Conducting the reaction A → B in an adiabatic plug flow reactor with pure A at 2 kmol/m3 fed at 0.01 m3/s and 500 K yields 20% conversion. What is the exit temperature in K (given heat of reaction at 298 K = -50000 kJ/kmol A reacted, CPA = CPB = 100 kJ/kmol K, assumed temperature-independent)?
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Answer: C. 600
Explanation
An adiabatic energy balance equates the heat released by the reaction to the sensible heat rise of the fluid. Substituting the given heat of reaction, feed temperature, and 20 percent conversion yields the exit temperature. Solving the energy balance equation calculates an exact adiabatic exit temperature of 600 Kelvin. Adiabatic reactors operate without any heat exchange with the external surroundings through the vessel walls. Heat of reaction quantifies the thermal energy released or absorbed during chemical conversions. Heat capacities allow calculation of temperature changes resulting from exothermic or endothermic reactions.
Industrial adiabatic reactors require careful thermal design to prevent runaway temperatures from damaging equipment. Calculating exit temperatures ensures that catalyst materials do not exceed maximum thermal stability limits. Energy balances form the fundamental basis for thermal simulation and control in chemical plants. Option A 400 K incorrectly assumes an endothermic temperature drop for an exothermic reaction system. Option B 500 K represents the inlet feed temperature without accounting for exothermic heat release. Option D 1000 K overestimates the adiabatic temperature rise by miscalculating conversion enthalpy.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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