Machine Room

(in electric power plants), the part of the power house that houses the units that produce electric power (electric generators), as well as their driving engines (turbines or diesels) and associated auxiliary equipment. The machine rooms of state regional electric power plants, combined heat and electric power plants, and atomic, hydroelectric, gas-turbine, diesel, and geothermal power plants differ in terms of the type and layout of equipment.

Equipment in the machine rooms of state regional electric power plants, heat and electric power plants, and atomic power plants includes turbogenerators, steam turbines, condensers, heat exchangers, recirculation systems, and feed, circulation,-condensate-removal, and drainage pumps, as well as service equipment for the power plant itself. The machine rooms of heat and electric power plants also have preheaters and pumps for distribution pipelines. In atomic power plants operating on wet or slightly superheated steam, intermediate separators and steam superheaters are also located in the machine room.

Machine rooms have a transverse or longitudinal layout, according to the orientation of the turbine units. Turbines and generators are installed on reinforced-concrete or metal foundations. The depth of the foundation depends on the rated power and on the particular structural features of the equipment being installed. The upper reference mark on the foundation is the level at which maintenance of the turbine unit is conducted. The part of the machine room that is below the maintenance level is called the condenser room. The space in a machine room occupied by one turbine unit, its auxiliary equipment, and its maintenance platform is called a cubicle. In single-loop atomic power plants individual units are installed in concrete bays; a large part of the equipment is equipped with radiation shielding. In modern multiunit power plants the erection site for assembly of the main and auxiliary equipment of a unit is directly adjacent to each new unit (temporary site). An erection site is also located near the main wall (near the first unit) and is used for major repairs on equipment already in operation. The outer wall of the machine room is next to the bus-and-switch structure. The end wall adjacent to the premises is a main wall, and the opposite end wall, next to the area of possible expansion of the plant, is a temporary wall.

The dimensions of the machine room in a steam power plant depend on the number of units, their rated power, their type, and their relative arrangement. For example, the standard design of a GRES-2400 state regional electric power plant (eight units of 300 megawatts [MW] each) provides for a machine room 432 m long, 41.5 m wide, and 31.5 m high. A basement 3.3 m deep is located under the machine room. The reference mark at the turbine maintenance level is 9 m above the floor of the condenser room. The machine room is equipped with two overhead cranes, with load capacities of 75 and 20 tons.

The structures of a machine room are made from prefabricated reinforced concrete in the form of two longitudinal rows of columns that support the roof and the structures for the overhead cranes. Machine rooms located in southern regions are often of open construction. In the machine room of the standard GRES-600 state regional electric power plant (four turbine units of 150 MW each), only the area of the condenser room is enclosed (up to the reference mark at the maintenance level of the turbine unit). A gantry crane is used to install equipment in open machine rooms.

The machine rooms of gas-turbine and diesel power plants are the basic parts of the main building, where all operating equipment, such as gas turbines, diesels, current generators, compressors, starting motors, and combustion chambers, is located.

In hydroelectric power plants the machine room is the superstructure of the powerhouse. In hydroelectric power plants with vertical generators, the machine room contains the hydraulic generators or only the upper part of their superstructure, as well as the speed governor column and oil pan, the control boards for hydraulic units, and equipment for automatic control and regulation. In hydroelectric power plants with horizontal generators, the machine room also contains hydraulic turbines and their regulating devices. In pumped-storage hydroelectric power plants with a three-machine system, turbine-generator-pump units are installed in the machine room. If a two-machine system is used, two reversible hydraulic units are installed. A machine room may be full-size, with an interior overhead crane, or of semiopen or sunken construction, with an exterior main crane. Some hydraulic power plants, whose hydraulic generators are located outdoors, do not have machine rooms.

The height and width of a full-size machine room depend on the requirements for assembly, disassembly, and transportation of the equipment. The length of machine room in a hydraulic power plant depends on the number and dimensions of the units, on the distance between units, and on the overall dimensions of the erection site. For example, the machine room of the Krasnoiarsk Hydroelectric Power Plant, the largest in the world, has 12 units with a rated power of 508 MW each, with radial-axial turbines; the machine room is about 330 m long, 30 m wide, and 20 m high.