Abstract: Disclosed are methods and compact apparatus for controlled, on-demand ammonia generation from urea. The process gasifies an aqueous urea solution in a chamber utilizing hot gas while controlling the flows of aqueous urea solution and hot gas to achieve complete gasification of the aqueous urea solution and form a gas mixture comprising ammonia, isocyanic acid, carbon dioxide and water vapor, which is passed through a catalyst bed containing particulate transition metal oxide to convert substantially all of the isocyanic acid to ammonia. A catalyst support and the catalyst bed are aligned with the gasification chamber at the lower end of said chamber to provide a degree of back pressure on the gases in the gasification chamber to isolate the gasification chamber from turbulent exit effects caused by equipment downstream of the thermal reactor. A sample of the product stream is treated to remove water and ammonia, and analyze for carbon dioxide content to control the process.

Abstract: Disclosed are methods and compact apparatus for controlled, on-demand ammonia generation from urea. The process gasifies an aqueous urea solution in a chamber utilizing hot gas while controlling the flows of aqueous urea solution and hot gas to achieve complete gasification of the aqueous urea solution and form a gas mixture comprising ammonia, isocyanic acid, carbon dioxide and water vapor, which is passed through a catalyst bed containing particulate transition metal oxide to convert substantially all of the isocyanic acid to ammonia. A catalyst support and the catalyst bed are aligned with the gasification chamber at the lower end of said chamber to provide a degree of back pressure on the gases in the gasification chamber to isolate the gasification chamber from turbulent exit effects caused by equipment downstream of the thermal reactor. A sample of the product stream is treated to remove water and ammonia, and analyze for carbon dioxide content to control the process.

Abstract: Disclosed are methods and apparatus for providing an ammonia feed for a low-temperature process. The process includes two defined stages, gasification and hydrolysis. In a first stage thermal reactor, an aqueous urea solution is fed to a gasification chamber and heated gases are controlled in response to demand from a low temperature process requiring ammonia. The heated gases and aqueous urea are introduced into the gasification chamber upstream to fully gasify the solution of aqueous urea to a first stage gas stream comprising ammonia and isocyanic acid. The first stage gas stream is withdrawn and maintained hot enough to prevent solids formation. All amounts of urea feed, water and heated gases fed into the first stage thermal reactor are monitored and adjusted as necessary to achieve efficient hydrolysis in the second stage hydrolysis reactor. The second stage gas stream is withdrawn from the second stage reactor responsive to demand from a low temperature process requiring ammonia.

Abstract: Disclosed are methods and apparatus for treating and analyzing a gas stream to determine the ammonia concentration. A gas stream is continuously monitored to determine the ammonia concentration by extracting gas samples from one or more locations and sending it to a tunable diode laser absorption spectroscopy instrument for analysis. By proper placement of sampling probes within a duct, depending on the particular flow patterns that have been determined by suitable modeling, e.g., computational fluid dynamics or cold flow modeling, the valves can be operated manually or by a controller to take samples at predetermined locations within the duct. This will enable taking samples from particular locations, samples representative of the entire cross section, or samples that are an average of a particular cross section. It will be possible by judicious placement of the probes and operation of the valves to map the concentrations of ammonia at a plurality of load settings and will permit continuous control.

Abstract: Disclosed are methods and apparatus for treating and analyzing a gas stream to determine the ammonia concentration. A gas stream is continuously monitored to determine the ammonia concentration by extracting gas samples from one or more locations and sending it to a tunable diode laser absorption spectroscopy instrument for analysis. By proper placement of sampling probes within a duct, depending on the particular flow patterns that have been determined by suitable modeling, e.g., computational fluid dynamics or cold flow modeling, the valves can be operated manually or by a controller to take samples at predetermined locations within the duct. This will enable taking samples from particular locations, samples representative of the entire cross section, or samples that are an average of a particular cross section. It will be possible by judicious placement of the probes and operation of the valves to map the concentrations of ammonia at a plurality of load settings and will permit continuous control.

Abstract: Disclosed are methods and apparatus for providing an ammonia feed for a low-temperature process. The process includes two defined stages, gasification and hydrolysis. In a first stage thermal reactor, an aqueous urea solution is fed to a gasification chamber and heated gases are controlled in response to demand from a low temperature process requiring ammonia. The heated gases and aqueous urea are introduced into the gasification chamber upstream to fully gasify the solution of aqueous urea to a first stage gas stream comprising ammonia and isocyanic acid. The first stage gas stream is withdrawn and maintained hot enough to prevent solids formation. All amounts of urea feed, water and heated gases fed into the first stage thermal reactor are monitored and adjusted as necessary to achieve efficient hydrolysis in the second stage hydrolysis reactor. The second stage gas stream is withdrawn from the second stage reactor responsive to demand from a low temperature process requiring ammonia.