Coke Dry Quenching

Coke Dry Quenching (CDQ) is an alternative to the traditional wet quenching of the coke. Coke is cooled using an inert gas in dry cooling plant, instead of cooling by sprayed water which results in high CO2 emissions and thermal energy loss.  This process allows the recovery of the thermal energy in the quenching gas which can then be used for the production of steam and electricity, for district heating, and/or for the preheating of coking coal.  

CDQ also improves the quality of coke and enables reduced coke consumption in the blast furnace.  As the product quality is improved, CDQ may also allow for the use of lower cost non-coking coal in the process, thereby reducing costs.  

CDQ is widely applied in Japan and Korea.  According to a report from 2007 (IEA, 2007, p112) less than 30% of plants in China have this technology, and the application remains very low in the EU, in the US and in Canada - primarily due to low electricity prices and high IRR expectations, but also due to environmental and safety concerns.  

Chinese flag Indian flag US flag This technology is regarded to have very high application potential for China and India, and high application potential for the United States. 

Development Status Products
Commercial
steel, coke, iron

Coke Dry QuenchingCosts & Benefits

Parent Process: Coke Making
Energy Savings Potential

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.

Chinese flag 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 Emission Reduction Potential

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)

Costs

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.

EU Flag 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)

Japanese flag 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

Coke Dry QuenchingSchematic

Coke Dry Quenching Publications

Global Warming Countermeasures: Japanese Technologies for Energy Savings / GHG Emissions Reduction

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 COemissions.  

Page Number: 

67

Energy Efficiency Improvement and Cost Saving Opportunities for the U.S. Iron and Steel Industry

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.

Page Number: 

79