SHERWOOD CURTAIN
The Sherwood Curtain now becomes control introduced in the Tailgate.
My question on the use of the Sherwood Curtain
IS THE SHERWOOD CURTAIN ACTUALLY BEING USED AS PER THE FOLLOWING GUIDELINES OR IS IT A WATERED DOWN VERSION OF IT?
On a retreat face this does not happen and the methane fringe moves forward out of the waste at the return end of the face towards the supply gate machinery. This can cause problems if the methane concentration exceeds 1.25%.
The Sherwood Curtain was developed (at Sherwood Colliery) to overcome this problem and is an arrangement where the gas fringe is held into the waste by directing the airflow at the face end
The ideal arrangement of the Sherwood Curtain is illustrated
The ideal arrangement is where the pressure lock provided by the two sets of doors is intact and the air/methane mixture is forced to travel around the back of the Sherwood Curtain and so keep the gas fringe well into the waste.
http://eprints.nottingham.ac.uk/12977/1/334922.pdf
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The Sherwood Curtain was developed in the Nottinghamshire Area of British Coal and is
used by many Nottinghamshire collieries. It can be used on both advance and retreat
faces.
On an advancing face the ventilating air tends to keep the waste methane away
from the men and machinery on the face side and so electrical equipment is kept free of
gas.
On a retreat face this does not happen and the methane fringe moves forward out of
the waste at the return end of the face towards the supply gate machinery. This can cause
problems if the methane concentration exceeds 1.25%.
The Sherwood Curtain was developed (at Sherwood Colliery) to overcome this problem and is an arrangement where the gas fringe is held into the waste by directing the airflow at the face end
The ideal arrangement of the Sherwood Curtain is illustrated by Figure
The ideal arrangement is where the pressure lock provided by the two sets of doors is
intact and the air/methane mixture is forced to travel around the back of the Sherwood
Curtain and so keep the gas fringe well into the waste.
At the limit of the Sherwood Curtain where it is well behind the line of the goaf the author has recorded methane levels in excess of 5% (the limit of a portable methanometer) and using a high concentration device the methane concentration was found to be around 15%.
In contrast, the supply gate methane readings were less than 0.5%, a sure sign of the usefulness and worth of the Sherwood Curtain.
The arrangement and condition of the curtain is quite critical if it is to remain effective. The curtain does not interfere with the methane concentration or air velocity readings which are taken at the end of the supply gate. At the end of the face life when it was some 30 m away from the monitors, it was still thought to have no effect on these parameters as this distance was deemed to be sufficient for adequate mixing of the air/methane mixture.