Energinet.dk’s natural gas facilities consist of 800 km of large-dimensioned steel gas pipelines, 42 meter and regulator (M/R) stations and 4 meter stations.
Meter and regulator stations
The M/R stations have been established alongside the transmission pipelines. Their main functions are:
- Reducing the gas pressure to the distribution grid’s level of operation
- Metering the gas flow through the station
- Adding odorant to the gas.
The M/R stations are designed to ensure that the distribution grid pipelines and equipment are not subjected to over-pressure.
Valve stations have been established in connection with the branching-off from all stations, and some stations are fitted with scraper installations. Via the scraper installations, a so-called ‘intelligent pig’ can be sent into the pipelines.
All stations are connected to the control centre via the SCADA system, ensuring access to the continuous display of essential functions, remote control of regulator set points and remote control of the stations’ outlet valves.
How the meter and regulator station works
Natural gas under pressure – up to 80 bar – is fed into the M/R station, filtered and preheated in a heat exchanger. The pressure is lowered to 40 or 19 atmospheres by a regulator. The volume of natural gas is also metered at the M/R station.
The M/R stations are normally unmanned, but they are monitored 24/7 from Energinet.dk’s control centre in Egtved and are regularly inspected.
During daily operation, an M/R station emits a faint noise. The noise stems from the regulator and is muffled by the building. Outside the station, the noise can be heard as a gentle humming.
During inspections etc. of the M/R stations, natural gas is blown off to the atmosphere. This means that a limited volume of natural gas at the installation is released via a valve. The blow-off can be heard as short, strong whistling sounds.
Heating of gas
The temperature of the gas drops as a side-effect when the pressure is reduced. To prevent the formation of deposits that may damage the pipelines, the gas is heated in a natural gas boiler. The boiler emits ‘smoke’ like a normal natural gas-fired boiler in a large house. The ‘smoke’, seen as white steam, is pure water vapour.
Odorant is added
Natural gas is odourless. Immediately before the natural gas leaves the station, a very strong odorant is added so that consumers can smell any gas leaking from pipes or installations. The odorant is stored in drums at the M/R stations, and the drums are replaced when they are nearly empty. In rare cases, replacing the drums can briefly produce an unpleasant smell outside the station. The smell is similar to that of bottled gas but is safe to inhale outside the M/R station.