Velocity reactors

The flow conditions (mass velocity, reactor diameter, etc.). 

On a commercial scale, hexamine is manufactured from anhydrous NHi and a 45% solution of methanol-free formaldehyde. These raw materials, plus recycle mother liquor, arc charged continuously ai carefully controlled rates 10 a high-velocity reactor. Tile reaction is exothermic. "Die reactor effluent is discharged into a vacuum evaporator which also serves as a... 

Given the wide range of industrial applications that involve particle systems, the influence of the operating conditions such as temperature, pressure, velocities, reactor design and any other special conditions, such as the presence of liquid in the reactor, can also significantly affect the... 

Superficial fluid velocity Reactor volume (length3)... 

Due to the shape-selective pore structure of the ZSM-5 class catalysts, the hydrocarbons fall predominantly in the gasoline boiling range. The product distributions are influenced by the temperature, pressure, space velocity, reactor type, and Si/Al ratio of the catalyst [73,74]. Paraffins are dominated by isoparaffins, while aromatics are dominated by highly methyl-substituted aromatics. The C9+ aromatics are dominated by symmetrically methylated isomers reflecting the shape selective nature of the catalysis. The Cj0 aromatics are mostly durene (1,2,4,5-tetramethylbenzene), which has an excellent octane... 

The PSR is compared to a PFR with identical catalyst weight and hourly space velocity. Reactor characteristics are quantified in terms of the conversion of A, the selectivity towards B and the productivity. 

Fig. 5.13 Methane conversion in MR and TR and pure H2 recovered through membrane versus inlet methane hourly space velocity (reactor operating pressure = 15 bar, S/C = 3, wall temperature = 823 K)...

Find the fuel distribution and the corresponding flux that give a constant power distribution in an infinite-slab reactor. Assume (1) a bare one-velocity reactor, (2) the extrapolation boundary condition, and (3) that the diffusion coefficient is unaffected by local variations in fuel concentration. 

Thus the eigenvalues Vn and Bn are related through an equation identical in form to the criticality condition for the one-velocity reactor. This leads us to attempt a physical interpretation of the Vn. Several such observations, along with other properties of the eigenvalues and eigenfunctions, are listed below ... 

In the present study of multi velocity reactors it will be convenient to separate all scattering collisions into two categories. To the first category we assign all nuclear scattering phenomena which cause substantial... 

Let us now consider the application of the set of Eqs. (8.408) to a reflected reactor, assuming that all cross sections and constants have been chosen. For a two-region reactor, for each lethargy interval there are two sets of differential equations, one for the core and one for the reflector. An appropriate set of boundary conditions must be chosen, for example, analogously to that for the one-velocity reactor model thus if and... 

The factor on the left-hand side of Eq. (9.16) may be recognized as the average neutron lifetime in the one-velocity reactor (cf. Sec. 5.4g). It follows immediately from (5.223) that... 

S The flux in a bare homogeneous one-velocity reactor is time dependent. Find this time behavior under the following two (different) physical assumptions (a) all neutrons are prompt b) a fraction /8 of the neutrons from fission are delayed time to. Assume that the form... 

For CCR reformers, the typical operating variables for a given feedstock are reactor temperature, feed rate (or space velocity), reactor pressure, hydrogen to hydrocarbon ratio (H2/HC) and the activity of the catalyst By making changes in the process variables, refiners can make significant shifts in the product distribution. 

Fig. 23. Turbulent and bubbling beds scale-up comparison where increasing gas velocity, fines content, and JT/D staging can help maintain reactor efficiency as the reactor diameter increases. A 100% efficiency is equivalent to plug flow.

One of the most efficient implementations of the slurry process was developed by Phillips Petroleum Company in 1961 (Eig. 5). Nearly one-third of all HDPE produced in the 1990s is by this process. The reactor consists of a folded loop with four long (- 50 m) vertical mns of a pipe (0.5—1.0 m dia) coimected by short horizontal lengths (around 5 m) (58—60). The entire length of the loop is jacketed for cooling. A slurry of HDPE and catalyst particles in a light solvent (isobutane or isopentane) circulates by a pump at a velocity of 5—12 m/s. This rapid circulation ensures a turbulent flow, removes the heat of polymeriza tion, and prevents polymer deposition on the reactor walls. 

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