Ultrasonic instrument to measure the gas velocity and/or the solids loading in a flowing gas stream

An instrument for measuring the mass flow rate of solids suspended in a gas being transported through a conduit coprising:

• computer means programmed for solving equations of flow, doing numerical analysis and controlling the overall function of said instrument,
• transmitter means for generating packets of ultrasound energy,
• receiver means for detectng the signal strength of said packets of ultrasound energy, said receiver means spaced from said transmitter means whereby said ultrasound packets travel across said conduit, and said signal strength is influenced by the concentration of said solids and the velocity of said gas in said conduit,
• a receiver amplifier for amplifying said signal strengths of said packets detected by said receiver means,
• variable positioning means for changing the relationship between said transmitter means and said receiver means in a manner that enables the sensing of the downstream drift of said ultrasound packets whereby the velocity of said gas in said conduit may be determined,
• controller means for controlling said variable positioning means in response to signals from said computer means and for setting said transmitter means and said receiver means at a plurality of different relationship values,
• gated peak analyzer means for determining a maximum signal strength value from said receiver means for an individual packet of said ultrasound energy including resetting means for resetting said gated peak analyzer means after each of said individual packets of ultrasound energy are analyzed such that said maximum signal strength values for each of said individual packets are independent of each other,
• an analog to digital converter for converting said maximum signal strength values for each of said individual packet to digital form,
• processing means for receiving a plurality of said maximum signal strength values for said individual ultrasound packets and generating a value representative of said plurality of said maximum signal strength values when said transmitter means and said receiver means are at a particular relationship,
• digital memory means for storing a relationship value of said transmitter means and said receiver means and said value representative of said plurality of said maximum signal strength values when said transmitter means and said receiver means are at said relationship, and
• timer means for providing timing signals for said power amplifier and said gated peak analyzer means, wherein said instrument provides an output representing said mass flow rate of solids using said values representative of said plurality of said maximum signal strength values and said relationship values.

A method of measuring the mass flow rate of solids suspended in a gas being transported through a conduit using a device having an ultrasonic transmitter and an ultrasonic receiver, said transmitter and receiver positioned such that packets of ultrasonic energy are transmitted across said conduit, said devices further having means for varying the relationship between said transmitter and receiver in a manner that senses the downstream drift of said packets of energy, said method comprising the steps of:

• (a) positioning said transmitter and said receiver at a first relationship;
• (b) driving said transmitter to generate a plurality of packets of ultrasound energy;
• (c) amplifying by a known amount in a receiver amplifier a signal representative of the received packet of ultrasound energy;
• (d) processing each said signal from said receiver amplifier by a gated peak analyzer to determine the maximum signal strength value received by said receiver for an individual packet of said ultrasound energy and resetting said gated peak analyzer after determining the maximum signal strength for said individual packets such that each of said maximum signal strength values determined for said individual packets is independent of each other;
• (e) storing each said value of maximum signal strength received at said relationship in a digital memory;
• (f) processing the plurality of signals from said gated peak analyzer using numerical techniques to provide a value representative of the signal strength processed by said gated peak analyzer at said first relationship;
• (g) storing said value representative of said signal strengths and a value represenative of said first relationship;
• (h) changing the relationship of said receiver and transmitter from said first relationship to a plurality of other relationships;
• (i) repeating steps (b) through (g) with said receiver and transmitter at said other relationships;
• (j) using the stored values representative of said maximum signal strength at each said relationship and values corresponding to said relationships and using numerical techniques determine the relationship where maximum signal strength occurs and from said relationship calculate the gas velocity;
• (k) using the stored values representative of said maximum signal strengths using numerical techniques calculate a value of maximum signal strength and from this value determine coal loading;
• (l) from said gas velocity and said coal loading, calculate mass flow rate.