The invention relates to a procedure for preheating untreated water, in particular in a power plant. The invention further relates to a power plant having a water/steam circuit.
In the case of power plants that have steam extraction without, or with partial, return of the condensate, frequently there is a requirement for large quantities of deionate, i.e. demineralized (also: deionized) water, in order to compensate the circuit losses resulting from the steam extraction. At low outside temperatures, in particular, the untreated water does not have the temperature necessary for production of deionized water. Hitherto in this case, the untreated water was preheated by means of steam or electrically, resulting in a high requirement in respect of machinery or electrical equipment resources, in reduction of the efficiency or in an increased house load.
An object is to further develop the said procedure and the said apparatus such that a considerable reduction of the resource requirement is achieved.
These objects are achieved according to the invention by the procedure for preheating untreated water as claimed, and the power plant as claimed. Advantageous developments of the invention are defined in the respective dependent claims. In that, in the case of a procedure for preheating untreated water in a power plant having a water/steam circuit, the power plant comprising a steam generator, a steam turbine and steam lines, of which at least some connect the steam generator to the steam turbine, untreated water for production of deionized water is heated by waste water from the water/steam circuit, wherein the waste water is admixed with the untreated water for the purpose of heating the untreated water, it is achieved that residual heat in the waste water is utilized and the house load of the power plant is reduced, or the efficiency is increased.
Waste water in this case is the water that leaves the water/steam circuit and that is usually discharged into the cooling water or discarded following appropriate recooling. Vessels for waste water, and associated pumps, and the pipeline to the cooling water are already present. It is necessary to add only a line branch to an untreated-water mixer having fittings.
If the waste water is admixed with the untreated water for the purpose of heating the untreated water, no heat losses occur, as in the case of heating by means of low-pressure steam. Also, with appropriate selection of the waste water, the latter can be used again as untreated water.
It is expedient in this case if the waste water is a blowdown water from the steam generator, in particular from steam drums.
Alternatively or additionally, it may be advantageous if the waste water is a condensate from the steam lines that are automatically drained at low points.
In respect of good intermixing of waste water and untreated water, it is advantageous if the waste water is distributed in the untreated water.
Further, it is advantageous if an untreated water temperature is controlled, by closed-loop control, by alteration of a blowdown water quantity.
In particular, it may be advantageous if, on the basis of a heat demand for the preheating, more water is blown down than is required on the basis of a water chemistry requirement. Only in this case, however, there is also only a comparatively small reduction in efficiency, since in this case additional heat is extracted from the steam generator. The electrical house load is not increased. In any case, closed-loop control of the untreated water temperature can be effected by variation of the boiler blowdown. It is thus also possible to set an optimal temperature for the production of deionized water.
In the case of the power plant according to the invention having a water/steam circuit, the power plant comprising a steam generator, a steam turbine and steam lines, which at least in part connect the steam generator to the steam turbine, an untreated-water mixer and a vessel for waste water from the water/steam circuit, the untreated-water mixer and the vessel for waste water from the water/steam circuit are fluidically connected to each other, wherein an apparatus for distributing the waste water in the untreated water is provided in the untreated-water mixer. A distribution of the waste water in the untreated water improves the intermixing.
It is expedient in this case if the vessel for waste water from the water/steam circuit is connected to the steam generator. In particular, blowdown water is produced regularly at the steam drums of the steam generator.
Further, it is expedient if the vessel for waste water from the water/steam circuit is connected to steam lines. The latter are drained automatically at their low points, and the condensate produced is usually not contaminated.
In a further advantageous embodiment of the power plant according to the invention, a closed-loop controller for closed-loop control of the untreated water temperature is provided. The optimal temperature for the production of deionized water can thus be set.
It is expedient in this case if the closed-loop control for the untreated water temperature comprises an open-loop control of a blowdown water quantity.
Unlike condensate from the steam lines, the blowdown water quantity is easily set.
The invention is explained exemplarily in greater detail on the basis of the drawings. There are shown schematically, and not true to scale:
The steam turbine installation 12 comprises a steam turbine 4 having a coupled generator 19, and, in a water/steam circuit 2, a condenser 20 downstream from the steam turbine 4, and a waste-heat steam generator 3. In
The waste-heat steam generator 3 is also represented in a highly simplified form. For the purpose of supplying working fluid, expanded in the gas turbine 13, into the waste-heat steam generator 3, there is a waste-gas line 22 connected to an input 23 of the waste-heat steam generator 3. The expanded working fluid from the gas turbine 13 leaves the waste-heat steam generator 3, via the output 24 thereof, in the direction of a flue, not represented in greater detail.
A feed-water vessel/deaerator 25 can be fed with condensate from the condenser 20, via a condensate line 26, connected into which there is a condensate pump unit 27. The arrangement of the feed-water vessel/deaerator 25 in the water/steam circuit 2 of
Shown exemplarily on the steam turbine 4 is a steam extraction 34 for a steam supply system. In principle, steam extractions may be provided at various points on the steam turbine, but also in the region of the waste-heat steam generator 3. Exemplarily, a condensate return 35 goes into the condensate line 26.
The power plant 1 additionally comprises an untreated-water mixer 6, and a vessel 7 for waste water from the water/steam circuit 2, which, according to the invention, are fluidically connected to each other. An apparatus 8 for distributing the waste water in the untreated water is provided in the untreated-water mixer 6.
The vessel 7 for waste water from the water/steam circuit 2 is connected both to the steam generator 3 and there, in particular, to the steam drum 30, and to the steam lines 5.
Provided for the purpose of closed-loop control of the untreated water temperature there is a closed-loop controller 9 that, on the one hand, senses a current untreated water temperature by means of a temperature sensor 36, and on the other hand, by means of the pump 37 connected into the water line 41 between the vessel 7 and the untreated-water mixer 6, conveys an appropriate quantity of waste water from the vessel 7 into the untreated-water mixer 6. If the heat demand for the preheating of the untreated water in the untreated-water mixer 6 exceeds that which can be achieved by the quantity of water present in the vessel 7, the blown-off water quantity is increased, by means of a corresponding open-loop control 10, even if this were not necessary on the basis of a water chemistry requirement.
Finally,
Number | Date | Country | Kind |
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102015201143.7 | Jan 2015 | DE | national |
This application is the US National Stage of International Application No. PCT/EP2015/079113 filed Dec. 9, 2015, and claims the benefit thereof. The International Application claims the benefit of German Application No. DE 102015201143.7 filed Jan. 23, 2015. All of the applications are incorporated by reference herein in their entirety.
Filing Document | Filing Date | Country | Kind |
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PCT/EP2015/079113 | 12/9/2015 | WO | 00 |