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Constructional explosion protection in grinding plants

Published

6 years ago

January 8, 2019

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Manoj Thakur and Berthold Bussieweke explain the importance and necessity of constructional explosion protection, which if happens once, leads to personal losses, financial losses and social defamation.

This is to be highly appreciated that nowadays in almost majority of the cement plants in India, employee safety is given topmost priority. Well recognised safety consultants and skilled agencies are appointed to educate the plant workmen and also the management about the global safety rules and standards. Not even the plant personnel, even the visitors are not allowed to walk in the plant without wearing PPEs and without attending safety related training. Lots of emphasis is given on the proper size and arrangement of working platforms with safety handrails, toe guards and walking clearances. In a nutshell, almost all the possible safety precautions are taken. However, one particular safety concern, which is mostly neglected even by the major cement manufacturing plants, is the safety against constructional explosion in coal grinding systems.

State-of-the-art constructional explosion protection e.g. in coal grinding systems as well as in alternative fuel processing and storage is nowadays regulated by international rules and directives. However, as the coal grinding system is only a part of a very large equipment scope, less attention is paid to this issue during the overall decision-making process. Non-proper design in terms of constructional explosion protection systems leads to serious consequences such as fatal injuries or injured workers during a big explosion. In recent years, several severe explosions in coal grinding systems, as well as in the processed industry of alternative fuels, have emphasised the necessity of properly-working constructional explosion protection. Therefore a.m. rules and directives should be implemented in the technical specification.

European ATEX directives divided in:
Directive 1999/92 EG relevant for operators covering the aspects of risk assessment, zoning, technical and organizational measures etc. pursuant the main target to the protection of health of workers acting in potentially hazardous areas.

Directive 2014/34/EC relevant for manufacturer of explosion protection devices covering the requirements of autonomous protection systems, components, safety and control equipment. The significance of this Directive is emphasized by the common requirements for equipment and protective systems. The part which is related to constructional explosion protection sounds as follows: "Should an explosion occur possibly endangering persons directly or indirectly (or for that matter domestic animals or property), such explosion is to be halted immediately and / or the range of explosion flames and explosion pressures to be limited to a sufficient level of safety".

EN European standards: These standards are of great significance e.g. for coal grinding systems in terms of explosion resistant equipment (EN 14460), dust explosion venting protective systems (EN 14491), explosion isolation systems (EN 15089).

A further decisive factor to have properly working constructional explosion protection in place, is generated as a result of changed coal properties in terms of high volatile fuels to be ground. Fuels of a VM content between 35 per cent and 45 per cent aren’t a rarity. In some areas in the world the use of pet coke is already banned.

Other areas will probably follow. The fact that high VM coals have the tendency of creating a smoldering fire (even in the coal yard), reflects a potential risk of an explosion in the coal grinding system. At this point, it has to be emphasised that even the milling of pet coke creates an explosive atmosphere and may lead to an explosion.

Constructional explosion protection
The issue of constructional explosion protection in coal grinding plants is very multifaceted and needs attention with regard to the following themes:
Explosion venting in combination with explosion pressure shock resistance to the relevant degree. This is mainly applicable for: Protection of bag houses ? taking the related Rule (EN 14491) into account. Apart from the coal characteristic values, K St / p max the enclosure’s pressure shock resistance is one of the decisive factors to determine the necessary area in order to sufficiently protect the bag house as part of the coal grinding system. From experience, this value of pressure shock resistance is between 100 – 400 mbar g. Additionally, the obstruction of the venting path by filter bags should be avoided right from the beginning of the design stage.

Protection of pulverised fuel silos – taking the related rule (EN 14491) into account. As a result of the cylindrical shape of such enclosures, it is quite feasible to reach a pressure shock resistance of 2 bar g (max. value as stated in the relevant rule). This maximum pressure shock resistance leads to the lowest possible venting area, depending on the efficiency factor of the venting equipment to be installed.

"Explosion venting respectively explosion de-coupling in combination with explosion pressure shock resistance to the relevant degree.

In the past, explosion risks caused by dust explosion transmission through pipes and ducts of interconnected plant in units, have caused serious damages. This scenario is generated by a secondary dust explosion, the so called "Flame-jet-ignition", which results in very high explosion pressures in the connected enclosure. To limit the extend of dust explosions and to prevent violent secondary explosions due to explosion transmission via pipes and ducts, explosion protection using suitable explosion isolation techniques, are mandatory. In coal grinding plants, the installation of explosion diverters, designed in accordance to the relevant rule have proven their efficiency.

Techniques of intelligent concepts are available in order to effectively mitigate flame front propagation in dust-laden ducts. There have been made further research in form of various successful field tests with the French notified body, Ineris. Apart from field tests, the concept is now subject to computational modelling.

The main aim is the mitigation of pressure pushing the flame front into the riser duct, in combination with the diversion of the largest possible portion of flame body. In coal grinding plants, explosion isolation measures in form of explosion diverters are mainly required. E.g. in riser ducts between mill outlet and bag house inlet as well as in any kind of ducts used as de-dusting pipes. Other mechanically-operated explosion isolation devices (e.g. rotary airlocks, double flap systems of a certain pressure shock resistant degree) are necessary as well.

Explosion pressure shock resistance for full explosion pressure: An explosion pressure shock resistant design for full explosion pressure, is always necessary where venting as well as decoupling measures aren’t feasible respectively uneconomical. Typical applications are intermediate hoppers e.g. pump pre-hoppers for pneumatic conveying systems. In coal grinding plants the full explosion pressure of 9 bar g as a design parameter is deemed as sufficient.

Self-re-closing, re-usable explosion venting devices: Self-re-closing explosion venting devices have been invented aiming at mitigating a fire inside the equipment. Mitigation respectively extinguishing of fire inside the equipment is only working effectively, provided that ingress of oxygen is prevented and the injected inerting gas e.g. CO2, N2 is kept in the system. Once open, the oxygen in the ambient air will increase the damages caused by fire while injected inerting gas is lost to the atmosphere without being effective.

Conclusion
The technical design of coal grinding systems has to be based on the latest available standards. Any non-consideration of a.m. standards may lead to fatal incidents. Scrutinising a proposed coal mill protection concept in the earliest stage of the acquisition procedure will prevent incorrect system protection. Investments in follow-up costs in terms of system’s modifications are avoided.

Storage and handling of alternative fuels as well as of biomass products play more and more an important role. The substitution rate of coal by alternative fuels/biomass is steadily increasing, provided the infrastructure of the country concerned is given. Especially the processing and handling of wood pellets, wood shavings, saw dust, etc. is growing and require special attention in terms of constructional explosion protection. Explosive specific values of wood pellets are even higher than lignite, which underlines the hazard of a violent explosion.

It requires a special mention that employee safety is not limited to PPEs and the safety slogans but much more beyond and requires to be attended more specifically in case of the constructional explosion.

ABOUT THE AUTHORS:
Manoj Thakur, Director with Techcon Consulting and Engineering, and Berthold Bussieweke is Head of Sales with Thorwesten Vent GmbH, Thorwesten Vent GmbH. Thakur can be contacted on: Manoj.thakur@techcon.co.in or +91 9892189804, while Bussieweke can be contacted on: berthold.bussieweke@thorwesten.com or +49 172 2544100.

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Price hikes, drop in input costs help cement industry to post positive margins: Care Ratings

Published

3 years ago

October 21, 2021

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Region-wise,the southern region comprises 35% of the total cement capacity, followed by thenorthern, eastern, western and central region comprising 20%, 18%, 14% and 13%of the capacity, respectively.

The cement industry is expected to post positive margins on decent price hikes over the months, falling raw material prices and marked drop in overall production costs, said an analysis of Care Ratings.

Wholesale and retail prices of cement have increased 11.9% and 12.4%, respectively, in the current financial year. As whole prices have remained elevated in most of the markets in the months of FY20, against the corresponding period of the previous year.

Similarly, electricity and fuel cost have declined 11.9% during 9M FY20 due to drop in crude oil prices. Logistics costs, the biggest cost for cement industry, has also dropped 7.7% (selling and distribution) as the Railways extended the benefit of exemption from busy season surcharge. Moreover, the cost of raw materials, too, declined 5.1% given the price of limestone had fallen 11.3% in the same aforementioned period, the analysis said.

According to Care Ratings, though the overall sales revenue has increased only 1.3%, against 16% growth in the year-ago period, the overall expenditure has declined 3.2% which has benefited the industry largely given the moderation in sales.

Even though FY20 has been subdued in terms of production and demand, the fall in cost of production has still supported the cement industry by clocking in positive margins, the rating agency said.

Cement demand is closely linked to the overall economic growth, particularly the housing and infrastructure sector. The cement sector will be seeing a sharp growth in volumes mainly due to increasing demand from affordable housing and other government infrastructure projects like roads, metros, airports, irrigation.

The government’s newly introduced National Infrastructure Pipeline (NIP), with its target of becoming a $5-trillion economy by 2025, is a detailed road map focused on economic revival through infrastructure development.

The NIP covers a gamut of sectors; rural and urban infrastructure and entails investments of Rs.102 lakh crore to be undertaken by the central government, state governments and the private sector. Of the total projects of the NIP, 42% are under implementation while 19% are under development, 31% are at the conceptual stage and 8% are yet to be classified.

The sectors that will be of focus will be roads, railways, power (renewable and conventional), irrigation and urban infrastructure. These sectors together account for 79% of the proposed investments in six years to 2025. Given the government’s thrust on infrastructure creation, it is likely to benefit the cement industry going forward.

Similarly, the Pradhan Mantri Awaas Yojana, aimed at providing affordable housing, will be a strong driver to lift cement demand. Prices have started correcting Q4 FY20 onwards due to revival in demand of the commodity, the agency said in its analysis.

Industry’s sales revenue has grown at a CAGR of 7.3% during FY15-19 but has grown only 1.3% in the current financial year. Tepid demand throughout the country in the first half of the year has led to the contraction of sales revenue. Fall in the total expenditure of cement firms had aided in improving the operating profit and net profit margins of the industry (OPM was 15.2 during 9M FY19 and NPM was 3.1 during 9M FY19). Interest coverage ratio, too, has improved on an overall basis (ICR was 3.3 during 9M FY19).

According to Cement Manufacturers Association, India accounts for over 8% of the overall global installed capacity. Region-wise, the southern region comprises 35% of the total cement capacity, followed by the northern, eastern, western and central region comprising 20%, 18%, 14% and 13% of the capacity, respectively.

Installed capacity of domestic cement makers has increased at a CAGR of 4.9% during FY16-20. Manufacturers have been able to maintain a capacity utilisation rate above 65% in the past quinquennium. In the current financial year due to the prolonged rains in many parts of the country, the capacity utilisation rate has fallen from 70% during FY19 to 66% currently (YTD).

Source:moneycontrol.com

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Wonder Cement shows journey of cement with new campaign

Published

3 years ago

October 21, 2021

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The campaign also marks Wonder Cement being the first ever cement brand to enter the world of IGTV…

ETBrandEquity

Cement manufacturing company Wonder Cement, has announced the launch of a digital campaign ‘Har Raah Mein Wonder Hai’. The campaign has been designed specifically to run on platforms such as Instagram, Facebook and YouTube.

#HarRaahMeinWonderHai is a one-minute video, designed and conceptualised by its digital media partner Triature Digital Marketing and Technologies Pvt Ltd. The entire journey of the cement brand from leaving the factory, going through various weather conditions and witnessing the beauty of nature and wonders through the way until it reaches the destination i.e., to the consumer is very intriguing and the brand has tried to showcase the same with the film.

Sanjay Joshi, executive director, Wonder Cement, said, "Cement as a product poses a unique marketing challenge. Most consumers will build their homes once and therefore buy cement once in a lifetime. It is critical for a cement company to connect with their consumers emotionally. As a part of our communication strategy, it is our endeavor to reach out to a large audience of this country through digital. Wonder Cement always a pioneer in digital, with the launch of our IGTV campaign #HarRahMeinWonderHai, is the first brand in the cement category to venture into this space. Through this campaign, we have captured the emotional journey of a cement bag through its own perspective and depicted what it takes to lay the foundation of one’s dreams and turn them into reality."

The story begins with a family performing the bhoomi poojan of their new plot. It is the place where they are investing their life-long earnings; and planning to build a dream house for the family and children. The family believes in the tradition of having a ‘perfect shuruaat’ (perfect beginning) for their future dream house. The video later highlights the process of construction and in sequence it is emphasising the value of ‘Perfect Shuruaat’ through the eyes of a cement bag.

Tarun Singh Chauhan, management advisor and brand consultant, Wonder Cement, said, "Our objective with this campaign was to show that the cement produced at the Wonder Cement plant speaks for itself, its quality, trust and most of all perfection. The only way this was possible was to take the perspective of a cement bag and showing its journey of perfection from beginning till the end."

According to the company, the campaign also marks Wonder Cement being the first ever cement brand to enter the world of IGTV. No other brand in this category has created content specific to the platform.

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In spite of company’s optimism, demand weakness in cement is seen in the 4% y-o-y drop in sales volume. (Reuters)

Published

3 years ago

October 21, 2021

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Cost cuts and better realizations save? the ?day ?for ?UltraTech Cement, Updated: 27 Jan 2020, Vatsala Kamat from Live Mint

Lower cost of energy and logistics helped Ebitda per tonne rise by about 29% in Q3
Premiumization of acquired brands, synergistic?operations hold promise for future profit growth Topics

UltraTech Cement
India’s largest cement producer UltraTech Cement Ltd turned out a bittersweet show in the December quarter. A sharp drop in fuel costs and higher realizations helped drive profit growth. But the inherent demand weakness was evident in the sales volumes drop during the quarter.

Better realizations during the December quarter, in spite of the 4% year-on-year volume decline, minimized the pain. Net stand-alone revenue fell by 2.6% to ?9,981.8 crore.

But as pointed out earlier, lower costs on most fronts helped profitability. The chart alongside shows the sharp drop in energy costs led by lower petcoke prices, lower fuel consumption and higher use of green power. Logistics costs, too, fell due to lower railway freight charges and synergies from the acquired assets. These savings helped offset the increase in raw material costs.

The upshot: Q3 Ebitda (earnings before interest, tax, depreciation and amortization) of about ?990 per tonne was 29% higher from a year ago. The jump in profit on a per tonne basis was more or less along expected lines, given the increase in realizations. "Besides, the reduction in net debt by about ?2,000 crore is a key positive," said Binod Modi, analyst at Reliance Securities Ltd.

Graphic by Santosh Sharma/Mint
What also impressed analysts is the nimble-footed integration of the recently merged cement assets of Nathdwara and Century, which was a concern on the Street.

Kunal Shah, analyst (institutional equities) at Yes Securities (India) Ltd, said: "The company has proved its ability of asset integration. Century’s cement assets were ramped up to 79% capacity utilization in December, even as they operated Nathdwara generating an Ebitda of ?1,500 per tonne."

Looks like the demand weakness mirrored in weak sales during the quarter was masked by the deft integration and synergies derived from these acquired assets. This drove UltraTech’s stock up by 2.6% to ?4,643 after the Q3 results were declared on Friday.

Brand transition from Century to UltraTech, which is 55% complete, is likely to touch 80% by September 2020. A report by Jefferies India Pvt. Ltd highlights that the Ebitda per tonne for premium brands is about ?5-10 higher per bag than the average (A cement bag weighs 50kg). Of course, with competition increasing in the arena, it remains to be seen how brand premiumization in the cement industry will pan out. UltraTech Cement scores well among peers here.

However, there are road bumps ahead for the cement sector and for UltraTech. Falling gross domestic product growth, fiscal slippages and lower budgetary allocation to infrastructure sector are making industry houses jittery on growth. Although UltraTech’s management is confident that cement demand is looking up, sustainability and pricing power remains a worry for the near term.