KINETIC STUDY ON PYROLYSIS OF NSSC BLACK LIQUOR IN A NITROGEN ATMOSPHERE

Thermogravimetric analysis experiments were carried out to investigate the pyrolysis properties of neutral sulfite semi-chemical pulp (NSSC) black liquor ranging from room temperature to 800°C with heating rates of 20°, 30°, 50°C/min. Experimental results show that the black liquor quickly loses weight in the temperature range of 170°–370°C, 370°–570°C, and 570°–800°C. The organic volatiles are mostly released in the former two ranges, while the alkali metal salts decompose, volatilize, and react in the third range. The mechanism function of NSSC black liquor pyrolysis is determined by means of the thermal analytic dynamics method and the most probable mechanism functions. The kinetic parameters for the chemical reactions were calculated by the Coats and Redfern method and the Ozawa method. Meanwhile, the pyrolysis dynamics equation of the NSSC black liquor is presented in this work. The results show that the activation energies of the NSSC black liquor decomposition calculated by the Ozawa method in the three temperature ranges are in general lower than that those calculated by the Coats and Redfern method.     

Electrochemical Treatment of Black Liquor from Straw Pulping

Abstract

The conventional black liquor regeneration process is not always suitable for pulping plants of nonwood fibers due to the unfavorable ratio of organic to inorganic solids. This paper presents an alternative treatment based on an electrolysis process of the soda black liquor from straw pulping. This alternative method minimizes the environmental impact by recovering the caustic at the same time that the liquor is acidified, which favors the later separation of the lignin.     

造纸黑液对石油焦-CO2气化的催化作用及动力学补偿效应

研究了以造纸黑液为催化剂,齐鲁石油焦-CO2的气化动力学.在950～1200℃测定了造纸黑液负载量为0～15%时石油焦的气化反应活性,发现造纸黑液使石油焦的气化反应活化能大幅度降低,表明造纸黑液具有催化作用.得到了齐鲁石油焦-CO2催化气化反应动力学的缩芯模型,并给出相应的动力学参数.催化剂用量对动力学参数的影响表明,...     

造纸黑液超临界水气化制氢与高附加值化学品回收研究进展

造纸黑液的无害化资源化利用对造纸工业减少环境污染、缓解能源短缺具有重要意义。超临界水气化技术是一种新型且高效的有机废水无害化资源化利用技术,利用水在超临界状态下的特殊性质使其在无害化资源化处理造纸黑液时具有独特的优势。回顾了近年来造纸黑液超临界水气化制氢与高附加值化学品回收的进展,介绍了制氢反应机理,系统总结了温度、压力、浓度、停留时间和催化剂等因素对黑液超临界水气化制氢的影响,介绍了造纸黑液里各类有用无机盐在超临界水条件下的反应、分离回收及造纸黑液超临界水气化反应装置的发展现状。针对现存问题对造纸黑液超临界水气化制氢和资源化无害化处理回收有用成分进行了展望。     

造纸黑液超临界水气化制氢与高附加值化学品回收研究进展

造纸黑液的无害化资源化利用对造纸工业减少环境污染、缓解能源短缺具有重要意义。超临界水气化技术是一种新型且高效的有机废水无害化资源化利用技术,利用水在超临界状态下的特殊性质使其在无害化资源化处理造纸黑液时具有独特的优势。回顾了近年来造纸黑液超临界水气化制氢与高附加值化学品回收的进展,介绍了制氢反应机理,系统总结了温度、压力、浓度、停留时间和催化剂等因素对黑液超临界水气化制氢的影响,介绍了造纸黑液里各类有用无机盐在超临界水条件下的反应、分离回收及造纸黑液超临界水气化反应装置的发展现状。针对现存问题对造纸黑液超临界水气化制氢和资源化无害化处理回收有用成分进行了展望。     

造纸工业黑液和纸浆快速测定硅含量的新方法

针对国内造纸工业造纸黑液研究热点问题,提出一种黑液和纸浆中硅含量的快速测定新方法。该方法利用现代分光光度仪,绘制了标准曲线,结果准确,速度快捷,适合批量检测硅试样,可替代制浆造纸行业的传统硅测定方法。     

The pyrolysis of extracted solids from oxidized kraft black liquor after lignin precipitation

A laboratory investigation of the possibilities for the reduction of odor from Kraft mill stack gases by lignin precipitation from oxidized Kraft black liquor and subsequent pyrolysis of the filtrate solids has been carried out. Samples of oxidized black liquor were acidified with sulphuric acid and the lignin precipitate extracted. The extraction scheme indicates that > 90% w/w of the sodium in the original black liquor samples can be retained in the filtrate after lignin removal at final pH 2.0. The evaporated filtrate solids containing the bulk of the black liquor inorganic chemicals were pyrolyzed and the evolved hydrogen sulphide, methyl mercaptan and dimethyl sulphide monitored by gas-chromatography. Gas-chromatograph traces displaying the increase and decrease of methyl mercaptant evolution levels on pyrolysis of the filtrate solids to increasing temperatures are shown. A thermogravimetric technique was used to investigate the decomposition rates of the extracted samples and these rates correlated with the levels of sulphur gases evolved on pyrolysis. Heats of combustion were determined by bomb calorimetry. Sulphur losses from the filtrate solids and the Kraft black liquor total solids are compared. The results show a significant decrease in the evolution of organo sulphur gases from samples of ligninextracted black liquor solids in comparison with original total solids samples, an increase in the level of hydrogen sulphide evolution however, presents a problem.     

Thermal studies on kraft black liquor

Kraft black liquor and lignin from the same batch were subjected to thermal analysis (DTA and TGA) under an inert atmosphere and also in an oxidising atmosphere to simulate conditions which might be encountered in the recovery furnace. Gasification studies were carried out by rapidly heating the sample under helium. Results showed that the thermal decomposition of black liquor can be divided into four characteristic steps: drying up to 200°C, pyrolysis between 200 and 550°C, inorganic sodium salt formation between 550 and 800°C and salt fusion between 800 and 1000°C. Gases evolved during gasification of black liquor are rich in flammable compounds while those from the lignin sample are rich in CO₂.     

Kinetics of wet oxidation of black liquor over a Pt–Pd–Ce/alumina catalyst

The catalytic oxidation of industrial wastewater from paper and pulp mills has been investigated in a slurry reactor at a temperature range 433–463 K and at pressures from 1.5 to 2.2 MPa. Adding Ce on alumina support promotes the catalytic activity for oxidation of black liquor. Pt–Pd–Ce/alumina catalyst shows a promising activity for wet catalytic oxidation of black liquor. The oxidation reaction over a Pt–Pd–Ce catalyst is characterized by an initial fast reaction step followed by a slow reaction step. The rate of total organic carbon (TOC) reduction was described by first-order kinetics with respect to TOC concentration in black liquor for both initial and later reaction steps. The activation energies were determined to be 54.53 and 50.13 kJ/mol for the initial and later oxidation steps, respectively. Comparison of the data with the generalized kinetic model was also presented.     

超滤微滤处理制浆黑液技术的研究进展

介绍了目前国内外制浆黑液的主要处理方法,重点阐述了国内外采用超滤、微滤技术处理制浆黑液的研究进展,详细介绍了无机膜和有机膜在浓缩、预处理制浆黑液方面取得的效果。在制浆黑液的循环利用方面,超滤、微滤技术在投资和运行成本上具有较大优势,但是需要与其它膜过程集成,并进行系统工艺优化,提高整体回收、利用水平才具有工业化前景。最后,本文认为膜技术是经济、高效处理制浆黑液的重要发展方向。     

Recovery of some valuable components from industrial waste

The present work studied several ways for wastewater treatment for the waste from the pulp and paper industries including the recovery of some valuable components from this waste and reaching the acceptable environmental limits for the treatment of waste. The acidification technique showed high efficiency for the removal of solids from the black liquor. A proper treatment for the effluent produced from the pulp and paper industry that used rice straw as raw material. The dose of the alum as a coagulant has an effect on the solid process and is due to the high percentage of solids in the black liquor. Hydrochloric acid is used to control the pH of the solution and separating most of the solids from the black liquor. Sodium hydroxide can be used to remove silica from the other solids by forming sodium silicate. The amount of solids precipitated increased by increasing the stirring time, temperature, rpm of the agitator, and decreasing pH. IR spectroscopy was carried out on the solid to assign the functional groups. Thermal analysis and EDX analysis were done to study the thermal properties of the solids. A proper design of the mixer and drier is accomplished to provide high efficiency of the silica removal process.     

连续处理造纸黑液的研究

采用微波辐射处理麦草浆蒸煮黑液，由正交实验来确定其最优工艺奈件是：麦草浆蒸煮黑液流速u为0．11mL／s，微波辐射功率P为400W，活性炭催化剂床层高度L为18cm，处理后的黑液吸光度为0．061．木素去除率为n=90．2％。根据极差判断：微波辐射功率对处理效果的影响最大，活性炭催化剂床层高度次之．流速对黑液处理效果影响最小。     

硅化物对麦草碱法蒸煮黑液黏度的影响

为了研究硅对黑液黏度的影响,向麦草碱法蒸煮黑液中添加定量的二氧化硅、麦草灰分和硅酸钠,分析不同硅化物对黑液黏度的影响。研究发现,相对于麦草灰分和二氧化硅,硅酸钠更能增加麦草黑液的黏度。硅酸钠对不同浓度麦草黑液黏度的影响顺序为:高浓黑液≥中浓黑液>低浓黑液。当硅酸钠占黑液总固形物的量大于15%(SiO2计)时,其对低浓度黑液的黏度造成显著影响;当硅酸钠占黑液总固形物的量为13%～15%(SiO2计)时,其对中浓黑液的黏度有显著影响;当硅酸钠占黑液总固形物的量为11%～13%(SiO2计)时,其对高浓黑液的黏度有显著影响。     

亚铵制浆废液资源化及其在造纸和农业经济中的作用

以亚铵法制浆造纸废液为原料开发了数种新型系列肥料,并通过在不同地区不同作物上进行应用评价.结果表明,这一举措不仅使造纸废液变废为宝,在消除污染的同时给造纸企业带来可观的经济效益;而且生产的多种肥料都显示出很好的增产、增质效果,并能提高作物的抗逆性.目前,这种对废液的循环利用是适应现代农业可持续发展的有效方法.     

麦草制浆造纸黑液的处理新工艺研究

对麦草制浆造纸黑液的处理工艺进行了报道,在酸析时加入硫酸铝,木质素析出更加完全,混合絮凝能有效去除污染成份,为中小型造纸厂黑液的治理提供了新途径。     

THE INFLUENCE OF COMPOSITION ON THE SWELLING OF KRAFT BLACK LIQUOR DURING PYROLYSIS

During the drying and pyrolysis phases of kraft black liquor combustion, significant swelling of individual liquor particles occurs. Swollen volumes can reach 20 to 30 times the original volume during combustion. The swelling process can affect the combustibility of black liquor and the amount of carryover in a recovery furnace.

The composition of black liquor was found to have a large influence on swelling. A combination of sugar acids and kraft lignin swelled to a larger extent than when either component was pyrolyzed separately. A 1:1 ratio of these two components resulted in maximum swelling for the various ratios tested. The molecular weight of kraft lignin had an effect on swollen volume with higher molecular weight fractions producing lower swelling chars.

Other components were found to reduce the swelling of black liquors. Extractives interfered with the swelling by appearing to change the deformable properties of the pyrolyzing material. Inorganic salts acted as a diluent.

Analysis of the surface characteristics of chars revealed that good swelling chars were composed of small bubbles 50 to 150 microns in diameter. Poor swelling liquors did not exhibit this phenomenon. The formation of bubbles was found to be initiated at 240°C, which closely corresponded to the thermal decomposition temperature of a sugar acid. Kraft lignin appeared to have a major influence on the fluid properties of the pyrolyzing particle. The composition of black liquor determines to a large extent surface forces present in black liquor; these forces are thought to be responsible for the extent to which kraft black liquors deform and swell during pyrolysis.     

黑液制胶合板用胶粘剂的研究

本研究用纸厂度黑液经发酵法处理后，取代部分苯酚制取碱木素酚醛树脂胶作胶合板用胶粘剂．不但部分解决了黑液的利用和污染问题，且增加了胶合板用胶种．文中介绍了胶制备工艺的研究，讨论了黑液中碱木素分子量及分布等对胶性能影响，同时与普通酚醛胶性能和成本作了比较等．     

膜技术处理碱法草浆黑液及综合利用技术

通过膜分离技术处理碱法草浆黑液并回收碱的试验,探索造纸黑液处理的新工艺,以求找到一种碱法草浆黑液治理的新方法,取代投资高、能耗大的燃烧法碱回收工艺。该试验结果表明:通过混凝沉淀、膜分离处理过程,黑液中CODCr和色度去除率可达96.8%和99.3%,碱回用率可达78.2%。     

制浆黑液的超声膜法碱回收工艺

利用超声波的空化作用和超搅拌作用,研制出了制浆黑液的超声膜法碱回收工艺,该工艺可以有效地减缓黑液膜法碱回收时的膜污染,同时降低碱回收时的耗电量。配合混凝沉淀及生物处理,处理后的黑液可达到造纸业的中段水标准。     

蔗渣碱本素低温等离子体处理研究

从蔗渣纸浆黑液中分离提纯出蔗渣碱木素，然后在Ar．N_2及O_2等不同气氛下进行低温等离子体处理，得处理残存物及裂解产物。分析结果表明，在等离子体处理过程中，蔗渣碱木素有新的自由基生成．其含量随不同气氛而异，顺序为O_2＞N_2＞Ar；蔗渣碱木素处理残存物有O．N等元素嵌入，其玻璃化转变温度和热稳定性能提高；蔗渣碱木素苯丙烷基结构单元的侧链容易断裂，其木素裂解产物有较高的O和N等元素含量。