Türkiye'deki çimento endüstrisinin yarattığı hava kirliliği ve modellenmesi

Abstract

Katı, sıvı ve gaz atıkların miktar ve derişimlerinin canlı ve cansız varlıkları olumsuz yönde etkileyecek düzeye ulaşması "Çevre Kirlenmesi " sorunu olarak bilinmektedir. Hava, su ve toprak kirliliği yanında radyoaktif atıklar ve gürültü de çevreyi etkileyen faktörler arasındadır. Sosyo-ekonomik etkinlikler veya doğal olaylar sonucu ortaya çıkan bu kirliliğe neden olan kirlilik kaynaklarından; önce önlem almak veya sonradan arıtma yöntemlerini araştırarak korunmak çevre korumasının ana ilkelerini oluşturur. Hava kirliliği problemleri yurdumuzun birçok yöresinde her geçen yıl daha belirgin bir hal almakta, hava kalitesi gittikçe kötüleşmektedir. Bu problemlerin yoğun yerleşim alanlarının bulunduğu yörelerde ve özellikle kış aylarında ölümcül boyutlara ulaşması bu konuda yakıt kaynaklı kirlenmenin önemini vurgulamaktadır. Sanayileşmenin yoğun olduğu endüstri bölgelerinde problemler sadece kış aylarında tehlikeli boyutlara ulaşmakla kalmamakta; sürekli hal alarak bütün yıl boyunca yaşanmaktadır. Çimento, ülkemizde pekçoğu kentsel yerleşim alanına kurulmuş olan büyük tesislerde üretilmektedir. Çimento sektörünün kirlilik düzeyi yüksektir. Çalışmamızda ülkemizdeki çimento sanayiinin oluşturduğu kirlilik seviyesinin belirlenmesi ve tesisler için oluşturulan emisyon faktörlerinin değerlendirilmesi yapılmıştır. Ülkemizde seçilen bir çimento fabrikasının azotoksit emisyonlarının değişimi saatlik, günlük, aylık ve yıllık bazda belirlenmiş ve bu değişimlerin nedenleri araştırılmıştır. Emisyonlardaki değişimin üretim sırasındaki işletme şartlarındaki değişime bağlı olduğu gözlenmiştir. Ayrıca tesislerin oluşturduğu kirlilik "Hava Kalitesi Model Programı" yardımıyla değerlendirilmiştir. Doğu, Batı ve Orta Anadolu Bölgesi' nde seçilen üç çimento fabrikasının yıllık ortalama azotdioksit emisyon dağılımı model programı yardımıyla belirlenmiş ve Hava Kalitesi Koruma Yönetmeliği' nde verilen uzun vade sınır değerlerinin aşılmadığı belirlenmiştir.

Air pollution is woven throughout the fabric of our modern life. A by product of the manner in which we build our cities, air pollution is waste remaing from the ways we produce our goods, transport ourselves and our goods and generate the energy to heat and light the places where we live, play and work. The major cause of all the air pollution is combustion. When perfect or theoretical combustion occurs, the hydrogen and carbon in the fuel combine with oxygen of the air to produce heat, light, carbondioxide and water vapour. However, impurties, in the fuel, poor fuel to air ratio, or too high or too low combustion temperatures cause the formation of such side products as carbonmonoxide, sulphur and nitrogen oxides, fly ash and unburned hydrocarbons all air pollutants. The sources of pollution are typically classified into the following five categories: 1- Fuel combustion in stationary sources: The first category includes all facilities where fuels are burned to provide either space or process heating. All fuels-coal, coke, fuel oil, gas and wood-contribute in varying degrees to total emissions. In most areas, the burning of these fuels accounts for the majority of sulphur oxide and particulate emission. Sources in category can be further subdivided according to the type of consumer; a- Steam-electric power plants, b- Industrial facilities, c- Houses and apartment buildings, d- Commercial, institutional and governmental buildings. 2- Mobile sources: This category includes road vehicles, ships, trains and aircraft. The fuels of primary concern are gasoline and diesel fuel by motor vehicles; diesel oil and coal burned in locomotives and aviation fuels in aircraft. Carbonmonoxide, oxides of nitrogen; hydrocarbons and particulates are pollutants of primary interest from this category of sources. 3- Industrial processes: This category includes all facilities that generate pollutants during the manufacture or handling of products, other than the pollutants emitted from the use of fuels. X 4- Disposal of solid waste: This category consists of the incineration or open burning of solid waste which can be a significant source of pollution. Such burning may take place either in large central facilities, such as municipial incinerators and open-burning dumps or at individual residences, factories or shops. 5- Evaporation of organic substances: Included in this category is the evaporation of gasoline and dry cleaning solvents. Emissions, air quality and meteorological data provide the basic information for understanding an area's air pollution problem. The accounting of air pollutant sources and their related emission rates for a given area is defined as an " emissions inventory ". Although many different procedures are available for compiling an emissions inventory, all of them depend on the use of average " emission factors ", since it is impractical to measure continuously or even periodicaly, the discharges of pollutants into the atmosphere from all sources. Emission factors have been formulated for most of the major types of sources. Cement production is one of the dominants sectors in Turkish industry. Due to its high energy consumption and dust emission potential, it is one the the sectors which is scrutinized for its rule as an air pollution source. Realiable emission calculations have not been made because of the lack of emission factors. In Turkey, the first cement plant was established in Darıca (Kocaeli) in 1912, with a capacity of 2.1 04 tonnes per year. At present there are 48 cement plants which have a total production capacity of approximately 32. 106 tonnes/year. These capacities classify Turkey as the eighth highest cement producer in the World and second in Europe. The difference between production and cunsumption makes cement a strong export commodity for Turkey. An emission factor is an average value which relates the quantity of a pollutant released into the atmosphere with the activity associated with the release of pollutants. Emission factors are rated according to their reliability and accuracy between A and E. An emission factor based on ten or more source tests would be rated A. Conversely a factor base on sinle observation of questinable quality or extrapolated emission factor would be rated D or E. The rating is scaled in 5 categories 1-5 by European Commuinity. It is important to estimate the contribution of the cement industry to present air pollution in Turkey. Also pollution characteristics of cement and other sectors of industry need to be determined in order to make life cycle analysis which is necessary for current practices. In this study, A type emission factors for different cement plants and country average for Turkey are reported. These factors include some or all of dust, CO, NO2 and SO2 and concentration of suspended particulate matter. The emission factors obtained from different plants are discussed and compared with the available data in the literature. Special care is taken to ensure representative sampling. The plants are visited prior to sampling, necessary sampling parts are choosen and attachment are prepared for probes. In the cement plants, the dust emission measurements were performed using SICK-SHC 2 and SHC 5 isokinetic samplers. The standards of these samplers refer to VDI-2066 and VDI-3950. For gaseous xiv emissions, the computerised system sends the pressure and temperature readings to data logger and automaticaly adjusted the opening at the tip of probe. MRU 95/3 - CD model electrochemical analyser working under TUV Guarantee and Binos 4.2 type equipment operating according to NDIR methods were used for NO and CO measurements, respectivey. For dust mass flow, CO, NO2 and SO2, three different hourly measurements are averaged. Table 1. Emissions Factors According To Average Capacity of Cement Plants In Turkey Investigation of the emission factors for cement plants in Turkey show that the heaviest load to air is CO emissions followed by NO2, dust and SO2. The least number of measurements were understandably done for SO2. The SO2 emissions were found to be of trace amount or very low for the plants for which measurements were taken. This was due to the presence of Ca and Mg based absorbents of SO2 which contacted the gases above calcination temperatures and excess air conditions. Sulphonation under these conditions kept the SO2 emissions low arising from the combustion of coal petroleum coke and fuel-oil which ever is applicaple. A plot of CO emission factors together with capacity of the plants, gave a roughly inverse relationship with capacity. The values of the emission factors fluctuated immersely at plant capacities lower than 150 tonnes/h. This is explained by the plants with smaller capacity which are usually located in eastern Turkey and generally consist of machinery using older technologies. Then larger plants are built using more up to date and better control capabilities. Considering that the emission measurement in each plant were repeated three times using well established international standards, the emission factors reported for each plant may be rated as B. However, the national average for dust, CO, NO2 and emission factors are as A. From the average emission factors it is clear that the dominant emission from cement production in Turkey is CO XV followed by NO2, dust and SO2. The emission factors for German cement plants are 0.17,2,0.6 kg/tonnes clinker for dust, NO2 and SO2 respectively. On the national average Turkish dust emission factor is higher than German factors, however NO2 and SO2 emission are much lower. The low NO2 emission may be due to the differences in combustion conditions and reactions between nitrogen oxides and calcined solid products. The steadily growing cement industry in Turkey is pressurized by national and international emission factor limitations. At present on a national scale, dust emissions are higher than national and EC limitations but NO2, CO, and SO2 emissions are lower than both of these limitations. There is a strong move to bring cement emissions under control by using a number of measures. These measures include the renewable of filters, insulations of new cooling towers, control of open storage and continuous dust and CO, O2 and NOx monitoring and automation of some of the older plants. In the light of new environmental goals and to keep the pollution under control, all cement plant have agreed to renew old electrofilters. For the air quality modelling of the planned cement plant, Industrials Complex Source Long term Air Quality Modelling Programme is used. BREEZE AIR ISCLT3 of Trinity Consultants, Inc. was used to asses the impact of the emissions on the ambient air quality. The software is a "Windows based programme for the development of the EPA long term industrial source complex (ISCLT3) model. The software is capable of analysing the emissions of up to 1000 point, area, volume and open pit sources which may be grouped. Receptor grids as well as the discrete receptos can be defined to assess the air quality in a particular urban location. Concentrations can be calculated for all terrain elevations up to stack height and for receptors above ground elevation. It requiers summary meteorological data in a frequency distribution of wind spee, stability class and wind direction (star data). Star data was prepared from the long term monthly average climate data published by the Turkish Meteorology Office. The stabilty classes have been calculated by considering by the rules in AQPR and EPA regulatory options. Topografy around the plants was investigated and the relevant file was prepared by reading elevations on a 1/25000 chart in 250 m distances for a grid of 5 km by 5 km. The elevations and locations of discrete sources for which the air quality has to be calculated specifically is also read on the map. The locations of the emission sources are also indicated in the same grid file. In choosing a cement plant have also been investigated in different location (flat) and for applying two different meteorological data ( for two mixing height). The original modelling results are Tablo 3 and applying two different meteorological data's results are shown Table 4 and Table 5 applying different location's results are shown Table 6. XVI Table 3. The Original Plants Data