Home Grown Quality

to petroleum products, having less environmental impact. Until electric cars become affordable, the Indian government is supporting the adoption of CNG vehicles. 

Quoting a report from Nomura, the Economic Times of India said that if the required infrastructure is put in place by the government over the next decade, natural gas vehicles could account for one out of every two vehicles sold in India by 2030.

The Natural Gas Infrastructure Development Plan will see 10,000 CNG stations set up over the next 10 years, growing from the 1,424 that existed in April 2018. 

Meeting critical conditions

Trelleborg Sealing Solutions in India has been a sealing partner of leading Hydraulic Cylinder Manufacturers for decades. 

“Our engineers discussed the application challenges with their design team,” says Sunil Kalamdani, Head-Application Engineering and Technical Services. “We had to find a way to seal CNG at high pressure on one side and hydraulic oil on other. My team knew the working conditions were critical and suggested a complete sealing system incorporating a variety of seals in our proprietary Turcon® perfluoroelastomer (PTFE) based materials along with elastomer O-Rings and Back up Rings.”

Successful tests

Two sets of seals were supplied for validation, which the customer installed in cylinders to the Trelleborg Sealing Solutions specification. After four months of successful running in the Tulsa Gas Application, Tulsa Gas were pleased with the results.

Pradyumna Pati, Head Sales- South says: “Tulsa Gas is very happy due the cost saving achieved from localized supply, improved delivery time, the performance of the cylinder as well as us, as its local supplier.”

Transportation of natural gas within a city is achieved by laying a pipeline from the City Gate Station where natural gas is pushed through the pipeline 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:

1. ONLINE STATION – Online stations are directly connected with the natural gas pipeline.
2. MOTHER STATION – Similar to an online station, in addition to filling local vehicle demand, the facility can refuel mobile cascades that are dispatched to stations which are not connected to a pipeline.
3. 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.
4. DAUGHTER BOOSTER STATION – Once the pressure of a mobile cascade drops below 200 bars at a Daughter Station, vehicles receive less gas. With each fill thereafter, the amount of gas dispensed to vehicles starts decreasing and filling time starts increasing.
   Daughter Booster Stations address the issue as they include a hydraulic booster compressor with variable suction pressure. The booster compressor increases the pressure above 200 bars once the pressure of the mobile cascade falls below 200 bars to maintain the speed of gas delivery from the CNG dispenser.

CNG is comprised mostly of methane gas that, like gasoline, produces engine power when mixed with air and is fed into an engine's combustion chamber. CNG is compressed to less than one percent of the volume it occupies at standard atmospheric pressure. This allows enough fuel to be stored in a vehicle to extend the driving range to match that of a vehicle powered by gasoline.

The fuel is used in traditional gasoline/internal combustion engine automobiles that have been modified, or in vehicles which are manufactured for CNG use, either alone ('dedicated'), with a segregated
gasoline system to extend range (dual fuel) or in conjunction with another fuel such as diesel (bi-fuel). The cost and placement of fuel storage tanks has been the major barrier to wider and quicker
adoption of CNG as a fuel. 

CNG is seen as an environmentally friendly fuel as it emits significantly less pollution than gasoline or oil when combusted. For example, an engine running on gasoline for 100 kilometers emits 22 kilograms of CO2, while covering the same distance on CNG, only 16.3 kilograms of CO2 are emitted.

The booster compressor used in the Daughter Booster CNG Station is a two-stage hydraulic gas compressor that discharges CNG at between 200 and 250 bar. The natural gas coming from the  network is filtered, and then sucked into the chamber of the first stage through two inputs located at the top and bottom of the cylinder, inside of which it is compressed by the reciprocating movement
of the piston. The compressed gas exits from the cylinder at the discharge pressure through two outputs, one at the bottom and the other at the top.

The gas, compressed in the first cylinder, enters the second stage chamber to undergo a second compression. From the cylinder, after having passed through the second heat exchanger, it is sent to for use at high pressure of 200 to 250 bar.

The sealing system from Trelleborg Sealing Solutions seals CNG at high pressure on one side of the hydraulic piston and hydraulic oil on other. The configuration specified and successfully proved includes a Turcon® AQ seal, Turcon® Stepseal in M12 compound, Turcon® Glyd Ring® T in T10 material, Zurcon® Slydring® in T51, as well as O-Rings and Back up Rings.