System and apparatus for connecting a gas source to a thermal oxidiser

Abstract

A duct for connecting a source of gas including a volatile organic compound to a thermal oxidiser wherein the duct has a sufficiently sized cross-sectional diameter to reduce the velocity of the gas to below 7 m/s prior to entering the thermal oxidiser

1 . A duct for connecting a source of gas including a volatile organic compound to a thermal oxidiser wherein the duct has a sufficiently sized cross-sectional diameter to reduce the velocity of the gas to below 7 m/s prior to entering the thermal oxidiser. 
     
     
         2 . A duct according to  claim 1  wherein the source of gas includes methane and is derived from a coal mine ventilation system which is introduced via a fan into an inlet of the duct remote from the thermal oxidiser, or which is drawn through the duct into the inlet of the thermal oxidiser by an induce draft fan located at the outlet of the thermal oxidiser. 
     
     
         3 . A duct according to  claim 1  wherein the duct includes a barrier at a point along the length of the duct between the inlet of the duct and the thermal oxidiser, the barrier being moveable between an open position where the gas may pass along the duct between the inlet of the duct and the thermal oxidiser and a closed position where the gas is prevented from moving beyond the barrier along the length of the duct towards the thermal oxidiser. 
     
     
         4 . A duct according to  claim 3  wherein the barrier moves from the open position to the closed position upon the occurrence of an event. 
     
     
         5 . A duct according to  claim 3  wherein the duct further includes a vent located at a point along the length of the duct between the inlet of the duct and the barrier wherein the vent is moveable between an open state and a closed state. 
     
     
         6 . A duct according to  claim 5  wherein the vent moves from the closed state to the open state upon the occurrence of an event. 
     
     
         7 . A duct according to  claim 1  wherein the duct further includes a dilution door to introduce air from outside the duct into the gas passing through the duct to dilute the concentration of the volatile organic compound in the gas. 
     
     
         8 . A duct according to  claim 7  wherein the dilution door also acts as a vent in the event the gas pressure within the duct reaches a predetermined level. 
     
     
         9 . A duct according to  claim 1  wherein the duct further includes one or more safety vents which are retained in a closed position until the pressure within the duct reaches a predetermined level at which time the safety vents move to an open position allowing the gas within the duct to escape to atmosphere. 
     
     
         10 . A duct according to  claim 9  wherein the one or more safety vents are formed in a frangible manner wherein the safety vent opens when the pressure within the duct reaches a predetermined level. 
     
     
         11 . A duct according to  claim 9  wherein the predetermined level is 250 Pa. gauge. 
     
     
         12 . A duct according to  claim 1  wherein the duct further includes an isolation valve located immediately before the thermal oxidiser which provides that the thermal oxidiser may be isolated from the duct and the source of the gas when the isolation valve is closed. 
     
     
         13 . A duct according to  claim 12  wherein the isolation valve is closed upon the occurrence of an event. 
     
     
         14 . A duct according to  claim 4  wherein the event is selected from one or more of the following: a power failure, a methane concentration in the coal mine ventilation system above 1.5%. high pressure in the coal mine ventilation system. 
     
     
         15 . A system for safely connecting a source of gas including a volatile organic compound to a thermal oxidiser, the system including:
 a. a duct according to  claim 1 ; and   b. a monitor located at some point associated with the source of the gas: wherein the monitor is able to detect an event