CN111001292B - Coal chemical looping combustion demercuration device and method - Google Patents

Coal chemical looping combustion demercuration device and method Download PDF

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CN111001292B
CN111001292B CN201911199416.XA CN201911199416A CN111001292B CN 111001292 B CN111001292 B CN 111001292B CN 201911199416 A CN201911199416 A CN 201911199416A CN 111001292 B CN111001292 B CN 111001292B
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flue gas
reactor
air
fuel
cyclone separator
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CN111001292A (en
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刘敦禹
刘壮
金晶
熊志波
王秋麟
程潜
林黎明
李伟
冯亮
倪明国
蔡雨阳
许开龙
何军飞
于志浩
林丰
李承绪
黄小妞
赵健
沈翰
郑良倩
曲小珂
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University of Shanghai for Science and Technology
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8665—Removing heavy metals or compounds thereof, e.g. mercury
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D45/00—Separating dispersed particles from gases or vapours by gravity, inertia, or centrifugal forces
    • B01D45/12—Separating dispersed particles from gases or vapours by gravity, inertia, or centrifugal forces by centrifugal forces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/864—Removing carbon monoxide or hydrocarbons
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8671—Removing components of defined structure not provided for in B01D53/8603 - B01D53/8668
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/10—Single element gases other than halogens
    • B01D2257/108—Hydrogen
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/50—Carbon oxides
    • B01D2257/502—Carbon monoxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/60—Heavy metals or heavy metal compounds
    • B01D2257/602—Mercury or mercury compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/02—Other waste gases
    • B01D2258/0283—Flue gases

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Abstract

The invention provides a coal chemical looping combustion demercuration device, which comprises: a fuel reactor; the fuel reactor U-phase valve is connected with the fuel reactor; the air reactor is connected with the U-phase valve of the fuel reactor; the air cyclone separator is connected with the air reactor; the flue gas cyclone separator is connected with the fuel reactor; the air reactor U-phase valve is simultaneously connected with the air cyclone separator, the flue gas cyclone separator and the fuel reactor; the condenser is connected with the flue gas cyclone separator; the SCR denitrator is connected with the condenser; the flue gas dust remover is connected with the SCR denitrator; the wet flue gas desulfurizer is connected with the flue gas dust remover; and CO2And the catcher is connected with the wet flue gas desulfurizer. The invention also provides a demercuration method based on the coal chemical looping combustion demercuration device for demercuration of flue gas generated by combustion.

Description

Coal chemical looping combustion demercuration device and method
Technical Field
The invention belongs to the technical field of chemical looping combustion, and particularly relates to a coal chemical looping combustion demercuration device and method.
Background
CO produced by industrial production and residential life2Is the main cause of global greenhouse effectFor the reason. In response to CO2Chemical looping combustion is one of the uses for CO in terms of emissions2Trapping the sealed new combustion technology. Compared with the traditional fuel combustion technology, the chemical looping combustion system consists of an air reactor and a fuel reactor, the fuel and the air are not in direct contact in the whole combustion process, and oxygen required by the combustion of the fuel is provided by an oxygen carrier. The specific process is as follows: the fuel entering the fuel reactor is combusted under the oxygen supply effect of the oxygen carrier, the flue gas and fly ash generated by combustion are separated by the cyclone separator, and the main component in the flue gas after passing through the cyclone separator is CO2And H2O (g), the flue gases then being passed through a condenser, H2O (g) condensed into liquid and CO2Separation is effected and thereby a high concentration of CO is obtained2High concentration of CO2Then is CO2The trapping device traps and stores. The oxygen carrier is subjected to reduction reaction in the fuel reactor, and the reduced oxygen carrier is collected and sent to the air reactor to be oxidized by air, and then is sent to the fuel reactor again to provide oxygen and heat required by fuel combustion. The chemical chain combustion technology is rich in CO with wide application prospect2Provided is a technique.
Because of the current energy situation of rich coal, lean oil and less gas in China, the fuel for the chemical looping combustion technology is mainly coal, and the serious hazard of mercury to human beings and natural environment is considered due to the existence of mercury elements in the coal, so the problem of mercury pollution generated in the coal combustion process cannot be ignored. Generally, mercury exists in coal combustion flue gas in three forms, namely elemental mercury, oxidized mercury and granular mercury. The oxidized mercury is water-soluble and is not easy to volatilize, so that the oxidized mercury can be removed by the wet flue gas desulfurization device of the thermal power plant in a synergic manner. The granular mercury is generally present on the surface of solid particles and can be removed by dust removal equipment such as an electrostatic dust collector or a bag type dust collector of a thermal power station. However, since elemental mercury is difficult to dissolve in water and is very volatile, it is difficult to remove elemental mercury from the flue gas treatment equipment of the conventional thermal power station, and mercury exists mainly in the form of elemental mercury at high temperatures. Thus, the problem of mercury pollution treatment in thermal power stations has been focused on the treatment of elemental mercury.
The application of mercury adsorbent injection method is very common in the aspect of coal-fired flue gas demercuration. The most common mercury adsorbents mainly comprise activated carbon-based adsorbents, but the activated carbon-based adsorbents have the serious defect of high cost. Compared with activated carbon-based adsorbents, fly ash as a byproduct of coal-fired power plants has the remarkable advantages of easy acquisition and low cost, and in recent years, many researchers propose related patents for using fly ash as a mercury adsorbent for flue gas demercuration. However, the fly ash injection methods proposed in these patents are often applied to the cooling side of flue gas with temperatures below 300 ℃, and there is no relevant research on mercury adsorbents at high temperatures. In the chemical looping combustion technology, since the temperature of the fuel reactor is generally higher than 700 ℃, if the fly ash adsorbent is used under the chemical looping combustion technology, the length of a flue gas pipeline needs to be additionally increased so as to prolong a flue gas cooling path, so that the flue gas can be cooled to be lower than 300 ℃ and then the fly ash adsorbent is sprayed. However, this results in large space occupation of the equipment, increased investment cost of chemical looping combustion technology, and generally weak adsorption at high temperature.
In the aspect of chemical-looping combustion flue gas demercuration, a document entitled "research progress of technology for removing Hg0 in coal-fired flue gas by an oxidation method" (Zhaoye et al; published in chemical engineering environmental protection, 3 months 2018) introduces research progress of a demercuration technology in coal-fired flue gas oxidation methods at home and abroad, and some researchers propose related patents for realizing the demercuration of elemental mercury by carrying out catalytic oxidation on elemental mercury in flue gas by using a metal oxide oxygen carrier. Since the metal oxygen carrier in the fuel reactor is continuously reduced in the process of providing oxygen for coal combustion, and the oxidizability of the metal oxygen carrier is continuously weakened, it is difficult to continuously oxidize the elemental mercury in the flue gas in the high-temperature environment of the fuel reactor, and if more metal oxide oxygen carriers are fed into the fuel reactor in order to improve the mercury removal efficiency, the problems of increased cost and the like caused by the increased input amount of the metal oxygen carriers are caused.
Disclosure of Invention
The present invention has been made to solve the above problems, and an object of the present invention is to provide a coal chemical looping combustion demercuration apparatus and method.
The invention providesA coal chemical looping combustion demercuration device is provided, which has the characteristics that: the fuel reactor is used for putting fuel for combustion; the fuel reactor U-phase valve is connected with the fuel reactor; the air reactor is connected with the U-phase valve of the fuel reactor and is used for providing an oxygen carrier; the air cyclone separator is connected with the air reactor and is used for separating the oxygen carrier from the air; the flue gas cyclone separator is connected with the fuel reactor and is used for separating flue gas and fly ash generated by fuel combustion; the air reactor U-phase valve is simultaneously connected with the air cyclone separator, the smoke cyclone separator and the fuel reactor and used for receiving the oxygen carrier and part of separated smoke, enabling the smoke and the oxygen carrier to react and enter the fuel reactor together, and enabling the oxygen carrier to lead Hg in the smoke to be introduced into the fuel reactor0Adsorption oxidation to Hg2+Oxidation of CO to CO2Is prepared from H2By oxidation to H2O (g); a condenser connected with the flue gas cyclone separator for separating H in the flue gas2O (g) condense, thereby H2O (g) separation from flue gas; the SCR denitrator is connected with the condenser and is used for removing nitrogen oxides in the flue gas; the flue gas dust remover is connected with the SCR denitrator and is used for collecting fly ash mixed in flue gas; a wet flue gas desulfurizer connected with the flue gas dust remover and used for removing Hg in the flue gas2+(ii) a And CO2A trap connected with the wet flue gas desulfurizer for collecting CO in the flue gas2Wherein, a flow guide pipe is arranged between the smoke cyclone separator and the U-phase valve of the air reactor for connection, the flow guide pipe is used for conveying part of separated smoke to the U-phase valve of the air reactor, the height in the valve at the side where the U-phase valve of the air reactor is connected with the flow guide pipe is higher than the height in the valve at the side where the U-phase valve of the air reactor is connected with the air cyclone separator, an inlet pipeline of the smoke cyclone separator is a thick pipeline, the section of the inlet is a suddenly-expanded section, reduced oxygen carrier in the fuel reactor enters the air reactor through the U-phase valve of the fuel reactor for reoxidation, the oxidized oxygen carrier enters the U-phase valve of the air reactor and the fuel reactor for circular reaction after passing through the air cyclone separator, and the wet-process smoke desulfurizer is also connected with the fuel reactor for connecting CO with the fuel reactor2Re-feedingTo the fuel reactor.
The coal chemical looping combustion demercuration device provided by the invention can also have the following characteristics: wherein, the fuel reactor is also provided with a fuel inlet and a fuel air distribution plate.
The coal chemical looping combustion demercuration device provided by the invention can also have the following characteristics: wherein, the air reactor is also provided with an air inlet and an air distribution plate.
The coal chemical looping combustion demercuration device provided by the invention can also have the following characteristics: wherein, the flue gas dust remover is an electrostatic dust remover or a bag type dust remover.
The coal chemical looping combustion demercuration device provided by the invention can also have the following characteristics: wherein, the air reactor and the fuel reactor are both fluidized bed reactors.
The invention also provides a demercuration method based on the coal chemical looping combustion demercuration device, which is characterized by comprising the following steps: step 1, enabling fuel to enter a fuel reactor to perform combustion reaction, enabling fly ash and smoke generated by combustion to enter an inlet pipeline of a smoke cyclone separator, separating the smoke from the fly ash through the smoke cyclone separator, enabling a part of the smoke to enter a U-phase valve of an air reactor along a guide pipe and react with an oxygen carrier in the U-phase valve of the air reactor, and enabling the oxygen carrier to react with Hg in the smoke0Adsorption oxidation to Hg2+Oxidation of CO to CO2Is prepared from H2By oxidation to H2O(g)；
Step 2, the flue gas after being adsorbed and oxidized by the oxygen carrier and the reduced oxygen carrier enter a fuel reactor together, and then enter a condenser after passing through the flue gas cyclone separator again, and the condenser enables H in the flue gas to be introduced into the condenser2O (g) coagulation of H2O (g) separation from flue gas;
step 3, the flue gas passing through the condenser enters an SCR (selective catalytic reduction) denitrator to remove nitrogen oxides;
step 4, the flue gas passing through the SCR denitrator enters a flue gas dust remover to remove fly ash mixed in the flue gas;
step 5, the flue gas passing through the flue gas dust remover enters a wet methodFlue gas desulfurizer for Hg in flue gas2+Removing to finish demercuration;
step 6, a part of CO in the flue gas passing through the wet flue gas desulfurizer2Quilt CO2The trap traps another portion of the CO2And H2And O (g) enters the fuel reactor again to be mixed with the fuel, the oxygen carrier reduced in the fuel reactor is collected, passes through a U-phase valve of the fuel reactor and is sent to an air reactor to be oxidized, and then enters the fuel reactor through an air cyclone separator and the U-phase valve of the air reactor to finish the circulating reaction, wherein the oxygen carrier is coal ash, the fuel is coal of general, and the set temperature of the air reactor and the set temperature of the fuel reactor are both 850 ℃.
Action and Effect of the invention
According to the coal chemical looping combustion demercuration device and method, before the flue gas is treated by the condenser, a part of the flue gas is circulated to the U-phase valve of the air reactor again by diversion of the flow guide pipe, so that the flue gas is contacted with the oxygen carrier in the U-phase valve of the air reactor, and Hg in the flue gas is carried out under the action of the oxygen carrier0The adsorption oxidation is carried out, and simultaneously, a small amount of CO and H in the flue gas can be oxidized, so that Hg can be realized0The catalytic oxidation also improves the oxidation rate of CO and H and improves CO2Conversion and capture efficiency of; because the side of the air reactor, which is connected with the U-phase valve and the flow guide pipe, is provided with a higher height in the valve, the contact time between the flue gas introduced from the flow guide pipe and the oxygen carrier can be prolonged, and the CO and H in the flue gas can be favorably realized2Further oxidation to CO2And H2O vapor and in favor of Hg0Oxidation of (2); because the inlet pipeline of the flue gas cyclone separator is provided with the rough pipeline and the sudden expansion section, the flue gas and the fly ash can be more effectively separated through the obvious difference of the density, the self gravity and the flow velocity of the flue gas and the fly ash; the oxygen carrier is easy to obtain and low-cost general coal ash, so that the cost can be effectively reduced; because the oxygen carrier can be reduced and re-oxidized by entering the air reactor and then enter the combustion reactor, the oxygen carrier can be reduced and re-oxidized by entering the air reactor and then enter the combustion reactorThe oxidation of the elemental mercury in the flue gas can be kept by ensuring that the oxygen carrier can keep the oxidation under the high-temperature condition of the combustion reactor.
Drawings
FIG. 1 is a schematic structural diagram of a coal chemical looping combustion demercuration device in an embodiment;
FIG. 2 is a schematic diagram of a fixed bed reactor experimental setup for testing the mercury removal efficiency of general coal ash in the examples;
FIG. 3 is a temperature rise program diagram of general coal in the example;
FIG. 4 is a graph showing the mercury removal efficiency of example coal ash in a simulated air reactor and a simulated fuel reactor.
Detailed Description
In order to make the technical means and functions of the present invention easy to understand, the present invention is specifically described below with reference to the embodiments and the accompanying drawings.
FIG. 1 is a schematic structural diagram of a coal chemical looping combustion demercuration device in an embodiment.
As shown in fig. 1, the embodiment provides a coal chemical looping combustion demercuration device 100, which includes a fuel reactor 1, a fuel reactor U-phase valve 2, an air reactor 3, an air cyclone 4, a flue gas cyclone 5, an air reactor U-phase valve 6, a condenser 7, an SCR denitrator 8, a flue gas dust remover 9, a wet flue gas desulfurizer 10, and a CO2The trap 11.
The fuel reactor 1 is used for putting fuel to burn.
The fuel reactor 1 is further provided with a fuel inlet 101 and a fuel distribution plate 102.
The fuel reactor U phase valve 2 is connected to the fuel reactor 1.
The air reactor 3 is connected with a fuel reactor U phase valve 5 for providing oxygen carrier.
Both the air reactor 3 and the fuel reactor 1 are fluidized bed reactors.
The air reactor 3 is further provided with an air inlet 301 and an air distribution plate 302.
An air cyclone 4 is connected to the air reactor 3 for separating the oxygen carrier from the air.
The flue gas cyclone separator 5 is connected with the fuel reactor 1 and is used for separating flue gas and fly ash generated by fuel combustion.
In this embodiment, the fly ash and flue gas generated by combustion enter the inlet duct of the flue gas cyclone 5 under the action of the fluidizing gas, and the fly ash particles are mainly concentrated at the position close to the wall of the duct and the flue gas is mainly concentrated at the axis of the duct due to the friction resistance of the wall of the duct and the gravity of the fly ash particles. Therefore, the inlet pipeline of the flue gas cyclone separator 5 is designed to be a thick pipeline, and the inlet section is designed to be a sudden expansion section, so that the flow velocity of flue gas and fly ash is reduced when the flue gas and the fly ash pass through the section of the inlet pipeline of the flue gas cyclone separator 5, after the fly ash particles with higher density and lower flow velocity tend to flow at two sides of the sudden expansion section after passing through the inlet pipeline of the flue gas cyclone separator 5 along the way resistance consumption, and then fall on the inclined planes at two sides of the sudden expansion section under the action of gravity and are gradually accumulated, while the flue gas with lower density and higher flow velocity and concentrated at the axle center position of the flue gas cyclone separator 5 is discharged through the outlet pipeline of the flue gas cyclone separator 5, so that the separation of the flue gas and the fly ash is completed.
The air reactor U-phase valve 6 is simultaneously connected with the air cyclone separator 4, the flue gas cyclone separator 5 and the fuel reactor 1, and is used for receiving the oxygen carrier and the separated part of flue gas, enabling the flue gas and the oxygen carrier to react and enter the fuel reactor 1 together, and enabling the oxygen carrier to lead Hg in the flue gas to enter the fuel reactor 1 together0Adsorption oxidation to Hg2+Oxidation of CO to CO2Is prepared from H2By oxidation to H2O(g)。
And a draft tube 12 is arranged between the flue gas cyclone separator 5 and the U-phase valve 6 of the air reactor for connection, and the draft tube 12 is used for conveying the separated part of flue gas to the U-phase valve 6 of the air reactor.
The height in the valve at the side of the connection between the U-phase valve 6 of the air reactor and the flow guide pipe 12 is higher than the height in the valve at the side of the connection between the U-phase valve 6 of the air reactor and the air cyclone separator 4, and by increasing the height in the valve at the side of the connection between the U-phase valve 6 of the air reactor and the flow guide pipe 12, the flue gas entering from the flow guide pipe 12 can have longer contact time with an oxygen carrier in the U-phase valve 6 of the air reactor, which is beneficial to C in the flue gasO，H2Further oxidation to CO2And H2O vapor and in favor of Hg0Oxidation of (2).
The condenser 7 is connected with the flue gas cyclone separator 5 and is used for separating H in the flue gas2O (g) condense, thereby H2O (g) is separated from the flue gas.
The SCR denitrator 8 is connected with the condenser 7 and used for removing nitrogen oxides in the flue gas.
The flue gas dust remover 9 is connected with the SCR denitrator 8 and is used for collecting fly ash mixed in flue gas.
The flue gas dust collector 9 is an electrostatic dust collector or a bag type dust collector.
The wet flue gas desulfurizer 10 is connected with the flue gas dust remover 9 and is used for removing Hg in the flue gas2+。
Hg in flue gas2+Due to its water solubility, it is capable of being removed by the wet flue gas desulfurizer 10.
The wet flue gas desulfurizer 10 is also connected to the fuel reactor 1 for feeding CO2And then to the fuel reactor 1.
CO2The catcher 11 is connected with the wet flue gas desulfurizer 10 and is used for collecting CO in the flue gas2。
The reduced oxygen carrier in the fuel reactor 1 enters the air reactor 3 through the fuel reactor U-phase valve 2 for reoxidation, and the oxidized oxygen carrier enters the air reactor U-phase valve 6 and the fuel reactor 1 for circular reaction after passing through the air cyclone separator 4.
In this embodiment, the fuel is general coal, the oxygen carrier is general coal ash, the general coal does not directly contact with air, and the air required for combustion is high-iron (Fe)2O3) High calcium (CaSO)4) The coal ash oxygen carrier is provided, and the mercury removal method of the coal chemical looping combustion-based mercury removal device 100 of the embodiment comprises the following steps:
step 1, the military coal enters a fuel reactor 1 to carry out combustion reaction, fly ash and flue gas generated by combustion enter an inlet pipeline of a flue gas cyclone separator 5, the flue gas and the fly ash are separated by the flue gas cyclone separator 5, and a part of the flue gas flows along a guide pipe 12 enters an air reactor U-phase valve 6, the air reactor U-phase valve 6 is provided with general coal ash which comes from an air reactor 3 and is separated from air through an air cyclone separator 4, the flue gas reacts with the general coal ash in the air reactor U-phase valve 6, and the general coal ash is used for converting Hg in the flue gas0Adsorption oxidation to Hg2+Oxidation of CO to CO2Is prepared from H2By oxidation to H2And O (g) and reducing the military coal ash.
Step 2, enabling the flue gas after adsorption and oxidation of the fly ash and the reduced fly ash to jointly enter a fuel reactor 1, enabling the flue gas to pass through a flue gas cyclone separator 5 again and then enter a condenser 7, and enabling the condenser 7 to enable H in the flue gas to be separated by the cyclone separator 72O (g) coagulation of H2O (g) is separated from the flue gas.
And 3, the flue gas passing through the condenser 7 enters an SCR (selective catalytic reduction) denitrator 8 to remove nitrogen oxides.
And 4, enabling the flue gas passing through the SCR denitrator 8 to enter a flue gas dust remover 9 to remove fly ash mixed in the flue gas.
Step 5, the flue gas passing through the flue gas dust remover 9 enters a wet flue gas desulfurizer 10 to remove Hg in the flue gas2+And removing to finish demercuration.
Step 6, a part of CO in the flue gas passing through the wet flue gas desulfurizer 102Quilt CO2The other part of the CO is captured by a trap 112And H2And O (g) enters the fuel reactor 1 again to be mixed with the coal, the reduced coal ash in the fuel reactor 1 is collected, passes through a fuel reactor U-phase valve 2 and is sent to an air reactor 3 to be oxidized, and then enters the fuel reactor 1 through an air cyclone separator 4 and an air reactor U-phase valve 6 to complete the circular reaction.
The set temperatures for both the air reactor and the fuel reactor were 850 ℃.
FIG. 2 is a schematic diagram of a fixed bed reactor experimental apparatus for testing mercury removal efficiency of general coal ash in an example, and FIG. 3 is a temperature rise program diagram of general coal in the example.
In the present example, Hg was catalytically oxidized by using fly ash through a fixed bed reactor experimental device as shown in FIG. 20Effect of (1) toCarrying out an experiment, comprising the following steps:
step 1, crushing general coal into 170 meshes (about 90um) of general coal powder by using a coal mill, and increasing general coal ash particles and Hg generated by the general coal powder0To contribute to Hg0Adsorption and catalytic oxidation of (3);
step 2, drying the pulverized coal at 80 ℃ for 8 hours to remove water in the pulverized coal, thereby avoiding the generation of water vapor to Hg in subsequent high-temperature experiments0The effect of catalytic oxidation;
step 3, placing the dried pulverized coal in a muffle furnace, setting the calcining temperature and the heating rate to be 850 ℃ and 20 ℃/min, setting the calcining time to be 2h, and setting the heating program as shown in figure 3;
step 4, taking out the fly ash after heating and calcining, mixing 0.2g of the fly ash with 1.0g of quartz sand, placing the mixture in a tube furnace, placing 0.03g of quartz wool on two sides of the fly ash, wherein the quartz sand is used for enabling air flow to be uniform and preventing the fly ash from being blown away by the air flow;
step 5, considering HgCl2Is the most main oxidized state mercury form, the reaction atmosphere of a fuel reactor is simulated by inputting 50ppm HCl, the reaction atmosphere of an air reactor is simulated by inputting high-purity air, and Hg is catalytically oxidized by oxygen carriers in the fuel reactor and the air reactor at four temperatures of 750 ℃, 850 ℃, 950 ℃ and 1050 ℃ respectively in a fixed bed reactor0The experimental setup is shown in fig. 2: with 100ng/min of Hg permeability0Placing a U-shaped pipe of a permeation tube in a 50 ℃ constant temperature water bath kettle, under the condition that N2 with the flow rate of 1L/min is used as carrier gas for conveying, mixing 100ug/min of mercury vapor with stable flow rate with HCl and high-purity air respectively, then entering a tubular furnace to react with a sample, and then entering flue gas into a QM201H through a mercury injection port to measure Hg after reaction0Concentration, residual Hg in the tail gas after passing through QM201H mercury-measuring instrument0And HCl gas are sequentially absorbed by activated carbon and NaOH solution. The mercury removal efficiency calculation formula is as follows: eta ═ C1-C2)/C1，C1For Hg before entering the tube furnace0Concentration, C2After entering the tube furnaceHg0And (4) concentration.
FIG. 4 is a graph showing the mercury removal efficiency of example coal ash in a simulated air reactor and a simulated fuel reactor.
As shown in FIG. 4, both in the fuel reactor and in the air reactor, fly ash showed good catalytic oxidation of Hg0The method has the advantages that the optimal reaction temperature of the fly ash in the air reactor and the fuel reactor is 850 ℃, wherein the catalytic oxidation demercuration efficiency in the simulated fuel reactor is up to about 91% at 850 ℃, and the catalytic oxidation demercuration efficiency in the simulated air reactor is up to 70% at 850 ℃.
Effects and effects of the embodiments
According to the coal chemical looping combustion demercuration device and method related by the embodiment, before the flue gas is treated by the condenser, a part of the flue gas is circulated to the U-phase valve of the air reactor again by diversion of the diversion pipe, so that the flue gas is contacted with the oxygen carrier in the U-phase valve of the air reactor, and Hg in the flue gas is carried out under the action of the oxygen carrier0The adsorption oxidation is carried out, and simultaneously, a small amount of CO and H in the flue gas can be oxidized, so that Hg can be realized0The catalytic oxidation also improves the oxidation rate of CO and H and improves CO2Conversion and capture efficiency of; because the side of the air reactor, which is connected with the U-phase valve and the flow guide pipe, is provided with a higher height in the valve, the contact time between the flue gas introduced from the flow guide pipe and the oxygen carrier can be prolonged, and the CO and H in the flue gas can be favorably realized2Further oxidation to CO2And H2O vapor and in favor of Hg0Oxidation of (2); because the inlet pipeline of the flue gas cyclone separator is provided with the rough pipeline and the sudden expansion section, the flue gas and the fly ash can be more effectively separated through the obvious difference of the density, the self gravity and the flow velocity of the flue gas and the fly ash; the oxygen carrier is easy to obtain and low-cost general coal ash, so that the cost can be effectively reduced; because the oxygen carrier can be reduced and then re-oxidized by entering the air reactor and then enter the combustion reactor, the oxygen carrier can be ensured to be oxidized under the high-temperature condition of the combustion reactor to the flue gasThe elemental mercury of (a) is oxidized.
The above embodiments are preferred examples of the present invention, and are not intended to limit the scope of the present invention.

Claims (6)

1. A coal chemical looping combustion demercuration device is characterized by comprising:
the fuel reactor is used for putting fuel for combustion;
the fuel reactor U-phase valve is connected with the fuel reactor;
the air reactor is connected with the U-phase valve of the fuel reactor and is used for providing an oxygen carrier;
the air cyclone separator is connected with the air reactor and is used for separating the oxygen carrier from air;
the flue gas cyclone separator is connected with the fuel reactor and is used for separating flue gas and fly ash generated by fuel combustion;
the air reactor U-phase valve is simultaneously connected with the air cyclone separator, the smoke cyclone separator and the fuel reactor, and is used for receiving the oxygen carrier and the separated part of smoke, enabling the smoke and the oxygen carrier to react and enter the fuel reactor together, and enabling the oxygen carrier to lead Hg in the smoke to enter the fuel reactor together0Adsorption oxidation to Hg2+Oxidation of CO to CO2Is prepared from H2By oxidation to H2O(g)；
A condenser connected with the flue gas cyclone separator and used for separating H in the flue gas2O (g) condense, thereby H2O (g) separating from the flue gas;
the SCR denitrator is connected with the condenser and is used for removing nitrogen oxides in the flue gas;
the flue gas dust remover is connected with the SCR denitrator and is used for collecting fly ash mixed in the flue gas;
a wet flue gas desulfurizer connected with the flue gas dust remover and used for removing Hg in the flue gas2+(ii) a And
CO2a trap for removing the flue gas by wet methodA sulfur trap connection for collecting CO in the flue gas2，
Wherein a draft tube is arranged between the flue gas cyclone separator and the U-phase valve of the air reactor for connection, the draft tube is used for conveying the separated part of the flue gas to the U-phase valve of the air reactor,
the height of the valve at the side of the air reactor U-phase valve connected with the draft tube is higher than that of the valve at the side of the air reactor U-phase valve connected with the air cyclone separator,
the inlet pipeline of the flue gas cyclone separator is a thick pipeline, the cross section of the inlet is a sudden expansion cross section,
the reduced oxygen carrier in the fuel reactor enters the air reactor through the U-phase valve of the fuel reactor for reoxidation, the oxidized oxygen carrier enters the U-phase valve of the air reactor after passing through the air cyclone separator for cyclic reaction with the fuel reactor,
the wet flue gas desulfurizer is also connected with the fuel reactor and is used for removing CO2Then the mixture is conveyed into the fuel reactor,
the fuel is general coal, and the oxygen carrier is general coal ash.
2. The coal chemical looping combustion demercuration device of claim 1, further comprising:
wherein, the fuel reactor is also provided with a fuel inlet and a fuel air distribution plate.
3. The coal chemical looping combustion demercuration device of claim 1, further comprising:
wherein, the air reactor is also provided with an air inlet and an air distribution plate.
4. The coal chemical looping combustion demercuration device of claim 1, further comprising:
wherein, the flue gas dust remover is an electrostatic dust remover or a bag type dust remover.
5. The coal chemical looping combustion demercuration device of claim 1, further comprising:
wherein the air reactor and the fuel reactor are both fluidized bed reactors.
6. The mercury removal method based on the coal chemical looping combustion mercury removal device as claimed in claim 1, characterized by comprising the following steps:
step 1, enabling the fuel to enter the fuel reactor to perform a combustion reaction, enabling fly ash and flue gas generated by combustion to enter an inlet pipeline of a flue gas cyclone separator, separating the flue gas from the fly ash through the flue gas cyclone separator, enabling a part of the flue gas to enter a U-phase valve of the air reactor along a flow guide pipe and react with the oxygen carrier in the U-phase valve of the air reactor, and enabling the oxygen carrier to react with Hg in the flue gas0Adsorption oxidation to Hg2+Oxidation of CO to CO2Is prepared from H2By oxidation to H2O(g)；
Step 2, the flue gas after being adsorbed and oxidized by the oxygen carrier and the reduced oxygen carrier enter the fuel reactor together, and then enter the condenser after passing through the flue gas cyclone separator again, and the condenser enables H in the flue gas to enter the condenser2O (g) coagulation of H2O (g) separating from the flue gas;
step 3, the flue gas passing through the condenser enters the SCR denitrator to remove nitrogen oxides;
step 4, the flue gas passing through the SCR denitrator enters the flue gas dust remover to remove fly ash mixed in the flue gas;
step 5, enabling the flue gas passing through the flue gas dust remover to enter the wet flue gas desulfurizer to remove Hg in the flue gas2+Removing to finish demercuration;
step 6, passing through the wet flue gas desulfurizer, and partially removing CO in the flue gas2Is covered with the CO2The trap traps another portion of the CO2And H2O (g) enters the fuel reactor again to be mixed with the fuel, the oxygen carrier reduced in the fuel reactor is collected and then passes through a U-phase valve of the fuel reactor and is sent to the air reactor to be oxidized, and then enters the fuel reactor through the air cyclone separator and the U-phase valve of the air reactor to complete the circulating reaction,
wherein the oxygen carrier is general coal ash, the fuel is general coal,
the set temperatures of the air reactor and the fuel reactor were both 850 ℃.
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