Electrical energy at cost. Gas turbine plant for an industrial enterprise
Currently, there are several thousand thermal power plants and state district power plants in Russia, as well as more than 66 thousand boiler houses, which provide almost 80% of the generated heat. In this regard, Russia is the undisputed world leader in terms of volumes of centralized heat supply. Let us note that in terms of centralization, Russia is a world leader not only in the field of energy. However, experts note the inefficiency of using gas on outdated units, as well as the low level of efficiency of traditional steam power turbines, which does not exceed 38%. In centralized networks, heat is produced mostly using equipment of previous generations, while excess heat “warms” the air.
Gas turbine installationThe use of local systems for the production of electrical and thermal energy using gas turbine power plants (GTU) running on natural gas or propane is one of the possible solutions to this problem. In this regard, there has been a trend toward the construction of decentralized combined sources of electricity and heat supply (the so-called cogeneration mode), installed both in existing heating boiler houses and in newly constructed heat sources.
The most urgent is the transition to new small facilities using modern gas turbines that provide cogeneration.
In developed countries, the share of small-scale energy installations with a cogeneration cycle is increasing, which allows optimizing the production of heat and electricity in social and industrial infrastructure, as well as ensuring effective energy saving. For example, in the USA and Great Britain the share of cogeneration in small-scale energy reaches 80%, in the Netherlands – 70%, in Germany – 50%. Abroad, this process is actively supported by the state both through legislative regulation and through budget financing.
The basis for the economic efficiency of gas turbine cogeneration power plants is their high electrical and thermal efficiency, achieved through the basic mode of their operation on thermal consumption (heating, hot water supply, heat supply for production needs). Gas turbine units have now received recognition in the energy sector as fully developed, reliable equipment. The performance indicators of gas turbine units in power plants are at the same level as traditional power equipment. They are characterized by readiness for operation within 90% of the calendar time, a 2-3 year repair cycle, and a trouble-free start-up rate of 95-97%.
Low specific weight, compactness, ease of transportation and ease of installation are some of the main advantages of gas turbine units, the most attractive from the point of view of their use. The advantages of gas turbines also include short construction times, increased reliability of heat and power supply to consumers, minimal volumes of harmful emissions into the environment, reduced inertia of thermal regulation and losses in heating networks relative to networks connected to large distribution systems and thermal power plants.
Description of gas turbine technology.
The basis of the gas turbine is a gas generator, which serves as a source of compressed hot combustion products to drive a power turbine. The gas generator consists of a compressor, a combustion chamber and a compressor drive turbine. The compressor compresses atmospheric air, which enters the combustion chamber, where fuel (usually gas) is supplied to it through nozzles, then the fuel is burned in the air flow. Combustion products are supplied to the compressor turbine and power turbine (in the single-shaft version, the compressor and power turbine are combined). The power developed by the power turbine significantly exceeds the power consumed by the compressor for air compression, as well as overcoming friction in the bearings and the power expended on driving auxiliary units.
Gas turbine unit The difference between these values represents the useful power of the gas turbine unit. A turbogenerator (electric generator) is located on the turbine shaft. The gases exhausted in the gas turbine drive go through the exhaust device and the silencer into the chimney. It is possible to recover heat from exhaust gases when the exhaust gases enter a waste heat boiler, which generates thermal energy in the form of steam and/or hot water.
Steam or hot water from the waste heat boiler can be transferred directly to the heat consumer. The electrical efficiency of modern gas turbine plants is 33–39%. However, taking into account the high temperature of exhaust gases in powerful gas turbine plants, it is possible to combine gas and steam turbines. This engineering approach can significantly improve fuel efficiency and increases the electrical efficiency of installations to 57–59%.
The advantages of gas turbine units are low specific weight, compactness, ease of transportation and ease of installation. It is allowed to install gas turbine units on the technical floor of a building or to install low-power gas turbine units on the roof. This useful property of gas turbines is an important factor in urban development. When operating gas turbine units, the content of harmful NOx and CO emissions in their exhaust gases is minimal. Such excellent environmental qualities make it possible to easily place gas turbine units in close proximity to human habitation. In addition, small-capacity gas turbine units are usually supplied in the form of one or several fully prefabricated units, requiring a small amount of installation work, and their relatively small size allows them to be installed in a cramped master plan. Hence the relative cheapness of construction and installation work.
Gas turbine installationGas turbine installations have minor vibrations and noise in the range of 65–75 dB (which corresponds on the noise level scale to the sound of a vacuum cleaner at a distance of 1 meter). As a rule, special sound insulation is not needed for such high-tech generating equipment. Modern gas turbine plants are highly reliable. There is evidence of continuous operation of some units for several years. Many suppliers of gas turbines carry out major overhauls of equipment on site, replacing individual components without transportation to the manufacturer, which significantly reduces the cost of servicing the unit. Most gas turbine plants have the ability to overload, i.e. increasing power above rated. This is achieved by increasing the temperature of the working fluid.
However, manufacturers impose strict restrictions on the duration of such modes, allowing operation above the initial temperature for no more than several hundred hours. Violation of these restrictions significantly reduces the resource of the installation. However, there are also difficulties when introducing power gas turbine units. This is, first of all, the need for preliminary compression of gas fuel, which significantly increases the cost of energy production, especially for small gas turbines, and in some cases is a significant obstacle to their implementation in the energy sector. For modern gas turbines with high degrees of air compression, the required fuel gas pressure can exceed 25-30 kg/cm2. Another significant disadvantage of gas turbine plants is the sharp drop in efficiency when the load decreases. The service life of gas turbine units is significantly shorter than that of other power plants and is usually in the range of 45-125 thousand hours.
Historically, the pioneers in the development of gas turbine technology were the creators of engines for ships and aircraft. Therefore, at present, they have accumulated the greatest experience in this field and are the most qualified specialists. In Russia, leading positions in the manufacture of gas turbine power plants are occupied by companies that develop and manufacture aviation gas turbine engines and gas turbine units created specifically for energy use.