Exhaust unit

1. An exhaust unit, comprising:

a dirty air intake opening;

a clean air output opening;

an airflow path defined between the dirty air intake opening and the clean air output opening;

an upstream quenching section along the airflow path, the quenching section having a wetting chamber, the wetting chamber including a reservoir having a fill level for a quenching liquid, and a downtube connected over the dirty air intake opening and opening at its end above, and in opposition to, the plane of the fill level;

a downstream filtering section along the airflow path;

a blower operable to induce airflow along the airflow path;

a motor operable to power the blower;

an air sensor located along the airflow path and configured to generate signals indicating, when the reservoir holds a quenching liquid at the fill level, the air's velocity as it flows out the end of the downtube and is directed at the surface of the quenching liquid; and

a computing device in communication with the motor and the air sensor, the computing device configured to control the operating speed of the motor in response to the signals to maintain the air's velocity as it flows out the end of the downtube and is directed at the surface of the quenching liquid at a setpoint velocity, wherein the setpoint velocity is a velocity where, if the air is dirty air containing swept up particles, at least some of the swept up particles fall from the dirty air and land in the quenching liquid.

2. The exhaust unit of claim 1 , wherein the filtering section has a dirty air chamber, the dirty air chamber opening from the wetting chamber, and including one or more air filters through which the airflow path is defined.

3. The exhaust unit of claim 2 , wherein the filtering section has a clean air chamber, the clean air chamber opening from the dirty air chamber through one or more openings over which the air filters are supported, and opening to the clean air output opening.

4. An exhaust unit, comprising:

a quenching section, the quenching section having a wetting chamber, the wetting chamber opening to a dirty air intake opening, and including a reservoir having a fill level for a quenching liquid, a downtube connected over the dirty air intake opening and opening at its end above, and in opposition to, the plane of the fill level, and upright perimeter walls surrounding the downtube;

a filtering section, the filtering section having a dirty air chamber and a clean air chamber, the dirty air chamber opening from the wetting chamber through an opening defined at the top of one of the wetting chamber's perimeter walls, and including one or more air filters, and the clean air chamber opening from the dirty air chamber through one or more openings over which the air filters are supported, and opening to a clean air output opening;

a blower operable to induce airflow between the dirty air intake opening and the clean air output opening;

a motor operable to power the blower;

an air sensor located between the dirty air intake opening and the clean air output opening and configured to generate signals indicating, when the reservoir holds a quenching liquid at the fill level, the air's velocity as it flows out the end of the downtube and is directed at the surface of the quenching liquid; and

a computing device in communication with the motor and the air sensor, the computing device configured to control the operating speed of the motor in response to the signals to maintain the air's velocity as it flows out the end of the downtube and is directed at the surface of the quenching liquid at a setpoint velocity, wherein the setpoint velocity is a velocity where, if the air is dirty air containing swept up particles, at least some of the swept up particles fall from the dirty air and land in the quenching liquid.

5. The exhaust unit of claim 4 , wherein:

when the reservoir holds a quenching liquid at the fill level, and airflow is induced between the dirty air intake opening and the clean air output opening, air took in at the dirty air intake opening flows through the inside of the downtube, is directed at the surface of the quenching liquid as it flows out the end of the downtube, and is redirected away from the surface of the quenching liquid and between the outside of the downtube and the perimeter walls.

6. The exhaust unit of claim 4 , further comprising:

a fill line, the fill line adapted to connect to a quenching liquid source, and opening to the wetting chamber in communication with the reservoir;

a fill valve included on the fill line, the fill valve selectively actuable to open or close the fill line;

a fill level sensor configured to generate signals indicating the level of a quenching liquid held by the reservoir; and

a computing device in communication with the fill valve and the fill level sensor, the computing device configured to control the actuation of the fill valve in response to the signals to maintain the level of the quenching liquid held by the reservoir at the fill level.

7. The exhaust unit of claim 4 , wherein the wetting chamber has a base and a roof, the reservoir is included at the bottom of the wetting chamber, and the dirty air intake opening opens from the roof.

8. The exhaust unit of claim 4 , wherein the cross section of the inside of the downtube is expanded along a section leading to its end compared to the cross section of the inside of the remainder of the downtube leading from where it connects over the dirty air intake opening, whereby when the reservoir holds a quenching liquid at the fill level, the air's velocity as it flows through the inside of the remainder of the downtube is relatively higher than the air's velocity as it flows out the end of the downtube and is directed at the surface of the quenching liquid.

9. The exhaust unit of claim 1 , wherein:

the wetting chamber has upright perimeter walls surrounding the downtube; and

when the reservoir holds a quenching liquid at the fill level, and airflow is induced along the airflow path, air took in at the dirty air intake opening flows through the inside of the downtube, is directed at the surface of the quenching liquid as it flows out the end of the downtube, and is redirected away from the surface of the quenching liquid and between the outside of the downtube and the perimeter walls.

10. The exhaust unit of claim 1 , further comprising:

a fill line, the fill line adapted to connect to a quenching liquid source, and opening to the wetting chamber in communication with the reservoir;

a fill valve included on the fill line, the fill valve selectively actuable to open or close the fill line; and

a fill level sensor configured to generate signals indicating the level of a quenching liquid held by the reservoir;

wherein the computing device is in communication with the fill valve and the fill level sensor, and the computing device is configured to control the actuation of the fill valve in response to the signals to maintain the level of the quenching liquid held by the reservoir at the fill level.

11. The exhaust unit of claim 1 , wherein the wetting chamber has upright perimeter walls surrounding the downtube, a base and a roof, the reservoir is included at the bottom of the wetting chamber, the dirty air intake opening opens from the roof, and an opening is defined at the top of one of the perimeter walls through which the airflow path is defined between the wetting chamber and the filtering section.

12. The exhaust unit of claim 1 , wherein the cross section of the inside of the downtube is expanded along a section leading to its end compared to the cross section of the inside of the remainder of the downtube leading from where it connects over the dirty air intake opening, whereby when the reservoir holds a quenching liquid at the fill level, the air's velocity as it flows through the inside of the remainder of the downtube is relatively higher than the air's velocity as it flows out the end of the downtube and is directed at the surface of the quenching liquid.

13. The exhaust unit of claim 1 , wherein:

the filtering section has a dirty air chamber, the dirty air chamber opening from the wetting chamber, and including one or more air filters through which the airflow path is defined; and

the filtering section has a clean air chamber, the clean air chamber opening from the dirty air chamber through one or more openings over which the air filters are supported, and opening to the clean air output opening.