Apparatus for injecting particulate insulant material

Abstract

An apparatus for injecting a blend of EPS bead and aerogel particles into a wall or sub-floor cavity comprising a first unit adapted to supply EPS bead to a dispensing 5 head and a second unit adapted

Description

FIELD OF THE INVENTION This invention relates to an apparatus for injecting particulate insulant material into wall and sub-floor cavities and in particular to an apparatus for injecting a blend of expanded polystyrene (EPS) bead insulation and aerogel bead into a wall or subfloor cavity. BACKGROUND OF THE INVENTION There’s a growing realisation globally that we will need to maximise the insulation of our buildings to reduce energy consumption as part of the goal of reaching net zero by 2050. The majority of houses that will be in existence in 2050 have already been built. A large portion of these houses in many countries are of cavity wall construction. This construction form consists of an outer leaf of masonry with a dividing airspace (cavity) and then an inner leaf of masonry. The most simple way to insulate these properties is by injecting particulate insulant material into the cavity. It is known to inject expanded polystyrene (EPS) particulate bead, with or without a bonding adhesive, into cavity wall constructions by providing a series of boreholes through one skin of the wall (typically the outer skin) and using bead injection guns fitted with nozzles that fit into the bore holes. The EPS bead is then injected into the cavity wall using a compressed air system. The flow of compressed air forces the beads through the bore hole and causes the bead to be pushed against the opposite skin of the wall, where the bead rebounds off and falls down to fill the vertical space beneath. The injection system has been designed to use a combination of compressed air and gravity to ensure that the injected bead fills the vertical space correctly. These systems are often referred to as “blown bead” cavity wall insulation. Typically a bonding agent, such as a liquid adhesive, is added to the beads so that they become bonded together once settled within the cavity. The bonding agent is typically mixed with the beads within the bead injection gun. However, as the cavity of a given wall is of predetermined width, there is a finite thickness of insulation which can be injected into the cavity. The only way to improve thermal insulation of the cavity is to use better insulants to improve the overall thermal efficiency of the building and reduce the heat loss. Aerogel is becoming increasingly chosen as an insulant in the construction of new buildings due to its very high thermal insulation properties. Aerogel is made from nano-porous silica and can be formed into beads. Aerogel provides a high thermal insulation performance. However, aerogel is very expensive compared to EPS bead. Furthermore, aerogel bead has a delicate, nanocell structure. This structure means the material can be damaged I broken up as it is moved, making it difficult to inject into a cavity wall using existing equipment intended for injecting EPS bead. The nanocell structure of aerogel also means that any moisture within a composition including aerogel will be drawn into the aerogel and away from the mixture. A blend of EPS bead and aerogel bead may provide improved u value compared to EPS bead alone. However, existing systems for injecting particulate insulant material into a cavity wall have been found not be suitable for injecting a blend of EPS beads and aerogel particles and therefore aerogel bead has been rejected as a means for improving cavity wall insulation. An object of the invention is to provide an apparatus for injecting particulate insulant material adapted to inject a blend of EPS beads and aerogel beads and overcome the problems encountered by the prior art. SUMMARY OF THE INVENTION In accordance with the present invention there is provided an apparatus for injecting a blend of EPS bead and aerogel bead into a wall or sub-floor cavity comprising a first unit adapted to supply EPS bead to a dispensing head and a second unit adapted to supply aerogel beads to the dispensing head, the dispensing head being adapted to blend the mixture of EPS bead, aerogel particles and adhesive and inject said blend into a cavity, wherein said dispensing head comprises a hollow cuboid body defining a mixing chamber, an outlet nozzle extending from said mixing chamber adapted to be inserted into a bore hole for dispensing a mixture of EPS bead, aerogel particles and adhesive a cavity, a compressed air inlet being adapted to supply compressed air into said mixing chamber and an EPS bead inlet adapted to supply EPS bead into the mixing chamber from the said first unit, an adhesive inlet being provided for delivering said adhesive into the mixing chamber to be mixed with the particulate insulant material before it is dispensed from the outlet nozzle, an aerogel inlet being provided in a portion of the outlet nozzle adjacent the mixing chamber adapted to receive aerogel particles from the second unit. Preferably said aerogel inlet is angled forwardly with respect to the outlet nozzle extending at an angle of approximately 15° to an axis extending perpendicular to a central axis of the outlet nozzle. More preferably the side walls of said portion of the outlet nozzle into which the aerogel inlet extends taper inwardly towards an outlet end of the outlet nozzle at an angle of between 6° to 8°, more preferably 7°, to the central axis of the outlet nozzle. The compressed air inlet of the mixing chamber may be axially aligned with said outlet nozzle. The EPS bead inlet may extend forwardly and downwardly into a rear end of the mixing chamber above the compressed air inlet. The adhesive inlet of the mixing chamber may be defined by a spray nozzle to disperse the adhesive into the particulate insulant material. In one embodiment the first unit may comprise a storage hopper containing a supply of EPS bead, a compressor for compressing air, a pressurised storage reservoir containing a supply of adhesive and a supply hose leading from the first unit to the dispensing head, said supply hose containing a first supply line for supplying EPS bead entrained in compressed air to the dispensing head and a second supply line for supplying adhesive to the dispensing head, and a controller for controlling the operation of the first unit. The second unit may comprise a storage hopper containing a supply of aerogel particles, a compressor for compressing air, a pump for pumping aerogel particles from the storage vessel to the dispensing head, the pump being powered by compressed air from the compressor, and a controller. Preferably the pump comprises a diaphragm pump. The first unit may be mounted on the back of a vehicle and the second unit may be mounted on a trailer to be towed by said vehicle. BRIEF DESCRIPTION OF THE DRAWINGS An apparatus for injecting particulate insulant material will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic view of an apparatus for injecting particulate insulant material in accordance with an embodiment of the present invention; Figure 2 is a side view of an injection gun of the apparatus of Figure 1; and Figure 3 is a sectional view of the injection gun of Figure 2 cut on a vertical plane. DETAILED DESCRIPTION OF THE DRAWINGS As illustrated in Figure 1, an apparatus for injecting a blend of EPS bead and aerogel particles (in the form of beads or powder but hereinafter referred to as “bead”) into a wall or sub-floor cavity in accordance with an embodiment of the present invention comprises a first unit 2 adapted to supply EPS bead to a dispensing head 6 and a second unit 4 adapted to supply aerogel bead to the dispensing head 6, the dispensing head 6 being adapted to blend the mixture of EPS bead, aerogel bead and adhesive and inject said blend into a cavity. The first unit 2 comprises a storage hopper 10 containing a supply of EPS bead, a compressor 12 for compressing air, a pressurised storage reservoir 14 containing a supply of adhesive and a supply hose 16 leading from the first unit 2 to the dispensing head 6, said supply hose 16 containing a first supply line for supplying EPS bead entrained in compressed air to the dispensing head 6 and a second supply line for supplying adhesive to the dispensing head 6, and a controller 18 for controlling the operation of the first unit 2. The second unit 4 comprises a storage hopper 20 containing a supply of aerogel bead, a compressor 22 for compressing air, a pressurised storage reservoir 24 containing a supply of adhesive, a pump 26 for pumping aerogel bead from the storage vessel 24 to the dispensing head 6, the pump 26 being powered by compressed air from the compressor 22, and a controller 28. The pump 26 may comprise a diaphragm pump specially adapted so as not to damage the delicate structure of the aerogel bead. The first unit 2 may be mounted on the back of a vehicle and the second unit 4 may be mounted on a trailer to be towed by said vehicle. This may allow the first unit 2 to be used alone to inject just EPS bead into a cavity or in combination with the second unit 4 to inject a mixture of EPS bead and aerogel bead into a cavity. As illustrated in Figures 2 and 3, the dispensing head 6 in preferably the form of an injection gun having a hollow cuboid body defining a mixing chamber 30, an outlet nozzle 32 extending from said mixing chamber 30 adapted to be inserted into a bore hole for dispensing a mixture of EPS bead, aerogel bead and adhesive a cavity, a compressed air inlet 34 being adapted to supply compressed air into said mixing chamber 30 and an EPS bead inlet 36 adapted to supply EPS bead into the mixing chamber 30 from the first unit. The compressed air inlet 34 is preferably axially aligned with said outlet nozzle 32. The EPS bead inlet 36 extends forwardly and downwardly into a rear end of the mixing chamber 30 above the compressed air inlet 34. A bonding agent inlet 35 is provided for delivering a bonding agent into the mixing chamber 30 to be mixed with the particulate insulant material before it is dispensed from the outlet nozzle 32. A bonding agent (e.g. suitable liquid adhesive) is supplied to the bonding agent inlet 35 from the pressurised reservoir of either unit 2,4 via a flexible supply line. The flow of bonding agent into the mixing chamber 30, which may be via a suitable spray nozzle to disperse the bonding agent into the particulate insulant material, is controlled by a bonding agent flow control valve provided on the body of the dispensing head 6. An aerogel inlet 38 is provided in a portion 35 of the outlet nozzle 32 adjacent the mixing chamber 30. The aerogel inlet 38 is angled forwardly with respect to the outlet nozzle 32 extending at an angle of 15° to an axis extending perpendicular to the axis of the outlet nozzle 32. Furthermore, the portion 35 of the outlet nozzle 32 into which the aerogel inlet 38 extends tapers down (converges) towards an outlet end of the outlet nozzle 32 at a taper angle of 7°. This arrangement enables allow the additional mixing of additional adhesive required with the EPS bead and aerogel bead mix and still allow for the venturi effect to efficiently pump the bead / aerogel / adhesive mixture into the required spaces for insulation. The outlet end of the nozzle 32 downstream of the tapered portion is preferably tubular with parallel sides. The injection angle of the aerogel inlet 38 into the nozzle 32 is critical as this has been found to allow the introduction of the aerogel particles to the EPS bead and adhesive mixture without destroying the delicate structure within the aerogel bead themselves. The pump 26 is controlled by the controller 28 to supply aerogel bead to the dispensing head 6 to ensure the correct hybrid ratio of EPS bead, glue and aerogel is mixed in the injection gun. A preferred ratio is 4:1:5 (EPS bead:Aerogel bead:Adhesive) within acceptable tolerance ranges of + / -10%. The water content of the adhesive is increased to combat the aerogels tendency to absorb moisture from the mix The Thermal performance uplift resulting from the use of the present invention to supply a predetermined mixture of EPS bead and aerogel bead over the use of standard EPS bead insulants has been found to be between 10% and 15% for a ratio of aerogel to eps bead of 3% to 10% . A pneumatic powered powder pump 26 is preferably be used to transfer the aerogel bead at the correct dosing rate to the tapered nozzle 32 of the injection gun. The powder pump 26 is controlled via a dedicated air compressor and air regulator unit provided in the second unit 4. Compared to known injection guns used with EPS bead, the injection gun in accordance with the present invention has been significantly modified, increasing the size of the mixing chamber 30 and outlet nozzle 32 The mixing chamber 30 incorporates of three material inlets, one used for compressed air, one used for bead delivery and one for adhesive. The jet size of the bonding agent inlet 35 has been increased signification to allow for the significant increase in adhesive being added. The opening of the injection gun has been increased to 80mm to accommodate the increased amount of materials entering the injection gun chamber. The nozzle has been subsequently designed to taper down to 22mm or 26mm, the injection nozzle also has had a port added to the outlet nozzle 32 to allow the addition of aerogel to the bead / adhesive mix before being injected into the cavity. Due to the large surface area of the aerogel particles, there was a requirement to develop an adhesive to ensure a bonded material. Through multiple iterations of different adhesive and water mixes, it has been found that it was necessary to use double the amount of standard adhesive, and also dilute the adhesive by half to overcome the absorption of the aerogel particles within the mix. This requires much larger adhesive jet nozzles to accommodate requirement to deliver the greater volume of adhesive into in the mixing chamber 32. The adhesive may be passed through an additional diaphragm transfer pump and pumped into the injection gun, rather than using a pressurized adhesive transfer system alone. The invention is not limited to the embodiment described herein but can be amended or modified without departing from the scope of the present invention.

Claims

1. An apparatus for injecting a blend of EPS bead and aerogel particles into a wall or sub-floor cavity comprising a first unit adapted to supply EPS bead to a dispensing head and a second unit adapted to supply aerogel particles to the dispensing head, the dispensing head being adapted to blend the mixture of EPS bead, aerogel particles and adhesive and inject said blend into a cavity, wherein said dispensing head comprises a hollow cuboid body defining a mixing chamber, an outlet nozzle extending from said mixing chamber adapted to be inserted into a bore hole for dispensing a mixture of EPS bead, aerogel particles and adhesive a cavity, a compressed air inlet being adapted to supply compressed air into said mixing chamber and an EPS bead inlet adapted to supply EPS bead into the mixing chamber from the said first unit, an adhesive inlet being provided for delivering said adhesive into the mixing chamber to be mixed with the particulate insulant material before it is dispensed from the outlet nozzle, an aerogel inlet being provided in a portion of the outlet nozzle adjacent the mixing chamber adapted to receive aerogel particles from the second unit.

2. An apparatus as claimed in claim 1, wherein said aerogel inlet is angled forwardly with respect to the outlet nozzle extending at an angle of 15° to an axis extending perpendicular to a central axis of the outlet nozzle.

3. An apparatus as claimed in claim 2, wherein side walls of said portion of the outlet nozzle into which the aerogel inlet extends converge towards an outlet end of the outlet nozzle at an angle of between 6° to 8°, more preferably 7°, to the central axis of the outlet nozzle.

4. An apparatus as claimed in ant preceding claim, wherein said compressed air inlet of the mixing chamber is axially aligned with said outlet nozzle.

5. An apparatus as claimed in claim 4, wherein said EPS bead inlet extends forwardly and downwardly into a rear end of the mixing chamber above the compressed air inlet.

6. An apparatus as claimed in any preceding claim, wherein said adhesive inlet of the mixing chamber is defined by a spray nozzle to disperse the adhesive into the particulate insulant material.

7. An apparatus as claimed in any preceding claim, wherein said first unit comprises a storage hopper containing a supply of EPS bead, a compressor for compressing air, a pressurised storage reservoir containing a supply of adhesive and a supply hose leading from the first unit to the dispensing head, said supply hose containing a first supply line for supplying EPS bead entrained in compressed air to the dispensing head and a second supply line for supplying adhesive to the dispensing head, and a controller for controlling the operation of the first unit.

8. An apparatus as claimed in any preceding claim, wherein the second unit comprises a storage hopper containing a supply of aerogel particles, a compressor for compressing air, a pump for pumping aerogel particles from the storage vessel to the dispensing head, the pump being powered by compressed air from the compressor, and a controller.

9. An apparatus as claimed in claim 8, wherein said pump comprises a diaphragm pump.

10. An apparatus as claimed in any preceding claim, wherein the first unit is mounted on the back of a vehicle and the second unit is mounted on a trailer to be towed by said vehicle.

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