Blast furnace injection

USS installed three 9004ip conq>ressors and the as iated piping to boost the incoming coke oven gas pressure from 68.9 kPa (10 psig) to 379 kPa (55 psig) for injection into the furnaces. Since n(H enough coke oven gas would be available to completely satisfy the blast furnace injection requirements, USS purchased instrumentation and equipment so that natural gas could be added to supplement the coke oven gas [24]. 

Blast furnace injection system marketed by Clyde Pneumatic Handling, Doncaster,... 

In 1990, U.S. coke plants consumed 3.61 x 10 t of coal, or 4.4% of the total U.S. consumption of 8.12 x ICf t (6). Worldwide, roughly 400 coke oven batteries were in operation in 1988, consuming about 4.5 x 10 t of coal and producing 3.5 x 10 t metallurgical coke. Coke production is in a period of decline because of reduced demand for steel and increa sing use of technology for direct injection of coal into blast furnaces (7). The decline in coke production and trend away from recovery of coproducts is reflected in a 70—80% decline in volume of coal-tar chemicals since the 1970s. 

Worldwide demand for blast furnace coke has decreased over the past decade. Although, as shown in Figure 1, blast furnace hot metal production (pig iron) increased by about 4% from 1980 to 1990, coke production decreased by about 2% over the same time period (3). This discrepancy of increased hot metal and decreased coke production is accounted for by steady improvement in the amounts of coke required to produce pig iron. Increased technical capabihties, although not universally implemented, have allowed for about a 10% decrease in coke rate, ie, coke consumed per pig iron produced, because of better specification of coke quaUty and improvements in blast furnace instmmentation, understanding, and operation methods (4). As more blast furnaces implement injection of coal into blast furnaces, additional reduction in coke rate is expected. In some countries that have aggressively adopted coal injection techniques, coke rates have been lowered by 25% (4). 

A heat balance for the blast furnace produced by Michard et al. (1967), shows tlrat nearly 80% of the heat generated in tire furnace is used to produce and melt the iron and slag. The gas which emerges from tire first zone is further used to pre-heat the ah injected in the tuyeres in large stoves. The process thus runs at a vety high efficiency, botlr from tire point of view of tire amount of metal and slag produced and from the heat generation and utilization. 

Reducing coke oven emissions with other technologies - The use of pulverized coal injection technology substitutes pulverized coal for a portion of the coke in the blast furnace. Use of pulverized coal injection can replace about 25 to 40% of... 

Allyl diglycol carbonate (CR-39) is the most highly scratch resistant of the transparent plastics. Unlike most of the other transparent plastics that are TP, CR-39 is a TS plastic that has been in use for over a half century in applications such as bullet-proof shields, high temperature steel blast furnace eye and face guards, aircraft window side panels, etc. Processing methods include injection molding and casting. 

As indicated, pig iron production requires input of a reducing agent. Stahlwerke Bremen uses plastic waste as a substitute for fuel oil. Plastics are injected into the blast furnace in a similar way to coal powder or fuel oil. In order to remove fibres and metal particles a separation takes place. Large particles are separated via a screen of > 18 mm. The smaller plastic waste particles (< 18 mm) go to the injection vessel. There, an injection pressure of about 0.5 MPa is built up. Via a pneumatic process the plastics can be dosed and discharged into the blast furnace. The bulk density of the plastics has to be 0.3 tonnes/m. ... 

The simultaneous splitting and distribution of solids-gas mixtures for applications requiring multipoint injection, where the mixtures are transported usually under positive-pressure conditions. Some common examples include tuyere injection for blast furnaces, large burner nozzles for pulverized coal-fired boilers, small coal-fired plasma torches providing startup and support energy for boilers, injection of pulverized fuel into calciners, etc. 

The flow pattern of gas through blast furnaces was studied by VDEh (Veren Deutscher Eisenhiittenleute Betriebsforschungsinstitut) by injecting Kr-85 into the air stream entering the tuyeres of the 688 m furnace. A sketch and listing of pertinent quantities for run 10.5 of 9.12.1969 is shown in Fig. P13.1. Assuming that the axial dispersion model applies to the flow of gas... 

These factors have prompted two principal thrusts in ironmaking development. First, progress continues to be made in increasing blast furnace productivity and in decreasing coke rates. Coal (qv) injection to replace coke units has assumed a prominent role. Coal replaces coke on a nearly 1 1 mass basis, and coal injection rates of up to 250 kg/t of hot metal (thm) have been achieved. Injection of oxygen and other reductants besides coal are expected to be used more extensively. Increased additions of scrap, DRI, and HBI are expected to play a significant role in efforts to boost productivity and decrease coke rates. 

The final step is desulfurization. A number of processes have been developed which are suitable for removing H2S from coke-oven gas. These include using solutions of potassium carbonate, monoethanolamine (MEA), or ammonia to absorb the H2S. If ammonia solution is used as the absorbent, desulfurization is frequently combined with the ammonia removal step. Recovered H2S can be converted to elemental sulfur or sulftiric acid. The product remaining after all the above steps is cleaned coke-oven gas, some of which is used to heat the coke ovens and produce more coke with the rest going to the boiler house and/or the blast furnace for direct injection. 

---