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Title:
STRAINER WITH PRESSURE INDICATOR
Document Type and Number:
WIPO Patent Application WO/2017/119819
Kind Code:
A1
Abstract:
A filter device comprises: - a filter element (2) that is insertable into a pipe (9) for filtering a liquid and/or gaseous medium flowing through the pipe (9); - a filter flange (3) surrounding an end portion of the filter element (2) for attachment of the filter device to a corresponding pipe flange of the pipe (9); and - a first and a second pressure measurement connection (4) for connecting a respective first and second chamber formed on opposite sides of the filter element (2) to a respective first and second tapping point (5) on the filter flange (3).

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Inventors:
OPDAHL, Frode (Postboks 144, 1371 Asker, 1371, NO)
ABRAHAMSEN, Per (Postboks 144, 1371 Asker, 1371, NO)
Application Number:
NO2017/050002
Publication Date:
July 13, 2017
Filing Date:
January 05, 2017
Export Citation:
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Assignee:
WÄRTSILÄ OIL & GAS SYSTEMS AS (Postboks 144, 1371 Asker, 1371, NO)
International Classes:
B01D35/02; B01D29/60; B01D35/143
Domestic Patent References:
WO2000018487A12000-04-06
WO2001093982A12001-12-13
Foreign References:
EP2329872A22011-06-08
US20140083686A12014-03-27
Other References:
None
Attorney, Agent or Firm:
ZACCO NORWAY AS (Box 2003, Vika, 0125 Oslo, 0125, NO)
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Claims:
Filter device comprising:

- a filter element (2) that is insertable into a pipe (9) for filtering a liquid and/or gaseous medium flowing through the pipe (9);

- a filter flange (3) surrounding an end portion of the filter element (2) for attachment of the filter device to a corresponding pipe flange of the pipe (9); and

- a first and a second pressure measurement connection (4) for connecting a respective first and second chamber (10, 11) formed on opposite sides of the filter element (2) to a respective first and second tapping point (5) on the filter flange (3).

Filter device according to claim 1, wherein the first and/or the second tapping point (5) is provided on a tangential side surface of the filter flange (3).

Filter device according to any one of claims 1 or 2, wherein the first and/or second pressure measurement connections (4) comprise at least one tube leading from the filter flange (3) to the respective first and/or second chambers (10, 11).

Filter device according to any one of claims 1 to 3, wherein the first and/or second pressure measurement connections (4) comprise channels leading through the filter flange (3) to the respective tapping points (5).

Filter device according to any one of claims 1 to 4, wherein the first pressure measurement connection (4) comprises a channel leading through the filter flange (3) to an inner surface of the filter flange (3) which borders on the first chamber (10) on a first side of the filter element (2) and the second pressure measurement connection (4) comprises a tube leading from an inner surface of the filter flange (3) through the filter element (2) into the second chamber (11) on a second, opposite side of the filter element (2).

Filter device according to any one of claims 1 to 4, wherein the first pressure measurement connection (4) comprises a channel leading through the filter flange (3) to an inner surface of the filter flange (3) which borders the first chamber (10) on a first side of the filter element (2) and the second pressure measurement connection (4) comprises a channel leading through the filter flange (3) to a side surface of the filter flange (3) which borders on the second chamber (11) on a second, opposite side of the filter element (2).

7. Filter device according to any one of claims 1 to 6, wherein the first and second tapping points (5) are adapted for connection to a differential pressure instrument (7) for determining a pressure difference between the first and second chambers (10, 11).

8. Filter device according to any one of claims 1 to 7, wherein the filter element (2) comprises a conical shaped or a frustoconical shaped strainer.

9. Filter device according to any one of claims 1 to 8, wherein the filter flange (3) is formed integral with the filter element (2).

10. System (1) comprising a filter device according to any one of claims 1 to 9 and a differential pressure instrument (7) for determining and outputting a value corresponding to a differential pressure in the first and second chamber (10, 11) as detected via the first and second pressure measurement connections (4).

11. System (1) according to claim 10, wherein the differential pressure instrument (7) is attached to a tangential side surface of the filter flange (3) of the filter device.

Description:
STRAINER WITH PRESSURE INDICATOR

Background of the Invention

The present invention relates to a filter device and a system for filtering a liquid or gaseous medium flowing through a pipe.

The IGC code (International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in bulk) states the following:

5.6.6 Cargo filters

The cargo liquid and vapour systems shall be capable of being fitted with filters to protect against damage by extraneous objects. Such filters may be permanent or temporary, and the standards of filtration shall be appropriate to the risk of debris, etc., entering the cargo system. Means shall be provided to indicate that filters are becoming blocked, and to isolate, depressurize and clean the filters safely.

Hence, there is a need to provide a filter when loading and unloading a cargo liquid and vapour system, and there is further a need to monitor the filter performance in order to detect filter blockage.

It is thus an object of the present invention to provide a filter device and a system which fulfils the requirements for a cargo filter as specified by the IGC code cited above. It is a further object to provide a filter device and a system which has low manufacturing costs and which can be handled and replaced with ease for servicing and replacement.

Summary

This object is achieved by the claimed filter device and by the claimed system. A filter device comprises a filter element that is insertable into a pipe for filtering a liquid and/or gaseous medium flowing through the pipe and a filter flange surrounding an end portion of the filter element for attachment of the filter device to a corresponding pipe flange of the pipe. Thus, the filter element may be inserted at an end portion of a pipe, e.g. between a cargo manifold flange and a manifold spool piece flange when a liquid or gaseous cargo is loaded or unloaded. The manifold spool piece is an adapter piece made to fit a loading arm in one end and the cargo manifold flange in the other end. Typically a manifold spool piece is installed between the loading arm and the cargo manifold flange. The said spool piece is an adaptor allowing connection to loading arms of different sizes. The filter element will then typically be installed between the cargo manifold flange and the spool piece. The filter flange may then be secured between the cargo manifold flange and the loading arm flange for fastening the filter element inside the pipe and for ensuring that the liquid or gaseous cargo passes through the filter element. The filter device further comprises a first and a second pressure measurement connection for connecting a respective first and second chamber formed on opposite sides of the filter element to a respective first and second tapping point on the filter flange. Thus, the filter device is compact, can be inserted into a pipe and fastened at an existing flange interface without substantially increasing the overall length of the pipe assembly. The filter device further provides tapping points for determining a pressure difference between a first chamber on a first side of the filter element and a second chamber on an opposite chamber of the filter element so that a blockage of the filter can be reliably detected.

According to embodiments, the first and/or the second tapping point may be provided on a tangential side surface of the filter flange. Therein, the tangential surface of the flange may e.g. be a radially outer surface of the flange which is substantially cylinder shaped. Thus, the tapping points are accessible from the outside when the filter device is inserted between respective pipe flanges at a pipe interface. A differential pressure instrument can easily be connected to the tapping points for providing an indication of the pressure difference between the first and second chambers.

According to embodiments, the first and/or second pressure measurement connections may comprise tubes leading from the filter flange to the respective first and/or second chambers. These tubes may be fastened to any suitable surface of the filter element. One tube may be guided through the filter element to the second chamber.

According to embodiments, the first and/or second pressure measurement connections may comprise channels leading through the filter flange to the respective tapping points. These channels may either directly connect to the respective first or second chamber or they may be connected to respective tubes that lead to the respective first or second chamber.

According to one embodiment, the first pressure measurement connection may comprise a channel leading through the filter flange to an inner surface of the filter flange which borders on the first chamber on a first side of the filter element and the second pressure measurement connection may comprise a tube leading from an inner surface of the filter flange through the filter element into the second chamber on a second, opposite side of the filter element. Thus, the first chamber can be contacted without the need for any additional tubing by a channel provided in the filter flange, e.g. by a simple bore extending in a radial direction of the flange from a radially outer surface to a radially inner surface of the flange. At the same time, the second chamber can be contacted by a tube which may be led through e.g. an opening in a bottom surface of the filter element. The tube may be attached to a radially inner surface of the filter flange and may be in contact with a suitable bore for connecting the respective tapping point on the tangential outer surface of the filter flange.

According to an alternative embodiment, the first pressure measurement connection may comprise a channel leading through the filter flange to an inner surface of the filter flange which borders the first chamber on a first side of the filter element. The second pressure measurement connection may comprise a channel leading through the filter flange to a side surface of the filter flange which borders on the second chamber on a second, opposite side of the filter element.

According to embodiments, the first and second tapping points may be adapted for connection to a differential pressure instrument for determining a pressure difference between the first and second chambers. Thus, a differential pressure across the filter element can be determined and indicated by the differential pressure instrument while the filter device is fastened e.g. between a cargo manifold flange and a loading arm flange.

According to embodiments, the filter element may comprise a conical shaped or a frustoconical shaped strainer. Alternatively, the filter element may have any other suitable shape such as e.g. a cylinder, a disc or the like.

According to embodiments, the filter flange may be formed integral with the filter element. Thus, the filter device may be manufactured as a compact device with as few separate components as possible in order to reduce manufacturing costs and complexity.

According to a further aspect, a system comprising a filter device as described above is provided. The system further comprises a differential pressure instrument for determining and outputting a value corresponding to a differential pressure in the first and second chamber as detected via the first and second pressure measurement connections. Thus, the system provides an indication of the pressure drop across the filter element and thus enables the detection of a filter blockage in real time.

According to embodiments, the differential pressure instrument may be attached to a tangential side surface of the filter flange of the filter device. Thus, the differential pressure instrument is accessible when the filter device is fastened between two adjacent pipe flanges, and the overall dimensions of the system can be minimized. Brief description of the Drawings

Embodiments of the invention will now be described with reference to the drawings, in which like reference numerals denote the same or corresponding elements, and in which:

Fig. 1 shows a first view of an indicating wafer strainer according to embodiments;

Fig. 2 shows a further view of the indicating wafer strainer of Fig. 1;

Fig. 3 is a schematic drawing of a portion of a piping and instrumentation diagram for illustrating a possible use of the indicating wafer strainer of Fig. 1 and 2;

Fig. 4 is a cross-sectional schematic view of a first embodiment of an indicating wafer strainer; and Fig. 5 is a cross-sectional schematic view of a second embodiment of an indicating wafer strainer. Detailed description

In the following description of various embodiments, reference will be made to the drawings, in which like reference numerals denote the same or corresponding elements. The drawings are not necessarily to scale. Instead, certain features may be shown exaggerated in scale or in a somewhat simplified or schematic manner, wherein certain conventional elements may have been left out in the interest of exemplifying the principles of the invention rather than cluttering the drawings with details that do not contribute to the understanding of these principles.

It should be noted that, unless otherwise stated, different features or elements may be combined with each other whether or not they have been described together as part of the same embodiment below. The combination of features or elements in the exemplary embodiments are done in order to facilitate understanding of the invention rather than limit its scope to a limited set of embodiments, and to the extent that alternative elements with substantially the same functionality are shown in respective embodiments, they are intended to be interchangeable, but for the sake of brevity, no attempt has been made to disclose a complete description of all possible permutations of features.

Furthermore, those with skill in the art will understand that the invention may be practiced without many of the details included in this detailed description. Conversely, some well-known structures or functions may not be shown or described in detail, in order to avoid unnecessarily obscuring the relevant description of the various implementations. The terminology used in the description presented below is intended to be interpreted in its broadest reasonable manner, even though it is being used in conjunction with a detailed description of certain specific implementations of the invention.

Reference is first made to Fig. 1 which shows an indicating wafer strainer (IWS) according to an embodiment. As discussed above, it is a new requirement for ships carrying liquefied gases to indicate the blocking of a filter for cargo liquid and vapour systems. The IWS 1 as shown in Fig. 1 thus includes a filter element 2 which may e.g. be provided as a cone-shaped or frusto-conical strainer formed from a suitable material and adapted for filtering a liquid or a gas. A filter flange 3 surrounds an outer end portion of the filter element 2. Pressure measurement connections 4 are provided which connect a respective first and second chamber formed on opposite sides of the filter element 2 to respective tapping points 5 on a tangential outer surface of the filter flange 3.

As shown in Fig. 2, one pressure measurement connection 4 may terminate at a radially inner surface of the filter flange 3 and thus extend into the first chamber formed on the inside of the filter element

2. The other pressure measurement connection 4 may comprise a tube that is passed through the filter element 2 and thus extends into the second chamber formed on the outside of the filter element 2. Various configurations of pressure measurement connections 4 that may be employed with the IWS 1 are discussed in detail below in conjunction with Fig. 4 and 5.

At the tapping points 5, respective pressure leads 6 are provided which connect the tapping points 5 to a differential pressure instrument 7. For connecting the pressure leads 6 at the tapping points 5, corresponding threads may be provided, or the pressure leads 6 may be welded onto the surface of the filter flange 3 at the tapping points 5. As a differential pressure instrument 7, any known type of differential pressure sensor may be employed. According to some embodiments, non-electric differential pressure sensors may be employed in order to avoid the need for electric installations at the IWS 1. Alternatively, the differential pressure instrument 7 may comprise e.g. a piezoresistive strain gauge, a capacitive sensor utilizing a diaphragm and pressure cavity to create a variable capacitor, or an electromagnetic or piezoelectric differential pressure sensor.

The differential pressure instrument 7 may be mounted on a support 8 which is attached to the tangential outer surface of the filter flange 3. The support 8 may e.g. be welded onto the filter flange

3. Thus, the IWS 1 is a compact strainer device which can be fastened at a junction of two pipes using the filter flange 3 and which provides filtering of any liquid or gas flowing through the pipes as well as a differential pressure measurement of pressures on either side of the filter element 2. Any blockage of the filter element 2 can be detected at an early stage by monitoring any rise in differential pressure as detected by the differential pressure instrument 7. Therein, the IWS 1 is inserted between corresponding pipe flanges at an existing pipe interface so that, during operation, only the support 8 and the differential pressure instrument 7 extend beyond an outer surface of the pipes through which the liquid and/or gaseous medium is flowing.

Fig. 3 shows a portion of a piping and instrumentation diagram (P&ID) of a loading station wherein an IWS 1 according to an embodiment above may be used. In Fig. 3, two strainers are indicated at 32S6430 and 22S6330 with associated differential pressure instruments PDI indicated at PDI 6430 and PDI 6330. As indicated by the curly lines surrounding the respective strainer and differential pressure instrument, these two elements are integrated in an IWS 1 as discussed above in conjunction with Fig. 1 and 2. From Fig. 3, it can be clearly seen that the IWS placed at the manifold flange fulfils all requirements in the above-cited new IGC regulation for cargo filters. Further, in the exemplary P&ID shown in Fig. 3, isolation is provided by valve 32HV6430 in combination with the closing valve on the loading arm. For liquid cargo, depressurizing and draining is achieved through valve 57V6610. For vapour, no drainage is necessary since pressure will be atmospheric after closing the loading arm valve and the valve indicated as 22HV6330 in that sequence.

Fig. 4 and 5 illustrate two alternative embodiments of the IWS 1 as shown in Fig. 1 and 2. In Fig. 4 and 5, the IWS 1 is shown in a schematic cross-sectional view when it is mounted between adjacent flanges of two consecutive pipe segments 9. It can be seen that the filter flanges 3 align with the respective pipe flanges in order to provide a compact and light filter device with integrated differential pressure management which can be easily handled on site and which can be easily inserted at a desired position in a larger piping system. The flow direction of liquid or gaseous medium in the pipes 9 and through the filter element 2 is indicated by an arrow in Fig. 4 and 5.

In the first embodiment as shown in Fig. 4, the pressure measurement connections 4 comprise respective channels which extend through the filter flange 3 in a radial direction from the tapping points 5 to a radially inner surface of the filter flange 3. For contacting the first chamber 10 which is located in an upstream flow direction of the filter element 2 (see Fig. 4), no further channels or tubing needs to be provided. For contacting the second chamber 11 which is located in a downstream flow direction of the filter element 2 (see Fig. 4), additional tubing is provided which extends from the radially inner surface of the filter flange 3 through the filter element 2 and terminates on the opposite side of the filter element 2. This additional tubing of the pressure measurement connection 4 for contacting the second chamber 11 may be formed from a fairly rigid material, in which case it may be sufficient to fasten the tubing to the radially inner surface of the filter flange 3 at one end and guide it through a suitable sized and shaped hole in a surface of the filter element 2 at its other end. Alternatively, the additional tubing of the pressure measurement connection 4 for contacting the second chamber 11 may be formed from a flexible hose material and may be guided along a surface of the filter element 2 using suitable fasteners, clips or the like. In Fig. 4, the tubing 4 extends through a flat bottom surface of a frustoconical filter element 2.

Alternatively, the tubing 4 may extend through any other suitable surface of the filter element 2, such as e.g. a side surface. Therein, the tubing 4 may be passed through any one of the existing strainer openings of the filter element 2 or a separate hole for the tubing 4 may be provided in the filter element 2.

In the alternative embodiment shown in Fig. 5, instead of tubing 4 that is guided through the filter element 2 as shown in Fig. 4, an angled channel may be provided in the filter flange 3 for contacting the second chamber 11. Thus, no additional tubing is required, and both chambers 10, 11 can be contacted via channels or bores provided in the filter flange 3. The channel for contacting the first chamber 10 may be identical to the corresponding channel as shown in the embodiment of Fig. 4, i.e. a radial bore extending from the tapping point 5 on the tangential outer surface of the filter flange 3 to a radially inner surface of the filter flange 3 for contacting the first chamber 10 on an upstream side of the filter element 2. The channel for contacting the second chamber 11 may be an angled bore extending from the corresponding tapping point 5 on the tangential outer surface of the filter flange 3 to a side surface of the filter flange 3 which borders the second chamber 11 formed downstream of the filter element 2. Alternatively, the channel for contacting the second chamber 11 may be a straight bore extending at an angle to the radial direction, so as to connect the tapping point 5 on the radially outer tangential surface of the filter flange 3 with the side surface of the filter flange 3, or a curved bore may be provided.

In all of the embodiments as discussed above, by providing the tapping points 5 on the radially outer surface of the filter flange 3, the pressure on both sides of the filter element 2 can be sensed without the need for any installations in the piping 9 on the sides of the IWS 1.

The IWS 1 according to the various embodiments described above allows installation of a wafer type strainer at an interface of a system or a supply scope where it until now has been a complex task to keep control of the pressure drop over the strainer while staying within the interface limit/supply scope. The IWS 1 also allows easy retrofitting in existing installations where a wafer type strainer without any means for measuring differential pressure has previously been fitted. When fitting the IWS 1, no on site cutting or welding is needed; hence it can be done while the remaining system is in operation.

The IWS 1 as discussed above further provides a compact system for straining a liquid or gaseous medium and providing differential pressure measurements across the strainer at the same time, which is less costly to manufacture than prior art systems, since it comprises few components and can be inserted at any existing pipe interface without the need for additional piping sections or adaptations. Due to the small size, the present IWS 1 is easy to handle and replace on-site. The filter element 2 is readily accessible for cleaning and servicing when a blockage has been detected by the differential pressure instrument 7. Since the IWS 1 may be inserted at an existing pipe interface of e.g. a cargo manifold, there is no need for any additional valves for isolating and/or draining the IWS 1. The IWS 1 may remain permanently inserted in the respective pipe interfaces of the loading station (see Fig. 3), or it may be easily removed and stored between uses since its compact size and low overall weight makes it easy to handle.