Car dumper dust control system

1. A method of improving dust control in a rotary rail car dumping facility, the method comprising:

creating at least one secondary air intake positioned to pass through an upper surface of a backside diverter into a backside hood, the backside hood being located in a pit;

locating the secondary air intake at a location at least an attenuating distance from a primary hood intake such that when the pit is subject to spike increases in pressure initiated by a load clearing a rail car and entering the pit, the spike increases in pressure travel into the backside hood the attenuating distance from a primary hood intake before being attenuated, the attenuating distance being that distance from the primary hood intake at which a pressure within the backside hood is less than or equal to a pressure in an interbaffle space that is located between two baffles that contact the upper surface during at least part of rotation of a rotational frame disposed at least partially in the pit.

2. The method as claimed in claim 1 , further comprising positioning the secondary air intake a first distance from a lower edge of the upper surface of the backside diverter substantially equal to or greater than a second distance between a first baffle and a second baffle that at least partially define the interbaffle space.

3. The method as claimed in claim 1 , further comprising constructing the backside hood to comprise at least two backside subhoods each having a tapered portion and a transition portion and further locating the at least one secondary air intake proximate a junction between the tapered portion and the transition portion.

4. The method as claimed in claim 1 , further comprising forming the secondary air intake to be slit shaped having a long axis and orienting the long axis of the slit shaped air intake generally horizontally.

5. The method as claimed in claim 1 , further comprising chamfering edges of the at least one secondary air intake.

6. The method as claimed in claim 1 , further comprising locating a dumpside diverter generally on the dumpsite of the pit.

7. A method of reducing release of dust generated during rotary dumping of rail cars in a rail car dumping facility, the method comprising:

providing a material receiving pit disposed within an interior of the dumping facility, the pit having a dumpside and a backside, if the material receiving pit is not already present;

providing a rotational frame disposed at least partially in the pit, the rotational frame configured to dump a load from a rail car during rotational motion of the rotational frame between an upright position wherein the load is retainable in the rail car and a dumping position wherein the load can clear the rail car, if the rotational frame is not already present;

providing a backside airflow diverter disposed within the pit adjacent the backside of the pit, wherein the backside airflow diverter includes an upper surface, if the backside diverter is not already present,

providing a backside hood for removing contaminated air from the back side of the pit, if the backside hood is not already present;

providing at least two baffles each presenting a leading edge that is configured to contact the backside airflow diverter during at least a portion of the rotational motion including a first baffle and a second baffle, the first baffle coming into contact with the upper surface of the backside diverter prior to the second baffle as the rotational frame moves from the upright position to the dumping position, the leading edges of the two baffles being separated by a first distance along the upper surface of the backside diverter, the first baffle, the second baffle, a baffle support and the backside airflow diverter defining a first interbaffle space when the first baffle and the second baffle are in contact with the backside airflow diverter, if the two baffles are not already present;

determining a pressure in the interbaffle space;

determining that the pit is subject to spike increases in pressure initiated by the load clearing the rail car and entering the pit;

determining an attenuating distance that the spike increases in pressure traveling into the backside hood travel from a primary hood intake before being attenuated, the attenuating distance being that distance from the primary hood intake at which the pressure within the backside hood is less than or equal to the pressure in the interbaffle space; and

locating at least one secondary air intake to pass through the upper surface of the backside diverter into the backside hood at a location at least the attenuating distance from the primary hood intake.

8. The method as claimed in claim 7 , further comprising positioning the secondary air intake a second distance from a lower edge of the backside diverter, the second distance being substantially equal to or greater than the first distance.

9. The method as claimed in claim 7 , further comprising constructing the backside hood to comprise at least two backside subhoods each having a tapered portion and a transition portion and further locating the at least one secondary air intake proximate a junction between the tapered portion and the transition portion, if the least two backside subhoods are not already present.

10. The method as claimed in claim 7 , further comprising forming the secondary air intake to be slit shaped having a long axis and orienting the long axis of the slit shaped air intake generally horizontally.

11. The method as claimed in claim 7 , further comprising chamfering edges of the at least one secondary air intake.

12. The method as claimed in claim 7 , further comprising locating a dump side diverter generally on the dump side of the pit, if the dump side diverter is not already present.