Hydrogen-Enriched Syngas from Biomass Steam Gasification for Use in Land-Based Gas Turbine Engines - Novel Combustion Concepts for Sustainable Energy Development - page 98

syngas. The energy ef ciency describes the conversion of all energy sources to

syngas (on a heating value basis). It is observed that the energy flow rate of the

syngas increases with reactor temperature, gas residence time, and S/B ratio (Das-
comb 2013 ). The drawback to this increased power production is that increasing any
of the three major parameters increases the auxiliary heating requirement. Increasing
reactor temperature obviously increased conduction losses, but it also increased the
sensible heat of the gas. For facilities without a heat exchanger, such as the one used
presently, that sensible energy is not recovered. The non-heat recovery energy
ef

fl

ciency gives a conservative estimate of the impact of increasing reactor tem-
perature. To analyze the ef ciency with a heat exchanger, one can simply assume a

recovery ef ciency of a heat exchanger.

It takes a considerable amount of energy to generate superheated steam. Steam
has a high heat of vaporization, and most of the energy requirement is needed
simply to make saturated steam. Because the reactor thermal losses were

xed at
each temperature, when less biomass was injected into the reactor, the relative
amount of thermal losses increased. In this way, increasing gas residence time
increases the relative amount of thermal losses. In other words, the amount of joules
lost per kg of biomass is greater when less kilograms of biomass are inserted into
the reactor. The gasi er conditions that maximize the thermal conversion of

all energy sources to syngas heating rate was discussed in a recent publication
(Dascomb et al. 2013 ). The energy conversion efficiency used is defined as

m syngas

HHV syngas

HHV b þ Q h þ m b D H s

m b

Figure 12 shows the effect of temperature on energy ef ciency. The energy

conversion ef ciency increased with increasing reactor temperature despite the

increased conduction losses of the reactor and increased sensible heat requirement

Fig. 12 Effect of temperature
on energy ef ciency.
(S/B = 1.8 ± 0.4)