Discuss the operational issues of the alkylated propane column
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After consulting various sources, it has been found that for the bottom of the propane column in alkylation units, some manufacturers control the operating temperature at 80+ degrees, some at 90+ degrees, and others around 100 degrees. The top pressure varies as well, ranging from 1.3 to 1.6 MPA. I would like to ask everyone what their operating temperatures and pressures are, as well as what the purity levels of propane at the top and bottom of the column are. Generally, the proportion of propane in the feed is less than 5%. I’d like to learn from how others operate in order to save energy and reduce consumption.
Based on the analysis, make gradual adjustments to ensure that the conditions at the bottom of the tower are satisfactory, by appropriately reducing the tower pressure, bottom temperature, and reflux. . Adjust slowly
Relatively speaking, a slightly higher pressure at the top of the tower and a larger reflux rate result in higher energy consumption during operation; however, this approach ensures that light components such as dimethyl ether and propane at the bottom of the tower remain within specified limits. It also reduces acid consumption, while improving the purity of propane at the top of the tower and decreasing the amount of isobutane carried there, thus reducing isobutane losses. Given the current price of isobutane at 5500–5700, and the price of propane at the top of the tower at around 4200, it is possible to calculate the benefits – which are likely greater than those obtained from saving 2 tons of steam
This mainly depends on the content of terpenes in the feed, the number of trays, the requirements for the product at the bottom of the tower, and the availability of heat source. Controlling these different factors has an impact on all of them. Our tower pressure is 1.8–2.0 Mpa, the temperature is around 100°C; the purity of terpenes at the top of the tower is generally 98–99%, while the terpene content at the bottom of the tower is less than 0.5%
The tower pressure is kept so high. Here, the bottom temperature is 97 degrees and the pressure is 1.55, but there’s about 1% propane at the bottom, which prevents the bottom temperature from rising
The control of parameters is ultimately based on the qualification of the product, which is the goal. Other parameter adjustments should be based on this goal; therefore, even if there are differences in the parameters, as long as the product is qualified, that’s sufficient.:
Our pressure at the top of the tower is 1.67, and the temperature at the bottom of the tower is 101. We mainly focus on the quality of the products as well as the operations at both the bottom and top of the tower.
Tower pressure and bottom temperature are related; if the pressure is low, the bottom temperature certainly cannot rise. But tower pressure is also related to the load. While ensuring product quality, a higher load results in greater pressure; under the same load, higher pressure leads to better product quality. However, high pressure affects the feeding load. As long as the tower is not overloaded and the pressure is high, the bottom temperature is also high; the product quality is good, but steam is not saved – on the contrary, energy is conserved. So, it’s necessary to find a balance point. The pressure at the top of the tower is 1.67, while the temperature at the bottom of the tower is around 101. We focus mainly on the quality of the products at both the bottom and the top of the tower, but we still give priority to ensuring the quality at the bottom.