Sewer flow measurement control system

• US 5,198,989 A
• Filed: 06/13/1990
• Issued: 03/30/1993
• Est. Priority Date: 09/23/1980
• Status: Expired due to Term

• Current Assignee: ADS LLC (ADS Environmental Services Corporation)
• Original Assignee: ADS Environmental Services Corporation
• Inventors: Petroff, Alan M.
• Primary Examiner(s): Chin, Gary
• Application Number:
  US07/537,369
• Time in Patent Office: 1,021 Days
• Field of Search: 364/509, 364/510, 364/565, 364/558, 364/564, 73/196, 73/227, 73/861.18, 73/861.25, 128/661.07, 128/661.09, 128/662.01
• US Class Current: 702/48
• CPC Class Codes: G01F 1/002 wherein the flow is in an open channel
• CPC Class Codes: G01F 1/663 by measuring Doppler frequency shift
• CPC Class Codes: G01F 23/2962 Measuring transit time of reflected waves
• CPC Class Codes: G01P 5/244 involving pulsed waves
• CPC Class Codes: G01S 15/582 using transmission of interrupted pulse-modulated waves and based upon the Doppler effect resulting from movement of targets

Abstract

A sewer flow monitoring system wherein the volume of flow is determined from the depth of fluid in a pipe together with the average velocity of flow through the pipe as determined by detecting the peak velocity from particles flowing in sewage at different velocities and then determining average velocity to be approximately 90% of the peak velocity.

Claims

1. A first sewage flow monitoring system comprising:

first liquid height detection means for providing an indication of a wetted area of a sewage flow conduit of a discrete configuration; and

first velocity sensing means comprising;

sonic means including at least one transducer immersed in sewage flowing in said conduit and including emitting means for emitting a sonic signal generally along the direction of flow of sewage and detecting echo signals from objects flowing generally along the said direction of flow,

signal generating means responsive to said sonic means for providing output signals representative of Doppler signals detected by said sonic means,

multi-signal detection means for receiving the output signals and detecting the presence of a range of different Doppler signals therein,

discrimination means including means responsive to a maximum value in the range of different Doppler signals from the detection means for providing a selected output which is representative of average velocity of sewage flow through said conduit, and

flow computation means responsive to said discrimination means and said first liquid height detection means for indicating the volume of flow through said conduit.

2. A system as set forth in claim 1 further comprising:

second liquid height detection means and second velocity sensing means positioned at a location in said conduit which is spaced from the first liquid height detection means and the first velocity sensing means; and

means for identifying flow volumes from said first liquid height detection means and velocity sensing means and said second liquid height detection means and velocity sensing means, respectively, whereby the difference in said flow volumes is indicative of extraneous flow into said conduit.

3. A system as set forth in claim 1 wherein said first liquid height detection means comprises:

ultrasonic transducer means positionable in the top region of said conduit for transmitting and receiving acoustic energy along a generally vertical path;

signal means coupled to said transducer means and responsive to an input control signal for energizing said transducer means in repetitive bursts of a selected duration of ultrasonic frequency signals to thereby produce bursts of ultrasonic acoustic energy which move downward in a said conduit;

receiver means comprising;

filter means coupled to receive signals received by said transducer means and for passing signals corresponding to signal energy proximate to the frequency of the transmitted ultrasonic signals, and

envelope detection means responsive to the output of said filter means for providing a burst contour signal;

signal timing means responsive to said envelope detection means and a signal from said signal means corresponding in time to a transmitted signal burst from said transducer means for providing an output signal varying as a function of the period between the transmission of said transmitted signal burst and the reception of said signal burst and for providing an output representative of the distance between said transducer means and the surface of a fluid flowing through said conduit;

comparator means for comparing a series of outputs from said timing means, each being a sample representative of said distance, with the preselected values and for providing signal outputs in a form of discrete timing signal samples; and

averaging means responsive to the outputs of said comparator means for averaging said signal samples from said comparator means, and thereby providing an average distance.

4. A system as set forth in claim 1 including means responsive to the indication from said liquid height detection means for computing velocity of the flow from the wetted area of the conduit, and wherein said flow computation means, alternately, employs said computed velocity for computing the volume of flow through said conduit.

5. A system as set forth in claim 4 further comprising a second sewage flow monitoring system, said first sewage flow monitoring system and said second sewage flow monitoring system being positioned at separated upstream/downstream locations in said conduit;

and means for identifying flow volumes from said first and second sewage flow monitoring systems, whereby the difference in said flow volumes between the separated locations is indicative of extraneous flow into said conduit between said locations.

6. A system as set forth in claim 5 wherein each of said sewage flow monitoring systems is positioned in the vicinity of a manhole.

7. A method for determining liquid flow velocity within a conduit comprising emitting from a location within a body of liquid in the conduit an acoustic signal which varies at a selected frequency, detecting at a location within the conduit reflected acoustic signals received from the body of liquid in the conduit which have frequency differences from the selected frequency which are representative of the velocities of the liquid at the locations in the body of liquid from which they are reflected, analyzing the acoustic signals received from the body of liquid according to said frequency differences to provide a difference frequency distribution range having a maximum value and determining from the maximum value in the difference frequency distribution range a value representative of the average velocity of the liquid moving in the conduit.

8. A method according to claim 7 wherein the value representative of the average velocity of the liquid is a value corresponding to approximately 90% of the maximum value in the frequency distribution range.

9. A method according to claim 7 including detecting the level of the surface of the liquid within the conduit and determining a fluid flow rate from the average velocity and the liquid level.

10. Apparatus for determining liquid flow velocity within a conduit comprising acoustic signal-generating means disposed within the conduit for emitting an acoustic signal which varies at a selected frequency, acoustic signal-detecting means disposed within the conduit for detecting acoustic signals reflected from a plurality of locations within a body of liquid flowing within the conduit and which have frequencies representative of the velocities of liquid at the plurality of locations within the body, frequency analyzer means for analyzing the acoustic signals received from the body of liquid within the conduit according to said frequencies to provide a frequency distribution range having a maximum value, and selection means for selecting a value based on the maximum value which is representative of the average velocity of the liquid moving in the conduit.

11. Apparatus according to claim 10 wherein said value corresponds to approximately 90% of the maximum value in the frequency distribution range.

12. Apparatus according to claim 10 including liquid level determining means for determining the level of the surface of the liquid within the conduit and flow computing means for determining a rate of flow of liquid within the conduit from the average velocity and the level of the surface of the liquid.