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Filtration Fibres and Finishes

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In a modern cement plant there are plenty of applications, which need APC (air pollution control) equipment. Of all the APC equipment, RABH (reverse air bag house) and PJBH (pulse jet bag house) have gained wide acceptance as preferred equipment/technologies for separation of fine dust from air/flue gases.

In all sections of cement manufacturing like raw material handling, grinding, storage, clinkerisation, calcination, cooling, cement grinding and packing there are several PJBH in use. RABH is used in cement/kiln section only. The fabric filters are positive filtration equipment where the separation of dust takes place on the surface of the filter media or up to a certain depth of the filter media. When the filtration takes place on the surface it is termed as surface filtration and when some depth of filter media is used for holding the primary cake, the process is termed as depth filtration. We shall discuss various filter fabrics made using different fibres used in a cement plant in this article.

Filter material
There are several synthetic and mineral fibres in use for making filter fabrics. They have different temperature resistance and chemical resistance. Based on these two properties namely, thermal stability and chemical resistance, the choice of filter media is made for a particular application in a cement plant.

The fibres, which are used in cement plant, are mainly polyester, homopolymer acrylic, aramid, PPS, P-84 and glass. Very seldom filter fabrics like polypropylene and PTFE are used in a cement plant. Therefore, we shall restrict the discussion here to the fibres, which are commonly used and to various finishes used for enhancing the filter fabric performance.

Polyester: As can be seen from table, it can withstand a continuous temperature of 150?C in absence of moisture in the gas stream. It can withstand 160?C for a short period, but if the temperature goes beyond 160?C, the felt will shrink and loose its mechanical properties. It will get hardened and loose its flexibility. The colour will get darker and the filter bags will be torn after some time due to continuous pulsing. Polyester is workhorse of industry and has more than 70 per cent share in terms of no of filter bags. It is the cheapest fibre available and therefore, unless it fails in a particular duty condition, polyester remains the first choice.

Homopolymer Acrylic: In presence of water vapour in the gas stream, polyester starts reverse hydrolysing (disintegrates into ester and acid) and holes are formed in the filter bags. Besides, felt also loses its mechanical strength. In the applications like cement grinding, gypsum drying and slag drying homopolymer acrylic is a fibre, which is the preferred material. It can withstand operating temperature of 130?C continuously and does not hydrolyse. Homopolymer acrylic when blended with polyester resists charging of filter fabric and therefore it is frequently used on coal mill PJBH. It particularly performs well if fly ash is present in the mill and 100 per cent, while homopolymer acrylic fails due to abrasion in such conditions. Polyester renders better abrasion resistance to the felt made using a combination of polyester and homopolymer when compared with 100 per cent homopolymer felt. Use of microdenier fibres for making the felt has further helped in performance of the filter fabrics in cement mill air venting bag-filters. Increased surface area improves filtration efficiency and keeps the operating DP lower than conventional felts.

Aramid/Nomex?: Aramid is a very strong fibre and has excellent resistance to abrasion. It can work at a continuous temperature of 204?C and can take short surges up to 220?C. It is fibre of choice in clinker material handling and also handling of fly ash and slag. Nomex is an aramid fibre made by DuPont Inc. Aramid felts can take a continuous temperature of 200?C. They are rugged and give good life in most of the applications. However, being synthetic fibre, they cannot handle spark OR red hot particles and therefore, having an equipment to arrest hot particles or spark before PJBH must be considered while using these bags. They are very expensive when compared with polyester and homopolymer acrylic.

PPS (Polyphenelyne Sulfide): It is a fibre rarely used in cement plant. It is fibre of choice for boiler flue gas filtration. Therefore most of the captive power plants, which are fitted with PJBH as APC equipment, are using PPS filter bags. PPS has a continuous temperature withstanding capacity up to 180?C. However, this temperature comes down to less than 140?C if the oxygen is more than 10 per cent in the flue gases. It is known to interact with oxygen and oxidize at temperatures above 150?C; therefore, care must be taken to ensure that the O2 levels are always below 10 per cent. It has excellent chemical resistance against both alkali and acids.

P-84? (Polyimide): P-84? has been successfully used for filtering flue gases from cement kiln and one of the largest PJBH installed after kiln at a cement plant in northern India is using the filter bags made of P-84? fibres with excellent operating parameters. It can take a continuous temperature of 200?C. However, if the NOx content is more than 100 ppm, the fibres may become susceptible to oxidation at elevated temperatures.

Glass: Glass is a mineral fibre and E-glass is the grade of glass fibre, which is used in filtration. The fibres are used for making woven cloth, as it is difficult to needle the glass fibres due to their brittle nature. However, very high temperature withstanding capability (260?C) has made it a first choice for cement kiln/raw mill bag house. It is used in RABH as well as PJBH. Almost all the PJBH installed in country after cement kiln have woven glass with ePTFE membrane laminated filter bags. RABH bags are made by sewing rings at predetermined distance and do not use cages. The glass fibre filter bags have exceptionally good life and fair resistance to both alkali and acids. They have also been used in power plant bag filters for high temperature flue gas filtration.

Finishes applied to the basic felt
There are various finishes applied to the basic felt to enhance the performance of the filter fabrics. They are described as under:
Heat set: The needle felt must be passed through a temperature higher than its continuous operating temperature during manufacturing to make is shrink to a level when exposed to the heat setting temperature that varies for different fibres. If heat set before, the filter bags dimensions will remain unaffected when a temperature of similar value is reached during filtration. Several times, when not heat set the filter bags shrink to a smaller size and fail prematurely.

Singed: Singeing is a process of reducing the fur like protruding fibre tips from the surface that participates in filtration. Singeing enhances the dust release properties of the felt and improves cleanability. It helps felt operate at relatively lower DP on long term basis. This is accomplished by passing the felt over an open flame, which melts the tip of the fibres. The latest technological advancement in this process has taken place where electrical singeing has replaced open flame singeing. This reduces contamination of felt while singeing is carried out.

Calandering: After singeing, the felt is passed through heavy and hot steel rolls to iron out the fibre tips melted during singeing. Calandering improves the dust release properties further. It is the most basic surface treatment done on a filtration felt to make it suitable for use as a filter fabric. Eggshell like surface is created by heavy calandering when extra smooth surface is desired.

PTFE impregnation: PTFE resins are used in different proportion to apply a chemical coating on the fibres. The impregnation of fibres with PTFE resins enhances the dust release property of the fibres and also increases their chemical resistance as the fibres get encapsulated in PTFE resins.

ePTFE membrane: ePTFE membrane laminated media is termed as the best available control technology for emission control. It promotes surface filtration, increases flow through the media and reduces differential pressure drop. Also, the life of media is enhanced in almost all cases. A thin expanded film of PTFE is thermally OR chemically laminated on the filtration side of the felt or woven filter media. The membrane has holes of less than three microns and promotes surface filtration. The felt remains clean and cleaning force required is extremely less.

In conclusion
Filter fabrics have gained preference over ESP and other technologies for air pollution control due to stringent emission norms imposed on cement industry by CPCB and MOEF. Research in development of new fibres and improvement in filtration efficiency of existing fibres have given great advantage to PJBH/RABH equipment over ESPs. The shift towards installation of new bag-filter and conversion of existing ESP to bag-filter has been the trend in last 10 years.

Filter fabrics have gained preference over ESP and other technologies for air pollution control due to stringent emission norms imposed on cement industry by CPCB and MOEF.

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

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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

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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)

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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.

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