Weiher Power Plant.

Transcription

1 Weiher Power Plant

2 Power and heat for the future Energy, for more than 90 years As fifth biggest electricity producer in, with ultramodern power plants in and outside and a variety of services, STEAG GmbH safeguards the energy supply of the future reliably, efficiently, and with low environmental impact. STEAG blazes the trail for the energy sources biomass, biogas, mine gas, geothermics, wind and solar thermics. The engineers of STEAG Energy Services GmbH develop, build and operate power plants all over the world and are experts for the modernization of existing plants and for made-tomeasure energy supply which goes easy on the climate and at the same time is economical. Power plants at home and abroad STEAG operates eleven power plants at ten locations in with an installed capacity of about 7,500 MW; nine of these plants use hard coal as primary energy source. At two sites, each of which integrates an industrial power plant, refinery by-products also are used to produce steam, compressed air and electricity. Most of the electricity from hard coal is supplied to industrial and public utilities. The customers include RWE, EnBW and Deutsche Bahn, the German Railways. Where there is a demand for it, cogeneration the simultaneous production of power and useful heat is practiced. This heat either is used for heating purposes or is purchased by industrial enterprises in the form of process heat for their production processes. Outside, too, the company contributes to public power supply with three hard-coal-fired power plants, capacity about 1,700 MW, in Turkey, Colombia and the Philippines. The efficient power plants of STEAG make an active contribution to a secure and sustainable supply of energy. With a total installed capacity of 724 megawatts, the Weiher III power plant in the town of Quierschied in the Saarland produces, besides electricity, district heating for the nearby community. In all, around 1.7 billion kilowatthours (kwh) of electricity and around 13 million kwh th of district heating are generated each year at the plant. The electricity could supply the needs of about 425,000 singlefamily households. The boiler in Weiher is a so-called outdoor boiler and therefore an unusual piece of architecture. In pure visual terms the outdoor boiler clearly sets the power plant apart from other plants, because it lacks an enveloping boilerhouse façade from about halfway up the boiler. Coal is delivered to the power plant by rail. The coal storage yard has a capacity of about 150,000 tons of coals. A fully automatic belt conveyor system transports the coal via holding bunkers in the boilerhouse to the six coal mills; it is then air-blast fed into the furnace in finely pulverized form. In an internal combustion engine which also belongs to the power plant, mine gas is burned and transformed into electrical energy and heat. Saar River water for power generation The make-up water for the cooling tower, through which some 60,000 cubic meters (m 3 ) of cooling water flow each hour, is pumped into the power plant through a 16-kilometer pipeline from the Saar River. The make-up water volume comes to about 1,000 m 3 per hour. Before the river water can be used, it is purified in a water treatment plant.

3 The power plant process The coal, as much as 6,000 tons per day, is shipped to Weiher by rail. From there it is transported to the coal mills. The mills pulverize the fuel, which is dried with hot air and then burned in the furnace at temperatures of about 1,200 C. During combustion, hot flue gas is formed. In kilometers of tubes in the steam generator, the flue gas heats water to make steam. The steam, which reaches a temperature of up to 530 C and is under high pressure, is conducted into a turbine where it impacts the turbine blades and causes the turbine shaft to rotate. A connected generator produces electricity from this motion, like a dynamo. Transformers bring the electricity up to the necessary voltage and feed it into the grid. When the steam has finished its work in the turbine it is conducted into a condenser. This is a large heat exchanger with many tubes in which cooling water circulates. The steam comes in contact with the tubes and forms droplets (condensation), much like humid air on a cold window pane. The condensed water droplets are collected and pumped back into the boiler to complete the cycle. In the process the cooling water from the condenser heats up from about 20 C to 30 C. It is piped into cooling towers where it cascades down and cools off again. A small portion evaporates and is replaced by water from the Saar River. Combined heat and power from Quierschied In addition to electricity, heat is produced in Weiher. At several points in the turbines, steam is extracted to heat water under pressure to a temperature as high as 180 C for district heating purposes. This water then is fed into the district heating supply system of the town of Quierschied. Protecting the environment Schematic illustration of the power plant process From the viewpoint of physics, energy is not produced, but merely transformed. The energy is fixed to the coal in chemical form. The coal is burned in the boiler; the released heat heats up water. This gives rise to hot steam (thermal energy) which drives a turbine (mechanical energy). A connected generator then transforms this mechanical energy into electricity (electrical energy). When coal is fired, flue gases form which contain mainly particles of ash, dust, nitrogen oxides and sulfur dioxide. For many years STEAG has been using highly effective methods to reduce the emissions of these substances. When a power plant is built today, a third of the expenditure goes into environmental protection, most of it into air pollution control. STEAG will make substantial investments in environmental protection in future too. The emissions of the power plant are continuously measured. The company s environmental protection officers monitor and evaluate the measurements. In addition they have independent bodies like the German inspecting authority TÜV make measurements. Noise control for the environment When planning the Weiher power plant, STEAG Power Saar made practical use of natural conditions to keep plant noises from reaching the neighboring community of Quierschied. The entire plant was nestled into the valley in such a way that it is surrounded by a natural protective wall. Cooling tower with flue gas discharge In Weiher, since 1988 flue gas which has been cleaned by DeNO x reactor, electrostatic precipitator and flue gas desulfurization plant is discharged into the cooling tower, where it rises up into the atmosphere together with the water vapor from the cooling tower. This saves energy, as the flue gas does not have to be reheated so that it can be discharged through the stack. Clean water The wastewater discharged by the power plant into the nearby Kohlbach brook is cleaner than the water extracted from the Saar River to operate the plant. Before it leaves the plant, all wastewater is subjected to intensive mechanical, chemical and biological treatment if required. Valuable by-products The STEAG subsidiary STEAG Power Minerals GmbH is responsible for recycling the by-products of all STEAG hardcoal-fired power plants in. Power plant by-products which originate in the firing process are valuable and are marketed. The by-products include fly ash, boiler sand, slag tap granulate and FGD gypsum. These power plant by-products are environmentally sound and can be used in almost all applications as construction materials without impairing the soil or groundwater. Treatment is only necessary in special cases. In contrast to the natural resources which are becoming increasingly scarce, power plant by-products will be available in the longer term, conserving natural raw materials.

4 Data and facts * Installed capacity Installed capacity 724 MW District heating capacity max. 30 MW th Steam generator Forced-circulation boiler simple reheat Single-pass boiler dry ash removal Steam flow at full load 2,100 t/h sliding-pressure operation Steam pressure 186 bar Steam temperature 525 C Annual coal consumption Useful electricity output District heating (heating supplied) Turbine unit Generator Main transformer Cooling tower Water vapor escaping from cooling tower Dust removal Flue gas desulfurization (FGD) about 630,000 t / 590,000 tce about 1.7 billion kwh / a about 13 million kwh th / a Four-cylinder condensing turbine HP inlet: 177 bar / 525 C IP inlet: 36 bar / 530 C LP inlet: 6 bar / 280 C Rated output: 800 MVA Generator rated voltage: 21 kv 2 50 %-duty transformers Rated output: 385 MVA each Rated voltage: 21 kv / 245 kv Natural-draft Height: 135 m Diameter at base: 100 m Water flow: 60,000 m 3 / h 1,500 m 3 / h 2 electrostatic precipitators Lime slurry scrubbing with ground limestone, gypsum as final product A site with a tradition NO x removal (DeNO x ) SCR system (Selective Catalytic Reduction) By-products Fly ash, boiler sand, gypsum Initial start-up 1976 Operator The Weiher power plant has a long tradition. It stands on the oldest power station site in the Saarland. In January 1918 the first plant at the Weiher site was put into operation in direct proximity to the Göttelborn coal mine. The Weiher I power plant followed in 1943 / In the 1960s the Weiher II power plant (put into service in 1963 / 1964) was regarded as a pioneering achievement in the field of environmental protection. The Weiher III pow- er plant (put into operation in 1976) continued to play this trailblazing role, boasting peak results for dust removal, and especially for desulfurization and NO x control. Moreover, in 1976 Weiher III was the first hard-coal-fired power plant in this capacity class in Europe. Whereas the older plants meanwhile have been taken out of service and dismantled, the unit Weiher III continues to generate power in environmentfriendly and reliable operation. Owner STEAG refers to the gross maximum capacity under nominal conditions as installed capacity. This is the continuous output that can be attained under normal conditions. It is limited by the weakest part of the plant (bottleneck), is determined by measurement and converted to normal conditions; stated in MW, calculated as MW electric and equivalent (thermal output). The standard coal equivalent or ton of coal equivalent (tce) is a commonly used unit of measure in Central Europe, though not a statutory unit of measure, to compare the energy content of primary energy sources. 1 ton coal equivalent = gigajoules (GJ) = thermal megawatt-hours (MWh th ). * as at December 31, 2011

5 STEAG GmbH Rüttenscheider Strasse Essen Phone Fax info@steag.com Trierer Strasse Saarbrücken Phone Fax info-powersaar@steag.com Weiher Power Plant Holzer Strasse Quierschied Phone Fax sekretariat-weiher@steag.com V-UK, as at June 2012