Apparatus for quantitatively converting urea to ammonia on demand

Abstract

Processes and apparatus for quantitatively converting urea to ammonia on demand are disclosed. One process includes the steps of: receiving a demand rate signal for ammonia; feeding reactants including urea and water into a reactor to provide a reaction mixture; and controlling temperature and pressure in the reactor to produce a gaseous product stream including ammonia and carbon dioxide at substantially constant concentrations. Another process includes the steps of: feeding molten urea or solid urea to a reactor; feeding water (liquid or steam) to the reactor; and reacting the urea and water at elevated temperature and pressure to form a gaseous product stream including anmmonia and carbon dioxide.

1 - 68 . (cancelled).  
     
     
         69 . An apparatus for quantitatively converting urea to ammonia on demand, comprising: 
 an ammonia demand rate signal receiver;    a reactor vessel to contain reactants comprising urea and water at elevated temperature and pressure and to release a gaseous product stream comprising ammonia, carbon dioxide, and water;    a feeder responsive to the demand rate signal for feeding urea into the vessel;    a heater responsive to the demand rate signal for heating the reactants to elevated temperature; and    a variable restriction device in fluid communication with the reactor for maintaining the reactants at elevated pressure and releasing the gaseous product stream.    
     
     
         70 . The apparatus of  claim 69 , further comprising a controller operatively associated with the heater to heat the reactants to a substantially constant temperature.  
     
     
         71 . The apparatus of  claim 70 , further comprising a controller operatively associated with the variable restriction device to maintain the reactor at a substantially constant pressure.  
     
     
         72 . The apparatus of  claim 69 , further comprising a temperature sensor and wherein the variable restriction device is responsive to the temperature sensor.  
     
     
         73 . The apparatus of  claim 69 , further comprising a demister.  
     
     
         74 . The apparatus of  claim 73 , wherein the demister is at least one member selected from the group consisting of mechanical degassers, mist filters, and mesh pads.  
     
     
         75 . The apparatus of  claim 69 , further comprising a urea melter.  
     
     
         76 . An apparatus for quantitatively converting urea to ammonia on demand, comprising: 
 an ammonia demand rate signal receiver;    a reactor vessel to contain reactants comprising urea and water at elevated temperature and pressure and to release a gaseous product stream comprising ammonia, carbon dioxide, and water;    a feeder responsive to the demand rate signal for feeding urea into the vessel;    a heater responsive to the feeder for heating the reactants to elevated temperature; and    a variable restriction device in fluid communication with the reactor for maintaining the reactants at elevated pressure and releasing the gaseous product stream.    
     
     
         77 . The apparatus of  claim 76 , further comprising a demister.  
     
     
         78 . The apparatus of  claim 77 , wherein the demister is at least one member selected from the group consisting of mechanical degassers, mist filters, and mesh pads.  
     
     
         79 . The apparatus of  claim 76 , further comprising a urea melter.  
     
     
         80 . An apparatus for quantitatively converting urea to ammonia on demand, comprising: 
 an ammonia demand rate signal receiver;    a reactor vessel to contain reactants comprising urea and water at elevated temperature and pressure and to release a gaseous product stream comprising ammonia, carbon dioxide, and water;    a level sensor;    a feeder responsive to the level sensor for feeding urea into the vessel;    a heater responsive to the demand rate signal for heating the reactants to elevated temperature;    a temperature sensor; and    a variable restriction device in fluid communication with the reactor and responsive to the temperature sensor for maintaining the reactants at elevated pressure and releasing the gaseous product stream.    
     
     
         81 . The apparatus of  claim 80 , further comprising a demister.  
     
     
         82 . The apparatus of  claim 81 , wherein the demister is at least one member selected from the group consisting of mechanical degassers, mist filters, and mesh pads.  
     
     
         83 . The apparatus of  claim 80 , further comprising a urea melter.  
     
     
         84 . The apparatus of  claim 69 , further comprising a controller operatively associated with the variable restriction device to maintain the reactor at a substantially constant pressure.  
     
     
         85 . In an apparatus for quantitatively converting urea to ammonia, the improvement comprising: 
 a variable speed solid urea feeder;    a vessel for continuously receiving a feed comprising solid urea, said vessel comprising an inlet for receiving solid urea and a fluid outlet in fluid communication with a fluid inlet of a urea hydrolysis reactor;    and a heater disposed in operational relationship with the vessel capable of heating vessel contents to a temperature of at least 133° C.    
     
     
         86 . The improvement of  claim 85 , further comprising a controller operatively associated with the heater to heat the vessel contents, and wherein the heater is capable of heating vessel contents to a temperature in a range of 135° C. to 150° C.  
     
     
         87 . The improvement of  claim 85 , wherein the heater comprises a jacket.  
     
     
         88 . The improvement of  claim 85 , wherein the heater comprises tracing.  
     
     
         89 . The improvement of  claim 85 , wherein the fluid outlet of the vessel is in direct, controllable fluid communication with the fluid inlet of the hydrolysis reactor.  
     
     
         90 . The improvement of  claim 85 , wherein the feeder is a variable speed screw feeder.  
     
     
         91 . The improvement of  claim 85 , further comprising a level sensor operatively associated with the vessel.  
     
     
         92 . The improvement of  claim 85 , further comprising a recirculation conduit having an inlet disposed in fluid communication with the fluid outlet of the vessel, and having an outlet disposed in fluid communication with the vessel interior.  
     
     
         93 . The improvement of  claim 85 , wherein the vessel further comprises a gas phase outlet in communication with a gas phase product outlet of the urea hydrolysis reactor.  
     
     
         94 . The improvement of  claim 85 , wherein the vessel further comprises a gas phase outlet in communication with an ammonia scrubber.  
     
     
         95 . In an apparatus for quantitatively converting urea to ammonia comprising a urea hydrolysis reactor adapted to contain a liquid reaction mixture and discharge a gas phase product comprising ammonia, the improvement comprising a demister in operational relationship with the reactor.  
     
     
         96 . The improvement of  claim 95 , wherein the demister is at least one member selected from the group consisting of mechanical degassers, mist filters, and mesh pads.  
     
     
         97 . In an apparatus for quantitatively converting urea to ammonia comprising a urea hydrolysis reactor adapted to contain a liquid reaction mixture and discharge a gas phase product comprising ammonia, the improvement comprising a mechanical agitator disposed in the urea hydrolysis reactor for operational relationship with a liquid reaction mixture contained therein during operation.  
     
     
         98 . In an apparatus for quantitatively converting urea to ammonia comprising a urea hydrolysis reactor containing an acid catalyst and adapted to contain a liquid reaction mixture and discharge a gas phase product comprising ammonia, the improvement comprising an agitator comprising a steam injector disposed in the urea hydrolysis reactor for agitating a liquid reaction mixture contained therein during operation.  
     
     
         99 . In an apparatus for quantitatively converting urea to ammonia comprising a urea hydrolysis reactor adapted to contain a liquid reaction mixture and discharge a gas phase product comprising ammonia, the improvement comprising an analytical sensor, selected from at least one of a pH sensor and a conductivity sensor, disposed to contact a liquid reaction mixture contained in the urea hydrolysis reactor during operation.  
     
     
         100 . The improvement of  claim 99 , further comprising a control system for the apparatus in communication with the analytical sensor.  
     
     
         101 . The improvement of  claim 99 , wherein the analytical sensor is a pH sensor.