FI20235785A1 - Soap separation monitoring and control - Google Patents

Abstract

A control arrangement for monitoring a separation of the liquid, comprising imaging means (110) arranged to image a target area from the surface of a liquor storage tank (10); illumination means arranged to illuminate the target area; at least one support means (42,44) carrying a device housing (100) on its end and arranged to be removably mounted in a mounting opening in a service hatch cover on top of the liquor storage tank such that the end carrying the device housing is inside the tank, wherein the imaging means and the illumination means are placed inside the device housing of at least one of the support means; wherein the device housing comprises an optical element (120) arranged to provide the imaging means and the illumination means with a field of view of the target area; the vertical position and angle of the device housing relative to the device housing of at least one of the support means are adjustable to adjust the field of view of the imaging means; and wherein the imaging means (110) is arranged to image at least two frames of a target area, wherein the target area comprises at least a portion of the liquor storage tank (10) and at least a portion of the sludge overflow channel (120). Also a method and control system.

Description

SOAP SEPARATION MONITORING AND CONTROL

TECHNICAL FIELD

The present disclosure generally relates to soap separation from alkaline liquors. The disclosure relates particularly, though not exclusively, to soap separation and tall oil production at a pulp mill. The disclosure relates particularly, though not exclusively, to measurement and control of soap separation.

BACKGROUND

This section illustrates useful background information without admission of any technique described herein representative of the state of the art. — Soap separation and tall oil production is an important part of chemical recovery at a pulp mill processing softwood. Greases and resin acids at least in part saponify during sulphate pulping in alkaline liquor and dissolve therein. When the black liquor is led to an applicable storage tank and allowed to settle, the soap separates and forms a layer on the liquor surface. This raw soap rising to the surface can be skimmed and collected and processed further in tall oil production.

Typically, the soap separation is carried out using liquor tank overflow into overflow channels. The overflow channels convey the soap into a soap storage tank. During soap collection, there is a risk of excess black liquor ending up in the overflow channels and subsequently to the soap storage tank which is detrimental to the tall oil production process and chemicals use therein.

Currently, the soaping phenomena in the liquor storage tank can only be observed manually, i.e. through physical checks through manholes placed on top of the storage tank

O

N and hence the process operator has no overview of the process in the operating room.

N

N Accordingly, there is a need for a solution allowing remote observation and guantifiable 2 25 measurements of the soaping activity. It is the objection of the present invention to provide

I such an arrangement and method. a 3 SUMMARY

LO

Q The appended claims define the scope of protection. Any examples and technical

N descriptions of apparatuses, products and/or methods in the description and/or drawings not covered by the claims are presented not as embodiments of the invention but as background art or examples useful for understanding the invention.

According to a first example aspect there is provided a soap separation monitoring arrangement, comprising imaging means configured to image an area of interest of a surface of a liquor storage tank; illuminating means configured to illuminate the area of interest; at least one support means supporting at an end thereof an instrumentation case and configured to be releasably installed at an installation duct in a cover of a manhole on top of the liquor storage tank so that the end supporting the instrumentation case is inside the tank, wherein the imaging means and the illuminating means are positioned inside the instrumentation case of the at least one support means; wherein the instrumentation case comprises an optics element configured to provide the imaging means and illuminating means with a field of view to the area of interest; the vertical position and angle with respect to the support means of the instrumentation case is adjustable for adjusting the field of view of the imaging means; and wherein the imaging means are configured to image at least two image frames of the area of interest, wherein the area of interest comprises at least a part of the liquor storage tank and at least a part of a soap overflow channel.

The at least one support means may comprise two support means comprising an instrumentation case, wherein first and second support means are spatially separated and the imaging means are positioned inside the instrumentation case of the first support means and the illuminating means are positioned inside the instrumentation case of the second support means.

N

< The arrangement may further comprise cooling means for cooling the instrumentation case

N 25 — by conveying cooling gas into the instrumentation case.

S The arrangement may further comprise washing means for keeping the optics element

E clean by conveying washing fluid on the external surface of the optics element. 10 The imaging means may comprise a digital video camera.

N

LO

Q The illuminating means comprise a light emitting diode or an array of light emitting diodes.

O

N

According to a second example aspect there is provided a soap separation monitoring method, comprising imaging an area of interest on the surface of a liquor storage tank by imaging means, wherein the area of interest comprises at least a part of the liquor storage tank and at least a part of a soap overflow channel; selecting two image frames showing the area of interest, wherein the selected frames have atime interval; and determining a property of interest based on the selected frames, wherein the property of interest is selected from the group of moving mass detection, soaping velocity measurement, soaping detection and flowing liquor detection.

The method may further comprise controlling the soap separation process based on the result of determining the property of interest.

The method may further comprise illuminating the area of interest with illuminating means.

Determining the property of interest may first comprise selecting a region of interest from the selected frames depending on the property of interest to be determined.

Determining the property of interest may comprise determining using image processing and/or image analysis algorithms.

According to a third example aspect there is provided a control system for soap separation comprising: the arrangement of the first example aspect; a control unit, comprising at least one memory comprising computer executable program code, and at least one processor configured cause the control system to perform, when executing the program code, the method of the second example aspect. e The control system may further comprise an actuator unit; wherein the at least one

N . . .

E processor is configured cause the control system to perform, when executing the program

K code, the method of the second example aspect.

O

2 25 According to a fourth example aspect there is provided a computer program comprising =E computer executable program code which when executed by the at least one processor of a

LO the control system of the fourth example aspect causes the control system to at least to

S perform the method the second example aspect 0

O According to a fifth example aspect there is provided A non-transitory memory medium, comprising the computer program of the fourth example aspect.

Any foregoing memory medium may comprise a digital data storage such as a data disc or diskette; optical storage; magnetic storage; holographic storage; opto-magnetic storage; phase-change memory; resistive random-access memory; magnetic random-access memory; solid-electrolyte memory; ferroelectric random-access memory; organic memory; or polymer memory. The memory medium may be formed into a device without other substantial functions than storing memory or it may be formed as part of a device with other functions, including but not limited to a memory of a computer; a chip set; and a sub assembly of an electronic device.

Different non-binding example aspects and embodiments have been illustrated in the foregoing. The embodiments in the foregoing are used merely to explain selected aspects or steps that may be utilized in different implementations. Some embodiments may be presented only with reference to certain example aspects. It should be appreciated that corresponding embodiments may apply to other example aspects as well.

BRIEF DESCRIPTION OF THE FIGURES

Some example embodiments will be described with reference to the accompanying figures, — in which:

Fig. 1A schematically shows a principle view of the environment in which the present invention according to example embodiments is applicable;

Fig. 1B schematically shows an enlarged view of the surface area of a storage tank in which the present invention according to example embodiments is applicable;

Fig. 2 shows a schematic view of an arrangement according to an example embodiment of the present invention;

Fig. 3 shows a further schematic view of an arrangement according to an example embodiment of the present invention;

Fig. 4A shows a flow chart of a method according to an example embodiment of the present @ 25 invention; < Fig. 4B shows a further flow chart of a method according to an example embodiment of the 5 present invention; and 2 Fig. 5 shows a schematic block view of a control system according to an example

I embodiment of the present invention. a

O 30 DETAILED DESCRIPTION

N

2 In the following description, like reference signs denote like elements or steps.

O

N Fig. 1A schematically shows a principle view of the environment in which the present invention according to example embodiments is applicable. Fig. 1A shows a liquor storage tank 10 configured to store liquor from a pulping process of a pulp mill. While not depicted in Fig. 1A, the storage tank 10 comprises at least one inlet for feeding liquor into the tank and at least one outlet for conveying liquor that has been stored in the tank and settled to further processing. 5 The storage tank 10 comprises, at the top thereof, at least one manhole, or hatch, 30 through which the liquor in the tank can be observed visually. While Fig. 1A shows a single manhole 30, the number of manholes is chosen in accordance with each tank and the process and accordingly the number of manholes 30 is typically larger than one. The manhole 30 is typically covered with a hinged lid that can be opened.

The storage tank 10 further comprises at least one overflow channel 20 configured to convey, with the help of gravitation, the soap formed on top of the liquor and overflowing the edge of the overflow channel to a soap storage tank (not shown). While Fig. 1A shows a single overflow channel 20, the number of overflow channels is chosen in accordance with each tank and the process and accordingly the number of overflow channels typically — is larger than one. In an embodiment, the overflow channels 20 start at an edge of the tank and advance in towards the opposite edge of the tank.

Fig. 1A further shows a soap separation monitoring arrangement according to an example embodiment of the invention and described in more detail hereinafter. The soap separation monitoring arrangement comprises in an embodiment imaging means and illuminating means for illuminating and imaging the surface of the liquor in the tank 10 and the overflow channel 20.

Fig. 1B schematically shows an enlarged view of the surface area of a storage tank in which the present invention according to example embodiments is applicable, i.e. Fig.1B schematically shows the field of view of the soap separation monitoring arrangement en 25 according to an example embodiment, showing the liguor surface and the edge of the

S overflow channel 20 from the top and a part of the overflow channel 20 from the top. In a

N further example embodiment, the imaging means are positioned in such away that the

O imaging is not directly above the area of the surface to be imaged but at an angle thereto. = Fig. 1B further schematically shows an example of regions of interest 1-3, ROI, in the field o 30 of view of the soap separation monitoring arrangement. In an embodiment, the region of 2 interest 3 comprises the tank surface, the region of interest 2 the edge of the overflow 2 channel 20 and region of interest 1 a part of the overflow channel 20.

N Fig. 2 shows a schematic view of an arrangement according to an example embodiment of the present invention. Fig. 2 shows the manhole 30 as viewed from outside the liquor storage tank. The manhole 30 is covered with openable lids, or hatches, 32,34 comprising hinges 36,38. Fig. 2 shows the manhole 30 covered with two separate lids 32,34 but in a further embodiment the number of lids is one or more than two depending for example on the need for manual access through the manhole.

Atleast one of the lids, in the example embodiment shown in Fig. 2, the lid 34, comprises at least one installation duct 46, 48 configured to releasably receive support means 42,44 of the soap separation monitoring arrangement according to an example embodiment. In an embodiment, the at least one support means 42,44 comprise a rod inserted through the duct 46,48 and carrying at the lower end thereof instrumentation as described in detail hereinafter.

While Fig. 2 shows an example embodiment with two support means, in a further embodiment the lid 34 comprises a single duct and the arrangement comprises a single support means carrying instrumentation. In an example embodiment, the first support means 42 is configured to carry the imaging means and the second support means 44 is configured to carry the illuminating means. Providing the imaging means and illuminating means on separate support means, in an example embodiment spatially separated from each other by a predetermined distance, provides for an improved illumination for the imaging means in certain conditions, for example in case of fog-like vapours forming inside the tank.

Fig. 3 shows a further schematic view of an arrangement according to an example embodiment of the present invention. The arrangement comprises support means 42 releasably installed at an installation duct of a manhole on top of a liquor storage tank.

The support means comprise at a lower end thereof an instrumentation case 100. In the example embodiment of Fig. 3, the arrangement comprises an imaging means 110 inside en 25 the instrumentation case 100. The instrumentation case protects the imaging means 110

S from the environment inside the liguor tank.

S In an embodiment, the imaging means comprise a digital camera or a digital video camera. 3 In an embodiment, the imaging means comprise elements such as a charge coupled device,

E CCD, imaging sensor, a complementary metal oxide semiconductor, CMOS, imaging

LO 30 sensor, or a further digital imaging system. 00 5 The imaging means 110 are configured to image, or capture, digital images, or frames, from

O the area of interest in the field of view of the imaging means 110. In an embodiment, the imaging means are configured to capture a seguence of still images with predetermined time intervals. In a further embodiment, the imaging means 110 are configured to image, or capture, a video sequence from the area of interest in the field of view of the imaging means 110 for a predetermined time. In an example embodiment, the imaging means are configured to continuously image a video from the area of interest in the field of view of the imaging means 110.

In an embodiment, the imaging means 110 comprise a communication interface for sending the imaged date for example to a control system. In an embodiment, the communication interface comprises a wired or wireless connection from the imaging means to an entity outside the tank. In a further embodiment, the imaging means are configured to receive commands or instructions via the communication interface from an entity outside the tank, — for example from a control system or an operator. In an embodiment, the imaging means comprise or are connected with a processor configured to control the communication interface.

The arrangement further comprises optics element 120 for providing the imaging means with a field of view to the liquor surface to be monitored as hereinbefore exemplified with reference to Fig. 1B. In an embodiment, the optics element 120 comprises a lens with suitable optical properties and suitable mechanical properties for withstanding the environment in the tank. In a further example embodiment, the optics element comprises in addition to or instead of a lens, further optical components such as further lenses, prisms, mirrors or fibreoptics.

The support means 42 further comprise, in an example embodiment, a pivot element 130 comprising a swivel joint 140 configured to allow the instrumentation case 100 to be pivoted in various angles and directions in order to adjust the field of view of the imaging means 110. In an embodiment, the vertical position of the instrumentation case 100 is adjustable, i.e. the vertical position thereof can be changed along the length of the support means. en 25 In an example embodiment, the arrangement comprises cooling means for cooling the

S instrumentation case in order to keep the instrumentation, i.e. the imaging means 110 as

N shown in Fig. 3, in a suitable operating temperature. In an embodiment, the cooling means

O comprise a gas inlet line 160 for conveying gas, for example air, in suitable temperature = inside the instrumentation case 100 through a cooling outlet 165. The cooling gas exits the o 30 instrumentation case through a gas outlet line 170.

E In an example embodiment, the arrangement comprises washing, or flushing, means in

N order to keep the optics element 120 clean of any possible accumulation of impurities on

N the surface thereof that might obscure the field of view of the instrumentation. In an embodiment, the washing means comprise a washing fluid inlet line 150 for conveying a fluid, for example water, condensate and/or air, on the external surface of the optics element 120 through a washing outlet 155. The used washing fluid ends up in the liquor in the tank and is processed in mill processes.

Fig. 3 shows an example embodiment in which the instrumentation case of the support means 42 comprises a single instrument, in the case of Fig. 3 the imaging means 110.

Accordingly, the illumination means would be comprised at an instrumentation case of a second support means 46 depicted in Fig. 2. The second support means 46 in an embodiment has an analogue structure with the first support means 42 described hereinbefore with the imaging means being replaced with illuminating means configured to illuminate the field of view of the imaging means. In an embodiment, the illuminating means comprise a suitable source of electromagnetic radiation, such as visible light or uv-light. In an example embodiment, the illuminating means comprise elements such as a light emitting diode, LED, or an array thereof.

In a further example embodiment, both the imaging means and the illuminating means are provided in the instrumentation case of the same support means with the optics element being adapted for both and/or with a separate optics element provided for the imaging means and illuminating means respectively.

In a further example embodiment, the imaging means and the illuminating means are at least in part situated outside the tank, for example the electronic elements are outside, and an optical arrangement for providing a field of view to the area to be imaged is provided in the support means.

Figs. 4A and 4B show flow charts of a method according to an example embodiment. Figs. 4A and 4b illustrate a process comprising various possible steps including some optional steps while also further steps can be included and/or some of the steps can be performed © 25 more than once.

N At step 410, the imaging is carried out with the imaging means 110, such as a digital video

S camera. Depending on the setup, either successive still images or a video seguence is 3 imaged. The field of vision of the imaging means is captured in the image frames, image

E frames here meaning either still images or frames of a video seguence. The field of vision

LO 30 and subsequently the frames comprise the area of interest comprising the liquor in the tank

S 10 and the soap overflow channel 20 as depicted in Fig. 1B.

S Further, at step 410, two frames showing the area of interest are selected for analysis from the imaged date. In an embodiment, the two frames comprise successive frames of a video sequence or two successive still images. In a further embodiment, the two frames comprise frames with a pre-selected time interval from a video sequence. In a further example embodiment, more than two frames showing the area of interest are selected for analysis, i.e. the number of frames used varies with the algorithm and the method of analysis used.

At step 420, the property of interest is determined. The property of interest is determined using image processing and/or image analysis algorithms. The method according to example embodiments is configured to determine a plurality of properties of interest. In an example embodiment, the plurality of properties of interest comprise moving mass detection, soaping velocity measurement, soaping detection and flowing liquor detection. In an example embodiment, a numerical value is determined for a property of interest, for example a soaping velocity has a value in centimetres per second. In an embodiment, the method determines all the properties. In a further embodiment, a property of interest is used in determining a further property of interest.

At step 430, a result of the determination of the property of interest is available and is for example displayed top an operator of the process on display device or the like. In an embodiment, the result is shown with continuous showing of the data from the imaging means, i.e. the operator is shown a video feed and the result of the determination of the property of interest. In a further embodiment, a history of the determinations carried out is displayed also, i.e. the operator is shown a graphical representation of the history of the property.

At 440, in a further embodiment, the result of the determination is used in controlling the process. In an example embodiment, the inflow of liquor into the tank is adjusted in accordance with the determined soaping velocity. In a further example embodiment, the inflow of liquor into the tank is reduced if flowing liquor is detected by the method.

In an example, the process is controlled by raising the surface of black liquor in the tank in en 25 — suitable steps, for example 1% at a time. Raising of the surface is controlled by controlling

S the inflow and/or outflow of the liguor from the tank, taking into consideration also the

N average time the black liguor resides in the tank. In an example, the surface of the tank is

O raised until soap separation is detected using the arrangement and method of the invention = or until the soaping velocity detected reaches a predetermined threshold value. The surface o 30 level with which the desired soap separation is achieved is in an example subsequently 2 used as a set surface level value for surface level control. 3 Fig. 4B shows a flow chart with the alternative properties of interest to be determined

N according to an example embodiment.

At step 410, the imaging and frame selection is carried out as hereinbefore described.

For each property of interest at steps 422-428, at least one region of interest, ROI, is selected from the regions of interest 1-3 depicted in Fig. 1B. The selection of the region of interest depends on the property of interest which is to be determined at said moment. In an embodiment, the soap separation monitoring method according to present invention is capable of determining all the properties of interest simultaneously, and regions of interest for calculation are selected for each determination respectively. Regions of interest 1-3 are used for overall detection of moving mass, region of interest 1 is used for soaping velocity and soaping detection and region of interest 2 is used for flowing liquor detection.

At step 422, the moving mass detection is carried out. The moving mass detection, in an embodiment comprises the following steps. In an embodiment, Flow is computed in selected regions of interest 1-3 using a suitable algorithm, for example Farnebäck's polynomial pyramid search algorithm with predefined constant parameters and/or a further algorithm selected from the group of Gunnar-Farnebäck, Lucas-Kanade, Horn-Schunck and Block-matching method .

From the result of the flow computation, a vertical direction velocity matrix is selected and the values thereof are filtered by selecting only negative vertical direction velocity values that correspond to a motion from bottom to top in Fig. 1B. Hereto it is noted, as is clear to a skilled person, that the direction of the movement in the tank is horizontal, but appears vertical in an image as schematically shown in Fig. 1B for example. In an embodiment, filtering is also used to remove possible artefacts, for example by removing velocity values smaller than a predetermined limit. Next, a binary mask is created using velocity values selected in previous filtering and areas smaller than a predetermined limit are removed from the mask. Moving mass percentage is then calculated by comparing the masked area to the area of regions of interest 1-3.

At step 424, the soaping velocity measurement is carried out. First, a mean vertical & direction, or horizontal direction in the tank, velocity inside regions of interest 1-3 is e computed using similar flow computation as for moving mass detection. The mean vertical <Q direction, or horizontal direction in the tank, velocity is then scaled to SI-units from pixels 3 using a known width of at least a part of the soap overflow channel in the frame.

I o 30 Atstep 426, the soaping detection is carried out. In an embodiment, the region of interest 1 2 is used for soaping detection. A mask is created for the region of interest 1 in the same

O manner as in moving mass detection and the percentage of mask coverage is calculated

O by comparing the mask to the area of region of interest 1. Soaping is detected by comparing the percentage of mask coverage to a predetermined threshold value. In an embodiment, — the predetermined threshold value is 20 and soaping is detected in case the created mask covers more than 20 percent of the region of interest 1.

At step 428, flowing liquor detection is carried out. In an embodiment, the region of interest 2 is used for flowing liquor detection. In an embodiment, the absolute difference between the two selected frames is calculated and this result is used as a mask. Flowing liquor is detected by comparing the percentage of mask coverage to a predetermined threshold value. In an embodiment, the predetermined threshold value is 20 and flowing liquor is detected in case the created mask covers more than 20 percent of the region of interest 2.

Steps 430 and 440 are carried out as described hereinbefore.

Fig. 5 shows a schematic block diagram of a control system according to an example embodiment of the present invention The control system comprises a control unit 500 comprising a communication interface 510; a processor 520; a user interface 530; and a memory 540.

The communication interface 510 comprises in an embodiment a wired and/or wireless communication circuitry, such as Ethernet; Wireless LAN; Bluetooth; GSM; CDMA;

WCDMA; LTE; and/or 5G circuitry. The communication interface can be integrated in the apparatus 500 or provided as a part of an adapter, card or the like, that is attachable to the apparatus 500. The communication interface 510 may support one or more different communication technologies. The control unit 500 may also or alternatively comprise more than one of the communication interfaces 510.

In this document, a processor may refer to a central processing unit (CPU); a microprocessor; a digital signal processor (DSP); a graphics processing unit; an application specific integrated circuit (ASIC); a field programmable gate array; a microcontroller; or a combination of such elements. n The user interface may comprise a circuitry for receiving input from a user of the control unit

S 25 500, e.g., via a keyboard; graphical user interface shown on the display of the control unit

K 500; speech recognition circuitry; or an accessory device; such as a headset, and for = providing output to the user via, e.g., a graphical user interface or a loudspeaker.

S

E The memory 540 comprises a work memory 542 and a persistent memory 544 configured

LO to store computer program code 546 and data 548. The memory 540 may comprise any

S 30 one or more of: a read-only memory (ROM); a programmable read-only memory (PROM);

O an erasable programmable read-only memory (EPROM); a random-access memory (RAM);

N a flash memory; a data disk; an optical storage; a magnetic storage; a smart card; a solid- state drive (SSD); or the like. The control unit 500 may comprise a plurality of the memories

540. The memory 540 may be constructed as a part of the control unit 500 or as an attachment to be inserted into a slot; port; or the like of the control unit 500 by a user or by another person or by a robot. The memory 540 may serve the sole purpose of storing data, or be constructed as a part of a control unit 500 serving other purposes, such as processing data.

A skilled person appreciates that in addition to the elements shown in Figure 5, the control unit 500 may comprise other elements, such as microphones; displays; as well as additional circuitry such as input/output (I/O) circuitry; memory chips; application-specific integrated circuits (ASIC); processing circuitry for specific purposes such as source coding/decoding circuitry; channel coding/decoding circuitry; ciphering/deciphering circuitry; and the like.

Additionally, the control unit 500 may comprise a disposable or rechargeable battery (not shown) for powering the control unit 500 if external power supply is not available.

The control unit 500 is in an embodiment a stand-alone control unit. In a further embodiment the control unit 500 is comprised in or integrated with another control arrangement, such as a mill-wide control system. In a further embodiment, the control unit 500 is situated in a cloud-based service. In a still further embodiment, the control unit is integrated with a personal computing device such as a laptop, tablet computer or a smartphone.

The control system of Fig. 5 in an embodiment further comprises the soap separation monitoring arrangement 600 according to the embodiments of the invention described hereinbefore. In an embodiment, the soap separation monitoring arrangement comprises elements not shown, such as a communication interface; a processor; a user interface; and a memory. In a still further embodiment, the functions and elements of the control unit 500 are wholly or in part integrated with the monitoring arrangement 600.

The control system of Fig. 5 in an embodiment further comprises an actuator unit 700 en 25 configured to carry out adjustments to the process based on instructions from the control

S unit 500. In an embodiment, the actuator unit 700 comprises actuators such as valves for

N controlling liguor flow. In an embodiment, the actuator unit comprises elements not shown, se such as a communication interface; a processor; a user interface; and a memory.

E In an embodiment, the monitoring arrangement 600 and actuator unit 700 are in

LO 30 communication with each other directly in addition to or instead of communicating via the

S control unit 500.

N

< The soap separation monitoring arrangement and method according to example embodiments of the invention is configured to enable the monitoring of soap separation remotely without manual visual inspection. The soap separation monitoring arrangement and method according to example embodiments of the invention is further configured to improve the soap separation process and subsequent tall oil production at a pulp mill.

Accordingly, a technical effect of example embodiment of the invention is minimizing pulping liquor overflow into the soap storage tank. A further technical effect of the example embodiments of the invention is to enable remote monitoring of soap separation. A still further technical effect of the example embodiments of the invention is to reduce chemical usage in tall oil production by improving soap separation. A still further technical effect of the example embodiments of the invention is to automate the control of soap separation. .

A still further technical effect of the example embodiments of the invention is easier — optimization of soap separation conditions at a liquor storage tank. A still further technical effect of the example embodiments of the invention is improved safety due to reduced need of manual inspection. A still further technical effect of the example embodiments of the invention is minimizing the amount of soap in black liquor due to improved soap separation, leading to less fouling of the black liquor evaporation units.

Any of the afore described methods, method steps, or combinations thereof, may be controlled or performed using hardware; software; firmware; or any combination thereof.

The software and/or hardware may be local; distributed; centralised; virtualised; or any combination thereof. Moreover, any form of computing, including computational intelligence, may be used for controlling or performing any of the afore described methods, method steps, or combinations thereof. Computational intelligence may refer to, for example, any of artificial intelligence; neural networks; fuzzy logics, machine learning; genetic algorithms; evolutionary computation; or any combination thereof.

Various embodiments have been presented. It should be appreciated that in this document, words comprise; include; and contain are each used as open-ended expressions with no n 25 intended exclusivity.

N

N The foregoing description has provided by way of non-limiting examples of particular

S implementations and embodiments a full and informative description of the best mode 2 presently contemplated by the inventors for carrying out the invention. It is however clear to = a person skilled in the art that the invention is not restricted to details of the embodiments > 30 presented in the foregoing, but that it can be implemented in other embodiments using

S eguivalent means or in different combinations of embodiments without deviating from the

N characteristics of the invention.

N Furthermore, some of the features of the afore-disclosed example embodiments may be used to advantage without the corresponding use of other features. As such, the foregoing description shall be considered as merely illustrative of the principles of the present invention, and not in limitation thereof. Hence, the scope of the invention is only restricted by the appended patent claims.

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Claims (15)

1. A soap separation monitoring arrangement, comprising imaging means configured to image an area of interest of a surface of a liquor storage tank; illuminating means configured to illuminate the area of interest; at least one support means supporting at an end thereof an instrumentation case and configured to be releasably installed at an installation duct in a cover of a manhole on top of the liquor storage tank so that the end supporting the instrumentation case is inside the tank, wherein the imaging means and the illuminating means are positioned inside the instrumentation case of the at least one support means; wherein the instrumentation case comprises an optics element configured to provide the imaging means and illuminating means with a field of view to the area of interest; the vertical position and angle with respect to the support means of the instrumentation case is adjustable for adjusting the field of view of the imaging means; and wherein the imaging means are configured to image at least two image frames of the area of interest, wherein the area of interest comprises at least a part of the liquor storage tank and at least a part of a soap overflow channel.

2. The arrangement of claim 1, wherein the at least one support means comprises two support means comprising an instrumentation case, wherein first and second support means are spatially separated and the imaging means are positioned inside the instrumentation case of the first support means and the illuminating means are positioned inside the instrumentation case of the second support means.

3. The arrangement of claim 1 or 2, further comprising cooling means for cooling the n 25 instrumentation case by conveying cooling gas into the instrumentation case. N O

N 4. The arrangement of any of the claims 1 to 3, further comprising washing means for S keeping the optics element clean by conveying washing fluid on the external surface of the 2 optics element. I

= 5. The arrangement of any of the claims 1 to 4, wherein the imaging means comprise a 2 30 digital video camera. LO

O 6. The arrangement of any of the claims 1 to 5, wherein the illuminating means comprise O N a light emitting diode or an array of light emitting diodes.

7. A soap separation monitoring method, comprising imaging an area of interest on the surface of a liquor storage tank by imaging means, wherein the area of interest comprises at least a part of the liquor storage tank and at least a part of a soap overflow channel; selecting two image frames showing the area of interest, wherein the selected frames have atime interval; and determining a property of interest based on the selected frames, wherein the property of interest is selected from the group of moving mass detection, soaping velocity measurement, soaping detection and flowing liquor detection.

8. The method of claim 7, further comprising controlling the soap separation process — based on the result of determining the property of interest.

9. The method of claim 7 or 8, further comprising illuminating the area of interest with illuminating means.

10. The method of claim any of claims claim 7 to 9, wherein determining the property of interest first comprises selecting a region of interest from the selected frames depending on — the property of interest to be determined.

11. Themethodofany of claims claim 7 to 10, wherein determining the property of interest comprises determining using image processing and/or image analysis algorithms.

12. A control system for soap separation comprising: the arrangement of any of the claims 1 to 6; a control unit, comprising at least one memory comprising computer executable program code, and at least one processor configured cause the control system to perform, when executing the program code, the method of any one of claims 7 to 11.

13. Thecontrol system of claim 8, further comprising an actuator unit; wherein the at least 2 one processor is configured cause the control system to perform, when executing the & 25 program code, the method of any one of claims 7 to 11. K S

14. A computer program comprising computer executable program code which when O © executed by the at least one processor of the control system of claim 12 causes the control E system to at least to perform the method of any one of claims 7 to 11. 2

15. A non-transitory memory medium, comprising the computer program of claim 14. 3 N O N