Disposal of disulfide oil compounds and derivatives in delayed coking process

Abstract

A heavy hydrocarbon oil is mixed with one or more disulfide oil compounds and/or one or more oxidized disulfide oil compounds and, optionally, a homogeneous catalyst includes dissolved hydrogen, and the mixture is subjected to a delayed coking process to produce a liquid coking unit product stream for recovery and further processing, with the delayed coking being completed in a reduced residence time as compared to the delayed coking of the heavy hydrocarbon oil without the DSO and/or ODSO compounds.

Claims

1. A process for the delayed coking of a heavy hydrocarbon oil feed, the process comprising: a. introducing and mixing the heavy oil hydrocarbon teed and one or more disulfide oil compounds, or oxidized disulfide oil compounds, or disulfide oil and oxidized disulfide oil compounds in a mixing zone and recovering a blended heavy oil mixture; b. heating the blended heavy oil mixture in a coking unit furnace to a delayed coking temperature; c. passing the heated blended heavy oil mixture to at least one coking drum of a delayed coking unit to produce a delayed coking unit product stream and depositing coke on the interior of the drum; and d. recovering the delayed coking unit liquid and vapor product stream for further downstream processing, wherein the coke formation in the coking drum is enhanced by promoting the formation of coke more rapidly than would occur in the coking of the heavy hydrocarbon oil feed in the absence of the DSO or ODSO.

2. The process of claim 1 which includes adding a homogeneous liquid catalyst for inclusion in the blended heavy oil mixture introduced into the delayed coking unit.

3. The process of claim 2 in which the homogeneous liquid catalyst includes transition metal-based compounds derived from an organic acid salt, or from an organo-metal compound containing molybdenum, vanadium, tungsten, chromium or iron.

4. The process of claim 2, in which the catalyst is selected from the group consisting of vanadium pentoxide, molybdenum alicyclic and aliphatic carboxylic acids, molybdenum naphthenate, nickel 2-ethylhexanoate, iron pentacarbonyl, molybdenum 2-ethylhexanoate, molybdenum di-thiocarboxylate, nickel naphthenate and iron naphthenate.

5. The process of claim 1 in which the disulfide oil comprises a plurality of disulfide oil compounds.

6. The process of claim 1 in which the oxidized disulfide oil comprises a plurality of oxidized disulfide oil compounds.

7. The process of claim 1 in which the disulfide oil or oxidized disulfide oil constitutes from 0.001-5 W %, 0.1-50 W %, 0.5-30 W %, 0.5-10 W % or 5-75 W % of the total weight of the blended heavy oil mixture.

8. The process of claim 1 in which the blended heavy oil mixture is heated to a temperature in the range of from 480° C. to 530° C. in the coking furnace.

9. The process of claim 1 in which the heavy hydrocarbon oil feedstream is a vacuum residue fraction boiling at or above 480° C. an atmospheric residue fraction boiling at or above 350° C., or a whole crude oil boiling at or above 36° C.

10. The process of claim 1 in which the delayed coking unit comprises at least two drums that operate in swing mode.

11. A method of enhancing the formation of coke in the drum of a delayed coking unit during the delayed coking of a heavy hydrocarbon oil feed, the method comprising: a. introducing and mixing the heavy hydrocarbon oil feed and one or more disulfide oil compounds, or oxidized disulfide oil compounds, or disulfide oil and oxidized disulfide oil compounds in a mixing zone and recovering a blended heavy oil mixture; b. heating the blended heavy oil mixture in a coking unit furnace to a delayed coking temperature; and c. passing the heated blended heavy oil mixture to at least one coking drum of a delayed coking unit to produce a delayed coking unit product stream and depositing coke on the interior of the drum, wherein the coke is formed more rapidly than would occur in the coking of the heavy hydrocarbon oil feed in the absence of the DSO and/or ODSO compounds.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be described in greater detail below and with reference to the attached drawings in which:

(2) FIG. 1 is a simplified schematic illustration of a system for the practice of a delayed coking process according to the present disclosure; and

(3) FIG. 2 is a simplified schematic illustration of a typical delayed coking unit for use in the system of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

(4) The process of the present disclosure for treating by-product disulfide oil compounds and, optionally, their derivative oxidized disulfide oil compounds in a delayed coking unit will be described with reference to FIG. 1. The process and system (10) include a mixing zone 30, a coking furnace (40) and coking unit (50).

(5) The heavy hydrocarbon oil (12) is introduced into the mixing zone (30) which includes an inlet (24) for introducing a liquid homogeneous catalyst, and an inlet (14) for the DSO, ODSO and/or a mixture of DSO/ODSO. As shown, mixing zone (30) also includes an outlet (32) for discharging the blended heavy oil mixture. Mixing zone (30) also comprehends an alternative system in which the heavy hydrocarbon oil and the other additive components comprising the feed to the delayed coking unit are stored in two or more tanks (not shown) that are in fluid communication with pumps equipped with controllers that adjust the rate of discharge in response to control signals from a programmed microprocessor. In this alternative system, the feed components are simultaneously injected into a conduit upstream of the coking furnace.

(6) Coking furnace (40) includes an inlet (41) in fluid communication with mixing zone outlet (32) and an outlet (42) for discharging the heated blended heavy oil mixture.

(7) Coking unit (50) includes an inlet (51) in fluid communication with furnace outlet (42) and an outlet (52) for the delayed coking product stream and an outlet (54) for recovering the coke when it has eventually been freed from the inside of the cooled drum.

(8) In the practice of the process of the invention, a fresh heavy hydrocarbon feedstock is introduced into mixing zone (30) for mixing or blending with the DSO, ODSO, or a mixture of DSO/ODSO to produce the blended heavy oil mixture. A homogeneous catalyst is optionally added to the mixing zone, or to the DSO and/or ODSO upstream of the mixing zone (30).

(9) The blended heavy oil mixture is introduced into furnace (40) via inlet (41) where it is heated to a predetermined coking temperature that is in the range of from 480° C. to 530° C. The heated blended heavy oil mixture is discharged via the outlet (42) and passed to coking unit (50) via inlet (51) for introduction into at least one coking drum where it is thermally cracked to produce the delayed coking unit product stream of gases and liquids, with the coke being deposited on the interior of the drum of the coking unit. The delayed coking product stream is discharged via outlet (52) for downstream processing, e.g., separation of the gases and fractionation of the liquid portion in a coking unit fractionator (not shown). Coking unit (50) also produces a coke product that is subsequently removed by conventional means from the cooled coking drum via outlet (54).

(10) Referring now to FIG. 2, the delayed coking unit (50) includes at least two drums (50A, 50B). The coking unit produces a delayed coking unit liquid product stream that is discharged via outlet (52) and a solid coke product that is eventually recovered via outlets (54A and 54B), respectively. The drums (50A and 50B) are operated in swing mode. When the operating drum is filled to capacity with coke, the heated blended heavy oil mixture discharged from the furnace (40) via outlet (42) is switched to the parallel drum for continuous operation of the unit. The coke product is then cooled and removed from the first drum by conventional means.

(11) In some embodiments, the operating temperature of the coking drum can be in the range of from 425° C. to 650° C., 425° C. to 540° C., 425° C. to 510° C., 425° C. to 500° C., 450° C. to 510° C., 450° C. to 650° C., 450° C. to 540° C., 450° C. to 500° C., 470° C. to 650° C., 470° C. to 540° C., 470° C. to 510° C. or 470° C. to 500° C. The operating pressure of the coking drum is mildly super-atmospheric and can be in the range of from 1 to 60 bar, from 3 to 20 bar, from 2 to 10 bar, or from 3 to 7 bar. The coking cycle time can range from 1 hrs to 60 hrs; from 10 hrs to 48 hrs; from 24 hrs to 60 hrs, from 8 hrs to 48 hrs, or from 8 hrs to 24 hrs. These ranges are dependent in part on the capacity of the drums and the nature of the heavy hydrocarbon oil feed.

(12) In some embodiments, the heavy oil portion of the feedstream is a vacuum residue (VR) fraction boiling at or above 480° C., an atmospheric residue (AR) fraction boiling at or above 350° C., or a whole crude oil boiling at or above 36° C.

(13) In some embodiments, the DSO, ODSO, or the mixture of DSO/ODSO is present in a concentration in the range of from 1 wt % to 75 wt %, or from 5 wt % to 70 wt %, or from 1 wt % to 10 wt %.

Example 1

(14) A vacuum residue (VR) oil sample “VR-1” derived from an Arab medium crude oil was blended with DSO compounds and subjected to delayed coking. The vacuum residue and DSO were blended at the various weight percentages indicated in Columns 1 and 2 of Table 1.

(15) TABLE-US-00001 TABLE 1 3 4 5 1 MCR of MCR MCR 6 Vacuum 2 Blend Expected VR Coke Residue DSO Measured calculation Basis Yield W % W % W % W % W % W % 100 0 23.4 23.4 23.4 37.4 95 5 22.3 22.2 23.5 37.6 91 9 21.8 21.3 24.0 38.3 67 33 16.4 15.7 24.5 39.2 50 50 12.6 11.7 25.2 40.3

(16) Each blend was analyzed for its micro carbon residue (MCR) content using the procedure of ASTM D4530, with the results shown in Column 3 of Table 1. Assuming that only the vacuum residue contributes to the overall MCR content, the expected MCR content for each blend is listed in Column 4 of Table 1. It is understood that the sulfur introduced with the DSO is distributed among the solid, liquid and gaseous products formed during the coking step. In accordance with standing refinery practices, the coking unit products will be subjected to hydrotreating and other downstream processing.

(17) The computer program used to calculate the expected values entered in Column 4 was described by J. F. Schabron and J. G. Speight in an article entitled “An Evaluation of the Delayed-Coking Product Yield of Heavy Feedstocks Using Asphaltene Content and Carbon Residue”, Oil & Gas Science and Technology—Rev. IFP, Vol. 52 (1997), No. 1, pp. 73-85.

(18) The normalized MCR content is entered in Column 5 of Table 1. The MCR content of each of the blends is normalized to the vacuum residue concentration, according to the equation:

(19) $\begin{array}{cc}\frac{\mathrm{Measured}MCR\mathrm{of}\mathrm{blend}\left(W\%\right)}{\mathrm{Measured}\mathrm{vacuum}\mathrm{residue}\mathrm{in}\mathrm{blend}\left(W\%\right)}\times 100& \left(3\right)\end{array}$

(20) In order to calculate the expected coke yield of Column 6 in Table 1, the normalized MCR content from Column 5 of Table 1 was multiplied by a factor of 1.6 based on a model commonly utilized in the industry that has been found to be accurate.

(21) It is clear from the results reported in Example 1 that in the delayed coking of a blend of vacuum residue and DSO that the expected coke yield increases with an increase in the DSO content. This indicates that the presence of DSO gradually increases coke formation in the delayed coking unit with the addition of up to 50 wt %, where the increase in coke production was over 7%.

Example 2

(22) Another vacuum residue (VR) oil sample derived from an Arab medium crude oil was mixed with ODSO compounds to form a blended heavy oil mixture and subjected to delayed coking. The weight percent of vacuum residue to ODSO was varied over the range from 100% VR to 24.5 W %, with the corresponding maximum of 75.5 W % ODSO, as entered in Columns 1 and 2 of Table 2.

(23) TABLE-US-00002 TABLE 2 3 4 5 1 MCR of MCR MCR 6 Vacuum 2 Blend Expected VR Coke Residue ODSO Measured Calculated Basis Yield W % W % W % W % W % W % 100.0 0.0 21.7 21.7 21.7 34.7 90.6 9.4 20.7 19.7 22.8 36.6 75.5 24.5 21.3 16.4 28.2 45.1 50.0 50.0 15.5 10.9 31.0 49.6 27.5 72.5 9.9 6.0 36.1 57.6 24.5 75.5 11.9 5.3 48.6 77.7

(24) Each blended heavy oil mixture was analyzed for its MCR content using the ASTM D4530 method, with the results shown in Column 3 of Table 2. Assuming that only the vacuum residue contributes to the overall MCR content, the expected MCR content for each blend is listed in Column 4 of Table 2. The normalized MCR content is entered in Column 5 of Table 2. The MCR content of each of the blends is normalized to the vacuum reside concentration, according to equation (3) above.

(25) In order to calculate the expected coke yield for Column 6 of Table 2, the normalized MCR content from Column 5 of Table 2 was multiplied by a factor of 1.6 as described above.

(26) It is clear from the results of Example 2 that in the delayed coking of mixtures of vacuum residue and ODSO, the coke yield increases as the ODSO content is increased. This data indicates that the presence of ODSO at 50 weight % results in an increase in coke formation of about 43% and at 75% of ODSO in a 124% increase in coke formation.

(27) The results of both Example 1 and Example 2 indicate that the presence of either DSO compounds or ODSO compounds in a heavy hydrocarbon feed to a delayed coking unit will result in a substantial savings in processing time.

(28) The process and system of the present invention have been described above and in the attached figures; process modifications and variations will be apparent to those of ordinary skill in the art from this description and the scope of protection is to be determined by the claims that follow.