Online water vapor detection in the product gas from indirect gasification
The integration of a gasifier into a complex synthesis process, such like SNG synthesis,
with several process steps asks for a better monitoring of the gasifier performance.
While the dry gas composition is often known, tar concentration and
steam concentration in the raw producer gas are usually not available online. A set
of standard analyzers for dry gas composition (GC or NDIR) and online tar measurement
combined with an online water measurement could allow the continuous
calculation of simple mass and energy balances. Those balances, that characterize
the gasification process, could enable the operator to monitor the effects of
varying fuel properties and eventually counter the effects on the downstream
For the detection of steam concentration in raw gas electromagnetic waves of
terahertz frequencies (hundreds of gigahertz) are promising with regard to develop
a robust online measurement device for industrial application. Main reasons for the
high potential are the low risk for interference with the wide range of other molecules
and the fact that THz frequencies are rather insensitive to deposits and particulate
matter in the course of the beam, compared to laser technology at IR.
Aiming to test the feasibility of applying this measurement technique in the industrial
scale, a gas cell was designed and constructed providing conditions close to
the onsite operation (i.e. T, P, gas composition, etc.) for primary laboratory tests.
The experiments were then followed with onsite tests at Chalmers power central.
Within those experiments the application of THz spectroscopy as a promising
technique for detection and measurement of steam and CO at real industrial processes
was proven. Current report demonstrates the procedure of implementing a
THz spectrometer to acquire data in both laboratory and industrial scale and discuss
how those data could be interpreted to gain a precise measurement of desired
water vapor detection
hot gas cell.