WO2001029523A1 - Apparatus for measuring the level in a container - Google Patents
Apparatus for measuring the level in a container Download PDFInfo
- Publication number
- WO2001029523A1 WO2001029523A1 PCT/SE2000/001806 SE0001806W WO0129523A1 WO 2001029523 A1 WO2001029523 A1 WO 2001029523A1 SE 0001806 W SE0001806 W SE 0001806W WO 0129523 A1 WO0129523 A1 WO 0129523A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- tank
- absorber
- base
- microwaves
- liquid
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/12—Supports; Mounting means
- H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
- H01Q1/225—Supports; Mounting means by structural association with other equipment or articles used in level-measurement devices, e.g. for level gauge measurement
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/28—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
- G01F23/284—Electromagnetic waves
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
- H01Q13/06—Waveguide mouths
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
- H01Q17/001—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems for modifying the directional characteristic of an aerial
Definitions
- the invention relates to an absorber for microwaves that is fitted to the base of a tank that is devised for storing a liquid, such as liquid gas.
- the absorber is positioned below the opening of a pipe, which is used as a waveguide for microwaves from a radar, which measures the distance to the surface of the liquid in the tank.
- the purpose of the absorber is to prevent the base of the tank generating an echo that can disturb the wave reflected by the liquid surface.
- the use of radar mounted on the roof of a tank is a common technique today for determining the level of the surface of material, in the form of a liquid or a solid grain-shaped material, stored in a tank.
- a vertically mounted pipe is used as a waveguide for the microwaves sent from the radar downwards to the surface of the material in the tank, where the microwaves are reflected by the surface of the material as an echo, and are sent back to a receiver in the radar.
- the distance to the surface may be determined.
- the said technique is employed in tanks of various types, for example in tanks and cisterns used to store oil or products refined from oil.
- tanks on ships for storage of liquid gas are normally designed as large rectangular blocks, for which the area of the base can be very big, as great as the size of a football pitch with a height of up to 30 m.
- the walls of the tank are made of a thin metal membrane, approximately 1mm thick.
- the membrane is supported in turn by a wooden structure, which makes the whole construction light in weight. Since the area of the base of a tank of this type is large, it is of utmost importance that the liquid level, i.e. the liquid gas, can be read with a high degree of accuracy.
- the large area implies that small changes in the liquid level correspond to relatively large changes in the volume of liquid. If radar is used for measuring, with a pipe acting as a waveguide, the measurement carried out at higher levels may be taken in a controlled fashion and will produce good measurement results.
- the pipe acting as a waveguide must have an opening at its end above the base of the tank, because the pipe is subjected to large changes in length caused by the large variations in temperature that a tank periodically filled with liquid gas displays. Consequently, a measurement of the liquid level close to the base of the tank will be performed in free space if it is carried out by a radar level measuring apparatus.
- an apparatus and a method are presented here for determining the liquid level in a tank by means of a radar level-measuring apparatus, which transmits microwaves downwards to the surface of the liquid through a waveguide, in the form of a vertically arranged pipe, which is open close to the base of the tank, and which after reflection of the microwaves from the liquid surface receives the microwaves for determining the level of the liquid surface, where an absorber for microwaves is placed at the base of the tank below the opening of the pipe to absorb the greater part of the microwave energy that is incident on the base of the tank.
- the apparatus and method are, in particular, intended to be used in tanks with liquid which is not of a clogging character. It is primarily intended for use in tanks for storage of liquid gas. If the absorber is to fulfil its function for a long period of time, the stored material in the tank cannot be of such character that sticky material builds up on the surface of the absorber.
- the absorber is made of a material that is preferably composed of a flouro- polymer resin, such as PolyTetraFlouroEthylen (PTFE). This material is known, for example, under the trade name TEFLON®. The material has, in addition, a component of carbon powder, which imparts the microwaves- absorbing properties.
- PTFE PolyTetraFlouroEthylen
- the absorber is modelled in the form of spikes, with the tips of the spikes facing the incident microwaves.
- the absorber is preferably designed as a number of closely arranged pyramids on a connected plate of the absorbing material. This type of design is also present in devices for absorption of sound in echo-free rooms.
- the reason for using spikes in the shape of pyramids is that the microwaves on contact with the absorber hits a successively increasing area of absorption material, whereby the microwaves' transition from propagation in air (or other gas) to propagation in the absorption material is mild, so that the microwaves can be absorbed effectively without undesirable reflection at the base of the tank.
- the absorption of microwaves happens with increasing effectiveness with depth in the absorber, since its cross-sectional area increases with depth
- One advantage of the absorber according to the invention is that it permits measurement of the liquid level with a high degree of accuracy using a radar level-measuring device, even close to the base, in tanks with liquid gas. Another advantage is that it is possible to measure the liquid level right down to the height defined as " empty tank " .
- a further advantage is that the proposed absorption material can be inserted into tanks of the aforementioned type without risk for introduction of unsuitable matter or material in the tank.
- Figure 1 shows schematically a sectional view of a cut-away tank, in which a liquid is stored and where an absorber according to the invention is fitted to the base of the tank below a waveguide, which sends microwaves towards the bottom.
- Figure 2a shows the aforementioned absorber in a plan view from above.
- Figure 2b shows a sectional view of a version of the aforementioned absorber where each pyramidal part stands on a separate rectangular prism, which are linked together to make a plate.
- a liquid gas 1 is stored in a tank 2, where the base of the tank 3 is composed of a metal membrane.
- the walls 4 of the tank are partly illustrated in the drawing.
- a vertical waveguide 5 in the form of a pipe is arranged in the roof of the tank 2, or running through the roof of the tank 2, a vertical waveguide 5 in the form of a pipe is arranged.
- the waveguide is terminated a little above the base 3 of the tank, whereby the waveguide is open downwards.
- a microwave radar 6 is fitted in the upper part of the waveguide 5. As already mentioned, this radar 6 transmits a microwave signal through the waveguide 5 to be reflected by the liquid surface 7, which means that a reflected microwave signal can be received by the radar 6.
- the level of the liquid surface 7 in the tank can be determined in a known way.
- the level of the liquid surface is low; i.e. it is shown a little below the opening in the waveguide 5.
- an absorber 8 has, in accordance with the aspect of the invention, been fitted to the base 3 of the tank 2, below the opening in the waveguide 5.
- the duty of the absorber is to absorb the greater part of the microwave energy that, from the waveguide 5, is incident on the liquid surface 7, and that is not reflected by this surface, thereby preventing an echo; i.e. a reflected wave created at the base 3 and sent to the receiver in the radar 6.
- the absorber 8 It is the object of the absorber 8 to absorb the greater part of the microwave energy incident on the base 3.
- the absorber is composed of material that absorbs microwave energy to a high degree.
- a plastic material in the form of PTFE has been chosen in the example.
- the material with the TEFLON trademark is used, with a component of carbon powder, a material that has good absorption capacity with respect to microwaves for the wavelength in question.
- the concentration of carbon powder is 1%. If the microwaves are incident on a plane surface comprised of the said effective absorption material, there is still a risk that a reflected wave will arise at the surface of the absorber.
- the absorber is constructed in such a way that it has increasing cross-sectional area in the forward movement direction of the microwaves.
- the absorber 8 is constructed as closely arranged standing pyramids 9.
- the pyramids are suitably attached to a shared_plate 10 that holds the absorber together, where the basal surfaces of the pyramids rest on the shared plate.
- the plate 10 may be glued to the base 3 of the tank 2.
- the basal surfaces of each individual pyramid 9 can stand on a rectangular block 11, after which these ratblock 11 are connected to each other, for example by gluing, and fitted to the base in a similar way.
- the absorber is fixed between a metal plate welded to the base of the tank, and a frame that frames the absorber and which is secured by screws to the metal plate.
- the choice of material for the absorber was, as mentioned above, a PTFE material. This is not essential, since other material with the desired parameters can be used. According to the invention, the requirement for use is that the material has a relative dielectric constant that exceeds 1.8. The material, furthermore, should have the ability to incorporate up to 4% carbon without it being friable at the low temperatures, down to c. -165 °C, which can occur in tanks with liquid gas.
- the height of the absorber is naturally adapted to the length of the microwave used.
- the wavelength as in the example of the embodiment, is 3 cm in free space
- the height of the pyramids is 30 mm and the thickness of the plate
- the embodiment can be varied in many ways.
- the spikes of the absorber i.e. the pyramids referred to above, can be replaced by other geometric shapes.
- the material in the absorber can be varied in multiple ways, the requirement being that the material should absorb microwave energy, and have a composition that be accepted in a tank milieu.
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Thermal Sciences (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)
- Filling Or Discharging Of Gas Storage Vessels (AREA)
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2001532067A JP4499972B2 (en) | 1999-10-21 | 2000-09-18 | Device for measuring the level in a container |
KR1020027004871A KR20020047241A (en) | 1999-10-21 | 2000-09-18 | Apparatus for measuring the level in a container |
EP00966631A EP1242794B1 (en) | 1999-10-21 | 2000-09-18 | Apparatus for measuring the level in a container |
AU76949/00A AU7694900A (en) | 1999-10-21 | 2000-09-18 | Apparatus for measuring the level in a container |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE9903855A SE9903855L (en) | 1999-10-21 | 1999-10-21 | Device for level measurement in tanks |
SE9903855-6 | 1999-10-21 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2001029523A1 true WO2001029523A1 (en) | 2001-04-26 |
Family
ID=20417488
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/SE2000/001806 WO2001029523A1 (en) | 1999-10-21 | 2000-09-18 | Apparatus for measuring the level in a container |
Country Status (7)
Country | Link |
---|---|
EP (1) | EP1242794B1 (en) |
JP (1) | JP4499972B2 (en) |
KR (2) | KR20020047241A (en) |
CN (1) | CN1160548C (en) |
AU (1) | AU7694900A (en) |
SE (1) | SE9903855L (en) |
WO (1) | WO2001029523A1 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2004068081A1 (en) * | 2003-01-29 | 2004-08-12 | Saab Rosemount Tank Radar Ab | Bottom reflector for a radar-based level gauge |
WO2005031284A2 (en) * | 2003-09-23 | 2005-04-07 | Endress+Hauser Gmbh+Co. Kg | Arrangement for measuring the filling level in a tank equipped with a sounding pipe |
WO2007037696A1 (en) * | 2005-09-27 | 2007-04-05 | Kongsberg Maritime As | Sheltering device for radar type liquid level measuring apparatus |
US7532155B2 (en) | 2006-04-10 | 2009-05-12 | Rosemount Tank Radar Ab | Radar level gauging system |
US7541969B2 (en) | 2007-05-31 | 2009-06-02 | Rosemount Tank Radar Ab | Radar level gauging system for use at sea |
Families Citing this family (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN101825487B (en) * | 2005-09-27 | 2012-08-15 | 康斯伯格马里蒂姆公司 | Sheltering device for radar type liquid level measuring apparatus |
NO331262B1 (en) * | 2010-04-12 | 2011-11-14 | Kongsberg Maritime As | Method and apparatus for measuring the density of a liquid |
US8350752B2 (en) | 2010-07-09 | 2013-01-08 | Rosemount Tank Radar Ab | Radar level gauge system with bottom reflector and bottom reflector |
CN102343969B (en) * | 2011-07-20 | 2013-10-09 | 中国船舶重工集团公司第七○二研究所 | Liquid tank without free liquid level |
KR200468200Y1 (en) | 2011-11-16 | 2013-07-30 | 삼성중공업 주식회사 | Apparatus for liquid level measurement of Radar-type |
US9212942B2 (en) * | 2012-07-04 | 2015-12-15 | Vega Grieshaber Kg | Waveguide coupling, high-frequency module, fill-level radar and use |
CN104843357B (en) * | 2014-02-17 | 2017-02-15 | 五冶集团上海有限公司 | Tank of benzene hydrogenation engineering and manufacturing and mounting method thereof |
CN106903481A (en) * | 2015-12-22 | 2017-06-30 | 五冶集团上海有限公司 | The method for prefabricating of large-size stainless steel groove tank base plate under hot environment |
US20170302001A1 (en) | 2016-04-19 | 2017-10-19 | Rosemount Tank Radar Ab | Floating roof target plate |
US10677635B2 (en) * | 2017-10-31 | 2020-06-09 | Rosemount Tank Radar Ab | Dielectric filling member with microwave absorbing element |
RU2687896C1 (en) * | 2018-08-02 | 2019-05-16 | Сергей Александрович Терехин | Device for absorption of secondary radiation in test bench of level gauges calibration |
CN110051285B (en) * | 2019-04-18 | 2021-12-24 | 云鲸智能科技(东莞)有限公司 | Detection method, device and storage medium |
CN113418580A (en) * | 2021-05-21 | 2021-09-21 | 杭州海芯达科技有限公司 | Boiler level gauge based on ultrasonic ranging |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2464006A (en) * | 1944-04-28 | 1949-03-08 | Philco Corp | Radio wave absorption device |
DE19510484A1 (en) * | 1995-03-27 | 1996-10-02 | Krohne Messtechnik Kg | Level meter for medium in container working according to radar principle |
SE504020C2 (en) * | 1994-03-11 | 1996-10-21 | Kockum Sonics Ab | Radar pulse depth measuring method for liquid in vessel e.g. hydrocarbon |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS57153216A (en) * | 1981-03-18 | 1982-09-21 | Hitachi Ltd | Magnetic rotary sensor |
JPS61108921A (en) * | 1984-11-01 | 1986-05-27 | Mitsubishi Electric Corp | Microwave flow meter |
-
1999
- 1999-10-21 SE SE9903855A patent/SE9903855L/en not_active IP Right Cessation
-
2000
- 2000-09-18 CN CNB008141746A patent/CN1160548C/en not_active Expired - Lifetime
- 2000-09-18 KR KR1020027004871A patent/KR20020047241A/en not_active Application Discontinuation
- 2000-09-18 WO PCT/SE2000/001806 patent/WO2001029523A1/en active Application Filing
- 2000-09-18 JP JP2001532067A patent/JP4499972B2/en not_active Expired - Fee Related
- 2000-09-18 EP EP00966631A patent/EP1242794B1/en not_active Expired - Lifetime
- 2000-09-18 KR KR1020067017228A patent/KR100903658B1/en active IP Right Grant
- 2000-09-18 AU AU76949/00A patent/AU7694900A/en not_active Abandoned
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2464006A (en) * | 1944-04-28 | 1949-03-08 | Philco Corp | Radio wave absorption device |
SE504020C2 (en) * | 1994-03-11 | 1996-10-21 | Kockum Sonics Ab | Radar pulse depth measuring method for liquid in vessel e.g. hydrocarbon |
DE19510484A1 (en) * | 1995-03-27 | 1996-10-02 | Krohne Messtechnik Kg | Level meter for medium in container working according to radar principle |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2004068081A1 (en) * | 2003-01-29 | 2004-08-12 | Saab Rosemount Tank Radar Ab | Bottom reflector for a radar-based level gauge |
WO2005031284A2 (en) * | 2003-09-23 | 2005-04-07 | Endress+Hauser Gmbh+Co. Kg | Arrangement for measuring the filling level in a tank equipped with a sounding pipe |
WO2005031284A3 (en) * | 2003-09-23 | 2005-06-23 | Endress & Hauser Gmbh & Co Kg | Arrangement for measuring the filling level in a tank equipped with a sounding pipe |
WO2007037696A1 (en) * | 2005-09-27 | 2007-04-05 | Kongsberg Maritime As | Sheltering device for radar type liquid level measuring apparatus |
US7532155B2 (en) | 2006-04-10 | 2009-05-12 | Rosemount Tank Radar Ab | Radar level gauging system |
US7541969B2 (en) | 2007-05-31 | 2009-06-02 | Rosemount Tank Radar Ab | Radar level gauging system for use at sea |
Also Published As
Publication number | Publication date |
---|---|
JP2003512614A (en) | 2003-04-02 |
AU7694900A (en) | 2001-04-30 |
CN1378640A (en) | 2002-11-06 |
CN1160548C (en) | 2004-08-04 |
EP1242794A1 (en) | 2002-09-25 |
KR20060117360A (en) | 2006-11-16 |
JP4499972B2 (en) | 2010-07-14 |
SE513461C2 (en) | 2000-09-18 |
EP1242794B1 (en) | 2009-04-08 |
KR100903658B1 (en) | 2009-06-18 |
KR20020047241A (en) | 2002-06-21 |
SE9903855D0 (en) | 1999-10-21 |
SE9903855L (en) | 2000-09-18 |
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