EP2533875A1 - Compressed air supply for the operation of moving bed filters - Google Patents

Compressed air supply for the operation of moving bed filters

Info

Publication number
EP2533875A1
EP2533875A1 EP11742549A EP11742549A EP2533875A1 EP 2533875 A1 EP2533875 A1 EP 2533875A1 EP 11742549 A EP11742549 A EP 11742549A EP 11742549 A EP11742549 A EP 11742549A EP 2533875 A1 EP2533875 A1 EP 2533875A1
Authority
EP
European Patent Office
Prior art keywords
compressor
compressed air
pressure
air
moving bed
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP11742549A
Other languages
German (de)
French (fr)
Other versions
EP2533875A4 (en
Inventor
Hans F. Larsson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nordic Water Products AB
Original Assignee
Nordic Water Products AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nordic Water Products AB filed Critical Nordic Water Products AB
Publication of EP2533875A1 publication Critical patent/EP2533875A1/en
Publication of EP2533875A4 publication Critical patent/EP2533875A4/en
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D24/00—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof
    • B01D24/36—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof with the filter bed fluidised during the filtration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D24/00—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof
    • B01D24/28—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof with the filter bed moving during the filtration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D24/00—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof
    • B01D24/46—Regenerating the filtering material in the filter
    • B01D24/4668—Regenerating the filtering material in the filter by moving the filtering element
    • B01D24/4689—Displacement of the filtering material to a compartment of the filtering device for regeneration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D24/00—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof
    • B01D24/48—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof integrally combined with devices for controlling the filtration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D24/00—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof
    • B01D24/48—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof integrally combined with devices for controlling the filtration
    • B01D24/4884—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof integrally combined with devices for controlling the filtration by pressure measuring
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D37/00—Processes of filtration
    • B01D37/04—Controlling the filtration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D37/00—Processes of filtration
    • B01D37/04—Controlling the filtration
    • B01D37/046—Controlling the filtration by pressure measuring

Definitions

  • the present invention relates generally to a method and a system for the supply of compressed air for operating granular bed filters and/or reactors of the moving bed type and particularly for operating air lift pumps in such filters.
  • Moving bed filters are commonly used for treatment of water and wastewater.
  • the granular media filter bed (hereafter filter bed) of such moving bed filters is kept in a slow motion by a transport device transporting granular filter media from the lower part of the filter bed to the top of the filter bed often via a washer for granular filter media, so-called media washer, in which the granular filter media is washed to remove pollutants that have been separated in the moving bed filter.
  • One or more air lift pumps are normally used as such transport device.
  • the air lift pump is operated with compressed air.
  • an air lift pump is a tube immersed in a liquid, which may contain particles, with the inlet part of the tube at a lower level than outlet part thereof and in which compressed air is introduced close to the inlet part. Since the air/liquid/particle mixture in the air lift pump will have a lower density than the surrounding liquid or liquid particle mixture a pumping action will result.
  • Air lift pumps offer a simple means of transporting liquids containing particles and the operating cost will largely depend on the cost of said compressed air. This cost is dependent on air pressure and air flow e.g. volume per unit of time. Air pressure is the factor that has the greatest influence on the cost of operating an air lift pump.
  • the compressor is normally controlled in such a way that it pumps compressed air into a holding tank for air which feeds air into the filter system.
  • the compressor is operated in on/off mode in such a way that a high pressure level and a low pressure level are set and when the air pressure in the tank has reached the high pressure the compressor is turned off and when the air pressure in the tank reaches the low pressure the compressor starts again. If a mid pressure compressor is used instead of the conventional compressor the system will fail.
  • the pressure of the mid pressure compressor is close to the pressure needed by the air lift pump and therefore it is not possible to use it in the same system as the conventional compressor, since the on/off operation to control the compressor will lead either to too frequent starts and stops that will damage the compressor or the lower pressure set for the start of the compressor will be too low for operating the air lift pump.
  • An object of the present invention is to provide a method and a system of the kind initially mentioned, wherein the drawbacks of prior art are eliminated or at least minimized.
  • An electrical frequency control device is preferably used for the control of the rotational speed of an electrical motor.
  • the rotational speed of a combustion engine is preferably controlled by controlling the fuel/air mixture fed to the engine.
  • the moving bed filter comprises an air lift pump.
  • a controller and a pressure sensor adapted to sense the pressure in the conduit are provided, wherein the controller is adapted to control the speed of the compressor in dependence of the sensed pressure in the conduit.
  • the compressor is preferably a claw compressor.
  • the compressor is devoid of lubrication in the air part.
  • compressed air free from traces of lubricants can be produced for use in sensitive applications, e.g. drinking water production.
  • a heat exchanger is adapted to cool compressed air in the conduit in order to condense the water vapor.
  • the system is less sensitive to condensation of water in the tubes for the compressed air.
  • Fig. 1 illustrates a conventional system according to prior art.
  • Fig. 2 illustrates a system according to the invention.
  • FIG. l shows a conventional system according to prior art with a compressor 1 which will normally be of the piston or screw compressor type.
  • the compressed air in the compressed air line 2 passes a lubricant removal filter 3 for the removal of drops of lubricant which may have been entrained in the compressed air in the compressor.
  • An air holding tank 4 for the compressed air is included in the system and the air pressure is controlled by an on/off control system with a pressure sensor 5 connected to a control box 6 which in turn gives a signal that controls the motor of the compressor in such a way that the compressor is stopped when the air pressure in the holding tank reaches a certain level and starts the motor of the compressor when the air pressure in the holding tank has fallen below a certain predetermined value.
  • the pressure of the compressed air is finally reduced to the operating pressure needed for the transport device(s) of the moving bed filter(s) connected to the system in a pressure reducing device 7, wherein the pressure of the compressed air is reduced from approximately 7 Bars to a pressure of approximately 3-4 Bars and a further pressure reduction takes place in connection with the flow control devices in a pneumatic cabinet 8 used for the subsequent distribution of the compressed air to the transporting device(s) of the moving bed filter(s).
  • Fig. 2 shows the proposed new system, generally designated 1 0, with a mid pressure compressor 1 1 with a motor with its rotational speed controlled by a controller in the form of a control box 14 which receives a signal from a pressure sensor 1 3, which senses the pressure in a conduit in the form of a compressed air line 1 2.
  • the controller keeps the pressure in the compressed air line at close to a predetermined pressure in the range of 1 .2 - 2.0 Bars, preferably approximately 1 .5 Bars.
  • the compressed air is optionally cooled in a heat exchanger 1 5, for instance with water provided through pipe 1 6.
  • the compressed air line is arranged with a slope at least between the heat exchanger and a pneumatic cabinet 1 8 towards a lowest point where a valve 1 9 is used for evacuating condensate from the heat exchanger and the compressed air line.
  • the heat exchanger 15 is arranged so that any condensate formed will be evacuated through the valve 1 9.
  • the compressed air line will be arranged so that any condensate formed will flow to the lowest point of the line and be evacuated through valve 1 9.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
  • Compressor (AREA)

Abstract

A method for supplying compressed air for the operation of moving bed filters by means of a compressor is characterized by controlling the pressure of compressed air from the compressor by controlling the rotational speed of the compressor. A system for supplying compressed air is also provided. By use of the described method and system, substantial energy savings of approximately 50 percent can be achieved.

Description

Compressed air supply for the operation of moving bed filters
Technical field
[0001 ] The present invention relates generally to a method and a system for the supply of compressed air for operating granular bed filters and/or reactors of the moving bed type and particularly for operating air lift pumps in such filters.
Background art
[0002] Moving bed filters are commonly used for treatment of water and wastewater. The granular media filter bed (hereafter filter bed) of such moving bed filters is kept in a slow motion by a transport device transporting granular filter media from the lower part of the filter bed to the top of the filter bed often via a washer for granular filter media, so-called media washer, in which the granular filter media is washed to remove pollutants that have been separated in the moving bed filter.
[0003] Examples of moving bed filters are found in the US patents Nos. US 6,426,005 Bl , US 4, 1 26,546, US 4, 1 97,201 , and US 4,246, 1 02, which are incorporated herein by reference.
[0004] One or more air lift pumps are normally used as such transport device. The air lift pump is operated with compressed air. In principle an air lift pump is a tube immersed in a liquid, which may contain particles, with the inlet part of the tube at a lower level than outlet part thereof and in which compressed air is introduced close to the inlet part. Since the air/liquid/particle mixture in the air lift pump will have a lower density than the surrounding liquid or liquid particle mixture a pumping action will result.
[0005] Air lift pumps offer a simple means of transporting liquids containing particles and the operating cost will largely depend on the cost of said compressed air. This cost is dependent on air pressure and air flow e.g. volume per unit of time. Air pressure is the factor that has the greatest influence on the cost of operating an air lift pump.
[0006] Traditionally compressors giving an air pressure of typically 7 bars and blowers operating at an air pressure of approx. 1 bar have been available. Since the pressure from a blower has not been sufficient for operating air lift pumps in moving bed filters the standard means for such operation has been the traditional compressor. The pressure of the compressed air exiting from such a compressor is too high for direct use for operating an air lift pump in a moving bed filter and the compressed air has therefore been subjected to a pressure reduction before being used in the air lift pump. The practice of first creating a high pressure and then reducing the pressure before using the compressed air leads to unwanted energy losses.
[0007] The reason for this practice is that no suitable compressors offering a pressure between the too high pressure of the traditional compressor and the too low pressure of the blower have been available.
[0008] This has been changed with the advent of the mid pressure compressor (for instance claw compressor), which can produce compressed air of for instance 2.2 bars, i.e. lower than the conventional compressor but higher than the blower. The pressure of the compressed air delivered by a mid pressure compressor would appear suitable for operation of moving bed filters.
[0009] However, surprisingly enough replacing the conventional compressor with such a mid pressure compressor for the operation of moving bed filters leads to problems. For instance in the moving bed filter system using a conventional compressor, the compressor is normally controlled in such a way that it pumps compressed air into a holding tank for air which feeds air into the filter system. The compressor is operated in on/off mode in such a way that a high pressure level and a low pressure level are set and when the air pressure in the tank has reached the high pressure the compressor is turned off and when the air pressure in the tank reaches the low pressure the compressor starts again. If a mid pressure compressor is used instead of the conventional compressor the system will fail. The pressure of the mid pressure compressor is close to the pressure needed by the air lift pump and therefore it is not possible to use it in the same system as the conventional compressor, since the on/off operation to control the compressor will lead either to too frequent starts and stops that will damage the compressor or the lower pressure set for the start of the compressor will be too low for operating the air lift pump.
[0010] The use of a mid pressure compressor will also lead to a system that is highly sensitive to condensation of water in the tubes for the compressed air. The condensed water together with the low pressure will render the system inoperable.
Summary of invention
[001 1 ] An object of the present invention is to provide a method and a system of the kind initially mentioned, wherein the drawbacks of prior art are eliminated or at least minimized.
[001 2] According to a first aspect of the invention, there is provided a method as defined by the features of the characterizing portion of appended claim 1 .
[001 3] According to a second aspect of the invention, there is provided a system as defined by the features of the characterizing portion of appended claim 7.
[0014] By use of the described method and system, substantial energy savings of approximately 50 percent can be achieved.
[001 5] An electrical frequency control device is preferably used for the control of the rotational speed of an electrical motor. [001 6] The rotational speed of a combustion engine is preferably controlled by controlling the fuel/air mixture fed to the engine.
[001 7] In a preferred embodiment, the moving bed filter comprises an air lift pump.
[001 8] In a preferred embodiment, a controller and a pressure sensor adapted to sense the pressure in the conduit are provided, wherein the controller is adapted to control the speed of the compressor in dependence of the sensed pressure in the conduit.
[001 9] The compressor is preferably a claw compressor.
[0020] In a preferred embodiment, the compressor is devoid of lubrication in the air part. Thereby, compressed air free from traces of lubricants can be produced for use in sensitive applications, e.g. drinking water production.
[0021 ] In a preferred embodiment, a heat exchanger is adapted to cool compressed air in the conduit in order to condense the water vapor. Thereby, the system is less sensitive to condensation of water in the tubes for the compressed air.
Brief description of drawings
[0022] The invention is now described, by way of example, with reference to the accompanying drawings, in which:
[0023] Fig. 1 illustrates a conventional system according to prior art. [0024] Fig. 2 illustrates a system according to the invention.
Description of embodiments
[0025] In the following, a detailed description of a method and a system for supply of compressed air will be given. [0026] Fig. l shows a conventional system according to prior art with a compressor 1 which will normally be of the piston or screw compressor type. The compressed air in the compressed air line 2 passes a lubricant removal filter 3 for the removal of drops of lubricant which may have been entrained in the compressed air in the compressor. An air holding tank 4 for the compressed air is included in the system and the air pressure is controlled by an on/off control system with a pressure sensor 5 connected to a control box 6 which in turn gives a signal that controls the motor of the compressor in such a way that the compressor is stopped when the air pressure in the holding tank reaches a certain level and starts the motor of the compressor when the air pressure in the holding tank has fallen below a certain predetermined value. The pressure of the compressed air is finally reduced to the operating pressure needed for the transport device(s) of the moving bed filter(s) connected to the system in a pressure reducing device 7, wherein the pressure of the compressed air is reduced from approximately 7 Bars to a pressure of approximately 3-4 Bars and a further pressure reduction takes place in connection with the flow control devices in a pneumatic cabinet 8 used for the subsequent distribution of the compressed air to the transporting device(s) of the moving bed filter(s).
[0027] Fig. 2 shows the proposed new system, generally designated 1 0, with a mid pressure compressor 1 1 with a motor with its rotational speed controlled by a controller in the form of a control box 14 which receives a signal from a pressure sensor 1 3, which senses the pressure in a conduit in the form of a compressed air line 1 2. The controller keeps the pressure in the compressed air line at close to a predetermined pressure in the range of 1 .2 - 2.0 Bars, preferably approximately 1 .5 Bars. The compressed air is optionally cooled in a heat exchanger 1 5, for instance with water provided through pipe 1 6. The compressed air line is arranged with a slope at least between the heat exchanger and a pneumatic cabinet 1 8 towards a lowest point where a valve 1 9 is used for evacuating condensate from the heat exchanger and the compressed air line. The heat exchanger 15 is arranged so that any condensate formed will be evacuated through the valve 1 9. Likewise the compressed air line will be arranged so that any condensate formed will flow to the lowest point of the line and be evacuated through valve 1 9.
[0028] The compressed air needed for the transport device(s) of the moving bed filter(s) connected to the system is distributed to such transport device(s) via flow control devices in the pneumatic cabinet 1 8 wherein also the pressure of the compressed air is finally adjusted.
[0029] A preferred embodiment of a method and a system for supplying compressed air for the operation of moving bed filters according to the invention has been described. It will be realized that this embodiment can be modified without departing from the inventive idea as defined in the appended claims.

Claims

1 . A method for supplying compressed air for the operation of moving bed filters by means of a compressor, c h a r a c t e r i z e d b y controlling the pressure of compressed air from the compressor by controlling the rotational speed of the compressor.
2. The method according to claim 1 , comprising using an electrical frequency control device for the control of the rotational speed of an electrical motor.
3. The method according to claim 1 , comprising controlling the rotational speed of a combustion engine by controlling the fuel/air mixture fed to the engine.
4. The method according to any of claims 1 -3, comprising condensing water vapor in the compressed air in an air supply system downstream of the compressor and discharging the condensed water.
5. The method according to any of claims 1 -4, comprising cooling the compressed air in order to condense the water vapor.
6. The method according to any of claims 1 -5, wherein a claw compressor is used.
7. The method according to any of claims 1 -6, wherein the pressure of compressed air from the compressor is kept in the range of 1 .2 - 2.0 Bars
8. A system for supplying compressed air for the operation of a moving bed filter, the system comprising: a compressor (1 1 ), a conduit (1 2) interconnecting the compressor and the moving bed filter, c h a r a c te r i z e d i n t h a t the compressor is a variable speed compressor.
9. The system according to claim 8, wherein the moving bed filter comprises an air lift pump.
1 0. The system according to claim 8 or 9, comprising a controller (14) and a pressure sensor (1 3) adapted to sense the pressure in the conduit (1 2), wherein the controller is adapted to control the speed of the compressor in dependence of the sensed pressure in the conduit.
1 1 . The system according to any of claims 8-1 0, wherein the compressor is a claw compressor.
1 2. The system according to any of claims 8-1 1 , wherein the compressor is devoid of lubrication in the air part.
1 3. The system according to any of claims 8-1 2, comprising a heat exchanger (15) adapted to cool compressed air in the conduit (1 2).
14. The system according to any of claims 8-1 3, wherein the compressor is adapted to keep the pressure in the conduit at close to a predetermined pressure in the range of 1 .2 - 2.0 Bars.
EP11742549.6A 2010-02-12 2011-02-11 Compressed air supply for the operation of moving bed filters Ceased EP2533875A4 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US30383210P 2010-02-12 2010-02-12
SE1050143A SE534558C2 (en) 2010-02-12 2010-02-12 Methods and systems for supplying compressed air for operation of filters with variable bed
PCT/SE2011/000024 WO2011099917A1 (en) 2010-02-12 2011-02-11 Compressed air supply for the operation of moving bed filters

Publications (2)

Publication Number Publication Date
EP2533875A1 true EP2533875A1 (en) 2012-12-19
EP2533875A4 EP2533875A4 (en) 2013-07-17

Family

ID=43555043

Family Applications (1)

Application Number Title Priority Date Filing Date
EP11742549.6A Ceased EP2533875A4 (en) 2010-02-12 2011-02-11 Compressed air supply for the operation of moving bed filters

Country Status (5)

Country Link
US (1) US20130011274A1 (en)
EP (1) EP2533875A4 (en)
CN (2) CN201739768U (en)
SE (1) SE534558C2 (en)
WO (1) WO2011099917A1 (en)

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US7897040B2 (en) 2007-09-19 2011-03-01 Blue Water Technologies, Inc. Washbox
US10702805B2 (en) 2007-09-19 2020-07-07 Nexom (Us), Inc. Washbox
WO2012116404A1 (en) * 2011-03-01 2012-09-07 Nepsus Technologies Pty Ltd Influent treatment process
US20170080360A1 (en) * 2014-05-21 2017-03-23 Nexom (U.S.), Inc. Energy reduction and monitoring control system for backwashing media systems
CN104950933B (en) * 2015-05-29 2020-07-14 湖北绿色家园材料技术股份有限公司 Stabilizer for system steam pressure
CN113309186B (en) * 2021-05-31 2022-04-19 北控水务(中国)投资有限公司 Water purification plant clean water pool water level management energy-saving control method and system

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JPH09158846A (en) * 1995-12-05 1997-06-17 Mitsubishi Heavy Ind Ltd Air compressing unit
US5730886A (en) * 1994-12-13 1998-03-24 Ashbrook-Simon-Hartley Corporation Continuous self-cleaning filtration unit
CN201306269Y (en) * 2008-09-24 2009-09-09 东营市天信纺织有限公司 Pressure constant device controlled by frequency converter

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GB2475245A (en) * 2009-11-10 2011-05-18 Lothar Peter Schmitz Compressor assembly with planetary gear means

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US5730886A (en) * 1994-12-13 1998-03-24 Ashbrook-Simon-Hartley Corporation Continuous self-cleaning filtration unit
JPH09158846A (en) * 1995-12-05 1997-06-17 Mitsubishi Heavy Ind Ltd Air compressing unit
CN201306269Y (en) * 2008-09-24 2009-09-09 东营市天信纺织有限公司 Pressure constant device controlled by frequency converter

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Title
See also references of WO2011099917A1 *

Also Published As

Publication number Publication date
US20130011274A1 (en) 2013-01-10
CN102781536A (en) 2012-11-14
SE1050143A1 (en) 2011-08-13
EP2533875A4 (en) 2013-07-17
SE534558C2 (en) 2011-10-04
CN201739768U (en) 2011-02-09
WO2011099917A1 (en) 2011-08-18

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