How to formulate a coke oven large-cycle table

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This post was last edited by wangshaobo on 2025-9-5 08:39. How to formulate a coke oven large-cycle schedule? Developing a “large-cycle schedule” for coke ovens (also known as a coke oven cycling push-plan schedule or push-order arrangement table) is a highly important and technically complex task in coke oven production management. It is directly related to the balanced operation of the coke oven, the stability of the oven structure, equipment maintenance, and the uniformity of gas production. The following are the detailed steps, principles, and considerations for developing a coke oven large-cycle table. I. Core Purpose and Function: Protecting the furnace body – ensuring that each carbonization chamber of the coke oven is heated and cooled evenly as planned, thereby preventing severe fluctuations in the furnace’s temperature due to overly concentrated operations such as coke pushing and coal loading, which could otherwise damage the lifespan of the furnace bricks. Balanced production: Ensures that the workload of mechanical vehicles ( coke pushers, coal loading cars, coke stoppers, and coke quenching cars) is distributed evenly, avoiding uneven loads and guaranteeing a stable coke output. Stable gas generation volume: The coal loading and coking processes are periodic, and uniform operation can keep the generated gas volume relatively stable, facilitating the stable operation of the gas recovery system. Ensure safe production: A strict plan is the basis for avoiding mistakes such as repeated coke pushing or pushing coke at high temperatures. II. Basic knowledge for creating a large-cycle table: Coking time refers to the total time required for coal to be converted into coke within the coking chamber (for example: 25 hours). Operation time: The cycle time required to complete one coke pushing and coal charging operation (e.g., 10–12 minutes per furnace). Charging chamber number: Usually numbered in sequence from the machine side (operation side) of the coke oven to the coke side (e.g., 1#, 2#, 3# ...). Coking oven bank: Usually consists of several coking ovens (such as 2 or 4), with each oven having dozens to hundreds of carbonization chambers. Turnaround time: For a single carbonization chamber, it is the time interval between one push of coke and coal loading and the next such push. Theoretically, it equals the coking time plus the operating time. Turnaround time ≈ coking time (because the operation time is very short). III. Core principles for formulating the large-cycle table 1. The principle of sequential coke pushing throughout the furnace – this is the most fundamental principle. Quenching must be carried out in the order specified by the large-cycle table, rather than simply following the chamber numbers 1, 2, 3..., etc. 2. Equal-spacing arrangement (9-2 pusher sequence) – this is the most commonly used and important method of arrangement. Meaning: The difference between the coke pushing sequence number and the carbonization chamber number is a fixed value (or a multiple thereof). Taking the most common “9-2 sequence” as an example: Suppose a coke oven has 65 carbonization chambers. The coke pushing sequence is not 1, 2, 3, ..., 65. Rather: 1, 11, 21, 31, 41, 51, 61, 6, 16, 26, 36, 46, 56, 66, 10, 20, ... and so on. Why “9-2”? The first number assigned is 1; the next one is 1+10=11 (skipping 9 numbers); the one after that is 11+10=21, and so on. Therefore, the difference between the numbers of the carbonization chambers between two consecutive operations of pushing coke is 10 (that is, 9 chambers are skipped). “2” indicates that there are two maintenance numbers. Advantages: Furnace protection: The carbonization chambers where coking occurs in two consecutive cycles are physically far apart from each other (e.g., Furnace No. 1 and Furnace No. 11), preventing excessive concentration of the thermal field. The mechanical traveling distance is reasonable: Machines such as coke pushers do not need to travel long distances back and forth; they usually only have to move the distance between one carbonization chamber and the next, resulting in high efficiency and low losses. Uniform wear: Mechanical vehicles work uniformly across the entire furnace. 3. staggering mechanical operation times: For furnace groups with multiple coke ovens, the scheduling should involve staggered times for pushing coke from each oven, in order to avoid situations where multiple coke pushers and coal loading vehicles need to operate on adjacent ovens at the same time, resulting in conflicts and delays. 4. Consider that maintenance time (maintenance schedule) must be reserved in the plan (usually at least 2 hours per shift). This is achieved by setting a “maintenance number” in the coke pushing sequence. For example, in the 9-2 sequence of 65 carbonization chambers, chambers 5 and 55 are usually designated as maintenance chambers and no coke pushing schedule is arranged for them; this time is used for routine inspections, maintenance, and minor repairs of the equipment. IV. Specific steps for formulating the large-cycle schedule
Assumptions: Coke oven battery: 2 ovens (Oven No. 1 and Oven No. 2; each oven has 65 carbonization chambers. Coking time: 24 hours. Operation cycle time: 10 minutes per furnace. The 9-2 pusher sequence is adopted. Daily planned number of coke ovens to be pushed: 2 × 65 = 130 ovens (theoretical value). Three-shift production, with 8 hours of work per shift and 2 hours for maintenance. Steps to determine: Determine the total number of coke pushes per day: Theoretically, 24 hours / (10 minutes per oven) = 144 ovens/day. However, the maintenance time must be deducted: with 2 hours of maintenance per day, the coking time is 22 hours. Actual number of coke pushes per day: 22 × 60 / 10 = 132 batches/day. Planned coke pushing rate: 2 units × 65 furnaces = 130 furnaces/day. Therefore, the plan is feasible, with 2 furnaces of spare time. To arrange the order of coke pushing for a single coke oven: use the 9-2 sequence. The order of coke pushing for Oven No. 1 is: 1, 11, 21, 31, 41, 51, 61, 6, 16, 26, 36, 46, 56, 66, 10, 20, ... until all 65 numbers have been used (skipping the maintenance numbers 5 and 55). Determine the baseline time and rhythm: Set a baseline start time (for example, 8:00 am on the first day, starting coke pushing from chamber No. 1 of furnace No. 1). The coke pushing rhythm is one furnace every 10 minutes. Plan for alternating the operation of the two furnaces: 8:00 —— Furnace No. 1 starts pushing batch No. 1; 8:05 —— Furnace No. 2 starts pushing batch No. 1; 8:10 —— Furnace No. 1 starts pushing batch No. 11; 8:15 —— Furnace No. 2 starts pushing batch No. 11... and so on. This is the key to creating the macrocycle table. It is not allowed to push coke from two furnaces at the same time. Common method: Delay the planned start time of Furnace 2 by half a cycle (i.e., 5 minutes) relative to Furnace 1. For example: Such an arrangement allows mechanical operations to be completely staggered, achieving the highest efficiency. Enter maintenance time: In the schedule, when it is the turn of the maintenance numbers (5 and 55), that time period is left blank and marked as “Maintenance”. For example, it is estimated that around 16:00 in the afternoon, it will be the turn of unit 5 in furnace 1#; during this period (about 1 hour, as multiple shifts may share the same maintenance window), no operations are scheduled and the furnace is used for maintenance. Generate the final table: Use Excel or other production management software to create a detailed table with time on the vertical axis and furnace number on the horizontal axis. The table should include: planned coke pushing time, chamber number, actual coke pushing time, coke pushing current, and remarks (for recording cases of early or delayed execution, etc.). V. Examples of the master cycle (simplified excerpt): Planned time for Furnace No. 111; Carburization chamber number: Furnace No. 2; Remarks: 08:00–08:05–1, 08:10–08:15–11, 08:20–21–………………, 16:00–17:00 for maintenance; Maintenance plan in effect. 17:00–66–……………… VI. Execution and adjustments: Strict adherence is required – production must be carried out in strict accordance with the master cycle schedule. Recording and evaluation: The pusher coefficient (planned number of cars pushed out/actual number of cars pushed out) and the pusher uniformity coefficient (number of cars with a deviation from the planned time within ±5 minutes/total number of cars) are recorded to assess production stability. Flexible adjustment: In the event of special situations such as equipment failures or production accidents, it is necessary for the production scheduling department to make temporary adjustments to the plan while ensuring safety, in order to return to the original schedule as soon as possible. In summary, developing a large-cycle schedule is a systematic task that requires a thorough understanding of coke oven processes and equipment characteristics in order to achieve safe, stable, efficient, and long-lasting production outcomes. Today, this task is usually carried out automatically by specialized coking production management software (MES systems), but the principle remains the same.