Energy auditing efficiently

JAMCEM was pleased to be informed two weeks ago that it had been included on the list of recommended companies for Energy Auditing by the Saudi Energy Efficiency Centre (SEEC). The Energy Efficiency Centre is in place - as its name would suggest - to promote the minimisation of fuel and power consumption across all industries within the Kingdom. For the cement industry there are two areas of focus for cement plants dependent upon whether they are existing or planned plants. For existing plants, SEEC has set the targets of 830 kcal/kg for fuel consumption and 110 kWh/tonne for power consumption, to be achieved by 2019.

The keys to any energy audit are both fully understanding the manufacturing process and creating value for the cement manufacturer. This is especially the case in Saudi Arabia where both fuel and power are extremely cheap, which makes it more challenging to find the projects that will provide an attractive payback for the customer. It is all too easy for an energy auditor to visit a plant with a list of "standard" projects taken from the internet or an academic study  - addition of a 5th cyclone stage, installation of a high efficiency separator, producing mineralised clinker or installing a waste heat recovery system. Making such suggestions add no value to the customer, as they are projects that the cement manufacturer could consider without paying a consultant to suggest them as well as offering an impossible payback period. Even worse is an auditor that focuses on the wrong areas - for example plant lighting and office air conditioning systems - which are areas which can bring improvements but in the scale of power used in the cement manufacturing process are a drop in the ocean. Sadly, this is what many "Energy Auditors" do!

A full effective energy audit needs to take into consideration the interaction of each process stage on the next - for example the impact of the crusher product size on the raw mill grinding efficiency, the raw meal residue composition (siliceous or calcareous) and the impact it has on the combinability temperature or the effect of the clinker cooling on the final product qualities. The process needs to be "balanced", so that the optimum power and fuel consumption is achieved throughout the process instead of looking at each process stage in isolation. Many companies that consider themselves capable of energy auditing will forget about the final product quality and the opportunities that exist in this area and which often present a cement manufacturer the added benefit of increasing the throughput of the plant at low capital cost.

Finally, getting it "right first time" is essential - if an energy audit is completed correctly it should provide the cement manufacturer with a road-map to improving energy efficiency with short, medium and long term actions being included in the action plan.