Abstract:

After the revamping and expansion of a 1 100 kt/a ethylene plant of SINOPEC, the energy consumption of propylene refrigeration compressor unit exceeded the design value, and the heat loads of each stage were mismatched. High liquid level was observed on the ethylene side of ethylene product vaporizer. In order to lower the liquid level, an appropriate opening was set for the anti-surge valve on the pipeline from the 4^th stage to the 3^rd stage of propylene refrigeration compressor to increase the flow rate and temperature on the refrigerant side. However, this method further increased the load of the propylene refrigeration compressor unit, limited the further capacity expansion of the plant, and reduced the margin of the anti-surge valve, bringing hidden danger of tripping. ASPEN PLUS was used to build a propylene refrigeration compressor unit model from the process point of view, and the process parameters of each stage and the heat loads of each user were simulated and compared with design values. HTRI was used to build an ethylene product vaporizer model from the equipment point of view. The reasons for high liquid level were analyzed, and some optimization measures were proposed based on the actual situations for reducing the opening of anti-surge valve and the power consumption of propylene refrigeration compressor unit.

Key words: ethylene plant, propylene refrigeration compressor unit, anti-surge, energy consumption