Improved process for the production of sulfur dioxide with reduced sublimed sulfur

Abstract

The present application belongs to the field of sulfur dioxide production, and particularly relates to an improved sulfur dioxide production method with reduced sublimed sulfur. The method of the present application improves production efficiency by controlling the sulfur feeding frequency of a sulfur incinerator, stabilizing the liquid level of the sulfur incinerator, optimizing the sublimed sulfur discharge mode of a wire mesh tower, and controlling the outlet temperature of a cooling tower. The method can be adjusted according to actual production conditions, reduces the generation of sublimed sulfur and system resistance, prolongs the service life of a felt filter, has high energy utilization rate, and is thus suitable for industrial large-scale production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of sulfur dioxide production, and particularly relates to an improved sulfur dioxide production method with reduced sublimation sulfur. BACKGROUND

[0002] There are many methods for producing sulfur dioxide in industry, mainly including pure oxygen combustion sulfur method, ammonia-acid method, sodium citrate method, sulfur trioxide-sulfur method, water absorption method, etc. The pure oxygen combustion sulfur method is commonly used in China, and has relative independence in production, simple process, and convenient operation and management. The process principle of producing sulfur dioxide by the pure oxygen method is to pump liquid sulfur (135°C) into a sulfur incinerator while oxygen is introduced. The gaseous sulfur evaporated from the surface of the liquid sulfur is combusted with oxygen to generate sulfur dioxide gas, while a large amount of heat is released. The sulfur dioxide gas generated by the reaction is subjected to heat exchange in a waste heat boiler to produce steam, and then enters a refining device (including a cooling tower-felt filter) to remove sulfur vapor, liquid droplets, dust, water molecules and other solid impurities (metal wire mesh tower, bag filter, felt filter) in the sulfur dioxide gas, and finally enters a freezing section to exchange heat with liquid ammonia to condense into liquid sulfur dioxide. The liquid sulfur dioxide condensed down flows into a product storage tank through a liquid level difference, and the uncondensed impurity gas and sulfur dioxide enter a tail gas absorption device.

[0003] The disadvantages of the prior art are:

[0004] 1) Sublimation sulfur has been a problem for the production of sulfur dioxide devices, which is particularly prominent when the device load is increased;

[0005] 2) The device is seriously clogged with sulfur, the system resistance is large, the energy consumption is high, and the yield is low;

[0006] 3) The felt filter has a large amount of sublimation sulfur, and the device has a short running period.

[0007] The inventors found in the process of invention that when the existing device is produced at low load (40% production), the entire production system is relatively matched, the sublimation sulfur generated by the two cooling towers is relatively small, and the sublimation sulfur generated by the two cooling towers is relatively small. The amount of sublimation sulfur increases significantly, mainly reflected in the increase of pressure difference between the two series-connected two cooling towers, and the increase of sublimation sulfur amount of the two cooling towers from 1-2 days / time to 12h / time. With the increase of the number of sublimation sulfur, the sublimation sulfur also increases with the airflow to the 1# bag filter, and the cleaning period of the filter is increased to 3 months, thereby affecting the stability of the entire ecological system, and the yield is decreased, and the subsequent production load is 80%. SUMMARY

[0008] The technical problem solved by the present application is to provide an improved sulfur dioxide production method with reduced sublimed sulfur, which can reduce the sublimed sulfur in the sulfur dioxide production process.

[0009] To solve the above technical problem, the present application provides an improved sulfur dioxide production method with reduced sublimed sulfur, comprising the following steps: 1) heating sulfur through a molten sulfur tank to obtain liquid sulfur; combusting high-concentration oxygen and liquid sulfur at 790-860°C in a sulfur combustion furnace; 2) SO2 gas produced by the combustion reaction and unreacted sulfur vapor enter a waste heat boiler for heat recovery to obtain cooled SO2 mixed gas; 3) the cooled SO2 mixed gas is subjected to refining treatment, which comprises cooling and filtering; and 4) the SO2 mixed gas after refining treatment is condensed to obtain sulfur dioxide (liquid sulfur dioxide product).

[0010] In step 1), the liquid level in the sulfur combustion furnace after the sulfur is added is controlled by controlling the number of times of adding sulfur per day.

[0011] Step 3) is performed in the following order:

[0012] 3.1) The cooled SO2 mixed gas enters a first cooling tower (from the gas inlet located in the lower part of the first cooling tower), and the temperature in the first cooling tower is set to 140±10°C.

[0013] The cooled SO2 mixed gas is cooled in the first cooling tower to form first-cooled gas, and part of the sublimed sulfur (liquid sublimed sulfur) remains in the bottom of the first cooling tower during the cooling process.

[0014] The first-cooled gas is SO2 mixed gas with a small amount of liquid sublimed sulfur.

[0015] 3.2) The first-cooled gas is discharged from the top outlet of the first cooling tower and flows through a metal wire mesh tower. The sublimed sulfur entrained in the first-cooled gas is intercepted on the metal wire mesh and then deposited at the bottom of the metal wire mesh tower. That is, the metal wire mesh tower can remove the sublimed sulfur in the first-cooled gas.

[0016] The sublimed sulfur deposited at the bottom of the first cooling tower cavity and the sublimed sulfur intercepted by the metal wire mesh tower are returned to the sulfur combustion furnace together.

[0017] 3.3) The wire mesh filtered SO2 mixed gas discharged from the gas outlet of the metal wire mesh tower enters a second cooling tower, which is composed of a 1# cooling tower and a 2# cooling tower connected in series. The 1# cooling tower and the 2# cooling tower have the same structure, with an outlet at the top and an inlet at the middle or lower part of the tower.

[0018] Therefore, the metal wire mesh tower gas outlet is connected with the inlet of the 1# cooling tower, the top outlet of the 1# cooling tower is connected with the inlet of the 2# cooling tower, and the top outlet of the 2# cooling tower is connected with the bag filter assembly;

[0019] After the silk screen filtration, the SO2 mixed gas is firstly introduced into the 1# cooling tower for cooling, and then introduced into the 2# cooling tower for cooling;

[0020] The temperature of the 1# cooling tower is set to 40±5℃, and the temperature of the 2# cooling tower is set to 40±5℃, and the 1# cooling tower and the 2# cooling tower are respectively provided with pressure detectors, when the pressure difference between the 1# cooling tower and the 2# cooling tower is greater than or equal to 6KPa, it is determined that the sublimed sulfur in the mixed gas is blocked at the top outlet of the 1# cooling tower, therefore, the temperature of the 1# cooling tower needs to be increased to 100-115℃, when the pressure difference between the 1# cooling tower and the 2# cooling tower is less than 6KPa, the temperature of the 1# cooling tower is decreased to the original 40±5℃;

[0021] The secondary cooling gas discharged from the top outlet of the 2# cooling tower is the SO2 mixed gas with a small amount of sulfur powder;

[0022] 3.4), the secondary cooling gas discharged from the top outlet of the 2# cooling tower is filtered by the bag filter assembly to remove part of the sulfur powder, and then filtered by the felt filter assembly to remove the remaining sulfur powder, so as to obtain the refined SO2 mixed gas.

[0023] In the present application, the sublimed sulfur is further removed by the felt filter, and then the gas is sent to the liquid ammonia condensation to obtain liquid sulfur dioxide.

[0024] As an improvement of the improved sulfur dioxide production method for reducing sublimed sulfur in the present application:

[0025] In the step 1), the set sulfur feeding frequency is 6-12 times per day (preferably 8-12 times per day, more preferably 8 times per day), and the liquid level in the sulfur incinerator after the sulfur feeding is completed is less than 34% (preferably less than 27%, more preferably less than 24%).

[0026] As a further improvement of the improved sulfur dioxide production method for reducing sublimed sulfur in the present application:

[0027] In the 3.2):

[0028] The sublimed sulfur precipitated at the bottom of the first cooling tower cavity is returned to the sulfur incinerator through the molten sulfur tank in real time;

[0029] The sublimed sulfur intercepted by the metal wire mesh tower is optionally in one of the following modes:

[0030] Mode one, the sublimed sulfur intercepted by the metal wire mesh tower is returned to the sulfur incinerator through the molten sulfur tank at a time of 1-4 times per day (preferably 4 times).

[0031] Method two, the sublimated sulfur intercepted by the metal screen tower is returned to the sulfur burning furnace through the molten sulfur tank in real time.

[0032] As a further improvement of the improved sulfur dioxide production method of the present application for reducing sublimated sulfur:

[0033] In the step 1), the high-concentration oxygen is oxygen with a content of ≥99.9% (volume %); specifically, high-concentration oxygen is separated from air through an air compressor and an air fractionation tower, and the oxygen content is controlled to be more than 99.9%.

[0034] The time for each feeding to be completed is 15-30 minutes.

[0035] As a further improvement of the improved sulfur dioxide production method of the present application for reducing sublimated sulfur:

[0036] The temperature of the mixed gas obtained after cooling in the step 2) is 350±20℃.

[0037] As a further improvement of the improved sulfur dioxide production method of the present application for reducing sublimated sulfur, in the step 3.4):

[0038] The bag filter assembly is composed of 3 bag filters connected in series.

[0039] The felt filter assembly is composed of 2 felt filters connected in series.

[0040] As a further improvement of the improved sulfur dioxide production method of the present application for reducing sublimated sulfur:

[0041] In the step 4), the SO2 mixed gas obtained after cooling and filtering is cooled to ≤-10℃ through an ammonia condenser, so as to obtain sulfur dioxide; the non-condensable gas (protecting a small amount of sulfur dioxide gas) discharged after ammonia condensation is recovered by sodium hydroxide to obtain a by-product of sodium sulfite.

[0042] As a further improvement of the improved sulfur dioxide production method of the present application for reducing sublimated sulfur:

[0043] The sublimated sulfur generated in the 1# cooling tower and the 2# cooling tower is discharged 4 times a day due to a small amount, and this sublimated sulfur is collected regularly without being returned to the sulfur burning furnace.

[0044] In the present application, the combustion reaction in the sulfur burning furnace is preferably at a temperature of 800-840℃.

[0045] In the present application:

[0046] The sulfur-burning furnace vaporizes sulfur into gaseous sulfur and oxygen to react, the total amount of sulfur input per day is fixed, different input frequency of sulfur leads to different amount of single sulfur input, and the vaporization rate of sulfur is also different. The temperature in the sulfur-burning furnace is controlled at 700-950 DEG C, the dosage ratio of oxygen to sulfur is 1:1 (mole ratio), oxygen is continuously input, and the amount of sulfur input is measured by liquid level scale; the reaction equation is S+O2→SO2.

[0047] The application also limits that the preferred input frequency of sulfur is 8 times per day, and more input frequency of sulfur reduces the generation amount of sublimed sulfur. The sublimed sulfur is generated by high-temperature sublimation of sulfur, more input frequency of sulfur and less single input amount of sulfur lead to less sublimation amount, but too much frequency reduces production efficiency and increases energy consumption. Since sulfur removal is manually operated, more sublimed sulfur leads to more production workload and lower efficiency.

[0048] The improved sulfur dioxide production method of the application reduces sublimed sulfur by controlling the input frequency of sulfur in the sulfur-burning furnace, stabilizing the liquid level of the sulfur-burning furnace, optimizing the sublimed sulfur discharge mode of the wire mesh tower, and controlling the outlet temperature of the cooling tower to improve production efficiency. The method can be adjusted according to actual production conditions to reduce the generation of sublimed sulfur and system resistance, prolong the service life of the felt filter, has high energy utilization rate, and is suitable for industrial large-scale production.

[0049] By using the method of the application, the frequency of heating the cooling tower can be obviously reduced, the cleaning cycle of the felt filter can be prolonged, and the purposes of stabilizing the process and reducing product energy consumption can be finally achieved.

[0050] The beneficial effects of the application mainly include:

[0051] 1. The total amount of sulfur input is unchanged, and the amount of sublimed sulfur is reduced by increasing the feeding frequency.

[0052] 2. By controlling the process parameters, the blockage of sublimed sulfur at the top outlet of the 1# cooling tower is reduced, so that the heating frequency of the cooling tower can be reduced, and the sublimed sulfur can enter the felt filter less.

[0053] 3. By controlling the liquid level (trapezoidal liquid level) of the sulfur-burning furnace, the vaporization amount of sulfur is stabilized, and the generation amount of sublimed sulfur is reduced.

[0054] Note: The liquid level of the sulfur-burning furnace is related to the amount of single sulfur input and the temperature in the sulfur-burning furnace.

[0055] Through the above measures, the stability and operation cycle of the device are improved, the generation amount of sublimed sulfur, system resistance and device energy consumption are reduced, and the production cost is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0056] The specific embodiments of the application will be further described in detail below with reference to the accompanying drawings.

[0057] Figure 1 is a schematic view of the structure of the device of the present application;

[0058] Figure 2 is a felt filter of Comparative Example 1;

[0059] Figure 3 is a felt filter of Example 2. DETAILED DESCRIPTION

[0060] The present application will be further described in conjunction with specific examples, but the scope of protection of the present application is not limited to this:

[0061] In the following case, the volume of the sulfur burning furnace is 63m 3 (the volume of the sulfur burning furnace is 10t); the total height of the sulfur burning furnace is about 3 meters, and the daily sulfur input is 18 tons / day.

[0062] The whole process: liquid sulfur is directly punched into the molten sulfur tank, transported to the sulfur burning furnace by the liquid pump and burned with oxygen. The burned sulfur dioxide gas goes to the waste heat boiler, and the heat is recovered by soft water vaporization. The mixed gas of sulfur vapor and sulfur dioxide is cooled to about 350±20℃, enters the first cooling tower (set temperature 140±10℃), and after cooling, the gas is introduced into the metal wire mesh tower to recover most of the sublimed sulfur. The recovered sulfur is returned to the sulfur burning furnace for repeated use, and then enters the second cooling tower (set temperature 40±5℃). The sulfur dioxide gas after the second cooling tower passes through 3 serially connected bag filters to remove part of the sulfur powder, and then passes through 2 serially connected felt filters to filter out the remaining sulfur powder, and then enters the refrigeration section. The liquid sulfur dioxide condensed by the two-stage condensation ammonia condenser flows into the product storage tank by the difference in level, and the non-condensed gas and a small amount of sulfur dioxide gas go to the tail gas absorption device.

[0063] The specific process is as follows:

[0064] Example 1, the improved sulfur dioxide production method for reducing sublimed sulfur, the following steps are carried out in turn:

[0065] 1), combustion reaction, including the following steps:

[0066] 1.1), air is pressurized by an air compressor and separated into high-concentration oxygen by an air fractionation tower, i.e., the oxygen content is controlled to be more than 99.9%;

[0067] 1.2), sulfur is heated by a molten sulfur tank to obtain liquid sulfur;

[0068] Note: The temperature of the molten sulfur tank should only ensure that the sulfur forms liquid sulfur, which is generally controlled at about 135℃.

[0069] 1.3), high concentration oxygen is sent into the incinerator, and reacts with liquid sulfur flowing into the incinerator in the incinerator, S+O2=SO2, O2:S=1:1 molar ratio;

[0070] The sulfur feeding control of liquid sulfur to the incinerator is 8 times per day, the time interval between adjacent 2 times of feeding is 3 h, the time for each feeding is about 15-20 min, and the sulfur feeding amount of each time is about 2.25 t (tons); after each time of liquid sulfur feeding is completed, the liquid level in the incinerator is about 800 mm.

[0071] Description: Before each time of feeding, the liquid level in the incinerator is about 300 mm, therefore, in this embodiment, the liquid level in the incinerator is always about 300-800 mm.

[0072] The temperature fluctuation of the incinerator is small, and the temperature in the incinerator can be controlled to be 810-840°C.

[0073] 2), the SO2 gas generated by the combustion reaction in the incinerator and the unreacted sulfur vapor (formed by liquid sulfur at the set temperature in the incinerator) are discharged from the top outlet of the incinerator and then enter the waste heat boiler, and the heat is recovered by soft water vaporization in the shell side of the waste heat boiler to obtain the cooled SO2 mixed gas;

[0074] The effect of heat exchange can be adjusted by adjusting the flow of soft water, so that the temperature of the cooled mixed gas discharged from the bottom of the waste heat boiler is controlled to be 350±20°C;

[0075] 3), the cooled SO2 mixed gas is refined, including the following steps:

[0076] 3.1), the cooled SO2 mixed gas is discharged from the bottom of the waste heat boiler and enters the first cooling tower from the gas inlet located in the lower part of the first cooling tower, the temperature in the first cooling tower is set to be 140±10°C, and the heat exchange area of the first cooling tower is about 81 m 2 , and the volume is about 1.51 m 3 ;

[0077] The cooled SO2 mixed gas forms the first cooled gas after being cooled in the first cooling tower, and part of the sublimed sulfur (liquid sublimed sulfur) remains in the bottom of the first cooling tower during the above cooling process; the first cooled gas is SO2 mixed gas with a small amount of liquid sublimed sulfur.

[0078] 3.2), the first cooled gas (basically the same as the set temperature in the first cooling tower) is discharged from the top outlet of the first cooling tower and goes to the metal wire mesh tower (the gas inlet is arranged at the middle and lower part of the metal wire mesh tower, and the gas outlet is arranged at the top of the metal wire mesh tower);

[0079] The sublimated sulfur (liquid sulfur) entrained in the gas after the first cooling is intercepted on the metal wire mesh and then precipitates at the bottom of the metal wire mesh tower (solidified after natural cooling); that is, the metal wire mesh tower can remove the sublimated sulfur in the gas after the first cooling;

[0080] The sublimated sulfur (liquid) precipitated at the bottom of the first cooling tower and the sublimated sulfur (liquid) intercepted by the metal wire mesh tower are both returned to the sulfur incinerator.

[0081] The first cooling tower is higher than the molten sulfur tank connected to the sulfur incinerator, so the sublimated sulfur in the first cooling tower automatically returns to the sulfur incinerator through the molten sulfur tank under the action of gravity.

[0082] A switch valve is provided at the bottom of the metal wire mesh tower, and the sublimated sulfur is intermittently discharged from the bottom of the metal wire mesh tower and returned to the sulfur incinerator, with 4 discharges per day, each for about 1.5 minutes, so that the sublimated sulfur can be completely discharged. Since the metal wire mesh tower is higher than the molten sulfur tank connected to the sulfur incinerator, when the valve is opened, the sublimated sulfur in the metal wire mesh tower automatically returns to the sulfur incinerator through the molten sulfur tank under the action of gravity.

[0083] 3.3), the wire mesh filtered SO2 mixed gas discharged from the gas outlet of the metal wire mesh tower enters the second cooling tower, which is composed of a 1# cooling tower and a 2# cooling tower connected in series, and the 1# cooling tower and the 2# cooling tower have the same structure, with an outlet at the top and an inlet at the middle or lower part of the tower;

[0084] Therefore, the gas outlet of the metal wire mesh tower is connected to the inlet of the 1# cooling tower, the top outlet of the 1# cooling tower is connected to the inlet of the 2# cooling tower, and the top outlet of the 2# cooling tower is connected to the bag filter assembly.

[0085] The wire mesh filtered SO2 mixed gas first enters the 1# cooling tower for cooling and then enters the 2# cooling tower for cooling.

[0086] The temperature of the 1# cooling tower is set to 40°C, and the temperature of the 2# cooling tower is set to 40°C. The 1# cooling tower and the 2# cooling tower are respectively provided with pressure detectors. When the pressure difference between the 1# cooling tower and the 2# cooling tower exceeds 6 KPa, it indicates that the sublimated sulfur in the mixed gas is blocked at the top outlet of the 1# cooling tower, so the temperature of the 1# cooling tower needs to be raised to 100°C (so that the sublimated sulfur in the mixed gas is liquefied), thereby ensuring that the pressures of the 1# cooling tower and the 2# cooling tower are basically the same. Then the temperature of the 1# cooling tower is lowered to 40°C.

[0087] The amount of sublimated sulfur generated in the 1# cooling tower and the 2# cooling tower is small, and it is discharged 4 times a day at regular intervals. This sublimated sulfur is collected regularly and does not return to the sulfur incinerator.

[0088] 2# cooling tower top outlet discharged for secondary cooling gas, this secondary cooling gas is mixed gas of SO2 with a small amount of sulfur powder;

[0089] Note: using the above process parameters set in this embodiment, generally speaking, the pressure difference of 1# cooling tower and 2# cooling tower exceeds 6Kpa, which occurs at most once a day.

[0090] 3.4), 2# cooling tower top outlet discharged secondary cooling gas through 3 in series bag filter to remove part of the sulfur powder, and then through 2 in series felt filter to filter the remaining sulfur powder; get refined SO2 mixed gas.

[0091] 4), refined SO2 mixed gas into ammonia condenser for condensation, the gas temperature is reduced to-10℃ or lower; so as to obtain sulfur dioxide product (liquid).

[0092] Non-condensable gas and a small amount of sulfur dioxide gas are recovered with sodium hydroxide to obtain sodium sulfite by-product, which is a conventional technology, so it is not described in detail.

[0093] The results are as follows:

[0094] According to the production load of 80% (i.e. 10 days of work, 8 days of rest, and 2 days of rest), continuous production for 3 months, the sulfur accumulation of the bag filter is large, there is a large amount of sulfur powder on the surface of the bag, and the sublimed sulfur on the felt filter is: 3 people are needed to clean the sublimed sulfur in the felt for 8h, that is, the sulfur removal time is 24 hours.

[0095] Note: the sulfur removal of the felt filter is manually operated, so the longer the sulfur removal time, the more the amount of sublimed sulfur on the felt filter, and the lower the benefit.

[0096] According to the above embodiment 1, it can be known that:

[0097] Using the technical solution described in embodiment 1, the production load is 80% and the continuous production can be carried out for 3 months;

[0098] When the highest liquid level is controlled at 800mm, the pipeline still has a blockage, so further optimization (production control below 700mm) is considered.

[0099] Comparative example 1, relative to example 1, the following changes are made:

[0100] The sulfur feeding frequency in step 1.3) is changed to 4 times / day, and the interval between adjacent 2 times is 6h, and the amount of sulfur fed each time is about 4.5t (tons), that is, the total amount of sulfur fed per day (18t / day) is the same as example 1.

[0101] After each liquid sulfur feeding is completed, the liquid level in the sulfur incinerator is about 1200mm.

[0102] Note: Before each feeding, the liquid level in the sulfur burner is about 600 mm, so in this example, the liquid level in the sulfur burner is always about 600 mm to 1200 mm;

[0103] In this comparative example 1, due to the large amount of sulfur fed at a time, the temperature of the sulfur burner fluctuates greatly, and the temperature in the sulfur burner can only be controlled at 790-860°C.

[0104] In step 3), the number of times the metal mesh tower bottom discharges sublimed sulfur is changed to 2 times; and the number of times the 1# cooling tower and the 2# cooling tower discharge sublimed sulfur is changed to 2 times.

[0105] The number of times when the pressure difference of the 1# cooling tower and the 2# cooling tower exceeds 6KPa (i.e., the case of sublimed sulfur blocking at the top outlet of the 1# cooling tower) is about 2 times per day, i.e., about 12 hours, the 1# cooling tower needs to be heated up once. Note: The disadvantage of frequent heating is that more energy is consumed, and more labor costs are incurred.

[0106] The results are:

[0107] I. According to the production load of 40% (i.e., 4 days of work and 6 days of rest for 10 days), continuous production for 3 months, the sulfur accumulation in the bag filter is large, and there is a large amount of sulfur powder on the surface of the bag, and the sublimed sulfur on the felt filter is as shown in Figure 2 , which takes 4 people 8h to clean up. That is, the desulfurization time is 32 hours.

[0108] Comparative example 1 relative to example 1, under the premise of greatly reducing the production load, the amount of sulfur powder accumulated on the felt filter is still higher than that of example 1, the more sulfur powder means the more sublimed sulfur, and the more sublimed sulfur means the lower the utilization rate of raw materials.

[0109] II. If the production load is 80% and continuous production is carried out, when continuous production is carried out for two months, there is a large amount of accumulated sulfur in the bag filter, and the sublimed sulfur on the felt filter is too hard, so the production is forced to stop for cleaning sublimed sulfur, and at this time, 6 people spend 8h to clean up, that is, the desulfurization time is 48h.

[0110] Example 2:

[0111] Relative to example 1: the sublimed sulfur in the metal mesh tower is returned to the sulfur burner through the molten sulfur tank intermittently (4 times a day), which is changed to real-time continuous return to the sulfur burner through the molten sulfur tank;

[0112] After each liquid sulfur feeding is completed, the liquid level in the sulfur burner is about 700 mm;

[0113] Note: The liquid level in the sulfur burner was about 300 mm before each feeding, so in this example, the liquid level in the sulfur burner was always about 300-700 mm.

[0114] The temperature in the sulfur burner was controlled at 800-830°C.

[0115] The rest was the same as in Example 1.

[0116] Using the above process parameters, the number of times when the pressure difference of the 1# cooling tower and the 2# cooling tower exceeded 6 KPa (i.e., the case where the sublimed sulfur at the top outlet of the 1# cooling tower was blocked) was about once every 2-3 days.

[0117] The results were as follows:

[0118] When the production load was 80% and continuous production was carried out for 3 months, there was almost no sulfur dust on the cloth bag; the sublimed sulfur accumulated at the bottom of the felt filter was significantly reduced, and the cleaning of the sublimed sulfur in the felt filter could be completed in 2 hours by 2 people. That is, the sulfur removal time was 4 hours.

[0119] This Example 2 was relative to Example 1, the amount of sulfur added and the number of times of adding sulfur per day were the same, only the sublimed sulfur from the metal mesh tower was returned to the sulfur burner from intermittent (4 times a day) to real-time continuous return to the sulfur burner; the results were that the sulfur removal time was greatly reduced, thus indicating that the raw material utilization rate was greatly increased. Therefore, the effect of Example 2 was obviously better than that of Example 1.

[0120] Example 3:

[0121] The following changes were made relative to Example 1:

[0122] The number of times of adding sulfur in step 1.3) was changed from 8 times / day to 12 times / day, and the interval between adjacent two feeding times was 2 hours, and the amount of sulfur added each time was about 1.5 tons, i.e., the total amount of sulfur added per day (18 tons / day) was the same as in Example 1.

[0123] After each liquid sulfur feeding was completed, the liquid level in the sulfur burner was about 600 mm;

[0124] Note: The liquid level in the sulfur burner was about 300 mm before each feeding, so in this example, the liquid level in the sulfur burner was always about 300-600 mm.

[0125] In this Example 4, since the amount of sulfur added at a time was small, the temperature fluctuation of the sulfur burner was small, and the temperature in the sulfur burner could be controlled at 810-830°C.

[0126] And the sublimed sulfur from the metal mesh tower in Example 1 was changed from intermittent (4 times a day) to real-time continuous return to the sulfur burner through the molten sulfur tank, and the rest was the same as in Example 1.

[0127] Under the above process parameters, the number of times when the pressure difference of the 1# cooling tower and the 2# cooling tower exceeds 6KPa (i.e., the case where the sublimed sulfur is blocked at the top outlet of the 1# cooling tower) is about 2-3 days once.

[0128] When the production load is 80%, the results are as follows:

[0129] After continuous production for 3 months, there is almost no sulfur dust on the cloth bag, and the sublimed sulfur accumulated at the bottom of the felt filter is significantly reduced. The cleaning of the sublimed sulfur in the felt filter can be completed by 2 people in 2 hours, i.e., the sulfur removal time is 4 hours. This result is basically the same as that of Example 2, but compared with Example 2, the increased number of sulfur feeding increases the workload.

[0130] Example 4:

[0131] The following changes are made with respect to Example 1:

[0132] The number of sulfur feeding in step 1.3) is changed from 8 times / day to 6 times / day, and the interval between the adjacent two feeding times is 4 hours, and the amount of sulfur feeding each time is about 3 tons, i.e., the total amount of sulfur feeding per day (18 tons / day) is the same as that of Example 1.

[0133] After each liquid sulfur feeding is completed, the liquid level in the sulfur incinerator is about 1000mm;

[0134] Note: Before each feeding, the liquid level in the sulfur incinerator is about 300mm, so in this example, the liquid level in the sulfur incinerator is always about 300-1000mm.

[0135] In this Example 4, since the amount of sulfur feeding at a time is also small, the temperature fluctuation of the sulfur incinerator is also small, and the temperature in the sulfur incinerator can be controlled at 800-840℃.

[0136] Moreover, in this Example 4, the sublimed sulfur from the wire mesh tower in Example 1 is changed from intermittent (4 times a day) to real-time continuous return to the sulfur incinerator through the molten sulfur tank, and the rest is the same as that of Example 1.

[0137] Under the above process parameters, the number of times when the pressure difference of the 1# cooling tower and the 2# cooling tower exceeds 6KPa (i.e., the case where the sublimed sulfur is blocked at the top outlet of the 1# cooling tower) is about 2 days once.

[0138] When the production load is 80%, the results are as follows:

[0139] After continuous production for 3 months, there is almost no sulfur dust on the cloth bag, and the sublimed sulfur accumulated at the bottom of the felt filter is significantly reduced. The cleaning of the sublimed sulfur in the felt filter can be completed by 2 people in 2 hours, i.e., the sulfur removal time is 4 hours. This result is basically the same as that of Example 2, but compared with Example 2, the increased number of sulfur feeding increases the workload.

[0140] In summary, the experiment of embodiment 2 is the best, by reducing the amount of sulfur, increasing the number of sulfur, reducing the number of cooling tower temperature, sublimation of sulfur from the metal wire mesh tower bottom continuous discharge, can greatly reduce the waste of sulfur, and the cleaning of felt filter becomes simple, the use cycle is prolonged.

[0141] Finally, it should be noted that the above are only some specific embodiments of the present application. Obviously, the present application is not limited to the above embodiments, but can also have many variations. All variations that can be directly derived or inferred by those of ordinary skill in the art from the disclosure of the present application should be considered as falling within the scope of the present application.

Claims

1. An improved method for producing sulfur dioxide with reduced sublimation sulfur, characterized in that... Includes the following steps: 1) Sulfur is heated in a sulfur melting tank to obtain liquid sulfur; high-concentration oxygen and liquid sulfur are reacted in a sulfur incinerator at 790~860℃; the number of sulfur injections is set at 8~12 times / day to control the liquid level in the sulfur incinerator to <27% after the sulfur injection is completed; 2) The SO2 gas produced by the combustion reaction, along with unreacted sulfur vapor, enters the waste heat boiler for heat recovery, resulting in a cooled SO2 mixture. 3) The cooled SO2 mixture is purified, including cooling and filtration. Specifically, the following steps are performed in sequence: 3.1) After cooling, the SO2 mixed gas enters the first cooling tower, and the temperature inside the first cooling tower is set to 140±10℃; After cooling, the SO2 mixture is cooled in the first cooling tower to form the first cooled gas. During the above cooling process, some of the sublimated sulfur remains at the bottom of the first cooling tower. After the initial cooling, the gas is a mixture of SO2 containing a small amount of liquid sublimed sulfur; 3.2) After the initial cooling, the gas exits from the top outlet of the first cooling tower and flows through the metal wire mesh tower. The sublimated sulfur entrained in the gas after the initial cooling is intercepted on the metal wire mesh and then precipitates at the bottom of the metal wire mesh tower. The metal wire mesh tower can remove the sublimated sulfur in the gas after the initial cooling. Sublimated sulfur precipitated at the bottom of the first cooling tower and sublimated sulfur intercepted by the metal wire mesh tower are returned to the sulfur incinerator together. The sublimed sulfur formed by the precipitation at the bottom of the inner cavity of the first cooling tower is returned to the sulfur incinerator in real time through the sulfur melting tank; Sublimated sulfur intercepted by a metal wire mesh tower can be selected using one of the following methods: Method 1: Sublimated sulfur intercepted by the metal wire mesh tower is returned to the sulfur incinerator through the sulfur melting tank 1-4 times a day at regular intervals; Method 2: The sublimed sulfur intercepted by the metal wire mesh tower is returned to the sulfur incinerator in real time through the sulfur melting tank; 3.3) The SO2 mixed gas filtered by the wire mesh and discharged from the gas outlet of the metal wire mesh tower enters the second cooling tower. The second cooling tower consists of cooling tower #1 and cooling tower #2 connected in series. Cooling tower #1 and cooling tower #2 have the same structure, with an outlet at the top of the tower and an inlet in the middle and lower part of the tower. Therefore, the gas outlet of the metal wire mesh tower is connected to the inlet of cooling tower #1, the top outlet of cooling tower #1 is connected to the inlet of cooling tower #2, and the top outlet of cooling tower #2 is connected to the bag filter assembly. After being filtered through a wire mesh, the SO2 mixture first enters cooling tower #1 for cooling, and then enters cooling tower #2 for further cooling. The temperature of cooling tower #1 is set at 40±5℃, and the temperature of cooling tower #2 is also set at 40±5℃. Cooling towers #1 and #2 are each equipped with a pressure detector. When the pressure difference between cooling towers #1 and #2 is ≥6KPa, it is determined that sublimated sulfur in the mixed gas is causing blockage at the top outlet of cooling tower #1. Therefore, the temperature of cooling tower #1 needs to be increased to 100~115℃. When the pressure difference between cooling towers #1 and #2 is <6KPa, the temperature of cooling tower #1 is then reduced back to the original 40±5℃. The gas discharged from the top outlet of cooling tower #2 is the gas after secondary cooling. This gas after secondary cooling is a SO2 mixture containing trace amounts of sulfur powder. 3.4) The gas discharged from the top outlet of cooling tower #2 after secondary cooling passes through a bag filter assembly to remove some of the sulfur powder, and then passes through a felt filter assembly to filter out the remaining sulfur powder; thus obtaining a refined SO2 mixed gas. 4) After purification, the SO2 mixture is condensed to obtain sulfur dioxide.

2. The improved sulfur dioxide production method for reducing sublimation sulfur according to claim 1, characterized in that: In step 1), high-concentration oxygen is defined as oxygen content ≥ 99.9%. Each feeding cycle takes 15-30 minutes to complete.

3. The improved sulfur dioxide production method for reducing sublimation sulfur according to claim 2, characterized in that: The temperature of the cooled mixed gas obtained in step 2) is 350±20℃.

4. The improved sulfur dioxide production method for reducing sublimation sulfur according to claim 3, characterized in that... In step 3.4): The bag filter assembly consists of three bag filters connected in series; The felt filter assembly consists of two felt filters connected in series.

5. The improved sulfur dioxide production method for reducing sublimation sulfur according to claim 4, characterized in that: In step 4), an ammonia condenser is used. The SO2 mixed gas obtained after cooling and filtration is cooled to ≤-10℃ by the ammonia condenser, thereby obtaining sulfur dioxide. The non-condensable gas discharged after ammonia condensation is recovered with sodium hydroxide to obtain sodium sulfite as a byproduct.

6. The improved sulfur dioxide production method for reducing sublimation sulfur according to claim 5, characterized in that: The sublimed sulfur produced in cooling towers #1 and #2 is relatively small in quantity and is discharged four times a day at regular intervals. This sublimed sulfur is collected routinely and is no longer returned to the sulfur incinerator.

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