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The MultiDrive: A safeguard against total failure

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Thanks to the electrical and mechanical redundancy, the mill can continue to run even in the unlikely event of the failure of a drive unit with the MultiDrive drive system.

The MultiDrive drive system that has proved successful in practice since 2009 was developed by Gebr. Pfeiffer in conjunction with Siemens/Flender specifically for driving the MVR vertical roller mill (Fig 1). Unlike virtually any other mill drive system the MultiDrive offers maximum availability and therefore provides the greatest possible security against possible total failure (Fig 2). The mill is driven through a girth gear flanged to the grinding bowl by up to six actively redundant drive units with a total output of up to 18,000 kW (Fig 3), each consisting of an electric motor, coupling and gear unit. The use of this drive system means that the gear units are not exposed to the grinding forces (Fig 4). Thanks to the electrical and mechanical redundancy the mill can continue to run even in the unlikely event of the failure of a drive unit. Driving the MVR vertical roller mill with a MultiDrive represents a crucial step forward not just because of the opportunity for transmitting high drive ratings. The MVR vertical roller mill equipped with the MultiDrive drive system is still available for operation even if a roller has to be taken out of the grinding process. The advantages are no unplanned stoppages and a very high production capacity at all times. The installation of just one mill achieves availabilities and outputs that would otherwise require two vertical roller mills set up in parallel.

Completed plants, tests and operating results
Since their introduction in 2009 [1] the MVR mills equipped with the MultiDrive drive system have been submitted to tests and extensive operating experience has been gathered.

  • A pilot plant equipped with a MultiDrive with three drive units in an MPS 4750 BC vertical roller mill was commissioned in 2009 in a cement plant belonging to HolcimLafarge in France.

  • This pilot plant and the subsequent operational plants (Table 1) were submitted to intensive testing.

  • The tests and analyses led to ongoing improvements to the MultiDrive drive system.
    At the same time a modular MultiDrive construction system was developed with different sizes of grinding bowl support systems.

  • There are now five MultiDrive drives in operation with variable speed adjustment and one MultiDrive drive with fixed speed is being delivered. So far 31 KMRS 220 gear units were built.

The MultiDrive drive system is an alternative drive system for vertical roller mills that now combines long-term operating experience with great operating results. The drive system was systematically improved against the background of the experience that had been obtained. The operating experience and test results are described using three examples of different mill sizes.

MPS 4750 BC vertical roller mill at Val de Seine, France
The mill is driven through a MultiDrive drive system equipped with three drives with a total installed rating of 4 350 kW.

Investigation: The mill was operated for several days with (n-1) drives during which the displacement of the drive flange was measured.

Results

  • The direction of displacement was established as assumed and a smaller displacement than expected was measured (Fig. 5).
  • There were no problems with continuous operation in this operating state.
  • From stopping the mill to re-starting it the time taken for disengaging a drive was 8 h.

MVR 5600 C-4 vertical roller mill in Balaji, India
The mill is driven through a MultiDrive drive system consisting of four drives with a total installed rating of 6 600 kW.
Investigation: The mill was operated with (n-1) rollers. The roller was raised and secured. Various measurements were carried out during the operation with (n-1) rollers.

Results

  • Operation with (n-1) rollers was, as expected, possible.
  • Apart from the output the process engineering parameters were unchanged. The output achieved was 85 per cent.
  • The fluctuations in power consumption, rotational speed, current input and measured torque were higher than during the operation with all rollers. The torque fluctuations, for example, rose from ? 10 to ? 20 per cent.
  • The smoothness of running proved to be practically unchanged.
  • The displacement of the drive flange of the grinding bowl support system was as expected (Fig. 6).
  • No abnormalities were detected in the pad bearing pressures, e.g. pressure irregularities due to bearing displacement.
  • There were no problems with continuous operation in this operating state.

MVR 6700 C-6 vertical roller mill at Barroso, Brazil
The Barroso MVR 6700 C-6 vertical roller mill in Brazil is the most powerful vertical roller mill in operation that is used for grinding cement. The mill is driven by a MultiDrive drive system with six drives with a total installed rating of 11,500 kW. The MultiDrive is equipped with frequency converters that allow the grinding bowl speed to be adjusted to suit the different product grades.

Since April 2016 the mill has been in operation to the complete satisfaction of the operator, who reported in a lecture in December 2016 in Fort Lauderdale on the remarkable quietness of running of the MVR mill [2] and emphasized the flexibility of the plant that makes it possible to product a wide variety of types of cement. The progress of the commissioning of the grinding plant was also described as very satisfactory so that after only 79 operating hours the mill could be operated without the presence of a GP supervisor.

The capital investments costs (CAPEX) for the new cement production line in the cement plant belonging to the HolcimLafarge Group were reduced by about 25 per cent through the use of the MVR mill with MultiDrive.

The MultiDrive? against the background of specific customer demands

Demands based on the example of large cement mills (> 9 000 kW): According to Harder [3], vertical roller mills with installed drive ratings of up to 5 000 kW lie in the small to medium power range, mills with drive ratings of 5,000 to 9,000 kW are classified as large mills and above this are very large mills.

In projects where the mills have drive ratings > 9,000 kW the standard for mill suppliers has been set very high: high outputs with reduced production costs and increased efficiency with the ability to produce different blended cements under conditions of comparatively low total investment. In addition to this it is necessary to fulfill the demands for very high plant availability and sophisticated maintenance schemes so that the cost per tonne of cement produced can be kept permanently at a fairly low level. Today’s customers favour the one-line principle to fulfil the requirement for low total investment, but only on the condition that total failure of cement production can be ruled out by guaranteeing excellent availability of the grinding system.

The total drive power of 11,500 kW needed to obtain an output of 450 t/h in the example of the "Barroso" mill cannot be achieved with conventional drive systems. Gebr. Pfeiffer is now in the position to offer the most suitable drive solution for this and comparable requirements at the lowest possible CAPEX costs.

Advantages of the MultiDrive multiple drive system
The customers’ demands can be met individually through carefully developed and well engineered strategies so that the MultiDrive drive system combines the advantages:

Modularity

  • 2, 3, 4, 5 or 6 identical drive units, each consisting of motor, coupling and gear unit, drive the girth gear of the grinding bowl support system with a total installed rating of up to 18 000 kW.
  • KMRS 2200 and KMRS 2540 gear units are used in the drive units. Engineering
  • Patented innovative solutions.
  • Drive of the grinding bowl with variable or constant rotational speed.
  • The MultiDrive? drive system represents a successful solution for driving the MVR vertical roller mill and the use of space-saving twin supports means that there are also appropriate lanes for removing the grinding bowl support system.
  • The radial bearing using pivoted shoe technology is dimensioned to take dynamic radial forces from the grinding operation as well as static radial forces from operation with (n-1) rollers and (n-1) drives.

Active redundancy: The MultiDrive? drive system increases the MVR vertical roller mill’s great potential. Operation of the mill with (n-1) rollers and (n-1) drives was verified successfully during the test operation. The MVR vertical roller mill has a high degree of mechanical and electrical redundancy and, in contrast to mills and drive systems in which the failure of a single component leads to a production stoppage, can maintain production operation.

Space- and cost-saving design: The use of the MultiDrive drive system facilitates the lowest overall height of all the mill drive systems on the market and means that the MVR grinding plants can be built very compactly and economically.

The grinding forces act on the base with a small lever arm and are directed conveniently into the foundation.

Flexible through variable grinding speed: The MultiDrive drive system can, if required, be operated at varying speeds using frequency converters. In many cases it is possible to dispense with the speed control but a frequency converter can be retrofitted at any time if the requirements change.

Simple maintenance: The drive units are positioned radially on mounts so they are easy to pull out from under the mill and can then be picked up with a crane. With a maximum weight of 25 t per KMRS- 2200 drive unit this ensures comparatively greater ease of maintenance.

Efficient stock-holding: The stock-holding is simpler and more economical due to the simple modular design based entirely on standard components. A drive unit can also be used in other mills that are driven by a MultiDrive drive system.

Optimum plant profitability (ROI, TCO): Unlike any other mill drive system, unplanned stoppage times are reduced to a minimum. Even with unplanned stops the one-mill solution using an MVR vertical roller mill, when compared with a two-mill solution, gives a better rate of return in the long term thanks to its high level of availability.

Costs/ROI: An examination of costs shows that the use of the MVR vertical roller mill equipped with the MultiDrive drive system is also characterized by a favourable cost/benefit ratio. This is shown in ?Table 2 and ?Fig 7 based on the example of an MVR cement mill with six rollers and an output of 270 t/h when compared with a mill of the same capacity with three grinding rollers. If one of the six rollers in the MVR mill has to be taken out of operation for maintenance reasons the output falls to 84 (?Fig. 8). If, with the other mill with three rollers, one roller is taken out of operation then the mill can no longer be operated – the output drops to zero. With a basic cement price of $60/t and an assumed outage time of five days there is a loss of sales revenue with the MVR mill equipped with the MultiDrive drive system of about $3,00,000. For the competitor mill it is almost $20,00,000.

Differentiation from other drive systems
In conventional mill drives the gear unit not only transmits the power from the motor to the grinding bowl but also carries the grinding forces down into the foundation. The MultiDrive drive system is currently the only drive solution on the market that separates these two processes. The advantage is that there is no additional loading by axial and radial grinding forces.

Harder [3] also counts the COPE drive from Renk [4] among the multiple drives. The COPE-Drive builds up high and slim, so that it can pass through the narrow gap between the single support (?Fig.8) With the comparatively clean MultiDrive-concept, there are not many single components under the mill where the access is very difficult, so that with the MultiDrive it is, for example, simpler to remove a motor (Fig 9 & 10).

A robust and flat grinding bowl support system is used for the MVR grinding bowl through the use of space-saving twin supports as there is sufficient space for its installation and removal. This grinding bowl support system is capable of taking static radial forces from the operation of the mill with (n-1) rollers and (n-1) drives (see Fig. 4). Dynamic radial forces amounting to 30 per cent of the axial force are also taken in accordance with the customer’s design criteria.

The advantages of driving the MVR vertical roller mill with a MultiDrive were verified in tests on operating plants. Even with very large production units a level of availability never previously obtained is achieved through the active redundancy of the mill and MultiDrive. Apart from the comparatively favourable total investment cost the implementation of the one-mill technology is therefore very important for the grinding plants in both the raw meal and cement departments. Figs. 11 and 12 show the MultiDrive drive system in the cement mills at HolcimLafarge’s Biskra and Barroso cement plants..

Outlook
An MVR vertical roller mill, driven by a MultiDrive with four drives, is currently being delivered to a cement plant in Cambodia and a mill driven by a MultiDrive with four variable-speed drives is being processed for a customer in Pakistan. Not only the advantages with the OPEX costs but also optimized CAPEX costs have become apparent now that the MultiDrive drive system has been examined from the value analysis point of view.

References
[1]Hoffmann, D.; Reichardt, Y.; Sch?tte, K.-H.: The MVR vertical roller mill plus MultiDrive? a successful combination. CEMENT INTERNATIONAL 9 (2011) No. 2, pp. 44-19.
[2]HolcimLafarge-Vortrag auf dem "Gebr. Pfeiffer ready- 2grind Technical Panel", Fort Lauderdale, Dec 2016.
[3]Harder, J.: Drives for large vertical roller mills. ZKG International (2017) No. 1/2, pp. 32-39.
[4]Broschure of Renk about the COPE-Drive, edition 02.2015.
[5]XXXI Congresso Tecnico FICEM. Federacion Interamericana del Cemento, Santo Domingo, Republica Dominicana, 2014.
[6]19th Arab International Cement Conferenz and Exhibition, November 2014.

– The article is authored by D. Hoffmann, L. Schmitt, Gebr. Pfeiffer SE, Kaiserslautern, Germany

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Economy & Market

Impactful Branding

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Advertising or branding is never about driving sales. It’s about creating brand awareness and recall. It’s about conveying the core values of your brand to your consumers. In this context, why is branding important for cement companies? As far as the customers are concerned cement is simply cement. It is precisely for this reason that branding, marketing and advertising of cement becomes crucial. Since the customer is unable to differentiate between the shades of grey, the onus of creating this awareness is carried by the brands. That explains the heavy marketing budgets, celebrity-centric commercials, emotion-invoking taglines and campaigns enunciating the many benefits of their offerings.
Marketing strategies of cement companies have undergone gradual transformation owing to the change in consumer behaviour. While TV commercials are high on humour and emotions to establish a fast connect with the customer, social media campaigns are focussed more on capturing the consumer’s attention in an over-crowded virtual world. Branding for cement companies has become a holistic growth strategy with quantifiable results. This has made brands opt for a mix package of traditional and new-age tools, such as social media. However, the hero of every marketing communication is the message, which encapsulates the unique selling points of the product. That after all is crux of the matter here.
While cement companies are effectively using marketing tools to reach out to the consumers, they need to strengthen the four Cs of the branding process – Consumer, Cost, Communication and Convenience. Putting up the right message, at the right time and at the right place for the right kind of customer demographic is of utmost importance in the long run. It is precisely for this reason that regional players are likely to have an upper hand as they rely on local language and cultural references to drive home the point. But modern marketing and branding domain is exponentially growing and it would be an interesting exercise to tabulate and analyse its impact on branding for cement.

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Concrete

Indian cement industry is well known for its energy and natural resource efficiency

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Dr Hitesh Sukhwal, Deputy General Manager – Environment, Udaipur Cement Works Limited (UCWL) takes us through the multifaceted efforts that the company has undertaken to keep emissions in check with the use of alternative sources of energy and carbon capture technology.

Tell us about the policies of your organisation for the betterment of the environment.
Caring for people is one of the core values of our JK Lakshmi Cement Limited. We strongly believe that we all together can make a difference. In all our units, we have taken measures to reduce carbon footprint, emissions and minimise the use of natural resources. Climate change and sustainable development are major global concerns. As a responsible corporate, we are committed with and doing consistent effort small or big to preserve and enrich the environment in and around our area of operations.
As far as environmental policies are concerned, we are committed to comply with all applicable laws, standards and regulations of regulatory bodies pertaining to the environment. We are consistently making efforts to integrate the environmental concerns into the mainstream of the operations. We are giving thrust upon natural resource conservation like limestone, gypsum, water and energy. We are utilising different kinds of alternative fuels and raw materials. Awareness among the employees and local people on environmental concerns is an integral part of our company. We are adopting best environmental practices aligned with sustainable development goals.
Udaipur Cement Works Limited is a subsidiary of the JK Lakshmi Cement Limited. Since its inception, the company is committed towards boosting sustainability through adopting the latest art of technology designs, resource efficient equipment and various in-house innovations. We are giving thrust upon renewable and clean energy sources for our cement manufacturing. Solar Power and Waste Heat Recovery based power are our key ingredients for total power mix.

What impact does cement production have on the environment? Elaborate the major areas affected.
The major environmental concern areas during cement production are air emissions through point and nonpoint sources due to plant operation and emissions from mining operation, from material transport, carbon emissions through process, transit, noise pollution, vibration during mining, natural resource depletion, loss of biodiversity and change in landscape.
India is the second largest cement producer in the world. The Indian cement industry is well known for its energy and natural resource efficiency worldwide. The Indian cement industry is a frontrunner for implementing significant technology measures to ensure a greener future.
The cement industry is an energy intensive and significant contributor to climate change. Cement production contributes greenhouse gases directly and indirectly into the atmosphere through calcination and use of fossil fuels in an energy form. The industry believes in a circular economy by utilising alternative fuels for making cement. Cement companies are focusing on major areas of energy efficiency by adoption of technology measures, clinker substitution by alternative raw material for cement making, alternative fuels and green and clean energy resources. These all efforts are being done towards environment protection and sustainable future.
Nowadays, almost all cement units have a dry manufacturing process for cement production, only a few exceptions where wet manufacturing processes are in operation. In the dry manufacturing process, water is used only for the purpose of machinery cooling, which is recirculated in a closed loop, thus, no polluted water is generated during the dry manufacturing process.
We should also accept the fact that modern life is impossible without cement. However, through state-of-the-art technology and innovations, it is possible to mitigate all kinds of pollution without harm to the environment and human beings.

Tell us about the impact blended cement creates on the environment and emission rate.
Our country started cement production in 1914. However, it was introduced in the year 1904 at a small scale, earlier. Initially, the manufacturing of cement was only for Ordinary Portland Cement (OPC). In the 1980s, the production of blended cement was introduced by replacing fly ash and blast furnace slag. The production of blended cement increased in the growth period and crossed the 50 per cent in the year 2004.
The manufacturing of blended cement results in substantial savings in the thermal and electrical energy consumption as well as saving of natural resources. The overall consumption of raw materials, fossil fuel such as coal, efficient burning and state-of-the-art technology in cement plants have resulted in the gradual reduction of emission of carbon dioxide (CO2). Later, the production of blended cement was increased in manifolds.
If we think about the growth of blended cement in the past few decades, we can understand how much quantity of , (fly ash and slag) consumed and saved natural resources like limestone and fossil fuel, which were anyhow disposed of and harmed the environment. This is the reason it is called green cement. Reduction in the clinker to cement ratio has the second highest emission reduction potential i.e., 37 per cent. The low carbon roadmap for cement industries can be achieved from blended cement. Portland Pozzolana Cement (PPC), Portland Slag Cement (PSC) and Composite Cement are already approved by the National Agency BIS.
As far as kilogram CO2 per ton of cement emission concerns, Portland Slag Cement (PSC) has a larger potential, other than PPC, Composite Cement etc. for carbon emission reduction. BIS approved 60 per cent slag and 35 per cent clinker in composition of PSC. Thus, clinker per centage is quite less in PSC composition compared to other blended cement. The manufacturing of blended cement directly reduces thermal and process emissions, which contribute high in overall emissions from the cement industry, and this cannot be addressed through adoption of energy efficiency measures.
In the coming times, the cement industry must relook for other blended cement options to achieve a low carbon emissions road map. In near future, availability of fly ash and slag in terms of quality and quantity will be reduced due to various government schemes for low carbon initiatives viz. enhance renewable energy sources, waste to energy plants etc.
Further, it is required to increase awareness among consumers, like individual home builders or large infrastructure projects, to adopt greener alternatives viz. PPC and PSC for more sustainable
resource utilisation.

What are the decarbonising efforts taken by your organisation?
India is the world’s second largest cement producer. Rapid growth of big infrastructure, low-cost housing (Pradhan Mantri Awas Yojna), smart cities project and urbanisation will create cement demand in future. Being an energy intensive industry, we are also focusing upon alternative and renewable energy sources for long-term sustainable business growth for cement production.
Presently, our focus is to improve efficiency of zero carbon electricity generation technology such as waste heat recovery power through process optimisation and by adopting technological innovations in WHR power systems. We are also increasing our capacity for WHR based power and solar power in the near future. Right now, we are sourcing about 50 per cent of our power requirement from clean and renewable energy sources i.e., zero carbon electricity generation technology. Usage of alternative fuel during co-processing in the cement manufacturing process is a viable and sustainable option. In our unit, we are utilising alternative raw material and fuel for reducing carbon emissions. We are also looking forward to green logistics for our product transport in nearby areas.
By reducing clinker – cement ratio, increasing production of PPC and PSC cement, utilisation of alternative raw materials like synthetic gypsum/chemical gypsum, Jarosite generated from other process industries, we can reduce carbon emissions from cement manufacturing process. Further, we are looking forward to generating onsite fossil free electricity generation facilities by increasing the capacity of WHR based power and ground mounted solar energy plants.
We can say energy is the prime requirement of the cement industry and renewable energy is one of the major sources, which provides an opportunity to make a clean, safe and infinite source of power which is affordable for the cement industry.

What are the current programmes run by your organisation for re-building the environment and reducing pollution?
We are working in different ways for environmental aspects. As I said, we strongly believe that we all together can make a difference. We focus on every environmental aspect directly / indirectly related to our operation and surroundings.
If we talk about air pollution in operation, every section of the operational unit is well equipped with state-of-the-art technology-based air pollution control equipment (BagHouse and ESP) to mitigate the dust pollution beyond the compliance standard. We use high class standard PTFE glass fibre filter bags in our bag houses. UCWL has installed the DeNOx system (SNCR) for abatement of NOx pollution within norms. The company has installed a 6 MW capacity Waste Heat Recovery based power plant that utilises waste heat of kiln i.e., green and clean energy source. Also, installed a 14.6 MW capacity solar power system in the form of a renewable energy source.
All material transfer points are equipped with a dust extraction system. Material is stored under a covered shed to avoid secondary fugitive dust emission sources. Finished product is stored in silos. Water spraying system are mounted with material handling point. Road vacuum sweeping machine deployed for housekeeping of paved area.
In mining, have deployed wet drill machine for drilling bore holes. Controlled blasting is carried out with optimum charge using Air Decking Technique with wooden spacers and non-electric detonator (NONEL) for control of noise, fly rock, vibration, and dust emission. No secondary blasting is being done. The boulders are broken by hydraulic rock breaker. Moreover, instead of road transport, we installed Overland Belt Conveying system for crushed limestone transport from mine lease area to cement plant. Thus omit an insignificant amount of greenhouse gas emissions due to material transport, which is otherwise emitted from combustion of fossil fuel in the transport system. All point emission sources (stacks) are well equipped with online continuous emission monitoring system (OCEMS) for measuring parameters like PM, SO2 and NOx for 24×7. OCEMS data are interfaced with SPCB and CPCB servers.
The company has done considerable work upon water conservation and certified at 2.76 times water positive. We installed a digital water flow metre for each abstraction point and digital ground water level recorder for measuring ground water level 24×7. All digital metres and level recorders are monitored by an in-house designed IoT based dashboard. Through this live dashboard, we can assess the impact of rainwater harvesting (RWH) and ground water monitoring.
All points of domestic sewage are well connected with Sewage Treatment Plant (STP) and treated water is being utilised in industrial cooling purposes, green belt development and in dust suppression. Effluent Treatment Plant (ETP) installed for mine’s workshop. Treated water is reused in washing activity. The unit maintains Zero Liquid Discharge (ZLD).
Our unit has done extensive plantations of native and pollution tolerant species in industrial premises and mine lease areas. Moreover, we are not confined to our industrial boundary for plantation. We organised seedling distribution camps in our surrounding areas. We involve our stakeholders, too, for our plantation drive. UCWL has also extended its services under Corporate Social Responsibility for betterment of the environment in its surrounding. We conduct awareness programs for employees and stakeholders. We have banned Single Use Plastic (SUP) in our premises. In our industrial township, we have implemented a solid waste management system for our all households, guest house and bachelor hostel. A complete process of segregated waste (dry and wet) door to door collection systems is well established.

Tell us about the efforts taken by your organisation to better the environment in and around the manufacturing unit.
UCWL has invested capital in various environmental management and protection projects like installed DeNOx (SNCR) system, strengthening green belt development in and out of industrial premises, installed high class pollution control equipment, ground-mounted solar power plant etc.
The company has taken up various energy conservation projects like, installed VFD to reduce power consumption, improve efficiency of WHR power generation by installing additional economiser tubes and AI-based process optimisation systems. Further, we are going to increase WHR power generation capacity under our upcoming expansion project. UCWL promotes rainwater harvesting for augmentation of the ground water resource. Various scientifically based WHR structures are installed in plant premises and mine lease areas. About 80 per cent of present water requirement is being fulfilled by harvested rainwater sourced from Mine’s Pit. We are also looking forward towards green transport (CNG/LNG based), which will drastically reduce carbon footprint.
We are proud to say that JK Lakshmi Cement Limited has a strong leadership and vision for developing an eco-conscious and sustainable role model of our cement business. The company was a pioneer among cement industries of India, which had installed the DeNOx (SNCR) system in its cement plant.

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Concrete

NTPC selects Carbon Clean and Green Power for carbon capture facility

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Carbon Clean and Green Power International Pvt. Ltd has been chosen by NTPC Energy Technology Research Alliance (NETRA) to establish the carbon capture facility at NTPC Vindhyachal. This facility, which will use a modified tertiary amine to absorb CO2 from the power plant’s flue gas, is intended to capture 20 tonnes of CO2) per day. A catalytic hydrogenation method will eventually be used to mix the CO2 with hydrogen to create 10 tonnes of methanol each day. For NTPC, capturing CO2 from coal-fired power plant flue gas and turning it into methanol is a key area that has the potential to open up new business prospects and revenue streams.

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