CN100377763C - A method of using active coke to purify flue gas - Google Patents

Abstract

The invention discloses a method for purifying flue gas by using active coke. The method of using activated coke to purify flue gas provided by the present invention comprises that the flue gas is purified in a desulfurization and denitrification reactor composed of a two-stage moving bed reactor equipped with activated coke, and the process is as follows: the flue gas first enters the bottom The second stage reactor with active coke from the first stage reactor absorbs and removes SO ₂ in the flue gas, and then mixes it with NH ₃ or H ₂ and CO mixed gas, and enters the top first stage with active coke The reactor reacts with the activated coke in the first stage reactor at the top to remove nitrogen oxides, wherein the flue gas is also purified through the pipeline for injecting activated coke. The method of using activated coke to purify flue gas in the present invention can remove heavy metal pollutants such as SO ₂ , NO _X and mercury at the same time, has the advantages of high flue gas purification rate, low engineering investment, no water consumption in the purification process, etc., and has wide popularization and application prospect.

Description

A method of using active coke to purify flue gas

technical field

The invention relates to a flue gas purification method, in particular to a method for purifying flue gas using active coke.

Background technique

The development of clean coal technology is one of the sustainable development strategies. Air pollution in China is mainly caused by coal burning, and the produced NO _x and SO ₂ can cause acid rain hazards; and the possible environmental pollution caused by heavy metals such as mercury, lead, and chromium in coal after burning has attracted widespread attention. Mercury is an example. Mercury usually exists in the form of cinnabar and free mercury in coal. When it is burned, it volatilizes into the flue gas and is harmful to humans and animals.

At present, most foreign flue gas purification adopts wet technology, but the promotion and application of wet flue gas purification technology in power plants in some areas of China is limited. Activated coke flue gas purification technology is an advanced dry flue gas purification technology, and methods such as active coke fixed bed and moving bed have been developed and studied. The inventor of the present invention applied for an invention patent titled "a method for flue gas desulfurization and denitrification" on June 25, 2004, and the application number is 200410038037.X. The flue gas desulfurization and denitrification method is carried out in a desulfurization and denitrification reactor composed of two-stage moving bed reactors. The process includes: the flue gas first enters the second-stage reactor with activated coke from the first-stage reactor at the bottom, The SO ₂ in the flue gas is adsorbed and removed, and then mixed with NH ₃ or H ₂ and CO mixed gas, then enters the reactor with activated coke in the first section of the top, and reacts with the active coke in the first section of the top reactor. In addition to nitrogen oxides, the resulting gas is discharged into the atmosphere. Under the action of _NH3 or _H2 and CO mixed reducing agent, this method has high denitrification performance, solves the problems of slow reaction speed and low denitrification efficiency in flue gas desulfurization and denitrification, and is mainly used for flue gas desulfurization and denitrification; however, the moving bed device used in this technology is generally relatively large, and the equipment investment is high. In addition, the broken activated coke produced in the process of desulfurization and denitrification is generally processed by incineration, and the utilization rate is not high, which makes the operating cost high.

Contents of the invention

The object of the present invention is to provide an efficient and continuous flue gas purification method using active coke.

The method of using activated coke to purify flue gas provided by the present invention comprises that the flue gas is purified in a desulfurization and denitrification reactor composed of a two-stage moving bed reactor equipped with activated coke, and the process is as follows: the flue gas first enters the bottom The second stage reactor with active coke from the first stage reactor absorbs and removes SO ₂ in the flue gas, and then mixes it with NH ₃ or H ₂ and CO mixed gas, and enters the top first stage with active coke The reactor reacts with the activated coke in the first stage reactor at the top to remove nitrogen oxides therein, and it is characterized in that: the flue gas is also purified through a pipeline for injecting activated coke.

The flue gas purification method of the present invention has multiple combinations. The flue gas can be purified first through a desulfurization and denitrification reactor composed of two-stage moving bed reactors equipped with active coke, and then through a pipeline for injecting active coke. It can also be purified first through the pipeline for injecting active coke, and then through the desulfurization and denitrification reactor composed of two-stage moving bed reactors equipped with active coke.

In order to improve the flue gas purification efficiency, the active coke used for pipeline injection is derived from the active coke produced by the two-stage moving bed reactor, which usually needs to be ground into powder before use.

After the flue gas is purified by spraying activated coke through the pipeline, the flue gas is separated from the powdered active coke through the dust collector, and can be emptied or used for the next step of desulfurization and denitrification.

In the present invention, the space velocity of the moving bed is 800-2000h ^-1 , and the injection amount of activated coke injected into the pipeline is 10-400mg active coke/m ³ flue gas. In order to ensure the effect of flue gas purification, the temperature of the flue gas is preferably 100-180°C.

The active coke used in the present invention is preferably the active coke prepared in the patent application with the application number 02146004.3 and the title of the invention "a method for preparing activated carbon". The two-stage moving bed reactor for desulfurization and denitrification reactions can be selected from the reactor disclosed in the patent No. 00254473.3 named "a flue gas desulfurization device" invented by the inventor of the present invention.

The method of using activated coke to purify flue gas in the present invention is divided into two stages, wherein the schematic diagram of the desulfurization and denitrification process using activated coke moving bed reactor is shown in Figure 1A, and the process schematic diagram of using pipeline spraying activated coke to purify flue gas is shown in Figure 1B . The broken activated coke produced in the moving bed has undergone multiple _SO2 adsorption and heating regeneration treatments. Since the heating regeneration is the oxidation reaction between the sulfuric acid on the surface of the active coke and the carbon on the surface of the active coke, its adsorption and demercuration performance has been significantly improved, which can After it is ground into powder, it is used for pipe spraying to purify flue gas. In the present invention, due to the removal of some heavy metal pollutants such as SO ₂ , NO _X and mercury in the flue gas by pipe injection purification, the pressure of the flue gas purification of the active coke moving bed is reduced, so that the space velocity of the active coke moving bed can be changed from the conventional process The 200-600h ^-1 can be increased to 800-2000h ^-1 , which can reduce the volume of the moving bed reactor, and the active coke used in the pipe injection has high performance, which can not only significantly improve the flue gas purification efficiency, but also reduce the waste of moving bed active coke , save the amount of active coke, and significantly reduce the cost of flue gas purification. The method of using activated coke to purify flue gas in the present invention can remove heavy metal pollutants such as SO ₂ , NO _X and mercury at the same time, has the advantages of high flue gas purification rate, low engineering investment, no water consumption in the purification process, etc., and has wide popularization and application prospect.

Description of drawings

Figure 1A is a schematic diagram of the desulfurization and denitrification process using an active coke moving bed reactor;

Fig. 1B is a schematic diagram of a process for purifying flue gas by injecting activated coke into a pipeline;

Fig. 2 is a structural schematic diagram of a pipeline jet purifier.

Detailed ways

Embodiment 1, flue gas purification desulfurization, denitrification, demercury

1. The flue gas is purified by active coke moving bed reactor

Sulfur and nitrate in flue gas were removed by using two-stage moving bed reactor produced by Nanjing Electric Power Automation Equipment General Factory. The SO ₂ concentration in the flue gas is 5000mg/m ³ , the NO _X concentration is 500mg/m ³ , the Hg content is 20ug/m ³ , the temperature is 120°C, and the space velocity of the moving bed reactor is 1000h ^-1 . 150 kg of active coke is added to the first section of the SO _x / NO _x reactor; the concentration of NH ₃ and CO mixed reducing agent added is 500 mg/m ³ (NH ₃ /CO molar ratio is 20), and the temperature is 10 -100°C, the intake air flow rate is 500m ³ /h. The activated coke after the second desulfurization reaction is recycled and sent to the regeneration tower, heated at 200-600u°C for 3-30h for regeneration, and the CO gas generated during the regeneration process is sent to the _deSOx / _deNOx reactor to regenerate the activated coke After adding 0.5-10% of the total amount of new active coke, it is sent to the first section of the de-SO _x / de-NO _x reactor to start the next cycle.

2. The flue gas is purified by pipe spraying active coke

Grind the crushed active coke generated in the moving bed in the previous step into a powder with a particle size of 100-320 mesh, which is used in the pipeline jet purifier.

The structure of the pipeline jet purifier is shown in Figure 2, the active coke storage bin 11, the quantitative feeder 12, the gas compressor 13 and the active coke delivery pipeline 14 form the active coke delivery system, and there is a row of active coke input holes on the pipeline 22 21 is used to spray activated coke into the pipeline 22, and the flue gas flows in the pipeline 22. The active coke stored in the active coke storage bin 11 enters the quantitative feeder 12, presses air into it with the gas compressor 13, controls the injection amount of active coke through the quantitative feeder 12, and sprays the active coke through the active coke conveying pipeline 14 is sent into the pipeline 22 from the active coke input hole 21, and the flue gas in the pipeline 22 is purified.

The flue gas passing through the moving bed reactor is passed into the pipe jet cleaner, and the active coke is sprayed into the pipe at an injection rate of 150mg active coke powder/ ^m3 flue gas.

The removal rate of flue gas SO ₂ is 95%, NO _X removal rate is 79%, and Hg removal rate is 85%.

Embodiment 2, flue gas purification desulfurization, denitrification, demercury

1. The flue gas is purified by pipe spraying active coke

The flue gas SO ₂ content is 3000mg/m ³ , the NO _X concentration is 300mg/m ³ , the Hg content is 10ug/m ³ , and the flue gas temperature is 120°C, the flue gas is passed into the pipeline as in Example 1 for jet purification In the device, inject active coke into the pipeline at an injection rate of 380mg active coke powder/m ³ flue gas. Among them, the initial active coke powder used can be new active coke, and the subsequent process can use broken active coke generated in the moving bed.

2. The flue gas is purified by active coke moving bed reactor

Pass the flue gas obtained in the previous step into the moving bed reactor as in Example 1, wherein the space velocity of the moving bed is 800h ^-1 , and the concentration of the added NH ₃ and CO mixed reducing agent is 300PPm (NH ₃ /CO molar Ratio is 5), and all the other processes are carried out according to embodiment 1.

The removal rate of flue gas _SO2 is 98%, _NOx removal rate is 83%, and Hg removal rate is 90%.

Embodiment 3, flue gas purification desulfurization, denitrification, demercury

The flue gas SO ₂ content is 7500 mg/m ³ , the NO _X concentration is 600 mg/m ³ , the Hg content is 25ug/m ³ , the flue gas temperature is 180°C, and the flue gas is continuously carried out according to step 1 and step 2 of Example 1. Gas purification, where the space velocity of the moving bed is 900h ^-1 , the concentration of the added H ₂ and CO mixed reducing agent is 600mg/m ³ (the molar ratio of H ₂ /CO is 0.5), and the injection amount of activated coke pipeline is 50mg/m ³ . The removal rate of _SO2 is 90%, _NOx removal rate is 75%, and Hg removal rate is 80% in the whole process.

Claims (9)

1. the method for a purifying flue gas by application of active coke, comprise that flue gas purifies in the desulfurization and denitrification reaction device that is made of two sections moving-burden bed reactors of activated coke is housed, its flow process is: second section reactor from the activated coke of first section reactor is housed, the SO in the adsorbing and removing flue gas bottom flue gas is introduced into ₂, then with NH ₃Or H ₂After the mixing of CO mist, enter the first section reactor that is added with activated coke in top, react the nitrogen oxide that removes wherein with the activated coke in the first section reactor in top, it is characterized in that: described flue gas also purifies by the pipeline that sprays activated coke.

2. method according to claim 1 is characterized in that: described flue gas purifies by the desulfurization and denitrification reaction device that is made of two sections moving-burden bed reactors that activated coke is housed earlier, and then purifies by the pipeline that sprays activated coke.

3. method according to claim 1 is characterized in that: described flue gas purifies by the pipeline that sprays activated coke earlier, and then purifies by the desulfurization and denitrification reaction device that is made of two sections moving-burden bed reactors that activated coke is housed.

4. according to claim 1 or 2 or 3 described methods, it is characterized in that: described duct injection derives from the activated coke that described two sections moving-burden bed reactors produce with activated coke.

5. according to claim 1 or 2 or 3 described methods, it is characterized in that: described two sections moving-burden bed reactor air speeds are 800-2000h ^-1

6. according to claim 1 or 2 or 3 described methods, it is characterized in that: the emitted dose of described duct injection activated coke is 10-400mg activated coke/m ³Flue gas.

7. method according to claim 5 is characterized in that: the emitted dose of described duct injection activated coke is 10-400mg activated coke/m ³Flue gas.

8. according to claim 1 or 2 or 3 described methods, it is characterized in that: the temperature of described flue gas is 100-180 ℃.

9. method according to claim 7 is characterized in that: the temperature of described flue gas is 100-180 ℃.

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