Choice of method metallurgical coke production

The IPCC Guidelines outline three tiers for calculating CO2 emissions and two tiers for calculating CH4 emissions from coke production. The choice of a good practice method for estimation of CO2 emissions depends on national circumstances as shown in the decision tree in Figure 4.6 Estimation of CO2 Emissions from Metallurgical Coke Production. For CH4 emissions, use the decision tree in Figure 4.8.

Metallurgical coke is produced either at the iron and steel facility ('onsite') or at separate facilities ('offsite').The Tier 1 method calculates emissions from all coke production using default emission factors applied to national coke production.

The Tier 2 method for estimating CO2 emissions distinguishes between onsite and offsite coke production. It uses national activity data for the consumption and production of process materials (e.g., coking coal consumed, coke produced, and coal tar products produced). As discussed above, the Tier 2 method is not applicable to estimating CH4 emissions. The Tier 3 method requires plant-specific CO2 emissions data and plant-specific CH4 emissions data, or plant-specific activity data.

TIER 1 METHOD - PRODUCTION-BASED EMISSION FACTORS

Equation 4.1 calculates emissions from all coke production. The Tier 1 method assumes that all coke made onsite at iron and steel production facilities is used onsite. The Tier 1 method is to multiply default emission factors by tonnes of coke produced. Emissions should be reported in the Energy Sector.

Equation 4.1 Emissions from coke production (Tier 1)

ECO2 = Coke • EFCO2 and ECH4 = Coke • EFCH4 (To be reported in Energy Sector)

Where:

EC02 or ECh4 = emissions of CO2 or CH4 from coke production, tonnes CO2 or tonnes CH4 Coke = quantity of coke produced nationally, tonnes

EF= emission factor, tonnes C02/tonne coke production or tonnes CH4/tonne coke production

Note: The Tier 1 method assumes that all of the coke oven by-products are transferred off site and that all of the coke oven gas produced is burned on site for energy recovery.

TIER 2 METHOD

The Tier 2 method is appropriate if national statistics on process inputs and outputs from integrated and non-integrated coke production processes are available. Tier 2 will produce a more accurate estimate than Tier 1 because it takes into account the actual quantity of inputs into and outputs rather than making assumptions.

As expressed in Equations 4.2 and 4.3, Tier 2 estimates CO2 emissions from onsite coke production separately from off-site production. This separation is due to overlapping data requirements when estimating emissions from onsite coke production and emissions from iron and steel production.

Equation 4.2

CO2 EMISSIONS FROM ONSITE COKE PRODUCTION (TIER 2)

ECO 2, energy =

_ a

-

ECO2, energy = emissions of CO2 from onsite coke production to be reported in Energy Sector, tonnes

CC = quantity of coking coal consumed for coke production in onsite integrated iron and steel production facilities, tonnes

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 onsite coke production and iron and steel production facilities, tonnes

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

CO = quantity of coke produced onsite at iron and steel production facilities, tonnes

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

COBb = quantity of coke oven by-product b, transferred offsite either to other facilities, tonnes

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

For offsite coke production, the inventory compiler should use Equation 4.3. Total emissions are the sum of emissions from all plants using both Equations 4.2 and 4.3.

CO2 EMISSIONS FROM OFFSITE COKE PRODUCTION (TIER 2)

ECO2,energy =

CC • Ccc + £ (PMa • Ca )- NIC • CNlc - COG • CCOG - £ (COBb • Q )

ECO2, energy = emissions of CO2 from offsite coke production to be reported in Energy Sector, tonnes

CC = quantity of coking coal used in non-integrated coke production facilities, tonnes

PMa = quantity of other process material a, other than coking coal, such as natural gas, and fuel oil consumed nationally in non-integrated coke production, tonnes

NIC = quantity of coke produced offsite in non-integrated coke production facilities nationally, tonnes

COG = quantity of coke oven gas produced in offsite non-integrated coke production facilities nationally that is transferred to other facilities, m3 (or other unit such as tonnes or GJ. Conversion of the unit should be consistent with Volume 2: Energy)

COBb= quantity of coke oven by-product b, produced nationally in offsite non-integrated facilities and transferred offsite to other facilities, tonnes

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

TIER 3 METHOD

Unlike the Tier 2 method, the Tier 3 method uses plant specific data because plants can differ substantially in their technology and process conditions. If actual measured CO2/CH4 emissions data are available from onsite and offsite coke production plants, these data can be aggregated and used directly to account for national emissions from metallurgical coke production using the Tier 3 method. Total national emissions will equal the sum of emissions reported from each facility. If facility-specific CO2 emissions data are not available, CO2 emissions can be calculated from plant-specific activity data applying the Tier 2 method, Equations 4.2 and 4.3. Total national emissions will equal the sum of emissions reported from each facility.

Figure 4.6 Estimation of CO2 emissions from metallurgical coke production

Figure 4.6 Estimation of CO2 emissions from metallurgical coke production

Box 1: Tier 1

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