METHOD AND ARRANGEMENT FOR HEAT ENERGY RECOVERY IN SYSTEMS COMPRISING AT LEAST ONE REFORMER

Abstract

A method of heat energy recovery in installations including at least one reformer, wherein, for the purpose of heat energy recovery, process condensate is preheated and/or evaporated on a cooling section of the installation by heat exchange with gas generated in the installation, in particular synthesis gas, wherein, prior to being preheated in a flue gas duct of the installation, combustion air is preheated by heat exchange by means of boiler feed water. The invention also relates to a heat energy recovery system for the implementation of the method.

Claims

1-15. (canceled)

16. A method for heat energy recovery in an installation, comprising: at least one reformer in a synthesis gas installation having steam reforming means, wherein at least the following process streams of the installation are interconnected: combustion air for the reformer, boiler feed water for steam generation, process condensate on a cooling section of the installation, and flue gas from the reformer; the method comprising: a) at least partially evaporating the process condensate on the cooling section; b) recovering heat energy from the flue gas discharged through a flue gas duct; c) conducting the combustion air through the flue gas duct prior to being supplied to the reformer for recovery of the heat energy; d) one or both of preheating and evaporating the process condensate on the cooling section for the purpose of heat energy recovery by heat exchange with synthesis gas generated in the installation, and e) preheating the combustion air by heat exchange by means of the boiler feed water prior to being preheated in the flue gas duct.

17. The method of claim 16, wherein heat transfer from the boiler feed water to the combustion air is realized in that the boiler feed water and the combustion air are conducted through at least one external air preheater arranged externally with respect to the flue gas duct, before the boiler feed water is conducted to the flue gas duct.

18. The method of claim 16, wherein the boiler feed water is conducted via a KSW preheater arranged internally in the flue gas duct and is arranged at the end of the flue gas duct.

19. The method of claim 18, wherein, in the flue gas duct, the flue gas is conducted through at least one air preheater arranged internally in the flue gas duct and is arranged upstream of the KSW preheater arranged internally in the flue gas duct.

20. The method of claim 18, wherein the boiler feed water is heated in at least one external KSW preheater before it is conducted via a further external air preheater, to the flue gas duct, the external KSW preheater arranged on the cooling section by means of process gas.

21. The method of claim 20, wherein, downstream of the external air preheater, the boiler feed water is subdivided into two parallel partial streams for the purpose of preheating the boiler feed water, into a partial stream to the KSW preheater arranged internally in the flue gas duct, and into a partial stream to the external KSW preheater, on the cooling section.

22. The method of claim 16, wherein the cooled boiler feed water exiting the first external air preheater is reheated and then conducted to a further external air preheater, in which heat exchange with the combustion air is again realized.

23. The method of claim 18, wherein the KSW preheater is a heat exchanger which is arranged on the cooling section and via which synthesis gas generated in the installation is conducted.

24. The method of claim 16, wherein the preheating or evaporation of the process condensate on the cooling section is realized in a boiler evaporator, which comprises two heat exchanger units and a common steam chamber.

25. A heat energy recovery arrangement for installations, comprising: at least one reformer for synthesis gas installations having steam reforming means, in which installations at least the following process streams of the installation are interconnected: combustion air for the reformer, boiler feed water for steam generation, process condensate on a cooling section of the installation, and flue gas from the reformer, which flue gas is discharged through a flue gas duct; wherein the heat energy recovery arrangement comprises: at least one air preheater for the combustion air, which is arranged externally with respect to the flue gas duct; at least one heat exchanger for the process condensate or the boiler feed water; a heat exchanger for the process condensate arranged on the cooling section and configured for heat energy recovery by way of heat exchange with synthesis gas generated in the installation, and wherein the external air preheater is configured and arranged for heat exchange between the boiler feed water and the combustion air prior to the preheating thereof in the flue gas duct.

26. The heat energy recovery arrangement of claim 25, wherein the heat exchanger for the process condensate is a boiler evaporator, which comprises two bundles and a common steam chamber.

27. The heat energy recovery arrangement of claim 25, wherein at least one KSW preheater is arranged internally in the flue gas duct, downstream at the end of the flue gas duct, the KSW preheater arranged in the flow path of the flue gas.

28. The heat energy recovery arrangement of claim 27, wherein a further external air preheater is arranged upstream of the internal KSW preheater; and/or a boiler feed water preheater is arranged on the cooling section, which is configured for heat exchange between the boiler feed water and process gas, downstream of the external air preheater.

29. The heat energy recovery arrangement of claim 25, further comprising a logic unit configured to control volumetric flow rates or for the switching of installation components at an external air preheater through which boiler feed water and combustion air are conducted for preheating the combustion air.

Description

[0047] Further features and advantages of the invention will emerge from the description of exemplary embodiments on the basis of drawings and from the drawings themselves. In the drawings:

[0048] FIGS. 1A, 1B each show, in a schematic illustration, a heat recovery arrangement according to one of the exemplary embodiments or the interconnection thereof with an installation,

[0049] FIGS. 2A, 2B each show, in a schematic illustration, a heat recovery arrangement according to a further exemplary embodiment or the interconnection thereof with an installation,

[0050] FIG. 3 shows, in a schematic illustration, a heat recovery arrangement according to a further exemplary embodiment or the interconnection thereof with an installation.

[0051] For reference signs which are not described explicitly with respect to a single figure, reference will be made to the in each case other figure.

[0052] FIG. 1A shows an arrangement 20 having a calorifier 15 and having an economizer 14 which is arranged at the end of a flue gas duct 2 of a synthesis gas installation. Gas FG is fed to a reformer 1 and is split into a process gas stream SG and a steam fraction. A flue gas stream RG is formed during the combustion of fuels with combustion air VL. Boiler feed water KSW is conducted through the calorifier 15 in heat exchange with combustion air VL. In particular, the boiler feed water passes from the battery limit or from a water treatment unit or from a deaerator/stripper to the calorifier 15. The boiler feed water which is cooled by heat exchange with the combustion air is then reheated in the economizer 14 at the very end of the flue gas duct and finally conducted to a steam drum 11, from which saturated steam SV is removed. The steam drum 11 is connected to a KSW evaporator 12 arranged in the flue gas duct 2. With certain installation configurations, it is also possible for this KSW evaporator 12 to be omitted. Upstream of the economizer 14 and downstream of the KSW evaporator 12, there are arranged two or more internal air preheaters 13, which, owing to the economizer 14, are able to be operated at relatively high flue gas temperatures, this contributing to cost reductions.

[0053] An evaporator 4 for process condensate PK is arranged on the cooling section 17, from which evaporator process steam PV is removed. The PK evaporator 4 comprises two heat exchangers/bundles, which can, in a common drum or a common steam chamber, make possible the PK evaporation in a single apparatus. Upstream thereof, process gas or synthesis gas SG is conducted from the reformer 1 via a gas cooler 3. Downstream of the first bundle, synthesis gas is conducted to a CO shift reactor 5 or to a water-gas shift reaction arrangement. This may comprise an HTS (high temperature shift) means or MT (medium temperature) shift means or HT-LT (low temperature) shift means. A CO shift reaction (or water-gas shift reaction) causes the synthesis gas temperature to increase again, it being possible for use to be made of this by the second bundle in the evaporator 4 for PK evaporation. This results in advantages, such as for example saving of material, smaller required steam chamber, fewer pipelines, and less measurement/control equipment, in particular since no interconnection of multiple separate evaporators is necessary.

[0054] Arranged downstream of the evaporator 4 is at least one external heat exchanger 6, via which the process gas SG can be conducted. Said at least one heat exchanger 6 may be used for different purposes according to the installation configuration. Here, as exemplary types of heat exchangers 6 in this arrangement, mention can be made, non-exhaustively, in particular of: fuel preheater, steam generator, input gas (feed) preheater, PSA offgas preheater, KSW preheater, PK preheater.

[0055] The first and second separators 7, 10 shown in FIG. 1A, which are arranged on a cooling section 17 extending from the reformer 1 to the synthesis gas removal means SG10, do not necessarily have to be provided in exactly this arrangement or number. One or more such separators are optionally arranged on the cooling section 17. Unused heat can be absorbed by way of an air cooler 8 and a water cooler or final cooler 9.

[0056] A logic unit 40 is connected to, for example, valves, fittings, heat exchangers and/or throughflow regulators of the arrangement 20, and also to a measurement device 30 which comprises at least one sensor unit 31 (for example for detecting temperature, pressure, volumetric flow rate), which can in each case be arranged on one of the fittings. Here, the arrangement of the sensor unit 31 is merely exemplary. In particular, it is also possible for sensor units 31 to be arranged on each of the further installation components.

[0057] A two-steam system may in this case be provided in particular by the following components: process gas cooler 3, steam drum 11, KSW evaporator 12 for the KSW evaporation and PK evaporator 4 for the PK evaporation.

[0058] FIG. 1B shows, in a modification to FIG. 1A, an arrangement in which the heat exchanger 6 may be optionally omitted according to installation configuration.

[0059] FIG. 2A shows an installation configuration having two calorifiers 15, 16, this arrangement allowing a first, boiler feed water preheating, process on the cooling section 17 and a second, boiler feed water heating, process in the economizer 14 at the end of the flue gas duct 2. The boiler feed water can be heated at two locations, whereby the cooling section 17 is linked to the flow path of the combustion air. FIG. 2A shows, in a modification to FIG. 1A, a KSW preheater 6a and a second calorifier 16 downstream of the KSW preheater 6a. The further process streams, not described here in detail, can be realized or arranged in a manner comparable with the description in FIG. 1A. The arrangement shown in FIG. 2A promises a particularly high saving of energy or a particularly efficient use of low-calorific energy.

[0060] Preheating of the boiler feed water may also be assisted by virtue of an additional economizer being arranged in the flue gas duct 2. Optionally, it is also possible to use for example a third calorifier (not illustrated), wherein, between the second calorifier 16 and the third calorifier, the boiler feed water could then be preheated again. Downstream of the KSW preheater 6a, it would thus be possible for a further calorifier and a further KSW preheater to be arranged between the KSW preheater 6a and the separator 7.

[0061] FIG. 2B shows, in a modification to FIGS. 1A, 1B, 2A, an arrangement in which the first calorifier 15 is optionally omitted and further components (illustrated by dashed lines) are also optionally omitted.

[0062] FIG. 3 shows, in a modification to FIGS. 2A, 2B, an arrangement in which the boiler feed water is at any rate firstly conducted to the cooling section 17 for preheating before heat exchange with combustion air is realized.

LIST OF REFERENCE SIGNS

[0063] 1 Reformer [0064] 2 Flue gas duct (convection bank) [0065] 3 Process gas cooler [0066] 4 PK evaporator, in particular having two bundles [0067] 5 CO shift reactor or HTS (high temperature shift) means or MT shift means or HT-LT shift means [0068] 6 External heat exchanger (FIGS. 1A, 1B) [0069] 6a (External) KSW preheater (FIGS. 2A, 2B; FIG. 3) [0070] 7 First separator or PK separator (hot separator) [0071] 8 Air cooler [0072] 9 Final cooler or water cooler [0073] 10 Second separator or PK separator (cold separator) [0074] 1 Steam drum (for KSW evaporation) [0075] 12 KSW evaporator [0076] 13 Internal air preheater arranged in the flue gas duct [0077] 14 Economizer or internal preheater for KSW [0078] 15 First calorifier, in particular external air preheater [0079] 16 Further calorifier, in particular external air preheater (FIGS. 2A, 2B; 3) [0080] 17 Cooling section [0081] 20 Heat energy recovery arrangement [0082] 30 Measurement device [0083] 31 Sensor unit [0084] 40 Logic unit [0085] FG Feed/steam mixture [0086] KSW Boiler feed water [0087] PK Process condensate [0088] PV Process steam [0089] RG Flue gas [0090] SG Synthesis gas or cracking gas or process gas [0091] SG10 Discharged synthesis gas stream, optionally to the pressure swing adsorption unit (PSA) [0092] SV Saturated steam [0093] VL Combustion air