Central Tejo
| Central Tejo | |||
|---|---|---|---|
| location | |||
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| Coordinates | 38 ° 41 '44 " N , 9 ° 11' 44" W | ||
| country | Portugal | ||
| Data | |||
| Type | Steam power plant | ||
| Primary energy | Fossil energy | ||
| fuel | coal | ||
| owner | Companhias Reunidas de Gás e Electricidade (CRGE) | ||
| operator | Companhias Reunidas de Gás e Electricidade (CRGE) | ||
| Start of operations | 1909 | ||
| Shutdown | 1975 | ||
The Central Tejo thermodynamic power plant of the United Gas and Electricity Company “ Companhias Reunidas de Gás e Electricidade (CRGE) ” supplied the Portuguese capital Lisbon and the surrounding area with electricity. Built in the Belém district , it was in operation from 1909 to 1972, but from 1951 only as a backup power station. Over the years it has been rebuilt several times and expanded with additions, so that different construction and production stages can be distinguished.
The original “Central Tejo” power plant from 1909 produced until 1921. Today nothing can be seen of this structure. In 1914, the construction of the factory halls for the low-pressure steam boiler and the machine room began, which was later added on several times. In 1941, the installation of the high-pressure steam boiler began with the largest building in this industrial plant, and in 1951 an additional steam boiler was added .
Although it last ran in 1972, it was not officially closed until 1975. What remained was an industrial monument of great importance. It was declared a Cultural Heritage of Public Interest in 1986. Since 1990 the steam power plant “Central Tejo” can be visited in its redesign as an electricity museum.
history
Like most European metropolises at the end of the 19th century, the city of Lisbon developed rapidly and expanded, and with progress so did the need for electricity : it began with the replacement of gas lamps with electric street lighting while in the Industry gradually recognized the advantage of electric motors and the era of private electricity consumption began in the wealthier households.
At that time there were two power plants in the Portuguese capital: " Central da Avenida " (1889) and " Central da Boavista " (1903). The respective names indicated their locations within the city; accordingly the steam power plant "Central Tejo" was initially called " Central da Junqueira " because it belonged to the Junqueira district. However, this name fell into oblivion over time, and after its completion it was officially named after the river that shapes it and on whose bank it borders - " Central Tejo ".
The old "Central Tejo"
The small power plants (Avenida and Boavista) could no longer meet the growing demand. In addition, they were in the midst of densely built-up residential areas, the quality of life of which they severely impaired due to environmental pollution. In addition, they had no expansion possibilities for the necessary extensions that would be necessary in the foreseeable future in order to be able to meet the requirements of the new electricity industry. The company that owned the production and distribution rights for electrical energy for the city of Lisbon, " Companhias Reunidas de Gás e Electricidade " (CRGE) (United Electricity and Gas Works), therefore planned in early 1908 to build a new steam power plant . In the concession application, they asked for permission to build a “new power station” on an industrial site in the western part of the city between the naval arsenal and Pedrouços beach .
The chosen building site was exactly halfway between the residence of the President " Palácio de Belém " and the National Rope Factory of Junqueira, the so-called " Cordoaria Nacional ", both of which still exist today. In March 1908, after the financial means for the new thermo-electric center had been obtained, the construction of the factory that was to supply Lisbon and its immediate vicinity with electricity for more than four decades began.
The engineer Lucien Neu was responsible for the final technical planning. He made maximum use of the available space by arranging the turbines in the middle and the steam boilers on the sides. The project was changed several times, which is why the construction work dragged on longer than planned. The construction company commissioned was Vieillard & Touzet , which employed around 50 workers there. The “Central Tejo” power station was formally inaugurated in the summer of 1909, although many important changes were made by the end of 1910, such as the use of new machine sets or the enlargement of the boiler room, which necessitated the construction of a new, 36 meter high, funnel-shaped chimney .
In the pursuit of a steady increase in the production rate, the “ Central da Junqueira ” power plant has repeatedly acquired new machinery from its commissioning until 1912. It began in 1908 with two alternators, which still came from the " Central Boavista ", each with 1 MW capacity, and six steam boilers from the Delaunay-Belleville brand. In the course of the expansion in 1910 and the installation of three new turbo-generators Brown Boveri & Cª , the total power could be increased to 7.75 MW. In addition to the four boilers at the beginning, five were added later with higher steam generation. After all the systems were in operation in 1912, the machine park of the former "Central Tejo" consisted of fifteen small Belleville boilers and five three-phase current generators, which fed the power grid of the city of Lisbon.
In terms of its exterior design, the building in which this huge facility was located was characteristic of the architecture of small power stations at the end of the 19th century, at that time also called "electricity factories". The floor plan corresponded to an elongated, double roofed main building with three transverse halls adjoining the west side; like “guardians”, two slender chimneys towered over the factory complex. On the respective north - south front the company name: " 1909 / Cªs Reunidas Gás e Electricidade / Estação Eléctrica Central Tejo " ("1909 / United Gas and Electricity Works / Central Tejo Electricity Station ").
This first "Central Tejo" was designed for an operating period of six years (1908-1914) until the CRGE were able to raise the necessary capital for the construction of a larger headquarters with more capacity. The outbreak of the First World War delayed this, however, and the "Central Tejo" produced in this original form until 1921. The generation and distribution of electricity took place under increasingly precarious conditions, especially since the use of inferior fuels resulted in, among other things, constant malfunctions in the steam boiler caused significant setbacks in the rate of growth and development of the city's electricity distribution. Despite these difficulties, construction work on the low-pressure boilers continued and at the end of 1916 the headquarters began to produce steam from the first two low-pressure boilers. These were housed in the new building, which, although still unfinished, offered the prerequisites for increasing the supply of the existing machine sets.
After the building for low-pressure production was ready for occupancy and fully operational in 1921, the old "Central Tejo" was shut down, dismantled and various storage rooms and workshops set up there. A few years later, in 1938, the halls of this "original headquarters" had to give way to the new building for the high-pressure boilers and were completely demolished.
The new Central Tejo
Due to the poor condition in which the old "Central Tejo" was, and in order to be able to meet the growing demand for electricity, new buildings began to be erected in 1914 and more efficient machines were used. This development and modernization phase only ended with the commissioning of the 15th and last steam boiler in 1951.
In general, two main construction phases can be identified:
- In the first phase, between 1914 and 1930, the low-pressure system was constructed and the halls for the low-pressure steam boiler and the engine room were expanded.
- The second corresponds to the period between 1938 and 1951, the installation of high pressure production. After that, the structure of the building complex remained unchanged to this day, whereby the high-pressure steam boiler hall stands out from the rest of the facility.
Low pressure
With the construction of the system for the low-pressure steam boiler and the new machine room, the "Central Tejo" begins to consolidate both operationally and architecturally, with the use of brick for the front facades of the entire industrial complex.
The low-pressure period can also be divided into three different construction phases:
- The first, from 1914 to 1921, corresponds to the construction of the steam boiler building, the coal conveyor system and the machine room.
- During the second phase, between 1924 and 1928, the addition of a factory hall for the installation of new steam boilers and additional coal conveyor belts, a new turbo set, and the quay for the cooling water supply including a channel system should be emphasized.
- In the third construction phase, between 1928 and 1930, the machine hall and the steam boiler room were expanded for the last time for the larger combustion systems.
First phase (1914-1921)
In 1914 construction began for the low-pressure system and machines. The project consisted of several building parts: two elongated, double-roofed halls each for six low-pressure steam boilers from Babcock & Wilcox ; a machine room, designed for two German 8 MV turbo alternators from AEG ; a control room and a small substation . Construction is started in a north-south direction and east-west; to the south they planned from the beginning a later expansion up to the river " Tejo ".
Shortly after construction began, the First World War broke out, which meant delays in deadlines and delivery problems for the turbo generators ordered in Germany . These should only arrive after the end of the war. Nevertheless, in 1916 the first two low-pressure steam boilers (marked with the numbers 5 and 6 on the plan) were installed to operate the generators of the old headquarters.
In the two following years two more new steam boilers were installed (numbers 3 and 4), which, together with the 5 and 6, exceeded the capacity of the old generators of the primitive "Central Tejo". The "CRGE" had to realize that the purchase of an additional turbo generator was inevitable as a replacement for the one that had been ordered years ago in Germany but still could not be delivered. Therefore, a department for another turbo generator was set up in the machine room. Finally, in 1919, a new machine set from the Swiss brand Escher & Wyss with a capacity of 7500 kW went into operation.
In the following year, the remaining steam boilers were installed (numbers 1 and 2) and after the end of the war the two German AEG machines finally arrived, which were already functional in 1921. With the assembly of these six steam boilers and three generator sets, the production quota leveled off and made it possible to dismantle the outdated machine park of the “Central Junqueira”.
Second phase (1924–1928)
Over time, electricity consumption grew and again demanded decisive renovation work in the plant, as well as the expansion and completion of the low-pressure steam boiler wing. The “CRGE” expansion project envisaged a new industrial hall in order to be able to install three new low-pressure steam boilers and a new three-phase generator.
Accordingly, a study in 1922 examined the assembly of steam boilers number 7 and 9. Any possible firing with coal dust was discarded after tests with this fuel in steam boiler 8 had not produced satisfactory results. Nevertheless, boiler number 11 would later be charged with coal dust.
The so-called “new steam boiler room” extended to the south, with the front facade still unfinished towards the river, only temporarily covered with zinc sheet, while a metal structure simulated the bay window, as a third and last extension to the low-pressure building was planned. The steam boilers 7 and 9 from Babcock & Wilcox were first installed in this new hall, in 1924 and 1925, respectively. The steam boiler 11, by Humboldt, was installed in 1928; as it was fired with coal dust, it had its own coal dust mill.
The machine room remained unchanged, but in 1925 an 8 MW turbo generator was installed, the number 4 of the Stal-Asea brand . In addition, the inflow channels were constructed, as well as two siphons at the new dock of the cooling water supply for the inlet of the river water into the system.
The third phase (1928–1930)
In the third construction phase of the original "Central Tejo", the factory halls (the steam boiler room and the machine room) were completed. It was not until 1928, when the steam boiler 11 was already being assembled, that the decision was made to acquire the last two low-pressure boilers 8 and 9 from the well-known manufacturer Babcock & Wilcox due to the protracted construction problems of the Humboldt boiler. However, these are not finally ready for operation until the end of 1930.
Structurally, the external appearance of the new wing of the factory was retained, only with larger dimensions; For this purpose, the provisional zinc sheet cladding was dismantled, added towards the river and given the definitive facade that still exists today.
Like the boiler room, the engine room also had to be enlarged towards the south in order to be able to set up the latest and last turbine set from Escher Wiss / Thompson (to which number 5 was assigned in order) and to gain space in the basement for unloading the Turbines , alternators and various other materials. The higher capacity of the machines also required an adaptation of the cooling water supply and therefore the construction of two new siphons , one each for the inflow and one for the outflow, with the existing four.
After fifteen years of construction and expansion work, the “Central Tejo” finally had three large working zones arranged parallel to the river in its low-pressure phase: steam boiler , machines and substation . The boiler room consisted of four large factory halls, the open interior of which offered enough space for eleven low-pressure boilers, ten from Babcock & Wilcox (British technology) and one German make from the Humboldt brand. In the machine room, an elongated building that was also open space inside, across the boiler room, there were five generator groups of different outputs and origins: Escher & Wiss , AEG , Stal-Asea y Escher Wiss / Thompson.
High pressure
Although the plant was operated with low pressure from 1930 to 1938, a series of renovations had already been undertaken with a view to future high-pressure conversion, as a new building was needed.
It was to be built exactly where the original "Central Tejo" was. This only consisted of a series of workshops and warehouses, but before it could be demolished, an alternative had to be found for the ancillary functions that are indispensable for operation. Therefore, the land and facilities of the neighboring old sugar refinery Senna Sugar Estates, Ltd. to the east were bought . , owned by the Companhia de Açúcar de Moçambique .
Since the beginning of the decade, AEG three-phase units 2 and 3 had constantly caused malfunctions and breakdowns. Therefore, in 1934, an application was made to acquire and license two generators from the same manufacturer, but with double the power. At the end of 1935 the turbo generator number 2 was installed and inaugurated; at the same time the installation of the new voltage transformer was ready, which the substation allowed the "Central Tejo" the whole Lisbon area including Tagustal to Santarém supply. At the end of the following year, generator 3 was also replaced by a new one.
With the installation of these new, more powerful turbo sets , it became almost inevitable to use the first high-pressure steam boilers (numbers 12, 13 and 14) in order to use the power of the turbo generators efficiently with more steam energy. The steam boilers were also ordered from Babcock & Wilcox this time . Because of its size, the largest building in this industrial complex had to be built, namely the high-pressure boiler hall.
Dismantled and out of order, the demolition of what was left of the old headquarters began in 1938 in order to set up this new “Central Tejo” factory department in its place. The construction contracts were awarded to various companies: The Societé des Pieuz Franki, which began in September of the same year, was commissioned with the mixer and the expansion of the coal conveyor system. The metal structure and construction was taken over by the Portuguese company Vulcano & Colares and began to construct the boiler frame and the first structural elements in March 1939. It is worth noting about this building that the entire structure is made of iron , while brick is used to clad the external facades , just like the low-pressure hall. The only difference is in the decoration , which, in contrast to the rest of the complex, shows a distinctly classical tendency towards court renaissance.
At the same time as the construction of the high-pressure wing, work was carried out on another new, but much smaller, building for the low-pressure auxiliary systems, such as B. the filter and water treatment machines. This annex was intended to create space in the boiler room, especially since, later, an extension was also planned for the high-pressure auxiliary systems. The low-pressure auxiliary system, completed in 1939, was located directly adjacent to the main building next to boilers 8 and 10, which it served.
Again it was a war, this time the Second World War , which delayed the assembly and completion of the high-pressure building. The three steam boilers, which were scheduled to be operational in 1940, could not be put into operation until the following year, after the systems were operational. Boiler 12 in March, boiler 13 one month later and boiler number 14 in August 1941.
The steam boilers could not achieve satisfactory efficiency at low pressure; the high-pressure auxiliary systems had to be set up and the turbines adapted. The space for this was created in the low-pressure boiler room, which is why boilers 1 and 2 were dismantled in 1943. In addition, it was difficult to design turbo sets 2 and 3 for high pressure, especially since the order from the German manufacturer failed due to the trade ban that prevailed throughout Europe due to the Second World War. The conversion material finally arrived in 1942, which made it possible to generate electrical energy under high pressure a year later. In 1943, boilers 12 and 13 began to feed turbo set number 2 and, in 1944, steam boiler 14 began to feed turbo set 3.
Because of the war, the price of coal rose while its quality deteriorated. In just six years (1939–1945), the costs increased fourfold as a result. On the other hand, electricity production also rose gradually, with annual higher growth rates up to a maximum of 52,200 kW and a record rate of 216 million kWh in 1950.
Due to the overpricing of coal, the three high-pressure steam boilers have been converted for firing with crude oil (diesel fuel), a petroleum derivative cheaper than coal. The tank for this liquid fuel with 8000 m³ was at the coal storage area.
The steam boiler 15
As a result of technological progress, the electricity company CRGE planned in 1944 to replace the alternators and obsolete steam boilers with new ones that were better suited to the requirements of the time. Due to the rapid increase in electricity consumption, the expansion plan was later changed to a construction project for a new production facility. In other words, the plan was to build a new steam power plant. In the same year, nationwide electrification was regulated by law, with a change in Portuguese energy policy in favor of electricity generation through hydropower . Not in accordance with this legislation, the project of a new steam power plant was not approved. After several objections, CRGE finally got the approval in 1948 for a minimal expansion of the "Central Tejo", which made the acquisition and installation of a new steam boiler , boiler number 15, possible.
It was also installed by Babcock & Wilcox next to boiler number 12. To do this, a facade had to be torn down, the new area concreted and the new metal structure clad with brick in keeping with the style. The renovation began at the beginning of 1950 and after completion in mid-1951 the new boiler could be started. At that time, the plant was only functioning as an auxiliary center.
During the nearly ten years between the commissioning of the first high-pressure steam boiler and the last, significant technological advances have been made. The steam boiler 15 z. B. comes from the factory with fuel injectors (while the others had only been retrofitted one after the other), the traveling grate was lower, the control room was more functional for displaying and storing the operating functions of the boiler, the ash containers had six grinding funnels to hold the ash and Eject coal residues (not just three) and are also smaller overall.
Connection to the national power grid
The legislation concerning the national electrification ( Lei de Electrificação Nacional ) gave the hydroelectric power generation absolute priority and sat down for a standardization of the distribution through a nationwide supply grid. Against this background, the “Central Tejo” was graded as a backup power station in 1950 and from then on assumed a secondary position as an auxiliary power station, which inevitably marked the beginning of its gradual decline.
In fact, on January 21, 1951, the official inauguration of the “ Castelo do Bode ” dam , the first large hydroelectric power station, was one of the many that were included in the Portuguese electrification project to generate electricity for large consumer centers such as the greater Lisbon and Porto metropolitan areas . From then on, the “Central Tejo” only functioned as an auxiliary power plant to support the supply network in dry and arid years. Even so, it continued to produce electricity, albeit only with a turbo group and two high-pressure boilers.
From 1951 to 1968 the center was in operation every year, except 1961. Because of the water shortage, 1953 was a particularly difficult year, which is why it worked practically all year round, often extremely overloaded, not only to meet the needs of its distribution network, but to to complement the national network. In the sixties the complete low pressure system was then dismantled.
The last production records of the headquarters are from August 14, 1972, which is related to an action by the political resistance movement against the then ruling state regime. In an attack on August 9th, the high-voltage lines were sabotaged and the power supply to the city was interrupted; The “Central Tejo” steam power plant had to step in for a week and generate electricity to compensate for the failure and to feed the Lisbon electricity grid. The former factory employees, many of them already retired, were asked to use their knowledge and experience again to start up the plant and fire the steam boiler 15 with coal for the last time. In this way it was possible to produce 1,200,678 kWh, a fifth of the daily requirement of the “CRGE”. The last entry in the register was left behind - the decade-long rumble and wobble, the characteristic noises and vibrations of the power station fell silent forever.
The "Central Tejo" was officially closed in 1975 and retired.
Museu da Electricidade (Lisbon)
After the shutdown and nationalization of the electricity company, the decision was made to revive this old thermodynamic power plant by using it for cultural purposes. In 1986 the first working group was formed to found the museum, which opened its doors to the public in 1990. Between 2001 and 2005, the museum underwent a profound restructuring, not only with regard to the renovation of the buildings, but also with regard to its content. In 2006 the museum was finally able to celebrate its reopening with a completely new museological concept, dynamic, with an emphatically educational focus.
Due to its cultural and multidisciplinary design, the visitor is offered a wide variety of events; from the main exhibition of the museum, which explains the operation and working conditions of the power plant factory using the original machinery of the former "Central Tejo", to various temporary exhibitions ( paintings , sculptures , photography ...) next to didactic niches with educational games on the subject of energy, or also outdoor solar energy demonstrations , theatrical performances, concerts, conferences, etc.
carrier
The museum is owned and structured by the EDP Foundation, which in turn forms part of the EDP - Energias de Portugal, SA . heard.
The construction
The Central Tejo building complex is now an industrial monument. The extensive factory from the first half of the 20th century was therefore converted into a museum. The brick facades emphasize the uniform appearance of the entire building, differentiate it from all other surrounding structures and give it its very own, characteristic shape. However, the large building of the “Tejo Steam Center” is supported by a supporting iron structure - like an internal skeleton.
Primitive Central Tagus
Originally there was a small “electricity factory” at this point, the old “Central Tejo”, also popularly known as “Central da Junqueira”, after a street of the same name in the neighborhood. Nothing remains of this former production facility, built in 1909 by the architects Charles Vieillard and Fernand Touzet based on a project by the engineer Lucien Neu . Its emphatically modernist tendency restricted the decorative elements mainly to the north and south fronts. On the west side of the main wing there were three halls for the steam boilers . The hallmarks of this "original headquarters" were the slender chimneys , one made of brick, the other, in the form of an inverted funnel, made of iron.
The north and south sides of the main hall, where the generators were located, were similar in their ornamentation to other architectural projects made of iron at the time , such as train stations and market halls, designed in the modern style, the influence of which was beginning to show itself in Portugal . Divided into three parts by pilasters , with narrow horizontal serrated friezes and, above it, a wide ornamental gable . Right and left two openings arranged one below the other: the lower one with a lintel , the upper one with a segmental arch. In the middle segment, wider than the side sections, an enormous window yoke over the entire front, which reached from the base to the gable, so that it formed a step upwards. The arched frame, decorated with tiles , bore the inscription: " 1909 / Cªs Reunidas de Gaz e Electricidade / Estação Eléctrica Central Tejo " (1909 / United Gas and Electricity Works / Central Tejo Electricity).
The industrial halls of the former sugar refinery next to the power plant, then owned by the “ Companhia de Açúcar de Moçambique ”, came from the end of the 19th century . These were bought when the demolition of the old “Tejo steam center” began. It was a small factory with no special decorations , but a very peculiar shape, made up of two elongated sawed roof structures, a kind of tower that served as a silo in the middle, and four double-roofed transverse halls on the west side. All window openings were supported by segment arches and brick frames.
Low pressure production building
Construction of the building for the low-pressure system began in the middle of the first decade, although various extensions were still made up until 1930. From the modernist architectural style (in Portugal under the name " Arte Nouveau "), it consists of an iron structure, lined with the typical brick , which is later also used in the construction of the high-pressure machine hall.
Several factory halls, three of the same size and a fourth, slightly larger, with a gable roof, form a bright, column-free interior, the former boiler room. Across this on the east side, two more factory halls, also modernist, even if the one further away, the substation, did not have a double roof.
The tall vertical windows framed by round arches stand out on the relatively low facades . Above it a kind of frontispiece with emphasized offset edges and a final lintel . The brick was plastered over along the lower plinth, which seems to "support" the rest of the facade. Frame-shaped segment arch protrusions simulate windows (some actually were).
The front view of the machine room is particularly worth mentioning. Facing the river, perhaps precisely for this reason, it offers the most modernist facets of all views, but without violating the overall aesthetic design. The base is distinguished by its stone paneling above the raw layer, the arched window openings by a keystone.
At the level of the brick cladding, three extremely high arched windows rise up, the middle one slightly larger than the others. The continuous frame-like border, each with a keystone at the apex of the arch, extends along the entire south front and side walls. The facade gable is decorated with brick borders , similar to a Lombard arched frieze . Pilasters rise up the wall like two church towers .
The longitudinal facades, divided into three sections by high pillars, reveal a harmonious overall picture, each with three tall windows, which are framed by a continuous border along the entire side front. Above that, square windows, which are lined up like a final decorative strip .
High pressure production building
The classical influence differentiates the ornamentation of the high pressure building from that of the low pressure building. The decorative elements gain in size and monumentality. But the brick cladding is also used here . As with the low-pressure steam boiler hall, the inner carrying ceiling between the boiler and ash room is made up of a brick arched vault with parallel half-domes, with the difference that the low-pressure production was made of ceramic and the high-pressure phase was made of reinforced concrete .
The building was erected in the 1940s and reflects, influenced by the classicism of the Renaissance palaces , the zeitgeist and the authoritarian environment of the local Portugal . Its structure is, in fact, a technical masterpiece, an exponent of iron architecture , unparalleled in Lisbon . It not only holds the brick masonry, but also serves as a supporting structure for the steam boiler and a supporting bracket for the chimneys and the water depot on the roof. From an aesthetic point of view, the facade is comparable to the model of a Renaissance palace, divided into a base , pilaster and entablature . The main facade has three large longitudinal windows in the arched style with a final central stone and decorative molding that extends over the entire front; in between high pillars, from the base to the top gable.
There are two independent friezes . The lower one with framed indentations; the upper one, in the same arrangement, but with windows in the framed fields. Closer to the low-pressure complex is a small tower, and the four chimneys of the high-pressure boiler tower above everything, as well as the mechanisms for air intake and smoke extraction below.
The structure of the steam center "Central Tejo" differs from all buildings in the area, not only because of its imposing monumentality, but of course the typical brick aesthetics. It's hard to believe that it used to be an “electricity factory”.
Functional description of the steam power plant
The operating principle of a thermodynamic power plant is based on the combustion of a fuel to generate steam , which activates an alternator . Theoretically, this seems quite simple, but requires a complex system of machines, piping systems and logistic devices.
Due to the circumstances at the time, power generation in the “Central Tejo” was a bit problematic. Among other things, a complex internal circulation system was required for water and supply air, as well as for processing the fossil fuel , which in the case of this power plant mainly consisted of coal .
coal
Most of the coal-laden freighters came from Great Britain , went upstream and docked directly at the steam power station; The coal was unloaded over narrow walkways between the ship and the quay and stacked in various piles in the coal store “Praça do Carvão”.
The coal was pushed from the stockpiles to the sieve and the coal mill of the firing system in carts. A kind of paddle wheel system carried them up to the mixing silos . Different types of coal were stored there so that the fuel mix could be matched for ideal firing of the boiler.
Well mixed, it was then carried upwards by lifting shovels to the conveyor system of the combustion system above the combustion chamber. From here the coal fell into the stoking device and through chute pipes onto the traveling grate inside the boiler, where it slowly began to burn and reached temperatures of around 1200 ° C.
The cycle of the steam boiler
The steam boilers basically consisted of three cycle processes: water-steam, air-smoke and ash. The functions of each of these cycles were essential to the overall process, and they complemented each other. The task of the water-steam cycle was to transform the water from its liquid state into steam; the ideal use of the air-smoke cycle influenced the profitability of the boiler; Finally, the ash compartment , where not only the ashes produced by incineration, but also uncombusted coal residues were disposed of.
The water required for steam generation was treated and flowed through a closed pipe system through the preheater from behind into the feed water tank, the "drum" (Portuguese: "Barrilete"), above the boiler. It was considered a link because it stored water and steam at the same time. From there, the water trickled down the inside of the combustion chamber, into the so-called '' Bailey '' walls of the water tube boiler. Made of cast iron , these were designed to keep the heat constant while the water circulating in many vertical pipes evaporated. This mixture of steam and water rose again to the drum, from where the steam flowed to the superheater, a group of pipes also inside the combustion chamber. The high pressure (38 kg / cm² and 450 ˚C at the maximum pressure moment) converted the moist steam into dry (i.e. above the critical temperature). So it could be fed to the steam turbines in the machine house.
Air supply is just as important for coal firing as water and water vapor. The main part of the induced draft fan was on the back of the boiler. In order to use the high temperatures of the escaping warm air, it was blown through a pre-suction pipe to the air preheater and from here passed through a fan to the traveling grate in order to fan the flames. The smoke produced was expelled from smoke outlets through the chimneys , after the residual heat had previously been diverted to the furnace and filtered to reduce the pollutants.
The last material cycle, that of the ashes , took place under the steam boiler. Here there were three V-shaped containers to catch the unburned coal , the only partially burned coal and the coal ash. The tub under the downpipes, d. H. at the beginning of the grate, collects those coal pieces that miss the belt when fed; the middle, the half-charred ones that fall from the traveling grate due to vibrations of the steam boiler; the recovered fuel comes back to the storage area and is reintegrated into the feed system. The third and final ash funnel, under the end of the boiler grate, was equipped with a shredder that mixed in water to cool and soften the coal ash. This was then carted outside in wagons to the coal storage area at the ash depot.
Water treatment
As already mentioned, only pure water was fed to the steam boilers in a closed pipe system. Contrary to the obvious assumption that river water from the Tagus river was used for evaporation in the headquarters, tap water from the municipal supply network (as well as from a borehole on the site of the power plant) was consumed. From the huge depot on the high pressure boiler house, the so-called “Castelo de Água” (= water castle), where the water was stored, it came to the “Sala de Água” water house. Three processes were carried out here: water treatment, preheating and pumping.
The treatment of the water is of crucial importance, especially since its impurities, harmful ingredients and the gases dissolved in it lead to corrosion and leaks in pipes and turbines, as well as to oxidation of the pipes. In addition, deposits and scale formation on iron and steel can damage the system and reduce the efficiency of the power plant. That is why all the water intended for the power plant had to be examined in the laboratory beforehand and subjected to a complex treatment and pretreatment process. a. Careful, filters, etc. Abgasung chemical prior to its feed into the system in the form of pure H 2 O .
In order to increase the efficiency of the combustion , the treated water was preheated. The recovered turbine exhaust steam was used for this. This heat exchange in the preheater results in temperatures of up to 130˚C. Then the pure water only had to be put under a certain pressure before it could be fed into the steam boiler. This is done by the pumps in the water space with a pressure of 52 kg / cm², sufficient to overcome the counter pressure of the boiler drum.
Turbo generators
The superheated steam produced flows under high pressure (38 kg / cm²) for Turbo AC generator, wherein he the absorbed energy in the form of kinetic energy to write to the steam turbine, and the power in turn from the connected generator in Electrical energy is converted. A turbo generator set consists of a turbine and an alternator , hence the name turbo generator. The turbine has eight wheels with two blade rings and another seven with only one ring each. The boiler steam enters the distributor depot in the turbine housing through the inlet valve . From here it flows through the opening controlled by injection nozzles through the Venturi tube and reaches the first wheel rim with enough energy to accelerate the turbine to 3000 rpm. In the following wheels, the pressure of the steam gradually decreases in order to equalize the condenser, but at a constant flow rate.
In this way the turbine wheels are set in motion, which in turn make the alternating current generator rotate via a drive and thus generate electrical energy for distribution to the consumers, but also for the control center's own use. The star-shaped coiled alternator provides 10,500 V three-phase current with a frequency of 50 oscillations per second (Hz). The excitation current of the generator is produced by an excitation machine, a direct current generator coupled directly to the main station, which at full power produces a voltage of 170 volts and an amperage of 340 amperes.
The energy generated by the respective generator blocks is sent to the output bus. Each busbar or rail is intended for a substation . A wide variety of customers were supplied from there. In addition to the main busbar, designed for a substation with 10 kV power for the power grid of the city of Lisbon , there were two further busbars, one with 3.3 kV and the other with 30 kV. The first and older of these two output buses fed the associated auxiliary drives of the control center; two lines went from the second with 30 kV, one to Marvila and from there to Vila Franca de Xira , while the other led directly to Santarém , around the industrial plants upstream to supply the Tagus .
Capacitors
After the hot steam has set the turbine blades in motion, it flows into the condensers and then, again in a liquid state, evaporates again in the steam boilers. The exhaust steam jets into the condenser and condenses in contact with the tube bundles filled with cold water inside the exhaust steam room. The cooling water came from the Tagus . Three supply lines and a return pipe formed a siphon which forced the water into the inflow channels. This prevented the river water from mixing with the pure water used in the steam boilers. Because, as already explained, the river water flows through the cooling pipes, while the exhaust steam is in the free interior of the condenser.
The water resulting from the condensation of the exhaust steam is sucked in by the condensate pumps and conveyed again to the boiler drums of the steam boiler, but not without first going through the preheaters , tanks, feed pumps and, last but not least, the superheater. Recovering the condensed exhaust steam and reusing it as feed water for the steam boilers completes the water-steam cycle of a thermodynamic power plant , and as such “Central Tejo” was no exception.
Employment relationships in the electricity company
Since the city needed electricity all the time, the steam boilers were never allowed to rest. Therefore a work regime was introduced around the clock, with three alternating shifts: from 0:00 to 8:00; from 8 a.m. to 4 p.m. and from 4 p.m. to midnight. The continuous increase in output and expansion of the power plant required more and more workers, especially in times of war. In the 1940s the number of employees was around 550, from skilled workers to the vast majority of unskilled workers who did the simplest but also the most difficult tasks.
Work schedule
The “Central Tejo” steam power plant was an extremely complex industrial plant. Due to the large number of employees, a hierarchically structured functional structure was required , divided into the respective factory halls, where, in addition to hard work, there was also physically lighter work to be done. The workers at the steam boiler, for example, had a harder time than those who operated it from the control room.
There were around 45 areas of responsibility in the power station, in the production chain, such as that of the so-called “Alcochetanos” during unloading, to the manual jobs in the workshops and the electricians in the substation.
Functional areas of the steam center:
- The coal store : this is where the workers were used to unload and distribute the coal . The “Alcochetanos” were responsible for transporting the coal from the launch to the storage area. These were specially hired temporary workers, mostly men and women from Alcochete , a place on the opposite bank of the Tagus river . They came to the coal loading, transported them ashore and, depending on the country of origin, piled them in different piles.
At the coal store, known as “Praça”, the so-called “Homens da Praça” (warehouse workers) took over the transport of the coal to the conveyor system of the furnace system. On a normal production day, a shift consisted of 16 men, including foremen, those responsible for maintaining the machinery and checking the bucket and tipping devices.
- Kesselaal : this is where most of the workers were needed: ninety people between 8:00 am and 5:00 pm, thirty during the rest of the time. Every single position made a decisive contribution to the proper functioning of the steam boiler .
The chief engineer monitored the boilers with the help of two henchmen who reported directly to him. At the control command of the boiler of the Kapo Heizmeister (port .: "fogueiro"), which from the control desk that stood steam generation contributed, while the second heater from the boiler down called up out instructions. While the boiler was checking the quality of the firing, the slide (Portuguese: “chegador”) pushed the unburned coal back in from behind in order to burn and not block the grate.
- The ashers (Portuguese: "cinzeiros"): the workers responsible for disposing of the ashes were in the ash bunker under the boilers. Their job was to empty the ashes from the silos and move them outside.
- Machine room and auxiliary drives : During the day, a staff of around 15 worked here, from technical engineers to machine operators as well as specialists for water treatment, cleaning and maintenance crew.
- Substation : here was the application range of the electrician that the substation had under its supervision, its electrical equipment such as transformers , circuit breakers , etc.
- Also to be mentioned are some additional areas of activity such as the laboratory , the workshop, the drawing room and the warehouses . The electrician's workshop took over the maintenance of the entire electrical infrastructure of the headquarters, the joinery and the forge made the molds, furniture and various spare parts for the repairs of the power plant. Around 50 employees worked here from 8:00 a.m. to 5:00 p.m.
- There was also a security service (four guards per production shift) and clerks in the administration area.
working conditions
The working conditions in the steam center “Central Tejo” (as in all thermoelectric power plants at that time) were very tough. This was especially true for unloading coal, working on the steam boiler, disposing of ashes, cleaning the cooling systems and slag containers. The quality of life of the workers, measured by today's standards, was poor.
The great heat and the inhalation of dust and gases are essential here.
It was particularly difficult for the “Äscher”, where the temperatures were very high. Removing the ashes was the most arduous task of all, in an atmosphere of exhaust fumes, slag and still-glowing ashes, which, often collected by hand, were carted onto wagons to the coal store to be emptied into the ash bins. The huge temperature differences made the work of transporting the ashes outside even more difficult.
Social aspects
As one of the largest companies in Portugal with thousands of employees nationwide, “ Companhias Reunidas de Gás e Electricidade (CRGE)” (United Gas and Electricity Works) has implemented social policy measures for the benefit of its employees. The most important were:
- Construction of the Camarão da Ajuda workers' settlement at the end of the 1940s ;
- Establishment of schools for the children of the employees, but also for the employees themselves, with lessons for children, as well as literacy and professional training for adults.
- Creation of medical care centers for the families of the employees.
Patrimonial value
As already mentioned, the “Central Tejo” power station has a relevant patrimonial value , not only from an architectural or archaeological point of view, but also in terms of its historical , social , anthropological and economic importance. The cultural assets left behind from decades of operation are undisputed. It was the great power station in Lisbon and Portugal until the middle of the 20th century. Its supply radius extended for the entire urban area and the Tagus Valley upwards , for street lighting, private consumption and the energy supply of the factories. Without its existence, Lisbon would certainly have developed differently. It stood behind the growth and expansion of the city in the 20th century, aided the industrialization of the region and the construction of the country's first electric rail link (Lisbon - Cascais).
At the same time, the “Central Tejo” steam power plant was crucial for the modernization of the city. Several generations worked under the toughest conditions on and under the steam boilers so that others could have light in their homes, walk on illuminated streets at night or comfortably take the tram up the steep hills of Lisbon. The building complex of the power station houses a valuable cultural heritage which, if it is cared for and preserved, will help this old power station escape the de-industrialization of the Belém district and continue to exist as a unique industrial monument of Portugal, perhaps even Europe.
- Real estate : the “Central Tejo” factory (cultural monument of public interest since 1986), with buildings of low pressure production and machine room (1914–1930), high pressure production and water treatment tract (1938–1951), and the various workshops of the plant, their series of buildings, (formerly from the former sugar factory from the late 19th century principles of the 20th century), are now the Center for Documentation and Reserves Museum.
- Mobile inventory : The museum currently has: four high-pressure steam boilers made by Babcock & Wilcox from 1941 and 1951; two AEG turbo sets from 1942. Condensers , coolers and disconnectors in the machine room, as well as water treatment systems , filters, pumps and distillators from the 1940s in the water house, coal paddle wheels, wagons , silos , carpenters ' and blacksmith tools, etc .; In the reserve warehouse and front yard: turbo generators from other power plants, speed regulators, valves , parts of Lisbon's public street lighting , electrical household appliances from various eras, types and classes, etc.
swell
- BARBOSA, Pires, CRUZ, Luís, FARIA, Fernando, A Central Tejo: A fábrica que electrificou Lisboa , Museu da Electricidade and ed.Bizânzio, Lisboa, 2007
- COSTA, Vítor, Central Tejo. Breve resumo da sua evolução e dos seus processos tecnológicos (1906–1972), in Revista Arqueologia & Indústria , (2–3), pp. 149-160, Associação Portuguesa de Arqueologia Industrial (APAI), Lisboa, 1999/2000
- SANTOS, António, "Arquitectura de Tijolo e Indústria. A Introdução do Tijolo Sílico Calcário em Portugal (1903-1913)", in Revista Arqueologia & Indústria , (1), pp. 101-114, Associação Portuguesa de Arqueologia Industrial (APAI), Lisboa, 1998
- SANTOS, António, "A Arquitectura da Electricidade em Portugal (1906-1911)", in Revista Arqueologia & Indústria , (2-3), pp. 123-148, Associação Portuguesa de Arqueologia Industrial (APAI), Lisboa, 1999/2000
- Revista Indústria Portuguesa, nº. 101, 118, 153, 164, 171 and 179
- Wikienergia . Categories and subcategories from Central Tejo, Museu da Electricidade, Acervo and Centro de Documentação. Consulted May 2010
Individual evidence
- ↑ Entry / IGESPAR. Classification by government decree nº 1/86 3 January ( Memento of the original from October 15, 2014) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
