JPH1053989A - Batching for producing improved kraft pulp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cook a pulp raw material by using a smaller amount of white liquor and obtain pulp having good pulp strength and breaching degree by diverting a part of green liquor to carbonate crystallization process and causticizing the separated carbonate crystal. SOLUTION: Wood chip is charged into a digester and black liquor AA from a tank is packed therein and an over flow line A2 to a tank 4 is closed and the digester is pressurized to impregnate the black liquor into the wood chip. Then, hot black liquor B from a tank 1 is transferred and cold black liquor A3 is introduced into the tank 4. White liquor C is transferred from a tank 3 to the digester and a liquor D2 is introduced into a tank 2. When delignification is advanced to a desired extent, already used liquor is substituted with a cleaning filtrate E and total volume B required for a packing process is obtained from the first part B1 of the hot black liquor and the second part D1 of the black liquor is introduced into the tank 2. When cooking liquors X1 to X3 which are not causticized are added to the digester, pure caustic alkali for bleaching is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing cellulose using a regenerated pulping process liquor, a non-causticified cooking liquor and a causticized white liquor to dissolve lignin. The present invention relates to a method for producing kraft pulp to be treated. More particularly, the present invention relates to the use of green liquor or mother liquor obtained from the crystallization of carbonate of green liquor in the initial stage of modern displacement kraft batch cooking, and its advantages in the field of improved kraft pulp quality It is about.

[0002]

BACKGROUND OF THE INVENTION In various kraft pulping processes, cellulosic raw materials, wood chips, are usually treated at elevated temperatures using an alkaline cooking liquor (called white liquor) containing sodium hydroxide and sodium hydrogen sulfide. You. In these processes, the cooking liquor, which occurs when the inorganics eluted from the recovery kiln are dissolved in water before the carbonates are causticized to hydroxide, is usually mixed with green liquor. Said, causticized green liquor is usually referred to as white liquor, and used cooking liquor is usually referred to as black liquor. Table 1 shows a typical composition comprising green liquor and white liquor.

──────────────────────────────────── Table 1. Typical composition of so-called green liquor and white liquor / 1) / ─── Green liquor White liquor Component Concentration Concentration g / L g / L As Na ₂ O As Na ₂ O ─────────────────────────── ───────── NaOH 1595 Na ₂ S 37 38 Na ₂ CO ₃ 107 26 ─────────────────────────── ───────── 1) Clayton, D. , Et al., "Chemistry of alkaline pulping, in Pulp and Paper Manufacture in the manufacture of pulp and paper", Third Edition, Volume 5, Alkaline Pulping,, Grace , Tea, M. (Grace, TM), Malcolm, E. W. (Malcom, EW), TAPPI, CPPA, 1989, pages 17,15.

[0004] The high and low hydroxide concentrations of carbonate are noteworthy in green liquor. Of particular importance is to note that all the reduced sulfur is already in the final and useful form of hydrosulfide [HS ^- ion (Na ₂ S dissolved in water)]. The carbonate / hydroxide combination in the green liquor does not provide the high pH required for conventional kraft processes and must be converted to a so-called "white" liquor by a caustic process, but , It is an excellent source of hydrosulfide in alkalinity buffering carbonate. Traditionally, steaming with green liquor has only been used for high-yield semi-chemical pulping, in which delignification has been deliberately reduced, and pulp that still contains the majority of lignin and fiber, After steaming with green liquor, it must be opened by mechanical refining [Paltheim, S .; (Vardheim, S.), The use of green liquor as cook in the production of semi-chemical hardwood pulp for fluting
ing liquor in the production of semi-chemical hard
wood pulps for fluting), Paperi japu (Paperi ja
Puu) (1967)]. These types of pulp are not suitable for so-called chemical paper pulp and cannot be bleached and find use in board making.

[0005] From a cooking chemical point of view, in recent years the industrial kraft pulp process has been quite unchanged and underdeveloped.
It is true that many different chemical agents have been proposed to improve factors such as pulp yield, quality and delignification selectivity, but each of these requires complex external equipment, additional These proposals are entirely acceptable in terms of acceptable practical solutions to the above problems, since they involve the use of expensive chemicals that cannot be recovered and regenerated, besides the production process, more digester capacity or pulp mill. It did not provide a solution. In the early 1970's, a new trend was noted indicating increasing environmental pressure on the kraft pulp industry to rapidly reduce the amount of leachables that pollute the environment. In order to eliminate organic effluents from pulp bleaching, the kraft cook to be spread must have a much lower residual lignin concentration in the pulp than previous methods. Due to the poor pulp quality obtained when using conventional cooking methods to obtain low residual lignin concentrations, an improved kraft cooking method had to be developed. Above all, the study of the development
The role of hydrosulfide ions was not considered. The concentration of hydrosulfide ions must be high during the early stages of the cook-as the cook ends, the hydrosulfide is no longer effective. The desired role of the hydroxyl ion is exactly the opposite [Sjoeblom, K.,
"Extended delignification in kraft cooking via improved selectivity"
in kraft cooking through improved selectivity), Paperi ja Puu, 65: 4227 (1
983); Norden, S .; (Norden, S.) and Tedder,
A. (Teder, A.), "Modified kraft processe for softwood bleached grade pulp.
s for softwood bleached-grade pulp) ", TAPPI
Journal (TAPPI Journal) 62: 7,49 (197
9)]. It has been proposed to produce white liquors of different sulfidities in order to obtain optimal hydrosulfide and hydroxide ion concentration profiles (Jang Jiang) et al., "Improved kraft pulping with controlled sulfide addition ( Improved kraft pulping by controlled sulfide
additions) ”, Proceedings of the 7th International Symposium on Wood and Pulping Chemistry, P.R. China
(PRChina), May 25-28, 1993; Tedder,
A. (Teder, A.) and Olm, L., "Extended Delignification by Combination of Improved Kraft Cooking and Oxygen Bleaching"
bination of modified kraft pulping and oxygen blea
ching), Paperi ja Puu, 63: 4
a, 315 (1981)]. Another study [Andrews, e. Kei. (Andrews, EK), "Extended delignification of Rhubarb pine using a novel concept approach within the framework of conventional craft and oxygen technology.
lignification of southern pine using novel concept
ual approaches within the framework of conventiona
l kraft and oxygen technologies) ”, Dr. Thesis (Ph.
D. Thesis), Department of wood and papersci
ence), University of North Carolina, 1982], a sulfide-containing liquor was tried as a pretreatment step prior to conventional kraft cooking using white liquor.
As predicted by theory, a better pulp viscosity was found. Since these types of pretreatments require a separate cooking step at relatively high temperatures (effective alkali dosing of the wood up to 7% and 135 ° C.), these types of pretreatments require It requires sufficient production time and requires process improvement. Predictable yields and modest advantages have prevented this type of technology from being implemented.

In accordance with another invention (Tikka, US Pat. No. 5,183,535), a sulfur specie found in used black liquor is disclosed.
s) Before steaming is completed using white liquor,
It can impregnate and react with wood chips.

Another trend in kraft pulp process development has been to strive for energy efficiency. Therefore, from the early 1960's, continuous digesters began to become mainstream in this field. However, from the early 1980's, emerging and competing energy-efficient kraft batch processes using various displacement techniques began to gain ground again. The characteristics of the displacement kraft batch process are to collect hot black liquor at the end of the cook and to recycle the cook energy in subsequent batches. A good example of such development is described, for example, in Fagerlund, US Pat.
No. 78149, and the process described in Oestman, U.S. Pat. No. 4,764,251. In these inventions, the heat of the cooking is efficiently recovered, but the use of cooking chemicals is far from optimized.

Further development of substituted kraft batch cooking is
In order to easily achieve delignification and high pulp strength, a combination of energy efficiency and efficient use of the remaining and freshly cooked chemicals was included. This is due to the primary recovery of the hot and residual sulfur-rich "mother liquor" black liquor in one accumulator, and then the washing filtrate in another accumulator and This can be done by placing the displacement at the end of the cook for the recovery of the part of the black liquor with low minutes and low temperature. The accumulated black liquor is then recycled back to the next batch of wood chips for impregnation and reaction, respectively, prior to finishing with hot white liquor (Hiryanen (H
iljanen), Tikka, EP-B520452].
Using this means began kraft cooking with high doses of hydrosulfide and low concentrations of hydroxyl ions, thus making it possible to carry out the sulfur-lignin reaction in the hot black liquor pretreatment phase. Means that. White liquor, a required causticized cooking liquor with high hydroxyl ion content, is used to finish the cooking phase (where hydroxyl ions are consumed and the white liquor hydrosulfide in the residue of spent black liquor) Should be re-used in the next step). So far, both the heat and chemicals of batch cooking can be very efficiently recycled by using displacement batch cooking techniques.

In view of the total chemical balance of modern kraft pulp mills, new concepts have emerged. Instead of caustic purchased from outside, caustic should be produced inside the mill chemistry. This is becoming increasingly important as bleaching methods under development use less chlorine and more caustic than conventional methods.
The decline of the chlorine / alkali industry, the cost of cleaning caustic and the problem of mills to maintain chemical balance, and sufficient external sodium uptake will add to the alkali production required for some pulp mills.

[0010]

A solution to the above problem relates to a pulp mill by diverting part of the green liquor to a step for carbonate crystallization and then causticizing the separated carbonate crystals. One part of the desire is to produce pure caustic (NaOH). The remaining mother liquor contains residual carbonate, but
All original sulfides are also present in green liquor. This mother liquor is now, for example, injected into the front end of the steam,
Its new use in improving displacement kraft batch cooking was found directly. Initially, it was proposed to separately causticize the mother liquor to produce high sulfide white liquor, but this would further complicate the pulp mill process. A typical configuration in modern mill-manufactured bleached kraft pulp is 20% of the total green liquor output after the recovery boiler.
% Would require a green liquor amount for crystallization, which should be set to% (the remaining 80% should be causticized to white liquor, conveniently for cooking). This means that NaOH per ton of oven dried wood
Equivalent to 25 kg, ie typically compensate for the caustic consumption of oxygen bleaching and alkaline extraction steps,
It will produce pure caustic for bleaching, equivalent to about 60 kg of NaOH per metric ton of air-dried pulp. The resulting crystallization mother liquor volume for use in steaming is 16 kg EA (NaOH) / kg wood and 0.1 kg.
0.11 liquor with 23 moles HS / kg wood-to-liq-to-wood units. Of course, the percentage of green liquor and the production of pure caustic may vary from case to case.

[0011]

SUMMARY OF THE INVENTION A small amount of non-caustic cooked liquor (green liquor, or a derivative thereof, such as a mother liquor obtained from green liquor carbonate crystallization).
Is added to the front end of the black liquor recycle displacement kraft batch process (i.e., to the impregnation and / or hot black liquor pre-treatment step) to a lesser amount than would otherwise be required. It has now been found that pulping properties can be improved in terms of the optimized cooking phase using white liquor, improved pulp strength and bleaching degree. It is very practical to use green liquor as it is always available in the pulp mill. It is very practical to use the mother liquor obtained from the green liquor carbonate crystallization, in which case the pure caustic for the oxygen delignification and alkaline bleaching steps is the carbonate obtained from green liquor. Manufactured from

[0012]

FIG. 1 is a block diagram of a kraft replacement batch cooking system. This figure defines the necessary tanks, flows and procedures of the steaming process. In order to clarify the conventional replacement batch cooking technique, the following description will be given. Kraft batch cooking is started by putting wood chips into a digester, then filling the digester with black liquor AA from the impregnated black liquor tank 5 and allowing the chips to absorb. An overflow (A2) to the black liquor tank 4 (point AB) is preferred to remove the diluted front of air and liquor. After closing flow A2,
The digester is pressurized and impregnation is complete. The steaming process is then continued by pumping hot black liquor B from hot black liquor tank 1. Colder black liquor A3 replaced by hot black liquor
Is introduced into the black liquor tank 4 (point AB),
The steamed chemicals are transferred to an evaporation plant for recovery. The cooking procedure is continued by pumping hot white liquor C from tank 3 into the digester. The liquor (D 2) replaced by the hot liquor having a boiling point substantially equal to or higher than the normal pressure is introduced into the hot black liquor tank 2. After the filling procedure, the digester temperature approaches the final cooking temperature. The final heating ramp is performed using direct or indirect steam heating and digester recirculation. After the desired cooking time, when the delignification has proceeded to the desired degree of reactivity, the used liquor has already been replaced by the washing filtrate E. In the final displacement, the first part B1 of the displaced hot black liquor corresponds to the total volume B required for the filling process. The second part D1 of the substituted black liquor, which is diluted by the washing filtrate E, but is still approximately above normal pressure, is introduced into the hot black liquor tank 2 (point D). After the completed final displacement, the contents of the digester are discharged for further processing of the pulp. The above cooking procedure may then be repeated.

The hot black liquor tank 2 provides cold impregnated black liquor to the tank 5 by transferring the heat to white liquor and water by heat exchange.

Tank 6 is provided for storage of green liquor or derivatives thereof supplied from the cooking chemical recovery plant. According to the invention, at least one of the parts X1 to X3 of green liquor or derivatives thereof is introduced in the impregnation and / or pretreatment step.

[0015]

EXAMPLES AND EFFECTS OF THE INVENTION In accordance with the present invention, a non-caustic alkalinized cooking liquor (green liquor) in the impregnation and pretreatment "front end" of a displacement kraft batch cooking process.
Or the addition of a derivative thereof, as well as the finishing of the delignification step using white liquor addition, resulting in an improvement in the process of kraft pulping by the kraft batch process, which results in improved pulp quality due to milder cooking conditions. Now offered.

In the following, reference is made to the figures described in the previous section.

In one embodiment of the method of the present invention,
The volume X1 of 1.0 L green liquor / kg oven-dried wood (corresponding to 0.15 to 0.7 mol HS ⁻ / kg oven-dried wood) is measured at a temperature between about 90 ° C. and 100 ° C., and about 30 ° C. Before performing the impregnation using a time of ６０60 minutes, add from tank 6 to warm black liquor AA for impregnation from tank 5.

In a second embodiment of the method of the present invention, 0.2
１．０1.0 L green liquor / kg oven-dried wood volume X2 (corresponding to 0.15-0.7 mol HS ⁻ / kg oven-dried wood) is first added from tank 6, for example to a digester, then impregnated Hot black liquor AA is added, followed by an impregnation using a temperature between about 80 ° C. and 100 ° C. and a time of about 30-60 minutes.

In a third embodiment of the process of the invention, a warm black liquor impregnation is performed as described in the prior art, followed by a 0.2-1.0 L green liquor / kg oven-dried wood volume X3 (0.15 0.7 mol HS ^-
/ Kg of oven-dried wood) from tank 6 to hot black liquor B, then hot black liquor treatment is carried out at a temperature between 145 ° C and 165 ° C, and about 1 ° C.
Perform using a time of 5 to 30 minutes.

In a fourth embodiment of the process according to the invention, the volume of the mother liquor X1 (0.06
~ 0.4L / kg oven dried wood, 0.15 ~ 0.7
Mol HS ⁻ / kg corresponding to oven-dried wood) from tank 6 to warm black liquor AA for impregnation,
Then a temperature between about 90 ° C and 100 ° C, and about 30-
The impregnation using a time of 60 minutes is performed.

In a fifth embodiment of the process according to the invention, the volume of the mother liquor X2 (0.06
~ 0.4L / kg oven dried wood, 0.15 ~ 0.7
Mol HS ⁻ / kg oven-dried wood) is added from tank 6, for example to a digester, then warm black liquor AA for impregnation is added, then at about 80 ° C. and 100 ° C.
The impregnation is carried out using a temperature between 0 ° C. and a time of about 30-60 minutes.

In a sixth embodiment of the process according to the invention, a warm black liquor impregnation is carried out as described in the prior art, followed by a mother liquor volume X3 (from 0.06 to 0.4 L / kg) obtained from green liquor crystallization. Oven dried wood,
0.15 to 0.7 moles HS ⁻ / kg, corresponding to oven-dried wood) from tank 6 to the hot black liquor and then hot black liquoring is carried out at 145 ° C. and 16 ° C.
Performed using a temperature between 5 ° C. and a time of about 15-30 minutes.

If a non-caustic cooking liquor is added in the impregnation step of the present process, it may be necessary to further utilize the chemicals and to avoid having too high a residual alkali concentration in the feed to the evaporator. Higher temperatures should be used. The higher impregnation temperature required can be achieved by using either digester recirculation and direct or indirect steam heating, or by supplementing a small amount of hot black liquor B from tank 1 to impregnated black liquor AA. -adding).

If a non-caustic cooking liquor is added to the hot black liquor, the temperature of the liquor is:
High enough to provide the desired reaction temperature.

A major advantage of the process of the present invention is that the "front end" of the kraft displacement batch cooking is more effective. This makes cooking with white liquor in the "rear end" of kraft displacement batch cooking much easier, requires milder rear end cooking conditions, and reduces pulp strength and easier bleaching of the pulp. The pulp quality is improved because improved pulp quality is obtained.

Furthermore, the practice of the process according to the invention is advantageous for at least the following reasons: Unlike the prior art, no extra cooking step is required in the cooking procedure. The practice of the present invention does not require discontinuation of production, as the steaming process shown is an improvement only and does not require any major equipment modifications. In response to the improved cooking process, the demand for white liquor has decreased, and reduced cooking times have increased production. The required amount of non-causticized liquor as green liquor is small enough to be handled by conventional sized evaporation systems. The overall load on the recovery system does not increase in response to increased green liquor use as the causticized cooking liquor is reduced. -The use of mother liquor from green liquor carbonate crystallization is very advantageous from the point of view of the chemical balance of modern kraft pulp mills. Causticizing the carbonate separated in the same place produces the pure caustic required in modern bleaching of kraft pulp. The amount of caustic purchased from outside has been significantly reduced,
And the chemical balance is maintained.

The following examples are illustrative of the present invention and demonstrate the advantages over the prior art kraft batch displacement cookers having a black liquor front end.

The following abbreviations are used in this example: Ｅ EA Effective alkali = NaOH + 1/2 Na ₂ S, expressed as NaOH equivalent AA Active alkali = NaOH + Na ₂ S, expressed as Na ₂ O equivalent WBL Warm impregnated black liquor OWBL Oven flow WBL DWBL Replacement (removal) ) WBL HBL hot black liquor RHBL substituted (removed) HBL WL white liquor, caustic treated cooking liquor DL end-substituted liquor GL caustic untreated cooking liquor, “green liquor” xGL GL from carbonate crystallization Mother liquor O oxygen delignification process D chlorine dioxide bleaching process E alkali extraction process ───────────── ────────────────────── results and advantages of the present invention is summarized in the table below.

Table 2: Results summary of the examples. All experiments were cooked at a constant kappa number of 20 and 20 g EA / L cooking end balance. Factor Control Method Method Method Method Example 1 Example 2 Example 3 Example 4 Example 5 ────────────────────────────────── ── Additional liquor None GL GL GL GL Dose (liq-to-wood units) None 0.5 0.5 0.5 0.11 White liquor dose (% EA on OD material) 20.7 16.3 17.1 16.5 17.3 H-factor requirement 1006 980 1008 1017 978 Screen Yield (%) 43.6 43.4 43.4 43.9 43.2 Viscosity (ml / g) 1052 1041 1081 1088 1035 Unbleached pulp strength, tear index at 90 mN / g (mNm ² / g) 14.7 16.2 16.2 15.8 16.4 89% ( Effective chlorine consumption rate in ISO (kg act.Cl/ODtxkappa) 4.2 4.2 3.7 3.8 3.7 Brightness ceiling (% ISO) 90.1 90.1 90.5 90.3 90.9 Bleached pulp strength, tensile 90 mN / g (mNm ² / g) Tear index at 14.0 15.0 16.4 15.3 16.4

Based on the results in the table, the present invention offers the following surprising benefits over the same prior art cooking method. By using a small volume of a non-caustic undistilled cooking liquor at the front end of the displacement kraft batch cooking according to the methods shown in Examples 2 to 5, White liquor) can be reduced by 20%, while pulp yield, viscosity and H-factor requirements (ie cooking time) remain unchanged; unbleached pulp strength increases by 10%; Bleach chemical consumption is reduced by 10%; brightness sailing (ie, the highest attainable brightness) is increased; and pulp strength levels are maintained during pulp bleaching.

Example 1 Production of ordinary "control" pine kraft pulp by using displacement kraft batch technology pine (Pinus sylvestris)
3.5 kg chips (oven dried substrate) were weighed into a chip basket placed in a 20 liter jacketed displacement batch digester with forced circulation. Close the digester lid, then chip under atmospheric pressure for 100
Steamed at 10 ° C for 10 minutes. Impregnated black liquor (WB
L, 80-90 ° C., 8 g EA / L) was pumped with some overflow (OWBL) for 20 minutes and then impregnated at 80 ° C. under 5 bar pressure for 20 minutes. After impregnation, hot black liquor (HBL, 165
C, 20 g EA / L) was introduced into the bottom of the digester, and the used impregnated black liquor (DWB) was introduced from the tip of the digester.
A hot black liquor pretreatment step was performed by displacing L). After a 20 minute hot black liquor step, hot white liquor (105 g EA (NaOH) /
L; 40% sulphide) The dose was introduced into the bottom of the digester to displace the equivalent volume of spent hot black liquor (RHBL) from the top of the digester. When heated and heated for 25 minutes while circulating, the temperature rises from 155 ° C
The temperature rose to 70 ° C. After a desired cooking time sufficient to sufficiently fill the desired H-factor, the washing buffer DL (0.02 M Na
₂ CO ₃ /L+0.05 mol Na ₂ S / L) The terminal substitution was started by introducing into the bottom of the digester and displacing hot spent black liquor from the digester tip. First replaced part of hot black liquor (HBL1)
Supplemented the 17 L volume required for the next cooked hot black liquor dose. The second part of the liquor displaced (BL2) made up for the 13 L volume required for lowering the temperature and for the impregnating liquor for the next steam. After end displacement, the pulp was degraded, washed with deionized water, examined and analyzed. This cooking procedure was repeated three times by returning the displaced liquor to the next cooking. By these means, an equilibrium in the cooking process was obtained, and the cooking was repeated the same, corresponding to an industrial batch cooking system. In all the steaming experiments,
The cooking conditions were adjusted so that the kappa number obtained was 20 and the residue EA at the end of the cooking step was 20 g EA / L. Table E1.1 below. Shows the amount of liquor input and output (volume in liters) and the conditions of the corresponding cooking step. Unbleached pulp was analyzed by beating and testing for overall yield, screened yield, kappa number, viscosity, brightness and pulp strength. In addition, unbleached pulp is
Bleached using the decolorization procedure OD-Eop-DED. The bleaching chemical requirements for a given pulp brightness were determined, and the pulp strength was measured by beating and testing. Table E1.2. Shown in Table E1.3. Steaming properties and results. Shown in

Table E1.1. Liquor input and output and corresponding steaming process conditions in Example 1. Volumes are given in liters. Liquid inlet Bleeding manufacturing process WBL 30.7 OWBL 12 Warm black liquor impregnation 80 ° C., 40 min HBL 13.3 DWBL 13.5 Hot black liquor pretreatment 155 ° C., 20 min HWL, RHBL apr upon administration Apr.7 + hot white liquor fill 3.5 HBL. 10 DL 30 HBL 17 Terminal substitution BL2 13

Table E1.2. Conditions of bleaching process in all cases Process O D0 Eop D1 E D2 Time (min) 90 30 120 180 90 240 Temperature (° C) 105 60 70 75 60 75 Consistency (%) 10 10 12 12 12 12 Pressure (bar) 6 ( O ₂ ) Atmospheric pressure 2 (O ₂ ) Atmospheric pressure Atmospheric pressure Atmospheric pressure Atmospheric pressure NaOH 1.1-1.2-0.6xD0 0.5-0.5-(%) Act.Cl 30 MgSO ₄ 0.5------ClO ₂ ,-0.2-Variable- variable _{AcCl (%) H 2 O 2} - 0.3 - - -. final pH 11 2 3.5-4 3.5-4 kappa, 40-45 red (%)

Table E1.3. Result of Example 1. Steamed , non-caustic cooked liquor, 0 (TA-to-wood unit) 0 (TA, total alkali (NaOH) 0) White liquor dose [EA,% (NaOH)] 20.7 H-factor 1006 kappa number 20 Cooking residue [gEA (NaOH) / L] 20 Screened yield (%) 43.6 SCAN viscosity (mL / g) 1052 ISO brightness (%) 34.0 Tear index (mNm ² ) at a tensile index of 90 Nm / g / G) 18.3

[0035] Bleaching effective chlorine consumption ratio 89% with respect to (ISO) brightness, [kg Act.Cl/(ODtonxkappa] 4.2 Brightness Sailing (% ISO) 90.1 ISO89% SCAN Viscosity at luminance (mL / g) 765 tear index at 90 Nm / g (mNm ² / g) 14

Example 2 The experiment was carried out as described in Example 1 except that a 0.5 liquor vs. wood unit non-caustic cooking liquor was used as follows. After steaming the chips, a new liquor array was introduced for impregnation. First add 18.7 liters of WBL (90 ° C.), then 3.5 liters of 0.5 liquor to wood unit (1.75 liters) non-caustic cooked liquor GL (90 ° C.) Of WBL (168 ° C.).
In this case, hot black liquor was used to raise the impregnation temperature to 100 ° C. Table E2.1. Shows the liquor volume and conditions. Fill liquor over 20 minutes, then
While circulating in the digester, impregnation was carried out at 100 ° C. and 5 bar for 40 minutes. Since the amount of WBL (18.7 liters) has been reduced, the WBL consists only of RHBL and BL2, the second part of the terminally substituted liquor. . The improved results for Control Example 1 are shown in Table E2.2. Shown in

Table E2.1. Liquor input and output and corresponding cooking process conditions in Example 2. Volumes are given in liters. Liquid inlet Bleeding manufacturing process WBL 18.7 Warm black liquor impregnation GL 1.75 90/100 ℃, 60 min HBL 3.5 OWBL 5.25 HBL 13.5 DWBL 13.5 Hot black liquor pretreatment 155 ° C., 20 min HWL, administration Apr.7 + hot white liquor fill 3.5 HBL-based RHBL apr.10 DL 30 HBL1 17 Terminal substitution BL2 13

Table E2.2. Result of Example 2. Steamed non-caustic cooked liquor, 0.5 (TA to wood, 9 as total alkali (NaOH)) White liquor dose [EA,% (NaOH)] 16.3 H-factor 980 Kappa number 20 Cooking residue [gEA (NaOH) / L] 20 Yield screened (%) 43.4 SCAN viscosity (mL / g) 1041 ISO brightness (%) 33.9 Tensile index Tear index at 90 Nm / g ( mNm ² / g) 16.2

[0039] Bleaching effective chlorine consumption ratio 89% with respect to (ISO) brightness, [kg Act.Cl/(ODtonxkappa] 4.2 Brightness Sailing (% ISO) 90.1 ISO89% SCAN Viscosity at luminance (mL / g) 763 Tear index (mNm ² / g) at a tensile index of 90 Nm / g 15

Example 3 The experiment was carried out as described in Example 1 except that a 0.5 liquor vs. wood unit non-caustic cooking liquor was used as follows. After steaming the chips, a new liquor array was introduced for impregnation. Prior to introducing any WBL, 0.5 liquor to wood unit (1.75 liters) of non-caustic cooked liquor GL (90 ° C.) is introduced into the bottom of the digester over 10 minutes. And then over 20 minutes, 23 liters of WBL
And then, while circulating in the digester,
Impregnation at 40 ° C. and 5 bar for 40 minutes. Table E3.1. Shows the liquor volume and conditions. Instead of a mixture of WBL and GL, the GL may be contacted with the first steamed chip and the chip may be impregnated in a more diluted environment. The improved results for Control Example 1 are shown in Table E3.2. Shown in

Table E3.1. Liquor input and output and corresponding steaming process conditions in Example 3. Volumes are given in liters. Liquid inlet Bleeding manufacturing process GL 1.75 warm black liquor impregnation WBL 23 OWBL 6 90 ℃, 60 min HBL 13.5 DWBL 13.5 Hot black liquor pretreatment 155 ° C., based on 20 minutes HWL, administration Apr.7 + hot white liquor fill 3.5 HBL RHBL apr.10 DL 30 HBL1 17 Terminal substitution BL2 13

Table E3.2. Result of Example 3. Steamed non-caustic cooked liquor, 0.5 (TA vs. wood units) 9 (TA, total alkali (NaOH) 9 White liquor dose [EA,% (NaOH)] 17.1 H-factor 1008 Kappa number 20 Cooking residue [gEA (NaOH) / L] 20 Yield screened (%) 43.4 SCAN viscosity (mL / g) 1081 ISO brightness (%) 34.0 Tensile index Tear index at 90 Nm / g ( mNm ² / g) 16.2

[0043] Bleaching effective chlorine consumption ratio 89% with respect to (ISO) brightness, [kg Act.Cl/(ODtonxkappa] 3.7 Brightness Sailing (% ISO) 90.5 ISO89% SCAN Viscosity at luminance (mL / g) 813 Tear index (mNm ² / g) at a tensile index of 90 Nm / g 16.4

Example 4 The experiment was carried out as described in Example 1 except that a 0.5 liquor vs. wood unit non-caustic cooking liquor was used as follows. The impregnated part of this method was performed in the same manner as described in Example 1, except that the volume of WBL was 24 liters. 0.5 liquor to wood units (1.75 liters) of non-caustic cooked liquor GL (90 ° C.) was introduced in the hot black liquor treatment together with the hot black liquor.
In all other respects, this step was identical to the one described in Example 1. Table E4.1. Shows the liquor volume and conditions. The results improved over Control Example 1 are shown in Table E4.2.
Shown in

Table E4.1. Liquor input and output and corresponding steaming process conditions in Example 4. Volumes are given in liters. Liquid inlet Bleeding manufacturing process WBL 24 OWBL 5 Warm black liquor impregnation 80 ° C., 40 min HBL 13.3 DWBL 15.5 Hot black liquor pretreatment GL 1.75 155 ° C., based on 20 minutes HWL, administration Apr.7 + hot white liquor fill 3.5 HBL RHBL apr.10 DL 30 HBL1 17 Terminal substitution BL2 13

Table E4.2. Result of Example 4. Non- caustic cooked cooking liquor, 0.5 as (liquid-to-wood unit) 0.5 (TA, 9 as total alkali (NaOH) White liquor dose [EA,% (NaOH)] 16.5 H-factor 1017 Kappa number 20 Cooking residue [gEA (NaOH) / L] 20 Yield screened (%) 43.9 SCAN viscosity (mL / g) 1088 ISO brightness (%) 33.5 Tensile index Tear index at 90 Nm / g ( mNm ² / g) 15.8

[0047] Bleaching effective chlorine consumption ratio 89% with respect to (ISO) brightness, [kg Act.Cl/(ODtonxkappa] 3.8 Brightness Sailing (% ISO) 90.3 ISO89% SCAN Viscosity at luminance (mL / g) 786 Tear index at 90 Nm / g tensile index (mNm ² / g) 15.3

Example 5 The experiment was carried out as described in Example 1 except that a non-caustic cooked liquor from GL carbonate crystallization was used as follows. After steaming the chips, a new liquor array was introduced for impregnation. Prior to introducing any WBL, a 0.11 liquor of the mother liquor xGL that is not causticized versus a unit of wood (0.39 liter, 90 ° C.) is introduced into the bottom of the digester over 10 minutes. Then, over a period of 20 minutes, 23 liters of WBL were introduced and then impregnated at 90 ° C. and 5 bar for 30 minutes while circulating in the digester. Table E5.
1. Shows the liquor volume and conditions. The improved results for Control Example 1 are shown in Table E5.2. Shown in

Table E5.1. Liquor input and output and corresponding steaming process conditions in Example 5. Volumes are given in liters. Liquid inlet Bleeding manufacturing process Xgl 0.39 warm black liquor impregnation WBL 23 OWBL 5 90 ℃, 60 min HBL 13.5 DWBL 13.5 Hot black liquor pretreatment 155 ° C., based on 20 minutes HWL, administration Apr.7 + hot white liquor fill 3.5 HBL RHBL apr.10 DL 30 HBL1 17 Terminal substitution BL2 13

Table E5.2. Result of Example 5. Steamed , non-caustic cooked liquor, 0.11 as (liquid vs. wood unit) (TA, 2.9 as total alkali (NaOH) 2.9 White liquor dose [EA,% (NaOH)] 17.3 H- Factor 978 Kappa number 20 Cooking residue [gEA (NaOH) / L] 20 Yield screened (%) 43.2 SCAN viscosity (mL / g) 1035 ISO brightness (%) 31.4 Tear at tensile index 90 Nm / g Index (mNm ² / g) 16.6

[0051] Bleaching effective chlorine consumption ratio 89% with respect to (ISO) brightness, [kg Act.Cl/(ODtonxkappa] 3.7 Brightness Sailing (% ISO) 90.9 ISO89% SCAN Viscosity at luminance (mL / g) 773 Tear index at 90 Nm / g tensile index (mNm ² / g) 16.4

[Brief description of the drawings]

FIG. 1 is a block diagram of a kraft replacement batch cooking system.

Claims (10)

[Claims] 1. The following steps: a step of adding a fixed volume of a non-caustic alkalinized cooking liquid to a container containing a cellulose raw material; filling a used cooking liquid into the container and cooking the non-caustic alkalinized raw material into the cellulose raw material Impregnating the mixture obtained from the liquor and the spent cooking liquor; replacing the liquor used for the impregnation with another fixed volume of hot spent cooking liquor, and then replacing the cellulosic feedstock with said another Pretreating with a fixed volume of hot spent cooking liquor; replacing the liquor used for the pretreatment with a causticized hot cooking liquor and then replacing the cellulosic material with said causticized hot cooking liquor Steaming with the cooking liquor to the desired degree of delignification; replacing the liquor used for the cooking with the washing filtrate, for pre-treatment of the cellulose raw material and subsequent separate filling steps of the batch A first volume of hot spent cooking liquor, corresponding to the total volume required for the desired addition in step 1, is collected, and then the replacement liquor to be cooled and to be used in the impregnation of the cellulosic feedstock in the subsequent batch Collecting a second volume; a batch process for producing kraft pulp from a lignin-containing cellulosic material. 2. A process according to claim 1, wherein the amount of non-caustic cooking liquor added corresponds to 0.2-1.0 L / kg oven-dried wood. 3. The non-caustic alkaline cooking liquor used is a mother liquor obtained by crystallization of carbonate from the non-caustic alkaline cooking liquor, and the amount added is 0.06 to 0.06.
2. The method according to claim 1, corresponding to 0.4 L / kg oven dried wood. 4. The following steps: filling a vessel containing a cellulose raw material with a used cooking liquid to which a certain amount of a cooking liquid that is not causticized is added;
Impregnating the obtained liquor; replacing the liquor used for the impregnation with another fixed volume of hot spent cooking liquor, then pretreating the cellulose raw material with said liquor; Replacing the liquor used in the above with a causticized hot cooking liquor, and then steaming the cellulosic material using the causticized hot cooking liquor to the desired degree of delignification; The spent liquor is replaced by a washing filtrate and the hot spent cooking liquor corresponding to the total volume required for pretreatment of the cellulosic feedstock and for the desired addition in a separate filling step of the subsequent batch Collecting a first volume of the lignin-containing cellulose feedstock, and then collecting a second volume of the replacement fluid to be cooled and to be used in the impregnation of the cellulose feedstock in a subsequent batch. Batch method for producing Futoparupu. 5. The process as claimed in claim 4, wherein the amount of non-caustic cooking liquor added corresponds to 0.2 to 1.0 L / kg oven-dried wood. 6. The non-caustic alkaline cooking liquor used is a mother liquor obtained by crystallization of carbonate from the non-caustic alkaline cooking liquor, and the amount added is 0.06 to 0.06.
5. The method according to claim 4, corresponding to 0.4 L / kg oven dried wood. 7. The following steps: filling a vessel containing a cellulose raw material with used cooking liquor; impregnating the cellulose raw material with the used cooking liquor; using the above used for the impregnation. The cooked liquor is replaced with another fixed volume of hot used cooking liquor to which a fixed volume of non-caustic cooking liquor has been added, and then the cellulosic material is separated from the non-causticized cooking liquor and used cooking liquor. Pretreating with the resulting mixture; replacing the liquor used for the pretreatment with a causticized hot cooking liquor, and then replacing the cellulosic raw material with said causticized hot cooking liquor Steaming to the desired degree of delignification; replacing the liquor used for cooking with the washing filtrate, for pre-treatment of the cellulose raw material and for subsequent filling steps of the batch. The first volume of hot spent cooking liquor, corresponding to the total volume required for the desired addition in the batch, is collected and then replaced with the replacement liquor to be cooled and to be used in the impregnation of the cellulosic feedstock in the subsequent batch. Collecting a second volume; a batch process for producing kraft pulp from a lignin-containing cellulosic material. 8. The process according to claim 7, wherein the amount of non-caustic cooked liquor added corresponds to 0.2-1.0 L / kg oven-dried wood. 9. The non-caustic cooking liquor used is a mother liquor obtained from the crystallization of carbonate from the non-caustic-alkaline cooking liquor, and the amount added is 0.06 to 0.06.
8. The method according to claim 7, corresponding to 0.4 L / kg oven dried wood. 10. The method according to claim 7, wherein a part of green liquor or a derivative thereof is further introduced according to claim 1 or claim 4.