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Reducing Emissions

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With spreading consciousness about the need to preserve the environment, there has been a renewed interest in bag houses, which help to arrest pollution.

As the country is progressing, education is spreading and people are becoming more aware about their health requirements and more forceful about their rights. Environmental laws at our end and across the world are becoming more stringent. In the last couple of years, the cement industry has been facing a tough challenge of meeting the revised environment regulations. With this backdrop, we take a fresh look at process filters.

A bag house, as it is commonly known as, is essential equipment for a cement plant. The attention paid and the involvement of top management in every aspect of the pollution-arresting device is an indication of the importance of the subject. A bag house is nothing but a dust-arresting device in the cement plant. Though it appears very simple, it a perfected engineering product. There is always a comparison between an Electrostatic Precipitator (ESP) and a bag house since both are dust-control equipment. There are locations in the plant where a bag house is preferred over ESP and there are locations where ESP will be preferred over a bag house.

Bag House Operation
Bag houses consist of filter media (bags) suspended inside a huge casing. Fans on the outside of the housing blow the dirty or polluted air through the filters, capturing the suspended particulate matter and solids on the bags and pushing clean air through the outlet. While filtering, a bag house allows the formation of a layer of particulate matter on its surface, called a dust cake. This dust cake continues to build until the thickness reaches a level where flow is sufficiently restricted; at this point, the bags are cleaned. Cleaning can be done during operation or offline, depending on the type of bag house.

As air is filtered through the bag house, (Ref to Pic. 1) the dust cake on the bag filters continually thickens. For most bag fabrics (those without a membrane coating), the cake is what does most of the filtering of the particulate matter in the air stream. A thicker dust cake increases both collection efficiency and pressure drop as the pathways through the bag become finer and also more restrictive. Cleaning mechanisms must find the right balance for this trade-off – too thorough or frequent cleaning results in a lower collection efficiency and possibly reduces bag life, but insufficient cleaning will cause excessive energy requirements for blower fans (i.e., high-pressure drops).

Bag House Design
Although the design of bag houses is typically the responsibility of the manufacturer, an understanding of the most important design criteria is helpful for making an informed selection.

The air-to-cloth ratio, also known as the superficial filtering velocity (in units of ft/min), is the most important criterion for bag house design. It is defined as the amount of air entering the bag house divided by the total surface area of the filter fabric in the bag house. This ratio determines the airflow capacity of the bag house, and must be optimised to balance the size of the bag house (capital costs) with the pressure drop (operating costs).

The differential pressure, or pressure drop, is a measure of the resistance to gas flow in the system. Bag houses with higher pressure drops require higher-powered fans to move air through the system, resulting in increased energy costs. The total differential pressure is the sum of individual pressure drops due to the fabric, particulate layer (dust cake), and bag house structure. An abnormally high pressure drop in a bag house can be caused by a number of factors relating to poor design or setup, including:

Bag Materials
The bag material is an important part of bag house design and selection, as it determines the life and effectiveness of the filter bag. Fabric filter media must be compatible both physically and chemically with the gas stream and system conditions. Selection of the correct bag material incorporates factors like particle size, operating temperature of the bag house, compatibility with gas stream chemistry, including moisture levels, acidity or alkalinity, electrostatic nature of the particles, abrasiveness of the particles, air-to-cloth ratio, fabric cost, etc. In addition to the material type, whether the fabric or material is woven (or otherwise) will affect what systems the bag is suitable for.

Non-woven materials consist of randomly placed fibres supported and attached to a woven backing. This strong construction is required for high-energy cleaning techniques like pulse jets and aggressive shakers.

Woven materials have fibres wound in uniform, repeating patterns. This construction is used for low-energy cleaning methods such as reverse air and lower-intensity shakers. The weave space affects the strength of the fabric and the permeability/capture efficiency of the filter.

Cleaning Mechanism
Bag houses are primarily classified based on the methods they use for bag cleaning. There are three different types of bag house cleaning mechanisms; each offers its own advantages for different applications. Reverse air (R/A) bag houses use continuous streams of low pressure air to remove collected solids. Bags are cleaned by back washing (reversing the air flow) within a chamber after shutting off the dirty gas flow and isolating the compartment. The recommended air-to-cloth ratio for these bag houses is between 1.75:1 and 2.5:1.

Advantages
R/A bag houses are typically compartmentalised, allowing sections to be cleaned without shutting off the whole system. The cleaning action is very gentle, which lengthens bag life. ItGC?s preferred for high temperatures due to its gentle cleaning action.

Disadvantages
Cleaning air must be filtered. It provides no effective means for removing residual dust build-up. It also requires more maintenance than other types due to dust re-entrainment on the bags.

Bag house filters selection guide, shaker
Shaker bag houses use mechanical shaking or vibrating actions to dislodge the filter cake. Bag bottoms are secured to a plate and their tops are connected to horizontal beams. These beams, driven manually or by a motor, vibrate to produce waves in the bags which shake off particulate matter. The recommended air-to-cloth ratio for these bag houses is between 2.0:1 and 2.5:1.

Advantages
It has design and operation simplicity. They can be compartmentalised to allow sections to be cleaned without shutting off the whole system.

Disadvantages
Cannot operate in high temperatures. It is also more energy- and time-intensive than other cleaning methods. Small amounts of positive pressure inside the bag can significantly reduce collection efficiency. Large footprint and space requirements, and requires a large number of bags.

Pulse-Jet
Pulse-jet (P/J) or reverse-jet bag houses use compressed streams of high pressure air to remove particulate matter. During cleaning, brief (0.1 second) pulses of air are pushed through the bag, dislodging solids which collect in a hopper below. The recommended air-to-cloth ratio for these bag houses is between 3.25:1 and 4.0:1.

Advantages
Cleaning mechanism allows P/J bag houses to be cleaned while the system is online. More complete cleaning than shaker or reverse air bag houses, lengthening bag life. It also operates at lower pressure drops and with lower space requirements.

Disadvantages
These bag houses require the use of dry compressed air. They also require special fabrics for higher temperatures. They cannot tolerate high moisture levels or humidity in exhaust gases.

Some others depend on sonic horn technology, which uses high-intensity sound waves to provide additional vibrational energy for dislodging particles.

Cleaning Sequence
When considering a bag house?s cleaning mechanism, the cleaning sequence is a particularly important factor. It determines when and how often the cleaning takes place in the system.

Intermittent cleaning requires the fan/process to be stopped at intervals while the bags are cleaned. This sequence is used for single-compartment bag houses, usually shaker types. Continuous offline cleaning involves taking individual compartments offline in turn to clean, meaning the overall process is not shut down during cleaning. This sequence is used with multiple-compartment reverse air or pulse-jet bag houses. Continuous online cleaning allows the process flow to continue during cleaning. This fully-automated sequence is typically used for pulse-jet bag houses.

The other challenge in the operations of bag house is spotting the punctured bag where use of instrumentation is common.

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Concrete

We engineer smarter systems to reduce waste

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Naveen Kumar Sharma, AVP – Sales and Marketing, Toshniwal Industries, talks about redefining instrumentation with customised, digitally enabled solutions engineered for harsh plant environments.

For over six decades, Toshniwal Industries has played a pioneering role in advancing process instrumentation for Indian manufacturing. In this exclusive conversation with Kanika Mathur, Naveen Kumar Sharma, AVP – Sales & Marketing, explains how the company designs kiln and grinding plant solutions tailored to the unique demands of the cement industry. As plants transition to higher AFR use and smarter automation, Toshniwal’s technologies offer greater reliability, accuracy and predictive insight.

Tell us how are your process instruments and condition monitoring system customised for cement kilns and grinding plant operations?
Toshniwal is a company with a legacy of over 65 years, and our experience has taught us that cement kilns and grinding units are fundamentally different in their operational demands. As an Indian company, we understand the unique requirements of Indian cement manufacturers. We work closely with our customers, engage deeply with their technical teams, and study operational challenges in real-time.
Based on these insights, we customise our solutions for both kiln and grinding applications. This tailoring is not just at a product level, but at a solution level—engineering design, instrumentation logic, and process optimisation. Our primary objective, for both the industry and our customers, is to reduce yield loss. Every customisation we implement is driven by this goal. We engineer smarter systems to reduce waste, improve consistency and increase plant reliability.
Ultimately, our solutions are built on an understanding that cement manufacturers require robust, practical and maintainable instruments. We design with this mindset so plants can operate more efficiently, with better control and higher profitability.

With the rising use of AFR, how do your solutions support thermal zone reliability and process time?
Our solutions are built around four core parameters: energy efficiency, yield loss reduction, product quality and environmental responsibility. These pillars drive our engineering decisions and define how our technologies support cement plants, especially as they adopt alternative fuels and raw materials (AFR).
We strongly believe in energy conservation. Every product we offer—whether for thermal monitoring, kiln control or flame optimisation—is engineered to improve energy performance. Reducing yield loss is another principle deeply embedded in our solutions, because production interruptions and material losses directly affect plant profitability and clinker quality.
We are also highly conscious of the end-product quality delivered by our customers to their markets. Consistency in burning, heat transfer, and thermal profiling directly influences clinker characteristics, and our instruments help maintain this stability.
Lastly, and most importantly, we care about the environment. We want to leave a greener world for the next generation. This mindset aligns with India’s digitalisation movement, advocated by our Prime Minister. Digital technologies are crucial for optimising AFR use, process stability, emissions and kiln efficiency. We are proud to contribute to this transition.
By optimising flame patterns, energy use, and pollution, our solutions deliver direct and indirect savings. Plants benefit from lower operational losses, reduced maintenance, and improved reliability, especially in pyroprocessing zones.

Tell us how do you address harsh environment challenges in cement plants, say dust, temperature, etc. with your sensor and monitoring?
This is a very important question because cement plants, steel plants, and power plants operate in extremely harsh environments. There are two major categories of specifications that we must respect while designing solutions: technical specifications and environmental specifications. Technical specifications relate to performance accuracy, measurement integrity, responsiveness and process safety. Environmental specifications, on the other hand, relate to high temperatures, heavy dust, humidity, vibrations and corrosive atmospheres. Our solutions are engineered to withstand both. We customise sensors, housings, mounting mechanisms and protective systems so that our instruments operate at 100 per cent functionality in harsh conditions. We ensure that the plant experiences minimal downtime from our systems. That is our engineering philosophy—solutions must work reliably in real-world environments, not just in ideal laboratory conditions.

What retrofit pathways do you offer for older cement lines to upgrade measurement and monitoring systems and how is the Indian market responding?
Every solution we provide is scalable and digitally adaptable. Technology evolves rapidly, and our offerings evolve with it. When we upgrade instruments or monitoring systems, we design them to integrate with existing plant infrastructure, so customers do not have to rebuild everything from scratch. Once our solution is installed, software upgrades or performance improvements can often be deployed without major cost. This ensures that customers continue to benefit from ongoing technological advancements. The Indian market has responded positively to this approach. Plant operators appreciate solutions that are future-ready and dynamic rather than static. Scalability helps them maintain competitiveness, extend asset life, and move toward smart manufacturing with confidence.

So how is your organisation leveraging digital technologies in your instrumentation portfolio for cement plants?
Digitalisation is at the core of every product we manufacture. We stand firmly behind the digital movement, not only because it represents efficiency, but because it is the direction in which the Indian industrial ecosystem is evolving. We deploy machine-vision technologies, advanced inline monitoring systems, and solutions capable of visualising the
inside of the furnace. These systems help reduce downtime, enable predictive asset management and provide actionable analytics to customers. All our technologies communicate seamlessly with Level 1, Level 2, and Level 3 automation. This allows integration across SCADA, DCS, ERP, and cloud ecosystems. Digitalisation for us is not an add-on—it is foundational to how our instrumentation is built.

What are your key innovation priorities to help Indian cement plant producers hit harder, higher substitution rates, lower emissions and smarter processing?
Sustainability is a national priority, and we are committed to supporting it. Our current portfolio already helps improve efficiency, reduce emissions, and support alternative fuel integration. But our innovation roadmap goes further. We are now developing specialised productivity-oriented software modules that will provide proactive alerts—not just alarms triggered after a fault has occurred. These modules will leverage artificial intelligence and machine learning to detect patterns early. The intention is to help plant teams take corrective actions ahead of time, reducing yield loss and environmental impact. Instead of informing the plant that a disruption has happened, the system will indicate that a disruption will happen, giving operators time to prevent it. We believe that within the next 12 to 18 months, we will launch these predictive solutions in combination with our instrumentation. When implemented, they will significantly improve decision-making, process stability and environmental performance across the Indian cement sector.

– Kanika Mathur

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Concrete

India donates 225t of cement for Myanmar earthquake relief

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On 23 May 2025, the Indian Navy ship UMS Myitkyina arrived at Thilawa (MITT) port carrying 225 tonnes of cement provided by the Indian government to aid post-earthquake rebuilding efforts in Myanmar. As reported by the Global Light of Myanmar, a formal handover of 4500 50kg cement bags took place that afternoon. The Yangon Region authorities managed the loading of the cement onto trucks for distribution to the earthquake-affected zones.

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Concrete

Reclamation of Used Oil for a Greener Future

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In this insightful article, KB Mathur, Founder and Director, Global Technical Services, explores how reclaiming used lubricants through advanced filtration and on-site testing can drive cost savings, enhance productivity, and support a greener industrial future. Read on to discover how oil regeneration is revolutionising sustainability in cement and core industries.

The core principle of the circular economy is to redefine the life cycle of materials and products. Unlike traditional linear models where waste from industrial production is dumped/discarded into the environment causing immense harm to the environment;the circular model seeks to keep materials literally in continuous circulation. This is achievedthrough processes cycle of reduction, regeneration, validating (testing) and reuse. Product once
validated as fit, this model ensures that products and materials are reintroduced into the production system, minimising waste. The result? Cleaner and greener manufacturing that fosters a more sustainable planet for future generations.

The current landscape of lubricants
Modern lubricants, typically derived from refined hydrocarbons, made from highly refined petroleum base stocks from crude oil. These play a critical role in maintaining the performance of machinery by reducing friction, enabling smooth operation, preventing damage and wear. However, most of these lubricants; derived from finite petroleum resources pose an environmental challenge once used and disposed of. As industries become increasingly conscious of their environmental impact, the paramount importance or focus is shifting towards reducing the carbon footprint and maximising the lifespan of lubricants; not just for environmental reasons but also to optimise operational costs.
During operations, lubricants often lose their efficacy and performance due to contamination and depletion of additives. When these oils reach their rejection limits (as they will now offer poor or bad lubrication) determined through laboratory testing, they are typically discarded contributing to environmental contamination and pollution.
But here lies an opportunity: Used lubricants can be regenerated and recharged, restoring them to their original performance level. This not only mitigates environmental pollution but also supports a circular economy by reducing waste and conserving resources.

Circular economy in lubricants
In the world of industrial machinery, lubricating oils while essential; are often misunderstood in terms of their life cycle. When oils are used in machinery, they don’t simply ‘DIE’. Instead, they become contaminated with moisture (water) and solid contaminants like dust, dirt, and wear debris. These contaminants degrade the oil’s effectiveness but do not render it completely unusable. Used lubricants can be regenerated via advanced filtration processes/systems and recharged with the use of performance enhancing additives hence restoring them. These oils are brought back to ‘As-New’ levels. This new fresher lubricating oil is formulated to carry out its specific job providing heightened lubrication and reliable performance of the assets with a view of improved machine condition. Hence, contributing to not just cost savings but leading to magnified productivity, and diminished environmental stress.

Save oil, save environment
At Global Technical Services (GTS), we specialise in the regeneration of hydraulic oils and gear oils used in plant operations. While we don’t recommend the regeneration of engine oils due to the complexity of contaminants and additives, our process ensures the continued utility of oils in other applications, offering both cost-saving and environmental benefits.

Regeneration process
Our regeneration plant employs state-of-the-art advanced contamination removal systems including fine and depth filters designed to remove dirt, wear particles, sludge, varnish, and water. Once contaminants are removed, the oil undergoes comprehensive testing to assess its physico-chemical properties and contamination levels. The test results indicate the status of the regenerated oil as compared to the fresh oil.
Depending upon the status the oil is further supplemented with high performance additives to bring it back to the desired specifications, under the guidance of an experienced lubrication technologist.
Contamination Removal ? Testing ? Additive Addition
(to be determined after testing in oil test laboratory)

The steps involved in this process are as follows:
1. Contamination removal: Using advanced filtration techniques to remove contaminants.
2. Testing: Assessing the oil’s properties to determine if it meets the required performance standards.
3. Additive addition: Based on testing results, performance-enhancing additives are added to restore the oil’s original characteristics.

On-site oil testing laboratories
The used oil from the machine passes through 5th generation fine filtration to be reclaimed as ‘New Oil’ and fit to use as per stringent industry standards.
To effectively implement circular economy principles in oil reclamation from used oil, establishing an on-site oil testing laboratory is crucial at any large plants or sites. Scientific testing methods ensure that regenerated oil meets the specifications required for optimal machine performance, making it suitable for reuse as ‘New Oil’ (within specified tolerances). Hence, it can be reused safely by reintroducing it in the machines.
The key parameters to be tested for regenerated hydraulic, gear and transmission oils (except Engine oils) include both physical and chemical characteristics of the lubricant:

  • Kinematic Viscosity
  • Flash Point
  • Total Acid Number
  • Moisture / Water Content
  • Oil Cleanliness
  • Elemental Analysis (Particulates, Additives and Contaminants)
  • Insoluble

The presence of an on-site laboratory is essential for making quick decisions; ensuring that test reports are available within 36 to 48 hours and this prevents potential mechanical issues/ failures from arising due to poor lubrication. This symbiotic and cyclic process helps not only reduce waste and conserve oil, but also contributes in achieving cost savings and playing a big role in green economy.

Conclusion
The future of industrial operations depends on sustainability, and reclaiming used lubricating oils plays a critical role in this transformation. Through 5th Generation Filtration processes, lubricants can be regenerated and restored to their original levels, contributing to both environmental preservation and economic efficiency.
What would happen if we didn’t recycle our lubricants? Let’s review the quadruple impacts as mentioned below:
1. Oil Conservation and Environmental Impact: Used lubricating oils after usage are normally burnt or sold to a vendor which can be misused leading to pollution. Regenerating oils rather than discarding prevents unnecessary waste and reduces the environmental footprint of the industry. It helps save invaluable resources, aligning with the principles of sustainability and the circular economy. All lubricating oils (except engine oils) can be regenerated and brought to the level of ‘As New Oils’.
2. Cost Reduction Impact: By extending the life of lubricants, industries can significantly cut down on operating costs associated with frequent oil changes, leading to considerable savings over time. Lubricating oils are expensive and saving of lubricants by the process of regeneration will overall be a game changer and highly economical to the core industries.
3. Timely Decisions Impact: Having an oil testing laboratory at site is of prime importance for getting test reports within 36 to 48 hours enabling quick decisions in critical matters that may
lead to complete shutdown of the invaluable asset/equipment.
4. Green Economy Impact: Oil Regeneration is a fundamental part of the green economy. Supporting industries in their efforts to reduce waste, conserve resources, and minimise pollution is ‘The Need of Our Times’.

About the author:
KB Mathur, Founder & Director, Global Technical Services, is a seasoned mechanical engineer with 56 years of experience in India’s oil industry and industrial reliability. He pioneered ‘Total Lubrication Management’ and has been serving the mining and cement sectors since 1999.

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