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EP-3444320-B1 - PROCESS FOR CONVERSION OF RESIDUE EMPLOYING DE-ASPHALTING AND DELAYED COKING

EP3444320B1EP 3444320 B1EP3444320 B1EP 3444320B1EP-3444320-B1

Inventors

  • PRADEEP, PONOLY RAMACHANDRAN
  • DAS, SATYEN KUMAR
  • PRASAD, TERAPALLI HARI VENKATA DEVI
  • KOTTAKUNA, Arjun Kumar
  • BHATTACHARYYA, DEBASIS
  • MAZUMDAR, Sanjiv Kumar
  • RAMAKUMAR, SANKARA SRI VENKATA

Dates

Publication Date
20260506
Application Date
20180309

Claims (14)

  1. An integrated coking and solvent de-asphalting process, the process comprising: (a) introducing a feedstock [1] near to bottom of a fractionator column [2] to obtain a mixed feed [3] drawn out from the bottom of the fractionator column; wherein the feedstock [1] is selected from vacuum residue, atmospheric residue, shale oil, coal tar, clarified oil, residual oil, heavy waxy distillate, foots oil, slop oil or blend of hydrocarbons; wherein the mixed feed [3] comprises the feedstock [1] and an internal recycle stream in the range from 5 to 80 wt% of the feedstock; (b) contacting the mixed feed [3] with a solvent [5] in a extractor [4] to obtain a pitch stream [6] containing asphaltenic fraction and predominantly a paraffinic stream [10] containing a de-asphalted oil and the solvent; (c) passing the pitch stream [6] to a pitch solvent stripper [7] to obtain a residual pitch stream [8] and the solvent; (d) heating the residual pitch stream [8] in a furnace [16] to a coking temperature to obtain a hot pitch stream [17]; (e) transferring the hot pitch stream [17] to one of a plurality of coke drums [18, 19] where it undergoes thermal cracking reaction to obtain hydrocarbon vapours [20] and coke; (f) passing the hydrocarbon vapours [20] to the fractionator column [2] to obtain product fraction.
  2. The process as claimed in claim 1, wherein the solvent to the mixed feed ratio in step (b) is in the range of 2:1 to 50:1.
  3. The process as claimed in claim 1, wherein the paraffinic stream [10] is transferred to a solvent separator [11] to obtain the solvent and the de-asphalted oil [12].
  4. The process as claimed in claim 1, wherein the paraffinic stream [10] further comprises a lighter paraffinic fraction of the internal recycle stream.
  5. The process as claimed in claim 3, wherein the solvent is recovered from the de-asphalted oil [12] in an oil solvent stripper [13] to obtain the solvent and a residual de-asphalted oil [14].
  6. The process as claimed in claim 5, wherein the solvent recovered from the pitch solvent stripper [7], the solvent separator [11] and the oil solvent stripper [13] is recycled to the extractor [4].
  7. The process as claimed in claim 1, wherein the solvent is selected from the group comprising of hydrocarbons having 3 to 7 carbon atoms and mixtures thereof.
  8. The process as claimed in claim 1, wherein the extractor [4] is operated at a temperature in the range of 55 to 300°C.
  9. The process as claimed in claim 1, wherein the extractor [4] is operated at a pressure in the range of 1 to 60 kg/cm2 (g).
  10. The process as claimed in claim 1, wherein the coke drums [18, 19] are operated at a temperature in the range of 470 to 520°C.
  11. The process as claimed in claim 1, wherein the coke drums [18, 19] are operated at a pressure in the range of 0.5 to 5 Kg/cm2 (g).
  12. The process as claimed in claim 1, wherein residence time of the hot pitch stream [17] in the coke drums [18, 19] is in the range of 10 to 26 hours.
  13. The process as claimed in claim 1, wherein the feedstock [1] has conradson carbon residue content in the range of 4 to 30 wt% and density in the range of 0.95 to 1.08 g/cc.
  14. The process as claimed in claim 1, wherein the product fraction is offgas selected from the group consisting of LPG and naphtha [21], Kerosene [22], Light coker gas oil [23], Heavy coker gas oil [24] and Coker fuel oil [25].

Description

FIELD OF THE INVENTION: This invention relates to processing of heavy bottom residue material from the refining of crude oil. More specifically, this invention relates to integration of solvent de-asphalting process and delayed coking process. BACKGROUND OF THE INVENTION: Solvent de-asphalting is a process that separates heavy hydrocarbon oil into two phases, an asphalt phase, which contains substances of relatively low hydrogen to carbon ratio often called asphaltene type materials and a de-asphalted oil phase, which contains paraffinic type material substances of relatively high hydrogen to carbon ratio often called De-asphalted Oil (DAO). Therefore, it may be said that solvent de-asphalting is possible because different compounds have different solution affinity for each other and some combination are completely miscible while other combinations are almost immiscible. The ability of the solvent to distinguish between high carbon to hydrogen asphaltene type and low carbon to hydrogen paraffinic type materials is termed as selectivity. Solvent de-asphalting of heavy residual hydrocarbon oils using solvents to remove contaminants such as asphaltenes, metals and sulphur constituents has long been a standard processing practice in the petroleum refining industry. In the era of high crude oil prices, refiners prefer to process cheaper heavier crude. The large residue generated from heavy crude can be upgraded through solvent de-asphalting process to produce DAO for secondary processes. Solvent de-asphalting of short residue is primarily being employed for (lube-oil base stocks) LOBS production. However, the process also employed to produce more feedstock for secondary conversion processes such as Fluid Catalytic Cracking (FCC) and hydrocracking so as to upgrade bottom of the barrel and improve distillate yield. Conventionally, Propane de-asphalting is predominantly used for production of LOBS feedstock and slightly heavier paraffinic solvents are used for production of feedstock for conversion process. Propane de-asphalting produces high quality DAO suitable for LOBS production with limited DAO yield while use of heavier solvent say, C5 hydrocarbons results in increased DAO yield at the cost of quality. Thus, the choice of solvent for de-asphalting is made based on the requirement of DAO yield and rejection level of contaminants leading to requirement of two different processing units. The use of light hydrocarbon to upgrade heavy hydrocarbon oils is the subject of many patents, for instance US4502944, US4747936, US4191639 US3975396, US3627675, and US2729589. Use of mixture of propane, CO2, H2S is reported in US4191639 and an increase in DAO yield for same quality is also reported. Delayed coking is a process used in petroleum refineries to crack petroleum residue, thus converting it into gaseous and liquid product streams and leaving behind solid, carbonaceous petroleum coke. The excess generation of low value petroleum coke in Delayed coking unit causes problems of coke handling and also reduces the profitability. In order to improve the conversion of the heavy residue feedstock, different process configurations employing combination of delayed coking and solvent de-asphalting processes have been employed in the prior art. U.S Pat. No. 3617481 discloses a combination of De-asphalting-Coking-Hydrotreating processes. The residue feed is first de-asphalted in a de-asphalting extractor and then the asphalt pitch is coked to obtain residual coke, by directly routing to the coking reactor. The metal containing coke is gasified in a gasifier in presence of steam and the said activated coke is employed for hydrotreating. U.S Pat. No. 6673234 describes a combination of low degree solvent asphalting and delayed coking process. In the first step, a low degree solvent de-asphalting is employed to remove the heavy asphaltene portion of the residue feedstock, in which the yield of de-asphalted oil ranges from 70 to 95 wt% of residue feedstock. In the second step, the de-asphalted oil containing lesser asphaltenes compared to the residue feedstock, along with an optional residue feed, is fed to the delayed coking section of the process. The main objective of the process is to produce premium quality petroleum coke from the residue feedstock. U.S Pat. No. 9296959 describes the integration of solvent de-asphalting with resid hydroprocessing and delayed coking. First step of this process consist of solvent de-asphalting of residue feedstock to obtain three fractions namely, de-asphalted oil, resin and pitch. The resin steam is subjected to hydrotreating, in which lighter hydrocarbons are generated and recovered. The hydrotreated resin and pitch combine together and is sent to the delayed coking section. In an embodiment, the hydrotreated resin stream is further subjected to solvent extraction to recover lighter material, before being sent to the delayed coking section. EP-A-209225 describes solvent de-asphalting with delayed