U.S. patent application number 14/060706 was filed with the patent office on 2014-04-24 for visual monitoring system for covered storage tanks.
This patent application is currently assigned to Syscor Controls & Automation Inc.. The applicant listed for this patent is Syscor Controls & Automation Inc.. Invention is credited to Dale SHPAK, Nikolay Nikolov TZONEV.
Application Number | 20140111642 14/060706 |
Document ID | / |
Family ID | 50484996 |
Filed Date | 2014-04-24 |
United States Patent
Application |
20140111642 |
Kind Code |
A1 |
TZONEV; Nikolay Nikolov ; et
al. |
April 24, 2014 |
VISUAL MONITORING SYSTEM FOR COVERED STORAGE TANKS
Abstract
A visual monitoring system for covered storage tanks, comprising
in combination a storage tank, an Imaging Unit and a Communication
Unit. The storage tank has a peripheral wall, a fixed ceiling and a
floating roof that travels up and down the peripheral wall. The
Imaging Unit is positioned within the covered storage tank and
includes a Camera, a Microcontroller, a Power Source and a Wireless
Communication Interface. The Camera is mounted on one of the
ceiling or the wall adjacent to the ceiling and is focused upon the
floating roof. The Communication Unit receives wireless
communication signals from the Imaging Unit providing imaging data
regarding the floating roof.
Inventors: |
TZONEV; Nikolay Nikolov;
(Victoria, CA) ; SHPAK; Dale; (North Saanich,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Syscor Controls & Automation Inc. |
Victoria |
|
CA |
|
|
Assignee: |
Syscor Controls & Automation
Inc.
Victoria
CA
|
Family ID: |
50484996 |
Appl. No.: |
14/060706 |
Filed: |
October 23, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61717436 |
Oct 23, 2012 |
|
|
|
Current U.S.
Class: |
348/143 |
Current CPC
Class: |
B65D 90/48 20130101;
B65D 88/34 20130101; B65D 90/22 20130101; B65D 2590/0083
20130101 |
Class at
Publication: |
348/143 |
International
Class: |
B65D 90/48 20060101
B65D090/48 |
Claims
1. A visual monitoring system for covered storage tanks, comprising
in combination: a storage tank having a peripheral wall, a fixed
ceiling and a floating roof that travels up and down the peripheral
wall; an Imaging Unit positioned within the covered storage tank,
the Imaging Unit comprising a Camera, a Microcontroller, a Power
Source and a Wireless Communication Interface, the Camera being
mounted on one of the ceiling or the wall adjacent to the ceiling,
the Camera having a field of view that includes at least part of
the floating roof; and a Communication Unit remote from the covered
storage tank, the Communication Unit comprising a Microcontroller,
a Power Source and a Wireless Communication interface, the
Communication Unit receiving wireless communication signals from
the Imaging Unit providing imaging data regarding the floating roof
via their respective Wireless Communication Interface.
2. The visual monitoring system of claim 1, wherein visual markers
are located on the floating roof to provide positional information
when used in conjunction with the Camera.
3. The visual monitoring system of claim 1, wherein one or more
sensors are associated with the Imaging Unit and image acquisition
is automatically initiated by the Microcontroller of the Imaging
Unit following the detection of an anomalous condition by the one
or more sensors.
4. A method of visual monitoring of a floating roof of a covered
storage tank, comprising: providing an Imaging Unit comprising a
Camera, a Microcontroller, a Power Source and a Wireless
Communication Interface; providing a Communication Unit comprising
a Microcontroller, a Power Source and a Wireless Communication
interface; positioning the Communication Unit remote from the
covered storage tank; positioning the Imaging Unit within the
covered storage tank with the Camera being mounted on one of the
ceiling or the wall adjacent to the ceiling, the Camera having a
field of view including at least part of the floating roof; and
sending wireless communication signals from the Imaging Unit to the
Communication Unit via their respective Wireless Communication
Interface providing imaging data regarding the floating roof.
5. The method apparatus of claim 4 wherein a human operator
initiates image acquisition.
6. The method of claim 4 wherein image acquisition is automatically
initiated by the Microcontroller of the imaging Unit on a scheduled
basis.
7. The method of claim 4 wherein one or more sensors are associated
with the Imaging Unit and image acquisition is automatically
initiated by the Microcontroller of the Imaging Unit following the
detection of an anomalous condition by the one or more sensors.
8. The method of claim 4 further comprising a means of image
encoding is provided and the wireless signals are encoded.
9. The method of claim 8 further comprising where the means of
image encoding is a means of motion video encoding.
10. The method of claim 4 further comprising the use of one or more
visible markers to determine the elevation of the floating roof
within the aboveground storage tank.
11. method of claim 4 further comprising the use of computer vision
techniques to determine the elevation of the floating roof within
the aboveground storage tank.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/717,436 filed on Oct. 23, 2012.
FIELD OF THE INVENTION
[0002] This invention relates to the remote visual monitoring of
the space between the floating roof and the fixed roof of a covered
aboveground storage tank (AST). This monitoring system can be used
to view visible or invisible optical wavelengths and is used to
monitor for fires, leaks, mechanical problems, and other hazardous
conditions, or to determine the elevation of the floating roof
within the AST. Additionally, since the appearance of the space
being monitored does not often change, alarm conditions or operator
notifications can be triggered when the visual field of the camera
changes. The monitoring system can use wired or wireless means, or
a combination thereof, for communication.
BACKGROUND OF THE INVENTION
[0003] The processing and storage of chemical compounds, such as
petrochemicals, is quite widespread. Since many of these compounds
can be toxic, flammable, or potentially explosive, there are grave
safety concerns for personnel and for the environment.
Additionally, the capital, environmental, and human costs of a
disaster at a processing facility can be staggering.
[0004] In the petroleum industry, each large aboveground storage
tank (AST) has a roof that floats on top of the stored liquid. This
prevents having a potentially explosive vapor space between the
liquid and the roof of the AST. The roof typically floats on
pontoons and has a flexible seal around its perimeter to minimize
the escape of liquid or vapor from the inside of the AST. However,
the escape of at least small quantities of liquid or vapor is
inevitable.
[0005] Covered AST's have a fixed roof above the floating roof that
serves both to protect the floating roof and to reduce the amount
of evaporation into the atmosphere. In the petroleum storage
industry, a current industry practice for monitoring covered AST's
is to perform manual inspections through roof hatches. A minimal
visual inspection can check that the floating roof appears to be
floating properly, that there is no visible liquid on the roof, and
that the seal is visibly intact. Additional manual inspections
include measuring the internal atmosphere to cheek that it has a
volatile gas concentration that is less than prescribed limits.
[0006] Manual inspection is generally non-comprehensive and, since
it occurs infrequently, such as annually or monthly, it could miss
the timely detection of a potentially catastrophic condition.
Remote monitoring makes it operationally feasible to inspect and
monitor the AST more frequently and thoroughly, thereby
facilitating the detection of potentially hazardous conditions in a
timelier manner. The AST can be inspected at scheduled intervals,
on demand, or when monitoring devices such as gas sensors detect an
anomalous condition.
[0007] Another operational hazard is the overfilling of AST's. When
an AST is overfilled, the elevation of the floating roof within the
tank is excessive and large quantities of liquid can escape from
the AST, often with dire consequences such as catastrophic
fires.
BRIEF SUMMARY OF THE INVENTION
[0008] The current invention is a visual monitoring system and a
related method for the visual monitoring of the space between the
floating roof and the fixed roof of a covered above ground storage
tank (AST).
[0009] This invention is presented in the context of use in the
petrochemical industry where the integrity of the floating roof,
the escape of liquid or gas, and fires are of great concern but it
is also suitable for deployment for other industrial
applications.
[0010] The invention comprises two types of units that communicate
using wireless means. The Imaging Unit includes at least one
digital camera and at least one wireless communication link. The
Communication Unit contains at least one wireless communication
link and may also contain one or more wired communication links.
The Communication Unit is used to relay information from the
Imaging Unit to the system operator or to a remote monitoring
system by wired or wireless means. The Communication Unit or the
Imaging Unit may also be directly connected to an alarm system or
an audible or visual alarm by wired or wireless means.
[0011] The Imaging Unit is battery powered and consequently it is
important to conserve power. Since the visual field being monitored
by the camera does not change often, one method of conserving power
is to use a low flame acquisition rate. As an example, an image
frame could be captured once every hour. The frame rate is not
necessarily a fixed value and could be increased if an anomalous
condition is detected.
[0012] Herein, an anomalous condition is any operational condition
that is of concern to the plant operator including, but not limited
to, the existence of flames, excessive vibration, excessive gas
concentration, or the improper position of the floating roof.
[0013] When compared to the current industry practice of manual
inspection, major benefits of the current invention include:
inspection at more frequent intervals (e.g., multiple times per
day), thereby improving the probability of the timely detection of
a potentially catastrophic event and avoiding the exposure of
personnel to potentially hazardous conditions. It also features low
power consumption, thereby allowing long-term autonomous
operation.
[0014] The proposed invention can also be used to optically monitor
the elevation of the floating roof within the AST, thereby helping
to reduce the danger of overfilling the AST.
[0015] A further potential benefit of the invention is that the
ease of installation and low installed cost may serve to hasten the
upgrading of safety systems.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1: Functional Block Diagram of the Proposed
Apparatus
[0017] FIG. 2: Functional Block Diagram of the Imaging Unit
[0018] FIG. 3: Functional Block Diagram of the Communication
Unit
[0019] FIG. 4: A side elevation view, in section, of a visual
monitoring system for covered storage tanks.
DETAILED DESCRIPTION OF THE INVENTION
[0020] With reference to the block diagram in FIG. 1, the invention
minimally comprises a Communication Unit 1 and an Imaging Unit 2
that communicate via wireless means using Antennas 3. The
configuration of the Antennas 3 is not a facet of this
invention.
[0021] With reference to the block diagram in FIG. 2, the Imaging
Unit 2 comprises an Antenna 3; one or more digital Cameras 4; a
Microcontroller or Microprocessor 5; an electrochemical Power
Source 6; and a Wireless Communication Interface 7. Said Wireless
Communication Interface 7 can be integrated with said
Microcontroller 5, e.g., the Freescale MC13224.
[0022] With reference to the block diagram in FIG. 3, the
Communication Unit 1 minimally comprises an Antenna 3; a
Microcontroller or Microprocessor 5; a Power Source 6 such as solar
panels, a connection to an external power source, or an
electrochemical power source; and a Wireless Communication
Interface 7. It may include additional wireless or wired
interfaces.
[0023] In the current embodiment of both the Communication Unit 1
and the Imaging Unit 2, the Microcontroller 5 and Wireless
Communication Interface 7 is realized using a Freescale MC13224;
the Power Source 6 is a lithium-thionyl-chloride battery pack; and
the Antenna 3 is a patch antenna.
[0024] There are multiple variants of the current embodiment of the
Imaging Unit 2. For an Imaging Unit that is used for monitoring
visible wavelengths, the Camera 4 is a Firefly MV from Point Grey
Research whereas for an Imaging Unit 2 that is used for monitoring
wideband thermal infrared wavelengths, the Camera 4 is a
thermoImager TIM 400 from Micro-Epsilon. Additionally, a Camera 4
can be a multispectral imaging system that captures separate images
for each of a plurality of bands of spectral wavelengths. Said
multispectral imaging systems can more accurately detect specific
anomalous conditions such as flames.
[0025] Multispectral methods for flame detection are more reliable
than wideband infrared methods and are well known in the existing
art, but imaging multispectral sensors have not yet been employed
within AST's. Because an imaging multispectral sensor provides
positional information for a detected event, rather than simply an
indication of the occurrence of said event, the current invention
introduces the use of multispectral imaging within an AST.
[0026] The Imaging Unit 2 is designed for long-term battery-powered
operation and it is therefore advantageous to minimize power
consumption. Acquiring a digital image from the Camera 4 requires a
significant amount of power, as does transmitting said image from
the Imaging Unit 2 to the Communication Unit 1. Hereinafter we
further describe the current low-power embodiment of the Imaging
Unit 2.
[0027] To reduce the amount of power consumed by image acquisition,
the image is acquired only when requested by the system operator or
if some other device, such as a gas sensor detects an anomalous
condition and subsequently signals the Imaging Unit 2 using wired
or wireless means. Additionally, the current invention can be used
to acquire the image at scheduled intervals.
[0028] The amount of power consumed by transmitting the image from
the Imaging Unit 2 to the Communication Unit 1 can be reduced by
employing various encoding methods. One class of said encoding
methods compresses the data from each individual image that is
acquired by the Camera 4 using commonly-available algorithms such
as JPEG 2000, which is lossy, or entropy coding, which is lossless.
Since said compressed image comprises fewer bits of information
than an uncompressed image, the power required to transmit the
image is thereby reduced.
[0029] A second class of said encoding methods employs motion-video
encoding, such as MPEG-4 or H-264. Although the frame rate used by
this invention is quite low compared to common video-encoding
applications, motion video encoding is appropriate because the
visual field monitored by the Camera 4 does not often change. When
compared to the said encoding of individual images, motion-video
encoding greatly reduces the amount of data that needs to be
transmitted from the Imaging Unit 2 to the Communication Unit 1,
thereby reducing power consumption.
[0030] The visual field monitored by this invention is essentially
invariant unless the AST is being filled or being emptied.
Therefore, a change in the visual field can be used to indicate a
potentially hazardous anomaly, such as a failed pontoon, a leaking
seal, or a fire. Consequently, said change can be used to trigger
an alarm or an operator notification. Methods for detecting changes
in a visual field are well known in the current art and are not a
facet of this invention.
[0031] A further aspect of this invention is that it can be used to
determine the elevation of the floating roof inside of the AST.
With reference to FIG. 4, the Imaging Unit 2 can be attached to the
Ceiling 9 or Wall 11 of the AST. The location of said Imaging Unit
2 and the location of one or more visible Markers 8, wherein said
Markers are located on the Floating Roof 10, can be determined
during installation. When filling or emptying the AST, the Floating
Roof 10 rises or falls within the AST, and the angle .alpha. will
thereby decrease or increase, respectively. Therefore, the distance
from the Floating Roof 10 to the top of the AST can be determined
by using elementary trigonometry. This aspect of the invention can
be used in the prevention of the overfilling of AST's. Said visible
marker is any physical feature on the AST or any additional marker
or marking that can be discerned using any of the visible or
invisible wavelengths monitored by any Camera 4. By using the
location of a said Marker within an image from a Camera 4, the
elevation of the roof can be manually determined by a human
operator. Alternatively, the location of said Marker within said
image can be automatically determined using known methods from
computer vision, thereby enabling the automated computation of the
elevation of the Floating Roof 10.
[0032] A plurality of Cameras 4 can be integrated into a single
Imaging Unit 2 to provide redundancy, to provide additional
spectral coverage, or for extending the field of view. Any Camera 4
can be mounted on a pan/tilt mechanism to extend its effective
field of view. Any Camera 4 can have a zoom lens for varying its
field of view.
[0033] A plurality of Imaging Units 2 can be deployed to improve
the coverage of the area being monitored or to monitor multiple
portions of the electromagnetic spectrum, such as visual and
infrared. A plurality of Communication Units 1 can be deployed to
provide spatial diversity or frequency diversity for the wireless
signals or to provide redundant communication links for
safety-critical systems. Any Communication Unit 1 or Imaging Unit 2
can employ multiple Antennas 3 for the purpose of antenna diversity
or frequency diversity.
[0034] The acquisition of an image can be performed at regular time
intervals or image acquisition can be triggered by anomalous
conditions that are detected by one or more Sensors 12, such as a
gas sensor, inclinometer, accelerometer, or optical flame
sensor.
[0035] As required for any particular deployment, the communication
system of the Imaging Unit 2 or the Communication Unit 1 can be
configured to act as a communication relay or as part of a
redundant network, such as a mesh network. These capabilities are
well known in the existing art.
[0036] Because the Imaging Unit 2 and the Communication Unit 1 can
have a minimal number of external physical connections, including
the possibility of zero external connections, they can be readily
protected by an environmentally-protective enclosure, thereby
making them suitable for use in harsh environments. The current
embodiment of the Imaging Unit 2 is intended for deployment within
petroleum AST's and meets the ATEX requirements for Intrinsic
Safety, although these are not requirements of the current
invention.
* * * * *