Tušimice II Power Plant
The coal-fired power plant with four 200 MW units commenced its operation in 1974–1975. Like the first, now already demolished power plant Tušimice I, it was built right next to a fuel source, the Nástup Tušimice Mines, from where fuel is transported by belt conveyors right to the boiler house. The power plant also delivers heat to customers in its vicinity, supplying heat to the town of Kadaň. The annual total of heat delivered to customers is about 750 TJ at maximum heat output of 85 MWt. Its installed capacity for heat delivery is 120 MWt.
Between 2007 and 2012 the Tušimice II power plant underwent impressive overall renewal, which will ensure its future operation in line with the current European standards until about 2035, when the adjacent Libouš mine is expected to be exhausted. The power plant’s efficiency increased by 6 %, saving 14 % of fuel per MWh produced. The upgraded plant will allow burning lower quality fuel from the Libouš mine in the future. The flue gas desulphurization (FGD) equipment constructed in 1994–1997 was upgraded as well. Now it is ready to meet the strictest emission limits after 2016. The emissions of nitrogen oxides could be decreased by 70 %, sulphur dioxide by 79 % and dust by 87 %. (However, the power plant underwent its first ecologization in the 1990s when its emissions were decreased by more than 90 per cent!) Power plant byproducts (fly ash, slag and FGD gypsum) originated in the Tušimice II Power Plant are certified deposit products. The deposit products are used for landscape revitalisation after mining. The comprehensive renewal worth CZK 26 billion also helped overcome the economic crisis in the region, while an operation extension of 25 years will allow preserving thousands of jobs.
Output transformers transform the input voltage of 15.75 kV coming from the generator to an output voltage of 400 kV. The transformers are connected through circuit breakers to output lines connected to a substation in Hradec near Kadaň.
Central control room
The control rooms manages all four generation units and most shared facilities.
Area in front of the unit control room
A view of the turbine hall through a glass noise barrier.
The turbine building contains 4 turbine units with a capacity of 200 MW each.
The Škoda condensing steam turbines located in the turbine building have three casings with the high-pressure, medium-pressure and low-pressure parts. A Siemens generator is installed on the common shaft. The turbine is driven by steam. Steam heated to 575 °C and pressurized to 18.1 MPa enters the high-pressure part first, then returns back to the boiler where it is reheated to 580 °C but under a lower pressure of 3.9 MPa, spins the turbine blades again and flows directly to the low-pressure part and from there to a condenser. The turbine rotates at 3,000 revolutions per minute, i.e. 50 revolutions per second.
A condenser consists of 17,096 thin tubes with cooling water from the cooling towers flowing inside, cooling supplied steam to condense it back to the liquid state. Heated cooling water returns to the cooling towers.
First and second stage condensate pumps push water through five low-pressure heaters to the feed tank and with the help of feed pumps back to the boiler.
The low-pressure heaters take some steam from all parts of the turbine to heat the condensate. Some steam is also delivered from the turbine to heaters that heat service water for supplying heat to Kadaň.
After a shutdown, when boilers are re-ignited, feed water is transported to the boiler using two feeding pumps driven by electric motors (electric feeders). In operation, feed water is transported to the boiler by one feeding pump that is driven by the steam turbine (turbine feeder). This arrangement improves operation economy as it decreases the internal consumption of electricity.
Under the condensers
The cellar of the turbine building that contains the intakes of various pumps, pipe discharges, summer coolers and low-pressure heater subcoolers.
Lower part of the boiler house
Draws hot flue gases from the boiler, to which coal falls. This dries the coal, which is pulverized in the grinding equipment of the mill. The powder is blown by the fan mill through a pulverized coal burner to the boiler for burning. Each boiler has 6 fan mills. The mill wheel is driven by an electric motor through a fluid clutch (used to start up the mill and control its speed) and a gear box. Its rated speed is 576 rpm. Under full load, the boiler burns up to 200 t of coal per hour.
The blue-painted metal-clad part is the boiler’s hopper where slag falls into a water trap. Slag is then transported by chain slag removers to a slag breaker and then by screw and bellows slag removers to a trough screw conveyor. Slag then falls to a belt conveyor and is transported to slag silos.
At the highest level of the boiler house, at 52 metres, you can find the boiler top, air fan intake and outgoing steam lines. The air fan intake draws in air and uses it to support burning in the combustion chamber.
The temperature in the boiler / combustion chamber is about 1,100 °C. The boiler walls consist of tube diaphragm walls through which water and then steam flows. Water is turned into steam by heat generated in the combustion chamber first, then steam is reheated and finally transported by steam lines from the boiler to the turbine. Steam temperature is 575 / 580 °C. Steam temperature is controlled by injecting water into the steam.
Combustion generates slag, which falls by gravity to the boiler bottom from which it is removed by a system of conveyors and transported to storage silos. Flue gases containing fly ash flow into electrostatic precipitators.
View of the air fan intake and boiler room piping
The dark blue, metal-clad part is a boiler wall. There is a bypass station in front of the wall, which also serves as a safety valve of the superheater part of the boiler. The rated steam capacity of the boiler is 547 t/hr, its height is 53 m and the combustion chamber is 50 m high.
View of boiler suspension under the boiler room ceiling and adjacent steam pipes
The boiler, including its steam pipes, is suspended from the boiler house structure by adjustable rods and brackets. This arrangement allows the boiler to dilate vertically.
On the boiler house roof
The boiler house roof is 60 m above ground. It includes safety valves outlets of the boilers’ pressure systems and equipment for heating air on boiler house premises. The roof offers a view of a former, reclaimed ash disposal site, the Doupov Hills, the Ore Mountains and the two Prunéřov power plants.
View from the boiler house roof
To the right of the cooling towers, you can see the parallel lines of the incrementally raised dam of a fly ash disposal site that is reclaimed today. On the left, under the Ore Mountains range, you can see the cooling towers of the Prunéřov coal-fired power plant and the edge of an open coal pit. Next to the site of the Tušimice II power plant, towards Prunéřov, you can see a grassed area where the Tušimice I power plant used to be. It was in operation until the early 1990s; then all of its 6 units were shut down under a retirement plan. The power plant’s stack fell down in November 2005; it was the highest (196 m) reinforced concrete stack to be blasted at that time.
Above the smoke stacks
The rear wall of the boiler house with air intake ducts. You can see smoke stack inlets in electrostatic precipitators under the footbridge.
Above the electrostatic precipitators
Electrostatic precipitators contain discharge and collection electrodes supplied with high voltage. Precipitator chambers consist of three sections. The first section captures the largest ash particles; the last section captures the finest dust particles. Flying ash is electrically charged on discharge electrodes and then drawn by the electrostatic force to suspended plate electrodes charged with the opposite charge. As the rotating hammers of rappers periodically strike the collection plate electrodes, ash falls down to pressure receivers and is removed to fly ash silos pneumatically.
Flue gases flow from the electrostatic precipitators to the flue gas desulphurization (FGD) unit to be additionally cleaned. The contents of flue gases is monitored constantly, checking the amount of sulphur oxides, dust, carbon oxides and nitrogen oxides.
Area under the electrostatic precipitators
The top part includes the hoppers of the individual sections of the electrostatic precipitators, with the ash collecting pressure receivers beneath. When they are full, pressure air is supplied to the receivers to blow the ash to the fly ash silos.
The flue gas desulphurization system uses the limestone wet scrubbing method. Pulverized limestone is mixed with water to form limestone suspension. Five circulating pumps suck the suspension and spray it at five spraying levels in the absorber. Flue gases flow from below and sulphur dioxide contained in them reacts with limestone to form gypsum suspension. Cleaned (desulphurized) flue gases flow into the smoke stack; the formed gypsum suspension is collected from the bottom of the absorber and transported for drying.
Above the smoke stacks II
The smoke stacks for clean and desulphurized flue gases are made of fibreglass. The smoke stacks were manufactured on site at the cooling towers. They are about 6 metres in diameter; their wall is up to 20 cm thick at some points. Cleaned flue gases are transported to cooling towers.
Slag and fly ash silos. The deposit belt conveyor begins in front of the fly ash silos where FGD gypsum is poured onto it. Moistened fly ash is added in between the fly ash silos and finally slag is added behind the slag silos. The deposit is transported to the extracted pits of the neighbouring open-cut mines.
Warmed cooling water from the condensers is transported to the cooling tower, where it is sprayed at about 30 m and cooled by a flow of outside air drawn in from below. Water droplets fall into the collection basin and cooled water returns to the condensers. Some water evaporates in the process, rising as a plume above the cooling towers. Cleaned flue gases are transported by smoke stacks to cooling towers 1 and 3.
Inside a cooling tower
The cooling tower interior consists of 30 m high eliminators, which prevent excessive water evaporation. A distribution system for warmed cooling water is located under the eliminators.
Wastewater settling tank
A 4,000 m3 intercepting trap for aggressive waste is used to hold all wastewater during a shutdown, discharging wastewater from the central fly ash mixing plant for up to three days when 4 units run at their rated capacity.
Cooling water pumping station
The cooling water pumping station includes 4 cooling pumps that keep water circulating between the turbine condensers and the cooling towers. It also includes pumps for the fire-fighting water distribution system and filtration plant.
Lower part of the cooling water pumping station
The cellar of the cooling water pumping station, with 4 cooling pumps and the cooling water make-up inlet.
Gypsum drying hall
The hall is equipped with three drying vacuum lines, with a set of hydrocyclones above each of them (separating 41 % of water from the gypsum suspension). Suspension with FGD gypsum collected from the absorber is spread over a long rubber belt which is vacuumed from below. FGD gypsum has 15 % residual humidity at the end of the drying line.
View from the top of a yard machine to the reserve coal stockyard
There are 3 yard machines at the reserve coal stockyard: 1 tripper car and 2 gantry loaders.
Reserve coal stockyard
The reserve stockyard has a capacity of 120,000 tonnes of coal and is intended to be used in case of suspension of direct fuel deliveries from Severočeské doly. The amount will suffice for about a week of power plant operation. Coal at the stockyard is constantly compacted by bulldozers and must be replaced regularly to minimize the risk of ignition.
View from the roof of the coaling control room
To the right of the reserve coal stockyard is a siding for limestone transport, the cooling towers and the FGD plant. In the background you can see the boiler house with enclosed coaling belts connecting to it on the right. The empty space to the right of the boiler house is where the former Tušimice I power plant used to be. The site of our neighbour, Severočeské doly, can be seen behind the reserve coal stockyard.
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