Salt bath reactors

Eqn. (2) was found to accurately represent individual sets of data, giving estimates of kx and k2 having normalised standard errors (ak/ ) less than 10%. The reproducibility of the data was checked by changing the salt baths, the reactor tubes and by repeated packings of the tube. A comparison of U values obtained over two different salt bath reactors and two different tubes, packed independently, is given in Table III. 

PA production received a further innovative impetus from the use of an alternative feedstock. In 1944/45, for the first time, Oronite Chemical Co. Standard Oil CA)) in the USA oxidized o-xylene in a salt-bath reactor to produce PA. The catalyst was a low-porosity carrier (silica quartz or silicon carbide), which was coated with 7 to 8% molten V2O5. The reaction temperatures of 450 to 600 °C were considerably higher than those used in the process. 

Table M. Heterogeneity of the N.lit./hr salt bath reactor temp = model. 400 C Tube inlet rate 1687 butane ...

The niter and fresh caustic soda, required to maintain the fluidity of the salt bath in the reactor chamber, are added gradually. When the color of the saturated salts turns from a dark gray to white, the impurity metals are at their highest state of oxidation, and the lead content of the spent salts is very low. In a modification, the arsenic and tin are selectively removed as sodium arsenate and sodium stannate, followed by the removal of antimony as sodium antimonate. 

Process Description. Reactors used in the vapor-phase synthesis of thiophene and aLkylthiophenes are all multitubular, fixed-bed catalytic reactors operating at atmospheric pressure, or up to 10 kPa and with hot-air circulation on the shell, or salt bath heating, maintaining reaction temperatures in the range of 400—500°C. The feedstocks, in the appropriate molar ratio, are vaporized and passed through the catalyst bed. Condensation gives the cmde product mixture noncondensable vapors are vented to the incinerator. 

In contact with molten salts, the nickel-base alloys behave much more satisfactorily than is the general experience with molten metals. For this reason they are considered as structural materials in atomic reactors using fluoride mixtures as coolants and are used as vessels for heat-treatment salt baths, as thermocouple sheaths and in similar applications. 

Adipic acid, 219.2 g (1.5 mol), and 77.6 g (1.25 mol) of 1,2-ethanediol are weighed into a 500-mL glass reactor equipped with a mechanical stirrer, a nitrogen inlet, and a distillation head connected to a condenser and a receiver fiask. The reactor is placed in a salt bath preheated at 180°C and the temperature is dien raised gradually to 220°C (see note at end of procedure) until the greater part of water has been removed (3 h). The reactor is cooled down to 160°C and vacuum is applied slowly to ca. 0.07 mbar (30 min). Temperature is ramped to 220°C (see note below) at a rate of l°C/min and reaction is continued for an additional 90 min. At the end of reaction, the carboxylic acid endgroup content is close to 1.90 mol/kg. No purification of final polyester is carried out. 

A pulse reactor system similar to that described by Brazdll, et al( ) was used to obtain the kinetic data. The reactor was a stainless-steel U-tube, composed of a l/S" x 6 preheat zone and a 3/8" X 6 reactor zone with a maximum catalyst volume of about 5.0 cm. The reactor was Immersed In a temperature controlled molten salt bath. 

Potassium nitrate in cloth sacks stowed next to baled peat moss became involved in a ship fire and caused rapid flame spread and explosions [1]. Heat transfer salt from a new supplier was added to a pilot plant reactor salt bath. Some 12 h after start of heating to melt the bath contents a muffled explosion occurred, attributed to presence of organic impurities in the new salt [2],... 

To start a run, the reactor was immersed in a preheated salt bath and the temperature and time were recorded by computer for subsequent calculation of the reaction ordinate, to be defined later. Typically, the desired reaction temperature ( 3°C experimental error) was reached within the first ten minutes of heating. 

Other reactors and processes include the hot oil bath, molten salt bath, microwave, and plasma. These processes have been researched on laboratory and some cases pilot plant scale. None have proven commercially successful. 

Water used in the experiments was doubly distilled and passed through an ion exchange unit. The conductivity was approximately 1 x 10"6 S/m. Simulated HLLW consisted of 21 metal nitrates in an aqueous 1.6 M nitric acid solution as shown in Table 1 and was supplied by EBARA Co. (Tokyo, Japan). Concentrations were verified by AA for Na and Cs with 1000 1 dilution and by ICP for the other elements with 100 1 dilution. Total metal ion concentration was 98,393 ppm. The experimental apparatus consisted of nominal 9.2 cm3 batch reactors (O.D. 12.7 mm, I.D. 8.5 mm) constructed of 316 stainless steel with an internal K-type thermocouple for temperature measurement. Heating of each reactor was accomplished with a 50%NaNO2 + 50% KNO 2 salt bath that was stirred to insure uniform temperature. Temperature in the bath did not vary more than 1 K. The reactors were loaded with the simulated HLLW waste at atmospheric conditions according to an approximate calculated pressure. Each reactor was then immersed in the salt bath for 2 min -24 hours. After a predetermined time, the reactor was removed from the bath and quenched in a 293 K water bath. The reactor was opened and the contents were passed through a 0.1 pm nitro-ceflulose filter while diluting with water. Analysis of the liquid was performed with methods in Table 1. Analysis of filtered solids were carried out with X-ray diffraction with a CuK a beam and Ni filter. Reaction time was defined as the time that the sample spent at the desired temperature. Typical cumulative heat-up and cool-down time was on the order of one minute. Results of this work are reported in terms of recoveries as defined by ... 

The pressure and temperature in the reactor were measured by a K-type thermocouple inserted into the reactor and pressure transducer, respectively. The molten salt bath was bubbled with air so to obtain a homogenous temperature inside the bath and effective heat transfer. The temperature in the reactor rose quickly, exceeding 390 C in 40 s. The pressure continued to slowly increase after the temperature reached 400 C, probably due to the gas formation. 

The batch scale rotative reactor was developed and used as a tool to validate the new heat transfer model [4, 6]. The batch reactor consists of a well insulated tank which contains molten salt and is equipped with heating elements in order to be able to heat the salt to the set point temperature. A second well insulated tank can be placed in the salt bath. The feedstock enters the reactor through the feedpipe. The same agitation blades as those found in the industrial reactor are used. The stirring mechanism transports and agitates the feedstock in a circular manner. The center of the reservoir is kept free of feedstock by a scraping mechanism. The diameter of the feedstock tank is 107 cm and the effective heat transfer area is 0.82 m [6]. 

The Beckmann rearrangement in superheated and SCH2O was performed at temperatures of 250-400 °C at fixed densities of 0.35 and 0.50 g/mL. The experiments were conducted using a batch reactor system. The reactor vessel was made from a piece of SUS 316 tubing, providing an internal volume of 10 cm A predetermined amount of reactant solution (cyclohexanone-oxime of 0.44 mmol and water of 0.20 or 0.28 mol) was loaded into the reactor in N2 atmosphere. The reactor vessel was immersed and vigorously shaken in a fluidized molten salt bath. The heating time to raise the reactor temperature from 20 °C to 400 °C was within 30 s and the temperature was controlled within 2°C. After a preselected reaction time of 3 min, the reactor was removed from the bath, and then quenched in a water bath. 

Fig. 2.2-16 Salt-bath tube-bundle reactor for partial oxidation on a heterogeneous catalyst. The heat of reaction is removed by a circulating salt bath, which is cooled by evaporation of condensate.

Benzene vaporizer 2 Multitubular reactor 3 Salt bath cooler 4 Gas scrubber 5 Dehydration column 6 Storage tank 7 Distillation boiler 8 Distillation column... 

Benzene vapor is mixed with air (benzene concentration 1 to 1.4 mol%) and fed over a fixed-bed catalyst contained in a multitubular reactor. The tubes, which are arranged vertically, have a diameter of 20 to 50 mm one reactor contains up to 20,000 tubes. The reaction temperature is kept at 350 to 400 °C by cooling with a salt bath the pressure is 1 to 2 bar. 

Concurrently, developed a durable catalyst for a process operating at low temperature, by which naphthalene could be converted into PA in high yields, initially 73.5% and later rising to 87%. The cylindrical A45Fcatalyst contained 10% vanadium pentoxide, 20 to 30% potassium sulfate and 60 to 70% porous silica. The reaction was carried out in a multitubular reactor at 380 to 390 °C heat was removed by a salt bath. 

A suitable temperature at the walls of the metal reactor can be maintained by means of a molten salt bath containing fused sodium and potassium nitrates and nitrites. The reactor is immersed in the bath and heat is applied... 

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