Method for heating crude

Abstract

A method for heating one or more streams from a refinery process, chosen from the group of a crude tower inlet, vacuum tower inlet, catalytic reformer inlet, coker inlet, thermal cracker inlet and hydrocracker inlet. The method includes transferring, in a heat exchanger, heat from one or more streams from a petro-chemistry process, chosen from the group of a steam cracker charge gas, propane dehydrogenation charge gas and butane dehydrogenation charge gas to said one or more streams from a refinery process for obtaining one or more heated streams in which the temperature of said one or more streams from petro-chemistry process is above the temperature of said one or more streams from a refinery process before said step of heat exchanging has taken place.

Claims

1. A method for heating one or more streams from a refinery process, chosen from a crude tower inlet, a vacuum tower inlet, a catalytic reformer inlet, a coker inlet, a thermal cracker inlet and a hydrocracker inlet, said method comprising a step of transferring, in a heat exchanger, heat from one or more streams from a petro-chemistry process, chosen from a steam cracker charge gas, a propane dehydrogenation charge gas and a butane dehydrogenation charge gas to said one or more streams from a refinery process for obtaining one or more heated streams, wherein the temperature of said one or more streams from the petro-chemistry process is above the temperature of said one or more streams from a refinery process before said step of heat exchanging has taken place, wherein the crude tower inlet is heated by transferring, in a heat exchanger, heat from the steam cracker charge gas to said crude tower inlet for obtaining a heated crude tower inlet.

2. The method according to claim 1, wherein said step of heating further comprises a step of additionally heating said crude tower inlet in a crude furnace, wherein said step of additionally heating takes place after transferring heat from steam cracker charge gas.

3. The method according to claim 1, wherein said step of heating further comprises a step of additionally heating said crude tower inlet in a crude furnace, wherein said step of additionally heating takes place before transferring heat from steam cracker charge gas.

4. The method according to claim 1, wherein the vacuum tower inlet is heated by transferring, in a heat exchanger, heat from said steam cracker charge gas to said vacuum tower inlet for obtaining a heated vacuum tower inlet stream.

5. The method according to claim 1, wherein the temperature at an inlet of said heat exchanger is at least 10 C. higher than the temperature at an outlet of said heat exchanger.

6. The method according to claim 1, wherein temperature of said at least one or more streams from the petro-chemistry process is in the range of from 350 C. to 600 C.

7. The method according to claim 1, wherein said step of heating further comprises a step of additionally heating said crude tower inlet in a crude furnace.

8. The method according to claim 2, wherein the temperature at an inlet of said heat exchanger is at least 10 C. higher than the temperature at an outlet of said heat exchanger.

9. The method according to claim 3, wherein the temperature at an inlet of said heat exchanger is at least 10 C. higher than the temperature at an outlet of said heat exchanger.

10. The method according to claim 4, wherein the temperature at an inlet of said heat exchanger is at least 10 C. higher than the temperature at an outlet of said heat exchanger.

11. The method according to claim 6, wherein the temperature at an inlet of said heat exchanger is at least 10 C. higher than the temperature at an outlet of said heat exchanger.

12. The method according to claim 2, wherein temperature of said at least one or more streams from the petro-chemistry process is in the ranges range of from 350 C. to 600 C.

13. The method according to claim 3, wherein temperature of said at least one or more streams from the petro-chemistry process is in the ranges range of from 350 C. to 600 C.

14. The method according to claim 4, wherein temperature of said at least one or more streams from the petro-chemistry process is in the ranges range of from 350 C. to 600 C.

15. The method according to claim 4, wherein said step of heating further comprises a step of additionally heating said crude tower inlet in a crude furnace.

16. The method according to claim 5, wherein said step of heating further comprises a step of additionally heating said crude tower inlet in a crude furnace.

17. The method according to claim 6, wherein said step of heating further comprises a step of additionally heating said crude tower inlet in a crude furnace.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be described in further detail below and in conjunction with the attached drawings in which the same or similar elements are referred to by the same number, and where:

(2) FIG. 1 is a schematic illustration of an embodiment of the process of the invention.

(3) FIG. 2 is another embodiment of the process of the invention.

(4) FIG. 3 is another embodiment of the process of the invention.

DETAILED DESCRIPTION OF THE INVENTION

(5) Referring now to the process and the apparatus schematically depicted in FIG. 1, there is shown a method 101 for heating crude. Crude 1 is preheated in a crude preheater 20 and the thus preheated crude 4 can be sent directly, via line 9, to a crude furnace 2. The heated crude 12 having a temperature of around 350 C. is sent to a unit 11. This route is the standard route for heating crude to a final temperature. Unit 11 relates to a refinery unit, such as for example a CDU, VDU, HYC, Coker or FCC, wherein stream 1 can be identified as a heat demanding refinery stream, i.e. a stream that needs to be raised in temperature before sending to unit 11. Although the following discussion of the embodiments identifies unit 11 as an atmospheric tower, the present invention is not restricted to such a refinery unit.

(6) According to the present method shown in FIG. 1 cracked gas 3 coming from a cracking furnace and having a temperature of around 800 C., is sent to a heat exchanger (TLE) 21 providing an effluent 5 having a temperature of around 500-400 C. The pre-heated crude 4 is brought, via line 8, into contact with the effluent 5 in a heat exchanger 6 resulting in a heated crude 10. The crude 10 thus heated is sent to atmospheric tower 11. Cracked gas 7 coming from heat exchanger 6 has now a temperature in the range of 150-250 C. According to this method heat from a petro-chemistry process, i.e. the cracked gas from a steam cracking furnace 3 is integrated in a stream from a refinery process, i.e. an atmospheric tower 11.

(7) FIG. 2 shows another embodiment of the process 102 for heating crude, wherein cracked gas 3 from a cracking furnace having a temperature of around 800 C. is sent to a heat exchanger (TLE) 21 resulting in an effluent 5 having a temperature of around 400-500 C. Crude 1 is sent to a crude preheater 20 and its effluent 4 is brought into contact with the effluent 5 in a heat exchanger 6 resulting in heated crude 18. If necessary, crude 18 can be further heated in a crude furnace 2 resulting in a crude 12 having a final temperature of around 350 C. In this embodiment crude 12 is sent to an atmospheric tower 11. According to another embodiment (not shown) it is also possible to send effluent 4 first to a crude furnace 2 and then the crude thus heated to a heat exchanger 6 for further transferring heat between the heated crude and effluent 5. In the last embodiment the step of additionally heating in the furnace 2 takes place before transferring heat from steam cracker charge gas 3.

(8) FIG. 3 shows another embodiment of the process 103 for heating crude, wherein the heat capacity of stream 5 is also used to heat bottom stream 14 of atmospheric tower 11. Thus, bottom stream 14 can be further heated by a heat changer 22 to the desired inlet temperature of a feed 16 to a vacuum distillation tower 17. In vacuum distillation tower 17 feed 16 is separated into a top stream 19 and a bottom stream 18. The outlet stream of heat exchanger 22 can be mixed with the outlet stream 7 of heat exchanger 6 resulting in a mixed stream to be used for further possible heat integration purposes. Although FIG. 3 shows two different heat exchangers 6, 22, these two heat exchangers are integrated into one single heat exchanger according to a preferred embodiment. According to another embodiment heat exchangers 6, 22 can be run in parallel, in series, or in a combination thereof.

(9) As shown above, heat exchanger 6 is used to transfer heat from cracked gas 3 to an already preheated crude oil to replace all or part of the duty of the crude furnace 2. As shown in FIG. 2, an exergy advantage can be achieved by preheating crude in a convection section of a crude preheater 20 and subsequently heating crude 4 in heat exchanger 6 to the desired final temperature. FIG. 3 shows a preferred embodiment of further linking streams from heat producing units on the chemical side with heat demanding refinery streams.

EXAMPLES

(10) The examples refer to the application of crude heating by integration with ethylene furnace.

(11) The relevant data are: Cracking Furnace Ethane Feed: 100 t/h, Cracking Furnace steam to oil ratio: 0.33, and Cracking Furnace effluent temperature: 850 C., Crude feed to crude furnace: 230 t/h, Crude feed temperature 150 C. and Crude final temperature: 350 C.

(12) According to the state of the art processes there is no heat exchange between the processes for heating crude and cooling cracked gas (see scheme 1).

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(14) An example of heat integration using the present invention, is provided by the scheme 2.

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(16) The example above shows that the heat recovery from the secondary and tertiary TLE could be replaced by the heat recovery from a crude heater, heating and partly evaporating 230 t/h crude from 150 to 350 C. This avoids the requirements for a crude furnace. However the steam generated by the secondary and tertiary TLE's will have to be generated by other means, such as conventional steam boilers. Although this example refers to the use of TLE's, other hot streams can be used here as well, for example hot streams originating from dehydrogenation units, such as a propane dehydrogenation unit and butanes dehydrogenation unit.

(17) Stand alone steam generation is more efficient than stand alone crude preheating, resulting in energy savings: where the typical thermal efficiency of a crude furnace is 85%, the typical efficiency of a steam boiler is 90%, the resulting energy savings are 39.9/85%-39.9/90%=2.6 MW of fuel gas.

(18) Energy savings can be further increased by applying combined heat and power technologies such as back pressure steam turbines and gas turbines with waste heat boilers.