CA1268605A - Method of controlling alkaline pulping by means of a rapid analyzer measuring organic and inorganic cooking liquor components - Google Patents
Method of controlling alkaline pulping by means of a rapid analyzer measuring organic and inorganic cooking liquor componentsInfo
- Publication number
- CA1268605A CA1268605A CA000494986A CA494986A CA1268605A CA 1268605 A CA1268605 A CA 1268605A CA 000494986 A CA000494986 A CA 000494986A CA 494986 A CA494986 A CA 494986A CA 1268605 A CA1268605 A CA 1268605A
- Authority
- CA
- Canada
- Prior art keywords
- sample
- pulping
- measuring
- analyzer
- sulphate
- 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 - Lifetime
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Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C7/00—Digesters
- D21C7/12—Devices for regulating or controlling
Abstract
Abstract of the Disclosure The invention relates to a method of controlling an alkaline pulping process, sulphate pulping in particular. According to the invention, the concentration of the dissolved components as well as the concentration of the residual cooking chemical are measured. The measurements are carried out by means of an analyzer positioned outside of the cooking process in a separate liquid flow. The measuring devices are per se known detectors. The cooking process is observed and the necessary corrections are made on the basis of the measuring results.
(Figure 1)
(Figure 1)
Description
~3~
A method of controlling alkaline pulping by means of a rapid analyzer measuring organic and inorganic cooking liyuor components The invention relates to a method of controlling alkaline pulping processes, especially sulphate pulping, in which method the components dissolved from wood and the recidual inorganic cooking chemical are measured from the process liquors by means of a rapid analyzer apparatus.
The object of the invention was to provide a method of obtaining measuring data on the concentrations of the cooking chemical and the reaction product of alkaline pulping processes at short intervals for controlling the cooking on the basis of the factual proceeding thereof.
: The object of the invention is achieved by feeding a small sample taken from the process into a separate analyzer liquid flow having accurately uniform conditions, in which flow the sample, after having been diluted therein under the influence of diffusion, flows as a peak-shaped zone having a nearly normally distributed concentration through different kind of measuring dP~ices operated on the flow-through principle. Lignin dissolved from wood is measured on the basis of the absorption of the ultraviolet radiation at the wave length of an extreme point (e.g. 205 or 280 nm) of the UV-spectrum of lignin; the total amount of the dry matter dissolved from wood is measured on the basis of the difference in the re~raction index in relation to a pure flowing medium by means of a differential xefractometer; the residual active alkali being measured by a conductivity measurement. In addition, the liquid flow can be passed through any measurement carried out .~ .
' ~ ~
'' ~ .
~.
~26~
on the flow-through principle in order to provide further measurings. Obtaining data from the above-mentioned measurements involves the principle that the alkali concentration measured at the beginning of the cooking and during -the proceeding thereof is used as grounds for set-ting an objective for -the end point of the cooking, the attainment of said objective being then observed and, if required, corrected by means of measurements of the reaction products. In other words, the cooking is here controlled both by means of a "feed forward" control directed forwards and a "feed back" control connected backwards. Both ways of controlling have been suggested to be effected by means of different kinds of direct measurements carried out from the process pipelines or by means of automatic titrators. The novelty of the present invention lies in that the arrangement according to the present method combines all ways of control by providing the necessary data by means of a single apparatus and from one and the same sample. The present measuring tech-nique is particularly advantageous in that the measurements are independent of any changes of the zero point, because there is always returned to the zero between the measurements and there are measured only the differences caused by the sample in the quantity to be measured in relation to time. Further, the measuring devices are not at all liable to become contaminated, as the sample is diluted and a pure measuring medium flows between the samples.
At present, controlling of alkaline pulping processes, sulphate pulping in particular, is based on the fact that it has been possible to develop a ma-thematical model, a so called H-factor, on lignin dissolution occuring during the cooking, said model taking into consideration the cooking chemical charge, ., .
, : , , - :. ,, : :;
,.
; ~,', 6~5 the digestlng temperature and the digesting time, as appears from the publication Rekunen, S., Jutila, E., LXhteenmaki, E., Lonnberg, B., Virkola, N-E., Examination of reaetion kinetics in kraft cooking.
Paperi ja Puu 62 (1980):2, 80-90). Thls kind oE
model operates fairly satisfac-torily, provided that the cooking conditions as well as the quali-ty and humidity of the wood ehips are known. However, this is not usually the ease at any single plant, but the conditions vary at random, and, although important for the process control, such quantities as humidity, quality and particle si~e distribution characteri~ing the raw material, i.e. chips, are left beyond the possibilities of the present measuring techniques.
Attempts have been made to improve the situation by carrying out different kind of measurements from the digester liquors. The amount of the eooking ehemieal or active alkali has been measured either by conduct-ivity measurement directly from a process pipeline system in a manner disclosed in the publication Lundqvist, G., Alkali analysis by conductivity measurements. Svensk Papperstid 76 (1972): 9, 524-527 or by an automatic microprocessor-controlled titration from the cooking liquid sample, which, in turn, is known from ~.S. Patent Specifications 4,104,028 and 4,012,197 as well as from the publication Wallin, G., Noreus, S., Computer control of bateh digesters.
Svensk Papperstid 76 (1973): 9, 329-334. A
disadvantage of a direet eonduetivity measurement, however, is that the proeess pipelines are extremenly liable to ge-t eontaminated, whieh results in slipping of the zero point and diffieulties in the eompensation thereof. Fairly reliable information is obtained on the aetive alkali by means of titrators, whieh, however, are slow and, besides, a single point per process in ~1~2t~ 05 the initial stayes thereof does not yet disclose the profile of the alkali consumption nor the recidual alkali providing perhaps the most important grounds for :Eorward control in view of the determination of the end point.
Attempts have also been made to measure lignin dissolved from wood and to determine the end poin-t of the cooking on said grounds. In particular, the absoxption of the ultraviolet radiation has been used in Kleinert, T.N., Joyce, C. S., Short wawelength ultraviolet absorption of various lignins and related substances. IV lignin determination in sulphate pulping liquor. Pulp and pap.mag.of Can. 58 (1957):
11, 147-152i Williams, D. J., The application of the ultraviolet absorption characteristic of lignin to the control of pulp uniformity. Appita 22 (1968):2, 45-52~ Capart, R., Obese -Dec-ty, K-, Le Cardinal, G., Gelus, M., Contribution to on-like kraft pulping control.
IFAC PRP 4 automation, Ghent, Belgium 1980, p. 121-128.
These methods are greatly disadvantageous in that they are continuously operated, whereby they are difficult to control with respect to contamination and, even the more, with respect to the extensive continuous dilution.
On account of technical difficulties, lignin measurements have not been put to constant use in process controlO Besides, it can be estimated that a mere lignin concentration without any information on the alkali concentration and the properties of the chip filling can not provide a reliable basis for the determination of the end point.
No mention of a combined use of the above-mentioned measurements nor of carrying out the same by a single apparatus and from one and the same sample has been found in literature.
The present invention combines the separate ;
:
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` '' .,:', . ~
.:.. . ::: .~.
. .: :
determinatiorls mentioned in literature above by means of a novel technique and by elimination of certain previously encountered factors which reduce the reliability of the measuring results, and simultaneously enables in principle an unlimited number of different flow-through measurements to be carried out from one and the same sample.
The following figures are illustrative of the invention: _ Figure 1 illustrates an analyzer apparatus or observing and controlling alkaline cooks, Figure 2 illustrates proceeding of a plant-scale sulphate batch pulping as a function of the digesting time, curve A representing the lignin content, curve B the dry matter content and curve F the residual alkali content Figures 3A and 3B show lignin dissolution curves calculated on the basis of the lignin measuring results of the analyzer, said curves concerning a plant-scale sulphate pulping process as a function of the pulping time, Figures ~A and 4B show a relative alkali concentratlon measured by the analyzer from a plant-scale sulphate batch pulping as a function of an alkali titration carried out in a laboratory, Figure 5 shows a relative dry matter content measured by the analyzer from a plant-scale sulphate batch pulping as a function of a dry matter content determination carried out in a laboratory, Figure 6 illustrates observation of a continuously operated sulphate pulping process, curve D representing the alkali concentration equalizing cycle, curve E the resi~ual alkali concentration in the outgoing black liquor, curve F -the lignin concentration in the outgoing black liquor, ,,j~ ~ .
~ . .
.. .
, ,,, - ' ' "' '"'"'` -~ ~ .
:~ .
.. .
~2~ 5 curve G the lignin concentration in the terminating cycle, curve H the lignin concentration in the washing cycle, curve J the lignin concentration equalizing cycle and curve k kappa number of pulp from digester.
According to Figure 1, a small sample is taken from a process pipeline, e.g. from a delivery-side 1 of a pump (a circulation pump of a batch digester or a circulating pump o~ one cycle of a continuously operated digester) by means of a valve 2, which sample is cooled in a condenser 3 and filtered in a sinter filter 4 and then passed through a normal position of a wash valve 5 to a loop 7 of a loop-injection valve 6. When a necessary amount of the sample, from the point of view of representativeness (with a tube size of 1/8" about 50 ml) 7 has passed through the loop, the injection valve 6 turns over 6~ and a separate liquid flow 8 of the analyzer (a pump or a pressurized liquid container) is conducted through the loop, thus taking therewith a uniform volume (the loop being 25 microliters) of the sample. In the analyzer liquid flow ~usually pure water but also a diluted alkali or an alkalic buffer solution is possible), the sample is diluted in a long capillary tube 9 (5-6 m 0 0.8 rnm teflon capillary) under the influence of diffusion without any artificial dilution steps and the diluted sample zone flows through different kinds of measuring devices: an ultraviolet or UV-detector 10 measuring the lignin concentration of the sample on the basis ~f the absorption of the ultraviolet radiation (205 or 280 nm); a refraction index or RI-detector measuring the dry matter content of the sample on the basis of a difference in the refraction indices; and a conductivity detector measuring the concentration of the residual active alkali on the basis of the conductivity o~ hydroxyl ions. In addition, the flow can be passed throuyh other measurements xx 13 operated : , ,. ~ .
.. ' . . :~
; ' ~ ~ :" . ., , )5 on the flow through principle, such a e.g. ion selective eLectrodes, pH-electrodes and an addition oE a neutralizing chemica~, the active alkali and sulphidity being thereby determined by means of the reaction heat and changes in the conductivity.
Measuring signals of the different detectors from the diluted sample zone are integrated as a function of time, i.e. the areas of the concentration peaks are calculated, thus directly obtaining the relative concentrations of the sample, when -the analyzer liquor flow is run at a standard rate. If desired, the relative concentrations can be modified into the actual ones, e.g. g/l, by running samples analyzed in a laboratory in order to form a calibration curve.
When the sample zone has advanced in the analyzer into the dilution capillary, washing of the sample line begins immediately. Said valve 5 passes the water upstream through the filter 4 and the condenser 3 and the washing water is discharged -through a valve 14.
The analyzer arrangement according to the invention has the following advantages:
- the sample amount required is small (50 ml), which is of advantage as the dry matter content of such a small sample is low and so the filter can easily be kept clean by a simple counter-current wash.
In industrial test runs, a sinter filter having a diameter of 30 mm has remained completely clean through thousands of analyses.
- complicated dilution devices required by the UV-devices mentioned in literature are not at all necessary. The dilution is effected spontaneously in a long capillary tube under the influence of diffusion.
- the measurements are completely independent ., , ' ' ., ,.:,.:: .: .
`' ` '~
:~` `''`'' ~: ' ~: :'' :.
; ` :
,'' ~ : .
~,'2~60~i of shiftings of the zero points of the measuring devices, because only a difference caused by the sample zone is measured and there is always returned to the zero point between the measurements, whatever it may be.
- the measuring devices remain almost clean, because the sample is very diluted and a pure measuring medium flows between the samples.
- all measuring conditions are made accurately constant by maintaining the temperature of the measuring devices and the measuring medium constant.
- by virtue of the integration principle, small variations if the operation of the apparatus or in the shape of the dilution zone do not cause any disturbances.
Example 1 Use of the analyzer apparatus for observing a plant-scale sulphate batch pulping process in accordance with the invention.
An industrial sulphate batch digester was observed by means of the analyzer apparatus of Figure 1 with sampling intervals of 10 minutes by taking a sample from the delivery-side of a calorisator pump of the digester. The volume of the digester was 180 cm3, the wood species was pine, the alkali charge 21~
calculated on the amount of wood, the sulphidity being 30~ and the digesting temperature 170C. In the apparatus of Figure 1, the flowing liquid of the analyzer was pure water; a hose pump was used as a liquid flow source 8; the flow rate was ~ ml/min, the volume of the sampling loop 7 was 25 /ul, the length of the diffusion dilution capillary 9 was 5 m and the diameter therof 0.8 mm. The UV-detector 10 was a Knauer*UV/VIS Photometer, the wave length being 280 nm; the refxaction index detector was a Knauer Differential Refractometer; and the conductivity *Trade Mark , , .. :
.. '~. ... :' ~ ~ , ' . - .: , ~ ' ~ ' '' : ' - . ` :
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detector a Vydac*Conductivity Detector. The electrical signals of the detectors were integrated by means of an eight-bit SELMA*-microprocessor and a self-made integrator program. With this way of measuring, the analyzing time for one sample was about four minutes.
Example 2 Use of the analyzer apparatus for observing a plant-scale continuously operated suplhate pulping in accordance with the invention.
The procedure was similar to Example 1 expect that different cycles of a conti~uously operated sulphate digester were observed, said cycles being equalizing, outgoing black liquor, terminating and washing. The analyzer took a sample about every five minutes by moving from one cycle -to another, whereby the analyzing interval of one cycle was 20 minutes. The results appear from Figure 6.
*Trade Mark , ~
,.: ; . .: , : ~ `
".
A method of controlling alkaline pulping by means of a rapid analyzer measuring organic and inorganic cooking liyuor components The invention relates to a method of controlling alkaline pulping processes, especially sulphate pulping, in which method the components dissolved from wood and the recidual inorganic cooking chemical are measured from the process liquors by means of a rapid analyzer apparatus.
The object of the invention was to provide a method of obtaining measuring data on the concentrations of the cooking chemical and the reaction product of alkaline pulping processes at short intervals for controlling the cooking on the basis of the factual proceeding thereof.
: The object of the invention is achieved by feeding a small sample taken from the process into a separate analyzer liquid flow having accurately uniform conditions, in which flow the sample, after having been diluted therein under the influence of diffusion, flows as a peak-shaped zone having a nearly normally distributed concentration through different kind of measuring dP~ices operated on the flow-through principle. Lignin dissolved from wood is measured on the basis of the absorption of the ultraviolet radiation at the wave length of an extreme point (e.g. 205 or 280 nm) of the UV-spectrum of lignin; the total amount of the dry matter dissolved from wood is measured on the basis of the difference in the re~raction index in relation to a pure flowing medium by means of a differential xefractometer; the residual active alkali being measured by a conductivity measurement. In addition, the liquid flow can be passed through any measurement carried out .~ .
' ~ ~
'' ~ .
~.
~26~
on the flow-through principle in order to provide further measurings. Obtaining data from the above-mentioned measurements involves the principle that the alkali concentration measured at the beginning of the cooking and during -the proceeding thereof is used as grounds for set-ting an objective for -the end point of the cooking, the attainment of said objective being then observed and, if required, corrected by means of measurements of the reaction products. In other words, the cooking is here controlled both by means of a "feed forward" control directed forwards and a "feed back" control connected backwards. Both ways of controlling have been suggested to be effected by means of different kinds of direct measurements carried out from the process pipelines or by means of automatic titrators. The novelty of the present invention lies in that the arrangement according to the present method combines all ways of control by providing the necessary data by means of a single apparatus and from one and the same sample. The present measuring tech-nique is particularly advantageous in that the measurements are independent of any changes of the zero point, because there is always returned to the zero between the measurements and there are measured only the differences caused by the sample in the quantity to be measured in relation to time. Further, the measuring devices are not at all liable to become contaminated, as the sample is diluted and a pure measuring medium flows between the samples.
At present, controlling of alkaline pulping processes, sulphate pulping in particular, is based on the fact that it has been possible to develop a ma-thematical model, a so called H-factor, on lignin dissolution occuring during the cooking, said model taking into consideration the cooking chemical charge, ., .
, : , , - :. ,, : :;
,.
; ~,', 6~5 the digestlng temperature and the digesting time, as appears from the publication Rekunen, S., Jutila, E., LXhteenmaki, E., Lonnberg, B., Virkola, N-E., Examination of reaetion kinetics in kraft cooking.
Paperi ja Puu 62 (1980):2, 80-90). Thls kind oE
model operates fairly satisfac-torily, provided that the cooking conditions as well as the quali-ty and humidity of the wood ehips are known. However, this is not usually the ease at any single plant, but the conditions vary at random, and, although important for the process control, such quantities as humidity, quality and particle si~e distribution characteri~ing the raw material, i.e. chips, are left beyond the possibilities of the present measuring techniques.
Attempts have been made to improve the situation by carrying out different kind of measurements from the digester liquors. The amount of the eooking ehemieal or active alkali has been measured either by conduct-ivity measurement directly from a process pipeline system in a manner disclosed in the publication Lundqvist, G., Alkali analysis by conductivity measurements. Svensk Papperstid 76 (1972): 9, 524-527 or by an automatic microprocessor-controlled titration from the cooking liquid sample, which, in turn, is known from ~.S. Patent Specifications 4,104,028 and 4,012,197 as well as from the publication Wallin, G., Noreus, S., Computer control of bateh digesters.
Svensk Papperstid 76 (1973): 9, 329-334. A
disadvantage of a direet eonduetivity measurement, however, is that the proeess pipelines are extremenly liable to ge-t eontaminated, whieh results in slipping of the zero point and diffieulties in the eompensation thereof. Fairly reliable information is obtained on the aetive alkali by means of titrators, whieh, however, are slow and, besides, a single point per process in ~1~2t~ 05 the initial stayes thereof does not yet disclose the profile of the alkali consumption nor the recidual alkali providing perhaps the most important grounds for :Eorward control in view of the determination of the end point.
Attempts have also been made to measure lignin dissolved from wood and to determine the end poin-t of the cooking on said grounds. In particular, the absoxption of the ultraviolet radiation has been used in Kleinert, T.N., Joyce, C. S., Short wawelength ultraviolet absorption of various lignins and related substances. IV lignin determination in sulphate pulping liquor. Pulp and pap.mag.of Can. 58 (1957):
11, 147-152i Williams, D. J., The application of the ultraviolet absorption characteristic of lignin to the control of pulp uniformity. Appita 22 (1968):2, 45-52~ Capart, R., Obese -Dec-ty, K-, Le Cardinal, G., Gelus, M., Contribution to on-like kraft pulping control.
IFAC PRP 4 automation, Ghent, Belgium 1980, p. 121-128.
These methods are greatly disadvantageous in that they are continuously operated, whereby they are difficult to control with respect to contamination and, even the more, with respect to the extensive continuous dilution.
On account of technical difficulties, lignin measurements have not been put to constant use in process controlO Besides, it can be estimated that a mere lignin concentration without any information on the alkali concentration and the properties of the chip filling can not provide a reliable basis for the determination of the end point.
No mention of a combined use of the above-mentioned measurements nor of carrying out the same by a single apparatus and from one and the same sample has been found in literature.
The present invention combines the separate ;
:
: .:. .: . .; , .. .
.' ' '`' ' ' ' `, ' ' ' ' ' ",1 ' . '. ' ', , , ,.-: : .
` '' .,:', . ~
.:.. . ::: .~.
. .: :
determinatiorls mentioned in literature above by means of a novel technique and by elimination of certain previously encountered factors which reduce the reliability of the measuring results, and simultaneously enables in principle an unlimited number of different flow-through measurements to be carried out from one and the same sample.
The following figures are illustrative of the invention: _ Figure 1 illustrates an analyzer apparatus or observing and controlling alkaline cooks, Figure 2 illustrates proceeding of a plant-scale sulphate batch pulping as a function of the digesting time, curve A representing the lignin content, curve B the dry matter content and curve F the residual alkali content Figures 3A and 3B show lignin dissolution curves calculated on the basis of the lignin measuring results of the analyzer, said curves concerning a plant-scale sulphate pulping process as a function of the pulping time, Figures ~A and 4B show a relative alkali concentratlon measured by the analyzer from a plant-scale sulphate batch pulping as a function of an alkali titration carried out in a laboratory, Figure 5 shows a relative dry matter content measured by the analyzer from a plant-scale sulphate batch pulping as a function of a dry matter content determination carried out in a laboratory, Figure 6 illustrates observation of a continuously operated sulphate pulping process, curve D representing the alkali concentration equalizing cycle, curve E the resi~ual alkali concentration in the outgoing black liquor, curve F -the lignin concentration in the outgoing black liquor, ,,j~ ~ .
~ . .
.. .
, ,,, - ' ' "' '"'"'` -~ ~ .
:~ .
.. .
~2~ 5 curve G the lignin concentration in the terminating cycle, curve H the lignin concentration in the washing cycle, curve J the lignin concentration equalizing cycle and curve k kappa number of pulp from digester.
According to Figure 1, a small sample is taken from a process pipeline, e.g. from a delivery-side 1 of a pump (a circulation pump of a batch digester or a circulating pump o~ one cycle of a continuously operated digester) by means of a valve 2, which sample is cooled in a condenser 3 and filtered in a sinter filter 4 and then passed through a normal position of a wash valve 5 to a loop 7 of a loop-injection valve 6. When a necessary amount of the sample, from the point of view of representativeness (with a tube size of 1/8" about 50 ml) 7 has passed through the loop, the injection valve 6 turns over 6~ and a separate liquid flow 8 of the analyzer (a pump or a pressurized liquid container) is conducted through the loop, thus taking therewith a uniform volume (the loop being 25 microliters) of the sample. In the analyzer liquid flow ~usually pure water but also a diluted alkali or an alkalic buffer solution is possible), the sample is diluted in a long capillary tube 9 (5-6 m 0 0.8 rnm teflon capillary) under the influence of diffusion without any artificial dilution steps and the diluted sample zone flows through different kinds of measuring devices: an ultraviolet or UV-detector 10 measuring the lignin concentration of the sample on the basis ~f the absorption of the ultraviolet radiation (205 or 280 nm); a refraction index or RI-detector measuring the dry matter content of the sample on the basis of a difference in the refraction indices; and a conductivity detector measuring the concentration of the residual active alkali on the basis of the conductivity o~ hydroxyl ions. In addition, the flow can be passed throuyh other measurements xx 13 operated : , ,. ~ .
.. ' . . :~
; ' ~ ~ :" . ., , )5 on the flow through principle, such a e.g. ion selective eLectrodes, pH-electrodes and an addition oE a neutralizing chemica~, the active alkali and sulphidity being thereby determined by means of the reaction heat and changes in the conductivity.
Measuring signals of the different detectors from the diluted sample zone are integrated as a function of time, i.e. the areas of the concentration peaks are calculated, thus directly obtaining the relative concentrations of the sample, when -the analyzer liquor flow is run at a standard rate. If desired, the relative concentrations can be modified into the actual ones, e.g. g/l, by running samples analyzed in a laboratory in order to form a calibration curve.
When the sample zone has advanced in the analyzer into the dilution capillary, washing of the sample line begins immediately. Said valve 5 passes the water upstream through the filter 4 and the condenser 3 and the washing water is discharged -through a valve 14.
The analyzer arrangement according to the invention has the following advantages:
- the sample amount required is small (50 ml), which is of advantage as the dry matter content of such a small sample is low and so the filter can easily be kept clean by a simple counter-current wash.
In industrial test runs, a sinter filter having a diameter of 30 mm has remained completely clean through thousands of analyses.
- complicated dilution devices required by the UV-devices mentioned in literature are not at all necessary. The dilution is effected spontaneously in a long capillary tube under the influence of diffusion.
- the measurements are completely independent ., , ' ' ., ,.:,.:: .: .
`' ` '~
:~` `''`'' ~: ' ~: :'' :.
; ` :
,'' ~ : .
~,'2~60~i of shiftings of the zero points of the measuring devices, because only a difference caused by the sample zone is measured and there is always returned to the zero point between the measurements, whatever it may be.
- the measuring devices remain almost clean, because the sample is very diluted and a pure measuring medium flows between the samples.
- all measuring conditions are made accurately constant by maintaining the temperature of the measuring devices and the measuring medium constant.
- by virtue of the integration principle, small variations if the operation of the apparatus or in the shape of the dilution zone do not cause any disturbances.
Example 1 Use of the analyzer apparatus for observing a plant-scale sulphate batch pulping process in accordance with the invention.
An industrial sulphate batch digester was observed by means of the analyzer apparatus of Figure 1 with sampling intervals of 10 minutes by taking a sample from the delivery-side of a calorisator pump of the digester. The volume of the digester was 180 cm3, the wood species was pine, the alkali charge 21~
calculated on the amount of wood, the sulphidity being 30~ and the digesting temperature 170C. In the apparatus of Figure 1, the flowing liquid of the analyzer was pure water; a hose pump was used as a liquid flow source 8; the flow rate was ~ ml/min, the volume of the sampling loop 7 was 25 /ul, the length of the diffusion dilution capillary 9 was 5 m and the diameter therof 0.8 mm. The UV-detector 10 was a Knauer*UV/VIS Photometer, the wave length being 280 nm; the refxaction index detector was a Knauer Differential Refractometer; and the conductivity *Trade Mark , , .. :
.. '~. ... :' ~ ~ , ' . - .: , ~ ' ~ ' '' : ' - . ` :
~2~6C)S
detector a Vydac*Conductivity Detector. The electrical signals of the detectors were integrated by means of an eight-bit SELMA*-microprocessor and a self-made integrator program. With this way of measuring, the analyzing time for one sample was about four minutes.
Example 2 Use of the analyzer apparatus for observing a plant-scale continuously operated suplhate pulping in accordance with the invention.
The procedure was similar to Example 1 expect that different cycles of a conti~uously operated sulphate digester were observed, said cycles being equalizing, outgoing black liquor, terminating and washing. The analyzer took a sample about every five minutes by moving from one cycle -to another, whereby the analyzing interval of one cycle was 20 minutes. The results appear from Figure 6.
*Trade Mark , ~
,.: ; . .: , : ~ `
".
Claims (7)
1. A method for controlling alkaline pulping processes which comprises removing a sample from an alkaline pulping process during operation of said process and collecting said sample in a sample zone, passing a liquid medium provided by an analyzer posi-tioned outside said pulping process through the samp-le zone under pressure thereby spontaneously diluting a uniform volume of said sample by diffusion, conduc-ting said diluted sample through a series of measu-ring devices and adjusting the pulping process in ac-cordance with the measurements of said measuring de-vices.
2. The method of Claim 1 wherein the pulping process is controlled by adjusting the digesting time and temperature and the amount of the active alkali fed into said process.
3. The method of Claim 1 wherein the sample is measured uncontinuously and independently of the zero point of said process.
4. The method according to Claim 1, c h a r a c t e r i z e d in that the process to be control-led is a sulphate batch pulping process.
5. The method according to Claim 1, c h a -r a c t e r i z e d in that the process to be control-led is a continuously operated sulphate pulping pro-cess.
6. The method according to Claim 1, 4 or 5 c h a r a c t e r i z e d in that the liquid medium in the analyzer is water.
7. The method according to Claim 1, 2 or 5 c h a r a c t e r i z e d by using as measuring devi-ces an ultraviolet detector, a refraction index detec-tor and a conductivity detector.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI844419 | 1984-11-09 | ||
| FI844419A FI71960C (en) | 1984-11-09 | 1984-11-09 | Process for controlling alkaline cellulose boiling by a rapid analyzer which measures inorganic and organic boiling liquid components. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1268605A true CA1268605A (en) | 1990-05-08 |
Family
ID=8519875
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000494986A Expired - Lifetime CA1268605A (en) | 1984-11-09 | 1985-11-08 | Method of controlling alkaline pulping by means of a rapid analyzer measuring organic and inorganic cooking liquor components |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS61119791A (en) |
| CA (1) | CA1268605A (en) |
| FI (1) | FI71960C (en) |
| SE (1) | SE459422B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6134952A (en) * | 1997-09-18 | 2000-10-24 | Alberta Research Council Inc. | Dissolved solid analyzer |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0789884B2 (en) * | 1987-03-25 | 1995-10-04 | キッコーマン株式会社 | Method and apparatus for making soy sauce |
| JPH02175996A (en) * | 1988-12-28 | 1990-07-09 | Sanyo Kokusaku Pulp Co Ltd | Raw paper for laminating board and production thereof |
| WO2015037647A1 (en) * | 2013-09-11 | 2015-03-19 | 日本製紙株式会社 | Production method for dissolving kraft pulp |
-
1984
- 1984-11-09 FI FI844419A patent/FI71960C/en not_active IP Right Cessation
-
1985
- 1985-11-08 CA CA000494986A patent/CA1268605A/en not_active Expired - Lifetime
- 1985-11-08 SE SE8505285A patent/SE459422B/en not_active IP Right Cessation
- 1985-11-09 JP JP60251830A patent/JPS61119791A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6134952A (en) * | 1997-09-18 | 2000-10-24 | Alberta Research Council Inc. | Dissolved solid analyzer |
Also Published As
| Publication number | Publication date |
|---|---|
| FI844419L (en) | 1986-05-10 |
| SE459422B (en) | 1989-07-03 |
| JPS61119791A (en) | 1986-06-06 |
| SE8505285L (en) | 1986-05-10 |
| SE8505285D0 (en) | 1985-11-08 |
| FI71960B (en) | 1986-11-28 |
| FI71960C (en) | 1987-03-09 |
| FI844419A0 (en) | 1984-11-09 |
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| LIQUORS | LeClerc et a1. |
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| Date | Code | Title | Description |
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| MKLA | Lapsed |