The combination of a CHP plant with gasification of biomass enables a
more flexible use of biomass energy resources compared to only combustion. In
this way, the possibility to co-generate heat and power and other chemical
energy carriers by either combustion of the product gas or by upgrading to a
synthesis gas or a specific energy carrier, such as methane, is introduced. By expanding
the CHP plant in this way it is possible to compensate for the lower heating
demand most of the year, but still have a capacity to produce high amounts of
heat for a district heating net when the winters are very harsh.
When the heat load is low the focus
is on producing high value fuels like methane from the biomass, while the
residual gas with CO+ H2 is burned in the boiler to produce the heat still needed.
Production of methane by using this route is an interesting alternative,
compared to production from a tar free CO + H2 synthesis gas. This is as the
second case requires a much more complicated and costly gas cleaning and
upgrading process.. Methane production followed by direct separation from the
product gas still requires removal of tar prior to separation
but will most likely still be less costly.
Methane production by separation from the product gas requires
relatively high methane content, higher than obtained in normal gasification as
indicated in Table III. To achieve this, the gasification should be optimised
for producing a methane rich product gas. Reduced steam to
biomass ratio, increased pressure and reduced temperature all increases
the CH4 content. In figure 2, at a steam-tobiomass ratio of 0.07, roughly 50 %
CO, 20 % H2 and 20 % CH4, is produced.
As each mole of CH4 contains 3.1 times more energy than H2 and CO, the CH4 contributes
to 47 % of the HHV of the produced gas. This is why it is interesting to look
at the possibility to produce high amounts of CH4 directly and then separate it
from the other gas components in the product gas.
What is Gasifier?
What is Simulation System?
Comparison or Difference between Steam Power Plant and Hydro-electric Power Plant
Power Plant Site Selection
Deriaz Turbine
Various Methods of Drawing Flow Nets
What is Flow Net?
What is Fluid Kinematics?
Types of Equilibrium of Floating Bodies
What is Buoyancy?
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