关键词: 催化裂解装置, 液化石油气分离, 脱丙烷塔, 压力, 温度, 关键组分, 相对挥发度, 理论板数

Abstract: As the cracking depth of the catalytic cracking unit increases, the content of alkadienes in the catalytic cracked gas increases. The bottom temperature of the depropanizer in the conventional process of catalytic cracked gas separation is about 108°C. The higher temperature increases the possibility of alkadiene polymerization, affecting the operating cycle and economic benefits of the unit. Several catalytic cracked gas separation units in China commonly experience coking and blockage in the reboiler of the depropanizer tower and the bottom of the depropanizer tower. To alleviate the shutdown caused by coking at the bottom of the depropanizer tower, polymerization inhibitors are usually added to the feed and bottom materials to reduce the polymerization rate of the materials. The article analyzes the influence of pressure on the relative volatility and bottom temperature of the depropanized system. Lower tower pressure is beneficial for reducing the bottom temperature and increasing the relative volatility of light and heavy key components, making separation easier. The tower pressure is suitable within the range of 0.9 to 1.1 MPa, and the bottom temperature of the tower can be controlled below 80°C, to reduce unplanned shutdowns caused by coking at the bottom of the tower while meeting the separation requirements of the depropanizer tower. In addition, the article compares the optimized plan with the conventional plan in terms of energy consumption and equipment investment. The optimized plan reduces energy consumption by about 37% compared to the conventional plan, and the main equipment investment is also lower than the conventional plan.

Key words: font-family:-apple-system, blinkmacsystemfont, ", font-size:14px, background-color:#FFFFFF, ">catalytic cracking unit, liquefied petroleum gas separation, depropanization tower, pressure, temperature, key components, relative volatility, theoretical plate number