System and method for control of a stripper tower

A method of operating a stripper tower comprising the steps of:

• measuring a temperature TB of an aqueous solution at a bottom of the stripper tower;
• determining a temperature TC of saturated steam based on an operating pressure of the stripper tower;
• determining a temperature T1, wherein T1 is the temperature of the aqueous solution exiting the stripper tower at an underflow outlet having a specific ammonia content at the underflow outlet and in a stripper tower having a specific operating pressure;
• adjusting a flow rate of saturated steam into the stripper tower so that TB is substantially equivalent to the difference between TC and T1.

A system for stripping ammonia from an aqueous solution, the system comprising:

• a stripper tower having an inlet for receiving an aqueous solution and an inlet for receiving saturated steam;
• a first temperature sensor configured to measure a temperature TM of the aqueous solution at a first elevation in the stripper tower;
• a controller;
• a first database containing a plurality temperatures TC, wherein each TC corresponds to the temperature of saturated steam at an operating pressure of the stripper tower;
• a second database containing a plurality of temperatures TDELTA, wherein each TDELTA corresponds to a difference between a temperature of the aqueous solution in the stripper tower at the first elevation subject to over stripping conditions and a temperature of the aqueous solution in the stripper tower at the first elevation subject to normal stripping conditions;
• software executing on the controller for querying the first database by the operating pressure of the stripper tower to retrieve a TC,
• software executing on the controller for querying the second database by the temperature of the aqueous solution in the stripper tower at the first elevation to retrieve a TDELTA,
• software executing on the controller for generating a signal indicative of an adjustment of a flow rate of saturated steam into the stripper tower so that TM is substantially equivalent to the difference between TC and TDELTA.

A system for stripping ammonia from an aqueous solution, the system comprising:

• a temperature sensor configured to measure a temperature TB of the aqueous solution at a bottom of the stripper tower;
• a first database containing a plurality temperatures TC, wherein each TC corresponds to the temperature of saturated steam at an operating pressure of the stripper tower;
• a second database containing a plurality of temperatures T1, wherein each T1 corresponds to the temperature of an aqueous solution at the bottom of the stripper tower having a specific ammonia content and at the operating pressure of the stripper tower;
• software executing on the controller for determining a flow rate of saturated steam into the stripper tower so that TB is substantially equivalent to the difference between TC and T1.