CN103687990B - Manufacture the compact method of prehydrolyzed pulp - Google Patents
Manufacture the compact method of prehydrolyzed pulp Download PDFInfo
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- CN103687990B CN103687990B CN201180072257.2A CN201180072257A CN103687990B CN 103687990 B CN103687990 B CN 103687990B CN 201180072257 A CN201180072257 A CN 201180072257A CN 103687990 B CN103687990 B CN 103687990B
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- 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
- D21C1/00—Pretreatment of the finely-divided materials before digesting
- D21C1/02—Pretreatment of the finely-divided materials before digesting with water or steam
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- 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
- D21C1/00—Pretreatment of the finely-divided materials before digesting
- D21C1/04—Pretreatment of the finely-divided materials before digesting with acid reacting compounds
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- 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
- D21C1/00—Pretreatment of the finely-divided materials before digesting
- D21C1/06—Pretreatment of the finely-divided materials before digesting with alkaline reacting compounds
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- 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
- D21C3/00—Pulping cellulose-containing materials
- D21C3/02—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes
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- 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
- D21C3/00—Pulping cellulose-containing materials
- D21C3/22—Other features of pulping processes
- D21C3/26—Multistage processes
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Abstract
The present invention relates to the compact method for manufacturing dissolving pulp in prehydrolysis sulphate cook method.In order to avoid the pitch prob-lems of screen cloth is extracted in blocking, and obtain prehydrolysis stage obviously terminate (distinct? ending) the uniform alkali dipping and before the sulphate cook stage, add in prehydrolysis material blends alkali make in and however, residual base concentration after Acidic Hydrolysis Products higher than 20 grams per liters in the degree of the effective alkali of NaOH, and temperature reduction at least 10% compared with the temperature in prehydrolysis stage of gained alkaline processing liquid for prehydrolysis material.Alkali charging depositing the hemicellulose avoiding dissolving in prehydrolysis stage again, and suddenly timber mixture is switched to alkali condition, this alkali condition is conducive to the alkali steeping stage at the reduction temperature before the final sulphate cook stage, and this impregnation stage will extract the major part of the hemicellulose level of this cellulosic material.
Description
Invention field
The present invention relates to the method manufacturing paper pulp, hydrolysis of hemicellulose becomes hydrolysate in the method, and lignin is dissolved by sulphate cook method to discharge cellulose fibre.More particularly, the present invention relates to the manufacture method with the paper pulp that high alpha-cellulose content also can be sold as dissolving pulp.
Background of invention
Traditionally, basic exist the method that two kinds of manufactures have the extraordinary paper pulp of high alpha-cellulose content.Comprise acid accumulator sulfite boiling and prehydrolysis-sulfate (sulfate pulp, kraft) boiling.The former is developed the late 19th century, and the latter is developed in generation nineteen thirty, see such as Rydholm, S.E., PulpingProcesses, and the 649 to 672 page, IntersciencePublishers, NewYork, 1968.Basic idea in two kinds of methods from cellulose fibre, removes hemicellulose when carrying out delignification as much as possible, thus obtain high alpha-cellulose content, namely there is the polymeric chain of relative high polymerization degree, but not there is the short hemicellulose molecule of the molecular structure of random grafting.
In traditional sulphite process, in digestion process, remove hemicellulose, simultaneously dissolved lignin.In this case conditions of cooking is highly acidic, temperature in the scope of 140 DEG C to 150 DEG C, facilitation of hydrolysis thus.But result is always compromised with delignification.Shortcoming is reduction of the degree of polymerization and the loss of yield of alpha-cellulose, also limit the possibility of hydrolysis.Therefore proposing various improvement, as changed conditions of cooking, even after pre-hydrolysis step, connecing the alkaline sulfite boiling stage.The major obstacle relevant to sodium sulfite process is the complexity of boiling chemicals and the recovery method of costliness.
Independent pre-hydrolysis step allows to carry out required adjustment by changing hydrolysising condition double cellulosic hydrolysis.A large amount of delignification is not carried out in this prehydrolysis-sulfate cooking process, until carry out independent alkaline boiling step, even if some handbook represents the lignin (i.e. the sub-fraction of total lignin levels, because 30 kilograms, timber per ton corresponds to about 3% of timber) that can dissolve nearly 30 kilograms, timber per ton in prehydrolysis.Prehydrolysis condition is the most usual to be realized by heating in vapours phase or hot water liquid environment, and pH can be reduced to about 3.5 by natural timber acidity usually that wherein discharge, is commonly referred to automatic hydrolysis most.Sometimes extra acid and catalyst can be added.Delignification's step is subsequently conventional Kraft cooking process, and wherein white liquid has added in boiling vessel.
Disclosed several prehydrolysis-sulfate cooking process, this technology the late period sixties to the seventies early stage pole paid attention to.
In 105-119 page, the experience from " continuous prehydrolysis-sulfate pulping " is described in earlier publication " ContinuousPulpingProcesses " (1970) of SvenRydholm.At the 106th page, a kind of twin containers continuously cooking system is disclosed in Fig. 8 .1, connect lower to spreading system sulphate cook boiling vessel (adownflowconventionalkraftcookingdigester) within the system after first upward flow prehydrolysis tower (afirstupflowprehydrolysistower), wherein upward flow tower only just stands serious pitch deposition (pitchdeposits) (this filter screen is blocked) extracting on filter screen in 3-6 days afterwards running.Another kind of system is disclosed in the 107th page, and shown in Fig. 8 .2, one has single container hydraulic continuous boiling vessel system, and described system has the first top pre-hydrolysis area and basic sulfatase boiling region, bottom, and two regions are separated by filter screen part.But in this single containment system, filter screen still meets with serious pitch deposition and blocking.Pitch prob-lems (pitchproblem) has also transferred to wood chip feed system, causes the alkalescence charging of needs in high pressure charging device to avoid the pitch deposition in high pressure charging device.In almost each table apparatus of the continuously cooking system with the slurrying of prehydrolysis-sulfate method, find this pitch prob-lems.This causes the change to the interference of producing and pulp quality.In addition, in previous continuous apparatus, lack the clear and definite pre-hydrolysis area in border result in variation in hydrolysis degree, thus cause the unacceptable quality fluctuations of final products.
When the slurrying of prehydrolysis-sulfate method is implemented in batch system, pitch prob-lems obtains part by the following fact and solves: the filter screen in batch (-type) boiling vessel switches to alkaline cooking liquor by extracting acid pre-hydrolysate and finally switches to black liquor.The volume of the Acidic Hydrolysis Products extracted after vapor phase prehydrolysis is relatively little in cumulative volume, and the exposure in filter screen is limited.Alkali stage subsequently also can dissolve with wash-out any resin deposit, with make they can not through time accumulate.This can not realize in continuous system, because filter screen is positioned at fixing process station, electrochemical conditions (as pH, resin content etc.) is constant there.
Usual and Superbatch is disclosed in US5589033
tMthe batch process of prehydrolyzed kraft for being sold by Metso that boiling is correlated with.Have gaseous steam mutually in 170 DEG C of pre-hydrolysis step of heat, described step terminates by using the thermo-neutrality step of alkali at 155 DEG C of heating, and only continues 15 minutes (as shown in Example 3).Next neutralization is hot black liquor treatment step at 148 DEG C, continues 20 minutes, and finally, paper pulp is boiling 54 minutes at 160 DEG C in the sulphate cook stage.Here, can by controlling the duration controlled hydrolysis degree well in each stage.Because hydrolysing step carries out in vapor phase, neutralization and the alkalization of timber below quite fast and can be carried out up hill and dale, due to timber at high temperature steam treatment mistake in vapor phase, allow alkali by this timber of diffusion dipping.But, vapor phase prehydrolysis and in and between the clear and definite transitional region in such border be disadvantageous in continuous system (wherein timber should be flow through reaction tower with plug flow form (inaplugflow)), therefore, hydrolysis is the most usual on the contrary realizes in the stage (at least at last part) being full of liquid.
Nowadays, be considered to and the optional method manufacturing the manufacture textiles had fewer environmental impacts compared with cotton textiles for the dissolving pulp of this type of purposes as spinning fibre (artificial silk/Lyocell).Dissolving pulp is still for the base product of the different additive in tyre cord and cover tire and adhesion agent and filler, ether and sponge (spongs), NC Nitroncellulose and acetic acid esters.Therefore, dissolving pulp can be replace the substitute products for the paper pulp of conventional slurrying.
Typical embodiments in most of prehydrolysis-sulfate cooking process be by extract pure acid pre-hydrolysate or in and the pre-hydrolysate of pre-hydrolysate form stop prehydrolysis stage.As previously mentioned, extract pre-hydrolysate if to be switched to by acidity in the dislocation of alkalescence when pre-hydrolysate remains on its minimum pH level or at wood chip suspension, any filter screen in this type of process station all will meet with pitch deposition.
Summary of the invention
An object of the present invention is the prehydrolysis-sulfate method providing to improve for being prepared paper pulp by the cellulosic material containing lignin.According to the present invention, the method now by comprising following steps achieves these and other objects: at the temperature of about 120 DEG C to 180 DEG C and at least 20 minutes period in prehydrolysis stage cellulosic material described in prehydrolysis to manufacture prehydrolysis cellulosic material and Acidic Hydrolysis Products.Subsequently to adding after the intensive charging of highly basic (alkalichockcharge) makes this Acidic Hydrolysis Products of neutralization in the mixture of prehydrolysis cellulosic material and Acidic Hydrolysis Products, preferably to follow closely after this charging and after thorough mix-ing, however, residual base concentration in the degree of the effective alkali of NaOH (g/lEAasNaOH), forms alkaline processing liquid higher than 20 grams per liters.Subsequently, in the alkaline preextraction stage, this prehydrolysis cellulosic material is remained on time enough in described alkaline processing liquid alkali concn is reduced at least 10 grams per liters in the effective alkali of NaOH, but be not reduced to lower than 5 grams per liters in effective paper mill wastewater of NaOH.In the described alkaline preextraction stage, the carbohydrate dissolved and any lignin dissolved in this prehydrolysis stage keep dissolving in this alkaline preextraction phase process, and from this cellulosic material, dissolve more carbohydrate and lignin in this alkaline preextraction stage.After the alkaline preextraction stage, this cellulosic material is transferred to the sulphate cook stage from the alkaline preextraction stage.Characteristic of the present invention is: use certain amount of liquid to manufacture the intensive charging of highly basic, described amount of liquid makes temperature reduction at least 10% compared with the temperature in prehydrolysis stage of the gained alkaline processing liquid for prehydrolysis material, if preferably prehydrolysis temperature is about 120 DEG C, reduce at least 12 DEG C, if prehydrolysis temperature is about 180 DEG C, reduce at least 18 DEG C, to reduce the alkali consumption in boiling chemical species diffusion process, in this diffusion process, alkali treatment liquid penetrates in the core of the cellulosic material containing lignin.The core of the cellulosic material containing lignin can be impregnated into more up hill and dale to the conversion in the alkaline preextraction stage of relative low temperature by acid prehydrolysis stage, cause carrying out with low substandard products amount (lowrejectsamounts) after the sulphate cook stage subsequently evenly boiling.Another positive effect is that boiling temperature can reduce, and which increases the final alpha-cellulose content in paper pulp after sulphate cook.This temperature of remarkable reduction also reduces hemicellulose and deposits on fiber, because precipitation process is strongly depend on temperature again.
According to a preferred embodiment, do not add by means of only heating and optional interpolation water the acidifying that any external acid agent carries out described prehydrolysis, the timber acidity only discharged in use heating process reaches the pH level lower than 5 in pre-hydrolysis process.In such an implementation, do not use any external acid agent also can carry out the acidifying of described prehydrolysis in the topping up stage, and the temperature at the end of prehydrolysis is preferably 150-180 DEG C.In such cases, external acid agent is not used to make the temperature of the mixture of gained alkaline processing liquid and prehydrolysis material lower than 130 DEG C.The temperature of the mixture of gained alkaline processing liquid and prehydrolysis material preferably lower than 120 DEG C, this best sulphate cook temperature far below about 142 DEG C.
According to another preferred embodiment, carry out the acidifying of described prehydrolysis by heating and add external acid agent, in pre-hydrolysis process, reach the pH level lower than 3.In such an implementation, use external acid agent can carry out the acidifying of described prehydrolysis in the topping up stage, and the temperature at the end of prehydrolysis is preferably 120-165 DEG C.In such cases, use external acid agent, make temperature for the gained alkaline processing liquid of prehydrolysis material lower than 125 DEG C.The mixture of gained alkaline processing liquid and prehydrolysis material preferably lower than 120 DEG C, this best sulphate cook temperature far below about 142 DEG C.
And if carry out prehydrolysis in the topping up stage in two kinds of situations of adding in prehydrolysis or do not add acidulant, obtain the several advantages to the object realizing high alpha-cellulose productive rate.As mentioned above, solubilized nearly timber per ton 30 kilograms of lignin in pre-hydrolysis process, and if be be full of liquid mutually in, this lignin more easily can remain dissolved state, prevents it from condensing on fiber.Condensation lignin adversely can affect the ensuing diffusion/infiltration of boiling chemicals, because have been found that it forms the layer hindering diffusion on fibrous material, can reduce delignification's speed like this in sulphate cook process subsequently.Lignin condensation is in dilution alkaline environment, occurs especially in acid condition and causes the well known phenomenon of " steam burnt " (namely containing the extremely difficult paper pulp at the condensation lignin after this removed further).Lignin condensation will cause the boiling temperature improved to reach target Kappa number, and this transfers to create adverse influence to alpha-cellulose productive rate.If avoid the condensation of lignin in pre-hydrolysis process, paper pulp can easier at the end of sulphate cook subsequently boiling to required Kappa number, and there is higher productive rate and cellulosic degree of polymerization, this is all conducive to the specific class of dissolving pulp.
As by use or do not use the above-mentioned embodiment of external acid agent realize, if do not use acidulant, higher temperature is needed to the prehydrolysis effect of similar degree, but for two embodiments, it is required for carrying out changing between prehydrolysis stage and alkaline preextraction stage, with significantly reduce temp.
Further embodiment of the present invention is the step remained on by prehydrolysis cellulosic material in described alkaline processing liquid, and described step carries out about 10 to 90 minutes.Except carrying out thoroughly timber after prehydrolysis stage according to main purpose and except uniform alkalization, importantly optimizing the condition of alkaline preextraction and alkali steeping before boiling.Find out from laboratory test, sub-fraction only in hemicellulose total content is dissolved at prehydrolysis stage and is hydrolyzed into oligosaccharides, monose and catabolite thereof, and the larger part in hemicellulose total content can be dissolved in the alkaline preextraction stage subsequently.Total dissolved organic matter content (DOC) after prehydrolysis is about 5-10%, and up to 30% after the alkaline preextraction stage of prolongation after prehydrolysis.DOC comprises all content of organics from timber, comprises hemicellulose/carbohydrate and lignin.
According to another embodiment, dried from least 1 cubic metre/ton of OD(the alkaline processing liquid of described alkaline preextraction stage removing before the sulphate cook stage starts) timber, and the carbohydrate of contained dissolving and lignin, this backward sulphate cook stage adds alkali.By the alkaline processing liquid in the place's extraction of this latter half, keep its alkalescence simultaneously, can avoid pitch prob-lems in any extraction screen portion (extractionscreensections) in prehydrolysis stage, and total DOC content can be accumulate to this point in this process.This is especially useful for continuously cooking system, and described continuously cooking system is attempting to have met with serious pitch deposition problem when the extraction screen cloth in type systematic thus extracts acid or neutral pre-hydrolysate.In addition, before the sulphate cook stage, extract the liquid being rich in hemicellulose decrease the belongings entering the sulphate cook stage, this then reduce, in sulphate cook phase process, the reppd risk of hemicellulose occur after a while, this precipitation again depends on hemicellulose concentration and high temperature.
In the most preferred embodiment of the present invention, the method can be implemented in a continuous digester system, and described continuous steamer system uses at least one container for prehydrolysis, and uses a container for alkaline preextraction stage and sulphate cook stage.In this embodiment, the alkaline preextraction stage can also implement in a separate container, and this sulphate cook stage implements in another independent container.Because the intensive charging of highly basic will make pH condition fast steering alkalescence side after prehydrolysis, not only avoid the potential pitch deposition problem relevant to violent continuity method, the risk that the hemicellulose also eliminating the initiation of low however, residual base concentration deposits again.The following alkaline preextraction stage give also the optimum condition of thoroughly being flooded this acid wood by the diffusion of described alkaline processing liquid, and this result in higher DOC Alkaline solubilization degree and the uniform pH level to timber core before the alkaline boiling stage.Diffusion is the process than more being depended on the time by the replacement process obtained by rinsing (by-flushing) akaline liquid, so, when without the need to realizing internal liquid circulation in all stage, improves the condition of continuous process.
When with known prehydrolysis-sulfate method, as US5589033 compare time, the invention provides following advantages:
Reduce temperature (namely two kinds of prehydrolysis have the process conditions of dominance most) by pH sharp transition this prehydrolysis stage is terminated (distinctending) at once to enough little alkali concn.
The neutralization of free fluid occurs quite rapidly (instantly), but be that of obtaining more be conducive in and the condition of constraint liquid of wood internal.High temperature be conducive to diffusion, but due to alkali wear rate at high temperature much higher, lower temperature is vital for alkali is diffused in timber core.
Most of batch (-type) cooking process come from the state of the prior art wherein very paying close attention to heat-economy, start from RDH method and more modern batch (-type) cooking process Superbatch.In pretreatment stage before cooking, use come from the used beat of boiling stage latter end with warm liquid to reclaim heat.Be similar in US5589033, usually use high boiling temperature (160 DEG C).Therefore in batch (-type) boiling, there is conventional method to attempt to keep high temperature to improve heat-economy in the process of the method.In the continuous sulphate cook in modern times, best boiling temperature reduces, in nineteen fifty for late period, boiling temperature is typically about 160 DEG C, for hardwood even up to 170 DEG C, now, in nineteen ninety for late period, the typical boiling temperature of hardwood is about 142 DEG C.
In the method for the invention, relatively cold alkali charging is for interrupting this prehydrolysis.This is called the cold alkali charging without heating before interpolation.The alkali charging be applicable to herein contains caustic soda, and preferred reagent is basic sulfatase cooking liquor, i.e. white liquid.Effective alkali concentration (i.e. EA) provides usually in units of %, and meets: 1/2Na
2s+NaOH.This type of white liquid keeps the temperature of about 80-90 DEG C usually when being carried by recovery island (recoveryisland), and the white liquid of this temperature is included in cold alkali charging definition used.This white liquid preferably cools in a heat exchanger further to reach required final temperature after adding at the end of prehydrolysis.Other alkaline filtrate can also be added, preferably there are high alkali content and low temperature those.
The cellulosic material containing lignin being ready to use in this method is cork, hardwood or annual plant suitably.
According to the present invention, can obtain prehydrolysis-sulfate paper pulp with high alpha-cellulose productive rate, described alpha-cellulose has high polymerization degree.
Summary of drawings
Fig. 1 is the schematic diagram of the cooking process according to US5589033;
Fig. 2 is the schematic diagram according to cooking process of the present invention;
Fig. 3 a be after prehydrolysis stage when termination (PR) and be exposed to alkaline processing liquid time (when Ex starts) run through the schematic diagram of the pH of wood chips;
Fig. 3 b shows temperature-dependent alkali wear rate;
Fig. 4 shows after prehydrolysis when the different pH levels making to realize in wood chip when being exposed to alkaline processing liquid (the using cold or heated alkaline treatment fluid) a very long time;
Fig. 5 shows the inner Kappa number after sulphate cook of wood chip after kind of the different disposal of two as shown in Figure 4;
Fig. 6 shows the main device of the continuously cooking system using method of the present invention, uses a prehydrolysis tower and two for the follow-up container of basic treatment and boiling here;
Fig. 7 shows the main device of the continuously cooking system using method of the present invention, uses a prehydrolysis tower and one for the follow-up container of basic treatment and boiling here;
Fig. 8 a-8d shows the method for the present invention implemented in batch (-type) boiling vessel when terminating prehydrolysis and starting follow-up alkali treatment.
Detailed Description Of The Invention
As a comparison, show the boiling step of US5589033 in FIG.First wood chip processes in pre-hydrolysis step Pr, wherein by steam, wood chip is heated to 170 DEG C, continues 25 minutes.The white liquid adding heating subsequently, to carry out neutralization procedure Ne, extracts acid pre-hydrolysate REC from this process
aC.This neutralization procedure carries out 15 minutes at 155 DEG C.Although white liquid is heated, its temperature reduces about 8%.After this neutralization procedure, by adding this neutralising fluid of hot black liquor BL Hot swapping, this create the maintenance alkaline black liquor impregnation step BL of 20 minutes at 148 DEG C.Extract black liquor subsequently, and add new white liquid charging before boiling step Co below, described boiling step keeps 54 minutes at 160 DEG C.At business batch (-type) decoction system, as the Superbatch that Metso sells
tMin, white liquid used to be used as before neutralising fluid in a heat exchanger by the cooking liquor by mistake of heat and Steam Heating not keep high-temperature level.
On the contrary, the boiling step of method of the present invention is shown in fig. 2.There is shown the first steaming step ST for wood chip, but this step can avoid the prehydrolysis implemented in vapor phase subsequently.Wood chip processes subsequently in pre-hydrolysis step Pr, by steam, wood chip is heated to about 120 DEG C to 180 DEG C in this step and also continues at least 20 minutes to manufacture prehydrolysis cellulosic material and Acidic Hydrolysis Products.Adding liquid is as water H
2o is a kind of selection, if such as attempt liquid prehydrolysis in continuously cooking system, this is preferred.Alternatively add acidulant Ac, if attempt lower temperature in this prehydrolysis.
According to method of the present invention, by adding, strong WL is cold with the intensive charging of cold alkali realizes terminating at once of prehydrolysis, and the volume of the intensive charging of described alkali will make the reduction at least 10% compared with the temperature in prehydrolysis stage of cellulosic material temperature with temperature.If preferably prehydrolysis temperature is about 120 DEG C, reduces at least 12 DEG C, if prehydrolysis temperature is about 180 DEG C, reduce at least 18 DEG C.This will obtain alkaline processing liquid, and this alkaline processing liquid reaches higher than 20 grams per liters in the remaining effective alkali concentration of the effective alkali of NaOH after charging.Subsequently, this prehydrolysis material is kept time enough alkali concn is reduced at least 10 grams per liters in the effective alkali of NaOH at alkali preextraction stage Ex, but can not be reduced to lower than 5 grams per liters in effective paper mill wastewater of NaOH.In this preextraction stage, the carbohydrate of dissolving and any lignin dissolved in this prehydrolysis keep dissolving in this alkaline preextraction phase process, and dissolve more carbohydrate and lignin from this cellulosic material.Subsequently, this cellulosic material is transferred to sulphate cook stage Co by alkaline preextraction stage Ex.Before transferring to the sulphate cook stage, preferably extract most alkaline processing liquid use with recovery, and the WL that feeded by fresh alkali is added into boiling starts.Sulphate cook can be implemented with the known sulphate cook method of any type, and such as batch (-type) or continuously cooking, as Compact boiling, Lo-Solids boiling, ITC-boiling, MCC boiling, EAPC boiling.Sulphate cook is terminated by washing stage Wa subsequently, and this washing stage to implement in the known washing facility of any type, as the countercurrent washing district in digester bottom, or can use pressure diffuser washing or filter wash after cooking.
Schematically disclose in fig. 3 a after prehydrolysis when the pH situation being exposed to the intensive when filling with substance of alkali and running through wood chip.PH level at wood chip core place is equally low with the pH level realized in prehydrolysis, and wood chip outer surface is exposed to the alkaline processing liquid of acquisition.
Disclose the reaction rate (i.e. wear rate) of the alkali changed with temperature in delignification's process in fig 3b.Disclosed herein is the rule of thumb of sulphate cook, wherein temperature often improves 8 DEG C, and reaction rate doubles.If start from the typical boiling temperature of 140 DEG C, this temperature corresponds to the reaction rate of reference as 100%.If boiling temperature progressively reduces by 8 DEG C to 132,126,118 and 110 DEG C, reaction rate will progressively be reduced to 50%, 25%, 12.5% and 6.25% respectively.Therefore the most important thing is to reduce temperature, if the core highly basic of wood chip floods, decrease lignin delignification and react alkali consumption in the diffusion process caused.Alkali wear rate too high in diffusion process can cause the alkali shortage in the core of the cellulosic material containing lignin, causes substandard products amount after the sulphate cook stage subsequently to improve.
If show that use heat respectively or cold alkaline processing liquid (i.e. T in the diagram
heatand T
cold) make alkali be diffused in the timber of prehydrolysis, the schematic difference in the pH of wood chip inside realization is horizontal.As seen in right figure, at cold alkalies (T
cold) in after process the pH level (dotted line) that reaches in the core of cellulosic material far above pH level when using the alkaline processing liquid T heat of heat.Its reason is the alkali wear rate reduced in diffusion process.
For follow-up boiling, the most important thing is uniform pH situation, in Figure 5, Fig. 5 schematically discloses Kappa number through digested wood chip respectively to heat with cold basic treatment dotted line in this display.As seen in left figure, Kappa number is higher in core, i.e. non-boiling UC, and surface has much lower Kappa number, i.e. hard cook OC.Which results in core segment high substandard products amount and in surface cellulosic alkaline degradation.Show in right figure evenly delignification, between wood surface and core, there is less difference because of complanation pH situation.Left figure and right figure all obtains identical average Kappa number H
aVbut the boiling carried out after with cold alkali treatment obtains the paper pulp containing higher alpha-cellulose.
Disclose the three container continuously cooking systems for prehydrolysis and boiling in figure 6.First wood chip is fed in wood chip accumulator 1 and also sends into subsequently in steam treatment container 2, adds steam ST in the process for purging wood chip with the air except attachment removal.The wood chip crossed of steam treatment falls within the skewed slot being full of liquid above high pressure chute feeder 3 by steam treatment container, and the wood chip slurry of formation is also fed to prehydrolysis container 10 with incoming flow 4 by the wood chip pressurization that steam treatment is crossed by this high pressure chute feeder.Here, prehydrolysis container is Vapor-liquid phase boiling vessel form, and it has inverted top separator 11, can extract part conveying liquid be back to charging beginning through A by pipeline 4.As shown, steam ST is added to the top of container 10, optionally can also add acid by origin source Ac.In the bottom of this prehydrolysis container 10, origin source WL adds the charging of cold highly basic.This can by this alkali is mixed into return stream B realize.Prehydrolysis timber in the treatment fluid that it is alkaline is at present fed to preextraction container 20 subsequently in pipeline 14, and this container is the vessel form of filling with water, has the top separator 21 of below charging.In preextraction container after the required processing time, alkaline timber is fed in Vapor-liquid phase boiling vessel 30 through pipeline 24, and extract excessive transmitting fluid by inverted top separator 31 and deliver to C, it can be used as a part for transfer cycle to add the bottom of preextraction container 20 to.Here, most of alkaline processing liquid used can be extracted to reclaim by returning stream C.In boiling vessel 30, carry out sulphate cook, and finally in pressure diffuser 40, wash the paper pulp of prehydrolysis and boiling.
Disclose the twin containers continuously cooking system for prehydrolysis and boiling in the figure 7.Here be relative to the difference of Fig. 6, preextraction container 20 carries out as the first stage in container 30 most recovery to REC1 being extracted alkaline processing liquid used by this screen portion between top separator 31 and screen portion.The central tube of fresh white liquid through extracting screen cloth At The Height for boiling phase subsequently adds.
In Fig. 8 a to 8d, show method of the present invention such as how 4 step order and implement in batch (-type) boiling vessel.In Fig. 8 a, show steam prehydrolysis stage, wherein vapor phase is at prehydrolysis temperature T
hYDlower this container of filling.At the end of this prehydrolysis stage, add the white liquid of cooling to bottom, as shown in figure 8b, the white liquid of interpolation catches the acidic condensate (the layer PC as before the cold white liquid liquid level risen) on timber.In Fig. 8 c, show cold white liquid subsequently, through the displacement stage of container, also there is the cold white liquid formed between acidic condensate PC and the cold white liquid of rising of more volume and the mixture M X of acidic condensate here.When liquid level reaches upper screen, it can be circulated back to bottom as shown in Fig. 8 d, and acidic condensate PC can the part in mixing portion MX or as acidic condensate return at least partially.But part or all of acidic condensate PC can send to recovery with the form of more net portion PC, and the acidic condensate be included in mixture M X that only circulates.Can be controlled by pH sensor and/or temperature sensor by the switching extracted to recirculation.
Claims (13)
1. prepared the method for paper pulp by the cellulosic material containing lignin, to be included at the temperature of 120 DEG C to 180 DEG C cellulosic material described in prehydrolysis in prehydrolysis stage, and to continue at least 20 minutes to manufacture prehydrolysis cellulosic material and Acidic Hydrolysis Products, add in the mixture of prehydrolysis cellulosic material and Acidic Hydrolysis Products the intensive charging of highly basic make in and however, residual base concentration after Acidic Hydrolysis Products higher than 20 grams per liters in the degree of the effective alkali of NaOH, form alkaline processing liquid, this prehydrolysis cellulosic material is remained on the time sufficient in described alkaline processing liquid in the alkaline preextraction stage alkali concn is reduced at least 10 grams per liters in the effective alkali of NaOH, but be not reduced to lower than 5 grams per liters in effective paper mill wastewater of NaOH, the carbohydrate dissolved thus and any lignin dissolved in prehydrolysis stage keep dissolving in this alkaline preextraction phase process, and from this cellulosic material, dissolve more carbohydrate and lignin in the alkaline preextraction stage, subsequently this cellulosic material is transferred to the sulphate cook stage by the alkaline preextraction stage, it is characterized in that, certain amount of liquid is used to manufacture the intensive charging of highly basic, described amount of liquid makes temperature reduction at least 10% compared with the temperature in prehydrolysis stage of the gained alkaline processing liquid for prehydrolysis material, if prehydrolysis temperature is 120 DEG C, reduce at least 12 DEG C, then at least 18 DEG C are reduced as prehydrolysis temperature is 180 DEG C, to reduce the alkali consumption in boiling chemical species diffusion process, in this diffusion process, alkali treatment liquid is impregnated in the core of the described cellulosic material containing lignin.
2. the method for claim 1, wherein do not add by means of only heating and optional interpolation water the acidifying that any external acid agent carries out described prehydrolysis, the timber acidity only discharged in use heating process reaches the pH level lower than 5 in pre-hydrolysis process.
3. method as claimed in claim 2, the acidifying of wherein said prehydrolysis be full of liquid mutually in carry out.
4. method as claimed in claim 3, the temperature wherein at the end of prehydrolysis is 150-180 DEG C.
5. method as claimed in claim 4, the temperature of the wherein said gained alkaline processing liquid for prehydrolysis material is lower than 130 DEG C.
6. the method for claim 1, the acidifying of wherein said prehydrolysis, by heating and add external acid agent to realize, reaches the pH level lower than 3 in pre-hydrolysis process.
7. method as claimed in claim 6, the acidifying of wherein said prehydrolysis be full of liquid mutually in carry out.
8. method as claimed in claim 7, the temperature wherein at the end of prehydrolysis is 120-165 DEG C.
9. method as claimed in claim 8, the temperature of the wherein said gained alkaline processing liquid for prehydrolysis material is lower than 125 DEG C.
10. the method as described in claim 2 or 5, is wherein undertaken the step that this prehydrolysis cellulosic material remains in described alkaline processing liquid 10 to 90 minutes.
11. methods as described in claim 2 or 5, at least 1 cubic metre/ton of kiln dried wood in the alkaline processing liquid of wherein removing from the described alkaline preextraction stage before the sulphate cook stage starts, and the carbohydrate of contained dissolving and lignin, this backward sulphate cook stage adds alkali.
12. the method for claim 1, wherein implement the method in a continuous digester system, and this system uses at least one container for prehydrolysis, and a container is used for alkaline preextraction stage and sulphate cook stage.
13. methods as claimed in claim 12, its neutral and alkali preextraction stage implements in a separate container, and the sulphate cook stage implements in another independent container.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/SE2011/050610 WO2012158075A1 (en) | 2011-05-13 | 2011-05-13 | Compact process for producing prehydrolyzed pulp |
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| Publication Number | Publication Date |
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| CN103687990A CN103687990A (en) | 2014-03-26 |
| CN103687990B true CN103687990B (en) | 2016-03-30 |
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| CN201180072257.2A Active CN103687990B (en) | 2011-05-13 | 2011-05-13 | Manufacture the compact method of prehydrolyzed pulp |
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| Country | Link |
|---|---|
| EP (1) | EP2707539B1 (en) |
| CN (1) | CN103687990B (en) |
| CA (1) | CA2837277C (en) |
| ES (1) | ES2737432T3 (en) |
| PT (1) | PT2707539T (en) |
| RU (1) | RU2546497C1 (en) |
| WO (1) | WO2012158075A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US8951388B2 (en) | 2011-04-08 | 2015-02-10 | Pec-Tech Engineering And Construction Pte Ltd | Method and system for efficient production of dissolving pulp in a kraft mill producing paper grade pulp with a continuous type digester |
| SE539706C2 (en) | 2014-11-07 | 2017-11-07 | Valmet Oy | Method for recovering hydrolysate |
| SE538454C2 (en) | 2014-11-27 | 2016-07-12 | Valmet Oy | Method for displacement in batch digesters |
| ES2959654T3 (en) * | 2016-05-27 | 2024-02-27 | Fibratech Pte Ltd | A method and system for the production of high molecular weight lignin |
| SE541646C2 (en) * | 2017-07-04 | 2019-11-19 | Valmet Oy | Method for operating a continuous vertical reactor comprising a prehydrolysis zone and the reactor design as such |
| EP3673110A4 (en) * | 2017-08-25 | 2021-05-12 | Valmet AB | Improved compact process for producing prehydrolyzed pulp |
| FI130070B (en) * | 2018-03-07 | 2023-01-31 | Andritz Oy | Method of producing dissolving pulp |
| CN109629290A (en) * | 2018-12-25 | 2019-04-16 | 新疆富丽达纤维有限公司 | A kind of pulping production technology reducing dissolving pulp dosage |
| SE542991C2 (en) * | 2019-03-29 | 2020-09-22 | Valmet Oy | A method and a system for extracting hydrolysate in a continuous cooking process for producing pulp |
| FI129760B (en) * | 2020-07-06 | 2022-08-15 | Amppc Finland Oy | A high yield cooking method |
| FI130568B (en) * | 2020-07-06 | 2023-11-21 | Amppc Finland Oy | A cooking method |
| CN112048929B (en) * | 2020-08-18 | 2021-06-29 | 福建农林大学 | Method for separating hemicellulose from wood and bamboo raw materials by low-solid prehydrolysis |
| CN112853796A (en) * | 2021-01-07 | 2021-05-28 | 杭州融凯盛科技有限公司 | Preparation method for modifying papermaking pulp into pulp special for lyocell fibers |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4436586A (en) * | 1982-01-22 | 1984-03-13 | Kamyr, Inc. | Method of producing kraft pulp using an acid prehydrolysis and pre-extraction |
| CN1139464A (en) * | 1994-01-24 | 1997-01-01 | 波里桑德斯纤维分离机公司 | Production of prehydrolyzed pulp |
| CN101368295A (en) * | 2008-09-19 | 2009-02-18 | 福建省南纸股份有限公司 | Preparation method for Chinese red pine dissolving pulp |
| CN101514529A (en) * | 2008-09-02 | 2009-08-26 | 上海士林纤维材料有限公司 | Method for preparing bamboo dissolving pulp by improved prehydrolysis alkaline process and product thereof |
| CN101565906A (en) * | 2009-06-09 | 2009-10-28 | 上海士林纤维材料有限公司 | Method for producing bamboo dissolving pulp by pre-extracting hemicellulose and product thereof |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU182496A (en) * | ||||
| AT398588B (en) * | 1992-12-02 | 1994-12-27 | Voest Alpine Ind Anlagen | METHOD FOR THE PRODUCTION OF VISCOSE CELLS |
| US6248208B1 (en) * | 1995-06-02 | 2001-06-19 | Andritz-Ahlstrom Inc. | Pretreatment of chips before cooking |
| AT404478B (en) * | 1996-02-02 | 1998-11-25 | Impco Voest Alpine Pulp Tech | Cooking liquor containing low b.pt. solvents and quinone reducing catalysts - contains alkali sulphite(s) and sulphide(s) in aqueous solution |
| FI122654B (en) * | 1997-12-08 | 2012-05-15 | Ovivo Luxembourg Sarl | Process for making paper cellulose pulp |
| FI20085425L (en) * | 2008-05-08 | 2009-11-09 | Metso Paper Inc | Sulfate pre-hydrolysis cooking method |
-
2011
- 2011-05-13 PT PT11865841T patent/PT2707539T/en unknown
- 2011-05-13 RU RU2013155475/12A patent/RU2546497C1/en active
- 2011-05-13 WO PCT/SE2011/050610 patent/WO2012158075A1/en active Application Filing
- 2011-05-13 ES ES11865841T patent/ES2737432T3/en active Active
- 2011-05-13 CN CN201180072257.2A patent/CN103687990B/en active Active
- 2011-05-13 EP EP11865841.8A patent/EP2707539B1/en active Active
- 2011-05-13 CA CA2837277A patent/CA2837277C/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4436586A (en) * | 1982-01-22 | 1984-03-13 | Kamyr, Inc. | Method of producing kraft pulp using an acid prehydrolysis and pre-extraction |
| CN1139464A (en) * | 1994-01-24 | 1997-01-01 | 波里桑德斯纤维分离机公司 | Production of prehydrolyzed pulp |
| CN101514529A (en) * | 2008-09-02 | 2009-08-26 | 上海士林纤维材料有限公司 | Method for preparing bamboo dissolving pulp by improved prehydrolysis alkaline process and product thereof |
| CN101368295A (en) * | 2008-09-19 | 2009-02-18 | 福建省南纸股份有限公司 | Preparation method for Chinese red pine dissolving pulp |
| CN101565906A (en) * | 2009-06-09 | 2009-10-28 | 上海士林纤维材料有限公司 | Method for producing bamboo dissolving pulp by pre-extracting hemicellulose and product thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2012158075A1 (en) | 2012-11-22 |
| EP2707539A4 (en) | 2014-11-19 |
| RU2546497C1 (en) | 2015-04-10 |
| ES2737432T3 (en) | 2020-01-14 |
| EP2707539A1 (en) | 2014-03-19 |
| EP2707539B1 (en) | 2019-05-08 |
| PT2707539T (en) | 2019-06-27 |
| CA2837277C (en) | 2017-06-27 |
| CN103687990A (en) | 2014-03-26 |
| CA2837277A1 (en) | 2012-11-22 |
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