METHOD AND DEVICE FOR COOLING A SYNTHESIS GAS FLOW

Abstract

The invention relates to a method and to a device for performing a process (P) having at least one heat-consuming process step (F). A first fluid (2), which arises in the process and contains acid gases and water vapor, is cooled indirectly against a second fluid (7), an acidic condensate thus being formed. The invention is characterized in that the first fluid (2) is cooled in at least two successive steps (E1, E2), between which heat for use in the heat-consuming process step (V) is indirectly drawn from the second fluid (10).

Claims

1. Method for performing a process (P) having at least one heat-consuming process step (F), wherein a first fluid (2), which arises in the process and contains acid gases and water vapor, is cooled indirectly against a second fluid (7) thus forming an acidic condensate, characterized in that the first fluid (2) is cooled in at least two successive steps (E1, E2), between which heat for use in the heat-consuming process step (V) is indirectly drawn from the second fluid (10).

2. The method according to claim 1, wherein a chemically neutral second fluid (7) is used and the heat intended for use in the heat-consuming process step (F) is transferred to a likewise chemically neutral medium.

3. The method according to claim 1, wherein the process (P) is a synthesis gas generation in which a carbon-containing feedstock (1) is thermochemically converted, in order to obtain a hot raw synthesis gas (11) containing water and acid gases as first fluid, which is cooled against demineralized water (DMW) (22) as a second fluid to obtain clean export steam.

4. The method according to claim 3, wherein heat is drawn from the DMW between the two steps of raw synthesis gas cooling, in order to use it for producing stripping steam (21), which is used for degassing DMW (22).

5. The method according to claim 3, wherein heat is drawn from the DMW between the two steps for cooling the raw synthesis gas, in order to use it for producing stripping steam (25) which is used in the degassing of process condensate (18).

6. Device for performing a process (P) having at least one heat-consuming process step (F), comprising a cooling device (B) by means of which a first fluid (2) that arises in the process and contains acid gases and water vapor can be cooled indirectly against a second fluid (7) thus forming an acidic condensate, characterized in that the cooling device (B) comprises two cooling stages (E1, E2) arranged in series and each of which allowing passage of the two fluids therethrough, between which a heat exchanger (E3) referred to as intercooler is arranged, via which heat can be indirectly drawn from the second fluid (10) and supplied to the heat-consuming process step (F).

7. The device according to claim 6, wherein it is suitable for performing a synthesis gas generation, in which a carbon-containing feedstock (1) can be thermochemically converted in order to obtain as first fluid a hot raw synthesis gas (11) containing acid gases and water vapor, which first fluid can be cooled against DMW (22) as second fluid in the cooling device (B′, B″) to obtain clean export steam.

8. The Device device according to claim 7, wherein the cooling device (B′, B″) comprises a degasifier (G1, G) for degassing DMW (22) provided for export steam production, wherein the intercooler (E13) is arranged in the sump chamber (S1, S) of the degasifier (G1, S), so that degassed DMW accumulating in the sump chamber (S1, S) can be converted against the DMW (19, 28) to be cooled in the intercooler (E13) into stripping steam (21) for degassing DMW (22).

9. The according to claim 7, wherein they have a PC fractionating column (T2, T2′) by means of which process condensate (18) arising during the cooling of the raw synthesis gas (11) can be degassed using stripping steam (25) before it is further processed to process steam, wherein the PC fractionating column (T2, T2′) is fluidically connected to the sump chamber (S1, S) of the degasifier (G1, G), so that DMW vapor generated there from degassed DMW (20) can be introduced as stripping steam (25) into the PC fractionating column (T2, T2′).

Description

[0023] In the following, the invention is to be explained in more detail based on three exemplary embodiments schematically illustrated in FIGS. 1 to 3.

[0024] FIG. 1 shows a process comprising a heat consuming process step in which a hot first fluid is cooled according to the invention.

[0025] FIGS. 2 and 3 each show a section from a synthesis gas generation in which hot raw synthesis gas produced as an intermediate is cooled in accordance with the invention to produce stripping steam. In the two figures, identical system components and process flows are identified by the same reference numbers.

[0026] Process P in FIG. 1 is supplied via line 1 with a feedstock, from which, in process step A, a first fluid 2 containing acid gases and water vapor is obtained as an intermediate. In order to be able to condense water and subsequently to separate acid gases, the first fluid 2 is supplied to the cooling device B, where it is cooled indirectly against a second fluid 3 in a first cooling step in the heat exchanger E1. While the second fluid exits the heat exchanger E1 heated via line 4 and is conditioned, for example, into a product 5 in process step C, the cooled first fluid 6 is passed into the heat exchanger E2, where it is cooled to below the water dew point against the first fluid supplied cold via line 7 from the outside. In the condensate obtained, a portion of the acid gases dissolves, so that via line 8 an acidic two-phase mixture of substances leaves the heat exchanger E2 which is passed on to process step D, where product 9 is obtained in particular by removing water and acid gases. In the intercooler E3, heat which is used in the heat-consuming process step F is drawn from the second fluid 10 that has been heated in the heat exchanger E2. For renewed heating, the second fluid cooled in intercooler E3 is supplied to heat exchanger E1 via line 3.

[0027] In FIG. 2, hot raw synthesis gas containing water and acid gases is supplied to a first heat exchanger E11 at a temperature between 370 and 150° C. via line 11, where in a first step it is cooled indirectly against degassed DMW 12 to a temperature between 300 and 120° C. While the degassed DMW 13 exits the heat exchanger Ell at a temperature just below its boiling temperature in order to be subsequently evaporated to export steam in a steam drum (not shown), energy is further drawn from the raw synthesis gas 14, which has been cooled in the first step, in a second heat exchanger E12 against also degassed DMW 15, wherein water is condensed and a two-phase mixture of substances 16 is obtained, which in the separating device D is separated into a largely anhydrous synthesis gas 17 and acidic process condensate 18. The degassed DMW 19 heated in the second heat exchanger E12 against the raw synthesis gas 14 releases part of its heat via the intercooler E13 again before it is supplied to the first heat exchanger E11 via line 12. The intercooler E13 embodied as an evaporator is arranged in the sump chamber S1 of the DMW degasifier G1 operated at low overpressure and surrounded by already degassed DMW 20, from which stripping steam is produced as a result of the heat supplied. One part 21 of the stripping steam rises upwards in the fractionating column T1 of the DMW degasifier G1 arranged above the sump chamber Si and is brought into intensive contact with the DMW 22 supplied to the top of the DMW fractionating column T1, which is degassed in the process. The stripping steam 23 loaded with the gases separated from the DMW 22 is withdrawn from the top of the DMW fractionating column T1 and supplied to disposal (not shown), while the degassed DMW is withdrawn via line 24 from the sump Si of the DMW degasifier and, after increasing the pressure in the pump P, is supplied to the second heat exchanger E12 as coolant 15.

[0028] The process condensate 18 is also degassed, for which purpose it is charged via the top of the fractionating column T2 of the PC degasifier G2, in which it flows downwards and is brought into intensive contact with stripping steam supplied via line 25 from the sump S1 of the DMW degasifier G1. As the stripping steam 26 loaded with the gases separated from the process condensate 18 is withdrawn from the top of the PC fractionating column T2 for disposal, degassed condensate 27 can be withdrawn from the sump S2 of the PC degasifier G2 and subsequently converted to process steam (not shown).

[0029] In FIG. 3, DMW 22 is first heated in the heat exchanger E12 against the raw synthesis gas 14 already cooled in a first step in the heat exchanger E11 before it is supplied to the intercooler E13 via line 28 to deliver heat. The intercooler E13 embodied as an evaporator is arranged in the sump chamber S of the degasifier G operated at low overpressure and surrounded by degassed DMW 20, from which stripping steam is produced by the heat supplied via the DMW 28. A first part 21 of the stripping steam rises upwards in the DMW fractionating column T1 arranged above the sump chamber S, at the top of which the DMW 29 cooled in the intercooler E13 is fed in order to be degassed on its way downwards by means of the stripping steam 21. The stripping steam 21 loaded with the gases separated from the DMW 29 is withdrawn from the top of the DMW fractionating column T1 and supplied to disposal (not shown).

[0030] For its degassing, the process condensate 18 is supplied via the top of the PC fractionating column T2′, which is likewise arranged above the sump chamber S of the degasifier G. On its way down, the process condensate is brought into intensive contact with stripping steam 25, which flows upwards through the chimney tray K from the sump chamber S. While the stripping steam 26 loaded with the gases separated from the process condensate 18 is discharged from the top of the PC fractionating column T2′ for disposal, condensate 27 can be withdrawn from the chimney tray K in a degassed manner and subsequently converted to process steam (not shown).