The continuous replacing and digesting technoloy of dissolving pulp
Technical field
The present invention relates to the continuous replacing and digesting technoloy of a kind of dissolving pulp, to adopt traditional vertically digesting equipment, in conjunction with the continuously cooking technology, make fibrous raw material make dissolving pulp (chemical fiber pulp), and reach energy-saving and environmental protection, improve output and quality, fall low consumed purpose.Belong to textile industry pulping technique field.
Background technology
The main raw material(s) of producing viscose is linter pulp and dissolving pulp, in recent years because factors such as sown areas of cotton minimizings, the linter pulp increment seldom, so dissolving pulp becomes the unique raw material sources that increase viscose.Dissolving pulp is through purer wood pulp, straw pulp behind bleaching, the extraction organic solvent etc.It has removed lignin, hemicellulose through acidolysis, keeps chemical cellulose.
Domestic present dissolving pulp manufacturing enterprise more than 90% still adopts single pot of mode boiling of tradition, first under low temperature environment, fill pot, be incubated when utilizing thermal source that digester is heated to 170 ℃, after the H factor (temperature and time relative reaction rate in the digestion process) reaches requirement, namely the slurries in the digester can be discharged, finish the boiling of one pot of paper pulp.Just can carry out the production of next pot because this mode need to be got rid of cooking liquor when cooking liquor reaches 170 ℃, cause the huge waste of heat energy.The steam consumption of tradition vertically digesting is (4~4.5t vapour/t slurry) approximately; The omnidistance cycle of boiling dissolving pulp long (18-20 hour/pot).
In the eighties in last century, the Radar company of Sweden and U.S. Beloit company have developed a kind of boiling method cooperatively, with the hot black liquor collection storage in the digester, and its heat energy of reuse in next digester cycle then.
Similarly boiling mainly contains following three kinds of methods at present:
1, RDH Rapid replacement cooking process.
2, SuperBatch SuperBatch cooking method.
3, DDS displacement cooking method.
The patent of RDH belongs to U.S. GLV company, and the patent of SuperBatch belongs to Finland Metso company, and the patent of DDS belongs to U.S. CPL company.The technology similar in China still is in blank.
The basic principle of these methods is identical, wherein best with the DDS cooking effect, generally be that a plurality of digesters are linked together by the pipeline circulation, the pipeline between adjacent two digesters is provided with reservoir, and the volume of 1 reservoir needs 3 times of digester capacity.The cooking liquor that reservoir inside groove storage temperature is lower, the cooking liquor that the water jacket storage temperature is higher.But the use grooving is when the large build-up of pressure of the unbalanced or inside and outside liquid storage amount of external and internal pressure difference can cause groove to be damaged by pressure or flatten.
This technique has reduced energy consumption, contain remaining chemicals in the liquid of circulation, increased the selective of cooking reaction, can remove (boiling is to lower card valency) to more lignin in the raw material and increase the intensity of fiber, reduce the removal amount at the bleachery lignin, be easy to bleaching.
Although this mode has effectively been saved heat energy,, large volume reservoir all is set between each digester, can cause area of mill site larger, equipment investment is higher.
Summary of the invention
The purpose of this invention is to provide the continuous replacing and digesting technoloy of a kind of dissolving pulp, energy-conservation and can eliminate when putting pot waste gas to the pollution of environment.
Solution of the present invention is characterized in that, described method is: a plurality of digesters are in respectively different operations, during work, set the sour time swap t2 of all digesters, in to reclaim time swap t9 all identical with time swap t5 and alkali, adjust the zero-time between each digester, so that each time swap overlaps; When to digesting technoloy when the time, coincide point began to replace, open simultaneously cooking liquor import and the cooking liquor outlet of each pot that needs displacement, and with the headstock gear of cooking liquor reservoir, so that the digester of each displacement is sent into the liquid that needs and the equal cooking liquor of the total amount that displaces simultaneously, reach continuous displacement; After displacement is finished, close simultaneously each headstock gear, enter subsequent handling, wait for next time time swap.
Particularly, adopt a plurality of digesters with cooking liquor import, cooking liquor outlet, each pot has and overlaps the independently cooking liquor circulatory system, each digester inputs or outputs to liquid storage by on-off structure control cooking liquor liquid storage independently and fills with, each digester is connected with the cooking liquor heater, each digester bottom is provided with the slurry outlet, it is characterized in that: the cooking liquor outlet of each digester all directly communicates by the cooking liquor displacement import of each digester of pipeline and other, and any two or more digesters all form closed circulation and connect;
Described reservoir is the hot acid liquid bath; Hot black liquor; Hot water storgae; Cold white liquid bath; The white liquid bath of heat and dilution liquid bath.The volume of each reservoir is 1.5-2 times of digester.Each digester is connected with heater, and each digester bottom is provided with the slurry outlet.Each pot has and overlaps the independently cooking liquor circulatory system, uses in normal boiling.
For energy savings consumption, described cooking liquor liquid storage (black liquor of High Temperature High Pressure) is by heat exchanger heating white liquid or running water, cooking liquor liquid storage after the heat exchange enters liquid storage and fills with, hot water is then delivered to other by hot-water line and need to be used with the place of hot water, carry out the pulp washing operation in the pulp washing operation behind the digesting technoloy as it being delivered to, to take full advantage of the energy.
The technique of a digester cycle is as follows:
(1) pot filling: send into hot water more than 95 ℃ in the time of the dress pot, the limit charging, the limit liquor charging, until pot is filled, this moment, kettle temperature was T1;
(2) acid displacement: with hot water V
1With hot acid liquid V
2Digester bottom input from filling displaces hydrolyzate V from the top
3Deliver to reservoir; This boiling kettle temperature is warming up to T2 from T1; Time swap t2;
(3) hydrolysis heats up: pass into steam and be warming up to T3, t3 consuming time heats up;
(4) hydrolysis insulation: temperature T 4=T3, temperature retention time t4;
(5) neutralization displacement: the white liquid V of heat that sends here from the white liquid bath of heat first
4Rapidly and acid solution; Subsequently respectively with hot black liquor V
5The heat white liquid V additional with needs
6From the input of digester bottom, displace hot acid liquid V from the top
7, so that the boiling kettle temperature is down to T5, time swap t5;
The hot acid liquid V that displaces
7Send into another digester that needs hot acid liquid or hot acid liquid bath;
The neutralizer V that displaces
8Send evaporation section, reclaim salt;
The hot black liquor V of the pH that displaces 〉=7
9Enter the hot black liquor groove;
(6) neutralization insulation: holding temperature T6=T5, temperature retention time t6;
(7) soda boiling heats up: through heater with steam direct heating to T7, heat time heating time t7;
(8) soda boiling insulation: temperature T 8=T7, soda boiling time t8;
(9) alkali reclaims displacement: after cooking reaction reaches terminal point, and pulp washing filtrate V
10Send into the digester bottom, the top displaces the hot black liquor V more than 160 ℃
11, warm black liquor V
12To comprehensive groove; Displacement is down to T9 below 100 ℃ to last kettle temperature by T8; T9 during time swap;
(10) put pot: 80 ℃ of rare black liquor of dilution pumping are extracted out with pulp pump and are sent spraying pot to, and the temperature t 10 when putting pot is lower than 95 ℃, put to be lower than 80 ℃ after pot is finished, and can load pot, and a pot time t10 is put in the operation boiling that next time circulates;
During work, the digesting technoloy of setting each digester is accomplished to from filling and sets identical process conditions before putting pot, and it is all identical to set 3 time swaps of all digesters: t2=t5=t9; Adjust the time interval between each digester, so that time swap overlaps, namely have at least two pots to be in operation 2 acid displacements, the operation 5 and displacement or operation 9 alkali recovery displacement at time swap, and time swap overlaps;
When to when the time, coincide point began to replace, open simultaneously cooking liquor import and the cooking liquor outlet of each pot that needs displacement, and with the headstock gear of cooking liquor reservoir, so that the digester of each displacement is sent into the liquid that needs and the equal cooking liquor of the total amount that displaces simultaneously, reach continuous displacement; After displacement is finished, close simultaneously each headstock gear, enter subsequent handling, wait for next time time swap.
An embodiment of the invention are:
T1=60℃-70℃;t1=30-90min;
T2=150-155℃;t2=25-40min;
T4=T3=170-175℃,t3=20-30min;t4=120-240min;
T6=T5=150-160℃,t5=20-40min,t6=2-30min;
T8=T7=165℃-175℃,t7=20-40min;t8=30-90min;
Below T9=100 ℃, t9=20-40min;
T10 is lower than 95 ℃, t15-20min.
Further, during displacement
V
1+ V
2Remaining space=V in the-pot
3
V
4+V
5+V
6=V
7+V
8+V
9;
V
10=V
11+V
12。
Wherein, the V that displaces of operation 9
11Namely as V
5Send in the pot of operation 5, remaining part is sent into the hot black liquor groove; The V of operation 5 displacings
7Namely as V
2Send in the pot of operation 2, remaining part is sent into the hot acid liquid bath, and each conveyance conduit is by the flowmeter autocontrol valve.
As preferably: in each digester, have simultaneously 3 pots to overlap in operation 2,5,9 times, realize a pair of two displacements.
Such as, adopt 4 digester A, B, C, D, wherein each displacement has three pots to replace continuously, and another pot is in holding stage:
When the A pot is in the initial of operation 2 acid displacement, the B pot is in the operation 5 and displacement initial, and the C pot is in cooking reaction and reaches terminal point, and operation 9 alkali reclaim the initial of displacement, and the D pot is in other operation;
Open simultaneously corresponding valve, so that C pot bottom input pulp washing filtrate V
10, the hot black liquor V more than 160 ℃ that the top displaces
11As V
5Directly send into the B pot bottom, remaining part is sent into the hot black liquor groove, warm black liquor V
12Deliver to comprehensive groove;
160 ℃ of-170 ℃ of hot acid liquid V that B pot top displaces
6, V wherein
2From A pot bottom input A pot, the hydrolyzate V that A pot top displaces
3Enter reservoir;
After time swap reached, valve-off finished the displacement of A pot operation 2, B pot operation 5, C pot operation 9 simultaneously, until next time displacement: the A pot reaches operation 5, and the B pot reaches operation 9, and the D pot reaches operation 2, carried out above-mentioned similarly simultaneously displacement ... the rest may be inferred.
Another embodiment of the present invention: in each digester, have simultaneously 2 pots to overlap in operation 2,5, realize one to one displacement.Such as: adopt 4 digester A, B, C, D,
When the A pot is in the initial of operation 2 acid displacement, the B pot is in the operation 5 and displacement initial, and C pot D pot is in other operation; Open simultaneously corresponding valve, so that the hot black liquor that the hot black liquor groove comes is sent into the operation 5 of carrying out the B pot and displacement from the B pot bottom, the hot acid liquid V that B pot top displaces
6Carry out the operation 2 acid displacements of A pot, the hydrolyzate V that A pot top displaces from the input of A pot bottom
3Enter reservoir; After time swap reached, valve-off finished A pot operation 2, B pot operation 5 simultaneously, until next time displacement.
Another embodiment of the present invention: in each digester, have simultaneously 2 pots to overlap in operation 5,9, realize one to one displacement.Such as: adopt 4 digester A, B, C, D, when the A pot is in the initial of operation 5, the B pot is in the initial of operation 9, and C pot D pot is in other operation; Then open simultaneously corresponding valve, so that B pot bottom input pulp washing filtrate, the hot black liquor V that the top displaces
11Directly send into the A pot bottom, carry out in the operation 5 of A pot and displacement, the hot acid liquid V that A pot top displaces
7Enter the hot acid liquid bath; After time swap reached, valve-off reclaimed displacement with displacement, B pot operation 9 alkali in the operation 5 of end A pot simultaneously, until next time displacement.
In the above-mentioned embodiment, if there is a certain pot to break down, then should send into corresponding storage tank by the cooking liquor that this pot that breaks down receives in the replacing process continuously.
The present invention is applicable to various timber, bamboo, and raw material is not had specific (special) requirements; Feed change kind at any time; Can steaming mixed different raw material; Can distinguish simultaneously the boiling different material mixes behind same hardness or different hardness again.Only need to adjust the concrete technology parameter according to actual conditions, so that compound above-mentioned permutizer condition gets final product.
Advantage of the present invention is:
1, effectively utilizes boiling heat energy, steam saving: decoction system is a process of utilizing the contained heat energy of cooking liquor to replace heating and heat exchange, steam directly passes in the circulation fluid to be warming up to maximum temperature, efficient is high, heating-up time is short, therefore effectively saved the consumption of steam, a ton slurry steam consumption can reach the 1.5-2 ton, than traditional batch boiling steam saving more than 65%;
2, put pot temperature below 100 ℃, do not have traditional boiling to put foul smell and the waste gas of pot process, eliminate atmosphere pollution;
3, improve dissolving pulp yield 1-3%, increase output, because the restored acid hydrolyzate has been used in hydrolysis, hydrolytic acidification time is shortened;
4, the heat energy of digestion process generation takes full advantage of by continuous displacement, and reaction condition is evenly gentle, and the boiling maximum temperature only needs 160~170 ℃, therefore can keep a cellulose more, fully removes the hemicellulose lignin, makes the yield raising of dissolving pulp, and output increases;
5, reduce Kappa number, because liquid filling stage acid solution is conducive to the stripping of hemicellulose in the acidic hydrolysis process; Excess base is used in soda boiling, does not give lignin condensation chance, and Kappa number is reduced, and improves the dissolving pulp quality:
6, the bleaching chemical consumption reduces, reduced discharge of wastewater load and wastewater flow rate: because Kappa number reduces, the required available chlorine of bleaching is reduced, the consumption of bleaching medicine reduces, simultaneously also reduce bleaching effluent amount and pollutional load, saved the wastewater treatment expense;
7, the dissolving pulp quality is even: be full of from bottom to up liquid displacement, carry out large liquor ratio boiling, alkali lye and uniformity of temperature profile make boiling dissolving pulp quality out even;
8, continuous replacing and digesting technoloy has concurrently intermittently and the characteristics of continuously cooking, makes the flow process of continuous displacement cooking simple, and operating procedure is simplified, so the investment of grassroot project is low; Because take full advantage of the equipment of traditional batch boiling, newly added equipment is few, when existing chemical fibre factory was undergone technological transformation, cost of investment was lower;
9, to various fibrous raw material strong adaptabilities, also can be used for the hydrolysis of paper making pulps boiling and corncob and produce furfural.
Description of drawings
Fig. 1 is the system architecture schematic diagram.
Be labeled as among Fig. 1: cooking liquor import 1, cooking liquor outlet 2, cooking liquor dress pot entrance 3, slurry outlet 4, the white liquid bath 5 of heat, cooking liquor reservoir 6, hot cooking liquor reservoir 7, white liquid heat exchanger 8, cold white liquid pipe 9, the white liquid pipe 10 of heat, running water heat exchanger 11, running water pipe 12, hot-water line 13, gases at high pressure pipeline 14, dilution reservoir 15, pulp washing section dilution intake line 16, spraying pot 17, cold white liquid bath 18, hot water storgae 19, cooking liquor heater 20.
Fig. 2 represents the process conditions curve of 1 pot.
Fig. 3 represents a plurality of pots process conditions curve (4 pots), and many are in different time (abscissa), the curve of same process condition, (curve shape is identical, and the position is different).
Fig. 4 represents a plurality of pots process conditions curve, and many are in different time (abscissa), the curve of same process condition, (curve shape is identical, and the position is different).
Fig. 5 represents a plurality of pots process conditions curve, and many are in different time (abscissa), the curve of same process condition, (curve shape is identical, and the position is different).
Fig. 6 represents a plurality of pots process conditions curve, and many are in different time (abscissa), the curve of same process condition, (curve shape is identical, and the position is different).
Fig. 7 represents a plurality of pots process conditions curve, and many are in different time (abscissa), the curve of same process condition, (curve shape is identical, and the position is different).
Fig. 8 represents the relation of bamboo pulp digester yield and the H factor.
The specific embodiment
The inventive method comprises a plurality of cooking liquor displacement imports 1 that have, the digester of cooking liquor displacement outlet 2 and cooking liquor dress pot entrance 3, described each digester is connected with cooking liquor heater 20, each digester bottom is provided with slurry outlet 4, the cooking liquor displacement outlet 2 of described each digester all directly communicates by the cooking liquor displacement import 1 of each digester of pipeline and other, and the cooking liquor of each digester displacement outlet 2 all is connected with same cooking liquor reservoir 6 by pipeline, and cooking liquor reservoir 6 communicates with the cooking liquor dress pot entrance 3 of each digester by pipeline.Among Fig. 1, digester is four pots of A, B, C, D among the figure, certainly, also can arrange more; In addition, the cooking liquor displacement outlet 2 of each digester described in the present embodiment all directly communicates by the cooking liquor displacement import 1 of each digester of pipeline and other, refer to directly connection between the digester, and the groove of liquid storage need to be set between per two digesters.
During work, set the identical process conditions of each digester and program.10 operations following (digester cycle):
1, pot filling:
Send into hot water more than 95 ℃ in the time of the dress pot, limit charging (bamboo chip or other are treated the boiling material), the limit liquor charging, until pot is filled, this moment, kettle temperature was T1=60 ℃-70 ℃.The present invention fills pot and also can adopt from the lower acid solution of the temperature that displaces of other pot or the warm acid solution in the reservoir, a dress pot time t1=30-90min.
2, acid displacement:
With V
1The hot acid liquid V of hot water (135 ℃) and 160 ℃-170 ℃
2Digester bottom input (for prehydrolysis provides acid condition, prehydrolysis being carried out fast) from filling displaces hydrolyzate V from the top
3Deliver to reservoir, can be used for loading other pot.This boiling kettle temperature is warming up to T2=150-155 ℃ from T1=60 ℃-70 ℃.Time swap t2=25-40min; Wherein, V
1+ V
2=V
3
In the prehydrolysis process, the acetic acid that is discharged by the acetylation glycan makes the pH value of hydrolyzate drop to 3~4, thereby causes the hydrolysis of hemicellulose, and hemicellulose is separated from raw material.
3, hydrolysis heats up
Follow-up temperature of continuing rising (passing into steam heats up) is finished in displacement, and to T3=170-175 ℃, t3=20-30min consuming time heats up.
4, hydrolysis (circulation) insulation: temperature T 4=T3=170-175 ℃, temperature retention time t4=120-240min;
During heating and heat preservation, circulating pump is released the pre-hydrolyzed solution in the digester, is entered in the pot by the top and the bottom of digester after with steam direct heating through heater, circulates.
5, neutralization displacement:
When the prehydrolysis reaction reaches P factor control (end) point of expection, the V that sends here from the white liquid bath of heat first
4The white liquid (150-155 ℃) of heat rapidly in and acid solution; Subsequently respectively with 160-170 ℃ hot black liquor V
5The heat white liquid V additional with needs
6(145 ℃-150 ℃) displace V from the input of digester bottom from the top
7160 ℃-170 ℃ of hot acid liquid, so that the boiling kettle temperature is down to T5=150-160 ℃, time swap t5=20-40min,
The hot acid liquid V that displaces
7Can send into another digester that needs hot acid liquid or hot acid liquid bath.V
7Unnecessary part is sent into the hot acid liquid bath to send into another digester that needs hot acid liquid.
The neutralizer V that displaces
8(being in the critical pH=7 of soda acid) send evaporation section, reclaims salt.
The hot black liquor V of the pH that displaces 〉=7
9Enter the hot black liquor groove.
6, neutralization insulation (further neutralization reaction, and so that alkali lye infiltrate through in the tablet)
Acid solution with in the alkali and displacement finish after temperature T 6=T5=150-160 ℃, temperature retention time t6=20-30min;
7, soda boiling heats up
Circulating pump is released the cooking liquor in the digester, is entered in the pot by the top and the bottom of digester after with steam direct heating through heater, circulates, and reaches T7=165 ℃-175 ℃, heat time heating time t7=20-40min.
8, soda boiling insulation: T8=T7=165 ℃-175 ℃, soda boiling time t8=30-90min;
Released from the cooking liquor in the digester by circulating pump,, heat rear top and the bottom by digester and enter a pot interior circulation soda boiling with steam direct heating boiling liquid through heater.
The soda boiling emphasis is according to the H factor control of setting.The H factor is that boiling temperature and digestion time are combined into parameter of moral in the pulping digestion process.
A and B flavor constant in the formula, constant A=E/R, E are delignification reaction activation energy, R is gas constant.On the basis of large quantitative determination activation energy, get E=32000 card/gram molecule, then A=16113.T is absolute temperature, reaction rate K is 1 when supposing 100 ℃ (373K), can calculate reaction rate constant K corresponding to different temperatures.
According to the H factor=average relative reaction rate * time interval, calculate the H factor.Utilize H factor control boiling end under certain condition, thereby stablize pulping quality and yield.
Among the present invention, the bamboo pulp H factor is controlled at 600-800; If the employing softwood pulp, the H factor is controlled at 800-1200.Because in the certain situation of alkali charge, the too high meeting of the H factor sharply descends yield, the pulping quality is affected; And the H factor is crossed low can causing and is cooked phenomenon rawly, and the slag rate is high, and screened yield descends.
9, alkali reclaims displacement:
When cooking reaction reaches control (end) point of expection, about 80 ℃ pulp washing filtrate V from pulp washing
10Send into the digester bottom, the top displaces the hot black liquor V more than 160 ℃
11, the warm black liquor V about 135 ℃
12To comprehensive groove, a part is replenished liquid as next digester cycle, and another part carries out alkali and reclaims; Displacement is down to T9 (below 100 ℃) to last kettle temperature by T8=165-175 ℃, waits for putting pot.
T9=20-40min during time swap.
Replacement amount is pressed the 100-110% of digester capacity.V
10=V
11+V
12。
10, put pot:
Extract out with pulp pump through the paper pulp of pulp washing filtrate cooling and to send spraying pot to, the temperature t 10 when putting pot is lower than 95 ℃, puts to be lower than 80 ℃ after pot is finished, and can load pot, and a pot time t15-20min is put in the operation boiling that next time circulates.
During work, a plurality of digesters are in respectively different operations.Such as take A, B, four digesters of C, D as example, certainly, also more digesters can be set.A, B, four pots of difference of C, D interval regular time (150min), each pot are accomplished to from filling and put the identical process conditions of the front setting of pot, such as Fig. 2.Certainly, in order further to simplify the operation, the filling operation also can be identical with the process conditions of putting pot operation.
Fig. 2 represents the process conditions curve of 1 pot.
Fig. 3 represents a plurality of pots process conditions curve (4 pots, a pair of two replacing process), and 4 are in different time (abscissa), the curve of same process condition, (curve shape is identical, and the position is different).
As can be seen from Figure 3, the acid of each pot displacement operation 2, neutralization displacement operation 5, alkali reclaim the identical time swap of displacement operation 9, i.e. t2=t5=t9.
There are 3 pots to be in simultaneously operation 2,5,9.
When to the time coincide point, when needing displacement, open simultaneously cooking liquor displacement import and the cooking liquor displacement outlet of each pot that needs displacement, and with cooking liquor reservoir (hot acid liquid bath; Hot black liquor; Hot water storgae; Cold white liquid bath; The white liquid bath of heat or dilution liquid bath) headstock gear equate with the total amount that displaces so that each pot sent into the total amount of digester:
V
1+ V
2Remaining space=V in the-pot
3
V
4+V
5+V
6=V
7+V
8+V
9;
V
10=V
11+V
12。
Wherein, the V of operation 9
11Namely as V
5Send in the pot of operation 5, remaining part is sent into the hot black liquor groove; V in the operation 5
7Namely as V
2Send in the pot of operation 2, remaining part is sent into the hot acid liquid bath.Each conveyance conduit is by the flowmeter autocontrol valve.
After displacement is finished, close a headstock gear, enter subsequent handling, wait for next time time swap.
A pair of two displacements(have three pots can realize continuous displacement in four pots, a pot is replaced continuously to two other pot):
When the A pot is in the initial of operation 2, the B pot is in the initial of operation 5, and the C pot is in cooking reaction and reaches terminal point, and operation 9 initial, the D pot is in other operation (such as acid hydrolysis insulation operation).Then open simultaneously corresponding valve, so that C pot bottom input pulp washing filtrate V
10, the hot black liquor V more than 160 ℃ that the top displaces
11=V
5Directly send into the B pot bottom, carry out the operation 5 of B pot; Warm black liquor V about 135 ℃
12To comprehensive groove;
160 ℃ of-170 ℃ of hot acid liquid V that B pot top displaces
6, V wherein
2Part is carried out the operation 2 of A pot, the hydrolyzate V that A pot top displaces from A pot bottom input A pot
3Enter reservoir.
After time swap reached (t2=t5=t9), valve-off finished the displacement of A pot operation 2, B pot operation 5, C pot operation 9 simultaneously, until next time displacement: the A pot reaches operation 5, the B pot reaches operation 9, and the D pot reaches operation 2, carries out above-mentioned similarly simultaneously displacement.The rest may be inferred carries out a pair of two displacements.
Certainly, if certain pot breaks down, can not realize continuous circulation, also can have and carry out the continuous circulation displacement between two pots.Two pots overlapped in operation 2,5, time of 9, and being in operation 2 such as a pot, to have another pot to be in operation 5 when initial initial, or pot is in operation 5, and to have another pot to be in operation 9 when initial initial.Should send into corresponding storage tank by the cooking liquor that the pot that breaks down receives gets final product.
One to one displacement: such as: when the A pot is in the initial of operation 2, the B pot is in the initial of operation 5, and C pot D pot is in other operation.Then open simultaneously corresponding valve, hot black liquor is sent into the B pot bottom, and the hot acid liquid that B pot top displaces carries out the operation 2 that A crosses from the input of A pot bottom, and the filling liquid that A pot top displaces enters reservoir.C pot, D pot were replaced when another time replaced continuously.Or
One to one displacement: such as: when the A pot is in the initial of operation 5, the B pot is in the initial of operation 9, and C pot D pot is in other operation.Then open simultaneously corresponding valve, so that B pot bottom input pulp washing filtrate, the hot black liquor that the top displaces is directly sent into the A pot bottom, carries out the operation 5 of A pot, and the hot acid liquid that A pot top displaces enters the hot acid liquid bath.C pot, D pot were replaced when another time replaced continuously.
In the above-described embodiment, white liquid in the white liquid bath 5 of described heat can heat by ad hoc heater, but for energy savings consumption, be provided with white liquid heat exchanger 8 on the cooking liquor displacement outlet 2 of each digester and the pipeline between the cooking liquor reservoir 6, described white liquid heat exchanger 8 also is connected with cold white liquid pipe 9 and the white liquid pipe 10 of heat, and the white liquid pipe 10 of heat is connected between white liquid heat exchanger 8 and the white liquid bath 5 of heat.Mention in the embodiment of front, when carrying out the cooking liquor displacement, one of them digester need to be put cooking liquor to cooking liquor reservoir 6, at this moment, this cooking liquor white liquid heat exchanger 8 of flowing through, cold white liquid carries out heat exchange from cold white liquid bath 18 through the cold white liquid pipe 9 white liquid heat exchanger 8 of also flowing through, after the heat exchange, cooking liquor still flow in the cooking liquor reservoir 6, the white liquid of heat after the heat exchange then flow in the white liquid bath 5 of heat by the white liquid pipe 10 of heat, utilize well the heat energy dialogue liquid of cooking liquor to heat, saved the energy.
In the above-described embodiment, owing to only need use the heat of seldom a part of cooking liquor to the heat exchange of cold white liquid, and in order to take full advantage of this heat, also be provided with running water heat exchanger 11 on the cooking liquor displacement outlet 2 of each digester and the pipeline between the cooking liquor reservoir 6, described running water heat exchanger 11 is arranged in parallel with white liquid heat exchanger 8, and running water heat exchanger 11 also is connected with running water pipe 12 and hot-water line 13.Cold water is from running water pipe 12 running water heat exchanger 11 heat exchange of flowing through, cooking liquor after the heat exchange flow in the cooking liquor reservoir 6, hot water is then delivered to hot water storgae 19 by hot-water line 13 and is stored, delivering to other need to use with the place of hot water again, carries out the pulp washing operation as it being delivered in the pulp washing operation behind the digesting technoloy.
For ease of putting the pot operation, be connected with gases at high pressure pipeline 14 at each digester top.When needs are put pot, in digester, pass into gases at high pressure by gases at high pressure pipeline 14, thereby also can well the slurries in the digester be discharged.
A pair of two displacements of 1 four digesters of embodiment
Whole digester cycle has 10 operations:
Replacement amount
Concrete steps are as follows:
1, B pot dress pot
Start dress pot blower fan, the dress pot is sent into 52.5m from hot water storgae simultaneously
3Hot water (95 ℃) or acid solution (solid-liquid volume ratio 1: 2.5) are until fill pot.Close the pot cover valve, start the liquid circulating pump, begin circulation, kettle temperature is 65-70 ℃ and waits for intensification.
Illustrate: 1. over dry tablet 35t;
2. tablet moisture 50%. is with water 35m
3
3. replenish hot water 52.5m
3
The pot in remaining space 52.5m
3
2, B pot acid solution displacement
The dress pot is finished, and the B pot self is played circulation (such as Fig. 1), then sends into first 135 ℃ of hot water 82m from hot water storgae
3, then send into 82m from the hot acid liquid bath or from the hot acid liquid (160 ℃-170 ℃) of C pot
3, displace 111.5m from the pot top simultaneously
3Hydrolyzate (mixed liquor of filling liquid, warm acid solution, the hot acid liquid) processing of anhydrating (or deliver to the A pot and load).The B pot self was played circulation after displacement was finished, and at this moment kettle temperature is 145 ℃-150 ℃.Wait for and continue to heat up.
Illustrate:
1, adds displacement hot water amount 82m
3
2, add displacement acid solution amount 82m
3
3, discharging the hydrolysis liquid measure is 82+82-52.5 (remaining space in the pot)=111.5m
3
3, B pot hydrolysis heating and heat preservation
First kettle temperature is added to 170 ℃ by the digester steam heater.
4, B pot hydrolysis circulation insulation
Be incubated 240 minutes.
5, acid neutralization displacement
After hydrolysis reaches terminal point (being incubated 240 minutes), send 145 ℃-150 ℃ 20m here from the white liquid bath of heat
3The white liquid of heat rapidly in and acid solution.
Respectively from 160-165 ℃ of hot black liquor 112m from the C pot
3And 48m
3The white liquid of heat is sent into the B pot, replaces the interior 130m that takes the dish out of the pot from B pot top
3(contain 10m
3Condensed water) 160 ℃ of-170 ℃ of hot acid liquid (set amount is take PH<7 as the boundary).82 (m in the hot acid liquid
3) enter the A pot and carry out acid displacement, the remaining hot acid liquid bath that automatically switches to.
Be in the critical neutralizer 34m of soda acid
3Enter comprehensive groove and send evaporation section by heat exchange.
The hot black liquor 26m of all the other PH 〉=7
3Enter the hot black liquor groove.Kettle temperature was 145 ℃-150 ℃ after displacement was finished.
6, neutralization insulation
Insulation 20min.
7, soda boiling heats up
In soda boiling heats up, send into 145 ℃-150 ℃ white liquid 32m of heat
3, displace 145 ℃ of-150 ℃ of hot black liquor 32m
3Send into the hot black liquor groove.
Illustrate: sending into total white liquid measure is 100m
3: in the operation 5 and when displacement add the white liquid V4 (20m of heat
3), the white liquid V6 (48m of heat
3), soda boiling heats up and adds 32 (m
3).
8, soda boiling insulation
Insulation 120min.Do recovery after waiting for the soda boiling terminal point.
9, alkali reclaims displacement
When cooking reaction reaches terminal point, send 80 ℃ of rare black liquor 180m from accumulator tank (from rare black liquor of pulp washing)
3Deliver to digester.Displace the 112m more than 160 ℃
3(contain 10m
3Condensed water) (setting value) hot black liquor is delivered to the A pot and is carried out alkali displacement or deliver to hot black liquor groove, the warm black liquor 68m below 135 ℃
3To comprehensive groove, last kettle temperature drops to below 100 ℃, waits for and puts pot.
10, put pot
By 80 ℃ of rare black liquor 116.2m of dilution pumping
3To the B pot, start and put a pot pump and take out slurry and send into spraying pot.
Rare black liquor of sending in the pot is 116.2m
3