METHOD FOR PRODUCING SYNGAS, AS WELL AS SYNGAS COOLING ASSEMBLY AND USE

Abstract

A method of producing synthesis gas in a dual pressure level ammonia plant having a first synthesis section operated in once through fashion at a first relatively lower high pressure and having a second synthesis section operated in recirculating fashion at a second relatively higher high pressure. In the first synthesis section downstream of an OT reactor of the first synthesis section the synthesis gas is cooled using cooling medium at a pressure below the first high pressure, wherein the cooling medium is provided at a pressure below the first high pressure level by means of a medium pressure steam generator or wherein the cooling is effected by means of the medium pressure steam generator. The disclosure further relates to a synthesis gas cooling assembly in such a dual pressure level ammonia plant and at least one plant component for providing or for utilizing the cooling medium.

Claims

1.-15. (canceled)

16. A method of producing synthesis gas in a dual pressure level ammonia plant, comprising: operating, in once through fashion, a first synthesis section at a first high pressure level, operating, in recirculating fashion, a second synthesis section at a second high pressure level, wherein the pressure of the second high pressure level is higher than the first high pressure level, cooling the synthesis gas in the first synthesis section downstream of an OT reactor of the first synthesis section using a cooling medium at a pressure level below the first high pressure level, and providing, by a medium pressure steam generator, said cooling medium at a pressure level below the first high pressure level or wherein the cooling is effected by the medium pressure steam generator.

17. The method of claim 16, wherein the pressure level is in the range from about 50 to about 75 bar.

18. The method of claim 16, wherein the cooling medium is steam.

19. The method of claim 18, wherein the steam is from boiler feed water.

20. The method of claim 16, wherein in the first synthesis section the synthesis gas is passed to at least one further OT reactor of the first synthesis section after cooling.

21. The method of claim 16, wherein the cooling medium is provided at or by the medium pressure steam generator comprising at least one dual phase heat exchanger which is traversed by synthesis gas upstream of the OT reactor or a further OT reactor, and/or wherein steam is generated from boiler feed water by the medium pressure steam generator when during the cooling of synthesis gas in the medium pressure steam generator heat is transferred to the boiler feed water.

22. The method of claim 16, wherein the cooling medium is passed to a process condensate stripper of the ammonia plant once heat exchange with the synthesis gas has been effected and/or wherein the cooling medium is passed to a primary reformer of the ammonia plant once heat exchange with the synthesis gas has been effected.

23. The method of claim 16, wherein decompressed cooling medium or cooling medium for decompression is diverted from the first synthesis section to a condensate drum of the ammonia plant downstream of the medium pressure steam generator.

24. A synthesis gas cooling assembly for heat removal from synthesis gas, comprising: two synthesis sections, a first one of the two synthesis sections having a relatively lower high pressure level of a dual pressure level ammonia plant relative to the second one of the two synthesis sections, the cooling assembly configured to provide cooling medium at a pressure level below the high pressure level of the first synthesis section, a medium pressure steam generator configured to provide the cooling medium at the pressure level below the high pressure level of the first synthesis section, and two discharge conduits, wherein one of the two discharge conduits is configured to provide the cooling medium to a process condensate stripper of the ammonia plant and the other of the two discharge conduits is configured to provide the cooling medium to a condensate drum of the ammonia plant.

25. The synthesis gas cooling assembly of claim 24, wherein the cooling arrangement is configured to provide the cooling medium in vaporous form.

26. The synthesis gas cooling assembly of claim 24, wherein the cooling arrangement is configured to provide the cooling medium downstream of a first OT reactor of the first synthesis section and upstream of a second OT reactor of the first synthesis section.

27. The synthesis gas cooling assembly of claim 24, wherein the synthesis gas cooling arrangement comprises the medium pressure steam generator comprising at least one dual phase heat exchanger.

28. The synthesis gas cooling assembly of claim 24, wherein the medium pressure steam generator of the cooling assembly which provides the cooling medium is connectable to a primary reformer of the ammonia plant; and/or wherein the medium pressure steam generator of the cooling assembly which provides the cooling medium is couplable/coupled to a process condensate stripper of the ammonia plant.

29. A dual pressure level ammonia plant having a first synthesis section comprising at least one OT reactor and having a second synthesis section having a plurality of loop reactors and having at least one synthesis gas cooling assembly according to claim 24.

Description

DESCRIPTION OF THE FIGURES

[0064] Further features and advantages of the invention are apparent from the description of at least one exemplary embodiment with reference to drawings and from the drawings themselves.

[0065] FIG. 1 shows a schematic diagram of the configuration of a dual pressure level ammonia plant,

[0066] FIG. 2 shows a schematic diagram of the configuration of a synthesis gas cooling assembly according to an exemplary embodiment in conjunction with a dual pressure level ammonia plant.

[0067] For reference numerals not described explicitly in respect of a single figure reference is made to the other figures. Identical reference numerals signify identical components.

DETAILED DESCRIPTION OF THE FIGURES

[0068] FIG. 1 shows a dual pressure level ammonia plant 1 having two synthesis sections, namely a first synthesis section 10a operated in once through fashion at a first high pressure level hp1 of about 100 bar and a second synthesis section 10b operated in recirculating fashion at a second high pressure level hp2 of about 200 bar. Arranged in the first synthesis section 10a is an OT reactor 2 and arranged in the second synthesis section 10b are a first loop reactor 10b1 and a second loop reactor 10b2.

[0069] Arranged downstream of the OT reactor 2 is a boiler feed water preheater 4 operated at high pressure which allows for heat exchange with synthesis gas SG and is operated at a heat exchanger pressure level hp1a of about 140 bar. The boiler feed water BFW may be provided by means of a feed water pump 5 and once heat exchange has been effected the preheated boiler feed water BFW may be passed on into a high pressure steam drum 6.

[0070] The preheater 4 operated a high pressure is a non-phase change heat exchanger. The preheater 4 is in the form of a horizontal (“flat-lying”) heat exchanger. In this assembly a conveying height for a boiler feed water pump may be kept low, thus saving energy.

[0071] In process engineering terms the OT synthesis section 10a is arranged upstream of the synthesis circuit 10b. Provided between the synthesis sections is a cooling sector for condensing ammonia produced in the OT synthesis out of the synthesis gas. The ammonia produced may be separated from the synthesis gas in an OT separator. A synthesis gas compressor may be used to increase the pressure from the relatively lower high pressure level of the OT synthesis to the relatively higher high pressure level of the synthesis circuit 10b.

[0072] The figures use the following abbreviations: medium pressure mp, low pressure lp, synthesis gas SG, boiler feed water BFW, high pressure steam HPS, medium pressure steam MPS, low pressure steam LPS.

[0073] FIG. 2 shows a synthesis gas cooling assembly 10 having two synthesis sections of which only the first synthesis section 10a at the first high pressure level is shown. The first synthesis section 10a comprises a first OT reactor 10a1 and at least one further OT reactor 10a2 between which OT reactors a medium pressure steam generator means 13 having a heat exchanger means is arranged. Arranged upstream of the medium pressure steam generator means 13 is a pass-through valve 12, in particular having a throttle or a valve unit.

[0074] The medium pressure steam generator means 13 is fed with boiler feed water from a pump 5. The medium pressure steam generator means 13 is coupled to a process condensate stripper 16 and/or a primary reformer 7. The medium pressure steam generator means 13 is further coupled to a condensate drum 18 via a decompression conduit/a decompression path 17, in particular in the form of a blow down conduit.

[0075] A logic unit 20 coupled to the pass-through valve 12 and/or to the medium pressure steam generator means 13 allows for monitoring and control of pressure and flow. In other words:

[0076] The logic unit 20 is optionally in communication with the valve 12 which may be operated as an actuator for controlling the pressure at the inlet into the heat exchanger means/the steam generator 13.

[0077] Compared to FIG. 1 two conduits are provided downstream of the medium pressure steam generator means 13, said conduits leading to the process condensate stripper 16 and to the condensate drum 18. By contrast, no steam is generated in the BFW preheater 4 shown in FIG. 1. A blow down is not necessary.

[0078] In contrast to a preheater 4 operated at high pressure in which no phase change takes place the medium pressure steam generator 13/the steam generator-heat exchanger thus contains two regions for a liquid phase and a gaseous phase respectively. The medium pressure steam generator may be in the form of a vertical (“upright”) heat exchanger means in which the tube bundle and the surrounding pressure vessel are vertically oriented. This allows effective phase separation especially for a large build height, in particular on account of specific density differences between steam and boiler feed water and on account of gravitational forces. This allows steam to be provided at the outlet in a sufficiently dry form. An additional liquid separator is not necessary.

LIST OF REFERENCE NUMERALS

[0079] 1 dual pressure level ammonia plant [0080] 2 OT reactor [0081] 4 preheater operated at high pressure (BFW preheater) [0082] 5 feed water pump
6 high pressure steam drum [0083] 7 primary reformer [0084] 10 synthesis gas cooling assembly [0085] 10a first synthesis section at first high pressure level [0086] 10a1 first OT reactor [0087] 10a2 further, especially second, OT reactor [0088] 10b second synthesis section at second high pressure level [0089] 10b1 first loop reactor [0090] 10b2 second loop reactor [0091] 12 pass-through valve, especially throttle or valve unit [0092] 13 medium pressure steam generator means, especially having heat exchanger means [0093] 16 process condensate stripper, especially medium pressure condensate stripper [0094] 17 decompression conduit/decompression path, especially blow down conduit [0095] 18 condensate drum [0096] 20 logic unit [0097] hp1 first high pressure level, especially about 100 bar in the first synthesis section [0098] hp2 second high pressure level, especially about 200 bar in the second synthesis section [0099] hp1a heat exchanger pressure level/BFW pressure in the first synthesis section [0100] hp2a pressure level of high pressure steam in the second synthesis section [0101] mp medium pressure [0102] lp low pressure [0103] SG synthesis gas [0104] BFW boiler feed water [0105] HPS high pressure steam [0106] MPS medium pressure steam, especially saturated medium pressure steam [0107] LPS low pressure steam/decompressed steam