Advanced development of a pressurized ash agglomerating fluidized-bed coal gasification system. Quarterly progress report, April 1-June 30, 1982 Page: 70 of 105
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4.1 AUTO-CONTROLLED TRANSIENT RESPONSE
During the transition from steady state 3 to 3A of PDU test TP-032-2, a
transient was imposed on the gasifier with three automatic control loops
operational. The purpose of this test was to observe how fast the gasifier
could respond when certain critical parameters are controlled in concert. The
controlled parameters were: a) fluidized bed level; b) freeboard temperature;
and c) ash annulus level. The manipulated variables used to control these
parameters are coal feed rate, oxygen feed rate, and the ash withdrawal rate,
The transient was implemented by changing the set point on the temperature
indicating controller from 1820*F to 1860*F. The immediate response was an
increase in oxygen flow. As bed carbon was being consumed at an accelerated
rate by combustion or gasification, the coal feed rate was increased to
maintain the bed level. The ash withdrawal rate was automatically adjusted to
accommodate the increased carbon and ash throughput.
Figures 4-1 through 4-5 illustrate the controlled response of the gasifier to
the imposed transient. Table 4-1 summarizes the results of the test.
The major highlight of the test was that net calorific heat production
increased at a rate of 8 percent per minute. The total load change was
observed to be 37 percent. Further testing is required to assess the
sensitivity of transient response characteristics to gasifier initial
conditions and feedstock properties.
4.2 FULL CYCLONE COLD WALL
TP-032-1 served as a shakedown test for the full cyclone cold wall using
highly fouling Indiana No. 7 and Upper Freeport coal as the feedstocks. The
amount of cooling water flow was adjusted to achieve a gas-side metal wall
temperature of not greater than 400*F. This resulted in a product gas
temperature drop of -450*F. A total of 111 hours of hot coal feed were
accumulated on the cold wall in this test. These hours were not, however,
accumulated continuously, since two intermediate shutdowns were necessitated
by unrelated problems.
TP-032-2 continued the demonstration of the full cyclone cold wall using Upper
Freeport coal, again along with an equally fouling Western Kentucky No. 9
coal. During this run, cooling water flow was adjusted to achieve gas-side
metal wall temperatures of no greater than 700*F. A total of 150 hours of hot
coal feed hours were accumulated on the cold wall, of which 96.5 hours were
continuous. No deposits were found upon visual inspection after shutdown.
The absence of deposition the cooled metal surfaces of the cyclone barrel and
inlet spools demonstrated the technical viability of this technique as a means
of controlling deposit formation.
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Advanced development of a pressurized ash agglomerating fluidized-bed coal gasification system. Quarterly progress report, April 1-June 30, 1982, report, October 21, 1982; United States. (https://digital.library.unt.edu/ark:/67531/metadc1058542/m1/70/: accessed May 25, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.