Output, reactor comparisons

Table II summarizes the yields obtained from the CONGAS computer output variable study of the gas phase polymerization of propylene. The reactor is assumed to be a perfect backmix type. The base case for this comparison corresponds to the most active BASF TiC 3 operated at almost the same conditions used by Wisseroth, 80 C and 400 psig. Agitation speed is assumed to have no effect on yield provided there is sufficient mixing. The variable study is divided into two parts for discussion catalyst parameters and reactor conditions. The catalyst is characterized by kg , X, and d7. Percent solubles is not considered because there is presently so little kinetic data to describe this. The reactor conditions chosen for study are those that have some significant effect on the kinetics temperature, pressure, and gas composition.

For a continuous-flow reactor, such as a CSTR, the energy balance is an enthalpy (H) balance, if we neglect any differences in kinetic and potential energy of the flowing stream, and any shaft work between inlet and outlet. However, in comparison with a BR, the balance must include the input and output of H by the flowing stream, in addition to any heat transfer to or from the control volume, and generation or loss of enthalpy by reaction within the control volume. Then the energy (enthalpy) equation in words is... 

The output temperature is given by the ambient temperature of the waste-heat loop and can be taken to be 30°C for purposes of estimation. The input temperature of the steam is limited by physical constraints on the reactor primary cooling loop to be about 300°C. Therefore, the maximum Carnot efficiency is approximately carnot = (573 K-303 K)/573 K = 0.47, whereas the actual efficiency is typically 8dec = 0.35 when measured as electrical power outside the plant to total thermal power in the core. For comparison, a coal-powered plant might have values of carnot = 0.65, 8eiec = 0.5 due to higher steam temperatures... 

COMPARISON OF BATCH, TUBULAR AND STIRRED-TANK REACTORS FOR A SINGLE REACTION. REACTOR OUTPUT... 

Table 1.3. Comparison of Continuous Stirred-Tank Reactors and Batch Reactors with Respect to Unit Output W k C0 and Reactor Volume. First-Order Reaction...

Here is a comparison chart of the reactor output data and the results of our simulation for the same plant. 

Chou and Wollast (1984) used a fluidized bed reactor to study albite weathering. An illustration of their device is shown in Fig. 3.5. The flow needed to maintain the feldspar particles in suspension is provided by the pumping rate Plt while P2 is the rate of addition of fresh solution P2 is also the rate of output of the reacted solution. By changing the rate of renewal of P2 one can vary the residence time of the fluid in the reactor. To maintain a small difference in concentration between the input at the bottom of the fluidized bed and the output at the top of the bed, P2 must be small in comparison to Pi. Chou and Wollast (1984) maintained the renewal rate P2 between 3 and 6% of the mixing rate Pi. 

The presentation of the result in the frequency domain offers an additional advantage. The reactor behaviour modelled (Comb. Chamber (,i) can be directly compared with the behaviour calculated (Comb. Chamberc t,). The calculated frequency response of the reactor is the ratio of Che measured output and input spectra. This comparison is not possible in the time domain due to the measurement noise at high frequencies. This noise is amplified by the compensation of the measurement dynamics and thus no useful presentation of data is possible in the time domain. 

Figure 4.42. Demonstration of the efficiency of the incorporation of an ion-exchange preconcentration column into a FIA system for the determination of lead by atomic absorption spectrometry. In (A) is shown the recordings obtained for a series of aqueous lead standards in the range 25-100 xg/L, using the manifold depicted in Fig. 4.41 comprising a dual-column system, that is, the twin peaks for each concentration refer to the outputs for reactors A and B respectively. (B) is the output for a 100 tig/L lead solution prepared in a matrix simulating seawater. For comparison the response of the same instrument, operated under conventional experimental conditions of direct continuous aspiration, but without the inclusion of the on-line preconcentration column, is shown in (C).

The fact that the results obtained earlier and described above were experimentally confirmed was of great importance. The literature does not contain e iq)erimental investigations of rheokinetic problems in which the distribution of flow velocities or residence times (conversion) at the output of the tubular reactor would be studied. Therefore, the results of the experimental investigation of hydrolytic polymerization of dodecalactam in a pilot tubular reactor and the comparison of these results with computation [58] deserve a more detailed presentation. 

The old proposed heavy water—moderated reactor had a core volume almost ten times greater than the present one, while the total power output, 3 10 kw, and virgin—neutron mean free path was the same. Its average virgin flux was thus smaller by a factor of 10. A comparison of the slow, resonance, and fast flux in these light water and heavy water reactors is given in Table 4. 2.A. 

The second series of experiments simulated the most serious accident, which consisted of the shutdown of the primary-circuit and secondary-circuit pumps, as well as the ternary-circuit fans, and the non-operation of the safety rods. Here, reactor output reached 21.2 MW (more than 50% of the rated value), while the mean coolant temperatures at the reactor inlet and outlet came to 402 and 507 C, respectively. A comparison of calculation results and experimental data demonstrated that the fuel residing in the core shared a state of coalescence with the FE cladding and expanded with the cladding upon heating-up. It is in such instances precisely that good agreement is reached between the calculation results and the experimental data concerning the coolant temperature at the subassembly outlet. 

A comparison as a gas-liqnid reactor was afforded by the Dow study of an unspecified reaction where the rate was known to be mass transfer limited. The rate of reaction was, specifically, controlled by the rate of reaction gas absorption into a solvent carrying the second reactant. However, when carried out in the RPB, the data output suggested that the reaction had become kinetically limited. Dow Chemicals stated that this allowed the exploration of the reaction chemistry and kinetics to provide a better understanding of the overall process. This was used to improve other mass transfer-limited reactors, and could lead to more applications for RPBs. The performance of the RPB reactor, illustrated in Figure 5.24, in comparison with an STR showed improvements in reaction rate of 3-4 orders of magnitude, with a 2-3 order increase in mass transfer. 

The spinning disc reactor (see also Chapter 5) was used by the company to produce an active pharmaceutical ingredient (API) that was required in the form of crystals with a specific size distribution (Oxley, 2000). The basis of the work was a 15 cm diameter spinning disc, on which crystalhsation was induced by adding an antisolvent. The improvements observed for the SDR output, in terms of crystal size distribution, are shown in Figure 8.19, where a comparison is made with the normal plant material. Overall, the PI solution compared to conventional production methods gave the following quantified benefits ... 

Having determined the quantity B, the flux relations (8.8) are now completely defined. Note that, as in the bare-reactor results, the expressions for the flux include an arbitrary constant A (or C) which is obtained from the initial conditions. (It is convenient in some cases to evaluate this constant in terms of the total power output of the reactor.) Of some interest here is the comparison of the results for the reflected sphere and for the bare sphere. These are given in Table 8.1. 

The difference between the total thermal output from the fuel and the electrical output is made up of the heat rejected to the heat sink (condenser), plus any heat losses in the reactor circuit, for example from the heat exchangers and the turbine. In practice, these heat losses are small in comparison with the heat rejected to the condenser. The most important factors in determining the thermal efficiency are the temperature of the steam entering the turbine and the temperature of the coolant in the condenser. The efficiency increases as the difference between these two temperatures increases. Since the condenser coolant temperature can vary over only a relatively small range, depending on the ambient temperature of the coolant water, the efficiency depends in practice on the temperature of the steam fed to the turbine. 

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