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蒸煮、洗选、氧脱木素和无元素氯的的三段漂(一)  

2008-07-23 12:05:59|  分类: 学科研究 |  标签: |举报 |字号 订阅

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Teaching Material for Training Program

(蒸煮、洗选、氧脱、三段漂)

(Cooking/Washing and Screening

    Oxygen delignification and Bleaching)

 

第一部份  蒸煮

Part 1. Cooking

 

1.蒸煮理论

1. Theory of Cooking

1.1蒸煮的目的:除去纤维原料中的木素和杂质,保留纤维和半纤维素,以利于造纸。

1.1 Purpose of Cooking: To remove the lignin and impurity from the fibrous materials, and retain the cellulose and hemicellulose for the paper making purpose.

1.2硫酸盐法制浆碱液的消耗在于:

1.2 The wastage of alkali liquor when making pulp with sulphate process lies in:

①与木素的反应

① The reaction with lignin.

②与纤维素和半纤维素的反应,促使纤维素和半纤维素的降解

② The reactions with cellulose and hemicellulose which drive the degradation of cellulose and hemicellulose.

③中和蒸煮过程中生成的有机酸

③ The organic acid generated from the neutralization and cooking process.

④与纤维原料中树脂产生皂化作用

④ The saponification generated with the resin of fibrous materials.

⑤少量的碱为纤维所吸附

⑤ Few alkali was absorbed by the fibers.

1.3蒸煮过程中的物理机理

1.3 The physical mechanism of the cooking process

①蒸煮液中的OH′SH′渗透和扩散到料片中去

① The OH′and SH′of cooking liquor infiltrate and proliferate into the material flakes.

②料片的木素等化学组分吸收OH′SH′在其表面上

② The chemical constituents of material piece such as lignin absorbs the OH′and SH′ to its surface.

③料片的木素等化学组分与其吸收的离子(OH′SH′)反应

③ The reaction between chemical constituents of material flake such as lignin and the absorbed ions (OH′and SH′).

④反应物的溶出

④ The dissolve of reactants.

⑤通过扩散将料片内反应物选出来

⑤ Pick out the reactants of material flakes by proliferation.

1.4蒸煮过程中的影响因素:

1.4 The influencing factors in cooking:

掌握影响因素的规律:就可制定出较好的工艺条件。生产了高产高质的纸浆?

Master the rules of influencing factors: can develop better techniques. Be able to produce pulp of high yield and high quality?

1.4.1①纤维原料:(竹片规格的大小,大的较难蒸煮,节小多,小的反之)

1.4.1 ① Fibrous materials: (the specification of bamboo flakes, big ones are difficult to cook, small and more knots, the small ones are on the contrary).

②纤维原料的水份:(竹片的水份必须均匀,湿的渗透快可缩短蒸煮时间)

② The moisture in the fibrous material: (The moisture of bamboo flakes must be equal as the wet ones are fast to proliferate and require shorter cooking time).

1.4.2用碱量:

1.4.2 Alkali dosage:

用碱量主要取决于原料的组成和性质及对纸浆的质量要求:加用碱量有利于加快蒸煮速度降低纸浆硬度和提高纸浆的可漂性:但过高却会降低纸浆得率和物理强度,如过低时,成浆较硬而色暗,不易漂白而且筛渣多即使延长蒸煮时间也难以保证脱木素反应进行。

The alkali dosage depends mainly on the constituents and property of material and the quality requirements for pulp: more alkali dosage will speed up cooking process, reduce the hardness of pulp and improve the bleachability of pulp; but excessive alkali dosage will lower the pulp yield and physical intensity, while too less alkali dosage will result in harder and darker pulp, uneasy to bleach, too much screenings, and even extending cooking time cannot guarantee the reaction of delignification.

竹子的用碱量,我厂定的是17%,但在生产中我们看竹子种类胡做适当的变化。

The alkali dosage for bamboo in our factory is 17%, but the percentage varies according to different kinds of bamboos.

以下是用碱量蒸煮时间和成效不得率关系的草图

The following figure is a diagram of relations among alkali dosage, cooking time and yield:

        用碱量 Alkali dosage

 

               15%

 

               20%

               25%

               30%

               40%

               60%

 

64

60

得率%

Yields %

56

52

48

44

40

36

32

  0 1 2 3 4 5 6 7 8 

      蒸煮时间(小时)

            Cooking Time (hours)

1.4.3碱液浓度:

1.4.3 Concentration of alkali liquor:

碱液浓度决定于活性碱用量和液比,改变蒸煮药液的浓度也就意味着改变用碱量或液比。

The concentration of alkali liquor depends on the active alkali dosage and liquor ratio, the variation of cooking liquor concentration means changing the alkali dosage and liquor ratio.

以下是碱液浓度与纸浆得率的关系草图:

The following figure is the diagram of relation between alkali liquor concentration and pulp yield:

62

得率 %

Yields %

54                       Concentration

46                      1 浓度30g/l(NaOH)

42                   2 60 g/l

38                3 90 g/l

30                           

    1   2   3   4   5   6   7   8

蒸煮时间(小时)

Cooking Time (hours)

1.4.4硫化度

1.4.4 Sulphidity:

在硫酸盐法制浆时,药液的硫化度无论对于蒸煮速度还是对成浆的得率和质量等各方面有很大影响。

When making pulp with sulfate process, the sulphidity of liquor has great impact on both cooking time and pulp yield & quality.

在一定范围内,提高硫化度不但可以加速木素的溶中,降低纸浆中木素含量并且还可缩短蒸煮时间,提高浆的得率和物理强度。

Within certain range, higher sulphidity can not only speed up the dissolve of lignin, but also reduce the lignin content in the pulp, as well as shorten the cooking time, increase pulp yield and physical intensity.

但过高也不行,因为在用碱量一定的情况下提高硫化度就意味着有较碱的降低。当降低到不足硫化木素的溶出将影响脱木素的反应。硫化度过高必将加剧药液的腐蚀性。增加操作困难。

But the sulphidity can not be too high either, as when the alkali dosage is fixed, higher sulphidity means the lower percentage of alkali, When the alkali percentage is as low as insufficient to dissolve the sulfurated lignin, it will adversely affect the reaction of delignification.

1.4.5蒸煮温度和时间:

1.4.5 Cooking temperature and time:

①蒸煮温度即指蒸煮的最高温度。

① The cooking temperature is the highest temperature when cooking.

②蒸煮时间主要包括升温时间和保温时间。

② The cooking time mainly includes heating up time and heating preservation time.

③随着温度的升高,加速蒸煮的反应,并促进木素的溶出,在蒸煮最高温度范围内,随着蒸煮温度的提高,蒸煮时间也就可缩短。

③ Higher temperature will speed up the reaction of cooking and drive the dissolve of lignin, so within the highest temperature range, the higher temperature it is, the shorter cooking time will be.

④但蒸煮温度的提高和保温时间的延长,虽有利于脱木素,但也加剧对碳化后物的损害,因此,成浆得率低硬度小物理强度小漂率也低。

④ Although the rising of cooking temperature and extension of heat preservation time will facilitate the delignification, it will also reinforce the damage to carbon compound, as well as low the pulp yield, hardness, intensity and bleachability.

100

90      140℃

纸浆得率 %

Pulp Yields %

80

70         160℃

60      170℃

50

40             180℃

 

1        2  3  4  5  6  7  8

蒸煮时间(小时)

Cooking Time (hours)

2、蒸煮工艺流程图:

2. Cooking technical process map:

从缅甸的工艺流程图看:有5台135m3的蒸煮锅:2台500m3喷放锅:1#、 2#、3#蒸煮锅的浆料喷到1#喷放锅4#、5#、蒸煮锅的浆料喷到2#喷放锅:

According to the Myanmar technical process map: there are 5 135m3 cooking tanks and 2 500m3 blow tanks; the pulp of 1#, 2# and 3# tanks will be blowed to 1# blow tank while the pulp of 4# and 5# tanks will be blowed to 2# blow tank.

以下为单锅的工艺流程图:

The following is the technical process map for single tank:

3、蒸煮操作控制参数分析蒸煮工艺控制要点。

3. Analysis of control parameters of cooking operation and the control essentials of cooking techniques.

蒸煮的所有操作都 跟据工艺要求和浆质量要求进行。现先介绍竹子蒸煮工艺条件,再进行分析其参数要点。

All the cooking operations will be in accordance with the technical requirements and pulp quality requirements. Firstly there is the introduction of bamboo cooking technical conditions, and the next step will be the analysis of its parameters.

(针对缅甸135m3的锅进行蒸煮的工艺)

(For the cooking techniques of Myanmar 135m3 tank)

1)、装锅量,、按30吨锅(按液浸装锅计)(绝干)

1) Filling amount will be according to the 30-ton tank (counted according to the liquor filled tanks) (absolutely dry)

2)、液比:1:3:7(其中竹制片水份由化验站监测)

2) Liquor ratio: 1:3:7 (the moisture of bamboo flakes will be monitored and measured by the lab)

3)、用碱量170%(以Nano计)每锅加碱量5100kg

3) Alkali dosage 170% (count with Nano) 5100kg alkali dosage for each tank.

4)、碱化度18—24%

4) Degree of alkalization 18-24%

5)、蒸煮升温曲线:(蒸煮最高温度160℃)

5) Heating up curve of cooking ( the highest cooking temperature is 160℃)

一段升温时间(85—130℃):100分钟

Heating up time of 1st phase (85-130℃): 100 minutes

小放汽(130℃)15分钟

Minor discharging of steam (130℃): 15 minutes

二段升温时间:(130—160℃):60分钟

Heating up time of 2nd phase (130-160℃): 60 minutes

高温保温时间(160℃):40分钟

High temperature heat preservation time (160℃): 40 minutes

6)、放锅时间15分钟

6) Discharging time: 15 minutes

7)、竹浆粗浆指标:硬度20——30kappa,残碱10—15g/L(Na2o计)

7) Index of brown bamboo pulp: hardness 20-30kappa, alkali remnant 10-15g/L (count with Na2o)

3.1控制参数:

3.1 Control parameters:

3.1.1装锅量:竹子30吨(绝干)是以液浸装锅和开中循环压竹片3——4分钟为计,(数据是根据多次实验得出的结果)如装锅量太小,硬度低,残碱大,浆得率低,装锅量太大蒸煮液无法完全送完,循环量小,循环泵电流小,蒸煮困难,浆节子多、硬度高、残碱小,有可能造成生浆。所以装锅量必须控制适当。

3.1.1 Filling amount: 30 tons of bamboo (absolutely dry) counted with liquor filled tank and circularly press the bamboo flakes for 3-4 minutes during boiling, (the data results from repeated experiments), if the filling amount is too less, the hardness is low, too much alkali remnant, and the pulp yield will be low; if the filling amount is too much, the cooking liquor can not be dried completed, and the circulation amount is too less, the electric current of circulating pump is too low, it will be difficult to cook, and there will be too much pulp knots with high hardness and less alkali remnant which may lead to unripe pulp. So the filling amount should be controlled appropriately.

3.1.2液比、用碱量:硫化度的工艺参数也是根据实验得出数据。分析在蒸煮理论里也讲到就不去分析。

3.1.2 Liquor ratio and alkali dosage: The technical parameters of sulphidity are also resulted from the experiment. The analysis will be mentioned in the theory of cooking, so we are not going to analyze here.

3.2、工艺控制要点:在我厂经过多年生产,工艺控制要点最主要的是:液比和一段、二段升温的调节。

3.2 Essentials of technical control: according to the years of our production experience, the key of technical control is: the liquor ratio and heating up regulation during phase one and phase two.

3.2.1液比:决定送液量的大小,送液量的大小又要跟据竹子水份,竹子水份的测定又不准确,所以送液时就要跟据竹子水份和送液时锅里假压情况及时调整黑液量,确保液比准确性。

3.2.1 Liquor ratio: decides the amount of liquor, and the liquor amount should be according to the moisture of bamboo; as the measurement of bamboo moisture is not correct, so when filling the liquor you should adjust the amount of black liquor in a timely manner according to the bamboo moisture and the false pressure status of the tank so as to ensure the accuracy of liquor ratio.

3.2.2一段升温和二段升温:

3.2.2 Heating up of phase one and phase two:

由于竹子原料的不统一。如新生竹和老竹、小杂竹和蒿竹、竹密度不一样,所以蒸煮时要自行调整工艺,新竹和小杂质,易蒸煮、所以一段可相应缩短,高保温度也可相应低一点,就可煮出高质和高得率的浆。老竹和蒿竹不易蒸煮,所以一段相应延长,高保温度要相应高一点,高保时间也要长一点,这样才能煮出好浆。

As the bamboo materials are not all the same, such as new born bamboo and grown-up bamboo, small miscellaneous bamboo and celery bamboo, the densities are not the same, so the techniques should be adjusted during cooking, new born bamboo and small miscellaneous bamboo are easy to cook, so the cooking time can be shortened, and the high temperature heat preservation temperature can be also relatively low to ensure pulp of high quality and high yield. The grown-up bamboo and celery bamboo are not easy to cook, so the 1st phase cooking should be longer and the high temperature heat preservation temperature should be higher and the preservation time should be longer, so as to produce good pulp.

4、开机前的检查、开停机操作运行检查。

4. Check before start, turn on and turn off operations and check during the operation.

4.1、装锅开机前的检查和停机操作运行检查。

4.1 Check before filling tank and start, turn off operation and check during the operation.

4.1.1、每次放完锅后,装锅前必须用低压灯(36V)仔细检查锅内情况。

4.1.1 Must check the status in the tank with low-voltage lamp (36V) after each discharging and filling of tank.

4.1.1.1、锅内有无残浆及其它杂物。

4.1.1.1 Whether there is pulp remnant or other sundries in the tank.

4.1.1.2、上、中、下循环鼠子有无脱落,损环变形。

4.1.1.2 Whether the upper, middle and lower circulation pieces are loose, damaged or distorted.

4.1.2、检查自动锅盖是否安全可靠锅上密封卷是否完好。

4.1.2 Check whether the automatic tank cover is safe and reliable, and whether the seal knot on the tank is good.

4.1.3、检查可逆输送滞有无跑偏异响在送料时应联系检查工取样测定水份及规格。

4.1.3 Check whether the reversible conveyer draper is deviated or has abnormal sound; while conveying the materials, contact the inspectors for sampling of moisture and specifications

4.1.4、检查各汽管阀门是否完好。

4.1.4 Check whether all steam fitter valves are good.

4.1.5、检查各管道阀门是否完好。

4.1.5 Check whether all pipe valves are good.

4.2、送液前的准备与检查。

4.2 Preparations and check before filling the liquor.

4.2.1 、检查出口阀门是否灵活,是否可以关严。排污阀是否关严。

4.2.1 Check whether the outlet valve is agile, and whether it can be closed tight, Check whether the drainage valve is closed tight.

4.2.2、液位测量系统是否灵活,准确。

4.2.2 Whether the liquor level measurement system is agile and accurate.

4.2.3、装锅前是否备足一锅白液和黑液,联系化验工测定浓度,计算好入锅白液量,然后如实填写原始记录。

4.2.3 Whether there are sufficient white liquor and black liquor before filling the tank, contact the tester to measure the concentration, calculate the white liquor amount for the tank and honestly fill in the original records.

4.3、蒸煮升温前的准备与检查。

4.3 Preparations and check before heating up step of cooking.

4.3.1检查各压力表、温度计以及有关仪表是否正常。

4.3.1 Check and make sure that all manometers, thermometers and other instruments are working well.

4.3.2、检查各管道、接头、阀门是否有漏。

4.3.2 Check whether the pipes, connectors and valves have any leakage.

4.3.3、检查循环泵试运转电流是否正常。

4.3.3 Check the circulating pump to find out whether the electric current is normal.

4.3.4、对生产全过程每台锅的主要阀门进行复查,确信该开的阀门开,该关的阀门关上后,方可进行升温操作。

4.3.4 Check all major valves of each tank again, make sure all the valves are in the corresponding on or off status before conducting the heating up operation.

4.4、放锅前的检查。

4.4 Check before discharging.

4.4.1、检查喷放锅浆位,是否够放入一锅浆料余位。

4.4.1 Check the pulp level of blow tank, find out whether there are enough space for a tank of pulp.

4.4.3、检查喷放锅取样口是否确实关好。

4.4.3 Check whether the sampling hole of blow tank are closed.

4.4.4、检查污热水坛温度是否在工艺要求范围内。4.4.4 Check whether the temperature of hot sewage jug is within the required range.

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