By Sales Director, Mr. Bent Have Johnsen Aalborg Engineering A/S.

Close co-operation and exchange of solutions made it possible to make an even more efficient solution for ACHEMA AB in Jonava, Lithuania.

ACHEMA is currently in a longer investment plan which includes upgrading the processes on the factory but also to make the factory more independent of purchasing power from the grid. When the Ignalina nuclear power plant is shut down in 2010 the back bone of the power supply in Lithuania is lost.

Aalborg Engineering is therefore in the process of supplying a Combined Heat and Power plant to ACHEMA. The plant consists of a SteamGen^TM 8 Heat Recovery Steam Generator (HRSG) and a Siemens SGT 800 gas turbine. Further the necessary components in the water and steam cycle.

The original project was basically to cover for the energy supply to the fertilizer factory owned by ACHEMA. As Aalborg Engineering became more and more aware of their operational expectations we could ask them to consider various improvements to the steam cycle.  In this process we first of all made sure that the generation of power was maximized. In order to make the most efficient solution it is important to recover the heat at the right energy level. This energy level should fit the already existing steam system and thereby allow for production of power on the steam turbine. When we have made the recovery of heat at this level, we would normally go to another steam pressure level. We are only limited by the laws of physics in this process. On this project the low pressure option was not possible as no part of the production on the plant could use low pressure steam.

On many industrial sites this would mean the rest of the exhaust energy from the gas turbine would be lost. In our dialog with ACHEMA we developed the idea to produce hot water which could be sold to the district heating company in the city of Jonava.

The HRSG was further optimized with a hot water producing coil and we found that it was possible to produce app. 10 MWt to the district heating network. The limitations in this respect were the design data for the district heating system. The hot water is produced with an inlet temperature of 70 deg. C: and outlet temperature of 130 deg. C. The exhaust from the gas turbine was however reduced to 85 deg. C. which we consider to be efficient with the boundary conditions given.

It is always a pleasure to develop such a HRSG solution with focus on optimizing the overall efficiency. We are confident that the approach selected by ACHEMA will be the leading in the industry in the years to come. The discussions of climate change and ways to improve the energy technologies will continue. ACHEMA is now ready for the future. The plant will be commissioned in 2010.