- Written by Thomas Börrnert, ABB Switzerland Ltd.
The energy intensive cement industry faces high and rising energy costs and must meet requirements for reducing CO2 emissions. One remedy for these challenges is to increase energy efficiency by recovering waste heat and converting it to electricity.
Modern cement plants can be thought of as huge heat exchangers. After firing the kiln (and eventually the precalciner), the heat in the stack gas and from the hot clinker can be used to a large extent in the plant for:
- Secondary air preheating,
- Tertiary air preheating,
- Preheater tower with 3–6 stages to preheat raw meal,
- Preheater waste gas to dry raw meal in the raw mill,
- Waste heat recovery to dry and preheat conventional or alternative fuels,
- Use of clinker cooler waste heat to feed districtheating systems.
Waste heat recovery is the most important measure towards decreasing heat losses and therefore has the highest priority. It is the most efficient way to increase energy efficiency because the efficiency of heat recovery is high, 1kWh of waste heat reused in the plant ends in 1kWh of useful heat.
- Written by Çaglan Becan, Turkish Cement Manufacturers' Association (TCMA)
2011 sees the 100th anniversary of the start of the Turkish cement industry. Since 1911 the cement sector has developed rapidly from a production capacity of just 20,000t/yr in 1911 to over 66Mt 100 years later.
In terms of production, the Turkish cement sector is ranked number one in Europe and number four in the world after China, India and the US. In terms of cement exports it is first with a global share of 12%, leaving China and many countries of South Eastern Asia behind.
By 2010 the sector became a vital branch of industry for the national economy, with turnover of around US$4.5bn, exports valued at US$1bn and direct employment of 15,000 people. Based on achievements during 100 years, the sector entered the new millennium with a new vision and mission enabling to serve as a model all over the world.
- Written by Teutrine GmbH
Teutrine GmbH has established itself as a reliable service partner for multi-faceted engineering, assembly and repair solutions for cement plant operators and plant engineering contractors. Companies from the chemical and wood-processing industries, from the waste disposal and power station sector also form part of Teutrine's customer base.
The ongoing performance increases and availability of process plant in the cement and mineral industry result in an increased need for large spare part stocks with resultant higher costs for procuring parts. The degree of wear in plant components that are subjected to heavy-duty operation increases exponentially. As a service partner and in very close customer contact, Teutrine GmbH from Oelde,
Westphalia, Germany, has solution strategies for greater planning assurance in the realm of maintenance and repairs. The upshot above all is an increase in lifetimes of highly stressed machine components.
In this regard a significant role is played by mobile processing machines for clients' on-site applications. Of major importance for the success of on-site operation is efficient preparatory work. Matching the mobile Teutrine processing machinery to clients' needs must be researched and precisely clarified in order that workshop quality can be achieved on site in reality.
- Written by Kamal Kumar, P Somarajan & Anupam, Holtec Consulting Pvt. Ltd, India
Given the disparate nature of the emerging cement scenarios in the MENA region, success and even survival depends on the ability to adapt. Most companies have consequently initiated focused efforts covering various aspects of their cement operations. While conventional focus may yield marginal to moderate results, incremental benefits can be reaped by harnessing the multi-functional dimensions of all internally controllable variables through an integrative approach. From ingeniously exploiting the hidden potential of the raw material portfolio to uncovering untapped value in the geographic market mix, innovative initiatives in the entire value chain of operations results in far higher success.
The key features of such initiatives include ensuring comprehensive coverage of the entire value chain, a focus on bottom-line results, exploration of the potential of non-conventional areas, adding value to on-going initiatives in terms of time and cost savings, use of optimisation tools to achieve superior solutions and employing a three-phased approach consisting of assessment, action and monitoring.
- Written by Dr Martin Schneider, Verein Deutscher Zementwerke (VDZ)
The cement industry worldwide is facing growing challenges in the context of saving material and energy resources as well as reducing its CO2 emissions. The International Energy Agency highlighted in its 'Road Map for the Cement Industry' that the main levers for the cement producers are the use of alternative materials, be it as fuel or raw material and in addition the reduction of the clinker/cement factor by utilisation of well tried and proven materials like slag, fly ash, pozzolanas or limestone fines. This underlines that in the years to come cement will depend on OPC clinker to a high degree. New cements will therefore most certainly first take into account higher amounts of main constituents besides clinker which show pozzolanic or latent hydraulic properties.
Artificial materials that originate from natural or industrial resources but require additional thermal treatment and/or activation may also have a role to play. It is not clear at present to what extent cements based on magnesia can play a role. On the other hand, sulphoaluminate cements may have a significant role to play. Unfortunately, due to their specific raw materials as well as their performance in concrete they will most probably not be able to substitute relevant parts of today's cement markets.
Cement production has undergone a tremendous development from its beginnings some 2000 years ago until the present day. While the use of cement in concrete has a very long history, the industrial production of cements started in the middle of the 19th century, at first with shaft kilns. These were later on replaced by rotary kilns as standard equipment worldwide. Annual global cement production has reached some 2.8Bnt/yr and is expected to increase still further to around 4Bnt/yr. Major growth is forecast in countries like China and India as well as the Middle East and Africa (MENA), (Figure 1). At the same time, the cement industry is facing challenges such as increased energy costs, requirements to reduce CO2 emissions and problems of sourcing raw material of sufficient quality and quantity.
The World Business Council for Sustainable Development and its Cement Sustainablity Initiative (CSI), comprising global cement producers, has initiated a project called 'Getting the Numbers Right,' which for the first time provides a good database for most of the global cement industry with respect to CO2 and energy performance. Figure 2 shows the energy performance of global cement productions covered by the CSI members.
