Natural gas compression energy saving technology of CNG (compressed natural gas) station

Abstract

The invention relates to a natural gas compression energy saving technology of a CNG (compressed natural gas) station, which can improve the technological level of a compression system so that a CNG compressor can run in an economical and energy-saving manner. The technical scheme comprises the steps of firstly inputting feed gas into a heat exchanger for precooling, wherein the cold for precooling the feed gas is obtained by the throttling and pressure reduction of dry gas by a J-T valve; then inputting the feed gas into a separator to remove free water and condensate impurities; inputting the feed gas after shallow dehydration into a compressor to gradually increase the pressure to 22-25MPa; cooling and separating the output gas of the compression cylinder of each level by the cooling separator of each level; finally inputting the gas into a fine filter to filter the mechanical impurities, and then inputting the gas into a deep dehydration system for dehydration to obtain a finished product of compressed natural gas; driving the compressor with a variable-frequency motor; inputting the cooling water into an electromagnetic descaling machine for softening treatment; regulating the opening of the regulating valve of each level in real time by a temperature control system so as to control the quantity of water entering the cooling separator of each level. By adopting the technology provided by the invention, the energy waste is avoided, the efficiency of the CNG compressor system is improved, and the operation cost of the compression system of the CNG station is reduced.

Description

technical field [0001] The invention relates to a natural gas compression and energy-saving process for a CNG filling station used in the natural gas treatment and processing industry. Background technique [0002] A CNG refueling station generally consists of six systems, namely a pretreatment system, a compression system, a drying system, a control system, a storage system and a gas sales system. As the core part of the CNG filling station, the compression system mainly includes intake buffer, compressor unit, unit lubrication system, cooling system, oil removal system and control system. The energy consumption of the compressor unit accounts for more than 80% of the entire CNG filling station. . my country's CNG technology started late, the process flow is not reasonable, and the overall performance of the CNG compressor is not good enough, resulting in problems such as high energy consumption, low efficiency, and high operating costs of the system, which has brought hug...

AI Technical Summary

Problems solved by technology

The existing problems of the water-cooled cooling system are as follows: (1) In the prior art, the circulating cooling water from the cooling water tower is evenly distributed from the coolers at all levels. Due to the different compression ratios and exhaust temperatures of the compression cylinders at each level, the cooling at each level The effects are not the same, and the complete cooling effect of back cooling is not realized, which increases the energy consumption of the compressor; (2) Due to the high temperature, the cooling water is easy to scale during operation. Inject corrosion and scale inhibitors to soften cooling water to reduce Ca 2+ , Mg 2+ Concentration, to ensure the stability of cooling water, if the addition time or dosage of corrosion and scale inhibitors is unreasonable, it will cause water hardening, scaling and other phenomena. Scaling increases the flow resistance of cooling water, because scale is a poor conductor of heat It will greatly reduce the heat transfer efficiency, and at the same time, the deposition of scale will cause local corrosion of equipment and pipelines; (3) Long-term use of scale inhibitors will deteriorate the water quality of cooling water, and the cooling water needs to be cleaned regularly. increased operating costs

When the motor starts and stops, it will generate a current shock instantly, which will have a bad influence on electrical and mechanical equipment

Since the power required for the motor to start with no load is roughly equivalent to 2 to 3 times the power when it is fully loaded, this consumes a lot of energy for compressors that are frequently started. In addition, the gas source of the CNG filling station is unstable, and the supply is in short supply. , low air supply pressure and other factors, there will be a situation where the shaft power of the compressor does not match the power of the motor

Images