Gas Engines
Bi-Fuel System
Overview
Applications & Key Technologies
Gaseous Fuel System
Overview
Gas Operating Characteristics
Gas Supply
Gas Control Components
Gas Installation
Gas Commissioning
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Fuel Savings Calculation
Glossary
Conversion
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Gaseous Fuel Systems
Applications
Compatible Fuel Types
Gaseous Fuel System Models
Gas Delivery System
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Gaseous Fuel System
The Gaseous Fuel System is a retrofit technology that allows diesel engines
to operate on a mixture of diesel fuel and natural gas. This is achieved through
the use of proprietary and patented technologies that are installed externally of the
engine.
Conversion requires no modifications of the engine and allows the engine
to operate on gas mixtures ranging from 50% to over 70% of total fuel consumed. After
conversion, the engine can still be operated on 100% diesel fuel without loss of
power or efficiency.
The Gaseous Fuel System has been designed to allow for
switching of fuel modes during full or part load conditions, without
interruption in engine speed, power or stability.
The Gaseous Fuel System
utilizes a fumigation gas delivery method whereby gas is delivered to the
cylinders via the standard engine air-intake system and is then ignited by a
diesel "pilot" which acts as an ignition source for the air-gas mixture.
Applications
The Gaseous Fuel System has been designed for variable or constant speed,
on/off- road applications such as heavy-duty trucks, refuse haulers, passenger
buses and earth moving equipment.
Compatible Fuel Types
The Gaseous Fuel System is compatible with methane-based fuels such as
Compressed Natural Gas (CNG) and Liquid Natural Gas (LNG).
Hydrocarbon gasses
such as propane and butane are not compatible with Gaseous Fuel operation (in
pure form) due to unfavorable combustion characteristics of these fuels.
Gas
quality and composition are critical factors for Gaseous Fuel operation, as
"pipeline quality" natural gas can have drastically different properties from
location to location, as well from season to season.
Ideally, pipeline supplied gas will have a high concentration of methane and
a low overall concentration of heavier hydrocarbon gasses. For lower quality
gasses (pipeline supplied or other), reductions in engine performance and/or gas
substitution rate may be required.
Gaseous Fuel System Models
The Gaseous Fuel System has been designed as a scaleable technology that can be
adapted to various engine sizes.
The Gaseous Fuel System is typically applied to
high speed diesel engines ranging in size from 100 horsepower to over 500
horsepower (75kW to over 370 kW). The Gaseous Fuel System is offered in multiple
models depending on engine air-intake size, operating gas pressure and method of
diesel fuel control.
Standard models include:
- one (1) air-gas mixer in either 4",
5" or 6" (101.6, 127 and 152.4 mm) outside diameters,
- one (1) electronic
controller configured for 2,400 psi, 3,000 psi or 3,600 psi CNG supply pressure
(165 bar, 206 bar or 247 bar)
- one (1) diesel fuel controller consisting of
either a diesel control valve (DCV) or aneroid control valve (ACV).
Gaseous Fuel
System model designations describe the specification of the kit, including type
of diesel fuel control (aneroid control valve or diesel control valve), quantity
and size of air-gas mixer and CNG operating pressure.
For example, the model
A15-30 designates a kit specified for aneroid fuel control, one 5" (127 mm)
air-gas mixer and 3,000 psi (206 bar) CNG operating pressure.
Gas Delivery System
The Gaseous Fuel System utilizes a vacuum-based gas control scheme, whereby
changes in combustion airflow result in a corresponding change of gas supplied
to the engine. The gas is supplied to the engine with the use of a specialized
"gas train" and proprietary air-gas mixing device (mixer).
The mixer is
installed upstream of the turbo-compressor inlet or air-intake manifold inlet
(for N.A. diesel engines). As engine vacuum changes according to variations in
load, more or less gas (as required) is supplied to the engine from the gas
train.
This variation is gas flow is achieved with the use of a "zero governor" type
gas regulator which alters the gas flow rate in order to maintain approximately
atmospheric delivery pressure (zero gas flow rate at approximately one
atmosphere of ambient pressure).
After exiting the mixer, the air-gas charge follows the normal path through
the engine's air-intake system.
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