Process for simultaneous cracking of lighter and heavier hydrocarbon feed and system for the same

Patent metadata

Field	Value
Publication number	US-9433912-B2
Application number	US-201113638460-A
Country	US
Kind code	B2
Filing date	Mar 30, 2011
Priority date	Mar 31, 2010
Publication date	Sep 6, 2016
Grant date	Sep 6, 2016

Abstract

The invention provides for a process and apparatus for simultaneous conversion of lighter and heavier hydrocarbon feedstocks into improved yields of light olefins in the range of C2 to C4, liquid aromatics in the range C6 to C8 mainly benzene, toluene, xylene and ethyl benzene and other useful products employing at least two different reactors operated in series with respect to catalyst flow and parallel with respect to feed flow under different regimes and process conditions with same catalyst system.

First claim

The invention claimed is:

1. A process for simultaneous conversion of lighter and heavier hydrocarbon feedstocks into improved yields of light olefins, liquid aromatics and other useful products by a continuous FCC operation in multiple reaction zones in different reactors operating under different regimes and conditions comprising the steps of:
a) cracking the lighter hydrocarbon feedstock along with steam in the molar ratio of 1:60 to 60:1 in a bubbling or turbulent bed first reaction zone in the first reactor to get a first reactor effluent mixture;
b) separating the first reactor effluent mixture of step (a) into a vapor rich phase and a solid rich phase;
c) separating the vapor rich phase of step (b) in a product separator into C5− and C5+ fractions;
d) recycling the C5+ fractions back to the first reaction zone and continuing the cracking operation until the aromatics concentration in C5+ fractions reaches more than 90 wt %;
e) stripping a portion of the solid rich phase of step (b) containing coke laden catalyst using steam to remove entrapped hydrocarbons along with vapor rich phase entering the product separator:
f) transferring the remaining portion of solid rich phase of step (b) containing coke laden catalyst of step (b) from the first reaction zone to a second reaction zone of a second reactor, cracking the heavier hydrocarbon feedstock therein at a relatively lesser temperature and pressure as compared with those in the first reaction zone to get a second reactor effluent mixture, wherein coke on the catalyst from the first reaction zone does not exceed 0.35 wt %;
g) separating the effluent mixture of step (f) into a vapor rich phase and a solid rich phase containing coke laden spent catalyst;
h) fractionating the vapor rich phase of step (g) to get different cracked products;
i) stripping the solid rich phase of step (g) using steam to remove entrapped hydrocarbons along with vapor rich phase of step (g); and
j) regenerating the coke laden stripped spent catalyst obtained from step (i) and step (e) in a common catalyst regenerator using air and/or an oxygen containing gas to produce an active regenerated catalyst for recirculating to the first reaction zone through regenerated catalyst standpipe and regenerated catalyst slide valve for the next cycle of operation.

2. The process as claimed in claim 1 , wherein the lighter feedstock is hydrocarbon fraction boiling up to 220° C. starting from C3 hydrocarbon and the heavier one is hydrocarbon fraction having initial boiling point above 220° C. and Conradson Carbon Residue up to 15 wt %.

3. The process as claimed in claim 1 , wherein the light olefin products are in the range of C2 to C4, comprising ethylene, propylene, isobutylene, trans-2-butene, cis-2-butene, butene-1 and the liquid aromatics are in the range of C6 to C8, comprising benzene, toluene, xylenes and ethylbenzene while other useful products comprise LPG (C3 and C4), gasoline (C5-150° C.), heavy naphtha (150-216° C.), light cycle oil (216-370° C.), bottoms (370° C+).

4. The process as claimed in claim 1 , wherein the cracking operation in the first reaction zone is carried out at a temperature of 500-750° C., pressure of 1 to 5 Kg/cm 2 and WHSV of 1 to 200 hr − 1 whereas in the second reaction zone at 450-700° C., 0.9 to 4.9 Kg/cm 2 and 10 to 400 hr − 1 respectively.

5. The process as claimed in claim 4 , wherein the cracking operation in the first reaction zone is carried out preferably at a temperature of 550-700° C. whereas in the second reaction zone preferably at 480-600° C. respectively.

6. The process as claimed in claim 4 , wherein the cracking operation in the first reaction zone is carried out preferably at a WHSV of 6 to 120 hr − 1 whereas in the second reaction zone preferably at 60-250 hr − 1 respectively.

7. The process as claimed in claim 1 , wherein the lighter hydrocarbon feedstock include straight run naphtha, visbreaker naphtha, coker naphtha, FCC naphtha, hydrocracker and hydrotreater naphthas, natural gas condensate, LPG condensate, gas well condensate or mixture thereof and the heavier hydrocarbon feedstocks includevacuum gas oil, vacuum slop, atmospheric gas oil, visbreaker/coker heavy gas oil, cycle oils, slurry oils, hydrocracker bottom, fuel oil, coker fuel oil, atmospheric residue, foots oil, vacuum residue or mixture thereof.

8. The process as claimed in claim 1 , wherein a sum of yields of ethylene plus propylene is not less than 25 wt % and 15 wt % in the first and second reaction zones respectively.

9. The process as claimed in claim 1 , wherein the propylene to ethylene ratio in the product from the second reaction zone is not less than 2.5:1.

10. The process as claimed in claim 1 , wherein the regenerator can be a single stage or multistage to burn the entire coke laden spent catalyst to form regenerated catalyst with coke content not exceeding 0.09 wt % and thus meeting the heat requirement of the first and second reaction zones.

11. The process as claimed in claim 1 , wherein the two reactors are operated in series with respect to catalyst flow and parallel with respect to feed flow.

12. The process as claimed in claim 1 , wherein the catalyst employed comprises Y -zeolite in rare earth ultra-stabilised form with bottom cracking components consisting of peptized alumina, acidic silica alumina or gamma alumina, pentasil shape selective zeolites or a mixture thereof which is capable of optimally cracking both the lighter and heavier hydrocarbon feeds.

13. The process as claimed in claim 1 , wherein the catalyst employed is solid micro-spherical acidic materials with average particle size of 60-80 microns and apparent bulk density of 0.7-1.0 gm/cc.

14. The process as claimed in claim 1 , wherein the active catalyst components are supported on relatively inactive materials such as silica/alumina or silica- alumina compounds, comprising kaolinites or with active matrix components comprising pseudobomite alumina.

15. The process as claimed in claim 1 , wherein the lighter hydrocarbon feedstock and steam at saturated or superheated conditions are mixed in a zone prior to contact with the catalyst and uniformly distributed using any of the distributors like manifold type, concentric ring type, perforated plate type, into the first reaction zone and are uniformly contacted with hot catalyst from the common regenerator in the first reaction zone.

16. The process as claimed in claim 1 , wherein the conversion in the second reaction zone, the sum of all products boiling less than or equal to 220° C. plus coke, is not less than 70 wt %.

17. The process as claimed in claim 1 , wherein the excess heat generated in the catalyst regenerator due to processing of heavy feedstock in the second reaction zone is utilized effectively for cracking the lighter hydrocarbon feedstock at temperature in the range of 600° C. to 700° C. in the first reaction zone.

Assignees

• Subramani Saravanan
• Bhattacharyya Debasis
• Manna Reshmi
• Das Satyen Kumar
• Sarkar Tridib
• Rajagopal Santanam
• Indian Oil Corp Ltd

Inventors

• Subramani Saravanan
• Bhattacharyya Debasis
• Manna Reshmi
• Das Satyen Kumar
• Sarkar Tridib
• Rajagopal Santanam

Classifications

• C10G2300/1074

  Vacuum distillates · CPC title

• C10G2300/4018

  Spatial velocity, e.g. LHSV, WHSV · CPC title

• C10G2400/30

  Aromatics · CPC title

• B01J2208/00902

  Nozzle-type feeding elements · CPC title

• C10G2300/104

  Light gasoline having a boiling range of about 20 - 100 °C · CPC title