CN110174020B - Flue gas carbon-based loaded ionic liquid flue gas desulfurization method - Google Patents

Flue gas carbon-based loaded ionic liquid flue gas desulfurization method Download PDF

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CN110174020B
CN110174020B CN201910449182.3A CN201910449182A CN110174020B CN 110174020 B CN110174020 B CN 110174020B CN 201910449182 A CN201910449182 A CN 201910449182A CN 110174020 B CN110174020 B CN 110174020B
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absorption
heat exchanger
flue gas
gas
ionic liquid
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CN110174020A (en
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崔琳
刘立飞
董勇
徐夕仁
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Shandong University
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Shandong University
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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
    • F23J15/006—Layout of treatment plant
    • 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
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D21/00—Heat-exchange apparatus not covered by any of the groups F28D1/00 - F28D20/00
    • F28D21/0001—Recuperative heat exchangers
    • F28D21/0003—Recuperative heat exchangers the heat being recuperated from exhaust gases
    • F28D21/001—Recuperative heat exchangers the heat being recuperated from exhaust gases for thermal power plants or industrial processes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J2215/00—Preventing emissions
    • F23J2215/20—Sulfur; Compounds thereof
    • 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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  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Treating Waste Gases (AREA)

Abstract

The invention provides an asymmetrically arranged heat exchanger, which comprises a header, wherein a left coil and a right coil are distributed on the left side and the right side of the header. The heat exchanger designed by the invention can perform heat exchange enhancement and deposition removal on different heights, and enhance the heat exchange and deposition removal effects.

Description

Flue gas carbon-based loaded ionic liquid flue gas desulfurization method
Technical Field
The invention belongs to the technical field of heat exchange and flue gas desulfurization, and particularly relates to an asymmetrically arranged heat exchanger and a flue gas waste heat utilization system thereof.
Background
China is the largest coal producing country and consuming country in the world, and a coal-fired power plant consumes a large amount of coal to provide steam and electric power and simultaneously discharges a large amount of waste heat. The flue gas waste heat recovery generally adopts a shell-and-tube heat exchanger, so the enhanced heat exchange technology of the heat exchanger has important significance for energy conservation and consumption reduction. The passive heat transfer enhancement technology achieves the purpose of heat transfer enhancement without external high-quality energy input, and becomes an important research direction at present.
The mode of passively strengthening heat exchange is to strictly prevent the fluid vibration induction in the heat exchanger from being changed into effective utilization of vibration, so that the convective heat transfer coefficient of the transmission element at low flow speed is greatly improved, dirt on the surface of the heat transfer element is restrained by vibration, the thermal resistance of the dirt is reduced, and the composite strengthened heat transfer can be realized.
In addition, coal-fired power plants consume large amounts of coal and also emit large amounts of SO2And the like. Flue gas desulfurization for reducing SO in flue gas2One of the effective technologies of discharge comprises wet, dry and semi-dry desulphurization technologies, wherein wet desulphurization, especially limestone/gypsum wet desulphurization, is most widely applied, but the method has the problems of large water consumption, difficulty in treating waste water, large investment and the like, and most of desulphurization by-product gypsum is idle and stacked, thereby occupying land resources and causing secondary pollution; while dry and semi-dry desulfurization processBut the problems of high Ca/S ratio, low desulfurization efficiency, high regeneration and replacement cost of the desulfurizer and the like exist, so that the search of an alternative environment-friendly desulfurizer becomes an important problem to be solved urgently.
The ionic liquid is organic molten salt which is composed of anions and cations and is in a liquid state at room temperature or near room temperature, has extremely low volatility, wide electrochemical window and good selective dissolution or absorption/adhesion performance, and researches in recent years show that the ionic liquid is used for SO2Has good selective dissolving, absorbing/adsorbing effects, and the ionic liquid desulfurization technology has the advantages of economic and high-efficiency removal of SO without secondary pollution2The ionic liquid desulfurizing agent is changed into a usable chemical raw material, the absorbent can be recycled after regeneration, however, due to the fact that the ionic liquid is high in inherent viscosity and large in gas mass transfer resistance, the ionic liquid desulfurizing agent is unfavorable to use in gas-liquid separation, carrying loss of the ionic liquid is caused, meanwhile, for desorption and regeneration of the ionic liquid desulfurizing agent, an extra heat source is needed to provide energy, and the desulfurizing operation cost is increased to a certain extent.
In the utilization of the waste heat of the flue gas, the structure of the heat exchanger is also an important design, and particularly, the heat exchanger for preventing the ash collection is very important.
Aiming at the problems, the invention provides a novel flue gas waste heat utilization heat exchanger and a waste heat utilization method thereof, which can fully utilize heat sources, reduce energy consumption and realize high-efficiency resource desulfurization.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a heat exchanger utilizing flue gas waste heat to strengthen heat exchange and remove deposited dust.
In order to achieve the purpose, the invention adopts the following technical scheme:
the heat exchanger is characterized in that the left coil pipe and the right coil pipe are arranged at intervals, a right coil pipe is arranged between every two adjacent left coil pipes, and a left coil pipe is arranged between every two adjacent right coil pipes.
Preferably, a left pipe and a right pipe are included as headers of the left coil and the right coil.
A flue gas waste heat utilization system comprises an air preheater, a first heat exchanger, a second heat exchanger, a first absorption/desorption tower, a second absorption/desorption tower, a gas-solid separator, a fan, a gas storage and acid production device, a compressor and a chimney, wherein the air preheater is connected with the heat exchanger, flue gas cooled by the air preheater enters the first heat exchanger to perform secondary heat exchange with air in the heat exchanger, and the heated air is returned to the air preheater to be reheated for secondary utilization; the first heat exchanger is also used as a heater for starting nitrogen gas of the analysis system, and the heated nitrogen gas is connected with the absorption/analysis tower through a pipeline; the flue gas side of the second heat exchanger is connected with an absorption/desorption tower, the upper part of the absorption/desorption tower is connected with a chimney through a pipeline, the bottom of the absorption/desorption tower is connected with a gas-solid separator through a pipeline, a fan and a compressor are sequentially connected behind the gas-solid separator, and the compressor is respectively connected with a gas and acid storage device and the second heat exchanger through pipelines.
Preferably, the air is subjected to heat exchange with a heat source from the compressor in the second heat exchanger, and then enters the air preheater to be subjected to heat exchange continuously and then is used.
Preferably, a dust remover is arranged on the flue gas pipeline between the air preheater and the heat exchanger.
Preferably, the absorption/desorption tower is two devices in parallel structure, and the valves are arranged on the inlet flue gas pipeline and the outlet flue gas pipeline for switching.
Preferably, the activated carbon loaded with the ionic liquid is reacted with SO in a first absorption/desorption tower2Carrying out absorption reaction, and switching the flue gas into a second absorption/desorption tower for adsorption when the absorption is saturated; the first absorption/desorption column starts desorption, in such a way that both reaction columns are recycled.
Preferably, the flue gas is firstly subjected to preliminary cooling through an air preheater and then passes through a dust remover, enters a heat exchanger to exchange heat with air, so that the temperature of the flue gas is reduced to below 50 ℃, the flue gas enters an absorption tower to be adsorbed, and the purified flue gas is discharged from a chimney;
preferably, the system is equipped with start-up nitrogen, which is only used for the stripper start-up process. Starting nitrogen to exchange heat with flue gas through a heat exchanger, feeding the heated nitrogen serving as desorption gas into a reaction tower which is saturated by adsorption for desorption, separating gas from solid particles by using the desorbed mixed gas through a gas-solid separator, pumping the desorbed mixed gas into a compressor by using a booster fan, and pumping N into the compressor2With SO2And (5) separating. Separated SO2Enters a gas storage tank/acid making system to realize SO2Resource utilization is carried out; n is a radical of2The heat which is released by the compression of the compressor is carried, the temperature is reduced to about 100 ℃ through the second heat exchanger, and the heat enters the desorption tower, and the heat is recycled.
The heat exchange medium in the second heat exchanger is air, and the air directly enters the air preheater after passing through the second heat exchanger to exchange heat with the desorption gas, so that the requirement of hot air in the boiler is met.
The invention has the advantages and effects that:
1) the heat exchanger designed by the invention can perform heat exchange enhancement and deposition removal on different heights, and enhance the heat exchange and deposition removal effects.
2) The flue gas waste heat utilization system designed by the invention can fully utilize the flue gas waste heat and can also realize the effect of reducing emission.
3) The waste heat recovery auxiliary regeneration system after desulfurization fully utilizes the heat of the tail flue gas, SO that the regeneration of the desulfurizer fully depends on the heat flow in the system, the problem of difficult utilization of the tail low-temperature flue gas is solved, and SO is used2Collected as a gas or sulfuric acid.
4) The ionic liquid is loaded on the surface of the porous activated carbon, so that the porous activated carbon has the characteristics of solid phase carriers such as large surface area, high porosity and good mechanical strength, has the characteristics of ionic liquid phase which is difficult to volatilize and has good gas solubility, and the loaded ionic liquid particles have faster gas absorption rate.
5) The invention takes the active carbon as the adsorption carrier, has light weight and strong stability, and is economical and practical.
6) The invention provides a vibrating symmetrical heat exchange tube bundle with a novel structure, which increases the vibration range of a pulsating tube bundle by arranging more coil pipes in a limited space, thereby strengthening heat transfer and enhancing descaling.
7) This application is through the pulsating flow of average heat transfer volume automatic adjustment every tube bank to realize holistic even heat transfer, reinforcing heat transfer effect.
Description of the drawings:
FIG. 1 is a schematic structural diagram of a waste heat utilization system according to the present invention;
FIG. 2 is a schematic top view of a vibrating tube bundle configuration of the present invention.
FIG. 3 is a schematic top view of another configuration of a vibrating tube bundle of the present invention.
FIG. 4 is a schematic view of a vibrating tube bundle of the present invention.
FIG. 5 is a schematic view of another configuration of the vibrating tube bundle of the present invention.
FIG. 6 is a schematic of the heat exchanger of the present invention with an internal vibrating tube bundle.
In the figure: 1. an air preheater; 2. a dust remover 3, a first heat exchanger; 4. a first absorption/desorption column; 5. a second absorption/desorption column; 6. a gas-solid separator; 7. a booster fan; 8. a gas storage/acid production device; 9. a compressor; 10. a chimney; 11. a second heat exchanger; 12. vibrating the coil pipe; 121 left coil, 122 right coil, 123 left riser, 124 right riser, middle riser 125, free ends 13-14, heat exchange tubes 15, flue gas inlet 16, flue gas outlet 17.
Detailed Description
The flue gas waste heat utilization system comprises an air preheater 1, a first heat exchanger 3, a first absorption/desorption tower 4, a fan 6, a gas storage and acid production device 8, a compressor 9 and a chimney 8, wherein the air preheater 1 is connected with the first heat exchanger 3, flue gas from the air preheater 1 enters the first heat exchanger 3 to exchange heat with air in the first heat exchanger 3, the air heated from the first heat exchanger 3 enters the air preheater 1 through an air pipeline, the heat exchange with the flue gas is continuously carried out in the air preheater, the air after the heat exchange forms hot air, and preferably hot primary air enters a hearth to support combustion. The flue gas cooled by the first heat exchanger 3 is connected with a first absorption/desorption tower 4, the bottom of the first absorption/desorption tower 4 is connected with a compressor 9 through a pipeline, a fan 7 is arranged on the pipeline between the first absorption/desorption tower 4 and the compressor 9, and the upper part of the first absorption/desorption tower 4 is connected with a chimney 10 through a pipeline; the compressor 9 is connected with the gas and acid storage device 8 and the first absorption/desorption tower 4 through pipelines respectively.
Preferably, the system further comprises a second heat exchanger 11, the second heat exchanger 11 is arranged on a pipeline between the compressor 9 and the first absorption/desorption tower 4, and the cold air enters the air preheater 1 for continuously exchanging heat after exchanging heat with the thermal desorption gas from the compressor in the second heat exchanger 11. Preferably the heated air forms a hot secondary air.
Preferably, a dust remover 2 is arranged on a flue gas pipeline between the air preheater 1 and the first heat exchanger 3. The dust remover can remove dust of flue gas and reduce dust deposition and scaling.
Preferably, a gas-solid separator 6 is arranged on a pipeline between the first absorption/desorption tower 4 and the fan 7 to realize the separation of gas and solid.
Preferably, the absorption/desorption towers are two in parallel connection, namely 4 and 5, and a valve is arranged on a flue gas pipeline between the heat exchanger 3 and each absorption/desorption tower. Valves are provided on the lines between the second heat exchanger 11 and each absorption/ desorption column 4, 5. The absorption/desorption towers are arranged and are respectively provided with a valve, and the absorption/desorption towers are adsorbed and regenerated by opening and closing the valves.
When the first absorption/desorption tower 4 is used as an absorption tower, the loaded activated carbon reacts with SO in the absorption tower2Reacting, wherein when the first absorption tower is saturated, the flue gas enters a second absorption/desorption tower 5 for adsorption; the first absorption tower after saturation of adsorption starts desorption, and in this way, the two reaction towers are recycled.
Preferably, the flue gas firstly passes through the air preheater 1 for preliminary cooling and then passes through the dust remover 2, enters the heat exchanger for heat exchange with air, so that the flue gas enters the absorption tower for adsorption after the temperature of the flue gas is reduced to below 50 ℃, and the clean flue gas is discharged from the chimney 10;
preferably, the system is provided withStarting nitrogen, wherein the starting nitrogen is only used for the starting process of the desorption tower. Starting nitrogen to exchange heat with the flue gas through a first heat exchanger 4, desorbing the heated nitrogen serving as the heated nitrogen in a reaction tower which is saturated by adsorption, separating gas from solid particles through a gas-solid separator 6 by using the desorbed mixed gas, sending the desorbed mixed gas into a compressor 9 by using a booster fan 7, and adding N2With SO2And (5) separating. Separated SO2Enters a gas storage tank/acid making system 8 to realize SO2Resource utilization is carried out; n is a radical of2The heat which is released by the compression of the compressor is carried, the temperature is reduced to about 100 ℃ through the second heat exchanger 5, and the heat enters the desorption tower, and the heat is recycled. The whole system fully utilizes the waste heat of the flue gas and the compression heat release of the compressor, and realizes the reutilization and resource utilization of the activated carbon loaded ionic liquid desulfurizing agent.
Preferably, the vibration coil 12 is adopted in the first heat exchanger and the second heat exchanger, so that waste heat can be fully utilized, and energy is saved.
The invention selects triethanolamine acetate plasma liquid, and the alcohol amine ionic liquid adsorbs SO2Has chemical absorption and physical absorption at the same time, and the absorption principle is SO2The molecule reacts with-NH in the cation to form an N-S bond, as detailed in the following formula:
Figure DEST_PATH_IMAGE001A
the absorbent adopted by the invention is characterized in that the ionic liquid with high viscosity is loaded on the surface of the porous active carbon by a simple impregnation-evaporation physical loading method, so that the dispersibility of the ionic liquid is improved, the reaction specific surface area is increased, the problems that the ionic liquid with high viscosity is not beneficial to mass transfer and the like are solved, meanwhile, the ionic liquid loaded has the characteristics of difficult volatilization and good gas solubility, the particles loaded with the ionic liquid have faster gas absorption rate, the regeneration of a desulfurizing agent is realized by utilizing the waste heat of flue gas, and the operation cost can be effectively reduced.
As conceived above, the technical scheme of the invention is as follows: firstly, preparing ionic liquid, loading the ionic liquid on porous media such as carbon-based materials and the like, and then carrying out efficient desulfurization and desulfurization through a reactorThe absorbent is heated and regenerated in a regenerating device, and the required heat is mainly provided by the waste heat of the flue gas and the heat released by the compression of a compressor; at the same time, SO is recovered during regeneration2A gas.
According to the technology, the ionic liquid can adopt low-viscosity ionic liquid or high-viscosity ionic liquid, and a microwave method is adopted in the preparation process of the ionic liquid, so that a target product can be quickly synthesized, and the reaction time is shortened; according to the technology, a carbon-based material is adopted to load ionic liquid, the carbon-based material can be active carbon, active coke and the like, and can also be loaded on porous materials such as silica gel and the like, and the loading is carried out through impregnation and evaporation; and the mass ratio of the ionic liquid to the supporting material is below 1.5: 1.
In the technology, the reactor adopts a fixed bed desulfurizer and a thermal regeneration mode, the heat source comprises two parts, one part utilizes the waste heat of flue gas passing through an inlet of a desulfurization system, and the other part utilizes a compressor to compress and release heat.
The technology loads the ionic liquid by the carbon-based material, not only solves the problem that the high-concentration ionic liquid is difficult to apply, but also can remove SO more efficiently by the cooperation of the carbon-based material and the ionic liquid2。
The technology effectively reduces the regeneration cost of the absorbent by utilizing the waste heat of the flue gas, and further improves the economical efficiency of the technology.
Further preferably, the desorption absorption material is prepared by the following method:
example 1: synthesizing ionic liquid under the action of microwave, wherein the ratio of triethanolamine to acetic acid is 1.2:1, carrying out impregnation on the ionic liquid by using activated carbon or silica gel after synthesis, wherein the loading ratio is 0.75:1, and then carrying out evaporation and drying to realize the loading of the ionic liquid;
example 2: the ionic liquid is synthesized under the action of microwave, the ratio of triethanolamine to acetic acid is 1.2:1, and after synthesis, 80-120 meshes of active carbon is used for loading through impregnation. The loading ratio is 0.75:1, 7.5g of ionic liquid is accurately weighed and dissolved in 30ml of absolute ethyl alcohol, 10g of 80-100 mesh active carbon is put into the ionic liquid, the ionic liquid is continuously stirred, the temperature is gradually raised to 90 ℃, when most of the solvent is evaporated, the loaded active carbon is put into a drying oven to be dried at 50 ℃ until particles appear.
2g of loaded activated carbon is placed in a reactor, simulated flue gas is introduced, an adsorption experiment is carried out at 40 ℃, and the loaded activated carbon is penetrated within about 7 hours.
Example 3: the ionic liquid is synthesized under the action of microwaves, the ratio of triethanolamine to acetic acid is 1.2:1, and the ionic liquid is loaded by dipping with 60-80 meshes after synthesis. The loading ratio is 0.75:1, 7.5g of ionic liquid is accurately weighed and dissolved in 30ml of absolute ethyl alcohol, 10g of active carbon is put into the ionic liquid, the ionic liquid is continuously stirred, the temperature is gradually raised to 90 ℃, and when most of solvent is evaporated, the loaded silica gel is put into a drying oven to be dried at 50 ℃ until particles are presented.
2g of loaded activated carbon is placed in a reactor, simulated flue gas is introduced, and an adsorption experiment is carried out at 40 ℃. About 1.5h adsorption was complete.
Example 4: preparing the loaded activated carbon particles with the loading ratio of 1: 1. Accurately weighing 10g of ionic liquid, dissolving the ionic liquid in 40ml of absolute ethyl alcohol, putting 10g of active carbon in the ionic liquid, continuously stirring and gradually raising the temperature to 90 ℃, and when most of solvent is evaporated, putting the loaded silica gel in a drying oven and drying at 50 ℃ until particles appear.
4g of loaded activated carbon particles (containing 2g of activated carbon and 2g of ionic liquid) are weighed and subjected to an adsorption test at 40 ℃, and the adsorption efficiency is over 98 percent within 160 minutes.
Example 5: preparing the loaded activated carbon particles with a loading ratio of 1.3: 1. Accurately weighing 13g of ionic liquid, dissolving the ionic liquid in 52ml of absolute ethyl alcohol, putting 10g of active carbon in the ionic liquid, continuously stirring and gradually raising the temperature to 90 ℃, and when most of solvent is evaporated, putting the loaded silica gel in a drying oven and drying at 50 ℃ until particles appear.
4.6g of loaded activated carbon particles (containing 2g of activated carbon and 2.6g of ionic liquid) are weighed and subjected to an adsorption test at 40 ℃, and the adsorption efficiency is more than 98% in 285 minutes.
Example 6: accurately weighing 10g of triethanolamine, dissolving in 30ml of absolute ethanol, placing 10g of silica gel in the absolute ethanol, continuously stirring, gradually raising the temperature to 90 ℃, and when most of the solvent is evaporated, placing the loaded silica gel in a drying oven to dry at 50 ℃ until particles appear. Finally, the supported silica gel particles appeared white.
2g of load silica gel is put into a reactor, simulated flue gas is introduced, and an adsorption experiment is carried out at 40 ℃. Wherein the adsorption efficiency is more than 90% in 440 min.
Further preferably, the ionic liquid loaded desulfurizer is prepared according to the following process steps:
(1) weighing triethanolamine and acetic acid in a molar ratio of 1.2:1, and respectively adding into a special three-neck flask for microwave and an adjustable quantitative liquid adding device.
(2) Putting the three-neck flask into a microwave reactor, respectively connecting the three-neck flask with an adjustable quantitative liquid feeder, a protective gas guide pipe and a thermometer sleeve which are filled with acetic acid through corresponding interfaces of the microwave reactor, simultaneously putting half beaker of clear water into the microwave reactor, and starting the microwave reactor for reaction.
(3) Introducing protective gas, and dropwise adding all acetic acid in an adjustable quantitative liquid adding device into the three-neck flask within 1/2 of the reaction time; and simultaneously, the magnetic stirring speed regulating knob is regulated to stir the reactants in the three-neck flask.
(4) After the reaction is finished, evaporating part of unreacted solvent of the crude product by using a rotary evaporator, and drying the crude product in vacuum at 50 ℃ to constant weight to obtain the purified triethanolamine acetate ionic liquid.
(5) Pretreatment of activated carbon: selecting the particle size between 40 and 100 meshes; the activated carbon is repeatedly washed with distilled water to remove powdery carbon. The active carbon particles with the particle size of more than 100 meshes are too fine and smooth, and the ionic liquid is loaded on the active carbon to obtain wet soil-like solid, so that dry active carbon loaded particles cannot be obtained; meanwhile, the particle size of the activated carbon is too small, so that the gas resistance is increased, and the adsorption is not facilitated. Therefore, the active carbon with 40-100 meshes is selected for loading, and the effect is better.
(6) Dipping-evaporation: weighing 9-11g (preferably 10 g) of triethanolamine acetate ionic liquid, dissolving in 29-31 ml, preferably 30ml of ethanol, stirring uniformly, pouring accurately weighed activated carbon or silica gel particles, stirring uniformly, gradually raising the temperature, slowly evaporating, removing excessive solvent, and continuously stirring during the process of evaporating the solvent to ensure uniform loading.
(7) Drying: and putting the prepared active carbon/silica gel desulfurizer loaded with the triethanolamine acetate ionic liquid into a vacuum oven at 50 ℃ to be dried to constant weight, and taking out the loaded ionic liquid.
(8) And (3) storage: the storage condition of the supported ionic liquid is drying and sealing.
Preferably, the molar ratio of triethanolamine to acetic acid is (1.1-1.3) to 1, preferably 1.2: 1; ensures that acetic acid is completely reacted, and the triethanolamine acetate ionic liquid is alkalescent (the PH is about 9), which can promote the acidic gas SO2Adsorption of (3); when the molar ratio of the triethanolamine to the acetic acid is more than 1.2, the alkalinity of the ionic liquid is enhanced, and the corrosiveness to equipment is increased.
Preferably, the power of the microwave reactor is set to be 300W during the reaction, the reaction temperature is 65 ℃, protective gas is introduced, the flow rate can be controlled to be 0.1L/min, and the acetic acid in the adjustable quantitative liquid adding device is completely dripped into the three-neck flask within 10 min;
preferably, the loading ratio of the triethanolamine acetate ionic liquid to the activated carbon particles is between 0.5 and 1.5; if the ratio is more than 1.5, the loaded activated carbon particles are in a clay shape and do not meet the adsorption requirement; when the ratio is less than 0.5, the ionic liquid content is small, and the adsorption effect is not obvious.
Preferably, a porous carrier such as active carbon or silica gel with the particle size of 40-100 meshes is selected; wherein the active carbon particles are repeatedly washed by distilled water to remove powdery carbon, and then are dried in a drying oven at 110 ℃;
preferably, nitrogen is introduced into the used desulfurizer at the temperature of 90 ℃, and the flow rate can be controlled to be 500ml/min till SO2The concentration reaches the emission standard, thereby realizing regeneration;
the regeneration method is a mechanism experiment regeneration, adopts the following system process to carry out regeneration operation and simultaneously carries out adsorption SO for meeting the large-scale application condition of a power plant and simultaneously utilizing the tail gas of the waste heat of the flue gas2And (6) carrying out collection treatment. Utilize supplementary regeneration system of waste heat of retrieving after desulfurization, include:
(1) the flue gas is firstly cooled to below 50 ℃ by an air preheater and a heat exchanger, then enters an active carbon desulfurizer loaded with triethanolamine acetate ionic liquid for adsorption, and the purified flue gas is discharged from a reaction tower and then enters a chimney for discharge.
(2) After the desulfurizer in the reaction tower is adsorbed and saturated, desorption is carried out, and the desorbed gas is N2，N2The heat source of (A) is compressor compression heat release, so that N2The temperature reaches about 90-100 ℃ and then enters a desorption tower for desorption.
(3) After desorption, the resulting desorbed gas mixture (N)2And SO2) Firstly, the desulfurizer particles mixed with the gas-solid separator are separated by the gas-solid separator, the desorption mixed gas is sucked into a compressor by a booster fan, and SO is added2After being compressed by a compression device, the mixture enters a gas storage tank or an acid making system. The heat generated in the compression process is N2And the temperature is reduced by the heat exchanger and then enters the desorption tower, so that the circulation of a desorption system is formed.
(4) When the desorption gas required by the desorption system is enough, the air directly enters the air preheater after exchanging heat with the flue gas through the heat exchanger; n is a radical of2The heat exchange medium in the heat exchanger is air, and the air is heated and then enters the air preheater, so that the hot air required in the boiler is provided. The whole system fully utilizes the waste heat of the flue gas and the compression heat release of the compressor to realize the reutilization of the activated carbon loaded ionic liquid desulfurizing agent and the SO2The resource utilization is realized.
Heat exchange tubes are provided in the first heat exchanger and/or the second heat exchanger, said heat exchange tubes being as in fig. 2-5. As shown in fig. 2, the heat exchanger comprises a middle pipe 125, a left pipe 123, a right pipe 124 and a plurality of coil pipes 12, wherein each coil pipe 12 comprises a plurality of heat exchange pipes 15 in the shape of a circular arc, the end parts of the adjacent heat exchange pipes 15 are communicated, the heat exchange pipes 15 are connected in series, and the end parts of the heat exchange pipes 15 form heat exchange pipe free ends 13 and 14; the coil pipe 12 comprises a left coil pipe 121 and a right coil pipe 122, one side of a middle pipe 125 is connected with an inlet of the left coil pipe 121, the other side of the middle pipe is connected with an inlet of the right coil pipe 122, an outlet of the left coil pipe 121 is connected with a left pipe 123, and an outlet of the right coil pipe 122 is connected with a right pipe 122. The left coil outlet and the right coil outlet are arranged on one side of the middle pipe; the left tube group and the right tube group are in mirror symmetry along the plane where the axis of the middle evaporation tube is located.
The air passes from the inlet of the middle tube 125 into the left and right coils, the heat exchange tube bundle vibrates under the impact of the fluid flow, which reduces ash deposition, and then the outermost heat exchange tubes pass through the flow inside the heat exchange tubes, finally pass through the outlet flow passage outlet riser of the innermost heat exchange tubes, and finally flow out through the outlet riser.
According to the invention, through improving the prior application, the coil pipes are respectively arranged into two coils which are distributed left and right, and the left coil pipe outlet and the right coil pipe outlet are arranged on one side of the middle pipe, so that the coil pipes distributed on the left side and the right side can vibrate, the vibration area is enlarged, the vibration is more uniform, the heat exchange is strengthened, and the dust deposition effect is reduced.
Preferably, the housing of the heat exchanger has a circular cross-section, and the opening formed between the ends of the free ends faces the center of the circular cross-section of the heat exchanger. So that heat exchange and vibration are carried out inside to strengthen heat transfer.
Preferably, the left coil pipe is centered on the axis of the left pipe, and the right coil pipe is centered on the axis of the right pipe. The left and right coil pipes are arranged as circle centers, so that the distribution of the coil pipes can be better ensured, and the vibration and the heating are uniform.
The plurality of coils 12 on the same side are arranged in parallel along the height direction of the middle tube 125.
Preferably, the left and right tubes 123, 124 are arranged in mirror symmetry along the plane of the axis of the central tube 125.
The symmetrical structural distribution of the right pipe is made by the left and right coil pipes, so that the vibration can be more uniform, and the heat exchange and dust deposition removal effects are enhanced.
Preferably, the left coil 121 and the right coil 122 are staggered in the height direction, as shown in fig. 3 to 4. Through the staggered distribution, can make to vibrate the heat transfer and remove the deposition on the co-altitude not for the vibration is more even, strengthens the heat transfer and removes the deposition effect.
Preferably, the inlet direction of the middle pipe 125 is located at the lower end of the middle pipe 125. Through setting up at the lower extreme for the pulse air current flows from the lower extreme to the upper end, fills in proper order and is full of the coil pipe, can guarantee that the air current fully fills in and is full of in whole heat exchange tube, reduces the heat transfer short circuit.
Preferably, as shown in fig. 2 and 3, a plurality of coil pipes 13 are provided on the same side (left side or right side) in the height direction of the middle pipe 125. The tube diameter of the heat exchange tube of the same side coil becomes larger along the direction from the upper end to the lower end of the middle tube 125. Because the experiment and practice find that along with the continuous proceeding of heat exchange, the lower end is the more easy to deposit dust for the heat exchange tube at the lower end, so that the flow rate of the air flow distributed by the lower end is more and more through the larger pipe diameter distribution of the lower end, the vibration frequency is higher, the dust deposition removing effect is better, and the heat exchange effect is integrally and obviously enhanced.
Preferably, the tube diameter of the heat exchange tube of the same side coil increases continuously along the direction from the upper end to the lower end of the middle tube 125. Because the experiment and practice find that along with the continuous proceeding of heat exchange, the speed of the deposited dust is not in direct proportion distribution from top to bottom, but the increasing amplitude of the deposited dust is also increased, the pipe diameter change amplitude of the lower end is large, the flow increasing amplitude of the air flow distributed by the lower end is large, the frequency increasing amplitude of vibration is large, the dust removing effect is good, and the heat exchange effect is obviously enhanced on the whole.
Preferably, the coil pipes on the same side are arranged in plural along the height direction of the middle pipe 125, and the pitch of the heat exchange pipes on the same side becomes smaller along the direction from the upper end to the lower end of the middle pipe 125. Because found in experiment and practice, along with the continuous going on of heat transfer, more toward the lower extreme, the heat transfer effect is better, consequently through the close of this lower extreme pulse tube distribution for the flow of the air current of lower extreme distribution is also more, thereby makes the frequency of vibration also bigger, and the heat transfer effect is also better, thereby leads to the whole obvious reinforcing of heat transfer effect.
Preferably, the spacing between the coil heat exchange tubes decreases in a direction from the upper end to the lower end of the middle tube 125. Because found in experiment and practice, along with the continuous going on of heat transfer, from top to bottom, the speed that the heat transfer effect increases is not directly proportional distribution, but the range of heat transfer effect also constantly grow, consequently the distribution density variation range through this lower extreme is some big for the flow increase range of the air current of lower extreme distribution is also more, and thus the frequency increase range that makes the vibration is also big more, and the heat transfer effect is also better, thereby leads to the whole obvious reinforcing of heat transfer effect.
Preferably, a plurality of heat exchange tubes are provided within the heat exchanger/second heat exchanger. The system also includes a controller that automatically detects a heat exchange amount of each heat exchange tube, then calculates an average heat exchange amount of the heat exchange tubes according to a weighted average, and automatically adjusts an airflow rate of each heat exchange tube according to the average heat exchange amount.
The heat exchange quantity of the heat exchange pipe fitting is obtained by calculating the fluid temperature and the flow of the inlet and the outlet.
Through detecting and calculating the average heat exchange quantity, the heat exchange condition of each heat exchange pipe fitting can be automatically detected, and then whether the accumulated dust vibration needs to be removed and the force of the accumulated dust vibration is removed is determined, so that each heat exchange pipe fitting achieves the overall uniform heat exchange in the heat storage tank.
Preferably, the controller detects that the heat exchange amount of a certain heat exchange pipe fitting is lower than the average heat exchange amount by a certain data, for example, lower than 10% of the average heat exchange amount, and then the controller controls to automatically increase the air flow rate of the heat exchange pipe fitting. Through increasing airflow, increase on the one hand and remove the deposition, reduce because the reduction of the heat exchange efficiency that the deposition brought, on the other hand can pass through the vibration reinforcing heat transfer for the heat transfer volume reaches the average number.
Preferably, the controller detects that the heat exchange amount of a certain heat exchange pipe is higher than the average heat exchange amount by a certain value, for example, higher than 10% of the average heat exchange amount, and then the controller controls to automatically reduce the air flow rate of the heat exchange pipe. By reducing the airflow rate, heat transfer can be reduced by reducing vibration, so that the amount of heat transfer averages out. Thereby making the overall heat exchange uniform.
Preferably, the inlet line of each heat exchange tube is provided with a valve, and the valve controls the amount of air flow entering each heat exchange tube.
Although the present invention has been described with reference to the preferred embodiments, it is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (2)

1. A flue gas carbon-based loaded ionic liquid flue gas desulfurization method is characterized by comprising an air preheater, a first heat exchanger, a second heat exchanger, a first absorption/desorption tower, a second absorption/desorption tower, a gas-solid separator, a fan, a gas storage and acid production device, a compressor and a chimney, wherein the air preheater is connected with the heat exchanger, flue gas cooled by the air preheater enters the first heat exchanger to perform secondary heat exchange with air in the heat exchanger, and the heated air is returned to the air preheater to be reheated for secondary utilization; the first heat exchanger is also used as a heater for starting nitrogen gas of the analysis system, and the heated nitrogen gas is connected with the absorption/analysis tower through a pipeline; the flue gas side of the second heat exchanger is connected with an absorption/desorption tower, the upper part of the absorption/desorption tower is connected with a chimney through a pipeline, the bottom of the absorption/desorption tower is connected with a gas-solid separator through a pipeline, a fan and a compressor are sequentially connected behind the gas-solid separator, and the compressor is respectively connected with a gas and acid storage device and the second heat exchanger through pipelines; the heat exchanger is an asymmetrically arranged heat exchanger and comprises a header, and left coil pipes and right coil pipes are distributed on the left side and the right side of the header;
the absorption/desorption tower is two devices with a parallel structure, and the valves are arranged on the inlet flue gas pipeline and the outlet flue gas pipeline for switching;
loaded ionThe liquid activated carbon reacts with SO in a first absorption/desorption tower2Carrying out absorption reaction, and switching the flue gas into a second absorption/desorption tower for adsorption when the absorption is saturated; the first absorption/desorption column starts desorption, in such a way that both reaction columns are recycled.
2. The method of claim 1, including left and right tubes as headers for the left and right coils.
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