RS20060127A - Steam power plant - Google Patents

Abstract

The thermal power plant (1) according to the invention consists of at least one steam turbine (3) and one steam generator (5), one combustion chamber (7) being arranged in the direction (9) of water flow (17) after the first stage (11) steam turbines and before the second stage (13) of the steam turbine (3) and that the flow (17) of water vapor in the combustion chamber (19) is heated by mixing with hot flue gas produced in the combustion chamber (19).

Description

THERMOPOWER PLANT.

SIEMENS AKTIENGESELLSCHAFT [DE&DE]

The invention relates to a thermal power plant with at least one steam turbine and one generator

steam heated by combustion.

In well-known thermal power plants, the driving steam for steam turbines is produced most often in a steam generator

heated by combustion, whereby the energy of hot flue gases is released in one or more

of heat exchangers, in which there is water, so that the heating of this water is achieved

water vapor, or in which there is already water vapor, so that with the help of the mentioned heat exchanger

performs superheating of steam; this type of overheating of water vapor occurs in well-known steam turbines, for example

between the high-pressure stage or the medium-pressure stage of the steam turbine, where water vapor is created

which leaves the stage of high-pressure superheating by means of the surfaces of the intermediate superheater smcStenog u

to the steam generator and leads to the middle pressure stage of the steam turbine.

Such intermediate captures of steam lead, for example, to a high level of utilization.

At well-known thermal power plants, heat energy is supplied for production and/or

intermediate superheating of water vapor using heat exchanger surfaces, which are installed in the generator

steam heated by combustion, for example by burning coal. fuel oil or biomass or in general

of the heated steam generator with fossil or nuclear fuels and which are brought into contact with the supplied

hot flue gases. The very heated surfaces of the heat exchanger give off their heat

energy again leads and/or water vapor, which is then spent inside a body formed by

heat exchanger surface. It means that overheating is achieved by means of heat transfer from the hot ones

flue gases to the surfaces of the heat exchanger and from the surfaces of the heat exchanger to the medium that needs it

to warm up.

In the case of known heat exchangers according to the existing state of the art, which are used in steam generators of known thermal power plants, which transfer the energy of hot flue gases to the medium to be heated using the material of the surface of the heat exchanger heated by hot flue gases, the amount of energy that can be transferred to the medium being heated, for example, water and/or steam, is limited by the characteristics of the material of the surface of the heat exchanger.

For this reason, the permitted steam temperatures are limited in known thermal power plants, because the surfaces of the heat exchanger, to which the amount of energy is transferred, due to the characteristics of the material and the limit of the thermal load, which is related to this, cannot be heated yet if desired.

Furthermore, the transfer of heat from the hot flue gases to the medium to be heated is burdened with a certain delay, which is caused essentially by the required speed of heating the surfaces of the heat exchanger.

The task of the invention is to realize a thermal power plant with at least one steam turbine and one steam generator, which can be applied flexibly and which will especially overcome the known defects from the existing state of the art.

This task according to the invention is solved by a power plant, which consists of at least one steam turbine and one steam generator heated by combustion, where one combustion chamber is placed in the direction of the steam flow after the first stage of the turbine of one steam turbine and before the second stage of the turbine, and that the flow of steam in the combustion chamber is heated by mixing with the hot gas generated in the combustion chamber.

The invention is based on the fact that the heat transfer from the hot flue gas to the heating medium is less limited in comparison with the existing state of the art, if the heat transfer to the heating medium is deprived of the use of heat exchanger surfaces.

This is achieved in the invention by introducing the water vapor to be heated directly into the combustion chamber and mixing it directly with the hot flue gas there.

This internal additional combustion according to the invention can be applied after the steam generator and before the steam turbine, in the direction of the steam flow, i.e. already for superheating fresh steam or for superheating steam, which has already given off a part of its energy in one stage of the turbine and which, after being superheated according to the invention, is fed to another stage of the turbine.

With the help of the power plant according to the invention, higher steam temperatures can be achieved compared to the same according to the existing state of the art, which can then contribute to increasing the degree of usefulness of the thermal power plant.

If the thermal power plant with an additional combustion chamber provides additional combustion according to the invention, if the combustion chamber is turned off or fails, then the thermal power plant can continue to work like all known thermal power plants.

It is advantageous to feed hydrogen and/or hydrocarbon, especially methane, as fuel into the combustion chamber.

Special fuel contains carbon and/or hydrogen.

By using hydrogen as a fuel, the first advantage is that - as hydrogen is produced as usual by reforming or gasifying one hydrocarbon - aggressive carbon dioxide is already retained during the production of hydrogen by reforming or gasifying one hydrocarbon with little need for energy, and that the formation of an acidic steam mixture inside the steam turbine and/or other components of the thermal power plant is prevented in advance.

In order to achieve a particularly good combustion inside the combustion chamber, it is suitable to introduce gas containing oxygen, especially pure oxygen and/or air, into the combustion device to create an atmosphere suitable for combustion.

This way of carrying out the invention requires taking into account that the combustion of one fuel is possible only in one favorable atmosphere for combustion. A particularly efficient combustion is possible using pure oxygen, because oxygen, compared to air, does not contain other ingredients unsuitable for combustion, i.e. which would have to be separated before combustion, for example in an air decomposition device, in order to create an atmosphere suitable for combustion.

In another convenient way of carrying out the invention, aggressive combustion products are separated from the steam flow by means of a condenser, which is behind the steam turbine.

In practically all combustion processes, combustion products are produced, which are usually removed, because, especially in the case of a long stay in the combustion chamber or on other components, they can be isolated and their function limited.

If in the thermal power plant according to the invention, for example, one hydrocarbon is burned as a fuel in an atmosphere consisting of pure oxygen, then at least the combustion products of water and carbon dioxide are produced. These combustion products are mixed with water vapor and introduced into the condenser. With known solutions for thermal power plants, there is already one capacitor, so in connection with the solution according to the invention, it is not necessary to provide a suitable, separate capacitor for the removal of combustion products.

When cooling the water vapor, which the combustion products contain as a mixture of water and carbon dioxide, part of the water vapor is abundantly condensed and almost pure, gaseous carbon dioxide remains as an excess, which is removed from the condenser and, for example, stored.

As already mentioned, when using hydrogen as a fuel, which is produced by reforming or gasifying a hydrocarbon, aggressive carbon dioxide can already be removed before introducing the fuel into the combustion chamber, so that in this case practically no carbon dioxide is produced as a combustion product.

The realized internal additional combustion by means of the combustion chamber of the thermal power plant according to the invention can be made available very easily during operation. Therefore, only light ignition of the fuel introduced into the combustion chamber is required; especially the heating times of the known surfaces of the heat exchanger.

Furthermore, the power plant according to the invention offers the convenience that the combustion products and/or flue gases must be removed from the combustion chamber by means of a special device for their removal, because they are carried by the flow of steam and can be turned off at another place in the circular cycle of water vapor, for example, the mentioned condenser. In addition, the invention achieves a higher water vapor temperature, without the need to change the steam generator.

The thermal power plant according to the invention can be switched on specifically to supply energy at peak loads or to support the grid frequency of an electrical power grid; the thermal power plant according to the invention offers the possibility of quick regulation of power and is very flexibly switched on.

Furthermore, an example of the implementation according to the invention will be described in more detail with a picture, in which:

Figure 1 shows a thermal power plant according to the invention.

Figure 1 shows the thermal power plant 1 according to the invention, which consists of a steam turbine 3 connected to a generator 21, as well as a steam generator S heated by combustion.

Steam turbine 3 is built as a three-stage and has one first stage 11 turbine, one second stage 13 turbine and one third stage 15 turbine, which are designed as a high pressure stage, a medium pressure stage, respectively. low pressure level.

In the case of the steam generator S, in the embodiment shown in the figure, it is a coal-fired boiler 27 to which combustion air 29 is supplied to achieve coal combustion.

In the steam generator 5, a heating surface 37 is placed in the area of its warm end, as well as in the area of lower temperatures, the surface of the intermediate superheater 35.

The heating surface 37 serves to heat the water vapor from the feed water 24 from the reservoir 23 in the generator 5 so that the steam can be fed to the first stage 11 of the turbine.

After partial unloading in the first stage 11 of the steam turbine, the water vapor is superheated by means of the heating surfaces 35 of the superheater. Water vapor flow 17 exits the intermediate superheater 35 in the direction 9 and leads to a combustion device. At the same time, the water vapor 17 is additionally heated in a combustion chamber 19 by means of a fuel 33 and by supplying oxygen 31, whereby the water vapor 17 in the combustion chamber 19 is mixed with hot flue gases, which are produced in the combustion chamber 19 during the combustion of the fuel 33.

The transfer of heat from the hot flue gases to the flow 17 of water vapor is achieved directly by mixing, without the provision of heat transfer materials, for example, the heating surfaces of the heat exchanger.

Instead of oxygen 31, it is possible to use air to create a suitable atmosphere for combustion, whereby air, or before entering the combustion chamber, it is decomposed by means of a device for the decomposition of air into oxygen and remaining gas.

For example, any hydrocarbon can be used as fuel33, especially methane or hydrogen.

The flow 17 of water vapor, heated by the combustion chamber 19, is fed to the second stage 13 of the steam turbine, where then at least one part of the energy contained in it is converted into mechanical work. In this way, the relieved water vapor leaves the second stage 13 of the steam turbine and leads to the third stage 15 of the steam turbine, where the still existing part of the water vapor condenses into water.

This water, which collects in the condenser 25, is supplied as condensate 26 to the feed water tank 23.

Combustion products 39 can be removed from the condenser 25, which are formed during combustion in the combustion chamber 19.

As the combustion process in the combustion chamber 19 takes place within the flow of water vapor 17, the combustion products 39 are carried along with the water vapor 17 in a circular cycle of water vapor and after this method of discharge according to the invention they are discharged from the condenser 25.

If, for example, fuel 33 is burned with oxygen 31, then the combustion products 39 contain water and carbon dioxide. This mixture of water and carbon dioxide is carried along with the flow of water vapor and can be withdrawn from the condenser 25, because when cooling the mixture of water and carbon dioxide, the water part condenses almost completely, so that what remains is almost completely pure carbon dioxide as a gas, which is then removed and, for example, can be stored.

Claims (4)

1. Thermal power plant (1), consisting of at least one steam turbine (3) and one steam generator (5), indicated by that one combustion chamber (7) is placed in the direction (9) of the flow (17) of water vapor after the first stage (11) of the steam turbine and before the second stage (13) of the steam turbine (3) and that the flow (17) of water vapor in the combustion chamber (19) is heated by mixing with the hot flue gas produced in the combustion chamber (19). 2. Thermal power plant (1), according to Request 1, indicated by which are arranged (7) for combustion brings hydrogen and/or hydrocarbon, especially methane, as fuel. 3. Thermal power plant (1), according to one of Claims 1 or 2, indicated by which are arranged (7) for combustion to create an atmosphere favorable for combustion in the chamber (19) brings gas containing oxygen. and especially Pure Oxygen (13) and/or air. 4. Thermal power plant (1), according to one of Claims I to 3, indicated by that the aggressive products (39) of combustion are removed by means of the condenser (25) of the water vapor flow (9) connected after the steam turbine (3).