London, United Kingdom
London, United Kingdom

Time filter

Source Type

Nance G.,GCC | Abbas T.,Cinar Ltd. | Lowes T.,Cinar Ltd. | Bretz J.,Cinar Ltd.
IEEE Cement Industry Technical Conference (Paper) | Year: 2011

In an effort to reduce production costs, the cement industry is using more and more alternative fuels and raw materials (AFRs) than ever before. Some successful examples show thermal substitution rate (TSR) as high as 90%. Generally, a higher than 20-30 TSR requires detailed analysis of not only combustion aspects of AFRs, but also their impact on emissions, kiln stability and clinker quality. Usually those conditions that provide a more optimum combustion environment both for plants using conventional fuels as well as those using AFRs or a combination of the two mean an increase in NOx emissions. Implementation of traditional low-NOx techniques can have a negative impact on CO/VOC emissions as well as increase deposit build-up potential and cause kiln instabilities. Several alternative NOx reduction methods are available and have been applied within the cement industry. These methods include Selective Non-Catalytic Reduction/Selective Catalytic Reduction (SNCR/SNR) and can provide NOx reduction efficiencies of 40-80% respectively, without significant negative impact on CO/VOC emissions, but at the same time add significant cost to clinker production. © 2011 IEEE.


Akhtar S.S.,Holcim Inc. | Ervin E.,Holcim Inc. | Raza S.,Cinar Ltd. | Abbas T.,Cinar Ltd.
IEEE Transactions on Industry Applications | Year: 2016

In the North American energy market, natural gas (NG) prices have been gradually decreasing during the past several years, primarily due to advances in shale gas extraction techniques. The availability of cheaper NG, while seen as an attractive short-term fuel switching option, is viewed with caution by most cement plants due to long-term procurement concerns. Also, due to traditionally higher NG prices, cement plants have invested heavily into solid fuels, including storage, grinding, handling, and dosing systems - often achieving high thermal substitution rates (TSRs) of solid alternative fuels and raw materials (AFRs). As a result, a wealth of knowledge has been acquired on firing solid fuels, including some of the more difficult ones, e.g., higher sulfur petcoke and bigger size AFRs, where operational issues such as build-ups, emissions, and production losses have been and are being minimized. Switching to gas firing, however, requires readaptation of combustion and process guidelines for a fuel which, although in principal, is easier to burn, but has relatively lower radiative heat transfer and sharper burning characteristics than coal. As such, the plants, which have switched to NG firing, have observed inconsistent trends in production, energy, and emission performance, mainly due to the lack of sufficient information on combustion/process interactions of the two fuel types required for cost-effective optimization. An NG flame ignites earlier, releases intense heat but lacks dissipation of heat as compared with a solid fuel flame, thereby requires plant specific adjustments. This paper presents actual results of NG firing trials at selected cement plants along with mineral interactive computational fluid dynamics (MI-CFD) predictions, subsequent to validation from the plant data, on four kiln and four calciners. Recommendations are also made to improve and optimize NG firing by taking into considerations of the combustion and mineral interactions. © 2015 IEEE.


Abbas T.,Cinar Ltd. | Lowes T.,Cinar Ltd.
ZKG International | Year: 2012

The article focuses on the optimization of the thermal substitution rate. The kiln is 58 meters long and inclined at an angle of 2 degrees, the burner is placed 1 meter outside the kiln nose ring at an angle of 1.5 degrees. The gas temperature profile indicates that the highest temperature flame is established in the near burner region, which is typically observed in gas-fired cement kiln. The flame lift-off distance is about 0.5 m from the burner tip, which is compatible with the high velocities applied for primary air injection and natural gas. fuels and oxygen. Although recirculation zones are observed in the kiln hood and in the burner near region, due to the geometrical effects of the hood, the current tertiary air duct and kiln hood arrangement, however, has little impact on the combustion of the burner fuel.


Abbas T.,Cinar Ltd | Bretz J.,Cinar Ltd | Garcia F.,St. Marys Cement Inc | Fu J.,St. Marys Cement Inc
IEEE Cement Industry Technical Conference (Paper) | Year: 2015

Combustion, calcination and emission (CO, NOx, S02) optimization results are presented from a separate line (SL) calciner, and are compared, where possible, with another SL calciner. Over 60% of the total fuel is fired in the calciner achieving 95% calcination levels in relatively short residence times (2.5 seconds). The use of petcoke and alternative fuels (AFR's) saves fuel costs, but their thermal substitution rate is limited by emissions and operational difficulties. In addition to the problems of complying with emission limits (i.e., CO, NOx, VOC's), kiln instabilities may result due to the higher sulfur and chloride contents of AFR' s, or petcoke. The problem is exacerbated if the meal injected in the calciner drops through-At the kiln inlet/tertiary air inlet due to the formation of meal-slugs or presence of lower velocities regions. A detailed study of a Canadian cement plant's separate line calciner is presented using a 3-D mineral interactive computational fluid dynamics (MI-CFD) model and results related to flow aerodynamics, calcination, combustion of conventional and alternative fuels and emissions (CO, SOx, and NOx) are compared with other separate line calciners. In addition, the effect of fuel-mix on emissions is analyzed and recommendations are made with regard to the burners, burner locations, meal inlets, specific to calciner geometrical characteristics. The computed results are compared with the plant data and additional MI-CFD model predictions are carried out for alternative fuels to be fired in the next project-phase. As a result, of the on-going calciner measurement and MI-CFD campaigns, the plant can easily achieve the legislative limits of NOx, CO and S02 for coal, low to higher sulfur petcoke blends as well as for 50% thermal substitution levels of AFR. The plant is 'AFR-ready' pending its permitting process, which is in its final stages. © 2015 IEEE.


Abbas T.,Cinar Ltd.
ZKG International | Year: 2012

Two case studies where coal and natural gas were replaced with precoke and AFR thermal substitution are presented. In the first study, a detailed MI-CFD modeling campaign was initiated with the emphasis on visualization of the effect of various calciner improvement designs. The injected petcoke particles were observed to penetrate slightly more into the upward directed flow of kiln gases in the base case as compared with the lower injection case. The temperature distribution within the chamber showed that the exit temperature is in good agreement with plant measured data. In an another case study shows the MI-CFD representation of a modification of riser duct chamber height by 3 m to improve combustion and calcination levels. The results showed that the combined effect of lowering the petcoke burners and extending the height of the precalciner by 3 m has only a marginal effect on char burnout and calcination levels as shifting the burners.


De Souza J.B.,Cinar Brazil Ltda | Abbas T.,Cinar Ltd.
ZKG International | Year: 2015

Most cement plants have limitations in terms of co-processing due to flow stratification leading to lower fuel burnout/calcination, high CO/NOx and build-ups. The identification of flow stratification is extremely difficult and requires elaborate in-flame and 3-D mapping of the temperature and major gas species to quantify the air-fuel mixing pattern and mixedness levels. In this paper, a mineral interactive computational fluid dynamics (MI-CFD) model encompassing combustion and mineral interactions is used to visualise intricacies of calciner internal aerodynamics and its effect on meal calcination levels and fuel burnout. Modelling results provide a cost-effective way to reduce flow stratification, which leads to the implementation of low-cost solutions.


Akhtar S.S.,Holcim Inc. | Ervin E.,Holcim Inc. | Raza S.,Cinar Ltd | Abbas T.,Cinar Ltd
IEEE Cement Industry Technical Conference (Paper) | Year: 2013

In the North American energy market, natural gas prices have been gradually decreasing during the past several years, primarily due to advances in shale gas extraction techniques. The availability of cheaper natural gas (NG), while seen as an attractive short-term fuel switching option, is viewed with caution by most cement plants due to long-term procurement concerns. Also, due to traditionally higher NG prices, cement plants have invested heavily into solid fuels, including storage, grinding, handling, and dosing systems often achieving high thermal substitution rates of solid AFRs (Alternative Fuels & Raw Materials). As a result, a wealth of knowledge has been acquired on firing solid fuels, including some of the more difficult ones, e.g. higher sulfur petcoke and bigger size AFRs, where operational issues such as build-ups, emissions and production losses have been and are being minimized. Switching to gas firing, however, requires re-adaptation of combustion and process guidelines for a fuel which, although in principal is easier to burn, but has relatively lower radiative heat transfer and sharper burning characteristics than coal. As such, the plants, which have switched to NG firing, have observed inconsistent trends in production, energy and emissions performance, mainly due to the lack of sufficient information on combustion/process interactions of the two fuel types required for cost effective optimization. A NG flame ignites earlier, releases intense heat but lacks dissipation of heat as compared with a solid fuel flame, thereby requiring plant specific adjustments. This paper presents actual results of NG firing trials at selected cement plants along with MI-CFD predictions, subsequent to validation from the plant data, on four kiln and four calciners. Recommendations are also made to improve and optimize NG firing by taking into consideration the combustion and mineral interactions. © 2013 IEEE.

Loading Cinar Ltd. collaborators
Loading Cinar Ltd. collaborators