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Generally speaking, the temperature of the coke oven roof space refers mainly to the temperature of the raw coal gas in the space at the top of the carbonization chamber. Generally, to ensure the quality and output of chemical products, the spatial temperature at the top of the coke oven is strictly controlled, with the optimal temperature being around 800±30°C. However, in the actual production process, due to factors such as the height of the coke cakes in the coke ovens, changes in the specifications of the coaling mixture, moisture control, measurement frequency and errors, the discharge of raw gas, and leaks within the oven structure, the temperature in the roof space during coke production cannot be strictly maintained within the specified range. Therefore, by analyzing the various factors that affect the temperature in the coke oven roof space and combining these with actual production processes and operations to identify control methods, it is possible to ensure the proper quality and output of chemical products. I. The impact of the temperature in the furnace roof area on coke quality and chemical products. 1. The temperature in the space above the furnace is generally maintained at 800±30°C, with a maximum of 850°C. If this temperature is too low, it affects the proper maturation of the coke, preventing the production of high-quality coke. 2. High temperature in the furnace top area: Elevated temperatures lead to increased secondary cracking of the chemical compounds in the gas, resulting in a decrease in the production of tar, benzene, and ammonia, while the production of combined water and hydrogen cyanide increases. At the same time, due to methane decomposition, the content of heavy hydrocarbons decreases while the hydrogen content increases, resulting in a decrease in the calorific value of the gas. Furthermore, excessively high temperatures can also lead to a harsh working environment at the top of the furnace and damage to the iron components of the furnace. II. Factors affecting the temperature in the furnace roof space. 1. Air excess factor. The air excess factor is generally maintained between 1.15 and 1.20; a value that is too high causes the gas to burn at the lower part of the combustion chamber, resulting in high temperatures at the bottom of the carbonization chamber and lower temperatures at the upper part. This leads to a greater temperature difference along the walls as well as lower temperatures in the space above the furnace. 2. Standard temperature. The standard temperature is determined based on the quality of the coke and the temperature at the center of the coke cake; an increase in the standard temperature leads to an increase in the temperature in the furnace top space, and vice versa. 3. The amount of coal loaded; insufficient coal loading or an insufficient height of the coal cake results in an increased space at the top of the furnace, leading to a rise in the temperature there. 4. The pressure in the gas collection duct and the temperature in the furnace top space are primarily determined by the temperature of the raw coal gas. When the pressure in the gas collection duct increases, the flow rate of the raw coal gas decreases, allowing it to remain in the furnace top space for a longer time, which results in an increase in temperature. 5. The length of the coal briquettes and the cracks in them: If the length of the coal briquettes is insufficient or if there are cracks in them within the carbonization chamber, this leads to an increase in the space inside the furnace, as well as a rise in the temperature in the space above the furnace. 6. Inaccurate measuring tools or a lack of rigor in the measurement process lead to inaccurate readings of the temperature in the furnace roof area, failing to reflect the actual temperature there. III. Formulate control measures to address the above issues. 1. Based on changes in the characteristics of the blended coal, and in response to temperature fluctuations, the pressure in the main gas pipeline of the coke oven as well as the suction force in the coke oven are adjusted promptly. At the same time, the temperature in the roof space of the oven is measured regularly, and adjustments are made in a timely manner based on all these data. 2. Conduct regular exhaust gas analyses to keep track of the air excess factor in the coke oven; adjust the air supply accordingly based on the analysis results, to ensure uniform heating throughout the combustion chamber. 3. Based on the data obtained from measuring the temperature in the furnace roof area, the standard heating temperature for the coke oven should be adjusted promptly. The furnace operators must regularly check the combustion conditions in each vertical flue, carry out measurements across different rows, and control any deviations from the optimal temperature levels. The temperature measurement team should adjust the amounts of gas and air supplied accordingly, based on the temperatures measured during each shift, so as to keep the average temperature within the specified range. When high or low temperature readings are recorded during routine temperature measurements, the fire control team must take prompt action to address them; at night, the temperature monitoring staff handles these situations and keeps records of temperature control. 4. The ramming height of the coke cake must be strictly kept within the specified range; the slope on the side of the coke should not be too steep, in order to prevent an increase in the space above the furnace and a rise in the temperature of the raw gas ； In the event of coal collapse, the amount of coal fed into the furnace decreases, and it is necessary to promptly inform the furnace operator to control the temperature of that specific furnace separately ； Scrapers should be regularly installed on the push rod to clean the graphite at the top of the carbonization chamber, thereby preventing the accumulation of graphite there; such accumulation can affect coal charging and also hinder the flow of raw gas out of the carbonization chamber. 5. Regularly clean the rising pipes, gas collection pipes, and bridge pipes by spraying ammonia solution to ensure smooth discharge of raw gas. This prevents issues such as graphite and tar from clogging these pipes, which could lead to slow discharge of raw gas, longer retention time in the carbonization chamber, increased temperatures, and further breakdown of the raw gas within the chamber, thereby affecting the recovery of chemical products ； At the same time, it is also necessary to strictly control the stability of the pressure in the gas collection pipe, to prevent a negative pressure in this pipe for extended periods of time; such a situation could lead to negative pressure in the carbonization chamber, allowing air to enter the chamber and mix with the raw gas there, thereby reducing the amount of raw gas available. 6. It is necessary to strengthen the overall maintenance of the furnace body, including regular measurement and adjustment of the iron components used to protect the coke oven, as well as seasonal adjustments, to ensure that the masonry remains intact and airtight despite its own expansion and external forces ； At the same time, the main function of the protective plate and the furnace door frame is to distribute the protective pressure evenly and reasonably across the masonry, while ensuring sealing between the furnace head masonry, the protective plate, the furnace door frame, and the edge of the furnace door. During the hot repair sessions, it is necessary to regularly check for leaks in the burner head and furnace walls, in order to prevent gas and air from the combustion chamber from entering the carbonization chamber, where they can mix with the raw gas present there and participate in the combustion process ； During the hot repair, it is also necessary to promptly carry out sealing repairs on areas such as the root of the rising pipe, the furnace nozzle on the machine-side, and the dust removal hole ring at the furnace top, in order to ensure the airtightness of the carbonization chamber. 7. Develop a comprehensive and organized plan for coke oven production to ensure stable coking times ； Proper inspection and maintenance of production equipment and facilities are essential to reduce incidents of coke loss or the need to restart coke production due to equipment problems, thereby ensuring long-term stable operation of the coke ovens with normal production cycles. By analyzing the factors that affect the temperature in the roof space of coke ovens, corresponding measures are taken based on the actual operating conditions of each oven. These measures focus on stabilizing the coal mixture composition, ensuring proper coal loading procedures, enhancing cleaning of key areas of the oven and equipment maintenance, as well as precise control of oven temperature, thereby achieving stability and control over the temperature in the roof space of the coke ovens. This helps to improve the thermal efficiency of the ovens, ensure the quality of coke and the yield of by-products, and further advance the efforts to save energy and increase efficiency in our factory. Source: Wusitai Coking & Coke Making Workshop 1, Qinghua Coal Chemical, Inner Mongolia