Practical operation of hydrocracking
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There are a few questions for which I need the guidance of those who are more experienced. 1. The unit is operating at full load, with a reactor temperature of 370 degrees and a pressure of 16 MPa. The conversion rate reaches 70%. When 60% is required for operation, in order for the reactor to achieve the same conversion rate, should the inlet temperature remain at 370 degrees, or should it be reduced? 370 degrees is the temperature at which the reaction reaches its conversion rate; then, after the reduction in volume, does the same raw material still require 370 degrees? Question 2: First reduce the temperature and then reduce the quantity. As the temperature drops and the quantity is reduced, could the temperature rise again due to the lower quantity? Third question: if the bed temperature rises by 25 degrees at a conversion rate of 70%, then when the conversion rate is lower, cold hydrogen is used to lower the temperature so that it rises by another 25 degrees, thereby bringing the conversion rate within the specified range.
The last edit to this post was made by Silent Lamb_QOQW on 2018-7-3 at 15:00. Reducing the load to 60% also means that the space velocity drops to 60%; without a decrease in temperature, the conversion rate will increase, so it is necessary to lower the temperature appropriately. 2. Reducing the temperature first and then the feed rate means first lowering the reaction temperature in order to reduce the degree of reaction and the conversion rate; this will result in a decrease in the bed temperature rise. Reducing the feed rate later on serves to increase the conversion rate. If the conversion rate at the end is the same as at the beginning, and the reactor inlet temperature remains the same during the latter stage, then the bed temperature rise will increase again. 3. With other conditions such as the hydrogen-to-oil ratio, catalyst activity, space velocity, hydrogen partial pressure, and feedstock properties remaining unchanged, reducing the amount of cold hydrogen and increasing the bed temperature can improve the conversion rate. 4. I don’t have any practical experience; this is just my guess. I hope experts can give me some advice
The reaction temperature is related to the quality of the product and the properties of the raw materials; when the properties of the raw materials remain unchanged, the reaction temperature also stays the same. Therefore, even if the load is reduced by 10%, the reaction temperature remains at 370 degrees. Due to the decrease in air velocity, the heat release amount decreases; at this point it is necessary to reduce the amount of recycled hydrogen in order to maintain the bed temperature. Therefore, in the end, only the turbine speed and the amount of fresh hydrogen added need to be adjusted. Third question, I think your understanding of it is acceptable.