Coke MakingTechnologies & Measures
|Technology or Measure||Energy Savings Potential||CO2 Emission Reduction Potential Based on Literature||Costs||Development Status|
|Coke Dry Quenching|
The most efficient coke ovens use CDQ and may use up to 40% less energy.
Approximately 1.5 GJ heat/t-coke (as ~ 400 - 500 kg high temperature steam/t-coke) and 0.55 GJ electricity/t-coke can be recovered.
For a plant with 450 000 t/y coke capacity (~1 million t/y BF capacity), 450 GWh/y of steam and around 150 GWh/y of electricity can be produced.
In China energy use for coking has decreased from 5.6 GJ/t-coke to 4.9 GJ/t-coke between 1995 and 2000, and further decreased to 4.2 GJ/t-coke by 2004, thanks to installation of more than ten coke dry quenching and other advanced quenching technologies.
CO2 savings in excess of 100 000 t/y are estimated by converting two 25 t/h capacity quenching systems from wet to dry (Climatetech Wiki, 2011)
Given about 300 Mt coke production without CDQ and savings of 600 g CO2/kWh, global CO2 emissions reduction potential is about 25 Mt CO2.(IEA, 2007)
Retrofit capital costs are 109.5$/ton coke. The cost of a 3-chamber plant can be estimated to be in the range of €60-70 million including equipment and installation costs.
In Europe equipment costs for a 2 million ton-coke/year plant are estimated to be €70 million. Depending on the electricity costs, the payback time can be 3 years - if all the steam is used for electricity generation. (IPPC BREF, p. 276)
In Japan, installation of a CDQ for a 450 000 t-coke/y capacity plant required ¥ 3 billion in equipment and ¥ 500 million in construction costs. With an electricity price of ¥17.99/kWh, approximate payback time was 3.6 years [1 ¥ = US $0.1257] (NEDO, 2008. p.67)
By converting two 25 t/h capacity quenching plants from wet to dry systems with 15 MW electricity generaton connected to each, US $9 million savings in electricity, and US $1 million in water related costs are estimated. (Climatetech Wiki, 2011)
|Additional Use of Coke Oven Gas|
Coke oven gas with a heating capacity of 6 to 8 GJ can be recovered for every ton of coke produced. (IEA, 2007)
In China, the potential of recovering COG from stand-alone coke enterprises was estimated to be around 250 PJ in 2005.
In China, CO2 emissions can be reduced by 25 million tons by recovering COG from stand-alone coke enterprises located near coal mines
By using COG as supplementary fuel in blast furnace, a steel mill in the US was able to save US $6 million annually. The project required an investment of around US $6.1 million, and had a payback time of just over one year.
|Automation and Process Control System||This technology can lead to fuel savings of about 10%. Estimated energy savings therefore are calculated to be 0.15 MBtu/ton (0.17 GJ/tonne) coke.||The technology leads to emissions reduction of 3.8 Kg CO2/tonne coke.||Retrofit capital costs are US $0.37/tonne coke.||Commercial|
|Coal Stamp Charging Battery|
This technology conserves coking coal due to use of higher proportion of high volatile & poor coal in the blend. It also increases the yield in the coke plant and may help improve the performance in heat recovery systems.
Emissions reduction is unlikely.
Investment and operational costs are reported to be reduced, due to reduced oven compartments and ability to use lower grade coal.
|Coal Moisture Control|
Coal moisture control costs for a plant in Japan were $21.9/t of annual steel capacity.
|Non-Recovery Coke Ovens||Electrical power of about 630-700 kWh/t-coke can be produced.||VOC and particulate matter emissions are mostly eliminated. SOx emissions are reduced but NOx emissions are likely to increase.||Investment cost of a US coking plant producing 1.2 million tons of coke per year was $365 Million – including coke oven facilities, coke handling/blending and power plant in 1998. For the energy facility, investment costs of only USD 140 million are reported for 1998 (IPPC, 2009).||Commercial|
|Variable Speed Drive Coke Oven Gas Compressors||Variable Speed Drive System on a compressor at a coke plant at Corus in The Netherlands saved 6 to 8 MJ/t-coke.||Emissions can be reduced by 0.12 kg CO2/t-coke.||Retrofitting cost is 0.47 $/tonne coke. The payback time was estimated as 21 years (US EPA, 16)||Commercial|
|Coke Stabilization Quenching||The technique can reduce coke consumption by 1-2% and may also reduce energy consumption in BF.||Dust emissions are reduced in Coke making. CO2 emissions may be reduced if the good quality coke results in energy savings in BF.||Cost data has not been provided.||Commercial|
|Single Chamber System|
SCSs offers an improvement in thermal efficiency from 38% to 70%.
The larger dimension ovens decrease the specific environmental emissions because fewer pushing operations are required per tonne coke. Emissions are directly proportional to number of pushes.
|SCOPE 21 - Next Generation Coke Making Technology||Coke-making energy consumption can be reduced by 21% (NEDO, 2008. p. 70).||For a plant with 1 million t/y capacity, CO2 reduction of 400,000 t-CO2/year are anticipated (NEDO, 2008. p. 70).||Production costs are 82% and construction costs are 84% of conventional coke oven.||Demonstration|
Coke Making Publications
The U.S. Environmental Protection Agency’s (EPA) energy guide, Energy Efficiency Improvement and Cost Saving Opportunities for the U.S. Iron and Steel Industry, discusses energy efficiency practices and technologies that can be implemented in iron and steel manufacturing plants. This guide provides current real world examples of iron and steel plants saving energy and reducing cost and carbon dioxide emissions.
The State–of-the-Art Clean Technologies (SOACT) for Steelmaking Handbook is developed as part of the Asia-Pacific Partnership on Clean Development and Climate program and seeks to catalog the best available technologies and practices to save energy and reduce environmental impacts in the steel industry. Its purpose is to share information about commercialized or emerging technologies and practices that are currently available to increase energy efficiency and environmental performance.
This revised 2008 version of the publication from New Energy and Industrial Technology Development of Japan includes information on innovative Japanese technologies for energy efficiency and for the reduction of CO2 emissions.