Exhaust gas sampling device

Abstract

The present invention provides an exhaust gas sampling device intended to heat or cool a temperature of sampled exhaust gas flowing through a sampling line to a desired temperature in accordance with such as various exhaust gas conditions and usage conditions of the sampling line irrespective of a temperature of the exhaust gas flowing through an exhaust pipe, and includes: the sampling line (2) for sampling the exhaust gas to be introduced into an analyzing instrument (3); a plurality of heating parts (41) to (43) provided along the sampling line (2) from an upstream side to a downstream side for heating the exhaust gas flowing through the sampling line (2); and a temperature control part (5) for individually setting set temperatures (T1) to (T3) of the plurality of heating parts (41) to (43) using the temperature of the exhaust gas in the exhaust pipe (H) and a target temperature (TA) of the exhaust gas in an outlet side of the heating part (43) located in the most downstream as parameters.

Description

technical field [0001] The invention relates to an exhaust gas sampling device for sampling exhaust gas from an exhaust pipe through which the exhaust gas flows, and then leading the sampled exhaust gas into an analysis device. Background technique [0002] Conventionally, as a method for reducing NO contained in engine exhaust from diesel engines X The system has a urea SCR system. The urea SCR system is equipped with an SCR catalyst in the exhaust pipe, and urea ((NH 2 ) 2 CO). [0003] The urea factor (NH 2 ) 2 CO+H 2 O→2NH 3 +CO 2 thermal decomposition reaction to generate NH 3 . Then, the NH 3 In SCR catalysts with NO X response, NO X is reduced to N 2 , thus reducing the NO X . Specifically, in SCR catalysts, 4NH 3 +4NO+O 2 →4N 2 +6H 2 O, 4NH 3 +2NO 2 +O 2 →3N 2 +6H 2 O reduction reaction. [0004] In the system, if the amount of urea injected into the exhaust pipe is excessive, it will cause NH to be discharged downstream of the SCR catalyst ...

AI Technical Summary

Problems solved by technology

Therefore, there is the following problem: although the exhaust gas obtained by sampling contains urea, if the urea cannot be sufficiently thermally decomposed and hydrolyzed in the sampling pipeline to generate ammonia, it is impossible to judge whether the injection amount of urea is an appropriate amount

[0008] However, for the scheme of heating the sampling pipe to a certain temperature in order to prevent adsorption or condensation, etc., there are problems in that the operating temperature of the analysis equipment connected to the sampling pipe, or the filter and throttle provided in the sampling pipe Due to restrictions such as the set temperature of the orifice, etc., the sampling pipe cannot be heated or cooled to a temperature at which specified components such as urea contained in the exhaust gas are thermally decomposed and hydrolyzed.

On the other hand, when the temperature of the exhaust gas obtained by sampling is lower than 113°C, there is a problem that a predetermined component of the exhaust gas cannot be thermally decomposed by simply heating the exhaust gas to 113°C.

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