SE2150600A1

SE2150600A1 - Apparatus and method for collecting dust samples

Info

Publication number: SE2150600A1
Application number: SE2150600A
Authority: SE
Inventors: Ilkka Pyykkönen; Pasi Kärki; Petri Janhunen; Timo Sirviö
Original assignee: Valmet Automation Oy
Priority date: 2020-05-19
Filing date: 2021-05-12
Publication date: 2021-11-20
Also published as: SE544152C2

Abstract

The invention relates to an apparatus (100) for collecting dust samples. The apparatus comprises a piston (102) and a cylinder (110) for holding the piston with a body having a hole (108) extending through the body. The cylinder (110) has a first end (112), which is open, the first end of the cylinder being slanted such that underside (130) of the cylinder extends farther than upper side (132). A mechanism (114) moves the piston between inward and outward positions. The apparatus gathers dust flowing past the piston into the hole of the piston when the piston is in the outward position and moves the gathered dust by moving the piston into the inward position. An input feed (116) is configured to spread fluid through the hole filled with dust to flush the dust to an output feed (118).

Description

ÅPPARATUS FOR COLLECTING DUST SAMPLES Technical Field The exemplary and non-limiting embodiments of the invention relate generally to collecting dust samples.

Background Automation systems are widely used in measuring and controllingvarious industrial processes such as paper and pulp or chemical factories. ln manyprocesses dust is produced in some form and analysing the amount and propertiesofthe dust is important when monitoring and controlling the process. An exampleof such process is pulp processing in recovery boilers. Recovery boilers maycomprise electric filters that may gather dust or ash from boilers. Analysing thedust at the output of electric filters is technically difficult to realise in a reliablemanner. ln many cases the dust is conveyed in pipes where there is a negativepressure. Prior art solutions of collecting dust samples have typically a screw-typestructure or utilise pressured air to blow dust into a container. They process drydust and need constant monitoring and cleaning as the dust get cloddy and blocksthe dust collectors, especially when the dust is lime based. Similar applications canbe found, for example, in food processing, where milk powder, coffee powder, and ﬂour manufacturing processes need similar monitoring and controlling.

Brief description An object of the invention is to provide an improved method and anapparatus implementing the method to reduce or avoid the above-mentionedproblems.

The objects of the invention are achieved by an apparatus as claimed inclaim 1 and by method as claimed in claim 8. Some embodiments of the inventionare disclosed in the dependent claims.

One or more examples of implementations are set forth in more detailin the accompanying drawings and the description below. Other features will beapparent from the description and drawings, and from the claims.

The embodiments and features described in this specification that donot fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention.

Brief description of the drawings ln the following the invention will be described in greater detail bymeans of preferred embodiments with reference to the accompanying drawings, inwhich Figures 1A, 1B and 2 illustrate examples of an apparatus; Figures 3A and 3B illustrate examples of the apparatus when installedon a conduit or pipe where dust is ﬂowing; Figure 4 is a ﬂowchart illustrating an example of an embodiment.

Detailed description of some embodiments The solution according to the invention is suitable for sampling any kindof ﬂowing dust. ln an embodiment, the dust is ﬂowing in a pipe or conduit wherethere may be a negative pressure. The apparatus is attachable to a conduit or pipein a simple manner. ln an embodiment, a simple hole may be drilled into the pipewall and the apparatus can be installed into the hole.

Collecting dust samples from conduits is problematic as dust has atendency to cumulate into dust collector and block the operation of the collector.

Figs. 1A, 1B, and 2 illustrate examples of an apparatus 100. Theapparatus 100 for collecting dust samples comprises a piston 102 and a cylinderstructure or a piston chamber 110 for holding the piston. The piston is configuredto move inside the cylinder structure between an inward position and an outwardposition. Fig. 1A illustrates the apparatus when the piston 102 is in the inwardposition. Fig. 1B illustrates an example of the cylinder structure without the piston.Fig. 2 illustrates the apparatus when the piston 102 is in the outward position.

The piston 102 comprises a body having an inner end 104 and an outerend 106. The inner end ofthe piston is always inside the cylinder structure. ln an embodiment, the piston comprises a hole 108 in the longitudinalside ofthe body, the hole extending through the body in a direction perpendicularto a movement of the piston. ln an embodiment, the cross section of the hole iscircular or elliptical. However, the cross section may also have any other shape. ln an embodiment, the cylinder structure 110 has a first end 112, whichis open. The first end of the cylinder may be slanted such that underside 130 of thecylinder extends farther than upper side 132. The outer end 106 of the piston issubstantially level with or extending farther than the underside of the first end of the cylinder when the piston is in an inward position.

The apparatus may comprise a mechanism 114 configured to move thepiston between the inward position and an outward position. ln an embodiment,the mechanism utilises compressed air to move the piston.

The apparatus may comprise detectors 124, 126 for detecting when thepiston is in the inward position and in the outward position. ln an embodiment, thepiston is attached to a shaft 128. The detectors may detect the movement orposition of the shaft. ln an embodiment, the cylinder structure comprises an input feed 116at the upper side wall of the cylinder structure and an output feed 118 at theunderside wall of the cylinder structure. The input and the output feeds may be onthe opposite sides of the cylinder wall. ln an embodiment, the feeds are atsubstantially the same distance from the upper end 132 of the first end 112 ofthecylinder. ln an embodiment, the cylinder structure has a larger diameter than thepiston and there is an open space 138 formed around the piston inside the cylinderstructure up till the first end 112 of the cylinder structure. ln an embodiment, thedifference between the diameter of the cylinder structure and the diameter of thepiston is between millimetres to tens of millimetres. At the first end 112 of thecylinder structure, the cylinder structure has a section 140 having a diametercorresponding to the diameter of the piston. The section and the piston sealshermetically the open space 138 around the piston and the hole 108 inside thecylinder structure from outside. ln an embodiment, the length of the section 140 is substantially shorterthan the length of the whole structure. ln an embodiment, the cylinder structure ismade of a single piece of material. lt may also be manufactured of multiplecomponents. ln an embodiment, the apparatus comprises a connector 134connecting input feed to a ﬂuid line 136 configured to feed ﬂuid through the holefilled with dust to the output feed. ln an embodiment, when the piston is in the inward position illustratedin Fig.1A, the hole of the piston is between the input and output feeds of thecylinder structure.

When the piston is in the outward position as illustrated in Fig.2, thehole of the piston is outside the upper side 132 of the first end of the cylinder and the underside of the hole is inside the underside of the cylinder structure. Thus, the hole and the underside of the cylinder form a space open at upper side but closedat the bottom.

Figs. 3A and 3B illustrate examples of the apparatus 100 connected to aconduit or pipe 300 where dust or ash is ﬂowing. The apparatus 100 may beinstalled to a wall 302 ofthe conduit or pipe 300 by preparing a suitable hole in thewall 302 and fixing the apparatus to the hole, for example with a ﬂange 332. ln thisexample, the dust is ﬂowing downwards inside the conduit or pipe 300. ln anembodiment, the conduit or pipe has a negative pressure.

Fig. 3A illustrates a situation where the apparatus is installed and whenthe piston 102 is in the inward position. Fig. 3B illustrates a situation where theapparatus is installed and when the piston 102 is in the outward position. ln the examples of Fig. 3A and 3B the input feed 116 at the upper sidewall of the cylinder structure is connected to ﬂuid supplies 304, 306 via valves 308,310 and connector 134. Further, the output feed 118 at the underside wall of thecylinder structure is connected to sample analyser cavity 314. ln an embodiment,the ﬂuid supplies 304, 306 are water and gas supplies. The gas may be air or someother gas. ln an embodiment, the amount of gas and water is adjusted and regulatedfor constant ﬂow. ln an embodiment, the water pressure may be is monitored witha pressure sensor 320 to detect pressure loss and sample line blockages. ln an embodiment, the apparatus is configured to receive one or morecontrol signals 318 controlling the movements of the piston and valves 308, 310feeding of ﬂuid to input feed 116.

As mentioned, in an embodiment, the piston 102 and the section 140 atthe open end of the cylinder structure are configured to hermitically seal theconduit from the hole 108 and the open space 138 around the piston from eachother while the piston is in the inward position.

As mentioned, the outer end 106 ofthe piston is substantially level withor extending farther than the underside 130 of the first end of the cylinderstructure when the piston is in the inward position. Also this protects the cylinderstructure from the dust ﬂowing in the conduit. The dust may not enter the cylinderstructure and cause blockages possibly disturbing the piston movement.

Fig. 4 is a ﬂowchart illustrating the operation of collecting a sample ofdust ﬂowing in the conduit or pipe 300 with the apparatus 100. ln the beginning ofthe process, the piston 102 is in the inward position as illustrated in Fig. 3A, valves308, 310 and the output valve 312 are closed. The outer end of the piston 102 is substantially level with the underside of the first end of the cylinder when thepiston is in the inward position. ln step 400, the piston is moved to outward position to gather dust. Thesituation is as illustrated in Fig. 3B. When the piston is in the outvvard position, thehole 108 of the piston is outside the upper side ofthe first end of the cylinder andthe underside of the hole is inside the underside of the first end of the cylinderstructure. ln an embodiment, the edges 120, 122 of the hole in the piston mayscrape the inside surface of cylinder clean of dust when the piston moves betweenthe inward position and the outward position. ln an embodiment, edges of thesection 140 scrape the piston clean of dust when the piston moves between theinward position and the outward position. ln step 402, dust moving in the conduit or pipe 300 gathers in the spaceformed by the hole and the underside of the cylinder structure. ln an embodiment, the piston stays in the outvvard position for apredetermined time. ln step 404, the piston is moved to the inward position. This way thedust gathered in the space formed by the hole in the piston and the underside ofthe cylinder structure is moved from the conduit or pipe 300 inside the apparatusbetween the input and output feeds 116, 118.

Again, as the piston moves to the inward position, the edges 120, 122 ofthe hole in the piston scrape the inside surface of cylinder clean of dust when thepiston moves from the inward position to the outward position. ln step 406, the valves 308, 310 are opened., Thus, ﬂuid coming fromthe ﬂuid supplies 304, 306 via the connector 134 and the input feed 116 ﬂush thedust from the hole 108 to the sample analyser cavity 314 via the output feed 118.The ﬂuid ﬂushes also the open space 138 around the piston. ln an embodiment, theinput feed comprises a nozzle to spray the ﬂuid into the open space around thepiston to ﬂush dust from the open space into the output feed. lt may be noted herethat the piston 102 and the section 140 at the open end of the cylinder structureseal the open space from the conduit. Thus, ﬂuid from the input feed does not enterthe conduit but is limited to the open space and the hole. The cavity receives thusthe dust ﬂuid. ln an embodiment, the ﬂuid is a mixture of water and air or someother gas. After a given amount of ﬂuid is ﬂushed the valves 308, 310 are closed.The amount of ﬂuid may be a system parameter. Flushing the space 138 around thepiston and the hole with the ﬂuid effectively cleans the open space and the hole ofany dust. Thus, the dust will not dust get cloddy and block the apparatus. This lengthens the time the apparatus may be used without any maintenance such asadditional Cleaning. ln an embodiment, the three above steps are performed a given numberof times. Thus, dust samples may be gathered for example three times into thesample analyser cavity 314 before sample analysis is performed. ln this way, asuitable amount of dust and ﬂuid may be gathered. ln step 408, it is checked whether a given number of samples have beengathered. lf not, the process continues in step 400. lt may be noted that the length of the output feed 118 connecting theapparatus to the sample analyser cavity 314 is not limited to any given length. Asthe ﬂuid ﬂushes the dust into the output feed, the ﬂuid may travel along the feed tothe sample analyser cavity several metres or tens or hundreds of meters, for example. ln step 410, one or both of the valves 308, 310 are opened and the holeand the open space around the piston is dried. ln an embodiment, the drying isperformed with the same ﬂuid as in step 406. ln an embodiment, the cleaning isperformed with gas only. The gas may be air, or it may also be some other gas. ln an embodiment, where the hole and the open space around the pistonare dried using air or some other gas, the air or other gas may enter the sampleanalyser cavity at the end of the output feed but it may leak out from the cavity andnot disturbing the sample.

The collected sample of dust and ﬂuid may then be analysed in thesample analyser cavity 314 or the collected sample of dust and ﬂuid may be takenelsewhere for analysis. lt will be obvious to a person skilled in the art that, as the technologyadvances, the inventive concept can be implemented in various ways. Theinvention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

1. An apparatus (100) for collecting dust samples, comprising a piston (102) and a cylinder structure (110) for holding the piston; thepiston with a body having an inner end (104) and an outer end (106), the inner endbeing always inside the cylinder structure, the piston comprising a hole (108) inthe longitudinal side ofthe body, the hole extending through the body in a directionperpendicular to a movement of the piston; the cylinder structure (110) having a first end (112), which is open, thefirst end of the cylinder being slanted such that underside (130) of the cylinderextends farther than upper side (132), the outer end (106) of the piston beingsubstantially level with or extending farther than the underside of the first end ofthe cylinder when the piston is in an inward position; a mechanism (114) configured to move the piston between the inwardposition and an outward position; the cylinder comprising an input feed (116) at the upper side wall of thecylinder, and an output feed (118) at the underside wall of the cylinder, the inputand the output feeds being on the opposite sides of the cylinder wall,characterised by the hole (108) being outside the upper side (132) of the first end ofthecylinder and the underside ofthe hole being inside the underside (130) ofthe firstend of the cylinder when the piston is in the outward position, the hole (108) andthe underside ofthe cylinder forming a space open at upper side but closed at thebottom for gathering dust ﬂowing past the piston; the hole of the piston being between the input and output feeds whenthe piston is in the inward position; the input feed being connected to a ﬂuid line (136) for spreading ﬂuidthrough the hole filled with dust to ﬂush the dust to the output feed when the piston is in the inward position.

2. The apparatus as claimed in claim 1, wherein the cylinder structurehas a larger diameter than the piston and there is an open space (138) formedaround the piston inside the cylinder structure up till the first end (112) of thecylinder structure, the first end of the cylinder structure having a section (140)with a diameter corresponding to the diameter of the piston and hermetically sealing the open space around the piston inside the cylinder structure from outside.

3. The apparatus as claimed in claim 2, wherein the input feedcomprises a nozzle to spray the ﬂuid into the open space around the piston to ﬂush dust into the output feed.

4. The apparatus as claimed in any preceding claim, the hole in thepiston comprising edges (120, 122) configured to scrape the inside surface ofcylinder clean of dust when the piston moves between the inward position and the outward position.

5. The apparatus as claimed in claim 1, wherein the apparatus isconfigured to move the piston to outvvard position to gather dust, move the piston to inward position; ﬂush the dust from the hole to the sample analyser cavity with anamount of ﬂuid from the input feed, perform the three above steps a given number of times.

6. The apparatus as claimed in claim 5, wherein the apparatus isconfigured, when the piston is in the inward position, toclean the hole and open space formed around the piston inside the cylinder structure with an amount of gas or ﬂuid from the input feed.

7. The apparatus as claimed in claim 1, wherein the ﬂuid is a mixture of water and gas.

8. A method of collecting dust samples from a conduit in which dust isﬂowing, the method comprising: controlling movement of a piston (102) inside a cylinder structure(110) for holding the piston; the piston with a body having an inner end (104) andan outer end (106), the inner end being always inside the cylinder structure, thepiston comprising a hole (108) in the longitudinal side of the body, the holeextending through the body in a direction perpendicular to a movement of thepiston; the cylinder structure (110) having a first end (112), which is open, thefirst end of the cylinder being slanted such that underside of the cylinder extends farther than upper side, the outer end (106) of the piston being substantially level with or extending farther than with the underside of the first end of the cylinderwhen the piston is in an inward position, the first end (112) being inside theconduit; moving (400, 402) the piston to an outward position to gather dustﬂowing in the conduit into the hole ofthe piston, the hole being outside the upperside of the first end of the cylinder and the underside of the hole being inside theunderside ofthe first end ofthe cylinder, characteris ed by the hole (108) and theunderside of the cylinder forming a space open at upper side but closed at thebottom; moving (404) the piston to the inward position where the hole of thepiston is between an input feed (116) at the upper side wall ofthe cylinder, and anoutput feed (118) at the underside wall of the cylinder, the feeds being on theopposite sides of the cylinder wall; ﬂushing (406) the dust from the hole to the output feed with an amountof ﬂuid from the input feed.

9. The method as claimed in claim 8, further comprising: spraying theﬂuid into an open space around the piston inside the cylinder structure to ﬂushdust into the output feed, the open space being formed by the cylinder structurehaving a larger diameter than the piston up till the first end of the cylinderstructure, the first end of the cylinder structure having a section with a diametercorresponding to the diameter of the piston and hermetically sealing the open space around the piston inside the cylinder structure.

10. The method as claimed claim 8 or 9, further comprising: receivingone or more control signals controlling the movements of the piston and thefeeding ofthe ﬂuid.

11. The method as claimed any preceding claim 8 to 10, furthercomprising: scraping the surface of the piston clean of dust with edges of section(140) ofthe cylinder structure when the piston moves between the inward position and the outward position.

12. The method as claimed claim 8, further comprising:cleaning the hole and open space formed around the piston inside the cylinder structure with an amount of gas or ﬂuid from the input feed.

13. The method as claimed any preceding claim 8 to 12, wherein the conduit has a negative pressure.