WO2023165816A1

WO2023165816A1 - System for steam and/or heat generation and method for operating the same

Info

Publication number: WO2023165816A1
Application number: PCT/EP2023/053845
Authority: WO
Inventors: Salman Azmat CHAUDHRY; Steffen GAU; Johannes Hartz; Gerhard Schlegl
Original assignee: MAN Energy Solutions SE
Current assignee: MAN Energy Solutions SE
Priority date: 2022-03-03
Filing date: 2023-02-16
Publication date: 2023-09-07
Anticipated expiration: 2024-09-03
Also published as: DE102022105052B4; DE102022105052A1

Abstract

System and method for steam and/or heat generation A system (10) for steam generation and/or heat generation, having at least one compression stage (11), wherein the compression stage (11) or the respective compression stage (11) comprises a compressor (12) which is equipped to compress steam, starting from an inlet pressure of the compressor (12) or of the respective compressor (12) to an outlet pressure of the compressor (12) or of the respective compressor (12), having at least one expansion stage (17), wherein the expansion stage (17) or the respective expansion stage (17) comprises at least one expansion valve (18) which is equipped to expand condensate, having an evaporator (20) which is equipped to supply heat to the condensate downstream of the expansion stage (17) or the lowest expansion stage (17), having a thermal storage device (25) comprising a cold storage tank (25a) and a heat storage tank (25b), and which is equipped, for charging the storage device (25) and thus for storing energy, to extract a storage medium out of the cold storage tank (25a), conduct the same via a heat exchanger (27) positioned downstream of the compressor (12) or of the respective compressor (12) and to supply the storage medium thus heated to the heat storage tank (25b), and for discharging the storage device (25) and thus for outputting energy, to extract the storage medium out of the heat storage tank (25b) and supply the same to a heat consumer.

Description

System for steam and/or heat generation and method for operating the same

The invention relates to a system for steam generation and/or heat generation and to a method for operating such a system .

For a multiplicity of di f ferent processes , the generation of steam and/or heat is required . To date , heat generators fired with fos sil fuels are being employed for this purpose . However, employing heat generators fired by fossil fuels for providing steam and/or heat is becoming increasingly uneconomical because of rising oil prices or gas prices . Heat generators fired with fossil fuels also have the disadvantage of having exhaust emissions . Starting out from this , the obj ect of the present invention is based on creating a new type of system for steam generation and/or heat generation and to a method for operating such a system for steam generation and/or heat generation which is free of emissions and has a high ef ficiency .

This obj ect is solved through a system for steam generation and/or heat generation according to Claim 1 .

The system for steam generation and/or heat generation comprises at least one compression stage , wherein the compression stage or the respective compression stage includes a compressor which is equipped to compress steam, starting out from an inlet pressure of the compressor or of the respective compressor to an outlet pressure of the compressor or of the respective compressor .

Preferentially, the compressed steam, emanating from the compression stage or the highest compression stage can be supplied in an open system directly to a steam consumer or in a closed system to a condenser and a heat exchanger . The highest compression stage is the one compression stage downstream of which the compressed steam has the highest pressure .

The system for steam generation and/or heat generation further comprises at least one expansion stage , wherein the expansion stage or the respective expansion stage includes at least one expansion valve which is equipped to expand a condensate .

The system for steam generation and/or heat generation, further, comprises an evaporator which is equipped to supply heat to the condensate downstream of the expansion stage or the lowest expansion stage . The lowest expansion stage is the one expansion stage downstream of which the expanded condensate has the lowest pressure .

Further, the system for steam generation and/or heat generation comprises a thermal storage device which includes a cold storage tank and a heat storage tank .

For charging the storage device and thus for energy storage , the thermal storage device is equipped to extract a storage medium from the cold storage tank, conduct the same via a heat exchanger positioned downstream of the compressor or of the respective compressor and to supply the storage medium heated by way of this to the heat storage tank . Further, the thermal storage device is equipped to extract the storage medium from the heat storage tank for unloading the storage device and thereby output energy, and to supply the said storage medium to a heat consumer .

Preferentially, the thermal storage device is equipped to discharge the storage device and thereby, for outputting energy, conduct the heat storage medium from the heat storage tank via a heat exchanger and subsequently to the heat discharge in the heat exchanger supply the said storage medium to the cold storage tank . The system according to the invention allows a highly ef ficient generation of steam and/or heat . In the region of the evaporator, the system is supplied with energy, namely ambient heat or waste heat , further electric current as drive energy for in particular the at least one compressor . The system generates usage energy in the form of heat and/or steam .

A part of the usage energy can be stored via the thermal storage device and utilised on a deferred basis . The portion of the amount of energy that can be stored in the thermal storage system preferentially amounts to the order of magnitude between 20% and 50% , in particular in the magnitude between 20% and 40% . The thermal storage device can be activated and deactivated as desired .

Preferentially, the cold storage tank and the heat storage tank are formed as two-tank system or as one-tank system with a strati fied storage tank . A two-tank system allows a simple separation of the cold storage tank and heat storage tank . A one-tank system having a strati fied storage tank requires less installation space .

Preferentially, the storage medium is molten salt or thermal oil . Molten salt and thermal oil are particularly suited as storage medium of the thermal storage device . However, another storage medium can also be employed which, in a temperature range of in particular between 110 ° C to 550 ° C, can absorb and output heat .

Preferentially, the evaporator is part of a heat pump cascading to the at least one compression stage and the at least one expansion stage . I f the temperature level in the region of the evaporator be inadequate for supplying suf ficient heat to the condensate it is advantageous when the evaporator is part of a heat pump cascading to the at least one compression stage and the at least one expansion stage . By way of such a heat pump, the temperature level in the region of the evaporator can be adapted .

Preferentially, the expansion stage or at least one of the expansion stages additionally to the expansion valve comprises a condensate reservoir, which is equipped to separate steam created during the expansion of the condensate in the respective condensate reservoir, wherein the steam separated in the condensate reservoir of a respective expansion stage can be supplied via a steam line of a compression stage downstream of the compressor to the respective compression stage . Preferentially, condensate can be supplied to the respective compression stage via a condensate line of the compression stage likewise upstream of the compressor of the respective compression stage , namely upstream of the steam supply into the respective compression stage via the respective steam line . By introducing the condensate and/or steam into the steam to be compressed in the region of a compression stage upstream of the respective compressor of the respective compression stage an interstage cooling can be provided . By way of this , the ef ficiency of the system according to the invention can be increased, preferentially in particular when the thermal storage device is not operated for energy storage in the storage medium .

The method according to the invention for operating the system for steam generation and/or heat generation is defined in Claim 11 .

Preferred further developments of the invention are obtained from the subclaims and the following description . Exemplary embodiments of the invention are explained in more detail by way of the drawing without being restricted to this .

There it shows : Fig. 1: a block diagram of a system according to the invention,

Fig. 2: a logP-h diagram for further illustrating the invention,

Fig. 3: a logP-h diagram for further illustrating the invention .

Fig. 1 shows a block diagram of a system 10 for steam generation and/or heat generation according to the invention. Basically, the system 10 has two-part systems 10a, 10b, wherein the part system 10a is designed in the form of a water-heat pump or H²0 heat pump, and wherein the part system 10b is a storage device for storing thermal energy .

The system 10, namely the part system 10a of the same, has at least one compression stage 11, wherein in Fig. 2 two compression stages 11-1 and 11-n are shown. The number n of the compression stages 11 is arbitrary and can be for example 10 or 20.

Each compression stage 11 has a compressor 12, namely the compression stage 11-1, the compressor 12-1 and the compression stage 11-n, the compressor 12-n. The respective compressor 12 is equipped to compress steam, starting from an inlet pressure of the respective compressor 12 to an outlet pressure of the respective compressor 12.

The compression stage 11-1 is the lowest compression stage and the compression stage 11-n the highest compression stage. The lowest compression stage 11-1 is the one compression stage upwards of which the steam to be compressed has the lowest pressure. The highest compression stage 11-n is the one compression stage, downstream of which the compressed steam has the highest pressure. Originating from the compression stage or the highest compression stage 11-n, the steam compressed in the at least one compression stage 11 can be supplied in an open system directly to steam consumers or in the closed system shown in Fig . 1 to a condenser 13 and at least one heat exchanger 14 , 15 . The outlet pressure of the highest compression stage 11- n is preferentially selected so that the associated condensation temperature corresponds to the usage temperature . In the open system, the steam can then be supplied from the compressor 12-n of the highest compression stage 11-n directly to steam consumers . In the closed system, the steam condenses in the condenser 13 and in the region of at least one heat exchanger 14 , 15 , heat is trans ferred to a heat trans fer medium . The condensate is collected in a condensate reservoir 16 .

The system 10 , namely the part system 10a, further has at least one expansion stage 17 , wherein in Fig . 1 two expansion stages 17- 1 and 17-n are shown . The expansion stage 17-n is the highest expansion stage and the expansion stage 17 - 1 is the lowest expansion stage . The highest expansion stage 17 - n is the one expansion stage upstream of which the condensate to be expanded has the highest pressure . The lowest expansion stage 17- 1 is the one expansion stage downstream of which the expanded condensate has the lowest pressure .

In the shown exemplary embodiment , each expansion stage 17 has an expansion valve 18 , namely the expansion stage 17- 1 the expansion valve 18- 1 and the expansion stage 17-n the expansion valve 18-n . Each expansion valve 18 is equipped to expand condensate .

In Fig . 1 , the number n of the expansion stages 17 corresponds to the number n of the compression stages 11 . As a modi fication of this it is also possible , as shown in Fig . 1 in dashed lines , that the number of the expansion stages 17 is smaller than the number of compression stages 11 . Accordingly it is shown by the dashed lines of Fig . 1 that merely one expansion stage 17 can also interact with multiple compression stages 11 , which expansion stage 17 will then in turn have an expansion valve 18 that is equipped to expand condensate . It is likewise possible to by design combine multiple expansion stages 17 to form an expansion stage 17 .

Condensate , which is stored in the condensate reservoir 16 , is initially expanded via the expansion valve 18-n of the highest expansion stage 17-n, preferentially into a condensate reservoir 19-n of the said expansion stage 17 -n . In the region of the said condensate reservoir 19-n, steam developing during the expansion can be separated from the condensate . Although in Fig . 1 merely in the region of the expansion stage 17 -n a condensate reservoir 19-n is shown, such a condensate reservoir 19 can also be present in the region of each expansion stage 17 , i . e . also in the region of the expansion stage 17 - 1 , downstream of the respective expansion valve 18 .

Further, the system 10 has an evaporator 20 which is equipped to supply heat to the condensate downstream of the expansion stage or the lowest expansion stage 17- 1 . In the evaporator 20 , ambient heat or waste heat is supplied to the condensate .

The higher the temperature level of the heat source is the more ef ficient can the evaporation pressure for the part system 10a be selected . Possible evaporation pressures are from approximately 0 . 03 bar, depending on temperature level of the evaporator 20 .

I f required, the evaporator 20 can be part of a heat pump 21 cascading to one of the at least one compression stage 11 and the at least one expansion stage 17 , which in addition to the evaporator 20 includes a compressor 22 , an expansion valve 23 and a heat exchanger 24 . The system 10 , furthermore , has a thermal storage device 25 which comprises a cold storage tank 25a and a heat storage tank 25b . The storage tanks 25a, 25b are part of the partsystem 10b .

The storage device 25 is equipped, for charging the storage device 25 and thus for storing energy, to extract a storage medium out of the cold storage tank 25a via a pump 26 and conduct the same via at least one heat exchanger 27 positioned downstream of a compressor 12 of a compression stage 11 and subsequently supply the storage medium heated in the process to the heat storage tank 25b . In the region of each compression stage 11 - 1 , 11-n, a heat exchanger 27- 1 , 27 -n is arranged, in Fig . 1 , downstream of the respective compressor 12 - 1 , 12-n, via which heat exchanger 27 - 1 , 27 -n the thermal storage medium can be conducted for absorbing energy .

Further, the storage device 25 is equipped to discharge the same and thus for outputting energy, supply the storage medium, originating from the heat storage tank 25b via a pump 28 to a heat consumer .

In an open system, the storage medium extracted from the heat storage tank 25 can be directly supplied to a heat consumer .

In the closed system shown in Fig . 1 , the storage medium extracted from the heat storage tank 25 can be conducted via at least one heat exchanger 29 , 30 and an evaporator 31 connected between these . In the region of the evaporator 31 , saturated or even super-heated steam while utilising thermal energy stored in the storage medium can be generated . The storage medium cooled down in the process is then supplied again to the cold storage tank 25a . The heat exchanger 30 is a preheater and the heat exchanger 29 is a super-heater . In the system 10 shown in Fig . 1 , a heat supply into the condensate , namely into the water (H2O ) accordingly takes place in the region of the evaporator 20 of the part system 10a, at the pressure level downstream of the lowest expansion stage 17 - 1 . Downstream of the evaporator 20 , a compression of the steam takes place in the region of at least one compression stage 11 of the part system 10a, preferentially in the region of multiple compression stages 11 , wherein the pressure level of the highest compression stage 11-n is selected so that the associated condensation temperature corresponds to the usage temperature of the part system 10a .

Condensate is collected in the condensate reservoir 16 of the part system 10a, which is arranged upstream of the highest expansion stage 17-n . In at least one expansion stage 17 of the part system 10a, preferentially in multiple expansion stages 17 , the expansion of the condensate collected in the condensate reservoir 16 takes place via a respective expansion valve 18 , wherein in the region of the expansion stages 17 downstream of the respective expansion valve 18 of the respective expansion valve 17 preferentially a condensate reservoir 19 is present , which in the part system 10a of the system 10 serves for separating the steam resulting during the expansion of the condensate from the respective remaining condensate .

The storage device 25 of the part system 10b of the shown system 10 can absorb in a first operating mode of the same , heat of the steam of the H²0 water pump of the part system 10a . By way of this heat extraction via the storage medium, which is conducted via the at least one heat exchanger 27 , a cooling or inter-stage cooling takes place in the circuit of the part system 10a . Preferentially, molten salt or thermal oil or another medium is employed as thermal storage medium which preferentially in a temperature range between 100 ° C and 550 ° C can absorb and output heat . In Fig . 1 , the storage device 25 has a two-tank system consisting of the cold storage tank 25 and the heat storage tank 25b . As alternative , a one-tank system with a strati fied storage tank can also be utilised .

For charging the storage device 25 and thus for storing energy in the storage medium, the cold storage medium with a temperature of between 150 ° C and 250 ° C is extracted from the cold storage tank 25a and supplied to the at least one heat exchanger 27 . There it is heated to a temperature of between 300 ° C and 550 ° C and subsequently conducted into the heat storage tank 25b where it is stored for any time which can amount to multiple days and weeks . For discharging the storage device 25 and thus outputting energy, a hot storage medium is extracted from the heat storage tank 25 via the pump 28 and conducted in the direction of a heat consumer .

The system 10 is supplied with electric current , in particular for driving the compressors 12 and the pumps 26 , 28 as drive energy . In the region of the evaporator 20 , ambient heat or waste heat is supplied to the system 10 . The system 10 generates usage energy in the form of heat and/or steam . A part o f the usage energy can be stored via the thermal storage device 25 and output at a later time . The portion of the energy quantity that is stored in the storage device 25 is between 20% and 50% , in particular between 20% and 40% . The storage device 25 can be activated and deactivated as required .

As already explained, the condensate reservoir 19-n is present in Fig . 1 in the region of the expansion stage 17-n downstream of the expansion valve 18-n, in which steam can be separated . This separated steam can be conducted via a steam line 32 in the direction of the compression stage 11- n upstream of the compressor 12-n and supplied upstream of the compressor 12-n to the compressed steam for inter-stage cooling . Preferentially, the pressure level of the steam, which is conducted via the steam line 32 from the condensate reservoir 19-n in the direction of the compressor 12 -n, is at the pressure level of the steam upstream of the compressor 12-n . A valve 33 is connected into the steam line 32 .

Further, Fig . 1 shows a condensate line 34 via which condensate can be conducted from the condensate reservoir 16 in the direction of the compression stage 11-n, namely again in the direction of the compressor 12-n upstream of the same . This condensate is preferentially expanded in the region of an expansion valve 35 integrated in the condensate line 34 and introduced upstream of the steam supply via the steam line 32 into the compressed steam, as a result of which a further inter-stage cooling can be provided . Likewise , the condensate line 34 can discharge condensate from the condensate reservoir 19 and the condensate introduced into the compressed steam .

When the pressure of the condensate in the condensate reservoir 19 or in the condensate reservoir 16 is greater than the pressure in the steam line upstream of the compressor 12 , the condensate , because of the pressure di f ferential , flows into the steam line . When the pressure in the condensate reservoir 19 or in the condensate reservoir 16 is lower than in the steam line upstream of the compressor 12 , a pump is required for introducing the condensate .

Accordingly, introducing the steam via the steam line 32 takes place downstream of the condensate supply via the condensate line 34 . By way of the inter-stage cooling actions , the ef ficiency of the part system 10a and thus ultimately of the overall system 10 can be increased . The inter-stage cooling of the steam via a steam introduction and/or condensate introduction takes place preferentially in particular when in a second operating mode of the storage device 25 no storage medium is conducted via the heat exchanger 27 positioned downstream of the respective compressor 12, i.e. when no energy for storing is transferred from the part system 10a into the part system 10b.

Fig. 1 shows a further condensate line 36 via which condensate can be extracted from the condensate reservoir 16 in order to introduce the condensate downstream of the highest compression stage 11-n into the steam present at the highest pressure level, as a result of which a regulation of the steam parameters ( saturated/super-heated) can take place. In this condensate line 36 according to Fig. 1 an expansion valve 37 and a pump are integrated.

As explained above, an inter-stage cooling by way of the heating of the thermal storage medium in the region of the heat exchanger 27 takes place during the operation of the thermal storage device 25. In the event that the thermal storage device 25 is not operated, i.e. no heat from the part-system 10a can be extracted into the part-system 10b, inter-stage cooling can take place via the condensate supply and/or steam supply described above upstream of the compressor 12 of the respective compression stage 11.

Fig. 2 and 3 show logP-h diagrams for illustrating the function principle of the system according to the invention, wherein on the horizontal X-axis the enthalpy-h is plotted linearly and on the vertical Y-axis the pressure P logarithmically. Fig. 2 illustrates the process in the system 10 in particular when via the storage device 25 energy storing into the storage medium takes place, namely in that out of the cold storage tank 25 the storage medium is extracted and for heating conducted via the heat exchanger 27. Accordingly, Fig. 2 shows the compression 12 '-1, 12 ' -n in the region of the compressors 12-1 and 12-n and the extraction 27'-1.27'-n of thermal energy from the partsystem 10a and thus the storing of thermal energy in the part-system 10b via the heat exchangers 27-1 and 27 -n respectively. Further, Fig. 2 shows the condensation 13' in the region of the condenser 13, a single-stage expansion 17' in the region of an expansion stage 17 and an evaporation 20' in the region of the evaporator 20. A dew line 38 and a boiling line 39 delimit a two-phase area 40 in the logP-h diagram for the part-system 10a and accordingly for the H²0 heat pump.

While Fig. 2 shows the logP-h diagram for the case in which from the part system 10a heat is stored into the part system 10b, Fig. 3 shows the logP-h diagram for the case for which the part system 10b is inactive, for which thus no heat from the part system 10a is transferred into the part system 10b. Thus, in Fig. 3, no energy storage into the storage medium of the part system 10b takes place via the storage device 25. In Fig. 3, a two-stage expansion 17'-1 and 17'-n takes place in the expansion stages 17-1 and 17-n and a three- stage compression 12 '-1, 12 '-2 and 12 ' -n in compression stages 12-1, 12-2 and 12-n. Further, Fig. 3 visualises the condensate introduction 34' from the condensate reservoir 16 via the condensate line 34 into the respective compression stage 12-2, 12-n, and the steam introduction 32' via the steam line 32, further also the condensation 13' in the region of the condenser 13 and the evaporation 20' in the region of the evaporator 20.

List of reference numbers

10 System

10a Part-system

10b Part-system

11 Compression stage

12 Compressor

13 Condenser

14 Heat exchanger

15 Heat exchanger

16 Condensate reservoir

17 Expansion stage

18 Expansion valve

19 Condensate reservoir

20 Evaporator

21 Heat pump

22 Compressor

23 Expansion valve

24 Heat exchanger

25 Storage device

25a Cold storage tank

25b Heat storage tank

26 Pump

27 Heat exchanger

28 Pump

29 Super-heater

30 Preheater

31 Evaporator

32 Steam line

33 Valve

34 Condensate line

35 Expansion valve

36 Condensate line

37 Expansion valve

38 Dew line

39 Boiling line

40 2-phase region

Claims

CLAIMS A system (10) for steam generation and/or heat generation, having at least one compression stage (11) , wherein the compression stage (11) or the respective compression stage (11) comprises a compressor (12) which is equipped to compress steam, starting from an inlet pressure of the compressor (12) or the respective compressor (12) to an outlet pressure of the compressor (12) or the respective compressor (12) , having at least one expansion stage (17) , wherein the expansion stage (17) or the respective expansion stage (17) comprises an expansion valve (18) which is equipped to expand condensate, having an evaporator (20) which is equipped to supply heat to the condensate downstream of the expansion stage (17) or the lowest expansion stage (17) , having a thermal storage device (25) which comprises a cold storage tank (25a) and a heat storage tank (25b) and which is equipped, for charging the storage device (25) and thus storing energy, to extract a storage medium from the cold storage tank (25a) , conduct the same via a heat exchanger (27) positioned downstream of the compressor (12) or of the respective compressor (12) and supply the storage medium thus heated to the heat storage tank (25b) , for discharging the storage device (25) and thus outputting energy, to extract the storage medium out of the heat storage tank (25b) and supply the same to a heat consumer. The system (10) according to Claim 1, characterised in that the outlet pressure of the or the highest compression stage (11) is selected so that an associated condensate temperature corresponds to a usage temperature to be provided. The system (10) according to Claim 1 or 2, characterised in that the expansion stage (17) or at least one of the expansion stages (17) in addition to the expansion valve (18) includes a condensate reservoir (19) , which is equipped to separate steam developing during the expansion of the condensate in the respective condensate reservoir (19) , a steam line (32) is equipped to supply steam separated in the condensate reservoir (19) of a respective expansion stage (17) to a compression stage (11) upstream of the compressor (12) of the respective compression stage (11) . The system (10) according to Claim 3, characterised by a condensate line via which condensate from the condensate reservoir (19) of the respective expansion stage (17) can be supplied to a compression stage (11) upstream of the compressor (12) of the respective compression stage (11) , namely upstream of the steam supply into the respective compression stage (11) via the respective steam line (32) . The system (10) according to any one of the Claims 1 to 4, characterised by a condensate reservoir (16) , which is arranged upstream of the expansion stage (17) or the highest expansion stage (17) . The system (10) according to Claim 5, characterised by a condensate line (36) which is equipped to supply condensate from the condensate reservoir (16) to the steam compressed in the compression stage (11) or the highest compression stage (11) downstream of the compressor (12) , and/or a condensate line (34) , which is equipped to supply condensate from the condensate reservoir (16) to the compression stage (11) or on of the compression stages (11) upstream of the compressor (12) of the same, namely upstream of the steam supply into the respective compression stage (11) via the respective steam line (32) . The system (10) according to any one of the Claims 1 to

6, characterised in that the evaporator (20) is part of a heat pump (21) cascading to the at least one compression stage (11) and the at least one expansion stage ( 17 ) . The system (10) according to any one of the Claims 1 to

7, characterised in that the number of the expansion stages (17) corresponds to the number of the compression stages (11) , or that the number of the expansion stages (17) is smaller than the number of the compression stages (11) .

The system (10) according to any one of the Claims 1 to 8, characterised in that the storage medium is molten salt or thermal oil. The system (10) according to any one of the Claims 1 to 9, characterised in that the cold storage tank (25a) and the heat storage tank (25b) are formed as two-tank system or as one-tank system with a stratified storage tank . A method for operating a system (10) for steam generation and/or heat generation according to any one of the Claims 1 to 10, in particular when for storing energy the storage medium is conducted via the heat exchanger (27) positioned downstream of the respective compressor (12) , by way of this an inter-stage cooling of the steam takes place, in particular when no storage medium is conducted via the heat exchanger (27) positioned downstream of the respective compressor (12) , an inter-stage cooling of the steam takes place via a steam introduction and/or a condensate introduction upstream of the respective compressor (12) .