Overflow vessel

Fig. 19. Vertical cross-section of the wiper-blade reactor. A, Sealing arrangement B, gas phase C, rotor D, sealing E, bearing F, excess gas flow G, gas collected from the liquid exit H, overflow vessel I, liquid exit J, rotor blades K, gas feed L, adjustable shaft M, baffles N, reactor shell O, cooling jacket P, cooling water feed and exit Q, sampling port R, grooves S, liquid phase T, gas-liquid interface U, top and bottom plates and V, liquid feed. (After Manor and Schmitz, 1984 also from Chaudhari et al., 1986, by courtesy of Marcel Dekker, Inc.).

Competition in a modified gradostat was considered in Smith and Tang [STa], There the rate E between the vessels (called the communication rate) was allowed to differ from the rate D (the dilution rate) from the feed bottle and to the overflow vessel. This, of course, still maintains the assumption that the volume in each vessel is constant. It was shown that the outcome of competition can be sensitive to the ratio E/D in the following sense As E/D is increased, first one competitor wins the competition, then coexistence occurs, and finally the second competitor wins. The analysis in the case E D k entirely similar to the case E = D discussed in this chapter. In [STa], a number of operating diagrams were determined numerically. For fixed population parameters fly, these oper-... 

Figure 1.1. The standard n-vessel gradostat. The left vessel labeled is a reservoir containing nutrient at concentration C is an overflow vessel, and D denotes the dilution rate. All vessels have the same volume.

Suppose that our gradostat consists of n vessels. Let Ejj be the constant (volumetric) flow rate from vessel j to i (i j), with the convention that Ejj = 0 for i = l,..., . Let Vj be the volume of fluid in the / th vessel, Dj the flow rate from a reservoir to vessel / (D, = 0 if no such reservoir exists), the concentration of substrate in the reservoir feeding vessel i (S/° = 0 if D, = 0), and Cj the flow rate from vessel i to an overflow vessel (C, = 0 if no such vessel exists). The notation diag(/3,) is used to denote a diagonal matrix whose diagonal elements are given by / , E is the matrix of flow rates Ejj. 

Figure 1.2. A three-vessel gradostat that does not satisfy the irreducibility hypothesis. The two vessels on the left receive no input from the vessel on the right. Arrows pointing down from the first and last vessel represent flow to overflow vessels not depicted. Notation is the same as in Figure 1.1.

It is extremely important that vessels are well protected from an overflow condition. An overflowing vessel may have severe safety consequences, impacting nearby employees, the environment and the surrounding community. Some vessels require low-level protection to operate safely. Ideally, each vessel should have a visual indication for the operator, an alarm point and a transmitted level indicator [8]. 

The two procedures primarily used for continuous nitration are the semicontinuous method developed by Bofors-Nobel Chematur of Sweden and the continuous method of Hercules Powder Co. in the United States. The latter process, which uses a multiple cascade system for nitration and a continuous wringing operation, increases safety, reduces the personnel involved, provides a substantial reduction in pollutants, and increases the uniformity of the product. The cellulose is automatically and continuously fed into the first of a series of pots at a controlled rate. It falls into the slurry of acid and nitrocellulose and is submerged immediately by a turbine-type agitator. The acid is deflvered to the pots from tanks at a rate controlled by appropriate instmmentation based on the desired acid to cellulose ratio. The slurry flows successively by gravity from the first to the last of the nitration vessels through under- and overflow weirs to ensure adequate retention time during nitration. The overflow from the last pot is fully nitrated cellulose. 

Clarifiers. The largest user of clarifiers is probably the water-treatment industry. The conventional one-pass clarifier uses horizontal flow in circular or rectangular vessels (Eig. 2) with feed at one end and overflow at the other. The feed is preflocculated in an orthokinetic (paddle) flocculator... 

The vessel design features a Chinese hat-like conical core stopper above the underflow sump, which is there to prevent the vortex from reaching the latter and reentraining the settled soHds. The core stopper is also beheved to stabilize and locate the vortex flow in the vessel. Overflow from the vessel is through a wide cylindrical insert through the Hd, similar to a vortex finder in a hydrocyclone (16), and an optional provision can be made for collecting any floatables in a float trap. 

Butyl slurry at 25—35 wt % mbber continuously overflows from the reactor through a transferline to an agitated flash dmm operating at 140—160 kPa (1.4—1.6 atm) and 55—70°C. Steam and hot water are mixed with the slurry in a nozzle as it enters the dmm to vaporize methyl chloride and unreacted monomers that pass overhead to a recovery system. The vapor stream is compressed, dried over alumina, and fractionated to yield a recycle stream of methyl chloride and isobutylene. Pure methyl chloride is recovered for the coinitiator (AlCl ) preparation. In the flash dmm, the polymer agglomerates as a coarse cmmb in water. Metal stearate, eg, aluminum, calcium, or zinc stearate, is added to control the cmmb size. Other additives, such as antioxidants, can also be introduced at this point. The polymer cmmb at 8—12 wt % in water flows from the flash dmm to a stripping vessel operated under high vacuum to... 

Continuous stirred tank reactors (CSTRs) are frequently employed multiply and in series. Reactants are continuously fed to the first vessel they overflow through the others in succession, while being thor-... 

The volume of solution will vary depending on the exact volume of the apparatus, the temperature, and the miscibility of gaseous reactant in the solvent. The solution should completely surround the lamp, but should not overflow the vessel. The submitters used a volume of 1100 mL and the checkers used 200 mL. 

Consider a thin layer solid bowl centrifuge as shown in Figure 4.20. In this device, particles are flung to the wall of the vessel by centrifugal force while liquor either remains stationary in batch operation or overflows a weir in continuous operation. Separation of solid from liquid will be a function of several quantities including particle and fluid densities, particle size, flowrate of slurry, and machine size and design (speed, diameter, separation distance, etc.). A relationship between them can be derived using the transport equations that were derived in Chapter 3, as follows. 

One source of an oil spill could be the filling of a vessel that has an outlet to atmosphere until it overflows. Whenever inflow exceeds outflow, the tank can eventually overflow. Another source is a rupture or sudden inability of a piece of equipment to contain pressure. Events leading to rupture are listed in Figure 14-2. Note that some of these events can be anticipated by sensing changes in process conditions that lead to the rupture. Other events cannot be anticipated from process conditions. 

Similarly, if the vent is designed to pass liquid, it should be fitted near the edge of the roof, and its top should not be more than 8 in. above the tops of the walls. Vessels have been overpressured because their vent pipes were too long (see Figure 5-2b). Tanks in which hydrogen may be evolved should be fitted with a vent at the highest point as well as an overflow (see Section 16.2). 

Oherlauf-gefSss, n. overfiow vessel, -pipette, /. overfiow pipet(te). -rohr, n. overfiow tube (or pipe), -stutzen, m. overflow tube (or pipe). 

The continuous phase moves through the vessel on a uniform flow equal to the overflow rate. To identify which is the continuous phase (from [65] by [32]) ... 

Fresh medium is pumped into the culture vessel. The liquid level is controlled as the overflow is drained to a product reservoir. 

Forms azeotropic mixts with butyl ale, acetic acid, heptane, toluene, nitroethane, perchioro-ethylene, w, etc. Prepn is by reacting propyl ale with coned nitric acid (d 1.41g/cc) dissolved in ethylacetate at 20°, followed by distn of the product. NPN can also be preod bv reacting a continuous stream of propyl ale below the surface of stirred mixed acid (20% nitric acid, 68% sulfuric acid and 12% w by wt) in a cooled (0—5°) open stainless steel vessel. Addnl mixed acid is also simultaneously introduced at about a third of the depth of the liq. An overflow pipe maintains a constant reactant level and the effluent prod is sepd, washed with 10% aq Na carbonate soln and dried by passage thru a Filtrol packed tower. Contact time of reactants can vary from 0.6 to 15 mins using about 50% isopropanol at 0° to yield 66.5% NPN (Ref 3b)... 

Equations (1-1) and (1-2) are true in the general case and can be used to study several modes of reactor operation (e.g. batch, semi-batch, continuous, start-up procedures, etc.). If the assumption is made that the reactor is a vessel continuously operating full, i.e. overflow CSTR, then the right hand side (RHS) of equation (1-2) is zero and (1-1) is considerably simplified to yield ... 

Solid particles can be removed from a dilute suspension by passing the suspension through a vessel that is large enough that the vertical component of the fluid velocity is lower than the terminal velocity of the particles and the residence time is sufficiently long to allow the particles to settle out. A typical gravity settler is illustrated in Fig. 12-2. If the upward velocity of the liquid (Q/A) is less than the terminal velocity of the particles (Ft), the particles will settle to the bottom otherwise, they will be carried out with the overflow. If Stokes flow is applicable (i.e., NRe < 1), the diameter of the smallest particle that will settle out is... 

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