Electric furnace tail gas treatment method and device

Abstract

The invention relates to the technical field of chemical engineering, and discloses an electric furnace tail gas treatment method and an electric furnace tail gas treatment device. The method comprises the following steps: S1, carrying out first desulfurization on pretreated electric furnace tail gas to obtain desulfurized raw material gas; s2, performing first deoxidation on the desulfurized raw material gas to obtain deoxidized raw material gas; s3, mixing the deoxidized raw material gas with water vapor, and purifying to obtain transformed raw material gas; wherein the purification treatment comprises secondary desulfurization, dechlorination, arsenic removal and secondary deoxidation; s4, carrying out isothermal shift reaction on the shift feed gas, and carrying out condensation and gas-liquid separation on an obtained gas-phase product; and S5, decarburizing the crude conversion product gas obtained by gas-liquid separation to obtain decarburized conversion product gas. The treatment method is suitable for the electric furnace tail gas with high CO content and complex gas composition.

Description

Technical Field

[0001] The invention relates to the technical field of chemical industry, and in particular to a method for treating electric furnace tail gas and a device for treating electric furnace tail gas. Background Art

[0002] Carbon monoxide shift is an important part of modern coal chemical projects. Through the shift reaction, CO in the raw gas is converted into H 2 , adjust the hydrogen-carbon ratio in the feed gas to meet the requirements of downstream devices.

[0003] The shift reaction is a reversible exothermic reaction. Traditional shift technology generally uses multiple adiabatic shift reactors in series to achieve the required shift depth. With the continuous development of coal gasification technology, dry coal powder quenching process gasification technology has been widely used. The raw coal gas produced by this type of gasification technology has the "double high" characteristics of high water content and high CO content. If it directly enters the shift furnace for reaction, the catalyst bed temperature will be as high as 500°C or above, which seriously affects the service life of the catalyst and the safe operation of the system. Traditional adiabatic shift technology generally uses high water-gas ratio or low water-gas ratio process to prevent the catalyst bed from overheating. However, neither the high water-gas ratio process nor the low water-gas ratio process can fundamentally solve the problem of using the catalyst at high temperature. In recent years, isothermal shift technology has received attention from many scientific research institutions and enterprises, and has achieved breakthrough development.

[0004] US6033634 discloses a hydrogen manufacturing device, which has a plate-type high-temperature shift furnace with a shift reaction chamber filled with a high-temperature shift catalyst; a cooling chamber with a filler to promote heat transfer, a cooling gas introduced into the cooling chamber, and a partition separating the shift reaction chamber and the cooling chamber. The shift reaction chamber has a light riding chamber separated by a plate-type partition composed of a porous plate and a palladium mold that can be permeated by hydrogen. Therefore, only the hydrogen generated in the shift reaction chamber can enter the hydrogen chamber through the hydrogen permeation mold.

[0005] CN1461730A discloses a carbon monoxide conversion process and reactor. The process steps include: introducing the raw gas into the reactor tube of the reaction unit, the reactor tube having a fixed bed of conversion catalyst located in the reaction zone; contacting the water raw gas with the catalyst under the conversion reaction conditions that can effectively react carbon monoxide with water vapor to generate hydrogen; the cooling medium has a falling mold form flowing along the shell side of the reactor tube, the reaction is cooled by indirect heat exchange through the cooling medium, and the heated cooling medium is removed from the falling mold, so that the hydrogen generated by the conversion reaction reaches the permeation zone through the hydrogen selection mold; hydrogen is extracted from the permeation zone and the raw gas depleted of carbon monoxide is discharged from the reaction zone.

[0006] A large amount of tail gas is generated during the production process of ferroalloy reduction electric furnaces, which contains CO, H 2 , CH4 The effective fuel components account for about 80% of the gas volume, mainly CO, with a calorific value of 2100-2400 kcal / standard meter. Due to its complex composition and difficult treatment, electric furnace tail gas has always been a technical problem. Traditional treatment methods can no longer meet environmental protection requirements. Under the new environmental protection requirements, how to reduce exhaust gas emissions, achieve the utilization efficiency of electric furnace tail gas, improve the ecological environment, achieve industrial upgrading, energy conservation and consumption reduction, is a new topic. Summary of the invention

[0007] The purpose of the present invention is to overcome the problems of low utilization efficiency of electric furnace tail gas and high waste gas emissions in the prior art, and to provide a method for treating electric furnace tail gas and a device for treating electric furnace tail gas. The treatment method is aimed at electric furnace tail gas with high CO content and complex gas composition, can effectively reduce waste gas emissions, and can achieve efficient utilization of electric furnace tail gas, so that the CO in the electric furnace tail gas has a higher conversion rate.

[0008] In order to achieve the above object, the first aspect of the present invention provides a method for treating electric furnace tail gas, the method comprising the following steps:

[0009] S1, performing a first desulfurization on the pretreated electric furnace tail gas to obtain a desulfurized raw gas;

[0010] S2, performing a first deoxygenation on the desulfurized raw gas to obtain a deoxygenated raw gas;

[0011] S3, mixing the deoxygenated raw gas with water vapor for purification treatment to obtain a conversion raw gas; wherein the purification treatment includes a second desulfurization, a dechlorination, a dearsenicization and a second deoxygenation;

[0012] S4, subjecting the conversion feed gas to an isothermal conversion reaction, and condensing and separating the obtained gas phase product into gas and liquid;

[0013] S5. Decarburizing the crude conversion product gas obtained by the gas-liquid separation to obtain a decarburized conversion product gas.

[0014] The second aspect of the present invention provides a device for treating tail gas from an electric furnace, wherein the device comprises: a pretreatment furnace, a desulfurization unit, a deoxidation furnace, a purification furnace, an isothermal shift reaction furnace, a gas-liquid separation unit and a temperature-swing adsorption tower connected in sequence; wherein,

[0015] The pretreatment furnace is used to pretreatment the electric furnace tail gas to remove oil and dust, thereby obtaining the pretreated electric furnace tail gas;

[0016] The desulfurization unit is used to perform a first desulfurization on the pretreated electric furnace tail gas, thereby obtaining a desulfurized raw gas;

[0017] The deoxidation furnace is used to perform a first deoxidation on the desulfurized raw gas to obtain a deoxidized raw gas;

[0018] The purification furnace is filled with a desulfurizer, a dechlorinator, a dearsenicizer and a deoxidizer, which are used to perform a second desulfurization, a dechlorination, a dearsenicization and a second deoxidation on the deoxygenated raw gas to obtain a conversion raw gas;

[0019] The isothermal shift reactor is used to perform an isothermal shift reaction on the shifted raw gas to convert CO in the shifted raw gas into H 2 and CO 2 ;

[0020] The gas-liquid separation unit includes a water cooling system and a gas-liquid separator, which is used to condense and separate the gas phase product obtained by the isothermal shift reaction, and the obtained crude shift product gas flows out from the upper part of the gas-liquid separator;

[0021] The temperature swing adsorption tower is used to remove CO in the crude shift product gas. 2 .

[0022] Through the above technical solution, the beneficial effects of the present invention are:

[0023] The isothermal conversion reactor of the present invention can effectively and quickly remove the heat of reaction. Compared with the traditional reactor, it has a good protective effect on the isothermal conversion catalyst used, and the use conditions of the catalyst are broadened.

[0024] The present invention sequentially performs a first desulfurization and a first deoxidation on the pretreated electric furnace tail gas, and then sequentially performs a second desulfurization, dechlorination, dearsenification, and a second deoxidation. After these treatments, the sulfide, oxygen, chloride, and arsenic in the electric furnace tail gas can be effectively removed, and the purification effect is remarkable. The obtained conversion raw gas with low sulfide, oxygen, chloride, and arsenic content can meet the use requirements of the isothermal conversion reaction catalyst when performing an isothermal conversion reaction, thereby increasing the source range of the electric furnace tail gas. The treatment method of the present invention can adopt a wide range of electric furnace tail gas raw gas, and is suitable for electric furnace tail gas with a high CO content and complex gas composition. The treatment method provided by the present invention can reduce the emission of carbon dioxide gas, and can achieve efficient utilization of electric furnace tail gas, so that the CO in the electric furnace tail gas has a higher conversion rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a process flow chart for treating electric furnace tail gas in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0026] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0027] A first aspect of the present invention provides a method for treating electric furnace tail gas, the method comprising the following steps:

[0028] S1, performing a first desulfurization on the pretreated electric furnace tail gas to obtain a desulfurized raw gas;

[0029] S2, performing a first deoxygenation on the desulfurized raw gas to obtain a deoxygenated raw gas;

[0030] S3, mixing the deoxygenated raw gas with water vapor for purification treatment to obtain a conversion raw gas; wherein the purification treatment includes a second desulfurization, a dechlorination, a dearsenicization and a second deoxygenation;

[0031] S4, subjecting the conversion feed gas to an isothermal conversion reaction, and condensing and separating the obtained gas phase product into gas and liquid;

[0032] S5. Decarburizing the crude conversion product gas obtained by the gas-liquid separation to obtain a decarburized conversion product gas.

[0033] In the present invention, the electric furnace tail gas mainly contains CO, H 2 , CO 2 、N 2 , O 2 and CH 4 and other components, and also contains chlorides, sulfides and arsenides. According to the present invention, preferably, the content of CO in the electric furnace tail gas is 60-75Vol%, the content of hydrogen is 3-6Vol%, the content of carbon dioxide is 11-16Vol%, the content of nitrogen is 12-16Vol%, the content of methane is 0.01-0.03Vol%, the content of oxygen is 0.02-0.08Vol%, the content of sulfide is less than or equal to 0.15ppm, the content of chloride is less than or equal to 0.15ppm, and the content of arsenide is less than or equal to 0.01ppm; for such electric furnace tail gas with high CO content and complex gas composition, the treatment method provided by the present invention can reduce the emission of carbon dioxide gas, and can achieve efficient utilization of electric furnace tail gas, so that the CO in the electric furnace tail gas has a higher conversion rate.

[0034] The present invention sequentially performs a first desulfurization and a first deoxidation on the pretreated electric furnace tail gas, and then sequentially performs a second desulfurization, a dechlorination, a dearsenification and a second deoxidation. After these treatments, the sulfide, oxygen, chloride and arsenic in the electric furnace tail gas can be effectively removed, and the purification effect is remarkable. The obtained conversion raw gas with low sulfide, oxygen, chloride and arsenic content can meet the use requirements of the isothermal conversion reaction catalyst when performing an isothermal conversion reaction, thereby increasing the source range of the electric furnace tail gas. The treatment method of the present invention can adopt a wide range of electric furnace tail gas raw gas, and is suitable for electric furnace tail gas with high CO content and complex gas composition.

[0035] According to the present invention, preferably, in S1, the pretreatment of the electric furnace exhaust gas after pretreatment refers to removing substances such as oil and dust in the electric furnace exhaust gas.

[0036] According to the present invention, preferably, in S1, the first desulfurization is carried out in the presence of a first desulfurization catalyst; wherein the first desulfurizer is selected from at least one of a COS hydrolysis desulfurizer, zinc oxide, a copper-based desulfurizer and activated carbon, preferably at least one of zinc oxide, a copper-based desulfurizer and activated carbon.

[0037] According to the present invention, preferably, the first desulfurization process comprises: performing medium-temperature desulfurization, low-temperature desulfurization and fine desulfurization in sequence, wherein the medium-temperature desulfurization is performed at a temperature of 175-190°C, and the volume space velocity of the pretreated electric furnace tail gas is 1000-2000h -1 The low-temperature desulfurization is carried out at a temperature of 160-175°C, and the volume space velocity of the electric furnace tail gas after pretreatment is 1000-2000h -1 The fine desulfurization is carried out at a temperature of 175-185°C, and the volume space velocity of the electric furnace tail gas after pretreatment is 1000-1500h -1 Carrying out three-stage desulfurization in sequence under the above conditions can effectively remove the sulfide in the pretreated electric furnace tail gas.

[0038] According to the present invention, preferably, the content of sulfide in the desulfurized raw gas is less than or equal to 0.1 ppm.

[0039] According to the present invention, preferably, in S2, the first deoxidation is carried out in the presence of a first deoxidizer; wherein the first deoxidizer is selected from at least one of activated carbon, a copper-based deoxidizer and a molecular sieve, and is preferably a copper-based deoxidizer. Using a copper-based deoxidizer as the first deoxidizer can make the desulfurized raw gas have a higher deoxidation efficiency.

[0040] According to the present invention, preferably, the first deoxidation conditions include: a temperature of 175-180°C, a volume space velocity of the desulfurized feed gas of 1000-2000h -1The first deoxygenation condition meets this range and can effectively remove oxygen from the desulfurization raw gas.

[0041] According to the present invention, preferably, the oxygen content in the deoxygenated feed gas is less than or equal to 0.05 Vol%.

[0042] According to the present invention, preferably, in S3, the second desulfurization, the dechlorination, the dearsenicification and the second deoxidation are carried out in the presence of a second desulfurization agent, a dechlorination agent, a dearsenicification agent and a second deoxidation agent, respectively.

[0043] in,

[0044] The second desulfurizing agent is selected from a copper-based desulfurizing agent and / or activated carbon, preferably a copper-based desulfurizing agent;

[0045] The dechlorinating agent is selected from at least one of a sodium dechlorinating agent, a calcium dechlorinating agent and a copper dechlorinating agent, preferably a copper dechlorinating agent;

[0046] The dearsenicating agent is selected from a copper-based dearsenicating agent and / or a manganese-based dearsenicating agent, preferably a copper-based dearsenicating agent;

[0047] The second deoxidizer is selected from at least one of activated carbon, copper-based deoxidizer and molecular sieve, and is preferably a copper-based deoxidizer.

[0048] According to the present invention, preferably, the volume ratio of water vapor to the deoxygenated feed gas is (0.4-0.5):1.

[0049] According to the present invention, preferably, the purification treatment conditions include: when the second desulfurization, the dechlorination, the dearsenicization and the second deoxidation are performed, the volume space velocity of the mixed gas of the deoxygenated raw gas and water vapor is 1000-2000h -1 1000-2000h -1 1000-2000h -1 and 1000-1500h -1 The purification treatment conditions satisfy this range, which can further remove sulfides and oxides in the electric furnace tail gas and has good arsenic removal and dechlorination effects.

[0050] According to the present invention, preferably, the sulfide content in the shift feed gas is less than or equal to 0.05 ppm, the oxygen content is less than or equal to 0.02 Vol%, the chloride concentration is less than or equal to 0.01 ppm, and the arsenide concentration is less than or equal to 0.005 ppm. When the contents of sulfide, oxygen, chloride and arsenide in the shift feed gas are reduced to this range, the isothermal shift reaction catalyst can be protected for long-term stable operation.

[0051] According to the present invention, in S4, the conversion raw gas is subjected to an isothermal conversion reaction with water vapor to convert CO in the conversion raw gas into H 2 and CO 2 The gas phase product obtained by isothermal conversion reaction of the conversion raw gas contains CO, CO 2 , H 2 、N 2 and CH 4 Since the gas phase product contains unreacted water vapor, it is necessary to condense and separate the gas-liquid phase to remove the unreacted water vapor, thereby obtaining a crude conversion product gas; and then decarbonize the obtained crude conversion product gas to remove the CO generated by the isothermal conversion reaction. 2 The final decarburized product is H 2 The main component of the conversion product gas.

[0052] According to the present invention, preferably, in S4, the isothermal shift reaction is carried out in the presence of an isothermal shift reaction catalyst; wherein the isothermal shift reaction catalyst is selected from a copper-based medium-temperature shift catalyst and / or a copper-based isothermal shift catalyst, preferably a copper-based isothermal shift catalyst.

[0053] According to the present invention, preferably, the conditions of the isothermal shift reaction include: the volume space velocity of the shift feed gas is 1000-2000h -1 , the bed temperature is 200-240° C. When the isothermal shift reaction conditions meet this range, the conversion rate of CO in the shifted raw gas can be increased, thereby reducing the content of CO in the gas phase product obtained after the isothermal shift reaction.

[0054] In the present invention, the extent of the isothermal shift reaction can be controlled by adjusting the amount of water vapor added in S3.

[0055] According to the present invention, preferably, in S4, the CO content in the gas phase product is 3-4.5 Vol%. The CO in the gas phase product is the unconverted CO in the conversion feed gas. The CO content in the gas phase product is 3-4.5 Vol%, indicating that at the reaction temperature, the chemical reaction equilibrium has been reached and CO cannot be completely converted.

[0056] According to the present invention, preferably, in S5, the decarbonization is performed by temperature swing adsorption (TSA), and the decarbonization method comprises: adsorbing and desorbing the crude conversion product gas by an adsorbent; wherein the adsorbent is selected from at least one of silica gel, activated carbon and molecular sieve, preferably molecular sieve. The temperature swing adsorption (TSA) can effectively adsorb CO in the gas. 2 The CO content in the product gas after decarbonization can be controlled by controlling the degree of adsorption. 2The use of molecular sieve as adsorbent can achieve a good adsorption effect.

[0057] According to the present invention, preferably, the decarbonization conditions include: the adsorption temperature is 20-30°C, and the desorption temperature is 115-125°C.

[0058] According to the present invention, preferably, the CO in the decarbonized conversion product gas 2 The content of is less than or equal to 5Vol%, the content of CO is 5.5-8.5Vol%, H 2 The content is 70.5-73.5Vol%, N 2 The content of CH 4 The content is 0.03-0.04Vol%.

[0059] The second aspect of the present invention provides a device for treating electric furnace tail gas, the device comprising: a pretreatment furnace, a desulfurization unit, a deoxidation furnace, a purification furnace, an isothermal shift reaction furnace, a gas-liquid separation unit and a temperature swing adsorption tower connected in sequence; wherein,

[0060] The pretreatment furnace is used to pretreatment the electric furnace tail gas to remove oil and dust, thereby obtaining the pretreated electric furnace tail gas;

[0061] The desulfurization unit is used to perform a first desulfurization on the pretreated electric furnace tail gas, thereby obtaining a desulfurized raw gas;

[0062] The deoxidation furnace is used to perform a first deoxidation on the desulfurized raw gas to obtain a deoxidized raw gas;

[0063] The purification furnace is filled with a desulfurizer, a dechlorinator, a dearsenicizer and a deoxidizer, which are used to perform a second desulfurization, a dechlorination, a dearsenicization and a second deoxidation on the deoxygenated raw gas to obtain a conversion raw gas;

[0064] The isothermal shift reactor is used to perform an isothermal shift reaction on the shifted raw gas to convert CO in the shifted raw gas into H 2 and CO 2 ;

[0065] The gas-liquid separation unit includes a water cooling system and a gas-liquid separator, which is used to condense and separate the gas phase product obtained by the isothermal shift reaction, and the obtained crude shift product gas flows out from the upper part of the gas-liquid separator;

[0066] The temperature swing adsorption tower is used to remove CO in the crude shift product gas. 2 .

[0067] According to the present invention, preferably, the desulfurization unit comprises a medium-temperature desulfurization furnace, a low-temperature desulfurization furnace and a fine desulfurization furnace which are connected in sequence, and the medium-temperature desulfurization furnace, the low-temperature desulfurization furnace and the fine desulfurization furnace are all filled with a desulfurizer; wherein,

[0068] The temperature in the medium-temperature desulfurization furnace is 175-190°C, the temperature in the low-temperature desulfurization furnace is 160-175°C, and the temperature in the fine desulfurization furnace is 175-185°C.

[0069] According to the present invention, preferably, the deoxidation furnace is filled with a deoxidizer.

[0070] According to the present invention, preferably, the inner wall of the purification furnace is provided with an annular sleeve, and circulating water is filled in the sleeve, and the water flows in a direction of upward inflow and upward outflow.

[0071] According to the present invention, preferably, the purification furnace is filled with a desulfurizing agent, a dechlorinating agent, a dearsenicizing agent and a deoxidizing agent in sequence from top to bottom.

[0072] According to the present invention, preferably, the isothermal shift reaction furnace is filled with an isothermal shift reaction catalyst.

[0073] According to the present invention, preferably, the isothermal shift reactor is a radial bed. The shift gas feed gas enters the cavity near the outer wall of the reactor from the top, passes through the catalyst bed from the outside to the inside, and then leaves the reactor from the bottom of the intermediate tube.

[0074] According to the present invention, preferably, the isothermal shift reactor is provided with a bottom-hanging water jacket, and the jacket is connected to a steam drum for taking away the heat generated by the reaction.

[0075] According to a preferred embodiment of the present invention, Figure 1 The process of treating electric furnace tail gas according to the present invention is described.

[0076] The electric furnace tail gas raw gas passes through a pretreatment furnace to remove oil, dust and other substances to obtain pretreated electric furnace tail gas; the pretreated electric furnace tail gas is then passed through a medium-temperature desulfurization furnace, a low-temperature desulfurization furnace and a fine desulfurization furnace in sequence for desulfurization to obtain a desulfurized raw gas; the desulfurized raw gas is then passed through a deoxidation furnace for deoxidation, and the obtained deoxidized raw gas is mixed with water vapor and passed through a purification furnace for desulfurization, dechlorination, dearsenicization and deoxidation in sequence to obtain a conversion raw gas; the conversion raw gas undergoes an isothermal conversion reaction in an isothermal conversion reaction furnace to convert CO in the conversion raw gas into H 2 and CO 2 The gaseous product flowing out of the isothermal shift reactor is first cooled by a water cooling system, and then separated by gas-liquid separation, and the resulting crude shift product gas flows out from the upper part of the separator; the crude shift product gas passes through a TSA adsorption tower to remove CO in the crude shift product gas. 2 After that, the decarbonized transformed product gas is obtained.

[0077] In the present invention, ppm is expressed as mg / m 3 count.

[0078] The present invention will be described in detail below through examples and comparative examples. In the following examples, unless otherwise specified, all methods are conventional methods; and the reagents and materials used, unless otherwise specified, can be obtained from commercial sources.

[0079] The gas content was determined using a gas chromatograph according to the internal standard method.

[0080] The following examples are used to illustrate the method for treating electric furnace tail gas.

[0081] Example 1

[0082] The electric furnace tail gas raw material gas is the electric furnace tail gas from the ferroalloy plant, in which the hydrogen content is 5.6Vol%, the carbon monoxide content is 63.7Vol%, the carbon dioxide content is 15.2Vol%, the nitrogen content is 15.4Vol%, the methane content is 0.02Vol%, the oxygen content is 0.05Vol%, the sulfide content is 0.15ppm, the chloride content is 0.1ppm, and the arsenide content is 0.005ppm.

[0083] The specific steps for treating electric furnace exhaust gas are as follows:

[0084] (1) Pretreatment and desulfurization: The electric furnace tail gas raw gas is passed through a pretreatment furnace to remove oil, dust and other substances to obtain pretreated electric furnace tail gas; the pretreated electric furnace tail gas is then passed through a medium-temperature desulfurization furnace, a low-temperature desulfurization furnace and a fine desulfurization furnace in sequence, the medium-temperature desulfurization reaction temperature is controlled at 185°C, the low-temperature desulfurization reaction temperature is controlled at 170°C, and the fine desulfurization reaction temperature is controlled at 175°C to obtain a desulfurized raw gas with a sulfide concentration of 0.07 ppm; wherein,

[0085] The medium-temperature desulfurization furnace, low-temperature desulfurization furnace and fine desulfurization furnace are respectively filled with zinc oxide desulfurizer T-308, activated carbon desulfurizer HT-102 and copper-based desulfurizer K-806; the volume space velocity of the pretreated electric furnace tail gas in the medium-temperature desulfurization furnace, low-temperature desulfurization furnace and fine desulfurization furnace is 2000h-1, respectively. -1 、2000h -1 and 1500h -1 ;

[0086] (2) Deoxidation: The desulfurized raw gas passes through a deoxidation furnace, the reaction temperature of which is controlled at 180°C, to obtain a deoxidized raw gas having an oxygen content of 0.035 Vol%. The deoxidation furnace is filled with a copper-based deoxidizer Z-30, and the volumetric space velocity of the desulfurized raw gas is 2000 h -1 ;

[0087] (3) Purification: The water vapor feed is mixed with the deoxygenated raw gas in a volume ratio of 0.4:1, and then passed through a purification furnace for desulfurization, dechlorination, dearsenicization and deoxygenation in sequence to obtain a conversion raw gas with a sulfide concentration of 0.03 ppm, an oxygen concentration of 0%, a chloride concentration of 0.005 ppm and an arsenide concentration of 0 ppm; wherein:

[0088] The purification furnace is filled with copper-based desulfurizer K-102, copper-based dechlorinator JX-5, copper-based dearsenicizing agent 9801 and copper-based deoxidizer AZ-1 from top to bottom; the volume space velocity of the mixed gas of deoxidized raw gas and water vapor is 2000h -1 、2000h -1 、2000h -1 and 1500h -1 ;

[0089] (4) Isothermal conversion and gas-liquid separation: After the conversion raw gas undergoes an isothermal conversion reaction, the gaseous product flowing out of the isothermal conversion reactor is first cooled by a water cooling system and then separated by gas-liquid separation. The resulting crude conversion product gas flows out from the upper part of the separator; wherein the CO content at the outlet of the isothermal conversion reactor is 3.2 Vol%; wherein,

[0090] The isothermal shift reactor is filled with copper-based isothermal shift reaction catalyst B209, and the volume space velocity of the shift feed gas is 2000h -1 , the bed temperature is 220℃;

[0091] (5) Decarbonization: The adsorption temperature of the TSA adsorption tower is controlled at 25°C and the desorption temperature is controlled at 120°C. After decarbonization, the crude conversion product gas is decarbonized to obtain CO 2 Content 4.5Vol%, CO content 7.4Vol%, H 2 Content 73.5Vol%N 2 Content 14.5Vol%CH 4 The decarbonized conversion product gas has a content of 0.03 Vol%; wherein the TSA adsorption tower is filled with molecular sieve adsorbent 13XAPG.

[0092] Example 2

[0093] The electric furnace tail gas raw material gas is the electric furnace tail gas from the ferroalloy plant, in which the hydrogen content is 4.6Vol%, the carbon monoxide content is 66.7Vol%, the carbon dioxide content is 13.2Vol%, the nitrogen content is 15.4Vol%, the methane content is 0.025Vol%, the oxygen content is 0.03Vol%, the sulfide content is 0.14ppm, the chloride content is 0.1ppm, and the arsenide content is 0.002ppm.

[0094] The specific steps for treating electric furnace exhaust gas are as follows:

[0095] (1) Pretreatment and desulfurization: The electric furnace tail gas raw gas passes through a pretreatment furnace to remove oil, dust and other substances to obtain pretreated electric furnace tail gas; the pretreated electric furnace tail gas then passes through a medium-temperature desulfurization furnace, a low-temperature desulfurization furnace and a fine desulfurization furnace in sequence, the medium-temperature desulfurization reaction temperature is controlled at 190°C, the low-temperature desulfurization reaction temperature is controlled at 175°C, and the fine desulfurization reaction temperature is controlled at 180°C to obtain a desulfurized raw gas with a sulfide concentration of 0.06 ppm; wherein,

[0096] The medium-temperature desulfurization furnace, low-temperature desulfurization furnace and fine desulfurization furnace are respectively filled with zinc oxide desulfurizer K-101, activated carbon desulfurizer HT-102 and copper-based desulfurizer K-806; the volume space velocity of the pretreated electric furnace tail gas in the medium-temperature desulfurization furnace, low-temperature desulfurization furnace and fine desulfurization furnace is 1500h-1, respectively. -1 、1500h -1 and 1500h -1 ;

[0097] (2) Deoxidation: The desulfurized raw gas passes through a deoxidation furnace, the reaction temperature of which is controlled at 175°C, to obtain a deoxidized raw gas with an oxygen concentration of 0.02 Vol%. The deoxidation furnace is filled with a copper-based deoxidizer Z-30, and the volumetric space velocity of the desulfurized raw gas is 1500 h -1 ;

[0098] (3) Purification: The water vapor feed is mixed with the deoxygenated raw gas in a volume ratio of 0.45:1, and then passed through a purification furnace for desulfurization, dechlorination, dearsenicization and deoxygenation in sequence to obtain a conversion raw gas with a sulfide concentration of 0.02 ppm, an oxygen concentration of 0%, a chloride concentration of 0.002 ppm and an arsenic content of 0 ppm; wherein:

[0099] The purification furnace is filled with copper-based desulfurizer K-102, copper-based dechlorinator JX-5, copper-based dearsenicizing agent 9803 and copper-based deoxidizing agent AZ-1 from top to bottom; the volume space velocity of the mixed gas of deoxidized raw gas and water vapor is 1500h -1 、1500h -1 、1500h -1 and 1200h -1 ;

[0100] (4) Isothermal conversion and gas-liquid separation: After the conversion raw gas undergoes an isothermal conversion reaction, the gaseous product flowing out of the isothermal conversion reactor is first cooled by a water cooling system and then separated by gas and liquid. The resulting crude conversion product gas flows out from the upper part of the separator; wherein the CO content at the outlet of the isothermal conversion reactor is 4.1 Vol%; wherein,

[0101] The isothermal shift reactor is filled with copper-based isothermal shift reaction catalyst B210, and the volume space velocity of the shift feed gas is 1500h -1, the bed temperature is 200℃;

[0102] (5) Decarbonization: The adsorption temperature of the TSA adsorption tower is controlled at 20°C and the desorption temperature is controlled at 115°C. The crude conversion product gas passes through the TSA adsorption tower to obtain CO 2 Content 4.4Vol%, CO content 7.2Vol%, H 2 Content 73.5Vol%N 2 Content 14.5Vol%CH 4 The decarbonized conversion product gas has a content of 0.03 Vol%; wherein the TSA adsorption tower is filled with molecular sieve adsorbent 13XAPG.

[0103] Example 3

[0104] The electric furnace tail gas raw material gas is the electric furnace tail gas from the ferroalloy plant, in which the hydrogen content is 4.4Vol%, the carbon monoxide content is 67.8Vol%, the carbon dioxide content is 12.8Vol%, the nitrogen content is 14.9Vol%, the methane content is 0.025Vol%, the oxygen content is 0.04Vol%, the sulfide content is 0.12ppm, the chloride content is 0.06ppm, and the arsenide content is 0.004ppm.

[0105] The specific steps for treating electric furnace exhaust gas are as follows:

[0106] (1) Pretreatment and desulfurization: The electric furnace tail gas raw gas passes through a pretreatment furnace to remove oil, dust and other substances to obtain pretreated electric furnace tail gas; the pretreated electric furnace tail gas then passes through a medium-temperature desulfurization furnace, a low-temperature desulfurization furnace and a fine desulfurization furnace in sequence, the medium-temperature desulfurization reaction temperature is controlled at 185°C, the low-temperature desulfurization reaction temperature is controlled at 170°C, and the fine desulfurization reaction temperature is controlled at 180°C to obtain a desulfurized raw gas with a sulfide concentration of 0.04 ppm; wherein,

[0107] The medium-temperature desulfurization furnace, low-temperature desulfurization furnace and fine desulfurization furnace are respectively filled with zinc oxide desulfurizer K-101, copper-based desulfurizer K-806 and activated carbon desulfurizer T-205; the volume space velocity of the pretreated electric furnace tail gas in the medium-temperature desulfurization furnace, low-temperature desulfurization furnace and fine desulfurization furnace is 1200h-1, respectively. -1 、1300h -1 and 1500h -1 ;

[0108] (2) Deoxidation: The desulfurized raw gas passes through a deoxidation furnace, the reaction temperature of which is controlled at 175°C, to obtain a deoxidized raw gas having an oxygen content of 0.01 Vol%. The deoxidation furnace is filled with a copper-based deoxidizer Z-30, and the volumetric space velocity of the desulfurized raw gas is 1500 h -1 ;

[0109] (3) Purification: The water vapor feed is mixed with the deoxygenated raw gas in a volume ratio of 0.5:1 and passed through a purification furnace for desulfurization, dechlorination, dearsenicization and deoxygenation in sequence to obtain a conversion raw gas with a sulfide concentration of 0.02 ppm, an oxygen concentration of 0%, a chloride concentration of 0.001 ppm and an arsenic content of 0 ppm; wherein,

[0110] The purification furnace is filled with copper-based desulfurizer K-102, copper-based dechlorinator JX-5, copper-based dearsenicizing agent 9803 and copper-based deoxidizer AZ-1 from top to bottom; the volume space velocity of the mixed gas of deoxidized raw gas and water vapor is 1000h -1 ;

[0111] (4) Isothermal conversion and gas-liquid separation: After the conversion raw gas undergoes an isothermal conversion reaction, the gaseous product flowing out of the isothermal conversion reactor is first cooled by a water cooling system and then separated by gas-liquid separation. The resulting crude conversion product gas flows out from the upper part of the separator; wherein the CO content at the outlet of the isothermal conversion reactor is 3.5 Vol%; wherein,

[0112] The isothermal shift reactor is filled with copper-based isothermal shift reaction catalyst B210, and the volume space velocity of the shift feed gas is 1200h -1 , the bed temperature is 240℃;

[0113] (5) Decarbonization: The adsorption temperature of the TSA adsorption tower is controlled at 30°C and the desorption temperature is controlled at 125°C. The crude conversion product gas passes through the TSA adsorption tower to obtain CO 2 Content 4.5Vol%, CO content 8.2Vol%, H 2 Content 72.7Vol%N 2 Content 14.5Vol%CH 4 The decarbonized conversion product gas has a content of 0.03 Vol%; wherein the TSA adsorption tower is filled with molecular sieve adsorbent 13XAPG.

[0114] Example 4

[0115] The electric furnace tail gas was treated according to the method of Example 1, except that in step (1), the desulfurization was not carried out through the medium-temperature desulfurization furnace, and a desulfurized raw gas with a sulfide concentration of 0.12 ppm was obtained; further, a deoxygenated raw gas with an oxygen content of 0.04 Vol% was obtained; a shift raw gas with a sulfide concentration of 0.065 ppm, an oxygen concentration of 0%, a chloride concentration of 0.005 ppm and an arsenic chloride concentration of 0.005 ppm was obtained; the CO content at the outlet of the isothermal shift furnace was 5.5 Vol%; and finally, CO 2 The content is 4.5Vol%, CO content is 10.4Vol%, H 2 The content is 69.5Vol%, N 2 The content is 14.5Vol%, CH4 The decarburized conversion product gas has a content of 0.03 Vol%.

[0116] Example 5

[0117] The electric furnace tail gas was treated according to the method of Example 1, except that in step (1), the medium-temperature desulfurization reaction temperature was controlled at 195°C, the low-temperature desulfurization reaction temperature was controlled at 155°C, and the fine desulfurization reaction temperature was controlled at 170°C, to obtain a desulfurized raw gas with a sulfide concentration of 0.19ppm; further obtain a deoxygenated raw gas with an oxygen content of 0Vol%; obtain a conversion raw gas with a sulfide concentration of 0.07ppm, an oxygen concentration of 0%, a chloride concentration of 0.004ppm and an arsenide concentration of 0.004ppm; the CO content at the outlet of the isothermal conversion furnace was 6.9Vol%; and finally obtain CO 2 The content is 4.3Vol%, CO content is 12.5Vol%, H 2 The content is 68.2Vol%, N 2 The content is 14.9 Vol%, CH 4 The amount of decarburized conversion product gas is 0.03Vol%.

[0118] Example 6

[0119] The electric furnace tail gas was treated according to the method of Example 1, except that in step (2), the reaction temperature of the deoxidation furnace was controlled at 185° C. to obtain a deoxidized raw gas with an oxygen content of 0.085 Vol%; a conversion raw gas with a sulfide concentration of 0.09 ppm, an oxygen content of 0.04 Vol%, a chloride concentration of 0.004 ppm and an arsenide concentration of 0.004 ppm was obtained; the CO content at the outlet of the isothermal conversion furnace was 5.5 Vol%; and finally CO 2 The content is 4.5Vol%, CO content is 11.5Vol%, H 2 The content is 69.1Vol%, N 2 The content is 14.8Vol%, CH 4 The decarburized conversion product gas has a content of 0.04Vol%.

[0120] Example 7

[0121] The electric furnace tail gas is treated according to the method of Example 1, except that the composition of the electric furnace tail gas raw gas is different. Specifically, the carbon monoxide content is 60.7Vol%, the hydrogen content is 4.6Vol%, the carbon dioxide content is 20.2Vol%, the nitrogen content is 14.4Vol%, the methane content is 0.02Vol%, the oxygen content is 0.04Vol%, the sulfide content is 0.14ppm, the chloride content is 0.1ppm, and the arsenide content is 0.005ppm. A desulfurized raw gas with a sulfide concentration of 0.06ppm is obtained; and a deoxygenated raw gas with an oxygen concentration of 0.01Vol% is obtained; a conversion raw gas with a sulfide concentration of 0.05ppm, an oxygen content of 0.005%, a chloride concentration of 0.004ppm and an arsenide concentration of 0.004ppm is obtained; the CO content at the outlet of the isothermal conversion furnace is 6Vol%; and finally CO 2 The content is 5.9Vol%, CO content is 10.5Vol%, H 2 The content is 68.8Vol%, N 2 The content is 14.7 Vol%, CH 4 The decarburized conversion product gas has a content of 0.03 Vol%.

[0122] Example 8

[0123] The tail gas of the electric furnace was treated according to the method of Example 1, except that the bed temperature of the isothermal conversion reactor was 250°C. The CO content at the outlet of the isothermal conversion reactor was 4.9 Vol%. 2 The content is 4.4Vol%, CO content is 10.5Vol%, H 2 The content is 70.2Vol%, N 2 The content is 14.5Vol%, CH 4 The decarburized conversion product gas has a content of 0.03 Vol%.

[0124] Example 9

[0125] The tail gas of the electric furnace was treated according to the method of Example 1, except that the zinc oxide desulfurizer in the medium-temperature desulfurization furnace was replaced by COS hydrolysis desulfurizer T503. A desulfurized raw gas with a sulfide concentration of 0.23ppm was obtained; a deoxygenated raw gas with an oxygen content of 0.035Vol% was obtained; a shift raw gas with a sulfide concentration of 0.13ppm, an oxygen concentration of 0%, a chloride concentration of 0.005ppm and an arsenic chloride concentration of 0ppm was obtained; the CO content at the outlet of the isothermal shift furnace was 5.8Vol%; and finally CO 2 The content is 4.5Vol%, CO content is 14.9Vol%, H 2 The content is 64.5Vol%, N 2The content is 15.9 Vol%, CH 4 The decarburized conversion product gas has a content of 0.03 Vol%.

[0126] Example 10

[0127] The tail gas of the electric furnace was treated according to the method of Example 1, except that the copper-based deoxidizer in the deoxidation furnace was replaced by activated carbon deoxidizer T3093. A deoxidized raw gas with an oxygen content of 0.12 Vol% was obtained; a conversion raw gas with a sulfide concentration of 0.03 ppm, an oxygen concentration of 0.07 Vol%, a chloride concentration of 0.005 ppm and an arsenic chloride concentration of 0 ppm was obtained; the CO content at the outlet of the isothermal conversion furnace was 5.9 Vol%; and finally CO 2 The content is 4.5Vol%, CO content is 14.4Vol%, H 2 The content is 66.1Vol%, N 2 The content is 14.9 Vol%, CH 4 The decarburized conversion product gas has a content of 0.02Vol%.

[0128] Embodiment 11

[0129] The tail gas of the electric furnace was treated according to the method of Example 1, except that the activated carbon desulfurizer T205, sodium dechlorinator F-101, manganese dearsenicizer JT-2 and molecular sieve deoxidizer F-02 were sequentially loaded in the purification furnace from top to bottom. The conversion raw gas with a sulfide concentration of 0.11ppm, an oxygen concentration of 0.05%, a chloride concentration of 0.03ppm and an arsenic chloride concentration of 0ppm was obtained; the CO content at the outlet of the isothermal conversion furnace was 6.2Vol%; and CO was finally obtained. 2 The content is 4.9Vol%, CO content is 13.2Vol%, H 2 The content is 67.2Vol%, N 2 The content is 14.6Vol%, CH 4 The decarburized conversion product gas has a content of 0.03 Vol%.

[0130] Example 12

[0131] The tail gas from the electric furnace was treated according to the method of Example 1, except that the molecular sieve adsorbent in the TSA adsorption tower was replaced by activated carbon adsorbent HT-111. 2 The content is 5.3Vol%, CO content is 7.4Vol%, H 2 The content is 71.5Vol%, N 2 The content is 15.5Vol%, CH 4 The decarburized conversion product gas has a content of 0.02Vol%.

[0132] Embodiment 13

[0133] The tail gas from the electric furnace was treated according to the method of Example 1, except that the adsorption temperature of the TSA adsorption tower was controlled at 35°C and the desorption temperature was controlled at 130°C during decarbonization. 2 The content is 5.6Vol%, CO content is 7.4Vol%, H 2 The content is 72.4Vol%, N 2 The content is 14.5Vol%, CH 4 The decarburized conversion product gas has a content of 0.03 Vol%.

[0134] Comparative Example 1

[0135] The electric furnace tail gas is treated according to the method of Example 1, except that the pre-treated electric furnace tail gas is first deoxidized to obtain deoxidized raw gas, and then the deoxidized raw gas is first desulfurized to obtain desulfurized raw gas. The deoxidized raw gas with an oxygen content of 0.09 Vol% is obtained, and then the desulfurized raw gas with a sulfide concentration of 0.28 ppm is obtained; the conversion raw gas with a sulfide concentration of 0.12 ppm, an oxygen concentration of 0.04%, a chloride concentration of 0.09 ppm and an arsenide concentration of 0.01 ppm is obtained; the CO content at the outlet of the isothermal conversion furnace is 8.5 Vol%; and finally CO 2 The concentration is 4.9 Vol%, CO content is 19.5 Vol%, H 2 The content is 59Vol%, N 2 The content is 14.5Vol%, CH 4 The decarburized conversion product gas has a content of 0.04Vol%.

[0136] It can be seen from the results of the examples and comparative examples that the CO in the decarbonized conversion product gas obtained in Examples 1-13 is 2 The content of H is less than or equal to 6Vol%, the content of CO is less than 15Vol%, 2 The content is above 64 Vol%, indicating that the method of the present invention is used to treat electric furnace exhaust gas, which can reduce the emission of carbon dioxide gas and realize the efficient utilization of electric furnace exhaust gas, so that the CO in the electric furnace exhaust gas has a higher conversion rate.

[0137] In addition, the desulfurization in Example 4 was not conducted through a medium-temperature desulfurization furnace, the medium-temperature desulfurization reaction temperature was increased in Example 5, and the type of desulfurizer in the medium-temperature desulfurization furnace was changed in Example 9. Compared with Example 1, the sulfide concentration in the conversion raw gas obtained in Examples 4, 5, and 9 was higher, and the CO content in the conversion product gas after decarbonization was higher. 2The content is low; Example 6 increases the reaction temperature of the deoxidation furnace, and Example 10 changes the type of deoxidizer in the deoxidation furnace. Compared with Example 1, the concentrations of sulfide and oxygen in the conversion raw gas obtained in Example 6 are higher, and the concentration of oxygen in the conversion raw gas obtained in Example 10 is higher. Finally, the CO content in the conversion product gas after decarburization obtained in Example 6 and Example 10 is higher, and H 2 Example 7 changes the composition of the raw gas of the electric furnace tail gas, and the carbon dioxide content in the raw gas is relatively high. Example 8 increases the bed temperature of the isothermal conversion reactor. Compared with Example 1, the CO content in the decarbonized conversion product gas finally obtained in Example 7 and Example 8 is relatively high, and H 2 Example 11 changes the types of desulfurizer, dechlorinator, dearsenicizer and deoxidizer in the purification furnace. Compared with Example 1, the concentrations of sulfide, oxygen and chloride in the converted raw gas are increased, and the CO content in the converted product gas after decarbonization is higher. 2 Example 12 changed the type of adsorbent in the TSA adsorption tower, and Example 13 changed the adsorption and desorption temperatures. Compared with Example 1, the CO content of the final decarbonized conversion product gas was 2 The above results show that the first desulfurization method, desulfurization conditions and type of desulfurizer, the first deoxidation conditions and type of deoxidizer, the types of desulfurizer, dechlorinator, dearsenicizer and deoxidizer during purification have a great influence on the composition of the conversion raw gas, thereby affecting the CO conversion rate; the composition of the electric furnace tail gas raw gas and the isothermal conversion reaction conditions will also affect the CO conversion rate; and the type and conditions of the adsorbent during decarbonization will affect the emission of carbon dioxide gas.

[0138] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for treating electric furnace tail gas, characterized in that: The method comprises the following steps: S1, performing a first desulfurization on the pretreated electric furnace tail gas to obtain a desulfurized raw gas; S2, performing a first deoxygenation on the desulfurized raw gas to obtain a deoxygenated raw gas; S3, mixing the deoxygenated raw gas with water vapor for purification treatment to obtain a conversion raw gas; wherein the purification treatment includes a second desulfurization, a dechlorination, a dearsenicization and a second deoxygenation; S4, subjecting the conversion feed gas to an isothermal conversion reaction, and condensing and separating the obtained gas phase product into gas and liquid; S5. Decarbonize the crude conversion product gas obtained by the gas-liquid separation to obtain a decarbonized conversion product gas.

2. The method according to claim 1, characterized in that The CO content in the electric furnace tail gas is 60-75Vol%, the hydrogen content is 3-6Vol%, the carbon dioxide content is 11-16Vol%, the nitrogen content is 12-16Vol%, the methane content is 0.01-0.03Vol%, the oxygen content is 0.02-0.08Vol%, the sulfide content is less than or equal to 0.15ppm, the chloride content is less than or equal to 0.15ppm, and the arsenide content is less than or equal to 0.01ppm.

3. The method according to claim 1 or 2, characterized in that: In S1, the first desulfurization is carried out in the presence of a first desulfurizing agent; wherein the first desulfurizing agent is selected from at least one of a COS hydrolysis desulfurizing agent, zinc oxide, a copper-based desulfurizing agent and activated carbon, preferably at least one of zinc oxide, a copper-based desulfurizing agent and activated carbon; Preferably, the first desulfurization process comprises: medium-temperature desulfurization, low-temperature desulfurization and fine desulfurization in sequence, wherein the medium-temperature desulfurization is carried out at a temperature of 175-190°C and a volume space velocity of 1000-2000h -1 The low-temperature desulfurization is carried out at a temperature of 160-175°C and a volume space velocity of 1000-2000h after pretreatment of the electric furnace tail gas. -1 The fine desulfurization is carried out at a temperature of 175-185°C and a volume space velocity of 1000-1500h after pretreatment of the electric furnace tail gas. -1 Next proceed; Preferably, the content of sulfide in the desulfurized raw gas is less than or equal to 0.1 ppm.

4. The method according to any one of claims 1 to 3, characterized in that: In S2, the first deoxidation is performed in the presence of a first deoxidizer; wherein the first deoxidizer is selected from at least one of activated carbon, a copper-based deoxidizer and a molecular sieve, and is preferably a copper-based deoxidizer; Preferably, the first deoxygenation conditions include: a temperature of 175-180°C, a volume space velocity of the desulfurized feed gas of 1000-2000h -1 ; Preferably, the oxygen content in the deoxygenated feed gas is less than or equal to 0.05 Vol%.

5. The method according to any one of claims 1 to 4, characterized in that: In S3, the second desulfurization, the dechlorination, the dearsenification and the second deoxidation are carried out in the presence of a second desulfurization agent, a dechlorination agent, a dearsenification agent and a second deoxidation agent, respectively; wherein, The second desulfurizing agent is selected from a copper-based desulfurizing agent and / or activated carbon, preferably a copper-based desulfurizing agent; The dechlorinating agent is selected from at least one of a sodium dechlorinating agent, a calcium dechlorinating agent and a copper dechlorinating agent, preferably a copper dechlorinating agent; The dearsenicating agent is selected from a copper-based dearsenicating agent and / or a manganese-based dearsenicating agent, preferably a copper-based dearsenicating agent; The second deoxidizer is selected from at least one of activated carbon, copper-based deoxidizer and molecular sieve, preferably a copper-based deoxidizer; Preferably, the volume ratio of water vapor to the deoxygenated feed gas is (0.4-0.5):1; Preferably, the purification treatment conditions include: when performing the second desulfurization, the dechlorination, the dearsenicization and the second deoxidation, the volume space velocity of the mixed gas of the deoxygenated raw gas and water vapor is 1000-2000h -1 1000-2000h -1 1000-2000h -1 and 1000-1500h -1 ; Preferably, the concentration of sulfide in the conversion raw gas is less than or equal to 0.05 ppm, the content of oxygen is less than or equal to 0.02 Vol%, the concentration of chloride is less than or equal to 0.01 ppm, and the concentration of arsenide is less than or equal to 0.005 ppm.

6. The method according to any one of claims 1 to 5, characterized in that: In S4, the isothermal shift reaction is carried out in the presence of an isothermal shift reaction catalyst; wherein the catalyst is selected from a copper-based medium-temperature shift catalyst and / or a copper-based isothermal shift catalyst, preferably a copper-based isothermal shift catalyst; Preferably, the conditions of the isothermal shift reaction include: the volume space velocity of the shift feed gas is 1000-2000h -1 , bed temperature is 200-240℃; Preferably, in S4, the CO content in the gas phase product is 3-4.5 Vol%.

7. The method according to any one of claims 1 to 6, characterized in that: In S5, the decarbonization method comprises: adsorbing and desorbing the crude shift product gas with an adsorbent; wherein the adsorbent is selected from at least one of silica gel, activated carbon and molecular sieve, preferably molecular sieve; Preferably, the decarbonization conditions include: the adsorption temperature is 20-30°C, and the desorption temperature is 115-125°C; Preferably, the content of CO2 in the conversion product gas after decarbonization is less than or equal to 5Vol%, the content of CO is 5.5-8.5Vol%, the content of H2 is 70.5-73.5Vol%, the content of N2 is 14.5-16Vol%, and the content of CH4 is 0.03-0.04Vol%.

8. A device for treating electric furnace tail gas, characterized in that: The device comprises: a pretreatment furnace, a desulfurization unit, a deoxidation furnace, a purification furnace, an isothermal shift reaction furnace, a gas-liquid separation unit and a temperature-swing adsorption tower which are connected in sequence; wherein, The pretreatment furnace is used to pretreat the electric furnace tail gas to remove oil and dust, thereby obtaining the pretreated electric furnace tail gas; The desulfurization unit is used to perform a first desulfurization on the pretreated electric furnace tail gas, thereby obtaining a desulfurized raw gas; The deoxidation furnace is used to perform a first deoxidation on the desulfurized raw gas to obtain a deoxidized raw gas; The purification furnace is filled with a desulfurizer, a dechlorinator, a dearsenicizer and a deoxidizer, which are used to perform a second desulfurization, a dechlorination, a dearsenicization and a second deoxidation on the deoxygenated raw gas to obtain a conversion raw gas; The isothermal shift reactor is used to perform an isothermal shift reaction on the shifted raw gas to convert CO in the shifted raw gas into H2 and CO2; The gas-liquid separation unit includes a water cooling system and a gas-liquid separator, which is used to condense and separate the gas phase product obtained by the isothermal shift reaction; The temperature swing adsorption tower is used to remove CO2 from the crude conversion product gas.

9. The device according to claim 8, characterized in that The desulfurization unit comprises a medium-temperature desulfurization furnace, a low-temperature desulfurization furnace and a fine desulfurization furnace which are connected in sequence; wherein, The temperature in the medium-temperature desulfurization furnace is 175-190°C, the temperature in the low-temperature desulfurization furnace is 160-175°C, and the temperature in the fine desulfurization furnace is 175-185°C.

10. The device according to claim 8 or 9, characterized in that The inner wall of the purification furnace is provided with an annular sleeve, and circulating water is filled in the tube; Preferably, the purification furnace is filled with a desulfurizing agent, a dechlorinating agent, a dearsenicizing agent and a deoxidizing agent in sequence from top to bottom.

11. The device according to any one of claims 8 to 10, characterized in that: The isothermal shift reaction furnace is filled with an isothermal shift reaction catalyst; Preferably, the isothermal shift reactor is a radial bed; Preferably, the isothermal shift reactor is provided with a bottom-hanging water jacket, which is connected to a steam drum to remove heat generated by the reaction.

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