CN103920365B - Nitrogen in variable-frequency variable-voltage absorption recovery roasting pyrite furnace gas and the method for sulfur dioxide - Google Patents

Abstract

The invention discloses a method for recovering nitrogen and sulfur dioxide in the furnace gas of roasted pyrite ore by frequency conversion and pressure conversion adsorption. Refined sulfuric acid furnace gas filter made of ethylene to remove dust particles and rust; then through the fine dehydration tank for deep fine dehydration, deoxidation and decarbonation, and then use the frequency conversion pressure swing adsorption method to achieve the separation of N ₂ and SO ₂ , and then pass through Compression or cooling, gas-liquid separation to obtain liquid SO ₂ , bottle the separated nitrogen and liquid SO ₂ for industrial use; SO2 that has not been liquefied and separated enters the cycle of compression or cooling, gas-liquid separation, and the SO in it _2. Continuous separation; the present invention realizes the comprehensive utilization and zero discharge of mixed furnace gas containing a large amount of nitrogen and sulfur dioxide in roasted pyrite, and the obtained liquid sulfur dioxide has high purity, and the process is green, safe, energy-saving, zero-emission and low in cost .

Description

Method for recovery of nitrogen and sulfur dioxide in roasting pyrite furnace gas by frequency conversion and pressure swing adsorption

technical field

The invention relates to a method for recovering nitrogen and sulfur dioxide in roasting pyrite furnace gas by frequency conversion and pressure swing adsorption.

Background technique

Liquid sulfur dioxide is a colorless, transparent liquid with a pungent odor. Its gasification is strong. When the concentration of sulfur dioxide in the air reaches 0.04% to 0.05%, it will be poisoned to the human body if it is inhaled, and it will irritate the breath and eyes. Liquid sulfur dioxide is widely used and is an important chemical raw material, which can be used to produce synthetic fibers (mainly nylon), detergents, rubber additives, hydrosulfite (sodium dithionite), plastics, dyes, medicines, lubricating oils and saccharin etc. It can also be used as refrigerant, bleaching powder, fire extinguishing agent and disinfectant, etc. In recent years, with the development of my country's modern industry, the demand for liquid sulfur dioxide is increasing day by day, the output of liquid sulfur dioxide is increasing year by year, and the market demand is becoming increasingly strong.

In the furnace gas or tail gas of roasting pyrite, sulfur dioxide accounts for about 7% to 12%, sulfur trioxide accounts for 0.05% to 0.4%, and traces of sublimated sulfur, oxygen and acid mist, etc., and the rest is nitrogen. Sulfur dioxide is a colorless gas at normal temperature and pressure, with a strong pungent odor. When discharged into the atmosphere, it will be oxidized into sulfur trioxide, which will combine with water vapor to form acid mist, which will corrode related iron metal equipment, pipelines and instruments, and shorten their service life. Therefore, it is particularly urgent to remove or recover the sulfur dioxide in the furnace gas or tail gas of roasting pyrite, and make use of it to turn harm into treasure!

At present, there are mainly ammonia-acid method, sodium citrate absorption method, water absorption method, partial condensation method and Weissman-Lord method in the industry at home and abroad to recover sulfur dioxide from roasting pyrite furnace gas or tail gas to produce liquid sulfur dioxide. etc. These methods all first absorb sulfur dioxide in flue gas or furnace gas with absorbents such as organic amines, water or ammonia that are easy to absorb sulfur dioxide, and then desorb to obtain high-concentration sulfur dioxide; then high-concentration sulfur dioxide is obtained by pressurization or freezing. sulfur dioxide. These technologies are more or less limited by technical reliability, economic rationality, regional sources of reagents, industry production characteristics and environmental protection requirements. For example, the ammonia-acid method currently widely used in China uses liquid ammonia or ammonia water as an absorbent, which has high absorption efficiency and thorough desulfurization, but the process is complicated, equipment investment is large, and operating costs are high, and the source of ammonia is restricted by region. The calcium method is to use lime water or lime milk to wash the flue gas containing sulfur dioxide, form calcium sulfite precipitate, and generate calcium sulfate. This method has mature technology and low production cost, but the absorption rate is slow, the absorption capacity is small, the practical application value of the by-product calcium sulfate is not great, and the output slag is large, which leads to serious scaling of equipment and pipelines. The sodium method uses alkaline substances such as sodium citrate, sodium carbonate or sodium hydroxide to absorb sulfur dioxide-containing flue gas to generate sodium sulfite or sodium bisulfite solution. The advantages are large absorption capacity, fast absorption rate, high desulfurization efficiency, and simple equipment , Easy to operate and not easy to scale. The disadvantage is that the raw material sodium alkali is more expensive and the production cost is high. The common problems of the above methods are: ① The investment cost of the desulfurization equipment project is high. ② Subsequent treatment of by-products after desulfurization is difficult. ③The requirements of environmental protection cannot be met or the operating cost of environmental protection is high.

Nitrogen is a colorless, odorless and odorless gas, non-toxic, with good stability and a very low boiling point. It is widely used in petroleum exploration, chemical safety protection, welding metal protection, bulb filling, breeding, fruit storage and transportation , preservation, fire extinguishing, medicine, pharmaceuticals, etc. It accounts for 78.12% (volume fraction) of the total atmosphere and is the main component of air.

At present, the main methods for separating and recovering nitrogen from air at home and abroad are: cryogenic rectification, pressure swing adsorption, membrane separation and chemical adsorption, each with its own advantages and disadvantages.

Among them, the mechanism of cryogenic rectification is to compress and liquefy the air, and according to the difference of the boiling point of each component, rectify and separate through the rectifying tower to obtain the desired product. For large-scale industrial production of oxygen and nitrogen, the low-temperature rectification method is the most economical method, which occupies a firm dominant position in the air separation method; at the same time, the cold loss can be as low as possible, and the required heat is as little as possible. The cryogenic method for air separation mainly includes two-tower process for simultaneous separation of oxygen and nitrogen and three-tower process for simultaneous production of oxygen, nitrogen and argon. The development trend of the cryogenic method is: (1) large-scale, up to 220,000m ³ /h nitrogen; (2) the use of structured packing, the advantages of large flow, small resistance, large operating flexibility, and high efficiency; (3) comparable to other processes Combined, reduce energy consumption and improve the overall total efficiency. The operation of equipment for cryogenic rectification is complicated, the investment is large, and the energy consumption is large.

Oxygen production by pressure swing adsorption method is to separate oxygen and nitrogen by using the characteristic that the adsorption affinity of zeolite molecular sieve to nitrogen is higher than that to oxygen, or to use the diffusion rate of oxygen in the narrow gap of carbon molecule micropore system to be greater than that of nitrogen, in Separation of oxygen and nitrogen away from equilibrium conditions. The production of oxygen and nitrogen by pressure swing adsorption is carried out at normal temperature. The process includes pressure adsorption, normal pressure desorption, normal pressure adsorption and vacuum desorption. The adsorption amount of the adsorbent to the gas increases with the increase of the pressure, and decreases with the decrease of the pressure. During the process of reducing the pressure, the adsorbed gas is released to regenerate the adsorbent. Pressure swing adsorption is limited by two key technologies: one is the development of high-efficiency adsorbents; the other is the improvement of the reliability and flexibility of frequent switching valves. At present, most of the large-scale PSA devices are for the separation of CO2 from the raw material gas of hydrogen production and ammonia synthesis in the iron and steel industry. In terms of air separation, at present, most of the separation capacity are devices under 6000m ³ /h.

Membrane separation method has the advantages of strong adaptability, high efficiency, short process, simple equipment, no moving parts, convenient operation, small footprint, low investment, energy saving, advanced technology, and low energy consumption. It has broad development prospects and application fields. But the cost of the membrane is high and the reliability is low!

The chemical absorption method refers to that the high-temperature alkaline mixed molten salt can absorb oxygen in the air under the action of a catalyst, and then desorb and release oxygen through decompression or temperature rise. The oxygen released from the molten salt has a purity of 98% to 99.5%. This method has great prospects for large-scale air separation oxygen production. The oxygen output is above 500t/d. Compared with the traditional low-temperature oxygen production, the efficiency can be increased by about 50%. At the same time, a large amount of high-temperature water vapor can also be produced.

To sum up, at present, there are few reports at home and abroad on the use of pressure swing adsorption technology to increase the concentration of sulfur dioxide and nitrogen in the mixed furnace gas of roasting pyrite, and to simultaneously obtain liquid sulfur dioxide and high-concentration nitrogen. Therefore, it is necessary to propose a method for recovering nitrogen and sulfur dioxide in roasted pyrite furnace gas by using pressure swing adsorption technology, so as to overcome the problems of large equipment investment, difficult follow-up by-product treatment and failure to meet environmental protection requirements in the traditional recovery of useful gases. , to realize the comprehensive utilization and zero emission of roasting pyrite flue gas.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for recovering nitrogen and sulfur dioxide in the furnace gas of roasting pyrite ore by variable frequency and pressure swing adsorption. Comprehensive utilization, product diversification, green, safe, zero-emission process, no need to purchase additional raw materials, and low cost.

The present invention solves the above technical problems with the following technical solutions:

The method for recovering nitrogen and sulfur dioxide in the roasting pyrite furnace gas by frequency conversion and pressure swing adsorption, the process steps are as follows:

(1) The sulfur dioxide-containing furnace gas from the fluidized bed furnace for roasting pyrite is cooled by waste heat recovery and cooling of high-temperature waste heat boilers, medium-temperature purification and low-temperature purification after cyclone dust removal and electric dust removal, dust removal, sulfur trioxide removal, drying and cooling, At this time, the temperature of the furnace gas is 35°C-40°C, the sulfur dioxide content is 7%-12%, the content of CO ₂ and O ₂ is less than 1%, and the content of N ₂ is 87%-92%;

(2) Purify and dry the furnace gas in step (1) and then pass through the refined sulfuric acid furnace gas filter made of polytetrafluoroethylene to remove the dust particles and rust entrained in the furnace gas;

(3) The furnace gas obtained in step (2) is passed through the adsorbent of the refinement tank loaded with combined carbon molecular sieves to remove traces of water, O ₂ and CO ₂ in the furnace gas. At this time, the water content in the furnace gas is reduced to 2.1mg /kg～3.2mg/kg, the content of sulfur dioxide is 7.5%～12.5%, the content of _N2 is 87.5%～92.5%;

(4) The furnace gas obtained in step (3) enters the buffer tank, is compressed by a compressor with a frequency converter, and enters the adsorption tower from the bottom of the adsorption tower. The sulfur dioxide in the furnace gas is adsorbed by the adsorbent on the adsorbent bed to realize nitrogen and Separation of sulfur dioxide; after the adsorbed sulfur dioxide is decompressed and desorbed, it is pumped into the buffer tank by the vacuum pump of the frequency converter, and liquid sulfur dioxide is obtained by pressurization or freezing; the gas-liquid mixture containing liquid sulfur dioxide and gaseous sulfur dioxide enters the gas-liquid separator for gas The obtained liquid sulfur dioxide is drained into steel cylinders for collection, and its purity is 98.6% to 99.5%; at the same time, the adsorbent is completely regenerated; % to 99.8%, nitrogen with a pressure of 0.11MPa to 0.53MPa reversely boosts the pressure on the adsorbent bed to an adsorption pressure of 0.10MPa to 0.50MPa, and the adsorbent bed begins to enter the next adsorption cycle process;

(5) A small amount of SO ₂ that has not been liquefied and separated is circulated in step (4) to be compressed or cooled, and gas-liquid separated, and the sulfur dioxide in it is continuously separated;

(6) The nitrogen purity from the top of the adsorption tower is 98.5% to 99.8%, and it enters the buffer tank and is bottled for later use.

The refined sulfuric acid furnace gas filter in the step (2) is 200 mesh.

In the step (3), the composition of the adsorbent in the fine-extraction tank loaded with combined carbon molecular sieve is: from bottom to top, the bottom layer is coarse-porous silica gel with a mass of 30% to 40% of the mass of the adsorbent, and the second layer is a mass of It is fine-pored silica gel with 20% to 30% of the mass of the adsorbent, the third layer is sodium bentonite with a mass of 10% to 20% of the mass of the adsorbent, and the fourth layer is 13X molecular sieve with a mass of 5% to 10% of the mass of the adsorbent. The uppermost layer is a carbon molecular sieve with a mass of 15% to 20% of the mass of the adsorbent, and the sum of the mass percentages of the above components is 100%.

In the step (4), the exhaust pressure of the compressor with frequency converter is 0.13MPa-0.55MPa, and the exhaust temperature is 35°C-41°C.

The adsorbent in the step (4) is based on activated carbon made of biogas residue, and various composite additives are added. The components and their mass percentages are as follows:

The sum of the mass percentages of the above components is 100%.

The biogas residue activated carbon uses biogas residue as a raw material, and its preparation method is: the biogas residue after fermentation in a biogas tank is cleaned, filtered, impurity removed, and extruded and dehydrated by a screw extruder or a three-roll extruder to make it contain water The rate is 8% to 10%; then soaked in a zinc chloride solution with a mass ratio of 10% to 20% and a temperature of 30°C to 40°C for 35 to 40 hours; extruded by a screw extruder or a three-roll extruder Dehydration, drying or drying to make the moisture content 5% to 10%; the obtained biogas residue is placed in a porcelain or silicon carbide crucible and carbonized by microwave irradiation with a power of 2000W to 3000W, and the irradiation time is 20 Minutes to 30 minutes, after natural cooling, rinse with deionized water at 30°C to 40°C, bake for 25 hours, and then pulverize into 200 to 400 mesh fine powder to obtain the biogas residue activated carbon.

The biogas digester sludge charcoal material uses sludge from a biogas fermentation tank as a raw material, and its preparation method is as follows: after the sludge from a biogas fermentation tank is screened, precipitated and drained, the mass concentration is 10%-20%, and the temperature is 30°C to 40°C. Soak in zinc chloride solution at ℃ for 20 hours, drain and bake for 24 hours, put it in a porcelain or silicon carbide crucible, and carbonize it by microwave irradiation with a power of 2000W~3000W, and the irradiation time is 10 minutes~20 minutes, and then After rinsing with deionized water at 30°C-40°C, drying for 25 hours, pulverizing into fine powder of 200-400 mesh, the biogas tank sludge carbonized material is obtained.

Method of the present invention has following advantage:

1. Nitrogen and liquid sulfur dioxide can be simultaneously obtained from the furnace gas of roasting pyrite ore, realizing the comprehensive utilization of furnace gas of roasting pyrite ore, and the cost is low, the process is green, safe and zero-emission.

2. It avoids the huge engineering investment and high environmental protection operation cost of the desulfurization equipment of the enterprise, and also avoids the difficult disposal of the by-products of the desulfurization process.

Description of drawings

Fig. 1 is the process flow diagram of the method for recovering nitrogen and sulfur dioxide in the furnace gas of roasted pyrite ore by frequency conversion and pressure swing adsorption of the present invention.

detailed description

An embodiment of the present invention will be described in detail below with reference to FIG. 1 .

As shown in Figure 1, the process flow of the present invention is: furnace gas coming out of the boiling furnace for roasting pyrite→cyclone dust removal→electric dust removal→drying→cooling→deep fine dehydration, deoxidation and carbon dioxide removal in the fine dehydration tank→pressure swing adsorption Realize the separation of nitrogen and sulfur dioxide→compression→condensation→gas-liquid separation→cooling→obtain liquid SO2.

Example 1:

The furnace gas from the fluidized bed furnace for roasting pyrite is recovered by the high-temperature waste heat boiler, the medium temperature and low temperature cooling purification after cyclone dust removal and electric dust removal, dust removal and sulfur trioxide, drying and cooling. At this time, the temperature of the furnace gas is 35°C , the mass ratio of sulfur dioxide is 12%, the content of CO ₂ and O ₂ is less than 1%, and the content of N2 is 87%; then the dust particles entrained in the mixed gas are removed through the refined sulfuric acid furnace gas filter made of 200 mesh polytetrafluoroethylene and rust, and then remove traces of water, O ₂ and CO ₂ in the mixed furnace gas through the fine desorption tank loaded with combined carbon molecular sieves. At this time, the water content in the mixed furnace gas is reduced to 2.1mg/kg, and the content of sulfur dioxide is about It is 12.5% and the content of N ₂ is about 87.5%; then it is compressed by a compressor with a frequency converter, the exhaust pressure of the compressor with a frequency converter is 0.13MPa, and the exhaust temperature is 35°C at room temperature; after that, the furnace gas is discharged from the adsorption tower The bottom enters the adsorption tower, and the adsorbent on the adsorbent bed absorbs sulfur dioxide to realize the separation of nitrogen and sulfur dioxide; the sulfur dioxide adsorbed by the adsorbent is desorbed by reducing pressure, and is pumped into the buffer tank by a vacuum pump, and then the high-concentration sulfur dioxide is pumped into the buffer tank by a pressurized or freezing method to obtain liquid sulfur dioxide, the gas-liquid mixture containing liquid and gaseous sulfur dioxide enters the gas-liquid separator for gas-liquid separation, and the separated liquid sulfur dioxide is drained into steel cylinders for collection, and the purity of liquid sulfur dioxide is 98.6%; at the same time, the adsorbent is obtained Complete regeneration; after the adsorbent bed is evacuated, use nitrogen gas with a purity of 98.5% and a pressure of 0.11MPa from the top of the adsorption tower to reverse the pressure of the adsorbent bed to an adsorption pressure of 0.10MPa, and the adsorbent bed will start Enter the next adsorption cycle process. A small amount of SO ₂ that has not been liquefied and separated enters the compressor with frequency converter again for a cycle of compression, cooling and gas-liquid separation, and the liquid sulfur dioxide in it is continuously separated and bottled for industrial use. The _N2 with a purity of 98.5% from the top of the tower enters the buffer tank and is bottled for later use.

The composition of the adsorbent of the fine-removing tank loaded with combined carbon molecular sieves is: from bottom to top, the bottom layer is coarse-pore silica gel, the second layer is fine-pore silica gel, the third layer is sodium-based bentonite, and the fourth layer is 13X Molecular sieve, the top layer is carbon molecular sieve.

The adsorbent on the adsorbent bed is based on activated carbon made of biogas residue, adding sludge carbonized material, silica sol, liquid paraffin and ammonium bicarbonate mixture with a mass ratio of 1:5, and sodium-based bentonite. made.

The preparation method of the biogas residue activated carbon is as follows: the biogas residue after fermentation in a biogas tank is cleaned, filtered, and impurity removed, soaked in a zinc chloride solution, and then soaked with deionized water, and squeezed and dehydrated after each of the above steps; Drying or air drying, carbonization by microwave irradiation, natural cooling, rinsing with deionized water, drying and pulverization to obtain the biogas residue activated carbon.

The preparation method of the sludge carbonization material is as follows: the sludge from the biogas fermentation tank is screened, precipitated and drained, soaked in zinc chloride solution, dried after drained, carbonized by microwave irradiation, dried after rinsing with deionized water, powdered, Obtain the sludge carbonization material.

Example 2:

The sulfur dioxide-containing furnace gas from the fluidized bed furnace for roasting pyrite is recovered by the high-temperature waste heat boiler, and after the cyclone dust removal and electric dust removal, the medium temperature cooling purification and low temperature cooling purification, dust removal and sulfur trioxide removal, drying and cooling, at this time, The temperature of the furnace gas is 40°C, the content of sulfur dioxide is 7%, the content of CO ₂ and O ₂ is less than 1%, and the content of N ₂ is 92%; then the mixed gas is removed through a refined sulfuric acid furnace gas filter made of 200 mesh polytetrafluoroethylene The dust particles and rust entrained in the air, the fine desorption tank absorbs and removes trace water, O ₂ and CO ₂ in the mixed furnace gas. At this time, the water content in the mixed furnace gas is reduced to 3.2mg/kg, and the content of sulfur dioxide is about 7.5 %, the content of N2 is about 92.5%; then compressed by the compressor with frequency converter, the exhaust pressure of the compressor with frequency converter is 0.55MPa, the exhaust temperature is about 41℃ at room temperature, and the gas entering the adsorption tower from the bottom of the adsorption tower The adsorbent bed layer, the adsorbent adsorbs sulfur dioxide, and realizes the separation of nitrogen and sulfur dioxide. The sulfur dioxide adsorbed in the adsorbent is decompressed and desorbed, extracted by the vacuum pump of the frequency converter, enters the buffer tank, and then the high-concentration sulfur dioxide is pressurized or frozen to obtain liquid sulfur dioxide, and the gas-liquid mixture containing liquid sulfur dioxide and gaseous sulfur dioxide enters The gas-liquid separator performs gas-liquid separation, and the separated sulfur dioxide is diverted to the steel cylinder for collection, and the purity of the liquid sulfur dioxide is 99.5%. At the same time the adsorbent is completely regenerated. After vacuuming, nitrogen gas with a purity of 99.8% and a pressure of 0.53 MPa from the top of the adsorption tower is used to reversely boost the pressure of the adsorbent bed to an adsorption pressure of 0.50 MPa, and the adsorbent bed begins to enter the next adsorption cycle process. A small amount of SO ₂ that has not been liquefied and separated is recirculated into the compressor with a frequency converter for a cycle of compression, cooling and gas-liquid separation, and the liquid sulfur dioxide in it is continuously separated and bottled for industrial use. The N2 purity of 99.8% from the top of the tower enters the buffer tank and is bottled for industrial use.

All the other are with embodiment 1.

Claims (7)

1. The method for reclaiming nitrogen and sulfur dioxide in the roasting pyrite furnace gas by frequency conversion and pressure swing adsorption is characterized in that the process steps are as follows: (1) The sulfur dioxide-containing furnace gas from the fluidized bed furnace for roasting pyrite is cooled by waste heat recovery and cooling of high-temperature waste heat boilers, medium-temperature purification and low-temperature purification after cyclone dust removal and electric dust removal, dust removal, sulfur trioxide removal, drying and cooling, At this time, the temperature of the furnace gas is 35°C-40°C, the sulfur dioxide content is 7%-12%, the content of CO ₂ and O ₂ is less than 1%, and the content of N ₂ is 87%-92%; (2) Purify and dry the furnace gas in step (1) and then pass through the refined sulfuric acid furnace gas filter made of polytetrafluoroethylene to remove the dust particles and rust entrained in the furnace gas; (3) The furnace gas obtained in step (2) is passed through the adsorbent of the refinement tank loaded with combined carbon molecular sieves to remove traces of water, O ₂ and CO ₂ in the furnace gas. At this time, the water content in the furnace gas is reduced to 2.1mg /kg～3.2mg/kg, the content of sulfur dioxide is 7.5%～12.5%, the content of _N2 is 87.5%～92.5%; (4) The furnace gas obtained in step (3) enters the buffer tank, is compressed by a compressor with a frequency converter, and enters the adsorption tower from the bottom of the adsorption tower. The sulfur dioxide in the furnace gas is adsorbed by the adsorbent on the adsorbent bed to realize nitrogen and Separation of sulfur dioxide; after the adsorbed sulfur dioxide is decompressed and desorbed, it is pumped into the buffer tank by a vacuum pump, and liquid sulfur dioxide is obtained by pressurization or freezing; the gas-liquid mixture containing liquid sulfur dioxide and gaseous sulfur dioxide enters the gas-liquid separator for gas-liquid separation , the resulting liquid sulfur dioxide is drained into steel cylinders for collection, and its purity is 98.6% to 99.5%; at the same time, the adsorbent is completely regenerated; 99.8% nitrogen with a pressure of 0.11MPa-0.53MPa reversely boosts the pressure of the adsorbent bed to an adsorption pressure of 0.10MPa-0.50MPa, and the adsorbent bed begins to enter the next adsorption cycle process; (5) A small amount of SO ₂ that has not been liquefied and separated is circulated in step (4) to be compressed or cooled, and gas-liquid separated, and the sulfur dioxide in it is continuously separated; (6) The nitrogen purity from the top of the adsorption tower is 98.5% to 99.8%, and it enters the buffer tank and is bottled for later use. 2. The method for recovering nitrogen and sulfur dioxide in the furnace gas of roasted pyrite ore by frequency conversion and pressure swing adsorption as claimed in claim 1, characterized in that the refined sulfuric acid furnace gas filter in the step (2) is 200 mesh. 3. The method of variable frequency and pressure swing adsorption recovery of nitrogen and sulfur dioxide in the furnace gas of roasted pyrite as claimed in claim 1, characterized in that in the step (3), the adsorbent of the fine stripping tank of the combined carbon molecular sieve is loaded The composition is: from bottom to top, the bottom layer is coarse-pored silica gel whose mass is 30% to 40% of the mass of the adsorbent, the second layer is fine-pored silica gel whose mass is 20% to 30% of the mass of the adsorbent, and the third layer is the mass of It is sodium bentonite with 10% to 20% of the mass of the adsorbent, the fourth layer is 13X molecular sieve with a mass of 5% to 10% of the mass of the adsorbent, and the uppermost layer is carbon molecular sieve with a mass of 15% to 20% of the mass of the adsorbent. The sum of the mass percentages of the components is 100%. 4. The method of variable frequency and pressure swing adsorption recovery of nitrogen and sulfur dioxide in the furnace gas of roasted pyrite as claimed in claim 1, characterized in that the exhaust pressure of the compressor with frequency converter in the step (4) is 0.13MPa ～0.55MPa, exhaust temperature is 35℃～41℃. 5. The method of variable frequency and pressure swing adsorption recovery of nitrogen and sulfur dioxide in the furnace gas of roasted pyrite ore as claimed in claim 1, characterized in that the adsorbent in the step (4) is activated carbon made of biogas residue As a basis, add a variety of composite additives, and its components and their mass percentages are as follows: The sum of the mass percentages of the above components is 100%. 6. the method for the nitrogen and sulfur dioxide in the frequency conversion pressure swing adsorption recovery roasting pyrite furnace gas as claimed in claim 5, it is characterized in that described biogas residue activated carbon is raw material with biogas residue, and its preparation method is: with biogas pit The fermented biogas residue is cleaned, filtered, impurity removed, and extruded and dehydrated by a screw extruder or a three-roll extruder to make the moisture content 8% to 10%; Soak in zinc chloride solution at a temperature of 30°C-40°C for 35-40 hours; extrude and dehydrate through a screw extruder or a three-roll extruder, dry or air-dry to make the moisture content 5%-10%; The biogas residue obtained is placed in a porcelain or silicon carbide crucible and carbonized by microwave irradiation with an irradiation power of 2000W~3000W. The irradiation time is 20 minutes~30 minutes. After rinsing, bake for 25 hours, and then pulverize into 200-400 mesh fine powder to obtain the biogas residue activated carbon. 7. the method for the nitrogen and sulfur dioxide in the frequency conversion pressure swing adsorption recovery roasting pyrite furnace gas as claimed in claim 5, it is characterized in that, described biogas digester sludge carbonization material is raw material with biogas fermentation pond sludge, and its The preparation method is as follows: After the sludge from the biogas fermentation tank is screened, precipitated and drained, it is soaked in a zinc chloride solution with a mass concentration of 10%-20% and a temperature of 30°C to 40°C for 20 hours, dried for 24 hours after being drained, and placed in a Porcelain or silicon carbide crucibles are carbonized by microwave irradiation with a power of 2000W to 3000W, and the irradiation time is 10 minutes to 20 minutes, then rinsed with deionized water at 30°C to 40°C, baked for 25 hours, and pulverized into 200 ~400 mesh fine powders to obtain the biogas tank sludge carbonization material.