Primary Systems General Operation

The primary coolant circuit of a PWR is shown in schematic form in Fig. 36. In this particular circuit, there are four loops between the reactor and the steam generators. The pressurizer is also shown, which maintains the pressure in the primary loop at a sufficiently high value (typically 150 bar) such that sustained boiling does not occur and maintains the desired concentration of hydrogen in the coolant. The reactor heat removal system (RHRS) and the reactor water cleanup system are not shown. The general operating conditions in a PWR primary loop are summarized in Table 2. 

Another major cost driver is any time requirement placed on the cleanup process. Time constraints generally require the system to operate more aggressively driving up the cost of the remedy. Aggressive electrokinetic operation often requires greater electrode placement densities (i.e. smaller distances between electrodes) and consequently increased current draw and power consumption. If time is not a primary... 

Bromination has been shown not to exhibit a primary isotope effect in the case of benzene, bromobenzene, toluene, or anisole. On the other hand, several substituted anisoles and derivatives of N,N-dimethylaniline and 1,3,5-trialkylaromatics show isotope effects. The observation of isotope effects in highly substituted systems generally seems to be the result of steric factors that can operate in two ways. There may be resistance to the large bromine taking up a position coplanar with adjacent substituents, as is required in the aromatization step. In other cases, the bulk of several substituent groups may hinder solvent or another base from assisting in proton removal. 

The second consideration is the model for the interstage heaters, product separators and compressors. In order to model these units meaningfully, we must have reasonable estimates for the key thermophysical properties of the lumps. In the case of the reformer, we must make reasonable prediction of reactant concentration (at system pressure), fC-values (for the product separator) and heat capacity (to correctly model the reactor temperature drop and product temperatures). The reforming process generally operates at temperatures and pressures where the ideal gas law applies for hydrocarbon species in the reactor section. Ancheyta-Juarez et al. [1, 2] use the ideal gas assumption to calculate the concentration of reactant species. In addition, they use the polynomial heat capacity correlations for pure components to approximate the heat capacity of the mixture. Work by Bommannan et al. [30] and Padmavathi et al. [31] uses a fixed value for the heat capacity and fC-value correlation to predict compositions in the primary product separator. 

Styrene is an important monomer of the plastics industry, generally produced from benzene (a known carcinogen) and ethylene (produced from thermal cracking of hydrocarbons). A more desirable process would be to convert toluene to ethylbenzene through a reaction with methane, the primary component of natural gas. In a 2009 BASF patent, they report a new catalyst that allows such a process to occur. Our goal is to identify the temperature at which the unreacted toluene can be recovered as a liquid when the system is operating at 100 psia. The composition of the vapor product contains 80% ethylbenzene and the remainder toluene. What is the liquid composition at the dew point ... 

Small Communities. Small communities and recent subdivision additions to larger communities, which have not yet been coimected to municipal coUection systems, must have a means of waste disposal. Septic tanks are a possibiHty, but require periodic servicing and cleaning. Furthermore, the soil is not always suitable for accepting the effluent. An alternative is the package plant. These units are commercially produced to serve small areas. They furnish primary treatment and some secondary treatment, and require only minimal operating supervision. Capacity can be varied as needs dictate. In general, pubHc health authorities prefer such installations instead of septic tanks. 

Some species have a large number of exchangeable hydrogens. Thus, metal ions with many coordinated water molecules will become completely deuterated in D20. For example, Co(H20) + becomes Co(D20) +. If there were a 2 percent secondary kie per bond, it would be amplified to (1.02)12 or 1.27. It would not be a simple matter to demonstrate the operation of a primary kie in such a system because of this, given the p/f difference between the two metal ions and the general effects of the solvent change. 

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