System and component solutions, to significant reduction off oil-fouling in ammonia refrigeration plants - Part 1

摘要

Apart from the occasional special application, oil is used to lubricate all refrigeration compressors.rnAn annoying side effect of this is that oil residues enter the plant with the compressed gas, inrnvapour and liquid form. This oil will contaminate the heat exchanger present, with a negativernimpact on performance and operation. This article presents a few ideas on how simple installationrnand/or adjustment of components can significantly reduce the oil concentration and thereforernincrease the operation and performance of the refrigeration plant.rnThe theory of how the oil film builds up with ring flow is explained, based on the boundary layerrn[2, 3], theory, and several practical equations are developed. There is a concrete example forrncalculation the average oil film thickness in a DX evaporator pipe.rnA reduction of the contaminating influence of the lubricating oil in the refrigeration plant isrndescribed for soluble oil, and in more details for insoluble oil such as the cases at the ammoniarnplants. The reduction of oil concentration in the ammonia plants is elaborated in several ideas: byrnchoosing a compressor with low oil consumption, using a high-efficiency oil separator, using arncompressed gas cooler for the oil separator, choosing proper oil type, arranging the liquid tankrnwhere the oil can settle and be returned to the compressor, using intermediate tank at 2-stage plants,rnby regularly draining off the oil, automatically or otherwise.