Table 2 Potential elements to be preserved in the As Pontes power plant
\({\varvec{E}}_{\varvec{i}}\) | Element | Description |
|---|---|---|
\({E}_{1}\) | Coal park | The dimensions of this park, which was devoted to coal storage and homogenization tasks, were 160 m wide by 592 m long. It is formed of a series of prestressed metal arches with circular section, from which the roof cladding is suspended |
\({E}_{2}\) | External coal park | The coal used in the plant was transported by road and stored temporarily in an external park where it was accumulated in piles. Subsequently, the coal went through a tunnel and was poured it onto a conveyor belt by two machines |
\({E}_{3}\) | Coal distribution system | The coal passed through other conveyor belts in the distribution system, which also resulted in its magnetic separation and crushing. This element had two independent lines that ensured the continuous fuel supply to the boiler |
\({E}_{4}\) | Air intake system and precipitators | The gases derived from combustion went through air preheaters that transmitted their thermal energy to the air used for combustion. In turn, these gases were separated from solid particles to prevent their release to the atmosphere by means of electrostatic precipitators |
\({E}_{5}\) | Boiler | The boiler had a natural circulation system and was prepared for the combustion of lignite and subbituminous coal. Its height amounted to 90 m, with a double line of forced and induced draft fans and 6 columns of burners tangentially arranged |
\({E}_{6}\) | Chimney | The chimney is a unique structural element whose presence allowed the evacuation of combustion gases. It is 356.5 m high and contains four metal conduits in a concrete shaft with diameters of 36.5 m at the base and 18.9 m at the top |
\({E}_{7}\) | Ash and slag extraction system | Wastes derived from the combustion of coal were collected in the form of slags and fly ash. The extraction system was continuous and discharged into the so-called ashtray, where slags and fly ash were extracted and subsequently evacuated |
\({E}_{8}\) | Ash and slag landfill | Slags and fly ash were disposed at a non-hazardous waste landfill specifically designed for their elimination. It was in a hillside area within the facilities of the thermal power plant. Until 2011, theses wastes were reused by the cement industry |
\({E}_{9}\) | Turbine hall | The turbine hall highlights by its occupation and technological complexity, including four turbines and their corresponding alternators. The hall comprises both metal and reinforced concrete frames, which work as a linkage with other areas in the park |
\({E}_{10}\) | Cooling towers | The cooling towers enabled the power plant working according to a closed thermodynamic cycle. The cooling process consisted of releasing water in the form of rain and exposing it to the air current that is inside. The flow processed amounts to 38,000 m3/h, with a thermal leap of 11 ºC |
\({E}_{11}\) | Transformer substation | There were 4 transformers corresponding to the output of each of the generation groups. These transformers served to change the nominal voltage of the alternators from 18 kV to 410 kV, which corresponds to the voltage of the high-power grid |
\({E}_{12}\) | Sewage treatment plant | The entire plant needed potable water for different general uses, such as production, human consumption, hygienic services, etc. The system had a clarification capacity of around 200 m3/h, as well as ozonation, demineralization and filtration systems |
\({E}_{13}\) | River water collection station | Water was extracted from the Eume river, which is very close to the power plant. It was collected by means of a pumping machine and then circulated to the water treatment plant |
\({E}_{14}\) | Fuel oil and gas oil storage tanks | There were 2 fuel oil tanks with a capacity of 4000 m3 and 3 diesel tanks with a capacity of 100 m3 each. This enabled having sufficient energy available for the complicated start-up processes |
\({E}_{15}\) | Effluent treatment plant | This plant treated effluents between 0.1 and 3.0 m3/s meeting the regulations in terms of authorization of discharges. The treatment phases included roughing filtration, neutralization, grinding, flocculation, decantation, homogenization and sludge reuse |
\({E}_{16}\) | Environmental monitoring infrastructures | The plant had different monitoring stations for environmental control. These included the analysis of the Eume river water, the evaluation of noise outside the perimeter of the facilities and a temporary deposit for hazardous wastes |