Travelling ovens

While there are small bakers who are using old ovens that consist merely of a heated box most modern ovens fall into one of three classes They are either deck ovens, rack ovens or travelling ovens. Travelling ovens are also known as tunnel ovens. 

Simplified workings of a tunnel or travelling oven Figure 10 Simplified scheme of a travelling oven... 

Figure 4.3 Schematic diagram of a thermal sweeper system located between two columns in the gas cliromatograph Cl, C2 and C3 are column connections, with C2 being small enough to allow the slotted heater S to pass over the connection. The accumulator column A retards the travel of solutes tlnough this section until the sweeper expels them out to the uncoated column (called a pigtail (P)), wliich then delivers them as a naixow band to the second column. The modulation drive, M, is external to the GC oven.

The coating material (about 75ml per l(X)ml of column packing) is applied as a solution in a suitable solvent such as methylene chloride, acetone, methanol or pentane, which is then allowed to evaporate in air, over a steam-bath, or in a vacuum oven (provided the adsorbed substance is sufficiently non-volatile). The order in which a mixture of substances travels through such columns depends on their relative solubilities in the materials making up the stationary phases. 

Esveld et a/.81,82 developed a continuous dry media reactor (CDMR) for pilot-scale applications. It consisted of a multi-modal tunnel microwave cavity operating at a frequency of 2.45 GHz with a power range from 0 to 6 kW irradiated on a surface of 0.6 m2. Temperatures of up to 250°C were achieved. A web conveyor travelling at 17 cm min-1 transported the solid-phase reaction mixture to the oven in low, open Pyrex supports closely packed on a polytetrafluoroethylene (PTFE)-coated glass fibre. An open flat bed process was employed to facilitate easy evaporation. 

Vacuum combined with microwaving has been tried for embedding the tissue in paraffin, using Milestone s MicroMED LAVIS-1000 machine (Marani et al., 1996 Bosch et al., 1996). The advantage of this system is that microwaves travel with ease through a vacuum, whereas conventional heating under vacuum is difficult. This machine provides pressure reaching 100 hPa, and the microwave oven attains a maximum power of 1,000 W its cycle time can be adjusted between 0.1 and 0.5 sec. The machine is equipped with an infrared temperature probe which allows temperature control from outside the unit. 

Varied boiler firing configurations are found in hog fuel boiler applications, including dutch oven, fuel cell, spreader stoker with traveling or vibrating grates, and cyclone stoker types. As stated previously, the spreader stoker is the most widely used of these configurations. Spreader/stoker boilers in the pulp and paper industry often have an air swept spout added to the front of the boiler to feed bark down on top of the coal.14 Wood is puffed at one-... 

Coke is also produced from coal in the by-product ovens in which the coal charge is heated on both sides so that heat travels toward the center and thus produces shorter and more solid pieces of coke than are made in the beehive oven. Air is excluded so that no burning takes place within the oven, the heat being supplied completely from the flues on the sides. About 40 percent of the oven gas, after being stripped of its by-products, is returned and burned for the underfiring of the battery of ovens, and some is used for fuel gas locally. 

Gas chromatography is a very sensitive technique requiring only very small amounts of sample (lO g). A solution of about 1% is sufficient and a few microlitres of this is injected into a heated injector block. A stream of carrier gas, usually helium, passes through the injector and sweeps the vapours produced onto the column, which is contained in an oven. The temperature of the oven can be accurately controlled and can either be kept constant or increased at a specified rate. Separation of the components in gc is not based on the principle of adsorption, as it is in liquid chromatography, but on partition. A gc column is rather like an extremely effective distillation column with the relative volatility of the components being the main factor which determines how quickly they travel through the column. 

As mentioned before, after the binder (including the silane) is sprayed onto the fibers, the wool travels through a collection chamber toward the curing oven. Silane diffuses from the resin toward the resin/fiber interface [5]. The best result is obtained when all the silane has the time and... 

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