Advanced High-Temperature, High-Pressure Transport Reactor Gasification Page: 92 of 147
View a full description of this report.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
Oil Refinery, and an additional 73 hours of operation on a high ash coal from India was completed.
Data from these tests indicate that the transport gasifier performs better on the lower-rank
feedstocks because of their higher char reactivity with the gasification reactions.
Comparable carbon conversions have been achieved at similar oxygen/coal ratios for both air-
blown and oxygen-blown operation. While separation of fines from the feed coals is not needed with
this technology, some testing has suggested that feedstocks with high levels of fines have resulted
in reduced performance. These data show that these low-rank feedstocks provided similar fuel gas
heating values; however, even among the high-reactivity low-rank coals, the carbon conversion did
appear to lower for the fuels (brown coal in particular) that contained a significant amount of fines.
The fuel gas under oxygen-blown operation has been high in hydrogen and carbon dioxide
concentration since the high steam injection rate drives the water-gas shift reaction to produce more
CO2 and H2 at the expense of the CO and water vapor. However, the high water and CO2 partial
pressures have also greatly retarded the reaction of hydrogen sulfide with the calcium-based
sorbents.
Since warm gas cleanup is utilized, the unconverted steam and coal moisture injected into the
gasifier will remain in the fuel gas entering the gas turbine. When the air-blown and oxygen-blown
fuel gas heating values are compared for the wet product gas streams, it is apparent that only a slight
improvement in product gas heating value entering the gas turbine is achieved with oxygen-blown
operation. In order to keep the gas turbine firing temperature down to prevent thermal NO,
formation, typically large amounts of nitrogen or steam are injected into the gas turbine combustor
such that the fuel gas heating is typically not much greater than 115 Btu/scf as-fired. In essence, the
transport reactor has either injected the nitrogen with the oxidant (in the form of air) into the gasifier
instead of directly into the gas turbine combustor in air-blown mode or has injected the steam
directly into the gasifier instead of the gas turbine combustor in the oxygen-blown case. However,
in a Vision 21 plant, where chemicals or fuel production are being considered and where potentially
conventional cold-gas cleanup technology would be utilized to remove the water vapor from the fuel
gas stream, significantly higher concentrations of desirable fuel gas constituents are achieved with
oxygen-blown operation.
The TRDU and hot-gas filters have operated for over 2175 hours in gasification mode and
over 2500 hours total with no major candle failures. The candles have exhibited no significant loss
in candle permeability. The baseline "cleaned" filter differential pressure typically increased from
20 to approximately 80 inches H2O over the course of most tests. The inlet particulate loading has
ranged from approximately 3500 to 33,800 ppm with the filter ash averaging between 20 to
70 wt% carbon with a low bulk density around 20 lb/ft3. The average filter ash particle size has
ranged from approximately 7 to 22 pm in size and was essentially representative of the coal ash
from very early in the gasification test. The initial rapid recovery of the filter differential pressure
along with the small size, the lack of the cohesiveness seen in other filter ashes, and the low density
of the ash had suggested that a high percentage of the filter cake would be reentrained back onto the
filters after they are backpulsed. The large increase in filter baseline differential pressure also
suggests that a thin but low porosity (permeable) filter cake is remaining on the surface of the candle
and is not being removed during backpulsing. The low bulk density and high flowability of the filter
ash possibly suggests that the inlet ash is able to move or sift on the surface of the candle to reach
some optimum (minimum) porosity leading to low gas permeability across the candle.80
Upcoming Pages
Here’s what’s next.
Search Inside
This report can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Report.
Swanson, Michael L. Advanced High-Temperature, High-Pressure Transport Reactor Gasification, report, August 30, 2005; [Grand Forks, North Dakota]. (https://digital.library.unt.edu/ark:/67531/metadc889538/m1/92/: accessed July 17, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.