[Haichuan: Lessons from Others] Energy-saving renovation of gas valves in CO2 compressors leads to a significant reduction in power consumption

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Recently, after carrying out energy-saving upgrades to the air valves of their carbon dioxide compressors, Hubei Sanning Chemical Co., Ltd. and Shanxi Tianze Group Yongfeng Fertilizer Co., Ltd. found that electricity consumption decreased significantly, and the equipment operated smoothly and reliably. According to statistics, the power consumption of the gas valves in reciprocating compressors accounts for approximately 5% to 20% of the compressor’s shaft power, and it has a significant impact on the compressor’s performance, such as displacement, power, and reliability. During the capacity expansion renovation of the 6MD32-215/146 carbon dioxide compressor by Hubei Sanning Chemical Co., Ltd., the bore diameter of the fifth-stage cylinder was increased from 0170 mm to 0180 mm. After this expansion, the limited effective flow area of the original fifth-stage valves resulted in excessive piston force in that stage of the compressor, causing the piston rod to break. At the same time, the valves consumed too much power, which led to an elevated current in the compressor motor. With the cooperation of Zhejiang Zheou Valve Co., Ltd., a professional valve manufacturer, the effective flow area of the valves was significantly increased by raising the number of flow channels and the stroke length of these valves. As a result, the piston force required to operate the valves was greatly reduced; the piston rods functioned properly over a period of six months without any breaks, and the valves operated in good condition. At the same time, the power consumption of these valves was significantly lowered, extending their service life. The current drawn by the compressor motor decreased by 2A, which improved the reliability of the carbon dioxide compressor operation and reduced the electricity consumption per ton of urea produced. When the urea production system of Yongfeng Fertilizer Co., Ltd., part of Tianze Group, was operating at full capacity, the operating current of the 6MD32-215/146 type carbon dioxide compressors was too high. The company then modified the valves of these compressors. By changing the structure of the valve, increasing the valve flow channel and flow coefficient, raising the valve lift, and properly matching the valve spring force, the effective flow area of the valve is increased and its operating behavior is improved, thereby reducing resistance. As a result, the operating current of the carbon dioxide compressor drops to around 300A, a reduction of 15A–20A. Three days after the modification, the total electricity consumption was 426,672 kWh; this represented a savings of 16,984 kWh compared to before and after the installation of the energy-saving valve, for an average daily savings of 5,661 kWh.