In-and-out furnaces

Batch-type furnaces and kilns, termed in-and-out furnaces or periodic kilns (figs. 1.1 and 1.2), have one temperature setpoint, but via three zones of control—to maintain uniform temperature throughout, because of a need for more heat at a door or the ends. They may be loaded manually or by a manipulator or a robot. 

Fig. 3.10. Box furnace, in-and-out furnace, or soak pit with two rows of slabs.

Fig. 6.1. Side-fired in-and-out furnace (with car-hearth), 18 wide x 12 deep x 8 high iD. Adjustabie fiame burners give uniform heating width-wise/depth-wise double-stacked piers help bottom uniformity. (See also figs. 3.26 and 6.23.)...

Fig. 7.5. Back-wall-fired in-and-out furnace. Stacks without bottom openings (without barometric dampers) must have automatic furnace pressure control.

Air Drying Equipment. Tunnel kiln dryers (70) are long furnaces comprised of several zones of different temperature, humidity, and air flow through which the ware travels on a moving car or belt. These kilns afford continuous processing. Periodic kiln cross-circulation dryers (70) are box furnaces in which ware is stacked on permanent racks or on a car that can be shuttled in and out of the furnace. Fans or jets are used to circulate heat uniformly through the ware. The process is not continuous, but production rates can be enhanced by shuttling multiple cars. 

Fig. 1. Double glove-box system for the preparation and refining of actinide metals 1. RF heating system 2. Water cooled quartz vacuum furnace 3. Box filled with circulating nitrogen 4. -I- 5. Argon in and out filters filter 6. Stainless steel box filled with circulating argon 7. Vacuum lock chamber 8. Pump...

Calculate the temperatures in and out of the furnace and heat exchanger, and calculate the heat transfer area. 

Take a porcelain tube and place it in a furnace, which may be heated to a very high temperature the ends of the tube are closed by corks each pierced with two holes. The gas may be let in and out through one hole of each end through the other two holes is passed a tube of silvered brass, 8 mm. in diameter, running the length of the porcelain tube and through which a rapid current of cold water is passed. Finally, two small screens of unglazed porcelain separate the cool portions of the porcelain tube outside the furnace from the hot part inside. 

Tubular fouling by coke deposition on its inner wall has restricted the development of a high-conversion furnace for residual oil. Such a furnace is desirable from the viewpoint of economics and operability. The proposed tubular fouling model as shown in Figure 6 well represents the complex phenomena of tubular fouling of a residue conversion furnace by modelling a sedimentation of coke precursor and its reaction into coking material in and out the boundary film. 

Why should you use long-handled tongs and insulated gloves when transferring materials in and out of a muffle furnace ... 

Rg. 6.5. Sectional view of a rotary hearth furnace (such as fig. 1.8) with enhanced heating. This also could be a car-hearth batch furnace or in-and-out batch-box furnace. In many cases, the higher velocity burners would be smaller (relative to the main burners above) than they appear in this drawing. In other than rotary hearth furnaces, the high-velocity burners should fire between piers and opposite the main burners—to further enhance circulation. 

There is little heat loss from rolls conveyors that stay within the hot furnace chamber all of the time. For conveyors that move in and out of the furnace, calculate loss/hr = (weight/hr) (specific heat) (Tn,ax. - ). 

Gloves providing thermal insulation must be used at all times when transferring objects in and out of an oven or furnace. 

Naphtha desulfurization is conducted in the vapor phase as described for natural gas. Raw naphtha is preheated and vaporized in a separate furnace. If the sulfur content of the naphtha is very high, after Co—Mo hydrotreating, the naphtha is condensed, H2S is stripped out, and the residual H2S is adsorbed on ZnO. The primary reformer operates at conditions similar to those used with natural gas feed. The nickel catalyst, however, requires a promoter such as potassium in order to avoid carbon deposition at the practical levels of steam-to-carbon ratios of 3.5—5.0. Deposition of carbon from hydrocarbons cracking on the particles of the catalyst reduces the activity of the catalyst for the reforming and results in local uneven heating of the reformer tubes because the firing heat is not removed by the reforming reaction. 

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