Vessel with temperature control

Vessels with temperature control are used mainly for precise theoretical measurements, especially when kinetic currents are involved, for methods using a calibration curve, and for the measurements of homogeneous kinetics, with a mercury dropping electrode as an indicator, for the changes of concentrations of polaro-graphically active substances with time. These vessels usually... 

Hydroxyquinoline ( oxine ). The technique adopted in this preparation is based upon the fact that, in general, the reactants glycerol, amine, nitro compound and sulphuric acid can be mixed with temperature control, and then maintained at any convenient temperature below 120° without any appreciable chemical reaction taking place. A pre-mix of the amine, glycerol and sulphuric acid, maintained at a temperature which keeps it fluid (60-90°), is added in portions to a reaction vessel containiug the nitro compound and warmed with stirring to 140-170° at which temperature the Skraup reaction takes place. 

Fig. 1. Addition of the reagent with temperature control and introduction of nitrogen. Fig. 1. Reaction vessel suitable for conversions in liquid ammonia.

States or Australia. In some cases, pot stills, arranged in cascade, are still used. The more sophisticated plants employ one or more carbon steel or cast-iron vessels heated electrically and equipped with temperature controls for both the bulk Hquid and the vessel walls. Contact time is usually 6—10 h. However, modem pitches are vacuum-distilled, producing no secondary quinoline insolubles, to improve the rheological properties. 

Fig. 2.7 Temperature profiles for a 30mL sample of 1-methyl-2-pyrrolidone heated under open-vessel microwave irradiation conditions [19]. Multimode microwave heating at different maximum power levels for 6 min with temperature control using the feedback from a fiber-...

Fig. 5.2 Temperature profile for a 30 ml sample ofwater heated under sealed-vessel conditions. Multimode microwave heating with 100 W maximum power for 8 min with temperature control using the feedback from a f ber-optic probe ramp within 120 s to 70 °C hold for 120 s at 70 °C ramp within 120 s to 100 °C hold for 120 s at 100 °C.

Take 0.1 m potassium phosphate buffer (640 mL) and add resting cell suspension (40 mL, containing 2 g dry cell weight) into a 1.5 L vessel or a fermentor (reactor with temperature control, impeller and addition port to add substrate periodically). 

We have analyzed, both theoretically and experimentally, the reaction chemistry of a variety of metal hydrides and water, and the chemical stability of the organic carriers in contact with metal hydrides and spent hydrides. Since detailed hydrolysis reaction kinetics of the metal hydride/organic carrier slurry is not known, we conducted experiments using a high pressure (13.790 MPa or 2000 psi) and high temperature (232°C) vessel with temperature, pressure, and magnetic stirrer control capabilities (500 cm3 internal volume). Some of the selection criteria for the hydride follow. 

A - solvent reservoir B - high pressure pump C - extraction vessel D - absolute pressure transducer E - electrical heating with temperature control system F - glass collector G - trap H - flow meter. 

All pyrolysis experiments were carried out in the thermo-gravimetric apparatus (TGA) having a pressure capacity of up to 1000 psi. A schematic of the experimental unit is shown in Figure 1. It consists of the DuPont 1090 Thermal Analyzer and the microbalance reactor. The latter was enclosed inside a pressure vessel with a controlled temperature programmer and a computer data storage system. The pressure vessel was custom manufactured by Autoclave Engineers. A similar set-up was used previously by others.( )... 

Figure 2 Experimental set up (1) 316 stainless steel feed preheater tube (1.3 cm i.d. X 50 cm length) (2) block heater containing a 316 stainless steel fixed bed reactor tube (2.5 cm X 46 cm length) (3) catalyst bed (4) Type J (iron/constantan) thermocouple probe (5) Type J (iron/constantan) thermocouple with temperature controller (6) syringe pump (7) condenser (8) receiving flask (9) gas trap (10) gas collection vessel and (11) nitrogen cylinder.

Figure 3.3 Microwave acid digester with temperature controller, safety membrane and vessel with fittings. (Reproduced by kind permission of CEM Corporation)...

A batch reactor generally consists of a closed vessel provided with a means of stirring and with temperature control. It may be held at constant pressure or it can be entirely enclosed at a constant volume. If the R simultaneous... 

Figure 10-16. Lined vessel with temperature and pressure control.

Probe heating is accomplished by means of k chilled-water-jacketed electrical furnace that fits snugly around the pressure vessel. The heating element consists of 50 turns of bifilar (i.e. noninductively) wound constantan wire powered from the spectrometer s temperature controller. Additional capacitance filtering was necessary to remove voltage spikes from the controller s output. Temperatures up to 250 °C could be achieved in this way with temperature control to within +0.1°C. 

For slow reactions with a half life of more than 30 minutes, reaction was carried out in 100 ml stoppered flasks, immersed in a thermostat with temperature controlled to + 0.1 C. Each flask initially contained nitrating acid of known composition. After thermal equilibrium had been established, a measured volume of aromatic substrate, previously dissolved in organic solvent and immersed in the same thermostat, was added to the nitrating mixture. Samples were tciken from the reaction vessel at intervals, diluted with solvent, and the absorbcince of a suitable peak in the U.V. or visible spectra of the nitro products was measured by a Beckmcin double-beam spectrophotometer. 

Either ideal (or close to ideal), with temperature control of the surrounding shield so as to keep at zero the temperature difference between the calorimetric vessel and the shield. 

We equip batch and semi-batch reactors with temperature control that actuates heating and cooling mechanisms per need. In addition to controlling heating and cooling rates, we control reactant addition rate to semi-batch reactors with temperature. We most often achieve fluid level control via weigh cells, either under the feed vessel or under the reactor. We also use metering pumps to control the fluid level in the reactor. Basically, we do not over-burden a batch or semi-batch reactor or process with instrumentation. Because of their simple construction and simple control schemes, batch and semi-batch reactors are relatively inexpensive to obtain and to install. 

Palmisano et al. [103] worked with ultrasound at 60 W power and 19.6 kHz, for 1.5 h, to get a wide range of (het)-3-arylmethyl-4-hydroxycoumarins (134) through a tandem Michael Knoevenagel-reductive reaction (Scheme 34). The efficient ultrasoxmd method promoted the reaction in the absence of organic solvents, with temperature control at 30-40 °C in an open vessel, without the need of an excess of Hantzsch 1,4-dihydropyridine. These compoxmds have biological properties such as anticoagulant, photosensitizing, and antineoplastic. 

A typical bourbon fermentation continues for 72 hours at a fermentation temperature within the 31—35°C range. Many fermentation vessels are equipped with agitation and/or cooling coils that facHitate temperature control. Significant increases in yeast numbers occur during the first 30 hours of fermentation. Over 75% of the carbohydrate is consumed and converted to ethanol. Within 48 hours, 95% or more of the ethanol production is complete. 

Oxychlorination of Ethylene or Dichloroethane. Ethylene or dichloroethane can be chlorinated to a mixture of tetrachoroethylene and trichloroethylene in the presence of oxygen and catalysts. The reaction is carried out in a fluidized-bed reactor at 425°C and 138—207 kPa (20—30 psi). The most common catalysts ate mixtures of potassium and cupric chlorides. Conversion to chlotocatbons ranges from 85—90%, with 10—15% lost as carbon monoxide and carbon dioxide (24). Temperature control is critical. Below 425°C, tetrachloroethane becomes the dominant product, 57.3 wt % of cmde product at 330°C (30). Above 480°C, excessive burning and decomposition reactions occur. Product ratios can be controlled but less readily than in the chlorination process. Reaction vessels must be constmcted of corrosion-resistant alloys. 

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