Method of supplying hydrogen to the gas transmission system (GTS)

The characteristics of hydrogen-containing gases (HG) depend on the hydrogen content in the fuel gas. Identification of these dependencies is necessary to determine the parameters of fuel gas preparation points for gas turbine installations. Embedding a hydrogen pipeline directly into a natural gas pipeline has the following disadvantages: Inability to control and regulate the concentration of hydrogen in a mixture of natural gas and hydrogen; Possible hydrogen embrittlement of the gas pipeline metal in the hydrogen supply zone, which may lead to the destruction of the gas pipeline; Gazprom's requirements prohibit the supply of gas to a gas pipeline with a calorific value below 31.8 MJ/nm3 (the calorific value of hydrogen is 10 MJ/nm3).

Therefore, the following method is proposed for supplying hydrogen to the gas transmission system:

General technical description:

• To organize the mixing of hydrogen with natural gas in order to ensure the calorific value of the mixture is not lower than 31.8 MJ / nm3, it is proposed to carry out a fireless tapping of the gas pipeline-outlet into the main gas pipeline.

• The gas pipeline-branch is laid parallel to the main gas pipeline.

• The internal diameter of the gas pipeline outlet is determined by calculation depending on the flow rate of hydrogen and the pressure of natural gas in the main gas pipeline.

• Shut-off valves are installed at the inlet and outlet of the gas pipeline outlet. With the help of shut-off valves, a reliable termination of the natural gas supply is ensured
• Pressure sensors are installed to determine the gas pressure at the inlet and outlet of the gas pipeline outlet.
• To determine the heat of combustion of the methane-hydrogen mixture, a calorimeter is installed at the outlet of the gas pipeline outlet.
• A safety valve is installed at the outlet of the outlet gas pipeline to prevent exceeding the design pressure of the gas.
• A shut-off valve, a safety valve, a flow meter, a pressure regulator, pressure and temperature sensors are installed on the hydrogen pipeline.

The inner diameter of the hydrogen pipeline is determined based on the following conditions:

A) the calculated flow rate of hydrogen

B) gas pressure in the main gas pipeline

A mixing intensifier (mixer) is installed inside the gas pipeline after the hydrogen-natural gas mixing unit to ensure the homogeneity of the methane-hydrogen mixture at the point of measurement of the heat of combustion. The hydrogen and natural gas mixing intensifier makes it possible to reduce the length of the discharge gas pipeline from the hydrogen supply point to the calorimeter placement point, as well as to avoid possible hydrogen embrittlement of the discharge gas pipeline in the section from the mixing intensifier to the insertion of the discharge gas pipeline into the main gas pipeline.

To compensate for the decrease in the pressure drop on the hydrogen supply system in the GTS, the hydrogen supply must be carried out at an acute angle to the gas pipeline outlet in the direction of the gas flow.

The hydrogen supply system in the GTU is equipped with a system of automatic regulation of pressure and flow of hydrogen, depending on the pressure and flow of natural gas in the main gas pipeline.