Shaodan Linfeng Fine Chemical Co., Ltd. and Southwest Chemical Research Institute jointly launched a PSA-CO unit with a capacity of 10 m³ (N)/h (N represents the standard volume at 25℃ and one atmosphere). Purified CO is used as raw material to supply the downstream processes. The equipment selected is a Sichuan Zigong Z-2/L60 type hydrogen compressor. 1. Process Flow In our actual process, this compressor is somewhat large, especially since the downstream processes use a smaller amount. The process flow is shown in Figure 1. [align=center] Figure 1 Process Flow[/align] When the PSA system is running, it produces 100 m³ (N) of CO per hour. The downstream reactor only uses 606710 m³ (N)/h, leaving a surplus of 406710 m³ (N) per hour. Given this situation, we added a large storage tank to store the remaining 40 m³ (N) CO per hour. The tank has a volume of 256,710 m³ (N) and a pressure of 3.0 MPa, yielding 7,506,710 m³ (N) CO when full. When the PSA-CO tank is full, the PSA-CO unit and upstream systems are all shut down. Only the compressor (type 2-2/60) is used to extract CO from the large tank and supply it to downstream processes, providing continuous operation for 12.5 hours. This system is called the PSA auxiliary unit. The average daily operating time for the PSA-CO unit is 14.4 hours, and for the PSA auxiliary unit, it is 9.6 hours. The greatest power waste occurs during the operation of the auxiliary unit. 2. Economic Benefits of Applying Frequency Converters Since applying frequency converters in January 1999, we have experienced significant economic benefits. Previously, flow control relied on inlet valves, which could save some electricity consumption, but the savings were meager, not to mention the effort required for control. When the inlet pressure was high, each stage was over-pressured; when the inlet pressure was low, it had a great impact on the valve plates and springs of each stage of valves. Advantages of using frequency converters: (1) Convenient and simple adjustment, directly operated in the control room; (2) After reducing the speed, the service life of the motor is extended; (3) After reducing the speed, the service life of the compressor valves (valve plates, springs), crankshaft, connecting rod large and small end bearings and piston rings is extended; (4) The failure rate of electrical components such as distribution cabinets has been zero for two years; (5) The gas pipelines of Z-2/160 compressors are all inside the water jacket. Previously, the copper pipes leaked due to vibration, but after reducing the speed, there has been no leakage (previously, the copper pipes had to be repaired three or four times a year, but after reducing the speed, there has been no leakage for three years); (6) Save electricity. According to literature [1], the motor power is proportional to the cube of the motor speed, and frequency conversion can save electricity. See Figure 2 for a detailed analysis. [align=center]Figure 2 Relationship between gas production and power consumption[/align] When the gas production is 10 m³ (N)/h, the measured current is 57A; when it is 9010 m³ (N)/h, the measured current is 53A. After applying the frequency converter, when the gas production is 10 m³ (N)/h, the current is only 35A, a reduction of 85%; when the gas production is 6710 m³ (N)/h, the current is 9.275A, a reduction of 56%. During the operation of the auxiliary device, due to the large size of the compressor, the minimum gas production is 906710 m³ (N)/h, with 306710 m³ (N)/h remaining and returning to the storage tank. When the PSA system is running, 106710 m³ (N)/h of CO gas needs to be extracted, part of which goes into the CO storage tank and the other part into the reactor. However, when the PSA is not running, CO gas is extracted from the storage tank. When the auxiliary unit is running, the equipment cannot be controlled to 676710 m³ (N)/h. Therefore, only frequency conversion can reduce the efficiency to the minimum. Specific power saving calculation: PSA-CO unit running (30 days a year, 14.4 hours per day): PSA auxiliary unit running (9.6 hours per day, 30 days a year): Conclusion In summary, the application of frequency converters in compressors not only simplifies operation and extends the service life of vulnerable parts, but also saves a significant amount of electricity. Considering that a large amount of CO raw material is carried out during continuous discharge from the reactor in the downstream section, we also plan to add frequency converters to pressure transmitters to implement intermittent feeding and achieve the goal of saving raw materials.