Acetylene is a valuable product for the chemical and welding industry. The Linde Acetylene Recovery Unit (ARU) can be integrated into any ethylene plant as the process can be operated independently from the process pressure.
The Linde acetylene recovery process is based on absorption, using DMF (dimethylformamide) as solvent and is accepted by the industry as the leading technology for acetylene recovery.
The average content of acetylene in the furnace effluent stream of an ethylene plant is in the range of 0.3 to 0.9 % by weight. Liquid feedstocks, such as light naphtha, and high cracking severities favour high acetylene yields.
The basic arrangement of the Linde process for the recovery of high purity acetylene includes three major steps as shown in process sketch:
The first column is the acetylene absorber tower, where all acetylene and some ethylene is dissolved after getting in contact with circulating DMF. Rich solvent from the bottom is fed to the ethylene stripper, where ethylene is removed via an overhead stream. This overhead stream is recycled to the cracked gas compressor. The bottom stream of this stripper is DMF, containing all acetylene. The acetylene is then recovered from the DMF as the overhead product in the regeneration tower.
The unit is located upstream the C2 splitter processing the combined C2 stream, containing all acetylene, ethylene and ethane. The process can be applied and has been used in the full pressure range (8 to 20 bar) typical for C2 splitters. The purification efficiency of the ARU is extremely good. Acetylene slip to the product is almost nil (in the order of magnitude of the detection limit of 200 ppb). Recovery rate is therefore 100 %.The Linde ARU process is the leading technology today. Numerous plants, using Linde’s technology are actually producing a total quantity of some 100,000 MTA of acetylene. Beyond these plants there are also a number of ethylene plants, based on ethylene technology of other licensors, using Linde’s ARU process.