Tell us about the use in the synthesis of ammonia: a) the principle of heat transfer,
Tell us about the use in the synthesis of ammonia:
a) the principle of heat transfer,
b) the circulation principle.
a) For the process of ammonia synthesis, the optimal temperature regime is essential. To ensure the maximum rate of synthesis, the process should be started at a high temperature and, as the degree of conversion increases, it should be lowered. Temperature control is provided by heat exchangers.
Ammonia synthesis is an exothermic reaction, and the heat coming out of the gas synthesis column in the heat exchanger is used to heat the nitrogen-hydrogen mixture to 400-500C. This is how the principle of heat exchange is implemented.
b) a negative consequence of the use of an elevated temperature of 500 C in the synthesis of ammonia is that the equilibrium of the reaction shifts towards the opposite reaction – decomposition of ammonia. This negative effect can be reduced by using increased blood pressure.
However, even when using an increased pressure of 300 atm, the ammonia yield is no more than 20%. The formed ammonia is separated in the separator from the unreacted nitrogen-hydrogen mixture, which is returned to the synthesis column with the help of a circulation compressor. This technique is called the principle of circulation. Thanks to him, the degree of conversion of the nitrogen-hydrogen mixture into ammonia can be increased to 95%,