A Gasification Technology to Combine Oil Sludge with Coal-Water Slurry:CFD Analysis and Performance Determination

The development of more environment-friendly ways to dispose of oil sludge is currently regarded as a hot topic.In this context,gasification technologies are generally seen as a promising way to combine oil sludge with coal–water slurry(CWS)and generate resourceful fuel.In this study,a novel five-nozzle gasifier reactor was analyzed by means of a CFD(Computational fluid dynamic)method.Among several influential factors,special attention was paid to the height-to-diameter ratio of the gasifier and the mixing ratio of oil sludge,which are known to have a significant impact on the flow field,temperature distribution and gasifier performances.According to the numerical results,the optimal height-to-diameter ratio and oil mixing ratio are about 2.4:1 and 20%,respectively.Furthermore,the carbon conversion rate can become as high as 98.55%with the hydrolysis rate reaching a value of 53.88%.The consumption of raw coal and oxygen is generally reduced,while the effective gas production is increased to 50.93 mol/%.

Simulation Research on Coal-Water Slurry Gasification of Oil-Based Drill Cuttings Based on Fluent

In this paper,based on Fluent software,a five-nozzle gasifier reactor was established to simulate the gasification process of oil-based drill cuttings coal-water slurry.The influence of concentration and oxygen/carbon atomic ratio on the gasification process of oil-based drill cuttings coal-water slurry was investigated.The results show that when the oxygen flow is constant,the outlet temperature of gasifier decreases,the content of effective gas increases,and the carbon conversion rate decreases with the increase of concentration;When the ratio of oxygen to carbon atoms is constant,the effective gas content rises and the temperature rises with the increase of the concentration,and the carbon conversion rate reaches the maximum value when the concentration of oil-based drill cuttings coal-water slurry is 65%;When the concentration is constant,the effective gas content decreases and the outlet temperature rises with the increase of the oxygen/carbon atom ratio,and the carbon conversion rate reaches 99.80%when the oxygen/carbon atom ratio is 1.03.It shows that this method can effectively decompose the organic matter in oilbased drill cuttings and realize the efficient and cooperative treatment of oil-based drill cuttings.

Characteristics of coal sludge slurry prepared by a wet-grinding process

Coal sludge slurry(CSS) is an alternative fuel and a potential competitive method for sludge reduction.Based on the researches of coal water slurry, we studied CSSs by using a wet-grinding process with different types of regional municipal sludge(sludge) in an orthogonal experiment. The sludge type,sludge mixing proportion, dosage of dispersant, and grinding time were tested in this study. The results show that water content and its occurrence characteristics in the sludge have primary hindering influences on slurry ability. The range of fixed-viscosity concentrations with raw wet sludge is from 50.78%to 44.40%(by weight), while the range is from 53.35% to 51.51%(by weight) with dry sludge. All of the CSSs exhibit shear-thinning behaviors with different variation trends, especially the CSSs with more than 15%(by weight) raw wet sludge in it. Adding the same proportion of raw wet sludge increases the thixotropic properties of CSSs and the highest area of thixotropy loop is 3065 Pa/s, while the highest value of dry sludge is 1798 Pa/s. Hydrophilic group plays an important role in adsorbing water and building three-dimension networks with other particles, which is the main reason for CSS properties.Therefore, the mechanism can be used to find the way for making high quality CSS.

Effect of the benzene ring of the dispersant on the rheological characteristics of coal-water slurry:Experiments and theoretical calculations

In this study,low-rank coal-water slurry(LCWS)was prepared using polyoxyethylene dodecylphenol ether(PDPE)and polyoxyethylene lauryl ether(PLE),respectively.A combination of experiments and simulations was used to investigate the pulping properties and microscopic mechanism of the LCWS samples prepared using the two agents,so as to explore the influence of benzene ring on the performance of dispersant.The results of the LCWS preparation experiments revealed that the pulp-forming performance of PDPE exceeded that of PLE.When LCWS concentration is 62%,64%,and 66%,the apparent viscosity corresponding to PDPE is 247.80,504.17,and 653.10 mPa·s,and the apparent viscosity corresponding to PLE is 548.10,1470.61,and 1549.98 mPa·s,respectively.The C_(1000)(When the apparent viscosity is 1000 mPa·s,the corresponding concentration of LCWS is defined as C_(1000))values of PDPE and PLE are 67.60%and 62.95%,respectively.In addition to the van der Waals forces and hydrogen bonds between the PDPE and/or PLE molecules and coal,the benzene rings of PDPE presentπ-πstacking effect with the aromatic rings of coal.That could facilitate and strengthen the adsorption of PDPE on coal,which would be conducive to further improving the dispersion of coal particles.The two dispersants have no significant difference in effect on the pyrolysis of LCWS.The simulation results indicated that the times for PDPE and PLE molecules to reach flat adsorption state on coal are approximately 290 and 565 ps,respectively.The self-diffusion coefficient(D)of the PDPE and PLE on coal is 3.16 x 10^(-6)and6.57×10^(-6)m~2/s,respectively,and their interaction energies with coal are 785.71 and 648.60 kcal/mol,respectively.The results of the simulation calculations demonstrated that PDPE adsorbed on coal easier than PLE,and its binding is more stable than that of PLE owing to theπ-πstacking effect,which is conducive to uniform dispersion of coal in solution.The simulation results confirmed the experimental results.

Synthesis, characterization and application of a dispersant based on rosin for coal-water slurry

A rosin derivative and maleopimaric acid diethanolamide(MAD), was synthesized, characterized by FTIR and1 H NMR, and applied as dispersant for the coal-water slurry(CWS) prepared from Chinese Shenfu coal. The CWS application performance investigation shows that the MAD dispersant has better abilities in reducing CWS viscosity and stabilizing the slurry than a commercial dispersant—sulfonated naphthalene-formaldehyde condensate(SNF). The physicochemical property investigation of the two tested dispersants shows that the adsorption amount of the MAD at coal-water interface is much larger than that of SNF, and the MAD has better wetting property than the SNF on the coal surface. It indicated that the excellent capabilities of MAD are related to the adsorption mode of standing upright on the coal surface. Based on the above, the mechanism of dispersion and stabilization of the CWS prepared from MAD dispersant is presented.

Treatment of Biogas Slurry: One of Products of Sludge Anaerobic Digestion

The production of urban sludge is huge,and the anaerobic digestion of sludge is one of the important methods for sludge treatment at home and abroad.The products of sludge digestion can be further used as resources.In this study,biogas slurry,as one of products of sludge digestion,was deeply treated by intermittent and continuous aeration,and the feasibility of using biogas slurry in land was discussed.Meanwhile,the processing cost was analyzed.This study can provide support for the deep utilization of sludge digestion products.

Effect of the high-power electromagnetic pulses on the reactivity of the coal-water slurry in hot environment

An effect of the high-power electromagnetic pulses onto the droplet of coal-water slurry inside the furnace was investigated.In contrary to the previously investigated laser-induced fuel atomization that occurs at the room temperature,the pre-heated(to 400 K)slurry becomes dry enough to prevent the explosion-like steam formation.Thus,fuel does not atomize and the ignition does not accelerate.Furthermore,the absorption of several laser pulses leads to evident sintering of irradiated surface with following increase of the ignition delay time for up to 24%.Variation of the pulse energy in range 48-118 mJ(corresponding intensity up to 2.4 J·cm^-2)leads to certain variation of the increase of ignition delay.The strong pulsed overheating of the coal water slurry which does not initiate the fine atomization of the fuel generally makes its ignition longer.

Artificial neural network approach for rheological characteristics of coal-water slurry using microwave pre-treatment

Detailed experimental investigations were carried out for microwave pre-treatment of high ash Indian coal at high power level(900 W) in microwave oven. The microwave exposure times were fixed at60 s and 120 s. A rheology characteristic for microwave pre-treatment of coal-water slurry(CWS) was performed in an online Bohlin viscometer. The non-Newtonian character of the slurry follows the rheological model of Ostwald de Waele. The values of n and k vary from 0.31 to 0.64 and 0.19 to 0.81 Pa·sn,respectively. This paper presents an artificial neural network(ANN) model to predict the effects of operational parameters on apparent viscosity of CWS. A 4-2-1 topology with Levenberg-Marquardt training algorithm(trainlm) was selected as the controlled ANN. Mean squared error(MSE) of 0.002 and coefficient of multiple determinations(R^2) of 0.99 were obtained for the outperforming model. The promising values of correlation coefficient further confirm the robustness and satisfactory performance of the proposed ANN model.

A comparative investigation of the properties of coal-water slurries prepared from Australia and Shenhua coals

Two coal samples of similar rank were chosen from Australia and China to investigate the differences in Coal-Water Slurry （CWS） made from them. The effect of ash content and particle size gradation on these properties was also studied. Different grinding times were used when grinding the two coals and particle size analysis of these ground coals was used to select samples with a ＂double-peak＂ particle size distri- bution. All the ＂double-peak＂ samples were used to prepare a CWS. The concentration, viscosity, fluidity, and stability of each CWS were measured. The results show that the properties ofa CWS prepared from a coal sample with a ＂double-peak＂ size distribution are better than those CWS prepared from samples with a mono-modal particle distribution. The ash content of Australian coal is 21.72g higher than the ash content of Shenhua coal. The highest coal concentration in slurry from the Australia coal is 11.01% higher than in CWS from the Shenhua coat. The fluidity and stability of the CWS prepared from the Australian coal are both better than the fluidity and stability of slurry prepared from Shenhua coal. High ash content in the Australian coal imnroves the nulning results of a CWS made from it.

Combustion and Sulfur-fixing Performance of Pulping Black Liquor Coal-water Slurry

The effects of adding pulping black liquor and other additives to coal-water slurry(CWS) on the sulfur-fixing performance of the resultant mixture(pulping black liquor coal-water slurry) were evaluated. The experimental results demonstrated that the ash content of the black liquor coalwater slurry decreased as the addition of pulping black liquor in the mixture increased. Nevertheless, the addition amount should be appropriately selected to ensure that the black liquor coal-water slurry had a moderate calorific value. Addition of black liquor improved the combustion performance of CWS by lowering the ignition point and stabilizing the combustion process; moreover, the sulfur-fixation ratio after combustion increased by 12 to 16 percentage points than that of CWS, and the content of high-melting-point salt in the ash from CWS after adding black liquor was low. The sulfur-fixing ratio of CWS after adding a sulfur-fixing agent was effectively increased by 25 to 30 percenatge points, but with compromise of the fluidity and stability of the CWS; thus, the addition amount of a sulfur-fixing agent should be optimized.

A novel 3-layer mixed cultural evolutionary optimization framework for optimal operation of syngas production in a Texaco coal-water slurry gasifier

Optimizing operational parameters for syngas production of Texaco coal-water slurry gasifier studied in this paper is a complicated nonlinear constrained problem concerning 3 BP(Error Back Propagation) neural networks. To solve this model, a new 3-layer cultural evolving algorithm framework which has a population space, a medium space and a belief space is firstly conceived. Standard differential evolution algorithm(DE), genetic algorithm(GA), and particle swarm optimization algorithm(PSO) are embedded in this framework to build 3-layer mixed cultural DE/GA/PSO(3LM-CDE, 3LM-CGA, and 3LM-CPSO) algorithms. The accuracy and efficiency of the proposed hybrid algorithms are firstly tested in 20 benchmark nonlinear constrained functions. Then, the operational optimization model for syngas production in a Texaco coal-water slurry gasifier of a real-world chemical plant is solved effectively. The simulation results are encouraging that the 3-layer cultural algorithm evolving framework suggests ways in which the performance of DE, GA, PSO and other population-based evolutionary algorithms(EAs) can be improved,and the optimal operational parameters based on 3LM-CDE algorithm of the syngas production in the Texaco coalwater slurry gasifier shows outstanding computing results than actual industry use and other algorithms.

深圳某生物质沼液处理厂工程设计

深圳某生物质沼液处理厂设计规模700 t/d,主体采用“预处理+亚硝酸硝化/反硝化-AO+MBR+NF”工艺,该污水处理厂处理后产水水质满足《水污染物排放限值》(DB 44/26—2001)第二时段排放标准。污泥处理系统采用离心处理,处理后的污泥堆肥或焚烧。该污水处理厂在设计工程中采用了一些新理念、新技术,成为了一座资源化、现代化的污水处理厂。

CaF_(2)污泥对硅酸盐水泥性能的影响及机理分析

固废利用是实现“双碳”目标的重要途径之一。本文以固废CaF_(2)污泥为水泥掺合料,通过抗压强度、浆体流动度试验探讨了CaF_(2)污泥掺量对水泥胶凝材料性能的影响,并结合XRD、SEM及TGA-DSC等微观表征测试进行机理分析。结果表明,CaF_(2)污泥的掺加有利于提高水泥胶凝材料的早期强度,CaF_(2)污泥掺量为8%(质量分数)的胶凝材料抗压强度表现较好。CaF_(2)污泥的掺加会导致浆体流动度降低,但掺量低于10%(质量分数)时对浆体流动度影响并不显著,掺量为8%、10%(质量分数)时浆体流动度比未掺加CaF_(2)污泥时降低了3.0%。CaF_(2)污泥在胶凝材料中主要起物理效应,CaF_(2)污泥能够形成更多的结晶位点,促进水泥水化。CaF_(2)污泥掺量增加使水泥的稀释效应及团聚效应显著。掺量为8%(质量分数)的CaF_(2)污泥复合水泥的微观性能较好。

基于氧化/混凝的污泥和疏浚泥浆泥水分离技术探讨

在污水处理、河湖疏浚过程中,必不可免会产生副产物污泥和疏浚泥浆,其体积大且含水率高。为避免对环境二次污染,减少堆放面积,国内外研究者均对污泥和疏浚泥浆高效泥水分离减容方法展开了系统研究。本文综述了采用氧化、混凝以及氧化协同混凝方法进行污泥和疏浚泥浆泥水分离的研究进展,并提出了基于氧化/混凝的污泥和疏浚泥浆泥水分离技术研究和发展方向。

煤制氢装置气化炉协同处置“三泥”探讨

某炼厂拟将来自污水处理场的浮渣/油泥和活性污泥送至煤制氢装置气化炉协同处置,以实现“三泥”的资源化利用。其中浮渣/油泥设计处理量4.2万吨/年,活性污泥设计处理量2.1万吨/年。根据掺配比例实验结果,浮渣/油泥、活性污泥按一定比例混合后,与水煤浆的掺配比例不宜大于12%。根据测算,项目实施后,装置进出料变化不明显,改造后硫含量比改造前增加约24吨/年。浮渣/油泥、活性污泥掺烧后产生废渣量较之前增加约0.2万吨/年。可减少能耗折算成标油为882.18吨/年,减少碳排放量399.41吨/年,环境效益明显。

锰铁矿泥水分离絮凝剂选型研究

为了提高锰铁矿石回收率,在回收过程中需要消耗大量水资源对矿石进行洗选,洗矿产生的废弃泥浆水如何处理成为企业难题。同时,选矿厂位于喀斯特地貌区,使得企业取水用水困难,在旱季严重影响选矿效率。本工作针对以上难题,以提高资源的循环利用率和节约企业生产成本为目标。根据泥浆水成分开展絮凝剂优选实验,采用对比分析法,优选出适合锰铁矿泥水分离的絮凝剂组合类型与配制浓度,再利用控制变量法优化絮凝剂用量。对絮凝剂沉降原理进行分析,发现APAM对含碱性粒子的锰铁矿泥水分离具有更好的沉降效果,优先加入阴离子絮凝剂进行电中和,破坏颗粒间的稳定状态,混凝剂(3-3)的加入利于发挥架桥作用,并通过液体扰动,增加颗粒之间碰撞概率,实现网捕和卷扫作用。实验结果表明,当进料浓度为20%、絮凝剂浓度为2‰时,阴离子聚丙烯酰胺(APAM)与高分子混凝剂(3-3)复合使用效果优于单独使用其中任何一种。在ω(APAM)∶ω(3-3)=1∶2条件下,絮凝沉降效果最佳。经过沉降和过滤后,分离出的水资源可有效利用于上游循环洗矿,而不会对矿石产生不利影响,从而显著提高选矿效率。这种方法还为企业节省了大量成本,并且无需建造尾矿库。

市政污泥“热水解+高含固厌氧消化”处理工艺设计浅析

厌氧消化工艺因具有良好的污泥稳定化、减量化、资源化特性而在市政污泥处理中得到广泛应用,而“热水解+高含固厌氧消化”工艺具有减少厌氧消化系统占地和投资、大幅提升厌氧消化效率的特点,该工艺可彻底实现污泥无害化,更好实现污泥减量化、稳定化和资源化,在市政污泥处理应用中具有广阔前景。文章依托国内“热水解+高含固厌氧消化”工艺实际工程案例,对工艺流程和各系统组成进行梳理和分析,梳理工艺设计关键参数,并对该工艺的特点及设计要点进行分析,为类似项目的工程设计提供参考。

废弃物处置协同制备水煤浆技术研究进展

阐述了近年来人们掺配不同废液与废固所制水煤浆的浆体性质,其中包括焦化废水、含油废水、印染废水、造纸黑液等废液所制水煤浆以及采用化工污泥、含油污泥、煤气化细渣、煤泥等固废所制水煤浆,分析了不同预处理与改性方式对浆体性能的影响,并对掺配废弃物制浆的技术瓶颈与未来发展趋势进行了展望。

生化污泥资源化利用

传统生化污泥的利用方式主要采用直接填埋、农业堆肥、焚烧、建工建材等,易对环境造成污染,而且污泥中的C、H等成分得不到有效利用。随着我国工业的大型化发展,生产污泥的排放量也随之增加,如何实现生化污泥低处理费用和降低环境污染是企业目前需要解决的问题。从生化污泥传统利用方式存在的问题着手,分析新开发的一种煤气化协同处理方式,包括水煤浆协同生化污泥处理技术、干煤粉掺混生化污泥及对装置产生的影响。

气化细灰高碳组分和化工污泥与煤协同制浆研究

对气化细灰高碳组分和化工污泥与煤协同制浆进行研究,有助于气化细灰和煤化工污泥的减量化及资源化利用,可为开发煤化工固废与煤协同制备高质量气化水煤浆技术提供支撑。针对气化细灰高碳组分和化工污泥在与煤协同制浆过程中存在的煤浆质量差的关键问题,采用气化细灰高碳组分和改性化工污泥与煤掺混制浆,通过分析固废不同研磨时间和掺混比例对混合煤浆黏度、流动性、粒度分布、纳米CT技术和接触角的影响,揭示煤化工固废的掺入对煤浆性能的作用机制。结果表明,改性污泥和高碳细灰与煤直接掺混制浆,掺混量每增加1个百分点,煤浆浓度降低约0.3~0.7个百分点;通过细磨或超细磨则可改善改性污泥、高碳细灰对煤浆成浆浓度的影响,在相同条件下与不进行研磨的制浆工艺相比,细磨后的煤浆浓度提升0.3~0.4个百分点。由于细灰和污泥的加入而使制浆原料与水的接触角降低,成浆性变差,煤浆浓度降低;细磨后的细灰、污泥与煤之间形成粒度级配,超细颗粒包覆在粗颗粒表面而具有润滑的作用,从而导致研磨后的固废掺入对煤浆浓度的影响降低。