1、Post-Combustion NOxControl for Fired Equipment in General Refinery ServicesAPI RECOMMENDED PRACTICE 536SECOND EDITION, DECEMBER 2006REAFFIRMED, SEPTEMBER 2013Post-Combustion NOxControl for Fired Equipment in General Refinery ServicesDownstream SegmentAPI RECOMMENDED PRACTICE 536SECOND EDITION, DECEM
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16、 Street, NW, Washington, DC 20005, standardsapi.org.iiiCONTENTSPage1 SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 APPLICABLE ENVIRONMENTAL REGULATIONS AND REFERENCES . . . . . .12.1 Environmental regulations.
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18、.22.4 National Standards or a source of carrier steam.3. Ammonia supply pump(s).4. Two cartridge filters and/or strainers.5. Ammonia vaporizer utilizing either an air heater or an external source of heat.6. Instrumentation and interconnecting piping for a fully functional system.7. The recommended c
19、omponents and features noted in 5.4.ii. Anhydrous Ammonia: Vaporized anhydrous ammonia is mixed directly with either an air or steam carrier. A vaporizer usually supplies heat to the storage tank to maintain pressure, and the ammonia vapor is drawn from the vapor space in the tank. The pri-mary comp
20、onents in this system are as follows, and Figure 3 illustrates a typical schematic representation of the system.1. Pressurized anhydrous ammonia storage tank.2. Carrier gas supply: two air blowers, or one blower and a backup air source; or a source of carrier steam.3. Ammonia vaporizer.POST-COMBUSTI
21、ON NOXCONTROL FOR FIRED EQUIPMENT IN GENERAL REFINERY SERVICES 134. Ammoniaair static mixer (if required).5. Instrumentation and interconnecting piping for a fully functional system.6. The recommended components and features noted in 5.4.b. Reactant Injection System (RIS), consisting of:1. Flow dist
22、ribution manifold with a series of injector nozzles that introduce the vaporized ammonia/carrier gas mixture to the flue gas stream.2. The recommended features noted in 5.5 and 5.7.c. System controls, provided by either a local control panel or the plants DCS.5.2.2 Urea-Based SNCR SystemsThe primary
23、 components of a urea-based SNCR system are as follows, and Figure 4 illustrates a typical schematic representation of the system.a. Urea Reactant Control and Dilutions System (RCDS), consisting of: 1. A reactant storage tank.2. Two cartridge filters and/or strainers.3. A reactant metering pump.4. A
24、 water pump, or dilution water source connection.5. An in-line static mixer as required.6. A series of flow indicators and regulating valves, as required, balancing the flow of reactant to each reactant injector. 7. All pertinent instrumentation and interconnecting piping for a fully functional syst
25、em. b. Reactant Injection System (RIS), consisting of:1. An atomizing chamber.2. Interconnecting tubing.3. Injector nozzles that introduce the atomized reactant/carrier air mixture into the flue gas stream.c. System controls, provided by either a local control panel and/or the plants DCS.5.3 SCR SYS
26、TEMS OVERVIEWThere are two major types of SCR systems: aqueous ammonia and anhydrous ammonia. The difference lies in the process used in the Reactant Control and Dilution System (RCDS) to vaporize the ammonia and mix it with the carrier air stream to obtain the reactant charge. SCR systems have one
27、of these two RCDS systems, a Reactant Injection System (RIS), a Selective Catalytic Reactor, system controls, and an Induced Draft Fan (if required):a. RCDSi. Aqueous Ammonia: Aqueous ammonia is pumped from the storage tanks and is commonly mixed with a heated carrier air stream in an ammonia vapori
28、zer/mixer. Alternatively, the ammonia can be vaporized in a once-through vaporizer before mixing with either an air or steam carrier. The primary components in this system are as follows, and Figure 5 illustrates a typical sche-matic representation of the system.1. Aqueous ammonia storage tank.2. Ca
29、rrier air supply: two air blowers, or one blower and a backup air source; or a source of carrier steam.3. Ammonia supply pump(s).4. Two cartridge filters and/or strainers.5. Air heater and ammoniaair vaporizer or ammonia vaporizer.6. All instrumentation and interconnecting piping for a fully functio
30、nal system.7. The recommended components and features noted in 5.4.ii. Anhydrous Ammonia: Vaporized anhydrous ammonia is mixed directly with carrier air or steam. A vaporizer usually supplies heat to the storage tank to maintain pressure, and the ammonia vapor is drawn from the vapor space in the ta
31、nk. The primary com-ponents in this system are as follows, and Figure 6 illustrates a typical schematic representation of the system.1. Pressurized anhydrous ammonia storage tank.2. Carrier air supply: two air blowers or one blower and a backup air source, or a source of carrier steam.3. Ammonia vap
32、orizer.POST-COMBUSTION NOXCONTROL FOR FIRED EQUIPMENT IN GENERAL REFINERY SERVICES 15Figure 2SNCR System Schematics Aqueous AmmoniaPOST-COMBUSTION NOXCONTROL FOR FIRED EQUIPMENT IN GENERAL REFINERY SERVICES 17Figure 3SNCR System Schematics Anhydrous AmmoniaPOST-COMBUSTION NOXCONTROL FOR FIRED EQUIPMENT IN GENERAL REFINERY SERVICES 19Figure 4SNCR System Schematics Urea InjectionPOST-COMBUSTION NOXCONTROL FOR FIRED EQUOPMENT IN GENERAL REFINERY SERVICES 21Figure 5SCR System Schematics Aqueous Ammonia
