Gas Services – CNG Station

CNG Station

Natural gas is a cleaner alternative to petroleum products, having lesser environmental impact energy. It can be used for industrial or residential heating, power generation, or at compressed natural gas (CNG) refueling stations for vehicular applications.
As far as CNG supply is concerned, the stations receive gas either directly from natural gas pipelines or through mobile cascades, which are essentially a bunch of cylinders mounted on trucks.
Types of CNG stations

For transportation of natural gas within a city, a pipeline is laid from the city gate station where natural gas is pushed at a pressure of 15 bars or even lower. In order to dispense gas to CNG vehicles, there are CNG stations at various locations, where the gas is compressed up to 250 bars initially and then dispensed to vehicles at a pressure of 200 bars. The following are the types of CNG stations:

Online Station
Online stations are directly connected with the natural gas pipeline. At the online station, natural gas is received at a pressure of 19 bars and then compressed up to a pressure of 250 bars with the help of a reciprocating compressor in order to enhance the onboard storage capacity. Thereafter, it is dispensed to vehicles locally through CNG dispensers at a pressure of 200 bars. Typically, a CNG online station consists of the following equipment:

  • CNG compressor
  • CNG dispenser
  • Storage cascade

Mother Station
A mother station is similar to an online station. It has the facility to refuel mobile cascades in addition to the local demand of vehicles. These mobile cascades are then despatched to stations that do not have pipeline connectivity. Mother Station-CNG Station connected with Steel pipeline and having CNG Dispensing and mobile Cascade filling facility

Daughter station
Daughter stations are not connected to natural gas pipelines. At these stations, CNG is transported through mobile cascades at a pressure of 240-250 bars and then dispensed to vehicles through CNG dispensers. In fact, if the CNG compressor stops functioning, a mother/online station acts as a daughter station and dispenses gas from local storage cascades.

Online Station-CNG Station connected with Steel pipeline and having CNG Dispensing only

Daughter Booster Station
CNG is dispensed to vehicles based on the principle of pressure equilibrium. Once the pressure of a mobile cascade drops below 200 bars at daughter stations, vehicles get less amount of gas, which is below 200 bars. With each fill thereafter, the amount of gas dispensed to vehicles starts decreasing and the filling time starts increasing, thereby leaving the customer dissatisfied.

Daughter booster stations address the issue. These are similar to daughter stations. However, in order to cater to customers with regard to the amount of gas dispensed as well as filling time, a booster compressor (hydraulic type with variable suction pressure) is installed in between the mobile storage and the CNG dispenser. The booster compressor increases the pressure above 200 bars once the pressure of the mobile cascade falls below 200 bars. Thus, the maximum amount of gas stored in the mobile cascade is dispensed to the daughter booster station.Daughter Booster Station-Gas is transporting to station on mobile cascade with boosting pressure to dispense CNG
Daughter Station-Gas is reaching to station on mobile cascade and dispense as CNG without boosting of pressure
L-CNG Station-Regasification the LNG through vaporizer and store in cascade to dispense as CNG

Approvals for CNG Station

  • CNG Station Layout preparation.
  • Regulatory approval.
  • Road and Land department approval.
  • Approval from Local Government authority.
  • Consent from Fire, District Supply officer and Traffic Police.
  • NOC from Forest department if applicable.
  • Other NOC from Industrial park, Restricted, Defense, Protected & Archaeological zones if applicable
  • Electrical Safety certificate
  • Air and Water pollution approval
  • Safety studies of the proposed layout.
  • No Objection Certificate from Government.
  • Safety approval.

Construction Process

  • Legal clearance of land like mutation and change of land use
  • Land survey and soil testing
  • Civil construction like fencing, foundation, trenches, Salesroom, basic amenities, driveway, and green area
  • Mechanical work like canopy, pylon, hoarding, tubing, pipeline connectivity, equipment installation and chain link fencing
  • Electrical works like suitable electric load connection, Servo/Automatic Voltage Regulator, Automatic Power Factor Corrector, UPS, electric panel, earth pits, electrical conduiting, earthing arrangement, back up generator preferably Natural Gas driven and lighting arrangement.
  • Station automation, internet, and communication facility.
  • Safety equipment installation like fire extinguisher, safety cones, siren, windsock, Emergency Safety Devices, safety signage, traffic directional markers, SOPs, and check list.
  • Emergency Response plan, Display of emergency nos. like Fire, Ambulance, Police, CGD company personnel.

Commissioning Process

  • Pre-commissioning of all equipment.
  • Safety check.
  • Training to staff.
  • Final commissioning for commercial sale of CNG

cakasaCNG Station