Conversion of high carbon refinery by-products. Quarterly technical report, April 1--June 30, 1996 Page: 6 of 10

Conversion of High Carbon Refinery By-Products July 12, 1996
PETC Project - J7519 B rPage 5 of 9
Quarterly Technical Report
wt% and the steam consumption was 1.4 lb. The C$ and other heavy hydrocarbons (not
measured) amounted to about 1.87 lb. Some of the unconverted heavy hydrocarbons
appeared to have been carried over to the filters causing filter plugging. Only 22 wt% of
the hydrocarbon contained in the feed was converted into fuel gas as a result of short run
time. Steady state with respect to carbon was not achieved as the carbon input was much
higher than carbon consumption. The LHV of the final product gas was estimated to be
110 BTU/ft3 if carbon conversion of 90% could be achieved.
As mentioned above, about 40 min after the start of the Rose Bottoms blend into
the unit, the differential pressure across the filter increased rapidly. This rapid buildup of
the filter DP appeared to be caused by some unconverted heavy hydrocarbons, which
deposited on the sintered metal surface. This was later established by an examination of
the plugged filter. The material balance around the circulation loop also confirmed a
substantial amount of unconverted hydrocarbons. The hydrocarbon carryover can be
attributed to a lower reactor temperature than what is required to crack the hydrocarbons
completely. The reactor has to be operated at 1800"F or higher and the filter must be
maintained at much higher than 600*F to eliminate plugging of filters.
The pressure imbalance over the TRTU, happened during the course of switching
filters, might have upset the reactor system contributing to loss of solid circulation as
indicated by a low riser bed density (Fig. 3). After the unit was cooled down, it was
observed that the cyclone skin temperature was much higher compared to other
components in the circulation loop indicating that some solids had hung up in the cyclone
section. Thus, the loss of solid circulation might be a result of choking the cyclone. As
mentioned earlier, the solid circulation rate has reached the upper limit of the cyclone
design capacity (1500 lb/hr). It may be necessary to use a smaller solid inventory than 10
lb used here to eliminate this problem.
General Comments
The following comments may be made based on the test with the Rose Bottoms
blend:
- This test has demonstrated the viability of the concept (discussed in Objectives).
The Rose Bottoms blend has been successfully converted into a fuel gas through
both partial oxidation and steam-carbon gasification in the unit.
* The heating value of the product gas can be enhanced to an acceptable level by
increasing the carbon utilization to 90% or higher.
. To improve the operability and stability of the unit, the operating temperature needs
to be increased to 1800"F or higher and the solid inventory needs to be reduced.

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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/m1/6/ocr/: accessed May 24, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.

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