Pressurized water reactor side components

In most industrially relevant reacting systems, one main reaction typically makes the desired products and several side reactions make byproducts. The specific rate of production or consumption of a particular component in such a reaction set depends upon the stoichiometry and the rates. For example, assume that the main reaction for making vinyl acetate, Eq. (4.4.1, proceeds with a rate r< (mol/L s) and that the side reaction, Eq. (4.8), proceeds with rate r2 (mol/L s). Then the net consumption of ethylene is (-l)r1 - (-1 )r2 (mol/L s). Similarly, the net consumption of oxygen is (-0.5)fi + (— 3)r2, and the net production of water is (l)r-, + (2)ra. For a given chemistry (stoichiometry), our ability to control the production or consumption of any one component in the reactor is thus limited to how well we can influence the various rates. This boils down to manipulating the reactor temperature and/ or the concentrations of the dominant components. Occasionally, the reaction volume for liquid-phase reactions or the pressure for gas-phase reactions can also be manipulated for overall production control. These are the fundamentals of reactor control. 

This is an endothennic conversion, which takes place in the gas phase between 150 and 300 C (preferably at about 275 C), at a pressure as low as possible, but suffident to recover the isobutene in the l uid phase by cooling with water, namely about 0.6. 10 Pa absolute. To avoid dehydration side reactions, operations are conducted in the presence of steam, with a typical H2O/MTBE mole ratio at the reactor inlet of 5/1. As in the steam cracking ofhydrocarbons, this procedure serves to reduce the partial pressure of the components and to fedlitate the production of isobutene and methanoL... 

The basic component in this system is a sensitive differential pressure transducer (A) with one side measuring atmospheric pressure and the other the internal reactor pressure. The computer monitors the transducer output, and when a slight pressure differential (about a half inch of water) is detected because of the gas uptake in the reactor, the pulse valve (B) is opened to introduce a known volume of gas into the reactor. The size of this pulse is dependent on the gas pressure at the pulse valve and the time it remains open. These factors are adjusted to provide calibrated pulses of near one half cc of reactor gas. The selection valve (S) provides a simple means of using different reaction gases. This apparatus can also be used to study reactions in which a gas is produced. 

In the event of instantaneous guillotine break of one tube in a steam generator with resultant fracture of three further tubes, analysis shows that the reactor shuts down and the event is terminated safely by several automatic operations These include blowdown of the water in the steam generator and tripping of the secondary pump The pressure generated in the secondary piping and the secondary side of the IHX is also kept below the structural integrity limit for these components... 

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