Basic knowledge of the fire adjuster position

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I. Overview: Coal can be converted into coke by heating it to high temperatures in an environment free from air. This process, known as coking or the dry distillation of coal, is generally classified into low-temperature coking (500–550°C), medium-temperature coking (600–800°C), and high-temperature coking (900–1050°C), depending on the source of the coal and the intended purpose of production. Depending on the coking temperature, the yield, composition, and quality of the product vary significantly. The process used in our factory is a high-temperature coking process primarily focused on the production of metallurgical coke, and furnace temperature adjustment is an important task within this production process. II. Main Related Equipment and Maintenance 1. Gas Preheater Its function is to heat the coke oven gas with indirect steam to a certain temperature as it passes through the preheater, thereby preventing naphthalene and condensates from precipitating out of the gas and blocking pipes and fittings. 2. Water seal tank: Its function is to collect the condensate and tar discharged from the pipes; it enables the removal of condensate while also preventing gas leakage. In the daily operation of adjusting the fire, it is necessary to check regularly to ensure that the water inside remains at a full level. 3. Gas valve: ① The gas valve includes an increase/decrease valve and a switching valve. The addition and subtraction valves are used to regulate and cut off gas. The switching plug is connected to the pull rod via a lever; during switching, the pull rod moves the lever, thereby controlling the opening and closing of the switching plug. ②To ensure normal load on the switch and proper sealing, the switching valve should be cleaned every two weeks. The specific method is as follows: Perform this operation during a downward airflow; close the inlet and outlet valves, remove the handle and the screws at the back to access the core. Scrape off any oil residue from the core, clean it with kerosene, and finally wipe it dry with a cloth. Apply a small amount of butter evenly. Do not install it in the reverse direction, nor should the numbers be misaligned; it must be installed in its original position. After installing the valve, check the flame condition on top of the furnace. 4. Gas mixer: A gas mixer is installed in the blast furnace gas pipeline system; it is a device used to mix a portion of coke oven gas into the blast furnace gas. The mixer consists of two concentric tubes; the inner tube is equipped with many small holes, through which coke oven gas passes from between the tubes and enters the blast furnace gas pipeline. The pressure in the coke oven gas branch line should be about 200 Pa higher than that of the blast furnace gas. 5. Exchange valve (also known as exhaust gas disc). The function of the exchange valve is to control the amount of air entering the regenerator, as well as the amount of blast furnace gas and exhaust gas that is discharged. The switch disconnecter consists of a cylinder and two prong sections. The two channels in the bifurcated part are connected to the small flue openings of the two regenerative chambers, respectively, while the lower end of the actuator cylinder is in communication with the flue. There are two weight discs inside the cylinder; the upper one is the gas weight disc, and the lower one is the exhaust gas weight disc. The upper weight disc is connected to the rod core of the lower weight disc through a sleeve rod, while the exhaust weight rod is connected to the exchange chain via a small chain. One of the two prongs is connected to a one-meter tube. When heated with high-temperature gas, the blast furnace gas enters one of the two branches at the bifurcation point through a one-meter pipe, and is led into the small flue. (The air inlet at the top of the fork is blocked.) The other fork is in communication with the air, and air enters through the air inlet above that fork. When blast furnace gas is introduced, two weights inside the cylinder drop; the upper weight separates the air from the gas ； The lower weight separates the cylinder from the flue. After the exchange, the air inlet cover is sealed; the two weight disks are lifted to connect the flue opening at the bottom of the cylinder with the two branches, allowing the exhaust gases from the two regenerative chambers to enter the flue through the cylinder. When heated with coke oven gas, the one-meter pipe stopcock is closed, and the two air inlets above the bifurcation are both connected to the exchange chain. When air is introduced, the two air inlets are opened; the weight disk drops down to separate from the flue, and the air enters the corresponding two regenerative chambers through the two branches. After the switch is made, the two air inlets close, the weight disk is lifted, and the exhaust gases are discharged. A flap for adjusting suction is provided at the lower part of the cylinder. A baffle for adjusting the air intake volume is installed at the air inlet. To ensure normal load on the switch and prevent sticking, the gas lever and exhaust gas lever should be sanded with sandpaper once a week to maintain their smooth surface. Additionally, the shaft sleeves on the exhaust manifold should be cleaned and lubricated regularly. III. Quality Knowledge 1. Quality of raw coal The coal blending parameters required for producing first-grade metallurgical coke are shown in Table 1: Table 1 Quality parameters of blended coal Ash content Sulfur content Volatilize content Gel layer thickness Moisture content ≤9% ≤0.66% ≤26% >14mm 7-10% Among these, the moisture content of coal has the greatest impact on the process of controlling furnace temperature; for every 1% increase or decrease in the moisture content of the blended coal, the furnace temperature must be adjusted by 5-7°C. Therefore, during production, those responsible for controlling furnace temperature should pay close attention to the moisture content of the blended coal, especially on rainy days. If the moisture content is high, the standard temperature should be adjusted accordingly to ensure proper curing of the coke. 2. Coke quality: The quality of coke has a significant impact on blast furnace operation. Coke serves three functions in the blast furnace: ① It acts as a framework to maintain the permeability of the blast furnace ； ②Provide a heat source ； ③As a reducing agent for iron ore, the requirements for coke used in blast furnaces are: low ash content, low sulfur content, low phosphorus content, high strength, uniform particle size, density, low reactivity, and high strength after reaction ； The quality standards for coke produced by our company are shown in Table 2: Table 2: Corporate Standards for Coke Particle size, mm Criteria >40 >25 25 ~ 40 Ash content, Ad, % Grades I and II Not more than 12.00 12.01–13.50 Sulfur content, St,d, % Grades I and II Not more than 0.60 0.61–0.80 Mechanical strength – Crushing strength, M25, % Grades I and II More than 88.0 80–88 As agreed upon by both parties Supply and demand Wear resistance, M10, % Grades I and II Not more than 7.0 Not more than 8.5 Volatile matter, Vdaf, % ≤ 1.9 Moisture content, Mt, % 4.0±1.0 ≤6 Not more than 12.0 Amount of coke dust, % ≤ 4.0 8 12.0 The quality of coke is greatly influenced by the work done in adjusting its properties; to produce high-quality coke, it is essential that those responsible for such adjustments carry out their tasks strictly in accordance with the specified heating procedures. The main ones are: ① A proper and appropriate standard temperature ； ②The temperature difference between the machine side and the coke side is reasonable ； ③Uniform heating in all directions ； ④The horizontal temperature distribution is reasonable ； ⑤Establish a proper pressure system. 3. Quality of gas for heating: Our plant’s coke ovens are regenerative type, so when using coke oven gas for heating, it is necessary to pay attention to factors such as the calorific value of the gas and its moisture content, and make corresponding adjustments ； When using blast furnace gas for heating, special attention must be paid to its calorific value, as this value is closely related to blast furnace operations and therefore varies considerably. Additionally, fluctuations in the moisture content, dust level, and temperature of blast furnace gas also affect its quality.