Continuous cooling

Note 2. Continuous cooling would lead to formation of a solid crust on the bottom of the flask and too low a temperature of the mixture. 

Stmctures that form as a function of temperature and time on cooling for a steel of a given composition are usually represented graphically by continuous-cooling and isothermal-transformation diagrams. Another constituent that sometimes forms at temperatures below that for peadite is bainite, which consists of ferrite and Fe C, but in a less well-defined arrangement than peadite. There is not sufficient temperature and time for carbon atoms to diffuse long distances, and a rather poody defined acicular or feathery stmcture results. 

Ko//M //s. When dispersion is requited ia exceedingly viscous materials, the large surface area and small mixing volume of roU mills allow maximum shear to be maintained as the thin layer of material passiag through the nip is continuously cooled. The roUs rotate at different speeds and temperatures to generate the shear force with preferential adhesion to the warmer roU. 

Fig. 18. Continuous-cooling transfomiation diagram for a Type 4340 alloy steel, with superimposed cooling curves illustrating the manner in which transformation behavior during continuous cooling governs final microstmcture (1). Ae is critical temperature at equiUbrium. Ae is lower critical...

M. Atkins, Atlas of Continuous Cooling Transformationsfor Engineering Steels, British Steel Corp., Sheffield, U.K., 1978. 

Unlike for synchrotron radiation, the maximum iatensity of x-rays from an x-ray tube is limited by how fast heat can be removed from the target to prevent its melting. In a conventional sealed tube, the target is stationary, relatively small, and must be continually cooled with water. In a rotating anode tube, the target is larger and is continually rotated so that the heat can be distributed over a larger surface. With such a tube the amount of heat, and hence. 

Fig. 7. Combined sulfur during preparation of cellulose acetate hydrolysis of sulfate and esters (6). Acetylation schedule A, mixer charged with linters and acetic acid B, minor portion of catalyst added C, began cooling to 18°C D, acetic anhydride added and continued cooling to 16°C E, significant portion...

Figure 9.4 Population density distribution of potassium sulphate crystals from continuous cooling crystallization Jones and Mydlarz, 1989)...

Roliani, S. and Paine, K., 1991. Feedback control of CSD in a continuous cooling crystallizer. Canadian Journal of Chemical Engineering, 69, 165. 

Benzene (80 ml) is placed in a suitable pressure vessel (soft drink bottle or hydrogenation bottle) and chilled to 5°. The bottle is weighed, and a gas dispersion tube connected to a cylinder of butadiene is immersed in the benzene. Butadiene is introduced into the flask with continued cooling until a total of 32 g has been transferred. Pulverized maleic anhydride (50 g) is added to the bottle, which is then capped or stoppered with a stopper wired in place. The bottle is allowed to stand at room temperature for 12 hours, then is heated (behind a safety shield) to 100° for 5 hours. The bottle is cooled, then opened, and the contents are transferred to an Erlenmeyer flask. The mixture is heated to boiling, and petroleum ether is added until there is a slight turbidity. After cooling, the product is collected, mp 101-103° (yield 90%). 

To this there is added dropwise with continued cooling and stirring a solution of ethyl chlorocarbonate (0.1 mol). After approximately 10 minutes, the acylating mixture is cooled to about -5°C and then is slowly added to a stirred ice-cold mixture of 6-aminopenicillanic acid 0.1 mol), 3% sodium bicarbonate solution (0.1 mol) and acetone. This reaction mixture is allowed to attain room temperature, stirred for an additional thirty minutes at this temperature and then is extracted with ether. 

There were placed 120 g of Lthree-necked flask equipped with a stirrer thermometer and methanol/dry ice cooling and 1.5 liters of liquid ammonia were allowed to enter at -40°C. Then there were added under continuous cooling 50 g (2.17 mols) of sodium metal in portions of 1 to 2 g during the course of one hour. The end of the reaction was recognized by the continuation of the blue color. After the end of the reaction the excess sodium was destroyed by the addition of ammonium chloride and the ammonia vaporized at normal pressure. The residue was taken up in 500 ml of water and concentrated in a vacuum to 200 ml in order to remove residual ammonia, and again treated with 300 ml of water. The entire operations were carried out under a nitrogen atmosphere. 

After the required heat-time cycle is completed, the mold is ready for cooling, which is accomplished with the mold rotating continually. Cooling is usually done by air from a high-velocity fan and/or by a fine water spray over the mold. After cooling, the final step is to remove the solid hallow product and reload the mold with plastic. 

In 8CB, continued cooling into the smectic phase reveals the appearance of a broad ultra-low-frequency feature centred at around 10 cm where no other modes are seen. This is shown in Fig. 15. This feature appears to be unique to the smectic phase and has been tentatively attributed to intermolecular dipolar coupling across smectic layers [79]. In principle this should be a generic feature of smectics but it will be necessary to explore this issue through extensive computer simulations using realistic, shape-dependent potentials for... 

Now a system of valves is used which effectively transposes the positions of Active beds 1 and 2 and Inert beds 1 and 2. The transposition also results in each bed experiencing a reversal of flow direction. The state of the whole system is now as at the beginning and the whole process can be repeated indefinitely to achieve continuous cooling. 

In a 2-1. four-necked flask (or a three-necked flask with a Y-tube connector) equipped with a stirrer, a reflux condenser, a dropping funnel, and a thermometer extending nearly, to the bottom of the flask is placed 550 ml. (595 g., 5.83 moles) of acetic anhydride which is cooled to 0° with an ice-salt bath. Then 180 ml. (300 g., 2.09 moles) of a 70% solution of perchloric acid is added with stirring at a rate such that the temperature does not rise above 8° (Note 1). This step takes about 3 hours. The mixture is continually cooled and stirred, and 240 ml. (204 g., 2.09 moles) of mesityl oxide is then added slowly. The slow addition of 370 ml. (400 g., 3.92 moles) of acetic anhydride follows. The ice bath is then replaced by a water bath the temperature of the reaction mixture will usually rise to 50-70° because of the heat liberated by the exothermic reaction, and the reaction mixture will turn dark. The reaction mixture is heated on a steam bath for 15 minutes to complete the reaction, and the mixture is then allowed to cool and stand at room temperature for 2 hours. The crystals,... 

Continuous cellulosic fibers, 20 557 Continuous compression filters, 77 379-381 Continuous conveyors, 9 119 Continuous cooling, in austenite transformation, 23 282-283 Continuous-cooling transformation (CCT) diagrams, 77 16 23 280 Continuous copper-drossing process, 74 745-747... 

Run the reactor continuously with continuous feed to and from the reactor. Observe the effect of varying space-time on the reaction yield and on SPTYC. Set TIMEON = 0, and to give continuous cooling set FCON to the desired cooling flow rate. 

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