Pot grate

Fig. 9.8 Two-pot grate furnaces for the heat treatment of (iron ore) pellets [B.16].

During a pot grate test the following parameters are determined and may be varied ... 

In a pot grate as shown in Fig. 9.9, the different process stages occur intermittently, one after the other. When the flow of gas is reversed, the temperature of the peripheral... 

Iron ore fines, limestone, dolomite, calcined lime, BF return fines and coke breeze were used and pot grate sintering experiments were carried out. Table I gives the chemical composition of the raw materials in the pot grate sintering test. The size distribution of raw material is shown in Table II. The raw material consists of iron ore fines, limestone, dolomite, calcined lime, BF return fines, coke breeze and sinter return fines. Table III shows the proportion of raw material. 

Table IV and Table V give coke breeze and limestone particle size distribution based on size analysis and the mean particle size of coke breeze and limestone was taken into consideration for analysis of the experiment results. In the pot grate sintering experiments, the mean particle size of coke breeze varied from 2.33 to 0.89 mm while the mean particle size of limestone varied from 2.38 to 1.10 mm to understand the effect of the mean particle on productivity and sinter properties. In each experiment, we just changed the mean particle size of coke breeze and limestone in the sinter mix and kept the taw material proportion constant. The pot grate sintering experimental program is shown in Table VI.

The pot furnace was constructed so that the radiant heat flux, which would prevail at the top of the fuel bed in a traveling grate stoker or incinerator, could be simulated under batch conditions. The burning rates could be determined by measuring the weight loss of the fuel bed as a function of time. The pot was constructed in two sections (Figure 1)- the overbed section (combustion system) and the fuel bed section (conversion system). Secondary air (overfire air) was supplied at a number of... 

They used a vertical cylindrical pot furnace of batch type, like Rogers. Two conversion concepts were simulated (a) overfired, updraft, fixed horizontal grate, and batch reactor and (b) underfired, updraft, fixed horizontal grate, and batch reactor. The diameter was 178 mm and primary air was supplied under the grate (Figure 7). A mirror was placed above the overbed section to be able to observe the combustion behaviour. 

For each run, the pot was loaded with a bed 125-130 mm deep, with an ignition source (char coal soaked in kerosine) on top of the bed. A low air flow was used during ignition. The ignition front propagating down towards the grate was monitored by thermocouples connected to chart recorders (Figure 7). 

The experiments were carried out in the commonly used cylindrical vertical pot furnace (Figure 8). The conversion concept was overfired, updraft, fixed horizontal grate, and batch reactor. The furnace dimensions were 250 mm i.d. and 300 mm in height. The furnace was constructed in two sections, here called conversion system and combustion chamber. This was one simple solution to be able to weigh the mass loss of the packed bed. 

Gort applied a typical pot reactor with vertical cylindrical shape. The conversion concept of Gort s conversion reactor was updraft, over-fired, fixed horizontal grate, and batch reactor. The reactor casing had a inner diameter of 0.3 m and a height of 0.8 m. The design of Gort s pot furnace is very similar to Koistinen et al s. 

Batch conversion systems hotnog fixed batch bed cocurr homog moving bed crosscurr homog moving bed fixed grate system overfired pellets in a stove or a pot furnace, see Figure 33. 

I am grateful to Hugh H. litis and for funds provided by the E.K. and O.N. Allen Herbarium Fund. Mark Wetter and Don Waller offered helpful comments, L.J. Valdes generously provided potted plants, Steve Solheim assisted during fieldwork, and Robert Kowal and Ray Curies provided guidance and the use of their laboratory facilites. Thanks also to Irene Baker for nectar analyses and Lucy Taylor for artwork. Additional funding for fieldwork was provided by the UW Botany Department J.J. Davis Fund, the... 

Financial support by the Deutsche Forschungsgemeinschaft (Schm 344/34-1,2 and Sa 1770/1-1,2) of the European Union under COST and FP7-People-2007-l-l (ELCAT) is gratefully acknowledged. We thank CONICET for continued support. We thank our colleague Prof A. Groli for useful discussions, and Dr. P. Quaino, Dr. A. Lundin, K. Potting and G. Soldano. 

---