Low feeding

In this case, FjSo/V Iqp axX- This is such a low feed rate that insufficient nutrients are available to produce protein at a productivity corresponding to qp,nax even in the absence of growth. This regime, which corresponds to F So/V 0.06 g L h is not preferred for protein production. 

In terms of the carbon source, glucose is a catabolite repressor, but many oligomers and polymers of glucose induce enzyme production. Lactose, cellobiose, and sophorose are all dimeric sugars that induce cellulase production. Cellulose is also an inducer. A list of the performance of several carbon sources is found in Table 5 [37]. 

The cellulase productivity varies greatly among strains. Allen and Andreotti 

Trichoderma reesei strain MCG80 in continuous culture with dilution rate of 0.044 h 

The oxygen dehvery rate into the system is given by Eq. (20)  

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In general, soHds-retaining batch and batch automatic machines are limited to low feed concentrations to minimize the time required to unload the soHds. Continuous disk centrifuges can have higher feed concentration. The limit is the underflow concentration. Conveyor discharge centrifuges can handle high feed concentration and are limited only by the volume of soHds displacement, or torque capacity. 

The pressure to be used for reverse osmosis depends on the salinity of the feedwater, the type of membrane, and the desired product purity. It ranges from about 1.5 MPa for low feed concentrations or high flux membranes, through 2.5—4 MPa for brackish waters, and to 6—8.4 MPa for seawater desalination. In desalination of brackish or sea water, typical product water fluxes through spiral-wound membranes are about 600—800 kg/m /d at a recovery ratio RR of 15% and an average salt rejection of 99.5%, where... 

The Stretford Process sweetens and also produces sulfur. It is good for low feed gas concentrations of H2S. Economically, the Stretford Process is comparable to an amine plant plus a Claus sulfur recovery plant. Usually, the amine/Claus combination is favored over Stretford for large plants. Stretford can selectively remove H2S in the presence of high CO2 concentrations. This is the process used in the coal gasification example in the Introduction. 

Solution The sparger (feedpipe) w as turned so that the holes w ere on top rather than the bottom. This ensured that the sparger remained full of liquid even at low feed rates. A deflector w as installed above the orifices to keep feed from impinging on the tray above. This solution w as... 

Volumetric or gravimetric feeders may be used, but volumetric feeders are usually selected only for installations where comparatively low feed rates are required. Dilution does not appear to be important, therefore, control of the amount of water used in the feeding operation is not considered necessary. Inexpensive hydraulic jet agitation may be furnished in the wetting chamber of the feeder as an alternative to mechanical agitation. The jets should be sized for the available water supply pressure to obtain proper mixing. 

Since cracking stocks generally do not have to meet the color specifications that lube distillates do, higher flash zone temperatures (up to 8(X)°F) can be tolerated. Fuel units are normally designed to distill material boiling up to 1100°F (at atmospheric pressure) from the feed, and some units have distilled beyond 12(X)°F at low feed rates. 

An alarm shower can occur when high pressure in the reactor trips the feed by closing a valve and turning off the feed pump. In addition to the high pressure trip alarm, the operator is frequently showered with low feed flow, low-low feed flow, and feed pump off alarms. 

Equations (20-66) and (20-67) present single-pass formulas relating retentate solute concentration, retentate crossflow, permeate flow, and membrane area. For relevant low-feed-concentration applications, polarization is minimal and the flux is mainly a function of pressure. Spiral or hollow fiber modules with low feed channel and permeate pressure drops are preferred. 

Pennline et al.32 used bifunctional Co/ThO/ZSM-5 catalysts at 280°C, 21 bar, H2/CO = 1 in the FTS. XRD of the used catalyst indicated that cobalt carbide is present. They found that the relative amount of the carbide species is larger on the used catalyst operated at 280°C than on the used catalyst operated at 320°C. They argued that this is because cobalt carbide begins to decompose around 300°C. Since this catalyst lacked high water gas shift activity, and a low feed gas ratio of... 

In summaiy, the DDO DGP is effective for low feed concentration, dilute systems which would experience high growth and high encrustation rates in finite size MSMPR ciystallizers. 

Ion exchange membranes are not completely semipermeable some leakage of co-ions of the same charge as the membrane can occur. This effect is generally negligible at low feed solution concentrations, but can be serious with concentrated solutions, such as the seawater treated in Japan. 

Figure 6.65 gives results for feed composition disturbances. At 0.1 h, the chlorine concentration in the feed is increased from 10 to 12.5 mol%, and at 1.5 h it is decreased to 7.5 mol%. The maximum deviation in T(6) temperature is about 2 K for the very large drop in feed composition. The temperature loop is somewhat oscillatory for the low feed composition and low coolant flow conditions, so some controller retuning would be advisable. 

Compared to Fig. 5.9 the line of reactive azeotropy is now shifted to higher concentrations for the cases in Fig. 5.11(b) and (c). Consequently, for a sufficiently low feed concentration, total conversion with pure products B and C is possible in all three cases. Theoretical limitations only occur for high feed concentration. In many practical applications the theoretical limitation illustrated in Fig. 5.11b, c is beyond the solubility limit of the reactants, and has then no practical significance. 

It is evident that the operation in terms of product amount, reflux ratio, recovery, etc. of case 1 of Table 11.3 is very close to the operation of case 1 operation of Table 11.2. Also note that the energy consumption for CBD operation presented in Table 11.3 over a time period tp is same as that for corresponding SPSS operation over the same time period, since the vapour boilup rate in all cases used is 5 kmol/hr. Note that the results of case 2 of Table 11.3 are not close to those of case 4 of Table 11.2. The results (Table 11.2 and Table 11.3) clearly show that if the operation is restricted to one single reflux ratio or one single pass operation, it is possible to replace the CBD operation by continuous column operation using a very low feed flow rate. 

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