High inlet temperature results in low conversion rate
Thread Content
After a major overhaul of one of our company’s systems, the catalysts in each section were screened, and new catalysts were added as required (mainly low-temperature catalysts for Section 1). After the system was put back into operation, based on the maximum temperature difference method, an inlet temperature of over 446°C was needed in Section 1 in order to achieve a temperature difference of around 130°C; at temperatures of 440°C or lower, this could not be achieved. The temperature difference is only 120°C; it’s impossible to maintain a higher temperature going forward. The electric furnace cannot be used for cooling, and at the same time, the conversion rate is low. The temperature difference across the five stages is high, reaching 15°C. Could someone please help analyze the reasons for this and suggest ways to address it? Thank you.
Provide some conditions so that everyone can analyze the reasons, such as the raw materials used for acid production, the concentration of sulfur dioxide in the incoming stream, and so on.
Is it because the catalyst filling ratio is incorrect? See if the reaction shifts backward
I think the original poster should realize that the reaction has shifted, as he noticed that the temperature increase in segment 5 was too large
Analyze parameters such as the concentration of imported sulfur dioxide in each section, the conversion rate in each section, the resistance in each section, and the production volume
This post was last edited by “I Love Chemical Engineering” on April 4, 2012, at 14:41. The amount of catalyst used in the first stage is relatively small; approximately 60% of the overall conversion actually occurs in this stage. A small temperature difference indicates that there is little reaction taking place, which is related to the amount of catalyst used and the control of the inlet gas temperature.
“After the major overhaul, each section of catalyst was screened, and new catalyst was added as required (mainly low-temperature catalyst for Section 1). After the plant was put into operation, according to the maximum temperature difference method, an inlet temperature of over 446°C was needed in Section 1 in order to achieve a temperature difference of around 130°C; at 440°C or below, this could not be achieved. The temperature difference is only 120°C. Under these conditions, if the amount of catalyst added is sufficient, the only explanation is that the original catalyst had poor activity; the additional low-temperature catalyst failed to enable ignition at low temperatures. As a result, although the temperature difference in that section of the catalyst is 130°C, the conversion rate remains low, and the reaction proceeds at a slower pace.
The temperature rise per layer of transformation is high; it is best to use layered screening and layered reset during screening. It is possible that it involves a mixed screening process, with the catalyst originally located in the lower layer being moved to the upper layer. The catalyst in the lower layer ages more rapidly due to the higher temperature, resulting in an increase in its ignition temperature.
Sulfur is used to produce sulfuric acid, with an inlet SO2 concentration of 10–10.5% in the first stage, and an oxygen-to-sulfur ratio of around 1. Using the domestically produced S101 vanadium catalyst, with an inlet temperature of 420°C, the conversion rate in the first stage is around 63%. The outlet temperature is around 600°C.
Is it a leak in the converter partition that is causing cross-ventilation, resulting in a high inlet temperature in one section and a small temperature difference? It could be due to an issue with the amount of catalyst filled in that section, or perhaps the use of catalysts suitable for different temperature ranges together.
What is the height of the catalyst layer? It’s not good if the height of the catalyst layer is too low.