District heating in Warsaw

Parallel to the reconstruction of Warsaw, destroyed as a result of warfare, discussions were pending with regard to the future home heating system. Originally, in the Warsaw Reconstruction Office established in 1945 by the Homeland National Council, separate central heating systems were considered to be installed for every building and connected to a central network in the future. At the same time, in 1947 the idea of using heat produced by power plants was taken up. The Central Power Engineering Authority sent engineer Witold Szuman on a mission to learn about centralised heating system solutions used in other countries. As a consequence, the first concept of a municipal heating system covering the whole city emerged, but for many years it remained a project only.

 

For practical reasons – fast and simple installation and independence of external systems – in the first years of reconstruction most households used heating stoves. Shortly after 1948 the implementation of a project providing for construction of local heating stations commenced. According to plans six combined heat and power plants were to be built at the Vistula along with ten district heating stations. However, only a few local heating stations of 10-15 MWt were built and with time the concept of building combined heat and power plants was abandoned in favour of local boiler plants (as many as 950 were built by 1964).

 

 

The turning point for the development of district heating in Warsaw was 26 April 1952 when the Cabinet adopted a resolution concerning the implementation of district heating in the capital city based on combined energy management. At the first stage central heating networks were installed in the city centre and at the same time the Powioele Power Plant was adapted to generate heat. Also, the “Warsaw under Construction” District Heating Company (ZSC) was set up. It was in charge of investing and building and then operating district heating networks supplied from CHP plants. One of the factors determining an accelerated launch of remote heating in the centre of the capital city was the construction of the Palace of Culture and Science – a gift from the Soviets to the Polish nation. In order to heat the first skyscraper in Warsaw it was necessary to use technology which would not require a chimney to be built next to or installed on the top of the landmark edifice.

 

In October 1953 the first section of the district heating network was put into service in Drewniana, Bartoszewicza, Nowy Świat, Świętokrzyska and Emilii Plater Streets with a branch to the Palace of Culture and Science. A 3.5 km long section was commissioned on 10 April 1954 – heat was supplied to twenty large residential buildings and to the construction site of the Palace of Science and Culture. At the end of that year the company already heated buildings with a total cubic capacity of 1,200,000 m3. On the other hand, the National Council Presidium appointed a company called the Municipal Heating Stations in the Capital City of Warsaw to operate boiler plants in Warsaw.

 

On 22 January 1957 the “Warsaw under Construction” District Heating Company and the Municipal Heating Stations merged into one entity – the Capital Heating Company. The already 62 km long networks built in the past years enabled heat to be supplied to the districts of Śródmieście, Muranów and the Old and New Town. One of the most important investments in that period was the 8.6 km long Żerań main along Jagiellońska Street supplying heat to the newly built districts of Praga I and II.

 

In 1960 the Capital Heating Company merged with the Warsaw Heating Investments Company and the Capital Heat Supply Company (SPEC) was established. At that time the length of the district heating network was 140 km, and one of the most important network investments was put into service, namely a tunnel under the Vistula which was used to supply heat from Żerań to new districts in the north-western part of the city such as Żoliborz, Bielany, Młociny and Wola. Five years later the three CHP plants of Warsaw were combined into a single system. From that time Powiśle, Żerań and Siekierki CHP plants operated in a shared network.

 

Thanks to the development of the district heating system in Warsaw a definite majority of living quarters made use of central heating: in 1950 those were 18.5 % of the premises only followed by as many as 44.8 % in 1960 and 84.4 % in 1978. The most important suppliers of heat were CHP plants and the plant in Wola, but local plants were still in operation. The number of these smaller plants decreased yearly: in 1970 there were 662 such plants while at the end of 1979 there were only 390.

 

 

From 1967 Warsaw had to face the problem of thermal power shortage. The development of combined heat and power plants did not keep up with the growing needs of the city. In the late 1970s the shortage in heat supply was estimated at 20 % of available capacity. The situation became even worse because of disruptions in fuel deliveries due to a downturn in the centrally planned economy. The poor condition of district heating in Warsaw in the economic conditions of that time was directly manifested by cold refrigerators in thousands of apartments. SPEC attempted to solve the emerging problems on a current basis and, if possible, use modern technical solutions that, on the one hand, would reduce the failure rate of the infrastructure and, on the other, improve the effectiveness of heat supply.

 

As early as 1966 internal central heating installations and substations in the district heating system could be adjusted by the use of orifices. In 1969, in order to improve the conditions of supply to the newly built housing estates, a pumping station was put into operation at Rawska Street in the district of Wola. On the other hand, in the pumping station “Batory” in 1971 pumps with regulated speed of rotation (Cramer's system) were used for the first time and temperature control valves “Samson” and “Clorius” were put into service.

 

At the same time the corroded sections of ductless piping built in the previous years were replaced. From 1975 stainless steel plate exchangers were in use. In the following years methods were worked out to restore patency of internal central heating installations by flushing them with chemicals.

 

In 1977 JAD exchangers were put into service, the “Marymont” pumping station was launched and ground-based and overhead technology was used in the construction of networks. In 1980 for the purposes of fast identification of leaks in the district heating system colorants were added to service water and simultaneously infrared mapping methods were used for the first time. From 1986 SPEC used pipes with thicker walls. This decision was due to the poor quality of service water and high rate of failure, i.e. up to four failures per 1 km of the network in a year. By 1990 more than 300 km of pipes were replaced.

 

After the political transformations in Poland the whole district heating system had to be reformed in order to become adapter to the new market conditions. Major drawbacks that remained from the socialist economy were: highly energy-intensive technologies, lack of equipment for automatic control of the network, lack of stimuli to save heat energy and improper insulation materials used in construction – at least 30 % of heat was irretrievably wasted because buildings were not insulated. With regard to the new political and economic situation SPEC had to face a number of challenges. Over the past few decades the company has implemented a scheme of modernization of the district heating system in Warsaw, and undergone a number of transformations and changes in the structure of organisation and ownership.

 

Powiśle Combined Heat and Power Plant 

 

The first source of district heating for Warsaw was the Powiśle Power Plant with a capacity of 46 Gcal/h – following an adaptation of one turbine set to district heating needs. In 1952-1953 subsequent units were modernised and the target heating capacity of 230 Gcal/h was achieved in 1953. In 1957 a new backpressure heat turbine with a capacity of 103 Gcal/h (120 MWt) was put into service.

 

 

The plant operated in such a configuration for nearly twenty years. Only in the mid 1970s did modernisation involve disassembly of the plant's condensing turbine sets, leaving only two that were adapted for the purposes of district heating. In 1974 the construction of the Wisłostrada route necessitated liquidation of railway tracks on the bank of the Vistula – from that time fuel was transported by trucks. Every day up to 40 trucks carrying 25 tonnes of coal each arrived in the plant. High operating costs and burden on the environment reduced the role of the Powiśle CHP Plant to generating only such an amount of heat energy that was necessary for Śródmieście (central district of the city) and in addition during the heating season only.

 

In the last period of operation three turbine sets were in operation in the plant, including two heating turbines:

 

• Tz10: condensing turbine produced by Brown Boveri Compagnie, installed in 1937, in 1964 converted into a poor vacuum unit with attainable power of 100 MWt (1998);

• Tz11: condensing turbine produced by Brown Boveri Compagnie, installed in 1939, in 1975 converted into a poor vacuum unit with attainable power of 105 MWt (1998).

 

In the late 1990s a decision was made to close down the plant, replacing it with a pumping station for service water from the Siekierki CHP Plant. In 2001 SPEC put the “Nadbrzeżna” main into service, thus ensuring supplies of heat from the Siekierki CHP Plant to the entire centre of Warsaw. This enabled decommissioning of the oldest CHP plant in the city – the Powiśle CHP Plant.

 

Żerań Combined Heat and Power Plant

 

In 1949 a decision was made to build a header-type combined heat and power plant with the electric capacity of 150 MWe and thermal capacity of 520 MWt. Preliminary assumptions for the Żerań CHP Plant were developed by the Office of Energy Projects in Warsaw and the technical design was prepared by “Tieploprojekt” in Leningrad in 1951. Civil engineering works started in the very same year. The core equipment was imported from the Soviet Union. The first 25 MW turbine set put into service in November 1954 was initially used only to generate electricity. Production of heat energy commenced the following year. During the construction of the CHP plant the decision was made to develop a centralized heating system in Warsaw. Therefore, simultaneously preparatory works began to expand the plant. In total by 1962 the plant had installed seven steam boilers made in the USSR and nine turbine sets, of which six were made in the USSR, two in Poland and one in Czechoslovakia.

 

 

In 1968 and 1970 another steam boiler produced by RAFAKO and turbine set No. 10 with a backpressure turbine produced by Zamech were put into operation. At the same time, the first water boilers were installed. By 1975 four WP-120 water boilers were put into service. The plant generated 1,477 MWt of heat and 250 MWe of electricity. Hard coal is the basic fuel for boilers but originally gas was also used. It accounted for approximately 30% of chemical Energy contained in fuel fed to boilers. The State Inspectorate of Fuel and Energy Management in 1973 imposed a ban on the use of gas. The gas installation was dismantled only in part, which as it turned out later, excellently illustrated the rich imagination characteristic of power engineers from Żerań. At the beginning of January 1979, during a severe winter, gas firing of boilers could be temporarily restored. Thanks to this fact, despite very serious troubles with coal supplies, the production of heat and electricity could be maintained. Other CHP plants in Warsaw operating at that time, i.e. Siekierki and Powioele, had to discontinue generating heat for the city due to the lack of fuel.

 

 

In the 1980s and at the beginning of the 1990s many engineering processes in the CHP plant were modernized. First and foremost the flow systems of nine turbines were redesigned, which increased the attainable electric capacity to 290 MWe. Water boilers were fitted with combustion chambers with sheet pile walls. A new district heating make-up water preparation plant based on reverse osmosis was built. The refurbished district heating network was equipped with a new system of automatic control and adjustment. In 1993-1999 three steam boilers were decommissioned and replaced by two fluidized bed boilers in 1996 and 2000 respectively.

 

Siekierki Combined Heat and Power Plant 

 

The third heat generating plant in Warsaw, the largest in Poland and second largest in Europe, is the Siekierki Combined Heat and Power Plant. Its origins date back to 1949 when the Office of Energy Projects in Warsaw presented a concept of locating the CHP plant on the bank of the Vistula near Siekierki. Initially three locations were taken into consideration: at the junction of Bartycka and Czerniakowska Streets, in the area of the intersection of Czerniakowska and Chełmska Streets and in the village of Augustówka where descendants of Tatars lived. In 1956 the Polish Prime Minister, Józef Cyrankiewicz, finally approved the location in Augustówka and two years later construction of the Siekierki CHP Plant commenced.

 

The general contractor was Energoprojekt Warsaw with Jerzy Garald as project leader. Design works took into account experience from the already operating Żerań CHP plant, but many innovative solutions were implemented. In the first place the light structure variant was adopted. Internal walls and roof of the boiler plant were supported on boiler structures. The rear walls of boilers were at the same time an external part of the main building. The arrangement of turbine sets was different than in Żerań – they were perpendicular to the longitudinal axis of the engine room, which significantly decreased its cubic capacity.

 

Construction of the combined heat and power plant started in 1958. The first condensing turbine set, producing electricity (50 MWe) only, was commissioned on 4 December 1961.

 

 

Initially the CHP plant was built in a header arrangement like the ones in Powiśle and Żerań. The header was composed of four OP-230 steam boilers, one condensing turbine set with a TK50 turbine and five condensing turbine sets adapted to work with TK30 turbines for the needs of district heating. In 1962 the plant generated 200 MWe of electricity and 522 MWt of heat.

 

In 1967-1984 the plant was expanded. As a result the following were installed: four hard coal fired water boilers, including three WP-120 and one WP-200 boilers; four oil-fired water boilers – two PTWM-100 and two PTWM-180 type; four heat generating units composed of a boiler and a turbine set, including three with a BC-100 turbine and one with a BC-90 turbine. The expansion resulted in the formation of one of Poland's largest energy complexes being a cluster of various units.

 

In 1984 the CHP plant started to refurbish the core equipment and auxiliary process lines. In 1987 an additional intake of water from the Vistula was put into service since the existing one had insufficient output. In 1993 condensing turbine No. 1 was adapted for the purposes of district heating. The next stage of modernisation, completed in 1998, referred to heat generating units in which control systems were replaced and a computerised monitoring system was introduced.

 

In 2002 the low-pressure part of the turbine was reconstructed, which considerably increased the efficiency of the whole heat generating unit. Also, boiler No. 2 was fully refurbished. Practically all its elements were replaced and a desulphurization plant was added.

 

Wola Heating Station

 

The heating station was put into operation in 1974. Its construction was necessitated by the need for supplying heat to the new housing estates in the western part of Warsaw, mainly Ursus and Jelonek, and to local industrial plants. Initially, water boilers of PTWM-100 type made by the Taganrog Boiler Factory were installed. Those were single-draught watertube boilers fired with heavy fuel oil (mazout), with a capacity of 116 MWt each. In 1975 and in 1978 two more such boilers were commissioned. Another boiler (No. 5) of KWGM-100 type with a capacity of 116 MWt, produced by the Drohobych Boiler Factory, was put into service in 1980. The then attainable thermal capacity of the plant was 570 MWt. The heating station also had five smaller steam boilers installed to heat the mazout. These are EO-125-021 boilers. In 2003 boiler No. 5 was dismantled due to its poor technical condition and lack of orders for thermal power from the city. Wola Heating Station is now used only in the heating season and only when the temperature outside drops. It supplies heat to two heat supply mains: “F” towards Śródmieście and “J” towards Jelonki. The third heat supply main “UR”, leading to Ursus, has been out of use for a few years.

 

Kawęczyn Heating Station 

 

Kawęczyn Heating Station is the third largest source of heat supplies for Warsaw. It was put into service as a heating station in 1983. The plant had four WP water boilers installed. In the following years the installation of steam boilers and heat generating turbine sets was planned according to the then assumptions for the development of district heating in Warsaw. Kawęczyn Heating Station had an autonomous chemical laboratory, electric equipment testing station, large mechanical and electrical workshop and a modern warehouse. In liaison with research and development institutions attempts were made to optimize the economic operation of generating equipment and new technologies were tested. An example is a flue gas desulphurization plant employing radiation methods.

 

When heat insulation was installed in thousands of buildings in Warsaw in the 1990s, the requirement for heat energy decreased considerably. Thus, there was no need for building new power units with turbine sets. And so the plant remained a heating station. In addition, one of two WP-120 boilers was decommissioned in 2002. The heating station has a chimney which is one of the most interesting building structures in Warsaw. It is 300 m tall and is higher than the Palace of Culture and Science. In 1988 a flue gas continuous monitoring system was installed inside the flues. The drainage installation of the chimney stack and the main building is at the same time a source of process water for the plant. 

 

Today the district heating system in Warsaw is one of the largest and the longest existing district heating systems in Europe. The total length of the pipelines exceeds 1,700 km, of which 300 km are heat supply mains, and distribution networks and service lines have 700 km each. The infrastructure supplies heat to an area of 190 km2, serving 19,000 buildings with a total cubic capacity exceeding 230 mln m3. District heating covers more than 80 % of the city's heat requirement which is now produced in the Siekierki and Żerań CHP plants and in Kawęczyn and Wola heating stations.