A Case Study of the Supercritical CO2-Brayton Cycle at a Natural Gas Compression Station

Abstract

Heat losses caused by the operation of compressor units are a key problem in the energy efficiency improvement of the natural gas compression station operation. Currently, waste heat recovery technologies are expensive and have low efficiency. One of these technologies is organic Rankine cycle (ORC) which is often analyzed in scientific works. In this paper, the authors decided to investigate another technology that allows for the usage of the exhaust waste energy—the supercritical Brayton cycle with CO2 (S-CO2). With a thermodynamic model development of S-CO2, the authors preformed a case study of the potential S-CO2 system at the gas compressor station with the reciprocating engines. By comparing the values of selected S-CO2 efficiency indicators with ORC efficiency indicators at the same natural gas compression station, the authors tried to determine which technology would be better to use at the considered installation. Investigations on parameter change impacts on the system operation (e.g., turbine inlet pressure or exhaust gas cooling temperatures) allowed to determine the direction for further analysis of the S-CO2 usage at the gas compressor station. When waste heat management is considered, priority should be given to its maximum recovery and cost-effectiveness.

Thermodynamic Modelling, Technical and Operational Issues of Supercritical Carbon Dioxide Power Generation Cycles for Industrial Applications: A Literature Review

“…The work of Niu et al (Niu et al, 2022) unveiled that the thermal and exergy efficiencies of the electricity production cycle, operating with the CO 2 -propane mixture, escalated respectively by 2.34% and 1.51%compared to that of S-CO 2 in the same operating condition. S-CO 2 cycles typically cater to heat source temperatures surpassing 300°C (Kowalski et al, 2020). The diagram showcasing the high-temperature S-CO 2 cycles mimics Figure 3, albeit with the substitution of a compressor and a chiller for the pump and condenser, respectively.…”

“…The heat source temperature of these systems plummets below 300°C. Low-temperature systems can function in a transcritical cycle (Kowalski et al, 2020). The cycle comprises an expansive turbine, a heat exchanger, an optional heat recuperator, a pump, and a condenser.…”

Step by Step Derivation of the Optimum Multistage Compression Ratio and an Application Case

“…However, this is not possible, so large compressions from a given to a much higher , are split in smaller stages: one stage compresses the gas at a certain intermediate pressure; it is then cooled and sent to the inlet of the next, and the process is repeated until . Although it is not ideal, the savings of multistage compression can be huge [ 6 ], depending on the number of stages into which the total compression is split, and how the total pressure ratio, , is shared between them. The former might be given by economics; the latter is a technical issue and will be assessed here.…”