Overview of a Micro LNG Plant
An LNG plant consists of 4 main unit operations:
- front end clean up of the feed gas
- refrigeration cycle
- cold box
- storage
The front end clean up removes key impurities from the feed gas, typically this operation removes CO2, sulphur compounds and moisture. Then the refrigeration cycle produces the cold which liquefies the natural gas to LNG. The cold box houses the heat exchanger in which the refrigeration cycle liquefies the gas. The LNG is stored in lightly-pressurised vacuum insulated tanks, ready to be transported to wherever it is required.
Micro LNG Plant – a first in Australia
In order to find a cost effective solution for the trucking industry, BOC has found a way to build a micro LNG plant (50 tonnes a day and less) at the same price per tonne as small scale plants (200 tonnes per day).
50 tonnes of LNG per day is equivalent to 70,000 litres of diesel, which can provide fuel for 125 heavy duty trucks. The micro LNG plant operation is also scalable down to as little as 16 tonnes per day for smaller fleet operations.
Using an existing patent purchased from the Gas Technology Institute (GTI) in the USA, BOC’s research and development team worked jointly with GTI. They refined the technology and developed the mixed refrigerant cycle to allow micro LNG production of up to 50 tonnes per day. BOC now owns an exclusive global licence to GTI technology patents and know-how.
Refuelling Stations
BOC’s sister company, Cryostar, is an expert in the design and build of refuelling stations for dispensing of LNG and CNG. All the LNG refuelling stations for Tasmania and the BOC east coast heavy duty transport network will be supplied by Cryostar.
Storage Tank
A refuelling station contains a cryogenic storage tank that is refilled from an LNG tanker. The storage tanks are equipped with level and pressure transmitters, in order to monitor the state of the tank in real time.
Station Control System
The LNG refuelling station’s sophisticated remote control centre means that there is no requirement for the station to be manned.
LNG Dispenser
Using the LNG dispenser is similar to using a conventional diesel bowser. The dispensers are fitted with a “Weights and Measures” approved flow meter to ensure high precision weight measurement, independent to the natural gas density. Methane emissions are kept to a minimum by using a unique vent gas recovery system incorporating a single fuelling connector and hose. Additionally, the dispensers are connected to the main pumping skid by vacuum insulated lines that allow minimal gas loss.
Payment
The refuelling payment system is connected to the station’s control system. It immediately activates all parts of the station when the user swipes their card in the system. The system is configured with a magnetic card payment, enabling the creation of a monthly invoice for each fleet operator.
How to Use the Refuelling Station
The refuelling station is very straightforward for drivers to use and comprises just a few simple steps:
- Drive vehicle into refuelling station
- Swipe card in reader
- Enter pin number to identify driver
- Input odometer reading to enable accurate fuel management system readings
- Select "fuel filling process" (duel or single hose according to engine type)
- Connect hose
- Once hose is connected, press fill button
- A green light shows when tank is full
- Disconnect hose
- A date and time stamp with number of kilograms of fuel is issued.
- Refuelling is complete