WO1984004552A1 - Analyseur de carbonate/sulfure et procede de regulation - Google Patents

Analyseur de carbonate/sulfure et procede de regulation Download PDF

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Publication number
WO1984004552A1
WO1984004552A1 PCT/US1984/000739 US8400739W WO8404552A1 WO 1984004552 A1 WO1984004552 A1 WO 1984004552A1 US 8400739 W US8400739 W US 8400739W WO 8404552 A1 WO8404552 A1 WO 8404552A1
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WIPO (PCT)
Prior art keywords
green
uquor
liquor
sodium carbonate
concentration
Prior art date
Application number
PCT/US1984/000739
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English (en)
Inventor
Jerry Robert Speaks
Thomas Franklin Mccall
Ronald Paul Warrick
Original Assignee
Weyerhaeuser Co
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Weyerhaeuser Co filed Critical Weyerhaeuser Co
Publication of WO1984004552A1 publication Critical patent/WO1984004552A1/fr
Priority to FI850235A priority Critical patent/FI850235A0/fi

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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
    • D21C11/00—Regeneration of pulp liquors or effluent waste waters
    • D21C11/0064—Aspects concerning the production and the treatment of green and white liquors, e.g. causticizing green liquor

Definitions

  • the process actually starts with the recovery furnace.
  • the black liquor consisting of organic and inorganic chemicals and water is charged to the furnace where the water is evaporated, the organic components are burned and inorganic components are recovered in the form of a molten smelt.
  • the molten smelt containing mostly sodium carbonate and sodium sulfide is continuously decanted from the furnace bed and dissolved in water
  • a typical green liquor composition is about 60-65% sodium carbonate and 25-28% sodium sulfide by weight (% of solids) expressed as Na.o.
  • a typical solids content of green liquor is around 18% of total liquor weight.
  • the green liquor is pumped from the dissolving tank or tanks to a green liquor clarifier where the dregs settle out.
  • the dregs are impurities, i.e., undissolved solids from the furnace. These are mainly carbon, calcium, magnesium and iron compounds.
  • the green liquor is mixed with reburned lime from the kiln in the slaker. Usually the amount of lime is adjusted to maintain a specified white liquor concentration.
  • Makeup lime in the form of fresh lime (or limestone burned in the kiln) is added to the reburned lime to replace lime losses in the system.
  • Grits large, unreacted lime particles
  • OMPI ⁇ SNAT ⁇ O liquor to form calcium hydroxide and this in turn reacts with the sodium carbonate in the green liquor to form sodium hydroxide and calcium carbonate, which then flows to the causticizing cells.
  • Causticizing cells are used to allow enough time for the causticizing reaction that starts in the slaker to approach completion.
  • the slurry is pumped to the white liquor clarifier (or a pressure filter) to separate the white liquor from the lime mud, calcium carbonate.
  • the clarified white liquor is pumped to storage and then to the digester house to pulp wood chips.
  • the mud or calcium carbonate in the bottom of the clarifier is pumped to a mud washer where it is washed with water from the mud filter and the dregs washer.
  • the overflow water from the mud washer is called weak wash and this is used at the dissolving tank or tanks to dissolve the smelt to form raw green liquor.
  • the causticizing reaction is usually controlled by chemical analysis (titration) of the white liquor taken from a causticizing cell or from the white liquor clarifier overflow.
  • Lime feed, green liquor density at the dissolving tank or tanks or a combination of the two is usually changed to maintain a white liquor strength within a mill's specification.
  • the specifica ⁇ tion is generally expressed as the sodium hydroxide and sodium sulfide concentration in the white liquor, i.e., AA (active alkali) or EA (effective alkali).
  • White liquor AA or EA concentration does vary considerably because of changes in lime availability (CaO content), reactivity (rate of hydration), mass flow rate of lime to the slaker or combinations of these.
  • Sodium carbonate concentration changes in the green liquor feed will also affect the resulting white liquor strength.
  • TTA total titratable alkali
  • TTA is a measurement of sodium hydroxide, sodium carbonate, and sodium sulfide, and is, therefore, only an indirect, approximate determination of the Na 2 CO 3 concentration in the liquor.
  • ABC test colorimetric titration
  • TAPPI test T624 OS-68 Parts 9, 10 and 11
  • Titration end points are not identified by a crisp color change. Rather, there is a gradual change in color, for example, from orange to red or from green to blue depending on which indicator is used. This "diffuse" end point determination results in much uncertainty in the liquor . concentrations which are the only variables which are measured regularly. There have been attempts to solve these problems. Hultman, et al, U.S.
  • Patents 4,236,960 and 4,311,666 describe a different type of process for controlling the degree of causticizion.
  • Sutinan and Haapoja "Causti ⁇ cizing Plant and Lime Kiln Computer Control” describes a Nokia Autolime system.
  • TAPPI test T624 OS-68 describes tests for the analysis of soda and sulfite white and green liquors.
  • Test 12 describes the sodium carbonate (evaluation method) test.
  • the proposed process control logic reduces or eliminates most of the above-mentioned process control problems. It is based on the idea that a kraft mill slaker is really a carbonate reactor, i.e., carbonate ions in the green liquor are crystallized from solution with hydrated lime, and sodium hydroxide is generated in the process. Specifically the causticizing control logic is based on determining the concentration of sodium carbonate and sodium sulfide in the green liquor, in the white liquor-mud slurry at the slaker or first causticizer and in the white liquor being sent to the digester house and using this information to control the entire process. This logic is much different than present practice.
  • the reason for measuring the concentration of sodium sulfide in the green liquor is not to control the slaking/caustieizing process, but to indicate inefficiencies in the process and to take steps to control them.
  • An increase in sulfide concentration will tend to decrease the efficiency of the causticizing reaction.
  • Knowledge of the concentration of sodium sulfide entering the slaker will indicate to the operator or process computer the optimum causticizing efficiency that can be expected from his recausticiz- ing plant.
  • the changes in sulfide concentration will also indicate changes in recovery boiler sodium sulfide reduction efficiency and will allow steps to be taken to better control boiler sodium sulfide reduction efficiency.
  • Variations in the a 2 CO 3 concentration in the liquor at the slaker or causticizer are the result of variations in the concentration and flow rate of lime and green liquor.
  • Lime quality and quantity can be variable and difficult to control - changes in mass flow rate, availability (% CaO) and lime reactivity (how fast hydration occurs) affect the Na ⁇ CO, concentration in the slaker/causticizer liquor, but are extremely difficult to measure and control.
  • the concentration and flow rate of the green liquor may be measured and controlled quite easily.
  • the proposed strategy will control the green liquor flow rate to the slaker to maintain the desired NaippoCO « concentration in the slaker/causticizer liquor despite variations which occur in the lime.
  • the green liquor concentration is also controlled in a control loop.
  • a constant, desired concentration of Na_C0 3 is controlled early in the slaking/causticizing reaction, ensuring safe, efficient operation.
  • the slaking/causticizing process is controlled by adjusting the flow rate and concentration of the green liquor, which is technically quite easy to accomplish. Controlling the concentration, activity, and flow rate of the lime is technically difficult and therefore is allowed to vary within normal limits and the green liquor flow rate is adjusted in response to these variations. This strategy provides much more precise control than do strategies which attempt to adjust lime flow rate in response to changes in liquor flow rate and concentration.
  • This strategy will control the process based on direct measurements of the critical component in the system, sodium carbonate. This provides much more precise control than do strategies based on TTA liquor conductivity, liquor density or other indirect, approximate indications of Na-COq in process liquors.
  • the overall liquor room production rate (amount of white liquor generated per minute) will be controlled by the flow rate of lime to the slaker. As the production rate needs to be increased or decreased in order to maintain an overall mill liquor balance, the flow rate of lime added to the slaker is correspondingly increased or decreased.
  • the green liquor flow rate will be automatically adjusted by a control loop to maintain the desired
  • the last measurement is to determine the concentrations of sodium hydroxide, sodium carbonate, and sodium sulfide in the white liquor which is sent to the digester house to be used in the cooking process. It is important to measure the sodium hydroxide and sodium sulfide
  • OMPI concentrations in the white liquor so that the amount of liquor to be charged in the digester(s) may be correctly determined.
  • Changes in sodium sulfide concentration can affect white liquor AA/EA concentration.
  • the apparatus takes a sample from an appropriate line - green liquor, slaker/causticizer liquor, or white liquor to the digester - filters the sample if necessary, takes a measured quantity, reacts that measured quantity with an acid to generate hydrogen sulfide and carbon dioxide and measures the quantities of these gases in a gas chromatograph.
  • the apparatus has four main circuits: the filter circuit, the sampling circuit, the reactor circuit and the gas chromatograph circuit.
  • a mud separation circuit is also utilized if the apparatus is to analyze liquor from the slaker or causticizing cells. A number of operations or modes are performed in each of these circuits during a test cycle. These modes are sequenced differently depending upon the different operation of the mill.
  • the unit must operate consistently over a long period of time and must give reproducible results.
  • the liquor is corrosive and can also plug lines.
  • the inventors have devised an apparatus which eliminates eorrosion and reduces line plugging to a minimum. This required a great deal of lab and mill testing and redesign to accomplish. During the testing, it was found that the liquor being analyzed, the degree of completion of the reaction and the temperature of the reactive gases would cause changes in the results which would lead to an inability to control the process. Again, a great deal of time and laboratory and mill testing was required before the problem was recognized, the sources of the problem discovered and corrective measures taken.
  • the present apparatus and control logic is the result of several man-years of work extending over a several-year period and the present application represents the inventor's understanding as of the date of the application of the problem and the solution. The work is continuing.
  • Figure 1 is a diagram of the principal components of the test unit.
  • Figure 2 is a diagram of the filter circuit for the apparatus.
  • Figure 3 is a diagram of a three-filter circuit unit for the apparatus when operating in a three-component configuration.
  • Figure 4 is a diagram of the mud separation circuit.
  • Figure 5 is a cross-sectional view of the reactor for the apparatus.
  • Figure 6 is a top plan view of the reactor for the apparatus.
  • Figure 7 is an interior side plan view partially in cross section showing the magnetic spin bar driver and the spin bar in the reactor chamber.
  • Figure 8 is a cross-sectional view along line 8-8 of Figure 7.
  • Figure 9 is a plot of a gas chromatograph voltage output over the course of gas analysis resulting from a typical green liquor sample.
  • Figure 10 is a schematic diagram of a data collection circuit.
  • Figure 11 is a diagram of a single loop apparatus in a pulp mill.
  • Figure 12 is a diagram of a double loop apparatus in a pulp mill.
  • Figure 13 is a diagram of a triple loop apparatus in a pulp mill.
  • Figure 14 is a diagram of a cascaded control.
  • the apparatus has four main circuits: the filter circuit, the sampling circuit, the reactor circuit and the gas chromatograph circuit.
  • a mud separation circuit is also used if the apparatus is to be utilized to analyze liquor from the slaker or causticizing cells.
  • Each of these circuits has a number of operations or modes which are performed during one test cycle. These modes are sequenced differently depending upon the particular operation of a mill. The parts and modes will be described for each of the circuits. A possible sequence will then be described. It should be noted that most of the operable valves throughout the unit are two-position valves. This is for ease and simplicity of operation. Three-position valves or multiple port valves are used in several specific applications. Where so used, the use of these valves is noted.
  • Filter Circuit The purpose of the filter circuit is to remove particulate material from the liquor to prevent both the plugging of the test equipment and the chemical side reactions that would mask the true composition of the liquor.
  • the following description is directed to the filter circuit of Figures 2 and 3.
  • Each of the filter circuits in the three circuit array shown in Figure 3 would have the same parts and operating sequence, so the same reference numerals will be used for the individual elements in these circuits.
  • the circuit has the following components: Major components F - Filter. FS - Filter shock dome. Lines
  • ML - Mill liquor line in the causticizing system between the green liquor clarifier and the slaker, between the slaker and first causticizer, between the first and second causticizers or between the clear white liquor storage tank and the digester, depending on the liquor being sampled.
  • L22 Sampling line from the filter outlet line L30A to the sampling circuit.
  • L28 Liquor return line from the filter circuit to the clarifier, slaker or causticizer depending on liquor being sampled.
  • L30 - Filter outlet line from the upper part of the filter F to the liquor return line L28.
  • L30A Filter outlet line from the filter F to the sampling line L22.
  • L30B Filter outlet line from the filter outlet line L30A to the filter backflush line L31.
  • L30C Filter outlet line from the filter outlet line L30B to the liquor return line L28.
  • L31 Filter backflush line from the valve V28 to the filter outlet line L30C.
  • L32 Filter bypass line from the filter circuit inlet line L29 to the liquor return line L28.
  • L33 Air inlet line to the top of the filter shock dome FS.
  • L33A Air inlet line from the air supply to the water backflush line L37.
  • L33B Air and water inlet line between the water backflush line L37 and the top of the filter shock dome FS.
  • V26 Valve in the air inlet line L33A. Two positions: open; closed. V28 - Filter inlet-backflush three-way T valve at juncture of the filter backflush line L31, the filter inlet line L34 and the inlet line L35. Two positions: position one (backflush) (IB) - open to the filter backflush line L31 and the filter backflush outlet line L34, closed to the inlet line L35; position two (filter) (2F) - open to the filter inlet line L34 and the inlet line L35, closed to the filter backflush line L31.
  • IB backflush
  • V23 Check valve in the filter backflush line L31 to prevent flow through the line L31 into the filter F.
  • Pressure valve (open or partially open, manually operable)
  • V20 - Back pressure valve in the filter outlet line L30B to provide pressure in the filter F and to induce preferential flow into the sampling line L22 when the valve V22 is open.
  • Pressure relief valve (normally closed, automatically openable)
  • V27 Pressure relief valve on the filter F. Repair valves (normally open, manually operable) VI 9 - Repair valve in the liquor return line L28. V25 - Repair valve in the filter circuit liquor supply line
  • the filter circuit has several operating modes. Bypass mode (no liquor to filter) (Bypass)
  • the first mode is a liquor bypass mode in which the liquor is taken from the mill liquor line, through the bypass line and returned to the slaker or eausticizer without passing through the ilter. Lines involved
  • L28 Liquor return line from the filter circuit.
  • L29 Liquor supply line from the mill liquor line ML to the filter circuit.
  • L32 Filter bypass line from the filter circuit inlet line L29 to the filter circuit outlet line L28. Valves involved Operating valves/position
  • VI 8 Check valve in the filter outlet line L30B to prevent flow through the line L30 into the filter F.
  • V23 Check valve in the filter backflush line L31 to prevent flow through the line L3I into the filter F. Repair valves
  • the second mode is a liquor filtering mode in which the liquor is taken from the mill liquor line, filtered in the filter F and returned to the return line in order to establish steady state filtering of the liquor.
  • Major components involved are involved
  • F - Filter Lines involved ML - Mill liquor line.
  • L29 - Liquor supply line from the mill liquor line ML to the filter circuit.
  • L30 - Filter outlet line from the upper part of the filter F to the return line L28.
  • a filter cycle is immediately performed to provide a liquor sample for the first reaction.
  • the filter cycle is started at a time determined by an action somewhere else in the system. It can be started by a sequencer output which is energized when a new liquor sample is desired. This could be signaled by completion of filling the acid pump AP2 or opening the valve which applies pressure to the reactor Rl. Time
  • Liquor sampling mode The-4hird-mode s-arliquor ⁇ sampHng mode in which the liquor is taken from the mill liquor line, filtered and sent to the sampling circuit to provide the test sample.
  • the parts, lines, valves and valve positions are the same in this mode as in the second mode, the filter mode, except for the following change.
  • F - Filter Lines involved L22 - Sampling line from the ilter outlet line L30A to the sampling circuit. Valves involved
  • V22 Valve in the sampling line L22/open.
  • Pressure valves V20 - Back pressure valve in the filter outlet line L30B provides back pressure to cause preferential diver ⁇ sion of the filtered liquor into the sampling line L22.
  • the fourth mode is a stop sampling mode which is a pause to allow the sample valve V22 in the sampling circuit to change position.
  • the parts, lines, valves, valve positions and flows are the same as in the second mode - the filter mode.
  • Liquor backflush mode The fifth mode is a liquor backflush mode, in which the liquor is used to backflush or backwash particulate matter in the filter from the filter to the return line. It takes place in two stages. Stage 1 (Backflush 1)
  • stage 1 the filter outlet valve V21 is closed and liquor from the mill liquor line ML fills the filter to the middle of the filter shock dome FS.
  • ML - Mill liquor line ML - Mill liquor line.
  • L29 Liquor supply line from the mill liquor line ML to the filter circuit.
  • L33 Air inlet line to the top of the filter shock dome FS.
  • L34 Filter inlet line from the valve V28 to the bottom of the filter F.
  • V22 Valve in the sampling line L22/closed.
  • V24 Valve in the filter bypass line L32/closed.
  • V26 Valve in the air inlet line L33A/closed.
  • V28 Filter inlet-backflush valve/position two (filter) (2F) - open to the filter inlet line L34 and the inlet line L35, closed to the filter backflush line L31.
  • V29 Valve in the water backflush line L37/closed. Repair valves
  • V25 - Repair valve in the filter circuit liquor supply line L29 V25 - Repair valve in the filter circuit liquor supply line L29.
  • stage 2 air admitted at the top of the filter shock dome FS, drives the liquor through the filter element of the filter F, out the inlet to the filter element, through the filter backflush outlet line
  • L28 Liquor return line from the filter circuit.
  • V22 Valve in the sampling line L22/closed.
  • V24 Valve in the filter bypass line L32/open.
  • V26 Valve in the air inlet line L33A/open.
  • V28 Filter inlet-backflush valve/position one (backflush) (IB) - open to the filter backflush line L31 and the filter backflush outlet line L34, closed to the inlet line L35.
  • V23 Check valve in the backflush line L31 to prevent flow through the line L31 into the filter F.
  • Repair valves VI 9 Repair valve in the filter circuit liquor return line
  • the sixth mode is a water backflush mode in which water is introduced at the top of the filter shock dome FS and washes particulate matter from the filter element, out the bottom of the filter through the filter backflush outlet Une L34, the backflush line L31, the filter outlet line L30C, and the filter circuit Uquor return line L28.
  • the water backflush mode would normally occur in place of a first mode, a bypass mode, and would follow a fifth mode, the liquor backflush mode. It is used any time the filter is excessively dirty with particulate matter.
  • the Uquor supply would normally be turned off.
  • the parts, lines, valves and valve positions are the same as in stage 2 of the fifth mode, stage 2 of the Uquor backflush mode, with the following additions and changes. Lines involved
  • L33B Inlet line from the water backflush line L37 to the top of the filter shock dome FS.
  • L36 Water supply line.
  • L37 Water backflush line from the water supply line L36 to the inlet line L33B. Valves involved
  • Mud separation circuit - slaker/causticizer white liquor It is often desirable for control appUcations to obtain liquor samples directly from the slaker or causticizer for analysis.
  • This liquor contains 8-10% by weight suspended calcium carbonate mud solids, which must be removed prior to analysis.
  • the level of soUds loading present in this liquor is too high to be introduced immediately to the filter circuit since severe plugging of the filter element would result.
  • the purpose of the mud separation unit is to remove the bulk of the soUds from the Uquor and yield a "clear" liquor containing 1% or less suspended mud solids. This "clear" Uquor is filterable and becomes the Uquor supply to the filter circuit.
  • the mud separation unit in no way interferes with subsequent operation of the analyzer system.
  • the filter, sample, reactor, and gas chromatograph circuits operate exactly as they do when no mud separation circuit is utiUzed.
  • the mud separation circuit merely ensures that an acceptable liquor sample is provided to the filter circuit.
  • the best method of mud separation has been found to involve the use of a continuous settUng cone.
  • This device receives unclarified liquor from the slaker or causticizer, separates the mud from the liquor, returns the mud to the slaker or causticizer, and supplies a continuous "clear" liquor supply to the filter circuit.
  • the advantages of this apparatus and method are simplicity, reliabiUty, ease of operation and a fresh, uninterrupted supply of Uquor to the filter circuit so that operation of the filter circuit is not disturbed.
  • the settling cone itself is a nonmechanical thickener of a type commonly used for continuous liquid-solid separations in low volume appli ⁇ cations.
  • the details of the construction and operation of these units are well known and will not be given in detail here, but may be found in Perry, J. H. (Ed.) Chemical Engineers Handbook, 3rd Ed., McGraw-Hill Book Co., Inc. New York, 1950, pp. 940-941.
  • the mud separation unit should be designed for a capacity that wiU deliver a desirable flow of "clear" liquor (approximately 2-3 Uters/minute) to the filter circuit.
  • the following description is of the mud separation circuit shown in Figure 4.
  • the circuit consists of the following components: Major components
  • SP1 Unclarified liquor supply pump from unclarified Uquor supply line L39 to unclarified liquor supply line L40.
  • SP2 Clear liquor supply pump in filter circuit liquor supply line L29.
  • Bl Bustle pipe and launder ring apparatus from settling cone Tl to clear liquor supply line L43.
  • L29 Liquor supply line to the filter circuit.
  • L39 Unclarified liquor supply line from slaker (or causti ⁇ cizer) to unclarified Uquor supply pump SP1.
  • L40 Unclarified liquor supply line from unclarified liquor supply pump SP1 to junction of settUng cone inlet line L41 and settling eone bypass line L42.
  • L41 SettUng cone inlet Une from unclarified liquor supply Une L40 to settUng cone Tl.
  • L42 SettUng cone bypass line from unclarified liquor supply line L40 to slaker (or causticizer) return Une L50.
  • L43 Clear liquor supply line from bustle pipe/launder ring apparatus Bl to junction of clear Uquor tank inlet line L44 and clear liquor tank bypass line L46.
  • L44 Clear liquor tank inlet line from clear liquor supply line L43 to clear Uquor tank T2.
  • L45 Clear liquor tank overflow line from clear liquor tank T2 to clear liquor bypass/overflow Une L48.
  • L46 Clear liquor tank bypass line from clear liquor supply Une L43 to clear Uquor bypass/overflow Une L48.
  • L47 Clear liquor tank outlet line from clear liquor tank T2 to junction of filter circuit Uquor supply Une L29 and clear liquor tank drain line L51.
  • L48 Clear liquor tank bypass/overflow line from junction of clear Uquor tank bypass Une L46 and clear liquor tank overflow line L45 to slaker (causticizer) return line L50.
  • L49 SettUng cone mud discharge line from sett ng cone
  • L51 Clear liquor tank drain line from clear liquor tank outlet line L47 to return Une L50.
  • L52 Water flush line from mill water supply to unclari ⁇ fied Uquor supply line L39. Operating and repair valves (manually operable)
  • the mud separation unit has five modes of operation, these being the normal operating mode, the clear liquor tank bypass mode, the settling cone bypass mode, the circuit shutdown/water flush mode, and the circuit shutdown/standby mode.
  • Normal operating mode The first mode is the normal operating mode. The circuit will normally remain in this mode. The circuit will be removed from this mode only as necessitated by the need for repairs to the mud separation or filter circuits, or upon shutdown of the slaking/causticizing process.
  • Major parts involved Tl - Continuous settling cone.
  • T2 Clear liquor tank.
  • SP1 Unclarified liquor supply pump/on.
  • SP2 Clear liquor supply pump/on.
  • Bl Bustle pipe/launder ring apparatus. Lines involved
  • L43 Clear liquor supply line.
  • L44 Clear quor tank inlet line.
  • V31 - Settling cone bypass valve/closed V31 - Settling cone bypass valve/closed.
  • V32 Clear liquor tank bypass valve/closed (or throttled).
  • V34 Clear liquor tank outlet valve/open.
  • V35 Clear liquor tank drain valve/closed.
  • the time wiU vary.
  • the circuit wiU normally be in this mode, being removed from this mode only for maintenance of this circuit or the filter circuit or upon shutdown of the slaking and causticizing process. Clear Uquor tank bypass mode
  • the second mode is the clear Uquor tank bypass mode. This mode is utilized when it is necessary to stop the flow of clear liquor to the clear liquor tank. This may be necessitated by the need for repairs to this part of the circuit, or by the need for repairs to the filter circuit which require that the flow of clear Uquor to the filter circuit be stopped.
  • Tl Continuous settling cone.
  • T2 Clear liquor tank.
  • SP1 Unclarified liquor supply pump/on.
  • L41 Settling cone inlet line.
  • L43 Clear liquor supply line.
  • L46 Clear liquor tank bypass line.
  • L47 Clear liquor tank outlet line.
  • L48 Clear liquor tank bypass/overflow line.
  • L49 Settling cone mud discharge line.
  • L50 Slaker (or causticizer) return line.
  • L51 Clear Uquor tank drain line.
  • Operating valves/position V30 Settling cone inlet valve/open.
  • V31 Settling cone bypass valve/closed.
  • V32 Clear liquor tank bypass valve/open.
  • V33 Clear liquor tank inlet valve/closed.
  • V34 Clear liquor tank outlet valve/closed
  • V35 Clear liquor tank drain valve/open.
  • V36 Water flush valve/closed.
  • V37 Unclarified liquor supply valve/open.
  • the third mode is the settUng cone bypass mode. This mode is utiUzed when it is necessary to stop operation of the settUng cone in order to repair this part of the circuit. The flow of clear liquor will be interrupted in this mode and there wiU be no sample flow to the filter circuit and analyzer.
  • L40 Unclarified liquor supply line.
  • L42 Settling tank bypass Une.
  • L47 Clear liquor tank outlet line.
  • L50 Slaker or causticizer return line.
  • V30 SettUng tank inlet valve/closed.
  • V31 Settling tank bypass valve/open.
  • V32 Clear liquor tank bypass valve/closed.
  • V33 Clear liquor tank inlet valve/open.
  • V34 Clear liquor supply valve/open.
  • V35 Clear liquor tank drain valve/open.
  • V36 Water flush valve/open.
  • V37 Unclarified liquor supply valve/open.
  • Circuit Shutdown/Water Flush Mode The fourth mode is the circuit shutdown/water flush mode. This mode is used when it is necessary to entirely shut down the circuit for maintenance or in response to a shutdown of the slaking/causticizing process. The flow of unclarified Uquor to the system is stopped and all Unes and major parts are flushed with water to ensure that they are clean and unplugged.
  • Tl Settling cone.
  • T2 Clear liquor tank.
  • SP1 Unclarified liquor supply pump/on.
  • SP2 Clear liquor supply pump/on.
  • L40 Unclarified liquor supply line.
  • L41 Settling tank inlet line.
  • L42 SettUng tank bypass line.
  • L48 Clear liquor tank bypass/overflow line.
  • L49 Settling cone mud discharge line.
  • L50 Return line to slaker or causticizer.
  • L51 Clear liquor tank drain line.
  • L52 Water flush line. Operating valves/position
  • V30 Settling cone inlet valve/open.
  • V31 SettUng cone bypass valve/open.
  • V32 Clear Uquor tank bypass valve/open.
  • V33 Clear liquor tank inlet valve/open.
  • V34 Clear Uquor tank outlet valve/open.
  • V35 Clear Uquor tank drain valve/open.
  • V36 Water flush valve/open.
  • V37 Unclarified liquor supply valve/closed.
  • the fifth mode is the circuit shutdown/standby mode. This mode is used after the circuit has been flushed with water. The circuit is in a "standby" condition and will remain in this condition until restarted.
  • V30 Settling tank inlet valve/open.
  • V31 Settling tank bypass valve/closed.
  • V32 Clear liquor tank bypass valve/closed.
  • V33 Clear Uquor tank inlet valve/open.
  • V34 Clear Uquor supply valve/open.
  • V35 Clear liquor tank drain valve/closed.
  • V36 Water flush valve/closed.
  • V37 Unclarified liquor supply valve/closed.
  • the sample loop obtains a 10 cc sample of the filtered Uquor and the acid pump obtains a 50 cc sample of 10% sulfuric acid by volume (approximately 2.2 N).
  • the acid pump strokes to deliver a full 50 cc of acid but only 40 cc goes to reactor.
  • the rest is left in the sample loop SL2 and is washed out when fresh liquor displaces the acid in the liquor sampling mode.
  • SL2 Sample loop for obtaining a 10 cc filtered liquor sample. It is connected to the ports P5 and P6 of the sample valve V14.
  • API The air piston for operating the piston in the positive displacement acid pump AP2. Two posi ⁇ tions: position one (acid in or f ⁇ U) (IF); position two (acid out or transfer) (2T).
  • AP2 Positive displacement acid pump for obtaining a 50 cc sample of 10% sulfuric acid. Two positions: position one (acid fill and standby) (IF); position two (acid out or transfer) (2T). Lines
  • Vll. L15 Air line from the valve Vll to the port PI of the sample valve V14 for supplying air to move the sample valve VI to position one (sampling) (IS).
  • LI 6 Air line from the valve Vll to the port P2 of the sample valve VI 4 for supplying air to move the sample valve VI 4 to position two (transferring) (2T).
  • L17 Sample line from the port P4 of the sample valve VI 4 to the port R9 of the reactor HI.
  • L19 Acid Une from the acid line L21 to the port P3 of the sample valve V14.
  • L20 Acid supply line from the acid supply to the acid Une L21.
  • L21 Acid line from the juncture of acid Unes L19 and
  • L22 Sample line from the filter system to the port P8 of the sample valve VI 4.
  • L23 Sample line from the port P7 of the sample valve V14 to the sewer.
  • L24 Air line from the valve VI 7 to the inner side of the piston in API to move the piston outwardly to position one (acid fill) (IF).
  • L25 Air line from the valve V17 to the outer side of the piston in API to move the piston inwardly to posi ⁇ tion two (acid transfer) (2T).
  • L26 Air line from the air supply line L27 to the valve
  • Vll - Solenoid operated air valve connecting the air line LI 4 to either the air line LI 5 or the air Une LI 6 to position the sample valve V14.
  • V14 - Air operated sample valve has two operational ports.
  • V17 - Solenoid operated air valve connecting air line L26 to either the air Une L24 or the air Une L25.
  • V12 - Check valve in the sample line L17 prevents material or gas from returning through the Une L17 from the reactor Rl to the sampling circuit.
  • V15 - Check valve in the acid line L19 prevents backflow of acid from LI 9 through L20 into AP2 during the acid pump fiU mode.
  • VI 6 - Cheek valve in the acid supply line L20 prevents backflow of acid through the acid supply line L20 during the acid transfer mode.
  • the sample valve and its associated sample loop receives and holds a measured Uquor sample.
  • the acid system receives and holds a measured amount of acid separate from the liquor sample. These are held until the reactor can accept the sample and the acid.
  • the circuit then transports the sample, followed by the acid, to the reactor Rl. During this latter step, the acid passes through the sample loop SL2. This accomplishes two objectives: (1) the sample is transported to the reactor assembly by the acid and (2) the sample loop is cleaned by the acid during the injection.
  • the sampling circuit has several operating modes. In many of these modes the valving arrangement is the same.
  • An initial acid flush cycle (Modes 1-4) is performed at start-up to ensure that the sample system is clean and filled with acid before sample analysis begins. At start-up, there may 'or may not be a sample in the sample loop depending upon the status of the sample system at shutdown.
  • the first mode is a standby mode in which there is acid or liquor in the sample loop SL2, depending on the status of the sample circuit at shutdown.
  • API Air operated piston for operating the piston in the acid pump/position one (acid fill) (IF).
  • AP2 Acid pump/position one (acid fill) (IF).
  • L24 Air line from the valve V17 to the inner side of the piston in API.
  • L26 Air line from the air supply line L27 to the valve V17.
  • L27 Air supply line.
  • Vll - Solenoid operated air valve/position one (sampling) (IS): connecting the air lines L14 and L15.
  • VI 6 - Cheek valve in the acid supply line L20 holds acid in the acid Unes L20 and L21.
  • AR2 Pressure regulation valve in the air Une L26.
  • AR3 Pressure regulation valve in the air line L14.
  • Sample valve repositioning mode (Reposition 1)
  • the second mode is a sample valve repositioning mode. The sample valve is moved from the sample receiving position to the sample transferring position.
  • API Air operated piston for operating the piston in the acid pump/position one (acid fill) (IF).
  • AP2 Positive displacement acid pump/position one (acid fiU) (IF).
  • V14 Air operated sample valve/position two (transfer ⁇ ring) (2T): connecting the ports P3, P4, P5 and P6.
  • VI 7 Solenoid operated air valve/position one (acid fill) (IF): connecting the air Unes L26 and L25.
  • V15 - Check valve in the acid line L19 holds acid in the
  • AR2 Pressure regulation valve in the air line L26.
  • AR3 Pressure regulation valve in the air line L14. Flow Air L27 through AR3 through L14 through Vll through L16 through P2 into VI 4.
  • the third mode is a transfer mode in which the acid pump forces the 50 cc of acid in the acid pump AP2 through the sample loop SL2 and into the reactor. An initial flushing of the system with acid is performed to ensure that the system is cleaned and filled with acid before sample analysis commences.
  • API Air operated piston for operating the piston in the acid pump/position two (acid transfer) (2T).
  • AP2 Positive displacement acid pump/position two (acid transfer) (2T). Lines involved
  • LI 6 Air line from the valve Vll to the port P2 of the sample valve VI 4.
  • L17 Sample Une from the port P4 of the sample valve V14 to the port R9 of the reactor Rl.
  • LI 9 Acid line from the acid line L21 to the port P3 of the sample valve V14.
  • V12 - Check valve in the sample line L17 prevents the Uquor and acid from returning to the sample circuit once it has entered the reactor.
  • V15 - Check valve in the acid line L19 allows acid to flow from AP2 through L21 through LI 9 into V14..
  • VI 6 - Check valve in the acid line L20 prevents acid from returning to the acid supply system when AP2 transfers the acid.
  • AR2 Pressure regulation valve in the air line L26.
  • AR3 Pressure regulation valve in the air line L14.
  • the fourth mode is a second sample valve repositioning mode to move the sample valve from position two (transferring) to position one (sampling), and to move the acid pump from position two (acid transfer) to position one (acid fiU) to fiU the acid pump with acid and antiflocculant. It is necessary to add antiflocculant to the reaction mixture to prevent flocculation and deposition of sulfur in the reactor. It is best to add a known amount of antiflocculant to each reaction by mixing antiflocculant solution with acid when the acid pump refills.
  • the proportions of acid and antiflocculant drawn into the acid pump AP2 will be such as to ensure a desirable concentration of antiflocculant in the reaction mixture.
  • API Air operated piston for operating the piston in the acid pump/position one (acid fill) (IF).
  • L9 Antiflocculant supply line from antiflocculant storage to acid supply line L20.
  • L14 Air valve from the air supply line to the valve Vll.
  • L15 Air Une from the valve Vll to the port PI of the sample valve V14.
  • L20 Acid supply line from the acid supply to the line
  • L21 L21 - Acid line from the acid supply line L20 to the acid pump AP2.
  • Vll - Solenoid operated air valve/position one (sampling) (IS).
  • the fifth mode is a second standby mode (Standby 2) in which the sample valve waits to receive a sample from the filter circuit. It is identical to the first mode (Standby 1) and will not be given in detail again.
  • Its time is 12 minutes, but may change depending on the operation of a particular system.
  • the sixth mode is a sample collecting mode in which a sample is collected from the filter circuit.
  • API Air operated piston for operating the piston in the acid pump/position one (acid fill) (IF).
  • AP2 Positive displacement acid pump/position one (acid fiU) (IF).
  • L22 Liquor sample line from the filter system to the port P8 of the sample valve V14.
  • L23 Sample line from the port P7 of the sample valve VI 4 to the sewer.
  • L24 Air line from the valve V17 to the inner side of the piston in API.
  • L26 Air Une from the air supply line L27 to the valve
  • Vll - Solenoid operated air valve/position one (sampUng)
  • VI 5 - Check valve in the acid Une LI 9 holds the acid in the Une L19.
  • V16 - Check valve in the acid supply line L20 holds the acid in the Unes L20 and L21.
  • AR2 Pressure regulation valve in the air line L26.
  • AR3 Pressure regulation valve in the air line L14.
  • the seventh mode is a third standby mode (Standby 3) in which the sample circuit waits for the reactor circuit to receive the sample. It is identical to the first and fifth modes (Standby 1 and Standby 2) and wiU not be given in detail.
  • the sample loop is filled with Uquor rather than acid at this stage.
  • the eighth mode is a third sample valve repositioning mode
  • the ninth mode is a second transfer mode (Transfer 2) in which the acid pump forces the 50 cc of acid through the sample loop and into the reactor. This carries the sample into the reactor also. Acid remains in the sample loop to clean the sample loop of any material that may have coated on the tubing during the seventh mode (Standby 3). This acid and the residue wiU be removed from the system during the next sample collecting mode. It is identical in operation to the third mode (Transfer 1) and will not be given in detail.
  • the tenth mode is a fourth repositioning mode (Reposition 4) in which the sample valve V14 is moved from position two (transferring) to position one (sampling) and the acid pump AP2 is filled with acid and antiflocculant. It is identical to the fourth mode (Reposition 2) and its time is the same. Reactor circuit
  • the reactor is shown in Figures 5 and 6 and the reactor circuit is shown in the bottom left hand section of Figure 1.
  • the reactor Rl has a reactor compartment R2 which is defined by a cover member R3, sidewalls R4 and a base R5.
  • the cover member R3 has four ports: R6 for the vent gas from the reactor to the sewer Une, R7 for the wash water to the reactor, R8 both for the reactor gas from the reactor to the gas chromatograph and for gas under pressure to pressurize the reaction chamber, and R9 for the sample and acid to the reactor.
  • the base R5 defines the bottom R10 of the chamber R2.
  • the bottom R10 is sloped toward the central outlet valve V13 so that the reaction chamber R2 may be washed and drained easily after each reaction.
  • the magnetic spin bar R13 provides turbulence and mixing of the reaction mixture.
  • the base R5 rests on a pressure chamber Rll and pressure within the chamber Rll is maintained by the rubber diaphragm R12 between the base R5 and the pressure chamber Rll.
  • the valve V13 drops into its lower position allowing the reaction chamber R2 to be drained.
  • the liquid goes into outlet Une L18 to be sewered or otherwise treated.
  • the reactor circuit has the foUowi ⁇ g components: Major components
  • LI Air line from the valve V10 to the reactor outlet pressure chamber Rll.
  • L2 Line to the gas chromatograph GC.
  • L2A Line between the reactor gas Une L6 and the gas chromatograph GC.
  • L2B Line between the reactor pressurization line L1Q and the Une L2A.
  • L3 Air line between the air supply line L27 and the line Lll.
  • L4 Water supply line between the water supply and the port R7 of the reactor Rl.
  • L5 Vent line from the port R6 of the reactor Rl to the sewer.
  • L6 Reaction gas line from the line L13 to the Une L2A.
  • Lll Connecting line between the air line L3 and the gauge line L12, and the reactor gas Une L6, the air pressure line L8 and the reactor line L13.
  • LI 2 Gauge line between the air Une L3 and the connect ⁇ ing Une Lll, and the gauge protector Gl and the pressure gauge G2.
  • L13 Reactor line between the port R8 of the reactor Rl and the juncture of the reactor gas Une L6, the reactor pressurization line L8 and the connecting
  • V10 - Valve between the air line L14 and the air line LI Two positions: open; closed. Operating valves (air operated)
  • V12 - Check valve in the sample line L17 preventing either the sample, the reaction gas or air from flowing back through the sample line L17.
  • AR1 Pressure regulation valve in the air line LI.
  • AR3 Pressure regulation valve in the air line L14.
  • AR4 Pressure regulation valve in the air line L3.
  • the acid and sample are placed in the reactor and the reaction starts.
  • the reactor is placed under pressure using a precise air pressure regulator. This is important if a direct relationship between gas chromato ⁇ graph output and Uquor concentration is to be obtained.
  • the final reactor pressure should be about 2 psi above the highest total reactor pressure resulting from the sum of aU the partial pressures or the expected components or 26 psi above the ambient pressure. This is to compensate for the" dependence of reactor pressure on Uquor concentration which would provide an incorrect reading if there was no compensation.
  • reaction gas is transferred to the gas chromatograph.
  • the time of transfer must be long enough to obtain a representative sample of gas in the sample loop SLl of the gas chromatograph. This usually requires 40-50 seconds.
  • Standby mode Standby
  • the first mode of the reactor circuit is a standby mode in which the reactor is waiting to receive the sample. It usually occurs only at start ⁇ up.
  • the reactor contains whatever was present in it at shutdown. This can 5 be the old reaction mixture, wash water, etc. Major components involved
  • V4 Valve in the water line L4/closed.
  • V5 Valve in the vent line L5/closed.
  • V6 Valve in the reaction gas line L6/closed.
  • V8 Valve in the air pressure line L8/closed. 20
  • V10 Valve between the air lines L14 and Ll/open.
  • Vent mode (Vent) 30 The second mode is a vent mode.
  • the reactor is vented when the sample valve V14 is repositioned from position one (sampUng) to position two (transferring). This allows the pressure in the reaction chamber to reach atmospheric pressure prior to sample injection.
  • the gas in the reactor contains, at most, minor amounts of carbon dioxide and hydrogen sulfide. 35 Major components involved
  • V3 Valve in the air Une L3/closed.
  • V4 Valve in the water Une L4/closed.
  • V5 Valve in the vent line L5/open.
  • V6 Valve in the reaction gas line L6/closed.
  • V8 Valve in the pressure Une L8/closed.
  • V10 Valve between the air lines L14 and Ll/open to hold the outlet valve VI 3 of the reactor Rl closed.
  • Drain mode Drain
  • the third mode is a reactor drain mode. During the washing cycle the reactor is drained either of reaction products or of wash water. Major components involved
  • L3 Air line from the air supply line L27 to the connecting line Lll.
  • Lll Connecting Une from the air line L3 to the reactor Une LI 3.
  • LI 3 Reactor line from the connecting line Lll to the port R8 of the reactor Rl.
  • L18 Outlet line from the reactor Rl.
  • L27 Air supply line. Valves involved Operating valves/position
  • V10 Valve between the air lines L14 and Ll/elosed to bleed air from the line LI to open the valve V13.
  • VI 3 Outlet valve of the reactor Rl/open to drain the reactor through the outlet line L18.
  • V12 - Check valve in the sample line L17 prevents air from escaping through the sample Une L17.
  • the fourth mode is the reactor fiU mode. During the wash cycle, the reactor is filled with wash water. Major components involved
  • V4 Valve in the water line L4/open.
  • V5 Valve in the vent line L5/open.
  • V6 Valve in the reaction gas line L6/closed.
  • V8 Valve in the air pressure line L8/closed.
  • V10 Valve between the air lines L14 and Ll/open.
  • V12 - Check valve in the sample line L17 prevents air from entering the sample circuit.
  • the sixth mode is the sample transferring mode.
  • the sample is received from the sampling circuit.
  • Major components involved Rl - Reactor.
  • V3 Valve in the air line L3/closed.
  • V4 Valve in the water line L4/elosed.
  • V5 Valve in the vent line L5/closed.
  • V6 Valve in the reaction gas line L6/closed.
  • V8 Valve in the air pressure line L8/closed.
  • V10 Valve between the air lines L14 and Ll/open.
  • V13 Outlet valve from the reactor Rl/elosed.
  • V12 - Check valve in the sample line L17 prevents the sample or reaction gases from returning through line
  • the seventh mode is the reaction mode.
  • the reaction between the acid and the sample takes place in the reaction chamber.
  • reaction 1 There are two stages in the reaction mode, reaction 1 and reaction 2.
  • Reaction 2 is the continuation of reaction 1 after pressure has been appUed to the reaction chamber and is identical to reaction 1.
  • Major components involved are involved
  • V12 - Check valve in the sample line L17 prevents the reaction gas from entering the sample circuit through the sample line LI 7.
  • AR1 Pressure regulation valve in line LI.
  • AR3 Pressure regulation valve in air line L14. Flow Air L27 through AR3 through L14 through V10 through LI through AR1 into Rll to hold VI 3 closed. Time
  • the total time of the reaction is about 15 minutes. It is divided into the two parts before and after pressure is applied.
  • the eighth mode is a pressurization mode. Eleven minutes after the reaction begins, air pressure is appUed through a precise regulator to the reaction chamber to maintain a constant final reactor pressure. It was decided to pressurize 11 minutes into the reaction, because at this time:
  • the time of pressurization may be changed as needed in response to the characteristics of individual reactor systems.
  • the pressurization step was added in response to observations made during the development of the system. In order to make vaUd comparisons among samples, it is necessary to have a constant final gas pressure. If this is not done, then the experience of our experiments will be repeated. In these experiments, the final gas pressure inside the reactor was aUowed to remain at whatever pressure existed due to the release of carbon dioxide and hydrogen sulfide from the reaction. This pressure varied according to the amounts of sodium carbonate and sodium sulfide in the liquor sample. It was observed that, although an increase in sodium carbonate concentration in the Uquor did cause an increase in the carbon dioxide peak area generated by the gas chromatograph, the relationship was not directly proportional.
  • the carbon dioxide peak area was influenced by the amount of Na 2 S in the Uquor, which resulted in erroneous sodium carbonate measurements due to changes in the sodium sulfide concentration in the Uquor.
  • the measurement of sodium sulfide in the Uquor was affected in the same manner. After this was reaUzed, it was decided to adjust the pressure so that there would be the same total moles of gas in the system for each measurement. This can be done by maintaining the reaction gas in the reactor at a constant pressure at the completion of the reaction. The addition of air will act as a diluent, and the total moles of gas wUl remain fixed among a number of samples.
  • sodium carbonate measurements wiU not be affected by the sodium sulfide concentration in the liquor, nor will the sodium sulfide measurements be affected by the sodium carbonate concentration.
  • the measurements of sodium carbonate and sodium sulfide are then used to control the process.
  • L10 Reactor pressurization Une between the reactor pressurization line L8 and the air supply Une L27.
  • Lll Connecting line between the reactor pressurization line L8 and the pressure gauge line L12.
  • L12 Pressure gauge line from the connecting line Lll to the gauge protector Gl and the air pressure gauge G2.
  • V3 Valve in the air line L3/closed.
  • V4 Valve in the water line L4/closed.
  • V5 Valve in the vent line L5/closed.
  • V12 - Check valve in the sample line L17 prevents reac ⁇ tion gases from entering the sample circuit through the sample line.
  • Pressure regulation valves AR1 - Pressure regulation valve in the air line LI
  • AR5 - Pressure regulation valve having a precision of + .02 psi in the reactor pressurization line L10.
  • the ninth mode is the reaction gas transfer mode.
  • the reaction gas is transferred to the gas chromatograph (G.C). This requires enough
  • L2A Line between the reaction gas Une 6 and the gas chromatograph.
  • L6 Reaction gas Une between the reactor Une L13 and the gas chromatograph Une L2A.
  • L13 Reactor Une between the port R8 of the reactor Rl and the reaction gas Une L6.
  • L14 Air line between the air supply line L27 and the valve V10.
  • V5 Valve in the vent line L5/closed.
  • V6 Valve in the reaction gas line L6/open.
  • V8 Valve in the air pressure line L8/closed.
  • V10 Valve between the air lines L14 and Ll/open.
  • VI 3 Outlet valve in the Reactor Rl/closed.
  • V12 - Check valve in the sample line L17 prevents reac ⁇ tion gas from entering the sample circuit through the sample line LI 7.
  • AR1 Pressure regulation valve in the air line LI.
  • AR3 Pressure regulation valve in the air line LI 4.
  • the tenth mode is the stop transfer mode.
  • the reaction gas valve V ⁇ is closed. Time is aUowed for the pressure in the gas chromatograph system to equalize.
  • V3 Valve in the air line L3/closed.
  • V4 Valve in the water line L4/closed.
  • V5 Valve in the vent line L5/closed.
  • V6 Valve in the reaction gas line L6/closed.
  • V8 Valve in the air pressure line L8/closed.
  • V10 Valve between the air lines L14 and Ll/open.
  • VI 3 Outlet valve in the Reactor Rl/closed.
  • V12 - Check valve in the sample line L17 prevents reac- tion gas from entering the sampUng system through the sample Une.
  • the Uquor within the reactor chamber R2 is stirred by the mixing rod R13 within the reactor and resting on the drain valve V13 in the bottom of the reactor.
  • This rod is magnetically coupled with and rotated by the magnetic spin bar driver M2 in chamber Ml.
  • the magnetic spin bar driver is shown in Figures 7 and 8.
  • a powerful horseshoe magnet M3 faces upwardly toward the spin bar R13.
  • the horseshoe magnet M3 is mounted on a rotating plate M4. Any type of mounting may be used. It may be adhered to the plate M4 with epoxy or other type of adhesive. It is shown mounted in an arcuate depression in the upper face of the plate M4.
  • the plate M4 rests on a base M5. Both the rotating plate M4 and the base M5 are shown as being circular in cross section.
  • the base M5 has an upper flat horizontal supporting surface M6 around its periphery.
  • a circular recessed section M7 is within the periphery. The recessed section
  • M7 also has a flat horizontal surface below surface M6 and a vertical side waU that extends from its surface to the supporting surface M6.
  • a circular further recessed section M8 is within section M7.
  • the surface of recessed section M8 is also flat and below the surface of section M7.
  • the section M8 also-has-a vertical side waU that extends from its surface to the surface of section M7.
  • the periphery of the base M5, the periphery of the section M7 and the periphery of the section M8 are concentric.
  • the section M8 holds a nylon and glass ball bearing M9.
  • M4 has a cylindrical shaft M10 that fits and rotates within bearing M9.
  • a motor section Mil of the plate M4 fits and rotates within the recessed section M7 of the base M5. There is a clearance between the motor section Mil and the surfaces of the recessed section M7.
  • the motor section Mil is circular and concentric with both the cylindrical shaft M10 and the outer circular periphery M12 of the plate M5.
  • the periphery M13 of the motor section Mil is broken by equaUy spaced radial slots or indentations M14.
  • An air Une Ml 5 extends through the base M5 below the recessed section M8.
  • Two secondary air passages M16 extend from air line M15 angularly upwardly to the surface of the recessed section M7.
  • the outlets of the secondary air passage Ml 6 are aligned with the radial slots Ml 4 to aUow air to impinge against the side walls of the radial slots M14 and rotate the plate M4.
  • the outlets of the secondary air passages Ml 6 are shown as 180° apart and on opposite sides of air line Ml 5.
  • the outlets may be paraUel to a tangent to the periphery of recessed section M7 or be angled toward the periphery.
  • the outlets may be, as shown, near the periphery of recessed section M7.
  • Air from air line L7 passes through line Ml 5 and passages Ml 6 to impinge against the walls of the radial slots M14 to rotate the plate M4.
  • the escaping air from the secondary air passages Ml 6 also acts as a bearing for the plate M5 between the surface M17 of the plate M4 and the supporting surface M6 of the base M5. The air eventually escapes along the surface M6 and out through the gap between the base and the revolving plate.
  • the rotation of plate M4 rotates the magnet M3.
  • the rotating magnet M3 rotates the spin bar R13.
  • the magnetic spin bar drive has the following components and operation:
  • the magnetic spin bar drive may also be turned off and on depending on whether the reactor chamber is f Uled or empty by changing the valve V7 to a solenoid operated on/off valve and operating it on the same cycle as valve VI 0 which controls the outlet valve VI 3 of the reactor. Valves V7 and V10 would open and close together.
  • the green Uquor or white Uquor is reacted with acid to form carbon dioxide and hydrogen sulfide gases.
  • the concentration of these gases is measured in the gas chromatograph.
  • the chromatograph outputs a continuous analog signal corresponding to the flow rate of gas through the detector of the chromatograph. By integrating this signal for the proper time intervals (corresponding to the time of appearance of carbon dioxide and hydrogen sulfide at the detector), the concentrations of carbon dioxide and hydrogen sulfide in the reaction gas are measured.
  • CaUbration of the reactor/gas chromatograph system using liquors of known concentration aUows the carbon dioxide and hydrogen sulfide measurements to be converted directly to a determination of sodium carbonate and sodium sulfide in the Uquor sample.
  • the analysis process takes about four minutes for both carbon dioxide and hydrogen sulfide. It may be necessary to analyze only for carbon dioxide in the green Uquor and causticizer white liquor samples. This would reduce the analysis time for these samples to one and one-half minutes.
  • the gas ehromatograph may be used to successively analyze the reaction gases from a number of reactors. For one slaking/causticizing Une, three Uquor samples should be analyzed, resulting in a three-reactor analyzer system.
  • the valve VI is a four position valve having four inlets from the reactors or other outside sources and one outlet to the gas chromatograph. It cycles through the four positions until is is at the proper position to receive reaction gas from the selected reactor. It requires approximately five seconds to move from one position to the next. Another five seconds is allowed to electronically cheek the position of the valve.
  • mode 1A bypass
  • mode IB gas transfer
  • mode 1C purge
  • position two analyze
  • SLl Sample loop for the gas chromatograph. Lines
  • L2 - Line to the gas chromatograph L2A - Line from the reaction gas line L6 to the gas chromatograph GC.
  • L2B Line from the calibration gas line L7 to the gas chromatograph line L2A.
  • L2C Line from the air pressure line L10 to the gas chromatrograph line L2B.
  • L6 Reaction gas line from the reactor Rl to the gas chromatograph Une L2A.
  • L7 Calibration gas line from the CaUbration gas supply to the gas chromatograph Une L2B.
  • L10 Air pressure line from the air supply line L27 to the gas chromatograph line L2C.
  • L14 Air line from air supply line L27 to air line L53.
  • L27 Air supply line.
  • VI - Valve in the gas chromatograph Une L2A Four positions to bring sample into gas chromatograph: position one (reactor one); position two (reactor two); position three (reactor three); position four (spare).
  • V2 - Valve in the high pressure air Une L2C Two positions: open; closed.
  • V6 - Valve in the reaction gas Une L6 Two positions: open; closed.
  • the gas chromatograph takes a gas sample into the sample loop SLl, analyzes the gas sample, purges the sample from the system and backflushes the system. It then waits for a new sample to be suppUed.
  • the first mode is a standby mode.
  • the gas chromatograph is waiting for a sample from the reactor circuit.
  • VI - Valve in gas chromatograph Une L2A/position four (closed). This is exemplary.
  • the valve may be in any position at start-up. It will depend upon the valve position when the system was shut down.
  • V6 - Valve in the reaction gas Une L6/elosed.
  • V7 - Valve in the calibration gas Une L7/closed.
  • the second mode is a reposition mode (Reposition).
  • the valve VI is repositioned around its four positions until it is Uned up with the right reactor. It moves in the same direction, either clockwise or counter ⁇ clockwise, requiring five seconds to move. An additional five seconds is alloted for the system to check the position of the valve. If its location is not right, it wiU move again and be checked again. This will continue until it is in the right position. The other valves and the gas chromatograph remain as they are.
  • the third mode is a new Standby mode (Standby 2) in which aU the valves remain in their positions until the reactor circuit is ready to transfer a gas sample.
  • the fourth mode is a reaction gas transfer mode.
  • the gas chromatograph is internally valved so that the reaction gas goes through the sample loop and then to the vent to sewer. The time of this transfer is long enough for a representative sample to be received.
  • the initial gas entering the sample loop SLl will usually not be representative of the bulk of gas in the reactor.
  • the lines from the reactor to the gas chromatograph are initially filled with air from the previous air purge mode. Air must be flushed from these lines and the sample loop to ensure a representative sample of reaction gas is obtained. It requires a period of time to obtain a steady state sample in the sample loop. Consequently the time will vary depending on the several factors influencing the gas transfer to the sample loop.
  • These factors may include the arrangement and dimensions of the tubing between the reactor and the sample loop, the sample purge condi- tions, and the conditions of pressure, gas composition, etc. existing in the reactor itself at the time of gas transfer.
  • the time is usually between 40 and 60 seconds.
  • Stop sample mode (Stop)
  • the fifth mode is a stop sampling mode in which the reaction gas he gas chromatograph is stopped and the gas pressure in the sample loop Uowed to equalize with atmospheric pressure.
  • VI - Valve in gas chromatograph line L2A/position one (reactor circuit one).
  • V6 - Valve in reaction gas line L6/closed V7 - Valve in calibration gas line L7/closed.
  • the sixth mode is an analysis mode in which the sample is analyzed in the gas chromatograph. There is no change in the external circuit. The change is in the internal system of the gas chromatograph. It switches from position two (gas transfer) to position three (analyze). Major components involved
  • V2 - Valve in high pressure air line L2A/closed V6 - Valve in the reaction gas line L6/closed.
  • Sample purge mode The seventh mode is a gas purge mode in which high pressure air is used to purge the sample from the sample loop and the Unes between the sample loop and reactor.
  • L10 to the sample loop SLl Includes Unes L2A, L2B and L2C.
  • L10 - High pressure Une between air supply Une L27 and the gas chromatograph Une L2.
  • VI - Valve in the gas chromatograph Une L2A/position one (reactor circuit one).
  • V2 - Valve in the high pressure air Une L2C/open.
  • the gas chromatograph output circuitry generates voltage "peaks" which correspond to the appearance of each gas component at the detector of the gas chromatograph.
  • the time interval (from the start of the analysis) during which each component (air, carbon dioxide and hydrogen sulfide) wiU pass through the detector is a characteristic of each component gas. This time interval during which each component appears at the detector is very reproducible and is easily estabUshed for each gas.
  • the gas chromatograph output circuitry generates a continuous 0-1 volt analog signal which is proportional to the flow of gas through the detector. During the time interval each component passes through the detector, a voltage "peak" is generated in response to the appearance of the component.
  • Figure 9 is a plot of G.C. voltage output over the course of a gas analysis resulting from a typical green Uquor sample. Each component of the gas sample is identified, and the time interval during which it appears is noted. The voltage "peaks" for each component are easily observed from the figure.
  • the integrated voltage for each component (which is equal to the area under each peak) is proportional to the amount of the component in the gas sample. Furthermore, the carbon dioxide and hydrogen sulfide integrated voltages are proportional to the sodium carbonate and sodium sulfide concentrations in the liquor. The integrated peak areas for CO and H 2 S are therefore a measure of the Na 2 CO 3 and Na 2 S concentrations in the liquor sample.
  • the data coUection circuit enables the carbonate/sulfide analyzer to convert the voltage peaks generated by the gas chromatograph into values which correspond to the concentrations of Na 2 CO 3 and Na 2 S in the liquor.
  • the data coUection circuit consists of the following major components:
  • FIG. 10 A schematic of the data collection circuit is shown in Figure 10.
  • the associated wiring and components needed to Unk the major components are known and are therefore not iUustrated.
  • the CO 2 and H 2 S voltage peaks must be integrated. There are many methods which may be utilized to accomplish the integra ⁇ tion.
  • the preferred method of peak integration is to utilize a voltage-to- frequency converter (VCO) to convert the 0-1 volt G.C. output signal to a 0-10,000 HZ frequency signal.
  • VCO voltage-to- frequency converter
  • the continuous series of electronic pulses thus generated is utilized as input to a digital microcomputer.
  • the time intervals corresponding to the appearance of the CO 2 and H 2 S peaks are programmed into the microcomputer software.
  • the microcomputer counts the total number of pulses generated by the VCO for the peak period.
  • the number of pulses thus counted is a measure of the peak area.
  • the peak area measurements thus obtained for COo and H S are proportional to the concentrations of Na 2 C0 3 and Na 2 S, respectively, in the Uquor sample.
  • the microcomputer furthermore, aUows for calibration of the analyzer by providing the abiUty to convert the pulse count measurements to direct determinations of Na 2 C0 3 and Na 2 S in the Uquor.
  • the pulse count is directly proportional to the concentration of chemical in the Uquor.
  • the measurement of sodium carbonate and sodium sulfide gener ⁇ ated by the carbonate/sulfide analyzer have been observed to be affected by the temperature at which the reaction occurs.
  • the reaction temperature is primarily governed by the temperature inside the analyzer cabinet.
  • the measurements generated by the analyzer vary in direct proportion with the cabinet temperature. As the cabinet temperature increases, the resultant measurements of sodium carbonate and sodium sulfide correspondingly increase. There must be compensation for this phenomena if accurate measurements are to be obtained for aU samples despite reactor tempera ⁇ ture variations.
  • T actual temperature of gas from reactor As an example if the reference temperature is 30°C and the actual temperature is 27°C, then for Na 2 CO 3
  • the temperature measurement system uses a resistance tempera ⁇ ture detector (RTD) mounted inside the cabinet, and a relay which closes to allow the detector to be sampled by the analyzer data coUection system.
  • the relay closes to aUow sampUng of the detector immediately upon completion of the transfer of reactor gases to the gas chromatograph sample chamber. It remains closed for 20 seconds or as needed to obtain an accurate temperature measurement.
  • the RTD signal is converted to a temperature measurement in the data coUection software.
  • a resistance temperature detector has been found to be the best suited temperature measuring device.
  • the detector element exhibits an electrical resistance which varies directly with temperature. This resis ⁇ tance is easily measured electronically and is easily converted to a temperature reading since the calibration of these elements is weU docu- mented.
  • Other devices, such as thermocouples or thermistors, which exhibit electrical properties that vary as a function of temperature could also be utiUzed in this application. Materials of construction
  • the reactor's top and base is constructed of P.V.C. (polyvinyl chloride).
  • the fixture at top of pump is P.V.C.
  • the mounting board for aU solenoids, etc. is P.V.C.
  • the magnetic spin bar driver is P.V.C.
  • the reactor cylinder and the acid pump cyUnder are glass.
  • AU tubing that is in direct contact with acid or the gases is teflon, aU other tubing is nylon.
  • AU fittings that are in direct contact with acid or the gases are nylon.
  • the reactor gas to gas chromatograph and the vent solenoids are teflon.
  • AU check valves are teflon.
  • the sample loop is nylon.
  • the acid pump piston is teflon coated 316 S.S. (stainless steel).
  • the fittings that come into indirect contact with gases or those that are flushed with air or water are 316 S.S. AU fittings, tubing, valves, columns, etc. within the gas chromatograph are 316 S.S.
  • the gas isolation valve mounted on front of gas chromatograph is 316 S.S.
  • the air, water, pressurization and purge solenoids are 304 S.S.
  • AU fittings on the air and water Unes that are on inlet sides of solenoid or regulators are brass.
  • AU regulators are aluminum.
  • the liquor/acid sample valve is Hastalloy C. Operation In an overaU system these circuits would operate together. The precise operation wUl depend upon the miU configuration.
  • a typical operation for one reactor circuit is shown in the foUowing table. In this table, the operating valves, the valve positions - open (O), closed (C) or position (1, 2) -, the change of position (*), and the time are given. For an analyzer utiUzing multiple reactor circuits, the time of start-up of each circuit would be offset so as to result in no overlap of gas chromatograph operation. Otherwise the logic and sequencing for each circuit wiU in general be identical, although minor modifications could be made to each individual reactor circuit in response to differences in liquor strength or other characteristics without adversely affecting the overaU system operation. Table I
  • V14 IS * V4 c
  • Use Figures 11, 12 and 13 are schematic diagrams showing the use of the apparatus in the causticizing system.
  • Control loop 1 seen in Figure 11 discloses the use of the analyzer in controUing the sodium carbonate concentration in the green liquor to the slaker.
  • green liquor from the green liquor clarifier GLC flows through the miU liquor line MLl and is pumped by the green liquor pump GLP to the slaker S. Lime is added to the green liquor at the slaker S.
  • the line L28/29 designates two lines, L29 which carries the Uquor from the miU Uquor line MLl to the reactor system RSI and L28 which returns the Uquor from the reactor system RSI to the miU liquor line
  • Each of the reactor systems - RSI, RS2 and RS3 - includes a filter circuit, a sample circuit and a reactor circuit. These circuits are shown in Figures 1-3.
  • the Une L2 carries the reaction gas from the reactor system RSI to the gas chromatograph/analyzer GC/A in which the gas is analyzed for carbon dioxide (resulting from sodium carbonate in the liquor) and hydrogen sulfide (resulting from sodium sulfide) as described above.
  • the analyzer uses the carbon dioxide analysis, outputs a signal through the control Une CL1 to the controUer which operates the valve V40 to increase or decrease, the amount of weak wash flowing through line L40 into MLl in order to maintain a constant sodium carbonate concentration in the green Uquor going to the slaker.
  • the hydrogen sulfide analysis has several uses. It is an indication of the reduction efficiency in the recovery boiler.
  • the sodium sulfide concentration can be given to the recovery boiler operator to confirm to him that the reduction efficiency is good or to aUow him to make corrections to improve the reduction efficiency. It is also an indication of the potential efficiency in the causticizing operation. As the concentration of sodium carbonate or sodium sulfide in the green Uquor increases, the efficiency of the causticizing operation decreases. This wttl give the operator information about the causticizing reaction that the green Uquor is about to undergo and aUow the causticizing operator to take corrective action.
  • the second control loop of this system is shown in Figure 12.
  • This loop controls the balance of green Uquor and Ume, and in fact controls the entire slaking operation.
  • a "clear" liquor sample is taken from the calcium carbonate mud separator at either the slaker or first causticizer.
  • This "clear" Uquid is then filtered to remove aU the remaining calcium carbonate mud.
  • the sodium carbonate-and ⁇ odmnr-sulfide-concentration in this filtered Uquor is then measured in the GC/A from the reaction gas from the second reactor system, RS2.
  • the control loop logic wiU contain a set point for the desired sodium carbonate concentration in the Uquor.
  • the amount of sodium carbonate in the green liquor is controUed by loop 1 as is described above.
  • the amount of this green liquor added to the slaker is controUed by loop 2.
  • the amount of sodium carbonate and sodium sulfide in the white liquor from the first causticizer or slaker is determined by the GC/A from the reaction gases from RS2.
  • a signal, based on the sodium carbonate, is then sent through control Une CL2 to the controUer which operates the valve V41 to increase or decrease the amount of green liquor flowing through MLl into the slaker S.
  • the measurement of the chemical concentrations in the white liquor is taken from the line between the clear white liquor storage tank and the digester or digesters.
  • concentrations of sodium sulfide and sodium carbonate in the white liquor are determined directly by analysis by the GC/A of the reaction gases from the third reaction system, RS3.
  • the amount of sodium hydroxide in the white liquor must be deter- mined indirectly. There are three pieces of information which must be combined to yield the sodium hydroxide concentration in the white Uquor.
  • Na 2 CO 3 leaving with the white liquor is the concentration of NaOH which has been produced in the white liquor due to the causticizing reaction.
  • AU chemical concentrations are expressed on a sodium oxide (Na personallyO) basis.
  • Some sodium hydroxide also enters the system with the green liquor. This sodium hydroxide passes unchanged through the system to the white liquor and must be accounted for.
  • This source of NaOH in the system is relatively stable - a periodic (every eight hour) determination of NaOH in the green liquor may be manually performed by an operator and entered into the analyzer software.
  • the determination of the NaOH in the green Uquor may be performed directly in titration of a green Uquor sample. It may alter ⁇ natively be determined indirectly by titrating the NaOH in the white Uquor.
  • the amount of NaOH in the white Uquor which cannot be accounted for by the amount of NaOH generated in reeaustieizing is the amount of NaOH which has entered with the green Uquor. It is recommended that the NaOH in the green Uquor be determined by the indirect method, which has the advantage of reducing errors caused by time lags in the process.
  • the amount of NaOH associated with the green Uquor is then stored in the microprocessor memory until updated by another titration. This value is used to update each subsequent white liquor sodium hydroxide determination.
  • the analyzer wiU solve the foUowing equation for each succeed ⁇ ing sample to determine the sodium hydroxide concentration in the white Uquor:
  • the carbonate analysis is updated with each sample every 19 minutes.
  • the determination of sodium hydroxide in the green Uquor is updated by manual titration of a green or white Uquor sample when necessary, usually every eight hours.
  • An updated, complete clarified white liquor analysis (determination of sodium hydroxide, sodium sulfide, and sodium carbonate) is provided to the digester operator or digester process computer every 12 to 19 minutes.
  • the system software must also take into consideration the time delays in the slaking, causticizing and clarification operations in order to correctly determine the current NaOH concentration in the white liquor. This wiU determine the amount of chemicals to be added to the digester in order to control the pulping process.
  • these devices provide only indirect measurements of the sodium carbonate concentration - they respond to the concentration of all chemicals in the process stream.
  • the ratio of sodium carbonate to total chemicals in the process stream wiU vary with time, resulting in improper determinations of sodium carbonate concentration and less precise control of the process than could be obtained if sodium carbonate was measured directly.
  • the changes which influence the calibration of these devices in measuring sodium carbonate concentration occur slowly - certainly greater than the 15-20 minute sampUng period generated by the earbonate/sulfide analyzer.
  • the direct measurements of sodium carbonate generated by the earbonate/sulfide analyzer may be used as a set point control input to each primary control device.
  • the main items are the ⁇ Ts oTvTI ⁇ tan DT, the green liquor clarifier GLC, the green liquor pump GLP, the slaker S and the first causticizer Cl.
  • Mill Uquor Une MLl carries green liquor from dissolving tank DT to the green liquor clarifier GLC
  • miU Uquor line ML2 carries green liquor from the green liquor clarifier GLC to the slaker S.
  • the principal weak wash line L42 carries weak wash to lines L40 and L41.
  • the weak wash in Une L41 is used to dissolve the smelt in the dissolving tank DT.
  • the amount of weak wash going to the dissolving tank DT through Une L41 is controUed by valve V41.
  • the amount of weak wash is determined by the density of the green liquor from the dissolving tank DT. This is monitored in miU Une MLl by the density meter DM1.
  • the signal from the density meter DM1 is carried through control line CL1 to the valve controUer CN1.
  • the valve V41 is controUed by CN1 with a signal which passes through control Une CL2. This is a standard local control loop in which a local direct measurement is used to monitor the proeess conditions.
  • Figure 14 also iUustrates the use of local conditions to monitor and control the amount of weak wash entering ML2 to maintain the carbonate level in the green Uquor. However, in this instance the gas chromatograph/analyzer is used to determine the set points for this loeal control.
  • the valve V40 is used to control the flow of weak wash in Une L40, which is the amount of weak wash which wiU enter the miU Uquor Une ML2.
  • This is monitored locaUy be a density meter DM2 which sends a signal through control Une CL3 to the control unit CN2.
  • CN2 operates the control valve V40 to increase or decrease the flow of weak wash to maintain the density in ML2 at a specified level.
  • the density of the liquor is not a direct indication of sodium carbonate in the liquor.
  • a sample of the density-controUed Uquor from ML2 is taken and analyzed for sodium carbonate concentration by reactor system RSI and the gas chromatograph/analyzer unit GC/A. This direct determination of sodium carbonate is utilized to send a set point signal through control line CLS to CN2 in order to adjust the density set point so that the density more accurately reflects the sodium carbonate concentration in the liquor.

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  • Paper (AREA)
  • Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)

Abstract

Procédé et appareil de mesure de concentrations de carbonate et de sulfure dans des liqueurs de pulpes blanche et verte et dans des cellules d'extinction/caustification (S, C1) et de régulation de la réaction de caustification et autres étapes utilisant cette information. D'une manière spécifique, la logique de régulation de la caustification est basée sur la détermination de la concentration du carbonate de sodium et du sulfure de sodium (GC/A) dans la liqueur verte, dans la boue-liqueur blanche au niveau de l'extincteur ou du premier caustificateur (ML3) ainsi que dans la liqueur blanche envoyée au digesteur et utilisant cette information pour réguler le procédé dans son ensemble. La concentration et le débit de liqueur verte peuvent être mesurés et régulés très facilement. La stratégie proposée consiste à effectuer la régulation du débit de liqueur verte (V41) passant par l'extincteur pour maintenir la concentration de Na2CO3 désirée dans la liqueur d'extinction/caustification en dépit des variations se produisant dans la chaux. La concentration de liqueur verte est également régulée dans une boucle de régulation. De la liqueur appauvrie de lavage (L40) est ajoutée à la liqueur verte pour maintenir la concentration de Na2CO3 dans la liqueur verte. Le procédé d'extinction/caustification est régulé en ajustant le débit et la concentration de liqueur verte. Cette stratégie permet de réguler le procédé en se basant sur des mesures directes du composant critique dans le système, à savoir le carbonate de sodium. Le débit de liqueur verte est automatiquement réglé par une boucle de régulation pour maintenir la concentration désirée de Na2CO3 dans la liqueur blanche. La dernière mesure consiste à déterminer les concentrations d'hydroxyde de sodium, de carbonate de sodium et de sulfure de sodium dans la liqueur blanche qui est envoyée au digesteur pour l'utiliser dans le processus de cuisson. Il est important de mesurer les concentrations d'hydroxyde de sodium et de sulfure de sodium dans la liqueur blanche (RS3, GC/A) de sorte que la quantité de liqueur à charger dans le(s) digesteur(s) puissent être déterminées de manière correcte. Des changements de concentration du sulfure de sodium (se produisant au niveau de la chaudière de récupération) peuvent affecter la concentration de liqueur blanche (AA/EA).
PCT/US1984/000739 1983-05-18 1984-05-16 Analyseur de carbonate/sulfure et procede de regulation WO1984004552A1 (fr)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0524743A1 (fr) * 1991-07-22 1993-01-27 The Foxboro Company Procédé pour contrôler la concentration de carbonate de sodium de la liqueur verte dans le réservoir de dissolution
EP0947625A1 (fr) * 1998-03-31 1999-10-06 Siemens Aktiengesellschaft Procédé et appareil de contrÔle et l'optimisation du procédé de la récupération des substances chimiques pendant la production de cellulose
WO2001088257A1 (fr) * 2000-05-14 2001-11-22 U.S. Borax Inc. Techniques d'analyse de lessives de cuisson alcalines contenant du bore
WO2003057980A1 (fr) * 2002-01-14 2003-07-17 L'air Liquide - Societe Anonyme A Directoire Et Conseil De Surveillance Pour L'etude Et L'exploitation Des Procedes Georges Claude Procedes de mesure de polysulfure dans lesquels des techniques colorimetriques sont utilisees
US10385513B2 (en) 2016-09-16 2019-08-20 Valmet Automation Oy Method and a system for quality optimization of green liquor

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04119186A (ja) * 1990-09-03 1992-04-20 Sumitomo Heavy Ind Ltd 苛性化工程の運転制御方法

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US4192708A (en) * 1974-09-05 1980-03-11 Mo Och Domsjo Aktiebolag Method for controlling the addition of active chemical for delignifying and/or bleaching cellulose pulp suspended in a liquor containing chemicals reactive with the delignifying and/or bleaching chemical
US4311666A (en) * 1978-07-18 1982-01-19 Mo Och Domsjo Aktiebolag Apparatus for controlling the degree of causticization in the preparation of white liquor from the chemicals recovered from black liquor

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US4192708A (en) * 1974-09-05 1980-03-11 Mo Och Domsjo Aktiebolag Method for controlling the addition of active chemical for delignifying and/or bleaching cellulose pulp suspended in a liquor containing chemicals reactive with the delignifying and/or bleaching chemical
US4311666A (en) * 1978-07-18 1982-01-19 Mo Och Domsjo Aktiebolag Apparatus for controlling the degree of causticization in the preparation of white liquor from the chemicals recovered from black liquor

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Bumazh. Prom. 24, No. 3:6-11, issued May/June 1949, DENISOV, Principles of the Technological Process of Kraft Liquor Causticization. *
Process ISA Symposium (Meeting Paper), issued October 1975, JACOBI et al, Modeling and Control Kraft Production Systems, see pages 187-202. *
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See also references of EP0148207A4 *

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0524743A1 (fr) * 1991-07-22 1993-01-27 The Foxboro Company Procédé pour contrôler la concentration de carbonate de sodium de la liqueur verte dans le réservoir de dissolution
US5213663A (en) * 1991-07-22 1993-05-25 The Foxboro Company Method for controlling the sodium carbonate concentration of green liquor in the dissolving tank
EP0947625A1 (fr) * 1998-03-31 1999-10-06 Siemens Aktiengesellschaft Procédé et appareil de contrÔle et l'optimisation du procédé de la récupération des substances chimiques pendant la production de cellulose
WO2001088257A1 (fr) * 2000-05-14 2001-11-22 U.S. Borax Inc. Techniques d'analyse de lessives de cuisson alcalines contenant du bore
US6635147B1 (en) 2000-05-14 2003-10-21 U.S. Borax Inc. Method for analyzing boron-containing alkaline pulping liquors
US6913672B2 (en) 2000-05-14 2005-07-05 U.S. Borax Inc. Methods for analyzing boron-containing alkaline pulping liquors
AU2001259769B2 (en) * 2000-05-14 2005-10-06 U.S. Borax Inc. Methods for analyzing boron-containing alkaline pulping liquors
WO2003057980A1 (fr) * 2002-01-14 2003-07-17 L'air Liquide - Societe Anonyme A Directoire Et Conseil De Surveillance Pour L'etude Et L'exploitation Des Procedes Georges Claude Procedes de mesure de polysulfure dans lesquels des techniques colorimetriques sont utilisees
US6875414B2 (en) 2002-01-14 2005-04-05 American Air Liquide, Inc. Polysulfide measurement methods using colormetric techniques
US10385513B2 (en) 2016-09-16 2019-08-20 Valmet Automation Oy Method and a system for quality optimization of green liquor

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JPS60501318A (ja) 1985-08-15
FI850235L (fi) 1985-01-18
FI850235A0 (fi) 1985-01-18
NO850160L (no) 1985-01-15
EP0148207A1 (fr) 1985-07-17
EP0148207A4 (fr) 1985-07-30

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