PROCESS AND PLANT FOR PRODUCING SYNTHESIS GAS BY PARTIAL OXYDATION

Abstract

The present invention relates to a process and plant for producing a hydrogen- and carbon oxides-having synthesis gas by partial oxidation of a carbonaceous feedstock having nitrogen compounds. The invention takes advantage of the different solubility of NH.sub.3 and CO.sub.2 as the synthesis gas stream is cooled. Water is condensed continuously throughout the cooling of the synthesis gas stream. NH.sub.3 preferentially dissolves or condenses into the liquid phase during cooling, but at relatively high temperatures, above about 80 to 100? C. Further condensation at lower temperatures then preferentially dissolves or condenses CO.sub.2 into the liquid phase. Thus, the formation of ammonium salts during cooling of the synthesis gas is prevented.

Claims

1. A process for producing a crude synthesis gas containing hydrogen and carbon oxides by non-catalytic partial oxidation of a fluid or fluidizable feed stream containing carbon and nitrogen with an oxygen-containing oxidant in a non-catalytic partial oxidation reactor, comprising the following steps: (a) providing the feed stream in fluid or fluidized form, providing an oxidant stream, y providing a moderator stream comprising water vapor and/or carbon dioxide; (b) providing a partial oxidation reactor comprising a reaction chamber having at least one inlet and one outlet, at least one burner disposed at the at least one inlet of the reaction chamber, and a precooling zone disposed downstream of and in fluid communication with the outlet of the reaction chamber; (c) introducing the feed stream, the oxidant stream, and the moderator stream into the reaction chamber via the at least one burner; (d) at least partially reacting the feed stream with the oxidant stream under partial oxidation conditions, at a pressure between and including 30 to 70 bara in the burner and/or in the reaction chamber located downstream of the burner to form a hot crude synthesis gas stream comprising hydrogen, carbon monoxide, carbon dioxide and ammonia; (e) discharging the hot crude synthesis gas stream from the reaction chamber and introducing it into the precooling zone, discharging a precooled crude synthesis gas stream from the precooling zone and from the partial oxidation reactor; (f) introducing the precooled crude synthesis gas stream into a first cooling zone, discharging a first cooled crude synthesis gas stream having a first gas temperature and a first condensate stream containing ammonia and/or ammonium compounds from the first cooling zone; (g) introducing the first cooled crude synthesis gas stream into a second cooling zone, discharging from the second cooling zone a second cooled crude synthesis gas stream having a second gas temperature and a second condensate stream containing carbon dioxide and/or carbonates; (h) feeding the second cooled crude synthesis gas stream to further purification, conditioning or processing steps; (i) wherein the first gas temperature is between and including 70 and 100? C. and wherein the second gas temperature is below and including 70? C.

2. The process according to claim 1, wherein the precooling zone is designed as a quench or as a waste heat boiler or as a combination of both.

3. The process according to claim 1, wherein the first cooling zone and the second cooling zone are designed as air coolers or as cooling water cooler.

4. The process according to claim 1, wherein the first cooling zone and the second cooling zone are arranged in a common cooling device, wherein the first cooling zone and the second cooling zone are cooled with the same single cooler.

5. The process according to claim 1, wherein the first condensate stream and the second condensate stream are each fed separately to at least one processing step.

6. The process according to claim 1, wherein the first condensate stream and the second condensate stream are combined to form a mixed condensate stream and are jointly fed to at least one processing step, the temperature of the mixed condensate stream being at least 30? C.

7. The process according to claim 5, wherein the at least one processing step comprises a stripping step with a stripping gas stream and/or an inherent steam stream.

8. The process according to claim 5, wherein in the at least one processing step a gas stream containing carbon dioxide is recovered, which is at least partially recycled to process step 1. (c) as a component of the moderator stream or forms the moderator stream.

9. A plant for producing a crude synthesis gas containing hydrogen and carbon oxides by non-catalytic partial oxidation of a fluid or fluidizable feed stream containing carbon and nitrogen with an oxygen-containing oxidant in a non-catalytic partial oxidation reactor, comprising the following means, devices and building blocks which are in fluid connection to each other: (a) a means for providing the feed stream in fluid or fluidized form, means for providing an oxidant stream, a means for providing a moderator stream comprising water vapor and/or carbon dioxide; (b) a partial oxidation reactor comprising a reaction chamber having at least one inlet and one outlet, at least one burner disposed at the at least one inlet of the reaction chamber, and a precooling zone disposed downstream of and in fluid communication with the outlet of the reaction chamber; (c) a means for introducing the feed stream, the oxidant stream, and the moderator stream into the reaction chamber via the at least one burner; (d) a means for discharging a hot crude synthesis gas stream from the reaction chamber and introducing it into the precooling zone, a means for discharging a precooled crude synthesis gas stream from the precooling zone and from the partial oxidation reactor; (e) a first cooling zone, means for introducing the precooled crude synthesis gas stream into the first cooling zone, a means for discharging a first cooled crude synthesis gas stream having a first gas temperature and a first condensate stream containing ammonia and/or ammonium compounds from the first cooling zone; (f) a second cooling zone, s means for introducing the first cooled crude synthesis gas stream into the second cooling zone, a means for discharging from the second cooling zone a second cooled crude synthesis gas stream having a second gas temperature and a second condensate stream containing carbon dioxide and/or carbonates; (g) at least one further purification, conditioning or processing apparatus, a means for feeding the second cooled crude synthesis gas stream to the at least one further purification, conditioning or processing apparatus; (h) wherein the first cooling zone and the second cooling zone are configured to allow adjustment of the first gas temperature between and including 70 and 100? C. and to allow adjustment of the second gas temperature below 70? C.

10. The plant according to claim 9 wherein the precooling zone is designed as a quench or as a waste heat boiler or as a combination of both.

11. The plant according to claim 9, wherein the first cooling zone and the second cooling zone are designed as air coolers or as cooling water cooler.

12. The plant according to claim 9, wherein the first cooling zone and the second cooling zone are arranged in a common cooling device, wherein the first cooling zone and the second cooling zone are cooled with the same single cooler.

13. The plant according to claim 9, wherein a means are comprised to allow that the first condensate stream and the second condensate stream are each fed separately to at least one processing apparatus.

14. The plant according to claim 9, wherein a means are comprised to allow that the first condensate stream and the second condensate stream are combined to form a mixed condensate stream and are jointly fed to at least one processing apparatus.

15. The plant according to claim 9, wherein the at least one processing apparatus is a stripping apparatus that is configured to carry out a stripping step with a stripping gas stream and/or an inherent steam stream.

16. The plant according to claim 9, wherein a means are comprised to allow that from the at least one processing apparatus, a gas stream containing carbon dioxide is recovered and at least partially recycled to the partial oxidation reactor as a component of the moderator stream or forms the moderator stream.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Developments, advantages and possible applications of the invention are also apparent from the following description of working and numerical examples and the drawings. All features described and/or depicted, either in themselves or in any combination, form the invention, regardless of the way they are combined in the claims or the back-references therein.

[0050] In the figures:

[0051] FIG. 1 shows a process or plant according to a first embodiment of the invention,

[0052] FIG. 2 shows a process or plant according to a second embodiment of the invention,

[0053] FIG. 3 shows a process or plant according to a third embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0054] In the process or plant according to a first embodiment of the invention as shown in FIG. 1, a precooled crude synthesis gas stream is discharged from a reaction chamber of a POX reactor and a precooling zone (both not shown) via line 11. The precooled crude synthesis gas stream is introduced into a first cooling zone 10 equipped with a first air cooler, and cooled to a first gas temperature between and including 70 and 100? C., preferably between and including 75 and 95? C.

[0055] From the first cooling zone 10, a first cooled crude synthesis gas stream with a first gas temperature is discharged via line 12 and introduced into a first gas-liquid-phase separator 20. From the first gas-liquid-phase separator 20, a first condensate stream containing ammonia and/or ammonium compounds is discharged via line 24, and a first cooled crude synthesis gas stream with a first gas temperature, partially depleted in condensate, is discharged via line 22, and introduced into a second cooling zone 30 equipped with a second air cooler.

[0056] From the second cooling zone 30, a second cooled crude synthesis gas stream with a second gas temperature is discharged via line 32 and introduced into a second gas-liquid-phase separator 40. From the second gas-liquid-phase separator 40, a second condensate stream containing carbon dioxide is discharged via line 44, and a second cooled crude synthesis gas stream with a second gas temperature, further depleted in condensate, is discharged via line 42, and routed to at least one further purification, conditioning or processing step.

[0057] In the embodiment of the invention as shown in FIG. 1, the first gas temperature is between and including 70 and 100? C., preferably between and including 75 and 95? C., and the second gas temperature is below and including 70? C., preferably below and including 50? C.

[0058] The first and second condensate streams may be processed separately or in a common processing step (not shown).

[0059] In the process or plant according to a second embodiment of the invention as shown in FIG. 2, all elements correspond to the corresponding elements shown in FIG. 1 labelled by the same reference numeral. However, line 24 is connected to line 44 so that the first and second condensate are combined to form a mixed condensate stream and are discharged from the process or plant as a common condensate stream.

[0060] In the embodiment of the invention as shown in FIG. 2, the first gas temperature is between and including 70 and 100? C., preferably between and including 75 and 95? C., and the second gas temperature is below and including 70? C., preferably below and including 50? C.

[0061] The first and second condensate streams are processed separately or in a common processing step (not shown).

[0062] In the process or plant according to a third embodiment of the invention as shown in FIG. 3, a first cooling zone 10 and a second cooling zone 30 are comprised in a common cooling device 50. In this embodiment, the first cooling zone and the second cooling zone are cooled with common air cooler 55. Both the first cooling zone 10 and the second cooling zone 30 are realized as heat exchanger tubes, arranged in parallel in the common cooling device 50.

[0063] In FIG. 3, a precooled crude synthesis gas stream is discharged from a reaction chamber of a POX reactor and a precooling zone (both not shown) via line 11 (indicated as horizontal arrow). The precooled crude synthesis gas stream is introduced into the first cooling zone 10 and is cooled by a flow of cold air (indicated as perpendicular arrows) as provided by an air cooler 55.

[0064] In the first cooling zone 10, the precooled crude synthesis gas stream is cooled to a first gas temperature between and including 70 and 100? C., preferably between and including 75 and 95? C., and discharged into a connection chamber 15 as a first cooled crude synthesis gas stream with a first gas temperature which is partially depleted in condensate (first condensate separation not shown in FIG. 3). From the connection chamber 15, the first cooled crude synthesis gas stream is introduced into the heat exchanger tube of the second cooling zone 30 and passes through the second cooling zone 30.

[0065] From the second cooling zone 30, a second cooled crude synthesis gas stream with a second gas temperature, further depleted in condensate (second condensate separation not shown in FIG. 3) is discharged via line 12 (indicated as horizontal arrow).

[0066] The first and second condensate streams may be processed separately or in a common processing step (not shown).

[0067] In the embodiment of the invention as shown in FIG. 3, the first gas temperature is between and including 70 and 100? C., preferably between and including 75 and 95? C., and the second gas temperature is below and including 70? C., preferably below and including 50? C.

Numerical Example

[0068] The gas composition in Table 1 is used as an example for illustration purposes and represents a shifted synthesis gas.

TABLE-US-00001 TABLE 1 Example Syngas Composition in vol.-%, saturated at ca. 184? C./5500 kPa(g) H.sub.2 46.5 CO 0.8 CO.sub.2 27.6 H.sub.2O 24.0 NH.sub.3 0.4 Other 0.8 Total 100.0

[0069] Table 2 shows the temperature of precipitation (solubility limit) of solid ammonium bicarbonate NH.sub.4 (HCO.sub.3) as a function of the starting gas phase ammonia content. For this example, the hydrogen content shown in Table 1 was adjusted to compensate for the varying ammonia content. Temperatures below 0? C. were not considered because of the normal freezing point of water (labelled *).

TABLE-US-00002 TABLE 2 Temperature of precipitation (solubility limit) of solid ammonium bicarbonate NH3 in gas phase NH.sub.4(HCO.sub.3) precipitation in mol-% temperature in ? C. 0.2 0* 0.5 0* 0.6 0* 0.7 3 1.0 12 1.75 22 2.5 26

[0070] On cooling the synthesis gas described in Table 1, the majority (more than 90 mol-%) of the ammonia present in the raw syngas condenses with the water by about 100? C. Further cooling down the synthesis gas to 70? C. captures more than 99 mol-% of the ammonia that was originally present in the gas phase. To this point, in comparison, a relatively small portion of the carbon dioxide is captured in the liquid phase. At 100? C., about 90 mol-% of the ammonia is in the liquid phase, whereas less than 1.5% of the CO.sub.2 partitions to the liquid phase. At 70? C., more than 99 mol-% of the ammonia is in the liquid phase and less than about 2 mol-% of the CO.sub.2 is captured.

[0071] Modifications to embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as including, comprising, incorporating, have, is used to describe, and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural.

LIST OF REFERENCE NUMERALS

[0072] 10 First cooling zone [0073] 11 Line [0074] 12 Line [0075] 15 Connection chamber [0076] 20 First gas-liquid phase separator [0077] 22 Line [0078] 24 Line [0079] 30 Second cooling zone [0080] 32 Line [0081] 40 Second gas-liquid phase separator [0082] 42 Line [0083] 44 Line [0084] 50 Common cooling device [0085] 55 Air cooler (blower)

[0086] It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. Thus, the present invention is not intended to be limited to the specific embodiments in the examples given above.