AAK Zaandijk more efficient through the years

AAK (AarhusKarlshamn) will reduce its energy consumption per tonne of product to about one third of the energy consumption in 1998. This improvement in energy efficiency is a result of targeted study and attention on energy in close cooperation with the energy consultants of Epro Consult. AAK is a edible oil processing company with sites throughout the world and has its headquarters in Sweden.

How does AAK succeed in making such a huge steps in energy efficiency improvement?

Energy management

By a step by step approach and structural analyses of the energy consumption AAK has worked on energy efficiency. In this process, which took several years the knowledge and experience of AAK employees has been combined with the expertise of Epro Consult. As one of the first companies in this industrial branche AAK has implemented energy management (dating from 1990). By keeping the attention focussed and integrating energy management in the organisation energy has been an important issue in the daily production activities for many years.

Less energy consumption

By making an inventory of the energy consuming units and subsequently analysing the way energy is consumed it was possible to track areas that could be improved. The starting point was first to reduce the energy consumption if possible. This could partly be achieved without large investment cost (e.g. insulation measures), partly investments with an acceptable pay back period were necessary. AAK was one of the first companies to apply the newly developed dry condensing units in its deodorisation (removal of fatty acids and other components from the edible oil).

In order to remove components from the unrefined oil it was common practice to build a vacuum based on steam ejectors. The fatty acids and other components removed end up in the waste water flow. By applying dry condensing the vapours from the oil are condensed by cooling these in specially designed heat exchangers. In the latter case these compounds can be recovered and used as by-products for other applications.

In other parts of the processes energy was saved by replacing steam ejectors by vacuum pumps for maintaining a vacuum in the processes. Although the steam demand was reduced substantially the electricity consumption did not increase as much as expected.

Waste heat utilisation

The next step in improving the energy efficiency has been made by analysing waste heat available and finding heat sinks to apply this waste heat. Epro Consult has made a customised simulation model for AAK, named ProcSim. Analysing the process data of all (batch) processes by using the simulation model has played a major role in determining which waste heat sources could be used. This resulted in a network of heat exchangers that has been installed and mainly uses waste heat form the deodorisation processes. The challenge at AAK is to recover waste heat from batch processes and apply the heat recovered in these batch processes. Because the heat demand and the heat supply are matching in time a hot water buffering system was needed. The project is in its implementation phase and will result in an energy efficiency improvement of about 22% compared to the year 2011.

Optimising the heat supply (utilities)

Because of all changes in the heat demand the next focus is on improving the energy efficiency of the steam and hot water generation. AAK energy demand has changed rapidly from the 1990’s till now. The steam boilers that have been in operation since then have become far too large for the present and expected steam demand. Due to the batch operation peak demands will always occur. The final steam demand will be less because some of the processes that are now connected to the steam grid do not need steam, since the temperature level is such that the heat can also be supplied by hot water. The resulting steam and hot water system has been studied and will be optimised. The heat supply will consist of smaller steam boilers, a hot water system and part of the heat will be supplied by the heat recovery system.

Chain optimisation, transport and renewable energy

Apart from process efficiency measures AAK has looked into chain optimisation and possibilities to optimise transport and apply renewable energy. By investing in a tank truck cleaning facility on site tank trucks can be cleaned without moving to and from Zaandam. This has saved time and reduces emissions and in addition less tank truck movements in the area. This tank truck cleaning also uses waste heat from the processes, which reduces primary energy consumption as well.
AAK has planned to purchase all electricity and natural gas from renewable sources. AAK will have a CO2-neutral operation at Zaandijk.

Roadmap

All steps described before do not exclude further optimisation at AAK. There still are several opportunities for improvement, these vary from implementing new technology to optimisation of processes and process settings.

A summary of the way AAK has dealt with energy efficiency improvement:

1. Implementing and maintaining an energy management system
2. Reducing energy consumption
3. Waste heat utilisation
4. Optimising energy supply and utilities
5. Chain optimisation, optimising transportation, purchasing renewable energy
6. Applying new technology and continuously optimising processing.

In all these steps AAK has closely worked together with Epro Consult, a cooperation that has proven to be successfull!