WO2011104325A2

WO2011104325A2 - Apparatus and method for generating superheated steam using solar energy on the basis of the forced flow concept, and use of the superheated steam

Info

Publication number: WO2011104325A2
Application number: PCT/EP2011/052786
Authority: WO
Inventors: Waldemar Hoffmann; Guenther Beckesch; Arno Czimczik
Original assignee: Siemens Aktiengesellschaft
Priority date: 2010-02-26
Filing date: 2011-02-25
Publication date: 2011-09-01
Also published as: DE102010009485A1; WO2011104325A3

Abstract

The invention relates to an apparatus and a method for generating superheated steam using solar energy and a steam generator based on the forced flow concept. Superheated steam, which is used to drive a steam turbine, for example, is generated in multiple stages within a water pipe, i.e. by preheating, evaporating, and superheating feed water. The thermal energy required for said process is supplied by a heat transfer medium heated using solar energy. In order to be able to more efficiently generate superheated steam, tube bundles are used, inter alia. Furthermore, a plurality of steam generators are connected in parallel for use in larger steam generator units.

Description

description

Apparatus and method for generating superheated steam by means of solar energy based on the forced-through concept and use of the superheated steam

The invention relates to a device for generating superheated steam by means of solar energy and a procedural ren for generating superheated steam using the device. In addition, a use of the superheated steam is indicated.

The use of solar thermal power plants as an alternative to conventional power generation is a way to defuse the existing carbon dioxide problem. In this way lar energy (solar energy), ^¬ ie electromagnetic Strah development of the sun into electrical energy.

Currently, a majority of the solar thermal power plants al solar thermal power plants with indirect evaporation out ^¬ leads. Solar fields with parabolic trough collectors serve as receivers of the solar energy. As an alternative to the parabolic trough collectors, Fresnel collectors are used as receivers of solar energy. Instead of the solar fields, solar towers are also used.

A solar thermal power plant with indirect evaporation has a steam generator. The steam generator includes a heat transfer circuit (primary circuit) with a heat carrier medium and a water / steam circuit (secondary circuit) with water. The heat transfer medium of the heat ^¬ carrier circuit, such as a thermal oil or a salt melt, absorbs the solar energy in the form of heat (thermal energy). The heat transfer medium is he ^¬ warms. The heat absorbed by the heat transfer medium heat is transferred by means of feed water preheater, evaporator and Üb heater to the water of the water / steam cycle. In this case, superheated steam is generated. The stored in superheated steam thermal energy is used to obtain the electrical energy. It comes to the conversion of thermal energy into electrical energy.

The conversion of the thermal energy of the superheated steam into electrical energy takes place in the "conventional" part of a solar thermal power plant, for example with the aid of a steam turbine.

Object of the present invention is to show how efficiently superheated steam can be obtained with the help of solar energy, which can be used for the production of electrical energy.

To solve the problem, a device for generating superheated steam by solar energy is specified, comprising at least one heat transfer circuit with a heat transfer medium for receiving the solar energy in the form of heat and at least one water / steam cycle with water, wherein the heat transfer circuit and the What ^¬ water / steam cycle are thermally coupled to each other via at least one steam generator, by the steam generator a forced flow concept is realized with feed water preheater, evaporator and superheater, at least one water ^¬ pipe for receiving the water is present, the water pipe and the heat transfer circuit in the region of the feedwater preheater for heating befindlichem in the water pipe, liquid water by means of heat of the heat transfer medium are thermally coupled to each other, the water pipe and the Wärmeträ ^¬ ger circuit in the evaporator Transferring in the water located, heated liquid water in water vapor by means of heat of the heat transfer medium are thermally coupled together and the water pipe and the heat ^¬ carrier circuit in the superheater to overheat the water vapor located in the water pipe by means of heat of the heat transfer medium are thermally coupled together. To achieve the object, a method for generating superheated steam using the device with the following steps is given: a) providing the heat transfer medium, b) converting solar energy into heat of the heat transfer medium and c) transferring the heat of Heat transfer medium to the water of the water / steam cycle, wherein the superheated steam is generated.

According to a further aspect of the invention, a use of the superheated steam generated by the described method for obtaining electrical energy is specified, wherein a steam turbine is driven by means of the superheated steam. The idea underlying the invention is to use solar energy for the formation of superheated steam, so the electromagnetic radiation that is sent from the sun ^¬ and hits the earth's surface. For this purpose, a suitable steam generator system is provided. Of the

Steam generators or the steam generator system are based on the concept of forced circulation. Within the water pipe (pipe in which the water of the water / steam cycle is ^¬ finds), the transfer of liquid water takes place in superheated steam. For this purpose, the heat transfer medium and the water are thermally coupled with each other. It comes to the exchange of heat between the heat transfer medium and the water. This is preferably accomplished by the heat transfer medium flowing past the water pipe or being conducted past it. Heat is exchanged by heat conduction indirectly via the water pipe.

The difference with natural circulation concepts lies with the once-through concept in water flow: The water of what ^¬ ser / steam circuit is always on the pipe side, so in the tube inside the water ear. Because preheating,

Evaporation and overheating take place in the same water pipe, in contrast to the natural circulation concepts one

Steam drum not necessary. The generation of the superheated steam is mehrstu ^¬ fig, namely on the feedwater preheating, the evaporation (formation of water vapor) and the overheating of the water vapor.

In order to simplify a start-up of the system, it is advantageous to provide at least one device for separating liquid water from the steam. This device includes fully, for example, a at the output of the superheater is mounted ^¬ separation vessel. Until the desired steam parameters are reached, the water vapor is passed on to a condenser of the separation vessel. The separated water is fed back into the water / steam cycle in ^¬ example with the aid of a pump.

In addition, the steam generator can have an intermediate superheater (intermediate overheating stage). With the intermediate superheater ^¬ an efficiency is increased, with a down- stream steam turbine is operated. With the intermediate overheating stage, additional thermal energy is introduced into the water vapor. The introduction of the thermal energy can be done arbitrarily, for example by means of fossil fuels. Preferably, however, the intermediate overheating stage is operated solar-thermally: The

Intermediate superheater has an intermediate superheater water pipe for receiving the water vapor. For intermediate superheating hot, heated by means of solar energy Wärmeträ ^¬ ger medium is passed by the intermediate superheater water pipe. Intermediate superheater water pipe and heat transfer medium are thermally coupled together. By passing the heat transfer medium, the water vapor in the intermediate superheater water pipe is additionally overheated. For the feed water preheating, the evaporation and the

Overheating can be provided in each case a separate heat transfer circuit. Preferably, however, for feedwater preheating, evaporation and overheating, there is a single, common heat transfer circuit available. In this case, the heat transfer circuit is designed such that the heat transfer medium can successively flow past the water pipe in the region of the superheater, in the region of the evaporator and in the region of the feedwater preheater. Water pipe and heat transfer medium are brought into contact with each other.

The feedwater preheater, the evaporator and the superheater can be arranged arbitrarily to each other, for example horizontally. In order to effect the flow of heat medium through the water pipe, for example, a heat transfer pump or a plurality of heat transfer pumps is used. The heat transfer medium is pumped past the water pipe.

According to a particular embodiment, the feedwater preheater, the evaporator and the superheater are arranged vertically one above the other, for example, stacked one above the other. By a vertical structure, the Vorbeiströmen the heat transfer medium to the water pipe can be caused solely by the force acting on the heat transfer medium gravity. In addition, at least one heat carrier pump can be ^¬ is to influence the flow past the heat transfer medium (flow direction and / or flow velocity) to the water pipe. In the vertical structure, the superheater at the top, the evaporator at the center and the feedwater preheater at the bottom are preferably arranged at the top. The heat transfer medium flows from top to bottom first in the area of the superheater, then in the region of the evaporator and finally ^¬ in the area of the feedwater preheater on the water pipe over. With the aid of hot heat transfer medium, the overheating takes place, with the aid of a slightly cooled heat transfer medium evaporation and with the help of "cold" heat transfer medium, the feedwater preheating takes place, which is required for the respective stage via the heat transfer medium Amount of heat provided in a simple manner.

The vertical structure of the steam generator is not only in Hin ^¬ look at the flow of the heat transfer medium from "top to bottom below. "In addition, the vertical structure exploits a natural movement of the water vapor from" bottom to top ".

For thermal coupling of the water pipe and the Wärmeträ ^¬ ger medium, the feedwater preheater, the evaporator and the superheater each have their own pressure vessel (preheating pressure vessel, evaporator pressure vessel and superheater pressure vessel) have. In these pressure vessels, the water pipe is arranged. The water pipe is guided by the Druckbe ^¬ container. In the case of a single, common heat transfer circuit, the pressure vessels are preferably connected to one another such that the heat transfer medium can flow successively through the preheating pressure vessel, through the evaporator pressure vessel and through the superheater pressure vessel.

According to a particular embodiment, the water pipe is mitein ^¬ other arranged for thermal coupling of the water pipe and the heat transfer medium in a single pressure vessel through which the heat transfer medium can flow with at least one particular flow direction. The common pressure vessel has at least one heat transfer medium inlet and at least one heat transfer medium outlet. About the heat transfer medium inlet hot heat transfer medium is introduced into the pressure vessel and cooled through the heat-transfer-medium outlet heat transfer medium abge ^¬ leads. The heat-transfer-medium inlet located ^¬ preference, in the range of the superheater, and the heat-transfer-Medium- outlet in the region of the feed water preheater.

Within the common pressure vessel which Wärmeträ ^¬ ger medium may cage, one with a direction of flow, or more rapidly with a plurality of flow to be performed by the push containers from each other different directions. Generous means that the heat transfer medium several times in each case in the region of the superheater, in the region of the evaporator and / or in the region of the feedwater preheater on the water pipe flows past. For example, the heat transfer medium is first passed in a first train in the region of the superheater, then in the region of the evaporator and finally in the region of the feedwater preheater on the water pipe. In a second train, the heat transfer medium flows in the opposite flow direction. The heat transfer medium is conducted past the water pipe starting in the area of the feedwater preheater, then in the area of the evaporator and finally in the area of the superheater. In the third move, the flow direction changes again. The heat transfer medium is again passed in accordance with the first train successively in the region of the superheater, then in the region of the evaporator and finally in the region of the feedwater preheater on the water pipe. One-way and Mehrzügigkeit the flow of the heat transfer medium can incidentally affect not only the common pressure vessel. Also in the preheating-pressure vessel, in the evaporator pressure vessel and / or in the superheater pressure vessel, the heat transfer medium can be passed one or mehrzügig the water pipe.

Basically, the water pipe with respect to the flow direction of the heat transfer medium can be arranged arbitrarily. But it is particularly advantageous if a longitudinal extension of the water pipe is arranged transversely to the flow direction of the heat transfer medium. In this form an efficient energy transfer takes place. The "cross-countercurrent circuit" can be realized in the area of the preheater, in the area of the evaporator and / or in the area of the superheater.

To further increase the efficiency with which the heat of the heat transfer medium can be transferred to the water of the water pipe, the water pipe is meandering. This means that at least one meander (arc) of the water pipe is EXISTING ^¬. The water pipe is bent. In a mäanderförmi- gen water pipe compared to a straight water pipe, a flow speed is reduced, with the heat ^¬ carrier medium bypasses the water pipe. In addition, comes it swirls as it flows past. Both lead to an increase in the efficiency of the heat exchange.

It is particularly efficient if there are a large number of parallel arranged water pipes. There is a water pipe bundle. For a given pipe volume is a (total) pipe surface over which takes place the thermal coupling of the Wär ^¬ meträger medium and water, at a ^¬ What serrohr bundle as compared to a single water pipe HOE forth.

In a water tube bundle, the water is, for example, ver ^¬ divides via a distributor to the water tubes of the evaporator. In each of the water pipes, the production of superheated steam takes place separately. About a collector, the recovered in the individual water pipes, superheated steam is brought together again. The merged, overheated over ^¬ water vapor is then passed to a steam turbine. It is particularly advantageous to provide a plurality of mutually parallel, meandering water pipes.

To further increase the efficiency with which the heat of the heat transfer medium can be transferred to the water of the water pipe, it is advantageous to influence the flow direction (and the flow velocity) of the heat transfer medium to be ^¬ . The heat transfer medium can be routed channeled on the water pipe or on the water pipes over. For this purpose, according to a particular embodiment, a plurality of Umleitblechen for changing the flow direction of the heat transfer medium is present. For example, the redirection ^¬ plates are arranged at regular intervals between meandering water tubes of a tube bundle. A further embodiment of the device relates, for example, to the provision of an additional heat carrier connection in the region of the evaporator. This connection is located at the outlet of the evaporator. The result is fene additional hot heat transfer media stream provides for faster settings of a design-related evaporation end point in the water pipes. When the desired superheated steam parameters are reached, this additional connection can be disabled. An additional amount of heat then connected to the additional heat transfer medium can be used, for example, for an intermediate overheating. According to a particular embodiment, a plurality of steam generators are present. Preferably, the plurality of steam generators are connected in parallel to a larger steam generator unit. With reference to several embodiments and the associated figures, the invention will be described in more detail below. The figures are schematic and are not true ^¬ dimensioning true to scale drawings. Figure 1 shows a circuit diagram of a solar parabolic trough nenkraftwerks.

Figure 2 shows a vertically placed steam generator without separation vessels in a side view.

FIG. 3 shows a vertical steam generator with a separating vessel in a lateral cross-section.

FIGS. 4A and 4B show the functional principle of the evaporator.

Figures 5 and 6 show further possibilities of Heizflächenaufteilung according to the embodiments of Figures 4A and 4B.

Given is a device 1 for generating water vapor by means of solar energy. The device has a Wärmeträ ^¬ ger circuit 2 and a water / steam circuit 3. The circuits are thermally coupled to each other via at least one steam generator 4. An exchange of heat can take place via the steam generator, so that the water is transferred from the liquid phase into the gaseous phase as water vapor (FIG. 1).

With the steam generator, a forced flow concept 44 with feedwater preheater 41, evaporator 42 and superheater 43 is realized. At least one water pipe 30 for receiving water is present.

To transfer heat that is transmitted via the solar panel 11 to the heat transfer medium 20 of the heat transfer circuit, the water pipe and the heat transfer circuit in the region 40 of the feedwater preheater for heating befindlichem in the water pipe, liquid water by means of heat Heat transfer medium thermally coupled together.

Likewise, the water pipe and the heat transfer circuit in the region 41 of the evaporator for transferring the heated liquid water in the water pipe in water vapor by means of heat of the heat transfer medium are thermally coupled GE ^¬ ge together. In addition, the water pipe and the Wärmeträ ^¬ ger cycle in the region 41 of the superheater for overheating the water vapor located in the water pipe by means of heat of the heat transfer medium are thermally coupled together.

Example 1 :

Feedwater preheaters, evaporators and superheaters are stacked vertically one above the other in a common pressure vessel 43 (FIG. 2). The pressure vessel has a heat transfer medium inlet 430 and a heat transfer medium outlet 431. By the heat transfer medium inlet hot heat transfer medium through the heat transfer medium outlet is spent heat transfer medium, ie cooled heat transfer medium removed again. The heat carrier Medium is a thermal oil. In an alternative embodiment, the heat transfer medium is a salt melt.

Within the pressure vessel, the heat transfer medium flows with a vertical flow direction from top to bottom of the heat transfer medium inlet in the direction of heat transfer medium outlet.

In order to ensure the most efficient heat transfer, deflecting plates 38 for changing the flow direction of the heat transfer medium are present in the pressure vessel. This ensures that an efficient heat exchange between the heat transfer medium and the water present in the pipes can take place.

According to the present embodiment is not Trennge ^¬ fäß for the separation of liquid and gaseous phase of the water present. Example 2:

In contrast to the preceding example, a separation vessel 37 for separating the liquid and gaseous phase of the water is present (Figure 3). The separation vessel has a condenser 33 for the separation of liquid and gaseous water. The separated water is returned to the water / steam cycle. This is done by ^gravity or, as shown in FIG.

FIGS. 4A and 4B show the functional principle of the steam generator with forced continuous flow concept. The figures show the steam generator in each case in a lateral cross-section. In the pressure vessel, a plurality of meandering water pipes is present. The water pipes are arranged parallel to one another and combined to form tube bundles 32. The water pipes are supplied via the distributor 34. What ^¬ ser. The formed in the water pipes, overheated Steam is again together ^¬ quantitative results with the aid of the accumulator 35 and passed on to the steam turbine 12th

The water pipes are angeord ^¬ net in such a pressure vessel, that a longitudinal extent 39 of the water pipes is aligned transversely to the flow direction of the heat transfer medium (Figure 4A). The heat transfer medium 20 flows with the flow direction 21 through the pressure vessel and past the water pipes arranged transversely thereto with their longitudinal extent. This ensures efficient heat exchange.

According to the present example, the heat transfer medium is passed through the pressure vessel einschubig. According to further embodiments, the heat transfer medium is more rapidly conducted through the pressure vessel (two rapidly according to Figure 5 and three ^¬ quickly according to Figure 6).

In embodiments not shown, the feedwater preheater, the evaporator and the superheater are each arranged in a separate pressure vessel. In this case, the water pipes are aligned transversely to the flow direction of the heat transfer medium in each of the pressure vessel (cross-countercurrent circuit)

Furthermore, in addition to the steam generator, an intermediate overheating stage (intermediate superheater) 13 is provided to increase the efficiency of the downstream steam turbine. The intermediate stage is also operated solar-thermally. The intermediate superheater has an intermediate superheater water pipe for receiving the water vapor. For intermediate superheating hot, heated by means of solar energy Wärmeträ ^¬ ger medium is passed past the intermediate superheater water pipe. Intermediate superheater water pipe and heat transfer medium are thermally coupled together.

The device described is used to generate superheated steam by means of solar energy. It will be the following process steps are carried out: a) providing the heat transfer medium, b) converting solar energy into heat of the heat transfer medium and c) transferring the heat from the heat transfer medium to the water, the superheated What steam is generated.

The generated, superheated steam is forwarded to a steam turbine for the production of electricity.

Claims

claims

1. Device (1) for generating superheated steam by means of solar energy, comprising

- At least one heat transfer circuit (2) with a heat carrier medium ^¬ (20) for receiving the solar energy in the form of heat and

- At least one water / steam cycle (3) with What ^¬ ser, wherein

- The heat transfer circuit (2) and the water / steam circuit (3) via at least one steam generator (4) are thermally coupled together,

a forced-circulation concept (44) with feed-water preheater (40), evaporator (41) and overheater (42) is realized by the steam generator (4),

- There is at least one water pipe (30) for receiving the water,

- The water pipe (30) and the heat transfer circuit (2) in the region (40) of the feedwater preheater for heating in the water pipe (30) befindlichem, liquid water by means of heat of the heat transfer medium (20) are thermally coupled together,

- The water pipe (30) and the heat transfer circuit (2) in the region (42) of the evaporator for transferring the water pipe (30) located, heated liquid water in water vapor by means of heat of the heat transfer medium (20) thermally mitein ^¬ other coupled are and

- The water pipe (30) and the heat transfer circuit (2) in the region (42) of the superheater for superheating of the water pipe (30) located in the water vapor by means of heat of Wärmeträ ^¬ ger medium (20) are thermally coupled together.

2. Device according to claim 1, wherein at least one device (37) for the separation of liquid water from the water vapor is present.

3. Apparatus according to claim 1 or 2, wherein a single heat transfer circuit is provided, which is configured such that the heat transfer medium can successively flow past the water pipe in the area of the overheater, in the region of the evaporator and in the region of the feedwater preheater.

4. Device according to one of claims 1 to 3, wherein the feedwater preheater, the evaporator and the superheater are arranged vertically one above the other.

5. Device according to one of claims 1 to 4, wherein for thermal coupling of the water pipe and the heat transfer medium together, the water pipe is arranged in a single Druckbe container through which the heat transfer medium with at least a certain flow direction (21) flow can.

6. Device according to one of claims 1 to 5, wherein a Längsaudehnung (39) of the water pipe is arranged transversely to the flow direction of the heat transfer medium.

7. Device according to one of claims 1 to 6, wherein the water pipe is meandering.

8. Device according to one of claims 1 to 7, wherein a plurality (32) of mutually parallel Wasserroh ren is present.

9. Device according to one of claims 1 to 8, wherein a plurality of Umleitblechen (38) for changing the flow direction of the heat transfer medium is present.

10. Device according to one of claims 1 to 9, wherein a plurality of steam generators is present.

11. A method for generating superheated steam using a device according to one of claims 1 to 10, comprising the following method steps:

a) providing the heat transfer medium, b) converting solar energy into heat of the heat transfer medium and

c) transferring the heat of the heat transfer medium to the What ^¬ water of the water / steam cycle, wherein the superheated steam is generated.

12. Use of the superheated in accordance with the method of claim 11 water vapor for the production of electrical energy, wherein with the aid of the superheated steam, a steam turbine (12) is driven.