Serbia: Thermal Power Plants Nikola Tesla TENT, power generation status report after floods, Ljubišа Мihаilоvić, Director for power production in TPPNT

25. June 2014. / News Serbia Energy

Floods have not incurred serious, direct damage to power plants Nikola Tesla TENT (TPPNT), but due to shortage of coal, the scope of production will be reduced and financial result will deteriorate.- Overhaul plans changed, the Business Plan amending to ensue

The aim of this year overhaul activities in the EPS company Thermal Power plants “Nikola Tesla“ has not altered nor revised, although the TPP Nikola Tesla A has stopped under the threat of the water force, and the floods in the wider production chain (production and coal dispatch) left consequences behind that cannot be easily cleared away. So, the objective was and stayed to do all that is necessary to maintain high operation reliability of thermal power units and accompanying facilities. Still, the overhaul plans have been changed, due to delay of works in time of floods and lack of coal, and also due to objective circumstances under which the activities are to take place. Instead of starting the capital overhaul on June 1, as it was originally planned, this most important work with the elements of rehabilitation of the unit A3 will commence on July 1st and it will last for 180 days, i.e. as it was envisaged to perform the full scope of planned works.

Capital overhaul will be carried out for the Unit A1, while for other parts only standard overhauls works will be performed. It should be mentioned that the debugging of faults that reduce the operation reliability of some machines, as well as construction of the system for reduction of the harmful influence of the power plant operation to the environment. Mr. Ljubiša Mihailović, Director for power production, told us all about that, in the conversation we had with him prior to floods being announced and after the floods, when the consequences were obvious.

Due to a delay of the Annual business plan of EPS, the deadlines for overhauls in 2014 were postponed for a month time, at the level of PE EPS. The floods caused a new postponement of the start. Have the public procurements procedures also slowed down and how will it all reflect on the financial aspect of overhaul activities?

The Units of TPPNT A have been shut down due to flooding occurred in the 220/380 kV substation, because the operation in such conditions would seriously endanger the safety of the equipment. Besides, not only the units were safely stopped, but also all the facilities without any damage incurred. With regards to that, the floods have not inflicted serious, direct damage to TPP, but due to lack of coal, having the mines flooded, the scope of production will be reduced, so the financial result will be worse than planned. Although the TPPNT is not to be blamed, it is clear that the amending of Business Plan must follow for this year. As far as the public procurements are concerned, we have initiated some emergency public procurement in the time of emergency situation, in order to deal with disaster consequences as soon as possible, because the branches of TPPNT – TPP Kolubara and Railway transport have been inflicted huge direct damage. Other public procurements will be carried out as planned, and they will have to be complied with the amendment of the plan. In that regard, it must be said that the start of the capital overhaul of the Unit A3 has not been delayed just because of the floods, but because of the total situation in the traffic functioning and sanitary conditions. Under the emergency circumstances it was not possible to carry out the procedure of public procurements and the deadline was postponed for a month time.

This year overhaul season in TPPNT will be marked by the capital overhaul of the Unit A3. Isn’t that the same Unit that was first rehabilitated at the beginning of this century, thanks to donations?

You are correct. The Unit A3 was under the capital overhaul in 2003. Its rehabilitation was spoken about even then, and the rehabilitation was realized out of funds of donations from the European agency for reconstruction, by the system “1:1”, i.e. to make the Unit technically operational, without any improvements and without our impact on the works. This is the oldest Unit of 300MW in our system and it is in operation since 1976. This year overhaul will have certain elements of rehabilitation given that its power will be increased to 329MW and efficiency will be increased, and also new electrical filter will be installed in order to reduce emission of dust matter and the burning coal dust facility will be reconstructed to cut the nitrogen oxide emission to the permitted level. Upon making these innovations, the Unit A3 will be operating in accordance with the European environmental standards.

Will the investments in eco-technology take the most of the 70 million euros planned for this capital overhaul?

Investments in the technology providing environmental protection represent a significant item in all segments of human activities, and especially in the power generation based on coal firing. Still, the ecological facilities within this Unit will not take much of the planned funds for overhaul. At the very Unit, large-scale and expensive works are planned, the most extensive and expensive of all operations to be done on the TPPNT Units in entirety. For example, the replacement of some heating surfaces in the boiler are envisaged, the replacement of the turbine by a new one, with better performances and higher power, and the option of working in the heating system mode. Also, the turbine regulator will be replaced with a new, modern device, and it is very important that we will replace the generator corset. This will be done for the first time in this region, and it is necessary because the corset has some faults that cannot be eliminated even in the capital overhaul. Thus it is simpler and more cost-effective to replace the entire generator corset. As a reminder, the generator corset is the active part of the generator. It is consisted of a magnetic circuit and coils of generator stator.

Hearing you making such a list of things to be done, it seems that everything on the Unit A3 will be new. Isn’t that right?

No, not everything will be new, something will be repaired, and I haven’t mentioned all things that will be replaced. Modern excitation system will replace the existing excitation system of the generator, operating since 1976. Also, we will procure a new step-up transformer for the PU operating with higher generator capacity, modernize the system for control, measuring and regulation on the Power Unit, perform capital overhaul of generator rotor and of course, repair all other facilities and devices. The intention was to make the Unit A3 significant, reliable and environmentally friendly capacity of TPPNT in the power generation process in the following 20 years.

Since this year the capital overhaul of the Unit A1 is planned, does this mean the previous plans of shutting down two Units of TPPNT A are no longer topical?

There were discussions on shutting down the Units A1 and A2 over the past ten years. In the meantime, it turned out that these two Units are not easy to be replaced by suitable new capacities, since currently we do not have such investments, and it is disputable how the heating for Obrenovac, using these two Units for heating, could be provided. Due to the current state of the Units, we are obliged to take special care of their maintenance and prolongation of their operating cycle regardless of the fact that A1 for example has been in operation since 1970. Therefore, we will do capital overhaul on this Unit in 2014, not so large as on the Unit A3, but still capital one.

What will make that overhaul capital?

We will replace all worn out parts on the turbine and at the same time preform an estimation of the remaining lifecycle of this plant. Important operations are to follow for the boiler pipeline system, where separate parts of the pipeline system of the boiler will be replaced, and what is most important in view of effectiveness increase and better operation of the electrical filters, we will improve the seals on the very boiler, so that the level of false air could be reduced, which make an adverse impact on the boiler performances. The overhaul on the Unit A1 will take some hundred days.

What do you mean by saying standard works that will be done on the majority of Units?
Having in mind that last year, due to extremely restrictive budget, very little works was done, this year we also plan to do something not included in the standard annual works. Among other things, we will try to eliminate “weak spots” to make operation safety of Units stay at the highest level. For instance, out of non-standard jobs, we planned to do the works on the system for managing the Unit B1, delivery to Siemens within the donation of the Switzerland government. The goal is to fix the faults due to which we had more breakdowns of this Unit this year than the last year.
Also the inspection of the magnetic circuit of the generator stator B2 will be done, so that we could assess what should be done to keep the reliability of this Unit operation, without many problems until it enters in the capital overhaul. Several parts on the Unit TPP Morava will be inspected also, in order to procure all required parts and equipment for the capital overhaul next year. In TPP Kolubara mainly standard overhauls works will be done, but on the Unit A1 new LP turbine blades will be installed to make the capacity of this Unit to the nominal level.
Expecting the Unit B2 to persevere

You have said that Unit B2 should persist until the time comes for the capital overhaul. What does it mean?

The general overhaul of the Unit B2 was to be carried out in 2013. This big job was, however, postponed for 2015 due to extremely hard financial situation which caused also other significant plans in EPS to be postponed. Now, after the floods, it is clear that due to reduced funds income, there will be no capital overhauls next year, and the overhaul of the Unit B2 will be moved. So much the important is to investigate and recover things what are now showing as possible cause of operation problems of this Unit, so that it could operate normally until capital overhaul. We expect the Unit B2 to keep working until this recovery takes place, since we didn’t have many important downtimes with this machine in the previous year and a half time.

How to procure the best bearings

– TPPNT will realize in total 3,500 public procurements this year. In their realization, it is most often difficult to explain that some part for some devices can be bought only from the suppliers of these devices or that because of incorporating a device in a system you have to buy it from a specific supplier. Now, one of the biggest puzzles is how to get good quality bearings for device when there are the bearings with assurances as if they are the best on the market, and we had bad experience with them. Such bidders give the lowest price, which makes them the most favourable, and we get the bearings that cannot last until the deadline expiry- says Mr. Mihailović.

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