EP2917155A2 - Saturation limited feeder for chemical additions - Google Patents
Saturation limited feeder for chemical additionsInfo
- Publication number
- EP2917155A2 EP2917155A2 EP13853956.4A EP13853956A EP2917155A2 EP 2917155 A2 EP2917155 A2 EP 2917155A2 EP 13853956 A EP13853956 A EP 13853956A EP 2917155 A2 EP2917155 A2 EP 2917155A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- chemical
- liquid
- container
- saturated
- water
- 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.)
- Withdrawn
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/68—Treatment of water, waste water, or sewage by addition of specified substances, e.g. trace elements, for ameliorating potable water
- C02F1/685—Devices for dosing the additives
- C02F1/688—Devices in which the water progressively dissolves a solid compound
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/50—Treatment of water, waste water, or sewage by addition or application of a germicide or by oligodynamic treatment
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/02—Non-contaminated water, e.g. for industrial water supply
- C02F2103/023—Water in cooling circuits
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/005—Processes using a programmable logic controller [PLC]
- C02F2209/006—Processes using a programmable logic controller [PLC] comprising a software program or a logic diagram
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/04—Oxidation reduction potential [ORP]
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/44—Time
Definitions
- the present invention relates to a system for additions of solid chemicals to liquid systems. More particularly, the present invention is directed to a method and apparatus to slug feed solid chemicals into a system.
- Evaporative cooling equipment dissipates heat by evaporation of some of the recirculated cooling water.
- the water in the recirculated-loop is warm and open to the atmosphere.
- One issue with such systems is the tendency for biological growth to occur. This biological growth can impede heat transfer, aggravate corrosion, and may even harbor human pathogens.
- liquid biocides are often pumped into the recirculating loop.
- the present invention relates to a saturation limited feed system for automated or semi-automated additions of solid chemicals to liquid systems. More particularly, the present invention is directed to a method and apparatus to slug-feed solid chemicals into a circulating liquid system.
- the method and apparatus can be used to add any suitable chemical to any suitable system, but the invention is described specifically for the addition of a biocide to the recirculating water of a cooling system.
- the present invention does not use kinetics to control the dissolution of the solid chemical; instead the invention relies on the solubility of the solid chemical in the liquid.
- the solubility limit of a chemical in a solution is defined as the maximum amount of chemical that can be dissolved in that solution at a specific temperature.
- a basket constructed from a plastic mesh is located inside a water impermeable container.
- the water impermeable container will be referred to herein alternatively as slug pipe, a holding tube, or as PVC pipe, though any water impermeable container made from an appropriate plastic, metal, fiberglass, or other material will be suitable.
- the container need to be in the shape of a pipe or tube as any shape container will also be suitable.
- the basket mesh will be referred to as a basket fabricated from some suitable plastic such as polypropylene; however, any appropriate material can be used for the basket.
- the invention functions by loading an excess of chemical into the mesh basket and placing the mesh basket into the PVC pipe.
- the PVC pipe is filled with a specific volume of water and the chemical and water are allowed to stay in contact for a period of time. During this time, the chemical dissolves until it approaches its solubility limit. At this point, no additional chemical will dissolve into the water.
- a valve or series of valves is opened and water flows through the slug pipe displacing the chemical-saturated water with unsaturated water. The flush typical lasts for only a few minutes; little additional chemical is dissolved by the small amount of excess flush water.
- the dosage of the chemical is accordingly determined by the volume of the water in the slug pipe times the solubility of the chemical.
- the dosage of the solid chemical is controlled by the chemical's solubility equilibrium rather than the kinetics of dissolution as used in the prior art.
- the control mechanism for opening the valve for biocide addition to a cooling tower is preferably a timer-controlled valve; however, other methods to control the chemical release are known, and are also considered part of the invention.
- a step in a program for example in a cleaning cycle for a laundry, where chemicals are dosed at a particular stage of the process.
- valve could be activated whenever an ORP value falls below a pre-set value.
- Another advantage of the present invention is its ease of scale-up from adding a small amount of chemicals to adding a very large amount of chemicals.
- the quantity of chemicals contained in a flush is simply the solubility of the chemical times the volume of the slug pipe. If a small amount of chemical is needed, the invention can be configured to place only a small volume of water in contact with the chemical. If a larger quantity of chemical per dose is needed then the only required change is that a larger volume of water is maintained in contact with the chemical, i.e., a larger slug pipe is used.
- the varying quantity of chemical dosing can be achieved by configuring the system with a large volume slug pipe, and using inert objects to displace water in the container, using various liquid heights in a container by varying the height of the output connection, or by other methods and systems known to persons having ordinary skill in the art.
- Figure 1 is a cut-away representation of an embodiment of the invention
- Figure 2 is a side perspective illustration of a mesh basket according to an embodiment of the invention.
- Figure 3 is a representation of the embodiment shown in Figure 1 , showing one embodiment of water flow and valve settings during discharge of chemical to the system.
- Figure 4 is a representation of the embodiment shown in Figure 1 , showing one embodiment of water flow and valve settings for draining the holding tube after the tube has fed a chemical slug to the system.
- Figure 5 is a side cutaway representation of an embodiment of the invention, showing chemical in the basket.
- Figure 6 is a side cutaway representation of an embodiment of the invention showing the use of inert material to reduce the volume of water in the holding tube.
- Figure 7 is a side cutaway representation of another embodiment of the invention.
- FIG. 1 illustrates the general layout of a slug feed loop 10 according to one embodiment of the invention.
- Section of pipe 1 (also referred to herein as slug pipe or holding tube) is configured to receive removable basket 3.
- the section of pipe is construction of PVC, and the basket is wire or plastic mesh.
- Slug pipe 1 is fitted with a removable top 5 to allow addition of chemical to the slug pipe and/or removal of the basket 3.
- Slug pipe 1 is connected to a circulating water system 2 by sections of pipe 7, 9.
- Sections of pipe 7, 9 may be fitted with isolation valves, 11, 13, and one or more of timer actuating valve 15, flow meter 17, flow adjusting valve 19 and air vent valve 21.
- Slug pipe 1 may also be fitted with drain section 23, including drain valve 25.
- FIG. 2 shows a close-up of basket 3, optionally fitted with centering ring 27 and optional funnel 29.
- Basket 3 is also optionally fitted with a wide base 31, comprising a disk or ring, the diameter of which is slightly less than the inside diameter of the slug pipe 1.
- Centering ring 27 is configured to prevent the basket from tipping while inside the slug pipe 1.
- Optional funnel 29 may be permanent, semi-permanent, or removable, and is configured to allow easy addition of chemical.
- Figure 3 illustrates one embodiment of the invention in which chemical is slug fed to the circulating water system 2 with isolation valves 11, 13, open, timer actuating valve 15 open, flow adjusting valve 19 open, and air vent valve 21 closed and drain valve 25 closed.
- water flow through the slug feed loop occurs by actuation/opening of the timer-controlled valve 15, and the flow rate is preset by the adjusting valve 19 with feedback from the flow meter 17.
- the timer-controlled valve When the timer-controlled valve is opened, water moves through the slug feed loop displacing the chemically saturated water in the slug pipe 1. After a suitable time, usually one to five minutes, and in any event whatever time is considered sufficient to fully flush the chemically saturated water from the slug pipe, the timer-controlled valve closes.
- FIG. 4 illustrates an embodiment of the invention according to which the slug pipe 1 may be drained or partially drained to allow addition of solid chemical to the basket 3.
- the system may be purged shortly before chemicals are added to the system.
- isolation valves 11, 13 are closed and drain valve 25 and air valve 21 are opened, and the slug pipe 1 will quickly drain.
- removable top 5 may be removed and chemicals may be added to the basket 3.
- the form of the chemical used in the basket/slug pipe can be any type of solid, including granulated, powdered or tablets.
- the form of the chemical is important for ease of loading, but does not dramatically affect the function of the invention.
- the amount of solid chemical in the basket must equal or exceed the maximum amount of chemical that will dissolve in a volume of water equal to the internal volume of the slug pipe, minus the volume of the solid chemical in the slug pipe.
- the invention provides a simple method for adjusting the amount of chemical added in a single slug feed.
- volumes of inert material 33 may be added to the slug pipe 1, inside, beneath, or around the basket 3, in order to reduce the volume of water in the slug pipe 1.
- the volume of liquid in the slug pipe may be reduced for chemicals with a higher solubility limit or a lower dosage amount, without having to reduce the size of the slug pipe.
- the slug pipe is configured to hold a volume of water that will dissolve the desired the amount of a chemical having the lowest solubility limit among the various chemicals that might be added to the system.
- the inert materials may be added to the slug pipe to reduce the volume of water in the pipe so that the appropriate amount of chemical for a single slug may be dissolved.
- FIG. 7 shows an alternative embodiment of a slug feed system 20 according to the invention in which the chemical slug is gravity fed to the circulating water system 2.
- actuator valve 101 when a slug of chemical is to be added to the circulating water system 2, actuator valve 101 is opened, and air-release/vacuum-breaker valve 103 opens, allowing the volume of water in the slug pipe 1 to flush into the circulating water system 2 under action of gravity.
- actuator valve 101 is closed, and refilling valve 105 is opened to refill the slug pipe with a new volume of water.
- the system may be configured to receive the new volume of water from the circulating water system 2, from a different source of water (e.g., a tank, a well), or from a combination thereof.
- a different source of water e.g., a tank, a well
- the dosing of the saturated liquid in the slug pipe into the circulating water system, and the refilling of the slug pipe with unsaturated liquid are two separate operations.
- DBNPA is a non-oxidizing biocide that is commonly used to control microbiological activity in cooling towers.
- DBNPA has a solubility limit in room-temperature water of about 1.0%.
- DBNPA is preferably slug-fed at a dosage of about 10 ppm based on the water volume of the system.
- a typical treatment program consists of dosing DBNPA 3 times per week (13 times per month). On a monthly basis the chemical feed system is inspected and the chemicals in the feeder are recharged.
- a water system having a volume of 1000 gallons requires a dose of 37.8 grams of DBNPA to be treated at the 10 ppm level. This treatment is accomplished by slug feeding 3.8 liters of water saturated ( 1.0%) with DBNPA. This dosage is administered as a slug feed over the course of a few minutes.
- a 4" diameter pipe holds approximately 200 ml of water per inch, thus a water- filled length of pipe that is about 19 inches long holds 3.8 liters.
- a 21 ⁇ 2" diameter mesh pipe 13 inches in length holds over 1000 grams of DBNPA, sufficient for 13 slug feeds at 37.8 grams with 100% excess.
- DBNPA has close to an ideal solubility for this invention.
- the chemical is soluble enough that a very large water volume and hence a large pipe is not required for a typical dose. Yet, at 1.0% solubility, it is not so soluble that the dissolving of the chemical with each dose would dramatically increase the volume of water and thus increase subsequent dosages. This allows a large number of doses to be done from a single charge. If the density of the DBNPA is equal to that of water, the variation in volume of saturated water with each dose over the period of a month will be less than 10% of nominal.
- a more soluble chemical can also be used with this invention; however the number of doses will be limited. Likewise a less soluble chemical could be used but the water volume of the feeder would need to be increased to get a similar dose.
- Table 1 illustrates the consistency of results that was obtained from testing with a small scale device.
- the device consisted of a 3.0 liter plastic container surrounding a tube fabricated from 400-mesh polypropylene. 600 grams of DBNPA powder were added to the mesh-tube. After various soak times, 1 gpm of water was flushed through the feeder for 2 minutes. The total amount of DBNPA was then measured.
- the average quantity of chemicals released was 34.6 grams with a standard deviation of 3.1 grams.
- the feeder may perform more consistently with the basket elevated and containing a mesh bottom and/or with the sides of the basket masked to allow a more consistent water/chemical interface regardless of the quantity of chemical in the feeder.
- the invention as shown and described with respect to Figures 1, 3, 4, 5 and 6 has the slug-feed of the chemical and the addition of new liquid occurring as a single flush operation.
- the slug-feed may be performed by opening a valve and allowing the saturated water to drain out by gravity.
- the slug pipe may be refilled with unsaturated water.
- An automatic air-release/vacuum-breaker valve is helpful in this arrangement.
- This arrangement has the advantage that there is no excess purge water that could carry a small amount of additional chemical.
- the limitation with this embodiment is that the saturated chemical must be fed at an unpressurized point in the system.
- the invention also does not require an internal basket as the chemical can simply sit in the slug pipe so long as the configuration of the slug-pipe and flow of the saturated liquid inhibits solid chemicals from leaving the container. Having a mesh basket allows equilibrium to be reached faster and limits the amount of solid chemical carryout when flushing over a large range of flushing velocities.
- This invention can be combined with a kinetic feeding step to provide additional dosing, if necessary.
- This part of the treatment will have the same issues as prior art devices, particularly the control of release rate.
- much of the required dose will be accurately provided by the saturation dosing therefore the impact of the variability of the kinetic dosing will be less.
- Making the device into a combination saturation and kinetic feeder could simply be done by allowing the purge water to flow for a controlled length of time at a specific flow rate for more than required to purge the system of saturated chemicals.
- the amount of the additional kinetic-dose can be controlled by adjusting either the flow rate, the length of time of the kinetic-feed flow, or both.
- the time required to supply the full dosage is short enough to allow slug feeding of the chemical.
- a single feeder size could treat a broad range of systems.
- a specific feeder will have a specific volume of water and thus release a specific amount of chemical when the water becomes saturated. That amount of chemical will be appropriate for a specific size of cooling system.
- inert material can be added to the feeder. This inert material will reduce the volume of water in the feeder and hence the amount of chemical released.
- a kinetic release step can be added. By controlling the length of time and the water velocity for this step, larger systems can be adequately treated. Thus a broad range of chemical dosing can be done from a single feeder.
- This invention could, in addition, be used for a monthly single-shot dose of a different, compatible, and highly-soluble chemical.
- a compatible, highly-soluble biocide or biodispersant to the invention when it is being refilled with a biocide, the first release will contain both the multiple-slug-fed biocide and the highly-soluble biocide or biodispersant.
- Such dosing can be effective at preventing bacteria resistant to the primary biocide from becoming established or aiding in the removal of biofilm.
- the multiple-slug-fed chemical is DBNPA the highly-soluble chemical could be isothiazoline.
- Isothiazoline is available as a solid, is highly soluble, and is compatible with DBNPA.
- the exact amount of isothiazoline required for a single dose could be added to the feeder once per month when the feeder is being refilled.
- the isothiazoline would completely dissolve during the first holding period and that dose would be released along with the DBNPA the first time that the system is slug-fed.
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Organic Chemistry (AREA)
- Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US201261723926P | 2012-11-08 | 2012-11-08 | |
US201361828824P | 2013-05-30 | 2013-05-30 | |
PCT/US2013/069163 WO2014074827A2 (en) | 2012-11-08 | 2013-11-08 | Saturation limited feeder for chemical additions |
Publications (2)
Publication Number | Publication Date |
---|---|
EP2917155A2 true EP2917155A2 (en) | 2015-09-16 |
EP2917155A4 EP2917155A4 (en) | 2016-05-04 |
Family
ID=53783491
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP13853956.4A Withdrawn EP2917155A4 (en) | 2012-11-08 | 2013-11-08 | Saturation limited feeder for chemical additions |
Country Status (1)
Country | Link |
---|---|
EP (1) | EP2917155A4 (en) |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
IL142389A (en) * | 2001-04-02 | 2007-10-31 | Bromine Compounds Ltd | Solid material dissolution apparatus |
US20050244315A1 (en) * | 2004-04-30 | 2005-11-03 | Greaves Michael D | Solid product dissolver and method of use thereof |
NO324547B1 (en) * | 2005-09-23 | 2007-11-19 | Well Proc As | Method and apparatus for chemical dosing for injection water |
-
2013
- 2013-11-08 EP EP13853956.4A patent/EP2917155A4/en not_active Withdrawn
Also Published As
Publication number | Publication date |
---|---|
EP2917155A4 (en) | 2016-05-04 |
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Legal Events
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DAX | Request for extension of the european patent (deleted) | ||
A4 | Supplementary search report drawn up and despatched |
Effective date: 20160404 |
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RIC1 | Information provided on ipc code assigned before grant |
Ipc: C02F 1/76 20060101ALI20160329BHEP Ipc: E03B 11/00 20060101ALI20160329BHEP Ipc: C02F 1/50 20060101AFI20160329BHEP |
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STAA | Information on the status of an ep patent application or granted ep patent |
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STAA | Information on the status of an ep patent application or granted ep patent |
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18W | Application withdrawn |
Effective date: 20180607 |