GB2488125A

GB2488125A - Injection Apparatus

Info

Publication number: GB2488125A
Application number: GB1102645.7A
Authority: GB
Inventors: Shane Richard Wootton
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-02-16
Filing date: 2011-02-16
Publication date: 2012-08-22
Also published as: GB201102645D0

Abstract

Apparatus 208 for injecting a liquid reagent into a mixing chamber comprises an outer body 501 having a bore 601 with a first inlet 404, a first control surface 703 and an first outlet 405 for allowing liquid chemical reagent to be expelled from the bore, and a throttle member 502 which extends through at least a portion of the bore 601wherein the throttle member 502 has a second control surface 704 arranged to cooperate with the first control surface 703 to provide a constriction, such that the first inlet 404, the constriction and the first outlet 405 define a flow path for liquid reagent supplied to the first inlet 407. The apparatus further defines a passageway 607 extending from a second inlet 223 to a second outlet 609 such that the second outlet is located along the flow path between the constriction and the first outlet. The apparatus essentially acts as a venturi mixer wherein an additional material is added via passageway 607 to the liquid reagent. The device may be used in polyurethane mixing equipment wherein the device adds additional material such as carbon fibres, filler or dye to polyol or isocyanate reagents prior to the reagents reacting in the mixing chamber. A method of injection a liquid reagent into a mixing chamber is also disclosed.

Description

Injection Apparatus

CROSS REFERENCE TO RELATED APPLICATIONS

This application represents the first application for a patent directed towards the invention and the subject matter.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to apparatus for injecting a liquid chemical reagent into a mixing chamber to mix with a second chemical reagent, mixing equipment for producing material by a chemical reaction between a first chemical reagent and a second chemical reagent and a method of injecting a liquid chemical reagent into a mixing chamber to mix with a second chemical reagent.

2. Description of the Related Art

It is known to create polyurethane, and polyurethane foam, by injecting Is two liquids, a polyol and isocyanate, into a mixing chamber at very high velocity, such that high energy jets of the liquids collide to form a reacting mixture from which the polyurethane is formed. To achieve the required high velocities the liquids are forced through nozzles using a liquid pressure of typically 150 Bar.

Mixing equipment for producing polyurethane in this manner is shown in Figure 1. The polyol is pumped by a first pump lOlA from a first storage container 102A to a first injection apparatus 103A for injection into the mixing chamber 104 of a mixing head 105. Similarly the isocyanate is pumped by means of a second pump IOIB from a second storage container 1026 to a second injection apparatus 1036 for injection into the mixing chamber 104 where it collides with the injected polyol.

The mixing head 105 includes a production piston 106 that is moveable backwards and forwards by a hydraulic system (not shown). With the production piston 106 in the retracted position, shown in Figure 1, the liquid chemical reagents emitted by the injection apparatuses 103A and 103B are allowed to collide and mix. The reacting mixture passes from the mixing chamber 104 and out of the mixing head 105 through an outlet cylinder 107.

After a mixing operation is completed the production piston 106 is moved to the forward position to stop the mixing process. With the production piston 106 in the forward position the liquid chemical reagents are diverted through a respective one of two grooves 108A and 108B formed in the production piston 106 back through a return pipe 109A, 109B to the storage containers 102A, 102B. After stopping the mixing process in this way, a second piston 110 is moved forward to clean any remaining mixture from the outlet cylinder 107.

As well as producing polyurethane by this process, it is also know to introduce additional material into the reacting mixture to produce polyurethane based materials with specific required physical properties. For example, it is known to introduce various types of gas into the mixture, such as air, carbon dioxide and pentane to produce various foam materials. In the case of carbon dioxide, it may be pre-mixed into the isocyanate, which is then held under pressure. Similarly air or pentane may be pre-mixed into the polyol. However, this in itself creates a potentially more dangerous product to store.

In the case of air, it is known to blend the gas into the polyol as it is used, but the emulsifying equipment used to blend the air into the polyol is expensive and additional equipment is required to measure the volume of air mixed into the polyol.

It is also know to introduce pentane into the polyol by blending in an emulsifier as the polyol is being used. Again, the required emulsifying equipment is expensive, and potentially dangerous.

It is also know to introduce additional liquid material into the reacting mixture. For example, a liquid pigment may be introduced to produce polyurethane material of a required colour. This is typically achieved by having a third nozzle in the mixing chamber arranged at approximately 90 degrees to the polyol and isocyanate nozzles, such that the pigment is injected at the point where the mixing takes place. However, such a method requires a more expensive mixing apparatus including a mixing head having the third nozzle, and high-pressure equipment used to inject the pigment. In addition, this method can result in the problem of the third nozzle becoming blocked by polyurethane. Furthermore, due to the design of the dosing unit that supplies the pigment at high pressure to the mixing head, the volume of pigment that can be provided for a particular mixing operation is limited. Consequently, the volume of coloured polyurethane that may be produced in a single mixing operation is limited. Also, where two different colours of polyurethane are required, the dosing unit must be cleaned of one pigment before the next is used.

It is also know to introduce particulate solid material into the reacting mixture. In some cases this may simply be to add weight to the polyurethane at low cost. For example, it is known to add a powdered material, such as calcium carbonate, to polyurethane foam used to fill the underside of shower trays. This may be achieved by pre-mixing the solid material with one of the liquid chemical reagents, but problems exist with the materials settling out if not used immediately.

In addition, there are some solid particulate materials that cannot be used in this way. One example is glass microspheres, which are known to be included in polyurethane where low density, high insulation and strength are required. Glass microspheres cannot currently be mixed into polyurethane using high pressure mixing equipment because they are unable to withstand the high pressure exerted upon them. i.e. the glass microspheres collapse under pressure.

Consequently polyurethane incorporating glass -microspheres is generated by alternative equipment. The alternative equipment includes a mechanical mixing arrangement in which the two liquid chemical reagents are supplied at a relatively much lower pressure, allowing the microspheres to remain intact. A problem with this latter equipment is that the mixing arrangement has to be rinsed through with solvents after each use, to avoid it becoming clogged up with solidified polyurethane material.

BRIEF SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provided an apparatus as claimed in claim 1 for injecting a liquid chemical reagent into a mixing chamber to mix with a second chemical reagent.

According to a second aspect of the present invention, there is provided a method, as claimed in claim 12, of injecting a liquid chemical reagent into a mixing chamber to mix with a second chemical reagent.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows prior art mixing equipment for producing polyurethane; Figure 2 shows a schematic diagram of mixing equipment 201 in a mixing configuration; Figure 3 shows a schematic diagram of mixing equipment 201 in a non-mixing configuration; Figure 4 shows the injection apparatuses 208 and 210 in cross-section, along with the remainder of the mixing head 202 shown in dotted outline; Figure 5 shows a perspective view of the injection apparatus 208; Figure 6 shows a cross sectional perspective view of the injection apparatus 208; Figure 7 shows the injection apparatus 208 separated into its two major components, namely the outer body 501 (shown in cross section), and the throttle member 502; Figure 8 shows a partial cross-sectional view of the mixing head 202 during operation, including front end portions of the injection apparatuses 208 and 210; Figure 9 shows a second example of mixing equipment 901 embodying the present invention; Figure 10 shows an alternative mixing equipment 1001 embodying the present invention, comprising two injection apparatuses 208A and 208B configured to receive additional material from containers 225A and 225B; Figure 11 shows further mixing equipment 1101 embodying the present invention; Figure 12 shows an injection apparatus 1208 with an internal valve mechanism in an open position; and Figure 13 shows an injection apparatus 1208 with an internal valve mechanism in a closed position.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Figures 2 and 3 Mixing equipment 201 for producing polyurethane and embodying the present invention is shown in the schematic diagrams of Figures 2 and 3. The mixing equipment 201 is shown in mixing configuration in Figure 2 and a non-mixing configuration in Figure 3.

The mixing equipment comprises a mixing head 202 that is supplied with liquid chemical reagents stored in storage containers 203A and 203B. In the present example the mixing equipment 201 is arranged to produce material comprising polyurethane, and consequently the first storage container 203A contains a polyol while the second storage container 203B contains an isocyanate.

A first pump 204A is arranged to pump polyol from the storage container 203A to a first stream distributor valve 205A. Depending upon the position of the stream distributor valve 205A, the polyol is directed via a pipe 206A back to the storage container 203A or through a second pipe 207A to a injection apparatus 208 located in the mixing head 202. The polyol is typically supplied at a controlled pressure of 150 bar, and fluid pressure metering 230A is provided on the pipe 207A for the purposes of monitoring and controlling this pressure.

Similarly, a second pump 204B is arranged to pump isocyanate from the storage container 203B to a second stream distributor valve 205B.

Depending upon the position of the stream distributor valve 205B the isocyanate is directed back through a pipe 206B to the storage container 203B or alternatively directed through pipe 207B to a second injection apparatus 210 located within the mixing head 202. The isocyanate is also supplied to the mixing head at a controlled high pressure of typically 150 bar, as measure by metering 230B located on the pipe 207B.

The first injection apparatus 208 and the second injection apparatus 210 are arranged either side of a mixing chamber 209 and they are each configured to provide a jet of the respective liquid chemical reagent into the mixing chamber 209. Thus, the first injection apparatus 208 is configured to provide a jet stream of polyol into the mixing chamber 209, while the second injection apparatus 210 is configured to inject a jet stream of isocyanate into the mixing chamber 209 so that the two liquid reagents collide and mix to produce a reacting mixture. The mixture flows from the mixing chamber 209 and out of the mixing head 202 through an outlet cylinder 211 located adjacent to the mixing chamber 209.

Although not clear from the schematic diagram of Figure 2, the mixing chamber and the outlet cylinder 211 are each cylindrical in shape and have axes extending perpendicular to each other. In addition, it may also be noted that the injection apparatuses 208 and 210 are shown in Figure 2 positioned one above the other, i.e. in the same plane as the outlet cylinder 211. This representation is purely for convenience of illustrating the equipment, and in reality the injection apparatuses 208 and 210 are arranged in a conventional manner in a substantially horizontal plane perpendicular to the outlet cylinder 211.

The mixing head 202 comprises a production piston 212 having a hydraulic end 213 located within a hydraulic cylinder 214 and an operating end 215 configured to slide into the mixing chamber 209. The hydraulic end 213 of the production piston 212 is acted upon by hydraulic fluid within the hydraulic cylinder 214 to either move it backwards into its retracted position, shown in Figure 2, or forwards into a forward position, shown in Figure 3.

The production piston 212 has a pair of grooves 216A and 216B formed along in its operating end 215. The grooves 216A and 216B are configured to align with the outlets of the injection apparatuses 208 and 210 when the production piston is in its forward position, as shown in Figure 3. In this position, the grooves 216A and 216B are also aligned with return ducts 217A and 217B respectively that are connected to respective storage containers 203A and 203B via return pipes 218A and 2188. Thus, when the production piston 212 is in its forward position, the liquid reagents ejected by injection apparatuses 208 and 210 are returned to their respective storage containers via grooves 216A, 216B, return ducts 217A and 217B and return pipes 218A and 2188.

The mixing head 201 also comprises a cleaning piston 219 having a hydraulic end 220 located within a second hydraulic chamber 221 and an operating end 222 configured to slide through the outlet cylinder 211. The hydraulic end 220 of the cleaning piston 219 is acted upon by hydraulic fluid supplied to the hydraulic cylinder 221 so as to move the piston 219 backwards to the retracted position of Figure 2 or forwards to the forward position of Figure 3 during operation. As is known in the art, after polyurethane material has been mixed and the production piston has been moved forward to stop further mixing, the cleaning piston is moved forward to eject material remaining within the outlet cylinder 211.

In the present example, the injection apparatus 210 is of a form that is known in the art. However, the mixing equipment 201 differs from conventional mixing equipment in the specific features of the injection apparatus 208. As well as having an inlet for receiving a liquid chemical reagent (in this case a polyol) via pipe 207A, the injection apparatus 208 has a second inlet for receiving additional material that is to be included in the reacting mixture produced by the mixing head 202. In the present example, the second inlet 223 is connected via a pipeline 224 to a container 225 storing the additional material. In the present example, a valve means 226 is provided in the pipe 224 for controlling flow of the additional material 225 to the injection apparatus 208. In addition, a flow measurement device 227 is provided to measure rates of flow of the additional material 225 to the injection apparatus 208.

In some examples, the additional material is in the form of a gas and the storage container 225 is a gas cylinder containing the gas under pressure.

In such cases, the flow measurement device 227 is a suitable device for measuring gas flows through a pipe, and the valve means 226 comprises a number of valves: a first valve to selectively switch on and off the flow of additional material and a second valve to adjust the rate of flow of additional material over a continuously variable range. At least the first of these two valves may be operated by a solenoid actuated in response to signals received from a processing system (not shown) that controls the operation of the mixing equipment 201.

In different examples of such mixing equipment 201 the gas cylinder contains compressed air, carbon dioxide, pentane, or other gaseous blowing agents.

In an alternative example, the container 225 is replaced by a compressor, which provides compressed air to the injection apparatus 208 via the pipe 224.

In alternative examples of the mixing apparatus 201 the container 225 is a container containing a liquid such as a colour pigment that is to be supplied to injection apparatus 208. In one such example, the additional material contained within the container 225 is a cross-linking reagent that is known to cause additional cross linking during the production of the polyurethane. Thus, by introducing the cross-linking reagent, harder (i.e. firmer) polyurethane is produced or by reducing the amount of cross-linking agent softer polyurethane is produced. Thus, it will be understood that by varying the rate of flow of additional material, by means of suitable valve means 226, polyurethane of varying hardness may be produced.

As will be described in further detail below, it has been discovered by the applicant that a partial vacuum is created by the injection apparatus 208 itself, and consequently, in examptes where the additional material stored in container 225 is a liquid, this partial vacuum in combination with ambient air pressure provides forces for transporting the liquid from the container 225 to the injection apparatus 208. This is further assisted by gravity by locating the container 225 at a height above the injection apparatus 208. However, it is envisaged that for some applications, additional mechanisms for transporting the liquid additional material from the container 225 to the injection apparatus 208 will be used. For example, where the liquid is particularly viscous and a relatively high flow rate of the additional material is required, then a pump may be used to increase the rate of flow.

In yet further examples of the mixing equipment 201, the additional material stored within the container 225 and supplied to the injection apparatus 208 is a particulate solid substance, such as glass microspheres, polymer spheres, a mineral, such as calcium carbonate or sand, etc. Depending upon the abilities of the solid particulate matter to flow, it may be transported from the container 225 to the injection apparatus 208 under the force of gravity alone, or in combination with a mechanical transportation device such as an Archimedes' screw.

Although the above-described examples refer to the production of polyurethane based materials, it will be understood that the apparatus may be used to create other material formed by mixing of two chemical reagents, such as an epoxy resin based material.

Figure 4 The injection apparatuses 208 and 210 are shown in cross-section in Figure 4, along with the remainder of the mixing head 202 shown in doffed outline to illustrate the location of the injection apparatuses within the mixing head. In this illustration, the production piston 212 is in its retracted position leaving open the mixing chamber 209 between the injection apparatuses 208 and 210.

The injection apparatus 208 is located within the mixing head 202 and maintained in position by an external screw thread 401 on the injection apparatus and mating internal thread on the mixing head. An inlet channel 402A is provided in the mixing head 202 providing communication from the pipe 207A (shown in Figure 2) to a cavity 403A that surrounds a portion of the injection apparatus containing its inlets 404. Thus, in use, liquid reagent is supplied to the inlets 404 of the injection apparatus 208 via the inlet channel 402A and the cavity 403A.

It may be noted that the conventional injection apparatus 210 is similarly mounted within the mixing head 202 and supplied with its liquid chemical reagent via an inlet channel 402B and cavity 403B.

The injection apparatus 208 has an outlet 405 at its front end, which is located to one side of the production chamber 209. The other injection apparatus 210 has an outlet 406 located on the opposite side of the production chamber 209 such that during production, liquid chemical reagents are ejected from the outlets 405, 406 to collide within the production chamber 209.

The grooves 216A and 216B formed in the production piston 212 are also illustrated in Figure 4. Immediately before material production commences, and after it is stopped, the chemical reagents emitted from the outlets 405 and 406 are returned via the grooves through the return ducts 217A and 217B respectively back to the storage containers 203A and 203B.

Figures 5, 6 & 7 The injection apparatus 208 is shown in the perspective view of Figure 5, and the cross sectional perspective view of Figure 6. In Figure 7, the injection apparatus 208 is shown separated into its two major components: the outer body 501; and the throttle member 502. The outer body 501 is shown in cross section in Figure 7, while the throttle member 502 is shown complete.

In the present embodiment, the injection apparatus 208 comprises an outer body 501 of as type that may be found in conventional injection apparatuses, such as injection apparatus 210. The outer body 501 defines the outlet 405 of the injection apparatus 208 and a plurality of first inlets 404: in the present case, four inlets 404. An outer cylindrical surface of the outer body defines the external thread 401 that is used to locate and maintain the injection apparatus 208 within a mixing head.

A front planar circular surface 503 of the outer body 501 surrounds the outlet 405, and a cylindrical outer surface 504 of the outer body extends backwards from the front surface 503. The surfaces 503 and 504, as is known in the art, are arranged to be a good fit against mating surfaces in a mixing head such that liquid chemical reagent supplied to the inlets 404 is unable to pass over the surfaces 504 and 503.

The outer body 501 defines a bore 601 that extends from the outlet 405 along the length of the outer body 501 to an opening 701 at the rear end of the outer body 501. The bore 601 comprises a threaded portion 602 adjacent the rear end of the outer body 501. The threaded portion 602 is configured to mate with an external threaded portion 603 formed on the throttle member 502.

A pair of 0-rings 604 are located within grooves formed in the bore 601 of the outer body 501 adjacent to the threaded portion 602. The 0-rings 604 provide a seal between the bore 601 of the outer body 501 and an outer cylindrical surface 605 of the throttle member 502.

The bore 601 of the outer body 501 has a generally cylindrical portion 702 and the inlets 404 extend through the wall of the outer body 501 into this cylindrical portion. The bore 601 also has a conical surface 703 that extends between this cylindrical surface 702 and the outlet 405. The conical surface provides a first flow control surface of the injection apparatus 208.

The throttle member 502 is provided with a conical outer surface 704 at its front end, which provides a second flow control surface of the injection apparatus 208. The second flow control surface 704 is spaced from the first flow control surface 703 by a narrow gap.

Adjacent to the conical outer surface 704, the throttle member 502 has a generally cylindrical outer surface 606, which in co-operation with the cylindrical surface 702 of the bore 601 provides a channel 607 that extends from the inlets 404 to the control surfaces 703 and 704.

The control surfaces 703 and 704 are spaced apart by a smaller gap than the gap provided between the cylindrical surfaces 606 and 702.

Consequently, the first control surface 703 of the outer body and the second control surface 704 of the throttle member co-operate to provide a constriction, which, during use, allows a restricted flow of the liquid chemical reagent between the inlets 404 and the outlet 405. Thus, the inlets 404, the constriction provided by the control surfaces 703 and 704 and the outlet 405 define a flow path through the injection apparatus 208 through which liquid chemical reagent supplied to the inlets is able to flow.

Unlike conventional injection apparatuses, the injection apparatus 208 has a throttle member that defines a passageway 608 extending from a second inlet 223 to a second outlet 609. The second outlet 609 is located adjacent the outlet 405 of the injection apparatus 208 along the flow path between the constriction (formed by the control surfaces 703 and 704) and the outlet 405.

A portion of the passageway 608 adjacent to the inlet 223 defines an internal thread 610 to allow a pipe, such as pipe 224 (shown in Figure 2), to be connected to the inlet 223.

It may be noted that the screw thread 610 is provided as a means of making connection with a pipe fitting, and alternative such means for providing a pipe connection, as are known in the art, may be used.

As mentioned previously, the 0-rings 604 are provided in grooves formed in the bore 601 of the outer body 501, rather than in grooves formed on the outer surface 605 of the throttle member 502. Consequently, this has enabled the passageway 608 to be made wider than it otherwise might have been.

Figure 8 A partial cross-sectional view of the mixing head 202 including front end portions of the injection apparatuses 208 and 210 is shown in Figure 8 during operation.

Polyol 801 is supplied, via the inlet channel 402 and the chamber 403 formed in the mixing head 202, to the inlets 404 of the injection apparatus 208.

Consequently, the liquid chemical reagent 801 flows from the inlets 404 along the channel 607, formed between the cylindrical inner surface 702 of the outer body 501 and the cylindrical outer surface 606 of the throttle member 502, through the constriction, formed by the first control surface 703 and second control surface 704, and through the outlet 405.

As is known in the art, the liquid chemical reagent 801 is forced into the mixing head 202 at high pressure (of typically 150 bar) with the rate of flow being limited by the constriction formed by the control surfaces 703 and 704.

Thus the pressure of liquid in the channel 607 is very high but the velocity of that liquid 801 is relatively low, and the constriction causes a large pressure drop, while greatly increasing the velocity. Consequently, the liquid emerging from the constriction and passing out of the outlet 405 is flowing at a very high velocity but the pressure within that liquid 801 is much reduced.

As illustrated in Figure 8, the outlet 609 formed at the end of the throttle member 502 is located along the flow path of the liquid chemical reagent 801 as it passes from the constriction (formed by the control surfaces 703 and 704) to the outlet 405. The constriction causes a large drop in the fluid pressure, so that, although the liquid chemical reagent is supplied at very high pressure (of typically 150 bars) to the injection apparatus 208, the pressure of the fluid emerging from the constriction is relatively low. Consequently, this arrangement allows additional material to be injected from the outlet 609 into the flow of liquid chemical reagent at a relatively low pressure (when compared to the pressure of reagent supplied to the injection apparatus).

In addition, the liquid chemical reagent 801 is flowing at a high velocity as it passes the outlet 609, and so the pressure present at the outlet is further reduced. It has been found, in trials, that the actual pressure appearing at the outlet 609 depends upon the set-up of the mixing apparatus. In cases where the two liquid chemical reagents is supplied to the two injection apparatuses 208 and 210 at different flow rates, fluid pressures have been measured at the outlet 609 of up to 40 bars. However, when the flow rates of the two chemical reagents was made equal, the fluid pressure present at the outlet 609 was measured at less than I bar (i.e. a partial vacuum). Thus, with this set up, the reduced pressure causes any material present in the outlet 609 to be drawn is into the flow, whether that material comprises a gas, a liquid, particulate solid material, or a combination of such materials.

It may be noted that in one experimental arrangement of the present apparatus, material was not supplied to the inlet 223 of the throttle member 502, but instead a pressure gauge was attached to the inlet 223. The result of the operation of this arrangement was that the stream of liquid 801 past the outlet 609 was found to create a partial vacuum at the outlet 609. Specifically, the pressure found within the passageway of the throttle member was approximately 30 millibars.

In the example shown in Figure 8, liquid material 803 is being provided into the passageway 608 of the throttle member 502 and is being drawn into the centre of the flow of liquid chemical reagent 801 exiting the outlet 405.

Thus, the material 803, along with the polyol 801 is injected into the production chamber 209 where it collides with a second high velocity flow of isocyanate 804 injected by the injection apparatus 210. As a result, as well as causing mixing of the two liquid chemical reagents, this arrangement also simultaneously mixes the additional material 803 in the production chamber 209. (For the sake of clarity, the resulting mixture is not shown in Figure 8.) The present example refers to polyol being provided to the injection apparatus 208 and isocyanate being provided to the conventional injection apparatus 210. However, in alternative examples the injection apparatus 208 is used to inject isocyanate, along with additional material, while the conventional injection apparatus 210 is used to inject the polyol.

Figure 9 A second example of mixing equipment 901 embodying the present invention is shown in Figure 9. The mixing equipment 901 has similar components to the mixing equipment 201, and where the components are the same, these have been provided with the same labels. Thus, for example, the mixing equipment 901 comprises the mixing head 202 and includes the injection apparatus 208. However, the mixing equipment 901 differs from the mixing equipment 201 in that the pipe-work 904 supplying additional material to the injection apparatus 208 includes a manifold 951 having three inlets each connected to as separate container 952, 953 and 954. Each of the containers contains a different additional material that is suppliable via the pipe-work 904 to injection apparatus 208. In this example, the containers 952, 953 and 954 each contain a different coloured pigment that may be added to the reacting mixture to produce different coloured polyurethane. So that the coloured pigments may be selected as required, each container 952, 953 and 954 is provided with a valve means 955, 956 and 957 at its outlet to control flow of material from the containers 952, 953 and 954. Also, a respective flow rate meter 958, 959, 960 has been provided in series with the valve means 955, 956 and 957 such that the flow rates may be monitored and controlled. An additional valve means 961 is provided adjacent to the injection apparatus 208, which may be closed to prevent residual additional material in the manifold 951 from entering the injection apparatus 208 after production of polyurethane has stopped.

In alternative embodiments, a metering pump is provided in series with each of the valve means 955, 956 and 957 in addition to, or as an alternative to, the flow rate meters 958, 959, 960.

Figure 10 In the above-described examples, additional material is supplied to one of two injection apparatuses within a mixing head. However, in alternative equipment embodying the present invention additional material is suppliable to more than one injection apparatus. An alternative mixing equipment 1001 embodying the present invention is shown in Figure 10 comprising two injection apparatuses 208A and 208B configured to receive additional material from containers 225A and 225B. The mixing equipment 1001 comprises many components that are common to mixing equipment 201, and these common components have been provided with the same numerical references as those provided for mixing equipment 201.

The essential difference between the mixing equipment 1001 and mixing equipment 201 is that the mixing equipment 1001 has two injection apparatuses 208A and 208B that are of the same type as injection apparatus 208. Thus, the second inlet 223A of injection apparatus 208A is provided via a pipe 224A with additional material from a container 225A. Valve means 226A and flow rate metering 227A is provided to control and monitor the flow of material from the container 225A to the injection apparatus 208A. Similarly, the second inlet 223B of the injection apparatus 208B is supplied via a pipe 224B with additional material stored in the container 225B. Again, valve means 226B and flow rate metering 227B are provided to monitor and control the rate of flow of material from the container 2258 to the injection apparatus 223B.

As will be appreciated, additional materials of different types may be stored within the containers 225A and 225B and appropriate valve means and flow rate metering provided on the respective pipes 224A and 224B. For example, a liquid may be stored within a suitable container 225A and supplied to injection apparatus 208A while a gas may be stored within 225B and supplied to the other injection apparatus 208B. In one such example, a liquid pigment is stored within the first container 225A while a blowing agent is stored within the second container 225B. Alternatively, the material stored in the two containers 225A and 225B may be of the same physical phase, i.e. the two containers may both contain a gas, or alternatively a liquid, or alternatively particulate solid material. For example, different coloured liquid pigments may be stored within the two containers 225A and 225B and their flow rates individually controlled to vary the colour of polyurethane produced by the mixing equipment 1001.

Furthermore, the material stored within the two containers 225A and 225B may be identical such that the same type of material is supplied through injection apparatuses 208A and 208B. This may be particularly appropriate where a flow rate, of say a solid material, cannot be made sufficiently large through just one of the two injection apparatuses.

Figure 11 Further mixing equipment 1101 embodying the present invention is shown in Figure 11. The mixing equipment 1101 has many components in common with mixing equipment 201 and where the components of mixing equipment 1101 are common to the mixing equipment 201 the same labelling has been used in Figure 11.

The mixing equipment 1101 differs from mixing equipment 1001 in that the storage container 225A is specifically adapted for containing particulate solid material and a transportation means 1102 for transporting particulate material is used to force material from the storage container 225A towards the injection apparatus 208A. In the present example, the transportation means 1102 is an Archimedes' screw that is supplied with the additional material by gravity feed from a hopper 225A.

In one example of the mixing equipment 1101, particulate carbon fibre material is stored within the hopper 225A and supplied by the mechanical transportation means 1102 to the injection apparatus 208A. The storage container 225B contains a liquid pigment for supply to the injection apparatus 208B. During operation of the mixing equipment 1101 the additional material is supplied simultaneously from the storage container 225A and the storage container 225B to produce a coloured polyurethane material comprising the solid particulate material stored in container 225A.

Figures 12 & 13 In the above-described mixing equipment the injection apparatus 208, 208A or 208B is arranged separately to the valve means 226, 226A or 226B.

A potential problem with such an arrangement exists during periods of time immediately before and after production of polyurethane. During these periods, the production piston is located in its forward position and liquid chemical reagent emitted from the injection apparatus is recycled back to the storage container. However, although the effect is reduced in magnitude, the flow of liquid chemical reagent past the outlet 609 of the throttle member 502 continues to have the effect of drawing material from that outlet. Consequently, if additional material is present within the passageway 608 of the throttle member it will be drawn into the flow of the liquid chemical reagent being returned to its storage container. Thus, over a period of time, the additional material would contaminate the liquid chemical reagents within the storage containers.

One way of avoiding such a problem is to ensure that the valve means 226, 226A, 226B are opened only after the production piston has being retracted and then closed a predetermined period before the production piston is moved forward to terminate the production process. Thus, initially liquid chemical reagents is passed through the injection apparatus 208, 208, or 208B with the production piston 212 forward so that the reagents are returned

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to their storage containers. During this period, the valve means 226, 226A, 226B remain closed so that no additional material is present in the passageway 608 of the injection apparatus. The production piston 212 is then retracted to commence mixing of the liquid chemical reagents, and the valve means 226, 226A or 226B are opened to allow additional material to flow through the passageway 608 and into the flow of the liquid chemical reagent. A predetermined time before mixing is to be stopped, the valve means 226, 226A, 226B are closed to allow a degree of mixing to take place that draws away material remaining within the passageway 608. The mixing operation is then ended by moving the production piston 212 forward, thereby redirecting the liquid chemical reagents emitted from the injection apparatus back to their storage containers. By this time, the injection apparatus 208, 208A, 208B is sufficiently free of additional material such that contamination of the returned liquid chemical reagents is avoided.

However, to avoid any potential problems of residual additional material entering into the returned liquid chemical reagents, in one embodiment, an injection apparatus is envisaged in which a valve mechanism is provided within the injection apparatus itself close to its outlet. An injection apparatus 1208 with an internal valve mechanism 1200 is shown in Figures 12 and 13. The valve mechanism is shown in its open position in Figure 12 and in its closed position in Figure 13.

The injection apparatus 1208 includes an outer body, 1201 that is identical to the outer body 501 of injection apparatus 208 (as per Figures 6 and 7), a throttle member 1202 that is similar to the throttle member 502, and the valve mechanism 1200.

Being identical to the outer body 501, the outer body 1201 has an inlet 404, a bore 601, an internal conical surface defining a first flow control surface 703 and a first outlet 1225.

Like throttle member 502, the throttle member 1202 has an external conical surface 704 defining a second flow control surface that co-operates with the first flow control surface 704 to define a constriction. The throttle member 1202 also has an outer surface 606 which, in co-operation with the bore 601 of the outer body 1201 defines a channel 607 between the inlet 404 and constriction formed by the surfaces 703 and 104. However, the throttle member 1202 differs from throttle member 502 in that it has a wide cylindrical passageway 1203 extending from its threaded portion 1204, adjacent its rear end, to a conical inner surface 1205 adjacent to its outlet 1209.

The injection apparatus also includes an elbow piece 1210 is fitted to the end of the throttle member 1201 by means of a threaded spigot 1211 on the elbow piece located within the threaded portion 1204. The elbow piece 1210 is provided with a passageway from its inlet 1212 to its outlet 1213 to allow additional material to be passed through the inlet 1212, through the outlet 1213 and into the passageway 1203 of the throttle member 1202. Thus, additional material may be supplied to the outlet 1209 of the throttle member 1202 and drawn into a flow of liquid chemical reagent ejected from the outlet 1225 of the injection apparatus 1208.

The elbow piece 1210 includes an additional bore 1214 that is coaxial with the bore 1203 of the throttle member 1202. An actuating mechanism 1216 is mounted on the elbow piece 1210, and an elongated valve element 1215 extends from the actuating mechanism 1216 to a free end 1217 that is located adjacent to the outlet 1209 of the throttle member 1202. The free end 1217 has a conical tip 1218 having a surface arranged to rest against the inner conical surface 1205 of the throttle member 1202 to provide a seal as shown in Figure 13. The actuating mechanism 1216 is provided in the present example by a solenoid that acts upon the valve element 1215 to move it from the retracted position of Figure 12 to the forward position of Figure 13 and from the forward position to the retracted position. Thus, the valve member 1215 is moveable to its retracted position to allow additional material to escape through the outlet 1209, and into its forward position to seal the outlet 1209 to prevent material escaping from the bore 1203 of the throttle member 1202.

Claims

Claims 1. Apparatus for injecting a liquid chemical reagent into a mixing chamber to mix with a second chemical reagent, said apparatus comprising: an outer body having a bore, a first inlet for allowing liquid chemical reagent to be supplied to said bore, a first control surface and an first outlet for allowing liquid chemical reagent to be expelled from said bore; a throttle member extending through at least a porUon of said bore of said outer body, said throttle member having a second control surface arranged to co-operate with said first control surface to provide a constriction, such that said first inlet, said constriction and said first outlet define a flow path for liquid chemical reagent supplied to said first inlet, wherein said apparatus defines a passageway extending from a second inlet to a second outlet, such that said second outlet is located along said flow is path between said constriction and said first outlet.
2. The apparatus of claim I wherein said passageway is formed through said throttle member.
3. The apparatus of claim 2 wherein said second outlet is coaxial with said first outlet.
4. The apparatus of claim 2 or claim 3 wherein said throttle member and said outer member extend along a common axis and said passageway extends along said common axis.
5. The apparatus of any one of claims I to 4 further comprising a valve means moveable between an open position allowing a flow of material from said second inlet to said second outlet and a closed position preventing such a flow.
6. The apparatus of claim 5 wherein: said passageway is defined by an inner surface of said throttle member; and said valve means comprises a moveable closing member located within said passageway and configured to provide a seal against said inner surface when said valve means is in said closed position.
7. The apparatus of any one of claims I to 6 wherein said apparatus comprises a manifold having a plurality of inlets and an outlet connected to said passageway.
8. The apparatus of any one of claims I to 7 wherein said apparatus comprises a metering device for measuring a rate of flow of material to said second inlet.
9. The apparatus of any one of claims I to 8 wherein said apparatus comprises a pumping device for providing a flow of material to said second inlet.
10. Mixing equipment for producing material by a chemical reaction between a first chemical reagent and a second chemical reagent, comprising the apparatus of any one of claims I to 9.
II. Mixing equipment for producing material by a chemical reaction between a first chemical reagent and a second chemical reagent, comprising a first apparatus for injecting a liquid chemical reagent into a mixing chamber and a second apparatus for injecting a liquid chemical reagent into a mixing chamber, wherein said first apparatus and second apparatus are as claimed in any one of claims I to 9.
12. A method of injecting a liquid chemical reagent into a mixing chamber to mix with a second chemical reagent, said method comprising: forcing a liquid chemical reagent through a constriction such that said liquid chemical reagent travels from said constriction and through a first outlet to an impingement location where said liquid chemical reagent collides with a second liquid chemical reagent; and providing a supply of an additional material to a second outlet such that said liquid chemical reagent passes through said constriction past said second outlet and carries said additional material from said second outlet through said first outlet to said impingement location.
13. A method of injecting a liquid chemical reagent in accordance with claim 12 wherein said additional material is injected through said second outlet at a pressure above atmospheric pressure.
14. A method of injecting a liquid chemical reagent in accordance with.is claim 12 wherein said additional material is drawn through said second outlet due to the flow of liquid chemical reagent past said second outlet causing a pressure of less than atmospheric pressure at said second outlet.
15. A method of injecting a liquid chemical reagent in accordance with any one of claims 12 to 14 wherein said additional material is a fluid.
16. A method of injecting a liquid chemical reagent in accordance with claim 15 wherein said fluid is a gas.
17. A method of injecting a liquid chemical reagent in accordance with claim 16 wherein said fluid is a gas at atmospheric pressure.
18. A method of injecting a liquid chemical reagent in accordance with claim 17 wherein said gas is selected from the group: carbon dioxide; pentane; air.
19. A method of injecting a liquid chemical reagent in accordance with claim 15 wherein said fluid is a liquid.
20. A method of injecting a liquid chemical reagent in accordance with claim 19 wherein said liquid comprises a pigment for colouring material produced by a reaction between said liquid chemical reagent and a second chemical reagent.
21. A method of injecting a liquid chemical reagent in accordance with claim 12 wherein said additional material comprises particulate solid material.
22. A method of injecting a liquid chemical reagent in accordance with claim 21 wherein said particulate solid material comprises hollow spheres.
23. A method of injecting a liquid chemical reagent in accordance with claim 22 wherein said spheres are formed of a polymeric material.
24. A method of injecting a liquid chemical reagent in accordance with claim 22 wherein said spheres are glass microspheres.
25. A method of injecting a liquid chemical reagent in accordance with claim 21 wherein said additional material comprises carbon fibres.
26. A method of injecting a liquid chemical reagent in accordance with claim 12, further comprising forcing said second liquid chemical reagent through a second constriction such that said second liquid chemical reagent travels from said second constriction and through a further first outlet to said impingement location; and providing a supply of a second additional material to a further second outlet such that said second liquid chemical reagent passes through said second constriction past said further second outlet and carries said second additional material from said further second outlet through said further first outlet to said impingement location.
27. A method of injecting a liquid chemical reagent in accordance with claim 26 wherein said second additional material is the same type of material as said additional material.
28. A method of injecting a liquid chemical reagent in accordance with claim 26 wherein said second additional material is a different type of material from said additional material.