CN-117305542-B - Converter gas purification and energy recovery system and method

CN117305542BCN 117305542 BCN117305542 BCN 117305542BCN-117305542-B

Abstract

The invention provides a converter gas purifying and energy recycling system which consists of a movable particle bed, a waste heat boiler, a secondary dust remover and a gas tank, wherein moving bed particles are formed by pressing converter ash, and the components contain a large amount of iron and iron oxides. The invention also provides a method for using the system, which comprises the steps of enabling the high-temperature converter gas to enter a movable particle bed, filtering most of dust and purifying oxygen components in the gas to prevent gas explosion in subsequent operation, enabling the purified gas to enter a waste heat boiler to recover waste heat to generate medium-high pressure steam, enabling the waste heat recovered gas to be dedusted in a secondary deduster, and enabling the gas to enter a gas holder. And when the CO content in the gas is lower than the concentration in the tank, the gas enters the movable particle bed for reducing the iron oxide in the particles. The method adopts a full dry method for dedusting, has zero water resource consumption, does not have the problem of gas safety, is environment-friendly, and has no dust and CO emission. The sensible heat of the full temperature area in the converter gas, the chemical energy in the discharged gas and TFe resources in the dust-removing ash can be recovered.

Inventors

LIU CHUANPING
HE ZIYI
WU HAIDONG
WANG HONGJUN

Assignees

北京科技大学
河钢集团有限公司
河钢股份有限公司唐山分公司

Dates

Publication Date: 20260505
Application Date: 20231010

Claims (9)

1. A converter gas purifying and energy recovering system is characterized by comprising a movable particle bed, a waste heat boiler, a secondary dust remover and a gas cabinet, wherein, The movable particle bed comprises an upper section bed layer, a middle section bed layer and a lower section bed layer which are sequentially connected, wherein the lower section bed layer is provided with a first air inlet and a first air outlet of the movable particle bed, the middle section bed layer is provided with a second air inlet and a third air inlet of the movable particle bed, and the upper section bed layer is provided with a second air outlet of the movable particle bed; The converter gas outlet is connected with a first gas inlet of the movable particle bed, a first gas outlet of the movable particle bed is sequentially connected with the waste heat boiler, the secondary dust remover and the gas tank, and a gas passage is formed, The gas tank is only provided with a gas inlet and a gas outlet, a pipeline connected with the gas inlet and the gas outlet of the gas tank is divided into two branches, one branch is connected with the secondary dust remover, and the other branch is connected with the third air inlet of the movable particle bed.
2. The converter gas cleaning and energy recovery system of claim 1, wherein the particles packed in the moving particle bed are pressed from iron-containing fly ash from the moving particle bed and/or secondary dust collector.
3. The converter gas cleaning and energy recovery system of claim 2, wherein copper and tin are also added to the particles.
4. The converter gas cleaning and energy recovery system of claim 1, wherein in the moving particle bed, the upper bed and the lower bed are both vertically arranged, and the middle bed is obliquely arranged.
5. The converter gas cleaning and energy recovery system of claim 4, wherein the tilt angle of the middle bed layer is 20-40 °.
6. The converter gas cleaning and energy recovery system according to any one of claims 1 to 5, wherein an induced draft fan is arranged between the secondary dust collector and the gas tank, a first valve is arranged between the gas tank and the induced draft fan, a second valve is arranged at the second air inlet, and a third valve is arranged between the gas tank and the third air inlet.
7. A method for cleaning converter gas and recovering energy, wherein the method adopts the system of claim 6, and comprises the following steps: S1, measuring the concentration of CO and O 2 in the converter gas at the outlet of the secondary dust remover, If the outlet CO of the secondary dust collector is higher than or equal to the set concentration value and O 2 is lower than the set concentration value, performing step S2; If the outlet CO of the secondary dust collector is lower than the set concentration value and/or the concentration of O 2 is higher than the set value, performing step S3; After the step S3 is finished, the concentration of CO in the converter gas is measured at the gas outlet of the upper-stage bed layer, and if CO is contained, the step S4 is carried out; S2, opening the first valve, closing the second valve and the third valve, filtering dust contained in converter gas after the converter gas enters a lower-stage bed layer of the movable particle bed, discharging the dedusted converter gas from an air outlet of the movable particle bed positioned in the lower-stage bed layer, sequentially entering a waste heat boiler for heat exchange, entering a secondary deduster for dedusting, and then entering a gas cabinet; S3, opening a third valve, closing the first valve and the second valve, enabling converter gas to sequentially pass through a lower-stage bed layer of the movable particle bed, a waste heat boiler and a secondary dust remover and then enter a middle-stage bed layer, reducing iron oxides in particles into metallic iron in the middle-stage bed layer by the converter gas, discharging the converter gas after CO removal from an air outlet of the lower-stage bed layer of the movable particle bed, sequentially passing through the waste heat boiler and the secondary dust remover, enabling the converter gas to enter an upper-stage bed layer to perform countercurrent heat exchange with the particles in the movable particle bed, and then discharging the converter gas; And S4, opening the second valve, closing the first valve and the third valve during the blowing intermittence, introducing air from the outside to the second air inlet, and oxidizing iron in the particles into iron oxide in the middle-stage bed layer.
8. The method of claim 7, wherein in step S1, the concentration value of CO is set to 20% -30%, the concentration value of O 2 is set to 2%, and the concentrations are all volume concentrations.
9. The method of claim 7, wherein the middle and lower beds each have a heat storage function, and the bed temperature is maintained above 800 ℃ at all times.

Description

Converter gas purification and energy recovery system and method Technical Field The invention relates to a converter gas purification and energy recovery system and method, belongs to the technical field of industrial kiln high-temperature flue gas purification and waste heat and residual energy recovery, and particularly aims at converter gas of a steel enterprise. Background In ferrous metallurgy production, a large amount of high-temperature gas, namely converter gas, is generated by a converter, and is an important secondary energy source for iron and steel enterprises. The converter gas has high temperature and a large amount of dust, and the dust content is about 80-150 g/m 3, and mainly comprises iron, ferric oxide, calcium oxide, manganese monoxide, silicon dioxide, carbon and the like. At present, the enterprises mostly adopt a converter gas LF dry method for dust removal. The main process is that the coal gas in the vaporization cooling flue is cooled from 1450 ℃ to 800-900 ℃, water is sprayed in a steam cooler for evaporation, the temperature is rapidly reduced to below 200 ℃, the coal gas enters a dust remover for purification, and then the temperature is further reduced and is sent to a converter gas cabinet. The LF dry dedusting still has certain defects that waste heat in the range of 200-900 ℃ is not recovered, a large amount of cooling water (0.2 ton of water/ton of steel) is wasted, water is changed into steam, the gas humidity is increased, the loads of a deduster and an induced draft fan are increased, and the power consumption is increased. The adoption of the 'full dry method dust removal and the recovery of steam by the waste heat boiler' ensures the full recovery and utilization of heat, but the practical application has a plurality of difficulties. Firstly, converter blowing is intermittent, gas temperature and gas quantity periodically fluctuate greatly, and long-term quenching and rapid heating resistant waste heat recovery equipment is needed. Secondly, the converter dust has complex components and cohesiveness at high temperature, can form high-temperature corrosion and scaling on equipment, and is difficult to filter and purify. In addition, in the converter steelmaking process, the air-gas is frequently converted, when equipment is not operated, the CO-containing gas is mixed with the oxygen-containing air, and the hidden danger of explosion exists. The converter gas is inflammable and explosive, and the safety problem of gas explosion caused by air suction must be considered in the process of heat recovery. The explosion limit of the converter gas is 21.5-71.5%, and the concentration range of the generated converter gas is wider in the recovery process of the converter gas, and if air is sucked into a pipeline, the explosion can be possibly caused. The lowest firing temperature of the converter gas is approximately 610 ℃. When the temperature of the converter gas is over 610 ℃ during normal recovery, if air is sucked into the pipeline, CO in the converter gas reacts with oxygen in the air rapidly, the oxygen is consumed rapidly, and oxygen accumulation can not be caused. Therefore, above 610 ℃, the converter gas is safe, and high-temperature converter gas (above 800 ℃) in the vaporization cooling flue does not explode. However, in the process of recovering waste heat in the middle temperature section of the converter gas, the converter gas needs to be cooled to be below 610 ℃, and the possibility of explosion exists. Depending on the three elements of the gas explosion, the combustible gas explosion requires sufficient ignition energy. In the waste heat recovery process of converter gas, fire seeds of smoke dust bands or sparks generated by collision friction between smoke dust and recovery equipment can be an ignition source for converter gas explosion. In the process of converter oxygen blowing smelting, the converter splash can generate red slag with larger particles and higher heat, and in the middle-temperature section recovery process, the red slag enters the waste heat recovery device along with the converter gas, so that the converter gas explodes. Disclosure of Invention The invention provides a converter gas purifying and energy recycling system aiming at high-temperature dust-containing converter gas and a method for purifying and recycling the converter gas by adopting the system. The method can realize the recovery of waste heat in the whole temperature range of the converter gas and zero release of the converter gas. The method does not need to arrange an explosion venting valve, and simultaneously realizes the recycling utilization of the converter ash. In order to achieve the above purpose, the technical scheme of the invention is as follows: The invention provides a converter gas purifying and energy recycling system, which comprises a movable particle bed, a waste heat boiler, a secondary dust remover and a gas cabinet, wherein, The movable particle bed com