Under the normal operating pressure of the urea reactor reactions proceed as follows; a part of gaseous NH
3 and CO
2 are absorbed into the solution, which includes formed urea and water, with rise of temperature which promotes successive conversion to urea.
This cycle, absorption and formation of urea, repeats till gas phase substantially disappears and conversion to urea approaches to that at the equilibrium state.
Accordingly, if the fluid in the urea reactor is assumed to flow like piston flow, the introduction of absorption coefficient L, just similar to Bunsen coefficient, enables us to calculate the reactor volume more simply than with a method in which complicate equations for phase equilibriu were usually used.
Pilot test data about the reactor with baffle plates showed that the flow in the reactor was like a piston type and that, the L derived from the data had a simple feature under a given condition of reactor operation. At first the volume for liquid phase was calculated using above L and then the whole volume of a urea reactor which was obtained by addition of volume for gas phase to the above volume was nearly equal to the volume of pilot test reactor.
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