Reactant outlet

The geometric variables are reactor diameter D [L] and reactor length [L], The material variables are fluid viscosity fi [L MT ], fluid density p [L M], fluid heat capacity Cp[L MT 0 ], and fluid heat conductivity k [LMT 0 ]. We must consider the molecular dif-fusivity of reactant Orsfr [L ] since we assume no back-mixing in the reactor. The process variables are reactant inlet concentration Qn and reactant outlet concentration Cout [L N], heat of reaction Ci A/fR [L MT ], fluid velocity through the reactor v [LT ], temperature difference between inlet and outlet fluid ATjo [0], and inlet fluid temperature [0], We determine all the physical properties for this reaction at... 

Ratio and Multiplicative Feedforward Control. In many physical and chemical processes and portions thereof, it is important to maintain a desired ratio between certain input (independent) variables in order to control certain output (dependent) variables (1,3,6). For example, it is important to maintain the ratio of reactants in certain chemical reactors to control conversion and selectivity the ratio of energy input to material input in a distillation column to control separation the ratio of energy input to material flow in a process heater to control the outlet temperature the fuel—air ratio to ensure proper combustion in a furnace and the ratio of blending components in a blending process. Indeed, the value of maintaining the ratio of independent variables in order more easily to control an output variable occurs in virtually every class of unit operation. 

Figure 4-4 shows a semi-batch reactor with outside circulation and the addition of one reactant through the pump. Semi-batch reactors have some reactants that are charged into the reactor at time zero, while other reactants are added during the reaction. The reactor has no outlet stream. Some reactions are unsuited to either batch or continuous operation in a stirred vessel because the heat liberated during the reaction may cause dangerous conditions. Under these... 

A loop reactor is a continuous steel tube or pipe which connects the outlet of a circulation pump to its inlet (Figure 3.1). Reactants are fed... 

Ethanol at concentration at the inlet plus ethanol generated is equal to ethanol in outlet stream as unreacted reactant plus ethanol consumed. For each mole of acetic acid, one mole of ethanol was utilised. The mass of ethanol used up is ... 

Although they are both flow reactors, there are large differences in the behavior of PFRs and CSTRs. The reaction rate decreases as the reactants are consumed. In piston flow, the reactant concentration gradually declines with increasing axial position. The local rate is higher at the reactor inlet than at the outlet, and the average rate for the entire reactor will correspond to some average composition that is between and In contrast, the entire... 

Example 14.1 Consider a first-order reaction occurring in a CSTR where the inlet concentration of reactant has been held constant at uq for f < 0. At time f = 0, the inlet concentration is changed to Up Find the outlet response for t > 0 assuming isothermal, constant-volume, constant-density operation. 

Washout experiments can be used to measure the residence time distribution in continuous-flow systems. A good step change must be made at the reactor inlet. The concentration of tracer molecules leaving the system must be accurately measured at the outlet. If the tracer has a background concentration, it is subtracted from the experimental measurements. The flow properties of the tracer molecules must be similar to those of the reactant molecules. It is usually possible to meet these requirements in practice. The major theoretical requirement is that the inlet and outlet streams have unidirectional flows so that molecules that once enter the system stay in until they exit, never to return. Systems with unidirectional inlet and outlet streams are closed in the sense of the axial dispersion model i.e., Di = D ut = 0- See Sections 9.3.1 and 15.2.2. Most systems of chemical engineering importance are closed to a reasonable approximation. 

The utihty stream gets started at operating temperature and flow rate. In the following experiments, the utihty stream is heated so as to initiate the reaction. The main and secondary process tines are fed with water at room temperature and with the same flow rate as one of the experiments. Once steady state is reached, operating parameters are recorded. Process tines are then fed with the reactants, hydrogen peroxide and sodium thiosulfate. At steady state, operating parameters are recorded, and a sample of a known mass of reactor products is introduced in the Dewar vessel. Temperature in the Dewar vessel is recorded until equilibrium is reached, that is, until the reaction ends. This calorimetric method is aimed at calculating the conversion rate at the product outlet and thus the conversion rate in the reactor. The latter is also determined by thermal balances between process inlet and outlet of the reactor. Finally, the reactor is rinsed with water. This procedure is repeated for each experiment... 

Figure 12.9 shows the temperature recording during the experiment A at the inlet and outlet of the reactor for process and utility streams. At t = 700 s, the reactor is fed with reactants instead of water. 

Fig. 4. Reformer outlet profile with reactant feed rate change by 10% at 1 sec.

A complete methanol reforming system was constructed by coimecting the integrated reformer with a PROX reactor. Fig. 5 shows the evolution of temperature at the gas outlet of the evaporator, reformer and PROX reactor during the start-up. Temperature of the reformer became stable in 5 min after introduction of the reactant. The reformer produced hydrogen up to 1.5L/min with methanol conversion higher than 95%, enough to run a lOOW PEMFC. 

The flow reactor is typically the one used in large-scale industrial processes. Reactants are continuously fed into the reactor at a constant rate, and products appear at the outlet, also at a constant rate. Such reactors are said to operate under steady state conditions, implying that both the rates of reaction and concentrations become independent of time (unless the rate of reaction oscillates around its steady state value). 

A coolant channel is guided through the metal block in a serpentine fashion [15], Hence reactant and coolant flows are orthogonal. A thermocouple measures the temperature at the product outlet of the single-channel thin-film micro reactor. 

Cf, Cm, and c ui are reactant concentrations in the feed, and at the inlet and outlet of the catalyst bed, respectively and Vr is the reactor volume. The mass balance equation for mixing feed with recycle is as follows ... 

The experimental apparatus consists of a gas flow system with a four-port valve, a multi-reflection Attenuated Total Reflection (ATR) accessory (Pike Technologies), and a custom reactor manifold mounted to the ATR top plate, shown in Fig. 45.1. The ATR reactor manifold consists of (i) a Cap2 window for UV irradiation, (ii) an inlet and outlet port, and (iii) an injection port for the liquid phase reactant. 

Figure 5.4a compares the profiles for a mixed-flow and plug-flow reactor between the same inlet and outlet concentrations, from which it can be concluded that the mixed-flow reactor requires a larger volume. The rate of reaction in a mixed-flow reactor is uniformly low as the reactant is instantly diluted by the product that has already been formed. In a plug-flow or ideal-batch reactor,... 

This chapter reports the results from transient experiments (mainly, TPD or TPSR) coupled with on-line analysis of reaction mixture at the outlet of a well-stirred reactor. It means that the gas composition detected at the outlet of the reactor is in contact with the catalyst inside the reactor. Catalytic runs in isothermal conditions were also proceeded in order to avoid strong adsorptions of reactants or intermediates. 

SR greater than 1 refers to fuel lean conditions, while SR less than 1 refers to fuel rich conditions. To convert from fuel rich to fuel lean experimentally, a portion of the helium in the reactant gases was replaced with an equal volume of 02 using a 4-way switching valve. The pressures of the switching valve outlets were balanced such that only the reactant concentration is changed while keeping the flow rates and the pressure constant. 

In principle one can treat the thermodynamics of chemical reactions on a kinetic basis by recognizing that the equilibrium condition corresponds to the case where the rates of the forward and reverse reactions are identical. In this sense kinetics is the more fundamental science. Nonetheless, thermodynamics provides much vital information to the kineticist and to the reactor designer. In particular, the first step in determining the economic feasibility of producing a given material from a given reactant feed stock should be the determination of the product yield at equilibrium at the conditions of the reactor outlet. Since this composition represents the goal toward which the kinetic... 

K] the excess escapes at the top through the side arm D which is connected to a Friedrichs condenser E. The bottom of the condenser is connected to a Y-shaped section with an outlet F for effluent gas and a return G which extends below the surface of the liquid in the reservoir. At the top of the column is a 250-ml. dropping funnel II for admitting reactants to the column. Since oleic acid is a liquid at room temperature, heating of this funnel is not required in the present preparation. At the bottom of the column is a 500-ml. flask I for receiving the product. 

In Fig. 9, the distribution of reactant C is shown in each environment. As cc is a linear combination of and Y2 (Eq. 78), we can distinguish features of both Fig. 7 and Fig. 8 in the plots in Fig. 9. In particular, because C is injected in the right-hand inlet stream, cC2 and 2 appear to be quite similar. Finally, as shown in Liu and Fox (2006), the CFD predictions for the outlet conversion X are in excellent agreement with the experimental data of Johnson and Prud homme (2003a). For this reactor, the local turbulent Reynolds number ReL is relatively small. The good agreement with experiment is thus only possible if the effects of the Reynolds and Schmidt numbers are accounted for using the correlation for R shown in Fig. 4. Further details on the simulations and analysis of the CFD results can be found in Liu and Fox (2006). 

The fractional yield of a product is a measure of how selective a particular reactant is in forming a particular product, and hence is sometimes referred to as selectivity.1 Two ways of representing selectivity are (1) the overall fractional yield (from inlet to a particular point such as the outlet) and (2) the instantaneous fractional yield (at a... 

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