Conversion of high carbon refinery by-products. Quarterly technical report, April 1--June 30, 1996 Page: 5 of 10
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Conversion of High Carbon Refinery By-Products July 12, 1996
PETC Project - J7519 Page 4 of 9
Quarterly Technical Report
temperature controllers on the hydrocarbon feed storage tank and feed line were set at 300
*F. Steam was introduced into the unit through both the oxidant and the feed nozzles. The
steam injection, however, tended to disturb the riser bed density. The main gas flows and
the aeration gas flows had to be adjusted again to stabilize the TRTU and maintain the riser
bed density in the range of 8 to 10 lb/ft3. At this time, the standpipe DP was slightly below
80 in. of water. The air feed was 10 SCFH while the fluidization N2 to the mixing zone was
set at 140 SCFH and the booster N2 to the riser was set at 165 SCFH.
The Rose Bottoms blend was introduced at a rate of 3.5 lb/hr. The introduction of
the hydrocarbon feed into the unit has resulted in a substantial increase in the riser bed
density. In order to maintain a solid circulation rate at less than 1500 lb/hr, all the aeration
gas flows were turned down to a minimal level in addition to adjusting the main gas flows.
This resulted in a stable operation that lasted about 40 min during which the on-line GC
analysis was conducted and a product gas sample was taken for off-line analysis.
After a steady operation for about 40 min, the differential pressure (DP) across the
filter increased as a result of plugging. When the filters were switched to stabilize the unit,
solid circulation was lost which led to the shutoff of Rose Bottoms feed. The unit was then
cooled down to 1400 F, and solid samples were taken for analysis.
Results and Discussion
The duration of the run processing the Rose Bottoms blend lasted about 60 min,
during which the unit has operated steadily for 40 min and then was unstable for 20 min
as aresult of loss of solid circulation. This is shown in Figs. 1, 2, and 3. During steady
operation, the volumetric ratio of CO to CO2 measured by the on-line CO and CO2
analyzers was about 2 to 1 (Fig. 1) which is relatively constant over this time period. This
measurement should be regarded as approximate. The CO/CO2 ratio determined by the
on-line GC was much higher, viz., 5 to 1 and is considered accurate. This high value is due
to the low carbon conversion achieved here and is expected to decrease significantly at
high carbon conversion. The concentration of free O2was negligible. These data show
that the partial oxidation (POX) of hydrocarbons had occurred in the transport reactor. The
temperature. in the mixing zone was steady at about 16900F. The process temperature
decreased with the elevation along the riser (Fig. 2). The temperature was.1670*F at the
entrance to the riser and then dropped to 1640 F at the top of the riser. This temperature
profile along the riser indicates that the gasification (endothermic) reactions took place in
the riser. The steam consumption has been verified by a material balance. The mixing
zone bed density was in the range of 15 to 17 lb/ft3 while the riser bed density was about
10 lb/ft3 (Fig. 3) and the total transport gas flow was 340 SCFH. Assuming a slip of 2, the
solid circulation rate was estimated to be 1565 lb/hr, which is close to the upper limit of the
A material balance on the data collected during the steady 40-min period has been
made to estimate the carbon conversion. The catalyst inventory in the circulation loop was
estimated to be 9 lb while the carbon deposited on the catalyst was determined to be 9.2
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Katta, S.; Henningsen, G.; Lin, Y.Y. & Agrawal, R. Conversion of high carbon refinery by-products. Quarterly technical report, April 1--June 30, 1996, report, July 12, 1996; United States. (https://digital.library.unt.edu/ark:/67531/metadc676552/m1/5/: accessed April 25, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.