Connect with us


Process optimisation and Retrofiting




In the current scenario of limited demand growth and competitive industrial environment, enhancing productivity and reducing the energy consumption has become the need of the hour for survival.

Over the years, Operations Audit has been found to be an effective tool for identifying the measures required to optimise the plant process operations and drawing action plans for exploring the hidden potential for enhancing the capacity through retrofitting route.

This paper discusses case studies to highlight the benefits accrued through conducting operations audit of plants.

Moreover, in view of the fact that cement production is an energy-intensive process, it is important for the cement production units to unleash the plant potential capacity so as to improve the capacity utilization and lower the energy consumption, ensuring reduced unit cost of production.

Process Audit helps in identifying the possibilities to upgrade the available equipment with optimum capital expenditure. A set of action plans are formulated based on identified improvement measures for implementation in the plant covering operational debottlenecking, establishing potential plant capacity, improving key performance indicators etc.

The main objectives of the process optimisation study are to identify the inherent potential in the entire production process starting from mining operations to packing. Each unit operation is studied and analysed including plant stoppages in detail with an objective to identify the potential improvement areas for optimisation of operational practices for sustained operation covering all the aspects.

Case Study – 1
Holtec Consulting Private Limited (HOLTEC) had carried out a Plant Operations Audit for a cement plant in the Kingdom of Saudi Arabia with following objectives:

  • Exploring the available potential in clinkering capacity for further capacity enhancement of both production lines
  • Improving the overall efficiency in terms of fuel & power consumption and performance to realise its objective of reducing its demand for HFO.
  • Optimisation of Bypass Operation for minimising heat and dust losses. The said plant has two production lines having 4 stage SP kilns & Flash calciner, ball mills for raw and finish grinding operating at an average production level of 3,600 tpd each. The plant is manufacturing Type I & Type V cement. The fuel used for manufacture of clinker is HFO being supplied by refinery within Kingdom of Saudi Arabia.

Plant is operating at specific fuel consumption of about 880 kcal/kg and specific power consumption of about 121 kWh/t cement with about 50% bypass to avoid operational problems caused by presence of excess sulphur present in fuel and raw materials.

HOLTEC suggested the following improvement measures for reducing the bypass extent and reduced specific heat and power consumption:

Raw Mill

  • Installation of VFD for mill vent fan and opening the damper fully
  • To improve the separator efficiency through optimisation
  • Installation of VFD for separator fan and opening the damper fully
  • Reducing pressure drop across separator bag filter

Pyro Process

  • Replacement of existing dust settling chamber with a suitably designed new dust settling chamber TA damper opening to be re-adjusted after installation of new dust settling chamber
  • The cooling fans for which efficiencies are lower even after upgradation of cooler vent Heat exchanger, replace the fans with new suitably designed high efficiency fans with VFD in phased manner
  • Increase the cooler grate area by extending the cooler length
  • Reduce preheater return dust by replacing top stage cyclone with high efficiency cyclone
  • To increase kiln inlet area
  • Use of silicon carbide refractory for kiln inlet area
  • Installation of new LP cyclone
  • Addition of 3rd parallel module of heat exchanger for reducing the bypass extent Use of alkali rich material like feldspar, soda ash in raw mix to neutralise presence of excess sulphur
  • Installation of air blasters.

Plant Capacity Assessment has been carried out based on the process measurements conducted by the HOLTEC team, data collected and discussions held with plant personnel during the site visit. The production capacity can be upgraded to 4,200 tpd clinker at a specific investment of USD 75 Plant implemented some of the above measures in a phased manner. Plant is currently operating at an average production level of about 4,200 tpd clinker at an average specific heat and power consumption of 800 kcal/kg clinker and 100 kWh/t cement.

Case Study – 2
Holtec Consulting Private Limited (HOLTEC) carried out a comprehensive technical audit for cooler optimisation in a cement plant in India having a dry process coal fired kiln with 5-stage suspension pre-heater, Separate Line Calciner (SLC), Grate cooler and Roller Press for Raw, Clinker and Slag grinding.

The target cement plant had operational issues with the cooler, affecting the kiln performance leading to reduced clinker production.

The rated capacity of the plant is 1,650 tpd and has operated at a peak production of about 1,900 tpd in the past. Due to operational issues with the cooler, the clinker production is reduced to 1,300 – 1,400 tpd.

Key Operational Issues

  • Kiln feed is restricted up to clinker production level of 1,300 – 1,400 tpd due to the frequent cooler grate plate failure
  • In-house trials to operate the cooler at lower speed to maintain higher clinker bed (typically in the range of 300 – 400 mm), led to clinker heap formation in the grate 1. The operators were forced to increase the cooler speed to avoid snowman formation and disturbance in kiln operation
  • The grate structure and frame got damaged due to over filling of under grate hopper of chamber 1, up to grate level Operating the cooler at higher grate speed of 16-17 spm leads to:
  • Low clinker bed height of 150-200 mm
  • High wear & tear of grate plates because of hot clinker movement and plate to plate abrasion
  • Low under grate pressure of 25-30 mbar, (against 45-50 mbar recommended) with full opening of cooling air fan damper
  • Exposure of grate plates to higher temperature causing premature oxidation/burning and more impact from the falling clinker.

Observations Based on Internal Inspection of Cooler

  • Deformations and misalignment in the support structure/frame and cooler grate plates in grate 1 (chamber 1 & 2)
  • Cracks observed in 3 plates, starting from the edge to centre
  • High wear on surface due to near zero gap between the fixed and moving plates observed in 10 nos plates.
  • 6 plates in Row 1, 2 and 3 were observed burnt due to excessive temperature condition
  • Failure of T-bolt reported due to mechanical stress development because of misalignment
  • The following gaps were observed in grate plates which is caused due to misalignment:
  • 8 – 10 mm between plates of two consecutive rows as against 2 mm recommended
  • 5 – 6 mm between adjacent plates of same row as against zero gap ?~ 20 mm gap between the side seal and grate plate.

The phenomenon of burning, faster wear, premature failure of the grate plates is attributable to deformations and misalignment in the support structure/frame which has now led to unwarranted gaps between the plates and cause of clinker fall through as well.

Observations Based on Process Measurement
Mass and Gas balance was done across the clinker cooler system in order to ascertain the present thermal efficiency of the clinker cooler system and cooler losses.

Details of heat balance worked out for clinker cooler is given in Table 2. Following are the observation based on process measurements:

  • Cooling input air measured is 3.13 Nm3/kg clk (4.05 kg/kg clk) against typical value of 2.2 – 2.5 Nm3/kg clk for such type of coolers
  • Cooler heat recuperation efficiency: 33% against a typical value of 55 ? 60%
  • Clinker cooler losses: 264 kcal/kg clk against a typical value of 140 ? 160 kcal/kg clk
  • Cooling air losses: 30% of total input air escapes from drive shaft, flanges etc of grate 1, which is avoidable
  • Cooler vent air temperature measured as 425oC (near vent take off) reduces to 150oC (near cooler ESP fan inlet) due to false air ingress from cooler ESP inlet duct, cooler ESP and Cooler vent fan inlet duct. False air ingress increases the volume of air being handled by the fan leading to higher ESP fan power consumption

Following actions were suggested for the improvement in cooler performance:

  • Intermediate plugging of air escaping from drive shaft & flanges of chamber 1 & 2, to increase undergrate pressure, guide cooling air to pass through aeration holes, and improve the cooler recuperation/thermal efficiency
  • After arresting the air leakages, trials may be taken to gradually reduce the cooler grate speed for increasing the undergrate pressure. Regular monitoring should be made to check any build-up/snowman formation in 1st chamber.
  • Reducing cooler vent ESP fan load by arresting false air ingress in the cooler vent ESP inlet and outlet duct
  • Minimising the gaps in cooler grate plates and side seals till the implementation of long term solutions
  • Modification of existing grate 1 by installing static grate plates for the first 7/8 rows along with the new dedicated air distribution system and blasters
  • Balance portion of grate 1 to be modified/replaced to suit the installation of above proposed modification
  • Installations of VFD for all the cooler fans.

Case Study – 3
Holtec Consulting Private Limited (HOLTEC) had carried out a process optimisation study in a cement plant in Pakistan. The plant was operating at a production level of about 1,800 tpd clinker. The average values of specific fuel consumption and specific power consumption at the time of study were about 977 kcal/kg clinker and about 131.55 kWh/t cement respectively. The major equipments in the plant were a two chambers central discharge ball mill for raw material grinding, a dry process kiln with twin string preheater (PH) and a precalciner (PC) in calciner string, grate cooler and a two chamber, closed circuit ball mill for cement grinding.

Following actions were suggested:

  • Plugging the false air infiltration in the system
  • Provision and functioning of the mechanical flaps at the bottom of dust settling chamber in the tertiary air duct (TAD)
  • Adjusting the feed distribution in kiln and calciner string PH
  • Reducing the primary air quantity in PC and kiln
  • Adjusting the flame momentum of kiln firing burner
  • Optimisation of grate cooler operation.

With implementation of above improvement measures and under HOLTEC?s operational supervision, the following were achieved:

  • Increase in kiln capacity to about 2,400 tpd clinker
  • Lowering of the specific fuel consumption to about 885 kcal/kg clinker
  • Reduction in specific power consumption to about 103 kWh/t cement.

HOLTEC assessed the potential capacity of plant as 3,000 tpd clinker. For achieving this capacity, some important recommendations made are as given below:

  • Installation of dust suppression system on crusher hopper and its conveyors.
  • Installation of line -2 raw mill for raw materials grinding.
  • Installation of one additional belt conveyor for feeding the raw mill hoppers.
  • Replacing the fuel oil by coal as fuel and installation of a coal mill of capacity 30 tph.
  • Removal of venturies in down comer ducts of kiln and PC string PH.
  • Installation of compressed air assisted water spray in PC string down comer duct.
  • Installation of 3rd cyclone in parallel to the existing top stage twin cyclones in PC string for saving in pressure drop.
  • Extension of PC height by 5 meters.
  • Installation of grid resistance regulators for HV fans.
  • Relocating the PC string ID fan after GCT for saving in electrical energy consumption of ID fan.
  • Replacement of PC string ID fan by a new suitably designed, high efficiency fan. Installation of kiln shell temperature scanner.
  • Installation of variable speed drive for cooler fans and one of the cooler exhaust fans.
  • Extension of clinker cooler area by provision of 3rd grate and increasing the capacity of cooling air fans.

With HOLTEC?s assistance, the plant implemented some of the above measures. Implementation of these improvement measures were done in a planned manner in consultation and supervision of HOLTEC, in a planned shutdown of about 5 weeks. The plant was able to achieve an average production level of about 2,850 tpd clinker. With complete implementation of the above recommendations, the expected kiln production is 3,000 – 3,100 tpd clinker. At this production level, the expected specific fuel consumption and specific power consumption shall be about 750 kcal/kg clinker and 90 kWh/t cement. Estimated payback period for the capacity upgradation worked out to about 5 months. Moreover, the plant operational consistency has improved a lot as a result the annual production has increased significantly.

The above case studies demonstrate that Operations Audit is an effective tool for identifying the measures required to optimise the plant process operations and drawing action plans for exploring and exploiting the hidden plant potential through retrofit route.

The broad specifications of the grate cooler are furnished below:


Inclined grate cooler

Size (6×2.8) + (13.5×2.8) m
Grate load 32.3 tpd /m2
Grate area 51 m2
Clinker Outlet Temperature 60-80? C
No. of grates 2
No. of chambers 5
No. of cooling fans 5
No. of rows:
– Chamber 1 6
– Chamber 2 18
– Chamber 3,4,5 45

Table: Parameters considered during period of measurement





Ambient temperature oC 31 Measurement
Total kiln feed tph 103 CCR indication
PH exhaust gases Nm3/ kg
2.196 Measurement and
PH exhaust gas temperature oC 365.7 Measurement
Oxygen at PH exhaust gas % 6.9 Measurement
CO at PH exhaust gas ppm 325 Measurement





Cooling air input to clinker
3.129 Measurement &
Secondary air quantity Nm3/kg
0.091 Estimated based on air
Tertiary Air quantity Nm3/ kg
0.306 Measurement and
Cooler vent air quantity Nm3/kg
1.780 Measurement and
Cooling air escaping for
cooler air chamber 1 & 2
0.954 Estimated based on air
balance in cooler
Hot Clinker temperature oC 1400 Assumed
Tertiary air temperature, oC 970 Calculated based on
cooler heat balance
Secondary air temperature
Cold clinker temperature oC 73 Measurement

Table2: Mass and Heat Balance of Clinker cooler








oC kcal/kg
1 Hot Clinker 1.00 1400 0.261 366
2 Cooling Air 4.05 31 0.238 30
Total 5.05 396
3 Cooler Exhaust 2.30 425 0.247 241
4 Tertiary Air 0.40 970 0.259 99
5 Secondary 0.12 970 0.259 30
6 Clinker Leaving cooler 1.00 73 0.190 14
7 Cooling air leakage 1.00 31 0.238 9
8 Radiation losses 3
Total 5.05 396

Continue Reading
Click to comment

Leave a Reply

Your email address will not be published. Required fields are marked *


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





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).

Continue Reading


Wonder Cement shows journey of cement with new campaign





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


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.

Continue Reading


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





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.

Continue Reading

Trending News



Don't miss out on valuable insights and opportunities to connect with like minded professionals.


    This will close in 0 seconds