The KWI BTEX Eliminator is designed to condense the emissions from the still column of glycol dehydrators. The hot vapors are routed through the heat exchanger, reducing the temperature and volume of the steam and hydrocarbons produced by the dehydration process. The liquids condensed are routed by gravity into a small tank placed at the base of the condenser. The tank dumps these liquids automatically, and must be connected to a holding tank. The vapors remaining uncondensed are routed through a separation and filtering media, then to either the main burner of the dehydrator, or to the exhaust stack. All VOC's are either condensed into liquids which may be separated and sold, or are burned.
BTEX Schematic Diagram 2
The VOC's are routed from the condenser through the gas liquid separator (1), a flame arrestor (2), a manual valve (3), the emergency shutdown valve (12), then either to the burner through the normally closed valve (4), or to the exhaust stack normally open valve (5).
These valves (4) and (5), along with the original equipment burner supply valve (6) are controlled by the temperature controller (7). During normal operation, when the thermostat (7) supplies pressure to operate the burner supply valve (6), the pressure also opens the vapor valve (4) and closes the vapor valve (5).
A KWI air mixer adapter allows the draft of fuel gas to mix the vapor with primary air in the main burner.
When the set temperature of the glycol in the reboiler is reached, the thermostat removes pressure from the valves, allowing the waste vapors to be diverted into the exhaust stack, where they are mixed with hot air being drafted into the fire tube and stack and ignited.
An over temperature controller (8) supplies pressure to the thermostat (7) to operate the control valves. This pressure is also used to operate a 2" motor valve (9) mounted on the heat exchanger. This valve (9) allows the vapors to be vented to the atmosphere during startup and automatic shutdown. It will open automatically in the event the over temperature control (8) or the high level shutdown (11) is tripped. The emergency shutdown valve (12) will also close at the same time.
The glycol pump should be stopped before beginning the starting sequence.
All gas and waste vapors must be allowed to clear from the fire tube and exhaust stack before lighting the pilot.
When lighting the pilot, the system should be bypassed by closing valves (10) and (3). Set the thermostat (7) to desired glycol temperature.
When the glycol reaches temperature, start the glycol pump and begin circulation through the contactor and reboiler tank.
The BTEX Eliminator is designed to handle the vapors generated under normal conditions. If the glycol is saturated with excess water, it will be necessary to allow the excess water to dissipate before opening valves (3) and (10).
The BTEX Eliminator may be isolated from the burner and exhaust stack at any time by closing valves (10) and (3).
This allows the vapors to vent through motor valve (9).
The dehydrator may then be serviced or operated normally.
It is important to keep the glycol flow to the minimum necessary to achieve the desired dewpoint of the gas stream. Any excess in flow rate will cause additional hydrocarbons to be absorbed by the glycol in the contactor. These hydrocarbons must then be condensed or burned.
If a two or three phase separator is used in the wet glycol stream, the load on the condenser is greatly reduced. If no separator is used, any excess glycol flow rate may cause an overly-rich fuel mixture, smoking, or flames from the exhaust stack.
Service and Maintenance
The KWI BTEX Eliminator system has very few moving parts. The Kimray valves and temperature controller are used extensively in the oil industry.
Maintenance of the KWI tank is covered in the service instructions.
A pressure gauge is provided to assist in determining operation of the Kimray motor valves. This pressure gauge will indicate any blockage or restriction of flow in the filtering media or flame arrestor.
The 2" motor valve (9) should be cycled monthly by closing manual valve (10). Operation of the vent valve can be confirmed by either a drop in system pressure, or if the manual valve (3) is closed briefly, no increase in pressure.