Cogeneration: a 20 year-long practice in ZP

We have been producing combined power and heat for twenty years.

View of the gas turbine of the cogeneration unit (on the lower left); in the background, the boiler of the cogeneration unit.

The cogeneration unit, also known as steam-gas plant, replaced the outdated technology of separate electricity and steam production in 2001.

Our company became the first metallurgical factory in Slovakia equipped for the production of electricity and, as a by-product, superheated steam from natural gas.

Combined power and heat generation provides huge benefits and is a step forward. On the occasion of the plant anniversary, we interviewed Ing. Jozef Hiľovský, Head of the Energy Unit of hot rolled and cold drawn tube mills.

Mr. Hiľovský, an incredible twenty years have passed since the cogeneration unit was put into operation. How do you see its contribution from today’s point of view?

I would like to point out the fact that the definition of superheated steam as a by-product is incorrect. The operation of a cogeneration unit would be inefficient if we were to produce electricity only.

The decision to build a cogeneration unit as a replacement for the old steam boilers was based on the assumption of optimizing the use of electricity and heat within our company.

The efficiency of a cogeneration unit is connected to the year-round consumption of both electricity and heat. In the first years of operation, we were not able to consume all the heat produced in our company during the summer months, hence affecting the energy balance of the plant.

The milestone for the operation of the cogeneration unit was the year 2010. Since then, the heat produced in cogeneration is used in full. In the summer months we operate a plant that uses the excess heat for electricity production. Operating in this mode, our cogeneration unit fulfils the conditions arising from the relevant legislation and can be classified as high-efficiency cogeneration.

That means minimizing the operating costs and the impact on the environment. For these reason the benefits of a cogeneration unit is indisputable for our company.

During that period, some innovations and repairs were carried out. Can you tell us about the most demanding ones?

In principle, we can say that every four years, having reached the prescribed operating hours, a demanding maintenance session takes place on the gas turbine. The worn turbine and gearbox are replaced with a new one. The biggest innovation can be considered the updating of the gas turbine control system that took place in 2013.

The most demanding activity in terms of time and organizational complexity is the maintenance of the boiler unit. The largest boiler tubes replacement took place in 2020.

In the next few days, our skilled team will take care of the fifth turbine and gearbox substitution. We are committed to keep our cogeneration unit efficient and sound, benefiting the whole company thanks to the advantages it provides.