Waste Plastics injection in a Blast Furnace Nov14

Waste Plastics injection in a Blast Furnace...

Waste Plastics injection in a Blast Furnace The recycling of waste plastics (WP) by injecting them in a blast furnace (BF) is being practiced in few BFs especially in japan and Europe. The use of plastics in the BF also recovers energy from the WP and so it is sometimes considered as energy recovery. BF based ironmaking processes can utilize WP by any of the following methods. Carbonization with coal to produce coke. Top charging into the BF, although this generates unwanted tar from the decomposition of the plastics in the shaft. Gasifying the plastics outside the BF. The resultant synthesis gas is then injected through the tuyeres. Injection as a solid through the tuyeres in a similar way to pulverized coal (PC). Normally it is done as a co-injection of WP and coal into the BF. The first attempt for the waste plastics injection (WPI) in a BF was made at the Bremen Steel Works in 1994, with commercial injection starting a year later. The first integrated system for injecting plastic wastes was at NKK’s (now JFE Steel) Keihin Works in Japan. Injecting WP into BF has several environmental, operational and economic advantages. These include the following. Reduction in the amount of plastic wastes being landfilled or incinerated. Lower consumption of both coke and PC, thus saving coal resources. However, neither WP nor PC can completely replace coke. The amount of coke replaced in the BF is partly dependent on the quality of the WP. There is energy resource savings. The benefit of saved resources from mixed WPI is around 11 giga calories per ton (Gcal/t). There is decrease in the carbon dioxide (CO2) emissions since the combustion energy of WP is generally at least as high as that of PC normally injected,...

Understanding Blast Furnace Ironmaking with Pulverized Coal Injection Nov04

Understanding Blast Furnace Ironmaking with Pulverized Coal Injection...

Understanding Blast Furnace Ironmaking with Pulverized Coal Injection Injection of pulverized coal in the blast furnace (BF) was initially driven by high oil prices but now the use of pulverized coal injection (PCI) has become a standard practice in the BF operation since it satisfies the requirement of reducing raw material costs, pollution and also satisfies the need to extend the life of ageing coke ovens. The injection of the pulverized coal into the BF results into (i) increase in the productivity of the BF, i.e. the amount of hot metal (HM) produced per day by the BF, (ii) reduce the consumption of the more expensive coking coals by replacing coke with cheaper soft coking or thermal coals, (iii) assist in maintaining furnace stability, (iv) improve the consistency of the quality of the HM and reduce its silicon (Si) content, and (v) reduce greenhouse gas emissions. In addition to these advantages, use of the PCI in the BF has proved to be a powerful tool in the hands of the furnace operator to adjust the thermal condition of the furnace much faster than what is possible by adjusting the burden charge from the top. Pulverized coal has basically two roles in the operation of a BF. It not only provides part of the heat required for reducing the iron ore, but also some of the reducing gases. For understanding the HM production in a BF with the injection of pulverized coal, it is necessary to understand what is happening inside the BF as well as the chemical reactions and the importance of permeability within the furnace and how the raw materials can affect this parameter. The BF is essentially a counter-current moving bed furnace with solids (iron ore, coke and flux), and later molten...