At a gas distribution station, natural gas arrives under pressure of several megapascals, and its pressure must be significantly reduced before reaching the consumer. Samara State Technical University has patented a method for GDS operation in which the energy from the pressure drop is used to generate electricity. The scheme uses a turbodetander connected to an electric generator and an electric heater for the intermediate coolant.
In the proposed scheme, natural gas with a pressure of 6.5–7.5 MPa first enters a heater with an intermediate coolant. The gas is heated to 80–100 °C, after which it is directed to a turbodetander. During expansion, the flow rotates a turbine, which in turn drives an electric generator.
After the turbodetander, the gas pressure drops to approximately 1.2–1.3 MPa, then a regulator brings it to 1.1–1.2 MPa before supplying it to consumers. The electricity from the generator is proposed to be divided into two streams: the larger part is supplied to the external grid, and the smaller part is used for electric heating of the intermediate coolant. As a result, gas heating in operating mode does not require burning natural gas in the heater.
The description of an earlier patent RU 2 822 331 C1, which SamGTU cites as a prototype, considered a GDS with a gas flow rate of 30–50 thousand Nm³/h and a pressure drop from 7 to 1.2 MPa; for such a mode, the electrical power was estimated at up to 2–2.5 MW.
The scheme also has a technical limitation: the turbodetander and generator require maintenance. For this period, the patent provides for the shutdown of the turbodetander section and direct supply of high-pressure gas to the regulator. In this case, the electric heater for the intermediate coolant is switched to power from the external electrical grid, so the new method allows for the elimination of natural gas combustion in the heater even during maintenance of the turbodetander and generator.