10 practical problems encountered in the PDS alkaline desulfurization system; reward of 30–50 wealth points
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The plant produces 1.3 million tons of coke per year, with a gas generation rate of approximately 65,000 m3/h. The chemical processing system is equipped with a PDS alkaline desulfurization unit with a processing capacity of 61,500 m3/h. Since its operation began, production has been unstable. Sulfur melting is carried out on a continuous basis, with a daily sulfur production of around 3,000 kg. The hydrogen sulfide content in the gas before the desulfurization tower varies significantly, ranging from 3 to 9 g/m3, while the hydrogen sulfide content in the gas after the desulfurization tower is around 100 mg/m3. This means that the plant cannot provide stable and qualified raw gas for the methanol factory. The existing problems are as follows: 1. The alkaline desulfurization process using PDS operates with a single desulfurization tower and a single regeneration tower. When the plant is operating at full capacity, the gas processing volume reaches 65,000–73,000 m3/h. The hydrogen sulfide content in the gas before the towers fluctuates significantly, rising from 3–6 g/m3 as designed to 5–9 g/m3. The hydrogen sulfide level after the towers varies between 100–200 g/m3, which severely affects subsequent chemical manufacturing processes. 2. After 3 years of operation, the resistance of the desulfurization tower increased rapidly; at one point it reached 1000–1500 Pa, posing a threat to the safe operation of the gas system. 3. The desulfurization regeneration tower uses a high-tower regeneration method, which results in high power consumption. Four air compressors are used to supply compressed air; the air contains a high level of moisture, leading to severe water accumulation in the pipes during winter. Fluctuations in air pressure and flow rate affect the regeneration process, and liquid agitation often occurs in the regeneration tower, impacting the flotation of sulfur. 4. The liquid flow foam in the regeneration tower remains thin for an extended period, with severe water content, which greatly hinders the production process in the sulfur melting stage. 5. During long-term operation, the capacity of the sulfur melting tank is insufficient to handle the amount of sulfur foam generated by the system on a daily basis. 6. The discharge pipes and valves are often clogged, resulting in a significantly low sulfur production level, with the daily output being less than 3 tons. Meanwhile, some of the raw sulfur is carried away along with the liquid from the sulfur melting tank in the form of suspended sulfur, and it deposits in the buffer tank. 7. During the operation of the equipment, the solution flow meter and air flow meter often exhibit distortion, which affects the stable regulation of the system. 8. During the operation of the foam tank, the frame-type mixer is equipped with a motor reducer of 7.5 Kw, which often fails and cannot operate properly. 9. The alkali dosing system is placed on the ground, which is unreasonable; it increases the labor intensity for workers, and there is no stirring in the catalyst activation tank. @Student in the sea of knowledge @Desert Poplar @Fish in the Desert @Fish in the Desert 10. The system’s salt concentration reverts to its normal level quickly, remaining stable at around 250 g/t over the long term.
I’m not familiar with these specific technical issues; I’ll help you find some experts: @ZhizheMing @ylb913 @EguanManying @WangTianze @HSLJHZ
The last edit to this post was made by Desert Poplar on 2016-5-5 at 21:22. 1. The main reason for the large fluctuations in hydrogen sulfide content in the gas produced in front of the tower is likely poor coal blending, as variations in coal quality lead to significant fluctuations in sulfur content in the gas； The large fluctuations in gas pressure behind the tower are mainly due to two reasons: one is the impact caused by large fluctuations in sulfur levels ahead of the tower ； Secondly, when operating at full capacity, the gas processing volume reaches 65,000–73,000 m3/h, which is about 20% higher than the designed processing capacity. Solution: First, stabilize the coal quality and ensure proper coal blending ； Secondly, use coal with low volatility or extend the coking time to reduce the average gas production per hour. 2. After 3 years of operation, the resistance of the desulfurization tower increased rapidly; at one point it reached 1000–1500 Pa, posing a threat to the safe operation of the gas system. Solution: Stop operations for maintenance, clean the desulfurization tower, and replace the internal packing. 3. The desulfurization regeneration tower uses a high-tower regeneration method, which results in high power consumption. Four air compressors are used to supply compressed air; the air contains a high level of moisture, leading to severe water accumulation in the pipes during winter. Fluctuations in air pressure and flow rate affect the regeneration process, and liquid agitation often occurs in the regeneration tower, impacting the flotation of sulfur. Solution: Install a dryer at the outlet of the air compressor to ensure effective water removal ； Install a larger compressed air storage tank, drain water promptly, and maintain proper air pressure ； Strengthen the automatic control valve for compressed air flow to intervene and adjust the flow in a timely manner. 4. The liquid flow foam in the regeneration tower remains thin for an extended period, with severe water content, which greatly hinders the production process in the sulfur melting stage. Solution: Raise the buoy position and extend the sulfur foam regeneration time. 5. During long-term operation, the capacity of the sulfur melting tank is insufficient to handle the amount of sulfur foam generated by the system on a daily basis. Solution: Increase the saturation temperature of the heating steam, or install a sulfur melting tank. 6. The discharge pipes and valves are often clogged, resulting in a significantly low sulfur production level, with the daily output being less than 3 tons. Meanwhile, some of the raw sulfur is carried away along with the liquid from the sulfur melting tank in the form of suspended sulfur, and it deposits in the buffer tank. Solution: The sulfur discharge pipe should use internal hyperbolic or spiral propulsion to reduce blockages. Extend the sulfur melting operation time to reduce raw sulfur overflow. 7. During the operation of the equipment, the solution flow meter and air flow meter often exhibit distortion, which affects the stable regulation of the system. Solution: Check whether the flow meter is installed in the appropriate location? Verify whether the instrument’s dry contact is correct; is calibration needed? Is it confirmed that the instrument selection is appropriate? Check if the gauge is clogged? 8. During the operation of the foam tank, the frame-type mixer is equipped with a motor reducer of 7.5 Kw, which often fails and cannot operate properly. Solution: Is the motor power too low? Is there a quality issue with the motor? Is the mechanical installation proper? 9. The alkali dosing system is placed on the ground, which is unreasonable; it increases the labor intensity for workers, and there is no stirring in the catalyst activation tank. Solution: An automatic batching, mixing, and feeding system can be installed.
Desulfurization: It is possible to install an empty tower in series before the desulfurization tower for pre-desulfurization. Regeneration: Replace it with an oxidation regeneration tank. Sulfur melting: Add a centrifuge and intermittent sulfur melting reactors. By-product salts: Install additional salt extraction equipment; this should suffice to completely resolve the problem