WO2016037197A1

WO2016037197A1 - An apparatus for cleaning an evaporator while in operation, and an associated method

Info

Publication number: WO2016037197A1
Application number: PCT/ZA2015/050008
Authority: WO
Inventors: Ryno VAN ZYL
Original assignee: Van Zyl Ryno
Priority date: 2014-09-04
Filing date: 2015-09-03
Publication date: 2016-03-10
Also published as: ZA201701525B

Abstract

An apparatus is for (100) for cleaning evaporators (110) having a plurality of aligned evaporator tubes (114) with their upper ends being positioned generally in a plane at a top of the evaporator (110). The apparatus (100) includes a nozzle (161) operable to direct fluid under pressure and a fluid supply connected to the nozzle (161). The apparatus (100) has a displacement arrangement (150, 151, 122, 120) operable to displace the nozzle (161) in at least two dimensions. The apparatus (100) has a control module (200) operable to direct the displacement arrangement (150, 151, 122, 120) to displace the nozzle (161) sequentially to be aligned with each of the evaporator tubes 114) and actuate the nozzle (114) to direct a stream of the fluid into the aligned evaporator tube (114), thereby to clean the tube (114) while it is still in operation.

Description

An apparatus for cleaning an evaporator while in operation, and an associated method

FIELD OF INVENTION

The invention relates generally to the cleaning of evaporators having a plurality of aligned evaporator tubes, and more specifically to an apparatus for cleaning such an evaporator while in operation, and to an associated method.

BACKGROUND OF INVENTION

An evaporator is an apparatus used to facilitate and accelerate the transition of a substance from liquid to vapour (hitp://en.wik:pedla.orq/wiki/EvapOiaior, accessed 14 July 2014). The Applicant is aware of conventional evaporators having an outer cylindrical housing and a plurality of upright parallel evaporator tubes housed therein. One application of such evaporators is in sugar cane processing, used as a sugar cane juice evaporator. This invention relates specifically to tube evaporators having a plurality of aligned evaporator tubes, but its application is not necessarily limited to sugar cane processing.

A problem that the Applicant has observed with such evaporators is the cleaning thereof, and specifically the cleaning of the individual evaporator tubes. Scale or other contaminants are deposited on inner walls of the evaporator tubes and current cleaning methodologies of which the Applicant is aware include chemical cleaning with the aid of a caustic agent and/or mechanical cleaning done manually by labourers. Either way, the operation of the evaporator must be suspended to permit such cleaning. These stoppages necessitated by cleaning result in production downtime and financial loss to a facility using the evaporator. On the other hand, lack of cleaning results in reduced efficiency, or complete failure, of the evaporator. The Applicant desires an apparatus which overcomes these drawbacks. More specifically, the Applicant desires an apparatus which is capable of cleaning such evaporators without suspending their operation.

SUMMARY OF INVENTION

Accordingly, the invention provides an apparatus for cleaning evaporators having a plurality of aligned evaporator tubes with their upper ends being positioned generally in a plane at a top of the evaporator, the apparatus including: a nozzle operable to direct fluid under pressure; a fluid supply connected to the nozzle; a displacement arrangement operable to displace the nozzle in at least two dimensions; and a control module operable to: direct the displacement arrangement to displace the nozzle sequentially to be aligned with each of the evaporator tubes; and actuate the nozzle to direct a stream of the fluid into the aligned evaporator tube, thereby to clean the tube while it is still in operation.

The fluid may be a liquid. The liquid may be water. The liquid may be the substance being evaporated, e.g., a clear juice mixture. The fluid supply may thus include a liquid pump, e.g., a high pressure water pump. The fluid supply may include a fluid conduit (e.g., a water hose) to connect the liquid pump to the nozzle.

The displacement arrangement may include an arm to which the nozzle is mounted. The arm may be displaceable and/or the nozzle may be displaceably mounted to the arm. The displacement arrangement may include a nozzle carrier which carries the nozzle and which is displaceably mounted to the arm. For example, the arm may be rotatable or swivelable and the nozzle carrier may be operable to travel along the arm, the apparatus thus using a polar coordinate system. The arm may thus define an axis of rotation about which it rotates. The axis of rotation may be co-axial with a central axis of the evaporator. The arm may include a wheel or roller at its free/distal end to support the arm. The wheel or roller may be aligned with, and displaceable along, a top edge of a housing or an outer wall of the evaporator.

Instead, the arm may be transversely linearly displaceable and the nozzle may be operable to travel along the arm, the apparatus thus using an orthogonal/Cartesian coordinate system. Other embodiments may be practicable too. The specific displacement arrangement and coordinate system may be influenced by the configuration of the evaporator to which the apparatus is applied.

The nozzle may be displaceable vertically relative to, or inside of, an evaporator tube. Accordingly, the nozzle may be extendable/retractable within an evaporator tube. The nozzle may be provided at the free end of the conduit. The displacement arrangement may include a reel about which the conduit can be wound, thereby to unwind and wind the conduit about the reel, thereby to extend and retract the nozzle. A vertical position of the nozzle may comprise a third coordinate in a three- dimensional coordinate system. In a different embodiment, the nozzle may be upwardly and downwardly displaceable lance-fashion (i.e., without use of a reel).

The displacement arrangement may include one or more electrical motors, e.g., servomotors or stepper motors, to realise mechanical displacement of the nozzle. The motors may be responsive to a control signal from the control module.

The apparatus may include a positioning arrangement to determine or track the position of the nozzle. The positioning arrangement may include at least one encoder, e.g., a pulse encoder. The positioning arrangement may include three pulse encoders, one for each component of a three-component coordinate system (e.g., one pulse encoder to track the angular position, another to track the radial position, and a third to track the vertical position). The or each pulse encoder may be in communication with the control module. The apparatus may include a predefined or predefinable tube map. The apparatus may include a memory module on which the tube map is stored. The control module may be in communication with the memory module thereby to access the tube map and to direct the nozzle in accordance with the tube map.

The tube map may be predefined by an operator (e.g., using a computerised drawing or modelling software tool) and updated or loaded to the storage module. Instead, or in addition, the tube map could be generated by a moving unit (which could be the nozzle) traversing the top of the evaporator and sensing the positions of the plural evaporator tubes.

Instead, the tube map may not be predefined but the apparatus may include sensors (e.g., optical sensors) to determine a layout of the tubes and the position of the nozzle in real time.

The invention extends to an evaporator assembly including an evaporator with the apparatus, as defined above, installed therein.

The invention extends further to a method of cleaning evaporators having a plurality of aligned evaporator tubes with their upper ends being positioned generally in a plane at a top of the evaporator, the method including: displacing, by a displacement arrangement, a nozzle operable to direct pressurised fluid from a fluid supply, the displacement of the nozzle being directed by a control module to align the nozzle sequentially with each of the evaporator tubes; and actuating the nozzle thereby to direct a stream of the pressurised fluid into the aligned evaporator tube, thereby to clean the tube while it is still in operation.

The method may be entirely automated, not requiring human or operator intervention. The method may include extending and retracting the nozzle within each evaporator tube.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be further described, by way of example, with reference to the accompanying diagrammatic drawings.

In the drawings:

FIG. 1 shows a side view of an evaporator and an apparatus, in accordance with the invention, for cleaning the evaporator;

FIG. 2 shows another side view of the evaporator and the apparatus of FIG. 1 ;

FIG. 3 shows a top plan view of the evaporator and the apparatus of FIG. 1 ;

FIG. 4 shows a three-dimensional view of the evaporator and the apparatus of

FIG. 1 ;

FIG. 5 shows a side view of a nozzle carrier of the apparatus of FIG. 1 ;

FIG. 6 shows a three-dimensional view of the nozzle carrier of FIG. 5;

FIG. 7 shows a partial sectional view of the evaporator and the apparatus of FIG.

1 ; and

FIG. 8 shows a schematic view of functional components and modules of the apparatus of FIG. 1 .

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENT

The following description of the invention is provided as an enabling teaching of the invention. Those skilled in the relevant art will recognise that many changes can be made to the embodiment described, while still attaining the beneficial results of the present invention. It will also be apparent that some of the desired benefits of the present invention can be attained by selecting some of the features of the present invention without utilising other features. Accordingly, those skilled in the art will recognise that modifications and adaptations to the present invention are possible and can even be desirable in certain circumstances, and are a part of the present invention. Thus, the following description is provided as illustrative of the principles of the present invention and not a limitation thereof.

FIGS 1 -2 show an evaporator 1 10 retro-fitted with an apparatus 100 in accordance with the invention for cleaning the evaporator 1 10 while in operation. The evaporator 100 has (in conventional fashion) an elongate, cylindrical enclosure or housing 1 12 and defines a central upright axis 1 10a.

FIGS 3-7 show the apparatus 100 in more detail. The apparatus 100 has a nozzle carrier 120 which is linearly displaceably mounted to an elongate arm 122. The arm 122 is swivelably mounted to the evaporator 1 10 to swivel about the central axis 1 10a. A distal end of the arm 122 has a wheel or roller 150 rotatably mounted thereto, to rest on a circumferentially extending top edge 1 12a of the housing 1 12. The wheel 150 supports the arm 122 at its distal end.

The wheel 150 is driven by a wheel servomotor 151 mounted on the distal end of the arm 122. The wheel servomotor 151 is operable to drive the wheel 150 thereby to rotate the arm 122 angularly about the central axis 1 12a. The servomotor is a precisely controllable motor to achieve relatively precise angular displacement of the arm 122.

The nozzle carrier 120 has a pair of opposed sidewalls 124 which are spaced a short distance apart and which define therebetween a space to accommodate a reel 160 which is mounted to rotate about a shaft 164 extending between the sidewalls 124. A fluid conduit in the form of a water hose 162 can be coiled around the reel 160. A portion 162a of the hose 162 depends downwardly from the nozzle carrier 120 and terminates in a nozzle 161 . The nozzle carrier 120 has a guide arrangement 162b to guide the coiling and uncoiling of the hose 162 thereby to extend and retract the nozzle 161 . A reel servomotor 166 is operable to rotate the reel 160 about a reel axis 1 66a, thereby to coil or uncoil the hose 162 from the reel 1 60 as the nozzle carrier 1 20 is displaced inwardly or outwardly along the arm 1 22.

The nozzle carrier 120 includes a U-shaped outer wall 1 25 (as most clearly seen in FIGS 5-6) which encloses the reel 160 and serves to protect components housed within the nozzle carrier 1 20.

The apparatus 1 00 has a turntable mechanism 1 28 beneath the arm 1 22. The turntable mechanism 1 28 serves to support the remainder of the components and to permit pivoting of the apparatus 1 00 about the central axis 1 1 2a.

The arm 122 has a pair of toothed racks 152 extending longitudinally along the length of the arm 1 22. The nozzle carrier 1 20 has corresponding drive pinions 1 26 in register with the racks 1 52, thereby to permit the nozzle carrier 1 20 to be displaced linearly back or forth along the arm 1 22. The pinions 1 26 are driven by means of a dedicated carrier servomotor arranged between the sidewalls 1 24. By driving the nozzle carrier 120 along the arm 1 22, radial displacement of the nozzle 1 61 is achieved.

The wheel 1 50, wheel servomotor 1 51 , and the arm 1 22; the carrier servomotor and the nozzle carrier 1 20; and the reel 1 60 and the reel servomotor 1 66 thus constitute a displacement arrangement for displacing the nozzle 1 61 in three dimensions.

It will thus be appreciated by one skilled in the art that the apparatus 100 employs a three-dimensional polar/linear coordinate system (a, r, /). An angular component (a) is generated by the swivelling of the arm 1 22, a radial component (r) is generated by the travelling of the nozzle carrier 1 20 along the arm 1 22, and a linear component (/) is generated by the vertical displacement of the nozzle 1 61 due to the winding or unwinding of the reel 160. Almost any point (a, r) on the surface of the evaporator 1 1 0 can be reached by the nozzle 161 by control of the angular displacement (a) of the arm 1 22 relative to the housing 1 1 2 on the one hand, and the radial displacement (r) of the nozzle carrier 1 20 along the arm 1 22 on the other hand. Then, a depth (/) down the evaporator tube is realised. The turntable 1 28 may even have holes formed (e.g., drilled) in it corresponding to locations where evaporator tubes 1 14 may be situated, thereby not to interfere with the operation of the nozzle 1 61 .

FIG. 8 shows a schematic view of the apparatus 1 00 including some of the functional components. The wheel servomotor 1 51 is operable to rotate the wheel 1 50, thereby to swivel the arm 1 22 around the top of the evaporator 1 1 0. The wheel servomotor 202 includes an integrated pulse encoder (a) 204 to determine or keep track of the angular inclination (a) of the turntable 128, thereby to determine the angular coordinate (a) of the polar/linear coordinate system (a, r, f) representative of the position of the nozzle 1 61 .

Similarly, the carrier servomotor 206 is operable to actuate and rotate the pinions 1 26, thereby to drive the nozzle carrier 1 20 in either direction along the arm 1 22. The carrier servomotor 206 has an integrated pulse encoder (r) 208 to determine, or keep track of, a distance which the nozzle carrier 120 has travelled along the arm 1 22, thereby to determine the radial coordinate (r) of the polar/linear coordinate system (a, r, f) representative of the position of the nozzle 161 .

Also, the reel servomotor 1 66 is operable to rotate the reel 1 60 thereby to wind and unwind the hose 162 causing the nozzle 161 to retract and extend, respectively. The reel servomotor 1 66 has an integrated pulse encoder (/) 209 to keep track of a length or distance which the nozzle 1 61 has been extended from the nozzle carrier 1 20, thereby to determine the linear coordinate (/) of the polar/linear coordinate system (a, r, I) representative of the position of the nozzle 161 .

Each servomotor 1 66, 202, 206 is controlled by a control module 200. Thus, the control module 200 is operable automatically to direct the displacement arrangement (1 50, 1 51 , 1 22; 1 20, 206; 1 60, 1 66) to displace the nozzle 161 . The control module 200 is communicatively coupled to a memory module 21 0 which has stored thereon a tube map 212 which comprises an indication of the location of each evaporator tube 1 14. The control module 200 is operable to read the tube map 212 and then to actuate the servomotors 202, 206 to displace the wheel 150 and nozzle carrier 120 - and hence the nozzle 161 - to be aligned with one of the evaporator tubes 1 14.

The tube map 212 may be defined or populated in a few different ways. In one embodiment, the layout of evaporator tubes 1 14 is mapped on a computer-aided drawing (CAD) program and the mapping is converted to the electronic tube map 212 and uploaded to the memory module. In another embodiment, the tube map 212 can be learned or generated by the apparatus. This can be done (in a manual example) by an operator moving the nozzle into alignment with each evaporator tube 1 14 and instructing the control module 200 to memorise each location, the control module 200 then generating the tube map 212 of all the locations. Instead, it could be done (in a more automated example), if a sensor (e.g., optical sensor) is coupled to the nozzle. Then, instead of an operator instructing the control module 200 that the nozzle is aligned with an evaporator tube 1 14, the control module 200 could sense it automatically.

Thereafter, the control module 200 is operable to unwind the reel 160 while simultaneously actuating a water pump (not illustrated) thereby to inject a stream of pressurised water from the nozzle 161 as it extends downwardly into and/or retracts outwardly out of each evaporator tube 1 14. Thus, the entire length of the evaporator tube 1 14 can be cleaned, while still in operation. After this has been done and the evaporator tube 1 14 has been cleaned, the control module 200 moves the nozzle to the next evaporator tube 1 14 in the sequence as defined by the tube map 212. All the while, the evaporator 1 10 remains in operation.

The control module 200 may be integrated with the remainder of the apparatus 100, e.g., inside the turntable mechanism 128. In a different embodiment, the control module 200 may be remote from the remainder of the apparatus 100, e.g., housed in a remote client terminal, and connected to the servomotors 202, 206 by means of a communication link (e.g., wired or wireless). The Applicant believes that the invention as exemplified is advantageous in that it not only provides effective cleaning of contaminants (e.g., scaling deposits) of the evaporator tubes 1 14, but in that they can be cleaned while the evaporator 1 10 remains operative. By using pressurised water, the substance being evaporated is not contaminated, as would the case be if a caustic chemical cleaning agent was used. Other drawbacks associated with chemical cleaning, which are presently alleviated or overcome, include: caustic chemical products are expensive; caustic chemical products are not highly effective against heavy scaling; and a chemical plant may be required to prepare the caustic chemical products.

The apparatus 100 is largely automated, thus reducing labour requirements significantly. It overcomes drawbacks associated with manual, mechanical cleaning, such as: labour intensivity; the mechanical cleaning devices have moving parts that can cause bodily harm to the labourer; and the mechanical devices can damage the evaporator tubes 1 14 themselves.

The apparatus 100 requires minimal maintenance and is modular so that if a component fails, it can fairly easily be removed and replaced without the removal or replacement of the remaining components of the apparatus 100.

The apparatus 100 can be adapted to various kinds of evaporators, such as rising and falling film evaporators (with longer evaporator tubes) and Roberts evaporator vessels (with shorter tubes).

Claims

1. An apparatus for cleaning evaporators having a plurality of aligned evaporator tubes with their upper ends being positioned generally in a plane at a top of the evaporator, the apparatus including: a nozzle operable to direct fluid under pressure; a fluid supply connected to the nozzle; a displacement arrangement operable to displace the nozzle in at least two dimensions; and a control module operable to: direct the displacement arrangement to displace the nozzle sequentially to be aligned with each of the evaporator tubes; and actuate the nozzle to direct a stream of the fluid into the aligned evaporator tube, thereby to clean the tube while it is still in operation.

2. The apparatus as claimed in claim 1 , in which: the fluid is water or clear juice; and the fluid supply includes a liquid pump.

3. The apparatus as claimed in any one of claims 1 -2, in which the displacement arrangement includes an arm to which the nozzle is mounted.

4. The apparatus as claimed in claim 3, in which the arm is displaceable.

5. The apparatus as claimed in any one of claim 3-4, in which the displacement arrangement includes a nozzle carrier which carries the nozzle and which is displaceably mounted to the arm. The apparatus as claimed in claim 5, in which: the arm is rotatable or swivelable; and the nozzle carrier is operable to travel along the arm.

The apparatus as claimed in claim 6: in which the arm defines an axis of rotation about which it rotates which is co-axial with a central axis of the evaporator; and which includes a wheel or roller at its distal end to support the arm, the wheel or roller being aligned with, and displaceable along, a top edge of a housing or an outer wall of the evaporator.

The apparatus as claimed in any one of claims 1 -7, in which the nozzle may be displaceable vertically relative to, and inside of, at least one of the evaporator tubes.

The apparatus as claimed in claim 8, in which the nozzle is extendable/retractable within at least one of the evaporator tubes.

0. The apparatus as claimed in claim 9, in which: the fluid supply includes a fluid conduit configured to connect the nozzle to the fluid supply; and the displacement arrangement includes a reel about which the conduit can be wound, thereby to unwind and wind the conduit about the reel, thereby to extend and retract the nozzle.

1. The apparatus as claimed in any one of claims 1 -10, in which the displacement arrangement includes at least one electrical motor, to realise mechanical displacement of the nozzle, the motor being responsive to a control signal from the control module.

2. The apparatus as claimed in any one of claims 1 -1 1 , which includes a positioning arrangement to determine or track the position of the nozzle.

3. The apparatus as claimed in any one of claims 1 -12, which includes: a memory module; and a predefined or predefinable tube map stored on the memory module.

4. The apparatus as claimed in claim 13, in which the control module is in communication with the memory module thereby to access the tube map and to direct the nozzle in accordance with the tube map.

5. An evaporator assembly including an evaporator with the apparatus as claimed in any one of claims 1 -14.

6. A method of cleaning evaporators having a plurality of aligned evaporator tubes with their upper ends being positioned generally in a plane at a top of the evaporator, the method including: displacing, by a displacement arrangement, a nozzle operable to direct fluid under pressure from a fluid supply, the displacement of the nozzle being directed by a control module to align the nozzle sequentially with each of the evaporator tubes; and actuating the nozzle thereby to direct a stream of the fluid into the aligned evaporator tube, thereby to clean the tube while it is still in operation.

7. The method as claimed in claim 16, which includes extending and retracting the nozzle within each evaporator tube.