Environmental Engineering Reference
In-Depth Information
Fig. 8 Deployed TGER
which required considerable remedial attention by the technicians. With remote
coordination with the manufacturer, many of these problems were quickly resolved,
but the overall reliability and performance of the downdraft gasifier was in gen-
eral decline over the three months, resulting in considerable down-time during the
Despite some initial tankage limitations (due to a delay in site prep by the
Victory Base Camp DPW) and intermittent performance of the chiller system
due to extremely high (120 F) ambient temperatures, the bioreactor performed
well during the first month. The chiller was eventually upgraded with one of
greater capacity, but during the final month the system encountered a compro-
mised heat exchanger, some pumping problems, and apparent loss of biocatalyst
efficacy due to heat exposure. The technicians were able to bypass the failed heat
exchanger, modify pump elevations and add fresh biocatalysts to recover system
About halfway through deployment, one of the two laboratory pelletizers became
inoperative and could not be recovered. This resulted in a shift from a daily to an
intermittent duty cycle (every other day) as the operators could not produce suf-
ficient waste fuel pellets to keep the downdraft gasifier running continuously. The
downdraft gasifier requires 60 lb/pellets/h and both pelletizers were needed to meet
that throughput.
Alternatively, the biggest issues anticipated prior to deployment, i.e., the viability
of the waste processing equipment involving the shredder, material transport/feeding
and generator flex-fuel control performed reliably and were generally trouble free.
Our pre-deployment effort on these critical system tasks ensured the system per-
formed reasonably well during the first month, and allowed the other engineering
issues to emerge from the background for proper identification and characterization
for remedy.
Despite the mechanical issues, when the various elements of the TGER system
were pulled together (routinely during the first month, then intermittently during
the last two months) the system performed remarkably well. Field data demon-
strated operations at or near 90% efficiency, with excellent throughput of both
liquid and dry waste. The system generally conserved water at steady state and no
environmental or safety problems emerged.
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