GB2033583A

GB2033583A - Apparatus for electrode cleaning

Info

Publication number: GB2033583A
Application number: GB7843210A
Authority: GB
Original assignee: COMMW SMELTING Ltd
Current assignee: COMMW SMELTING Ltd
Priority date: 1978-11-03
Filing date: 1978-11-03
Publication date: 1980-05-21

Abstract

Apparatus for cleaning an electrode, especially a pH-measuring electrode E, includes means A, B for mechanically removing the electrode from a process stream and positioning it above a container F of cleaning fluid, for dipping it into a cleaning fluid and removing it therefrom, followed by return to the process stream. Preferably the sequence of operations is controlled by a timer and is initiated at pre-set time intervals. Preferably means A, B are hydraulically or pneumatically operated piston/cylinder combination. <IMAGE>

Description

SPECIFICATION Improvements in or relating to electrode-cleaning apparatus This invention relates to electrode-cleaning apparatus of the type which requires the dipping of an electrode into a cleaning solution at intervals in order to remove adherent deposits.

It is known that when using pH electrodes with certain types of solutions, especially those in which acid constituents are neutralised with bases, adherent deposits can build up on the outer surface of the electrode and impair its efficiency, making it slow to respond to pH changes and inaccurate. Some deposits respond to well-known automatic methods of removal such as mechanical wiping or ultrasonic vibration. However certain deposits, especially those produced by neturalisation of sulphuric acid with lime, are not amenable to this approach and in these cases the use of a cleaning solution e.g. an acid wash has to be employed. If the cleaning requirement is a frequent one e.g. more than twice a day it is desirable to put the cleaning cycle on an automatic basis. The present invention sets out to provide an apparatus suitable for achieving this objective.

Accordingly this invention provides apparatus for cleaning an electrode, by dipping it into a container of cleaning solution, including the following essential features; (a) means for moving the electrode reciprocally, in a longitudinal direction, between operative and retracted positions (b) means for reciprocally displacing the electrode or the container laterally, while the electrode is in its retracted position, so that the electrode is above the container.

(c) means for limiting the longitudinal move ment of the electrode when positioned above the container of cleaning solution, (d) means for initiating the movement of the electrode from its operative to its retracted position, and (e) means for controlling a retraction/lateral displacement/reverse displacement/return to operative position sequence of movements of the electrode and/or container.

Preferably means (a) and (b) in the form of hydraulically - or pneumatically-operated piston/ cylinder combinations.

Means (c) is normally a limit-switch.

Means (d) may be a manuaily-operated switch or a switch operated by a timer so that it is actuated at pre-determined time intervals.

Means (e) may be a timer e.g. a cam-actuated timer which controls the sequence of retraction/ displacement/reverse displacement and return to the operative position.

Thus the apparatus according to this invention provides for the following sequence of operations.

1. Removal of the electrode from a process stream in which it is normally immersed.

2. Sideways displacement of the electrode or of the cleaning solution container.

3. Limited longitudinal movement of the displaced electrode to cause it to dip into a cleaning solution.

4. Removal of electrode from the cleaning solution.

5. Reverse sideways displacement of electrode or container.

6. Return of electrode to the process stream.

Preferably a limit switch is provided to ensure that the electrode or the container has returned from its laterally-displaced position before the electrode is returned to the process stream.

The invention will be further described with reference to the accompanying drawings in which Figure 1A shows a pH electrode in its operative measuring position and Figure 18 shows the electrode retracted and its wash position. Figure 2 is a sehematic block diagram of a control unit for the control of a sequence of operations as set out in 1-6 above.

With reference to Figure 1A, a pH electrode (E) is shown in its vertical operative position in which it dips into a process stream (not shown) to measure the pH of the stream. On initiation of the cleaning cycle by actuation of a switch, either manually or by timer, the pneumatic cylinder A is actuated causing the piston (P) to rise taking the electrode (E) with it and raising this out of the process stream. When the electrode (E) is in its fully-retracted position, secondary pneumatic cylinder B is actuated causing electrode (E) to be laterally displaced. As shown in Figure 18 main cylinder (A) has air released from it causing the electrode (E) to be lowered until the limit switch (C) is actuated at which stage tip of electrode (E) is then immersed in cleaning solution held in container (F).This is kept in the cleaning solution for a fixed period (which may be automatically timed) and the reverse sequence of operations is then put into effect i.e. removal of electrode from cleaning solution, return to a vertical position and lowering into the process stream provided that the limit switch (D) has been actuated.

With reference to Figure 2, this shows schematically a timer T1 for initiating cleaning cycles at fixed time intervals, a timer T2 which controls the cleaning cycle including a time of immersion of the electrode in the cleaning solution, limit switch C (for limiting longitudinal movement when electrode is laterally displaced) and limit switch D (for ensuring the electrode is vertical for return into process stream) and solenoid valves A and B respectively in order to actuate raising/lowering and sideways-displacement movements of the electrode.

During the cleaning cycle, the measured pH value to the pH recorder or controller is frozen at the last true measured value of the process stream.

Various modifications may be made within the scope of the invention. Thus it may be more convenient to move the cleaning liquid container laterally, rather than the electrode and if this is done the switch D will be actuated by the return to its original position of the container.

1. Apparatus for cleaning an electrode, by dipping it into a container of cleaning solution com

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in or relating to electrode-cleaning apparatus This invention relates to electrode-cleaning apparatus of the type which requires the dipping of an electrode into a cleaning solution at intervals in order to remove adherent deposits. It is known that when using pH electrodes with certain types of solutions, especially those in which acid constituents are neutralised with bases, adherent deposits can build up on the outer surface of the electrode and impair its efficiency, making it slow to respond to pH changes and inaccurate. Some deposits respond to well-known automatic methods of removal such as mechanical wiping or ultrasonic vibration. However certain deposits, especially those produced by neturalisation of sulphuric acid with lime, are not amenable to this approach and in these cases the use of a cleaning solution e.g. an acid wash has to be employed. If the cleaning requirement is a frequent one e.g. more than twice a day it is desirable to put the cleaning cycle on an automatic basis. The present invention sets out to provide an apparatus suitable for achieving this objective. Accordingly this invention provides apparatus for cleaning an electrode, by dipping it into a container of cleaning solution, including the following essential features; (a) means for moving the electrode reciprocally, in a longitudinal direction, between operative and retracted positions (b) means for reciprocally displacing the electrode or the container laterally, while the electrode is in its retracted position, so that the electrode is above the container. (c) means for limiting the longitudinal move ment of the electrode when positioned above the container of cleaning solution, (d) means for initiating the movement of the electrode from its operative to its retracted position, and (e) means for controlling a retraction/lateral displacement/reverse displacement/return to operative position sequence of movements of the electrode and/or container. Preferably means (a) and (b) in the form of hydraulically - or pneumatically-operated piston/ cylinder combinations. Means (c) is normally a limit-switch. Means (d) may be a manuaily-operated switch or a switch operated by a timer so that it is actuated at pre-determined time intervals. Means (e) may be a timer e.g. a cam-actuated timer which controls the sequence of retraction/ displacement/reverse displacement and return to the operative position. Thus the apparatus according to this invention provides for the following sequence of operations. 1. Removal of the electrode from a process stream in which it is normally immersed. 2. Sideways displacement of the electrode or of the cleaning solution container. 3. Limited longitudinal movement of the displaced electrode to cause it to dip into a cleaning solution. 4. Removal of electrode from the cleaning solution. 5. Reverse sideways displacement of electrode or container. 6. Return of electrode to the process stream. Preferably a limit switch is provided to ensure that the electrode or the container has returned from its laterally-displaced position before the electrode is returned to the process stream. The invention will be further described with reference to the accompanying drawings in which Figure 1A shows a pH electrode in its operative measuring position and Figure 18 shows the electrode retracted and its wash position. Figure 2 is a sehematic block diagram of a control unit for the control of a sequence of operations as set out in 1-6 above. With reference to Figure 1A, a pH electrode (E) is shown in its vertical operative position in which it dips into a process stream (not shown) to measure the pH of the stream. On initiation of the cleaning cycle by actuation of a switch, either manually or by timer, the pneumatic cylinder A is actuated causing the piston (P) to rise taking the electrode (E) with it and raising this out of the process stream. When the electrode (E) is in its fully-retracted position, secondary pneumatic cylinder B is actuated causing electrode (E) to be laterally displaced. As shown in Figure 18 main cylinder (A) has air released from it causing the electrode (E) to be lowered until the limit switch (C) is actuated at which stage tip of electrode (E) is then immersed in cleaning solution held in container (F).This is kept in the cleaning solution for a fixed period (which may be automatically timed) and the reverse sequence of operations is then put into effect i.e. removal of electrode from cleaning solution, return to a vertical position and lowering into the process stream provided that the limit switch (D) has been actuated. With reference to Figure 2, this shows schematically a timer T1 for initiating cleaning cycles at fixed time intervals, a timer T2 which controls the cleaning cycle including a time of immersion of the electrode in the cleaning solution, limit switch C (for limiting longitudinal movement when electrode is laterally displaced) and limit switch D (for ensuring the electrode is vertical for return into process stream) and solenoid valves A and B respectively in order to actuate raising/lowering and sideways-displacement movements of the electrode. During the cleaning cycle, the measured pH value to the pH recorder or controller is frozen at the last true measured value of the process stream. Various modifications may be made within the scope of the invention. Thus it may be more convenient to move the cleaning liquid container laterally, rather than the electrode and if this is done the switch D will be actuated by the return to its original position of the container. CLAIMS

1. Apparatus for cleaning an electrode, by dipping it into a container of cleaning solution com prising; (a) means for moving the electrode reciprocally, in a longitudinal direction, between operative and retracted positions, (b) means for reciprocally displacing the electrode or the container laterally, while the electrode is in the retracted position, so that the electrode is positioned above the container, (c) means for limiting the longitudinal movement of the electrode when positioned above the container of cleaning solution, (d) means for initiating movement of the electrode from its operative to its retracted position and vice-versa, and (e) means for controlling a retraction/lateral displacement/reverse displacemenfreturn to operative position sequence of movements for the electrode and/or container.

2. Apparatus a claimed in claim 1, wherein the displacement means (a) and (b) are in the form of hydraulically - or pneumatically-operated piston/ cylinder combinations.

3. Apparatus as claimed in claim 1 in which means (c) is a limit switch.

4. Apparatus as claimed in claim 1, wherein means (d) is a switch operated by a timer, so that the switch is actuated at pre-determined time intervals.

5. Apparatus as claimed in claim 1 wherein the means (e) is a timer which controls the specified sequence.

6. Apparatus for cleaning an electrode, normally immersed in a process stream, substantially as hereinbefore described with reference to figures 1A, 1 B and 2 of the accompanying drawings.

6. Apparatus as claimed in claim 1, which further comprises a second limit-switch which is actuated when the electrode or container are returned from their laterally-displaced positions.

7. Apparatus for cleaning an electrode, substantially as herein described with reference to figures 1A, 1B and 2.

New claims or amendments to claims filed on 13 Fez 1980 Superseded claims 1 to 7 New or amended claims:

1. Apparatus for cleaning an electrode, normally immersed in a process stream, by dipping it into a container of cleaning solution, comprising; (a) means for moving the electrode reciprocally in a longitudinal direction, between operative and retracted positions, (b) means for reciprocally displacing the electrode, or the container, laterally, while the electrode is in the retracted position, so that the electrode is positioned above the container, (c) a limit switch for limiting the longitudinal movement of the electrode when it is positioned above the container of cleaning solution, (d) means for initiating movement of the electrode from its operative to its retracted position and vice versa, and (e) means for controlling a retraction/lateral displacement/reverse displacement/return to operative position sequence of movements for the electrode and/or container.

2. Apparatus as claimed in claim 1, wherein means (a) and (b) are in the form of hydraulically - or pneumatically-operated piston/cylinder combinations.

3. Apparatus as claimed in claim 1, wherein (d) is a timer actuated switch, so that the switch is actuated at predetermined time intervals.

4. Apparatus as claimed in claim 1 wherein means (e) is a timer which controls the specified sequence.

5. Apparatus as claimed in claim 1, which further inciudes a second limit switch which is actuated when the electrode, or container, are returned from their laterally-displaced positions.