Introduction to Coal Moisture Control (CMC) Technology

Abstract: China is a major producer and consumer of coke; scientifically predicting the market demand for coke is significant for enterprises to make sound decisions and improve **macro-control. The domestic demand for coke in 2010, 2015, and 2020 was predicted using the industry analysis method, the elasticity coefficient method, and the regression analysis method respectively. Considering the advantages and disadvantages of each method as well as the actual conditions of China’s coke industry, the industry analysis method was used primarily for medium-term forecasts, while the elasticity coefficient method was used mainly for long-term forecasts, with the regression analysis method serving as a reference. After making appropriate adjustments, the predicted values for domestic coke demand in 2010, 2015, and 2020 were 233 million tons, 286 million tons, and 373 million tons respectively. Keywords: coke market ； Consumption analysis ； Demand forecasting ； Scientific Decision-Making Chinese Library Classification Number: F42 Document Code: A Article ID: 1004-4620(2007)05-0001-04 Analysis of China’s Coke Consumption and Demand Forecast WANG Yun1, CAO Guo-dong2 (1 Shanxi Academy of Social Sciences, Taiyuan 030006, China; 2 Shanxi University of Finance and Economics, Taiyuan 030012, China) Abstract: China is a major country in terms of coke production and consumption. Making scientific forecasts of market demand for coke is of great significance for enterprises to make correct decisions as well as for the government to improve its macro-control. In this paper, industry analysis, elasticity coefficients, and regression analysis are used to forecast domestic coke demand for the years 2010, 2015, and 2020. Since each method has its own advantages and disadvantages, and considering the actual situation of China’s coke industry, industry analysis is taken as the primary method, with the elasticity coefficient method playing a supplementary role and regression analysis serving as a reference. After appropriate adjustments, the forecasted domestic coke demand for 2010, 2015, and 2020 is 233 million tons, 286 million tons, and 373 million tons respectively. Keywords: coke market; consumption analysis; demand forecast; scientific decision-making 1 Introduction China is the world’s largest consumer of coke, a fact determined by its specific industrial structure, which is characteristic of an early stage of industrialization – that is, a primitive industrial structure and low levels of industrial technology. This is also determined by the historical development stage of China’s industry. Since 1986–2005, China’s apparent coke consumption has experienced sustained high growth, with an average annual growth rate of around 8%. In 1986, China’s apparent consumption of coke was only about 52.41 million tons, while by 2005 it had reached 230.43 million tons. Since 20a, the total consumption has increased by nearly 4.4 times, and overall, China’s coking coal consumption shows an upward trend. In 2006, the apparent national consumption of coke was approximately 2,831.8 million tons, representing a year-on-year increase of 17.32%; however, this growth rate decreased by 8.93 percentage points compared to the previous year ； It was 0.66 percentage points higher than the average growth rate during the 15th Five-Year Plan period, indicating that consumption remains in a phase of high growth. 　　Coke products are considered primary processed resources, and their uses span various industries; however, they are primarily used as basic raw materials in the steel and chemical industries within the industrial sector, which constitutes the main characteristic of coke consumption in China. Taking 1994 and 2003 as examples for coke consumption, in terms of energy consumption by sector, the industrial sector within the secondary industry is the main consumer of energy; the share of coke consumption in this sector was 96.79% and 97.56% respectively, with this proportion remaining relatively stable over the past 10 years. Among them, the share of coke consumption in the steel metallurgy industry has been increasing year by year; by 2005, it had reached over 85% of the total coke consumption in China’s steel metallurgy industry. Preliminary estimates suggest that in 2006, coke consumption for steel metallurgy production in China will account for around 87% of the country’s total coke consumption. 　　The global demand for metallurgical coke has been influenced by the development of technologies such as coal injection and direct reduction ironmaking. Decision-makers in the steel industry worldwide increasingly believe that ironmaking processes that do not rely on coke will not replace the current \"iron ore reduction method\" on a large scale over the next 20–30 years. Therefore, coke will remain the main raw material for the steel industry in the future, and there are no signs that coke used in casting within the machinery industry, or for producing synthetic ammonia and calcium carbide in the chemical industry, will be replaced by other products. Our country is also a major producer of coke in the world, but in the future, the supply and demand imbalance of coke in our country will be very prominent. Therefore, conducting analysis and research on the market demand for coke, as well as making scientific predictions, holds significant theoretical importance for **improving coke-related policies and formulating future development strategies for coke; it also has profound economic significance and **value. 　　Among the methods for predicting coke demand, the industry analysis approach is relatively more accurate, especially for short-term forecasts; the development goals of the major industries that use coke do not vary significantly ； When using the GDP per unit of energy consumption method (elasticity coefficient method), the prediction results tend to be quite inaccurate due to the many uncertain factors. In forecasting the coking coal demand for 2010 and 2015, a method based primarily on industry analysis specific to the coking sector was used, supplemented by the GDP per unit of energy consumption approach. 2 Industry Analysis 2.1 Current Status of Steel Production and Forecast for Coke Demand Economic development (particularly the growth in end-use consumer goods such as housing and automobiles) has driven sustained high growth in China’s steel production. Entering the 21st century, industrialization, urbanization, and the shift of manufacturing activities have driven high consumption of steel and rapid growth in its production in China. From 2001 to 2005, China increased its steel production by 22.53 million tons, 31.22 million tons, 40.09 million tons, 50.46 million tons, and 79.60 million tons respectively; over these 5 years the total increase was 224.10 million tons, representing an average annual growth rate of 21.78%, and accounting for 58.4% of the global increase in steel production. In 2006, the total steel production was 418.78 million tons, an increase of 65.38 million tons compared to 2005, representing a growth rate of 18.5% ； The growth rates are expected to be 15.5% and 12.2% in 2007 and 2008 respectively. Looking at China’s economic development, although the goals for economic growth during the 11th Five-Year Plan period were adjusted, the general direction remained unchanged; the national economy is expected to maintain a growth rate of around 8% in the next 10 years. China is currently building a moderately prosperous society, which will result in high demand for steel products; therefore, the period from 2005 to 2015 remains the golden age for the development of China’s steel industry. 　　**When formulating the steel industry policy and medium- to long-term plan in April 2005, the National Development and Reform Commission and the Chinese Academy of Engineering estimated the total amount of steel consumption, and on that basis predicted China’s steel consumption for various periods: the demand for steel in China was estimated to be around 300 million tons in 2005, 350 million tons in 2010, still 350 million tons in 2015, with it possibly dropping to 320 million tons by 2020. It is expected that demand for steel will reach a peak by 2015, at around 350 million tons. There will be a period of stable development thereafter, with possible slight declines. It is expected that in the first 20 years of the 21st century, China will reach the levels of total steel consumption and per capita steel production and consumption that are characteristic of developed countries around the world. 　　The steel industry is the main sector that consumes coke. Since 2005, the coke consumption in China’s steel industry has accounted for over 80% of the country’s total coke consumption (in foreign steel industries, coke consumption makes up 90% of the total). The basic raw materials for blast furnace iron production are iron ore and coke. In China’s steel production, the approach based on blast furnace iron production and converter steelmaking is unlikely to change in the next 15–20 years; therefore, coke will remain the fundamental feedstock for steel production in the future. Therefore, with the development of China’s steel industry, as well as high consumption of steel and rapid growth in its production, there will inevitably be an increase in the demand for coke. 　　Although China needs to phase out and shut down nearly 100 million tons of outdated steel production capacity over the next 10 years, the overall production capacity of China’s steel industry continues to expand rapidly. As new steel production capacity continued to expand, steel production remained on a rapid growth trajectory in 2005. In 2006, China produced 418.782 million tons of steel, an increase of 65.3325 million tons compared to the previous year, representing a growth rate of 18.48%. This amount accounted for 33.79% of the world’s total steel production, which was 1.2395 billion tons. It is estimated that an additional steel production capacity of around 100 million tons will be added by the end of 2007. An increase in steel demand and production capacity inevitably leads to an increase in coke demand. 　　Factors affecting the demand for coke in the steel industry include: 1) Direct reduced iron production. Due to its late start in the production of direct reduced iron, China’s production capacity lags behind, falling far short of demand. With the adjustment of China’s steel product structure, the proportion of electric-arc furnace steel is increasing continuously, while the supply and demand balance for high-quality scrap metal is strained, leading to a growing market demand for direct reduced iron as a substitute for such high-quality scrap metal. With the current annual production of electric arc furnace steel in China at 20 million tons, and assuming that direct reduced iron is used in amounts of 20% to 30%, the annual demand for direct reduced iron will reach 5 million tons. However, China’s current annual production capacity is only 400,000 tons. In recent years, China has successively built rotary kilns of different processes and scales in Tianjin, Shandong, Beijing, Sichuan, Fujian and other places to produce directly reduced iron, with some plans to expand their capacity. Relevant organizations in Shanghai Baosteel, Handan Magotan Steel, Jiaozuo Kaima, Fujian Datian, and other locations are actively preparing to include direct reduced iron in major scientific and technological projects, with tendering being conducted to attract investment. In the spring of 2008, direct reduction ironmaking will be officially launched at the Shijiazhuang Iron and Steel Plant. It is expected that within 10–20 years, direct reduced iron will not be able to change the existing steel production methods, but its output will increase. It is estimated that by 2015, the national production of direct reduced iron will reach 2 million tons, and this increase in direct reduced iron production will affect the demand for coke by at least 800,000 to 1.2 million tons (based on the fact that 0.4 to 0.6 tons of coke are required to produce 1 ton of pig iron). 　　2) Blast furnace coal injection is a new ironmaking technology that began to be widely used in the steel industry production in the 1960s. Our country was among the first in the world to adopt coal injection technology. Thanks to technological improvements during the 10th Five-Year Plan period, the average amount of coal injected per ton of iron produced in large and medium-sized blast furnaces across the country is 100–110 kg/t; in some cases, this figure reaches 250 kg/t, which is at the world’s advanced level. Blast furnace coal injection mainly uses anthracite, with only a few steel companies mixing in small amounts of bituminous coal. At present, the blast furnaces of enterprises such as Ansteel, Baosteel, Jiugang, SUGANG, and Shigang can all use bituminous coal for injection, and progress has also been made in the technology of oxygen-enriched coal injection in blast furnaces. With the advancement of coal injection technology, the amount of bituminous coal injected will increase significantly. In 2006, the coal injection rate for key steel enterprises across the country reached 135 kg/t, an increase of 11 kg/t compared to the previous year. The total amount of coal injected by these key steel enterprises throughout the year was 40.866 million tons, marking the best level in China’s history. In 2006, 9 enterprises across the country, including Baosteel, Changzhi, and Wugang, had a coal injection ratio of over 150 kg/t. It is estimated that by 2010, the amount of coal injected into blast furnaces will reach at least 50 million tons, and by 2015 it will reach 70 million tons. With the increasing use of coal injection in blast furnaces, the coke ratio required for operation will inevitably decrease. It is estimated that by 2015, about 56 million tons of metallurgical coke can be replaced (based on a coal-to-coke substitution ratio of 0.8), which directly affects the demand for coke. 　　3) Coke ratio per furnace load. Internationally, in industrially developed countries, the coke ratio per ton of steel produced has dropped below 300 kg/t. In China, the overall coke ratio for the steel industry fell below 400 kg/t for the first time in 2006, reaching 396 kg/t; however, there is still a gap compared to these levels. In some small and medium-sized enterprises in China, this ratio even exceeds 600 kg/t. Since the coke ratio per ton of steel produced in China is not expected to change fundamentally over the next 10 years, and based on an average domestic coke ratio of 400–500 kg/t, the total demand for coke in China’s steel industry is projected to rise year by year from 2005 to 2015. After that, it will remain stable before gradually declining. 　　4) Scrap steel utilization. According to data from the China Scrap Steel Application Association, the projected consumption of scrap steel in China for 2010, 2015, and 2020 was 75 million tons, 80 million tons, and 90 million tons respectively. 　　Based on the above analysis, factors such as the decline in the coke ratio per ton of steel produced in China’s steel industry and the increase in the coal injection ratio, the rise in direct reduction iron production in the country, as well as the recycling of scrap metal, efforts to save energy and reduce consumption, and structural adjustments within the industry, will lead to a reduction in coke consumption. Taking all the above factors into account, the forecasts for the domestic steel industry’s demand for coke in 2010, 2015, and 2020 are shown in Table 1. Table 1: Projections for domestic steel industry’s coke demand in 2010, 2015, and 2020, in 10,000 tons per year.
Year: 2010, 2015, 2020
Steel production: 42,000, 45,000, 48,000
Coke demand: 20,000, 21,000, 21,600
2.2 Coke demand in other industries
Since 2001, China’s machinery manufacturing industry has seen rapid development, with a growth rate of 15%–25% ； The growth rate of calcium carbide production is over 15%, and both the non-ferrous metals industry and the fertilizer industry have emerged from their difficulties. In 2002, ten non-ferrous metals saw a growth of 14.5%, fertilizers experienced a growth of 12.1%, and synthetic ammonia had a growth of nearly 10%. These industries are growing rapidly, and their consumption of coke is increasing accordingly. Based on rough estimates, the coking coal consumption in industries other than the steel industry in 2001 and 2002 was 29.14 million tons and 32.68 million tons respectively, with increases of 1.94 million tons and 3.54 million tons respectively on a year-on-year basis; the corresponding year-on-year growth rates were 7.12% and 12.16%. In 2003, other industries such as chemicals, non-ferrous metal smelting, and machinery manufacturing, which are not part of the steel industry, consumed approximately 38.47 million tons of coke, accounting for 23.60% of the total national coke consumption. In 2004 and 2005, the annual coke consumption in industries other than the steel industry was approximately 41 million tons and 46 million tons respectively. It is foreseeable that in the coming period, industries such as the chemical sector, non-ferrous metal smelting, and machinery manufacturing will continue to account for approximately 20% of the total national consumption of coke. In recent years, the production in China’s machinery manufacturing sectors such as automobiles, machine tools, power generation equipment, and electric motors, as well as in industries like chemicals, non-ferrous metals, and ferroalloys, has shown sustained rapid growth, with growth rates ranging from 25% to 30%. The growth rate for power generation equipment was as high as 99.9%, which is also a key reason for the strong demand for cast coke and similar products. At present, both China’s non-ferrous metals and machinery industries suffer from an overabundance of low-end products and low overall competitiveness. In the future, as total demand continues to grow, industrial upgrading will become an important step in the development of these industries. Therefore, the overall demand for products such as coke will continue to rise, and quality requirements will also increase further. The projected demand for coke in other industries in 2010, 2015, and 2020 was 55 million tons, 60 million tons, and 65 million tons respectively. 2.3 Forecast for Domestic Coke Demand 　Based on the analysis of coke demand in various industries mentioned above, it is predicted that the domestic coke demand in 2010, 2015, and 2020 will be 255 million tons, 270 million tons, and 281 million tons respectively. 3 Elasticity coefficient method: Research indicates that there is a quantitative relationship between coke consumption and various economic indicators, and this relationship exhibits stable patterns over the long term. This provides an empirical basis for making medium- to long-term forecasts of coke demand. Among the numerous regular quantitative relationships, two of the most significant parameters were selected: the relationship between the growth rate of coke consumption and China’s GDP growth rate, and the relationship between the growth rate of coke consumption and the growth rate of the steel industry, which is its largest consumer. Using these as fundamental parameters, the elastic coefficient method was applied to forecast China’s coke demand in the short, medium, and long terms. Other influencing factors were also taken into account to make appropriate adjustments to the initial forecasts, thereby obtaining more accurate and practical data on China’s coke demand. 3.1 Domestic coke demand forecasting model The elasticity coefficient method is suitable for medium- to long-term forecasting. The elasticity coefficient is a regular ratio between the growth rates of economic indicators. The elasticity coefficient of consumption is the ratio between the growth rates of already achieved economic indicators, and the natural extension of this coefficient to future periods is the elasticity of demand. China’s coke demand elasticity coefficient was derived on the basis of an analysis of the long-term consumption elasticity coefficient since 1986. 　　Between 1986 and 2005, the average annual growth rate of China’s total output in the metallurgical industry was 20.2%, while the average annual growth rate of domestic coke consumption during the same period was 8.5%. The ratio of these two figures (8.5%/20.2%) was 0.421; in other words, since 1987, the elasticity coefficient of coke consumption in the metallurgical industry, which is the largest consumer of coke, has been 0.421. 　　From this, the following mathematical model for predicting coke demand is derived: GN = L1 × S)^n, where GN represents the total demand in the forecast year ； 　　L1 —— Coke consumption in the steel industry during the base period ； 　　S — Expected growth rate of the steel industry ； 　　n — Number of years in the forecast period. 　　According to the development plans for the steel industry and projections by relevant research institutions, the expected growth rates for the steel industry over the next 15 years, across three five-year periods, have been set at 13.9% during the 11th Five-Year Plan period (2006–2010), 7.5% during the 12th Five-Year Plan period (2011–2015), and 8% during the 13th Five-Year Plan period (2016–2020). 　　Due to the accelerating pace of technological progress, the coke ratio per ton of metal produced in the metallurgical industry has been declining rapidly over the years, and this trend shows no sign of slowing down. As a result, the carbon coke consumption elasticity coefficient in the metallurgical industry decreased by approximately 0.01, which in turn led to a reduction in the overall carbon coke consumption elasticity coefficient of the national economy. Therefore, in this forecast, the elastic coefficients for the medium to long term (2015, 2020) in the model were adjusted by different amounts (0.411, 0.401). This revision and adjustment enhance the continuity and continuity between the predicted base value and past consumption levels and consumption growth rates. 3.2 Forecast for Domestic Coke Demand By applying the designed mathematical model, by inputting the established expected growth rates and planned growth rates for various periods, as well as relevant economic statistics, and using a rolling calculation method, the forecasted value for domestic coke demand is as follows: G2010=17 282×5≈22 962.97 (10,000 tons) ； G2015=G2010×5≈26,461.81 (10,000 t) ； G2020 = G2015 × 5 ≈ 30,094.97 (10,000 t). 　　Based on the above calculated values and various corrections and adjustments, taking into account the impacts of factors such as medium- to long-term prices and policies, the coke demand forecasts determined using the elasticity coefficient method for the years 2010, 2015, and 2020 are 200 million tons, 260 million tons, and 300 million tons respectively. 4 Regression Analysis: Utilize regression analysis or gray prediction methods to explore the relationship between coke consumption and GDP, and establish a mathematical model for predicting coke demand. 4.1 Analysis using SPSS software A quantitative study was conducted using SPSS software on coke consumption and GDP from 1986 to 2005. Through scatter plots (see Figure 1) and correlation analysis between the two (see Table 2), it was found that there is a significant linear relationship between coke consumption and GDP. http://www.dayejin.com/sdyj/sddyj/200705/image/1-1.jpg Figure 1: Linear relationship between coke consumption and GDP. Table 2: Coefficients (correlation analysis). Parameter, Unstandardized coefficient, Standardized coefficient, t-value, Significance level, 95% confidence interval for B, Standard error of B, Lower bound of Beta, Upper bound of Beta. (Constant), 4, 769.87, 0.5398, 4.836, 0.000, 3, 635.699, 5, 904.040. GDP, 0.081, 0.006, 0.950, 1.294, 0.000, 0.068, 0.094. Note: The dependent variable is coke consumption. 　　By plotting a scatter diagram with coke consumption as the dependent variable and GDP as the independent variable, and using the method of least squares to estimate the model parameters, while taking into account factors such as technological progress in the coking industry, it can be preliminarily determined that the regression model is: Yn = 3635.699 + 0.068Xn, where Yn represents domestic coke consumption ； Xn represents the gross domestic product ； n is the forecast year. 4.2 Regression model analysis Based on the predictions of the **Statistical Bureau and other research institutions, it is estimated that during the 11th Five-Year Plan period, China’s GDP growth rate will be slightly higher than the average annual growth rate of 7.8% recorded since the start of the reform and opening-up policy; the average annual growth rate is expected to be around 8.5%, with the total GDP exceeding 26 trillion yuan ； During the 12th and 13th Five-Year Plan periods from 2011 to 2020, China’s GDP experienced a phase of decline followed by a period of recovery. During the 12th Five-Year Plan period, the average GDP growth rate was around 8%, and the total GDP exceeded 42 trillion yuan ； “During the 13th Five-Year Plan period, the GDP growth rate is expected to be around 7%, and the total GDP will exceed 60 trillion yuan. 　　Based on these projections, the estimated domestic demand for coke is as follows: Y2010 = 3,635.699 + 0.068×260,000 = 21,316 (10,000 tons); Y2015 = 3,635.699 + 0.068×420,000 = 32,196 (10,000 tons); Y2020 = 3,635.699 + 0.068×600,000 = 44,436 (10,000 tons). 5 Conclusions of the 3 prediction methods There are many methods for predicting coke demand, but based on years of practical experience by the planning and research departments in the coke industry, it is believed that the industry analysis method (mainly the method based on industries that consume large amounts of coke) is more suitable for the conditions in China. Industries such as metallurgy and the chemical industry are the main consumers of coke in China; their consumption accounts for a large proportion of the total coke consumption. Moreover, trends such as increases in product output, coal consumption per unit of production, and advancements in energy-saving technologies are quite clear, making these factors reliable bases for predicting coke demand. The downside is that it is not suitable for long-term forecasting. The advantages of elastic coefficient analysis are its simplicity, ease of calculation, low cost, minimal requirement for data, and wide range of flexible applications. The drawback is that the analysis has a certain degree of locality and one-sidedness. Regression analysis is also a widely used quantitative forecasting method today, whose task is to determine the relationship between the predicted value and the influencing factors. But sometimes, in regression analysis, the choice of which factors to use and what form those factors should take is merely a guess; this affects the diversity of the factors as well as the unmeasurability of certain factors, thereby restricting regression analysis in some cases. Taking into account the advantages and disadvantages of the three forecasting methods—industry analysis method, elasticity coefficient method, and regression analysis method—as well as the trends in the internal and external environment of the coking industry, a forecast is made using the industry analysis method primarily for the medium term, the elasticity coefficient method primarily for the long term, with the regression analysis method serving as a reference. After making appropriate adjustments, the projected domestic demand for coke for the years 2010, 2015, and 2020 is 233 million tons, 286 million tons, and 373 million tons respectively.

The main thermal equipment for coking. 　　Structure: Modern coke ovens consist of a carbonization chamber, a combustion chamber, a regenerator, an inclined channel area, a furnace top, a foundation, flue ducts, etc. In the carbonization chamber, coal is heated in an air-free environment to turn into coke. A coke oven has dozens of carbonization chambers and combustion chambers arranged alternately, separated by refractory materials (silicon bricks). Each combustion chamber has 20 to 30 vertical flues. The preheated gas from the heat storage chamber (high-calorific-value gas is not preheated) and air meet at the bottom of the vertical flame channel to burn, providing heat to the carbonization chamber from the side. The regenerator is located at the lower part of the coke oven, and it uses high-temperature exhaust gas to preheat the gas and air used for heating. The chute area is an inclined passage that connects the regenerator and the combustion chamber. The part of the furnace above the carbonization chamber and combustion chamber is called the furnace roof, and its thickness is determined based on the strength of the furnace structure and the need to reduce the temperature of the furnace roof surface. The roof area contains coal loading holes and riser pipes that lead to the carbonization chamber, used for loading coal and removing the raw gas generated during the carbonization process. There are also fire viewing ports leading to each combustion chamber, used for temperature measurement and checking the flame; based on the results of these checks, the temperature and pressure are adjusted. The entire coke oven is built on a solid and level concrete foundation; each regenerator is connected to the flue gas ducts via exhaust gas plates, with these ducts being located within or on either side of the foundation, one end of each duct connecting to the chimney. 　　Type: A carbonization chamber is also known as a furnace hole; a coking oven consists of dozens of such furnace holes. Depending on the structure of the heating system, modern coking ovens come in various types, which can be roughly classified as follows: ① Double-chamber type, where ascending and descending airflow chambers are combined in pairs, with the entire combustion chamber consisting of several such double-chamber units ； ②Two-zone flame path design: on one half of the combustion chamber, the flame paths follow an upward airflow pattern, while on the other half, the flame paths follow a downward airflow pattern ； ③It features an overcrossing flame channel design; the various flame channels in the entire combustion chamber are divided into several groups, which are connected to the flame channel groups of adjacent combustion chambers through overcrossing flame channels. The production capacity of a coke oven is determined by the size of the carbonization chamber and the coking time. 　　Furnace construction and heating: The main parts of a coking furnace are constructed from silica bricks; to ensure good sealing, special-shaped bricks are used for construction. Typically, a large coking furnace requires more than 400 types of bricks, or even over 1,000 types. A coking furnace with 36 chambers and a volume of 35.4 cubic meters requires approximately 8,400 tons of refractory materials. Construction must be carried out in accordance with strict quality standards, and the properties of silica bricks should be fully considered during furnace drying to ensure proper operation and extend its lifespan. After the coke oven is baked, the expansion in the carbonization chamber area is nearly 200 millimeters. The daily expansion rate of the drying furnace is generally set to not more than 0.035%, with a drying period of 50 to 60 days. Due to the significant expansion that occurs during the heating up of coke ovens, certain equipment and structures connected to the oven body must be connected, fixed, and sealed only at the end of this process, once the expansion of the oven body has essentially ceased. 　　Regulating the temperature of coke ovens is done to maximize their production capacity and thermal efficiency. Temperature regulation is divided into three stages: at the beginning of operation, there are significant fluctuations in furnace temperature; the main task of temperature regulation is to ensure that the temperatures in all the combustion chambers remain balanced, by adjusting those chambers whose temperatures are too high or too low. When the coking time is gradually reduced to 16–18 hours, the formal temperature adjustment phase begins. At this stage, based on the uniform carbonization of the coke cake (the entire coke mass in the carbonization chamber) in both the vertical and horizontal directions, as well as on the requirement that the temperature at the center of the coke cake reach 950–1050°C, the temperature and pressure of the entire furnace heating system are adjusted. A suitable heating regime is established and maintained. The temperature adjustment process at this stage takes about half a year. Thereafter, it transitions to a regular temperature regulation phase, during which heating is adjusted in a timely manner based on changes in factors such as the coal feed, heating gas, and atmospheric conditions, so that the coke cakes in each carbonization chamber can be uniformly converted into coke within the specified coking time, both in the longitudinal and vertical directions. The heat consumption of coke ovens is an important indicator for evaluating the thermal management of coke ovens. Generally, when using coke oven gas for heating, the heat consumption per kilogram of dry coal is approximately 550 kcal ； When heated with blast furnace gas, it is about 630 kilocalories. 　　Furnace protection: During the heating phase of coke ovens, due to the nonlinear expansion of silica bricks, the expansion rates at the upper and lower parts differ, which may lead to the formation of stepped cracks. During normal production, due to the periodic loading of coal and removal of coke from the carbonization chamber, the furnace temperature fluctuates significantly, causing the masonry to undergo certain degrees of expansion and contraction. Additionally, the impact of various mechanical devices on the masonry can all lead to deformation and cracking of the masonry. Therefore, it is necessary to utilize the adjustable spring potential energy to apply a sufficient amount of protective pressure to the masonry in a consistent manner through furnace protection equipment, ensuring that the masonry remains intact and secure throughout the entire process from furnace heating and startup to normal operation. This protective pressure should be maintained even after the coke oven stops operating, with regular inspections and adjustments carried out. The total load exerted by the furnace-supporting iron components on the coke oven is, calculated based on the oven height, between 1.5 and 2.0 tons per meter. Due to the residual expansion of silica bricks and the cracks that inevitably occur, the length of the furnace increases over time. The normal annual expansion rate should not exceed 10 millimeters; in coke ovens with well-maintained furnace protection equipment, this annual expansion rate can be below 5 millimeters after two to three years of operation. The total expansion of the furnace head is one of the indicators of furnace aging. 　　The service life of a coke oven is generally around 25 years; with proper operation and maintenance, it can exceed 30 years. 　　Brief history of development: Before the 1930s, the volume of the carbonization chamber in coke ovens generally did not exceed 20 cubic meters. In 1927, the first large-capacity coking oven in Germany was put into operation, with a carbonization chamber height of 6 meters and an effective volume of 30 cubic meters. Starting in the 1960s, many **successively built large-volume furnaces. The large coke ovens that are currently in widespread use have a carbonization chamber height of 6 to 7.5 meters, a length of 15 to 17 meters, an average width of 0.4 to 0.46 meters, with an effective volume of around 50 cubic meters. 　　China’s first modern coking ovens were built and put into operation in Anshan in 1919, followed by others being constructed in Shijiazhuang, Shijingshan, Benxi, Dalian, Jilin, and other places. Due to the prolonged war, most of them were damaged. Between 1949 and 1959, 11 old coking ovens with 448 chambers were restored; 24 new or renovated coking ovens with 1,239 chambers were built. Starting in 1957, he designed coking ovens independently, and from 1965 he began researching and designing large-capacity coking ovens. In 1970, the first coke oven with 36 chambers, a height of 5.5 meters, and an effective volume of 35.4 cubic meters was put into operation, achieving good levels in all key performance indicators during production.

Hello, esteemed colleagues. I specialize in the research and development of coal moisture regulation technologies. Currently, the technology available in China is not yet very mature; in particular, there is no established technology that can serve as a reference for fluidized bed drying processes. I hope everyone will be willing to offer guidance in the future, so that we can all make progress together!

Coal moisture regulation technology is a method that removes a portion of the moisture from the coal before it is fed into the furnace, thereby ensuring stable moisture levels in the coal used in combustion. The coal moisture adjustment process employs strict moisture control measures to ensure that the moisture content of the coal fed into the furnace reaches the predetermined target value of around 6.5%. It ensures stable operation of the coke oven, achieving energy savings, increased production, and improved coke quality. Production practice has shown that by reducing the moisture content of the coal used in the furnace from 10% to about 6.5% after humidification, the carbonization time is shortened, the bulk density of the coal in the furnace increases, the production capacity of the coke oven rises by approximately 11%, and the heat required for coking is reduced by 12% ； The quality of coke is improved, with DI15150 and CSR increasing by 1–1.5 percentage points respectively. If the original coke quality level is maintained, 8% to 10% more weakly caking coal can be used. The low and stable moisture content of the coal used in charging helps facilitate the operation of coke ovens, extends their lifespan, and reduces the amount of coking wastewater generated. The application status of coal moisture control technology in our country is as follows: Japan provided assistance to our country, and the first set of coal moisture control equipment was put into operation at the Chongqing Iron and Steel Co., Ltd. coking plant in 1996. The coal humidification process in Chongqing Iron and Steel uses heat transfer oil as a heat medium; it absorbs the sensible heat from raw gas and flue gas, and then undergoes indirect heat exchange with wet coal in order to adjust the moisture content of the coal to be fed into the furnace. It was discontinued for various reasons and was not promoted. In 2007, the coal moisture control device designed by MCC Coking & Refractory Engineering Co., Ltd., which uses the backpressure steam generated from coke dry quenching for power generation as its heat source, was installed at Shanghai Baosteel and Taiyuan Iron and Steel Companies. The equipment is currently in the testing phase and is set to go into operation soon ； Pangang is under construction.

Let me add something: during the coal humidification process at Chonggang, the following issues have not been resolved. 1. The smoke and dust suppression systems attached to the coal transport vehicles are inadequate, resulting in a poor working environment for the workers, which discourages their use of these vehicles. 2. The inclination of the Y6 belt used to convey coal into the dryer is too high, around 65 degrees; moreover, the seals along this belt are not effective, causing dust to spread everywhere. 3. The jackets surrounding the rising pipes and the valves for hot kerosene are not originally imported from Japan, and their sealing elements tend to get damaged, leading to severe leaks of hot kerosene

May I ask the original poster, what should be the ideal moisture content of the coal used for the furnace?

Coal moisture control technology in China is not yet fully developed, and the existing systems for this purpose do not perform satisfactorily. However, newly built coking plants generally include facilities and interfaces for coal moisture control

The moisture content of coal used for charging furnaces is generally around 10%, but it can vary. For example, \"pacted coke\" requires a more stringent moisture level, typically between 9-11%

That’s good. I’m very interested in learning about coal moisture regulation. Currently, this technology is not yet well-developed in China, so it’s important for everyone to discuss and learn more about it, especially the successful experiences and relevant knowledge from abroad

Our company is planning to adopt the third-generation fluidized bed coal humidification technology! :loveliness:

I read in a book that the moisture content of coal used in furnaces is generally around 6%

For rammed coke ovens, a value of 9-11% is generally acceptable. .

The moisture content of coal used for coke making is generally around 10%; since the coke-making process requires the coal to be in a certain shape, it cannot be too dry. It is best to keep the moisture content of standard coking coal at around 6%; if it is too dry, a large amount of dust is generated, which increases the difficulty of dust removal as well as the associated costs. Controlling the moisture content of coal is primarily aimed at saving energy during the coking process and increasing coke production, while also improving the quality of the coke.

What is the investment required for equipment to humidify coal at a rate of 100 tons per hour? Is 20 million enough? The moisture content was reduced from 18% to 6%. Thank you!

Name: Project to Install Coal Moisture Control Equipment in the Coke Ovens of Baosteel’s Ironmaking Plant, Baosteel Co., Ltd. Summary: (3) Scale and scope of construction: It is planned to install a set of coal moisture control equipment capable of supporting the production capacity of 4×50-hole 6m coke ovens. The processing capacity of the coal humidification unit is 330 t/h. ⑸ Project investment: The total investment is approximately 155.23 million yuan. May I ask everyone, what is the approximate equipment investment for this project in ten thousand yuan? What is the moisture content before and after drying? Can the coking plant provide flue gas at over 600 degrees? Thank you!

The moisture content before and after drying has been determined. Recently, the lifting of the main equipment, namely the dryer cylinder, for Baosteel’s key technical renovation project in 2007 – the installation of a coal moisture control system in Baosteel’s coke ovens – was successfully completed. The project to install a coal moisture control device in the coke ovens, carried out by MCC Chenggong Shanghai Wuyie Technical Transformation Company, was one of Baosteel’s key technical transformation projects for the year 2007; it was also the first such installation project in the domestic industry. This project employs a coal moisture adjustment process (STD) that uses steam as the heat source. This process utilizes low-pressure steam from Baosteel’s existing pipeline network as a heat carrier to dry the coal being fed into the furnace, reducing the moisture content of the coal from 10.26% to approximately 6.5%. The most important component of this device is the dryer barrel in the drying unit; it has a large size, significant weight, and a considerable installation inclination, as well as a high installation height, all of which pose great difficulties during installation. In order to succeed in this task, the technical renovation company made thorough preparations in advance, including site preparation, laying steel slag, and constructing the roadbed framework. Regarding the positioning of the two 500-ton truck cranes, as well as the optimal routes for transporting the equipment to the site, and how the transport vehicles could reach the most suitable locations for lifting, the project’s technical staff and crane operators conducted multiple on-site surveys before the lifting operations. They also visited the equipment manufacturers several times to obtain detailed information about the equipment’s specifications. These efforts laid a solid foundation for the successful completion of the lifting task, earning high praise from the leaders of Baosteel present at the site. (Written by Chen Shunhua; Photos by Wang Chenhui)

Announcement on the Environmental Impact Assessment for the Project of Installing Coal Moisture Control Devices in the Coke Ovens of Baosteel’s Ironmaking Plant. Issued by: Shanghai Institute of Environmental Sciences. Date of issuance: May 10, 2007. The preliminary research work for the project of installing coal moisture control devices in the coke ovens of Baosteel’s Ironmaking Plant has already begun. In accordance with the requirements set out in Document No. Huanfa 2006[28] issued by the State Environmental Protection Administration on February 14, 2006, the following information is being made public: 1. Name and overview of the construction project: Name: Project of Installing Coal Moisture Control Devices in the Coke Ovens of Baosteel’s Ironmaking Plant. Overview: (1) Location of the project: Within the coking area of Baosteel’s First Ironmaking Plant, Fujin Road, Baoshan District. (2) Nature of the construction: Technical renovation. (3) Scale and scope of the construction: It is planned to install a set of coal moisture control devices capable of supporting the production capacity of 4×50 coke ovens with a diameter of 6 meters. The processing capacity of the coal humidification unit is 330 t/h. ⑷ Environmental protection: The main pollutant in this system is coal dust, with the primary sources of pollution being dryers, coal towers, various coal transfer stations, and coal transportation corridors. Coal dust primarily escapes into the atmosphere during operations such as drying and transportation, resulting in unorganized, continuous emission pollution. The control measures adopted include installing a total of 9 sets of pulse bag filters in dryers, coal towers, and various coal transfer stations. After dust removal, the exhaust gas is released through exhaust stacks 22 m or 24 m high, with the dust emission concentration at the discharge points being less than 35.6 mg/m3. The humidification section and the areas where the humidified coal is transported are designed to be enclosed, in order to prevent the release of coal dust and resulting secondary pollution. After implementing the above control measures, the dust emission from the coal humidification system and the Phase I coal processing system is approximately 35.6 t/year. Appropriate control measures are also taken for other issues such as solid waste and noise pollution. ⑸ Project investment: The total investment is approximately 155.23 million yuan. II. Name and contact information of the construction entity for the project: Construction entity: Baosteel Branch of Baoshan Iron and Steel Co., Ltd. Contact information: Baosteel Command Center, Fujin Road, Shanghai. Phone: 021-26649027; Fax: 021-26649227. Postal code: 201900. III. Environmental impact assessment agency and its contact information: Shanghai Institute of Environmental Sciences. Certificate level: Class A ； Certificate Number: Guohuanpingzheng Jia Zi No. 1801 Address: No. 508, Qinzhou Road, Shanghai ； Postal Code: 200233 ； Fax: 54485031 Contact person: Fang Cuizhen, Phone: (021)64085119×2614 extension ； Email: fangcz@saes.sh.cn IV. Procedures and main tasks for environmental impact assessment (1) Procedures ⑴ The project owner entrusts a qualified environmental impact assessment agency. ⑵ The project owner issues the first public announcement (covering 6 pieces of information). ⑶ The environmental impact assessment agency conducts on-site inspections, investigations into the current environmental conditions, and surveys of public opinions. ⑷ The environmental impact assessment agency prepares an environmental impact report. ⑸ The environmental impact assessment agency issues the second public announcement (covering 8 items). ⑹ The project owner submits the environmental impact report along with other relevant documents to the environmental protection authorities. ⑺ The environmental protection authorities grant approval. (2) Main tasks: ⑴ Project overview and project analysis ； ⑵ Review and Evaluation of Corporate Environmental Protection ； ⑶ Environmental impact identification ； ⑷Environmental characteristics of the construction area ； ⑸Compatibility between project construction and regional planning ； ⑹Impact analysis of ambient air, noise, and solid waste pollution ； ⑺Clean production analysis ； ⑻Feasibility analysis of pollution control technologies ； ⑼Public participation ； ⑽Environmental economic cost-benefit analysis ； ⑾Environmental Management and Monitoring Plan ； ⑿Conclusions and recommendations. V. Main matters and methods for seeking public suggestions and opinions (1) Content of seeking public opinions: This public announcement is primarily aimed at gathering the public’s views on the current environmental quality of the area where the project is planned to be constructed ； Understanding of the main environmental problems existing in the current regional environment ； Support for project development ； Suggestions for improving the environmental quality of the proposed site for the project ； The environmental issues that are of particular concern during the construction of this project ； Suggestions for addressing potential environmental issues that may arise during the construction of this project and after it is completed ； Suggestions for this public opinion survey. (2) Location and method of public announcement: This public announcement will be mainly made online, via: the Shanghai Environment Hotline website (http://www.envir.gov.cn) ； It is also publicly displayed on the website of the Shanghai Institute of Environmental Sciences (http://www.saes.sh.cn). VI. Methods for public feedback: After the publication of this information, the public may express their opinions and views on the construction of this project and the environmental impact assessment process through methods such as submitting comments on the website, sending emails to designated addresses, making phone calls, faxing messages, sending letters, or having face-to-face discussions. During the preparation of the environmental impact assessment report for this project, and before the report is finalized and submitted for approval, the project owner will conduct a second round of public participation, seeking further input from the public through methods such as distributing questionnaires and holding seminars. During this period, the public can still express their opinions through the website, by sending emails to designated addresses, by phone or fax, by writing letters, or in person. : We ask the public to provide as detailed contact information as possible when expressing their opinions, so that we can promptly provide you with relevant feedback. Public Participation Opinion Survey Form Name Age Gender Political affiliation Education level Occupation Workplace 1 Do you know that a coal humidification device will be installed in the coking area of Baosteel’s branch located on Fujin Road in Baoshan District? □ It was announced at a meeting ； □Seen in the media ； □I’ve heard others say it ； □Haven’t heard of it. Do you think the construction of this project will help increase the CO emission from coke ovens and the output of total coke? □ Very beneficial ； 　　　□May be advantageous ； 　　 □Unclear. 3 Do you think it is appropriate to build this project in the coking area of Baosteel’s branch located on Fujin Road in Baoshan District? □ Appropriate ； 　　　□Not suitable ； 　　 □Unclear. 4 Do you think the current environmental pollution control measures in coking are effective? □ Effective ； 　　　□Invalid ； 　　 □Unclear. 5 What do you think are the main environmental problems associated with coking at present? □ Noise ； □Vibration ； □Water pollution ； □Air ； □ Other 6: Do you think the environmental protection measures adopted for this project are effective? □ Effective ； 　　　□Invalid ； 　　 □Unclear. 7 Which factor do you think has the greatest impact on the environment during project construction: □ Noise ； 　□Construction material transportation ； □Dust ； □ Construction waste piled up in disarray ； □Other 8 Regarding environmental pollution issues that arise during construction, your attitude is: □Understanding ； □Report ； □complain ； □It doesn’t matter ； □Others　　　　 9 The environmental issue you are most concerned about after this project is completed and put into operation is: □ Noise ； □Vibration ； □Water pollution ； □Air ； □ For the other 10 pairs, your stance on building this project is □support ； □It doesn’t matter ； □Opposed 11. Please share your opinions on the construction of this project, your requirements, and your suggestions regarding environmental protection: