Flow rates, acid temperature control

Also PT analysis of 3-MH and 3-MHA is performed by adjusting the pH solution to 7.0 to reduce the stripping of the free fatty acids and to avoid 3-MHA hydrolysis. Linearity and sensitivity have been investigated using the same pre-treated wine employed for controlling the other two quoted methods and the same calibration solutions. The optimized experimental conditions of sample temperature (St), flow rate (Fr), purge flow time (Pft), trap temperature (Tt) and desorption time (Dt) are reported in Table 5.15 and the sensitivity results in Table 5.16 (Fedrizzi et al., 2007c). 

The primary process variables affecting the economics of sulfuric acid alkylation are the reaction temperature, isobutane recycle rate, reactor space velocity, and spent acid strength. To control fresh acid makeup, spent acid could be monitored by continuously measuring its density, the flow rate, and its temperature. This can reduce the acid usage in alkyla-tion units. 

The experiments were performed in a CINC V-02 separator also known as the CS-50 (15). Two Verder VL 500 control peristaltic tube pumps equipped with a double pump head (3,2 x 1,6 x 8R) were used to feed the CCS. In case of the enzymatic reaction, the low mix bottom plate was applied. To operate the reactor at a desired temperature, it was equipped with a jacket which was coimected to a temperature controlled water bath with an accuracy of 0.01°C. The CCS was fed with pure heptane and pure water, both with a flow rate of 6 mL/min. Subsequently, the centrifuge was started (40 Hz, which corresponds to 2400 rpm) and the set-up was allowed to equilibrate for a period of 1 h. At this point, the heptane feed stream was replaced by the organic feed stream (oleic acid (0.6M) and 1-bntanol (0.9M) in heptane). After equilibration for 10 minutes, the reaction in the CCS was started by replacing the water stream with the aqueous feed stream (0.1 M phosphate buffer pH 5.6 containing 1 g/1 of the lipase form Rhizomucor miehei). Samples were taken at regular intervals and analysed by GC. 

Figure 8 Separation of isomeric acids (maleic and fumaric acid) by controlled surface porosity anion exchange chromatography. Column Sulfonated fluoropolymer coated onto a 50-p glass bead. Average pore size about 1000 A. Flow rate 2.73 ml/min. Eluant 10 mM HN03. Temperature 60°C. Detection absorbance. (Reproduced from Kirkland, J. J., J. Chromatogr. Sci., 7,361,1969. By permission of Preston Publications, A Division of Preston Industries, Inc.)...

In order to study further the favorable aspects of in situ acid catalyzed hydrolysis, experiments were performed at different temperatures so as to evaluate the dependence of rate on temperature. Solutions of aldlcarb were passed through a jacketed column around which water at 30, 40, or 50°C was circulating. The ion exchange bed (5 cm x 0.70 cm) contained 2.0 g of Bio-Rad AG MP-50 strong acid cation exchange resin (iT ", 100-200 mesh), and the solution flow rate was approximately 1.0 ml/mln. The percent of Initial aldlcarb remaining at the end of the column for each temperature decreased from 76% at 30 C to 56% at 40 C and 35% at 50°C. Future temperature studies will be done in order to evaluate the practicality of temperature control in a detoxification filter unit. 

Kinetic Studies. Peracetic Ac id Decomposition. Studies with manganese catalyst were conducted by the capacity-flow method described by Caldin (9). The reactor consisted of a glass tube (5 inches long X 2 inches o.d.), a small centrifugal pump (for stirring by circulation), and a coil for temperature control (usually 1°C.) total liquid volume was 550 ml. Standardized peracetic acid solutions in acetic acid (0.1-0.4M) and catalyst solutions also in acetic acid were metered into the reactor with separate positive displacement pumps. Samples were quenched with aqueous potassium iodide. The liberated iodine was titrated with thiosulfate. Peracetic acid decomposition rates were calculated from the feed rate and the difference between peracetic acid concentration in the feed and exit streams. 

U liters (a round bottomed flask) and 185 liters (a 6.5 ft stainless steel rotary digester). Temperatures within the vessels were regulated by partial immersion in controlled (to 100°C) water baths. Aqueous nitric acid was introduced as either a fine stream or spray into the vessels both nitric oxide and oxygen flow rate and pressure drop were independently monitored into the systems. 

The control of the separation section is presented in Figure 10.11. Although the flowsheet seems complex, the control is rather simple. The separation must deliver recycle and product streams with the required purity acetic acid (from C-3), vinyl acetate (from C-5) and water (from C-6). Because the distillate streams are recycled within the separation section, their composition is less important. Therefore, columns C-3, C-5 and C-6 are operated at constant reflux, while boilup rates are used to control some temperatures in the lower sections of the column. For the absorption columns C-l and C-4, the flow rates of the absorbent (acetic acid) are kept constant The concentration of C02 in the recycle stream is controlled by changing the amount of gas sent to the C02 removal unit The additional level, temperature and pressure control loops are standard. 

---