EP0980668A2

EP0980668A2 - Method for dispensing a fluid, method for generating foam and systems to carry out said methods

Info

Publication number: EP0980668A2
Application number: EP99202659A
Authority: EP
Inventors: Cornelis Schouten
Original assignee: Epenhuysen Chemie NV
Current assignee: Epenhuysen Chemie NV
Priority date: 1998-08-18
Filing date: 1999-08-18
Publication date: 2000-02-23
Also published as: EP0980668A3

Abstract

Method of dispensing a fluid, such as foam, wherein from two spaced locations respective interdirected fluid jets, particularly foam jets, are generated to make a combined fluid jet, particularly a cone or fan shaped fluid jet, and wherein the fluid is preferably a highly concentrated detergent with one or more substances.

Description

The invention is in the field of dispensing a fluid, such as a gas or liquid, but e.g. also another flowable material, such as granules or powder of a solid matter (patricularly if fluidised), or a gel or paste, etc. Particularly, though not exclusively, the invention is in the field of dispensing a foaming liquid, more particularly dispensing a foaming detergent in e.g. a machine dishwasher.
Although the invention is dislosed here referring to machine dishwashing, the skilled person will immediately realise, that the invention has also other fields of application.
E.g. EP-A-465454 discloses a method for dispensing a liquid as well as relating equipment. Gas and liquid are seperately guided to a dispensing nozzle and brought together therewith to generate a mist of fine liquid droplets, wherein said mist is directly dosed into the for dispensing developed room, such as the with soiled crockery filled room within a dishwashing machine.
In one aspect an object of the invention is simplifying the equipment. In one aspect an object of the invention is simplifying maintenance. In one aspect an object of the invention is preventing failure. In one aspect an object of the invention to spread as homogeneous as possible a fluid, such as a highly concentrated detergent or another preferably highly concentrated fluid with preferably one or more preferably chemically active substances. In one aspect an object of the invention is efficient generating foam from an e.g. highly concentrated fluid with preferably one or more chemically active substances, such as a detergent. In one aspect an object of the invention is dosing fluid, such as foam, as seperate particles. In one aspect an object of the invention dosing fluid, such as foam, in such a manner as seperate particles, that when they settle on an object, such as crockery, they generate an at least essentially continuous, the object at least essentially completely covering layer. In one aspect an object of the invention is dispensing per unit of time an extremely small amount of fluid, particularly with a preferably chemically active substance, such as a liquid detergent. Other fluids with a preferably chemically active substance are e.g. insecticide, paint, coating, adhesive, cleaner, nutrient. In one aspect the object of the invention is safety.
One or more of the above objects are fulfilled with the invention as disclosed in here.
In the following the invention, its advantages and further objects, are illustrated in a non-limiting manner with the aid of an example that is expected to be the best embodiment at this moment. The enclosed drawing is at real scale.
Fig. 1 shows a sectional side view of a conveyor dishwasher with the dispensing equipment according to the invention;
Fig. 2 shows a sectional side view along the line III-III in fig. 3 of the dispensing nozzle of the invention;
Fig. 3 shows a sectional view along the line II-II in fig. 2;
Fig. 4 shows a side view of the dispensing nozzle of fig. 2, while the dispensing equipment is active;
Fig. 5 shows an end view of the dispensing nozzle of fig. 2, while the dispensing equipment is active;
Fig. 6 shows a top view of the dispensing nozzle of fig. 2, while the dispensing equipment is active;
Fig. 7 shows a top view of the foam generator according to the invention; and
Fig. 8 shows a sectional side view along the line VII-VII in fig. 7.
Fig. 1 shows a conveyor type machine dishwasher 1. It comprises a tunnel shaped housing 40, known as such, containing sequentially one or more optional, pre-wash 2, wash 4, rinse 5 and dry sections 6, all known as such. The tunnel shaped housing also contains a dispensing section 3 according to the invention. A conveyor belt, not shown, extends through the tunnel shaped housing along the above mentioned sections and projects with front and back end beyond the tunnel shaped housing. The e.g. in baskets 9 (only one shown) positioned crockery 10 is placed on the projecting front end of the conveyor belt at the beginning 7 of the machine 1 and moves in the direction of the arrow A while the machine is active, and is removed from the projecting back end of the conveyor belt at the end 8 of the machine 1. As such the crockery 10 is sequentially precessed by the several sections.
In the pre-wash, wash and rinse section the crockery is poured over with water, with dissolved therein possibly a small amount of detergent, at a rate of approximately 1000 l/hr in a way that is common in the field of machine dish washing, for which a plurality of nozzles 11 above, below and next to the conveyor belt direct relatively powerful water jets from all sides onto the passing crockery, to continuously maintain a relatively powerful water flow over the crockery. Said water is collected in the lower part of the machine in for each section an own reservoir 12 with between adjacent reservoirs an overflow. Water is continuously pumped from the reservoirs and through the nozzles 11 spread over the crockery. As is common, tap water, and possibly rinse aid, is dispensed in the reservoir of the last rinse section and superfluous water is removed from the reservoir of the first pre-wash section. Water flows therefore cascade-like counter to the crockery through the sequential reservoirs 12. The reservoir below the dispensing section 3 can be part of the cascade-flow. Alternatively, it is seperated therefrom to collect superfluous highly concentrated detergent therein for e.g. reuse. Within the machine the following temperatures above room temperature can prevail: 30°C in pre-wash, 50°C in wash and rinse, and 70°C in dry section.
The machine 1 comprises an externally located bin 13 for highly concentrated detergent that is conveyed to the machine 1 through tubing 14, preferably by supplying it to the tubing 14 and sucking it therein. This compound can be liquid, but also be of different particle type, such as granules or powder. The machine 1 also comprises a control unit 15 to control the supply of detergent to the machine 1.
Within the section 3 dispensing nozzle assemblies 16 are arranged above and below the conveyor belt, to direct jets of highly concentrated detergent from below and above onto the wet crockery. In this embodiment there are four of such assemblies 16 within the dispensing section 3; spaced next to each other, viewed in the longitudinal direction of the conveyor belt and two there above and two there below. With each assembly 16 seperate fluid particles, such as foam particles or foam flakes, are dosed such that a jet 19 of seperate particles is generated, wherein said jet 19 is the enclosure of the particles that each follow a statistic, own path. While the fluid particles move away from the assembly 16, the mutual distance of the fluid particels generally increases while generally the particles each follow an own ballsitic course. The particles settle on different locations onto the crockery and a plurality of said settled particles evenly makes a continuous layer, e.g. a foam layer. With the assembly 16 it is possible, at extremely low dose per unit of time (i.e. few liters of detergent per unit of time) to make a very fine, even distribution of the detergent over the crockery such that an optimised result can be provided at minimised consumption. It is found out that if the assembly 16 is used to dispense a foaming liquid, the assembly 16 can provide a homogeneous, continuous, flattened cone shaped (i.e. fan shaped) jet. This jet has in the one direction an apex between 60° and 120°, preferably approximately 80° and in the perpendicular direction an apex between 10° and 30°, preferably about 20°, with a consumption of at least essentially foamless detergent of approximately 5 l/hr to a maximum, preferably approximately 2 l/hr to a maximum. It is appreciated that the consumption of foamed detergent in liters per unit of time will be substantially higher. After a contact time of preferably 5 to 100 s, more preferably 8 to 25 s, the foam layer is removed from the crockery, preferably rinsed in one or more of the succeeding sections or phases.
The assembly 16 (see fig. 2-6) comprises two dispensing nozzles 17 that are each designed to eject a preferably powerful relevant jet 18, preferably a continuous, cohesive fluid jet, such as a jet foaming liquid. To get a common jet 19, the nozzles 17 are positioned such that the jets 18 mutually impact at a short distance from the relevant nozzle, preferably at or in the vicinity of, preferably upstream from the point, where from one or both jets a noticable quantity, e.g. at least 10 vol%, fluid has seperated in seperate particles (such as liquid or foam particles). While the jets 18 preferably diverge little (e.g. 10°), the shape of the jet 19 is substantially cone- or fan shaped (with an apex of e.g. 80°). The central longitudinal lines of the nozzles 17 preferably span an angle between about 60° and 120°, and said amgle is preferably at least about 90°. Preferably the assembly 16 is designed such that the interdirected jets 18 at least essentially share at least one physical property, such as jet shape (e.g. cone or fan shape), jet dimension (e.g. diameter of the cross section), power of the jet (e.g. the exit pressure from the nozzle), the density of the fluid (e.g. foam like), the fluid type (e.g. a gas or liquid). Preferably the interdirected jets 18 are at least essentially identical for a plurality of physical properties, among which the jet shape, jet dimension, fluid type, jet power, fluid density. The skilled man will have no particular problems to determine the mutual location of the nozzles 17 by trail and error to get the desired properties of the common jet 19. It is appreciated that when the nozzles 17 or too far apart, the power of the jets can be decreased too much to provide the desired effect.
The assembly 16 is furthermore structured as follows: There is a top housing 21, mounted onto a base 22 and povoting around shaft 20. As such the attitude of the jet 19 can be changed as desired. Wedged between the housing 21 and the base 22 is the web 23 of a mounting 24, here an elongated rail. Within the housing 21 a fluid channel 25 extends between the nozzles 17, via a connecting channel 26 connecting to the feed channel 27 extending through the base 22. The channel 26 extends through the spigot 30 upwardly extending from the base 22 and providing a pivot for the housing 21. The feed channael 27 has at one end a connecting stub 28 with enlarged diameter for connection to a fluid feed pipe (not shown). At its opposite end the channel 27 has a connecting stub 29 with enlarged diameter for connection to a fluid exhaust pipe (not shown). As such this assembly 16 can be connected to the fluid source (not shown) via the connecting stub 28, and a next assembly 16 (not shown) can be connected via the connecting stub 29, such that the respective channels 25 of two or more assemblies 16 are connected in parallel. As shown, it is prefered for providing a convenient jet 18 that the part 17a, connecting to the nozzle, has a constricted flow-through area, preferably at least about a factor two and with preferably a length of at least approximately one, more preferably at least approximately two times, its flow-through area. To provide a convenient jet 18 it is furthermore prefered, as shown, that the channel 27 and the central part 17b of the nozzle 17 have at least essentially the same flow-through area, while the flow-trhough area of the channel 25 and the channel part 17c of the nozzle 17 connecting thereto are larger, with that of the channel 25 as largest. To provide a convenient jet 18 it is furthermore prefered that the central part 17b of the nozzle 17 has e length such that a homogeneous flow is provided therein, for which said length is preferably at least approximately one time, more preferably at least approximately one and a half times the flow-through area thereof. Preferably the flow-through area of the fluid supply line and fluid exhaust line are at least approximately equal to that of the channel 27.
When using the assembly 16 to dispense a highly concentrated foam like detergent, with a concentration of one or more active agents of at least 3 wt%, in a machine dishwasher, it is prefered that the channel 27 and the central part 17b of the nozzle 17 have a flow-through area of at least approximately 4 mm, while the part 17a of the nozzle has a flow-through area of at least about 2 mm, the channel 25 has a flow-through area of at least about 6 mm, and the length of the part 17b of the nozzle measures at least approximately 6 mm.
The detergent is preferably liquid and contains e.g. an alkalic active substance and/or a sequestric active substance. A convenient composition for machine dish washing contains NaOH or KOH, a water conditioning agent such as NTA, EDTA, fosfates, zeolites or fosfonates; sequestering agents; possibly further agents such as a bleaching agent; surfactants; and the rest water, and has a pH more than approximately 13, preferably about 13.5. The concentration NaOH or KOH equals preferably more than about 10 wt%, more preferably more than about 20 wt%. The detergent preferably contains a substance that degrades the foaming action at high temperatures, e.g. from about 40°C, such that after being rinsed from the crockery, the detergent does not result in foam problems within the dishwasher. Said substance can possibly be added to said detergent as soon as it is being used.
The foam generator 31 (see fig 7 and 8) comprises a preferably at least essentially cylindrical, hollow chamber 32, preferably at least essentially filled with a porous material 33. The bottom of the chamber 33 contains an opening 34 for connection to a fluid supply line (not shown). Reletively close above the bottom, the chamber 32 contains two at least essentially diametrically opposed openings connecting to at least essentially radially directed pipe tubs 35, 36, such that fluid can be supplied to the chamber 32 in a substantially radial, diametrically opposite, direction. In an alternative embodiment said pipe tubs 35, 36 connect tangentially directed to the chamber 32. At the side opposite the bottom, the chamber 32 contains an exhaust opening 37. To e.g. make a foaming detergent, the contents of the chamber is about 100 ml. The contents of the chamber 32 is also determined by the number of assemblies 16 that is connected thereto. The opening 34 is supplied with a boosting means, preferably a gastype fluid, such as air, supplied at a pressure essentially higher than atmospheric pressure, such as a pressure of preferably about 1 bar, and in a quantity of preferably at least 300 l/hr, more preferably about 1200 l/hr. The line 35 supplies a fluid, such as a liquid, e.g. a diluting agent such as water, in a quantity of preferably about 2 l/hr. The line 36 suppies a fluid such as liquid, e.g. that with the foaming action, preferably at least essentially foam free, such as a highly concentrated aqueous detergent, in a quantity preferably about equal to that of the liquid supplied by the line 35. As such essentially more gas than liquid is supplied to the chamber 32. The ratio gas/liquid preferably amounts at least 100:1, more preferably at least 250:1, most preferably at least 500:1. To make foaming liquid, it is prefered to supply the chamber 32 with a liquid with foaming agent, such as a surfactant. Alternatively the foaming agent can also seperately supplied to the chamber 32.
The foam leaves the chamber 32 via the opening 37 and is due to the higher gas pressure within the chamber 32 compared to the gas pressure within the dishwasher pneumatically transferred to the assembly 16 and from there also pneumatically dispensed in the section 3. To prevent degradation of the foam during transfer between the chamber 32 and the section 3, it is prefered that the pneumatic transfer takes place at relatively low gas pressure.
It is found out that the above described foam generator 31 can supply two or more assemblies 16 at one time. Good results have been obtained wherein a foam generator 31 supplied 3, 4, 5 or 6 assemblies 16 at one time, wherein the resulting foam of the generator 31 was essentially equally spread over the assemblies 16. While the liquid detergent was supplied to the generator 31 in a continuous, pulsating flow by using a peristaltic pump, an even, homogeneous and continuous flow exited the assemblies 16.
In an alternative embodiment of the foam generator 31, the supply line 35 or 36 is removed.
The chamber 32 is preferably relatively elongated, such as shown in the drawing. The length of the foam chamber is preferably about twice its width. It was found out that the more elongated the chamber 32, the more mass of foam can be generated per unit of time. As such much foam can be dispensed with a chamber of relatively small volume.
The porous contents 33 of the chamber 32 determines preferably a labyrinth-type structure. The contents 33 is preferably chemically resistant. This porous material 33 is e.g. a three dimensional mesh structure of fine fibres, preferably made in a typical manner, such as e.g. comparable to material for scouring pads. For scouring pads mats are made from fibre bundles and a number of these mats are stacked to become a thick slab. With a binding agent the fibres are mutually fixated. Then the slab is cut in pieces. The fibres can be from e.g. Nylon or another plastic such as polyethene, glass or some other mineral or metal, such as (preferably stainless) steel. The fibres follow preferably a random two-or threedimensional pattern. The fibres preferably extend knotty through the material. Alternatives for the fibrous filler are feasible, such as a granule filling of e.g. carbon granules. A fibre filling is however prefered, since it is expected that this material takes minimum volume with respect to a maximum labyrinth-effect, while this material is relatively cheap. One of the functions of the poroes filler 33 is safeguarding an even exhaust flow of foam from the chamber 32. It was found out that without filler 33, the foam exits the chamber 32 shockwise (sputtering).
An alternative solution to the problem of uneven exhaust flow of foam from the chamber 32 is the use of a filter or sieve type flow through member, e.g. positioned within the opening 37, or locating the porous material 33 within a length part of the exhaust line, connected to the opening 37.
The foam generator 31 can e.g. be located on an easily accessible location, e.g. at a distance from the dispensing section, preferably at the exterior of the housing 40 of the conveyor dishwasher. By providing the chamber 32 with a view window, the proper functioning of the foam generator 31 can easily be detected.
The foam transfer line (not shown) connected to the exhaust opening 37 of the foam generator and the connection stub 28 of the assembly preferably has a length such that possible shocks or other irregularities within the foam supply are damped. The line may not be too long to prevent that the residense time of the foam becomes to large, resulting in essential degradation of the foam within said line such that it is not able any more to leave the assembly 16 essentially as foam.
It is appreciated that the foam is preferably merely transported to the nozzle 17 by the fluid supplied to the chamber 32, such that the equipment is simplified and maintenance is limited.
The foam generator 31 and the assembly 16 are also applicable to other fields than diswashing and cleaning.

Claims

Method of dispensing a fluid, such as foam, wherein from two spaced locations respective interdirected fluid jets, particularly foam jets, are generated to make a combined fluid jet, particularly a cone or fan shaped fluid jet, and wherein the fluid is preferably a highly concentrated detergent with one or more substances.
Dispensing nozzle assembly comprising two mutually spaced nozzles provided such that respective, interdirected fluid jets can be generated to make a combined fluid jet.
Assembly according to claim 2, wherein the nozzles are directed such that the fluid jets mutually make an angle between 60° and 120°, preferably about 90°.
Assembly according to claim 2 or 3, wherein at least one of the nozzles has a flow through constriction, preferably followed by a flow through widening.
Assembly according to claim 2, 3 or 4, wherein the nozzles are connected to a common fluid supply line.
Assembly according to any of claims 2-5, wherein at least one of the nozzles makes a fluid jet that diverges essentially less, preferably at least 30%, more preferably at least 50% than the combined fluid jet.
Device, such as dishwasher, with a dispensing nozzle assembly preferably located within said device, or a machine dishwahser provided with a foam generator.
Device according to claim 7, wherein there is, preferably outside the device, a foam generator connected to a fluid source, a line extending between the dispensing nozzle assembly and foam generator to transport foaming liquid therebetween.
Method for generating foaming liquid, wherein a gas is supplied to the bottom of a chamber, a liquid is supplied from the side and the foaming liquid is removed from the top.
Foam generator with a gas supply opening at the bottom, a liquid supply opening at the side and a foam exhaust opening at the top.