# US 2017/0284253 A1 · Aftertreatment systems for dual-fuel engines > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0284253 A1 - Document ID: US20170284253A1 - Status: Published application - Kind: A1 - Application number: 15/518,162 - Filed: 2014-10-16 - Published: 2017-10-05 - Earliest claimed: 2014-10-16 - Assignees: Cummins Emission Solutions Inc. - Applicants: Cummins Emission Solutions, Inc. - Inventors: Yi Liu; Arvind V. Harinath; Arpad Somogyvari - Web page: https://patentgrep.com/patent/US20170284253A1 ## CPC - F01N 3/208: {Control of selective catalytic reduction [SCR], e.g. by adjusting the dosing of reducing agent} - F01N 3/101: {Three-way catalysts} - F02D 19/105: {operating in a special mode, e.g. in a liquid fuel only mode for starting} - F01N 2260/04: for regeneration or reactivation, e.g. of catalyst - F01N 2570/10: Carbon or carbon oxides - F01N 2570/12: Hydrocarbons - F01N 2570/14: Nitrogen oxides - F01N 2610/02: the substance being ammonia or urea - F02D 41/0025: {Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures} - Y02T 10/12: Improving ICE efficiencies - Y02T 10/30: Use of alternative fuels, e.g. biofuels - 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) - F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract Systems and methods for an aftertreatment system configured for use with a dual-fuel engine system are described. The method comprises determining an operating mode of the dual-fuel engine. Upon determining that the dual-fuel engine is operating in a dual-fuel mode or a natural gas mode, the dual-fuel engine operates in a stoichiometric operating condition, and the exhaust is received into a three-way catalyst communicatively connected to a selective catalytic reduction catalyst. Upon determining that the dual-fuel engine is not operating in the dual-fuel mode or the natural gas mode, the engine operates in a lean operating condition. ## Claims ### Claim 1 A method of treating exhaust from a dual-fuel engine, comprising: determining an operating mode of the dual-fuel engine; upon determining that the dual-fuel engine is operating in a dual-fuel mode or a natural gas mode: operating the dual-fuel engine in a stoichiometric operating condition, and receiving the exhaust into a three-way catalyst communicatively connected to a selective catalytic reduction catalyst, the three-way catalyst facilitating desulfation of the selective catalytic reduction catalyst ; and upon determining that the dual-fuel engine is not operating in the dual-fuel mode or the natural gas mode, operating the engine in a lean operating condition. ### Claim 2 (depends on 1) The method of claim 1, further comprising disabling urea dosing when the dual-fuel engine is operating in the dual-fuel mode or the natural gas mode. ### Claim 3 (depends on 1) The method of claim 1, further comprising enabling urea dosing when the dual-fuel engine is not operating in the dual-fuel mode or the natural gas mode. ### Claim 4 (depends on 1) The method of claim 1, wherein the three-way catalyst is configured to reduce nitrogen oxide, carbon monoxide, and hydrocarbons when the dual-fuel engine is operating in the stoichiometric operating condition and operating in the dual-fuel mode or the natural gas mode. ### Claim 5 (depends on 1) The method of claim 1, further comprising using the selective catalytic reduction catalyst to reduce nitrogen oxide when the dual-fuel engine is operating in the lean operating condition and is not operating in the dual-fuel mode or the natural gas mode. ### Claim 6 (depends on 1) The method of claim 1, wherein the selective catalytic reduction catalyst is positioned downstream of the three-way catalyst. ### Claim 7 (depends on 6) The method of claim 6, further comprising using the selective catalytic reduction catalyst to store potential ammonia slip from the three-way catalyst when the dual-fuel engine is operating in the stoichiometric operating condition and operating in the dual-fuel mode or the natural gas mode. ### Claim 8 (depends on 6) The method of claim 6, further comprising using the three-way catalyst to oxidize nitrogen oxide to nitrogen dioxide and reduce hydrocarbons and carbon monoxide when the dual-fuel engine is operating in the lean operating condition and is not operating in the dual-fuel mode or the natural gas mode. ### Claim 9 (depends on 6) The method of claim 6, wherein the three-way catalyst is configured to oxidize nitrogen oxide, carbon monoxide, and hydrocarbons when the dual-fuel engine is operating in the lean operating condition and is not operating in the dual-fuel mode or the natural gas mode. ### Claim 10 (depends on 1) The method of claim 1, wherein the selective catalytic reduction catalyst is positioned upstream of the three-way catalyst. ### Claim 11 (depends on 10) The method of claim 10, further comprising using the three-way catalyst to reduce ammonia, carbon monoxide, and hydrocarbons exiting the selective catalytic reduction catalyst when the dual-fuel engine is operating in the lean operating condition and is not operating in the dual-fuel mode or the natural gas mode. ### Claim 12 (depends on 1) The method of claim 1, further comprising operating the dual-fuel engine in a diesel mode when the dual-fuel engine is not operating in the dual-fuel mode or the natural gas mode. ### Claim 13 A controller for use in an aftertreatment system, the controller comprising: a determination module configured to determine an operating mode of a dual-fuel engine; an operation module configured to operate the dual-fuel engine in a stoichiometric operating condition when the dual-fuel engine is operating in a natural gas mode or a dual-fuel mode, and to operate the dual-fuel engine in a lean operating condition when the dual-fuel engine is not operating in the dual-fuel mode or the natural gas mode; a dosing module configured to control the injection of urea into exhaust downstream from the dual-fuel engine, the dosing module communicating with the operation module to determine when to allow the injection of the urea; and a fuel injection module configured to control an air-fuel ratio in the dual-fuel engine based upon the operating mode of the dual-fuel engine. ### Claim 14 (depends on 13) The controller of claim 13, wherein the dosing module prevents the injection of the urea into the exhaust when the dual-fuel engine is operating in the stoichiometric operating condition and operating in the natural gas mode or the dual-fuel mode. ### Claim 15 (depends on 13) The controller of claim 13, wherein the dosing module enables the injection of the urea into the exhaust when the dual-fuel engine is operating in the lean operating condition and is not operating in the natural gas mode or the dual-fuel mode. ### Claim 16 (depends on 13) The controller of claim 13, wherein the dosing module enables the injection of the urea into the exhaust when the dual-fuel engine is operating in the lean operating condition and is operating in a diesel mode. ### Claim 17 (depends on 13) The controller of claim 13, wherein the fuel injection module creates a lean air-fuel ratio in the dual-fuel engine when the dual-fuel engine is not operating in the dual-fuel mode or the natural gas mode. ### Claim 18 (depends on 13) The controller of claim 13, wherein the three-way catalyst facilitates desulfation of the selective catalytic reduction catalyst when the dual-fuel engine is operating in the stoichiometric operating condition and operating in the dual-fuel mode or the natural gas mode. ### Claim 19 An aftertreatment system configured to be used with a dual-fuel engine operable in a plurality of operating modes, the aftertreatment system comprising: a three-way catalyst positioned downstream of the dual-fuel engine, the three-way catalyst configured to receive exhaust from the dual-fuel engine; a selective catalytic reduction catalyst communicatively connected to the three-way catalyst and positioned downstream of the dual-fuel engine; and a controller configured to determine the operating mode of the dual-fuel engine, wherein the controller operates the dual-fuel engine in a stoichiometric operating condition when the dual-fuel engine is in a dual-fuel mode or a natural gas mode, and wherein the controller operates the dual-fuel engine in a lean operating condition when the dual-fuel engine is not in the dual-fuel mode or the natural gas mode. ### Claim 20 (depends on 19) The aftertreatment system of claim 19, further comprising a doser configured to inject urea into the exhaust, wherein the selective catalytic reduction catalyst uses the urea injected by the doser to reduce nitrous oxide emissions exiting the three-way catalyst when the dual-fuel engine is operating in the lean operating condition and operating in a diesel mode. ### Claim 21 (depends on 19) The aftertreatment system of claim 19, wherein the three-way catalyst is configured to oxidize nitrous oxide exiting the dual-fuel engine into nitrogen dioxide when the dual-fuel engine is operating in the lean operating condition and is not operating in the dual-fuel mode or the natural gas mode. ### Claim 22 (depends on 19) The aftertreatment system of claim 19, wherein the three-way catalyst is configured to reduce carbon monoxide and hydrocarbons exiting the dual-fuel engine when the dual-fuel engine is operating in the lean operating condition and is not operating in the dual-fuel mode or the natural gas mode. ### Claim 23 (depends on 19) The aftertreatment system of claim 19, wherein the three-way catalyst is positioned downstream of the selective catalytic reduction catalyst. ### Claim 24 (depends on 23) The aftertreatment system of claim 23, wherein the three-way catalyst is configured to reduce ammonia, carbon monoxide, and hydrocarbons slipping from the selective catalytic reduction catalyst when the dual-fuel engine is operating in the lean operating condition and is not operating in the dual-fuel mode or the natural gas mode. ### Claim 25 (depends on 19) The aftertreatment system of claim 19, wherein the three-way catalyst is positioned upstream of the selective catalytic reduction catalyst. ### Claim 26 (depends on 25) The aftertreatment system of claim 25, wherein the three-way catalyst facilitates desulfation of the selective catalytic reduction catalyst when the dual-fuel engine is operating in the stoichiometric operating condition and operating in the dual-fuel mode or the natural gas mode.