GB2071517A

GB2071517A - Heated filter vane

Info

Publication number: GB2071517A
Application number: GB8008305A
Authority: GB
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1980-03-12
Filing date: 1980-03-12
Publication date: 1981-09-23
Also published as: GB2071517B

Abstract

A component, such as an air intake filter vane 18 for a marine gas turbine engine, has a layer 30 of electrically conducting material through which an electric current can be passed to heat the component, so that icing of the component can be prevented. The electrically conducting layer 30 can be nickel and the component can have a band of copper 34 at each end to improve the electrical connection between the conducting layer and a source of electrical power. An outer layer 32 of epoxy resin can be provided to prevent erosion and corrosion. The component can be formed from a plastics material or a metal, in the latter case a layer 36 of plastics material is first applied to the component before applying the conducting layer 38. <IMAGE>

Description

SPECIFICATION Improvements in or relating to the heating of exposed components This invention relates to any exposed surface of simple or complex shape which it is required to heat. A typical example would be the application to any device for separating liquid droplets from air where it is required to heat a surface of the device and prevent ice formation, e.g. an air intake filter for a gas turbine engine, required to operate in a marine environment, e.g. on board ships, oil rigs and platforms, and in helicopters.

The corrosive effect of salt water on the engine components is kept to a minimum by a number of methods, one of which is to remove as much as possible of the salt water from the air supply to the engine by filters. Under low temperature conditions, the salt water can freeze on the vanes of the air filters and the ice which is formed can reduce the effectiveness of the filters, and in extreme cases, the filters can be completely blocked. If complete blockage does occur, then emergency intake doors open and the engine receives unfiltered salt water laden air.

The filter vanes are usually formed from a plastics material or an easily extruded metal, such as aluminium or an aluminium alloy, and the #invention proposes a modified form of filter vane which can be heated to prevent the formation of ice under low temperature conditions.

According to the present invention, there is provided exposed surface such as an air intake filter vane, the vane including a layer of electrically conducting material through which an electric current can be passed for heating purposes. An outer protective coating may be applied over the electrically conducting coating to prevent erosion, corrosion and short circuits.

If the filter vane is formed from a plastics material, the electrically conducting material may be applied directly to the plastics material, and if the filter vane is metal, a plastics material coating may be first applied to the metal and the electrically conducting material applied to the layer of plastics material.

The electrically conducting material may be a thin layer of nickel and the vane may have at each end, a band of copper to improve the electrical contact between the connections to an electrical power source and the electrically conducting layer.

The present invention will now be more particularly described, with reference to the accompanying drawings in which, Figure 1 and associated Figures 1 a, 1 b and 1 c illustrate a marine gas turbine engine air intake filter, Figure 2 is an enlarged view of one of the filter vanes shown in Figure 1 a, Figure 3 is a section on line 3-3 in Figure 2, Figure 4 is an enlarged view of a different form of filter vane to that shown in Figure 1 a and, Figure 5 is a section on line 5-5 in Figure 4.

Referring to the Figures, a typical air intake filter 10 for a marine gas turbine engine (not shown) comprises a first stage louvre separator 12 to remove heavy salt water spray, a second stage coalescer filter 14 to remove small droplets and particles, and a third stage separator 16 for the removal of re-entrained droplets formed in high humidity conditions on the second stage 14.

The first and third stages 12, 1 6, each comprise a plurality of vertically arranged filter vanes 1 8, 20 respectively. The vanes define a tortuous path for the salt water laden air incoming air, and water droplets tend to flow into channels 22, 24 and thence into drains 26, 28 respectively.

In order to prevent the first and third stages of the filter from icing-up, the vanes of these stages are coated with a uniform thickness of an electrically conducting material 30 (Figure 3) the thickness of which is determined by the material used and the electrical power required to prevent, icing, the vanes all being connected to a source of electrical power, such as a generator. A typically suitable electrically conducting material would be a layer of nickel having a thickness in the range 0.00025" to 0.003". Conveniently such a layer can be applied by Permaiite Electroless method.

As shown in Figure 3, the nickel layer can have a protective layer 32 of clear 2 pack epoxy resin to DTD 5555 applied to it to prevent erosion, corrosion and short circuits. Additionally a band 34 of copper in the thickness range 0.002"-0.01 0" can be applied at each end of the filter vane to improve the electrical contact between the layer 30 and the electrical connections to the source of electrical power.

When the filter vanes are formed from a metal, such as aluminium or an aluminium alloy, as shown in Figures 4 and 5, a coating 36 of a plastics material, such as ABS or an epoxy resin is first applied to the vane, before applying a layer 30 of electrically conducting material and a protective layer 40, together with a copper band 42.

The layers 38, 40 and the band 42 can be of same materials and the same thickness ranges as described with reference to the embodiment of Figures 2 and 3.

1. A component having an exposed surface which in use is required to be heated, comprises a layer of electrically conducting material attached to the exposed surface, in use, an electric current being arranged to pass through the said layer to heat the component.

2. A component as claimed in claim 1 in which the electrically conducting coating comprises a layer of nickel.

3. A component as claimed in claim 1 or claim 2 having a further layer over the electrically conducting layer to prevent erosion and corrosion.

4. A component as claimed in claim 3 in which the said further layer is formed from an epoxyresin.

5. A component as claimed in any one of the preceding claims having at least a layer of copper in the form of a band in electrical contact with the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in or relating to the heating of exposed components This invention relates to any exposed surface of simple or complex shape which it is required to heat. A typical example would be the application to any device for separating liquid droplets from air where it is required to heat a surface of the device and prevent ice formation, e.g. an air intake filter for a gas turbine engine, required to operate in a marine environment, e.g. on board ships, oil rigs and platforms, and in helicopters. The corrosive effect of salt water on the engine components is kept to a minimum by a number of methods, one of which is to remove as much as possible of the salt water from the air supply to the engine by filters. Under low temperature conditions, the salt water can freeze on the vanes of the air filters and the ice which is formed can reduce the effectiveness of the filters, and in extreme cases, the filters can be completely blocked. If complete blockage does occur, then emergency intake doors open and the engine receives unfiltered salt water laden air. The filter vanes are usually formed from a plastics material or an easily extruded metal, such as aluminium or an aluminium alloy, and the #invention proposes a modified form of filter vane which can be heated to prevent the formation of ice under low temperature conditions. According to the present invention, there is provided exposed surface such as an air intake filter vane, the vane including a layer of electrically conducting material through which an electric current can be passed for heating purposes. An outer protective coating may be applied over the electrically conducting coating to prevent erosion, corrosion and short circuits. If the filter vane is formed from a plastics material, the electrically conducting material may be applied directly to the plastics material, and if the filter vane is metal, a plastics material coating may be first applied to the metal and the electrically conducting material applied to the layer of plastics material. The electrically conducting material may be a thin layer of nickel and the vane may have at each end, a band of copper to improve the electrical contact between the connections to an electrical power source and the electrically conducting layer. The present invention will now be more particularly described, with reference to the accompanying drawings in which, Figure 1 and associated Figures 1 a, 1 b and 1 c illustrate a marine gas turbine engine air intake filter, Figure 2 is an enlarged view of one of the filter vanes shown in Figure 1 a, Figure 3 is a section on line 3-3 in Figure 2, Figure 4 is an enlarged view of a different form of filter vane to that shown in Figure 1 a and, Figure 5 is a section on line 5-5 in Figure 4. Referring to the Figures, a typical air intake filter 10 for a marine gas turbine engine (not shown) comprises a first stage louvre separator 12 to remove heavy salt water spray, a second stage coalescer filter 14 to remove small droplets and particles, and a third stage separator 16 for the removal of re-entrained droplets formed in high humidity conditions on the second stage 14. The first and third stages 12, 1 6, each comprise a plurality of vertically arranged filter vanes 1 8, 20 respectively. The vanes define a tortuous path for the salt water laden air incoming air, and water droplets tend to flow into channels 22, 24 and thence into drains 26, 28 respectively. In order to prevent the first and third stages of the filter from icing-up, the vanes of these stages are coated with a uniform thickness of an electrically conducting material 30 (Figure 3) the thickness of which is determined by the material used and the electrical power required to prevent, icing, the vanes all being connected to a source of electrical power, such as a generator. A typically suitable electrically conducting material would be a layer of nickel having a thickness in the range 0.00025" to 0.003". Conveniently such a layer can be applied by Permaiite Electroless method. As shown in Figure 3, the nickel layer can have a protective layer 32 of clear 2 pack epoxy resin to DTD 5555 applied to it to prevent erosion, corrosion and short circuits. Additionally a band 34 of copper in the thickness range 0.002"-0.01 0" can be applied at each end of the filter vane to improve the electrical contact between the layer 30 and the electrical connections to the source of electrical power. When the filter vanes are formed from a metal, such as aluminium or an aluminium alloy, as shown in Figures 4 and 5, a coating 36 of a plastics material, such as ABS or an epoxy resin is first applied to the vane, before applying a layer 30 of electrically conducting material and a protective layer 40, together with a copper band 42. The layers 38, 40 and the band 42 can be of same materials and the same thickness ranges as described with reference to the embodiment of Figures 2 and 3. CLAIMS

5. A component as claimed in any one of the preceding claims having at least a layer of copper in the form of a band in electrical contact with the electrically conducting layer.

6. A component as claimed in any one of the preceding claims formed from a plastics material.

7. A component as claimed in any one of the preceding claims 1 to 5 formed from a metal or a metal alloy.

8. A component as claimed in claim 7 including a layer of plastics material between the component and the electrically conducting layer.

9. A marine gas turbine engine air intake filter vane constructed and arranged for use and operation substantially as herein described and with reference to the accompanying drawings.

9. A component as claimed in any one of the preceding claims in the form of an air intake filter vane.

10. An air intake filter vane constructed and arranged for use and operation substantially as herein described and with reference to the accompanying drawings.

New claims filed on 4 March 1981 Superseded claims 1-10 New or amended claims:~

1. A marine gas turbine engine air inlet vane having an exposed surface which in use is required to be heated, comprises a layer of electrically conducting material on the exposed surface, in use, an electric current being arranged to pass through the said layer to heat the component.

3. A vane as claimed in claim 1 or claim 2 having a further layer over the electrically conducting layer to prevent erosion and corrosion.

4. A vane as claimed in claim 3 in which the said further layer is formed from an epoxy-resin.

5. A vane as claimed in any one of the preceding claims having at least a layer of copper in the form of a band at each end of the vane in electrical contact with the electrically conducting layer.

6. A vane as claimed in any one of the preceding claims formed from a plastics material.

7. A vane as claimed in any one of the preceding claims 1 to 5 formed from a metal or a metal alloy.

8. A vane as claimed in claim 7 including a layer of plastics material between the vane and the electrically conducting layer.