Perfect stirred tank

CONTINUOUS FLOW ISOTHERMAL PERFECTLY STIRRED TANK REACTOR... 

Setting k = 0, simulate the tracer response (F-curves) for 3 perfectly-stirred tanks in series. 

Modify the program to allow for zero dead space volume and study the effect of fractional by-passing only. Compare the results to that of a perfectly stirred tank. 

Setting k = 0, simulate the response to a pulse of tracer for 3 perfectly-stirred tanks in series. Repeat this for various numbers of tanks and plot E versus dimensionless time for these on an overlay graph. 

First we must derive the equations for the perfectly stirred tanks. In these ideal tanks, it is assumed that the entire contents have the same composition as the outlet stream. Thus the C curve, or the response to a pulse input, can be found quite easily by a material balance. 

For one perfect stirred tank, the formulation used in Section III is used, modified by adding a term for the chemical reaction. 

LCB affects the properties of LDPE, low density polyethylene made by free-radical polymerization see Section 10. The continuous polymerization is carried out in stirred reactors or in tubes several authors (5, 90, 92) have considered the effects of LCB on MWD in perfectly-stirred tank reactors. 

An ideal batch reactor is a perfectly stirred tank of constant volume with no mass transfer from or to the outside. There is a single residence time, which is simply the duration of the reaction. Generally, a batch reactor is operated isothermally and therefore the reaction temperature may be considered as an independent variable. 

Many of these difficulties can be overcome by choosing an appropriate configuration of the photoreactor system. One such a system is the mechanically agitated cylindrical reactor with parabolic reflector. In this type of reactor, the reaction system is isolated from the radiation source (which could also simplify the solution of the well-known problem of wall deposits, generally more severe at the radiation entrance wall). The reactor system uses a cylindrical reactor irradiated from the bottom by a tubular source located at the focal axis of a cylindrical reflector of parabolic cross-section (Fig. 40). Since the cylindrical reactor may be a perfectly stirred tank reactor, this device is especially required. This type of reactor is applicable for both laboratory-and commercial-scale work and can be used in batch, semibatch, or continuous operations. Problems of corrosion and sealing can be easily handled in this system. 

A plot of Equation (14) would resemble Figure 2. There is a maximum value of SD equal to [p/(l+p)]P, which occurs at x = (1+p) log [(1-hp)/p]. As with the perfectly-stirred tank, these can be interpreted as critical values for stability. A few values are listed in Table IV. 

Consider the steady operation of a perfectly-stirred tank reactor (CSTR) of constant volume V, in which only homogeneous reactions occur. Again, the system for the b2dances is chosen as the fluid contents of the reactor. Eq. (3.1-4) then gives... 

A well-stirred reactor containing solid catalysts can be modelled as a perfect stirred tank reactor, that is, concentration is the same everywhere inside the reactor. When such catalysts are very small, the diffusional resistance inside the catalyst can be ignored. The catalyst is slowly... 

In order to describe adequately the hydrodynamics of the experimental fixed bed reactor, it is necessary to take into account the axial dispersion in the mathematical model. The time dependent continuity equation including axial dispersion for a fixed bed reactor is given by a partial differential equation (pde) of the parabolic/hyperbolic class. These types of pde s are difficult to solve numerically, resulting in long cpu times. A way to overcome these difficulties is by describing the fixed bed reactor as a cascade of perfectly stirred tank reactors. The axial dispersion is then accounted for by the number of tanks in series. For a low degree of dispersion (Bo < 50) the number of stirred tanks, N, and the Bodenstein number. Bo, are related as N Bo/2 [8].The fixed bed reactor is now described by a system of ordinary differential equations (ode s). No radial gradients are taken into account and a onedimensional model is applied. Mass balances are developed for both the gas phase and the adsorbed phase. The reactor is considered to be isothermal. 

If one attempts - despite the mentioned qualitative deviations - a guess of the number of effective compartments on Fig. 7.43, something like N=2 would be the outcome. Consequently, the equipment of Fig. 7.38 would perform in the sense of a narrow residence time distribution better than a cylindrical fluidized bed (which corresponds to just one perfectly stirred tank), but would still give quite broad distributions of product properties at the outlet. To squeeze such distributions towards uniformity, partitions (weirs) can be placed in the fluidization chamber. Additionally, the equipment can be further elongated. The combination of both... 

Figure 12.1. Modeling mixing by associating a Lagrangian model, which calculates the movements ofEFPs, with a model calculating their mixing in a fluid volume regarded as a perfectly stirred tank reactor...

Figure 12.2. Implementation process of mixing models in a perfectly stirred tank reactor. The fluid volume is fragmented into EFPs of the size of the Kolmogorov scale...

The mixing characteristics of the transfer pipe, on the other hand, are somewhere between plug fiow (no mixing) and perfectly mixed. A test is made on the transfer pipe that shows that it operates as if the total volume of the pipe were split into five equal-sized perfectly stirred tanks connected in series. 

A process consists of five perfectly stirred tanks in series. The volume in each tank is 30 L, and the volumetric flow rate through the system is 5 L/min. At some particular time, the inlet concentration of a nonreacting... 

A perfectly stirred tank is used to heat a flowing liquid. The dynamics of the system have been determined to be as shown in Fig. E14.4. 

Suppose chemical A is in solution in a perfectly stirred tank and its concentration is C°(g/L). The constant volumetric flow into and out of the tank is F (L/min) and the tank volume is V(L). A mass balance on component A leads to... 

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