Method and apparatus for extracting gas samples of high temperature gases, particularly for cement rotary kiln furnace exhaust gases

Apparatus for taking gas samples from the exhaust gases of a rotary kiln, comprising:

• a rotary kiln including an opening for discharging exhaust gases and receiving raw material;
• a heat exchanger for preheating the raw material, said heat exchanger including an exhaust gas inlet, a raw material inlet and a raw material outlet;
• walls connected together to define a raw material inlet chamber connecting said rotary kiln opening with said exhaust gas inlet and said raw material outlet of said heat exchanger;
• a passageway through one of said walls;
• gas sampling means outside of said chamber including a gas pick-up device and a gas sampling probe carried by said gas pick-up device;
• control means for moving said gas pick-up device including a drive motor connected to said pick-up device;
• guide means mounting said pick-up device for movement toward and away from said chamber to dispose said probe, through said passageway, into and out of the exhaust gas flow of said furnace;
• and
• door means for closing said passageway when said probe is withdrawn,
• sensing means in said control means for sensing at least one operating parameter and responsive to a predetermined value of that parameter to produce a control signal, and
• emergency operating means in said control means and connected to said sensing means and to said door means and said drive motor and responsive to said control signal to cause withdrawal of said probe and closure of said passageway.

A method of taking gas samples from the exhaust gases of a rotary kiln furnace, comprising the steps of:

• inserting a gas sampling probe from outside of the furnace into the exhaust gas flow of the furnace;
• feeding a gas sample from the probe to gas analyzing equipment outside of the furnace;
• and
• withdrawing the probe from the furnace.

A method of taking gas samples of the exhaust gases of the furnace which has a door to provide access to the flow of the exhaust gases, comprising the steps of:

• opening the door;
• inserting a gas sampling probe through the door and into the flow of exhaust gas;
• transporting a gas sample from the probe to an external gas analyzer while contemporaneously cooling the probe;
• flowing a cleaning agent over the tip of the probe by directing a blast of compressed air at the tip of the probe;
• withdrawing the probe from the furnace;
• closing the door to prevent the escape of exhaust gas and heat and the introduction of unfiltered air;
• and
• monitoring at least one system parameter and immediately causing the sequential steps of flowing a cleansing agent, withdrawing the probe and closing the door upon detection of a predetermined value of that parameter.