A high oxygen combustion sulfur cycle cooling method for producing SO 2 Device

Abstract

The invention discloses a device for preparing SO2 by circulating cooling of high-oxygen combustion sulfur, comprising a sulfur incinerator (3), wherein the sulfur incinerator (3) having a furnace temperature of 850-1080°C is provided with a large-spray angle swirl atomizing spray gun connected to a pipeline for supplying liquid sulfur (1), and a cooling device capable of reducing the high-temperature furnace gas outputted by the sulfur incinerator (3) to a low-temperature furnace gas of 130-230°C is provided on the outlet side of the sulfur incinerator (3), wherein the cooling device is connected to a purification and demisting tower (7) through a pipeline, and is connected to the furnace head of the sulfur incinerator (3) through a process gas supply pipe having a circulating sealed fan (5) and connected to a pipeline for supplying high-oxygen gas (2); the purification and demisting tower (7) is connected to a pressurizing device, or to a pressurizing device and a cooling device through a pipeline, so as to prepare a high-concentration SO2 gas product, or a liquid pure SO2 product. The device of the invention has high production efficiency, saves 20% of investment, and is more suitable for large-scale production.

Description

Technical Field

[0001] The invention belongs to the field of inorganic chemical production, and in particular to the technical fields of metal or precious metal hydrometallurgy, sulfuric acid production, environmentally friendly tail gas SO2 removal, and more specifically, is a device for producing SO2 by high-oxygen combustion sulfur circulation cooling. Background Art

[0002] With the widespread application of pure SO2 or high-concentration SO2 mixed gas in metallurgy, chemical industry, food, papermaking and other industries, the domestic and foreign markets have an increasingly strong demand for pure SO2 or high-concentration SO2 mixed gas; the traditional industrial methods for producing pure SO2 are: first, sulfuric acid replacement sulfite (ammonium, sodium, etc.) method, due to its small scale and high production cost caused by a large amount of sulfate by-product, it is now rarely used; second, the method of producing SO3 and heating reaction with sulfur in the reactor, because it is necessary to first produce pure SO3, the process is complex and energy-intensive, the equipment is severely corroded, and safety production control is difficult. The risk is high. It was used in the 1960s and 1970s but is now rarely used. The third is the pure oxygen surface combustion method. The burning of SO2 gas contains a lot of elemental sulfur and requires 5 to 8 complex filtrations. Although pure SO2 can be produced, the device is prone to clogging, the operation rate is low, and it cannot be produced continuously for a long period of time. Its production cost is high. The fourth is the organic solvent (citric acid, alcohol amine organic matter such as ionic liquid, etc.) absorption and desorption method, which produces high-concentration SO2 gas as a by-product. Pure liquid SO2 products are produced through purification, compression and cooling. However, because a large amount of steam and dry sulfuric acid are consumed in the production process, it is generally not possible to set up independently and is limited in application. Therefore, it is necessary to solve the bottleneck of large-scale production of pure SO2 products as a breakthrough in the application technology topic. Summary of the invention

[0003] The purpose of the present invention is to provide a device for producing SO2 by high-oxygen combustion of sulfur and circulating cooling in response to the problems existing in the prior art; the device adopts high-oxygen combustion of sulfur and circulating cooling to produce high-concentration SO2 gas and recover the waste heat of combustion, and the high-concentration SO2 gas is liquefied by compression and cooling to produce liquid pure SO2 product.

[0004] The purpose of the present invention is to be solved by the following technical solutions:

[0005] A device for preparing SO2 by high-oxygen combustion of sulfur and circulating cooling, comprising a sulfur incinerator, characterized in that: at least one large-spray angle swirl atomizing spray gun connected to a pipeline for supplying liquid sulfur is installed on the burner head of the sulfur incinerator with a furnace temperature of 850-1080°C, and a cooling device is provided on the outlet side of the sulfur incinerator, which can reduce the high-temperature furnace gas output by the sulfur incinerator to a low-temperature furnace gas of 130-230°C; the cooling device is connected to a purification and demisting tower through a pipeline to absorb and purify impurities in the low-temperature furnace gas, and at the same time, the cooling device is connected to a high-temperature furnace gas supply pipeline through a circulating sealed fan and a high-temperature furnace gas supply pipeline. The process gas supply pipe of the oxygen gas pipeline is connected to the burner head of the sulfur incinerator to supply the sulfur incinerator with a process gas mixed with low-temperature furnace gas and high-oxygen gas. The low-temperature furnace gas serves as a circulating cooling gas, and its most important function is to maintain the furnace temperature in the sulfur incinerator. The purification and demisting tower is connected to the pressurizing equipment, or the pressurizing equipment and the cooling equipment through a pipeline to pressurize or pressurize and cool the clean furnace gas at 20°C to 45°C output by the purification and demisting tower into a high-concentration SO2 gas product, or to pressurize the clean furnace gas to increase the liquefaction temperature of the SO2 gas and cool it into a liquid pure SO2 product.

[0006] The temperature of the liquid sulfur is 125°C to 150°C, the pressure is 1.0MPa to 1.6MPa and the purity is ≥99.5%. The large spray angle swirl atomizing spray gun can atomize the liquid sulfur into droplets of 5μm to 100μm and spray them into the sulfur incinerator.

[0007] The temperature of the high-oxygen gas is 30°C to 80°C, and the pressure is +20KPa(G) to 300KPa(G); the molar content of oxygen in the high-oxygen gas is 75% to 98%, and the molar content of N2 or inert gas is 2% to 25%, and the sum of the molar contents of oxygen, N2 or inert gas is 100%.

[0008] High-nitrogen gas contains almost no water vapor. High-nitrogen gas is produced or blended by pressure swing adsorption, vacuum pressure swing adsorption, cryogenic method or other oxygen production methods, but does not use pure oxygen with a content of ≥99%.

[0009] The connection point between the process gas supply pipe and the pipeline for supplying high-oxygen gas is located at the front side or the rear side of the circulating sealed fan.

[0010] The process gas supply pipe is connected with the furnace head of the sulfur incinerator and is connected with the middle and rear sections of the sulfur incinerator through a branch pipe with a control valve.

[0011] The molar concentration of oxygen participating in the reaction in the sulfur incinerator is maintained at 23% to 3%. A gas online analyzer is installed on the outlet pipeline of the steam boiler and / or the heat exchange equipment to control the input amount of liquid sulfur or high-oxygen gas, ensuring that the oxidizing atmosphere completely burns the sprayed atomized liquid sulfur within a sufficient reaction time, and no gaseous sulfur or sublimated sulfur is removed from the sulfur incinerator; the SO2 molar content of the high-temperature furnace gas output by the sulfur incinerator is 70% to 96%, the O2 molar content is 2% to 10%, the N2 or inert gas molar content is 2% to 20%, and the remainder is other trace substances.

[0012] A preferred solution is that the SO2 molar content in the high-temperature gas output from the sulfur incinerator is 75% to 93%.

[0013] The cooling equipment is connected to the purification and demisting tower through a pipeline to transport 40% to 15% of the total low-temperature furnace gas as a high-concentration SO2 mixed gas for absorption and purification to produce SO2 products. The cooling equipment transports 60% to 85% of the total low-temperature furnace gas to the sulfur incinerator through a process gas supply pipe with a circulating sealed fan as a process gas mixed with circulating cooling gas and high-oxygen gas.

[0014] The cooling equipment includes a steam boiler and / or a heat exchanger. When the steam boiler and the heat exchanger are connected in sequence behind the sulfur incinerator, the steam boiler can cool the high-temperature furnace gas output by the sulfur incinerator to a medium-temperature furnace gas of 300 to 450°C, and the heat exchanger can cool the medium-temperature furnace gas to a low-temperature furnace gas of 130 to 230°C.

[0015] The purification and demisting tower adopts concentrated sulfuric acid with a concentration of 91% to 98% to absorb and purify the low-temperature furnace gas. The temperature of the clean furnace gas containing high-concentration SO2 at the outlet of the purification and demisting tower is 20°C to 45°C; the concentrated sulfuric acid can absorb a small amount of SO3 gas from the high-concentration SO2 mixed gas, self-produce sulfuric acid and maintain self-balance.

[0016] The purification and demisting tower is used to remove acid mist in the gas by using a metal mesh demisting device, a fiber demisting device, an adsorber demisting device or an electric demisting device.

[0017] When the pressurizing device is a compression fan and the cooling device is a primary cooler, the compression fan is connected to the outlet of the purification and demisting tower, and the outlet of the compression fan is connected to the primary cooler; the clean furnace gas with a temperature of 20℃~45℃ output by the purification and demisting tower is pressurized to 0.05MPa~0.50MPa by the compression fan, the temperature is increased to 40℃~110℃, and then cooled to 20℃~50℃ by the primary cooler before outputting a high-concentration SO2 gas product; or the clean furnace gas with a temperature of 20℃~45℃ output by the purification and demisting tower is pressurized to 0.30MPa~0.65MPa by the compression fan, the temperature is increased to 100℃~160℃, and then cooled to 20℃~50℃ by the primary cooler before outputting a high-concentration SO2 gas product.

[0018] When the pressurizing equipment is a compression fan, and the cooling equipment is a primary cooler and a secondary cooler with a refrigeration unit connected in sequence, the outlet of the purification and demisting tower is connected to the compression fan, the outlet of the compression fan is connected to the primary cooler, the primary cooler is connected to the secondary cooler, and the outlet of the secondary cooler is connected to the liquid product storage tank. The clean furnace gas with a temperature of 20°C to 45°C output by the purification and demisting tower is pressurized to 0.30MPa to 0.65MPa by the compression fan, the temperature is increased to 100°C to 160°C, and then cooled to 20°C to 50°C by the primary cooler, and finally deep cooled to -15°C to +35°C by the secondary cooler with a refrigeration unit, so that the SO2 gas in the clean furnace gas is liquefied into liquid pure SO2 product and output to the liquid product storage tank.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] The device of the present invention uses high-oxygen combustion of sulfur to produce high-concentration SO2 gas or further produce pure SO2 products. Since sulfur and high-oxygen gas are very easy to obtain, the production device is relatively independent and not constrained by other processes. In particular, with the increasing maturity of VPSA (vacuum pressure swing adsorption) oxygen production technology, large-scale equipment, efficient operation, and reduced oxygen production costs, favorable conditions have been created for the production of high-concentration SO2 gas.

[0021] The combustion intensity of the sulfur incinerator of the present invention is 155-310KW / m 3 It is 5 to 10 times that of the pure oxygen surface combustion sulfur method. Through the circulation cooling of the reaction gas, the combustion temperature in the sulfur incinerator is maintained at 850-1080℃ (while the general pure oxygen surface combustion method furnace has a molten sulfur pool with a combustion temperature of 550-750℃), and the sulfur incinerator maintains excess oxygen to ensure sufficient reaction time (the sulfur combustion reaction time is extended by about five times), so that the sulfur burns fully, and there is no gaseous elemental sulfur in the mixed gas after combustion, creating conditions for the subsequent clean and convenient production of liquid pure SO2 products.

[0022] The high-temperature furnace gas discharged after full combustion in the sulfur incinerator of the present invention has a molar content of SO2 of 70% to 96%, a molar content of O2 of 2% to 10%, a molar content of N2 or inert gas of 2% to 20%, and the remainder is other trace substances, and the sum of the molar contents is 100%; typical components of the high-temperature furnace gas such as SO2-85%, O2-3%, and N2-11% can be directly used as a reducing agent without the need for compression, cooling, liquefaction, and reheating for gasification.

[0023] The fire tube boiler and economizer are directly arranged behind the sulfur incinerator of the present invention to produce low-pressure or medium-pressure steam for heating other processes or power generation. Due to the circulation effect of the circulating sealed fan, the heat energy recovery rate is high, the quality is high, and the economic value is significant.

[0024] The device of the present invention does not have clogging failures caused by elemental liquid sulfur or solid sulfur in the gas after combustion and cooling, simplifies the processes of gas washing, purification, compression, cooling, etc., and is well sealed to prevent leakage. The entire process is automated with instrument detection and adjustment control to ensure personal and equipment safety, and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Attached Figure 1 It is a schematic diagram of the device for producing SO2 by high-oxygen combustion sulfur circulation cooling of the present invention.

[0026] Among them: 1-liquid sulfur; 2-high-oxygen gas; 3-sulfur incinerator; 4-steam boiler; 5-circulating sealed fan; 6-economizer or heat exchanger; 7-purification and demisting tower; 8-compression fan; 9-primary cooler; 10-refrigeration unit; 11-secondary cooler; 12-liquid product storage tank. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0028] like Figure 1As shown, a device for preparing SO2 by high-oxygen combustion of sulfur with circulating cooling comprises a sulfur incinerator 3, wherein the temperature in the sulfur incinerator 3 is 850-1080°C, and at least one large-spray angle swirl atomizing spray gun connected to a pipeline for supplying liquid sulfur 1 is installed on the burner head of the sulfur incinerator 3, wherein the temperature of the liquid sulfur 1 is 125-150°C, the pressure is 1.0MPa-1.6MPa, and the purity is ≥99.5%. The large-spray angle swirl atomizing spray gun can atomize the liquid sulfur 1 into droplets of 5μm-100μm and spray them into the sulfur incinerator 3, and the molar concentration of oxygen participating in the reaction in the sulfur incinerator 3 is maintained at 23%-3% to ensure an excess of oxygen; the outlet side of the sulfur incinerator 3 is sequentially connected to a steam boiler 4 and a heat exchange device (economizer or heat exchanger 6), and the steam boiler 4 is connected to the outlet side of the sulfur incinerator 3. The furnace 4 can cool the high-temperature furnace gas output by the sulfur incinerator 3 to medium-temperature furnace gas of 300-450°C, and the heat exchange equipment can cool the medium-temperature furnace gas to low-temperature furnace gas of 130-230°C; the heat exchange equipment is connected to the purification and demisting tower 7 through a pipeline to transport 40%-15% of the total amount of low-temperature furnace gas to absorb and purify impurities in the low-temperature furnace gas through the purification and demisting tower 7, and at the same time, the process gas supply pipe with a circulating sealed fan 5 and connected to the pipeline for supplying high-oxygen gas 2 is connected to the furnace head of the sulfur incinerator 3 to supply 60%-85% of the total amount of low-temperature furnace gas to the sulfur incinerator 3 as a process gas mixed with the circulating cooling gas and the high-oxygen gas 2, and the temperature of the high-oxygen gas 2 is 30°C-80°C and the pressure is +20KPa(G)-300KP a(G); the molar content of oxygen in the high-oxygen gas 2 is 75% to 98%, the molar content of N2 or inert gas is 2% to 25%, and the sum of the molar contents of oxygen, N2 or inert gas is 100%; the purification and demisting tower 7 is connected to the compression fan 8, the primary cooler 9 and the secondary cooler 11 with a refrigeration unit 10, and the liquid product storage tank 12 in sequence through pipelines. The purification and demisting tower 7 uses concentrated sulfuric acid with a concentration of 91% to 98% to absorb and purify the low-temperature furnace gas. The temperature of the clean furnace gas containing high-concentration SO2 at the outlet of the purification and demisting tower 7 is 20℃ to 45℃ and the pressure is <0.05MPa; the clean furnace gas is pressurized to 0.05MPa to 0.50MPa by the compression fan 8, and the temperature is increased to 40℃ to 110 ℃, and then cool it down to 20℃~50℃ through the primary cooler 9 before outputting high-concentration SO2 gas products; or the clean furnace gas is pressurized to 0.30MPa~0.65MPa through the compressor fan 8, the temperature is increased to 100℃~160℃, and then cool it down to 20℃~50℃ through the primary cooler 9 before outputting high-concentration SO2 gas products; or the clean furnace gas is pressurized to 0.30MPa~0.65MPa through the compressor fan 8, the temperature is increased to 100℃~160℃, and then cool it down to 20℃~50℃ through the primary cooler 9, and finally deep-cooled to -15℃~+35℃ through the secondary cooler 11 with a refrigeration unit 10, so that the SO2 gas in the clean furnace gas is liquefied into liquid pure SO2 product and output to the liquid product storage tank 12.

[0029] In the device provided by the present invention, the connection point between the process gas supply pipe and the pipeline for supplying high-oxygen gas 2 is located at the front side or rear side of the circulating sealed fan 5, and according to needs, the process gas supply pipe is connected to the burner head of the sulfur incinerator 3 and is connected to the middle and rear sections of the sulfur incinerator 3 through a branch pipe with a control valve, that is, secondary air supply is performed. The purification and demisting tower mainly removes SO3, trace moisture, and trace dust in the high-concentration SO2 mixed gas, and then becomes acid mist with a content of ≤15mg / m 3 Clean furnace gas.

[0030] When the device for producing SO2 by high-oxygen combustion and cyclic cooling of sulfur provided by the present invention is used, the SO2 molar content in the high-temperature furnace gas output by the sulfur incinerator 3 is 70% to 96%, the O2 molar content is 2% to 10%, the N2 or inert gas molar content is 2% to 20%, and the balance is other trace substances. The preferred embodiment is that the SO2 molar content in the high-temperature furnace gas output by the sulfur incinerator 3 is 75% to 93%.

[0031] like Figure 1As shown, the device for producing SO2 by circulating cooling of high-oxygen combustion sulfur provided by the present invention comprises: a pressure pump and a pipeline valve for supplying liquid sulfur 1, a pipeline valve for supplying high-oxygen gas 2, a sulfur incinerator 3 with at least one large-spray angle swirl atomizing spray gun, a steam boiler 4, a circulating sealed fan 5, an economizer or heat exchanger 6 as a heat exchange device, a purification and demisting tower 7, a compression fan 8 for pressurizing clean furnace gas, a primary cooler 9, a refrigeration unit 10, a secondary cooler 11, and a liquid product storage tank 12. The specific functions are as follows: the liquid sulfur 1 supplied by the booster pump needs to be melted and finely filtered through solid powder or flake sulfur and enter the intermediate tank for heat preservation and storage. According to the sulfur burning process, the gas analyzer monitors the SO2 or O2 concentration online to adjust the supply of the pumped liquid sulfur 1; oxygen production, such as the oxygen molar concentration supplied by the VPSA oxygen generator unit is about 90%, and the water dew point temperature is lower than -40℃. In addition to oxygen, the high-nitrogen gas 2 also contains one of N2 or inert gas. The temperature of the supplied high-nitrogen gas 2 is 30℃~80℃, and the pressure is +20KPa(G)~300KPa(G); The sulfur incinerator 3 is made of Q345R steel + corundum refractory bricks + clay refractory bricks + high-strength insulation bricks + external insulation structure. The large spray angle swirl atomizing spray gun is connected to the furnace flange. Liquid sulfur is mechanically atomized and suspended + swirl gas + high temperature environment, etc. The sulfur and oxygen are strongly mixed and burned quickly and completely; the steam boiler 4 adopts a fire tube boiler. The boiler and the steam drum are integrated. The steam drum is supported by the riser. The front end of the boiler uses corundum casing and refractory insulation casting to prevent high temperature from burning the tube sheet. The two ends of the boiler are flexible tube sheets. The boiler tubes are 20G or heat-resistant and wear-resistant boiler alloy heat exchange steel pipes. It can produce 1.25 / 2.5 / 4.2 / 6.0MPa medium and low pressure saturated steam; the circulating sealed fan 5 adopts a variable frequency circulating corrosion-resistant and heat-resistant sealed fan, the fan body is made of heavy heat-resistant alloy, mechanical + air or nitrogen sealing to ensure no external leakage, and variable frequency speed regulation is used to control the combustion temperature in the sulfur incinerator; the economizer or heat exchanger 6 is connected to the rear of the steam boiler 4 to further recover the sensible heat of the flue gas, control the outlet temperature of the circulating cooling gas, and avoid low-temperature corrosion. A heat pipe type heat exchanger can also be used to heat hot water or other media; the concentrated sulfuric acid furnace gas purification washing tower used in the purification and demisting tower 7 is a steel-lined ceramic tile structure or a special alloy structure. The tower is a fluoroplastic structure or lined with a porcelain beam filler, an acid distributor, a precision and efficient demister, etc., which are mainly used to wash trace particles in the furnace gas, absorb SO3 gas, absorb trace moisture, and further reduce the temperature of the low-temperature furnace gas (20℃~45℃), remove trace acid mist in the low-temperature furnace gas, etc., to provide quality assurance for subsequent SO2 products; the compressor fan 8 is a piston type or multi-stage centrifugal type or other type of fan rotor (oil-free) type compressor fan, with variable frequency speed control, mainly providing suitable boost power for clean furnace gas (such as 0.05MPa~0.50MPa, 0.30MPa~0.65MPa), in order to facilitate the transportation or cooling and liquefaction of clean SO2 furnace gas. The key material of the fan is shock-resistant and corrosion-resistant alloy or alloy cast iron. The multi-stage mechanical and compressed air seals at the shaft end ensure no leakage; the first-stage cooler 9 usually uses circulating water cooling or other cooling media to reduce the furnace gas temperature to 20-50℃. The heat exchange surface of the cooler is mostly made of alloy steel, and must be designed, manufactured and inspected according to the pressure vessel specifications; the refrigeration unit 10 is specially used to provide cold capacity for further cooling and liquefaction of clean SO2 furnace gas. The refrigeration is a pressurized throttling heat exchange type or a lithium bromide steam heating endothermic type; the second-stage cooler 11 uses the refrigeration unit 10 to provide a cold capacity circulating medium to further cool the clean SO2 furnace gas, and cool the clean SO2 gas to phase change and liquefy to generate liquid pure SO2 products. In order to obtain an economical SO2 liquefaction rate, the outlet furnace gas pressure of the compressor 8 and the furnace gas outlet cooling temperature of the second-stage cooler 11 can be accurately controlled. The liquid product storage tank 12 is used to store and keep liquid pure SO2 cold (warm) for subsequent use or bottling and sale. .

[0032] In the device for producing SO2 by high-oxygen combustion sulfur circulation cooling, liquid sulfur 1 with a temperature of 125℃~150℃, a pressure of 1.0MPa~1.6MPa and a purity of ≥99.5% is metered and controlled by a flow meter to enter a large-spray angle swirl atomizing spray gun connected to the furnace head flange. The liquid sulfur 1 is atomized in particulate form at a large spray angle (~120°) and mixed with the process gas (20~300KPa) delivered by the circulating sealed fan 5 through swirl suspension expansion stirring and then enters a sulfur incinerator 3 at 850~1080℃. The atomized suspended droplets of liquid sulfur 1 with a size of 5μm~100μm are vigorously stirred and burned with the swirl flow of the process gas, and the sulfur incinerator 3 is maintained at a high temperature. The molar concentration of oxygen participating in the reaction in the furnace is maintained at 23% to 3% (the oxygen concentration in the gas at the front end of the incinerator is relatively high, such as 25%; the oxygen concentration gradually decreases along the axis of the furnace body as the reaction progresses, such as 3%) to ensure excess oxygen in a weak excess state. The sulfur in the furnace is completely burned by designing the secondary air supply (mainly controlling the oxidation in the furnace to maintain a weak oxidizing atmosphere, with an oxygen concentration of ≥3% to ensure complete combustion of the sulfur), the mixed gas deflection baffle wall (used to increase the contact and mixing state of the atomized sulfur and the gas reaction to prevent sulfur droplets from being directly taken out of the furnace) and the reaction time in the furnace. The circulating cooling gas actually increases the reaction time, and the longer the reaction time, the more thoroughly the sulfur is burned.The sulfur incinerator 3 is provided with an online temperature detection point, an infrared mirror observation point, a reaction gas back-end gas composition (SO2 / O2) analyzer, etc., which are used to detect the combustion temperature and the excess oxygen in the sulfur incinerator 3. The combustion process parameters in the furnace are precisely controlled by adjusting the supply of liquid sulfur 1 or high-oxygen gas 2 and the air volume of the circulating cooling gas. After the liquid sulfur 1 in the sulfur incinerator 1 is completely burned, it is discharged and connected to the fire tube boiler serving as the steam boiler 4. The high-temperature furnace gas passes through the tube process to heat the boiler water outside the tube, and steam is produced by evaporating the boiler water. The steam-water mixture in the evaporator passes through the riser. After entering the steam drum, steam and water are separated, and the saturated steam passes through the wire mesh demister and is controlled for output use. The desalted and deoxygenated water for the fire tube boiler is provided from outside the boundary and heated by the economizer to make up the water for the steam drum. The outlet gas temperature of the fire tube boiler is 300-450℃; the outlet gas is then connected to the economizer or the heat exchanger 6, and the gas temperature is reduced to 130-230℃ through heat exchange to become low-temperature gas. 60%-85% of the total low-temperature gas volume returns to the sulfur incinerator 3 as circulating cooling gas to continue to participate in the reaction, and the remaining part enters the purification demister tower as a high-concentration SO2 mixed gas 7 purification to produce products; the purified circulating sulfuric acid supplied to the purification and demisting tower 7 is cooled by the acid cooler and then sent to the tower filler surface to fully contact with the high-concentration SO2 mixed gas in countercurrent for mass and heat transfer and reduce the furnace gas temperature to below 45°C. The circulating acid is supplemented by external acid or sent out to maintain the circulation balance. The particulate matter, SO3, H2O (g), etc. in the furnace gas are washed and absorbed by spraying concentrated sulfuric acid (91% to 98%), and then the trace acid mist entrained is removed by the demister and discharged from the purification and demisting tower 7; the clean furnace gas from the purification and demisting tower 7 enters the compressor fan 8 for pressurization (e.g. 0.30MPa-0.65MPa), at this time, the compression fan 8 works to increase the temperature of the clean furnace gas (e.g. 100℃~160℃), and the pressurized and heated clean furnace gas enters the water-cooled primary cooler 9 for cooling, initially reducing the temperature of the clean furnace gas to below 50℃, and then enters the secondary cooler 11, where the clean furnace gas is further cooled and deep-cooled (-15℃~+30℃, and the pressurization increases the liquefaction temperature of SO2), and the SO2 gas in the clean furnace gas is cooled to undergo a liquefied phase change to produce liquid pure SO2 products. The liquid pure SO2 product flows into the SO2 storage tank / tank as the liquid product storage tank 12, and some non-condensable gases (e.g. oxygen, nitrogen, carbon dioxide, a small amount of sulfur dioxide) are separated and discharged from the storage tank for external treatment (e.g. alkali absorption or for other uses) and then discharged for environmental protection.

[0033] like Figure 1 When the high oxygen combustion sulfur circulation cooling device for producing SO2 is in operation, the specific steps are:

[0034] a. High-oxygen gas 2 is mixed with circulating cooling gas as process gas and sent to sulfur incinerator 3. Liquid sulfur 1 is sprayed into sulfur incinerator 3 and mixed with process gas and diffused in cyclone flow for full combustion. The sulfur incinerator 3 maintains an oxidizing atmosphere for full combustion so that no gaseous elemental sulfur escapes. The specific details are as follows:

[0035] The high-oxygen gas 2 contains 75% to 98% oxygen by mole, 2% to 23% N2 or inert gas by mole, and the sum of the mole contents of oxygen, N2 or inert gas is 100%;

[0036] The circulating cooling gas is the low-temperature furnace gas in step c. The low-temperature furnace gas of 130°C to 230°C is transported by the circulating sealed fan 5 and mixed with the high-oxygen gas of 30°C to 80°C and pressure of +20KPa(G) to 300KPa(G) as process gas and is sent to the sulfur incinerator 3 of 850 to 1080°C for sulfur incineration and lowering the furnace temperature. The mixing point of the high-oxygen gas 2 and the circulating cooling gas is set before the circulating sealed fan 5 or after the circulating sealed fan 5;

[0037] A large-spray-angle swirl atomizing spray gun connected to the liquid sulfur 1 supply device is fixed on the burner head of the sulfur incinerator 1. The liquid sulfur 1 with a temperature of 125°C to 150°C, a pressure of 1.0MPa to 1.6MPa and a purity of ≥99.5% is atomized into droplets of 5μm to 100μm by the large-spray-angle swirl atomizing spray gun and sprayed into the sulfur incinerator 3. The droplets of liquid sulfur 1 and the process gas are stirred, mixed, diffused and burned violently in the sulfur incinerator 3 in a swirl expansion manner.

[0038] When the sulfur incinerator 3 is burning, the molar concentration of oxygen participating in the reaction in the furnace is maintained at 23% to 3%, and the oxidizing atmosphere in the sulfur incinerator 3 is maintained to completely burn the sprayed atomized liquid sulfur 1 within a sufficient reaction time, so that no gaseous elemental sulfur is discharged from the sulfur incinerator 3;

[0039] b. The molar content of SO2 in the high-temperature gas discharged after full combustion in the sulfur incinerator 3 is 70% to 96%, the molar content of O2 is 2% to 10%, the molar content of N2 or inert gas is 2% to 20%, and the remainder is other trace substances;

[0040] A more suitable range is that the SO2 molar content in the high-temperature furnace gas is 75% to 93%;

[0041] c. After the high-temperature furnace gas recovers waste heat through the steam boiler 4 and / or the heat exchange equipment, it is cooled into low-temperature furnace gas at 130°C to 230°C, 60% to 85% of the total low-temperature furnace gas is returned to step a as circulating cooling gas to continue to participate in the reaction, and 40% to 15% of the total low-temperature furnace gas is sent to step d as a high-concentration SO2 mixed gas for purification to produce products;

[0042] When the steam boiler 4 and the heat exchange equipment are used together, the high-temperature furnace gas is cooled to 300-450°C medium-temperature furnace gas after the steam boiler 4 produces steam, and the medium-temperature furnace gas is cooled to 130-230°C low-temperature furnace gas after the heat exchange equipment recovers waste heat;

[0043] d. The high-concentration SO2 mixed gas is absorbed and purified by the purification and demisting tower 7 to reduce the temperature to 20℃~45℃ and the pressure to less than 0.05MPa of clean furnace gas. The concentration of concentrated sulfuric acid used in the purification and demisting tower 7 is 91%~98%. The concentrated sulfuric acid can absorb a small amount of SO3 gas from the high-concentration SO2 mixed gas, self-produce sulfuric acid and maintain self-balance;

[0044] The clean furnace gas is pressurized or pressurized and cooled to form a high-concentration SO2 gas product, or the clean furnace gas is pressurized to increase the liquefaction temperature of the SO2 gas and cooled to form a liquid pure SO2 product; specifically: the clean furnace gas is pressurized to 0.05MPa~0.50MPa and the temperature is 40℃~110℃, and then cooled to 20℃~50℃ by the primary cooler 9 and used as a high-concentration SO2 gas product; or the clean furnace gas is pressurized to 0.30MPa~0.65MPa and the temperature is The temperature of the clean furnace gas is 100℃~160℃, and then it is cooled to 20℃~50℃ by the primary cooler 9 and then used as a high-concentration SO2 gas product; or the clean furnace gas is pressurized to 0.30MPa~0.65MPa and the temperature is 100℃~160℃, and then it is cooled to 20℃~50℃ by the primary cooler 9, and finally it is deep cooled to -15℃~+35℃ by the secondary cooler 11 with a cooling unit 10, so that the SO2 gas in the clean furnace gas is liquefied into liquid pure SO2 product.

[0045] The device for producing SO2 by high-oxygen combustion and sulfur circulation cooling provided by the present invention is further described below through specific embodiments.

[0046] Embodiment 1

[0047] In a precious metal recycling plant, the smelting process requires ~12.5t / h of pure SO2, SO2 molar concentration ≥85%, O2 molar concentration ≤5%, SO2 gas temperature ≤60°C, and gas pressure ~100KPa (G) to reduce impurities. The device and process for producing SO2 by circulating cooling of high-oxygen combustion sulfur provided by the present invention are adopted. The temperature of the liquid sulfur 1 after the raw sulfur (wt ≥99.5%) is 140°C after the secondary refining and filtration of molten sulfur, and it is pressurized to 1.5MPa by a pump and then sent to two large-angle swirl atomizing spray guns. The refined sulfur pump frequency conversion speed control liquid sulfur supply ~6.31t / h; the vacuum pressure swing adsorption (VPSA) oxygen production unit supplies high-oxygen gas 2 (O2-92%, N2-8%) 5040Nm 3 / h, pressure 45KPa(G); circulating air volume 26000 Nm 3 / h, the mixed process gas and the droplets of liquid sulfur 1 atomized by the large-spray-angle swirl atomizing gun are burned in the sulfur incinerator 3. The inner diameter of the sulfur incinerator 3 is 2450mm, the length of the furnace is 15000mm and there are four retaining walls inside. The combustion temperature in the sulfur incinerator 3 is 995℃; the high-temperature furnace gas is cooled by the connected steam boiler 4 to recover the waste heat to produce saturated steam (4.2MPa, 252℃) 24t / h, and the temperature of the medium-temperature furnace gas out of the steam boiler 4 is 400℃; the medium-temperature furnace gas then enters the economizer (heat pipe) to heat the steam boiler 4 feed water from 103℃ to 245℃, and the temperature of the medium-temperature furnace gas is reduced to 145℃ to become low-temperature furnace gas; 60% to 85% of the total amount of low-temperature furnace gas out of the economizer is returned to the sulfur incinerator 3 as circulating cooling gas to continue to participate in the reaction, and the remaining part enters the purification and demisting tower 7 as a high-concentration SO2 mixed gas. The tower has a diameter of 1200mm and uses 93% sulfuric acid for circulation (Q=20m 3 / h) cooling, the acid temperature entering the tower is 40℃, the clean gas pressure out of the tower is 38KPa, the temperature is 42℃, and the acid mist content is ≤15mg / m 3 ; The clean furnace gas after purification enters two centrifugal compressors for pressurization, the pressure is increased to 120KPa, the temperature is raised to 90℃, and then cooled to 50℃ by a water cooler; the clean furnace gas temperature at the outlet of the water cooler is 50℃, the pressure is 118KPa, the SO2 molar concentration is 87.5%, and the O2 molar concentration is 3.5%, which fully meets the requirements of wet smelting, and is directly sent to the wet smelting process for use without separate deep-cold liquefaction. It is estimated that the investment of the device for producing SO2 by high-oxygen combustion sulfur circulation cooling of the present invention saves 26% and 40% of the comprehensive operating costs compared with the citric acid absorption and desorption method. The device layout is simple, occupies less space, and the operation and control are automated, achieving the purpose of saving investment and reducing production and operation costs.

[0048] Embodiment 2

[0049] In a copper-cobalt smelter, the smelting reduction and cobalt extraction process requires a purified SO2 volume of ~8.75t / h, a SO2 molar concentration of ≥80%, an O2 molar concentration of ≤5%, a SO2 gas temperature of ≤60°C, and a gas pressure of ~300KPa (G), and part of the produced liquid pure SO2 is stored for standby. The device and process for producing SO2 by circulating cooling of high-oxygen combustion sulfur provided by the present invention are adopted. The temperature of the liquid sulfur 1 after the raw sulfur (wt ≥99.5%) is refined and filtered by the second stage of molten sulfur is 135°C, and it is pressurized to 1.35MPa by a pump and then sent to two large-angle swirl atomizing spray guns. The refined sulfur pump frequency conversion speed regulation controls the liquid sulfur supply of ~4.45t / h; the vacuum pressure swing adsorption (VPSA) oxygen generator supplies high-oxygen gas 2 (O2-85%, N2-15%) 3900Nm 3 / h, pressure 40KPa(G); circulating air volume 17500Nm 3 / h, the mixed process gas and the droplets of liquid sulfur 1 atomized by a large-spray-angle swirl atomizing gun are burned in the sulfur incinerator 3. The inner diameter of the sulfur incinerator 3 is 2200mm, the length of the furnace is 14000mm and there are three retaining walls inside. The combustion temperature in the sulfur incinerator 3 is 1050℃. The high-temperature furnace gas is cooled by the connected steam boiler 4 to recover the waste heat to produce saturated steam (4.2MPa, 252℃) 16.65t / h, and the medium-temperature furnace gas temperature out of the steam boiler 4 is 410℃ The medium-temperature furnace gas then enters the economizer (heat pipe) to heat the steam boiler 4 feed water from 103°C to 235°C, and the temperature of the medium-temperature furnace gas drops to 160°C to become low-temperature furnace gas; 60% to 85% of the total low-temperature furnace gas volume from the economizer is returned to the sulfur incinerator 3 as circulating cooling gas to continue to participate in the reaction, and the remaining part is entered into the purification and demisting tower 7 as a high-concentration SO2 mixed gas. The tower has a diameter of 1100mm and uses 94% sulfuric acid for circulation (Q=20m 3 / h) cooling, the acid temperature entering the tower is 40℃, the clean gas pressure out of the tower is 33KPa, the temperature is 41℃, and the acid mist content is ≤10mg / m 3 ; The clean furnace gas after purification enters two centrifugal compressors for pressurization, pressurization to 340KPa (G), temperature rises to 140℃, and then cools to 45℃ through a water cooler; the clean furnace gas temperature at the outlet of the water cooler is 45℃, pressure is 338KPa, SO2 molar concentration is 80.5%, and O2 molar concentration is 3.6%, which meets the requirements of direct utilization of hydrometallurgy and can be directly sent to the hydrometallurgy process for use. Considering the need to store 300 tons of liquid SO2 products for emergency standby, the subsequent deep cooling and liquefaction is designed at 25% load. The cooling capacity of the refrigeration unit 10 is 350KW, and the temperature at the outlet of the secondary cooler 11 is about -13℃. Therefore, the liquefaction rate of gaseous SO2 in the clean furnace gas is 90%, and the production capacity is 2.0t / h. Two storage tanks with a diameter of 3500mm and a length of 16500mm are set for cold (warm) storage. When needed, it is vaporized by a vaporizer and sent to hydrometallurgy for use, and a small amount of non-condensable gas is sent to hydrometallurgy for pre-reduction. It is estimated that the investment in the device for producing SO2 by high-oxygen combustion sulfur circulation cooling of the present invention is 15% lower than that of the SO3 reduction sulfur method, and the comprehensive operating cost is saved by 20%. The device layout is simple, occupies little space, and the operation control is automated, achieving the purpose of saving investment and reducing production and operation costs, so it is suitable for promotion and use.

[0050] The device of the present invention uses high-oxygen combustion of sulfur to produce high-concentration SO2 gas or further produce pure SO2 products. Since sulfur and high-oxygen gas are very easy to obtain, the production device is relatively independent and not constrained by other processes. In particular, with the maturity of VPSA (vacuum pressure swing adsorption) oxygen production technology, large-scale equipment, efficient operation, and reduced oxygen production costs, favorable conditions have been created for the production of high-concentration SO2 gas. The low-temperature furnace gas of 130°C to 230°C is transported by the circulating sealed fan 5 and mixed with high-oxygen gas with a temperature of 30°C to 80°C and a pressure of +20KPa (G) to 300KPa (G) as process gas and sent to the sulfur incinerator 3 with a temperature of 850 to 1080°C for sulfur incineration and lowering the furnace temperature. There is no gaseous elemental sulfur in the mixed gas after combustion, which creates conditions for the subsequent clean and convenient production of liquid pure SO2 products. The process flow is simple, the production efficiency is high, and it is more suitable for large-scale production, saving 20% ​​of investment and making the production process safe and economical.

[0051] The above embodiments are only for illustrating the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention; any technology not involved in the present invention can be realized by existing technologies.

Claims

1. A device for producing SO2 by high-oxygen combustion of sulfur with circulating cooling, comprising a sulfur incinerator (3), characterized in that: A sulfur incinerator (3) having an internal temperature of 850 to 1080°C is provided with at least one large-spray angle swirl atomizing spray gun connected to a pipeline for supplying liquid sulfur (1) on the furnace head. A cooling device is provided on the outlet side of the sulfur incinerator (3). The cooling device can reduce the high-temperature furnace gas outputted from the sulfur incinerator (3) to a low-temperature furnace gas of 130 to 230°C. The cooling device is connected to a purification and demisting tower (7) through a pipeline to absorb and purify impurities in the low-temperature furnace gas. At the same time, the cooling device is connected to the furnace head of the sulfur incinerator (3) through a process gas supply pipe having a circulating sealed fan (5) and connected to a pipeline for supplying high-oxygen gas (2) to supply a process gas mixed with the low-temperature furnace gas and the high-oxygen gas (2) to the sulfur incinerator (3). The purification and demisting tower (7) is connected to the furnace head of the sulfur incinerator (3) through a process gas supply pipe having a circulating sealed fan (5) and connected to a pipeline for supplying high-oxygen gas (2). The process gas supply pipe is connected to a pressurizing device, or a pressurizing device and a cooling device, so as to pressurize or cool the clean furnace gas at 20°C to 45°C outputted from the purification and demisting tower (7) into a high-concentration SO2 gas product, or to pressurize the clean furnace gas to increase the liquefaction temperature of the SO2 gas and cool it into a liquid pure SO2 product; the temperature of the high-oxygen gas (2) is 30°C to 80°C, and the pressure is +20KPa(G) to 300KPa(G); the molar content of oxygen in the high-oxygen gas (2) is 75% to 98%, the molar content of N2 or inert gas is 2% to 25%, and the sum of the molar contents of oxygen, N2 or inert gas is 100%; the process gas supply pipe is connected to the burner head of the sulfur incinerator (3) and is controlled by a belt. The branch pipe of the valve is connected to the middle and rear sections of the sulfur incinerator (3); the molar concentration of oxygen participating in the reaction in the sulfur incinerator (3) is maintained at 23% to 3%; the molar content of SO2 in the high-temperature furnace gas output by the sulfur incinerator (3) is 70% to 96%, the molar content of O2 is 2% to 10%, the molar content of N2 or inert gas is 2% to 20%, and the remainder is other trace substances; the large-angle swirl atomizing spray gun can atomize liquid sulfur (1) into droplets of 5μm to 100μm and spray them into the sulfur incinerator (3); the connection point between the process gas supply pipe and the pipeline for supplying high-oxygen gas (2) is located at the front side or rear side of the circulating sealed fan (5); the cooling device is connected to the purification and demisting tower (7) through a pipeline 40% to 15% of the total amount of low-temperature furnace gas is transported as a high-concentration SO2 mixed gas for absorption and purification to produce SO2 products. The cooling device transports 40% to 15% of the total amount of low-temperature furnace gas as a circulating cooling gas and a process gas mixed with high-oxygen gas (2) to the sulfur incinerator (3) through a process gas supply pipe with a circulating sealed fan (5); the cooling device includes a steam boiler (4) and / or a heat exchange device. When the steam boiler (4) and the heat exchange device are connected in sequence behind the sulfur incinerator (3), the steam boiler (4) can cool the high-temperature furnace gas output by the sulfur incinerator (3) to a medium-temperature furnace gas of 300 to 450°C, and the heat exchange device can cool the medium-temperature furnace gas to a low-temperature furnace gas of 130°C to 230°C.

2. The device for producing SO2 by high-oxygen combustion sulfur circulation cooling according to claim 1 is characterized in that: The liquid sulfur (1) has a temperature of 125° C. to 150° C., a pressure of 1.0 MPa to 1.6 MPa, and a purity of ≥99.5%.

3. The device for producing SO2 by high oxygen combustion sulfur circulation cooling according to claim 1 is characterized in that: The purification and demisting tower (7) uses concentrated sulfuric acid with a concentration of 91% to 98% to absorb and purify the low-temperature furnace gas. The temperature of the clean furnace gas containing high-concentration SO2 at the outlet of the purification and demisting tower (7) is 20°C to 45°C.

4. The device for producing SO2 by high-oxygen combustion sulfur circulation cooling according to claim 1 or 3, characterized in that: When the pressurizing device is a compressor fan (8) and the cooling device is a primary cooler (9), the compressor fan (8) is connected to the outlet of the purification and demisting tower (7), and the outlet of the compressor fan (8) is connected to the primary cooler (9); the clean furnace gas with a temperature of 20°C to 45°C output from the purification and demisting tower (7) is pressurized to 0.05MPa to 0.50MPa by the compressor fan (8), the temperature is increased to 40°C to 110°C, and then the temperature is reduced to 20°C to 50°C by the primary cooler (9) before outputting a high-concentration SO2 gas product; or the clean furnace gas with a temperature of 20°C to 45°C output from the purification and demisting tower (7) is pressurized to 0.30MPa to 0.65MPa by the compressor fan (8), the temperature is increased to 100°C to 160°C, and then the temperature is reduced to 20°C to 50°C by the primary cooler (9) before outputting a high-concentration SO2 gas product.

5. The device for producing SO2 by high-oxygen combustion sulfur circulation cooling according to claim 1 or 3, characterized in that: When the pressurizing device is a compressor fan (8), and the cooling device is a primary cooler (9) and a secondary cooler (11) with a refrigeration unit (10) connected in sequence, the outlet of the purification and demisting tower (7) is connected to the compressor fan (8), the outlet of the compressor fan (8) is connected to the primary cooler (9), the primary cooler (9) is connected to the secondary cooler (11), and the outlet of the secondary cooler (11) is connected to the liquid product storage tank (12). The clean furnace gas outputted from the purification and demisting tower (7) at a temperature of 20°C to 45°C is pressurized to 0.30MPa to 0.65MPa by the compressor fan (8), the temperature is increased to 100°C to 160°C, and then cooled to 20°C to 50°C by the primary cooler (9), and finally deep cooled to -15°C to +35°C by the secondary cooler (11) with the refrigeration unit (10), so that the SO2 gas in the clean furnace gas is liquefied into a liquid pure SO2 product and output to the liquid product storage tank (12).

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