WO2012177130A1

WO2012177130A1 - A pulse valve system having a pipe holder with axially deformable spring arms

Info

Publication number: WO2012177130A1
Application number: PCT/NL2012/050436
Authority: WO
Inventors: Stefanus Theodorus Maria VAN SCHIJNDEL
Original assignee: Asco Controls BV
Current assignee: Asco Controls BV
Priority date: 2011-06-24
Filing date: 2012-06-21
Publication date: 2012-12-27
Anticipated expiration: 2013-12-24
Also published as: NL2006998C2; EP2723469A1

Abstract

A pulse valve system 1 comprises a pressurized gas storage tank 2 having an interior space 3, a main opening 7 provided in the tank wall, a blow pipe opening provided in the tank wall at a position opposite of the main opening, and a blow pipe 15 extending through the interior space 3 from the main opening 7 towards the blow pipe opening. A controllable pulse valve 8 is mounted at the location of the main opening, and has a valve organ 9 for closing/opening a flow path for the gas to flow out of the interior space 3 into an inlet end 15a of the blow pipe in an open position of the valve 8. One or more spring organs, for example formed by flexible wings 16b of a pipe holder 16, are provided for exerting an axially directed flexible clamping force to the blow pipe.

Description

Title: A pulse valve system having a pipe holder with axially deformable spring arms.

The invention relates to the field of pulse valve systems which are used to

controllably blow out pulses of compressed gas.

Such pulse valve systems are known to be used in combination with dust collector systems or pollution preventing filter installations in order to periodically blow air into them in a direction opposite to a filtering direction so as to detach adhered dusts from the filtering surface. In the beginning stand alone pulse valves were used for this which all had a die cast body having a machined seat for a diaphragm of the valve to lie sealingly against in a closed position of the valve. See for example EP-0 817 931.

When the dust collector systems and pollution preventing filter installations grew bigger, this evolved to pulse valve systems having a large common pressurized gas storage tank against the outside of which large numbers of controllable pulse valves can be mounted. With this the large common pressurized tank no longer was welded steel but was formed as an extruded aluminium body having an interior space. After having extruded the aluminium body, for each pulse valve a main opening was machined into the tank wall. With this each main opening was machined in such a way that it comprised a central inlet opening and four banana shaped slots around it. At the outer side around each central inlet opening seats were formed for diaphragms of the pulse valves to lie sealingly against in closed positions of their valves. At the inner side around each central inlet opening seats were formed for so-called blow pipes to be placed sealingly against with their inlet ends. At positions diametrically opposite the main openings, blow pipe openings were also machined into the tank wall. During assembly the blow pipes can be inserted into the tank through the blow pipe openings. As soon as the inlet ends of the blow pipes have come to lie sealingly against their respective seats of the main openings, the opposite outlet ends can be fixedly mounted to mounting flanges of the blow pipe openings by means of suitable pipe holders. For this the pipe holders have sleeve shaped parts sealingly fitting around the outlet ends of the blow pipes, while supporting and delimiting them in the axial direction. They can also be connected threaded to each other.

However, the machining of the steering and blow pipe openings required huge investments in production machines. In case of a small mistake, broken tool or damaging of one of the openings, the complete tank was immediately useless.

It has been tried to overcome this disadvantage by starting to make the main openings as simple round openings. The blow pipes then were only fixedly mounted with their outlet ends to the blow pipe openings of the tank wall. The inlet ends of the blow pipes then were no longer supported but just kept supported floating in front of the steering valve. See for example US 6,354,562 or WO 97/18026.

This however made the blow pipes instable, particularly because of the high pressure air blows which had to flow through them during operation.

In order to prevent this, a wide variety of rigid pipe holders have then been developed which could be placed between the main openings and inlet ends of the blow pipes. Each of these pipe holders have a part sealingly connecting to an inlet end of a blow pipe, and have rigid radially outwardly projecting support arms which are well able to support the inlet end of the blow pipe interspaced from the tank wall and main opening therein. The support arms are thus able to delimit a flow path for the supply of compressed gas to flow out of the tank into the blow pipe in the open position of the valve. The ring shaped parts of those pipe holders then comprise the seat for a diaphragm of the valve to sealingly lie against in the closed position of the valve for then closing the flow path. Thus the pipe holders still made it possible to machine rather simple round openings as main openings into the tank wall. EP-1 094 880 and US-7,837,062 show two variants of such rigid pipe holders.

The disadvantage of these known constructions however is that the lengths of the blow pipes all need to lie within strict boundaries. Otherwise they do not accurately fit between their pipe holders which may lead to leakages. Also expansions or shrinkages of the blow pipes which may well occur during temperature changes can lead to deformations of the blow pipes themselves or of their pipe holders which in turn may lead to the seats no longer being able to properly close or open the flow paths towards the blow pipes. In order to prevent this, the blow pipes are mostly mounted with a certain axial play between the pipe holders at the blow pipe openings and the pipe holders at the main openings. This however may lead to oscillating movements of the blow pipes during use, which results in a lot of noise being produced and which may lead to wear and damaging of seals placed between the pipe holders and the blow pipes.

WO 2010/028813, which is considered to be the closest prior art, shows a

construction of a pulse valve system with a pressure tank and with a semi-rigid pipe holder placed around an inlet end of a blow pipe. In this publication the pipe holder comprises a ring shaped part which is provided with a number of snap arms. The snap arms keep the inlet end of the blow pipe centred inside a main opening provided in a tank wall at an interspaced distance of this tank wall and thus keeping a flow path free between the tank wall and the respective arms. At a position opposite the main opening, the tank is provided with a blow pipe opening. The blow pipe opening comprises an inwardly projecting abutment edge for forming an abutment for the blow pipe in its axial direction. The snap arms project slanting outwardly under small angles of about 30 degrees relative to a central axis of the pipe holder. The snap arms are made out of plastic with such a thickness that they are able to to slightly bent radially inwards temporarily during assembling/mounting. The purpose of this "radial" inward springing option is to be able to insert the blow pipe together with the pipe holder into the tank via the relative slender main opening. As soon as an opposite outlet end of the blow pipe has been properly placed against the inwardly projecting abutment edge of the blow pipe opening, the arms need to have passed the main opening such that they are able to take their original position again and thus snap behind an inwardly projecting abutment edge provided adjacent the main opening. As soon as this position is achieved, the blow pipe is fixedly retained in the axial direction between the two openings.

Here also the disadvantage is that the length of the pipe with this semi-rigid pipe holder needs to lie within strict boundaries. Otherwise the pipe does not accurately fit between the two openings leading to possible permanent leakages or leading to seats no longer being able to properly close or open the flow path towards the blow pipe. In order to be sure that the snapping of the snap arms is able to occur during assembling, deviations in the length of the blow pipe always need to be such that the blow pipe never can be longer than the available length between the two openings. In practice this means that the blow pipe is designed and/or chosen to be a few mm's too short. This however causes the blow pipe to be mounted with an axial play of those few mm's between the two openings, which leads to oscillating movements of the blow pipe during use. This in turn results in a lot of noise being produced and may lead to excessive wear and damaging of seals placed between the pipe holder and the blow pipe. Further it is noted that the snap connection makes it difficult to remove the blow pipe out of the tank again if desired for maintenance or other reason. Finally it is noted that the plastic snap arms may break of if too much pressure or high-frequency pressure changes are exerted upon them. Another disadvantage is that the snap arms can only be bent inwards during mounting/assembling for a very short period of time, otherwise relaxation may occur causing the arms to no longer be able to take their snapping positions, for the same reason the plastic snap arms cannot be used under continuous tension, and have a high chance of breaking of because of high frequency oscillating movements of the assembly of blow pipe and pipe holder during blow outs.

The invention aims to overcome one or more of the abovementioned disadvantages at least partially or to provide a usable alternative. In particular the invention aims to provide a user-friendly and reliable multi-station pulse valve system which can be manufactured environmentally friendly against low costs.

This aim is achieved by a pulse valve system according to claim 1. The system comprises a pressurized gas storage tank having an interior space. A main opening is provided in the tank wall. A blow pipe opening is provided in the tank wall at a position opposite of the main opening. Between the main and blow pipe opening a longitudinal blow pipe is provided which extends through the interior space of the tank. A controllable pulse valve is mounted at the location of the main opening, and has a movable valve organ which is able to close or open a flow path for the gas between the interior space and an inlet end of the blow pipe. The pulse valve system further comprises a first pipe holder at the main opening for supporting the inlet end in the axial direction as well as in a radial direction. This first pipe holder has a sleeve shaped part sealingly fitting around the inlet end of the blow pipe. The sleeve shaped part comprises a seat for the valve organ to sealingly lie against in its closed position. The first pipe holder further has support arms which project outwardly from the sleeve shaped part. The support arms are able to properly position the sleeve shaped part of the pipe holder and thus also the inlet end of the blow pipe at an aimed interspaced distance from the tank wall. The flow path for the gas to be able to flow from the interior space of the tank towards the inlet end of the blow pipe in the open position of the valve is left clear in between the support arms. The support arms for this are divided interspaced around the circumference of the sleeve shaped part.

According to the inventive thought one or more axially deformable spring organs are provided for exerting an axially directed flexible clamping force to the blow pipe independent of the position of the valve organ, that is to say both in the open and closed position of the valve organ. If expansions or shrinkages of the blow pipe occur due to temperature changes or pressurization, then this is no longer a problem since the spring organ(s) is well able to deform in the axial direction and thus is able to compensate for the change in length of the blow pipe. Owing to this the blow pipe does not have to deal with large internal compressive stresses in the case of higher temperatures, nor can it start to oscillate between its supports in the case of lower temperatures. Another advantage is that the invention makes it possible to use blow pipes during manufacturing/assembly of which the precise length may be less accurate. The blow pipes may well be a mm longer or shorter without this having to lead to rejections. Again the spring organs are well able to compensate in both directions for such deviant blow pipe lengths. The adding up of tolerances of the various parts of the system thus no longer makes it difficult and expensive during assembly because of the large flexibility the spring organs offer in the axial direction. Another important advantage of the invention is that it is able to properly deal with the continuously changing use conditions of the tank. When the tank is in use, the pressure inside it constantly varies between 0 and 10 bar. Since the resistance of the tank against deformation is not the same for every location around its circumference, this delta pressure causes opposite tank walls to move over substantial distances towards and away from each other during blow outs and

pressurization. This causes the distance between the two openings to change with the same frequency as the blow outs occur. Thus the tolerance of the blow pipe fitting between the two openings is no fixed value. Thanks to the invention this is no problem. The spring organs are well able to each time over and over again deal with this variable available length and shall and shall prevent the pipe from starting to slide inside the pipe holder and/or between the openings during use.

In a particular embodiment the support arms may perform the function of the axially deformable spring organs. The support arms can then advantageously perform a double function. On the one hand they are able to properly position the sleeve shaped part of the pipe holder and thus also the inlet end of the blow pipe at an aimed interspaced distance from the tank wall. On the other hand they are able to bias the blow pipe in its

mounted/assembled position and keep it biased even during frequent pressure changes occurring during blow outs. They are able to immediately take up any axial play which otherwise would have arisen because of deformations of the blow pipe and tank each time the pressure inside the tank drops and rises around the periodic blow outs. The support arms then in particular are formed as being at least partially axially flexible. The sleeve shaped part is then resiliently movable in said axial direction relative to the support arms in order to have the sleeve shaped part exert a force on the blow pipe in the axial direction towards the blow pipe opening.

The sleeve shaped part of the first pipe holder may be connected in various ways to the inlet end of the blow pipe, for example crunched or otherwise clamped or mounted around the inlet end of the blow pipe. A sealing ring can be positioned in between them.

The support arms according to the invention may have all kinds of shapes and dimensions. Preferably they are made as flexible plate shaped wings. In particular the support arms then are given a thickness of less than 2 mm. For example the thickness may be approximately 0,8 mm. The thin arms have the advantage that they do not block the flow path anymore than necessary. The thin arms make it possible for the gas to flow from the interior of the tank into the blow pipe while only having to make one bend. Fewer restrictions are to be overcome by the compressed gas when flowing into the blow pipe. This makes it able to maintain more energy inside the gas blows, owing to which the performance gets slightly improved.

The first pipe holder can be made out of various materials like plastic. Preferably it is made out of metal, in particular stainless steel, more in particular spring steel, since this material maintains its spring characteristics, does not have to deal with relaxation, and is well able to deal with the continuously changing tensions caused by the high frequency blow outs.

According to an environmentally friendly embodiment the first pipe holder is formed by an element which has been cold formed out of metal plate material. Polluting techniques like die casting or machining of a pipe holder with a lot of waist of material are then no longer needed. The sleeve shaped part can then for example easily be deep drawn out of the metal plate material. In an embodiment the support arms have curved middle sections. Thus they are able to take up both axial play and length changes of the blow pipe, as well as expansion of the blow pipe in the radial direction. The curved middle sections advantageously are concavely curved towards the valve such that they do not abut against parts of the valve or tank wall if they need to deform/flex in the axial direction. Furthermore the curved middle sections preferably cover at least quarter circular segments having radii of at least 6mm.

In a preferred embodiment the support arms comprise parts which enclose angles between 45-90 degrees relative to the axial direction. More in particular the support arms comprise parts which extend substantially perpendicular to the axial direction. This makes it well possible for the support arms to flex in whichever axial direction and have this result in sufficient amounts of axial repositioning of the pipe holder and inlet end in order to cope with expansion, shrinkage or any other imposed deformation.

In a variant outer ends of the support arms extend fully perpendicular relative to a central axis of the sleeve shaped part. In other words those outer ends extend fully radially. With this those fully radially extending outer ends can support with their free outer edges against complementary side wall parts of the tank which complementary side wall parts preferably extend parallel to the axial direction. Furthermore those fully radially extending outer ends can support with their preferably substantially flat upper walls against complementary roof wall parts of the tank which complementary roof wall parts preferably extend parallel to the radial direction.

Further embodiments are stated in the dependent subclaims.

The invention also relates to a use of a pulse valve system for blowing air into a dust collector or filter installation in a direction opposite to a filtering direction so as to detach adhered dusts.

The invention shall be explained in more detail below with reference to the accompanying drawings, in which:

Fig. 1 shows a schematic cross sectional view of an embodiment of the pulse valve system according to the invention in an open position of the valve;

Fig 2 shows an enlarged partial view of an upper part of fig. 1 ;

Fig 3 shows an enlarged partial view of a lower part of fig. 1 ;

Fig 4 shows a perspective and cross sectional view of the first pipe holder of fig. 1 ; Fig 5 shows a perspective view of fig. 1 without the valve;

Fig 6 shows a top view of fig. 1 ;

Fig 7 shows a cross sectional view over the line B-B in fig. 6; and

Fig. 8 shows a view similar to the one of fig. 1 in which a plurality of adjacent pulse valves and blow pipes are to be seen. In fig. 1 the valve system is referred to in its entirety with the reference numeral 1. The system 1 comprises an extruded aluminium tank 2 having an interior space 3. The outer ends of the tank 2 are closed by end caps 4, inside one of which a gas inlet 5 is provided for feeding pressurized gas into the tank 2, for example via a compressor (not shown). At the upper side the tank 2 has a large number of circular so-called main openings 7 machined into the tank's circumferential wall. A pulse valve 8 is bolted to the outside of the tank 2 at the location of each main opening 7. The pilot operated valve 8 comprises a diaphragm 9 which can be positioned up and down between an open and a closed position against the action of a spring 10 (see fig. 2). The valve 8 can be of various types, like a solenoid operated valve or, as shown here, a remote operated valve. A control box (not shown) can be connected to the pulse valves 8 for periodically actuating them, that is to say to have their diaphragm 9 move upwards against the action of the spring 10.

Directly underneath the main opening 7 a blow pipe 15 is provided which extends downwards through the interior space 3. At its upper end the blow pipe 15 comprises an inlet end 15a onto which a first pipe holder 16 is placed. The pipe holder 16 is cold-formed and punched out of stainless steel plate and has a deep-drawn central sleeve shaped part 16a (see fig. 4). The sleeve shaped part 16a at its upper side has an inwardly deflected curved edge which forms a seat 16a' for the diaphragm 9 to lie sealingly against in the closed position. The seat 16a' has been given a radius of a few millimetres, in particular

approximately 2 mm. The inlet end 15a of the blow pipe 15 has been inserted into the sleeve shaped part 16a with its free end edge 15a' abutting in the axial direction A against the seat 16a'. Between the sleeve shaped part 16a and the inlet end 15a an O-ring 17 is placed. The sleeve shaped part 16a merges at four locations around its circumference into wings 16b. The wings 16b extend substantially in the radial outwards direction relative to the central sleeve shaped part 16a, and each start with a concavely curved part 16b' which is substantially radially directed while being curved around a tangential direction, to end with a straight part 16b" which is fully radially directed. The straight part 16b" lies abutting against axially inward edge parts 2' of the tank wall circumventing the main opening 7.

Between the curved part 16b' and the straight part 16b" a centring projection 16b'" is provided (only shown in fig. 2) which lies against radial inward edge parts 2" of the tank wall circumventing the main opening 7. The centring projections 16b'" of all the wings 16b together centre the seat 16a' and inlet end 15a of the blow pipe neatly in front of the diaphragm 9.

The blow pipe has an outlet end 15b which is sealingly held inside a second pipe holder 20. This pipe holder 20 comprises a sleeve shaped part 20a into which the outlet end 15b has been inserted with its free end edge 15b' abutting in the axial direction A against an inwardly projecting flange 20a'. The pipe holder 20 further comprises a mounting flange 20b with which it is bolted against the tank wall 2, while its sleeve shaped part 20a extends through a circular so-called blow pipe opening 22. The blow pipe openings 22 are machined into the tank's circumferential wall at diametrically opposite positions of the main openings 7. At their lower ends the pipe holder 20 comprises a connection 20c for connecting the blow pipe 15 via an additional blow pipe to a filtering cloth of a filter installation (not shown).

During use the tank 2 is filled with a pressurized gas, in particular at pressures between 0-10 bar. The gas most of the time can be environmental air. Each time that it is desired to have an amount of the gas blow out of the blow pipe 15 into the filtering cloth of the filter installation in order to blow any particles like dust free form the filtering cloth's surface, the pilot operated pulse valve 8 is operated by means of the control means in such a way that the diaphragm 9 moves upwards from the closed position in which it lied sealingly against the seat 16a' towards the open position as shown in fig. 1 and 2. In this open position a play is obtained between the diaphragm 9 and the seat 16a'. Thus a flow path arises which starts in the interior space 3 of the tank 2, and from there runs in between the wings 16b, over the seat 16a' into the inlet end 15a of the blow pipe 15. This flow path is shown with the arrows FP in fig. 1.

Advantageously the first pipe holder 16 out of thin metal plate material does not block the flow path anymore than needed with only a few energy taking restrictions like corners, in- and outlets, etc. This helps to prevent loss of pressure of the gas flow to occur and/or prevents turbulences to be introduced into the gas flow. Thus the flow path FP is hardly restricting the pulse performance. This is even further improved by the downwardly concavely curved parts 16b' of the wings 16b which make it possible for the gas to flow quicker with larger amounts and at less steep angles into the blow pipe 15. Not only is the first pipe holder 16 able to clamp and hold the blow pipe 15 into position horizontally, it is also able to position the seat 16a' in the axial direction and to take up any tolerance stack of the assembly of blow pipe 15, pipe holder 20 and valve 8 in the axial direction.

In the case of temperature changes the flexible wings 16b offer freedom for the blow pipe 15 to expand or shrink in the axial direction by flexing somewhat upwardly or downwardly. Furthermore the flexible wings 16b are able to take up deformation caused by blowing up of one or more parts of the system because of the high pressures occurring during use. Owing to the curved parts 16b' the blow pipes also have the freedom to expand or shrink somewhat in the radial direction by curving somewhat more or less. The centring projections 16b'" then still keep the assembly perfectly centred and prevent the straight wing parts 16b" to start sliding along the tank wall during this deformation.

Besides the embodiment shown numerous variants are possible. For example the various parts may have other shapes and dimensions and be made out of different materials. The system can be used in combination with partly or fully cylindrical tanks but also with other geometries like square ones. In case of an overhaul the various parts of the system, including the first pipe holder, can easily be replaced and repaired. Instead of four wings other numbers are also possible. Instead of using the valve system for blowing through filter installations and the like it can also be used for other purposes like blowing confetti into a room or other situations where a quick exhaust of an amount of gas is required. Instead of using a pipe holder with axially flexible wings, it is also possible to use other forms shapes and types of support arms, as long as they are able to exert the required axially directed flexible clamping force to the blow pipe. In the alternative or in addition it is also possible to add an axially deformable spring organ between the blow pipe and one of its axial supports. For example an axially compressible spring organ may be placed between the second pipe holder and the outlet end of the blow pipe and/or between the first pipe holder and the inlet end of the blow pipe.

Thus according to the invention a low cost and environmentally friendly valve system is obtained having improved pulse flow characteristics.

Claims

1. A pulse valve system for controllably blowing out compressed gas through a blow pipe, comprising:

- a pressurized gas storage tank having an interior space;

- a main opening provided in the tank wall;

- a blow pipe opening provided in the tank wall at a position opposite of the main opening;

- a blow pipe having an axial direction, extending through the interior space from the main opening towards the blow pipe opening;

- a controllable pulse valve mounted at the location of the main opening, and having a valve organ moveable in said axial direction for closing/opening a flow path for the gas to flow out of the interior space into an inlet end of the blow pipe in an open position of the valve; and

- a first pipe holder at the main opening for supporting the inlet end in the axial direction, in which the first pipe holder has a sleeve shaped part sealingly fitting around the inlet end and outwardly projecting support arms supporting against the tank wall,

in which the sleeve shaped part comprises a seat for the valve organ to sealingly lie against in a closed position of the valve, and

in which the outwardly projecting support arms position the sleeve shaped part and inlet end interspaced from the tank wall in order to delimit the flow path,

characterized in that,

one or more spring organs are provided for exerting an axially directed flexible clamping force to the blow pipe.

2. A pulse valve system according to claim 1 , wherein the support arms form said spring organs.

3. A pulse valve system according to claim 2, wherein the support arms are made as flexible plate shaped wings.

4. A pulse valve system according to claim 3, wherein the support arms have a thickness of less than 2 mm.

5. A pulse valve system according to claim 3 or 4, wherein the first pipe holder is a cold formed metal plate material element.

6. A pulse valve system according to claim 5, wherein the sleeve shaped part is a deep drawn metal plate material element.

7. A pulse valve system according to one of claims 2-6, wherein the support arms are formed such that the sleeve shaped part is resiliently movable in said axial direction relative to the support arms in order to have the sleeve shaped part exert a force on the blow pipe in the axial direction towards the blow pipe opening.

8. A pulse valve system according to one of claims 2-7, wherein the support arms have curved middle sections.

9. A pulse valve system according to claim 8, wherein the curved middle sections are concavely curved towards the valve.

10. A pulse valve system according to one of claims 2-9, wherein each support arm has a centring projection lying against a radial wall part of the tank.

1 1. A pulse valve system according to one of claims 2-10, wherein a total number of four support arms is provided.

12. A pulse valve system according to one of the preceding claims 2-1 1 , wherein the first pipe holder has been made out of stainless steel and/or spring steel.

13. A pulse valve system according to one of the preceding claims 2-12, wherein the support arms comprise radially outwardly projecting parts which enclose angles between 45- 90 degrees relative to the axial direction, and in particular extend substantially perpendicular to the axial direction.

14. A pulse valve system according to one of the preceding claims, further comprising: - a second pipe holder at the blow pipe opening for supporting the outlet end in the axial direction,

in which the second pipe holder has a sleeve shaped part sealingly fitting around an outlet end of the blow pipe, and

in which the second pipe holder is mounted to the tank wall.

15. Use of a pulse valve system according to one of the preceding claims, for blowing air into a dust collector or filter installation in a direction opposite to a filtering direction so as to detach adhered dusts.