1. Plan Stage

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Market Study

The first step of the process is to identify what potential materials exist within a reasonable distance of the cement plant, as transporting the materials over a long distance may not be economically viable. The potential sources could be either commercial, industrial or domestic and we have significant experience on completing such studies and knowing the kind of materials that are suitable for use in cement manufacture.

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Pre-processing Considerations

Once the potential material sources have been identified, it is essential to consider how they will be converted from their raw state into materials that could be used as fuels in a cement kiln. This may be a process of sorting the material, drying, size reduction etc. We have experience in the definition and design of the pre-processing stage as well as the considerations of whether this is a stage that could be completed by the cement manufacturer themselves or by a third party supplier already involved in the collection and handling of the materials.

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Fuels Chemical and Physical Specification

The chemical and physical specification of the fuel is extremely important, as it will dictate issues such as point of injection, equipment design, impact on the process, the environment and the final product. The specification that is formulated must be achievable and deliverable by the suppliers in the volumes required for the life of the project. The IMC experts can evaluate any alternative fuel specification and make recommendations with regard to either chemical or physical characteristics that could result in difficulties during any trials and in longer term usage.

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Process Impact

Once the specification is confirmed, the impact upon areas such as output, fuel consumption, fan power, build-up in the system and by-pass requirement can be predicted. This information is invaluable before any trials are started. The results of this study may then be used to modify the specification, as well as being used in the capital case for the project and areas such as redesigning the raw mix to take account of the changes in the fuel inputs.

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Emissions Prediction

As environmental legislation has become more strict, the regulators want to know the impact of the alternative fuel on the plant emissions. The prediction of the changes in the emissions of gases such as NOx, SO2 and CO2 as well as the minor pollutants can be assessed by IMC. The CO2 relating to the biomass. Component of the fuels can be calculated and used in the justification for carbon credits and/or exclusion from the annual CO2 emissions from the plant.

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Product Quality Impact

Despite using an alternative fuel, the primary purpose of the plant is still to produce cement. Minor elements in the cement manufacturing process can have a significant impacts on the properties of the cement such as colour or setting time. With the knowledge of the substitution rate and the specification, IMC can predict any the final composition of the cement and therefore identify potential problems in the final product quality and potential solutions.

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Public Relations Planning

One of the biggest challenges to overcome is the reaction of the local community to the introduction of an alternative fuel, which are often classified as wastes. Often, the fuels are designed to a strict specification and are “cleaner” than fuels such as coal. However, the perception is that they present an Environmental and Health and Safety threat to the local population. The success or failure of a cement plants public relations planning will have an impact for many years and will have a strong bearing on the success of subsequent alternative fuels implementations. 

 

IMC can assist in understanding the local perspective, who the key influencers are in the community (and broader legislative context) and that need to be targeted as part of the campaign. The objectives of the use of the alternative fuels programme and company policy on alternative fuels can be designed and presented to the key influencers in the community.

 

Financial analysis

The use of an alternative fuel by a cement manufacturer has to be financially viable, at least in the medium term (as the positive economics of each fuel has a limited timescale). Financial analysis will be required to identify the returns on the project as well as justifying the cost of the equipment for project. IMC has the expertise to build the financial model for the trial and long term use, taking into account factors such as changes in fuel consumption, loss of output, any new materials such as cement modifiers as well as the benefits of negative fuel costs. Different scenarios can be modelled to identify the sensitivity of the programme.

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Fuels Quality Control

It is important to know the actual composition of each batch of fuels that are burnt, as many specifications will have a range to which the supplier must comply. The legislation in some countries requires samples of each load of material that is used to be analysed, such that there is traceability. For the cement producer it is also important to ensure that the material meets the specification. IMC can advise on the requirements for the sampling and storage of samples and the type of laboratory that is required for the full range of alternative fuels that may be considered.

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Health and Safety

As with an new material that is brought onto the cement plant, the Health and Safety implications and regulations relating to the alternative fuels must be considered. Measures such as storage type and capacity, firefighting measures, personal protective equipment, spillage procedure etc. can all be addressed by IMC.

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2. Design Stage

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Injection Point Definition

The specification of the fuel will dictate where in the process the fuel can be be injected for the optimum burning conditions and substitution levels to be achieved. Certain fuels require a long residence time to fully burn out, whilst others require a specific temperature to ensure complete combustion and for others their physical characteristics prevent them from being used in certain places in the plant. The optimum may be through the main burner pipe or into the calciner – either through the calciner burner or through a series of chutes and flap valves. IMC will complete the necessary calculations relating to the fuel and use this information, along with its experience, to confirm the optimum injection point or points for the fuel. CFD analysis is often used at this stage of the process and this can be completed through third party suppliers known to IMC Consulting.

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Storage, Handling and Dosing System

The chemical and physical characteristics of the fuel will dictate the necessary storage and transport system that will be best suited to the fuel, and the ideal dosing system that will avoid blockages and also allow the fuel to be accurately measured. IMC will define the requirements of the system and can evaluate the proposals from the various equipment suppliers for the installation – both from a technical and financial point of view.

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3. Implementation Stage

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Fuels Commissioning

IMC will provide the necessary resources to assist in the commissioning of the equipment up to the target substitution level defined by the plant. Prior to the commissioning, training can be provided to the plant operators, as well as an experienced control room operator being part of the commissioning team to support the kiln burners with the new burning conditions. IMC can also provide process engineering assistance to support the control room operators and the plant process engineer who is evaluating the commissioning of the new fuel.

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Alternative Fuels Troubleshooting

Circumstances can change on a cement plant that affect the kiln stability such as raw materials changes, modifications that occur during the annual repair or even external factors such as changes in the environmental legislation. In these circumstances, the effects of the changes on the process or on emissions must be understood so that the plant can be returned to optimum operating conditions. IMC can provide technical support to troubleshoot any issue relation to any of the specific areas already mentioned within this scope of services.