Abstract
A single-screw expander with 195 mm diameter is developed to recover pressure energy in letdown stations. An experiment system is established using compressed air as a working fluid instead of natural gas. Experiments are conducted via measurements for important parameters, such as inlet and outlet temperature and pressure, volume flow rate and power output. The influence of inlet pressure and rotational speed on the performance are also analyzed. Results indicate that the single-screw expander achieved good output characteristics, in which 2800 rpm is considered the best working speed. The maximum volumetric efficiency, isentropic efficiency, overall efficiency, and the lowest air-consumption are 51.1 kW, 83.5%, 66.4%, 62.2%, and 44.1 kg/(kW·h), respectively. If a single-screw expander is adopted in a pressure energy recovery system applied in a certain domestic natural gas letdown station, the isentropic efficiency of the single-screw expander and overall efficiency of the system are found to be 66.4% and 62.2%, respectively. Then the system performances are predicted, in which the lowest methane consumption is 27.3 kg/(kW·h). The installed capacity is estimated as 204.7 kW, and the annual power generation is 43.3 MWh. In the next stage, a pressure energy recovery demonstration project that recycles natural gas will be established within China, with the single-screw expander serving as the power machine.
Highlights
With the development of the national economy, the demand on energy supply is increasing by 10% annually [1]
It shows that the best performance of single-screw expander happens correspondingly, which leads to the increase of outlet temperature, and the isentropic efficiency at 2800 rpm, at which thebest irreversible loss achieves at the minimum
The following hypotheses are adopted in the analysis of the natural gas pressure energy The following hypotheses are adopted in the analysis of the natural gas pressure energy recovery system: recovery system: (1) The natural gas can be defined as pure methane because of the high concentration of methane
Summary
With the development of the national economy, the demand on energy supply is increasing by 10% annually [1]. Normal applications include natural gas processing, petrochemical processing, air separation, pressure letdown, waste heat recovery, geothermal power generation, cryogenic refrigeration, dew point control and simulation of high altitude atmospheric conditions for turbine engine test cells [25]. The single-screw expander can realize 1~200 kW power output range, and it is more suitable for small scale pressure energy and low temperature recovery systems. Air Through current dynamometer for the load, the power output was the Compressed atataeddy flow rate with different pressures from the storage tanktank and and entered the single-screw expander by adjusting the inlet valve.
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