Locomotive exhaust aftertreatment system

1 . A system comprising:

an exhaust duct assembly coupled to a locomotive and to a capture car, the exhaust duct assembly including an exhaust duct assembly inlet and an exhaust duct assembly outlet, the exhaust duct assembly inlet being in fluid communication with a locomotive engine exhaust outlet of the locomotive, the locomotive being configured to produce locomotive exhaust through the locomotive engine exhaust outlet;

a generator housed by the capture car, the generator being configured to produce generator exhaust through a generator exhaust outlet;

an aftertreatment system housed by the capture car, the aftertreatment system including an aftertreatment system inlet;

a mixing valve housed by the capture car and having a first inlet in fluid communication with the exhaust duct assembly outlet, a second inlet in fluid communication with the generator exhaust outlet, a first outlet in fluid communication with the aftertreatment system inlet, and a second outlet in fluid communication with the atmosphere; and

a controller configured to receive a first signal indicative of a first system condition and to cause the mixing valve to direct an output gas through the first outlet and/or the second outlet based on the first signal, the output gas comprising the locomotive exhaust, the generator exhaust, or a mixture of the locomotive exhaust and the generator exhaust.

2 . The system of claim 1 , wherein:

the first system condition comprises a low-locomotive-exhaust-temperature condition, and

the controller is configured, in response to the low-locomotive-exhaust-temperature condition, to cause the mixing valve to direct all the output gas through the second outlet into the atmosphere.

3 . The system of claim 2 , wherein the low-locomotive-exhaust-temperature condition comprises a locomotive exhaust temperature value being below 200 degrees Celsius.

4 . The system of claim 1 , wherein:

the first system condition comprises a low-locomotive-exhaust-temperature condition, and

the controller is configured, in response to the low-locomotive-exhaust-temperature condition, to cause the mixing valve to mix locomotive exhaust from the first inlet with generator exhaust from the second inlet and to direct mixed output gas through the first outlet into the aftertreatment system inlet.

5 . The system of claim 4 , wherein the controller is further configured to:

receive a second signal indicative of a temperature-within-range condition, and

in response to the temperature-within-range condition, cause the mixing valve to continue directing the mixed output gas through the first outlet into the aftertreatment system.

6 . The system of claim 4 , wherein the mixed output gas comprises all the locomotive exhaust from the first inlet and all the generator exhaust from the second inlet.

7 . The system of claim 1 , wherein:

the first system condition comprises a backpressure condition, and

the controller is configured, in response to the backpressure condition, to cause the mixing valve to direct at least a portion of the output gas through the second outlet into the atmosphere.

8 . The system of claim 7 , wherein the controller is configured, in response to the backpressure condition, to cause the mixing valve to direct a greater proportion of generator exhaust than of locomotive exhaust through the second outlet into the atmosphere.

9 . The system of claim 1 , wherein:

the first system condition comprises an aftertreatment-system-inactive condition, and

the controller is configured, in response to the aftertreatment-system-inactive condition, to cause the mixing valve to direct all the output gas through the second outlet into the atmosphere.

10 . The system of claim 1 , wherein:

the first system condition comprises an aftertreatment-system-active condition, and

the controller is configured, in response to the aftertreatment-system-active condition, to cause the mixing valve to direct the output gas through the first outlet into the aftertreatment system inlet,

the controller is configured to receive a second signal indicative of a second system condition comprising an aftertreatment-system-inactive condition, and

the controller is configured, in response to the aftertreatment-system-inactive condition, to cause the mixing valve to direct all the output gas through the second outlet into the atmosphere.

11 . The system of claim 1 , wherein:

the generator comprises multiple generator units,

the first system condition comprises a diesel-particulate-filter-regeneration condition, and

the controller is configured, in response to the diesel-particulate-filter-regeneration condition, to:

cause one of the generator units to operate at a higher load level than other generator units to produce generator exhaust that is at a higher temperature than if all the generator units were operating at the same load level, and

cause the mixing valve to mix locomotive exhaust from the first inlet with generator exhaust from the second inlet and to direct mixed output gas through the first outlet into the aftertreatment system inlet.

12 . The system of claim 1 ,

wherein the aftertreatment system further includes an aftertreatment system outlet; and

the system further comprises:

a carbon capture system housed by the capture car, the carbon capture system including a carbon capture gas inlet, and

a bypass valve housed by the capture car and having a bypass valve inlet in fluid communication with the aftertreatment system outlet, a first bypass valve outlet in fluid communication with the carbon capture gas inlet, and a second bypass valve outlet in fluid communication with the atmosphere,

wherein the controller is configured to receive a second signal indicative of a second system condition and to cause the bypass valve to direct an aftertreatment system output gas through the first bypass valve outlet and/or the second bypass valve outlet based on the second signal.

13 . The system of claim 12 , wherein:

the first system condition comprises a backpressure condition, and

the controller is configured, in response to the backpressure condition, to cause the bypass valve to direct at least a portion of the aftertreatment system output gas through the second bypass valve outlet into the atmosphere.

14 . The system of claim 12 , wherein:

the first system condition comprises a carbon-capture-system-inactive condition, and

the controller is configured, in response to the carbon-capture-system-inactive condition, to cause the bypass valve to direct the aftertreatment system output gas through the second bypass valve outlet into the atmosphere.

15 . The system of claim 12 , wherein:

the second system condition comprises a carbon-capture-system-active condition,

the controller is configured, in response to the carbon-capture-system-active condition, to cause the bypass valve to direct the aftertreatment system output gas through the first bypass valve outlet into the carbon capture gas inlet,

the controller is configured to receive a third signal indicative of a third system condition comprising a carbon-capture-system-inactive condition, and

the controller is configured, in response to the carbon-capture-system-inactive condition, to cause the bypass valve to direct the aftertreatment system output gas through the second outlet into the atmosphere.

16 . A method comprising:

providing a locomotive exhaust treatment system, comprising:

a generator having a generator exhaust outlet;

an aftertreatment system including an aftertreatment system inlet,

a mixing valve having a first inlet in fluid communication with a locomotive exhaust outlet of a locomotive, a second inlet in fluid communication with the generator exhaust outlet, a first outlet in fluid communication with the aftertreatment system inlet, and a second outlet, and

a controller in operable communication with the mixing valve;

flowing locomotive exhaust to the first inlet of the mixing valve;

supplying power to the aftertreatment system and the controller from the generator, thereby causing generator exhaust to flow to the second inlet of the mixing valve;

identifying a first system condition associated with the locomotive exhaust treatment system via the controller; and

in response to the identified first system condition, controlling the mixing valve with the controller to do one of:

direct an output gas to the aftertreatment system through the first outlet, the output gas comprising the locomotive exhaust, the generator exhaust, or a mixture of the locomotive exhaust and the generator exhaust,

direct the output gas to the atmosphere through the second outlet, or

direct a first portion of the output gas to the aftertreatment system through the first outlet and a second portion of the output gas to the atmosphere through the second outlet.

17 . The method of claim 16 , wherein:

the first system condition comprises a low-locomotive-exhaust-temperature condition, and

controlling the mixing valve with the controller comprises directing the output gas to the atmosphere through the second outlet, the output gas comprising all the locomotive exhaust and all the generator exhaust.

18 . The method of claim 16 , wherein:

the first system condition comprises a temperature-within-range condition, and

controlling the mixing valve with the controller comprises directing the output gas to the aftertreatment system through the first outlet, the output gas comprising all the locomotive exhaust and all the generator exhaust.

19 . The method of claim 16 , wherein:

the first system condition comprises a backpressure condition, and

controlling the mixing valve with the controller comprises directing the first portion of the output gas to the aftertreatment system through the first outlet and the second portion of the output gas to the atmosphere through the second outlet.

20 . The method of claim 19 , wherein the first portion comprises a greater ratio than the second portion of locomotive exhaust to generator exhaust.

21 . The method of claim 16 , wherein:

the first system condition comprises an aftertreatment-system-inactive condition, and

controlling the mixing valve with the controller comprises directing all the output gas to the atmosphere through the second outlet.

22 . The method of claim 16 , wherein:

the first system condition comprises a diesel-particulate-filter-regeneration condition,

supplying power to the aftertreatment system and the controller from the generator comprises causing a first generator unit of the generator to operate at a higher load level than a second generator unit of the generator, and

controlling the mixing valve with the controller comprises directing the output gas to the aftertreatment system through the first outlet.

23 . The method of claim 16 , wherein:

the locomotive exhaust treatment system further comprises an exhaust duct assembly coupled to the locomotive and to a capture car, the exhaust duct assembly including an exhaust duct assembly inlet and an exhaust duct assembly outlet, the exhaust duct assembly inlet being in fluid communication with the locomotive engine exhaust outlet of the locomotive,

the generator is housed by the capture car,

the aftertreatment system is housed by the capture car,

the mixing valve is housed by the capture car and the first inlet is in fluid communication with the exhaust duct assembly outlet, and

flowing locomotive exhaust to the first inlet of the mixing valve comprises flowing locomotive exhaust through the exhaust duct assembly to the first inlet of the mixing valve.

24 . The method of claim 16 , wherein:

the aftertreatment system further includes an aftertreatment system outlet,

the locomotive exhaust treatment system further comprises:

a carbon capture system housed by a capture car, the carbon capture system including a carbon capture gas inlet, and

a bypass valve housed by the capture car and having a bypass valve inlet in fluid communication with the aftertreatment system outlet, a first bypass valve outlet in fluid communication with the carbon capture gas inlet, and a second bypass valve outlet in fluid communication with the atmosphere, and

the method further comprises:

identifying a second system condition associated with the locomotive exhaust treatment system via the controller; and

in response to the identified second system condition, controlling the bypass valve with the controller to do one of:

direct an aftertreatment system output gas through the first bypass valve outlet into the carbon capture gas inlet,

direct the aftertreatment system output gas through the second bypass valve outlet into the atmosphere, or

direct a first portion of the aftertreatment system output gas through the first bypass valve outlet into the carbon capture gas inlet and a second portion of the aftertreatment system output gas through the second bypass valve outlet into the atmosphere.

25 . The method of claim 24 , wherein:

the first system condition comprises a backpressure condition, and

controlling the bypass valve with the controller comprises directing at least a portion of the aftertreatment system output gas through the second bypass valve outlet into the atmosphere.

26 . The method of claim 24 , wherein:

the first system condition comprises a carbon-capture-system-inactive condition, and

controlling the bypass valve with the controller comprises directing the aftertreatment system output gas through the second bypass valve outlet into the atmosphere.