Trace ammonia concentration measuring device and application thereof

Abstract

The invention discloses a trace ammonia concentration measuring device and application thereof. In the trace ammonia concentration measuring device, a sampling probe is used for extracting a tiny part of flue gas with ammonia content to be measured from a flue by a constant-speed wet type sampling method and under the action of an air extracting pump; one part of the extracted flue gas to be measured directly enters an O2 analyzer and an NOX analyzer to measure O2 concentration and NOX concentration, and the other part of the extracted flue gas to be measured passes through an electric heater and a pretreatment module of a catalyst and then enters the NOX analyzer to measure the NOX concentration after all the trace ammonia in the flue gas to be measured reacts with the NOX to be converted into N2; and according to the input O2 concentration signal and NOX concentration signals before and after pretreatment, a data acquisition and analysis system converts and outputs a concentration signal of NH3 in the flue gas. The ammonia concentration is obtained by measuring the NOX concentration change before and after the reaction of the flue gas and all the trace escape NH3 and the number of measuring samples is increased, so measuring precision is improved, and the content of total ammonia, including ammonia salt can be measured.

Description

Technical field [0001] The invention relates to a trace ammonia concentration measuring device and its application, and is especially suitable for measuring the trace ammonia escape amount of flue gas in a coal-fired boiler after ammonia desulfurization or denitrification treatment in the field of environmental protection and its application. Background technique [0002] my country is one of the few countries with coal as the main energy supply, SO produced in the process of burning coal 2 , NO X Air pollutants such as air pollutants have become the main pollution sources that endanger my country's atmospheric environment. In order to reduce SO 2 , NO X emissions, a variety of desulfurization and denitrification technologies have emerged at home and abroad, among which NH 3 The method of using base (such as ammonia, urea) as a removal agent has good engineering applications in desulfurization and denitrification, such as: ammonia-based flue gas desulfurization technolog...

AI Technical Summary

Problems solved by technology

However, there are two main problems in this process: one is that the ammonia volatilized from the ammonia water will escape with the flue gas; Gaseous NH 3 with SO in flue gas 2 A gas phase reaction occurs, including (NH 4 ) 2 SO 3 , NH 4 HSO 3 , (NH 4 ) 2 S 2 o 5 and (NH 4 ) 2 SO 3 ·H 2 O and other components, where (NH 4 ) 2 SO 3 major part

However, in practical engineering applications, the signal generated is very weak due to the low concentration of escaped ammonia; and because the flue gas of coal-fired boilers contains dust and has dynamic changes, the obstruction of dust to the laser analyzer will affect the signal strength, even Completely block laser transmission and reception, and its dynamic changes will cause signal instability, which is not conducive to signal detection

Therefore, the amount of ammonia escape is often measured inaccurately, and the laser gas analyzer can only measure free ammonia, and cannot measure the part of NH in the ammonium salt. 3 For the ammonia desulfurization process, even if the parameter is measured accurately, it cannot fully reflect the real amount of ammonia slip

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