APPARATUS FOR CONTINUOUSLY MEASURING CONCENTRATION OF SULFUR TRIOXIDE IN FLUE GAS

PURPOSE:To continuously monitor the concn. of SO3 in flue gas, by a method wherein two systems of exhaust gas sampling/measuring lines are constituted under the same flow passage condition and an SO3-HCl converter is mounted to one system while one system is used as an SO3 measuring line and the other system is used as an HCl compensation line. CONSTITUTION:The exhaust gas introduced from a sampler 1a is passed through the SO3-HCl converter in the sampler 1a and passed through a heating conduit 2a in such a state that the SO3-component was selectively converted to HCl to be absorbed by an absorbing solution in a condenser 4a. The exhaust gas after absorption is exhausted out of the apparatus by an air pump 15 and the absorbing solution containing HCl is supplied to a flow cell 6 by a liquid feed pump 5a. This cell 6 has a chlorine ion electrode and a mercury sulfate electrode and the potential difference corresponding to the concn. of the chlorine ion in the solution is generated between both electrodes and the absorbing solution passed through the cell 6 is guided to a drain tank 8 by a drain pump 7. By this method, the SO3-concn. in flue gas is continuously monitored.