Patent Description:
Transforming fluid food products into solid food products by removing water is a well-known principle and is commonly used. In the dairy industry, milk, i.e. milk in a fluid state, can be transformed into milk powder, i.e. milk in a solid state. Another example from the dairy industry is whey transformed into whey powder. One reason for drying liquid food products is logistics. By removing water, which may be later added to create a so-called recombined product, weight and volume may be reduced, which facilitates transportation. Also, the shelf life may be increased by removing the water.

A common approach for removing water involves sing a spray dryer. The general principle of the spray dryer is to spray the food product in the liquid state into a top section of a vessel. The vessel can be filled with hot air such that droplets of the food products are transformed into powder particles as they fall down onto a bottom of the vessel. After being processed in the spray dryer the powder particles may be transferred to e.g. a fluidized bed for further processing.

To avoid contamination of the food products, a powder processing system is most often a closed system such that no bacteria or other unwanted microorganisms come in contact with the food products. In addition to controlling incoming air, outgoing air is often filtered to provide for that powder particles are kept within the system and not spread to surrounding areas. For filtering outgoing air, a bag house equipment can be used. This piece of equipment often comprises a number of parallel filter bags. The filter bags are often made of fabric.

The filter bags can be supported by support cages that are placed inside the filter bags. The support cages provide for that the filter bag are held in place and that nearby filter bags are not in contact with each other. Keeping the filter bags in place is relevant for filtering efficiency, i.e. providing for that powder particles are filtered out at a low cost. In addition to filtering efficiency, it is also relevant from a safety perspective that the filter bags are held in place adequately. Having nearby filter bags being in contact with each other could increase the risk that sparks arise due to static electricity.

Patent document <CIT> describes a support cage for a filter bag. The filter bag is secured to the support cage by using a locking mechanism that is pressed down into an upper section of the support cage.

Even though it is known to use support cages in bag house equipment for keeping filter bags in place, there is a need for an improvement such that the filtering efficiency can be improved and such that the risk of fires can be further reduced.

It is an object of the invention to at least partly overcome one or more of the above-identified limitations of the prior art. In particular, it is an object to provide a support cage that can reliably hold a filter bag in place such that efficient filtering can be achieved and such that a risk that sparks occur can be reduced.

In general words, it has been realized that by having a filter bag support system that comprises a support cage and a lock ring made to interact with one another, a likelihood that the support cage is properly mounted can be increased. An effect of this is that efficient filtering can be achieved. Another positive effect is that a risk of fire caused by incorrectly mounted filter bags can be reduced.

According to a first aspect it is provided a filter bag support system arranged to support a filter bag for separating food powder and air when the filter bag is placed in an opening of a cell plate of a bag house equipment, said filter bag support system comprising a support cage arranged to be placed inside the filter bag, and a lock ring arranged to be placed inside a top section of the support cage, wherein the top section of the support cage is expandable in a radial direction R, and the lock ring is provided with a first section with a first radius R1 and a second section with a second radius R2, wherein the second radius R2 is greater than the first radius R1, wherein the second section is arranged to expand the top section of the support cage in the radial direction R towards an edge of the opening of the cell plate when the lock ring is rotated within the top section, such that the filter bag is clamped between the cell plate and the support cage.

An advantage of the above is that threaded elements, such as a threaded opening interacting with a threaded lock ring, can be avoided. By avoiding these elements a more hygienic design can be achieved, which is made possible due to that there is less risk for having food residues stuck.

The support cage may comprise hook elements that extend in the radial direction R from the top section and thereafter extends in the axial direction A, such that the hook elements rest on the cell plate when the support cage is placed in the cell plate. The hook elements reduces a risk that the support cage and the filter bag are incorrectly mounted, e.g. that filter bag is not held straight. This is advantageous because this provides for improved filtering as well as less risk that sparks occur. Still an advantage with the hook elements is that contact is achieved between the support cage and the cell plate. This provides for that the support cage can be earthed, which in turn provides for that there is no static electricity formed, which is advantageous from a fire risk perspective.

The hook elements may be provided with a first group of ring elements arranged, in combination with the cell plate, to fixate the filter bag. By having this first group of ring elements attached to the hook elements, a correct mounting of the support cage both provides for that the filter bag is held straight and that the filter bag is tightly fitted to the cell plate.

The top section may be provided with a second group of ring segments arranged to be pressed against an underside of the cell plate such that the support cage is prevented to move in axial direction AD by the first group of ring segments and the hook elements. An advantage with having the hook elements abutting on an upper side of the cell plate and the second group of ring elements abutting the underside is that the support cage is reliably held in place.

The support cage may be cylindrically shaped and may comprise <NUM> to <NUM> longitudinal wires and horizontal reinforcement rings spaced apart by <NUM> to <NUM>. An advantage with having the support cage made of spaced apart wires is that this can easily be kept clean. For instance, cleaning-in-place can be used, which has the effect that a down time for cleaning can be reduced. For instance, the wires may have round cross-section and may be made of aluminum or stainless steel.

The top section of the support cage may be provided with a third group of ring elements and a fourth group of ring elements which together hold (fixate) the lock ring, where the third and fourth groups of ring elements are arranged on a respective side of the lock ring. An advantage with using ring elements for holding the lock ring is that less interaction areas between the lock ring and the support cage are formed. This is beneficial since this in turn provides for that there are fewer areas that are difficult to clean.

The fourth group of ring elements, in mounted position in the cell plate placed below the second group of ring elements, may be provided with two to six slots such that flexibility in the radial direction R is provided. Further, the first, the second and the third group of ring elements may also be provided with two to six slots.

The lock ring may comprise a funnel for directing air. An advantage with this is that air fed into the filter bag for removing powder particles stuck on an outside of the filter bag can be directed and/or amplified efficiently, thereby providing for improved cleaning.

The funnel may be a venturi nozzle. The lock ring may be provided with two or more holes arranged to receive a mounting tool.

According to a second aspect it is provided a bag house equipment comprising a cell plate provided with at least one filter bag support system according to the first aspect.

According to a third aspect it is provided a method for installing a filter bag in a bag house equipment, said method comprising placing the filter bag in a hole in a cell plate of the bag house equipment, placing a support cage inside the filter bag, placing a lock ring in a top section of the support cage, wherein the lock ring is provided with a first section with a first radius R1 and a second section with a second radius R2, wherein the second radius R2 is greater than the first radius R1, and the top section of the support cage is expandable in a radial direction R, and rotating the lock ring such that the filter bag is clamped between the cell plate and the support cage.

In line with the advantages presented with reference to the first aspect, an advantage of the above is that threaded elements, such as a threaded opening interacting with a threaded lock ring, can be avoided. By avoiding these elements a more hygienic design can be achieved, which is made possible due to that there is less risk for having food residues stuck.

The method may further comprise placing hook elements of the support cage that extend in the radial direction R from the top section and thereafter extends in the axial direction A, such that the hook elements rest on the cell plate when the support cage is placed in the cell plate.

As presented above in view of the first aspect, the hook elements reduce a risk that the support cage and the filter bag are incorrectly mounted, e.g. that filter bag is not held straight. This is advantageous because this provides for improved filtering as well as less risk that sparks occur, which can happen easily in this type of equipment. Still an advantage with the hook elements is that contact is achieved between the support cage and the cell plate. This provides for that the support cage can be earthed, which in turn provides for that there is no static electricity formed, which is advantageous from a fire risk perspective.

The top section may be provided with a second group of ring segments arranged to be pressed against an underside of the cell plate such that the support cage is prevented to move in axial direction A by the first group of ring segments and the hook elements. An advantage with having the hook elements abutting on the upper side of the cell plate and the second group of ring elements abutting the underside is that the support cage is reliably held in place.

The top section of the support cage may be provided with a third group of ring elements and a fourth group of ring elements arranged to in combination hold the lock ring. An advantage with using ring elements for holding the lock ring is that less interaction areas between the lock ring and the support cage are formed. This is beneficial since this in turn provides for that there are fewer areas that are difficult to clean.

<FIG> illustrates a bag house equipment <NUM> by way of example. The bag house equipment <NUM> can comprise a dome <NUM> under which a clean air chamber <NUM> is provided. In the clean air chamber <NUM>, a cell plate <NUM> is provided. This cell plate <NUM> separates the clean air chamber <NUM> from a dirty chamber <NUM> in which unfiltered air is provided.

In the cell plate <NUM>, filter bags <NUM> are arranged. These filter bags <NUM> provide for that food powder particles are separated from the air as this is fed through the filter bags <NUM> into the clean air chamber <NUM>. The filter bags <NUM> can be made of fabric or any other material suitable for filtering out powder particles from air. A lower part of the dirty chamber <NUM> may comprise a cone <NUM>. Unfiltered (powder polluted) air may be fed into the dirty chamber <NUM> via an inlet <NUM>. It flows through the filter bags <NUM> such that it thereby is filtered by the filter bags <NUM>, through openings in the cell plate <NUM>, into the clean air chamber <NUM> and thereafter out from the bag house equipment <NUM> via an outlet <NUM> in the dome <NUM>.

<FIG> illustrates the cell plate <NUM> and the filter bag <NUM> in further detail. As illustrated, a support cage system <NUM> comprising a support cage <NUM> is placed inside the filter bag <NUM> to provide for that this is held in place, which in turn provides for that efficient filtering can be achieved. Holding the filter bag <NUM> in place is relevant in normal operation when the air is fed from the dirty chamber <NUM>, through the filter bag <NUM> and to the clean air chamber <NUM>, but also when the air flow is reversed for removing powder particles from an outside of the filter bag, i.e. a side of the filter bag facing the dirty chamber <NUM>.

The filter bag <NUM> and the support cage system <NUM> is placed in an opening <NUM> of the cell plate <NUM>. The opening <NUM> has the shape of a circular hole in the cell plate <NUM>. When the filter bag <NUM> and the support cage system <NUM> are mounted correctly, the filter bag <NUM> abuts an edge <NUM> of the opening <NUM>.

As illustrated in <FIG>, the support cage system <NUM> comprises a lock ring <NUM>. The lock ring <NUM> can be provide with holes <NUM> for facilitating mounting of the lock ring <NUM> inside the support cage <NUM>.

The support cage <NUM> can comprise hook elements <NUM> that, when the lock ring <NUM> is mounted inside the support cage <NUM>, abut the cell plate <NUM>. One advantage with this is that the support cage <NUM> is earthed, which in turn provides for that a risk that static electricity is formed inside the bag house equipment <NUM> is reduced. This is advantageous in that a risk is reduced that the filter bag <NUM> or other combustible material inside the bag house equipment <NUM> catch fire.

During mounting of the lock ring <NUM> in the support cage <NUM>, a mounting tool <NUM> can be used. As illustrated, the mounting tool <NUM> is placed inside two of the holes <NUM> in the lock ring <NUM>. Once placed in the holes <NUM>, the mounting tool <NUM> can be rotated around an axial direction A of the support cage <NUM> such that the lock ring <NUM> is locked inside the support cage <NUM>. The lock ring <NUM> is further illustrated in <FIG>.

The hook elements <NUM> are provided with a first group of ring elements <NUM>. This first group of ring elements <NUM> is arranged such that when tip sections of the hook elements <NUM> abut the cell plate <NUM>, a snug fit for upper sections of the filter bags <NUM> is provided. In other words, interaction between the hook elements <NUM> and the cell plate <NUM> provide for that the filter bags <NUM> are held vertical, that is, contact with adjacent filter bags are avoided, and interaction between the first group of ring elements <NUM> and the cell plate <NUM> provides for that the filter bags <NUM> are prevented to move in axial direction A. Since the first group of ring elements <NUM> can be provided on the hook elements <NUM>, a proper mounting will provide for that both the filter bag <NUM> is held straight and that the filter bag <NUM> is tightly fit to the cell plate <NUM>.

The filter bag <NUM> may be provided in its upper section with a steel spring <NUM>. If such steel spring is provided, as illustrated in <FIG>, an axial distance D between the first group of ring elements <NUM> and the cell plate <NUM> corresponds to a height H of the steel spring embedded in the upper section of the filter bag <NUM>. In <FIG> the steel spring, which has the form of a circular steel ring, cannot be seen as it is enclosed by the fabric of the filter bag <NUM>.

<FIG> illustrates a side view of the support cage <NUM>. As illustrated, a second group of ring elements <NUM> is used for holding the support cage <NUM> fixated in axial direction A with respect to the cell plate <NUM>, which is illustrated in part in <FIG>. A third group of ring elements <NUM> and a fourth group of ring elements <NUM> are arranged to hold the lock ring <NUM>. To accomplish this the third group of ring elements <NUM> abuts an upper side of the lock ring <NUM> while the fourth group of ring elements <NUM> abuts an underside of the lock ring <NUM>.

Having groups of ring elements instead of a continuous ring in one piece is advantageous in that a top section <NUM> of the support cage <NUM> can flex in radial direction R. Thus, when rotating the lock ring <NUM> this can, as explained below, result in that the top section <NUM> expands radially, which as an effect provides for that the first group of ring elements <NUM> pushed in under the cell plate <NUM> such that these can abut an underside <NUM> of cell plate <NUM>, and thereby securely fix the support cage <NUM> as described above. <FIG> illustrates a top view of the support cage <NUM>, and <FIG> illustrates a perspective view of the support cage <NUM>.

<FIG> illustrate the hook element <NUM> in further detail. As illustrated, the hook element <NUM> may be made of wire, which also may be the case for other parts of the support cage <NUM>. This is advantageous from a hygienic point of view. By having the support cage <NUM> made of wires, e.g. stainless steel wires, a risk of having food residues stuck can be reduced. This especially holds true if the wires are spaced apart and if round wires are used.

As illustrated in <FIG>, the hook element <NUM> may be an element that is produced separately and thereafter attached to the other parts of the support cage <NUM>. Before being attached to the other parts, the first group of ring elements <NUM>, the second group of ring elements <NUM> and the third group of ring elements <NUM> may be attached, e.g. by welding, to a first leg 500a and a second leg 500b of a U-bent wire structure. By attaching to both legs, a form of the U-bent wire structure is fixated. In mounted position, the first and second legs 500a, 500b extend in axial direction A, as is illustrated in <FIG>.

The first leg 500a extends from a first radially extending section 502a, which joins a first axially extending section 504a that is radially spaced apart from the first leg 500a. The axially extending section 504a joins a tip section <NUM> which can be parallel with a circumference of the support cage <NUM>. In a similar manner, the second leg 500b extends from a second radially extending section 502b, which in turn joins a second axially extending section 504b. The second axially extending section 504b joins the tip section <NUM>, thereby connecting the first and second leg 500a, 500b. As illustrated in <FIG>, the tip section <NUM> is arranged to abut the cell plate <NUM> in the mounted position.

<FIG> illustrate the lock ring <NUM> in further detail from a top view and from a side view, respectively. The lock ring <NUM> has a first section <NUM> with a first radius R1 and a second section <NUM> with a second radius R2, wherein the second radius R2 is greater than the first radius R1. The lock ring <NUM> can comprise several first and second sections <NUM>, <NUM>. For instance, the lock ring <NUM> illustrated in <FIG> comprises four first sections and four second sections, placed alternately along a circumference of the lock ring <NUM>.

A protrusion <NUM> is provided on the second section <NUM>. An advantage with having the protrusion <NUM> is that when rotating the lock ring <NUM> with respect to the support cage <NUM> during an installation procedure, the protrusion <NUM> will hooks into a vertical wire of the support cage <NUM>, e.g. the first or second leg 500a, 500b of the hook element <NUM> or into another wire that is located before the leg as seen in the rotational direction RD of the lock ring <NUM>. I detail, to fixate the lock ring <NUM> to the support cage <NUM>, the lock ring <NUM> is moved in the axial direction A to a position in between the third ring elements <NUM> and the fourth ring elements <NUM>. This is done when having the second section <NUM> with the larger radius R2 aligned with the interspaces formed between the thirds ring elements <NUM>. Thereafter the lock ring is rotated in the rotational direction RD so that the second section <NUM> is forced in between the space formed between the third ring elements <NUM> and the fourth ring elements <NUM>. Due to the larger radius R2 the top section <NUM> of the support cage <NUM> is pressed out towards the edge <NUM> of the opening <NUM> of the cell plate <NUM>. This effectively "clamps" the support cage <NUM> to the cell plate <NUM>.

A funnel <NUM> may be provided in a mid-portion of the lock ring <NUM>. The funnel <NUM> may be used for directing and amplifying air during a filter bag cleansing phase when air is fed to the clean air chamber <NUM>, through the filter bags <NUM> and to the dirty chamber <NUM> for removing powder particles stuck on the filter bag <NUM>. As illustrated, the funnel <NUM> may be a venturi nozzle. The cross sectional area of the funnel <NUM> decreases in a direction from the air chamber <NUM> to the dirty chamber <NUM>.

<FIG> is a flowchart illustrating steps of a method <NUM> for installing a filter bag <NUM>. In a first step <NUM> the filter bag <NUM> is placed in the hole <NUM> in the cell plate <NUM>, or is placed on the outside of the support cage <NUM>. Thereafter, in a second step <NUM>, the support cage <NUM> is pushed through the hole <NUM> in the cell plate <NUM>. In a third step <NUM>, the lock ring <NUM> is placed in the top section <NUM> of the support cage <NUM>. As described above, the lock ring <NUM> may be provided with the first section <NUM> with the first radius R1 and the second section <NUM> with the second radius R2, wherein the second radius R2 is greater than the first radius R1, and the top section <NUM> of the support cage <NUM> is expandable in the radial direction R. In a fourth step <NUM>, the lock ring <NUM> is rotated such that the filter bag <NUM> is clamped between the cell plate <NUM> and the support cage <NUM>.

Optionally, in a fifth step <NUM>, the hook elements <NUM> that extend in the radial direction R from the top section <NUM> and thereafter extends in the axial direction A can be placed such that the hook elements <NUM> rest on the cell plate <NUM> when the support cage <NUM> is placed in the hole <NUM> of the cell plate <NUM>.

Claim 1:
A filter bag support system (<NUM>) arranged to support a filter bag (<NUM>) for separating food powder and air when the filter bag (<NUM>) is placed in an opening (<NUM>) of a cell plate (<NUM>) of a bag house equipment (<NUM>), said filter bag support system (<NUM>) comprising
a support cage (<NUM>) arranged to be placed inside the filter bag (<NUM>), and
a lock ring (<NUM>) arranged to be placed inside a top section (<NUM>) of the support cage (<NUM>), wherein
the top section (<NUM>) of the support cage (<NUM>) is expandable in a radial direction (R), and
the lock ring (<NUM>) is provided with a first section (<NUM>) with a first radius (R1) and a second section (<NUM>) with a second radius (R2), wherein the second radius (R2) is greater than the first radius (R1), wherein the second section (<NUM>) is arranged to expand the top section (<NUM>) of the support cage (<NUM>) in the radial direction (R) towards an edge (<NUM>) of the opening (<NUM>) of the cell plate (<NUM>) when the lock ring (<NUM>) is rotated within the top section (<NUM>), such that the filter bag (<NUM>) is clamped between the cell plate (<NUM>) and the support cage (<NUM>).