Proprietary Urea Conversion Process to Generate Ammonia for SCR Systems
- Simplified System - No Hydrolysis
- Compatible with a Wide Range of Urea Sources - No Special Requirements
- Commercial Systems in Operation on Gas Turbines and Utility Coal-Fired Units
- ULTRA-QS™ Quick Start System supports ISO Dispatched Combustion Turbines
Fuel Tech's ULTRA® process is a patented approach that converts safe urea reagent to ammonia for use on new Selective Catalytic Reduction (SCR) systems and in retrofit applications for existing systems. Our ULTRA technology offers a cost-effective solution for simplifying on-site ammonia generation for SCR applications of all types.
Urea products are non-hazardous sources of ammonia, so their transport, storage and use are greatly simplified. Fuel Tech has extensive, proven experience with urea-based systems, and the ULTRA system is built on that solid foundation.
Other urea-to-ammonia conversion systems on the market work by hydrolyzing urea on-site. These processes, which can be complex and expensive, include a high-pressure vessel containing ammonia, and may require the use of specialized urea. Almost all commercially available urea is coated with additives during the manufacturing process to facilitate storage and handling once the product becomes a solid. Hydrolytic systems can be sensitive to the presence of these additives (some of which are formaldehyde based), due to chemical reactions within the hydrolizer, resulting in pluggage and increased maintenance. Urea without additives is a specialized product with limited availability and higher cost. Specialized urea solution is an intermediate product from the urea production process, and requires special handling for site delivery to maintain the product in a narrow temperature range. Dry urea manufactured without additives can create significant handling problems since it is more susceptible to humidity, moisture and breakage than when additives are used.
Fuel Tech’s approach represents a more economical and less complicated way of generating ammonia. The ULTRA process does not involve hydrolysis of urea under high temperature and pressure and, therefore, the system itself is not affected by urea additives, nor is the ammonia mixture supplied to the SCR.
Other advantages include:
- Simplified process, highly efficient urea conversion
- System designed for minimal maintenance
- Specialized urea is not required
- Urea sourcing flexibility helps minimize operating costs
- Minimal potential for corrosion compared with hydrolytic processes
- Low pressure operation
- Process controls designed to follow load with minimal time lag and facilitate rapid system shutdown
- Dry urea storage and handling system option to minimize operating costs
- Relies on controlled urea decomposition reactions that occur in a chamber designed to provide an application-specific temperature and residence time.
- Is simple, consisting of a blower, decomposition chamber, chemical pumping system, urea storage, and process controls.
- Has all the benefits of ammonia supply for SCR without the cost, safety and environmental concerns associated with ammonia handling.
- Is more cost-effective than urea-hydrolyzing processes.
The ULTRA process is a smart choice for simplifying SCR operation with a urea-to-ammonia conversion process.
ULTRA-QS™, just like our standard ULTRA system, has the ability to rapidly respond to changes in ammonia demand rate for combustion units using SCR technology to control NOx emissions. ULTRA-QS facilitates a quick start from standby mode to full operation within minutes. In a standard ULTRA system, there is a warm up time to bring all the components to proper temperature, which can take anywhere from 20 minutes to 2 hours depending upon the size of the installation, capacity of the heating system, and type of insulation used.
The ULTRA-QS Decomposition Chamber operates at 600F in standby mode. After ULTRA-QS system warmup, isolation valves upstream and downstream of the Decomposition Chamber are automatically closed to isolate the Chamber from the main heater and the downstream Ammonia Injection Grid. A recirculation loop in the Decomposition Chamber is created using a smaller high temperature fan and a smaller secondary heater which are designed to heat the process air that is already at elevated temperature. In standby mode, this secondary fan and heater maintain the inlet air temperature to the Decomposition Chamber at 600F.
Once every four hours, an air change occurs to purge any possible impurities that may have deposited in the Decomposition Chamber during normal system operation which were not completely removed during the normal system purge cycle. The ULTRA-QS purge cycle is handled automatically where the small discharge can purge the AIG, or vented to an alternate location.
Once ULTRA-QS is called upon to operate, the secondary fan and heater are shutdown, the Decomposition Chamber isolation valves are opened, and the main fan and heater quickly bring the ULTRA-QS up to full operating temperature. The ULTRA-QS system can be injecting urea and producing ammonia for the SCR within 10 minutes of receiving the operating permissive. The ULTRA-QS system can be used in low ambient temperature environments down to 30 F, where the typical power cost of operating ULTRA-QS in standby mode is only $20 to $25 per day.