Emerson HAS60E-IM-HW SECTION, DESCRIPTION AND SPECIFICATIONS

Instruction Manual

HAS60E-IM-HW

June 2007

NGA 2000 CLD

SECTION 1

DESCRIPTION AND SPECIFICATIONS

1-1 OVERVIEW

This manual describes the Chemiluminescence (CLD) Analyzer Module of Emerson Process Mangement´s NGA 2000 Series of gas analysis components (See Figure 1-2, Figure 1-3and Figure 1-4).

The CLD Analyzer Module is designed to continously determine the concentration of Nitric Oxide and oxides of Nitrogen (NO plus Nitrogen Dioxide [NO2]) in a flowing gaseous mixture. The concentration is expressed in parts-per-million.

The CLD Analyzer Module is designed as a slide-in module (if configured in stand-alone instrument fashion), removable from the front of the Platform, with gas connections made from the rear. All electronics relative to sample detection and conditioning are included in this module.

1-2 TYPICAL APPLICATIONS

The CLD Analyzer Module has specific applications in the following areas:

•Oxides of Nitrogen emissions from the combus- tion of fossil fuels in

Vehicle engine exhaust Incinerators

Boilers

Gas appliances Turbine exhaust

•Nitric acid plant emissions

•De-NOxcontrol system

•Nitric oxide emissions from decaying organic material (e.g., landfills).

1-3 THEORY OF TECHNOLOGY

The CLD Analyzer Module uses the chemiluminescence method of detection. This technology is based on the reaction of NO with ozone (O3) to produce NO2 and oxygen (O2). Some of the NO2 molecules thus produced are in an electronically excited state (NO2* - the "*“ refers to the excitation). These revert immediately to the ground state, with emission of photons (essentially, red light).

The reactions involved are:

NO + O3 → NO2* + O2

NO2* → NO2 + red light

As NO and O3 mix in the reaction chamber, the intensity of the emitted red light is measured by a photodiode and is proportional to the concentration of NO in the original gas sample.

To measure NOx (NO + NO2), any NO2 in the sample is reduced to NO (at < 95 % efficiency) by being continously passed through a heated bed of vitreous carbon (this occurs before the sample gas is presented to the ozone). Any NO initially present in the sample passes through this converter stage unchanged before being routed to the reaction chamber.

The photodiode generates a DC current, which is then amplified, conditioned and expressed on the network as the Primary Variable.

Exhaust

NO Molecule O 2 Molecule

NO

Ozone

O3 Molecule	NO2 Molecule	NO2 Molecule
	(excitated)

Figure 1-1: Function Principle of

CLD Measurement

1-4 FEATURES

Among the features included in the CLD Analyzer Module are:

•1) ozonator air loss shutoff and

•2) NO/NOx mode capability.

Emerson Process Management GmbH & Co.OHG Description and Specifications 1 - 1