Ammonia generating and delivery apparatus

A control system for generating and delivering ammonia, comprising:

• a reductant container holding materials capable of generating ammonia at a temperature higher than an ammonia releasing temperature,
• a heating device for heating said materials in said reductant container,
• an injector fluidly coupled to said reductant container for controlling an ammonia delivery rate,
• a pressure sensor providing a pressure sensing signal indicative of a pressure of ammonia generated from said materials in said reductant container,
• an ammonia generation controller configured to operate said heating device for generating ammonia in said reductant container, and
• a delivery rate controller configured to operate said injector open and close with a PWM control signal in controlling said ammonia delivery rate, including a second stage controller generating a second stage PWM signal according to a set of second stage control parameters and a first stage controller generating a first stage PWM signal by periodically providing values for said second stage control parameters in response to at least a predetermined target value and said pressure sensing signal.

A control system for generating and delivering ammonia, comprising:

• a first container holding a first material capable of generating ammonia at a temperature higher than a first ammonia releasing temperature,
• a first heating device for heating said first material in said first container,
• a second container, which holds a second material capable of storing ammonia at a temperature lower than an ammonia charging temperature and discharging ammonia at a temperature higher than a second ammonia releasing temperature, fluidly coupled to said first container through a heat exchanger and a check valve preventing gas in said second container from flowing back to said first container,
• a second heating device for heating said second material in said second container,
• a pressure sensor providing a pressure sensing signal indicative of a pressure in said second container,
• a first container controller configured to operate said first heating device for releasing ammonia from said first material,
• a second container controller configured to operate said second heating device for charging and discharging said second material,
• an ammonia generation controller configured to enable said second container controller and disable said first container controller when discharging said second material in said second chamber, and enable said first container controller and disable said second container controller when charging said second material in said second container, and
• a pressure controller configured to provide control commands to said first container controller and said second container controller in response to at least said pressure sensing signal obtained from said pressure controller for maintaining a pressure in said second container within a predetermined range.