Serbia: TENT engineers increased the power of B1 unit, the project report

, News Serbia Energy

The technical teat of the engineers from the company TENT will remain recorded even in the pages of the prestigious international scientific journal ’’Energy“. – New solution for increasing the power and efficiency of the block B1 has been operating successfully for more than a year and a half, and the effects after its implementation are more positive and bigger than those envisaged by the design

During the first phase of revitalization of the block B1 at TPP „Nikola Tesla” in Ušće, the technical concept for increasing the energy efficiency of this 620-megawatt block was implemented, by installing an additional heating surface (EKO) with a separate feeder and regulation. It was a unique solution at the moment, implemented on thermal power blocks for the first time in the world. For such technical improvement, the company TENT has received numerous awards both from the domestic and foreign professional public.

The technical feat of the engineers from the company TENT will remain recorded even in the pages of the prestigious international scientific journal ’’Energy“, (, devoted to the achievements within the energy field. Namely, the study of the engineers from the company TENT titled „Increasing the Efficiency and Power by Installing an Additional High-pressure Economizer on the Lignite-fired 620 MW Thermal Power Plant ”, created by Miloš Milić, Milorad Jovanović et al., was published in English in the March issue of the renowned journal. At the same time, such technical solution concept represented the culmination of all the activities implemented within the previous period, starting form 2002, during the revitalization and modernization of the thermal power plants of the company TENT in Obrenovac.

– The new technical and economic business concept of the company TENT in the period after 2002 was actually born out of necessity, because, ever since 1985, when TENT B2 was commissioned, to this day, no new blocks have been built in this company. Almost the same time distance divides us from the „youngest” thermal power block when it comes to PE EPS (the block Kostolac B 2 which began operations in 1991) – says Miloš Milić, one of the creators and a long-time director of PTO in the company TENT, who occupied this position continuously from 1996 up to 2014, when he has been retired.

It should be added that the nineties were marked by survival within the energy sector, too, and that „when the going got tough, the experts got going”, as the well-known saying goes. In such circumstances, it was inevitable that, since a new block could not be built, the determination to commence the rehabilitation of the existing capacities and the extension of their working life should mature. The management of PE EPS at that time, with the support of the managing staff of the company TENT at that time, gave the „green light ” to take this course. According to Miloš Milić, the essence of this new concept of techno-economic management of the company consisted of increasing the power of the blocks, extending their working life, and particularly, increasing the efficiency of their operation, since all TENT blocks have exceeded the basic working life of around 30 years, or 200,000 hours of operation.

– This is why new methods had to be applied which would lead to the conditions enabling us to manage the electricity production processes, and not only to monitor them. Indeed, this is the first step towards the achievement of an increased efficiency of blocks and a whole series of projects have been made for this purpose– Miloš Milić says.

He emphasizes that, in addition to this, it was necessary to apply the environmental protection measures intensively, primarily for the suppression of solid particles emission, elimination of sulphur and nitrogen oxides from flue gases. This is in accordance with our country’s commitments resulting from its determination to start the process of accession to the European Union. Conceived in such manner, so to say, the „3Ps” program (power increase, prolongation of the working life and putting up the efficiency of blocks), was implemented on TENT blocks A6 and A5, whereas „the third block” will undergo these operations in 2014, and the first phase has been implemented on the block TENT B1 for the time being.

However, to increase the power and efficiency of „the first block” in Ušće, first it was necessary to remove some of the obstacles in the way. After a series of tests and analyses of the block operation, simulations of various conditions of its operation, the above mentioned team of engineers, consisting of Miloš Milić, Milorad Jovanović, Zoran Stojanović and Ivan Gajić, came up with this unique concept.

– It was necessary to bypass the high-pressure heaters with feedwater and thus avoid additional resistance which had already been a problem, to make and install a third EKO which, according to the dimensions, should represent around 60 percent of the sum of the existing two, to design and install a new water mixer which would homogenize the water from the existing and the additional EKO. This procedure would provide an additional quantity of steam for an increased power up to 675 megawatts instead of the basic 620 megawatts, and the efficiency of the boiler would also be increased to a large extent because the heat from the flue gases, practically released into the surroundings, would be additionally used – Miloš Milić emphasizes.

The original manufacturer of the boiler, „Rafako” from Poland, had been consulted about such concept and they were surprised at the offered solution, too. After three months of studious work, they defined it as very effective, efficient and applicable. Within the first phase of the capital overhaul which lasted for six months, in addition to the installation of a new feeder, a third economizer, a mixer, the necessary control systems, the evaporator of the boiler was also replaced on all four sides from the elevation 72 to 114 meters, and this with the inner diameter of the pipe increased by one millimetre so as to further reduce the resistance in the water-steam system. Several overheaters and reheaters were also replaced, having been worn. Milić particularly emphasizes that the new solution for increasing the power and efficiency of the block B1 has been operating successfully for more than a year and a half, and the effects after its implementation are, as he says, more positive and bigger than those envisaged by the design.

– The efficiency of the boiler has been increased by three percent, the efficiency of the turbine driven set has been reduced by 0.3 percent, the efficiency of the block has been increased by more than 1.5 percent. This has already been achieved in the first year of operation after the capital overhaul. Expressed in the language of money, after the first phase of the capital overhaul, due to the increased efficiency, TENT B1 makes a profit of three million euros per year. Owing to the increased power and the higher production, annually, an additional profit of 15 to 17 million euros is made depending on the block utilization, so that it can be said that the total effects are around 20 million euros – Miloš Milić says.

Our interlocutor points out that, in the following period, as soon as possible, the  same concept should also be implemented on TENT B2, then the second phase of B1 should be conducted, and finally the entire operation should be finalized with the second phase on B2.


For the technical improvement of the block B1, the company TENT has obtained awards from the domestic and foreign professional public. First, they got the award of the Serbian Chamber of Engineers and then the Annual Award of the Belgrade Chamber of Commerce, together with the award money which the winners gave to charity. The Serbian Energy Sector Alliance awarded the „Gold medal“ to TENT experts at the 29th international symposium „Energy 2013”, held in Zlatibor.

This technical solution concept was awarded the first prize of the European professional public at the prestigious international symposium within the energy sector field „POWER GEN”, held in Vienna last year.

Source; Serbia Energy