# US 9,873,084 B2 · Reducing agent pyrolysis system for selective catalytic reduction apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,873,084 B2 - Document ID: US9873084B2 - Status: Granted - Kind: B2 - Application number: 14/901,167 - Filed: 2013-12-06 - Published: 2016-05-12 - Granted: 2018-01-23 - Earliest claimed: 2013-06-28 - Assignees: Doosan Engine Co., Ltd. - Applicants: Doosan Engine Co., Ltd. - Inventors: Jae Moon Lee; Sang Jin Kim; Jong Tae Choi; Chang Hee Lee - Web page: https://patentgrep.com/patent/US9873084B2 ## CPC - B01D 53/9431: {Processes characterised by a specific device} - F01N 3/2033: {using a fuel burner or introducing fuel into exhaust duct} - F01N 3/2066: {Selective catalytic reduction [SCR]} - F01N 3/208: {Control of selective catalytic reduction [SCR], e.g. by adjusting the dosing of reducing agent} - B01D 2251/2067: Urea - F01N 2240/14: a fuel burner - F01N 2240/20: a flow director or deflector - F01N 2610/02: the substance being ammonia or urea - F01N 2610/1453: Sprayers or atomisers; Arrangement thereof in the exhaust apparatus - Y02T 10/12: Improving ICE efficiencies - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - F01N: GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES (arrangements in connection with gas exhaust of propulsion units in vehicles B60K13/00; combustion-air intake silencers specially adapted for, or arranged on, internal-combustion engines F02M35/00; protecting against, or damping, noise in general G10K11/16) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A reducing agent pyrolysis system for a selective catalytic reduction apparatus includes an elbow duct that is installed on an exhaust duct at a front end of a reactor, allows exhaust gas to flow into the elbow duct, and allows the inflow exhaust gas to be discharged toward the reactor. An inner pipe unit is disposed in the elbow duct, and allows a part of the exhaust gas to flow into and be discharged from the inner pipe unit. A heating device is installed in the inner pipe unit, and heats the exhaust gas flowing into the inner pipe unit. A nozzle is installed in the inner pipe unit, is disposed at a rear end of the heating device based on a flow of the exhaust gas, and injects a reducing agent into the inner pipe unit. ## Claims ### Claim 1 A reducing agent pyrolysis system for a selective catalytic reduction apparatus, the reducing agent pyrolysis system comprising: an elbow duct, which is installed on an exhaust duct at a front end of a reactor, allows exhaust gas to flow into the elbow duct, and allows the exhaust gas to be discharged toward the reactor; an inner pipe unit, which is disposed in the elbow duct and allows a part of the exhaust gas to flow into and be discharged from the inner pipe unit; a burner or electric heater, which is installed in the inner pipe unit and heats the exhaust gas flowing into the inner pipe unit; a nozzle, which is installed in the inner pipe unit, is disposed at a rear end of the burner or electric heater based on a flow of the exhaust gas, and injects a reducing agent into the inner pipe unit; and a valve unit, which is installed at a portion of the inner pipe unit where the exhaust gas flows in, wherein a flow rate of the exhaust gas flowing into the inner pipe unit is controlled by controlling an opening and closing operation of the valve unit. ### Claim 2 (depends on 1) The reducing agent pyrolysis system of claim 1, wherein the elbow duct has a first main pipe and a second main pipe that are disposed and connected at a right angle or an obtuse angle, and wherein the first main pipe and the second main pipe have a greater size than an exhaust duct. ### Claim 3 (depends on 2) The reducing agent pyrolysis system of claim 2, further comprising: an orifice unit, which is positioned in the first main pipe, wherein an end of the inner pipe unit is disposed inside an opening of the orifice unit. ### Claim 4 (depends on 1) The reducing agent pyrolysis system of claim 1, further comprising: a mixer unit, which is installed at a portion of the inner pipe unit where the exhaust gas is discharged, wherein the reducing agent and the exhaust gas are mixed by the mixer unit. ### Claim 5 (depends on 4) The reducing agent pyrolysis system of claim 4, wherein the mixer unit is coated with an oxidation catalyst. ### Claim 6 (depends on 1) The reducing agent pyrolysis system of claim 1, wherein the exhaust gas flowing into the inner pipe unit is heated to 450° C. to 600° C. by an operation of the burner or electric heater. ### Claim 7 (depends on 1) The reducing agent pyrolysis system of claim 1, wherein the reducing agent is a urea solution, and the urea solution is thermally decomposed into ammonia (NH3) and isocyanic acid (HNCO) in the inner pipe unit. ### Claim 8 (depends on 1) The reducing agent pyrolysis system of claim 1, wherein when a temperature of the exhaust gas flowing into the elbow duct is higher than a preset temperature, the burner or electric heater is not operated, and the reducing agent is injected toward the reactor. ### Claim 9 (depends on 3) The reducing agent pyrolysis system of claim 3, further comprising: a mixer unit, which is installed at a portion of the inner pipe unit where the exhaust gas is discharged, wherein the reducing agent and the exhaust gas are mixed by the mixer unit. ### Claim 10 (depends on 9) The reducing agent pyrolysis system of claim 9, wherein the mixer unit is coated with an oxidation catalyst.