Tubular parallel mechanism

However, a small-diameter tube gives more pressure drop for a given flowrate through each tube and a given tube length. Of course, a larger number of parallel tubes that are shorter can be used to keep pressure drop at a reasonable level, but this increases the shell diameter of the reactor, which increases the cost. Mechanical problems also limit the minimum tube diameter. Typical tube diameter in cooled tubular reactors is 0.03 m. Typical tube diameter in a furnace-fired heated tubular reactor is 0.15 m. 

In a plug flow reactor all fluid elements move along parallel streamlines with equal velocity. The plug flow is the only mechanism for mass transport and there is no mixing between fluid elements. The reaction therefore only leads to a concentration gradient in the axial flow direction. For steady-state conditions, for which the term IV is zero the continuity equation is a first-order, ordinary differential equation with the axial coordinate as variable. For non-steady-state conditions the continuity equation is a partial differential equation with axial coordinate and time as variables. Narrow and long tubular reactors closely satisfy the conditions for plug flow when the viscosity of the fluid is-low. 

In contrast to stationary applications, portable applications require frequent start and stop procedures. Therefore for SOFC, a robust cell design and adapted electrode-electrolyte assemblies are an important issue. Frequent thermal cycles between room temperature and an operation temperature of about 600-800 °C pose challenges to the layered system consisting of solid anode, ceranfic electrolyte and solid cathode with respect to thermal and mechanical stability. For several years, different approaches to developing tubular nficro SOFC have been undertaken but did not lead to a commercial product yet. As SOFC can be operated with pure hydrogen, reformate and hydrocarbons as fuel as well - the latter option means direct internal reforming at the anode catalyst — various investigations focused on reduced operation temperature and a parallel conversion of fuels [21]. 

The data can also be obtained in an integral fixed reactor, of course. Information on the coke content profile in a tubular reactor may yield valuable information as to the mechanism of coking—parallel or consecutive—and, therefore, as to the form of Pq, as will be shown in the next section. If the integral method of kinetic analysis is applied to the data, as was done by De Pauw and Froment [1975], the conversion 4 replaces the rate Pa in the objective function, requiring integration of the rate equation. 

MCM-41 is the well known model mesoporous material containing extended hexagonal arrays of parallel tubular pores separated by amorphous silica (Fig. 1.). This is a common description, on the heise of most studies to interpret adsorption phenomenon results. However, the structural and chemical parameters of the host porous material have a crucial influence on the adsorption mechanism. Actually each synthesis produces MCM-41 sample with its own silica wall and porosity. Our MCM-41 (19 A < 0 < 40 A) samples have been extensively characterized by sorption isotherm, microcalorimetry and neutron diffraction measurements... 

Several models exist, depending on membrane layout. Plate modules, derived from filter-presses, used to be the first used. (Figure 11.6). The fiuid to be treated circulates between the membranes of two adjacent plates. This assures the mechanical support of the membrane and the draining of the permeate. The systems currently in use are equipped with spiral or tubular modules. Membrane surface is often maximized to compensate for the low delivery rate of these systems. Several modules must be installed in parallel to have a satisfactory delivery rate. 

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