Estimation of energy consumption for each process in the japanese steel industry
Energy Conversion & Management 40 (1999) 1129±1140 Estimation of energy consumption for each process in the Japanese steel industry: a process analysis Y. Sakamoto a,*, Y. Tonooka b, Y. Yanagisawa ca Research Institute of Innovative Technology for the Earth (RITE), 9-2, Kizugawadai, Kizu-cho, Souraku-gun, Kyoto, 619-02, Japan b Faculty of Economics, Saitama University, Shimo-okubo 255, Urawa, Saitama, 338, Japan c Faculty of Engineering, Global Environment Engineering Program, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113, Japan Received 6 July 1998; accepted 21 December 1998Abstract The energy consumption for each process in the Japanese steel industry is estimated by a statisticalprocess in order to evaluate the possibility of reducing energy consumption. The speci®c energyconsumption for each product is estimated and also for crude steel produced from an integrated steelplant route and an electric arc furnace route. The speci®c energy consumption is compared. The energyconsumption can be estimated from the production amounts of products for each process and for crudesteel. The energy consumption of blast furnaces is the largest and that of rolling and piping is the nextlargest. The speci®c energy consumption of crude steel produced from an integrated steel plant route isapproximately 2.6 times as high as that of an electric arc furnace route. # 1999 Elsevier Science Ltd.All rights reserved.Keywords: Speci®c energy consumption; Steel industry; Reduction1. Introduction Recently, the phenomenon of global warming caused by greenhouse gases from fossil fuel * Corresponding author. Tel.: +81-774-75-2304; fax: +81-774-75-2317. E-mail address: firstname.lastname@example.org (Y. Sakamoto)0196-8904/99/$ - see front matter # 1999 Elsevier Science Ltd. All rights reserved.PII: S 0 1 9 6 - 8 9 0 4 ( 9 9 ) 0 0 0 2 5 - 4
1130Table 1Annual fuel consumption of each production process in 1994 Iron and steel production process Iron making Steel making BOFa EAFb Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140Fuel type Unit Total Sintering Pelletizing Blast Other Ferroalloy Forging Casting Rolling Private Miscellaneous Coke Others furnace furnace production and power production Piping generationPetroleum fuelKerosene kl 421,707 ± ± ± ± 2291 210 83,190 30,754 17,021 99,514 65,052 55,976 ± 67,699Diesel oil kl 36,520 ± ± ± ± 501 1786 23 159 131 8091 2 16,499 11 9317A kl 636,118 1801 ± 439 1665 7097 9897 42,822 75,603 24,436 271,053 82,378 76,020 465 42,442heavy oilB kl 10,066 44 ± ± ± 2454 ± 1901 110 139 4973 ± 254 ± 191heavy oilC kl 1,267,304 1547 2382 39,039 ± 19,060 209 3260 35,618 18 660,207 453,733 13,274 ± 38,957heavy oilHydrocarbon oil kl 107,995 ± ± 1602 3 ± ± ± ± ± ± ± ± 106,390 ±LPGc ton 628,635 1438 ± 14,347 ± 1137 53,561 2349 23,396 7737 239,844 152,747 81,891 24 50,164Petroleum coke ton 636,643 ± ± 397,005 ± 10,308 ± 11,434 ± 36 ± ± 27 215,458 2375Non-petroleum fuelMaterial coal ton 40,726,243 ± ± 1,860,187 ± ± 9 ± ± 19 ± ± 48 38,865,980 ±Other coal ton 8,146,274 756,986 70,532 5,684,376 23,409 324,542 260,455 3855 ± ± ± 838,415 ± ± 183,704Coke ton 35,428,384 4,016,722 40,097 30,396,806 19,897 383,981 153,557 170,716 ± 78 43 ± 157,180 59,266 30,041Tar ton 193,240 1788 ± 136,592 ± 9 ± ± ± ± 15,886 6640 1294 30,789 242COGd 1000 m3 9,705,932 148,262 47,517 1,433,428 453 2695 290,743 29,252 30,915 1925 3,932,544 1,695,371 419,454 1,589,007 84,366BFGe 1000 m3 78,753,737 67,543 ± 28,491,859 25,607 1099 5455 730 1308 ± 1,421,151 32,752,038 314,807 15,652,050 20,090BOFGf 1000 m3 4,406,050 20,082 ± 1,149,023 309 4550 4017 3413 6244 ± 1,310,124 1,631,808 32,073 190,239 54,168EAFGg 1000 m3 6248 ± ± ± ± 6248 ± ± ± ± ± ± ± ± ±LNGh ton 481,298 ± ± ± ± 11,352 ± 6363 12,749 2211 334,096 42,694 64,707 ± 7126 3City gas 1000 m 544,536 3270 ± 12,672 128 57 2715 12,827 3966 4908 261,548 76,116 121,268 1221 43,840 3Oxygen 1000 Nm 7,184,032 ± ± 1,757,692 15,468 51,225 3,980,737 953,731 3442 6376 118,955 ± 286,598 ± 9808Electricity 1000 kWh 66,732,696 3,264,549 243,438 4,660,395 22,931 2,545,976 3,362,715 14,865,570 537,056 453,004 18,765,949 1,291,996 12,360,190 993,268 3,365,659 a Basic oxygen furnace. b Electric arc furnace. c Lique®eld gas. d Coke oven gas. e Blast furnace gas. f Basic oxygen furnace gas.Ã. g Electric arc furnace gas. h Lique®ed natural gas.
Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140 1131combustion has become a worldwide problem. Emissions of CO2 from fossil fuel combustion isa serious problem throughout the steel industry. The Japanese steel industry consumedapproximately 13±15% of the total energy among all Japanese industry in 1990 . In order to evaluate the possibility of reducing energy consumption, exact estimation of theamount of energy consumed in each production process is necessary. However, reports inwhich energy consumption for each process, product and production route are simultaneouslyevaluated are few to date. This is due to the small amount of data in detail for eachproduction process. In this study, in order to perform an exact estimate of energy consumption for eachprocess in the Japanese steel industry, a process analysis was adopted using statistical data.The speci®c energy consumptions (SECs) for each product and for crude steel produced fromintegrated steel plants (ISPs) and electric arc furnace (EAF) routes were estimated andcompared. To present the countermeasures of energy consumption taken in the Japanese steelindustry, the next generation of Japanese steel making methods is introduced brie¯y.Furthermore, reduction of energy consumption was estimated in the Japanese steel industryby about 2010.2. Methodology2.1. Outline of methodology for estimating energy consumption of each process The Yearbook of Statistics on the Iron and Steel Industries  is published by the Japanesenational government (Ministry of International Trade and Industry, MITI) as a listing ofstatistical data on the Japanese iron and steel industries. In these statistics, the Japanese iron and steel industries are divided into 14 processes and aredescribed according to the input±output balance of products, fuel, raw materials and electricityfor each process. As an example of the data we used in this report, Table 1 and Table 2 showthe annual fuel and electricity consumption of each process in 1994 and the annual steelproduction in 1994. In this report, in order to obtain more exact estimation than those in other recent estimates,Table 2Annual steel production in 1994 Production (ton/year)Production route Common steel Special steel TotalISP 57,419,064 (71.6%) 9,805,187 (54.3%) 67,224,251 (68.4%)EAF 22,816,793 (28.4%) 8,253,519 (45.7%) 31,070,312 (31.6%)Total 80,235,857 (100%) 18,058,706 (100%) 98,294,563 (100%)
1132 Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140the amount of energy consumption was estimated by adding some improvements based onTonookas and Haradas methodologies [3,4] and using the above statistics. As the fundamental estimation methodology in this report, energy consumption wasestimated from mass and energy balances of fuel, products and electricity for the 14 processesshown in Table 1 and by summing these consumptions of energy (in detail see Section 2.2). This methodology has the following characteristics:1. All forms of energy were considered as primary energy. In particular, electricity was Fig. 1. Schematic ¯ow to estimate energy consumption.
Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140 1133 classi®ed into purchased and generated electricity. The calori®c value of purchased electricity was estimated from the Japanese electricity con®guration , while that of the generated electricity was estimated from input amounts of fuel and purchased electricity for private power generation.2. Energy consumption for each process was estimated from mass and energy balances of fuel, products and electricity. These values were separately described as fuel (petroleum fuel and non-petroleum fuel), raw materials and electricity. The SEC (GJ/ton-product) which is expressed in terms of thermal energy per ton of each product was estimated from the obtained energy consumption for each process.Consequently, even in countries with a large dierence in energy consumption con®guration(e.g. the fuel consumption and the electricity con®gurations), it is possible to compare energyconsumptions for each process and product. Steel is made via two large production routes. One is the ISP route, which produces pig ironin blast furnaces with iron ore and coke as the major charged raw materials and producescrude steel in basic oxygen furnaces. The other is the EAF route, which produces crude steel inEAFs from scrap as the major charged raw material. For crude steel (cs) produced via thesetwo productions routes, the SEC (GJ/ton-cs) which is expressed in terms of thermal energy perton of crude steel was estimated.2.2. Estimation procedure For the 14 processes, energy consumption and SEC per ton of each product wereestimated by calculating mass and energy balances for fuel (19 kinds), products (includingby-product, e.g. scrap, dust, slug, etc.) and electricity (two kinds, not divided into two kindsin statistics). However, another furnace process which does not produce pig iron forsteelmaking use was included in the blast furnace process, because the amount of fuelconsumption, electricity and production amount (pig iron) are extremely small comparedwith those of another process. The amount of generated electricity was allocated to the processes of the ISP route(sintering, pelletizing, coke production, blast furnace, basic oxygen furnace, and rolling andpiping). All electricity that was consumed from private power generation sources was classi®edas purchased electricity in order to avoid an in®nite loop. Fig. 1 shows the schematic ¯ow to estimate energy consumption.2.2.1. Energy consumption and SEC1. For each process, mass and energy balances for the amounts of each fuel and electricity are calculated.2. Energy consumption is calculated by multiplying balanced amounts of each fuel and electricity by each calori®c value (high heating value (HHV)) [5,6]. The calori®c values in these calculations were 9.134 MJ/kWh  (conversion eciency 39.4%) and 10.978 MJ/kWh (conversion eciency 32.5%) for purchased and generated electricity, respectively. The latter
1134 Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140 was calculated by dividing the amount of energy consumption for private power generation by the amount of generated electricity. The amount of energy consumption was calculated by multiplying the balanced amounts of each fuel and purchased electricity by each calori®c value.3. SEC is calculated by dividing the amount of energy consumption for each process by the production amount for each product.2.2.2. SEC of crude steel for each production route The major energy and material ¯ows in steel making, for estimation of the SEC of crudesteel, were de®ned as shown in Fig. 2 where crude steel was classi®ed into common andspecial steel produced from the ISP and EAF routes. These values were estimated from theamount of energy consumed in each process in the preceding estimation. Since theconsumption amounts of products, fuel, raw materials and electricity of ferroalloy productionand rolling and piping are not divided into statistics for each production route, these Fig. 2. Major energy and material ¯ows in steel making.
Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140Table 3Annual energy consumption of each production process in 1994 Petroleum fuel Non-petroleum fuel Electricity SECProduction process (PJ/year) Total (GJ/ton-prod) ProdSintering 0.2 146.0 35.8 182.0 (8.4%) 2.1 Sinter orePelletizing 0.1 4.2 2.7 7.0 (0.3%) 1.9 PelletsBlast furnacea 16.0 889.0 51.4 956.4 (44.1%) 13.0 Pig ironFerroalloy production 1.7 21.7 23.3 46.7 (2.2%) 53.2 FerroalloysBOF 3.1 À13.9 36.9 26.1 (1.2%) 0.4 BOF csEAF 5.4 12.7 135.8 153.9 (7.1%) 5.0 EAF csForging 6.7 1.6 4.9 13.2 (0.6%) 24.7 ForgingsCasting 2.0 0.4 4.1 6.5 (0.3%) 18.4 CastingsRolling and Piping 53.5 133.3 187.5 374.3 (17.3%) 4.2 Final steel productsPrivate power generation 31.7 189.8 À221.5 0.0 (0.0%) 0.0b Generated electricityMiscellaneous 10.2 26.4 112.9 149.5 (6.9%) 1.5 All csCoke production 11.5 179.6 10.9 202.0 (9.3%) 7.5 CokesOthers 8.7 10.9 30.7 50.3 (2.3%) 0.5 All csTotal 150.8 1601.6 415.5 2167.9 (100%) 22.1 All cs a Including other furnace. b (GJ/kWh). Prod: product. cs: crude steel. 1135
1136 Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140amounts were allocated to each process from the production amounts of crude steelproduced from each route.3. Results and discussion3.1. Energy consumption and SEC Table 3 shows the annual energy consumption and SEC for each production process in theJapanese steel industry in 1994. Blast furnaces comprise the largest energy-consuming process(956.4 PJ/year). The amount of energy consumption from this process accounted for 44.1% ofthe total energy consumption (2.168 EJ/year), those of rolling and piping and coke productionfollow (374.3 and 302.0 PJ/year) and account for 17.3 and 9.3% of the total energyconsumption, respectively. The amounts of energy consumption of the primary processes of theISPs route (i.e. blast furnace, coke production and sintering) accounted for 61.8% of the totalenergy consumption. The SEC of ferroalloy is the largest (53.23 GJ/ton-prod), and those offorgings and castings follow (24.66 and 18.37 GJ/ton-prod), because the production has thevarious kinds for various special steels production and their small production amount. Theoverall SEC for all crude steel is 22.05 GJ/ton-cs. Fig. 3 shows the fraction of consumed energy by source type in the Japanese steel industryin 1994. Energy consumption from combustion of non-petroleum fuel is the largest andaccounts for 73.9% of the total energy consumption. Fig. 3. Fraction of consumed energy by source type.
Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140 1137 The amount of energy consumption of the primary process of the ISP route accounted for75.8% of the total energy consumption, and in the case of including by-product gases (COG,BFG and BOFG) in coal fuel, the amounts of energy consumption of combustion of coal fuelaccount for 98.9% of that of the ISPs. Consequently, the amount of energy consumption fromcombustion of ISP coal accounted for 55.4% of the total energy consumption. Table 4 shows the SEC of each steel for two production routes. The SECs of common steel,special steel and the average value of the ISPs route are approximately 2.8, 2.4 and 2.6 times aslarge as those of the EAFs routes. The reason for this is that the major charged raw materialfor the EAF route is scrap, which has been already reduced. The EAF route produced 31.6% of the total crude steel production in 1994 (see Table 1). Byabout 2010, the EAF industry expects the percentage of crude steel produced by EAFs to riseto 40% of Japanese steel production by developing a large size EAF which can produce largesize shapes. If its percentage rises to 40% as an ideal case, the overall SEC for all crude steelwill fall by 0.611 GJ/ton-cs. The reduction of energy consumption will be approximately 126.0PJ/year and will account for 5.8% of the total energy consumption.3.2. Countermeasures for reduction of energy consumption in the Japanese steel industry From the preceding estimate, it was found that the energy consumption of the primaryprocesses (blast furnaces, coke production and sintering) of the ISP route was extremely largein the Japanese steel industry. As a countermeasure for reduction of energy consumption,besides introduction of new technologies, increasing the production ratio of EAF steel wouldbe a signi®cant measure. On the other hand, several new technologies are being developed by the Japanese steelindustry. A new generation of steel making process to replace the blast furnace processpresently used, called the Direct Iron Ore Smelting Reduction (DIOS) process is beingdeveloped by the Japanese steel industry with national support. Fig. 4 shows a comparison of the DIOS process and the current blast furnace process. Thisprocess can replace coke ovens, sintering machines and blast furnaces. Furthermore, it makespossible ¯exible production in response to demand ¯uctuations. The development of a pilot plant producing 500 ton-pig iron/day has been completed.Currently, a construction plan for a commercial plant to produce 3000 ton-pig iron/day isbeing promoted. The amounts of energy consumption of this plant will be reduced byTable 4SEC of each crude steel for two production routesProduction route SEC (GJ/ton-cs) Common steel Special steel AverageISP 24.3 26.7 24.6EAF 8.7 11.3 9.4
1138 Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140 Fig. 4. Comparison of DIOS process and blast furnace process.
Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140 1139approximately 3±4% from that of the current blast furnace process as reported. Furthermore,the production cost (per pig iron) will fall by approximately 19% from that of the blastfurnace process . By this estimate, the overall SEC of crude steel produced by the DIOS process will fall byapproximately 0.598 GJ/ton-cs. For the case of 100% production by the DIOS process usedinstead of the current blast furnace process, the reduction of energy consumption would beapproximately 40.2 PJ/year. The Japanese steel industry expects that approximately 20% of the number of current cokeovens, sintering machines and blast furnaces will be replaced by the DIOS process by about2010. The reduction of energy consumption will be approximately 8.0 PJ/year.4. Conclusions In this report, the energy consumption for each process in the Japanese steel industry wasestimated by a statistical process analysis to evaluate the possibility of reducing energyconsumption. The SEC for each product and for crude steel produced from the ISP and EAF routes wasestimated. The energy consumption could be estimated from the amount of product for each processand for crude steel. The energy consumption of blast furnaces was the largest, and that ofrolling and piping was the next largest. The average SEC of crude steel produced from the ISP route was approximately 2.6 times ashigh as that of the EAF route. By about 2010, reduction of energy consumption in the Japanese steel industry will reachapproximately 133 PJ/year through an increase in the production ratio of EAF steel andthrough development of the next generation steel making process.Acknowledgements This work was sponsored by New Energy and Industrial Technology DevelopmentOrganization (NEDO). The authors are grateful to NEDO.References  Japan Environment Agency (JEA). Counter-measures to global climate change handbook. Daiichi Hoki Shuppan, 1992. Vol. 2. p. 13. [in Japanese].  Ministry of International Trade and Industry (M.I.T.I). Yearbook of iron and steel statistics, 1995 [in Japanese].  Tonooka Y. Estimation methodology of CO2 emission in Japan. In: Proceedings of the 11th Energy System- Economy Conference, Tokyo, Japan, 1995. p. 243, 248 [in Japanese].  Harada K et al. Kankyou futansei hyouka shisutemu kouchiku no tameno kiso chousa kenkyu houkokusho [Ecomaterials forum]. The Society of Non-Traditional Technology 1995 p.109 [in Japanese].
1140 Y. Sakamoto et al. / Energy Conversion & Management 40 (1999) 1129±1140  Kagaku keizai kenkyuusho kiso sozai no enerugi kaiseki chousa houkokusho, CERI-RP1992 No. 1, 1993, [in Japanese].  Japan Environment Agency (JEA). Taiki osen haishuturyou sougou chousa kaigi houkokusho [Report of amount of air waste materials in Japan]. 1990, [in Japanese].  Sekitan riyou sougou senta. Sekitan chokusetu riyou seitetu gijutsu no kenkyu [The research of direct iron ore smelting reduction process]. 1996, [in Japanese].