Serbia: TPP Kostolac, Electricity generation and overhaul investment report17. March 2015. / SEE Energy News
Maximum production of Kostolac installed thermal power capacities amounts to about 6.600.000 MWh, which is the top limit of these units.
The time is getting near when the thermal power plants in Kostolac will produce electricity with the power of 1.000MW. EPS is no longer the sole electricity supplier in Serbia, meaning that the units need to be more efficient in order to make the price of the produced KWh more competitive on the market. Maximum production of Kostolac installed thermal power capacities amounts to 6.600 MWh, which is the top limit of these power units.
– Prior to reaching this maximum electricity production in the company Thermal Power Plants and Mines Kostolac, the most important is to facilitate the device operation stability, to execute the envisaged overhauls in TPP Kostolac A and Kostolac B. The optimization of the Unit B1 is to follow and at this moment both companies have to prove their contracted parameters based on which we can reach the maximum, nominal power – says Mr. Zoran Stanojević, the Director of the Department for electricity production in the company Thermal Power Plants and Mines Kostolac. – Fine adjustments and the optimization of the operation of the unit are to be carried out in the following months, and that would not be a fast process. That will improve both efficiency and exploitability rate. Afterwards the TPP “Kostolac B” will have 700MW, and “Kostolac” 1.000 MW in total, while in five years, with the future unit B3 it will have 1.350MW, until the units A1 and A2 are scheduled for reconstruction.
TPP Kostolac A has a steady operation with the Unit A1 and A2. This thermal power plant provides heat power for the heating system of Požarevac, Kostolac and surrounding settlements, and the total achieved electricity production over January in the Units А1 and А2 amounted to around 180.519 MWh, which is by several percent lower than planned.
– We had a minor intervention at the unit A1, one standstill in January, when we repaired all minor defects on the turbine, so that now this plant operates at maximum power of 100MW. The unit A2 worked without a single downtime and once again confirmed its reliability. At the Unit A2 we expect to have an overhaul this year, due to a complete boiler system part replacement with located points of what needs to be replaced. It is about the major Contract to provide a reliable operation of the Unit A2 in the period to come – said Mr. Stanojević. – in TPP Kostolac B, the rehabilitation on the Unit B2 was completed in 2012, so that this Unit now has the power of 350MW. The Unit B2 worked incessantly during the last month, except on January 31, when a short standstill occurred about an hour and a half in duration. That being done, we returned to the electric power grid and now we have a stable electricity production from the Unit B2.
According to our interlocutor’s words, in cooperation with the Chinese corporation CMEC, the rehabilitation of the Unit B1 has been completed, lasting for almost ten months and including large-scale and complex technical tasks. The rehabilitation of the Unit B1 commenced on March 1st, 2014 and lasted until December 1st last year. Due to the floods that hit the production units of the company Thermal Power Plants and Mines Kostolac in May, last year and unfavorable, windy weather conditions when mounting electric filter facility, there was a temporary standstill of this project implementation, which resulted in the deadline extensions. So, the synchronization of the Unit B1 with the electric power grid was done on December 29th 2014. In January, the optimization of the Unit B1 operation was done, particularly having in mind the new concept of combustion in the fire box because of the installation of the nitrogen oxides emission reduction system. The Unit has gradually been led towards full capacity, and on January 26th it worked at full blast, with the power of 335MW. The Unit B1 has currently been undergoing calibration, adjustments and other contracted activities with several large companies that are to bring the operation to nominal parameters and the power of 350MW.
– The plant has undergone a reconstruction of the turbine and when boiler unit reaches required parameters, we will have a maximum power the turbine is to give to the generator. The boiler unit has undergone several operations. CMEC has done the replacement of the pipeline system of a portion of the steam pipeline and complete steam pipeline hanger system, thus giving the system reliability and reducing the number of downtimes in the period to come – said Mr. Stanojević. – CMEC has also replaced complete electric filter system and it will be proved when all other things are finished. When reaching the maximum power of the Unit, what follows is the proving that particles emission is in accordance with the contractual obligations. The control room of the Unit B1 underwent several corrections due to reduction of nitrogen oxides.
As explained by our interlocutor, “Siemens” has worked on the complete reconstruction of the air mixture duct, by which coal dust is transported from the mills to the burners and inserted into the boiler and the air ducts by which secondary air heated to 250-300°C is inserted into the boiler, i.e. the fire box, to burn the coal. The different arrangement of the ducts and air gave Siemens the possibility to lower the temperatures in the upper zone, to link nitrogen oxides into compounds that are then ejected together with coal powder and do not represent pollution any more, mainly nitrogen monoxide and nitrogen dioxide.
-The boiler unit had work done on the reburning grid, and/or the complete deslaging beneath the boiler. The reburning grid and ash removal unit were replaced, which are within their capacities and produce required nominal values. There are slight problems with the temperatures distribution and heat progress, i.e. the slag that ends up there and the particles that are not burned that have a high temperature, cause the slagging – explained Mr. Stanojević.
The Mills underwent also a huge repair, which gives the boiler unit the basis for good combustion, achieved with boiler where the combustion is on the fly, by the fine coal powder. The mills are to mill the coal according to the given parameters and to insert fine particle in the three levels of the burner, i.e. 80-85% in the lower two and the remaining 15% in the third, top burner. The reconstruction was done by Siemens, and besides distribution and arrangement, a burner tilt of 15 degree was included, so that burning and flame and flame focus, the entire flame burning as ellipsoid are lowered. It provides for the lower temperatures to be above, and higher temperatures down, so that the nitrogen oxides could be extracted, i.e. to have a reaction while combusting and turn into other compounds. Our next step is to make a required milling fineness in the mills to make the coal and coal dust arrangement more optimized. “Siemens” will provide its guideline on how to reach optimized and right combustion by height, in order to have the appropriate heat exchange and to reach adequate parameter at the output of fresh steam from the preheater 3 and warm inter-heat at the output from the inter-preheater 2, which are the first heating surfaces above the fire box.
We are to hold a meeting soon with the company “Minel”, which is in consortium with “Feromont” and “Hitachi”, about the calibration of mills in accordance with the firebox geometry, made by Siemens. After obtaining specified fineness, Siemens will give the distribution of air-mixture and air to reach the optimized heat exchange in the firebox.
The heat exchange therein must be good with the boiler pipeline, maximum exchange of heat to the fluid in pipes, water/steam in the evaporator, and then steam/preheated steam in the lower preheaters – pointed out Mr.Stanojević. – We should also make sure for the small dimension particles to fall on the reburning grid and to get reburned there, but not burned out, so that the procedure stays steady. This would lead to maximum load of the mills and increasing of the coal up to the maximum to reach the power of 350MW. In technological terms, it must be done, as soon as possible.
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