Process simulations of NH3 abatement system for large-scale CO2 capture using aqueous ammonia solution

• NH3 abatement system for ammonia based CO2 capture was investigated.
• Process simulations of NH3 abatement were carried out using rate-base model.
• Effects of key operating parameters on NH3 abatement system were analyzed.
• Concentration of NH3 slip in the gas venting from the NH3 absorber is 1.6 ppmv.
• Simulation result of the flow rate of NH3 slip in vent gas is 1.687 kg/h.

Process simulations of NH3 abatement system for large-scale CO2 capture using aqueous ammonia solution for a 500 MW coal-fired power plant were carried out. For the NH3 abatement system, the lean NH3 solvent was adopted for the absorption of NH3 escaping from the CO2 capture system. Firstly, the equilibrium based model, RadFrac, was used to estimate key operating parameters. Then, the rate based model, RateFrac, was adopted to analyze the effects of different operating parameters on the NH3 absorption and regeneration processes. Under the optimal condition, the flow rate of NH3 slip is 1.687 kg/h and the NH3 concentration in the vent gas is 1.6 ppmv, which both can meet the NH3 emission standards in major countries of the world. If the heat releasing from the condenser of the NH3 regeneration processes is used for the CO2 regeneration, the CO2 regeneration energy will decrease to 3045 kJ/kg CO2. Whereas, if considering the reboiler heat duty in the NH3 regeneration process, the total CO2 regeneration energy of the whole CO2 capture system will increase to 8472 kJ/kg CO2. Besides, the balance evaluation of mass flow rates of gas streams between the CO2 capture system and NH3 abatement system was carried out.

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