Abstract:
The invention relates to a steam power plant which consists essentially of a steam generator ( 1 ), a turbo group comprising a condensing steam turbine ( 2 ) and generator ( 3 ), a water-cooled condenser ( 4 ) and a bled-steam-heated preheating system. In said steam power plant all components, including the fuel storage area ( 6 ), are situated at ground level and in the open air. The turbo group ( 2, 3 ) and the condenser ( 4 ), the preheating system with associated pumps and the transformers ( 7 ) are arranged such that a gantry crane is able to pass over them. The steam generator ( 1 ), flue gas cleaning system ( 16 ) and the chimney ( 17 ) are positioned in a row along a common flue gas axis ( 18 ) and the turbo group ( 2, 3 ) arranged in the immediate vicinity and parallel thereto. As seen from the main wind direction ( 9 ), the coal storage area ( 6 ) is positioned downwind from the turbo group ( 2, 3 ) and the steam generator ( 1 ).

Description:
FIELD OF TECHNOLOGY 
     The invention relates to a steam power plant, comprising essentially a steam generator, a turbo group with condensation steam turbine and generator, a water-cooled condenser, and a bleeder steam-heated pre-heater system. 
     STATE OF THE ART 
     Such power plants are usually produced according to customer specification and site requirements and therefore involve lengthy project development, planning, and construction times and, as a result, high costs. Especially the construction time in these customer specification-oriented power plants is influenced by the fact that a very detailed advance engineering is not possible, and essential aspects of the work, for example the construction portion, which should be processed as early as possible, only can be started with a delay. 
     It is known per se to reduce the construction time by building power plants using open air construction. But this type of construction again causes a number of disadvantages with respect to their operation as well as maintenance and repair. In this connection, DE 1426918 A1 discloses the concept of a steam power plant designed to be built in a shorter construction time and reduced investment costs, and which is supposed to hereby reduce said disadvantages. This concept is essentially based on the fact that the turbo group is arranged in a lane between the steam generators and a portal crane is mounted on the steam generators in order to facilitate both their assembly as well as the assembly of the turbo group. In addition, the principle of multipurpose use has been realized in such a way that the support frames of the steam generator or the coal bunker are at the same time equipped for receiving secondary installations, and the portal crane is able to serve both steam generator and power generator parts. The steam power plant constructed according to this concept is very compact and is brought together within a tight outline. The main emphasis of this solution is the reduction of construction time and expenditures. The price for the advantages of a small space requirement and multipurpose use of support frames is a vertical arrangement of numerous installation parts. But it is especially this vertical arrangement of numerous installation parts whose assembly is facilitated with the highly positioned portal crane during the construction phase, that excludes a use of the crane for necessary repair and maintenance purposes of the same installation parts in the operation phase. After the construction phase, the crane &#39;s use is essentially limited to the turbo group, since it is unable to access the installation parts of all intermediate planes. 
     DESCRIPTION OF THE INVENTION 
     The invention is designed to remedy this problem. Starting with the mentioned state of the art, the invention is based on the objective of creating a steam power plant characterized by very friendly maintenance and repair friendliness. In addition, a steam power plant should be created that achieves substantial standardization and can be built at a variety of possible sites. 
     The invention therefore is based on a steam power plant comprising essentially a steam generator, a turbo group with condensation steam turbine and generator, a water-cooled condenser, and a bleeder steam-heated pre-heater system and a portal crane and is characterized in that all components of the steam power plant, including the fuel storage site, are located at ground-level and placed in an open air arrangement and the portal crane swings over an area in which the turbo group with the condenser, pre-heater system and associated pumps as well as the transformers are arranged. 
     If the steam generator, flue gas cleaning system and chimney are located in series within a common flue gas axis, it is useful that the turbo group is located immediately adjacent and parallel to them. 
     If the fuel storage site is a coal heap, it would be suitable to locate it down-wind—seen in the main wind direction—behind the turbo group and steam generator. 
     The advantage of all these measures is in particular that the standardization of the installation engineering and of the components reduces the investment costs to a remarkable degree. The outline of the power plant is formed by a clearly defined rectangle. This makes it possible to expand the installation at any time by simply placing such rectangles next to each other. The previously common, very extensive project engineering is no longer required hereby. The power plant blocks that will be located next to each other are identical; only the access roads must be minimally adapted. Another advantage is the consistently realized open air placement. This makes it possible to forego the expensive and time-consuming construction of buildings, such as boiler and machine house. The measure of arranging the turbo group with the condenser, pre-heater system and associated pumps, as well as with at least the own-demand transformers in such a way that a portal crane can swing over them also defines a rectangular cross-section for these components. This makes it possible to arrange the installation parts in the tightest space directly next to each other without negatively affecting operation and maintenance. Maintenance and repair work can be performed with the crane. This arrangement also enables the shortest possible connections between the various installation parts, which again has a positive effect on assembly and maintenance. 
     The sensible measure of locating the coal heap down-wind behind the turbo group and the steam generator in no way has an adverse effect on the requirement of a rectangular cross-section of the installation and can be performed independently from the wind direction. This makes it possible to avoid coal dust emissions in the area of the technical installations and administrative operations. The desired rectangular cross-section in any case can also be realized in relation to the geographical location of the body of water necessary for cooling purposes. The respective situation plan in each case naturally takes into account this water location, whereby the emphasis here is also on the shortest possible connection paths. 
     A flatbed feeder located at ground level is provided for depositing the unground coal onto the inclined belt to the coal breaker. This means that the large and deep, concrete-lined, subterranean feeder pit that usually was required up to now is no longer necessary, which greatly reduces civil engineering work. 
     The steam generator is preferably supplied with roughly ground coal from coal silos. It is hereby reasonable that the coal silos associated with the steam generator are connected with the coal breaker located upstream from the steam generator by an at least approximately horizontally extending conveyor device with subsequent vertical conveyor device. The ground-level placement of the horizontally extending conveyor device makes it possible to eliminate complicated steel frames. 
     The steam turbine has an axial exit so that the steam condenser is located in the axial extension of the steam turbine. This solution, which is advantageous because of the almost ground-level placement of the turbo group, as well as the open air placement, allows unlimited access to the condenser. If condenser pipes must be replaced, this does no longer require removal facade elements from a building, as was the case in the past. In addition, the portal crane swinging over the condenser can be used for such maintenance procedures. 
     It is advantageous if all pre-heaters are designed for the same pressure on their water side, have essentially the same dimensions, and are located adjacent to the turbo group. This measure guarantees the shortest connections both on the water and steam side and also allows use of the portal crane for maintenance work. 
     Starting with the recognition that because of lacking advance planning and customization to client specifications the construction time for a power plant is extraordinarily long today, the invention, as characterized in the claims, is based on the task of achieving substantial standardization and creating a power plant that can be built at a variety of possible sites. 
    
    
     BRIEF DESCRIPTION OF DRAWING 
     The drawing shows an exemplary embodiment of the invention in the form of a single-shaft, axial-flow turbo group with coal as the primary fuel. Only elements essential to understanding the invention are shown. What is not shown of the installation is, for example, the numerous lines between the machines and equipment as well as most of the termination and control fittings, etc. The flow direction of the various working media is shown by the arrows. In the drawing: 
     FIG. 1 shows the principle layout of the installation; 
     FIG. 2 shows a multi-installation; 
     FIG. 3 shows a top view of the turbo group and adjacent area; 
     FIG. 4 shows the transport path of the coal from the coal heap to the steam generator; 
     FIG. 5 shows the heat diagrammatic of the installation; 
     FIG. 6 shows the cooling water removal; 
     FIG. 7 shows the liquid fuel diagrammatic; 
     FIG. 8 shows the principle layout of the installation for a different wind direction; 
     FIG. 9 shows the principle layout of the installation with a different location of the body of water. 
    
    
     WAY OF EXECUTING THE INVENTION 
     According to FIG. 1, an installation module containing all of the power plant components carries the reference number  200 . Such a module could comprise, for example, a 150 MW installation and is preferably built in an exclusively industrial zone in order to protect neighbors from emissions, such as dust, noise, and truck traffic. Reference number  6  indicates the fuel storage site. In this case, this is an open coal storage having a rectangular outline. In the shown example, the coal heap is located directly adjacent to a river  20 , which means that the coal can be delivered by ship. Naturally, it my also be delivered by train or trucks over access roads  36 . If the installation is near a coal mine, transport via conveyor belts would also be possible. 
     Based on this coal heap  6 , the basic orientation of the power plant elements is then determined by the main wind directions  9 . 
     The coal is first piled with a shovel dozer  49 —that also can be used for excavation work during the construction phase—from the heap  6  onto a flatbed feeder  10  (FIG.  4 ). From there, the piled up transported material  41  reaches the inclined belt  11  leading to the coal breaker  20 . As already mentioned initially, the feeder  10  eliminates the need for a concrete-lined pit in which the coal is guided via funnels onto a conveyor belt. Since the feeder  10  is located at ground-level on a foundation plate, this new measure, in comparison to the pit solution, also reduces the length of the inclined belt  11  that must convey the material to the inlet of the breaker building  12  which is usually located at a height of about 15 to 20 meters. 
     From the coal breaker, the transported material is first transported via a horizontal conveyor device  14  and then via a vertical conveyor device  15  to a horizontal conveyor  43  from which it is filled into the coal silos  13 . This solution has several advantages over the previously common inclined belt conveyance to the silos. Since the charging system of conventional boiler silos is usually located at a height of 50 meters, an inclined belt conveyance with the usual 14° to 15° incline must be almost 200 meters long. The present new measure makes it possible to reduce this length drastically, so that the coal breaker  20  can be located very close to the boiler. Furthermore, the horizontal conveyor device  14  can be built at ground level on simple concrete ties. Extensive steel constructions, such as in the case of inclined belt conveyance, which also require a high crane capacity during assembly, are no longer necessary. It should be understood that the access to a horizontal conveyor belt extending at ground level is also simplified because of the elimination of operating and walking ways. 
     This type of construction—first horizontal, then vertical—also allows the principal standardization of the subsequent vertical conveyor device  15 . This is an encased bucket conveyor with a simple carrying structure that is also positioned at ground level and is preferably connected with the boiler structure in order to take up horizontal loads. Because of all of this, only the length of the horizontal conveyor device  14  must be adapted to different situations in each case, i.e. the distance between coal heap and boiler. 
     The steam generator  1  works with atmospheric fluidized bed combustion. Hereby roughly broken coal with a particle size of about 6 mm can be used. The advantage in this is that in addition to the coal breaker  20  no additional coal mill is required. The steam generator is held in a steel frame; an exterior encasing or roof is no longer necessary. 
     FIG. 1 shows that a tank  24  for liquid fuel is located directly before the steam generator. This liquid fuel is necessary for starting up the steam generator and for the stabilizing fire. The location of this tank has been chosen with respect to short conveyance distances. The tank itself is located in a concrete collecting basin. The pumps  25  for the start-up fuel are located immediately next to the tank  24  on pedestals projecting from the concrete foundation plate. This foundation plate is hereby constructed as a collecting basin for the pump area. 
     The tank can be filled from the road  36  by tanker trucks. It was found that an advantageous solution is to use the pumps  25  for the start-up fuel both for charging the burners and for filling the tank. FIG. 7 shows how this can be realized. To fill the tank, the pump  25  withdraws fuel from the tanker truck via an appropriately set three-way element  47  and transports it via another appropriately set three-way element  46  through filling line  48  into the container. To start up the steam generator and for the stabilization fire, the pump  25  again transports the fuel from the tank  24  to the burners  45  of the boiler  1  by way of three-way elements  47  and  46  that are again set appropriately. 
     Since the steam generator  1  functions with atmospheric fluidized bed combustion, no desulfuration of the flue gases is necessary. Accordingly, the boiler is followed immediately by the flue gas cleaning system  16  that consists essentially of an electrostatic separator or a fibrous filter. The cleaned waste gases are released through the chimney  17  into the atmosphere. FIG. 1 shows that the steam generator  1 , the flue gas cleaning system  16 , and the chimney  17  are located in the longitudinal axis of the boiler in a so-called flue gas axis  18 . 
     The machine axis  33  then extends parallel to this flue gas axis  18 . The turbo group  2 , 3  and the condenser  4 , as well as the transformers  7  and preferably the open air switching installation  34  are arranged in this axis. Here the difference to other installations in which the turbo group is usually located at the frontal face of the steam generator  1  can be seen. 
     Module  200  further shows the road system  36  that permits access to the installation, a workshop  31 , and a switching installation system  32 , as well as the cooling tower system  35 , the added water  19  leading there, and the water reprocessing system  30 . To keep the piping short, a placement of the cooling tower system as close as possible to the condenser  4  is desired. An above-ground arrangement has been selected for these pipes so that the construction work for the installation construction is not adversely affected. For the alignment of the cooling cells with each other, both the function of the predominant wind direction as well as the distance to the turbine and boiler was considered; the objective hereby is not to adversely affect the ventilation of the cooling towers. 
     The added water is removed without the previously common, extensive intake mechanisms. FIG. 6 shows that the added water is transported in the simplest manner via a dirty water pump  22 . In the present example, this pump is located in a concrete pipe  21  that can be submerged in the body of water  20 . The concrete pipe preferably consists of individual, stacked concrete rings, of which at least one is provided with inlet openings  44 . The pipe  21  and pump  22  stand on a thin concrete plate placed into the river bottom. The water removal unit can be accessed via a walkway  37 . The water pipes  19  extend near the bottom and are supported on ties  38 . 
     As much as possible, mechanical and electrical accessories are prefabricated and pre-assembled and are transported to the installation in transport containers. For assembly, the containers are placed by a crane on simple concrete ties. This reduces both the customization engineering and the assembly time. The same applies to the entire lubrication and control oil system, including oil tank and pumps, that can be delivered pre-assembled and are placed immediately next to the turbo group into a concrete collecting basin. 
     For the same wind direction and same river course as in FIG. 1, FIG. 2 shows an arrangement of three modules  200 . The only difference to the installation according to FIG. 1 is the continuous roads  36 . This shows that an installation can be expanded at any time without adversely affecting the operation of the already existing modules. If it is even known before a power plant installation is built, that it will eventually consist of several modules, naturally a common coal heap and common cooling water removal will be considered. 
     FIG. 3 shows those elements over which the portal crane  8  swings according to the present invention. At the right edge of the illustration, the flue gas axis  18  with the elements pumps  25  for start-up fuel, coal silos  13 , steam generator  1 , and flue gas cleaning system  16  are shown. The fact that the installation does not need any buildings and the arrangement of the pre-heaters on the side facing away from the boiler—described below—now makes it possible that the actual turbine  2  can be located directly adjacent to the boiler  1 , thus enabling extraordinarily short connecting lines not shown in this figure. This particularly holds true for the fresh steam line. 
     The crane tracks  39  of the portal crane  8  are supported on both sides on concrete columns  40 , so that the passage of steam lines, water lines, and cable channels is not hindered. Their length is such that they include the own-demand transformer  7  and the feed pump block  26 , both of which are arranged in the machine axis  33 . The crane width has been selected so that the crane ( 8 ) is also able to serve the pre-heater system  5  and the switching system building  32 , both of which are constructed in container construction. This shows that this crane ( 8 ) is also required for the initial construction of the installation, so that no mobile lifting systems are necessary. Accordingly, the loading capacity of the crane is designed for the heaviest turbine parts that must be moved during assembly. This does not apply to the generator  3  that is preferably brought into its operation position via skid rails. 
     The advantage of the ground-level placement of all mentioned elements and their operation via portal crane cannot be underestimated. Especially in those market segments that permit an open air arrangement of the installation, among others for climatic reasons, often mobile cranes with an adequate design and loading capacity are not available. This is especially true if the completed installation deviates from the plan, in which case this must be immediately remedied. 
     Where the actual machine is concerned, in this case comprising a steam turbine with a high-pressure part  2 A, an intermediate pressure part  2 B, and a low pressure part  2 C, as well as a generator  3 , the term “ground level” must be qualified. In fact, this is an almost ground-level placement, whereby it should be understood that it is not a construction in which the machine is placed onto a foundation table that itself is supported by steel or concrete columns. This almost ground-level placement of the machine is made possible because the waste steam of the low-pressure turbine  2 C is axially oriented, and the condenser neck of the condenser  4  that is located on the same level is connected via flange with the waste steam. As a result of this construction, the machine axis  33  is only 5.5 meters above the ground, eliminating the need for the usual operating platform around the machine and any intermediate floors. Platforms with corresponding staircases are only provided at places where an access for operating personnel and maintenance purposes is absolutely necessary. 
     The turbo group  2 ,  3  with condenser  4  is supported by a simple, monolithic concrete foundation plate, whereby column plates projecting from the foundation support the bearings and cases. The above mentioned required platforms are located at a height of about 4.5 m above the ground. The oil lines are placed on them. 
     Because of the open air arrangement, the turbine cases are equipped with weather-resistant covers with correspondingly designed ventilation openings. These covers are also supported on the mentioned platforms. 
     All turbine housings are provided with a horizontal separation level, and at least all steam bleeder lines ( 110  in FIG. 5) are arranged on the respectively lower housing half. This means that these lines need not be removed when the top housing halves are covered as required during maintenance work on the blades or rotor. The low placement of the lines above the ground that results from this also has the advantage that the supports for the pipes can be constructed simply and can be simply installed even during the initial assembly. Access during any necessary welding work, tests, and insulations is also simplified. The close-to-the-ground placement of the bleeder steam lines now suggests that the feed water pre-heaters  5  are arranged accordingly. They are located immediately adjacent to the turbine. In the example of a 150 MW installation, the pre-heater installation consists of five devices located next to each other. It should be understood that they could be partially located on top of each other—without deviating from the underlying concept of ground-level placement—for example 3 pre-heaters on the ground, and 2 pre-heaters above them. The decisive factor here is that they can be operated from the portal crane  8 . The selected arrangement next to the turbine  2  results in short bleeder steam lines. The fact that they are not located on the boiler side but on the opposite side has the advantage that the bleeder steam lines and the steam lines leading to the steam generator are separated from each other. The close-to-the-ground placement of the pre-heaters also allows simple supports in the form of concrete pedestals that also carry the feed water lines and bleeder steam lines. 
     All pre-heaters  5  essentially have the same dimensions and are designed on the water side for the same pressure. This already indicates that the water-steam cycle is designed so that it does not need a feed water tank/degasser. This usually large and heavy device is usually arranged at a height of about 15 meters and requires the corresponding expensive supports. By eliminating this tank and the corresponding line placement, a significant reduction in investments costs and assembly time can be realized. 
     The water-steam cycle is shown in a simplified manner in the heat diagrammatic in FIG.  5  and shall be briefly described below. The feed water enters the economizer  101  of the steam generator  1  at the usual conditions (170 bar, about 250° C.) and from there reaches the steam collecting drum  103 . In the natural cycle, the water is passed through the evaporator  102  and then, as saturated steam, back into the drum. In the multi-part superheater  104  (not shown), it is heated to its final temperature of 540° C. and conducted via the fresh steam line  105  into the high pressure part  2 A of the steam turbine. There, the steam is expanded to a pressure of about 40 bar while releasing power in the process. The steam is returned via the cold intermediate superheater line  106  into the boiler, is reheated in the intermediate superheater there again to 540° C., and is conducted via the hot intermediate superheater line  108  into the intermediate pressure part  2 B of the steam turbine. After repeated partial expansion, the steam passes from the intermediate pressure part into the low pressure part  2 C, in which it is expanded to condenser pressure. In the water-cooled condenser  4 , the steam is condensed, the condensate collects in the hot well (not shown), from where it is transported by the condensate pump  111  into the pre-heater system. To this extent, such installations are known. 
     To simplify the pre-heater system, the following concept has now been chosen. The feed pump  26  is constructed in two stages. On the water side, a primer pump  27  is arranged upstream from the pre-heaters  5 , and a main pump  28  is arranged downstream from the pre-heaters. The two-stage feed pump is provided with a common drive  29 . In the pre-heaters, the feed water is heated to the boiler inlet temperature with bleeder steam removed via the stages of turbines  2 A- 2 C that correspond to bleeder lines  110 . The two-stage execution of the feed pump has the advantage that all pre-heaters can be designed on their water-side for the same low pressure and therefore can be manufactured in a cost-efficient manner. The final pressure of the primer pump  27  is selected as a function of the pressure loss within the pre-heater train and the permissible inlet pressure of the main pump  29 . 
     As a special feature, a compensation tank  23  for cold condensate is provided in the pre-heater train between the condensate pump  111  and feed pump  27 . This tank can function with a steam or inert gas pressure cushion and is used to supply the feed pump  27 . This tank is used especially in non-stationary operating conditions. 
     The heat diagrammatic of FIG. 5 also shows the generator  3 . This generator  3  is air-cooled, whereby the cooler box  112  is connected with a flange directly to the generator. A special feature here is that for the recooling of the cooling air circulating in the closed circuit non-desalinated cooling water is removed from the main cooling circuit  51 . In contrast to previous air/water coolers whose cooling elements were in most cases constructed of copper or nickel, stainless steel is used for this purpose. Nevertheless, the cooling water system is still more cost-efficient, since the use of main cooling water for cooling the generator makes it possible to construct the intermediate cooling system needed for other purposes, which works with reprocessed water, smaller and therefore cheaper. 
     The fact that the generator axis also is located at a height of about 5.5 meters above ground makes it possible to arrange the generator switches and exciter equipment (not shown) below the generator. They may be located on a simple concrete plate. The generator output lines are therefore located at the underside of the generator and extend serially, therefore resulting in the shortest possible line lengths. This solution prevents complicated support constructions, such as are known from the lateral exit of the output lines above the generator. 
     FIGS. 1 and 3 show the placement of the transformers  7  immediately near the generator  4 , which results in short bus bars  50 . The own-demand transformer and block transformers are separated from each other by a fire protection wall. The installations has been designed so that at least the own-demand transformer can be operated from the portal crane. 
     The switching system  34  can be designed as a gas-insulated high voltage module, which in the one hand significantly reduces the amount of space required, and on the other hand makes it possible that the switching system can be constructed very closely to the transformer system. The switching systems and attendance room are also constructed as containers. The modules are placed as prefabricated units with the portal crane onto a ground-level foundation plate with a surrounding pedestal. The space created in this way is used as a cable cellar. 
     FIGS. 8 and 9 show the selected principal layout for another wind direction and, respectively, for another course of the body of water. According to specification, the coal heap  6  in both arrangements is located down-wind. The figures show the great advantage of the coal transport concept. Only the length and course of the horizontal conveyor  14  must be adapted to the new situation. The installation in FIG. 9 differs from that in FIG. 8 by the different course of the river  20 . Because of a differently designed water removal, this only results in a different geometry of the module  200 . 
     List of Reference Numbers 
       1  steam generator 
       2  condensation steam turbine 
       2 A high pressure part 
       2 B intermediate pressure part 
       2 C low pressure part 
       3  generator 
       4  condenser 
       5  pre-heater system 
       6  fuel storage site 
       7  transformers 
       8  portal crane 
       9  main wind direction 
       10  flatbed feeder 
       11  inclined belt 
       12  coal breaker 
       13  coal silo 
       14  horizontal conveyor device 
       15  vertical conveyor device 
       16  flue gas cleaning system 
       17  chimney 
       18  flue gas axis 
       19  added water 
       20  body of water 
       21  concrete pipes 
       22  dirty water pump 
       23  cold condensate compensation pump 
       24  liquid fuel tank 
       25  pump for start-up fuel 
       26  feed pump 
       27  primer pump 
       28  main pump 
       29  feed pump drive 
       30  water reprocessing system 
       31  workshop 
       32  switching system building 
       33  machine axis 
       34  switching system 
       35  cooling tower 
       36  access road 
       37  walkway 
       38  tie 
       39  crane track 
       40  concrete columns 
       41  transported material 
       43  horizontal conveyor 
       44  inlet openings in  21   
       45  burner in  1   
       46  three-way element 
       47  three-way element 
       48  filling line 
       49  bucket loader 
       50  bus bar 
       51  main cooling water 
       101  economizer 
       102  evaporator 
       103  steam collecting drum 
       104  superheater 
       105  fresh steam line 
       106  cold intermediate superheater line 
       107  intermediate superheater 
       108  hot intermediate superheater line 
       110  bleeder line 
       111  condensate pump 
       112  generator cooling module 
       200  module