Hydrogen-Enriched Syngas from Biomass Steam Gasification for Use in Land-Based Gas Turbine Engines - Novel Combustion Concepts for Sustainable Energy Development - page 91

The main control parameters that govern the biomass conversion chemical
process are as follows: bed temperature, steam-to-biomass ratio, biomass mass
throughput, and catalytic properties. The energy balance of the system is deter-
mined from the measurement of the all the energy inputs such as the heating value
of the biomass, steam energy, electric energy, and the heating value of the synthesis
gas. Using measurement and analysis tools, the objective is to determine the most
cost-ef cient reactor conditions for desired gas composition and the heating value.

The settling chamber and reactor are heated using independently controlled
radiant heaters. The heating system has a maximum capacity of 29 kWe and pro-
vides all the necessary energy for maintaining bed temperature and gasifying the
biomass feedstock. The system is capable of gasifying up to 20 kg/h (115 kWth) of
biomass pellets at 650 C.

Steam enters the reactor through 5 tuyeres (gas injectors). The tuyeres were
constructed out of steel piping (24 mm OD) and protrude 76 mm into the gasi

° C and 9 kg/h (50 kWth) at 850 °

er
bed. Through holes (1 mm) were drilled radially into the tuyeres to ensure uniform
steam injection while not allowing material to fl flow back into the settling chamber.

The gasi filled with inert silica sand to a static height of 1.0 m. The

pure SiO 2 sand has an average particle size of 0.28 mm. When

er reactor is

fl fluidized, the bed

height reaches 1.5 ow rate. The reactor was

constructed from 316 stainless steel with an inner diameter of 0.21 m and a height
of 3.1 m.
The biomass used for gasi

- 2.5 m depending on the steam fl

cation is stored in a sealed hopper before being
injected into the reactor. The pellets have an average diameter of 8 mm and
maximum length of 32 mm. The pellets are carried from the hopper by a metering
auger. The pellets are then fed by a fast injection feeder into the reactor just above
the steam injection point. A water-cooled jacket prevents premature pyrolysis in the
feeding system. After the biomass and steam mixture pass through the reactor, a
cyclone mechanical filter removes any solid bed materials and unreacted char from

the gas stream. The gas then C. In

addition to condensing out steam, many of the heavy tars and ash remaining in the
syngas are also removed. Following the condenser, the product gas composition is
analyzed using a gas chromatograph. A micro-pump carries a small amount of the
gas to a

fl flows to a condenser where it is cooled to 30 °

filter system where it is cleaned and dried before analysis. The bulk syngas
stream is then filtered by a bed of sawdust and fabric filter. The volumetric fl ow rate

of the filtered stream is measured using a custom venturi fl flow meter before being

disposed.
For each experiment, the reactor is first heated to the desired testing temperature

by the radiant heaters. The heaters are connected to variable transformers, which are
controlled by LabView process software. All facility control and measurement
hardware utilized a NI compact DAQ chassis and input/output modules. The cal-
ibrated transformers tune the voltage sent to each of the heaters to maintain uniform
temperature along the length of the reactor. To achieve this, seven K-type ther-
mocouples are evenly spaced along the reactor. The temperatures are recorded
using a 24-bit thermocouple module (NI-9213). Once the reactor becomes ther-
mally stable, the electrical load of the heaters is measured to determine the thermal