Abstract:
A steam turbine unit, in particular for a steam power plant, comprising a steam turbine and a condenser connected to the steam turbine via an evaporation channel is provided. According to the following, a sound damper, particularly a low-frequency sound damper, is acoustically coupled to the evaporation channel.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to PCT Application No. PCT/EP2013/058087, having a filing date of Apr. 18, 2013, based off of DE 102012207176.8 having a filing date of Apr. 30, 2012, the entire contents of which are hereby incorporated by reference. 
     
    
     FIELD OF TECHNOLOGY 
       [0002]    The following relates to a steam turbine unit, in particular for a steam power plant, having a steam turbine and a condenser which is connected to the steam turbine via a waste steam duct. 
       BACKGROUND 
       [0003]    Steam power plants, otherwise known as thermal power plants, are extensively known, for example from http://de.wikipedia.org/wiki/Dampfkraftwerk (retrieved Apr. 20, 2012). 
         [0004]    A steam power plant is a type of power plant for generating electricity from fossil fuels, in which thermal energy from steam is converted into kinetic energy in a steam turbine and is further converted into electrical energy in a generator. 
         [0005]    In such a steam power plant, the steam required for operating the steam turbine is first generated in a boiler from (feed) water, which generally has been previously purified and prepared. Further heating the steam in a superheater increases the temperature and specific volume of the steam. 
         [0006]    From the boiler, the steam flows via pipes into the steam turbine, where it gives off part of its previously absorbed energy as kinetic energy to the steam turbine. A generator is coupled to the steam turbine and converts mechanical power to electrical power. 
         [0007]    Thereafter, the expanded and cooled steam flows out of the steam turbine via a waste steam line or a waste steam duct into the condenser, where it condenses by transfer of heat to the surroundings and collects as liquid water. 
         [0008]    Via condensate pumps and through preheaters, the water is held in a feed water container and is then once again supplied to the boiler by means of a feed pump, thus closing a circuit. 
       SUMMARY 
       [0009]    A distinction is drawn between various types of steam power plants, such as coal-fired power plants, oil-fired power plants, or also gas-and-steam combined-cycle power plants (COGAS power plants), which differ in their different methods for generating steam. 
         [0010]    A COGAS power plant is described for example in http://de.wikipedia.org/wiki/Gas-und-Dampf-Kombikraftwerk (retrieved Apr. 20, 2012). 
         [0011]    A COGAS power plant of this type is a power plant in which the principles of a gas turbine power plant and of the steam power plant are combined. A gas turbine serves here as a heat source for a downstream waste heat boiler which in turn serves as a steam generator for the steam turbine. 
         [0012]    It is further known that turbomachines, such as the steam turbines, produce relatively high pressure emissions and/or sound emissions which, in addition to vibrations and structure-relevant malfunctions, can also lead to (noise) disturbance in the surroundings of the turbomachine. 
         [0013]    For example, dominant pressure/sound sources in a steam turbine are typically generated at a rotor disk, caused by the high speed of the fluids flowing through these regions and by an interaction between rotor components and stator components. 
         [0014]    It is further known in this case that these emerging pressure/sound sources generate complex, dynamic, three-dimensional, rotating and/or pulsating pressure fields, whose pressure/sound waves propagate, via the fluid or flow medium, in adjacent flow spaces both downstream and upstream of the specified point of origin, such as the waste steam ducts coupled fluidically to the steam turbine. 
         [0015]    In many such steam power plants having described steam turbines, an elevated sound pressure level, in particular at low frequency ranges, for example at frequencies&lt;500 Hz, was measured in the waste steam duct connecting the steam turbine to the condenser. 
         [0016]    This low-frequency sound is transmitted further, through or via the waste steam duct, into the condenser. This acts as a loudspeaker and transmits the sound further into the surroundings of the condenser or steam power plant. 
         [0017]    This can lead to high noise load or noise pollution in the surroundings of the power plant, for example in residential areas adjacent to the steam power plant. In particular, low-frequency noise is also experienced as an unpleasant rumbling. 
         [0018]    If the sound emissions of the steam power plant exceed sound protection limit values, this can in the worst case lead to the steam power plant losing its operating permit. 
         [0019]    Low-frequency sound, as can be observed in the waste steam ducts, also has the disadvantage that it cannot be effectively blocked or damped by means of insulation, for example on the waste steam duct. 
         [0020]    Low-frequency sound also excites eigenfrequencies of adjacent components. This can lead to damage to components. 
         [0021]    Silencers, i.e. generally devices for reducing sound emissions, are generally known. There are several basic designs for silencers, which reduce the generated sound power on the basis of various mechanisms. In general, absorption silencers or interference/reflection silencers—hereinafter designated just as reflection silencers—are used. 
         [0022]    Such a reflection silencer contains multiple, for example four, chambers in order to make use of the principle of acoustic reflection. 
         [0023]    Multiple passes through the chamber internal spaces produces an averaging of sound pressure amplitudes, which results in a reduction of sound pressure peaks. 
         [0024]    The acoustic reflections are generated in the reflection silencer by baffles, cross-sectional widenings and narrowings. 
         [0025]    In the reflection silencer, principally the low frequencies are damped by the acoustic reflection. 
         [0026]    An absorption silencer contains a porous material, in general rockwool, glass wool or glass fiber, which partially absorbs sound energy, that is to say converts it into heat. 
         [0027]    The effect of the sound absorption is then reinforced by the multiple reflection. 
         [0028]    In the absorption silencer, principally the upper or higher frequencies are damped by absorption. 
         [0029]    A low-frequency silencer embodied as an interference silencer or low-frequency silencer is known from HOBATHERM®, G:\VERKAUF\Technischer Ordner\Technischer Ordner 2008.doc, 3.4 Tiefton-Schalldämpfer. 
         [0030]    Embodiments of the invention are based on the aspect of creating a steam turbine unit having at least one steam turbine and a condenser which is connected to the steam turbine via a waste steam duct, which steam turbine unit overcomes the described drawbacks of the prior art. In particular, the embodiments of the invention are based on the aspect of creating such a steam turbine unit which can be operated in a manner which is safe for the components and with low sound emissions, and which can be produced cost-effectively and easily. 
         [0031]    The aspect is achieved with a steam turbine unit having the features according to the independent claim. 
         [0032]    The steam turbine unit corresponding to embodiments of the invention have at least one steam turbine and a (waste steam) condenser which is connected to the steam turbine via a waste steam duct or waste steam line, both referred to in the following simply as waste steam duct. 
         [0033]    In the steam turbine unit according to embodiments of the invention, it is further provided that a silencer is coupled acoustically to the waste steam duct. 
         [0034]    “Coupled acoustically” is to be understood as meaning that sound or sound waves occurring in the waste steam duct can enter the silencer for sound damping or sound attenuation therein. 
         [0035]    More simply, or in other words, waste steam supplied from the steam turbine to the condenser via the waste steam duct is, according to embodiments of the invention, guided in or through the silencer arranged in the waste steam duct, in which sound pressure levels occurring in the waste steam are damped or attenuated. 
         [0036]    Thus, by the use according to embodiments of the invention of the silencer, the in a simple or constructively simple and effective manner, damping of sound occurring in the waste steam duct. The high noise load or noise pollution in the surroundings of the steam turbine unit can thereby be reduced, and sound protection limit levels can be observed. 
         [0037]    In addition, vibrations and structure-relevant malfunctions—and consequently damage to components—which are caused by pressure emissions and/or sound emissions, can be reduced by means of embodiments of the invention. 
         [0038]    Preferred refinements of embodiments of the invention also emerge from the dependent claims. 
         [0039]    One preferred refinement provides that the silencer is a low-frequency silencer, in particular configured as an interference silencer or reflection silencer. 
         [0040]    Such a low-frequency silencer, embodied as reflection silencer, allows frequencies below 500 Hz to be damped in a targeted manner, simply and effectively. 
         [0041]    Since it has been established that in particular low-frequency sound occurs in the waste steam duct, which low-frequency sound is in addition experienced as an unpleasant rumbling, such a low-frequency silencer accordingly represents a most effective and efficient sound- or emission-protection measure in the steam turbine unit. 
         [0042]    According to one preferred refinement, the reflection silencer has one or more reflection chambers which are each configured for filtering a very specific range or band of frequencies. It is thus possible to damp broad frequency ranges. 
         [0043]    Thus, for example, a reflection tube silencer having multiple series-connected outer resonance chambers can be provided, which resonance chambers function for example as lambda/2 resonators, lambda/4 resonators or Helmholtz resonators. 
         [0044]    The reflection chambers may be embodied with or without any absorption material, such as stainless steel or mineral wool. The reflection chambers may furthermore be embodied as a welded construction. 
         [0045]    The reflection chambers may also each be equipped with a liquid discharge or condensate discharge. Furthermore, cleaning openings may also be provided in the reflection chambers. 
         [0046]    One particularly preferred refinement provides that a reflection chamber of such a reflection silencer is formed by an inner sheet metal ring which is provided with longitudinal holes or slits and which is enclosed concentrically by a further ring. Multiple double rings of this type may be arranged in series in the waste steam duct—either immediately adjacent to one another or at a distance from one another—or may be coupled acoustically therewith. 
         [0047]    In order to configure the silencer to frequencies to be damped—in the waste steam duct—it is preferably possible to carry out a frequency analysis or a sound level measurement in the third-octave spectrum of noises in the waste steam duct. Depending on the result of this, a suitable silencer, for example a reflection silencer for low-frequency sound or an absorption silencer for higher-frequency sound, or a suitable or accordingly adapted configuration of the silencer, for example reflection chambers configured to certain frequencies or frequency bands in the case of a reflection silencer, may then be used. 
         [0048]    Another particularly preferred refinement provides that the silencer is configured to damp low frequencies, for example below 500 Hz, in particular between 40 Hz and 500 Hz. Very particularly preferred is a configuration of the silencer to damp frequencies between 60 Hz and 250 Hz. 
         [0049]    A particularly simple constructive embodiment is achieved by the silencer being arranged in the waste steam duct such that waste steam from the steam turbine can flow through it. 
         [0050]    A further refinement provides that the silencer has a drainage device. It is thereby possible to avoid liquid or condensed waste steam, simply condensate for short, which is precipitated from the waste steam, collecting in the silencer and the latter thus being caused to vibrate. 
         [0051]    This can be effected particularly simply if, in the case of a reflection silencer having reflection cavities, these reflection cavities are provided with drainage ducts or outflow bores. 
         [0052]    What are termed hotboxes are often in each case arranged in steam turbine units or in their waste steam ducts. By virtue of such a hotbox, bypass steam can be fed into the waste steam duct. One preferred refinement then provides in this case that the silencer is coupled acoustically to such a hotbox. 
         [0053]    A further preferred refinement provides that the silencer is coupled acoustically to a further silencer, whereby both silencers are then coupled acoustically to the waste steam duct. It is hereby possible, in a manner which is very simple and efficient (in terms of construction), to damp more frequencies and/or larger frequency bands of the sound occurring in the waste steam duct. 
         [0054]    Particularly preferably, the silencer may here be an interference silencer—for damping the low-frequency sound—and the further silencer, coupled acoustically to the interference silencer, may be an absorption silencer—for damping the higher-frequency sound. 
         [0055]    It can also be provided that the steam turbine has multiple sections or turbine sections. Thus, the steam turbine may be provided with a low-pressure, an intermediate-pressure and/or a high-pressure section. The turbine sections may be of single- or multiple-flow, in particular two-flow, design. 
         [0056]    Waste steam ducts which leave or lead away from these sections or turbine sections—in each case to the condenser—may thus be equipped with the silencer according to embodiments of the invention. Alternatively, it is also possible in this case for individual waste steam ducts or several or all of these waste steam ducts to be combined into a “central” waste steam duct leading to the condenser—and for the silencer according to embodiments of the invention to be coupled acoustically to this “central” waste steam duct. 
         [0057]    In that context, the silencer may be arranged within a machine casing which encloses the steam turbine at least partially or even entirely. Alternatively, it can also be provided that the silencer is arranged outside such a machine casing. 
         [0058]    One preferred refinement provides that the steam turbine installation according to embodiments of the invention are arranged in a steam power plant or in a water/steam circuit created there. 
         [0059]    In that context, the steam power plant may be a coal-fired power plant, an oil-fired power plant or a gas-and-steam combined-cycle power plant. 
         [0060]    The above description of advantageous configurations of embodiments of the invention contain numerous features which are reproduced in the individual subclaims, in some cases combined into groups. However, a person skilled in the art will expediently also consider these features individually and combine them into appropriate further combinations. 
         [0061]    The figures show exemplary embodiments of the invention which will be explained in more detail below. Identical reference signs in the figures denote technically identical elements. 
     
    
     
       BRIEF DESCRIPTION 
         [0062]    Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein: 
           [0063]      FIG. 1  shows a water/steam circuit having a steam turbine unit, consisting of a steam turbine and a condenser connected to the steam turbine via waste steam ducts, in a steam power plant according to one exemplary embodiment of the invention; 
           [0064]      FIG. 2  shows a detailed representation of a low-frequency silencer for a waste steam line or a waste steam duct in the steam turbine unit or in the steam power plant according to the exemplary embodiment of the invention; and 
           [0065]      FIG. 3  shows a waste steam line, equipped with a low-frequency silencer, in a steam turbine unit or in a steam power plant according to the further exemplary embodiment of the invention. 
       
    
    
       [0066]    Exemplary embodiments: low-frequency silencer  2  for a waste steam duct  24  in a steam power plant  100  with an (air/waste steam) condenser  11 . 
       DETAILED DESCRIPTION 
       [0067]      FIG. 1  shows a water/steam circuit  18  of a coal-fired steam power plant  100  with a steam turbine unit  1  consisting of a steam turbine  22  and a condenser  11  connected to the steam turbine  22  via waste steam ducts  24 . 
         [0068]    In this coal-fired power plant  100 , in the following simply steam power plant  100  for short, according to a conventional coal firing, lignite or hard coal is ground and dried in a coal mill. This coal is then blown into a combustion chamber  16  for a dust firing facility, where it is completely burnt  17 . 
         [0069]    Heat thus released is taken up by a water-tube boiler, steam generator  20  for short, and converts fed-in (feed) water  5  into steam/high-pressure steam  6 . The high-pressure steam  6  generated in the steam generator  20  enters the high-pressure section  7  of the steam turbine  22 , where it performs mechanical work as it expands and cools. 
         [0070]    After leaving the high-pressure section  7 , the high-pressure steam  6  flows via a crossover line  23  into the two-flow low-pressure section  8  of the steam turbine  22 , where further mechanical work is performed as the steam expands and cools to waste steam pressure. 
         [0071]    The generator  9  coupled to the steam turbine  22  then converts the mechanical power into electrical power, which is supplied to a grid  15  in the form of electrical current. 
         [0072]    The waste steam  25  from the steam turbine  22  or from the two-flow low-pressure (turbine) section  8  of the steam turbine  22  is supplied, via the two waste steam ducts  24 , to the condenser  11  where the waste steam  25  condenses with the aid of the cooling water  13  delivered through the cooling water circuit  10  by a cooling water pump  12 . 
         [0073]    The resulting condensate or feed water  5  is supplied back to the steam generator  20  by the condensate pump or feed water pump  4 , with heating in the preheater  14 . 
         [0074]    In order to damp high levels of low-frequency sound in the two waste steam ducts, these are each coupled acoustically to a low-frequency silencer  2 , which is shown in more detail in  FIG. 2 . 
         [0075]    To that end, as shown in  FIG. 1 , these two low-frequency silencers  2 , configured as reflection tube silencers—reflection silencers  2  for short—which are particularly suited to damping low-frequency sound emissions, are arranged in the two waste steam ducts  24  through which the waste steam  25 , flowing out of the two-flow low-pressure turbine section  8 , can flow. 
         [0076]      FIG. 2  shows a detailed representation of the low-frequency silencer  2  which is coupled acoustically to the two waste steam ducts  24 , or which is arranged in the two waste steam ducts  24  and through which the waste steam  25  flows. 
         [0077]    The low-frequency silencer  2  is designed as a reflection silencer  2  having three reflection chambers  26 ,  27  and  28  which are arranged in series in the flow direction  36  of the waste steam  25  and which function as lambda/2 resonators. 
         [0078]    The reflection chambers  26 ,  27 ,  28 , which are free from absorption material or fibers, are formed by a smooth stainless steel inner tube  29  through which the waste steam  25  flows and which is enclosed concentrically by a jacket tube  30 , also made of stainless steel. 
         [0079]    The interspace  31  thus formed between the two tubes  29  and  30  is divided or delimited by means of two separating disks  33 ,  34  and by means of two cover disks  32 ,  35 , whereby the three reflection chambers  26 ,  27 ,  28  are formed, each having a different size or volume. 
         [0080]    Each of the reflection chambers  26 ,  27  and  28  filters—on account of its different size or volume and its differently configured inlet opening  37 —a certain frequency range, which has been determined by means of frequency analysis of the noises in the waste steam duct  24  and according to which the respective reflection chamber  26 ,  27  or  28  has then been accordingly dimensioned or adapted. 
         [0081]    The reflection chambers  26 ,  27  and  28  represented are for example in this case configured so as to damp frequencies or frequency bands between 40 Hz and 500 Hz. 
         [0082]    At the start—as seen in the flow direction  36 —of a given reflection chamber  26 ,  27  or  28 , in a (starting) region  38  located there, are created the inlet openings or slits  37 , which are distributed over the circumference of the inner tube  29  and are of different configurations, and which allow the sound to enter from the inner tube  29 —through which the waste steam flows—into the respective reflection chamber  26 ,  27  or  28 . 
         [0083]    The construction of the reflection silencer  2  is effected by welding. The reflection chambers  26 ,  27  and  28  may (not shown) be provided with cleaning openings. 
         [0084]    The reflection chambers  26 ,  27  and  28  each have a drainage opening  39  to a liquid discharge, in order that no waste steam liquid or condensate, precipitated from the waste steam  25 , collects there, i.e. in the reflection chambers  26 ,  27  and  28 , and is caused to vibrate. 
         [0085]      FIG. 3  shows a further configuration of a waste steam duct  24  equipped with the low-frequency silencer  2 , as can be provided in the steam turbine unit  1 . 
         [0086]    As shown in  FIG. 3 , at the beginning (as seen in the flow direction  36 ) of the waste steam duct  24 , there is arranged what is termed a hotbox  40  which has multiple in-lines  43  (two in-lines  43  shown here), inter alia for bypass steam. 
         [0087]    The low-frequency silencer  2  is arranged downstream (as seen in the flow direction) of this hotbox  40 , such that the waste steam  25  leaving or flowing out of the hotbox  40  flows through the low-frequency silencer  2  and onward to the condenser  11 . 
         [0088]    As  FIG. 3  also shows, the low-frequency silencer  2  has the three reflection chambers  26 ,  27  and  28  which, however, have been altered in terms of their volume by further additional separating disks  41  and  42 —in this case adapted to (other) low frequencies to be damped. 
         [0089]    Here, too, the reflection chambers  26 ,  27  and  28  are each provided with a drainage opening  39 . 
         [0090]    In this case, the waste steam line  25  is outside a machine casing (not shown) which incorporates the steam turbine  22 . 
         [0091]    Although the invention has been illustrated and described in more detail by means of the preferred exemplary embodiment, the invention is not limited by the disclosed example and other variations may be derived herefrom by one skilled in the art without departing from the scope of protection of the invention.