The invention relates to a system for steam generation and/or heat generation . Further, the invention relates to a method for steam generation and/or heat generation .

For a multiplicity of di f ferent processes , the generation of steam and/or heat is required . To date , heat generators fired by fossil fuels have been used . The use of heat generators fired by fossil fuels for providing steam and/or heat however becomes 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 present invention is based on the obj ect of creating a new type of system and method for steam generation and/or heat generation which is free of emissions and highly ef ficient . 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 includes a compression unit comprising multiple compression stages , wherein each compression stage comprises a compressor which is equipped to compress steam, starting from an inlet pressure of the respective compressor, to an outlet pressure of the respective compressor . The inlet pressure of the respective compressor is also referred to as suction pressure of the respective compressor .

The system for steam generation and/or heat generation further includes an expansion unit comprising multiple expansion stages , wherein each expansion stage includes an expansion valve and a condensate reservoir, wherein the respective expansion valve is equipped to expand condensate into the respective condensate reservoir and wherein the respective condensate reservoir is equipped to separate steam created during the expansion of the condensate in the respective condensate reservoir .

The system for steam generation and/or heat generation further includes multiple steam lines , wherein each steam line is equipped to supply steam separated in a condensate reservoir of an expansion stage to a compression stage upstream of the compressor of the respective compression stage . The system for steam generation and/or heat generation for steam generation and/or heat generation further includes multiple condensate lines , wherein each condensate line is equipped to supply condensate out of a condensate reservoir of an expansion stage to a compression stage upstream of the compressor of the respective compression stage , namely upstream of the steam supply into the respective compression stage .

The invention present here proposes a system which comprises multiple compression stages and multiple expansion stages . The compression stages and the expansion stages are coupled in a defined manner, namely via the steam lines and the condensate lines .

By way of a respective steam line , steam, originating from an expansion stage , can be supplied to a compression stage upstream of the compressor preferentially in such a manner that the steam separated from the condensate reservoir in the region of the respective expansion stage is at the pressure level upstream of the respective compressor of the respective compression stage , to which the steam is supplied .

By way of a respective condensate line , condensate out of a condensate reservoir of a respective expansion stage can be supplied to a respective compression stage upstream of the compressor, namely upstream of the steam supply into the respective compressor stage , wherein the condensate , which is conducted in the direction of the respective compressor stage , has a higher pressure level than the inlet pressure of the respective compressor stage in the direction of which the condensate is conducted .

The order of condensate supply and steam supply is signi ficant in order to facilitate the evaporation . Initially, the condensate supply and subsequently the steam supply out of a respective expansion stage takes place in the region of a respective compressor stage upstream of the compressor of the respective compressor stage .

By way of this supply of condensate and steam into a compressor stage upstream of the respective compressor of the same , the compression of the steam can take place across all stages along or approximately along the dew line . The expansion of condensate in the expansion stages can take place along or approximately along the boiling line . With the invention it is possible to generate or provide steam and/or heat without emission and with high ef ficiency for a process .

Preferentially, the outlet pressure of the last or highest compression stage is selected so that an associated condensation temperature corresponds to a usage temperature or process temperature to be provided . In an open system, the steam can, emanating from the compressor of the last or highest compressor stage , directly to steam consumers . The last or highest compression stage is the one compression stage downstream of which the compres sed steam has the highest pressure .

Preferentially, the system includes a condenser, which is connected between the last or highest compression stage and the first or highest expansion stage , and/or a condensate reservoir which is preferentially arranged upstream of the first or highest expansion stage and equipped to supply condensate to the expansion valve of the first or highest expansion stage . The condensate reservoir can be present in the case of a closed system and an open system . The condenser is typically present only with a closed system . The first or highest expansion stage is the one expansion stage upstream of which the condensate to be expanded has the highest pressure .

Preferentially, the system for steam generation and/or heat generation includes an evaporator connected between the last or lowest expansion stage and the first or lowest compression stage , which is equipped to supply heat to the condensate at the lowest pressure level . The last or lowest expansion stage is the one expansion stage downstream of which the expanded condensate has the lowest pressure . The first or lowest compression stage is the one compression stage upstream of which the steam to be compressed has the lowest pressure . By way of this , heat can be supplied to the process and thus the condensate at the lowest pressure level of the condensate . The more heat can be supplied to the condensate at the lowest pressure level , the less compression work is necessary in order to achieve the necessary target pressure downstream of the compressor of the last or highest compression stage . The pressure at the lowest pressure level , in which the heat supply takes place via the evaporator, is typically limited by design to a pressure of approximately 0 . 01 bar . This then corresponds to an evaporation temperature of approximately 7 ° C . With respect to its temperature level the evaporator has to be above that . Should the minimum temperature of the evaporator be insuf ficient in order to supply heat to the condensate , it is advantageous when the evaporator is part of a refrigeration unit cascading to the compression stages and expansion stages . Preferentially, the system for steam generation and/or heat generation includes a heat exchanger downstream of the last or highest compression stage and/or a heat exchanger, which is coupled between two compression stages and each of which is equipped to extract heat from the steam . By way of such a heat exchanger, heat can be extracted and supplied to a process .

Preferentially, the system for steam generation and/or heat generation includes a venting unit which is equipped to separate air upstream of the first or highest expansion stage . Should air enter the condensate , this can be separated via the vent valve .

Preferentially, the number of the expansion stages corresponds to the number of the compression stages , wherein in the region of each compression stage a suction pressure of the respective compressor corresponds to the expansion pressure of one of the expansion stages . Alternatively, the number of the expansion stages is smaller than the number of the compression stages , wherein in the region of a compression stage of multiple compression stages each a suction pressure of the respective compressor corresponds to the expansion pressure of one of the expansion stages . In particular, when the number of the compression stages corresponds to the number of the expansion stages , each compression stage upstream of the respective compressor can be supplied with steam from a corresponding expansion stage at the pressure level upstream of the respective compressor and thus at the suction pressure level of the respective compressor . By supplying the condensate emanating from the condensate reservoir to an expansion stage operating at a higher pressure level , an optimal inter-stage cooling of the steam to be compressed can then take place . For reducing the equipment expenditure and the costs of the system for steam generation and/or heat generation, it is also possible however that the number of the expansion stages is smaller than the number of the compression stages, so that multiple stages are then combined before a next inter-stage cooling takes place.

The method according to the invention is defined in Claim 15.

Preferred developments of the invention are obtained from the subclaims and the following description. Exemplary embodiments of the invention are explained in more details by way of the drawing without being restricted to this. There it shows:

Fig. 1: a block diagram of a first system according to the invention,

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

Fig. 3: a COP-T diagram for further illustrating the invention,

Fig. 4: a block diagram of a second system according to the invention.

Fig. 1 shows an exemplary embodiment of a system 10 according to the invention.

The system 10 is equipped with multiple compression stages 11-1 to 11-n, wherein in Fig. 1 merely three compression stages 11-1, ll- (n-l) and 11-n are shown. The number n of the compressor stages can be for example up to n=10 or n=20. This number n of the compressor stages however is purely exemplary in nature. Each of the compressor stages 11 is equipped with a compressor 12, namely the compressor stage 11-1 via the compressor 12-1, the compressor stage ll- (n-l) via the compressor 12- (n-l) and the compressor stage 11-n via the compressor 12-n. Each of the compressors 12 is equipped to compress steam, emanating from an inlet pressure or suction pressure of the respective compressor 12 to an outlet pressure of the respective compressor 12.

The compression stage 11-1 is the first or lowest compression stage, the compression stage 11-n is the last or highest compression stage. The last or highest compression stage 11-n is the one compression stage downstream of which the compressed steam has the highest pressure. The first or lowest compression stage 11-n is the one compression stage upstream of which the steam to be compressed has the lowest pressure.

Furthermore, the system 10 of Fig. 1 is equipped with multiple expansion stages 13, namely the expansion stages 13-1 to 13-n, wherein in Fig. 1 in turn merely three expansion stages 13-1, 13- (n-l) and 13-n are shown. In Fig. 1, the number n of the compression stages 12 corresponds to the number n of the expansion stages 13. The number of the expansion stages 13 however can also be smaller than the number of the compressor stages 12.

The expansion stage 13-n is the first or highest expansion stage and the expansion stage 13-1 is the last or lowest expansion stage. The last or lowest expansion stage 13-1 is the one expansion stage downstream of which the expanded condensate has the lowest pressure. The first or highest expansion stage 13-n is the one expansion stage upstream of which the condensate to be expanded has the highest pressure. The condensate is water. Each expansion stage 13 is equipped with an expansion valve 14 and a condensate reservoir 15. Accordingly, the expansion stage 13-1 is equipped with the expansion valve 14-1 and the condensate reservoir 15-1. The expansion stage 13-n is equipped with the expansion valve 14-n and the condensate reservoir 15-n. The expansion stage 13- (n-l) is equipped with the expansion valve 14- (n-l) and the condensate reservoir 15- (n-l) .

The respective expansion valve 14 is equipped to expand condensate into the respective condensate reservoir 15 of the respective expansion stage 13, wherein the respective condensate reservoir 15 of the respective expansion stage 13 is equipped to separate steam developing during the expansion of the condensate in the respective condensate reservoir 15 from the condensate.

The system 10 is equipped with multiple steam lines 16. Accordingly, the steam lines 16-1, 16- (n-l) and 16-n are shown in Fig. 1 wherein each steam line 16 is equipped to supply steam separated in a condensate reservoir 15 of an expansion stage 13 to a compression stage 11 upstream of the compressor 12 of the respective compression stage 11. Accordingly, by way of the steam line 16-1 in Fig. 1, steam separated in the region of the condensate reservoir 15-1 can be supplied to the compression stage 11-1 upstream of the compressor 12-1. Steam separated in the region of the condensate reservoir 15- (n-l) of the expansion stage 13- (n- 1) can be supplied via the steam line 16- (n-l) to the compression stage ll- (n-l) upstream of the compressor (12— (n-1) . Likewise, steam which is separated from condensate in the condensate reservoir 15-n of the expansion stage 13- n, can be supplied via the steam line 16-n to the compression stage 11-n upstream of the compressor 12-n. The steam conducted from the respective condensate reservoir 15 via the respective steam line 16 in the direction of the respective compressor stage 11 upstream of the respective compressor 12 is present at that pressure level which corresponds to the suction pressure level upstream of the respective compressor 12 of the respective compression stage 11 .

According to Fig . 1 , the system for steam generation and/or heat generation 10 shown there furthermore includes the multiple condensate lines 17 , wherein via each condensate line 17 , condensate out of a condensate reservoir 15 of an expansion stage 13 can be supplied to a compression stage 11 upstream of the respective compressor 12 of the respective compression stage 11 , namely upstream of the steam supply via the steam line 16 of the respective compression stage 11 .

The pressure level of the condensate conducted via the respective condensate line 17 in the direction of the respective compression stage 11 is at a higher pressure level than the suction pressure level present upstream of the respective compressor 12 of the respective compression stage 11 .

In Fig . 1 , the condensate from the condensate reservoir 15- n can be supplied via the condensate line 17- (n- l ) of the compression stage l l- (n- l ) upstream of the compressor 12- (n- 1 ) , namely upstream of the steam supply via the steam line 16- (n- l ) . In the region of the compression stage 11 -n, condensate , which is kept ready in a condensate reservoir 18 arranged upstream of the first or highest expansion stage 13-n can be supplied via the condensate line 17-n upstream of the compressor ( 12 -n) to the compression stage ( 11-n) , namely upstream of the steam supply into the compression stage 11 -n that took place through the steam line 16-n . in Fig . 1 , not only the condensate reservoir 18 is connected between the last or highest compression stage I l n and the first or highest compression stage 13-n, but additionally a condenser upstream of the condensate reservoir 18 . In a closed system, the steam, emanating from the last or highest compression stage 11 -n, can be conducted via the condenser 19 and the condensate collected in the condensate reservoir 18 .

In an open system, the condenser 19 can be omitted in order to supply the steam present downstream of the last or highest compression stage 11-n to a steam consumer or customer . Emanating from the steam consumer, the condensate can then be conducted in the direction of the condensate reservoir 18 , dependent on the pressure level of the respective condensate also to at least one of the condensate reservoirs 15 .

Downstream of the last or lowest expansion stage 13- 1 , the lowest pressure level in the system 10 and thus in the condensate is present at the lowest pressure level , where in between the last or lowest expansion stage 13- 1 and the first or lowest compression stage 11- 1 an evaporator 20 is connected which is equipped to supply heat to the condensate or water at the lowest pressure level . The higher a pressure level in the region of the evaporator 20 , the higher can the evaporation pressure be selected and the less compression work is necessary in order to ensure via the compressors 12 the steam to be provided downstream of the last or highest compression stage 11-n .

In the compression stages 11 and in the expansion stages 13 , water (H ² O) is compressed or expanded as working medium .

Fig . 1 shows an optional refrigeration machine 21 , in which the evaporator 20 is integrated and which is coupled to the compression stages 11 and the expansion stages 13 in the sense of a cascade . In such a refrigeration machine 21 , which includes an expansion valve 22 , a compressor 23 and a heat exchanger 24 , the refrigerant R717 or a comparable refrigerant can be utilised as refrigerant for example . By way of such a refrigeration machine 21 , ambient heat or waste heat can be absorbed at low temperatures , namely in the region of the heat exchanger 24 , wherein in the region of the evaporator 20 a higher temperature level is then present , in order to evaporate , via this increased temperature level in the region of the evaporator 20 , condensate or water upstream of the first or lowest compression stage 11- 1 .

Fig . 1 shows a further condensate line 25 , in which a pump 26 is integrated, wherein the condensate line 25 and the pump 26 are equipped to introduce condensate from the condensate reservoir 18 downstream of the compressor 12-n of the last or highest compression stage 11-n into the steam .

In the system 10 of Fig . 1 , the compression thus takes place in the region of a compression unit comprising the multiple compression stages 11 - 1 to 11 -n, in which between each compression stage condensate for cooling can be initially inj ected and evaporated, namely via the condensate lines 17 and via valves 27 integrated in the condensate lines 17 . Following the inj ection of the condensate via the respective condensate line 17 , the steam is present preferentially in the saturated state . The introduction of the condensate initially takes place in the region of the respective compression stage 11 via the respective condensate line 17 and subsequently or downstream thereof , the admixture of the steam via the respective steam line 16 . By introducing the condensate into the super-heated steam, the further evaporation is facilitated . Downstream, for the condensate introduction via the condensate line 17 and valve 27 , the steam admixture via the steam line 16 promotes the mixing-through in the gas flow, as a result of which the evaporation o f the introduced condensate in this line section is favoured . Through the combined introduction of the steam via the respective steam line 16 and of the condensate via the respective condensate line 17 , the compression of the steam in the compression stages 11 takes place along or approximately along a dew line 28 ( see Fig . 2 ) . Thus , a boiling line 27 is also drawn in next to the dew line 28 in Fig . 2 , which shows a logP-h diagram . As already mentioned, the evaporation in the compression stages 11 takes place along or approximately along the dew line 28 , which is shown in Fig . 2 for a multiplicity of compression stages .

In Fig . 1 , the inter-stage cooling takes place after each compression stage 11 . This takes place , as already mentioned above , in a combined manner by the inj ection o f condensate and by the introduction of steam . The inj ection of the condensate is visualised in Fig . 2 by the arrows 30 and the introduction of the steam by the arrows 31 .

By way of a regulation of the inter-stage cooling described above , in particular by way of a reduction or increase of the introduction of the condensate via the respective condensate line 17 , the steam is present in the superheated or slightly super-heated state at the outlet of the compressor 12-n of the last or highest compression stage 11-n . In particular when 100% saturated steam is required, an inj ection of condensate or water is possible downstream of the compressor 12-n of the last or highest compression stage 11 -n via the condensate line 25 and the pump 26 . The system 10 can thus generate steam at di f ferent temperature and pressure qualities in a saturated or super-heated state . The expansion takes place in the expansion stages 13 analogously to the compression in the compression stages 11 in multiple stages , wherein preferentially the number of the expansion stages 13 corresponds to the number of the compression stages 11 . However, it is also possible that the number of the expansion stages 13 is smaller than the number of the compression stages 11 , so that multiple compression stages 11 then combined with an expansion stage 13 . The expansion takes place in each case from the liquid state of the condensate via a regulated expansion valve 14 into the condensate reservoir 15 of the respective expansion stage 13 . The steam liberated during the expansion is separated in the respective condensate reservoir 15 and directly supplied to the respective compression stage 11 at the same suction pressure level . The remaining liquid portion, emanating from the condensate reservoir 15 , is supplied to the respective next expansion stage 13 . No additional inj ection pump is necessary for this purpose . As already explained, for introducing condensate via the respective condensate line 17 in the region of a compression stage 11 , the liquid phase of a pressure level above it of an expansion stage 13 above it is preferentially used . The expansion takes place in multiple stages along or approximately along the boiling line 29 ( see Fig . 2 ) . The separation of steam and liquid portions in the expansion stages increases the ef ficiency since a large part of the mass flow of the condensate does not have to be expanded down to the lowest pressure level . This substantially results in two advantages . Firstly, compression work is avoided and, secondly, the compressors 12 can be designed smaller at lower compression stages because of a smaller mass flow .

Preferentially, the outlet pressure of the highest or last compression stage 11-n is selected so that the associated condensation temperature corresponds to a usage temperature to be provided . In an open system 10 , the steam from the compressor 12 of the last or highest compression stage 11 can be directly supplied to steam customers or steam consumers . In a closed system 10 , the steam is condensed in the region of the condenser 19 and supplied to the condensate reservoir 18 . As likewise already explained, the heat supply takes place at the lowest pressure level downstream of the last or lowest expansion stage 13- 1 and upstream of the first or lowest compression stage 1- 1 via the evaporator 20 .

Fig . 3 shows for the system 10 of Fig . 1 a COP-T diagram, wherein on the hori zontal axis the steam temperature Ti2-n downstream of the compressor 12 -n of the last or highest compression stage 11-n is plotted, and on the vertical axis the coef ficient of power COP of the system 10 is plotted . The COP is plotted over the steam temperature Ti2 _n for di f ferent evaporation temperatures T20 in the region of the evaporator 20 . The higher the evaporation temperature T20 in the region of the evaporator 20 , the higher is the COP at a defined temperature Ti2 _n downstream of the compressor 12-n of the last compression stage 11-n .

Fig . 4 shows a second exemplary embodiment of a system 10 for steam generation and/or heat generation according to the invention, which with respect to its fundamental structure corresponds to the exemplary embodiment of Fig . 1 . For this reason, same reference numbers are used for same assemblies to avoid unnecessary repetitions and for these assemblies with the same reference numbers , reference is made to the above explanations . In the following, merely details by which the exemplary embodiment of Fig . 4 di f fers from the exemplary embodiment of Fig . 1 are discussed .

In the exemplary embodiment of Fig . 4 , a heat exchanger 32 is arranged downstream of the last or highest compression stage 12-n, which is equipped to extract heat from the steam present downstream of the last compression stage 11 - n . In the region of said heat exchanger 32 , heat of the super-heated steam is extracted downstream of the condenser 19 . In the case of a closed system shown in Fig . 4 , saturated steam can be super-heated through this heat extraction in the heat exchanger 32 , wherein the super- heated saturated steam can then be discharged from the system 10 according to the arrow 33. The heat extracted downstream of the last or highest compression stage 11-n and upstream of the condenser 19 in the region of the heat exchanger 32, can also be supplied to other forms of utilisation. In contrast with the condensation in the condenser 19, the heat is accrued with falling temperature.

In Fig. 4, an additional heat exchanger 34 is connected between the compressor 12- (n-2) of the compression stage ll- (n-2) and the compressor 12- (n-l) of the compression stage ll- (n-l) . Heat can be extracted from the steam also by way of this heat exchanger 34. This takes place in the heat exchanger 34 at an intermediate pressure level between the compression stages ll- (n-2) and ll- (n-l) . Such a heat exchanger 34 can be arranged in any position between two compression stages 11.

In the exemplary embodiment of Fig. 4, steam can be extracted between two compression stages 11, namely in the shown exemplary embodiment between the compression stages ll- (n-2) and ll- (n-l) via a steam line 35 and supplied to an additional condenser 36. By way of this it is possible to provide usage heat and steam at different temperature and pressure levels. This is possible both in an open process and also in a closed process.

A further difference of the exemplary embodiment of Fig. 4 compared with the exemplary embodiment of Fig. 1 consists in that in the exemplary embodiment of Fig. 4 a venting unit 37 is provided upstream of the first or highest expansion stage 13-n. The venting unit 37 is equipped to separate air from the condensate upstream of the first or highest expansion stage 13, namely in Fig. 4 both in the region of the condensate reservoir 18 and also in the region of the condenser 19. Such a venting unit 37 is preferentially positioned in the location of the system in which the condensate or water should be present in the completely liquified state. Here, a phase separation of air is then provided which can enter the condensate. As already explained, this takes place in the region of the condensate reservoir 18 and/or in the region of the condenser 19, namely in the region of an outlet of the condenser 19.

A further difference of the exemplary embodiment of Fig. 4 compared with the exemplary embodiment of Fig. 1 consists in that in Fig. 4 a heat exchanger 38 is assigned to a condensate reservoir 15 of an expansion stage 13, and namely in Fig. 4 to the condensate reservoir 15- (n-2) of the expansion stage 13- (n-2) , which heat exchanger 38 is equipped to introduce heat into the respective condensate reservoir 15, namely into the condensate present in the condensate reservoir 15, of the respective expansion stage 13. Because of this it is possible to introduce heat, in particular ambient heat and waste heat, at different temperature levels into the system 10. This introduction takes place preferentially in the liquid phase of the respective condensate reservoir 15 of the respective expansion stage 13. Because of this, the same is utilised as evaporator. By introducing heat into the respective liquid phase of the respective condensate reservoir 15, condensate evaporates which, via the respective steam line 16, can be directly supplied to the relevant compression stage 11 at the respective pressure level. Introducing heat at the highest possible temperature level is preferred in order to provide as high as possible an efficiency of the system. However, the heat can be introduced at different temperature stages and thus expansion stages 13.

In contrast with the shown exemplary embodiment it is also possible to introduce condensate or water into a condensate reservoir 15 of a respective expansion stage 13, for example of different steam consumers which provide water or condensate at different pressure levels. The condensate provided by a steam consumer, which has a defined pressure level , can then be introduced into a respective expansion stage 13 the pressure level of which corresponds to the pressure level of the condensate of the respective steam consumer .

In Fig . 4 as in Fig . 1 , the number of the compression stages 11 corresponds to the number of expansion stages 13 . In Fig . 4 as in Fig . 1 , the respective compression stage 11 is supplied via the respective steam line 16 with steam from the condensate reservoir 15 of the respective expansion stage 13 at the suction pressure level of the compressor 12 of the respective compression stage 11 . Upstream of this steam infeed, a condensate infeed via the respective condensate line 17 emanating from an expansion stage 13 or emanating from the condensate reservoir 18 takes place , wherein the condensate then has a higher pressure level than the suction pressure level of the respective compression stage 11 and is introduced or inj ected via a respective expansion valve 27 into the respective steam upstream of the steam infeed via the respective steam line 16 .

Fig . 4 visualises for the compression stage l l- (n- l ) via a condensate line 39 that the compression stage l l - (n- l ) can be supplied with the condensate via the respective condensate line 17 not only from the immediately higher expansion stage 13 , but also from a higher expansion stage 13 or even from the condensate reservoir 18 . Alternatively or additionally to the inj ections of condensate from the next higher expansion stage shown in Fig . 1 and 4 it is accordingly possible to draw the condensate utilised for inter-stage cooling from the condensate reservoir 18 at maximum pressure and conduct the same at that pressure level in the direction of the respective compression stage 11 . This coupling of the compression stages 11 with the expansion stages 13 is less ef ficient thermodynamically but has the advantage that a higher pressure is present for the atomisation of the condensate and thus for the inter-stage cooling .

In Fig . 4 the evaporator 20 , as in Fig . 1 , can also be part of a refrigeration machine 21 cascading to the compression stages 11 and expansion stages 13 .

LIST OF REFERENCE NUMBERS

System Compression stage Compressor

Expansion stage Expansion valve Condensate reservoir

Steam line

Condensate line Condensate reservoir Condenser

Evaporator Refrigeration machine Expansion valve Compressor

Heat exchanger Condensate line

Pump

Valve

Dew line

Boiling line Condensate introduction Steam introduction

Heat exchanger Saturated steam Heat exchanger Steam line Condenser Venting unit Heat exchanger

Condensate part line