Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L9/00—Treating solid fuels to improve their combustion
  • C10L9/02—Treating solid fuels to improve their combustion by chemical means

Definitions

• Coking has its greatest utility in upgrading the quality of low grade petroleum vacuum residua and pitches from highly asphaltic and sour crudes.
• Such residua frequently contain high concentrations of sulfur, i.e. 3 wt. percent or more.
• the sulfur content of the coke product from the fluid or delayed coking processes is about 2 times the sulfur content of the residuum feed from which it is produced.
• the sulfur content of coke from sour residu'a thus can range from as much as 5% to 8% sulfur or more.
• the high sulfur content of the coke product poses a mag'or problem in its efficient utilization.
• a low sulfur content coke about or below 4 wt. percent sulfur is required.
• the sulfur content should be substantially lower than the 4%.
• This invention overcomes the above difiiculties and disadvantages by providing an improved process for desulfurizing high sulfur containing petroleum coke with steam at elevated temperatures and pressures.
• the process comprises partially gasifying petroleum coke with steam under elevated temperatures and pressures, if desired in the presence of a suitable catalyst, for example, K CO whereby the sulfur content of the petroleum coke is reduced to below about 1.5 wt. percent.
• the present invention provides an improved process of lowering the sulfur content of petroleum coke comprising partially gasifying the coke with steam, at a temperature ranging from about 800 to about 2500 F. and at pressures ranging from about 100' to about 3000 pounds per square inch gauge (p.s.i.g.), the coke being gasified to the extent of from about 5 to about 50 weight percent.
• the reduction of sulfur in the unconverted coke is to less than 1.5 weight percent remaining therein, and ideally, to less than 1.0 percent by weight remaining in the unconverted coke.
• the reaction may be conducted in the presence of an alkali metal carbonate catalyst, or other suitable steamcoke catalyst.
• the partial gasification of the petroleum coke is best accomplished using gas (steam) velocities of greater than 0.1 foot per second in either fixed or fluid bed.
• gas (steam) velocity which should be greater than about 0.1 foot per second (ft./sec.).
• gas velocities may vary from 0.05 ft./sec. up to about 2.0 ft./sec., the most preferred range, however, being from 0.1 to 0.4 ft./sec.
• the steam feed rate ranges from 0.1 to about 20 w./w./hr. At these rates, and under suitable conditions of temperature and pressure, as hereinafter specified, it is possible to obtain steam conversion of greater than twenty-five (25) percent. Most suitably, the steam feed rate should range from 1 to about 8 w./w./hr., depending on the temperature and pressure under which gasification is occurring.
• temperatures between about 800 and 2500 F When catalysts are used, the temperature preferably ranges from about 800 to about 1600 F., while temperatures of between about 1600 to about 2000 F. are most preferable in the absence of a catalyst. Temperatures ranging from about 1000 up to about 1500 F. are most preferred in the presence of a catalyst.
• petroleum coke can be gasified at up to about 110 percent per hour, especially at pressures ranging from about 200 p.s.i.g. up to about 1000 p.s.i.g.
• the higher pressures within the preferred range are desirable due to the fact that such pressures would reduce the requirement of subsequent compression of the hydrogen produced by the reactions involved.
• pressures ranging from 200 to about 850 p.s.i.g. would be most suitable in the invention, the upper ranges being the most preferred.
• the coke particle size is dependent upon the conditions under which the petroleum coking occurs.
• the present process may be applied generally to fluid or delayed cokes in their commercially available form. If desired, the particle size may be reduced for particular equipment requirements.
• Example 1 Using a fixed bed reactor charged with 33 grams of Billings Green fluid coke, steam was added thereto at 1400 F. The amount of steam added to the reactor was about 1 weight of water per weight of coke per hour (w./w./ hr.).
• the exit gas was cooled to condense unconverted water and a sample of the dry gas collected at the end of each period and analyzed. Hydrogen sulfide contents are tabulated below. In each case the dry gas contained the expected mixture of hydrogen, carbon monoxide, car-bon dioxide and methane.
• Examples 2-4 A fixed bed reactor was prepared in the same manner as in Example 1, above, again with Billings fluid coke.
• the fluid coke was partially gasified with steam at 1400 F. and 280 p.s.i.g., both with and without a gasification catalyst (Nos. 2 and 3 without catalyst).
• the Billings fluid coke sample used in these runs contained 5.85 Weight percent sulfur. The results of the three desulfurization runs are given hereinbelow.
• Catalyst was :KgCOg.
• Example 5 Partial gasification of a sample of a Billings fluid coke sample, similar to the sample used in Example 1, at a pressure of 850 p.s.i.g. and at a temperature of 1200 F. resulted in reduction of sulfur content of the remaining fluid coke from 5.7 weight percent down to 0.2 weight percent. Treatment of the coke with steam, in the presence of K CO catalyst, resulted in a 33 percent gasification of the coke.
• Example 6 A fixed bed reactor was prepared, as in Example 1, with a Billings fluid coke sample and with K CO as a catalyst.
• the coke was partially gasified with steam at 1400 F., but at atmospheric pressure.
• the contact period was greatly extended over that ordinarily employed when pressures greater than atmospheric are used. This was done in order to get up to about 66 percent gasification of the coke.
• the remaining coke had a residual sulfur content of 3.05 weight percent. This run illustrates the dramatic effect of conducting the gasification reaction under pressure, as shown in the other runs.
• Example 7 In a fluid bed, 1100 pounds of fluid coke containing 5.3 weight percent sulfur, and to which had been added 10 weight percent K CO was treated for a period of eleven (11) hours at 1200 F. and 200 p.s.i.g. with steam at the rate of 0.2 W./w./hr. at a linear gas velocity of 0.3 feet per second.
• the coke was originally prepared from a high vanadium content Caribbean residuum. At the end of the above treatment it was determined that the coke had been 35 percent gasified, and the remaining coke had a residual sulfur content of 1.1 weight percent.
• Example 8 Using a fixed bed type reactor, 1000 pounds of a delayed coke, prepared from a Caribbean residuum, and having a 5 percent sulfur content is treated in the same manner as the fluid coke sample in Example 3, i.e., in the absence of a catalyst at 1400 F. and 280 p.s.i.g. Gasification is over thirty (30) percent, while the remaining coke has a residual sulfur content of less than 1.5 weight percent.
• the method of the invention contemplates the use of a suitable gasification catalyst, such as potassium carbonate.
• a suitable gasification catalyst such as potassium carbonate.
• the catalyst is easily mixed with the petroleum coke prior to its being charged to the reactor. As a rule, the catalyst is recoverable by conventional methods. There may be a slight overall catalyst loss however.
• a catalyst can be seen in the fact that metals removal, particularly vanadium, is possible by simple water washing if the catalyst is used in the desulfurization step.
• a process would comprise charging the coke-catalyst mixture to a pressure reactor, pressurizing to the level specified above, at a temperature of about 1000 up to 1500 F. and treating with steam. The product gas is taken off, water recovered and hydrogen purified. The desulfurized coke is removed and water Washed, which removes the vanadium and most other metals. If a fluid coke from Venezuelan crude were being desulfurized, there would be about 0.36 weight percent vanadium therein subject to removal by the present invention.
• the desulfurization requires a temperature of from about 1500 up to about 2500 F., preferably from 1600 up to 2000 F.
• One of the disadvantages of not using a catalyst is that metals removal is not possible by the water washing step.
• Steam addition to the reactor is variable over a fairly broad range while achieving satisfactory desulfurization.
• Steam may be added in an amount ranging from about 0.05 up to about 20.0 w./w./hr. A more preferred range is from 0.1 up to about 10.0 w./w./hr., with best results being obtained with a steam addition ranging between 0.2 and 4 w./w./hr.
• the present process provides a desulfurized coke product extremely well suited for blast furnaces in iron making.
• the vanadium is extracted from the desulfurized coke, the product is useful in high grade aluminum manufacture.
• a process for the partial desulfurization of fluid coke which' comprises contacting the fluid coke with steam at a temperature between about 800 and 1600 F.
• a process for the partial desulfurization of fluid coke which comprises contacting the fluid coke with steam at a temperature between about 1600 and about 2500 F and at a pressure between about 200 and about 1000 p.s.i.g. until from about 5 to about 50 weight percent of the fluid coke has been gasified and until the sulfur content of the unconverted fluid coke has been reduced to less than about 1.5 weight percent, based on the remaining coke.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Chemistry (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
• Coke Industry (AREA)
• Industrial Gases (AREA)

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Cited By (8)

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• 1969
  • 1969-03-24 US US809937A patent/US3600130A/en not_active Expired - Lifetime
• 1970
  • 1970-03-09 CA CA076,908A patent/CA946312A/en not_active Expired
  • 1970-03-12 GB GB01956/70A patent/GB1268457A/en not_active Expired
  • 1970-03-19 NL NL7003920A patent/NL7003920A/xx unknown
  • 1970-03-20 DE DE19702013530 patent/DE2013530A1/de active Pending
  • 1970-03-23 FR FR7010425A patent/FR2039886A5/fr not_active Expired
  • 1970-03-24 JP JP45024773A patent/JPS4918442B1/ja active Pending

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