CN102985610B

CN102985610B - Slurry processing method and the system of the cold alkali extraction of lower use is re-used at alkaline filtrate

Info

Publication number: CN102985610B
Application number: CN201080067867.9A
Authority: CN
Inventors: M·M·莱特
Original assignee: Bahia Specialty Cellulose SA
Current assignee: Bahia Specialty Cellulose SA
Priority date: 2010-05-04
Filing date: 2010-08-18
Publication date: 2015-08-12
Anticipated expiration: 2030-08-18
Also published as: PT2567023E; EP2567022A1; ES2525490T3; RU2012151858A; EP2567023A1; AU2010352692B2; RU2523973C1; WO2011138633A1; BRPI1015676A2; CN103003487B; KR101613338B1; KR20130120982A; ES2525263T3; PT2567022E; MY157311A; KR101512550B1; WO2011138634A1; JP2013531139A; EP2567022B1; CN102985610A

Abstract

Slurry processing method comprises cold caustic extraction stage, and the cold caustic solution wherein used and the liquid with the slurry got for elution of mistake are concentrated by vapo(u)rization system.Concentrated liquid can be used as the neutralization in sizing process and boils the part of liquid, thus causes the efficiency of increase, and without starching the remarkable reduction of quality.During the filtrate of carrying out the high enrichment of self cooling caustic extraction stage can contribute to reducing boiling step, hemicellulose is deposited on xylon.

Description

Slurry processing method and the system of the cold alkali extraction of lower use is re-used at alkaline filtrate

Background of invention

1) invention field

Invention field relates generally to slurry processing, relates more specifically to carry out in conjunction with the process of brown paper chemical pulp processes the method and system that self cooling alkali extracts the improvement of the effluent of (caustic extraction).

2) background

Slurry from timber and vegetable material has a large amount of commercial uses.Although one of modal purposes is in papermaking, but slurry also can be used for producing many other products, comprise artificial silk and other synthetic material and cellulose acetate and cellulose esters, its for, such as, filter tow (filter tow), cloth, packing film and explosive is manufactured.

There is many converted timbers and vegetable material to manufacture chemistry and the mechanical means of slurry and paper.Basic procedure of processing comprises preparation raw material (such as, peeling and chopping), to be separated with machinery or chemical means (such as, grind, refining or boiling) xylon with from the cellulose separating lignin of xylon and extract, to be removed colouring agent by bleaching and the slurry of the processing produced formed paper or other products.Except starching and paper manufacture with combination, paper mill also usually has production and reclaims chemical agent, and refuse is removed and processed to collection and processed side product with produce power, and to make to reduce to minimum facility to ambient influnence.

" slurrying (pulping) " is often referred to the process realizing fiber separation.Timber and other vegetable material comprise cellulose, hemicellulose, lignin and other submember.Lignin is the polymer network be dispersed between individual fibers, and serves as iuntercellular adhesive to be bonded together by individual xylon.During pulping process, the large molecule of broken lignin, liberates individual fibers matter fiber thus and dissolves the impurity that paper or other finished product variable color and future can be caused to decompose.

Kraft process is normally used pulping process.Such as, the paper produced from brown paper pulping process can be used, prepare container board and the liner plate of the bleaching used in packaging industry.Traditional kraft process aqueous mixture process timber of the NaOH and vulcanized sodium that are referred to as " caustic lye of soda ".The connection that this process destroys between lignin and cellulose becomes fragment solvable in strong base solution with by most of lignin with part hemicellulose macromolecules degradation.This process that lignin discharges from the cellulose of surrounding is called delignification.After this solvable part is separated from cellulose slurry.

Fig. 1 shows the flow chart of traditional kraft process 100.Method 100 comprises to be put into wood chip (or other contains the raw material of organic slurry) 118 and alkaline solution to realize delignification in the high-pressure reaction vessel being called digester, and this is referred to as " boiling " stage 121.Mixed with caustic lye of soda 111 by wood chip, caustic lye of soda 111 can produce from downstream process or be provided by independent source.Delignification can need several hours, and the degree of delignification be expressed as without unit " the H factor ", this is defined usually, to boil at 100 DEG C the H factor equaling 1 for a hour.Because high temperature, due to the introducing of steam, reaction vessel is usually pressurized.Boiling step nearly at the end of, reaction vessel is reduced to atmospheric pressure, thus released vapour and volatile matter.

The caustic lye of soda used in boiling can be, such as, and the caustic solution containing NaOH (NaOH) and vulcanized sodium (Na2S).The character of caustic lye of soda usually represents with effective alkali (" EA ") and sulphidity (sulfidity).The weight that effective alkali concentration can be calculated as NaOH adds 1/2nd weight of vulcanized sodium, and the NaOH equivalent of representative often liter of liquid, is expressed as gram often liter.Effective alkali carrying capacity represents the NaOH equivalent of every timber stoving weight as NaOH, is expressed as a percentage.Sulphidity is the ratio of 1/2nd weight sums of 1/2nd weight of vulcanized sodium and the weight of NaOH and vulcanized sodium, is expressed as a percentage.

After boiling, the solid fabric chylema of brown---also referred to as " slightly starching "---discharges in the digester used from the boiling stage 121, and then screened in cleaning and screening technology 122 and cleaning.Screening makes slurry with fragment (shive) (wood fiber bundle), ties (wood chip (chip) do not boiled), dirt is separated with other chip (debris).The material be separated with slurry is referred to as " waste material (reject) " sometimes, and slurry is referred to as " good slurry (accept) ".Multistage cascade operation usually keeps the high-purity in good slurry logistics for reducing the amount of cellulose fibre in waste stream.Further fiber recovery realizes by the reprocessing of sieve and knot in downstream refiner or digester.

Then several continuous print wash phase can be carried out to be separated with the liquid that boils crossed with cellulose fibre with the material of dissolving by slightly starching.Boil liquid 112 and the liquid 113 from cleaning and screening technology 122 collection from digester useless used in the boiling stage 121, painted due to them, be usually all referred to as " black liquor ".Black liquor usually containing lignin fragment (fragment), from the carbohydrate of the hemicellulose of fragmentation and inorganic matter.Black liquor can be used for---caustic lye of soda except boiling step---as in such as Fig. 1 as shown in arrow, represent generation in cleaning and screening technology 122 and be transferred to the black liquor 113 in boiling stage 121.If need to obtain suitable alkali concn or in order to other similar purpose, also the black liquor 135 from accumulation tank (not showing in Fig. 1) can be thrown into the digester as boiling stage 121 part.

Then the thick slurry 131 of purification of in the future self-cleaning and screening technology 122 can mix with caustic lye of soda 114 and put into reaction vessel to remove the material of dissolving further as hemicellulose and low molecular weight cellulose.Exemplary separation method is that so-called cold alkali extracts (" CCE ") method, and is represented by the CCE stage of reaction 123 in FIG.Extract affected variable temperatures, but be usually less than 60 DEG C.

Then by from the CCE stage of reaction 123 use reactor purifying slurry 132 with cross cold caustic solution be separated with the hemicellulose of dissolving, and in CCE wash phase 124 second cleaning and separator in wash several times.Brown slurry (the brown pulp) 133 with relatively high chemical cellulose content of the purifying produced, still containing some lignin, proceeds to the downstream bleaching system of further delignification.In some slurry production technologies, bleach and carried out before the CCE stage of reaction 123 and CCE wash phase 124.

In many application, as in the manufacture of synthetic material or medicament, expect to have the slurry of very high-purity or quality.Slurry quality is evaluated by several parameter.Such as, the percentage of chemical cellulose content represents the relative purity of the slurry of processing.The degree of delignification and cellulose degradation is measured respectively by Kappa number (" KN ") and slurry viscosity.The higher slurry viscosity longer cellulosic chain-length of instruction and less degraded.Slurry solubility (" S18 ") in 18wt% sodium hydrate aqueous solution provides the estimation of residual hemicellulose amount.Slurry solubility (" S10 ") in 10wt% sodium hydrate aqueous solution provides the instruction of the total amount of dissolved substance in alkaline solution, and it comprises the cellulose sum of hemicellulose and degraded.Finally, the difference between S10 and S18 determines the cellulosic amount of degrading.

In traditional handicraft, the filtrate 116---also referred to as CCE alkaline filtrate---from CCE cleaning and separation phase 124 comprises by the cold caustic solution crossed and the washing lotion used coming self-cleaning and separation phase 124.This filtrate 116 is usually containing a large amount of macromolecule hemicelluloses.When have hemicellulose content filtrate be used as the boiling stage 121 digester in boil liquid part time, hemicellulose can be precipitated out and be deposited on cellulose fibre from solution.This can stop acquisition high-quality slurry.On the other hand, some application---as the filter tow part that uses in high-quality yarn or synthetic textiles, the material for liquid crystal display, the product be made up of acetate derivative, viscose products (as cotton tyre cord and dedicated fiber), cigarette and some food and medicinal application---needs the slurry of the hemicellulose deposited again containing minimum and chemical cellulose content.

The some parts of CCE alkaline filtrate 116 can re-use in the boiling stage 121, and residue is delivered to recovery area 134 to control the risk that in the boiling stage 121, hemicellulose deposits again.In recovery area 134, the CCE alkaline filtrate 116 of transfer can be mixed with excessive black liquor, concentrated and burn consume organic matter and reclaim inorganic salts in recovery boiler, or take other to another Pulping Line, or the combination of the two.Then new alkali source may be needed replace CCE filtrate and the black liquor of delivering to recovery area 134, to keep soda balance suitable in the boiling stage 121.The recovery process of new alkali source and supply are tending towards the production cost causing increasing.

Exist and cause having the slurry processing method of the dissolving pulp of very high chemical cellulose content and the needs of system.Further existence provides the efficiency of increase and allows effective use of CCE filtrate and the slurry processing method of hemicellulose deposition and the needs of system during minimizing boiling.

Summary of the invention

On the one hand, the pulping process of improvement and system comprise clean the purifying produced from cold alkali extracting method slurry, collect consequent alkaline filtrate, by such as evaporating concentrated alkaline filtrate and utilize alkaline filtrate concentrated at least partly etc. in the boiling method of upstream.

According to one or more embodiment, the pulping process using cold alkali to extract in conjunction with kraft process comprises the following steps with system: the thick slurry that the material of organic slurry is contained in lignification removal in digester, process produces producing semipurified slurry, extract with caustic solution semipurified slurry with the slurry producing purifying and the solution containing hemicellulose, from the slurry of purifying, is separated solution containing hemicellulose, cleans the slurry of purifying and collect consequent alkaline filtrate, concentrated alkaline filtrate and at least part of alkaline filtrate concentrated of utilization in digester.Concentrated alkaline filtrate can be replaced gradually and boil liquid for starting the different of digesting technoloy at first, causes the efficiency increased thus.

In some embodiments, concentrated alkaline filtrate is contained to be formed, and such as, the effective alkali of 90 grams often liter or more is as the solution of NaOH.By utilizing concentrated alkaline filtrate to boil liquid as part, the purity of the slurry of the purifying of thick slurry and generation can be improved.

Other embodiment, alternative and change are also described in this article or show in the accompanying drawings.

Accompanying drawing is sketched

Fig. 1 produces total process chart of the traditional prehydrolyzed kraft sizing process be combined with slurry as known in the art.

Fig. 2 is the process chart of the slurry production technology according to an embodiment as disclosed herein.

Fig. 3 is the system of evaporation and the schematic diagram of related process after extracting according to the cold alkali of the General Principle shown in Fig. 2.

Fig. 4 is traditional system of evaporation and the figure of technique that can be combined with cold alkali extraction etc.

Fig. 5 is the system of filtrate evaporation and the figure of related process extracted from cold alkali according to the General Principle of display in Fig. 2 and 3.

Detailed description of the preferred embodiment

According to one or more embodiment, the method and system of slurry processing comprises the first caustic solution, combine in suitable tank or container (digester) as caustic lye of soda and a large amount of timber or other contain the raw organic material starched, in suitable temperature, such as, boil between 130 and 180 DEG C to produce thick slurry.The cleaning of thick slurry and screening cause semipurified slurry and are thrown the derivative (as black liquor) getting back to digester.Semipurified slurry another caustic solution available (it can be caustic lye of soda again) is in suitable temperature, and such as, less than 60 DEG C are extracted with the slurry producing purifying.By other cleaning, the solution containing hemicellulose can be separated from the slurry of purifying, causes the caustic solution of another alkaline filtrate form, and it can be collected separately and store.This alkaline filtrate by, such as, evaporation or other means concentrate, and alone or combinationally use to process organic material with the first caustic solution in digester and restart circulation.

According to the aspect of one or more embodiment, react in reaction vessel by wood chip or containing other slurry organic with caustic solution.At the end of reaction, reactant mixture contains the cellulose fibre of release.These fibers are extracted with the second caustic solution to dissolve hemicellulose further.Be separated with the caustic solution crossed with the slurry of extraction with the hemicellulose of dissolving, and slurry is cleaned further, remove residual caustic solution and hemicellulose.By the washing lotion containing hemicellulose with the caustic solution mixing of crossing and concentrated, form concentrated CCE filtrate.Then concentrated CCE filtrate can be used alone or combinationally use to process timber in reaction vessel with another caustic solution.

Described above can to carry out with traditional equipment in steps.Follow according to description the CCE filtrate that step described above can cause concentrating, it has the effective alkali concentration being comparable to the caustic lye of soda being generally used for boiling.

Technique according to an embodiment shows in fig. 2.Technique 200 is by the boiling stage 221, in this stage, similar to traditional kraft process, wood chip or other slurry 218 containing organic material is put into and can resist in the digester of high pressure.Digester can have any suitable volume as, such as, about 360 cubic metres.In typical commercial plant, multiple digester can parallel running, and different digesters is in the different stage running of slurry production technology.

The concrete selection of the wood type used in digester or other plant or organic material can be depending on the final products of expectation.Such as, soft wood such as pine tree, Abies and Picea can be used for some derivative techniques and have full-bodied product to obtain, as cellulose ether, (it can be used as, such as, the additive in food, coating, oily withdrawal liquid or mud, paper, cosmetics, medicine, adhesive, printing, agricultural, ceramic, textiles, washing agent and construction material).Hardwood, as eucalyptus and Acacia, those application to the slurry not needing to have very high viscosity may be preferred.

In one embodiment, during the boiling stage 221, with steam or other proper method, digester is heated to the first predetermined temperature.This predetermined temperature can be 110 to 130 DEG C, more specifically, such as, can be 120 DEG C.Heating in this instantiation period between 15 to 60 minutes (such as, 30 minutes) is inner to be completed, although according to the individual cases of equipment and the heat time heating time that just can used other by the character of the organic material heated.

Preferably then by steam or other method, digester is heated to above the second temperature of the first predetermined temperature, for prehydrolysis stage.This second prehydrolysis temperature is preferably about 165 DEG C, although accurate temperature can be depending on the many variablees comprising equipment and organic material again.Heating for prehydrolysis can complete, although again can change as needs heat time heating time in the period of 30 to 120 minutes (such as, 60 minutes).Once reach prehydrolysis temperature, just digester is remained on this constant temperature suitable period, such as, 35 to 45 minutes, or be enough to the At All Other Times any of prehydrolysis.

In a preferred embodiment, neutralization solution 210 is joined the digester as boiling stage 221 part.Neutralization solution 210 can be made up of the freshly prepared caustic lye of soda being black liquor afterwards, or it can be made up of the CCE filtrate being black liquor afterwards.Caustic lye of soda can take such form, such as, and the mixture of NaOH and vulcanized sodium.In a preferred embodiment, caustic lye of soda has often liter of 85 to 150 grams of effective alkalis as NaOH (NaOH), and more preferably often liter of 95 to 125 grams of effective alkalis are as NaOH, and most preferably often liter of 100 to 110 grams of effective alkalis are as NaOH.The sulphidity of caustic lye of soda can be between 10% and 40%, preferably between 15 and 35%, most preferably between 20 and 30%.

In black liquor, effective NaOH concentration can be 10 to 50 grams often liter, although it can change according to concrete technology.In one embodiment, neutralization solution 210 comprises caustic lye of soda and black liquor, and caustic lye of soda has the effective alkali concentration of often liter of 85 to 150 grams of NaOH, and black liquor has the effective alkali concentration of often liter of 20 to 50 grams of NaOH.In a preferred embodiment, the neutralization solution 210 comprising caustic lye of soda and black liquor has the effective alkali concentration being respectively 95 to 125 grams often liter and 30 to 35 grams often liter, more preferably has the valid density being respectively 100 and 110 grams often liter and 38 to 45 grams often liter.Neutralization solution 210 can have effective alkali concentration combination liquid often being risen to 38 to 48 grams of NaOH.

Can a few part maybe can be divided to join in digester disposable for neutralization solution 210 joining in digester.In one embodiment, the neutralization solution 210 points of two parts be made up of caustic lye of soda and black liquor are added, first caustic lye of soda is supplied to digester whereby, adds black liquor afterwards.In one embodiment, neutralization solution 210 is between 130 to 160 DEG C, and the temperature more preferably between 140 to 150 DEG C adds.Add and in the period of 15 to 60 minutes, preferably can carry out in the period of 30 minutes.In a preferred embodiment, neutralization solution 210 points of two parts add, the temperature at every turn in 15 minute period between 140 to 150 DEG C.

Then the replaceable neutralization solution 210 of the first caustic solution 211 and for boiling timber in digester.First caustic solution 211 can have the composition identical with neutralization solution 210, maybe can have different compositions.Scope and the preferable range of NaOH and vulcanized sodium and identical in neutralization solution 210 in first caustic solution 211, and be well-known to those skilled in the art.

Digester is heated to boiling temperature by used vapour or other method.Boiling temperature can be between 140 and 180 DEG C, preferably between 145 to 160 DEG C.Heating can be in period of 10 to 30 minutes or other suitable period.Digester is kept suitable period at boiling temperature, for digesting technoloy, between 15 to 120 minutes.For target H selecting predictors temperature range and digestion time, they are preferably between 130 and 250.

The name that optimization technique is herewith being submitted to simultaneously of neutralization and boiling is called the co-pending U.S. Patent application serial no 12/789 of " method and system (Method and System for High Alpha Dissolving Pulp Production) that high α dissolving pulp is produced ", be described in 307 (attorney docket 161551-0003), this application is transferred to assignee of the present invention, and be merged in by reference at this, be shown entirely as herein.

As the result in boiling stage 221, produce thick slurry 212.Being provided to cleaning and screening technology 222 by slightly starching 212, operating similar to traditional brown paper, so by utilizing dissimilar filter screen or sieve and centrifugal clarification to screen thick slurry 212.Then in screening and cleaning 222,212 are starched with rinsing maching cleaning is thick.Rinsing maching can be any business type, comprises horizontal belt rinsing maching, drum-type washing machine, vacuum filter, washing press (washpresses), compacting baffle filter (compaction baffle filters), air diffuser (atmosphericdiffusers) and pressure diffuser.Cleaning device can use counter-current flow between the stages to starch and move to washings with contrary direction.In one embodiment, the water of pressurization is used for washing thick slurry 212.In another embodiment, the caustic solution of dilution is used for washing thick slurry 212.Dilution caustic solution can, such as, have and be less than often liter of 5 grams of NaOH, be more preferably less than the effective alkali concentration of often liter of 1 gram of NaOH.The washing lotion of collection and in technique 200 other places be used as black liquor 213.In one embodiment, black liquor 213 boils liquid or other caustic solution 211 as the part being supplied to digester in the boiling stage 221.

Then the reactor being pumped into and utilizing in the stage 223 cold alkali extraction (" CCE ") taken out by the semipurified slurry of self-cleaning in the future and screening technology 222 as slurry, method again to traditional is similar, wherein semipurified slurry and the second caustic solution 214 (it can be identical or different with the first caustic solution 211) is mixed being separated further of the cellulose fibre to realize hemicellulose and expectation.It is technique well known in the art that cold alkali extracts.The example of cold alkali treatment system is described in more detail, such as, in the U.S. Patent Application Publication No. 2005/0203291 of the people such as U.S. Patent Application Publication No. 2004/0020854 and Svenson of the people such as Ali, the two is merged in by reference at this, sets forth completely as herein.

Hemicellulose in CCE extraction process 223 is extracted in suitable temperature to carry out, usually between 15 and 50 DEG C, preferably at about 30 DEG C.The pH of slurry is usually above 13, and effective alkali is between often liter of 60 to 90 grams of NaOH.Slurry is immersed in cold caustic solution 214 and continues time enough to diffuse into solution with reaching hemicellulose expected degree.It is 30 minutes in the exemplary time of staying of 30 DEG C of extractions at pH13.Cold alkali extracts the slurry that usually can cause the purifying of the chemical cellulose with 92% to 96% scope content, although reach the upper end of this ratio in history or exceed its quite difficulty, particularly keep other characteristic (as levels of viscosity) expected of starching simultaneously.Reach high-purity keeps high working (machining) efficiency to be also difficult simultaneously.

The caustic solution 214 used in mixing in CCE extraction process 223 and extraction procedure can comprise fresh preparation sodium hydroxide solution, from the byproduct in the recovery of downstream process or slurry or paper-making operation, such as, the caustic lye of soda of half alkaline caustic lye of soda, oxidation and analog.Also can utilize other alkaline solution, as ammonium hydroxide and potassium hydroxide.

The caustic solution 214 used in CCE extraction process 223 can containing suitable hydroxide concentration; Such as, caustic solution 214 can containing by weight 3% to 50% hydroxide concentration, more preferably by weight 6% to 18% hydroxide concentration.Extraction can be carried out in any suitable slurry denseness, as by weight about 2% to 50%, but preferably by weight about 5% to 10%.In this context, term " denseness " refers to the concentration extracting cellulose fibre in mixture.

After the time of staying expected, be separated in the cleaning 224 of starching below with the cold caustic solution crossed.The hemicellulose of extraction is contained with the cold caustic solution crossed.Slurry cleans in CCE cleaning device.Exemplary rinsing maching comprises horizontal belt rinsing maching, drum-type washing machine, vacuum filter, washing press, compacting baffle filter, air diffuser and pressure diffuser.Washing lotion can comprise, such as, and pure water or there is effective alkali concentration, such as, lower than the caustic solution of the dilution of often liter of 1 gram of NaOH.The washing lotion of collection in a conventional manner also mixes to form another kind of caustic solution 216 with the cold caustic solution crossed, and this caustic solution 216, on the one hand, comprises the alkaline filtrate produced by cleaning 224.Therebetween, by extract and cleaning slurry 233 be transported to next stage be used for bleaching.

Preferably the 3rd caustic solution 216 is provided to concentration technology 225, and can, such as, throw into vapo(u)rization system for concentrated.Common vapo(u)rization system can contain device or the effector (effect) of several continuous installation.Liquid is moved by each effector and becomes denseer in the outlet of effector.Vacuum can be utilized to promote the evaporation of solution and to concentrate.

Be connected with concentration technology 225, by, such as, use the evaporation of one or more continuously arranged effector, light black liquor 243 is condensed into dense black liquor 244, during technique, increase the concentration of light black liquor 243 gradually.Dense black liquor 244 can be stored in accumulation tank and to be used for recovery area (recovery boiler) or for other object, therefore exporting byproduct by re-using or circulating and increase efficiency.

Quantity for the effector evaporated depends in part on the concentration level of expectation, the ability of factory and other factors.In one embodiment, the evaporation equipment for enriching stage 225 comprises six and can process, such as, and the effector of 740 tons of liquid per hour.Effector can---but need not---have with for the concentrated type identical from the black liquor in boiling stage 221.Usually, such as, the light black liquor using series of effects device to concentrate to be left from the boiling stage is also stored in holding tank, and it can be recycled for digesting technoloy or other technique of delivering to for different object there.Usually, produce excessive black liquor, excessive black liquor is burnt in the calcining furnace of generating.

In preferred embodiment (as shown in Figure 3), alkalescence from CCE wash phase 224 extract solution 316 concentrated under reduced pressure in six effectors two (in this embodiment, 5th effector 327 and the 6th effector 328) middle generation, concentrated solution 330 is provided, that is, concentrated CCE alkaline filtrate.Light Black Liquor Concentration from the boiling stage 221 is become under high pressure in six effectors four of concentrated black liquor and occur.In this embodiment, light black liquor 313 is incorporated in an effector (in this embodiment, the 4th effector 326), and pumping is used for concentrating further in other downstream effect device 329 after initial concentration.Alkalescence from CCE wash phase 224 extracts solution 316, and the concentrated of---it can be with the washing lotion 314 crossed and the combination with the cold caustic solution 315 crossed---can be provided at the 5th and the 6th effector 327 and 328 at suitable pressures and continue enough duration to reach the concentration of expectation, it is between often liter of about 85 and 110 grams of NaOH in one embodiment, more preferably between often liter of 95 and 105 grams of NaOH.In one embodiment, alkalescence is extracted solution 316 and is remained in the 5th effector 327 under the negative pressure of about-0.84 bar (g), and remain in the 6th effector 328 under the negative pressure of about-0.50 bar (g), there is provided and have, such as, the concentrated solution 330 of the effective alkali concentration between often liter of about 95 and 105 grams of NaOH.

Advantageously, configurable source mill to utilize creationary technique, and does not need a large amount of extraneous expenses of equipment.Utilized such as in factory, when six effectors are used for the concentrated light black liquor be left from the boiling stage, two in effector can redispose, for the alkaline filtrate produced in concentrated CCE cleaning.The effector that can be used for the minimizing number of Black Liquor Concentration is inessential, because although the ability of black liquor vaporizing reduces roughly 20 to 30%, but black liquor quality (final solid concentration) can keep, the black liquor produced from four effectors is allowed to burn recovery boiler, without any significant impact.But, according to the technology of invention described herein, use two in the effector concentrated and circulations for alkaline filtrate, significant impact can be had on plant efficiency.Because the effector of identical number can be used for two different process, factory can be configured to operator and can select in all effectors, use traditional technique for evaporating light black liquor, or can some in partition effect device concentrate for alkaline filtrate, there is no appreciable negative consequences, still in efficiency, provide improvement.

Get back to Fig. 2, all or part of concentrated alkaline filtrate solution 217 can be re-used, boil liquid 211 as neutralization solution 210 and/or as part.In one embodiment, neutralization solution 210 is made up of the alkaline filtrate solution 217 concentrated completely.In another embodiment, neutralization solution 210 comprises concentrated alkaline filtrate solution 217 and caustic lye of soda, and first it can be added in digester, and also optionally for alkaline filtrate solution 217 that enrichment is concentrated.In the 3rd embodiment, concentrated alkaline filtrate solution 217 is as boiling liquid 211.In the 4th embodiment, concentrated alkaline filtrate solution 117 mixes with caustic lye of soda, as boiling liquid 211.

The concentrated alkaline filtrate solution 217 do not re-used in the boiling stage 221 can be used for other object.Such as, it optionally can be turned to other object, as contiguous production line (as caustic lye of soda), as arrow 251 indication in the embodiment of Fig. 2.Meanwhile, concentrated alkaline filtrate solution 217 also can allow to use higher strength of fluid in the boiling stage 221, therefore prevented hemicellulose from depositing on fiber again.

Figure 4 and 5 display and compare the legacy system of the method for evaporating extracted in conjunction with cold alkali and a possible embodiment as disclosed herein.Fig. 4 is the figure of reflection as the legacy system 400 of the method for evaporating that can use together with cold alkali extraction etc.As shown in Figure 4, system 400 comprises many effector 461A-D and 462-466.Received in an effector by light black liquor 413 from digesting technoloy, be the 4th effector 464 in this case, evaporation technology starts there.Pipe 441 and 442 is connected the 4th effector 464 and the 5th effector 465 and the 5th effector 465 and the 6th effector 466 respectively.In the 6th effector 466 after processing, the black liquor that half concentrates is moved on to Intermediate Heat Exchanger 450 and 452.The black liquor that half concentrates is supplied to the 3rd effector 463 from heat exchanger 452, its product is moved on to another Intermediate Heat Exchanger 454.

Then the black liquor that half concentrates is supplied to the second effector 462 (being divided into a main body of two liquid circulating unit " A " and " B ") from heat exchanger 454.In the second effector 462 after evaporation, a part of black liquor is directly pumped into the first effector (inspissator) and other parts are under atmospheric pressure carried out flash distillation in evaporimeter 459 and pumping 432 to ash mixing.First effector physically can be made up of four evaporimeter 461A-D.Evaporimeter can be cast and shell mould falling film evaporator.Four all evaporimeter 461A-D can run simultaneously, and this can allow to produce the black liquor with higher concentration.Liquid containing ash is pumped into evaporimeter 461D from grey mixing channel.In evaporimeter 461D after evaporation, by the flash distillation being stored in the heavy liquid groove (not showing in Fig. 4) of pressurization in flash vessel 459 of the black liquor of concentrated heavy.

The output of vapo(u)rization system 400 is heavy (dense) black liquor 430, and is sent to the condensate 431 of washing lotion bunker.Dense black liquor 430 can be used for previously described object.In condensate tank(trap) 440A, mix from second, third steam condensate with the 4th effector 462,463 and 464, form clean condensate (" A-condensate ") and can flash distillation in several stage, until it stands the pressure similar to the steam inlet pressure of the 6th effector 466.A-collecting condensation be can be used for other places in the clean condensate tank(trap) (the groove A of condensate tank(trap) 440), such as, fiber tracks.

Condensate from the clean side of the 4th and the 5th effector 464 and 465 forms intermediate condensation thing (" B-condensate "), and the instantaneous decline of its pressure or step-down stage by stage, until it has the pressure similar to the inlet pressure of the 6th effector 466.By the B-condensate of flash distillation with from vapo(u)rization system other parts as the process of the primary part from the clean side of the 6th effector 466, the surface condenser 470 of isolation or untreated condensate and/or mix from the condensate of the process of stripper.The condensate of this mixing can contain the comparatively more impurity of A-condensate usually.By B-collecting condensation in intermediate condensation groove (the groove B of condensate tank(trap) 440), and can be used for slurrying production as the other parts in causticizing plant (causticizing plant).

Dirty condensate (" " C-condensate ")---it contains comparatively A-condensate or the more impurity of B-condensate usually---can from the surface condenser Part II of the dirty side of the 5th and the 6th effector 465 and 466, isolation and vacuum system collection.C-condensate is stored in dirty condensate tank(trap) (the C groove of condensate tank(trap) 440).

Fig. 5 is reflection carrys out the system 500 of the filtrate method of evaporating that self cooling alkali extracts figure according to the General Principle of display in Fig. 2 and 3.In this embodiment, system 500 uses the basic equipment identical with the system 400 of Fig. 4 to configure the effector with identical number, although this needs not to be the situation in other embodiment.Dotted line in Fig. 5 shows other connection (comprising pipe and valve), and it can join in the equipment of Fig. 4 to obtain concentrated functional in addition of CCE filtrate.In Figure 5, system 500 has multiple effector 561A-D and 562-566 again.Effector 561A-561D, 562 and 563 plays and effector 461A-D corresponding in Fig. 4,462 general objects identical with 463.But, in the system 500 shown in Figure 5, after light black liquor 513 is concentrated at first in the 4th effector 564, passed through bypass pipe 537 (as the valve 536 that increases control) be supplied to heat exchanger 550 (it is similar to the heat exchanger 450 of Fig. 4 in other side).Like this, light black liquor concentration process walks around the 5th and the 6th effector 565,566.

Different with the system 400 of Fig. 4, in the system 500 of Fig. 5, the cold alkali from CCE cleaning step is extracted (CCE) filtrate 516 and is supplied to the 5th effector 565 by tube connector 541, so the Part I of its experience concentration technology.New valve 538 has been added on Fig. 4 to allow the 4th effector 564 to be separated with CCE filtrate 516.Optional branch's tube connector 539 can be added to connect CCE filtrate 516 and the 6th effector 566, if allowed---, such as, that expects comparatively in a small amount is concentrated---select directly to provide CCE filtrate to the 6th effector 566.In addition, in the 5th effector 565 after evaporation, the CCE filtrate that half concentrates is supplied to the 6th effector 566 by tube connector 542, so it is concentrated to expected degree further by evaporation experience.

Concentrated CCE filtrate 560 can be directed to the groove C in condensate tank(trap) 540 by line 591, or be directed to the groove B of condensate tank(trap) 540 by line 592.Be combined with previously described brown paper procedure of processing, concentrated CCE filtrate 560 can mix with caustic lye of soda, black liquor or other solution as a boiling stage part.If expected, half concentrated CCE filtrate can be delivered to heat exchanger 550 from the 5th effector 565 by the tube connector 535 that another adds, as valve 534 control.Tube connector 535 also provides choice for use five effectors for light Black Liquor Concentration and only single effector (the 6th effector) is concentrated for CCE filtrate.This is configured in the various mixing of boiling and cleaning solution and concentrated aspect provides significant flexibility, etc.In this embodiment that CCE filtrate is concentrated in the 5th and the 6th effector 565 and 566, condensate flow changes by threshold switch: such as, and the dirty side of the 4th effector 564 can be the part of dirty condensate (C-condensate); Condensate from the 6th dirty side of effector 466 can be the part of intermediate condensation thing (B-condensate); With the part that the condensate of primary part of the surface condenser carrying out self-isolation can be clean condensate (A-condensate).

Embodiment

The technique of embodiments of the present invention is described in the examples below.Following methods is used to obtain the analysis result described in embodiment.

Method for measuring S10 and S18 slurry solubility at 25 DEG C is based on TAPPI Standard T235cm-00, is merged in by reference, as illustrated completely in this article at this.NaOH (NaOH) solution of 10% and 18% is used to extract slurry respectively.The carbohydrate dissolved is by measuring with potassium dichromate oxidation.Available hydrogen sodium hydroxide solution extracts the cellulose of low molecular weight carbohydrate as hemicellulose and degraded from slurry.During the solubility of therefore starching in alkali provides slurrying and bleaching process about the information of cellulose degradation and about hemicellulose loss or retain information.In the exemplary program that S10 solubility is measured, the slurry samples that 10 grams dry is placed in beaker and adds 75mL10%NaOH solution to slurry.With dispersal device, mixture is stirred time enough, until slurry is disperseed completely.An example of dispersal device can contain variable-speed motor and the chlamydate stainless steel agitator of tool.Regulate the speed of motor and the angle of blade during churning not have air to be sucked into slurry suspension.After slurry is disperseed completely, another 25mL10%NaOH is joined in mixture to guarantee that all pulp fibres are all covered by alkaline solution.Beaker containing mixture is kept adding 60min NaOH reagent from first time in a water bath in 25 ± 0.2 DEG C.After this time, about 50ml filtrate is collected in clean and dry filter flask.The aliquot of 10.0mL filtrate is mixed in 250mL flask with 10.0mL0.5N potassium bichromate solution.Add the 30mL concentrated sulfuric acid wherein while stirring, in the heating due to chemical reaction of solution this period.Solution is stirred and within 15 minutes, keeps heat simultaneously.Then 50mL water to be joined in mixture and by mixture cool to room temperature.Two to four ferroin indicator are joined in mixture, and with 0.1N l ferrous ammonium sulfate solution titration mixture.10mL10%NaOH solution is used to repeat titration.Utilize formulae discovery S10 solubility below:

S,%=[(V ₂-Vi) ^*N ^*6.85 ^*10]/(A ^*W)

Wherein, Vi is the volume of the l ferrous ammonium sulfate solution for titration filtrate, and unit is milliliter; V ₂also be the volume of the ammonium sulfate of the 10%NaOH solution for titration of straight represented with milliliter, N is the equivalent concentration of l ferrous ammonium sulfate solution; A---unit is milliliter---is the volume using slurry filtrate in oxidation; W is with a gram weight for the oven dry of the slurry samples represented.

The program of S18 solubility test is identical, except 18%NaOH solution substitutes the 10%NaOH solution used above.

Slurry viscosity in cupri ethylene diamine (CED) solution utilizes the method based on SCAN Standard CM15-99 to measure, and the method is merged in by reference, as illustrating completely herein.The method measures the intrinsic viscosity number starched in the CED solution of dilution.In common program, slurry samples is dissolved in CED solution.The intrinsic viscosity number expected is selected to the amount of starching.The slurry samples of weighing is placed in polyethylene bottle (the about 52mL of volume), wherein gets rid of residual air by extruding bottle.5 to 10 sections of copper cash and 25mL deionized water are joined in slurry, and with suitable oscillation device shake mixture, until slurry decomposes completely.The common time interval of decomposing is between 10 to 30 minutes.Another 25.0mL CED solution is joined in mixture.Get rid of after residual air, bottle is covered tightly and again to shake about 30 minutes or until slurry samples dissolves completely.The temperature of testing liquid and viscosimeter is adjusted to 25 DEG C.By drawing, part test solution is drawn onto in test viscosimeter.Measure the delivery time, that is, meniscus marks the time of needs below marking above viscosimeter and dropping to.Equation is below utilized to calculate relative viscosity:

(ηrel) = \frac{F}{Tced} \times T

Wherein, F is the calibration factor of viscosimeter; T _ced---showing with stopwatch---is delivery time of 50%CED solution; T is the delivery time of testing liquid, also shows with stopwatch.Equivalent (η ^*c) value can find in the table appended by SCAN standard, wherein the inherent viscosity of η to be unit the be slurry of mL/g, and c is the concentration of testing liquid, and it is calculated as the volume of slurry dry weight divided by testing liquid, and the volume of testing liquid is 50ML in this embodiment.

Kappa number (KN) utilizes the method similar to TAPPI Standard T236om-99 to measure.KN corresponds to the volume (representing with mL) of the 0.1N liquor potassic permanganate for being oxidized the slurry that a gram dries.In common program, slurry samples is decomposed or is dissolved in about 300ml distilled water.The slurry sample decomposed or dissolve is transferred to beaker and add enough water in pulp mixture, makes the cumulative volume of mixture reach about 795mL.100mL0.1N liquor potassic permanganate and 100mL4N sulfuric acid 4N are mixed in independently beaker, and by mixture quick adjustment to 25 DEG C.Immediately acidifying liquor potassic permanganate is joined in test slurry.After adding, the cumulative volume of mixture is about 1000 ± 5mL.Allow mixture to react ten minutes, after this period, add 20mL1N liquor kalii iodide and react with cancellation.Then immediately by measuring the free-iodine content of mixture with 0.2N sodium thiosulfate solution titrated pulp mixture.Titration end-point is indicated by the starch indicator added at the end of reaction.Do not remove pulp fibres and carry out titration.Another titration is carried out with not having the blank solution starched.Formula is below utilized to carry out calculating K N:

KN=(p ^*f)/w

Wherein p is the amount of the 0.1N potassium permanganate represented with milliliter of test sample consumption; F is the correction factor of 50% permanganate volume and is subordinated to " p ", and it can find in Tappi standard; W is the weight of the oven dry of slurry samples; " p " is measured as follows:

p=[(b-a) ^*N]/0.1

Wherein, b is the amount of the thiosulfate represented with milliliter consumed in titration blank solution; A is the amount of the thiosulfate represented with milliliter consumed in titration slurry samples; N is the equivalent concentration of thiosulfate.

Embodiment 1

The concentration of CCE filtrate

According to the first embodiment, very rare caustic solution stream of often liter of 5.6 grams of NaOH effective alkali concentrations is incorporated in the 5th effector 327 as shown in Figure 3 the behavior observing it with starting drive running and with different alkali enriched levels.With the temperature of decompression between 51.5 DEG C and 56.8 DEG C of-0.73 bar, water is removed from solution.After 4 hours 30 minutes,---similar to former CCE filtrate---caustic solution throws into the 5th effector will to have the effective alkali concentration of often liter of about 50 grams of NaOH, and the 5th effector arrives the outlet of the 6th effector from the entrance filter liquor concentration of often liter of about 50 grams of NaOH.Table I lists as the flow velocity of the function of time, temperature, effective alkali concentration and vacuum level.

Table I

Embodiment 2

Traditional kraft process

According to the second embodiment, in bench scale digester (about 20 liter capacities), carry out tentative kraft process to simulate industrial processes.20 liters of bench scale digester steam are preheated to 120 DEG C in the period of 30 minutes.The eucalyptus wood chip of appropriate amount (as 4.7kg, to dry base) is joined digester.Digester is heated to 165 DEG C in the period of 60 minutes and remains on 165 DEG C and continue other 40 minutes to complete prehydrolysis stage.For traditional kraft process (not using the filtrate from CCE), first caustic lye of soda (" WL1 ") 4.51 liters with the effective alkali concentration of often liter of 124.7g NaOH joined digester in the temperature of 152 DEG C 15 minutes.Common alkali carrying capacity for neutralizing is the NaOH effective alkali (EA) of in dry wood chip weight about 12%.Then 10.8 liters of hot black liquors (" HBL1 ") with the effective alkali concentration of often liter of 25.3g NaOH that temperature digester being filled in 140 DEG C added in 15 minutes are to complete neutralization procedure.By second hot black liquor (" HBL2 ") of decaliter same concentrations the temperature of 146 DEG C join in the period of 23 minutes digester with replace in and liquid, add in the period of 12 minutes 10 bar and 152 DEG C afterwards and boil liquid, by 1.0 liters of hot black liquors, (" HBL2 " and 4.16 liters of mixtures with second caustic lye of soda (" WL2 ") of the effective alkali concentration of often liter of 124.7g NaOH form for it.Usual alkali carrying capacity during boiling is about 11%NaOH effective alkali (EA) in dry wood chip weight.To liquid be boiled with the circulated under pressure 3 minute of the speed of 3 liters per minute at 9.1 bar.Then digester is heated to 160 DEG C in the period of 14 minutes, and remain on 160 DEG C continue another 23 minutes.Then cool digester, and wash reactant mixture twice with the caustic solution of dilution.Each cleaning contains the aqueous solution of often liter of about 0.2g NaOH of solution with 15 liters.The Kappa number of thick slurry display 10.3 produced, the viscosity of 988ml/g, the S10 solubility of 3.6% and 2.7% S18 solubility.Reaction has 39.3% productive rate.When screening, mixture has the waste material (reject) of 0.13%, causes the screening productive rate of 39.1%.

Embodiment 3

Low concentration CCE filtrate is used as neutralization solution and boils liquid

According to the 3rd embodiment, repeat and the identical pulping process described in embodiment 2, except neutralization and the caustic lye of soda in boiling stage substitute with the filtrate (" CCE54 ") with the EA of often liter of 54g NaOH from CCE step.Neutralysate has the pH of 11.0, and cooking mixture has the EoC of often liter of 18.5g NaOH.The P factor of prehydrolysis is 297, and the H factor of cooking reaction is 419.For this embodiment, the total yield effective alkali carrying capacity on timber respectively: in and the NaOH EA of the phase 12% and NaOH EA of boiling phase 11%.

The Kappa number of thick slurry display 10.8 produced, the viscosity of 1118ml/g, the S10 solubility of 4.5% and 3.6% S18 solubility.Reaction has the productive rate of 40.4%.When screening, mixture has the scrap rate of 0.09%, causes the screening productive rate of 40.3%.

Embodiment 4

The CCE filtrate of high enrichment is used as neutralization solution and boils liquid

According to the 4th embodiment, repeat and the identical pulping process described in embodiment 2, WL1 and WL2 except 2/3rds substitutes with the concentrated CCE filtrate of the effective alkali concentration of often liter of 110g NaOH.The Kappa number of thick slurry display 9.5 produced, the viscosity of 990ml/g, the S10 solubility of 4.1% and 3.0% S18 solubility.Reaction has the productive rate of 39.5%.When screening, mixture has the waste material of 0.10%, causes the screening productive rate of 39.43%.

Compared with traditional kraft process, the technique that the caustic lye of soda of 2/3rds is substituted by the CCE filtrate concentrated produces has the viscosity (be in this embodiment about 990mg/l) similar to traditional kraft process and the slurry of Kappa number.Expect that similar technology works in wider scope; Such as, wherein the caustic lye of soda of 60% to 75% is substituted by the CCE filtrate concentrated.Show with the Kappa number low a little that concentrated CCE filtrate obtains: substituting caustic lye of soda with concentrated CCE filtrate does not poorly affect delignification.There is the viscosity of the technique of concentrated CCE filtrate---optionally measure in boiling step---higher (in 104 pairs of traditional handicrafts 96) with the ratio of Kappa number, show to use concentrated CCE filtrate to obtain good boiling selective.

When concentrated CCE filtrate Substitute For Partial caustic lye of soda, S18 solubility is increased to 3.0%, S10 solubility from 2.7% and is increased to about 4.1% from 3.6%, represents that some hemicelluloses deposit generation again.As needs, by other method control S18 solubility level further.

Further by reducing boiling temperature a little to obtain identical Kappa number (about 10.8) and viscosity higher possibility Optimization Technology.Based on different experiments, expect to carry out less change to technique, comprise alkaline level, the relative quantity of caustic lye of soda and concentrated CCE filtrate, boiling temperature and boiling number of times, this can be determined by conventionally calculation or optimization according to based on principle described herein and technology, still the thick slurry quality produced is remained in potential expected range simultaneously.Such as, expect the thick slurry produced can produce less than 10.0 Kappa number, below 1000ml/g viscosity, be no more than the ratio of the S18 solubility of 3.0% and/or the viscosity more than 100 and Kappa number.

According to some embodiment disclosed herein, use concentrated CCE filtrate possibility boiling and the same or analogous viscosity of traditional kraft process and the Kappa number level that only use fresh caustic lye of soda, therefore cause the efficiency increased.

Although there have been described the preferred embodiment of the present invention, the many changes remained in the spirit and scope of the present invention are possible.After having seen description and accompanying drawing, such change will become obvious to those skilled in the art.Therefore, the present invention is unrestricted, except in the spirit and scope of any claims.

Claims

1., for generation of the pulping process that the cold alkali of use of dissolving pulp extracts, comprising:

Lignification removal's organic material in digester, and the thick slurry that process produces is to produce semipurified slurry for generation of dissolving pulp;

Described semipurified slurry is extracted with caustic solution, to produce the slurry of purifying and the solution containing hemicellulose during cold alkali extracting method;

The slurry of described purifying and the washing lotion of collection is thus cleaned be separated the solution containing described hemicellulose from the slurry of described purifying while;

By the described washing lotion crossed with containing the solution combination of described hemicellulose to form alkaline filtrate;

Concentrate the described alkaline filtrate of the washing lotion comprising described mistake and the solution containing described hemicellulose to form concentrated alkaline filtrate; With

In conjunction with the generation of dissolving pulp, in described digester, utilize at least part of described concentrated alkaline filtrate.

2. method according to claim 1, wherein concentrated described alkaline filtrate is undertaken by method of evaporating.

3. method according to claim 2, wherein said method of evaporating carries out in the effector of multiple continuous connection.

4. method according to claim 2, the temperature range of wherein said method of evaporating between 50 and 60 DEG C is carried out.

5. method according to claim 2, wherein said method of evaporating carries out at the pressure of-0.5 bar and-0.84 bar.

6. method according to claim 2, wherein carries out described method of evaporating, until described concentrated alkaline filtrate has the effective alkali concentration between often liter of 95 and 125 grams of NaOH.

7. method according to claim 2, wherein carries out described method of evaporating, until described concentrated alkaline filtrate has the effective alkali concentration between often liter of 100 and 110 grams of NaOH.

8. method according to claim 1, comprises the described concentrated alkaline filtrate being joined in described digester by caustic lye of soda and use further.

9. method according to claim 8, the ratio of wherein said caustic lye of soda and concentrated alkaline filtrate is between 1:1.5 and 1:2.5.

10. method according to claim 1, wherein said caustic solution comprises NaOH and Na ₂s.

11. methods according to claim 3, wherein said method of evaporating carries out at the pressure of-0.84 bar with in the second effector from described first effector downstream at the pressure of-0.5 bar in the first effector.

12. pulping process using cold alkali to extract in kraft process, comprising:

First organic material is boiled to produce thick slurry in digester;

Clean and screen described thick slurry to produce semipurified slurry;

Use cold alkali to extract and extract described semipurified slurry to produce the slurry of purifying and the solution containing hemicellulose;

The slurry of described purifying and the washing lotion of collection is thus cleaned while the slurry being extracted the purifying produced by cold alkali is separated the described solution containing hemicellulose;

In controlled environment, evaporation comprises the described alkaline filtrate of the described washing lotion crossed and the solution containing described hemicellulose to form concentrated caustic solution; With

In conjunction with the generation of dissolving pulp, at least part of described concentrated caustic solution is utilized to boil liquid to boil second batch organic material as at least one.

13. methods according to claim 12, are included in further on different slurry machining production lines and use alkaline filtrate concentrated described in Part II.

14. methods according to claim 12, wherein said method of evaporating carries out in the effector of multiple continuous connection.

15. methods according to claim 12, the temperature range of wherein said method of evaporating between 50 and 60 DEG C is carried out.

16. methods according to claim 12, wherein said method of evaporating carries out at the pressure of-0.5 bar and-0.84 bar.

17. methods according to claim 12, wherein carry out described method of evaporating, until described concentrated caustic solution has the effective alkali concentration between often liter of 95 and 125 grams of NaOH.

18. methods according to claim 12, wherein carry out described method of evaporating, until described concentrated caustic solution has the effective alkali concentration between often liter of 100 and 110 grams of NaOH.

19. methods according to claim 12, comprise the described concentrated caustic solution being joined in described digester by caustic lye of soda and use further.

20. methods according to claim 19, the ratio of wherein said caustic lye of soda and concentrated alkaline filtrate is between 1:1.5 and 1:2.5.

21. methods according to claim 12, the caustic solution wherein extracted for cold alkali comprises NaOH and Na ₂s.

22. methods according to claim 12, further comprising the steps:

Slightly starch by boiling second batch organic material to produce second in described digester;

Clean and screen described second and slightly starch to produce semipurified slurry; With

Use cold alkali to extract, extract from the described second thick described semipurified slurry starched to produce the slurry of the second purifying and the second solution containing hemicellulose.

23. methods according to claim 22, the wherein said second thick slurry had the S18 solubility being no more than 3.0% before cold alkali extracts.

24. methods according to claim 23, the wherein said second thick slurry had the Kappa number being less than 10.0 before cold alkali extracts.

25. methods according to claim 23, the wherein said second thick slurry had the viscosity of 1000 milliliters every gram before cold alkali extracts.

26. methods according to claim 23, wherein said second slightly starches the display viscosity of 100 or higher and the ratio of Kappa number before cold alkali extracts.

27. methods according to claim 14, wherein said method of evaporating carries out at the pressure of-0.84 bar with in the second effector from described first effector downstream at the pressure of-0.5 bar in the first effector.

28. for generation of the pulping process of the improvement using cold alkali to extract in kraft process of dissolving pulp, be included in digester and boil organic material to produce thick slurry, clean and screen described thick slurry to produce slurry, extract with using cold alkali and extract raw slurry to produce the slurry of purifying and the solution containing hemicellulose, described improvement comprises:

The slurry of described purifying and the washing lotion of collection is thus cleaned while the slurry being extracted the described purifying produced by cold alkali is separated the described solution containing hemicellulose;

In conjunction with the generation of dissolving pulp, in utilizing at least part of described concentrated alkaline filtrate to be used in described digester and or boil other organic material.

29. use the extraction of cold alkali for the preparation of the pulping process of dissolving pulp in kraft process, comprising:

Use in multiple batch digestor and boil organic material from the concentrated caustic solution of the cold caustic extraction stage in downstream at least partly, and produce thick slurry thus;

Clean and screen described thick slurry to produce semipurified slurry;

Use cold alkali to extract and extract semipurified slurry to produce the slurry of purifying and the solution containing hemicellulose;

While being separated the described solution containing hemicellulose from the slurry being extracted the described purifying produced by cold alkali

Clean the slurry of described purifying and the washing lotion of collection thus;

In conjunction with the generation of dissolving pulp, at least part of described at least one turning back in described batch digestor of concentrated caustic solution is boiled liquid as at least one.

30. in kraft process for the preparation of the pulping process of dissolving pulp, comprising:

Utilize after comprising the neutralizer of part caustic lye of soda is that second liquid different from it is to neutralize first organic material;

First organic material described is boiled to produce thick slurry in digester;

Clean and screen described thick slurry to produce semipurified slurry;

By the described washing lotion crossed with the solution combination containing described hemicellulose to form alkaline filtrate without the need to from wherein removing described hemi-cellulose components;

Using at least part of described concentrated caustic solution as at least one neutralizer or boil liquid to process second batch organic material for generation of dissolving pulp;

Described second liquid wherein for described neutralization procedure comprises black liquor or described concentrated caustic solution.

31. methods according to claim 30, the described neutralizer wherein for described second batch organic material comprises Part II caustic lye of soda, is concentrated caustic solution afterwards.

32. methods according to claim 30, wherein said method of evaporating carries out in the effector of multiple continuous connection.

33. methods according to claim 32, the temperature range of wherein said method of evaporating between 50 and 60 DEG C is carried out.

34. methods according to claim 33, the pressure that wherein said method of evaporating clings to-0.84 in the first effector, and carry out at lower pressure in second effector in described first effector downstream.

35. methods according to claim 34, wherein carry out described method of evaporating, until described concentrated caustic solution has the effective alkali concentration between often liter of 100 and 110 grams of NaOH.

36. methods according to claim 30, comprise the described concentrated caustic solution joined by caustic lye of soda for boiling described second batch organic material further.

37. methods according to claim 36, wherein said concentrated alkaline filtrate form that described concentrated alkaline filtrate and caustic lye of soda combine 60% to 75%.

38. methods according to claim 30, further comprising the steps:

39. methods according to claim 30, wherein comprise black liquor with described second liquid of middle use in first organic material described.

40. methods according to claim 30, wherein said caustic lye of soda has the effective alkali concentration between 95 and 125 grams often liter, and described second liquid has the effective alkali concentration between 30 and 35 grams often liter.