Ovens, drying

In most laboratories, drying ovens maintained at about 50° are available for the final drying of glass apparatus of all kinds. 

After the resin is appHed to the paper, the wet treated web enters a drying oven where most of the solvent is evaporated off. Modem treaters, such as that shown in Figure 1, have air flotation ovens so that the web is never touched by hot conveyor bars that may cause streaks noticeable in the final product. 

Phenohc resins are generally used in alcohohc solution, whereas melamine resins are best handled in water or water—alcohol mixtures. The paper or cloth web is passed through a dip tank containing resin solution, adjusted for pick-up on squeeze rohs, and then passed through a heated drying oven. 

The paper-impregnation drying oven exhausts contain high concentrations (10—20% LEL) of alcohols and some resin monomer. Vinyl resins and melamine resins, which sometimes also contain organic phosphate fire retardants, may be used for air filters. The organic phosphates could shorten catalyst life depending on the mechanism of reduction of catalyst activity. Mild acid leaching removes iron and phosphoms from partially deactivated catalyst and has restored activity in at least one known case. 

Proportional Slow to moderate Small Moderate Pressure, temperature, and level where offset is not objectionable. Kettle reboiler level, drying-oven temperature, pressure-reducing stations... 

Figure 23.19. Impregnation plant fitted with vertieal drying oven. (After Brown )...

A drying oven whieh is eonstrueted of firebriek walls is heated by an eleetrieally operated gas burner as shown in Figure 2.22. The system variables and eonstants are... 

The design proeedure employed was to maintain R as unity sealar, and systematieally vary the diagonal elements of Q to aehieve the performanee speeifieation. This was to maintain a dry elay moisture eontent of 6%, 1%, as the elay feed-rate varied from 6 to 10 tonnes/hour. Also the drying oven temperature should not vary more than 3°C from the set point of 50 °C. At eaeh design setting, the elay feed-rate was varied aeeording to... 

Linear Quadratic Gaussian (LQG) Design %Case Study Example 9.3 Clay Drying Oven %OptimalController... 

Drying oven An oven or stove used for the drying of a product. 

Kanal-jauche, /. (liquid) sewage, -ofen, m. tunnel kiln, -rohr, n. — Kanalisationsrohr. -strahl, m. canal ray, -trockner, m. tunnel drying oven, -wasser, n. sewage. 

The residue was dissolved in 50 ml of water and the solution was made alkaline with sodium hydroxide. The precipitate formed was filtered, washed and dried in a drying oven at 60°C. 6 g of N-(diethylaminoethyl)-2-methoxy-5-methylsu fonylbenzamide (melting point 124°C to 125°C) was produced. 

Electric ovens. The most convenient type is an electrically heated, thermostatically controlled drying oven having a temperature range from room temperature to about 250-300 °C the temperature can be controlled to within 1 -2 °C. They are used principally for drying precipitates or solids at comparatively low controlled temperatures, and have virtually superseded the steam oven. 

While still slightly warm from the drying oven, the photolysis vessel with a water-jacketed quartz immersion well (Note 1) (section A of Figure 2) is charged with 500 ml. of anhydrous tetrahydrofuran (Note 2) and 10 ml. (8.05 g., 0.122 mole) of cyclopentadiene (Note 3). The solution is cooled in an ice bath and purged with dry nitrogen for 2 minutes. Then the vessel is sealed, the lamp inserted, and the solution irradiated at 0° for 30 minutes. During this period, sections B and C... 

Detection and result The dried chromatogram was heated in the drying oven at 180 °C for 20 min. After cooling to room temperature it was dipped twice for 1 s into a solution of Triton X-100 — chloroform (l-t-4) which stabilized the fluorescence and increased its intensity by a factor of 2.5. Between the two dipping steps the chromatogram was air-dried in the dark for 30 min until the chloroform had completely evaporated. 

Detection and result The chromatogram was briefly dried in a stream of cold air then heated for 10 to 30 min at 260 °C in a drying oven. After cooling to room temperature (ca. 15 min) it was dipped in a solution of liquid paraffin — /i-hexane (1 + 2) for 3 s. This stabilized the fluorescence and intensified it by a factor of about 2. 

In a cosmetic laboratory, a recirculating system would have been adequate except for one very special condition. The noses had to perform their fragrance evaluations in a clean atmosphere. This called for once-through ventilation and included placing drying ovens under a simple hood extending part way down from the ceiling. The result was excellent. 

A drying oven looked hopeless after the fire, at least on the out-... 

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