Economy & Market
Innovations in Preheater Towers
Ashwini Khunte, Martin Engineering, talks about how modern air cannon innovations are transforming preheater tower operartions.
An essential part of the cement production process is the consistent flow of bulk materials, as poor material flow can put a stranglehold on a plant’s profitability.
Accumulations in storage systems and process vessels can choke material movement, causing bottlenecks that create expensive obstacles to equipment performance and process efficiency.
Poor material flow also raises maintenance expenses, diverting manpower from core activities. If they become severe enough, flow problems can bring production to a complete stop, introducing extra risk as well as cost.
Well-designed and fitted air cannons resolve material flow issues associated with bulk handling. They are instrumental throughout cement production, from unclogging feed hoppers to moving super-heated material through the cooling process. Recent innovations in the engineering, installation, assembly and design of air cannons have been particularly effective in maintaining safe, efficient flow in preheater towers.
Air cannons function by releasing a powerful shot of pressurised air from a tank through a pipe assembly to a specialised nozzle inside the flow vessel, removing collected material from surfaces and directing it back into the process stream.
In the preheater, air cannons dislodge buildup from the walls of riser ducts, feed pipes and other locations to avoid clogging and promote the free flow of material. Before their widespread adoption, when operators detected a flow bottleneck, production would be halted and the process shut down for manual cleaning, typically by workers in high heat PPE using air lances, widely considered one of the least desirable tasks on the plant.
Modern air cannon design
The latest air cannon innovations are the result of engineers going back to the drawing board and completely reinventing the equipment so it’s more efficient, cost-effective and safer to service. Today, design advancements are producing air cannons that are more compact and lighter, with greater efficiency and power than ever.
To extend service life, high heat retractable nozzles are now available for especially abrasive locations, extending into the vessel to fire, then retracting back into the protective pipe. Both the rugged construction and reduced exposure to punishing environments extend nozzle life. They are also designed to be easily removed from a flange by a single worker and serviced as individual units outside of a Y-pipe assembly, without shutting down production, delivering unprecedented ease of access and serviceability.
At the heart of the modern air cannon system is the valve assembly, which requires regular inspection and occasional service / replacement. To avoid the need for tank removal and confined space entry, engineers have designed new cannons with outward-facing valves. This provides easy access by a single worker from outside the vessel.
To prevent the risk of unintentional firing due to sudden drops in pressure, positive-firing valves use an air pulse signal from the solenoid to trigger discharge. Safely located far from the highest heat areas, solenoids can be connected to a plant’s central control room, allowing operators to maximise results by monitoring and adjusting firing sequences from a remote location.
Conclusion
Preheater tower downtime is costly in cement processing, both from a production and energy standpoint, as well as health and safety considerations. Old air cannon solutions raise labour costs and put workers at potential risk in a horrible job that degrades morale. Today it’s common for operators to employ a long-term strategy using modern air cannon technology that improves safety, mitigates downtime, increases efficiency and reduces the overall cost
of operation.
Jignesh Kundaria, Director and CEO, Fornnax Technology
India is simultaneously grappling with two crises: a mounting waste emergency and an urgent need to decarbonise its most carbon-intensive industries. The cement sector, the second-largest in the world and the backbone of the nation’s infrastructure ambitions, sits at the centre of both. It consumes enormous quantities of fossil fuel, and it has the technical capacity to consume something else entirely: the waste our cities cannot get rid of.
According to CPCB and NITI Aayog projections, India generates approximately 62.4 million tonnes of municipal solid waste annually, with that figure expected to reach 165 million tonnes by 2030. Much of this waste is energy-rich and non-recyclable. At the same time, cement kilns operate at material temperatures of approximately 1,450 degrees Celsius, with gas temperatures reaching 2,000 degrees. This high-temperature environment is ideal for co-processing, ensuring the complete thermal destruction of organic compounds without generating toxic residues. The physics are in our favour. The infrastructure is not.
Pre-processing is not the support act for co-processing. It is the main event. Get the particle size wrong, get the moisture wrong, get the calorific value wrong and your kiln thermal stability will suffer the consequences.
The Regulatory Push Is Real
The Solid Waste Management (SWM) Rules 2026 mandate that cement plants progressively replace solid fossil fuels with Refuse-Derived Fuel (RDF), starting at a 5 per cent baseline and scaling to 15 per cent within six years. NITI Aayog’s 2026 Roadmap for Cement Sector Decarbonisation targets 20 to 25 per cent Thermal Substitution Rate (TSR) by 2030. Beyond compliance, every tonne of coal replaced by RDF generates measurable carbon reductions which is monetisable under India’s emerging Carbon Credit Trading Scheme (CCTS). TSR is no longer a sustainability metric. It is a financial lever.
Yet our own field assessments across multiple Indian cement plants reveal a sobering reality: the primary barrier to scaling AFR adoption is not waste availability. It is the fragmented and under-engineered pre-processing ecosystem that sits between the waste and the kiln.
Why Indian Waste Is a Different Engineering Problem
Indian municipal solid waste is not the material that imported shredding equipment was designed for. Our waste streams frequently exceed 40 per cent to 50 per cent moisture content, particularly during monsoon cycles, saturated with abrasive inerts including sand, glass, and stone. Plants relying on imported OEM equipment face months of downtime awaiting proprietary spare parts. Machines built for segregated, low-moisture waste fail quickly and disrupt the entire pre-processing operation in Indian conditions.
The two most common failures we observe are what I call the biting teeth problem and the chewing teeth problem. Plants relying solely on a primary shredder reduce bulk waste to large fractions, but the output remains too coarse for stable kiln combustion. Others attempt to use a secondary shredder as a standalone unit without a primary stage to pre-size the feed, leading to catastrophic mechanical failure. When both stages are present but mismatched in throughput capacity, the system becomes a bottleneck. Achieving the 40 to 70 tonnes per hour required for meaningful coal displacement demands a precisely coordinated two-stage process.
Engineering a Made-in-India Answer
At Fornnax, our response to these challenges is grounded in one principle: Indian waste demands Indian engineering. Our systems are built around feedstock homogeneity, the holy grail of kiln stability. Consistent particle size and predictable calorific value are the foundation of stable kiln combustion. Without them, no TSR target is achievable at scale.
Our SR-MAX2500 Dual Shaft Primary Shredder (Hydraulic Drive) processes raw, baled, or loosely mixed MSW, C&I waste, bulky waste, and plastics, reducing them to approximately 150 mm fractions at throughputs of up to 40 tonnes per hour. The R-MAX 3300 Single Shaft Secondary Shredder (Hydraulic Drive), introduced in 2025, takes that primary output and produces RDF fractions in the 30 to 80 mm range at up to 30 tonnes per hour, specifically optimised for consistent kiln feeding. We have also introduced electric drive configurations under the SR-100 HD series, with capacities between 5 and 40 tonnes per hour, already operational at a leading Indian waste-processing facility.
Looking ahead, Fornnax is expanding its portfolio with the upcoming SR-MAX3600 Hydraulic Drive primary shredder at up to 70 tonnes per hour and the R-MAX2100 Hydraulic drive secondary shredder at up to 20 tonnes per hour, designed specifically for the large-scale throughput that higher TSR ambitions require.
The Investment Case Is Now
The 2070 Net-Zero target is not a distant goal for India’s cement sector. It starts today, with decisions being made on the plant floor.
The SWM Rules 2026 are already in effect, requiring cement plants to replace coal with RDF. Carbon credit markets are opening up, and coal prices are not going to get cheaper. Every tonne of coal a cement plant replaces with waste-derived fuel saves money on one side and generates carbon credit revenue on the other. Pre-processing infrastructure is no longer just a compliance requirement. It is a business investment with a measurable return.
The good news is that nothing is missing. The technology works. The waste is available in every Indian city. The government has provided the policy direction. The only thing standing between where the industry is today and where it needs to be is the commitment to build the right infrastructure.
The cement companies that move now will not just meet the regulations. They will be ahead of every competitor that waits.
About The Author
Jignesh Kundaria is the Director and CEO of Fornnax Technology. Over an experience spanning more than two decades in the recycling industry, he has established himself as one of India’s foremost voices on waste-to-fuel technology and alternative fuel infrastructure.
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