Tim Israel, P.E.

Sacramento County Department of Waste Management and Recycling

Jeremy Zuber, E.I.T.

Sacramento County Department of Waste Management and Recycling

Tom Morjig

Kurz Instruments

Drivers

Flow Meter Basics

Biogas Flow Metering Issues

Flow Meter Types

Kiefer Landfill

Use of Wet Gas Meters at Kiefer

Conclusions

Federal GHG Inventory

State Inventory

Local Permit Metering Requirements

Energy Project Development

Air District Fees and Title V designation

Variable Flows◦ Flares are designed with up to a 10:1 turndown

Variable Quality◦ CH4 Quality can range from 30% to 50%

◦ 2% change in CH4 translates into 1% flow error

Saturated Gas◦ Big impact on mass flow measurements

Dirty Conditions◦ Affects the accuracy of the measuring device

Requires Mass Flow Measurement

High Turndown

Can Operate in Dirty Environments

Low O&M Cost

Differential Pressure (Orifice Plates, Pitot Tubes, Venturis)

Thermal

Turbine

Vortex

Ultrasonic

Coriolis

Typically an Orifice Plate Type

Consists of an orifice in a straight length of pipe which creates a pressure drop

Static pressure, density, temperature and differential pressure are measured

Measures Volume

Easy to field-service and have no moving parts

Issues: Poor flow turn down, poor tolerance to water and dirt, higher operational cost due to large pressure drop

dPPT

Orifice Plate

Measures the Heat Transfer From a Heated Probe to the Flowing Gas

Easy to Install

Minimal Obstructions and No Moving Parts◦ Dirt tends to blow past sensor

◦ Ideal for dry gas flow measurements

Directly Reads Mass Flow

Accuracy Reduced in Wet Conditions (high reads)◦ Thermal sensor will read false high from varying

water moisture levels entrained in the gas flow.

Heated Sensor5 to 75 °C above process T

Process T sensor

Owned and Operated by Sacramento County

Part of the County’s Vertically Integrated System

Opened in 1967

Approximately 30,000,000 Tons of Refuse in place

History of LFG Migration and Groundwater Impacts

Aggressive LFG Collection and Control

LFG Migration Discovered in Early 90s

High Concentrations Found over 2,000 Feet From Footprint

Original System Began Operation in 1997

Flare Station and 15 Megawatt Power Plant

LFG Collection Both Internally and on Perimeter

Current Flowrate of 7,000 SCFM

Remnants of Original LFG “Cloud” Remain

Achieve Full Backup Capacity In Case of Energy Plant Shutdown

Added Second Flare

Upgraded Controls and Added VFDs

New Standard Thermal Flow Meters for Energy Plant Intakes and New Flare

Energy Plant Meters Reading Inconsistent ~20% High

Spikes in Readings

Attributed to Condensing Gas on Probe

Kurz Replaced Standard Meter With Their Wet Gas Meter (WGF)

300 °C Overheat Thermal Meter

Eliminated the Condensing Gas Issue

Wider sensor stings to avoid water bridging

Capable of reporting wet and dry gas flowrates (rates with or without H2O gas contribution)

Accuracy Verified Through Onsite Field Calibration

Heated Sensor300 °C above process T

Process T sensor

Accurate Flow Meter is Critical for Both Regulatory and Project Development

Wide Variety of Meters that Can be Used

Your Specific Conditions Will Drive Meter Selection