Page 51 - Energize April 2022

TECHNICAL

Substance Composition (%) The hot water and exhaust gases from the
H 2 20 to 40 engines are fed into boilers. The resulting
steam can be used within other localised
CO 35 to 40 industrial processes. Electricity generated
CO 2 25 to 35 by the Jenbacher gas engines can either
CH 4 <15 be used on-site or sold to the public grid.
N 2 2 to 5 Syngas electrical efficiencies of 37% and
Table 1: Typical range for the composition of syngases over can be achieved with Jenbacher gas
engines.
Syngas composition
Table 1 provides a typical range for the composition of syngases. This will be dependent Advantages of fuelling gas engines
upon the specific chemical composition of the feedstock to the gasifier. with syngas
• Independent power supply
Syngas and fuel gas quality requirements • Reduced energy costs and greater
A wide range of hydrogen gases can be used in gas engines. However as with all engine fuels, predictability and stability
there are specific limits to different components of the input fuel gas. Gas contaminants • Efficient and economic combined heat
in syngas, most notably tar and humidity, are a key technical challenge to the utilisation of and electricity supply
synthetic gases. Please request the special gas technical instruction for fuel gas quality for • High electrical efficiency compared to
more information. other power generation technology (i.e.,
steam or gas turbines)
Syngas CHP engine concept • Best suited for an electrical output
Varying compositions, as well as calorific values and the combustion behaviour of the gases range of a few hundred kW up to 20 to
from synthetic gases processes, put greater demands on engine design. Clarke Energy 30 MW
offers specially modified Jenbacher gas engines that make efficient use of these gases for • Low gas pressure required
combined generation of heat and electricity. Special features of these engines may include • Alternative disposal of a problem gas
flame arrestors for the prevention of backfiring and special gas mixers to improve gas mixing while simultaneously harnessing it as an
and to be more robust to dirt. energy source
In general, the stable composition of wood gas makes it advantageous as an engine fuel. • Substitute to conventional fuels
The high hydrogen content of some syngases however, means the combustion process is • Environmental benefits by greenhouse
very fast, which increases the danger of engine pre-ignition, knocking or engine backfiring. gas reduction
To avoid this risk, Jenbacher has created an engine control system that is able to fuel the
Jenbacher engine with a very lean mixture and, at the same time, react very quickly to Syngas competence
variations in the engine load. Clarke Energy has comprehensive
Some synthetic gases have a high carbon monoxide content, which has a low combustion experience with gas engine technology
speed and is very harmful. Jenbacher has developed the specific gas engine combustion and has a large reservoir of knowledge
system that enables burning of the gas efficiently and reliably. Additionally, Clarke Energy with respect to handling tricky gases such
and Jenbacher offer a safety technology package that allows firm handling of harmful gases as syngas. About 30 Jenbacher gas engines
such as carbon monoxide. Syngas can be used to create hot water, steam and electricity. now run on either coke gas or LD converter
gas. Underscoring Jenbacher’s technical
expertise, these units recently reached
a combined total of more than 1 million
operating hours. In addition, by utilising
these “free” waste gases compared to
using natural gas for power generation,
the Jenbacher technology-equipped
sites have achieved CO 2 savings of about
2-million tonnes since commissioning.
If you would like to find out more
about how Clarke Energy can help you
develop your landfill gas project, please
contact your local office for more details.

Contact Graeme Stanley, Clarke Energy,
graeme.stanley@clarke-energy.com,
Figure 2: The benefits of CHP – Click on the image to watch the video https://www.clarke-energy.com

energize | April 2022 | 49