The exemplary and non-limiting embodiments of the invention relate generally to collecting pulp samples. Background

Automation systems are widely used in measuring and controlling various industrial processes such as paper and pulp or chemical factories. In many processes pulp is produced in some form and analysing the amount and properties of the pulp is important when monitoring and controlling the process. An example of process is TMP refining process where the pulp is refined to meet the quality requirements for the next process phase. Analysing the newly refined pulp has been problematic because of the pressurized hot steam in the blowline from where the sample is needed. Brief description

An object of the invention is to provide an improved method and an apparatus implementing the method to reduce or avoid the above-mentioned problems.

The objects of the invention are achieved by an apparatus as claimed in claim 1 and by method as claimed in claim 7. Some embodiments of the invention are disclosed in the dependent claims.

One or more examples of implementations are set forth in more detail in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. The embodiments and features described in this specification that do not 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

In the following the invention will be described in greater detail by means of preferred embodiments with reference to the accompanying drawings, in which

Figures 1A, IB and 2 illustrate examples of an apparatus; Figures 3A and 3B illustrate examples of the apparatus when installed on a conduit or pipe where pulp is flowing;

Figure 4 is a flowchart illustrating an example of an embodiment;

Figure 5 is an exemplary installation of the apparatus. Detailed description of some embodiments

The solution according to the invention is suitable for sampling any kind of flowing pulp. In an embodiment, the pulp is flowing in a pipe or conduit where there may be a high pressure. The apparatus is attachable to a conduit or pipe in a simple manner. In an embodiment, a simple hole may be drilled into the pipe wall and the apparatus can be installed into the hole. One example application is first stage HC-refining in ThermoMechanicalPulp (TMP) or Chemi- ThermoMechanicalPulp (CTMP) plant. The impregnated pulp is fed to the refiners and that blow out the refined pulp in blowlines. The pulp within the blowlines is in high pressure, moist and temperature. Similar conditions are also with second stage LC refiners. Additionally, any pipeline with similar conditions may be suitable e.g. cooking blowline and output of Medium Density Fiberboard (MDF) defibrator.

Collecting pulp samples from conduits is problematic as pulp has a tendency to cumulate into pulp collector and block the operation of the collector. Additionally, the steam causes problems to the sampling and analyzing devices due to the high temperature and pressure.

Figs. 1A, IB, and 2 illustrate examples of an apparatus 100. The apparatus 100 for collecting pulp samples comprises a piston 102 and a cylinder structure or a piston chamber 110 for holding the piston. The piston is configured to move inside the cylinder structure between an inward position and an outward position. Fig. 1A illustrates the apparatus when the piston 102 is in the inward position. Fig. IB 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 outer end 106. The inner end of the piston is always inside the cylinder structure. In an embodiment, the piston comprises a hole 108 in the longitudinal side of the body, the hole extending through the body in a direction perpendicular to a movement of the piston. In an embodiment, the cross section of the hole is circular or elliptical. However, the cross section may also have any other shape. In an embodiment, the cylinder structure 110 has a first end 112, which is open. The first end of the cylinder may be slanted such that underside 130 of the cylinder extends farther than upper side 132.

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

The apparatus may comprise detectors 124, 126 for detecting when the piston is in the inward position and in the outward position. In an embodiment, the piston is attached to a shaft 128. The detectors may detect the movement or position of the shaft.

In an embodiment, the cylinder structure comprises an input feed 116 at the upper side wall of the cylinder structure and an output feed 118 at the underside wall of the cylinder structure. The input and the output feeds may be on the opposite sides of the cylinder wall. In an embodiment, the feeds are at substantially the same distance from the upper side 132 of the first end 112 of the cylinder.

In an embodiment, the cylinder structure has a larger diameter than the piston and there is an open space 138 formed around the piston inside the cylinder structure up till the first end 112 of the cylinder structure. In an embodiment, the difference between the diameter of the cylinder structure and the diameter of the piston is a between few millimetres to few centimetres. At the first end 112 of the cylinder structure, the cylinder structure has a section 140 having a diameter corresponding to the diameter of the piston. The section and the piston seals hermetically the open space 138 around the piston and the hole 108 inside the cylinder structure from outside.

In an embodiment, the length of the section 140 is substantially shorter than the length of the whole structure. In an embodiment, the cylinder structure is made of a single piece of material. It may also be manufactured of multiple components. In an embodiment, the apparatus comprises a connector 134 connecting input feed to a fluid line 136 configured to feed fluid through the hole filled with pulp to the output feed.

In an embodiment, when the piston is in the inward position illustrated in Fig.lA, the hole of the piston is between the input and output feeds of the cylinder structure. When the piston is in the outward position as illustrated in Fig.2, the hole 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 closed at the bottom.

Figs. 3A and 3B illustrate examples of the apparatus 100 connected to a conduit or pipe 300 where pulp is flowing. The apparatus 100 may be installed to a wall 302 of the conduit or pipe 300 by preparing a suitable hole in the wall 302 and fixing the apparatus to the hole, for example with a flange 332. In this example, the pulp is flowing downwards inside the conduit or pipe 300. In an embodiment, the conduit or pipe has a positive pressure.

Fig. 3A illustrates a situation where the apparatus is installed and when the piston 102 is in the inward position. Fig. 3B illustrates a situation where the apparatus is installed and when the piston 102 is in the outward position. In the examples of Fig. 3A and 3B the input feed 116 at the upper side wall 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 the cylinder structure is connected to sample analyser cavity 314. In an embodiment, the fluid supplies 304, 306 are water and gas supplies. The gas may be air or some other gas. In an embodiment, the amount of gas and water is adjusted and regulated for constant flow. In an embodiment, the water pressure may be monitored with a pressure sensor 320 to detect pressure loss and sample line blockages.

In an embodiment the input feed 116 is used for inputting cooling water to the taken sample. This is required when the pulp flowing in the conduit or pipe 300 is a mixture of pulp and steam. The cooling water may be used to dilute 50-60 m-% sample to 1-5 m-% consistency. This is the case e.g. when apparatus is taking sample from blowline.

In an embodiment, the apparatus is configured to receive one or more control signals 318 controlling the movements of the piston and valves 308, 310 feeding of fluid to input feed 116.

As mentioned, in an embodiment, the piston 102 and the section 140 at the open end of the cylinder structure are configured to hermitically seal the conduit from the hole 108 and the open space 138 around the piston from each other while the piston is in the inward position. In an embodiment, a steam seal 307 is attached on the end 106 of the piston. This steam seal can be a conical metal cap or any other shaped cap, that tightens against the opening of the section 140 at the open end of the cylinder structure when the piston is in the inward position. The pressure in the pipe 300 may also force the steam seal tighter against the opening. The steam seal may have an shape in the edge that fits with the underside 130 of the first end of the cylinder structure so that it can be used for scraping the pulp that accumulate on the underside while the piston moves outward.

Fig. 4 is a flowchart illustrating the operation of collecting a sample of pulp flowing in the conduit or pipe 300 with the apparatus 100. In the beginning of the process, the piston 102 is in the inward position as illustrated in Fig. 3A, valves 308, 310 and the output valve 312 are closed.

In step 400, the piston is moved to outward position to gather pulp. The situation is as illustrated in Fig. 3B. When the piston is in the outward position, the hole 108 of the piston is outside the upper side of the first end of the cylinder and the underside of the hole is inside the underside of the first end of the cylinder structure. In an embodiment, the edge 121 of the hole in the piston cuts the fibers and other particles of the pulp when the piston is moving inward and the hole passes the opening of the section 140 at the open end of the cylinder structure. In an embodiment, the edges 120, 121, 122 of the hole in the piston may scrape the inside surface of cylinder clean of pulp when the piston moves between the inward position and the outward position. In an embodiment, edges of the section 140 scrape the piston clean of pulp when the piston moves between the inward position and the outward position.

In step 402, pulp moving in the conduit or pipe 300 gathers in the space formed by the hole and the underside of the cylinder structure. In an embodiment, the piston stays in the outward position for a predetermined time.

In step 404, the piston is moved to the inward position. This way the pulp gathered in the space formed by the hole in the piston and the underside of the cylinder structure is moved from the conduit or pipe 300 inside the apparatus between the input and output feeds 116, 118.

Again, as the piston moves to the inward position, the edges 120, 121, 122 of the hole in the piston scrape the inside surface of cylinder clean of pulp when the piston moves from the inward position to the outward position. In step 406, the valves 308, 310, 312 are opened. Thus, fluid coming from the fluid supplies 304, 306 via the connector 134 and the input feed 116 flush the pulp from the hole 108 to the sample analyser cavity 314 via the output feed 118. While the piston is in inward position, the steam seal 307 keeps the hot steam from flowing from the pipe to the internal parts of the apparatus and especially protects the parts of the analyser cavity 314 and the analyser devices therein. The fluid flushes also the open space 138 around the piston. In an embodiment, the input feed comprises a nozzle to spray the fluid into the open space around the piston to flush pulp from the open space into the output feed. It may be noted here that the piston 102 and the section 140 at the open end of the cylinder structure seal the open space from the conduit. Thus, fluid from the input feed does not enter the conduit but is limited to the open space and the hole. The cavity receives thus the pulp fluid. In an embodiment, the fluid is a mixture of water and air or some other 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 the piston and the hole with the fluid effectively cleans the open space and the hole of any dust. Thus, the pulp will not get cloddy and block the apparatus. This lengthens the time the apparatus may be used without any maintenance such as additional cleaning.

In an embodiment, the three above steps are performed a given number of times. Thus, pulp samples may be gathered for example three times into the sample analyser cavity 314 before sample analysis is performed. In this way, a suitable amount of pulp and fluid may be gathered.

Meanwhile, it is checked whether a given number of samples have been gathered. If not, the process continues in step 400.

It may be noted that the length of the output feed 118 connecting the apparatus to the sample analyser cavity 314 is not limited to any given length. As the fluid flushes the pulp into the output feed, the fluid may travel along the feed to the sample analyser cavity several metres or tens or hundreds of meters, for example. In one optional step, one or both of the valves 308, 310 are opened and the hole and the open space around the piston is dried. In an embodiment, the drying is performed with the same fluid as in step 406. In an embodiment, the cleaning is performed with gas only. The gas may be air, or it may also be some other gas.

In an embodiment, where the hole and the open space around the piston are dried using air or some other gas, the air or other gas may enter the sample analyser cavity at the end of the output feed but it may leak out from the cavity and not disturbing the sample. The collected sample of pulp and fluid may then be analysed in the sample analyser cavity 314 or the collected sample of pulp and fluid may be taken elsewhere for analysis.

The apparatus may be installed in different orientations to meet the flow of the pulp. In case the pulp is flowing vertically upwards in the pipe, the apparatuses slanted end may be set so that the underside 130 of the cylinder that extends farther than upper side 132 is turned to be upside down. Similarly if the flow in the pipe is horizontal, the sampler may be set to an angle so that the when the piston is in the outward position, the hole 108 of the piston is outside and the flowing pulp may flow directly to the hole 108. Terms upside and downside may also be understood so that upside is the direction where the flow is coming from and downside the direction where the flow is going to in the pipe.

Fig 5. shows an exemplary installation of the apparatus 100 into a blowline 501. The pulp flows from impregnation phase 502 to a 1 ^st stage refiner 503 that blows the mixture of pulp and hot steam in high pressure to the blowline towards the next process phase which is the bleaching 504. The pulp flows in the blowline upwards and therefore the orientation of the apparatus’s piston 102 and hole 108 of the piston corresponds to the flow so that the pulp flows towards the hole opening when the piston is outside. It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.