Gas grid connection unit

Compact solution for biomethane injection into the gas grid or its transportation to the final point of biomethane utilization.

Grid injection unit – biomethane injection into the natural gas grid

For biomethane grid injection, Biovoima has developed its own container-based solution that accurately regulates the pressure of the biomethane according to the gas network requirements and then injects it to the gas grid. The grid connection unit also enables gas odorization and the measurement of the quality and quantity of commercial gas supplied as well as the billing of the network company on that basis.

Biomethane can be injected into the gas grid immediately after the biogas upgrading, or if the gas grid passes far from the biogas plant, the biomethane can be transported there either by a pipeline or a high pressure gas transportation container. Grid connection unit can also be used for gas pressure reduction in applications other than gas grid injection.

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Grid injection unit – biomethane injection into the natural gas grid

The gas grid connection unit is built into a compact 10 ft shipping container.

Biomethane grid injection – how does it work?

  1. Raw biogas is upgraded to biomethane with an upgrading technology. After the upgrading, the biogas is nearly equal to pure methane meaning that is has the same characteristics as natural gas.
  2. The produced biomethane is passed on to the gas grid connection unit with a pipeline or a gas transportation container.
  3. Then, the pressure of the biomethane is accurately adjusted to meet the requirements of the local natural gas grid. The normal pressure of the gas transported by the pipeline is 4-12 bar and the pressure of the gas brought in the transportation container is 200-300 bar. The gas grid pressure, in turn, is 4-60 bar, depending on the type of line. Whenever gas pressure is reduced across a pressure relief unit, its temperature is also reduced. Hence, the pressure relief unit is heated when large pressure differences occur.
  4. The gas flow is measured to enable amount-based invoicing of the grid owner or the end customer.
  5. The gas is odorized, if it has not been made at the biogas upgrading stage.
  6. Finally, biomethane is injected into the natural gas grid.

Factory-made compact solution

The gas grid connection unit is a factory-made solution built into a compact 10 ft shipping container, which is almost completely standardized. The size of the piping, the pressure control components and the accessories of the container are selected based on project specifications  such as how the gas is brought to the container, what is the gas grid pressure and how much gas can flow through the container.

In addition, the gas grid connection unit can be equipped with the following additional equipment:

  • Gas chromatograph that is used to accurately measure the composition of a gas. It is often used in situations where the gas quality requirements are precise, or if the gas upgrading unit’s quality measurement is incomplete. Gas that is evaluated to be of poor quality can be returned to the upgrading unit via automation, or alternatively passed on to a torch where it will be burned.
  • A gas odorization that is installed if the gas has not yet been odorized during upgrading. There are several odorization options and often the grid owner has requirements for this. The most common odorant is THT (tetrahydrothiophene).
  • Auxiliary input connectors NGV1 or NGV2.
  • Customer’s logo to decorate the facade.
  • Flow meter (also available remote flow meter). In simple projects (e.g. gas transportation to the burner), the flow meter can be omitted.

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Gas grid connection unit is suitable for heating centers and industrial projects

A gas grid connection unit can also be used for pressure reduction in applications other than the grid injection. With the help of the gas grid connection unit 250 bar gas transportation container’s pressure can be reduced to suit the pressure requirements of a customer’s gas burner or industrial process. For example, it enables the use of biogas as a backup fuel for a district heating plant. With minor modifications, the gas grid connection unit can also be adjusted to extract the gas from the natural gas grid and supply it to the final point of gas utilization.

 

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