Bottleneck And Countermeasure Of Long Operation Period Of C5 Separation Plant

A new C5 separation plant was built in Sinopec Beijing Yanshan Company who has the independent intellectual property rights. The raw materials C5, a byproduct of Yanshan ethylene plant, is mainly separated to isoprene, piperylene and cyclopentadiene components at a designed capacity of 150,000 tons per year. The use of C5 is crucial to reducing the cost of ethylene production. Also, C5 servers as the raw material in the Yanshan isoprene rubber device, so it supports the development of Yanshan’s core business and improves the product mix.Based on the existed problems during the first run of C5 separation plant, including a serious polymerization, a short operation period of the second extraction column, a significant hydrolysis of the solvent DMF, a great loss of isoprene, and some other issues that may also influence the long operation period of our plant, we offered our solutions and evaluated the improvement in further operations. In the premise of the same quality and yield, first we reduce the polymerization rate of isoprene and the degree of polymerization (DP) in the de-heavy oil column (C102) and the extraction system. With the extension of the operation time, some polymers more or less form, thus we need to keep the system running at a stable condition. Finally, we must maintain the quality of the recycled solvent DMF and reduce its hydrolysis and emission losses, in order to achieve a stable operation of the solvent system.During the second run of the plant, the quality of product meets the requirement and the lowest energy consumption is 218.7 kg standard oil/ton of raw materials, which is lower than the design value226.8 kg standard oil/ton of raw materials. Furthermore, the DP declines in the extraction system resulting in a less loss of isoprene in comparison with the first run. The yield of isoprene is 84%, which is lower than the design value 6%. The yield of piperylene is 92%, which is higher than the design value 3%. The yield of cyclopentadiene is 87%, which is higher than the design value 1%. The quality of recycled solvent DMF is becoming better, water content of recycled solvent is lower than 500mg/kg. Overall, our improvement is successful and ensures a long operation period of our unit.