CA1212825A - Apparatus for slaking lime - Google Patents
Apparatus for slaking limeInfo
- Publication number
- CA1212825A CA1212825A CA000437049A CA437049A CA1212825A CA 1212825 A CA1212825 A CA 1212825A CA 000437049 A CA000437049 A CA 000437049A CA 437049 A CA437049 A CA 437049A CA 1212825 A CA1212825 A CA 1212825A
- Authority
- CA
- Canada
- Prior art keywords
- tank
- lime
- slaking
- milk
- responsive
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2/00—Lime, magnesia or dolomite
- C04B2/02—Lime
- C04B2/04—Slaking
- C04B2/08—Devices therefor
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Control Of Non-Electrical Variables (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
An apparatus for slaking lime is disclosed. The apparatus comprises a slaking tank, a low-level liquid sensor mounted in the slaking tank, an electromagnetic valve responsive to the low level liquid sensor for allowing diluting water to flow into the slaking tank up to a predetermined level, feeder means for feeding quick-lime into the slaking tank at a constant rate, relay means responsive to closure of such electromagnetic valve when the level of diluting water has reached such pre-determined level to energize the quicklime feeder, a temperature sensor mounted in the slaking tank for measuring the temperature of the milk of lime formed in the tank as quicklime is fed into the tank, a thermostatic valve responsive to the temperature sensor for adding water into the tank in quantities such as to maintain the temperature of the milk of lime in the tank, as it is formed, at a desired value, and a high level liquid sensor mounted in the slaking tank for stopping the quick-lime feeder means when the maximum level of milk of lime in the tank is reached.
An apparatus for slaking lime is disclosed. The apparatus comprises a slaking tank, a low-level liquid sensor mounted in the slaking tank, an electromagnetic valve responsive to the low level liquid sensor for allowing diluting water to flow into the slaking tank up to a predetermined level, feeder means for feeding quick-lime into the slaking tank at a constant rate, relay means responsive to closure of such electromagnetic valve when the level of diluting water has reached such pre-determined level to energize the quicklime feeder, a temperature sensor mounted in the slaking tank for measuring the temperature of the milk of lime formed in the tank as quicklime is fed into the tank, a thermostatic valve responsive to the temperature sensor for adding water into the tank in quantities such as to maintain the temperature of the milk of lime in the tank, as it is formed, at a desired value, and a high level liquid sensor mounted in the slaking tank for stopping the quick-lime feeder means when the maximum level of milk of lime in the tank is reached.
Description
~PPA~ ~TUS F~ S~A~ING LI~E
This invention relates to an apparatus ~or slaking lime.
There ar~ on t~e market various apparatus commonly called "slakers" which are used for slaking quicklime to produce milk of lime. Lime slaking is well known and a reference is made to the textbook "Lime: Handling, Application and Storage" published by "National Lime Association", more particularly chapter V, pages 43-70, for a description of the theory of slaking, ~he methods used for slaking lime and the various types of slakers.
Slaking is commonly done by continuous slakers wherein predetermined ratios of lime and water are automatically mixed together under closely controlled temperature csnditions. Batch slaking is also known ~ut it is usually limited to simple handmixing of quicklime and water in relatively small containers although one procedure for batch slaking is known w~erein truckloads of quicklime may ~e unloaded directly into a mechanical mixing apparatus simultaneously with the requisite amount of water. However, batch slaking generally relie~ on the skill of an operator for determination o the proper lime/water ratio.
It-is the object o~ the present inven~ion to provide an apparatus for batch slaking of lime in a completely automatic manner without the help of an operator.
The apparatus, in accordance with the invention, comprises a slaking tank, a low level liquid sensor mount~d , ~
~ 2 -in the slaking tank, an electxomagnetic valYe responsive to the low level liquid ~ensor for allowing dïluting ~ater to flow into the slaking tank. up to a predetermined level, feeder means for feeding quicklime into the slaking tank at a cons.tant rate, relay means responsive to closure of such electroma~netic valve when the level of diluting water has reached ~uch predetermined level to energize the quicklime feeder, a temperature sensar mounted in the slaking tank for measuring the temperature 1~ of the milk of lime formed in the tank as quicklime is fed into the tank, a thermostatic ~alve responsive to the temperature sensor for adding ~ater into the tank in quantities such as to maintain ~he ~emperature of the milk of lime in the tank, as it is formed, at a desired value, and a high level liquid sensor mounted in the slaking tank for stopping the quicklime eeder means ~hen the maximum level of milk of lime in the tank is reached.
The apparatu~ pre~erably further comprises a milk of lime holding tank, a low level liquid sensor 2Q mounted in the holding tank, a transfer pump or pumping the mil~ of lime from the slaking tank to the holding tank, and a second relay means responsive to the Iow level liquid sensor in the holding tank or energizing the tran~fer pump. The milk of lime is preferably transferred into the holding tank. through. a sand removal reservoir for removing sand or other large particles from the milk of lime. Diluting water is also preferably fed to the milk . 3 _ of lime during transfer to the holding tank.
A maximum temperature sensor is also preferably positioned in the slaking tank for detec~ing any increase of temperature of the milk of lime above a maximum value and for stopping the quicklime feeder when such a maximum value is reachedO Means are also preferably provided for feeding additional water to the slaking tank to rapidly lower the temperature of the milk of lime below such maximum value.
The apparatus in accordance with.the.present invention also prefera~ly comprises sensor means associated with major elements of the apparatus for providing a signal indicative of th~ good operation of the major elements, and means responsi~e to such sensor means for stopping the apparatus when anyone of the major elements does not operate properly. Alarm de~ices are also associated with such.sensors for indicating maloperation of anyone of the maj~r elements.
The invention will now ~e disclosed,by ~ay of example, with reference to the accompanying drawings in which: -Figure 1 illustrate an embodiment of a limeslaking apparatus in accordance with. the inventioni and Figures 2 and 3 illustrate an emhodiment of a control circuit for controlling the operation of the apparatus of Figure 1.
o l~
Referring to Figurs 1, ~here is shown a quicklime storage tank 10 located above a slaking tank 12 so that the transfer of quicklime may ~e easily affected ~y gravity using a screw feeder 14 operated ~y a motor 16. A vibrator 18 is mounted on the storage tank for facilitating transfer of quicklime into the screw feeder. The slaking tank is provided with high and low level liquid sensors 20 and 22.
A mixer 24 is suspended in the slaking tank for mixing the solution contained in the tank. The tank is also provided with an opening 25 at the top for proper removal of heat from the slaking tank, and with a drain valve 26.
The slaking apparatus further comprises a holding tank 27 which.is used for storing the milk of lime produced in slaking tank 12. The transfer of the milk of lime from th~ slaking tank to the holding tank is done by a pump 28 through an elec~romagnetic valve 30 and a sand-removal reservoir 32. Such transfer is controlled by a liquid level sensor 34 installed in the holding tank 27.
Diluting and washing water is fed to the top of 2Q the slaking tank through an electromagnetic valve 36.
M~xing water is fed to the ~ottom of the slaking tank through.a thermostatic valve 38 whic~ is controlled by a temperature sensor 40 secured to the wall of the slaking tank.. An emergency solenoid valve 42 operated by a maximum ~5 temperature sensor 44 is connected across thermostatic valve 38 for cooling the slaking tank when the temperature of the sol-~tion in the tank exceeds a maximum value.
Diluting water is also fed to the sand removal reservoir
This invention relates to an apparatus ~or slaking lime.
There ar~ on t~e market various apparatus commonly called "slakers" which are used for slaking quicklime to produce milk of lime. Lime slaking is well known and a reference is made to the textbook "Lime: Handling, Application and Storage" published by "National Lime Association", more particularly chapter V, pages 43-70, for a description of the theory of slaking, ~he methods used for slaking lime and the various types of slakers.
Slaking is commonly done by continuous slakers wherein predetermined ratios of lime and water are automatically mixed together under closely controlled temperature csnditions. Batch slaking is also known ~ut it is usually limited to simple handmixing of quicklime and water in relatively small containers although one procedure for batch slaking is known w~erein truckloads of quicklime may ~e unloaded directly into a mechanical mixing apparatus simultaneously with the requisite amount of water. However, batch slaking generally relie~ on the skill of an operator for determination o the proper lime/water ratio.
It-is the object o~ the present inven~ion to provide an apparatus for batch slaking of lime in a completely automatic manner without the help of an operator.
The apparatus, in accordance with the invention, comprises a slaking tank, a low level liquid sensor mount~d , ~
~ 2 -in the slaking tank, an electxomagnetic valYe responsive to the low level liquid ~ensor for allowing dïluting ~ater to flow into the slaking tank. up to a predetermined level, feeder means for feeding quicklime into the slaking tank at a cons.tant rate, relay means responsive to closure of such electroma~netic valve when the level of diluting water has reached ~uch predetermined level to energize the quicklime feeder, a temperature sensar mounted in the slaking tank for measuring the temperature 1~ of the milk of lime formed in the tank as quicklime is fed into the tank, a thermostatic ~alve responsive to the temperature sensor for adding ~ater into the tank in quantities such as to maintain ~he ~emperature of the milk of lime in the tank, as it is formed, at a desired value, and a high level liquid sensor mounted in the slaking tank for stopping the quicklime eeder means ~hen the maximum level of milk of lime in the tank is reached.
The apparatu~ pre~erably further comprises a milk of lime holding tank, a low level liquid sensor 2Q mounted in the holding tank, a transfer pump or pumping the mil~ of lime from the slaking tank to the holding tank, and a second relay means responsive to the Iow level liquid sensor in the holding tank or energizing the tran~fer pump. The milk of lime is preferably transferred into the holding tank. through. a sand removal reservoir for removing sand or other large particles from the milk of lime. Diluting water is also preferably fed to the milk . 3 _ of lime during transfer to the holding tank.
A maximum temperature sensor is also preferably positioned in the slaking tank for detec~ing any increase of temperature of the milk of lime above a maximum value and for stopping the quicklime feeder when such a maximum value is reachedO Means are also preferably provided for feeding additional water to the slaking tank to rapidly lower the temperature of the milk of lime below such maximum value.
The apparatus in accordance with.the.present invention also prefera~ly comprises sensor means associated with major elements of the apparatus for providing a signal indicative of th~ good operation of the major elements, and means responsi~e to such sensor means for stopping the apparatus when anyone of the major elements does not operate properly. Alarm de~ices are also associated with such.sensors for indicating maloperation of anyone of the maj~r elements.
The invention will now ~e disclosed,by ~ay of example, with reference to the accompanying drawings in which: -Figure 1 illustrate an embodiment of a limeslaking apparatus in accordance with. the inventioni and Figures 2 and 3 illustrate an emhodiment of a control circuit for controlling the operation of the apparatus of Figure 1.
o l~
Referring to Figurs 1, ~here is shown a quicklime storage tank 10 located above a slaking tank 12 so that the transfer of quicklime may ~e easily affected ~y gravity using a screw feeder 14 operated ~y a motor 16. A vibrator 18 is mounted on the storage tank for facilitating transfer of quicklime into the screw feeder. The slaking tank is provided with high and low level liquid sensors 20 and 22.
A mixer 24 is suspended in the slaking tank for mixing the solution contained in the tank. The tank is also provided with an opening 25 at the top for proper removal of heat from the slaking tank, and with a drain valve 26.
The slaking apparatus further comprises a holding tank 27 which.is used for storing the milk of lime produced in slaking tank 12. The transfer of the milk of lime from th~ slaking tank to the holding tank is done by a pump 28 through an elec~romagnetic valve 30 and a sand-removal reservoir 32. Such transfer is controlled by a liquid level sensor 34 installed in the holding tank 27.
Diluting and washing water is fed to the top of 2Q the slaking tank through an electromagnetic valve 36.
M~xing water is fed to the ~ottom of the slaking tank through.a thermostatic valve 38 whic~ is controlled by a temperature sensor 40 secured to the wall of the slaking tank.. An emergency solenoid valve 42 operated by a maximum ~5 temperature sensor 44 is connected across thermostatic valve 38 for cooling the slaking tank when the temperature of the sol-~tion in the tank exceeds a maximum value.
Diluting water is also fed to the sand removal reservoir
2~
through an electromagnetic valYe 46.
A thermometer 48 i5 mounted on the slaking tank to calibrate the temperature sensor 400 TIle sand removal reservoir is also ~rovided wi~h an electrorlagnetic drain valve 50.
Screw feeder 14, mixer 24l pump 28, and valves 30, 36, 46 and 50 are all provided ~ith suitable operation sensors 114, 124, 128, 130, 136, 146 and 150, respectively, which operate so called "feedback" contacts located in the control-circuit of Figures 2 and 3 and used to provide an indication of the proper operation of such. devices.
Referring now to Figures 2 and 3, the slaking apparatus operates as follows:
Let us assume for the purpose of the description that the milk of lime in the slaking tank 12 is full~
hydrated and ready to be transferred into the holding tank 27. Under these c~nditions, contacts Tl-l of a timing relay Tl which controls the maximum time requirement for the transfer of milk of lime and a timing relay T4 which controls.the minimum time requirement for a proper slaking operation are closed as it will be disclosed later. Contacts lS0-1 of drain valve sensor 150 are also closed when the drain valve 50 of the sand removal reservoir 32 is closed.
When the.level of milk of lime in holding tank 27 gets below the longest electrode of liquid lavel sens.or 34, its contacts 34-1 close and relay winding RLl is energized from powoer lines Ll and L2 through normally closed contacts RL6-1, RL7-1, T6-1, RLll-l ~to be disclosed laterl. Contacts RLl-l of ~inding RLl are closed to energize the ~tr:n~.ing of electromagnetic valve 30. As soon as the valve 30 opens, its feedback contacts 130-1 close to energize r lay winding RL2, which through its contacts RL2-1 energizes transfer pump 28 and the electromagnetic valve 46. When the pump starts to rotate r it~ feedback contacts 128-1 close to allow energization of relay winding RL3 through contacts 20-1 of the high.level liquid sensor 20. Relay winding RL3 will lQ not ~e.energized however until the ~evel of the milk of lime in the slaking tank has dropped below the el~ctrodes of the sensor 20 causing closure of its contacts 20-1. This is to prevent damages if the pump is not working properly.
m e energization of ~inding ~L3 closes contacts RL3-1 to energize the winding of electromagnetic .v.alve 36.
Diluting water is then fed into the slaking tank through jets located at various locations in the upper portion of the slaking tank. While diluting the milk of lime, this permits to clean, at each transfer, the electrodes of the liquid level sensors 20 and 22 as well as the slak~ng tank itself. To increase the rate of transfer, some diluting water is added to the sand removal reservoir, ~hrough valve 46.
When the level of milk of lime in holding tan~ 27 gets a~ove the shortest electrode of liquid level sensor 34, its contacts 34-1 open to automatically deenergize relay winding ~Ll which, through. the opening of its contacts RLl-l, releases electromagnetic valve 30.
The release of electromagnetic valve 3Q causes closure of the valve and ope~ing o f its feedback contacts 130-1.
The opening of feedback contacts 130-1 releases relay winding RL2 which, through. the operning of its contacts Rh2-1, shuts off transfer pump 28 and closes electro-magnetic valve 46. Diluting water valve 36 remains open however because contacts RL3-1 are still closed. Indeed, relay winding RL3 is hel.d energized through closed contacts 22-1 of the low level liquid sensor 22 until the level of 1~ liquid in the slaking tank has raised to the level of the electrodes of the sensor 22. At the beginning of the ~ransfer, a timer Tl is energized through feed~ack contacts 128-2 of the transfer pump. Timer Tl is used to stop the transfer of the milk of lime (by opening its contacts Tl-l in the energizing circuit of rela~ RLll after a pre determined time interval so as to prevent excessive water ~e.ing fed to the holding tank which.would considerably affect the density of the milk bf lime ~eing stored.
As soon as th.e diluting water valve 36 closes, 2~ its feedback contacts 136-1 close to energize relay winding RL4 through normally closed contacts 44-1 of maxim~m temperature sensor 44, closed contacts 124-1 of mixer 24, closed contacts 20-2 of high. level level liquid sensor 20 and normally closed eed~ack contacts 25 114-1 of the quicklime feeder 14, if the state of the a~ove contacts allows it. Contacts 44-1 are closed when the temperature of the slaking tank is normal;
contacts 124-1 are closed when mixer 24 is working;
contacts 20-2 are closed when the electrodes of the .
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high level li~uid sensor are out of the liquid; finally, contacts 114-1 are closed when feeder 14 is working~
The energization of relay RL4 closes contacts RL4-1 which control energization of the scre~ feeder motor 16. Once the screw feeder is started, it continues to run until th~ electrodes of the high level liquid sensor are in the liquid causing opening of contacts 20-2 or until one of the other contacts in series with contacts 20 2 in the energization circuit of relay winding RL4 open.
When the screw feeder 14 is running, its feedback contacts 114-2 operate a timer T2 which, through its contacts T2-1, operates vi~rator 18 at regular time intervals. Furthermore, all the time relay RL4 is energized, a timer T3 i5 energize~ through contacts RL4-2.
Timer T3, through its contacts T3-1 energizes for a pre-determined time interval ~he winding of the electromagnetic YalYe 50 to drain from the sand removal reservoir the LmpuritieS accumulated therein during the transfer of milk of lime from the slaking tank to the holding tank.
As quicklime is added to water present in the ~lak~ng tank, the temperature of the solution in the slaking tank increases, as commonly known. When the temperature reaches 75C, thermostatic valve 38 opens to add water to the ~ase of the slaking tank in quantities such as to maintain the temperature of the slaking tankat 75C. The level of solution in the slaking tank then starts to rise.
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Temperature sensor 44 which is located at the base of the slaking tank permits, through its contacts 44-1, to stop the screw feeder (by deenergization of relay RL4) if the temperature exceeds 80C. At the same time, solenoid valve 42 is energized through contacts 44-2 of temperature sensor 44 to ~y-pass thermostatic valve 38 and add additional water into the slaking tank to lower the temperature of the slaking tank to 75C. When the ~emperature has reduced, contacts 144-2 of temperature sensor 44 open to release 1~ the solenoid valve 42. At the same time, contacts 44-1 of temperature sensor 44 close to reenergize relay winding RL4 and restart the screw feeder~
When the level of solution in the slaking tank reaches the electrodes of~th~ high level liquid sensor 2~, contacts 20-2 open to release relay winding R~4 and stop the screw feeder. A tîmer T4 is then energized through normally closed contacts RL4-3 of relay RL4.
This timer prevents, for a predetermined time interval t~rough its contacts T4-1, the energization of relay 2Q RLl which initiates the subsequent transfer of the milk of lime to the holding tank. This is to allow sufficient time for the newly formed milk of lime to be adequately h~drated before being transferred to the holding tank.
As soon as the required time has elapsed timer T4 will release to allow energization of relay RLl and subsequent transfer of the milk of lime from the slaking tank to the holding tank.
As illustrated in Figu.re 3, th~ circuit for controlling the operation o~.the slaking apparatus further comprises a series of alarms which facilitate identifica-tion and repairs of eventual failures in the slaking apparatus, each alarm being dedicated to a major component of the apparatus. As men~ioned previously, a sensor has been installed on each.major mechanical component which control the operation of the slaker and such sensors are provided with "feedback" contacts in the control circuit lQ of the slaking apparatus. Thus, each time that one of th major mechanical components is energized, such as one of the valves, the screw feeder, the mixer, the transfer pump, a feedback sisnal is provided and sucA signal is required.in order to allow the control circuit to move to the next step in the sequence of operation. In addition, as soon as a majox mechanical component is energized, its associated feedback contacts must be operated by its associated sensor within 5 seconds, otherwise an alarm signal is given.
I,et us take, for ~xample, ~he electromagnetic valve 3Q adjacent the transfer pump 28. When t~e relay RLl is energized, at the beginning of the transfer of the milk of lime fro~ the slaking tank to the holding tank, its associated contacts RLl-2 are closed and a timer T5 is ~nergized throush.closed feedback contacts 130-2 of valve 30. I due to some failure,. the valve does not open within 5 seconds, timer T5 will close its contacts T5-1, T5-2 and T5-3~ Timer T5 locks operated through.
its own contacts T5-3 and manual reset s~itch Sla. The timer will thus remain energized until reset switch Sla is operated. The closure of contacts T5-1 causes en~r-gization of a relay RL5 through cloaed contacts 130-3 and RL1-3 whereas the closure of contacts T5-2 causes the energization of an alarm device ALl through the now closed contacts RL5-1. The alarm device is maintained energized until ~he alarm is reset by manual opening of switch Sla.
If the valve 30 opens within a delay of 5 seconds, its feed~ack contact 130-3 will open and relay RL5 and the alarm ALl will not be energized.
Relays RL6, RL7, RL8, RL9 and RL10 and their associated alarms ALZ, AL3, AL4, AL5 and AL6 operate the same way when the transfer pump 28, the slaker diluting water valve 36, the screw feeder 14, the drain valve 50 and the diluting water valve 46, respectively, are energized but fail to operate due to a mechanical failure, and it is not ~eliaved to be necessary to disclose the operation of such relays and associated alarm devices in detail.
AnQther alarm lS provided to indicate when the transfer pUI~ 28 iS defectuous even if it rotates~ When th~ transfer pump is ènergized its feedback contacts 128-5 close and contacts 20-3 of high level liquid sensor 20 are closed because its electrodes are in the liquid so that a timer T6 is energized. If within 2 minutes after the transfer pump is energized, the feedback contacts 20-3 have not opened because the electrodes of high level liquid sensor 20 are still immersed in liquid, the timer T6 will close its contacts T6-2 and T6-3. An alarm device AL7 will then be energized and maintained energized until it is reset manually by operation of switch Slb.
During a transfer of the milk of lime from the slaking tank 12 to the h.olding tank.27, the level of liquid in the slaking tank must necessarily go down below t~e low level liquid sensor 22 before the transfer pump stops. This is to prevent the density of the lime in the slaking tank from getting too high in case of maloperation lQ of the pump. If the level of the liquid in the tank does not get belo~ the low le~l liquid sensor, contacts 22-2 will still b~ closed when feedback contacts 128~6 of transfer pump 28 close. This will energize a relay winding RLll and an alarm device AL8. The alarm device locks operated throug~ contacts RL11-2 of relay RLll and must be reset manually through the opening of contacts Slc.
Additional alarms AL9 and AL10 are also energized when the maximum temperature sensor 44 operates its contacts 44-3 or when mixer 24 stops closing its contacts 2a 124-2.
~ hen an alarm dPvice is energized, the control of the slaker i5 stopped automaticaLly either because the failure prevents continuation of the sequence of operation, or because power is removed by the opening of contacts RL6-1, RL7-1, T6-1 and RLll-l in series with lines Ll and L2~
Although the invention has been disclosed, with reference to a preferred em~odiment and with reference to a preferred control circuit, it is to be understood that , - 1:3 -other alternatives are also envisaged ~ithin th~ scope of the following claims and that the invention is not limited to such preferred em~odiment.
through an electromagnetic valYe 46.
A thermometer 48 i5 mounted on the slaking tank to calibrate the temperature sensor 400 TIle sand removal reservoir is also ~rovided wi~h an electrorlagnetic drain valve 50.
Screw feeder 14, mixer 24l pump 28, and valves 30, 36, 46 and 50 are all provided ~ith suitable operation sensors 114, 124, 128, 130, 136, 146 and 150, respectively, which operate so called "feedback" contacts located in the control-circuit of Figures 2 and 3 and used to provide an indication of the proper operation of such. devices.
Referring now to Figures 2 and 3, the slaking apparatus operates as follows:
Let us assume for the purpose of the description that the milk of lime in the slaking tank 12 is full~
hydrated and ready to be transferred into the holding tank 27. Under these c~nditions, contacts Tl-l of a timing relay Tl which controls the maximum time requirement for the transfer of milk of lime and a timing relay T4 which controls.the minimum time requirement for a proper slaking operation are closed as it will be disclosed later. Contacts lS0-1 of drain valve sensor 150 are also closed when the drain valve 50 of the sand removal reservoir 32 is closed.
When the.level of milk of lime in holding tank 27 gets below the longest electrode of liquid lavel sens.or 34, its contacts 34-1 close and relay winding RLl is energized from powoer lines Ll and L2 through normally closed contacts RL6-1, RL7-1, T6-1, RLll-l ~to be disclosed laterl. Contacts RLl-l of ~inding RLl are closed to energize the ~tr:n~.ing of electromagnetic valve 30. As soon as the valve 30 opens, its feedback contacts 130-1 close to energize r lay winding RL2, which through its contacts RL2-1 energizes transfer pump 28 and the electromagnetic valve 46. When the pump starts to rotate r it~ feedback contacts 128-1 close to allow energization of relay winding RL3 through contacts 20-1 of the high.level liquid sensor 20. Relay winding RL3 will lQ not ~e.energized however until the ~evel of the milk of lime in the slaking tank has dropped below the el~ctrodes of the sensor 20 causing closure of its contacts 20-1. This is to prevent damages if the pump is not working properly.
m e energization of ~inding ~L3 closes contacts RL3-1 to energize the winding of electromagnetic .v.alve 36.
Diluting water is then fed into the slaking tank through jets located at various locations in the upper portion of the slaking tank. While diluting the milk of lime, this permits to clean, at each transfer, the electrodes of the liquid level sensors 20 and 22 as well as the slak~ng tank itself. To increase the rate of transfer, some diluting water is added to the sand removal reservoir, ~hrough valve 46.
When the level of milk of lime in holding tan~ 27 gets a~ove the shortest electrode of liquid level sensor 34, its contacts 34-1 open to automatically deenergize relay winding ~Ll which, through. the opening of its contacts RLl-l, releases electromagnetic valve 30.
The release of electromagnetic valve 3Q causes closure of the valve and ope~ing o f its feedback contacts 130-1.
The opening of feedback contacts 130-1 releases relay winding RL2 which, through. the operning of its contacts Rh2-1, shuts off transfer pump 28 and closes electro-magnetic valve 46. Diluting water valve 36 remains open however because contacts RL3-1 are still closed. Indeed, relay winding RL3 is hel.d energized through closed contacts 22-1 of the low level liquid sensor 22 until the level of 1~ liquid in the slaking tank has raised to the level of the electrodes of the sensor 22. At the beginning of the ~ransfer, a timer Tl is energized through feed~ack contacts 128-2 of the transfer pump. Timer Tl is used to stop the transfer of the milk of lime (by opening its contacts Tl-l in the energizing circuit of rela~ RLll after a pre determined time interval so as to prevent excessive water ~e.ing fed to the holding tank which.would considerably affect the density of the milk bf lime ~eing stored.
As soon as th.e diluting water valve 36 closes, 2~ its feedback contacts 136-1 close to energize relay winding RL4 through normally closed contacts 44-1 of maxim~m temperature sensor 44, closed contacts 124-1 of mixer 24, closed contacts 20-2 of high. level level liquid sensor 20 and normally closed eed~ack contacts 25 114-1 of the quicklime feeder 14, if the state of the a~ove contacts allows it. Contacts 44-1 are closed when the temperature of the slaking tank is normal;
contacts 124-1 are closed when mixer 24 is working;
contacts 20-2 are closed when the electrodes of the .
- 8 ~
high level li~uid sensor are out of the liquid; finally, contacts 114-1 are closed when feeder 14 is working~
The energization of relay RL4 closes contacts RL4-1 which control energization of the scre~ feeder motor 16. Once the screw feeder is started, it continues to run until th~ electrodes of the high level liquid sensor are in the liquid causing opening of contacts 20-2 or until one of the other contacts in series with contacts 20 2 in the energization circuit of relay winding RL4 open.
When the screw feeder 14 is running, its feedback contacts 114-2 operate a timer T2 which, through its contacts T2-1, operates vi~rator 18 at regular time intervals. Furthermore, all the time relay RL4 is energized, a timer T3 i5 energize~ through contacts RL4-2.
Timer T3, through its contacts T3-1 energizes for a pre-determined time interval ~he winding of the electromagnetic YalYe 50 to drain from the sand removal reservoir the LmpuritieS accumulated therein during the transfer of milk of lime from the slaking tank to the holding tank.
As quicklime is added to water present in the ~lak~ng tank, the temperature of the solution in the slaking tank increases, as commonly known. When the temperature reaches 75C, thermostatic valve 38 opens to add water to the ~ase of the slaking tank in quantities such as to maintain the temperature of the slaking tankat 75C. The level of solution in the slaking tank then starts to rise.
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Temperature sensor 44 which is located at the base of the slaking tank permits, through its contacts 44-1, to stop the screw feeder (by deenergization of relay RL4) if the temperature exceeds 80C. At the same time, solenoid valve 42 is energized through contacts 44-2 of temperature sensor 44 to ~y-pass thermostatic valve 38 and add additional water into the slaking tank to lower the temperature of the slaking tank to 75C. When the ~emperature has reduced, contacts 144-2 of temperature sensor 44 open to release 1~ the solenoid valve 42. At the same time, contacts 44-1 of temperature sensor 44 close to reenergize relay winding RL4 and restart the screw feeder~
When the level of solution in the slaking tank reaches the electrodes of~th~ high level liquid sensor 2~, contacts 20-2 open to release relay winding R~4 and stop the screw feeder. A tîmer T4 is then energized through normally closed contacts RL4-3 of relay RL4.
This timer prevents, for a predetermined time interval t~rough its contacts T4-1, the energization of relay 2Q RLl which initiates the subsequent transfer of the milk of lime to the holding tank. This is to allow sufficient time for the newly formed milk of lime to be adequately h~drated before being transferred to the holding tank.
As soon as the required time has elapsed timer T4 will release to allow energization of relay RLl and subsequent transfer of the milk of lime from the slaking tank to the holding tank.
As illustrated in Figu.re 3, th~ circuit for controlling the operation o~.the slaking apparatus further comprises a series of alarms which facilitate identifica-tion and repairs of eventual failures in the slaking apparatus, each alarm being dedicated to a major component of the apparatus. As men~ioned previously, a sensor has been installed on each.major mechanical component which control the operation of the slaker and such sensors are provided with "feedback" contacts in the control circuit lQ of the slaking apparatus. Thus, each time that one of th major mechanical components is energized, such as one of the valves, the screw feeder, the mixer, the transfer pump, a feedback sisnal is provided and sucA signal is required.in order to allow the control circuit to move to the next step in the sequence of operation. In addition, as soon as a majox mechanical component is energized, its associated feedback contacts must be operated by its associated sensor within 5 seconds, otherwise an alarm signal is given.
I,et us take, for ~xample, ~he electromagnetic valve 3Q adjacent the transfer pump 28. When t~e relay RLl is energized, at the beginning of the transfer of the milk of lime fro~ the slaking tank to the holding tank, its associated contacts RLl-2 are closed and a timer T5 is ~nergized throush.closed feedback contacts 130-2 of valve 30. I due to some failure,. the valve does not open within 5 seconds, timer T5 will close its contacts T5-1, T5-2 and T5-3~ Timer T5 locks operated through.
its own contacts T5-3 and manual reset s~itch Sla. The timer will thus remain energized until reset switch Sla is operated. The closure of contacts T5-1 causes en~r-gization of a relay RL5 through cloaed contacts 130-3 and RL1-3 whereas the closure of contacts T5-2 causes the energization of an alarm device ALl through the now closed contacts RL5-1. The alarm device is maintained energized until ~he alarm is reset by manual opening of switch Sla.
If the valve 30 opens within a delay of 5 seconds, its feed~ack contact 130-3 will open and relay RL5 and the alarm ALl will not be energized.
Relays RL6, RL7, RL8, RL9 and RL10 and their associated alarms ALZ, AL3, AL4, AL5 and AL6 operate the same way when the transfer pump 28, the slaker diluting water valve 36, the screw feeder 14, the drain valve 50 and the diluting water valve 46, respectively, are energized but fail to operate due to a mechanical failure, and it is not ~eliaved to be necessary to disclose the operation of such relays and associated alarm devices in detail.
AnQther alarm lS provided to indicate when the transfer pUI~ 28 iS defectuous even if it rotates~ When th~ transfer pump is ènergized its feedback contacts 128-5 close and contacts 20-3 of high level liquid sensor 20 are closed because its electrodes are in the liquid so that a timer T6 is energized. If within 2 minutes after the transfer pump is energized, the feedback contacts 20-3 have not opened because the electrodes of high level liquid sensor 20 are still immersed in liquid, the timer T6 will close its contacts T6-2 and T6-3. An alarm device AL7 will then be energized and maintained energized until it is reset manually by operation of switch Slb.
During a transfer of the milk of lime from the slaking tank 12 to the h.olding tank.27, the level of liquid in the slaking tank must necessarily go down below t~e low level liquid sensor 22 before the transfer pump stops. This is to prevent the density of the lime in the slaking tank from getting too high in case of maloperation lQ of the pump. If the level of the liquid in the tank does not get belo~ the low le~l liquid sensor, contacts 22-2 will still b~ closed when feedback contacts 128~6 of transfer pump 28 close. This will energize a relay winding RLll and an alarm device AL8. The alarm device locks operated throug~ contacts RL11-2 of relay RLll and must be reset manually through the opening of contacts Slc.
Additional alarms AL9 and AL10 are also energized when the maximum temperature sensor 44 operates its contacts 44-3 or when mixer 24 stops closing its contacts 2a 124-2.
~ hen an alarm dPvice is energized, the control of the slaker i5 stopped automaticaLly either because the failure prevents continuation of the sequence of operation, or because power is removed by the opening of contacts RL6-1, RL7-1, T6-1 and RLll-l in series with lines Ll and L2~
Although the invention has been disclosed, with reference to a preferred em~odiment and with reference to a preferred control circuit, it is to be understood that , - 1:3 -other alternatives are also envisaged ~ithin th~ scope of the following claims and that the invention is not limited to such preferred em~odiment.
Claims (8)
1. An apparatus for batch slaking of lime comprising:
a) a slaking tank (12);
b) a low level liquid sensor (22) mounted in the slaking tank;
c) an electrical control circuit;
d) an electromagnetic valve (36) energized by said control circuit and responsive to said low level liquid sensor for allowing diluting water to flow into the slaking tank up to a predetermined level;
e) feeder means (14) for feeding quicklime into the slaking tank at a constant rate;
f) relay means (RL4) energized by said control circuit and responsive to closure of said electromagnetic valve when the level of diluting water has reached said predetermined level to energize said quicklime feeder;
g) a temperature sensor (40) mounted in the slaking tank for measuring the temperature of the milk of lime formed in the tank as quicklime is fed into the tank;
h) a thermostatic valve (38) responsive to said temperature sensor for adding water into the tank in quantities such as to maintain the temperature of the milk of lime in the tank, as it is formed, at a desired value; and i) a high level liquid sensor (20) mounted in the slaking tank for stopping the quicklime feeder means when the maximum level of milk of lime in the tank is reached.
a) a slaking tank (12);
b) a low level liquid sensor (22) mounted in the slaking tank;
c) an electrical control circuit;
d) an electromagnetic valve (36) energized by said control circuit and responsive to said low level liquid sensor for allowing diluting water to flow into the slaking tank up to a predetermined level;
e) feeder means (14) for feeding quicklime into the slaking tank at a constant rate;
f) relay means (RL4) energized by said control circuit and responsive to closure of said electromagnetic valve when the level of diluting water has reached said predetermined level to energize said quicklime feeder;
g) a temperature sensor (40) mounted in the slaking tank for measuring the temperature of the milk of lime formed in the tank as quicklime is fed into the tank;
h) a thermostatic valve (38) responsive to said temperature sensor for adding water into the tank in quantities such as to maintain the temperature of the milk of lime in the tank, as it is formed, at a desired value; and i) a high level liquid sensor (20) mounted in the slaking tank for stopping the quicklime feeder means when the maximum level of milk of lime in the tank is reached.
2. An apparatus as defined in claim 1, further comprising a milk of lime holding tank (27), a low level liquid sensor (34) mounted in said holding tank, a transfer pump (28) for pumping the milk of lime from said slaking tank to said holding tank, and a second relay means (RL2) energized by said control circuit and responsive to the low level liquid sensor in said holding tank for energizing said transfer pump.
3. An apparatus as defined in claim 2, further comprising a sand removal reservoir (32) interconnecting the transfer pump to the holding tank for removing sand or other large particles from the milk of lime, and an electromagnetic valve (46) energized by said control circuit and responsive to said second relay means for feeding diluting water into the sand removal reservoir during transfer of the milk of lime to the holding tank.
4. An apparatus as defined in claim 3, further comprising an electromagnetic drain valve (50) energized by said control circuit and responsive to said first relay means for removing impurities accumulated in the sand removal reservoir during the transfer of milk of lime from the slaking tank to the holding tank.
5. An apparatus as defined in claim 1, 2 or 3, further comprising a maximum temperature sensor (44) mounted on the slaking tank for detecting any increase of temperature of the milk of lime above a maximum value for stopping said quicklime feeder means, and further comprising a selenoid valve (42) energized by said control circuit and responsive to said maximum temperature sensor for feeding additional water to the slaking tank to rapidly lower the temperature of the milk of lime below said maximum valve.
6. An apparatus as defined in claim 2, 3 or 4, further comprising a timer (T4) energized by said control circuit and responsive to said high level liquid sensor for delaying the operation of said second relay means so as to provide enough time for adequate hydration of the milk of lime before transfer to the holding tank.
7. An apparatus as defined in claim 4, further comprising sensor means (114, 136, 146, 150) associated with said feeder, said transfer pump and other control elements of the apparatus for providing a signal indicative of the good operation of said control elements and means for stopping the apparatus if any one of said control elements does not operate properly.
8. An apparatus as defined in claim 7, further comprising alarm means responsive to said sensor means for indicating maloperation of anyone of said control elements.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000437049A CA1212825A (en) | 1983-09-19 | 1983-09-19 | Apparatus for slaking lime |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000437049A CA1212825A (en) | 1983-09-19 | 1983-09-19 | Apparatus for slaking lime |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1212825A true CA1212825A (en) | 1986-10-21 |
Family
ID=4126110
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000437049A Expired CA1212825A (en) | 1983-09-19 | 1983-09-19 | Apparatus for slaking lime |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1212825A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6451281B1 (en) | 2001-05-30 | 2002-09-17 | Mississippi Lime Company | Methods of manufacturing micro-particulated hydrate slurries |
| WO2011136658A1 (en) * | 2010-04-28 | 2011-11-03 | Poju R. Stephansen As | Method for temperature control in a slaker |
| US8703093B2 (en) | 2012-03-12 | 2014-04-22 | Poju R. Stephansen | Method for batchwise slaking of burnt lime in a slaker |
| WO2016053109A1 (en) * | 2014-09-30 | 2016-04-07 | Poju R. Stephansen As | Method for removal of grit in a slaker equipped with a grit collector |
-
1983
- 1983-09-19 CA CA000437049A patent/CA1212825A/en not_active Expired
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6451281B1 (en) | 2001-05-30 | 2002-09-17 | Mississippi Lime Company | Methods of manufacturing micro-particulated hydrate slurries |
| WO2011136658A1 (en) * | 2010-04-28 | 2011-11-03 | Poju R. Stephansen As | Method for temperature control in a slaker |
| US9126863B2 (en) | 2010-04-28 | 2015-09-08 | Poju R. Stephansen As | Method for temperature control in a slaker |
| US8703093B2 (en) | 2012-03-12 | 2014-04-22 | Poju R. Stephansen | Method for batchwise slaking of burnt lime in a slaker |
| WO2016053109A1 (en) * | 2014-09-30 | 2016-04-07 | Poju R. Stephansen As | Method for removal of grit in a slaker equipped with a grit collector |
| NO341006B1 (en) * | 2014-09-30 | 2017-08-07 | Poju R Stephansen As | Procedure for removing heavier gravel during batch leaching of burnt lime, as well as associated leaching |
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