General History of Component Facilities
Socha (1989) and Domalowsky (1985) provide thorough and fascinating accounts of the development of the Krakow system. These are summarized below by general product of the system components.Coal Gas Coal gas production in Krakow was begun in 1857 by a German firm under a 25-year contract with the city government. Some 15.5 miles (23 km) of distribution lines were built to carry the gas to the central market area in downtown Krakow, the "Rynek." In 1883 the city began to take over the system and finally purchased it completely in 1886. A year later the city built its own production plant at Dajwor Street. It supplemented the Rynek system but also provided 30% of its production for street and public building lighting. In 1968, coal gas production by the Krakow district system was discontinued (Socha 1989).
Electricity The first Polish city to have electricity was Przemysl, in 1895, in the Austrian-controlled area. Warsaw, then in the Russian-controlled area, did not begin electrification until 1902. The Krakow region's first electrical generation plant was built in 1900 in the town of Podgorze. Several buildings in the Krakow area also installed their own private generators over the next few years (Domalowsky 1985).
The city solicited bids for construction of a municipal generating plant and in 1905 built a plant fired with coal gas at the Dajwor Street site, expanding it from 4.5 MW initially to a 7.5-MW capacity by 1921. At that time it supplied three-phase AC current to the electrical distribution system. Due to the plant's limited capacity, electric rates were set lower for off-peak use (Domalowsky 1985).
By 1906, 28,758 light bulbs were lit in Krakow. In 1912 the system converted from DC to 50-Hz AC current, permitting transmission of current over greater distances and major expansion of the distribution system. The AC distribution system also required less copper. Copper was then critical to Austria's preparations for war, and Vienna demanded that Krakow dismantle its electrical distribution system and turn over the copper. Krakow, however, was able to stall until the end of the war, keeping the system intact (Domalowsky 1985).
From 1913 to 1930 Krakow contracted with plants established in the neighboring communities of Sierszy and Jaworzno for supplemental supply to meet growing demand (Domalowsky 1985). In 1939 an industrial power station was built in Solway at the sodium hydroxide and allied chemical productichi complex (Socha 1989). Following World War II, industrial power plants were reactivated at the Wieliczka salt mines and at the Solway plant.
In 1976 Krakow's largest electrical power plant was built at Skawina. Its coal-fired boilers drive turbine generators that have a total electrical energy capacity of 550 MW. It also has a separate 70-MW thermal energy capacity for high-temperature hot water production for the central distribution loop.
Additional electrical and thermal capacity was still required. In 1977 electric generators were installed at the Leg district heating plant. In an effort to improve plant fuel efficiency, cogeneration technology was employed. Its electrical generation capacity is 450 MW. The Leg plant and its cogeneration system are discussed in detail below.
The Krakow regional plants supply electricity to the national grid, stepped up from 15 kV to 400/220/110 kV (Domalowsky 1985). The total electrical capacity is 1,000 MW. Krakow draws power from the grid in periods of high demand and supplies surplus power at other times. The Polish national grid is also connected to those of neighboring countries.
Steam and Hot Water Heating In 1912 a system was established to distribute steam for heating and industrial processes. Construction of a hot water distribution system was begun in 1919, but large-scale development did not begin until 1950. Boiler houses were built then in Krakow and Nowa Huta. In 1955 and 1956, several plants were built at the Lenin Steel Works in Krakow. They produced process heat for the foundries and hot water to heat the new residential districts constructed near the industrial complex. In 1960 the Dajwor Street power station was converted to a thermal and electrical power plant, producing residential heat and power and supplying process steam to the nearby meat processing plants (producer of the famous "Krakus" hams). The Dajwor station continued its thermal operation until 1984.
In 1970 the 1,449-MW Leg (pronounced "Wang") thermal power plant began operation to supply high-temperature hot water to the district heating system. A 70-MW thermal energy plant was included during the Skawina plant's construction in 1976 to supply heat to the district heating system in addition to the 550 MW of electricity supplied to the regional grid. In 1976 the Solway plant began to supply up to 19 MW of high-temperature hot water to the central heating system. Jerzy Socha reports that in January 1991 the Solway chemical plant complex ceased manufacturing operations, but that its process heating plant continues to operate and supplies its entire output to the district heating system.
The energy of the hot water from the distribution loop is supplied to users, mainly in the residential sections of the city, through the heat exchangers of each building's hot water heating systems and ultimately to radiators or process equipment (Socha 1989).
District Heating Cooperative In 1953 several heating plants were consolidated under the district heating cooperative that now serves the Krakow region. These included four heating plants in Krakow and seven in Nowa Huta. Various expansions and additions were made to the system, including those at the Lenin Steel Works. In the late 1950s the electrical power stations were brought under the cooperative's control. In 1961 the district heating system was named the Miejskie Przedsiebiorstwo Energetyki Cieplnej (MPEC), the "Local Thermal Energy Cooperative." It consisted then of 140 local and regional boiler houses and 106 miles (170 km) of distribution lines (Socha 1989). Boiler houses range in thermal energy capacity from 1/4 MW to 50 MW, with an average size of 1 MW. Today 30% of the thermal energy produced by the district is supplied to industry for technological processes (Socha 1989).
No Nuclear Power Plants There are no nuclear power plants in Poland and plans to develop one in Krakow have been suspended as a result of the Chernobyl incident and other considerations (Socha 1989). Municipal planning for energy management and air pollution control improvememts have necessarily turned toward the coal-fired central plants, the central distribution system, and household heating systems.
Overall System Capacity Today The Krakow region has a peak electrical power denund of 1,100 MW, which is supplied by local plants and from the national grid. The region has a total capacity of 3,766 MW of thermal power production capacity, including all sources. The estimated 200,000 private boilers and furnaces contribute approximately 631 MW of this capacity; most are coal-fired (Socha 1989).
The Leg Power Station
Schematic of Leg cogeneration plant.
The Leg power station was opened in 1970 as the largest thermal energy plant supplying high-temperature hot water for the district heating system. It replaced the Lenin Steel Works plant as the main supplier to the district. In 1977 a cogeneration system was added for production of electricity, industrial process steam, and hot water. Plant expansion continued through 1985.
The Leg plant has a combined electrical generation capacity of 450 MW. It produces high-temperature hot water at 311 F (155 C) for the central district heating system. Its total thermal energy capacity is 1,449 MW, 39% of the total 3,766-MW capacity available to Krakow. The plant primarily burns pulverized bituminous coal. Flue gases, following particulate emissions removal in electrostatic precipitators, is exhausted through two chimneys designed for high-altitude gas dispersal, 738 feet (225 meters) and 853 feet (260 meters) high, respectively. It employs 200 operating personnel and is supported by 1,600 personnel in auxiliary maintenace, supply, and distribution units.
The Leg plant's equipment was manufactured in Poland, including the steam and hot water boiler, turbines, and generators. Its cycle begins with high-pressure steam boilers, two at 380 tons of steam per hour and two more at 430 tons per hour, which supply steam at 1,004 F (540 C) and at 2,029 psi (138 atmospheres pressure) to the steam turbines. The turbines drive generators that have a total capacity of 450 MW. The high-pressure steam is also supplied to industry for process use. The heat from the low-pressure steam that leaves the condensing turbines is transferred through heat exchangers to the high-temperature hot water system to supply the central district heating and industrial process distribution system. If necessary, the turbine exhaust steam can be condensed in condensers using water from the Wisla River. This can happen, for example, when the demand load on the district heating system is low, electrical generation demand is high, and the return water is too hot for efficient heat exchanger operation.
The return water from the distribution system enters the plant's heat exchangers at about 167 F (75 C) and leaves at 230 F (110 C). Should district load and demand require, it can be heated to 311 F (155 C) by six supplemental high-temperature water boilers, which are connected in parallel to the main distribution supply loop. The water at this temperature is under a pressure of 368 psi (25 atm). Plant expansion plans include an additional steam boiler and an additional high-temperature water boiler.
Forty-three percent of the total thermal energy produced for the main distribution loop of the district heating system is generated at the Leg station by the cogeneration process. The cogeneration system allows the plant to operate around the clock because surplus electrical production is diverted into the national distribution net and sold to other regions of Poland and to neighboring countries.
The Leg plant is designed to meet the thermal loads of the area, which includes Krakow, Skawina, and Wieliczka. Its 1,449-MW thermal capacity is supplemented from the heating plants at Skawina, the Lenin Steel Works, and Solway. The Leg and Skawina plants supply a majority of the region's electrical load.