ABB NGC8203 C3+ chromatograph and gas blending

The NGC8203 gas chromatograph

has a special column set to analyze

the components found in low Btu

“Landfill” gas.

Measurement made easy

Overview

The NGC8203 Gas chromatograph has a special

column set to analyze the components found in low

Btu “Landfill” gas. In addition, Totalflow has

constructed a sample system that provides a

pressurized sample to the NGC from the low

pressures typically found in landfill operations.

The low Btu gas is used primarily as fuel for turbines

to produce electricity in a “cogen” operation. In some

gases the landfill gas is blended with higher Btu

components such as propane to raise the quality of the

gas and allow it to be fed into a transmission pipeline.

The components typically found in landfill gas are:

• Methane 54%

• Carbon Dioxide 42%

• Nitrogen 3.1%

• Oxygen 0.8%

• Hydrogen Sulfide less than 1200 ppm

• Carbon Monoxide (indicating under ground combustion)

Stream Composition and ranges for a valid

application for the NGC C3+ Analysis:

• Component Mol%

• Nitrogen 0.1-100

• Carbon Dioxide 0.1-100

• Methane 0.05-100

• Ethane 0.1-100

• Propane 0.05-100

• Hydrogen Sulfide 0.01-0.12

• Oxygen 0.2-20

• Carbon Monoxide 0.2 -100

• Hydrogen 0.1-20

• Ethylene 0.1-100

Recommended sample conditioning

system for landfill application

This sample system is designed to bring

the low pressure landfill gas to the NGC at

an increased pressure (10-20 psig) for

injection into the analyzer.

The pressure is increased by a Di-Vac

pump. The operator can adjust the inlet

stream to an appropriate level of around

15 psig. Most of the sample stream will be

vented through the back pressure regulator.

It can be vented to atmosphere or

returned to the process stream since it is

at a higher pressure. The sample stream is

also passed through a sample

conditioning module which insures that

the NGC will be provided with dry,

uncontaminated gas for the analysis.