Process parameters for the rough processing section in the chemical production area of coking plants
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Regarding the process parameters of the crude tar production section in coking plant chemical production areas, the processes vary from one plant to another, so the parameters will also differ. However, the principles remain the same. Our company’s crude tar production volume has been relatively low recently, and I would like to discuss this with everyone. First, let me introduce our company’s process parameters: the volatil content of the coal used as feedstock is around 27% (on a combustible basis). 112 coke batches are produced per day, with each batch weighing 14.5 tons. The steam pressure in the furnace is 0.35 MPa. The flow rate of the lean oil entering the benzene washing tower is 70 m³/h, and its temperature is 32 degrees Celsius. The temperature of the gas after passing through the final cooling tower is 30 degrees Celsius. The steam temperature entering the regenerator is 350 degrees Celsius, and its flow rate is 2000 kg/h. The reflux ratio is 3.0–4.0 m³/h. The temperature of the oil vapor at the top of the benzene removal tower is 93–95 degrees Celsius. The crude tar production volume is 15–16 tons per day. These are the parameters for this entire production section. I hope my colleagues can offer me some suggestions. Thank you very much. My QQ number is 40491197
Here, we produce 1.1 million tons of coke per year. The temperature of the purified and finally cooled gas is maintained at 24–26 degrees; occasionally, there are slight fluctuations. The temperature of the lean oil after the secondary cooling is about 2–3 degrees higher than that after final cooling. The flow rate of the lean oil entering the benzene washing tower is 140 cubic meters per hour. The steam temperature entering the regenerator is around 420 degrees, while the steam flow rate is 3.00–3.20 m³/h. This parameter is primarily adjusted by us to regulate the temperature at the top of the debenzolization tower; no reflux is required for this purpose. The pressure of the steam entering the regenerator is 0.50 MPa; this is controlled by the thermal boiler. It is required that over 91.5% of the crude benzene output has a boiling point below 180 degrees. Our daily production volume is approximately 30–32 tons. The temperature at the top of the debenzolization tower is kept within the range of 93.5–94 degrees
Additionally, I believe it’s largely related to the stability of the steam. Last night during the midnight shift and this morning during the 8 a.m. shift, the gas flow rate was 55,375 cubic meters per hour both times. This morning, the steam remained very stable; the temperature at the top of the debenzolization tower didn’t need any adjustment and automatically stayed within the range of 93.5–94 degrees. Last night, the output during the midnight shift was 10.385, while this morning during the 8 a.m. shift, it reached 12.33
Can the person on the first floor please clarify the gas flow rate?
Excuse me, has your production volume on the first floor decreased only recently? I suggest you first determine which step is going wrong Distillation? Wash? The production volume of crude benzene is not necessarily determined by parameter control! It depends on the benzene content in the gas, the molecular weight of the wash oil, the contact area between the gas and the wash oil, the efficiency of gas-liquid contact, the benzene content in the circulating wash oil, as well as the benzene removal efficiency of the debenzolization tower, the amount of steam, the temperature of the rich oil entering the debenzolization tower, the gas flow rate in the benzol washing tower, etc. With so many factors at play, I suggest that you first measure the benzene content in the gas after it passes through the benzene washing tower, as well as the benzene content in the oil-poor stream after it passes through the benzene removal tower; this will help determine which stage is causing the problem. Additionally, monitor the quality of the wash oil and verify all operating indicators.
The recovery of crude benzene is also a basic chemical processing operation; what matters is generally the yield rather than the production volume. Of course, when the raw material supply is stable, the production volume can be fairly determined, but when the raw material supply is uncertain, it’s not possible to focus solely on the production volume.
Referring specifically to the situation in our plant: we designed the coke ovens to have an annual production capacity of 800,000 tons, but currently there is one coke oven with a capacity of 400,000 tons. Our plant mainly employs the following methods to increase the crude benzene yield: 1. Regularly removing sludge from the wash oil via a wash oil regenerator, thereby improving the quality of the wash oil. 2. Adjust the flow rates of lean oil and rich oil by testing the benzene content in the gas before and after the benzene washing tower. 3. Stable steam pressure ； 4. Keep the temperature of the gas after final cooling at around 25 degrees; the temperature of the lean oil should be 2–3 degrees higher than that of the gas. 5. Control the top temperature of the tower and the temperature of the rich oil entering the tower. Currently, through the aforementioned methods, the daily production of crude benzene exceeds 12 tons.
Based on the information provided by the poster, you seem to be using Type 58-2 coke ovens with an annual production capacity of 600,000 tons of coke; judging from the volatile matter content, they are not rammed coke ovens. I wonder if my guess is correct. In terms of output, it did not meet the design requirements. I agree with what the experts mentioned above have said. The quality of wash oil affects the yield of crude benzene; so does the temperature of the gas. It is recommended that you conduct two analyses: 1. The benzene content in the gas at the inlet and outlet of the benzene washing tower. 2 Content of rich and lean oil in the benzene washing tower. This way, we can tell whether the problem lies with benzene washing or benzene distillation. Targeted solutions. Our plant once experienced an incident where the distributor in the distillation tower became tilted, resulting in a decrease in benzene production; however, all parameters remained normal. Just my personal opinion, for reference only.
It should be related to oil washing, but the yield is unclear
If your raw materials are unstable, but there are no significant fluctuations in your process operating parameters, you probably don’t need to worry about production volume. I agree with the previous poster regarding the issue of recovery rate; it would be advisable to examine any changes in the coal composition and consider changing the coal supplier if necessary.