Energy-efficient Operation Strategy for Air Compressor and Cooling Tower System

摘要

The compressed air consumption in CSC is about 200,000 Nm3/hr, and the annual power consumption is about 250 million kWh, accounting for 5% of the company's total consumption. Improving the efficiency of the air compressor systems is an important issue for energy conservation. The Multi-stage centrifugal air compressor is the most common type of air compressor in CSC. Theoretical analysis shows that decreasing outlet air temperature of the inter-cooler can reduce compressor energy consumption. However, the cost is that it increases the energy consumption of the cooling tower. Therefore, the overall system's (air compressor and cooling tower) energy consumption must be considered. First, the relationship between energy consumption of the air compressor and the cooling water temperature of the intercooler was confirmed by the ASPEN simulation. Then, the previous research results showed that the relationship between the energy consumption of the cooling tower and outlet cooling water temperature. The cooling water temperature setting can be calculated from cooling tower and air compressor energy models. Simulation results show that reducing the cooling water temperature by 4°C, the compressor energy consumption is reduced by about 1%. However, considering the energy consumption required reducing the cooling water temperature, the overall system energy consumption can be reduced by 0.8%. The plant test in CSC #2 and #3 compressed air stations show that reducing the cooling water temperature by 5°C, the system energy consumption is reduced by about 1%. Therefore the annual electricity saving is about 300,000 kWh. The test results of the cooling tower system of DSC oxygen plant also show that the low cooling water temperature operation can improve the energy consumption by 1.5% and save about 1 million kWh.