Co-processing of alternate fuels

Co-processing of alternate fuels

The absence of necessary infrastructure to support co-processing is one of the main reasons of its slow growth in India. There is thus, an urgent need for stakeholders to come together and evolve a national strategy and a time bound programme for building up the infrastructure, writes
SP Deolalkar.

The Indian cement industry, Number Two in the world, is modern technology-wise, and efficient in terms of energy consumption. It is consciously taking steps to bring down CO2 emissions. As a part of this effort, India has taken up co-processing of Alternate Fuels (AF) but the overall rate of substitution is very low, just about one per cent. Technologies for using various types of AFs are available and have been successfully used elsewhere with substitution rates as high 30 - 40 per cent in European countries. Absence of necessary infrastructure to support co processing is the main reason of its slow growth in India.

Volume of AFs required

Installed capacity for and actual production of cement in India is 330 and 250 mtpa respectively. About 75 per cent cements produced are blended cements. With a clinker/cement ratio of ~ 0.72, clinker production would be ~ 180 mtpa requiring 38 - 40 mtpa of raw coal. If only ten per cent of it is replaced by AF, requirement of AF would be say 3.5 - 4 mtpa. Thus, there is tremendous scope for development of AFs as a viable industry in itself. Various aspects of co-processing AFs have been brought out in the author's book 'Designing Green Cement Plants in Section 4, devoted to AFR.

Need for infrastructure

The simple reason for the need for infrastructure is to create an environment where wastes with potential as fuels (AFs) would be continuously available to cement companies preferably in ready to use form. Incidentally, using coal also requires infrastructure and processing to be able to fire it in kilns and calciners. Historically, cement companies have taken on themselves this responsibility.

In contrast to coal, AFs come from a vast number of sources, are spread over a wide territory and differ greatly in properties and availability. Identified as wastes till now, it is necessary to begin at the beginning when planning to convert them into fuels and using them. Processing required to be done varies greatly from one type of AF to the other.

Co-processing replaces fossil fuel by say, a maximum 40 per cent. A cement plant is therefore required to process two types of fuels- sometimes three - if it is required to use two types of AFs as their continuous availability is not assured as of now. Hence investments in machinery and buildings for processing AFs are considered risky. For these reasons, cement companies would prefer buying the AF that can be delivered on their doorstep in ready to use form. This in turn implies outsourcing of this activity which is a new feature. Creating such supporting facilities means creating infrastructure. An appropriate example of an infrastructure created to meet the needs of the society is 'AMUL'.

Infrastructure required for AFs

The concept of using wastes on a large scale itself being new, there is not much information on their properties, sources and locations. Infrastructure would therefore comprise of:

  • Compilation of data in the form of a directory of wastes and potential AFs among them.
  • Testing the more promising among them for determining various aspects of burning them as fuels. Pilot plant tests on the selected AFs.
  • Setting up agencies which would do handling and processing of AFs and would supply them on a commercial scale to cement (or any other) industry continuously.

Directory of wastes and their potential

The first step in the build-up of infrastructure would be to collect categorical data on wastes that could be AFs. Such data would classify wastes and other non conventional sources of fuel according to their properties, heat value, sources, locations, availability and volume/ quantity.

Such data supplemented by maps showing locations would be very useful to potential users.

Refer to the map which is similar to maps of Geological Survey of India for mineral wealth of the country.

Often this is the starting point for location of a green field cement plant. Such data should be collected on a national level and should be available for all industries and for uses other than burning also.

Research on wastes as fuels

The next step on a national scale would be to have a fuel research institute that would carry out detailed research on every aspect of combustion of likely AFs such as products of combustion, gases emitted and ashes produced. In making cement, ashes enter clinker produced. Some wastes give away harmful compounds like NOx , dioxins, heavy metals. It is important to know about them before beginning to use them on a large scale. The Central Fuel Research Institute can be one such institute and should play an important role. If not equipped now, it should be strengthened and expanded by opening branches to serve the country as a whole.

Pilot plant tests

The next step in use of AFs would be to carry out pilot plant tests in a set up that simulates actual operating conditions. All aspects of co-processing that would influence regular operation and quality of product and emissions into the environment should be carefully observed and monitored. The tests would bring out aspects like efficiency of combustion, and the extent to which AF could replace fossil fuel. They would be the basis for designing of the system for co-processing in a real plant.

Such pilot plant tests assume great significance as their results would be the basis for approval and permission for co-processing on commercial scale continuously, by government agencies like Bureau of Indian Standards and Pollution Control Boards who would be invited to witness the tests. There are only a limited number of institutions that are equipped to carry out such pilot plant tests like for example NCCBM and CRS of ACC.

Since the requirements of pilot tests would increase with number of users and types of AFs, facilities in these institutes should be made available to other cement companies, say at cost. It should not be necessary to invent the wheel every time. Tests carried out on a given type of AF, if successful should be acceptable for that type as such.

Infrastructure for bringing AFs in ready to use form

This would be regional and product-wise. It has two main constituents:

  • Collection and transport of wastes to the processor and transport of processed AF to users like cement companies.
  • Processors of wastes who receive, store, blend and process wastes as per the requirements of users.

Transport can be within a state or interstate. Transporters may specialise in transporting specific types of AFs like, sludges, hazardous wastes, MSW, etc. That is because the transporting vehicles would have to be designed to suit wastes and AFs carried. Wastes occur all over the country but certain types of waste are predominant in specific regions. Their volume could also be large enough. In that case there can be more than one Intermediate Service Provider (ISP) or processor for one type of AF. It can be the other way round also; depending on relative locations of, processors and users, supply of processed AF can be within state or interstate. A processor may prefer to deal with one or say up to three types of wastes as different wastes require different facilities for handling, storing and processing for turning them into ready for use AFs.

A very important aspect of service to be rendered as supplier of AFs is the control on quality. It begins at the origin. Only those wastes which conform to the representative character established in research stations would be lifted. At the processor's premises, it will be necessary to blend wastes as they may be from different sources from time to time or would differ in quality from same source to ensure uniformity of quality.

The processor has therefore to equip himself with necessary testing equipment to satisfy himself and his clients about the quality. He should have equipment that would do pre blending.

If the processor is thus equipped with facilities for testing at all stages of processing, the users do not have to duplicate them in their respective factory premises.

Processors will maintain stocks of wastes for processing and also stocks of processed AFs to be able to maintain continuity of supply of AFs to clients. That such an infrastructure is feasible and is beneficial to all stakeholders has been amply demonstrated by Gujarat Environment Protection Industries (GEPIL) located at Surat. There is an urgent need for many more Processors / ISPs like them if co-processing is to be speeded up.

Advantages of infrastructure

The availability of infrastructure/s as explained above has several advantages. Wastes having potential as AFs would be removed as and when generated. Societies would have cleaner environment. Processors contribute greatly in creating value for wastes by converting them into AFs and AFs would most certainly be cheaper than fossil fuels. The cement industry would thus save fossil fuels and bring down CO2 emissions further.

Conclusion

There is an urgent need for stakeholders to come together and evolve a national strategy and a time- bound programme for building up infrastructure. Generators and users can come together to form sister companies or subsidiaries that could be the processors or ISPs.

Consultants and machinery designers should join to evolve tailor made systems for co-processing different types of AFs. Once the infrastructure is in position, MoEF can stipulate minimum per cent of AF by way of co-processing.

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