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- Title: A double conversion
- Author(s): Werner Weiss, Hassan Jradi and Hans-Jürgen Rzadki, BHA Group GmbH, Germany, describe the ESP to baghouse conversion undertaken at Union Cement Co., Ras Al Khaimah, United Arab Emirates.
- Synopsis:
- Environmental regulations for cement plants are becoming increasingly strict, and government authorities are pushing cement manufacturers all over the world to reduce emissions. The electrostatic precipitator (ESP) has been a reliable means of dust collection for many years. However, although ESPs usually operate very efficiently when new, they tend to lose efficiency as they age, even when properly maintained. Traditionally, ESP owners faced two alternatives when dealing with an underperforming unit: to replace the old ESP with a new one, or to rebuild the inside of the ESP with new component parts.
However, over the last few years, BHA Group has designed and developed a conversion program capable of changing virtually any ESP into a pulsejet baghouse, without demolishing the old unit and without lengthy downtime. Through a series of successful installations, this ESP to baghouse conversion has proven to work even better than originally estimated.
- Title: The Cost of Visual Monitoring
- Author(s): Terry Farmer, BHA Group Inc., and Doug Sweeney, Ash Grove Cement Co., USA, analyse the true cost of daily visual observation to comply with US EPA NESHAP regulations.
- Synopsis:
- 14th June 2002, is a date that will be recognised in the US cement industry as a milestone in environmental regulation. It marked the final compliance date for the National Emission Standards for Hazardous Air Pollutants (NESHAP), also referred to as the Maximum Achievable Control Technology for the Portland Cement Manufacturing Industry (PC MACT). The standards apply to each Portland cement manufacturing plant that is a major source or an area source. Under this rule, the US EPA imposes emissions limitations on particulate matter, dioxins and furans, as well as opacity from new and existing kilns, clinker coolers, and material handling processes at major sources.
- Title: Pollution Control and CFD Technology
- Author(s): Joseph Riley and Maurizio Archetti, BoldEco US, USA, and Luca Maiocchi, Boldrocchi Ecologia, Italy, look at the design and upgrade of air pollution control equipment using modern, analytical tools.
- Synopsis:
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To those in the market for process equipment, a performance guarantee is probably as important as price. In the case of standardised equipment, it is usually enough to rely on the experience of the supplier in order to be satisfied with his ability to achieve a particular level of performance. In the case of a custom engineered system, and especially in more demanding applications, not only must the supplier have had previous experience in a similar application, but he must be able to evaluate the critical design conditions of the particular application in order to properly modify his basic design. In the case of air pollution control systems, it is imperative that the company responsible for executing the order has not only the experience, but that it also has the experienced staff who can make distinctions about the very important, and often overlooked, differences between the reference projects and the one in hand. Only with this knowledge can the design be properly modified in order to achieve the guaranteed level of performance.
- Title: Continuous Emission Monitoring
- Author(s): Jose Tarodo, Dima Consultores, Spain, analyses the advantages and disadvantages of available emission monitoring systems, and discusses the installation of an Opsis cross stack DOAS monitoring system at the Cementos Alfa plant in Spain.
- Synopsis:
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Cementos Alfa S.A. is located in Mataporquera, in northern Spain. The cement plant is known for its environmental focus and for its commitment to high quality products. It is equipped with the latest technology, for example a totally automated laboratory. In October 2002, the plant installed a state-of-the-art continuous emissions monitoring system.
A number of environmental monitoring systems were investigated, and the monitoring equipment offered by Dima Consultores was considered to be the most appropriate. It consists of an Opsis system to monitor NO, NO2, SO2, CO, CO2, H2O, HCl, HF, Hg0, particles, flow velocity, etc. This Swedish technology provides Cementos Alfa with high quality data and fulfils the requirements set by the authorities. Furthermore, since it is a non-contact and non-extractive monitoring system, it requires extremely low maintenance. Another advantage is that the system can be easily upgraded to measure additional compounds.
- Title: Pulse Jet Off-line Filter Cleaning
- Author(s): Carlos Cengotitabengoa, AAF International Spain SA, analyses and suggests an alternative to reduce operating costs associated with fabric filters on kiln dedusting.
- Synopsis:
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The operating costs for bag filters depend on a number of factors, these include a drop in pressure across the filter which proportionally affects the power consumption of the system fan. The consumption of compressed air, used for cleaning the bags, affects the compressor power consumption. Amortization of the bag filters (the longer the bag life, the lower the cost to amortize them) and finally general maintenance of the installations. The following study is based on data obtained from the last four Cimpor-Portugal installations to be equipped with AAF XLC Pulse Jet filter units.
The four Cimpor-Portugal high throughput XLC FabriPulse bag filters have proven the ability of the AAF/Off-line method of bag cleaning to decrease the pressure drop across the filter and the consumption of compressed air, to increase bag life and allow on-line filter maintenance.
- Title: Dedusting Developments
- Author(s): Manfred Schobesberger, Inspec Fibres GmbH, Austria, discusses advances in kiln gas dedusting.
- Synopsis:
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Following a worldwide trend in the cement industry, a number of Austrian production facilities are changing to bag filters for venting kiln off gases. In the past, such filters were traditionally used at the clinker cooler and in many other locations, for example behind the grinders and classifiers, using low temperature bag materials. Considering that kiln gases have a temperature of approximately 300 ˚C when leaving the preheater tower, a quenching unit is required to cool them to a level suitable for the filter material. As is often common practice, these gases are used to dry the raw meal in the mill and classifier unit, the temperature before the bag house being somewhat lower most of the operational time.
- Title: ESP to Hybrid Transformation
- Author(s): Maurizio Vandelli, Cementirossi, Italy, analyses the process of converting two existing ESPs to hibryd filters to reduce dust emissions and increase efficiency.
- Synopsis:
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It is common knowledge that the ESP cannot always give, in all operating conditions, and especially during transient conditions, the high quality performances that are nowadays required by the environmental authorities. It is also common knowledge that this is especially true in the case of ESPs utilised for cement mill dedusting, where frequent stopping and starting is usual and when the gases being dedusted rarely have a suitable moisture content.
- Title: Understanding Filtration Fabric Efficiency
- Author(s): Philip H. Raley, Menardi Filters, USA, describes the influence of various factors on surface and depth filtration efficiency.
- Synopsis:
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The operating filtration efficiency of most woven, nonwoven, or felted materials without a coating or membrane is very dependent on the operating conditions and the material being collected. With this type of product, the dust cake on the fabric does much of the filtration. This is often referred to as depth filtration. The function of the media is to catch and hold the initial dust cake and to release well during cleaning. Factors other than the fabric can have a controlling influence on the filtration efficiency. A few examples are gas flow rate; gas stream composition; dust cake thickness and porosity; dust particle size and shape; and cleaning cycle.
If a fabric with an expanded PTFE membrane is used, such as Menardi’s Mikrotex®, the membrane becomes a controlling factor in the fabric efficiency. With membrane products, the efficiency of the fabric in the laboratory will generally be much closer to that experienced in the baghouse.
- Title: Integrated, High Temperature Kiln Dedusting
- Author(s): Bruno Radaelli, Redecam Group, Italy, makes a comparison between the expected performances of a plant, such as those measured at start-up and then after more than 20 000 hours of operation. Further developments in more recent plants of the same type, supplied to the same Group, are then discussed.
- Synopsis:
- In the April 2001 issue of World Cement, Redecam published a comparison of several of its processes for cement kiln gas dedusting. Among them were ‘integrated’ plants: those in which kiln gas is mixed with cooler vent air (quaternary air) into a single bag filter, which can be equipped with different type of bags, both at low and high temperatures.
This article will focus only on high temperature integrated plants, in particular a ‘dynasty’ of plants supplied to the Buzzi Unicem Group over the past four years, all in the Americas:
- River Cement: Signal Mountain plant (SGN), Tennessee, USA. Commissioned in March 2001.
- Cementos Moctezuma: Cerritos plant (CRT), Mexico. Two lines: line 1, commissioned in June 2004, and line 2, due to be commissioned this year.
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