The Technical Innovation Of Overpressure Of L_3.3-17/320-type Compressor And Its Techno-economical Evaluation

L3.3-17/320-type compressor is the core equipment of batch transformation tomake synthesize ammonia by natural gas. It has the advantage of compacted structure and small space-occupancy. But the amount of pumped gas is small, the energy consuming is more, and its running is unbalanced.The gas pressure in the sixth and seventh segments is relatively higher, and its packing seals technique by filling affected. So the sixth and seventh segments applied two-step pistons with the diameters of 82 and 48 to compress gas respectively, using a buffer cave between them to modify the unbalanced force by the gas leakage to the moving parts. The leakage of the gas was led back to the third segment of the compressor by gas-return tube named "SEVENTH BACK TO THIRD". The returned gas showed much higher pressure (about 1.4MPa) than that of the third segment. The pressure at the exits of the third to sixth segments is on the high side, i.e., over-pressure. Thus, the whole pipeline might shake strikingly, and the relief valve often leaked. It led to a large quantity of maintaining work, which increased the hidden troubles of safety and manufacturing cost simultaneously. On the other hand, over-pressure might lead the electromotor to keep higher current for a long time, even destroy it. Thus, the energy consuming increased. In order to overcome the above, the structures of the sixth and seventh segments must beredesigned.In this work, the second was chosen after the comparisons of plan I and plan II. Plan I is to expand the volume in turn to decrease the pressure, and plan II is to fully reconstruct the structures of the sixth and seventh segments to decrease the pressure. Finally, plan II was chosen. The key technique from Shenyang Compressor Research Institute was adopted. Our factory invested 260,000 yuan to redesign the sixth and seventh segments, re-choose the accessories of the pistons and sealing filler and other parts, and cancel the balanced cave and gas-return tube.Two years after the technique modification, the compressor still runs well, and the following were achieved:As far as the technical targets are concerned, the troubles caused by over-pressure were solved completely. The pressure at the exits of the third to sixth segments of the compressor was decreased by 25%, 28.5%, 6.5% and 17% respectively. The maximum current-decrease of the motors among five electromotor groups reached 110A, and the minimum one also got to 50A. Thus, the life of the motors was prolonged.The economic indexes show large energy-consuming decrease was achieved, and about ?20,000 yuan electric fares are saved annually. Fitting consuming has decreased by 14,000 yuan per year. Maintaining cost has decreased by over 50,000 yuan annually. The scheduled target to take back the investing within 6 months after the technical modification has been realized.Also, as far as the safety is concerned, the solution of over-pressure made the hidden troubles of safety caused by compressive containers and the aging of the equipments stopped. Thus, safeguard was provided to over 20,000 citizens living in the cultural zone. At the same time, the purpose of safe manufacturing is guaranteed.