Purge/sampling system for a vessel, the corresponding vessel and cleaning method using said purge/sampling system

Abstract

The invention concerns a purge/sampling system for vessels, particularly for high temperature, high pressure vessels such as hydroconversion reactors used in refinery processes and operated in severe conditions. Such purge/sampling system comprises a purge/sampling line (16) equipped with a connector designed to be connected to the vessel (10), a first (18 and a second (20) flow regulation systems mounted in series on the purge/sampling line, wherein at least one injection line (22) is connected to the purge/sampling line between the first and the second flow regulation systems, said injection line comprising connecting means to a source of cleaning fluid (24) and at least one flow regulation device to control the flow of cleaning fluid through injection line and purge/sampling line The invention also concerns a vessel equipped with such a purge/sampling system, as well as a cleaning method using said purge/sampling system.

Claims

1. A purge and/or sampling system for a vessel, comprising a purge and/or sampling line equipped with a connector adapted to be connected to the vessel, a first and a second flow regulation systems mounted in series on the purge and/or sampling line, wherein at least one injection line is connected to the purge and/or sampling line between the first and the second flow regulation systems, said injection line being connected to a source of cleaning fluid and at least one flow regulation device to control the flow of cleaning fluid through the injection line and the purge and/or sampling line, and wherein the first and second flow regulation systems each comprise at least two control valves in series.

2. Method for the hydroconversion of heavy residues, comprising hydroconverting the heavy residues in at least one hydroconversion reactor, wherein a purge and/or sampling system according to claim 1 is connected to the bottom of the hydroconversion reactor.

3. The method for the hydroconversion of heavy residues according to claim 2, wherein the heavy residues comprise conventional vacuum distillation residue (VR) or vacuum visbroken residues (VVR).

4. The method for the hydroconversion of heavy residues according to claim 2, wherein the purge and/or sampling system is cleaned.

5. The purge and/or sampling system according to claim 1, wherein said injection line comprises at least one check valve to impede the cleaning fluid to flow toward the source of cleaning fluid.

6. The purge and/or sampling system according to claim 5, wherein the at least one check valve(s) of the injection line are air operating valves.

7. The purge and/or sampling system according to claim 5, wherein the at least two check valve(s) of the injection line are made in corrosion resistant metal.

8. The purge and/or sampling system according to claim 5, wherein the at least one check valve includes at least two check valves, in series.

9. The purge and/or sampling system according to claim 8, wherein the at least two check valves of the injection line are valves of different technology.

10. The purge and/or sampling system according to claim 1, wherein the at least two control valves in series of the first and second flow regulation systems are valves of different technology.

11. The purge and/or sampling system according to claim 1, wherein the control valves in series of the first and second flow regulation systems are two-way control valves.

12. The purge and/or sampling system according to claim 1, wherein the control valves in series of the first and second flow regulation systems are air operating valves.

13. The purge and/or sampling system according to claim 1, wherein the control valves in series of the first and second flow regulation systems are made in corrosion resistant metal.

14. Hydroconversion reactor of a refinery process comprising a purge and/or sampling system according to claim 1, wherein the system is connected to the bottom of the reactor.

15. The hydroconversion reactor according to claim 14, wherein said reactor is a hydrocarbon processing slurry reactor or a reactor intended to contain solids.

16. Method for cleaning the purge and/or sampling system according to claim 1, the purge and/or sampling system being connected to the bottom of a vessel, wherein the method comprises providing the system of claim 1, and then: (i) injecting a cleaning fluid via the injection line and the purge and/or sampling line, (ii) opening the first flow regulation system to allow said cleaning fluid to pass through said first regulation system for a sufficient period of time to clean said first flow regulation system and closing said first flow regulation system, wherein a separate or simultaneous opening of the valves in series of first flow regulation system is performed, (iii) opening the second flow regulation system to allow said cleaning fluid to pass through said second regulation system for a sufficient period of time to clean said second flow regulation system and closing said second flow regulation system, wherein a separate or simultaneous opening of the valves in series of second flow regulation system is performed.

17. The method for cleaning the purge and/or sampling system according to claim 16, wherein the cleaning fluid is pressurized at a pressure higher or equal to the internal pressure of the vessel before opening said first flow regulation system when internal pressure of the vessel is higher than atmospheric pressure, and the first regulation system controls the flow issued from or entering the vessel, and step (ii) is performed while the second flow regulation system is closed.

18. The method for cleaning the purge and/or sampling system according to claim 16, wherein internal pressure of said vessel is atmospheric pressure, and steps (ii) and (iii) are performed simultaneously.

19. The method for cleaning the purge and/or sampling system according to claim 16, wherein steps (i) to (iii) are repeated in the following sequences: a sequence (B) wherein at least a one run of steps (i) to (iii) is performed using a liquid as cleaning fluid, and a sequence (C) wherein at least one run of steps (i) to (iii) is performed using a gas as cleaning fluid.

20. The method for cleaning the purge and/or sampling system according to claim 16, wherein said method is performed during or after use of the vessel in a hydroconversion process.

21. The method for cleaning the purge and/or sampling system according to claim 16, wherein said method is performed during or after use of the vessel in a slurry hydroconversion process or in a process in which the vessel contains solids.

22. The method for cleaning the purge and/or sampling system according to claim 16, wherein for cleaning the vessel the cleaning fluid is a gas chosen among H.sub.2, N.sub.2, Ar, He, CO.sub.2, CO, fuel gas, and C1 to C4 hydrocarbons alone or in combination.

23. The method for cleaning the purge and/or sampling system according to claim 16, wherein for purging the vessel the cleaning fluid is a liquid chosen among gas oils; naphthas; C5 to C20 hydrocarbons alone or in combination; mineral oils; paraffins; vegetal or animal oils; crude oils and distillation products thereof.

24. The method for cleaning the purge and/or sampling system according to claim 23, wherein said gas oils are selected from VGO (Vacuum Gas Oil), LCO (Light Cycle Oil), HCO (Heavy Cycle Oil), and distillate.

25. The method for cleaning the purge and/or sampling system according to claim 23, wherein said crude oils comprise shale oils.

Description

(1) The invention is now described with reference to a non limitative figure, representing schematically a vessel equipped with an embodiment of a purge/sampling system according to the invention.

(2) FIG. 1 represents a vessel 10 which comprises an inlet line 12 and an outlet line 14.

(3) This vessel 10 is also equipped with a purge/sampling system comprising a purge/sampling line 16 connected to the bottom of the vessel 10.

(4) The purge/sampling line 16 is equipped with a connector (not represented) designed to be connected to the vessel, a first 18 and a second 20 flow regulation systems mounted in series on the purge/sampling line 16.

(5) According to the invention, the purge/sampling system also comprises an injection line 22 connected to the purge/sampling line 16 between the first 18 and the second 20 flow regulation systems.

(6) The injection line 22 comprises connecting means (not represented) to a source 24 of cleaning fluid (gas or liquid) and at least one flow regulation device 26 to control the flow of cleaning fluid through injection line 22 and purge/sampling line 16.

(7) In the represented example, the first 18 and second 20 flow regulation systems each comprise two two-way control valves 18a, 18b and 20a, 20b respectively.

(8) Pressurization means (not represented) may also be provided to pressurize the cleaning fluid circulating in said injection line. Such pressurization means can be integrated to the source 24 or be separated.

(9) In the example, the injection line 22 is also equipped with two check valves 28, 29 mounted in series. These valves can be two flapper check valves as represented, but could be two check valves of different technology.

(10) An example of cleaning of the purge/sampling system described above is detailed here after.

(11) After use of the purge/sampling system, a cleaning fluid is introduced in the injection line 22 via opening of valve 26. If the vessel is under a pressure higher than atmospheric pressure, the cleaning fluid is pressurized. For safety reasons, it is preferable that pressure within injection line 22 is higher than pressure within purge/sampling line 16 and vessel 10.

(12) The cleaning fluid is then circulating trough check valves 28 and 29 to the purge/sample line 16. Opening of valves 18b and 18a permits the fluid to flow towards vessel 10, hereby cleaning valves 18a and 18b. The duration of such circulation of cleaning fluid is adapted by the operator on a case by case basis, depending the kind of waste to be removed (solids alone, finely divided electrostatic particles, solids within viscous liquid, gum deposition along the walls of lines, vessels and valves) and configuration of the purge line.

(13) If the vessel is under pressure and operation, valves 20a and 20b will preferably be closed during cleaning of valves 18a and 18b. If not, the valves 20a, 20b may be opened simultaneously with valves 18a, 18b, although separate opening is preferred.

(14) After cleaning of valves 18a and 18b, these valves are closed and valves 20a, 20b are opened to let the cleaning fluid flow through them for a sufficient time.

(15) At the end of the cleaning, valve 26 of the injection line is closed, as well as all the other valves.

(16) Off course, cleaning of valves 20a, 20b may be performed before cleaning of valves 18a, 18b.

(17) Advantageously, the cleaning of each set of valves 18a, 18b and 20a, 20b, is ending with a cleaning gas, which permits to dry the purge/sampling system and avoid any remaining liquid in the purge/sampling system.

(18) Preferably, in case of high temperature vessels, installation is designed with power-driven valves. Preferred power-driven valves include pneumatic-driven valves.