WO2018152085A1

WO2018152085A1 - Self de-icing fan blade for hot products

Info

Publication number: WO2018152085A1
Application number: PCT/US2018/017940
Authority: WO
Inventors: Michael D. Newman
Original assignee: Linde Aktiengesellschaft
Priority date: 2017-02-17
Filing date: 2018-02-13
Publication date: 2018-08-23
Also published as: EP3364041A1

Abstract

A fan blade includes a surface, an interior space within the fan blade, and a plurality of holes at the surface and in fluid communication with the interior space and from which a high pressure cryogenic gas is ejected for cleaning the surface of the fan blade. A corresponding self-cleaning fan is also provided.

Description

SPECIFICATION

TITLE: SELF DE-ICING FAN BLADE FOR HOT PRODUCTS

BACKGROUND

[0001] The present embodiments relate to fans and fan blades used in tunnel freezers such as for example cryogenic tunnel freezers for food products.

[0002] Axial flow fans are used in cryogenic tunnel freezers. When hot steamy products, such as for example food products, are frozen in cryogenic processes, ice and snow accumulate on the surfaces of the axial flow fan blades. This snow and ice accumulation creates two main issues. First, performance of the fan blade diminishes because the blade cannot move gas as efficiently, resulting in lower volumetric and velocity flow from the fan. This equates to lower overall heat transfer coefficients in the freezing process and decreased production rates. Second, the fan becomes imbalanced, causing vibration which affects the bearings in the motor driving the fans. Bearings fail prematurely and motors must be replaced more frequently. The freezer becomes susceptible to downtime to do repairs, leading to greater inefficiencies in the freezing process.

SUMMARY

[0003] The present embodiments enable the fans to shed snow and ice during operation, and overcome the problematic issues outlined above with respect to known axial flow fans.

[0004] A self-cleaning fan is provided herein which includes a blade having a interior space and a plurality of holes along the blade in fluid communication with the interior space; a rotary coupling, mounted to and operativeiy associated with the blade, the rotary coupling having an interior portion in fluid communication with the interior space and a source of cryogenic gas; and a valve interposed between the interior portion of the rotary coupling and the cryogenic gas source for selectively releasing a high pressure flow of the cryogenic gas into the interior portion and through the interior space for discharge from the plurality of holes onto a surface of the blade without having to cease rotation of the blade.

[0005] A fan blade is also provided herein which includes an interior space and a plurality of holes in fluid communication with said interior space and from which a high pressure cryogenic gas is ejected for cleaning a surface of the fan blade.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] For a more complete understanding of the present invention, reference may be had to the following description of exemplary embodiments considered in connection with the accompanying drawing Figures, of which:

[0007] FIG. 1 shows a side view of a fan embodiment of the present invention;

[0008] FIG. 2 shows a cross-section view of a fan blade of the fan embodiment shown in FIG. 1 ; and

[0009] FIG. 3 shows a partial view in cross-section of a tunnel freezer in which the fan embodiment of FIG. 1 is disposed for operation. DETAILED DESCRIPTION OF THE INVENTION

[0010] Before explaining the inventive embodiments in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, if any, since the invention is capable of other embodiments and being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

10011] In the following description, terms such as a horizontal, upright, vertical, above, below, beneath and the like, are to be used solely for the purpose of clarity illustrating the invention and should not be taken as words of limitation. The drawings are for the purpose of illustrating the invention and are not intended to be to scale.

[0012] In general, the present embodiments include fan blades constructed with an interior void for pressurization with high pressure nitrogen gas (or CO2 gas). The surface of the blade includes a plurality of small holes which restrict gas flow and create high velocity jets of nitrogen gas when the fan blade void is pressurized.

[0013] Additionally, a rotary coupling is installed for operation with the fan. An electrically powered fan motor is mounted to the roof of a food freezer and connected by a shaft to the rotary coupling. The fan motor rotates the fan blade a speeds of from 1750 to 3500 revolutions per minute (rpm). The rotary coupling includes an interior annular space or chamber portion which is provided or fed with high pressure nitrogen gas through a high flow valve from a high pressure buffer storage tank. The buffer storage tank can be filled with the high pressure nitrogen gas over a select duration of time. That is, the storage tank does not require a fast recharge (refill) time period and therefore, the flow rate of the nitrogen gas into said tank can be done over a period of minutes. For example, it may take twenty (20) minutes to refill the storage tank, but the cycle of using the gas in the present embodiments may, for example, be only three (3) seconds.

[0014] When a de-icing cycle for the fan blade is needed in order to clear same of accumulated snow and ice, the high flow valve is opened to release the high pressure nitrogen gas to the annular space of the rotating fan blade, which gas is then discharged through the plurality of holes in the blade. The tight spacing and close proximity of the holes with each other on the blade enables the high pressure-high velocity nitrogen gas to contact any snow and ice on the blade surface for removal therefrom.

[0015] Referring now to FIGS. 1-3, a self de-icing fan blade of the present embodiments is shown generally at 10 and includes a body portion 12 having an exterior surface 14 and defining an internal chamber 16, annular space or void within the blade. The chamber 16 can assume the proportions of and also be referred to as an annular space 16. As shown in FIG. 1 , the fan 10 referred to may have a plurality of blades 12, each one of which is joined to a rotary coupling 18, or be considered as a single blade to which the rotary coupling is interposed as a central, unifying member. With either construction, the rotary coupling 18 transmits a rotating force to the fan blade 12 for generating an axial gas flow 19 to products 20, such as for example food products, to be chilled and/or frozen as described below. The rotary coupling 18 provides a passageway 20 therethrough for high pressure nitrogen gas to be fed or directed to the chamber 16 of the blade along the blades' axis of rotation while same is rotating or spinning, as indicated with arrow 22. A high pressure rotary seal disposed in the rotary coupling 18 allows a hub of the coupling to rotate and the gas feed pipe 24 to remain stationary.

[0016] The fan blade 10 includes a plurality of holes 26 and for certain applications a myriad of the holes, in close proximity to each other along the surface 14 of the fan blade, each one of the holes in fluid communication with the annular space 16 of the fan blade for a purpose to be described hereinafter.

[0017] The rotary coupling 18 has an internal portion 28 in fluid communication with the annular space 16 of the fan blade 10 as shown in FIG. 1 , such that the cryogenic gas, such as for example gaseous nitrogen or gaseous CO2 can be directed through a passageway 30 of a shaft 32 into the rotary coupling and dispersed to the annular space 16 of the fan blade. As described hereinafter, pressurized gas 34 will be moved from the annular space 16 of the fan blade 10 through the plurality of holes 26 for the self -cleaning of the external surface 14 of the fan blade.

[0018] Referring to FIG. 3, the fan blade 10 embodiment may be mounted for operation in an internal space 36 or chamber of a freezer 38, such as for example a tunnel freezer for food products 20. As shown, the fan 10 is rotatably mounted to the shaft 32 which in turn is operationally associated with a motor 40 disposed at an exterior of the freezer 38 so as not to transfer heat from the motor to the internal chamber 36 of the freezer. A pipe 39 or fluid conduit extends along an exterior of freezer 38 and has one or a proximate end 46 (FIG. 2) of the pipe in fluid communication with the internal portion of the rotary coupling 18 such that cryogenic gas 34 under pressure can be introduced through the rotary coupling and into the annular space 16 of the fan blades. Another or a distal end 48 of the pipe 39 is in fluid communication with a buffer storage tank 50 for the cryogenic gas, which tank can be intermittently fed with the cryogenic gas such as nitrogen or CO2 gas from a remote source (not shown). In effect, the buffer tank 50 operates as an accumulator which is pressurized to ultimately provide the cryogen gas 34 to the annular space 16 of the fan blade 12 for cleaning the external surface 14 thereof at select time periods or intervals. A high flow valve 52 is interposed in the pipe 39 interconnecting the buffer tank 50 and the rotary coupling 18.

[0019] During operation, when a detrimental amount of snow and/or ice has accumulated on the exterior surface 14 of the self-cleaning fan 10, the buffer tank 50 is charged with the cryogen gas to a predetermined pressure, at which point the high flow valve 52 is opened causing said pressurized gas to be delivered through the pipe 39, through the rotary coupling 18 and into the annular space 16 of the fan blade 12 for expulsion through the plurality of holes 26 to dislodge and clean the accumulated snow and ice from the surface 14 of the fan blade(s). The expulsion of the gas from the holes 26 is in the form of jet sprays 56.

[0020] A conveyor belt 58 can be used to transport the products 20 through the space 36 of the freezer 38 so that the products are subjected to the chilling atmosphere in the space and contacted by the chilled axial gas flow 19.

[0021] The frequency of the de-icing can be adjusted based on the severity of the ice and snow accumulation on the fan blades 12.

[0022] The embodiments provided herein may also include said cryogenic gas being selected from the group consisting of nitrogen gas and CO2 gas.

[0023] It will be understood that the embodiments described herein are merely exemplary, and that a person skilled in the art may make variations and modifications without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as described herein and provided in the appended claims, ft should be understood that the embodiments described above are not only in the afternative, but can be combined.

Claims

CLAIMS What is claimed is:

1. A fan blade, comprising: a surface; an interior space within the fan blade; and a plurality of holes at the surface and in fluid communication with the interior space and from which high pressure cryogenic gas is ejected from the interior space for cleaning the surface.

2. The fan blade of claim 1 , wherein the interior space comprises an annular space.

3. The fan blade of claim 1 , further comprising a rotary coupling, and a passageway extending through the rotary coupling for the cryogenic gas to be directed to the interior space.

4. The fan blade of claim 3, wherein the rotary coupling comprises a high pressure rotary seal disposed in the rotary coupling, the high pressure rotary seal allowing a hub of the rotary coupling to rotate and a gas feed pipe for the rotary coupling to remain stationary.

5. The fan blade of claim 1 , wherein the high pressure cryogenic gas is selected from the group consisting of nitrogen gas and carbon dioxide gas.

6. The fan blade of claim 1 , wherein the fan blade is mounted for operation at an interior of a freezer.

7. The fan blade of claim 6, wherein the freezer comprises a cryogenic tunnel freezer.

8. A self-cleaning fan, comprising: a blade having an interior space and a plurality of holes along the blade in fluid communication with the interior space; a rotary coupling mounted to and operatively associated with the blade, the rotary coupling having an interior portion in fluid communication with the interior space and a source of cryogenic gas; and a valve interposed between the interior portion and the source of the cryogenic gas for selectively releasing a high pressure flow of the cryogenic gas into the interior portion and through the interior space for discharge from the plurality of holes onto a surface of the blade without having to cease rotation of the blade.

9. The self-cleaning fan of claim 8, wherein the blade comprises a surface in which the plurality of holes are disposed, the plurality of holes in fluid communication with the interior space.

10. The self-cleaning fan of claim 8, wherein the fan is rotatably mounted to a shaft which is operationally associated with a motor disposed at an exterior of a freezer so as not to transfer heat from the motor to an interior of the freezer.

11. The self-cleaning fan of claim 10, further comprising a pipe extending along an exterior of the freezer, the pipe having a proximate end in fluid communication with the interior portion such that the cryogenic gas can be introduced through the rotary coupling and into the interior space of the blade.

12. The self-cleaning fan of claim 11 , wherein the pipe comprises a distal end in fluid communication with a buffer tank for the cryogenic gas, the buffer tank being intermittently fed with the cryogenic gas from the source.

13. The self-cleaning fan of claim 12, wherein the buffer tank comprises an accumulator pressurized to ultimately provide the cryogenic gas to the interior space for cleaning the surface at select time intervals.

14. The self-cleaning fan of claim 10, further comprising a conveyor belt for transporting at least one product through the interior of the freezer.

15. The self-cleaning fan of claim 14, wherein the at least one product comprises at least one food product.