As it name indicates cogeneration works on concept of producing two different form of energy by using one single source of fuel. Out of these two forms one must be heat or thermal energy and other one is either electrical or mechanical energy. Cogeneration is the most optimum, reliable, clean and efficient way of utilizing fuel. The fuel used may be natural gas, oil, diesel, propane, wood, bassage, coal etc. It works on very simple principle i. In conventional power plant, the fuel is burnt in a boiler , which in turn produces high pressure steam. This high pressure steam is used to drive a tribune, which is in turn is connected to an alternator and hence drive an alternator to produce electric energy. The exhaust steam is then sent to the condenser, where it gets cool down and gets converted to water and hence return back to boiler for producing more electrical energy. The efficiency of this conventional power plant is 3. The cogeneration plant has high efficiency of around 8. In India, the potential of power generation from cogeneration plant is more than 2. MW. The first commercial cogeneration plant was built and designed by Thomas Edison in New York in year 1. It means with cogeneration the fuel utiliuzation is more efficient and optimized and hence more economical. Need for Cogeneration. Cogeneration helps to improve the efficiency of the plant. Cogeneration reduce air emissions of particulate matter, nitrous oxides, sulphur dioxide, mercury and carbon dioxide which would otherwise leads to greenhouse effect. It reduces cost of production and improve productivity. Cogeneration system helps to save water consumption and water costs. Cogeneration system is more economical as compared to conventional power plant. Types of Cogeneration Power Plants. In a typical Combined heat and power plant system there is a steam or gas turbine which take steam and drives an alternator. A waste heat exchanger is also installed in cogeneration plant, which recovers the excess heat or exhaust gas from the electric generator to in turn generate steam or hot water. There are basically four types of topping cycles. The steam so produced in a boiler is used to drive turbine and hence synchronous generator which in turn produces electrical energy. The exhaust from this turbine can be either used to provide usable heat, or can be send to a heat recovery system to generate steam, which maybe further used to drive a secondary steam turbine. Steam- turbine topping CHP Plant- In this the fuel is burned to produce steam, which generates power. The exhaust steam is then used as low- pressure process steam to heat water for various purposes. Water- turbine topping CHP Plant- In this type of CHP plant a jacket of cooling water is run through a heat recovery system to generate steam or hot water for space heating. Gas turbine topping CHP plant- In This topping plant a natural gas fired turbine is used to drives a synchronous generator to produce electricity. The exhaust gas is sent to a heat recovery boiler where it is used to convert water into steam, or to make usable heat for heating purposes. Bottoming cycle power plant - As its name indicate bottoming cycle is exactly opposite of topping cycle. In this type of CHP plant the excess heat from a manufacturing process is used to generate steam, and this steam is used for generating electrical energy. In this type of cycle no extra fuel is required to produce electricity, as fuel is already burnt in production process. Molten- carbonate fuel cells have a hot exhaust, very suitable for heating. Combined cycle power plants adapted for Combine Heat and Power. Cogeneration - Wikipedia, the free encyclopedia. Cogeneration or combined heat and power (CHP) is the use of a heat engine. Trigeneration or combined cooling, heat and power (CCHP) refers to the simultaneous generation of electricity and useful heating and cooling from the combustion of a fuel or a solar heat collector. Cogeneration is a thermodynamically efficient use of fuel. In separate production of electricity, some energy must be discarded as waste heat, but in cogeneration some of this thermal energy is put to use. All thermal power plants emit heat during electricity generation, which can be released into the natural environment through cooling towers, flue gas, or by other means. In contrast, CHP captures some or all of the by- product for heating, either very close to the plant, or. This is also called combined heat and power district heating (CHPDH). Small CHP plants are an example of decentralized energy. At smaller scales (typically below 1 MW) a gas engine or diesel engine may be used. Trigeneration differs from cogeneration in that the waste heat is used for both heating and cooling, typically in an absorption refrigerator. CCHP systems can attain higher overall efficiencies than cogeneration or traditional power plants. In the United States, the application of trigeneration in buildings is called building cooling, heating and power (BCHP). Heating and cooling output may operate concurrently or alternately depending on need and system construction. Cogeneration was practiced in some of the earliest installations of electrical generation. Before central stations distributed power, industries generating their own power used exhaust steam for process heating. Large office and apartment buildings, hotels and stores commonly generated their own power and used waste steam for building heat. Due to the high cost of early purchased power, these CHP operations continued for many years after utility electricity became available. In most heat engines, a bit more than half is lost as excess heat (see: Second law of thermodynamics and Carnot's theorem). By capturing the excess heat, CHP uses heat that would be wasted in a conventional power plant, potentially reaching an efficiency of up to 8. This means that less fuel needs to be consumed to produce the same amount of useful energy. Steam turbines for cogeneration are designed for extraction of steam at lower pressures after it has passed through a number of turbine stages, or they may be designed for final exhaust at back pressure (non- condensing), or both. A typical back pressure may be 6. MPa). In practice these pressures are custom designed for each facility. The extracted or exhaust steam is used for process heating, such as drying paper, evaporation, heat for chemical reactions or distillation. Steam at ordinary process heating conditions still has a considerable amount of enthalpy that could be used for power generation, so cogeneration has lost opportunity cost. Conversely, simply generating steam at process pressure instead of high enough pressure to generate power at the top end also has lost opportunity cost. The 4. 5MW boiler uses waste wood biomass as energy source, and provides electricity and heat for 3. Some tri- cycle plants have used a combined cycle in which several thermodynamic cycles produced electricity, then a heating system was used as a condenser of the power plant's bottoming cycle. For example, the RU- 2. MHD generator in Moscow heated a boiler for a conventional steam powerplant, whose condensate was then used for space heat. A more modern system might use a gas turbine powered by natural gas, whose exhaust powers a steam plant, whose condensate provides heat. Select Energy 15MW COGENERATION. The co-generation plant consists. Power Systems Services. Tri- cycle plants can have thermal efficiencies above 8. The viability of CHP (sometimes termed utilisation factor), especially in smaller CHP installations, depends on a good baseload of operation, both in terms of an on- site (or near site) electrical demand and heat demand. In practice, an exact match between the heat and electricity needs rarely exists. A CHP plant can either meet the need for heat (heat driven operation) or be run as a power plant with some use of its waste heat, the latter being less advantageous in terms of its utilisation factor and thus its overall efficiency. Trigeneration or combined cooling, heat and power (CCHP), is the process by which some of the heat produced by a cogeneration plant is used to. ENERGY FROM BIOMASS AND WASTES XIV. The viability can be greatly increased where opportunities for Trigeneration exist. In such cases, the heat from the CHP plant is also used as a primary energy source to deliver cooling by means of an absorption chiller. CHP is most efficient when heat can be used on- site or very close to it. Overall efficiency is reduced when the heat must be transported over longer distances. This requires heavily insulated pipes, which are expensive and inefficient; whereas electricity can be transmitted along a comparatively simple wire, and over much longer distances for the same energy loss. A car engine becomes a CHP plant in winter when the reject heat is useful for warming the interior of the vehicle. The example illustrates the point that deployment of CHP depends on heat uses in the vicinity of the heat engine. Thermally enhanced oil recovery (TEOR) plants often produce a substantial amount of excess electricity. After generating electricity, these plants pump leftover steam into heavy oil wells so that the oil will flow more easily, increasing production. TEOR cogeneration plants in Kern County, California produce so much electricity that it cannot all be used locally and is transmitted to Los Angeles. The exhausted steam is then condensed and the low temperature heat released from this condensation is utilized for e. Bottoming cycle plants are only used when the industrial process requires very high temperatures such as furnaces for glass and metal manufacturing, so they are less common. Large cogeneration systems provide heating water and power for an industrial site or an entire town. Common CHP plant types are: Gas turbine CHP plants using the waste heat in the flue gas of gas turbines. CHP PLANTS FOR CITIES AND INDUSTRIES – BENEFICIAL FOR THE ECONOMY AND THE ENVIRONMENT Harald Dichtl, Business Development Manager, Siemens Power Generation.The fuel used is typically natural gas. Gas engine CHP plants use a reciprocating gas engine which is generally more competitive than a gas turbine up to about 5 MW. The gaseous fuel used is normally natural gas. These plants are generally manufactured as fully packaged units that can be installed within a plantroom or external plant compound with simple connections to the site's gas supply, electrical distribution network and heating systems. SELECTION CONSIDERATIONS OF COMBINED CYCLES AND COGENERATION PLANTS Gas (combustion) turbine research performed in the 1970s hinted that high pressure ratios. Tuapse - cogeneration of electricity and steam. One of the most recent contracts signed by Siemens Energy is once again with the Russian oil and gas company Rosneft. Cogeneration or combined heat and power (CHP) is the use of a heat engine or power station to generate electricity and useful heat at the same time. Cogeneration Case Studies Handbook. 2 The sole responsibility for the contents of this. COGENERATION OF HEAT AND POWER – HACHP (EL) Costas Theofylaktos. A New Concept to Designing a Combined Cycle Cogeneration Power Plant Dr. Leonid Moroz –Presenter, Dr. Cogeneration and District Heating Page 3 of 7 Reciprocating engines cogeneration systems Cogeneration systems based on reciprocating engines are similar to those. Typical outputs and efficiences see . The advantage of using a biofuel is one of reduced hydrocarbon fuel consumption and thus reduced carbon emissions. These plants are generally manufactured as fully packaged units that can be installed within a plantroom or external plant compound with simple connections to the site's electrical distribution and heating systems. Another variant is the wood gasifier CHP plant whereby a wood pellet or wood chip biofuel is gasified in a zero oxygen high temperature environment; the resulting gas is then used to power the gas engine. Typical smaller size biogas plant see . With a heating system temperature of 9. With a temperature of 1. The heat is removed from the exhaust and radiator. The systems are popular in small sizes because small gas and diesel engines are less expensive than small gas- or oil- fired steam- electric plants. Some cogeneration plants are fired by biomass. Some CHP plants utilize waste gas as the fuel for electricity and heat generation. Waste gases can be gas from animal waste, landfill gas, gas from coal mines, sewage gas, and combustible industrial waste gas. The installation is usually less than 5 k. We in a house or small business. Instead of burning fuel to merely heat space or water, some of the energy is converted to electricity in addition to heat. This electricity can be used within the home or business or, if permitted by the grid management, sold back into the electric power grid. Delta- ee consultants stated in 2. With a Lifetime of around 6. For PEM fuel cell units, which shut down at night, this equates to an estimated lifetime of between ten and fifteen years. One author indicated in 2. Micro. CHP based on Stirling engines is the most cost effective of the so- called microgeneration technologies in abating carbon emissions. Cogeneration systems linked to absorption chillers use waste heat for refrigeration. The peak delivery is 1. GW). This is more valuable and flexible than low- grade waste heat, but there is a slight loss of power generation. The increased focus on sustainability has made industrial CHP more attractive, as it substantially reduces carbon footprint compared to generating steam or burning fuel on- site and importing electric power from the grid. Utility pressures versus self generating industrial. Among the reasons are: 1) Cogeneration plants face possible contamination of returned condensate. Because boiler feed water from cogeneration plants has much lower return rates than 1. Boiler feed water must be completely oxygen free and de- mineralized, and the higher the pressure the more critical the level of purity of the feed water. Utilities are less likely to have sharp load swings than industrial operations, which deal with shutting down or starting up units that may represent a significant percent of either steam or power demand. Heat recovery steam generators. The steam, in turn, drives a steam turbine or is used in industrial processes that require heat. HRSGs used in the CHP industry are distinguished from conventional steam generators by the following main features: The HRSG is designed based upon the specific features of the gas turbine or reciprocating engine that it will be coupled to. Since the exhaust gas temperature is relatively low, heat transmission is accomplished mainly through convection. The exhaust gas velocity is limited by the need to keep head losses down. Thus, the transmission coefficient is low, which calls for a large heating surface area.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. Archives
December 2016
Categories |