Choice of method iron and steel production

These Guidelines outline three tiers for calculating CO2 emissions and two tiers for calculating CH4 emissions from iron and steel production. The choice of a good practice method depends on national circumstances as shown in the decision tree in Figure 4.7 for CO2 emissions and Figure 4.8 for CH4 emissions: Decision Tree for Estimation of CO2 Emissions from Iron & Steel Production and Decision Tree for Estimating of CH4 Emissions from Iron and Steel Production. The Tier 1 method is based on national production data and default emission factors. It may lead to errors due to its reliance on assumptions rather than actual data for the quantity of inputs into the sinter production and iron and steel production sector that contribute to CO2 emissions. Therefore, the Tier 1 is appropriate only if iron and steel production is not a key category. Default emission factors are provided for sinter production, blast furnace iron making, direct reduced iron production, pellet production, and each method of steelmaking. The primary sources of emissions are the blast furnace iron making, and steelmaking. The Tier 2 method for estimating CO2 emissions from iron and steel production is based on data for the known consumption of raw materials, including reducing agents, and industry-wide data. It uses a mass balance approach and material-specific carbon contents. The Tier 2 method is not applicable to estimating CH4 emissions. The Tier 3 method requires plant-specific emissions or activity data aggregated to the national level for estimating CO2 and CH4 emissions.

Figure 4.7 Decision tree for estimation of CO2 emissions from iron and steel production

Figure 4.7 Decision tree for estimation of CO2 emissions from iron and steel production

Ipcc Tier Methodology Images

Note:

1. See Volume 1 Chapter 4, Methodological Choice and Identification of Key Categories (noting Section 4.1.2 on limited resources), for discussion of key categories and use of decision trees.

Figure 4.8 Decision tree for estimation of CH4 emissions from iron and steel production

Figure 4.8 Decision tree for estimation of CH4 emissions from iron and steel production

Note:

1. See Volume 1 Chapter 4, Methodological Choice and Identification of Key Categories (noting Section 4.1.2 on limited resources), for discussion of key categories and use of decision trees.

METHODOLOGY FOR ESTIMATING CO2 EMISSIONS Tier 1 method - production-based emission factors

The Tier 1 approach for emissions from iron and steel production is to multiply default emission factors by national production data, as shown in Equation 4.4. Because emissions per unit of steel production vary widely depending on the method of steel production, it is good practice to determine the share of steel produced in different types of steelmaking processes, calculate emissions for each process, and then sum the estimates. Equation 4.4 considers steel production from Basic Oxygen Furnaces (BOF), Electric Arc Furnaces (EAF), and Open Hearth Furnaces (OHF). In the event that activity data for steel production for each process is not available, default allocation of total national steel production among these three steelmaking processes is provided in Table 4.1 in Section 4.2.2.3.

Equation 4.5 calculates emissions from pig iron production that is not converted into steel. It is preferable to estimate emissions from this production separately because the emission factors for integrated iron and steel production (BOF and OHF processes) take into account emissions from both steps.

Equation 4.6 calculates CO2 emissions from production of Direct Reduced Iron (DRI) for the Tier 1 method using a CO2 emission factor.

It is also good practice to estimate separately the emissions from sinter production and national pellet production, using Equations 4.7 and 4.8. Equations 4.7 and 4.8 should be used if the inventory compiler does not have detailed information about the process materials used. If the process materials are known, emissions should be calculated using the Tier 2 method.

Total emissions are the sum of Equations 4.4 to 4.8.

Equation 4.4

CO2 EMISSIONS FROM IRON AND STEEL PRODUCTION (TIER 1) Iron & Steel: ECO2, non-energy = BOF • EFBOF + EAF • EFEAF + OHF • EFOHF

Equation 4.5

CO2 EMISSIONS FROM PRODUCTION OF PIG IRON NOT PROCESSED INTO STEEL (TIER 1) Pig Iron Product Eco2, non-energy = IP • EFIP

Equation 4.6

CO2 EMISSIONS FROM PRODUCTION OF DIRECT REDUCED IRON (TIER 1) Direct Reduced Iron: em 2, non-energy = dri • efdri

Equation 4.7 CO2 EMISSIONS FROM SINTER PRODUCTION (TIER 1)

Sinter Production: ECO2, non-energy = SI • EFSI

Equation 4.8 CO2 EMISSIONS FROM PELLET PRODUCTION (TIER 1)

Where:

ECo2, non-energy = emissions of CO2 to be reported in IPPU Sector, tonnes BOF= quantity of BOF crude steel produced, tonnes EAF = quantity of EAF crude steel produced, tonnes OHF = quantity of OHF crude steel produced, tonnes

IP = quantity of pig iron production not converted to steel, tonnes DRI = quantity of Direct Reduced Iron produced nationally, tonnes SI = quantity of sinter produced nationally, tonnes P = quantity of pellet produced nationally, tonnes EFx= emission factor, tonnes CO2/tonne x produced

Tier 2 method

The Tier 2 method is appropriate if the inventory compiler has access to national data on the use of process materials for iron and steel production, sinter production, pellet production, and direct reduced iron production. In addition, as discussed in Section 4.2.2.5, there are a number of other process inputs and outputs that could be considered under Tier 2. These data may be available from governmental agencies responsible for manufacturing or energy statistics, business or industry trade associations, or individual iron and steel companies. The Tier 2 method will produce a more accurate estimate than the Tier 1 method because it takes into account the actual quantity of inputs that contribute to CO2 emissions.

In calculating pellet production emissions, energy consumption and heating value and carbon content of the fuel can be used similarly to the other methodologies.

Equation 4.9

CO2 EMISSIONS FROM IRON & STEEL PRODUCTION (TIER 2)

C02,non—energ

PC • CpC +E(COBa • Ca )+ CI • Cd + L • CL + D • Cd + CE • Cc

+ E(Ob • Cb )+ COG • Ccog - S • Cs - IP • Cp - BG • CE

44 12

CO 2,non-energy

Equation 4.10 CO2 EMISSIONS FROM SINTER PRODUCTION (TIER 2)

CBR • CCBR + COG • CCOG + BG• CBG +Z (PMa • Ca )-SOG• Q

44 12

Where, for iron and steel production:

'CO2, non-energy

= emissions of CO2 to be reported in IPPU Sector, tonnes

PC = quantity of coke consumed in iron and steel production (not including sinter production), tonnes

COBa = quantity of onsite coke oven by-product a, consumed in blast furnace, tonnes

CI= quantity of coal directly injected into blast furnace, tonnes

L = quantity of limestone consumed in iron and steel production, tonnes

D = quantity of dolomite consumed in iron and steel production, tonnes

CE = quantity of carbon electrodes consumed in EAFs, tonnes

Ob = quantity of other carbonaceous and process material b, consumed in iron and steel production, such as sinter or waste plastic, tonnes

COG= quantity of coke oven gas consumed in blast furnace in iron and steel production, m3 (or other unit such as tonnes or GJ. Conversion of the unit should be consistent with Volume 2: Energy)

S = quantity of steel produced, tonnes

IP = quantity of iron production not converted to steel, tonnes

BG = quantity of blast furnace gas transferred offsite, m3 (or other unit such as tonnes or GJ. Conversion of the unit should be consistent with Volume 2: Energy)

Cx = carbon content of material input or output x, tonnes C/(unit for material x) [e.g., tonnes C/tonne]

Where, for sinter production:

ECO2, non-energy = emissions of CO2 to be reported in IPPU Sector, tonnes

CBR = quantity of purchased and onsite produced coke breeze used for sinter production, tonnes

COG= quantity of coke oven gas consumed in blast furnace in sinter production, m3 (or other unit such as tonnes or GJ. Conversion of the unit should be consistent with Volume 2: Energy)

BG = quantity of blast furnace gas consumed in sinter production, m3 (or other unit such as tonnes or GJ. Conversion of the unit should be consistent with Volume 2: Energy)

PMa = quantity of other process material a, other than those listed as separate terms, such as natural gas, and fuel oil, consumed for coke and sinter production in integrated coke production and iron and steel production facilities, tonnes

SOG = quantity of sinter off gas transferred offsite either to iron and steel production facilities or other facilities, m3 (or other unit such as tonnes or GJ. Conversion of the unit should be consistent with Volume 2: Energy)

Cx = carbon content of material input or output x, tonnes C/(unit for material x) [e.g., tonnes C/tonne]

Equation 4.11 calculates CO2 emissions from production of direct reduced iron for the Tier 2 method based on fuel consumption and fuel carbon content. Emissions from DRI production are derived from combusting fuel, coke breeze, metallurgical coke or other carbonaceous materials, and are to be reported as IPPU emissions.

Where:

ECO2, non-energy = emissions of CO2 to be reported in IPPU Sector, tonnes

DRIng = amount of natural gas used in direct reduced iron production, GJ

DRIbz = amount of coke breeze used in direct reduced iron production, GJ

DRIck = amount of metallurgical coke used in direct reduced iron production, GJ

CNG = carbon content of natural gas, tonne C/GJ

CBZ = carbon content of coke breeze, tonne C/GJ

CCK = carbon content of metallurgical coke, tonne C/GJ

Tier 3 method

Unlike the Tier 2 method, the Tier 3 method uses plant specific data. The Tier 3 method provides an even more accurate estimate of emission than the Tier 2 method because plants can differ substantially in their technology and process conditions. If actual measured CO2 emissions data are available from iron and steelmaking facilities, these data can be aggregated to account for national CO2 emissions. If facility-specific CO2 emissions data are not available, CO2 emissions can be calculated from plant-specific activity data for individual reducing agents, exhaust gases, and other process materials and products. Total national emissions will equal the sum of emissions reported from each facility. Equations 4.9 through 4.11 describe the parameters that are necessary for an accounting of plant-specific emissions using the Tier 3 method and plant-specific activity data at a facility level. Plant-specific carbon contents for each material are required for the Tier 3 method.

METHODOLOGY FOR CH4

When carbon-containing materials are heated in the furnace for sinter production or iron production, the volatiles, including methane, are released. With open or semi-covered furnaces, most of the volatiles will burn to CO2 above the charge, in the hood and off-gas channels, but some will remain un-reacted as CH4 and non-methane volatile organic compounds (NMVOC). The amounts depend on the operation of the furnace. Sprinkle-charging will reduce the amounts of CH4 compared to batch-wise charging. Increased temperature in the hood (less false air) will reduce the content of CH4 further.

This section describes a Tier 1 default method and a more advanced Tier 3 facility-level method for CH4 from sinter production or iron production, both of which are similar to the approaches described for estimating CO2 emissions. There is no Tier 2 method. CH4 may be emitted from steel-making processes as well, however those emissions are assumed to be negligible. Therefore CH4 emissions from steel-making processes are not discussed here.

The Tier 1 methodology for CH4 is based on emission factors and national production statistics.

Equation 4.12 CH4 emissions from sinter production (Tier 1)

Sinter Production: ech 4, non-energy = si • efsi

Equation 4.13

CH4 emissions from blast furnace production of pig iron (Tier 1)

Pig Iron ProdUCtion: Ech4,non-energy = PI • EFPI

Equation 4.14

CH4 emissions from direct reduced iron production (Tier 1) Direct Reduced Iron Production: ECH4non-energy = DRI • EFDRI

Where:

ECH4, non-energy = emissions of CH4 to be reported in IPPU Sector, kg SI = quantity of sinter produced nationally, tonnes

PI = quantity of iron produced nationally including iron converted to steel and not converted to steel, tonnes

DRI = quantity of direct reduced iron produced nationally, tonnes

EFx = emission factor, kg CH4/tonne x produced

The Tier 3 method uses plant specific emissions data. If actual measured CH4 emissions data are available for coke production, these data can be aggregated to account for national CH4 emissions. Total national emissions will equal the sum of emissions reported from each facility.

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