplement of a boiler deaerator, the water inlet temperature of the deaerator is increased, and the operation energy consumption of the deaerator is reduced;
(2) the application provides a solution for efficiently recovering flue gas waste heat in a flue gas purification system, wherein rectification heat-taking layers are arranged above inlet flue gas and below a purification spraying layer, a slurry heat-taking unit is arranged in a gas-liquid turbulence layer, and the rapid update of a liquid film on the outer wall surface of a heat-taking metal pipe is realized by utilizing the strong disturbance of gas-liquid on the turbulence layer on a rectification pore plate, so that the heat exchange rate between the heat-taking water and high-temperature flue gas and the spraying slurry is improved, and the efficient recovery of the waste heat in the high-temperature flue gas is realized;
(3) the application provides a solution for reducing the running water consumption of a flue gas purification system, wherein flue gas and spray slurry entering a rectification heat extraction layer are indirectly heated, so that the reaction temperature and the moisture evaporation capacity of gas and liquid in the flue gas purification process are reduced; the saturated clean flue gas after being purified and washed is subjected to heat extraction and condensation, and the condensed water is led out and recycled by the water receiving disc, so that the water balance of the wet flue gas washing system is ensured, and the running water consumption of the wet flue gas purification system is greatly reduced.
Drawings
FIG. 1 is a schematic diagram of the purification system of the present application;
FIG. 2 is a schematic structural diagram of the rectifying and heat extracting layer in FIG. 1;
fig. 3 is a partially enlarged view of a portion a in fig. 2.
Fig. 4 is a schematic structural diagram of a single slurry heat removal unit in fig. 2.
The reference numerals shown in the figures are as follows:
1-purification tower 2-rectification heat-taking layer 3-purification spraying layer
4-desizing layer 5-water receiving layer 6-purified flue gas heat collecting layer
7-flue gas outlet 8-flue gas inlet 9-waste heat recoverer
91-shell 92-rectifier 93-preheater
94-reheater
10-circulating pump 11-slurry taking heat pump 12-deaerator water replenishing pump
13-clean flue gas heat pump 14-clean flue gas hot water taking buffer tank 15-slurry hot water taking buffer tank
21-rectifying pore plate 22-slurry heat-taking unit
221-metal pipe 222-water inlet cavity 223-water outlet cavity
224-heat extraction unit water inlet 225-heat extraction unit water outlet
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
For a better description and illustration of embodiments of the application, reference may be made to one or more of the drawings, but additional details or examples used in describing the drawings should not be construed as limiting the scope of any of the inventive concepts of the present application, the presently described embodiments, or the preferred versions.
It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. When a component is referred to as being "disposed on" another component, it can be directly on the other component or intervening components may also be present.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
As shown in fig. 1, a purification system for recovering flue gas waste heat in a stepped manner comprises a purification tower 1, a slurry heat pump 11, a purified flue gas heat pump 13, a waste heat recoverer 9, a deaerator water replenishing pump 12, a connecting pipeline and a control valve arranged on the corresponding pipeline.
The purifying tower 1 is transformed by adopting a wet spraying tower, a flue gas inlet 8 is arranged on the tower wall of the purifying tower, a flue gas outlet 7 is arranged at the top of the purifying tower, and a rectifying and heat-taking layer 2, a purifying and spraying layer 3, a desizing layer 4, a water-taking layer 5 and a clean flue gas heat-taking layer 6 are sequentially arranged in the tower body between the flue gas inlet 8 and the flue gas outlet 9 from bottom to top.
The rectification and heat extraction layer 2 and the clean flue gas heat extraction layer 6 are both connected with a waste heat recoverer 9, and the waste heat recoverer 9 comprises a shell, a current equalizer 92, a preheater 93 and a reheater 94. A water inlet of a waste heat recoverer is arranged on one end face of the shell 91, a water outlet of the waste heat recoverer is arranged on the other end face opposite to the water inlet, low-temperature heat taking liquid is sent into the shell from the water inlet of the waste heat recoverer and is exchanged with heat taken out from the purifying tower by the rectification heat taking layer 2 and the clean flue gas heat taking layer 6 and then is discharged from the water outlet of the waste heat recoverer, a flow equalizer, a preheater and a reheater are sequentially arranged in the shell along the water flow direction, the preheater and the reheater are respectively and independently provided with a water inlet and a water outlet, namely the preheater is provided with a water inlet and. .
The outlet of the clean flue gas heat-taking pump 13 is communicated with the water inlet of the clean flue gas heat-taking device 6 through a pipeline, the water outlet of the clean flue gas heat-taking device 6 is communicated with the water inlet of the preheater 93 through a pipeline, the water outlet of the preheater 93 is communicated with the clean flue gas heat-taking buffer tank 15, the water outlet of the clean flue gas heat-taking buffer tank 15 is communicated with the inlet of the clean flue gas heat-taking pump 13 through a pipeline, and a clean flue gas heat-taking liquid circulation loop is formed. The clean flue gas heat extractor 6 recovers the low-grade waste heat of the clean flue gas, and the heat extracting liquid heated by the clean flue gas heat extractor 6 is sent into the preheater to be used as a heating medium of the preheater to preheat the low-temperature water passing through the preheater.
An outlet of the slurry heat taking pump 11 is communicated with a water inlet of the rectification heat taking layer 2 through a pipeline, a water outlet of the rectification heat taking layer 2 is communicated with a water inlet of a reheater 94 through a pipeline, a water outlet of the reheater 94 is communicated with the slurry heat taking buffer tank 14 through a pipeline, and a water outlet of the slurry heat taking buffer tank 14 is communicated with an inlet of the slurry heat taking pump 11 through a pipeline, so that a slurry heat taking liquid circulation loop is formed. The heat-taking liquid after heat exchange and temperature rise of the rectification heat-taking layer 2 and the slurry is used as a heating medium of the reheater to reheat the low-temperature water flowing through the reheater.
An inlet of a deaerator water replenishing pump 12 is communicated with a water outlet of the waste heat recoverer through a pipeline, an outlet of the deaerator water replenishing pump is connected to a water inlet of the deaerator through a pipeline, and the deaerator water replenishing pump sends high-temperature water heated by a preheater 93 and a reheater 94 in sequence into the deaerator.
This application adopts to get hot water and sprays the thick liquid and purify saturated flue gas respectively and carry out the two-stage and get heat to will take out the heat and be used for the two-stage heating of boiler oxygen-eliminating device moisturizing, promote the oxygen-eliminating device temperature of intaking, reduce the oxygen-eliminating device operation energy consumption. The effective recovery of low-grade heat of the flue gas is realized.
The rectification heat-taking layer 2 is horizontally arranged above a flue gas inlet 8 of the purification tower 1 and below the purification spraying layer 3 and is used for rectifying flue gas and recovering waste heat of washing liquid. As an embodiment of the rectifying and heat extracting layer 2, the structure of which is shown in fig. 2 includes a rectifying orifice plate 21 and a plurality of slurry heat extracting units 22, wherein the plurality of slurry heat extracting units 22 are installed above the rectifying orifice plate and spaced apart from the rectifying orifice plate 21 by a predetermined distance.
High-temperature flue gas carrying pollutants enters the purification tower from the flue gas inlet to flow upwards, and the high-temperature airflow passes through the rectification heat extraction layer at high speed in a uniform and upward airflow manner after being rectified by the rectification pore plate. The washing slurry is atomized into slurry liquid drops by the purification spraying layer and moves downwards to enter the rectification heat-extraction layer. The high-speed airflow and the spray liquid drops form a gas-liquid turbulent flow zone with a certain thickness in the slurry heat taking unit tray area of the rectification heat taking layer; and the slurry heat taking pump sends low-temperature hot water into a slurry heat taking unit of the rectification heat taking layer, mass transfer and heat exchange are carried out on high-temperature flue gas and spraying slurry in a gas-liquid turbulent flow region through the slurry heat taking unit, pollutants in part of the flue gas are removed, and the hot high-temperature hot water which is taken out is sent to a reheater water inlet in the waste heat recoverer through a pipeline.
As an embodiment of the rectification orifice plate 21, the rectification orifice plate has an aperture diameter of 20mm to 40mm and an aperture ratio of 25% to 40%, and a partial enlarged view thereof is shown in fig. 3.
The slurry heat-extracting units are closely arranged and assembled on the horizontal section of the purification tower, and as an implementation mode of the slurry heat-extracting unit 22, a single slurry heat-extracting unit is rectangular, the structure of the slurry heat-extracting unit is shown in fig. 4, the slurry heat-extracting unit 22 comprises a plurality of metal pipes 221, a water inlet cavity 222 and a water outlet cavity 223, the metal pipes are arranged in parallel, and two ends of each metal pipe are respectively connected with the water inlet cavity and the water outlet cavity. In this embodiment, the water inlet cavity and the water outlet cavity are both rectangular parallelepiped cavities, the water inlet cavity is provided with a heat extraction unit water inlet 224, the water outlet cavity is provided with a heat extraction unit water outlet 225, all the heat extraction unit water inlets are connected in parallel and then connected with the water inlet of the rectification heat extraction layer, and then connected with the water outlet of the slurry heat extraction pump 11, all the heat extraction unit water outlets are connected in parallel and then connected with the water outlet of the rectification heat extraction layer, and then connected with the water inlet of the reheater 94.
The inside of the metal pipe is provided with a hot liquid taking circulation channel, and the metal pipe is provided with N layers as an arrangement mode of the metal pipe, wherein N is more than or equal to 2; the metal pipes in the same layer are distributed at equal intervals.
As a distribution mode of metal pipes of adjacent layers, the metal pipes between adjacent layers are distributed in a staggered manner, and it can also be understood that each metal pipe is positioned right below two adjacent metal pipes of an upper layer and right above two adjacent metal pipes of a lower layer.
As a specific embodiment of the setting size of the metal pipe, the pipe diameter of the metal pipe is 15mm-40 mm; the gap distance between two adjacent metal pipes in the same layer is 50mm-100mm, and the gap distance between layers is 60mm-150 mm; the thickness of the tube wall of the metal tube is 0.3mm-1.5mm, and the distance between the lowest point of the bottom layer metal tube and the top surface of the rectification pore plate is 60mm-120 mm.
The slurry heat-taking unit is horizontally arranged on the horizontal section of the purification tower through a metal pipe. The rectification heat-taking layer is arranged above the inlet flue gas and below the purification spraying layer, the slurry heat-taking unit is arranged in the gas-liquid turbulence layer, the rapid update of the liquid film on the outer wall surface of the heat-taking metal pipe is realized by the strong disturbance of the gas-liquid on the turbulence layer on the rectification pore plate, the heat exchange rate between the heat-taking water and the high-temperature flue gas and the spraying slurry is improved, and the efficient recovery of the waste heat in the high-temperature flue gas is realized.
And a washing liquid circulating pool is arranged at the bottom in the purification tower body, and the washing liquid circulating pool is communicated with the purification spraying layer through a circulating pump 10. The circulating pump and the purification spraying layer both adopt conventional equipment of a wet spraying tower.
The desizing layer 4 is located the top that purifies spray layer 3 for the washing thick liquid drop in the desorption saturation flue gas, as an embodiment of desizing layer, the desizing layer includes a plurality of parallels and slope and sets up the defogging baffle on the purifying column horizontal cross-section, and equidistant distribution of defogging baffle, the contained angle is 30 ~ 60 between slope baffle and the tower body horizontal cross-section. A flue gas channel is arranged between the adjacent demisting baffles.
The clean flue gas heat-taking layer 6 recovers the waste heat of the clean flue gas and sends the recovered waste heat to the preheater to be used as a heating medium of the preheater. As an embodiment of the purified flue gas heat extraction layer, the purified flue gas heat extraction layer 6 comprises a plurality of layers of metal finned tubes arranged in parallel; the water inlet of each metal finned tube is communicated with the water inlet of the purified flue gas heat taking layer, and the water outlet of each metal finned tube is communicated with the water outlet of the purified flue gas heat taking layer.
As a specific embodiment of the metal finned tube, the tube diameter of a base tube of the metal finned tube is 15mm-35mm, the height of the metal fin is 0.5-1.0 time of the diameter of the base tube, and the gap between the metal fins is 0.5mm-4.0 mm.
The water receiving layer 5 is positioned above the desizing layer and below the clean flue gas heat-taking layer 6, and the water receiving layer collects condensed water from the clean flue gas heat-taking layer and discharges the condensed water to the outside of the tower body for recycling, so that the water balance of the wet flue gas washing system is ensured, and the running water consumption of the wet flue gas purification system is greatly reduced. The structure of the water receiving layer is conventional equipment in the spray tower, and the requirement that the flue gas can pass through the spray tower from bottom to top without the slurry falling is met.
As an embodiment of the preheater and the reheater, both the preheater and the reheater employ a coil pipe. For the water flow direction in the casing, the water inlet of preheater is located delivery port low reaches, and the water inlet of reheater is located delivery port low reaches. The water inlets of the waste heat recoverers are uniformly distributed on the water inlet end surface of the shell of the waste heat recoverer, and the water flow speed in the waste heat recoverer is controlled to be 0.2-0.8 m/s.
The method for recycling the flue gas waste heat in a gradient manner by using the purification system comprises the following steps:
(1) high-temperature flue gas carrying pollutants enters the purification tower from a flue gas inlet and flows upwards, and high-temperature airflow passes through the rectification heat-taking layer at high speed in the form of uniform upward airflow after being rectified by the rectification pore plate; the washing slurry is atomized from the purification spraying layer into slurry liquid drops which move downwards to enter the rectification heat extraction layer, and the high-speed airflow and the spraying liquid drops form a gas-liquid turbulent flow zone with a certain thickness in a tray area of the rectification heat extraction layer;
(2) the slurry heat taking pump sends low-temperature hot water into a slurry heat taking unit of the rectification heat taking layer, mass transfer and heat exchange are carried out on high-temperature flue gas and spraying slurry in a gas-liquid turbulent flow region through a metal pipe wall of the slurry heat taking unit, pollutants in part of the flue gas are removed, and the hot high-temperature hot water which is heated is sent to a reheater water inlet in the waste heat recoverer through a pipeline;
(3) the flue gas continuously flows upwards to enter a purification spraying layer to remove pollutants in the flue gas, water in part of the purification washing slurry is evaporated into steam in the gas-liquid turbulent flow area and the spraying area in the heat exchange process, and the flue gas passing through the purification spraying layer reaches a saturated state; removing washing slurry liquid drops in the saturated flue gas through a desizing layer, and then passing through a water receiving layer to enter a clean flue gas heat taking layer;
(4) the purified flue gas heat taking pump sends low-temperature hot water into the purified flue gas heat taking layer, indirect heat exchange is carried out on saturated purified flue gas through the metal finned tube, most of water vapor in the purified flue gas is condensed through heat exchange to form liquid condensate water which falls into the water receiving layer under the action of gravity and is discharged out of the tower through the water receiving layer drainage pipeline for recycling, and the hot water which finishes the heat taking of the purified flue gas is sent to a water inlet of a preheater in the waste heat recovery device through a water outlet of the purified flue gas heat taking layer through a pipeline;
(5) the water of the boiler deaerator enters the waste heat recoverer from a water inlet of the waste heat recoverer, flows through the preheater and the reheater in sequence after being rectified uniformly by the flow equalizer, and is sent to the deaerator by a deaerator water supplementing pump for deaerating after being subjected to two-stage heat exchange and temperature rise with high-temperature water taking in the preheater and the reheater, so that the operation energy consumption of the deaerator is reduced, and the waste heat of tail gas is recycled; the low-temperature water-taking in the preheater for completing the water-supplementing preheating of the deaerator is sent to the water inlet of the clean flue gas heat-taking device by the clean flue gas heat-taking pump for circularly taking heat; and the low-temperature hot water in the reheater for supplementing water and reheating the deaerator is conveyed to a water inlet of the rectifying heat-taking layer by the slurry heat-taking pump for circularly taking heat.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (9)
1. A purification system for recovering flue gas waste heat in a gradient manner is characterized by comprising a purification tower, a slurry taking heat pump, a purified flue gas taking heat pump, a waste heat recoverer, a deaerator water replenishing pump and a connecting pipeline;
a flue gas inlet is formed in the tower wall of the purification tower, a flue gas outlet is formed in the top of the purification tower, and a rectification heat-taking layer, a purification spraying layer, a de-sizing layer, a water-receiving layer and a purified flue gas heat-taking layer are sequentially arranged in the tower body between the flue gas inlet and the flue gas outlet from bottom to top;
the waste heat recoverer comprises a shell, a current equalizer, a preheater and a reheater, wherein one end of the shell is provided with a water inlet of the waste heat recoverer, the other end of the shell is provided with a water outlet of the waste heat recoverer, the current equalizer, the preheater and the reheater are sequentially arranged in the shell along the water flow direction, and the preheater and the reheater are respectively and independently provided with a water inlet and a water outlet;
an inlet of the slurry heat pump is communicated with a water outlet of the reheater through a pipeline, an outlet of the slurry heat pump is communicated with a water inlet of the rectification heat layer through a pipeline, and a water outlet of the rectification heat layer is communicated with a water inlet of the reheater through a pipeline;
the inlet of the clean flue gas heat pump is communicated with the water outlet of the preheater through a pipeline, the outlet of the clean flue gas heat pump is communicated with the water inlet of the clean flue gas heat collector through a pipeline, and the water outlet of the clean flue gas heat collector is communicated with the water inlet of the preheater through a pipeline;
an inlet of the deaerator water replenishing pump is communicated with a water outlet of the waste heat recoverer through a pipeline, and an outlet of the deaerator water replenishing pump is connected to a water inlet of the deaerator through a pipeline.
2. The purification system for the cascade recovery of the waste heat of the flue gas as claimed in claim 1, wherein the rectifying and heat extracting layer comprises a rectifying orifice plate and a plurality of slurry heat extracting units; and the slurry heat taking units are arranged above the rectifying pore plate.
3. The purification system for the cascade recovery of the waste heat of the flue gas as recited in claim 2, wherein the aperture of the rectification pore plate is 20mm-40mm, and the aperture ratio is 25% -40%.
4. The purification system for recycling the waste heat of the flue gas in a stepped manner according to claim 2, wherein the slurry heat taking unit comprises a water inlet cavity, a water outlet cavity and a plurality of metal pipes for connecting the water inlet cavity and the water outlet cavity; the water inlet cavity is provided with a water inlet communicated with the water inlet of the rectification heat-taking layer, and the water outlet cavity is provided with a water outlet communicated with the water outlet of the rectification heat-taking layer.
5. The purification system for the cascade recovery of the waste heat of the flue gas as recited in claim 4, wherein the metal pipe is provided with N layers, wherein N is more than or equal to 2; the layers are distributed at equal intervals, and the metal pipes in the same layer are distributed at equal intervals; the metal pipes between the adjacent layers are distributed in a staggered way; the pipe diameter of the metal pipe is 15mm-40 mm; the gap distance between two adjacent metal pipes in the same layer is 50mm-100mm, and the gap distance between layers is 60mm-150 mm; the thickness of the tube wall of the metal tube is 0.3mm-1.5mm, and the distance between the lowest point of the bottom layer metal tube and the top surface of the rectification pore plate is 60mm-120 mm.
6. The purification system for the cascade recovery of the waste heat of the flue gas as recited in claim 1, wherein the purified flue gas heat extraction layer comprises a plurality of layers of metal finned tubes; the water inlet of each metal finned tube is communicated with the water inlet of the purified flue gas heat taking layer, and the water outlet of each metal finned tube is communicated with the water outlet of the purified flue gas heat taking layer; the tube diameter of the base tube of the metal finned tube is 15mm-35mm, the height of the metal fin is 0.5-1.0 time of the diameter of the base tube, and the gap between the metal fins is 0.5mm-4.0 mm.
7. The purification system for recycling flue gas waste heat in a stepped manner according to claim 1, wherein a plurality of waste heat recoverer water inlets are uniformly distributed on a water inlet end face of a shell of a waste heat recoverer, and the water flow speed in the waste heat recoverer is 0.2m/s-0.8 m/s.
8. The cascade flue gas waste heat recovery purification system of claim 1, wherein the water inlet of the preheater is located downstream of the water outlet and the water inlet of the reheater is located downstream of the water outlet with respect to the direction of water flow in the housing.
9. A purification method for recovering flue gas waste heat in a gradient manner is characterized by comprising the following steps:
(1) high-temperature flue gas carrying pollutants enters the purification tower from a flue gas inlet and flows upwards, and high-temperature airflow passes through the rectification heat-taking layer at high speed in the form of uniform upward airflow after being rectified by the rectification pore plate; the washing slurry is atomized from the purification spraying layer into slurry liquid drops which move downwards to enter the rectification heat extraction layer, and the high-speed airflow and the spraying liquid drops form a gas-liquid turbulent flow zone with a certain thickness in a tray area of the rectification heat extraction layer;
(2) the slurry heat taking pump sends low-temperature hot water into a slurry heat taking unit of the rectification heat taking layer, mass transfer and heat exchange are carried out on high-temperature flue gas and spraying slurry in a gas-liquid turbulent flow region through a metal pipe wall of the slurry heat taking unit, pollutants in part of the flue gas are removed, and the hot high-temperature hot water which is taken out is sent to a water inlet of a reheater in a waste heat recoverer through a pipeline;
(3) the flue gas continuously flows upwards to enter a purification spraying layer to remove pollutants in the flue gas, water in part of the purification washing slurry is evaporated into steam in the gas-liquid turbulent flow area and the spraying area in the heat exchange process, and the flue gas passing through the purification spraying layer reaches a saturated state; removing washing slurry liquid drops in the saturated flue gas through a desizing layer, and then passing through a water receiving layer to enter a clean flue gas heat taking layer;
(4) the purified flue gas heat taking pump sends low-temperature hot water into the purified flue gas heat taking layer, indirect heat exchange is carried out on saturated purified flue gas through the metal finned tube, most of water vapor in the purified flue gas is condensed through heat exchange to form liquid condensate water which falls into the water collecting layer under the action of gravity and is discharged out of the tower for recycling through a water discharging pipeline of the water collecting layer, and the hot water which finishes the purified flue gas heat taking is sent to a water inlet of a preheater in the waste heat recovery device through a water outlet of the purified flue gas heat taking layer through a pipeline;
(5) the water of the boiler deaerator enters the waste heat recoverer from a water inlet of the waste heat recoverer, flows through the preheater and the reheater in sequence after being rectified uniformly by the flow equalizer, and is sent to the deaerator by a deaerator water supplementing pump for deaerating after being subjected to two-stage heat exchange and temperature rise with high-temperature water taking in the preheater and the reheater, so that the operation energy consumption of the deaerator is reduced, and the waste heat of tail gas is recycled; the low-temperature water-taking in the preheater for completing the water-supplementing preheating of the deaerator is circularly heated by the purified flue gas heat-taking pump to the water inlet of the purified flue gas heat-taking device; and the low-temperature hot water in the reheater for supplementing water and reheating the deaerator is conveyed to a water inlet of the rectification and heating layer by the slurry heating pump for circulating heating.
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| CN202010463364.9A CN111578303A (en) | 2020-05-27 | 2020-05-27 | Purification system and method for recycling flue gas waste heat in stepped mode |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112691534A (en) * | 2020-12-11 | 2021-04-23 | 新疆天富能源股份有限公司 | Energy-saving treatment system and method for recovering waste heat of wet desulphurization device |
| CN113101778A (en) * | 2021-04-14 | 2021-07-13 | 浙江理工大学 | Electrolytic aluminum tail gas pollutant cooperative purification system and method |
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2020
- 2020-05-27 CN CN202010463364.9A patent/CN111578303A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112691534A (en) * | 2020-12-11 | 2021-04-23 | 新疆天富能源股份有限公司 | Energy-saving treatment system and method for recovering waste heat of wet desulphurization device |
| CN113101778A (en) * | 2021-04-14 | 2021-07-13 | 浙江理工大学 | Electrolytic aluminum tail gas pollutant cooperative purification system and method |
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