Feeding the reactor

This is an obviously difficult task, and it is rarely possible to satisfy both requirements reasonably and simultaneously. This difficulty is compounded by the need to use a preconverter to achieve the various conversion levels where the additional incremental increase in conversion can be measured. The alternative way to a preconverter is to feed the reactor various amounts of products in addition to the starting material. This does not ease the analysis difficulties. 

Since this is a batch system, it might be advisable to use direct digital control. Undoubtedly the throughput could be increased over that with the more traditional analog control system. However, the initial costs and maintenance expenses would also increase. To fully instrument the system would also greatly complicate the equipment required, especially for feeding the reactors (this is discussed later). An economic balance should be run to determine whether this is feasible. I feel it would not be warranted, and have chosen to instrument the plant in the traditional way. 

Although there is steady flow of feed, the reactor is in unsteady-state operation during the time t, since the outlet concentration cA (and hence fA) is continuously changing (cA decreasing from cAo, and fA increasing from 0). 

Butadiene is made by the gas phase catalytic deydrogenation of 1-butene. In order to suppress side reactions and to maintain the temperature level, high temperature steam is added to the feed. The reactor pressure is 2 atm and the feed consists of 12 mol of steam per mol of butene. The equilibrium constant as a function of temperature is K = exp(14.3417 - 13997/T)... 

This bioreactor mode refers to a tank fermenter operated semi-continuously. The rate of the feed flow, F0, may be variable, and there is no outlet flow rate from the fermentor. As a consequence of feeding the reactor volume will change with respect to time. 

The vapor fed to the reactor can also come from a vaporizer which is fed from a surge tank. To conserve energy, it is desirable to feed the reactor with vapor directly from the column instead of from the vaporimr. The only time that the vaporizer should be used is when there is not enough vapor produced by the column. 

The tests were performed in a modified circulating ARCO pilot unit at Chalmers [18,19] with a North Sea atmospheric residue as feed. The reactor temperature was 500°C and the regenerator temperature was 700°C. Each of the catalyst tests were... 

We have seen that this model of the bubbling bed is essentially the same as a stirred tank when the two sources of the feed are recognized. These are the fraction (1 - /3) that comes with the gas feed at the bottom of the bed and the fraction /3 in the bubbles which feeds the reactor at all levels and from a diminishing concentration difference. The latter, when referred to the inlet difference c0 - cp, delivers a fraction 1 - exp(- Tr). Thus the total feed minus outlet is (1 - j8) + >3(1 - exp(- Tr)) (c0 — cp) = 1 - /3 exp(-7r) (c0 — cp) and this is what is equated to the reaction rate, (kH0IU)cp. 

Frontal polymerization carried out as described above can be turned into a continuous process. In order to do this, it is necessary to move the newly formed polymer and the reactive mixture in the direction opposite to the direction of spreading of a thermal front at a velocity equal to the velocity of the front development to feed the reactor with a fresh reactive mass.254 Control of the process, choice of process parameters and proper design of the equipment require solving the system of equations modelling the main physical and chemical processes characteristic of frontal reactions. 

Initial temperature (T0) Before starting the feed, the reactor has to be heated up to its initial temperature. If only the heat carrier s temperature can be actively... 

Figure 3.93 shows the results. The ethylene feed increases, and the ratio increases the benzene feed. The reactor temperature climbs to about 431.6 K in 0.08 h from its desired value of 430 K. The temperature controller decreases the cooling water temperature to about 395 K from its initial value of 400 K to handle the increase in throughput. 

To compare the performance of the reactor and evaluate the effect of CSL incorporation into the feed, the reactor was fed with CSL medium. Fermentation conditions and the dilution rate were kept constant as in Table 1 for the duration of this experiment. The reactor produced 6.29 g/L of total ABE, of which acetone, butanol, and ethanol were 2.00, 4.16, and 0.13 g/L, respectively (Table 1). This resulted in a productivity of 2.01 g/(L h) and a sugar utilization of 30.5% of that available in the feed (67.5 g/L). Compared to the control, the productivity was reduced by 10%. However, it is anticipated that it would be economical to use CSL compared with the P2 medium. This demonstrated that P2 medium can be replaced by economically available CSL. It is suggested, however, that the CSL... 

In contrast, fed-batch type involves feeding the reactor with fresh nutrients or carbohydrates or both during fermentation when low glucose concentrations (10-50 mg/L) are required to maintain the productivity of microorganism. 

Production of cumene from benzene and propylene using a phosphoric acid on quartz catalyst (Fig. 19-22c). There are four reactor beds with interbed cooling with cold feed. The reactor operates at 260°C. 

When the same thioalkoxylates were combined with t-butyl hydroxyperoxide initiator the maximum incorporation yield of the Transurf was around 40%. Monomodal or multimodal molecular weight distributions were observed, depending upon the structure of the Transurf, the conversion of the monomer and the process used for feeding the reactor [9]. 

Two separate types of experiments were undertaken. In one case Kr-85 was metered from a pressurized container into the natural gas feed line into the reactor and in the second case, separately from the first, the Kr-85 was metered into the heated feedstock oil line feeding the reactor. In each case the reactor was in steady-state operation producing standard HAF or Standard ISAF as described above. 

Figure 5 gives the flow scheme of a feed oil system. A high pressure plunger pump feeds the reactor with oil at a pressure of about 75 bar. The mass-flow of feed oil is measured by three Coriolis-Flowmeters. The second pump is out of line. The feed oil flow is adjusted by pump speed which is variable in a range of 25 to 110 rpm. Two resonators are used for pulsation damping. 

The larger reactor operates under a steady state, continuous flow conditions and was made of two 1 m cylindrical reactors of annular shape in order to use conventional Germicidal lamps (Figure 14). The system of tanks shown in the flow sheet was used to (i) feed the reactor with a constant flow rate and (ii) wash the system after each experimental run. The actual operating length (Zi) of each lamp (1.2 m long) was Im. Operation could be made with just one reactor or the two in series. 

The operational thermal stability of enzymes can be easily evaluated in experiments carried out in a CSMR fed with a saturating substrate concentration, while varying the temperature but maintaining all the other parameters constant. Each enzyme of the cascade system was tested by feeding the CSMR with the appropriate substrate. The kinetic characterization of amidase-catalyzed reactions in runs fed with a nitrile was hampered by the fact that the intracellular enzyme works in cascade with nitrile hydratase. The concentration of amide, produced in situ in the first step, varied with the time and reaction conditions and did not assure the differential conditions needed for an accurate analysis, the amide being completely converted by amidase in some runs. Hence, amidase activity was characterized independently by feeding the reactor with amide as the substrate [35]. 

This was performed for each enzyme independently, feeding the reactor with the appropriate substrate (nitrile for the cascade reaction, amide for the sole amidase). The activation energies of both catalysed reactions were evaluated together with those of the inactivation process that inevitably takes place even under the most suitable operational conditions. In the nitrile hydratase/amidase cascade system nitrile hydratase is the more labile enzyme that imposes process temperature choice. These findings make accessible the complete kinetic expression of the dependence from temperature of reaction rate, allowing accurate prediction on reactor performances for process scale-up. 

Changing the height of the bed by changing the rate of feeding the reactor with biomass is normally a very slow process as illustrated clearly by Figure 6 where there is hardly any change afrer an hour, even though the load has been reduced by 75 %, After another 6 hoius in operation the bed has only increased by about 12 cm which corresponds to an accumulation of char of about 1.9 kg. 

About 60—90 minutes after the start of the feeding, the reactor conditions were stabilized. 150 minutes after the start of the feeding, the steam and air supply was stopped and the reactor content was cooled to ambient temperature a nitrogen flow. 

The next example illustrates the use of Excel to solve mass balances for a process consisting of a feed stream, a mixer in which the feed stream is mixed with the recycle stream, and a reactor, followed by a separator where the product is removed and the reactants are recycled. In later examples and problems, there will be inerts, purge streams, and so on, but this problem uses a stoichiometric feed. The reactor is limited by chemical equilibrium considerations, which complicates the solution. 

---