Coke cost performance comprehensive evaluation method

Abstract

The invention relates to a comprehensive evaluation method for coke cost performance, and aims to solve the technical problem of single dimension of coke evaluation, and the technical scheme is as follows: the comprehensive evaluation method comprises the following steps: testing physicochemical indexes of coke entering a plant, and quantitatively scoring the coke entering the plant from four dimensions of appearance quality, supply guarantee capability, stability and cost performance respectively, comprehensive scores are calculated and ranked, and according to the coke comprehensive score ranking, the revision of the purchase contract amount is guided. According to the method, the comprehensive coke cost performance evaluation model is established through comprehensive evaluation ranking of coke appearance, coke supply guarantee, coke stability and coke cost performance calculation, more scientific and comprehensive comprehensive evaluation is performed on the coke cost performance from four dimensions, and the problem that in the prior art, the coke cost performance is evaluated according to the purchase price is solved. And evaluation is one-sided and inaccurate. A coke evaluation system is perfected, and guidance is provided for purchasing coke and further reducing the fuel cost of the blast furnace.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical coke evaluation technology, specifically relating to a comprehensive evaluation method for the cost-effectiveness of coke. Background Technology

[0002] Currently, the types of coke used in blast furnaces on the market include: cooling methods such as dry quenching and wet coke; smelting methods such as top charging and tamping coke. Due to the different smelting and cooling methods of coke, the metallurgical properties of coke vary greatly, and the actual performance of blast furnaces also varies considerably.

[0003] Different coking plants use different types of coal, different formulas, and different quality control processes, resulting in significant differences in the physical and chemical properties of coke. The quality indicators of coke produced by different coking plants are not stable, and the fluctuation of furnace conditions in actual blast furnace production leads to increased costs.

[0004] The traditional method of evaluating coke in ironmaking only considers the influence of price factors, that is, judging whether to purchase based on the contract price and evaluating the cost-effectiveness of coke solely based on the purchase price, and then implementing a survival of the fittest after comparison. This is not scientific or rigorous enough.

[0005] Evaluating the cost-effectiveness of coke based solely on the price delivered to the plant is a one-dimensional approach that ignores other properties and functions. It fails to consider the impact of coke's physicochemical properties and stability on actual usage costs. Cost-effectiveness evaluation is merely a qualitative description and cannot fully describe the impact of coke on technical and economic indicators and economic benefits during the blast furnace smelting process. Summary of the Invention

[0006] The purpose of this invention is to solve the above-mentioned problems and provide a comprehensive evaluation method for the cost-effectiveness of coke.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A comprehensive evaluation method for the cost-effectiveness of coke includes the following steps:

[0009] Step 1) Test the physicochemical properties of the coke entering the plant;

[0010] Step 2) Quantitatively score the incoming coke from the following four dimensions:

[0011] (a) Appearance quality rating: Based on the uniformity of coke particle size, powder rate, proportion of coke with bubbles, number of cracks, appearance color, shape and impact sound characteristics, quantitative rating is carried out according to preset rules;

[0012] (b) Supply capacity rating: Scored according to the average daily intake volume;

[0013] (c) Stability score: scored according to the monthly quality pass rate;

[0014] (d) Cost-effectiveness rating: The specific steps for rating the cost-effectiveness of coke are as follows:

[0015] Step I) Calculate the dry basis price (excluding tax) of the coke delivered to the factory based on the ex-factory price and freight:

[0016] Dry basis price excluding tax = ;

[0017] In the formula: typical moisture refers to the actual moisture content measured during the coke testing upon arrival at the plant; contract moisture refers to the upper limit of moisture content stipulated in the purchase contract; 1.13 = 1 + 0.13, where 0.13 is the value-added tax rate.

[0018] Step II) Select any one of the incoming cokes as the benchmark coke, and compare it with other coke types. Calculate the change in coke ratio ΔK and the change in production ΔP based on the deviations in ash content, sulfur content, moisture content, calorific value, and M25. The specific rules are as follows:

[0019] ; An increase in coke ratio is positive, and a decrease is negative; an increase in output is negative, and a decrease is positive. The ΔK / ΔP coefficient is obtained by comparing the correlation between coke performance and fuel ratio of 12 blast furnaces.

[0020] Step III) Generate the converted unit price:

[0021] The converted unit price = dry basis price excluding tax × (1 + ΔK) + blast furnace processing fee × |ΔP|; where the blast furnace processing fee is in yuan / ton and is 200-300 yuan / ton;

[0022] Step IV) Rank the units according to their converted unit price; the lower the converted unit price, the higher the ranking.

[0023] Step V) Score the cost-effectiveness of coke based on the ranking of the converted unit price;

[0024] Step 3) Calculate the overall score and rank the students:

[0025] Overall score = Appearance quality score × 10% + Supply guarantee capability score × 10% + Stability score × 30% + Cost-effectiveness score × 50%;

[0026] The coke entering the plant is ranked according to its overall score. The higher the overall score and the higher the ranking, the better the cost performance.

[0027] Step 4) Based on the overall score ranking of coke, guide the revision of the purchase contract order quantity.

[0028] Furthermore, the appearance quality scoring criteria in step 2) are as follows:

[0029] ; Furthermore, the supply guarantee capacity scoring criteria in step 2) are as follows:

[0030] Furthermore, the stability scoring criteria in step 2) are as follows:

[0031]

[0032] Furthermore, the cost-effectiveness rating criteria in step V) are as follows:

[0033]

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] 1. This invention establishes a comprehensive cost-effectiveness evaluation model for coke by quantitatively calculating and comprehensively evaluating coke appearance, supply, stability, and cost-effectiveness. This model provides a more scientific and comprehensive evaluation of coke cost-effectiveness from four dimensions. Combined with a dynamic cost conversion model, it solves the problem of inaccurate and one-sided evaluations of coke cost-effectiveness based solely on purchase price in existing technologies. This improves the coke evaluation system and provides guidance for coke procurement and further reducing fuel costs for blast furnaces.

[0036] 2. This invention establishes a mapping relationship between coke physicochemical indicators and blast furnace production parameters through an economic dynamic conversion algorithm, introduces blast furnace processing fees to correct for output fluctuation costs, and outputs a converted unit price that reflects the true production cost, replacing the ranking of contract prices.

[0037] 3. According to actual measurements by a steel plant, after adopting the method of this invention, the cost of coke procurement decreased by 5.2% year-on-year, and the blast furnace fuel ratio decreased by 3 kg / t. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the process of the present invention;

[0039] Figure 2 This is a schematic diagram of the cost-performance rating process of the present invention; Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0041] A comprehensive evaluation method for the cost-effectiveness of coke includes the following steps:

[0042] Step 1) Test the physicochemical properties of the coke entering the plant;

[0043] Step 2) Quantitatively score the incoming coke from the following four dimensions:

[0044] (a) Appearance quality rating: Based on coke particle size uniformity, powder rate, proportion of coke with bubbly tip, number of cracks, appearance color, shape, and impact sound characteristics, a quantitative rating is conducted according to preset rules. The rating criteria are as follows:

[0045]

[0046] Bubble head coke: refers to the bubbly or foamy structure formed on the top of coke due to incomplete precipitation of volatiles during the coking process. Its proportion is obtained by randomly selecting 1 ton of coke samples and manually sorting and counting the weight percentage of bubble head coke.

[0047] Cracked coke: refers to coke with visible cracks ≥5mm in length on the end face. The percentage of cracked coke = number of coke with cracks on the end face × total number of coke tested × 100% of the total number of coke tested. The test object is coke with a particle size of 25-40mm.

[0048] Impact sound characteristics: crisp metallic sound: frequency > 2000Hz, sound intensity > 80dB; low-pitched sound: frequency < 1000Hz, sound intensity < 60dB (must be tested in an environment with noise < 40dB).

[0049] (b) Supply capacity assessment: Scoring is based on the average daily intake volume, with the following criteria:

[0050]

[0051] (c) Stability rating: Scored according to the monthly quality pass rate, with the following scoring criteria:

[0052]

[0053] The quality pass rate is the percentage of batches of coke whose monthly incoming inspection indicators meet the company's internal control standards. The pass rate is defined as simultaneously meeting the following criteria: ash content ≤ 13.0%; sulfur content ≤ 0.7%; M25 ≥ 80%; and heat resistance ≥ 62%.

[0054] Pass rate = (Number of qualified batches in the current month / Total number of batches in the current month) × 100%.

[0055] (d) Cost-effectiveness rating: The specific steps for rating the cost-effectiveness of coke are as follows:

[0056] Step I) Calculate the dry basis price (excluding tax) of the coke delivered to the factory based on the ex-factory price and freight:

[0057] Dry basis price excluding tax = ;

[0058] In the formula: typical moisture refers to the actual moisture content measured during the coke testing upon arrival at the plant; contract moisture refers to the upper limit of moisture content stipulated in the purchase contract; 1.13 = 1 + 0.13, where 0.13 is the value-added tax rate.

[0059] Step II) Select any one of the incoming cokes as the benchmark coke, and compare it with other coke types. Calculate the change in coke ratio ΔK and the change in production ΔP based on the deviations in ash content, sulfur content, moisture content, calorific value, and M25. The specific rules are as follows:

[0060]

[0061] An increase in coke ratio is positive, and a decrease is negative; an increase in output is negative, and a decrease is positive. The ΔK / ΔP coefficient is obtained by comparing the correlation between coke performance and fuel ratio of 12 blast furnaces.

[0062] Based on the "Design Specification for Blast Furnace Ironmaking Process" (GB50427-2015) and measured data:

[0063] Each ±1% increase in ash content affects the focal ratio by ±1.5% (measured values: 1.2-1.8%).

[0064] Sulfur content ±0.1% affects coke ratio by ±1.0% (industrial test data)

[0065] Moisture content ±7% affects coke ratio by ±1.4% and yield by ±10%.

[0066] Step III) Generate the converted unit price:

[0067] The converted unit price = dry basis price excluding tax × (1 + ΔK) + blast furnace processing fee × |ΔP|; where the blast furnace processing fee is in yuan / ton;

[0068] Among them, the blast furnace processing fee refers to the comprehensive cost of blast furnace smelting a unit of pig iron, excluding raw materials, including energy consumption (gas, electricity), labor, equipment depreciation, maintenance costs, etc. The value of this plan is 200-300 yuan / ton, which is determined based on the average value of the blast furnace workshop's ton iron processing cost in our company's financial annual reports from 2022 to 2024.

[0069] Step IV) Rank the units according to their converted unit price; the lower the converted unit price, the higher the ranking.

[0070] Step V) The cost-effectiveness of coke is scored based on the ranking of the converted unit price. The scoring criteria are as follows:

[0071]

[0072] Step 3) Calculate the overall score and rank the students:

[0073] Overall score = Appearance quality score × 10% + Supply guarantee capability score × 10% + Stability score × 30% + Cost-effectiveness score × 50%;

[0074] The coke entering the plant is ranked according to its overall score. The higher the overall score and the higher the ranking, the better the cost performance.

[0075] Step 4) Based on the overall score ranking of coke, guide the revision of the purchase contract order quantity.

[0076] Example 1: Optimal Procurement of Foundry Coke for Blast Furnaces

[0077] Background: A company needs to purchase foundry coke for blast furnaces. The candidate suppliers are Jineng Holding Coking (wet quenching) and Shanxi Coking Group (dry quenching). The method of this invention is used to evaluate their cost-effectiveness and optimize the procurement strategy.

[0078] Step 1: Physicochemical index testing

[0079] Jineng Holding Coking (Wet Quenching):

[0080] Ex-factory price: 980 yuan / ton; freight: 35 yuan / ton; moisture content: 8.2%; dry basis price delivered to the factory: 1030 yuan / ton.

[0081] Physicochemical properties: ash content 11.5%, sulfur content 0.6%, M25 82%, thermal strength 68%, cracked coke ratio ≤7%, dark gray appearance, and particle size uniformity meets the standards.

[0082] Shanxi Coking Group (Dry Quenching):

[0083] Ex-factory price: RMB 1150 / ton; freight: RMB 28 / ton; moisture content: 1.2%; dry basis price delivered to the factory: RMB 1175 / ton.

[0084] Physicochemical properties: ash content 10.8%, sulfur content 0.45%, M25 88%, thermal strength 76%, cracked coke ratio ≤3%, appearance silver-gray, and particle size uniformity meets the standards.

[0085] Step 2: Quantitative Scoring

[0086] Appearance quality rating:

[0087] Jineng Holding's cracked coke content is ≤7% (>5%), therefore it receives 0 points;

[0088] Shanxi Coking Coal has a cracked coke content of ≤3%, earning 1 point;

[0089] Appearance and color: Jineng Holdings dark gray 0 points, Shanxi Coking silver gray +1 point;

[0090] Overall appearance quality score: Jineng Holdings 0 points, Shanxi Coking Coal 2 points.

[0091] Supply guarantee capability rating:

[0092] Jineng Holding's average daily inflow is 450 tons / day, earning it 4 points;

[0093] Shanxi Coking Plant's average daily input is 320 tons / day, scoring 4 points.

[0094] Stability rating:

[0095] Jineng Holdings' pass rate is assumed to be 85% (80-90%), so it scores 8 points.

[0096] The assumed pass rate for Shanxi coking is 92% (90-100%), which scores 10 points.

[0097] Value for money rating:

[0098] Benchmark coke: Shanxi Coking (ash content 10.8%, sulfur content 0.45%, M25 88%).

[0099] Impact of deviations in Jineng Holdings:

[0100] Ash content increased by 0.7% → ΔK increased by 1.05% (1.5% × 0.7);

[0101] A 0.15% increase in sulfur content leads to a 0.15% increase in ΔK (1% × 0.15).

[0102] A 7% increase in moisture content leads to a 1.4% increase in ΔK and a 10% decrease in total yield.

[0103] A 7% decrease in thermal intensity leads to a 5.6% increase in ΔK (7 × 0.8%).

[0104] M25 decreases by 6% → ΔK increases by 4.5% (0.75% × 6);

[0105] Change in total coke ratio: +12.7%, change in total production: +10%;

[0106] Jineng Holding's converted unit price = 1030 × (1 + 12.7%) + 250 × 10% = 1185 yuan / ton (blast furnace processing fee is taken as 250 yuan / ton);

[0107] The dry basis price of Shanxi Coking Coal, excluding tax, is calculated as follows: (1150 ÷ ​​1.13) / (1 - 0%) + 28 / (1 - 1.2%) = 1017.7 + 28.34 = 1046.04 yuan / ton.

[0108] Therefore, the cost-effectiveness rating is as follows: Shanxi Coking ranks first with 50 points, and Jineng Holdings ranks second with 48 points.

[0109] Step 3: Calculate the overall score

[0110] Jineng Holdings:

[0111] Appearance 0×10% + Supply Guarantee 4×10% + Stability 8×30% + Cost-Effectiveness 48×50% = 0 + 0.4 + 2.4 + 24 = 26.8 points.

[0112] Shanxi Coking:

[0113] Appearance 2×10% + Supply Guarantee 4×10% + Stability 10×30% + Cost-Effectiveness 50×50% = 0.2 + 0.4 + 3 + 25 = 28.6 points.

[0114] Conclusion: Shanxi Coking Coal scored higher overall (28.6 points), and it is recommended to increase its procurement ratio to 70%; Jineng Holdings can be used as a supplementary supplier, with its proportion controlled within 30%.

[0115] Example 2: Procurement Decisions for Low-Sulfur Coke in Blast Furnace Injection Process

[0116] Background: A steel company plans to optimize the procurement of coke for its blast furnace injection process. The candidate suppliers are Henan Yichuan Coking (low-sulfur wet quenching) and Hebei Tangshan Coking (low-sulfur dry quenching). The optimal procurement plan is determined by the method of this invention.

[0117] Step 1: Physicochemical index testing

[0118] Henan Yichuan Coking Plant (Wet Quenching):

[0119] Ex-factory price: RMB 1050 / ton; freight: RMB 40 / ton; moisture content: 9.0%; dry basis price delivered to the factory: RMB 1100 / ton.

[0120] Physicochemical properties: ash content 12.0%, sulfur content 0.3%, M25 80%, thermal strength 65%, cracked coke ratio ≤6%, dark gray appearance, and particle size uniformity meets the standards.

[0121] Hebei Tangshan Coking Plant (Dry Quenching):

[0122] Ex-factory price: RMB 1220 / ton; freight: RMB 25 / ton; moisture content: 1.0%; dry basis price delivered to the factory: RMB 1240 / ton.

[0123] Physicochemical properties: ash content 11.5%, sulfur content 0.25%, M25 86%, thermal strength 72%, cracked coke ratio ≤2%, silvery-white appearance, and particle size uniformity meets the standards.

[0124] Step 2: Quantitative Scoring

[0125] Appearance quality rating:

[0126] If the percentage of cracked coke in Yichuan, Henan is ≤6% (>5%), 0 points will be awarded.

[0127] The percentage of cracked coke in Tangshan, Hebei Province is ≤2%, earning 1 point;

[0128] Appearance and color: Henan dark gray -0 points, Hebei silver-white -1 point;

[0129] Overall appearance quality score: Yichuan, Henan 0 points, Tangshan, Hebei 2 points.

[0130] Supply guarantee capability rating:

[0131] The average daily intake of the plant in Yichuan, Henan is 500 tons / day, earning 4 points.

[0132] The average daily intake of the plant in Tangshan, Hebei Province is 280 tons / day, earning 2 points.

[0133] Stability rating:

[0134] The pass rate in Yichuan, Henan was 88% (80-90%), scoring 8 points.

[0135] The pass rate in Tangshan, Hebei Province is 95% (90-100%), and the score is 10 points.

[0136] Value for money rating:

[0137] Baseline coke: Tangshan, Hebei (ash content 11.5%, sulfur content 0.25%, M25 86%, moisture 1.0%, heat strength 72%).

[0138] Impact of deviation in Yichuan, Henan:

[0139] An increase of 0.5% in ash content leads to an increase of 0.75% in ΔK (1.5% × 0.5).

[0140] A 0.05% increase in sulfur content leads to a 0.05% increase in ΔK (1% × 0.05).

[0141] Moisture content increased by 8.0% → ΔK increased by 1.6%, total yield decreased by 11.42% (1.4%×8 / 7, 10%×8 / 7).

[0142] A 7% decrease in thermal intensity leads to a 5.6% increase in ΔK (7 × 0.8%).

[0143] M25 decreases by 6% → ΔK increases by 4.5% (0.75% × 6);

[0144] Change in total coke ratio: +12.5%; Change in total output: +11.42%;

[0145] The converted unit price in Yichuan, Henan = 1100 × (1 + 12.5%) + 250 × 11.42% = 1266 yuan / ton; (blast furnace processing fee is taken as 250 yuan / ton).

[0146] The unit price of coking coal in Tangshan, Hebei is 1240 yuan / ton;

[0147] Rankings: Tangshan, Hebei ranked first with 50 points, and Yichuan, Henan ranked second with 48 points.

[0148] Step 3: Calculate the overall score

[0149] Yichuan, Henan:

[0150] Appearance 0×10% + Supply Guarantee 4×10% + Stability 8×30% + Cost-Effectiveness 48×50% = 0 + 0.4 + 2.4 + 24 = 26.8 points.

[0151] Tangshan, Hebei:

[0152] Appearance 2×10% + Supply guarantee 2×10% + Stability 10×30% + Cost-effectiveness 50×50% = 0.2 + 0.2 + 3 + 25 = 28.4 points.

[0153] Conclusion: Hebei Tangshan Coking Coal Mine scored higher overall (28.4 points). Its low sulfur characteristics significantly improved the coke ratio of the injection process and demonstrated outstanding stability. It is recommended to sign a long-term contract and increase the procurement ratio to 65%. Henan Yichuan Coal Mine should be used as an emergency backup, with its proportion controlled within 35%.

Claims

1. A comprehensive evaluation method for the cost-effectiveness of coke, characterized in that, Includes the following steps: Step 1) Test the physicochemical properties of the coke entering the plant; Step 2) Quantitatively score the incoming coke from the following four dimensions: (a) Appearance quality rating: Based on the uniformity of coke particle size, powder rate, proportion of coke with bubbles, number of cracks, appearance color, shape and impact sound characteristics, quantitative rating is carried out according to preset rules; (b) Supply capacity rating: Scored according to the average daily intake volume; (c) Stability score: scored according to the monthly quality pass rate; (d) Cost-effectiveness rating: The specific steps for rating the cost-effectiveness of coke are as follows: Step I) Calculate the dry basis price (excluding tax) of the coke delivered to the factory based on the ex-factory price and freight: Dry basis price excluding tax = ; In the formula: typical moisture refers to the actual moisture content measured during the coke testing upon arrival at the plant; contract moisture refers to the upper limit of moisture content stipulated in the purchase contract; 1.13 = 1 + 0.13, where 0.13 is the value-added tax rate. Step II) Select any one of the incoming cokes as the benchmark coke, and compare it with other coke types. Calculate the change in coke ratio ΔK and the change in production ΔP based on the deviations in ash content / sulfur content / moisture content / heat strength / M25. The specific rules are as follows: An increase in coke ratio is positive, and a decrease is negative; an increase in output is negative, and a decrease is positive. Step III) Generate the converted unit price: The converted unit price = dry basis price excluding tax × (1 + ΔK) + blast furnace processing fee × |ΔP|; where the blast furnace processing fee is in yuan / ton and is 200-300 yuan / ton; Step IV) Rank the units according to their converted unit price; the lower the converted unit price, the higher the ranking. Step V) Score the cost-effectiveness of coke based on the ranking of the converted unit price; Step 3) Calculate the overall score and rank the results: Overall score = Appearance quality score × 10% + Supply guarantee capability score × 10% + Stability score × 30% + Cost-effectiveness score × 50%; The coke entering the plant is ranked according to its overall score. The higher the overall score and the higher the ranking, the better the cost performance. Step 4) Based on the overall score ranking of coke, guide the revision of the purchase contract order quantity.

2. The method for comprehensive evaluation of coke cost-effectiveness according to claim 1, characterized in that, The appearance quality scoring criteria in step 2) are as follows: 。 3. The method for comprehensive evaluation of coke cost-effectiveness according to claim 1, characterized in that, The supply guarantee capacity scoring criteria in step 2) are as follows: 。 4. The method for comprehensive evaluation of coke cost-effectiveness according to claim 1, characterized in that, The stability scoring criteria in step 2) are as follows: 。 5. The method for comprehensive evaluation of coke cost-effectiveness according to claim 1, characterized in that, The cost-effectiveness rating standard in step V) is as follows: 。

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