Liquid sulfur dioxide production plan
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I. Original site conditions: The factory has two vacant areas, with dimensions of 8000 (mm)×6500 (mm) and 7000×14000 (mm), which will be used as the absorption and conversion area as well as the compression tank area. The distance between these two areas is approximately 30 meters. The sulfur dioxide gas, which is the raw material on site, goes to the sulfur furnace; after cooling, the temperature of the raw gas is around 60°C. The main components of this gas are nitrogen and sulfur dioxide, with small amounts of dust, sublimated sulfur, and carbon dioxide present as well. The sulfur dioxide content in the feed gas is approximately 9% (by volume). The cooling circulating water required for the desulfurization unit can be drawn from the factory’s existing system. II. Design process and technology: The gas mixture containing about 9% sulfur, coming from the sulfur combustion furnace, is cooled to 60°C before being transported via pipes to the absorption tower. The absorption tower is designed with a PP (polypropylene) shell, filled with 316L stainless steel packing, featuring an average absorption efficiency of 95% and a maximum operating temperature of 90°C. The exhaust gas is absorbed and sent to the sodium sulfite production area. Absorption takes place in dual circulation tanks; once each tank becomes saturated with absorbed material, it is sent to the desorption system for desorption, while the process switches to the other circulation tank for absorption. The saturated absorbent liquid is heated in a heat exchanger and then sent to a desorption tower for desorption, which is carried out in an indirect manner using steam at a pressure of 0.2~0.4 MPa. The materials inside and outside the desorption tower are both 316L stainless steel. After desorption, sulfur dioxide gas and water vapor are obtained; these are dehydrated using a condensation separator and a calcium chloride drying tower, and then sent via pipelines to the compression tank area where they are pressurized and liquefied using screw compressors to yield liquid sulfur dioxide as the final product. The absorbed solution after desorption is returned to the circulation tank for reuse. This system does not generate wastewater or waste gas; the sources of waste residues are mainly impurities in the feed gas and elemental sulfur. III. Estimated List of Equipment Table 1: List of Standard General Equipment Equipment Name, Specifications/Model, Technical Requirements, Quantity, Equipment Description: Water Pump – Absorption circulation pump with a flow rate of 7.5 m3/h, head of 10 m, rotation speed of 1450 r/min; the associated motor has a power of 1.5 kW. The pump is corrosion-resistant, can handle media containing particles; it is made of engineering plastic. The density of the medium ranges from 1.0 to 1.3, and mechanical sealing is used. 2 units in operation with 1 as backup, operating continuously 24/7; the flow rate of the desorption rich liquid pump is 8.5 m3/h ； Head: 10m, speed: 1450r, motor power: 1.5kW, corrosion-resistant, made of engineering plastic, medium density: 1.0～1.3, mechanical seal. Two units are operated in parallel with one as a backup, providing 24/7 continuous operation. The cooling water circulation pump makes use of the existing cooling water system, eliminating the need for additional investment. Compressor air delivery volume: 3.2–3.5 m3/min; outlet pressure: 0.8–1.0 Mpa ； Equipped with a 22kW motor, oil-free lubrication, screw-type compressor, and internal components made of stainless steel. 1 unit operates continuously 24/7; SO2 monitoring device range: 0–15% ； Temperature: 0～220℃ ； Flow rate: 0–5000 m3/h; 1 set for SO2 detection at 3 points ； Temperature 6 points ； At a flow rate of 2, the absorption and desorption systems share one control cabinet, while the compression unit has its own control cabinet; this setup enables motor protection as well as control of the equipment’s operation. 2 units of safety monitoring equipment for sulfur dioxide leakage detection and alarm ； Pressure monitoring and alarm for pipelines and storage tanks ； Storage tank temperature monitoring alarm ； The safety monitoring equipment control cabinet, in batches of 1, can perform relevant processing automatically; this is optional. Table 2 List of Non-standard Equipment: Equipment Name, External Dimensions (mm), Technical Requirements, Quantity. Absorption tower: DN500, H6050; Packing tower: The casing is made of PP material, the packing type is SV, and the packing material is 316L stainless steel. The gas handling capacity is 2,500 m3/h, the maximum operating temperature is 90°C, the maximum allowable dust content is 200 mg/m3, and it operates under normal pressure conditions. 1 desorption tower, DN1000, H5300; packed tower, with a shell made of 316L stainless steel. The packing type is SV, and the packing material is also 316L. Maximum gas production: 250 m3/h, operates at atmospheric pressure, with insulated casing. 1 condensation and separation tower with DN1000, H5000 dimensions, equipped with a baffle heat exchanger; maximum gas handling capacity of 500 m3/h. Both the inner and outer components are made of 316L material, and it operates under normal pressure conditions. 1 drying tower, DN450, H3200, empty tower, made of PP; the two towers operate in turn, filled with anhydrous calcium chloride, and operate under slightly negative pressure. 2 absorption liquid heat exchangers, DN580, H3600, tubular heat exchangers; both the inner and outer surfaces are made of 316L material, and they operate under normal pressure conditions. External insulation treatment. 1 liquid-level controlled cooler DN400, H2600, tubular heat exchanger; the inner and outer materials are 316L, operating under atmospheric pressure. 1 finished liquid sulfur dioxide storage tank, DN1500, L10000; it belongs to category 3 pressure vessels. The maximum storage capacity of a single tank is 19 m3. The material used is 16Mn, and the operating pressure is 1 MPa. The total storage capacity of these tanks is sufficient to meet the storage needs for 2 days of production. 1 unit. IV. Estimated Investment Table 3: Investment Table for General Equipment. Equipment Name, Model, Quantity, Unit Price (yuan), Total Amount (10,000 yuan). Water pump: Suction circulation pump – available locally and easy to obtain; 2 units, 2,000 each, unit price 0.40 yuan, total 0.80 million yuan. Desorption rich liquid pump – available locally and easy to obtain; 2 units, 1,600 each, unit price 0.32 yuan, total 0.64 million yuan. Compressor: ZW-3.6/10 model, 1 unit, price 100,000 yuan, total 10.0 million yuan. Operating monitoring equipment and instruments: 1 set, price 58,000 yuan, total 5.80 million yuan. Control cabinets: 2 sets, price 12,000 yuan each, total 2.4 million yuan. Safety monitoring equipment (optional): 1 batch, price 22,000 yuan, total 2.2 million yuan. Grand total (10,000 yuan): 18.92 million yuan (21.12 million yuan). Table 4: Investment Table for Non-standard Equipment and Materials. Equipment Name, Material, Weight (tons), Cost (10,000 yuan), Remarks. Absorption tower: PP, weight 0.15 tons, cost 0.23 million yuan. Shell weight. Desorption system: Desorber made of 316L stainless steel, weight 1.6 tons, cost 5.76 million yuan (this is part of the total weight). Condensation separator: Made of 316L stainless steel, weight 2.8 tons, cost 10.08 million yuan (this is the total weight). Rich liquid preheater: Made of 316L stainless steel, weight 1.8 tons, cost 6.48 million yuan (this is the total weight). Poor liquid cooler: Made of 316L stainless steel, weight 1.0 ton, cost 3.6 million yuan (this is the total weight). Drying tower: PP, shell weight 0.14 tons, cost 0.21 million yuan. Storage tank for sulfur dioxide product: Made of 16Mn pressure vessel steel, weight 8.0 tons, cost 5.04 million yuan (this is the total weight). Grand total: 15.49 tons, cost 31.40 million yuan. Table 5: Purchase Table for Fillers for Non-standard Equipment. Purpose of filler, Material and specifications, Weight, Price. Absorption tower: 316L, SV type, weight 1.2 tons, price 58,000 yuan. Desorption system: Desorber, 316L, SV type, weight 0.5 tons, price 18,000 yuan. Grand total: 1.7 tons, cost 76,000 yuan. 1) The price of PP plastic is approximately 15,000 yuan per ton, 316L stainless steel is approximately 36,000 yuan per ton, and 16Mn steel is approximately 6,300 yuan per ton. The weights mentioned are all net weights. 2) Non-standard equipment is manufactured in-house, resulting in low processing costs, which are not included in the calculation. 3) The equipment investment for the entire desulfurization system is 579,200 yuan. 4) According to the provisions of GYD-205-2000 \"Installation of Static Equipment and Process Metal Structures\" and GYD-206-2000 \"Industrial Pipeline Projects\" in the National Unified Budget Quotas for Installation Works, the total cost for the installation of the desulfurization system equipment is approximately 30,000 yuan. 5) The civil engineering investment is approximately: 30,000 yuan. 6) The unforeseen, contingency, commissioning, and preparation costs for the desulfurization unit are approximately 50,000 yuan. 7) Summary of Investment Estimates Table 7 Summary of Investment Estimates Project Name Amount (10,000 yuan) Equipment investment 57.92 System installation 3.0 Civil engineering infrastructure 3.0 Operating, commissioning and contingency funds 5.0 Total 68.92 V. Economic Evaluation of the Plan 5.1. Process description of the plant 1) The desulfurization efficiency of the absorption tower is 95%, the design efficiency of the desorption and conversion system is 90%, and the conversion rate of sulfur dioxide is 85.5%. 2) Annual production of liquid sulfur dioxide: 3,000 tons. 5.2. Annual operating costs of the facility (for reference): Cost items, unit consumption, annual consumption, unit price (in 10,000 yuan), Sulfur powder: 0.585 tons, 17,551 tons; price per ton: 1,200 yuan/ton, total cost: 210.6 yuan. Water: 3 tons, 9,000 tons; price per ton: 1.3 yuan/ton, total cost: 1.17 yuan. Electricity: 120 kWh, 360,000 kWh; price per kWh: 0.6 yuan/kWh, total cost: 21.6 yuan. Steam: 2 tons, 6,000 tons; price per ton: 120 yuan/ton, total cost: 72.0 yuan. Absorbent: 20 kg, 60 tons; price per ton: 7,500 yuan/ton, total cost: 45.0 yuan. Labor costs: 6 employees, 10,000 yuan per employee per year, total cost: 6.00 yuan. Maintenance costs: 50,000 yuan. Total annual operating costs: 361.37 (10,000 yuan).*The unit consumption refers to the theoretical amount required to produce one ton of liquid sulfur dioxide ； *Annual usage refers to the amount consumed for that project throughout the year ； *The absorbent consumption is the value calculated theoretically. 5.3. Annual output value of the facility (for reference): The current factory price of liquid sulfur dioxide (as of January 2006, in the Sichuan North region) is 1,400 yuan per ton. The annual output value of liquid sulfur dioxide products is 4.2 million yuan. 5.4. Annual gross profit of the facility (for reference): The annual gross profit from liquid sulfur dioxide products is 586,300 yuan. 5.5. Economic evaluation of the unit: The main cost associated with the production of this unit comes from sulfur powder; if the waste gases generated in acid production can be utilized for production, the cost can be significantly reduced. Since the liquid sulfur dioxide product is produced to serve downstream products, sales are not a problem. Under the current conditions, the investment in the equipment can be recouped quickly.
Thanks for sharing! ! ! ! Very useful! ! :) :)
It’s quite comprehensive~~ But could the original poster provide more information on the production equipment?
·44. Selection and Improvement of Compressors for Liquid Sulfur Dioxide Production Tao Weihua (Sulfuric Acid Plant, Zhejiang Juhua Co., Ltd., Quzhou 324004, Zhejiang) Abstract: By replacing the third-generation compressors used in liquid sulfur dioxide production, the quality of this product is improved and the working environment is enhanced. It introduces the problems existing in the use of existing compressors and the improvements made. Keywords: Liquid sulfur dioxide, quality, compressor improvement. Liquid sulfur dioxide (abbreviated as liquid S) is a colorless and transparent liquid with an irritating odor. It has a high vaporization tendency; when its concentration in the air reaches 0.04% to 0.05%, inhalation can cause poisoning, and it irritates the respiratory tract and eyes. The liquid sulfur dioxide product produced by the sulfuric acid plant of Zhejiang Juhua Co., Ltd. was put into commercial production in 1987. While addressing the issues related to the absorption and comprehensive utilization of exhaust gases in sulfuric acid systems, it also meets the production needs for caprolactam products at the nylon factory within the group company, and is available on the market as an independent product. Our plant uses the \"ammonia-acid\" method for liquid sulfur production. That is, 93% sulfuric acid is used to decompose the absorbent solution in the sulfuric acid system (ammonium bisulfite-ammonium sulfite solution), producing high-concentration sulfur dioxide gas, which is then refined and compressed to be liquefied into liquid sulfur dioxide. As a key device in liquid sulfur production, the compressor is crucial for determining the quality of the liquid sulfur product. 1 Upgrade of compressors 1.1 Use of refrigeration compressors The 4V-12.5 type refrigeration compressor is the first-generation compressor that has been in use since its introduction in 1987. It has advantages such as light weight, small size, smooth operation, and low vibration. At the same time, its shaft seal uses a spring-driven automatic compression sealing type, which offers excellent sealing performance and wear resistance, ensuring a favorable working environment in the production site. The quality of liquid sulfur products has remained relatively stable over the years, with the proportion of products meeting national first-class standards exceeding 80%. However, as market competition becomes increasingly fierce and users place higher demands on product quality, in order to improve the standard of products and enhance their competitiveness in the market, it has been decided to focus on improving the quality of liquid sulfur, so that the proportion of products meeting national premium standards exceeds 90%. Through the analysis and testing of various quality indicators of liquid sulfur products, it was found that the gap compared to the \"national premium\" standards mainly lies in the relatively high content of \"residues\" in the products. Through laboratory analysis of the \"residue\" components in the product, it was determined that its main component is the lubricating oil for compressors (abbreviated as compressor oil). This situation is mainly caused by the large amount of compressor oil present in the gas exiting the compressor, which can reach up to 0.5 kg/h. Although an oil remover is installed at the compressor outlet, the high volume of oil present results in low oil removal efficiency, around 75% only. As a result, a significant amount of compressor oil still makes its way into subsequent processes and ends up in the product, leading to a high level of \"residues\" in it. We believe that the high oil content in the gas exiting the compressor is mainly due to structural defects in the 4V-12.5 type compressor itself. Since the piston of this compressor is directly connected to the connecting rod, it relies solely on an oil ring on the piston for sealing, and thus the sealing performance is unreliable. To this end, the existing compressor was first partially modified, with some seals being replaced ； At the same time, operational procedures were strengthened and the oil discharge frequency of the oil remover was increased; although this had some effect, the desired results were not achieved. The oil content in the gas at the compressor outlet is still 0.4 kg/h. 1. 2 Use of air compressors: To further reduce the level of \"residues\" in the liquid sulfur product as well as the oil content in the gas exiting the compressor, it was decided to upgrade the compressors. Through market research and visits to compressor manufacturers, a VW-6/7 type lubrication-free air compressor was selected. No oil needs to be injected into the compressor cylinder, thereby yielding clean compressed gas. This compressor was put into operation in May 1999; after some time of experimentation and adjustment, significant improvements were achieved – the oil content in the gas exiting the compressor dropped markedly to 0.05 kg/h ； The content of \"residues\" in the product has decreased; this parameter not only exceeds the \"national premium\" standards but also reaches the \"DuPont\" standards. After more than a year of operation, the residue content in the product has met all the \"national premium\" standards, with 85% meeting the requirements of the \"DuPont\" standards. However, since the VW-6/7 type lubrication-free air compressors do not have a shaft seal system, and no device using sealing gas was considered for these compressors, only simple fabric seals were used to prevent lubricant leakage. The compressor’s packing system is also of the air-sealing type, which is not suitable for SO2 gas; as a result, the packing does not have a long service life. During production, SO2 gas enters the crankcase, corroding the lubricating oil ； Furthermore, gas leaks outward through the shaft seal area, resulting in a poor working environment at the site. Furthermore, since the VW-type compressor has a V-shaped structure, with two rows of cylinders arranged in a V pattern on the casing, on-site maintenance work is time-consuming and labor-intensive, making it inconvenient. For this reason, a mid-scale maintenance session must be scheduled every 2 to 3 months while the compressor is in operation, not to mention minor repairs; this is highly detrimental to ensuring the proper operation of the compressor and the safe and stable production of liquid sulfur. 1. Use of 3 ZW - 6 / 7 type compressors: To address the issues encountered during the operation of VW - 6 / 7 type compressors, it was decided to modify these compressors or select alternative models. Coincidentally, our company has some idle ZW-6/7 type lubrication-free compressors, whose main technical parameters are basically similar to those of the VW-6/7 type compressors. It was repaired at a minimal cost for maintenance, and the compressor packing system was improved by contacting the manufacturer (by using a packing seal suitable for hydrogen compressors) ； Furthermore, based on the characteristics of liquid sulfur production, improvements were made to the on-site layout of the compressors. The ZW-6/7 type compressors were put into production and operation in November 2000, and after a period of production and improvement, they achieved ideal performance. The compressor operates stably, which **reduces** the amount of maintenance work required. Now, only one mid-term maintenance session is needed after 6 months of operation; in between, it is sufficient to clean the oil tank and filters twice (each time requiring only a 1-hour shutdown), or to inspect and service the gas valves ； Moreover, the compressor cylinders are arranged in a Z shape, which reduces the amount of work required for maintenance and saves time compared to VW-6/7 type compressors. Thanks to the improvements made to the compressor, it is now difficult to detect any SO2 odor while the compressor is in operation, resulting in an **improvement in the production environment**. 2 Improvements and Precautions for Compressors Based on the characteristics of liquid sulfur production, the ZW-6/7 type compressors have been improved in the following ways. (1) In accordance with the requirements of liquid sulfur production, significant improvements were made to the on-site layout of the compressor: the compressor inlet control system, the gas storage tank, and the primary and secondary separators were removed. The compressor’s inlet and outlet were connected directly to the liquid sulfur production system, with DN80 and DN65 stainless steel globe valves installed at each inlet and outlet respectively. A connecting pipe was installed between the inlet and outlet pipes, and the compressor was tested and controlled by adjusting the valves on this connecting pipe. Since the outlet temperature specification for the compressor in liquid sulfur production is 130.1°C, while the outlet temperature at the second stage during normal compressor operation is 100.1°C, the secondary gas cooler has been removed. The primary gas outlet cooler that comes standard with the compressor is a tubular cooler; its heat exchange tubes are made of red copper, and it is not suitable for SO2 gas. It should be replaced with a stainless steel tubular heat exchanger ； (2) The compressor packing system uses a packing seal similar to that of hydrogen compressors. Compared with ordinary ZW-6/7 air-lubricated compressors, this packing seal features an additional flow-reducing sleeve above the existing compressor packing assembly and a pumping device below it, thereby enhancing the sealing performance significantly ； (3) Use of compressor air valves. To ensure the proper operation of the compressor and extend its service life, ring valves, mesh valves, and reed valves have been used successively. During use, it was found that due to variations in the skill level of maintenance personnel, ring valves are prone to having their valve discs not installed properly, which results in noise from the compressor and abnormal pressure levels during operation ； The mesh valve is prone to valve disc fracture during use, and the air valve generally needs to be overhauled after about 1 month ； Reed valves are not suitable for use in liquid sulfur compressors; the spring used in these valves breaks after just a few days of use, rendering them unusable. Moreover, the compressor produces loud noises during operation, which hinders the identification of any faults. Through long-term practical use, ring valves are now employed; under normal conditions, the gas valves operate stably, and no maintenance is required for them during the intermediate maintenance intervals ； (4) To better control the temperature of the compressor lubricating oil, a lubricating oil cooling system was added between the compressor oil pump and the aircraft’s oil tank; a GLC1-1.2 type tubular oil cooler is used for this purpose ； (5) To prevent the leakage of SO2 gas during compressor operation, an exhaust pipe is connected below the compressor’s packing device to the negative-pressure pipeline for liquid sulfur production, thereby effectively improving the working conditions at the site. Through the use of ZW-6/7 compressors in liquid sulfur production, we have found the following points that deserve attention. (1) Within 24 to 72 hours after the compressor resumes operation following its mid-term maintenance, the compressor oil tank and filter screen must be cleaned once (this can be determined from fluctuations and drops in the compressor’s oil pressure) ； (2) The secondary intake valve of the compressor is prone to failure (this can be determined from the pressure at the primary exhaust). Under normal operation, the primary exhaust pressure fluctuates within the range of 0.10 to 0.20 MPa; when it rises above 0.20 MPa, it is necessary to shut down the machine for maintenance and check the secondary intake valve ； (3) Due to the dielectric properties of SO2 gas, after 18 months of compressor operation, it is necessary to carry out maintenance on the gas cooler at the primary outlet and clean the stainless steel coil tubes; otherwise, this will lead to high exhaust pressure at the compressor’s primary stage. At this point, even if the secondary exhaust pressure of the compressor is only 0.10 MPa, the primary exhaust pressure is still above 0.20 MPa. 3 Conclusion Through the use and improvement of generation after generation of compressors in liquid sulfur production, the quality issues associated with liquid sulfur products have been resolved, the efficiency of the compressors has been improved, maintenance costs have been reduced, and the production environment for liquid sulfur has been enhanced, thereby ensuring the normal and stable operation of liquid sulfur production.
Why not use 93 acid for dehydration? The dehydration resistance of calcium chloride increases quite rapidly, right? Replacing the desiccant seems like a lot of work.