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/%.

Effects of fractal surface on rheological behavior and combustion kinetics of modified brown coal water slurries

The paper reports the effects of surface fractal structures on the rheological behavior and combustion kinetics of raw brown coal and three modified coal water slurries （CWSs）. The results show that the fractal structures and physicochemical properties of samples are dependent on various modification processes. The apparent viscosities of the coal water slurries increase with increasing surface fractal dimensions （D）, especially with decreasing shear rates. Fur- thermore, it has been proved that the ignition temperatures and apparent activation energies of modified CWSs are lower than that of raw coal water slurry. Compared with the traditional qualitative analysis of the effect of pore structures on CWSs properties, D can more efficiently indicate the quantificational effect of pore structures on the rheological behavior and combustion kinetics of CWSs.

CFD simulation on the gasification of asphalt water slurry in an entrained flow gasifier

Gasification technology is suggested to utilize asphalt particles, which are produced in the heavy oil deep separation process of using coupled low temperature separation of solvent and post extraction residue. In this work, the asphalt particles were first slurried with water and then gasified to produce synthesis gas. The gasification process of asphalt water slurry in an entrained flow gasifier was simulated using a three-dimensional computational fluid dynamics （CFD） model based on an Eulerian- Lagrangian method. The trajectories and residence time of asphalt particles, and the reaction rates, gas species distribution, temperature field and carbon conversion in the entrained flow gasifier were obtained. The predicted results indicated that the asphalt water slurry was a good feedstock for gasification. Moreover, the effects of particle size, oxygen equivalence ratio, and mass content of asphalt particles on the gasification performance of asphalt water slurry were investigated. These results are helpful for industrial application of asphalt water slurry gasification technology.

Effects of pH on rheological characteristics and stability of petroleum coke water slurry

In this study, the effects of pH on slurrying properties of petroleum coke water slurry（PCWS） were investigated. The slurrying concentration, rheological characteristics and stability of PCWS were studied with four different types of additives at pH varying from 5 to 11.The results showed that the slurrying concentration, rheological characteristics and stability of PCWS all increased at first and then decreased with increasing pH from 5 to 11,and a pH of around 9 was found to be the most favorable acid–alkali environment to all these three slurrying properties. It was also indicated that only in a moderate alkaline environment can the additives be active enough to react with particle surfaces sufficiently to obtain good slurrying concentration and form a stable three-dimensional network structure, which can support strong pseudoplastic characteristics and good stability. An acid environment was a very unfavorable factor to the slurrying properties of PCWS.

Inherent relations between yield stress and stability of bubble petroleum coke water slurry

The stability of petroleum coke water slurry（PCWS） is currently a hot topic. The inherent relationship between yield stress and stability of bubble-PCWS was studied through orthogonal experiments and range analysis in this work. The results showed that the stability of bubble-PCWS was positively related to the yield stress and that the yield stress could be greatly impacted by the operation conditions during preparation of bubble-PCWS. The main factors affecting the yield stress of bubble-PCWS were solid concentration, aeration time and dosage of frother. However, the effects of aperture size of air distribution plates and type of frother on the yield stress were slight within the experimental range. The optimal conditions for the greatest yield stress were as follows： aeration time of 30 min, solid concentration of 65 wt%, frother dosage of0.030 wt% of the air-dried pulverized petroleum coke, aperture size of air distribution plate of 2-5 lm and AOS frother.The yield stress and the pour rate of bubble-PCWS under this optimum operation condition could reach maxima of more than 0.4 Pa and 96%, respectively.

Simulation analysis of ammonia distribution in methanol production from coal water slurry gasification

Aspen plus software was employed to simulate process. The system concludes gasification scrubbing system the opposed multi-burner gasifier （OMB） methanol production and purification shift system. The distributions of ammonia con- centration in streams were obtained. The study demonstrates that ammonium crystallization problem caused by ammonia ac- cumulation, and if the process has ammonia exports its concentration will greatly reduced and the ammonia salt problem will effectively alleviate. Aspen plus simulation is a useful tool strengthening the ammonia recycling use and reducing pollutant for improving water quality, maintaining stable production, emissions.

Blended coals for improved coal water slurries

Three coal samples of different ranks were used to study the effect of coal blending on the preparation of Coal Water Slurry (CWS). The results show that by taking advantage of two kinds of coal, the coal concentration in slurry made from hard-to-pulp coal can be effectively improved and increased by 3%–5% generally. DLT coal (DaLiuTa coal mine) is very poor in slurryability and the stability and rheology of the resulting slurry are not very good. When the amount of easily slurried coal is more than 30%, all properties of the CWS improve and the CWS meets the requirements for use as fuel. Coalification, porosity, surface oxygenic functional groups, zeta potential and grindability have a great effect on the performance of blended coal CWS. This leads to some differences in performance between the slurry made from a single coal and slurry made from blended coal.

Life Cycle Assessment of Ultra-clean Micronized Coal Oil Water Slurry

Life cycle assessment is applied to assess the ultra-clean micronized coal oil water slurry (UCMCOWS) with SimaPro and the environmental impact of UCMCOWS on its whole life cycle is also analyzed. The result shows that the consumption of energy and products are increasing along with the deepening of UCMCOWS processing, UCMCOWS making and combustion are the two periods which have a bigger impact on eco-system and human health. As a new substitute of fuel, UCMCOWS merits to be utilized more efficiently and reasonably.

Application of coal-water slurry on the rotary calcining kiln of pedgion magnesium reduction process

Energy saving has been an important concept in modern industry especially to the countries and regions with energy shortage such as China and Japan. Utilization of Coal-Water Slurry （CWS） can improve the burning efficiency of coal and reduce the pollutions of soot, sulfide and the nitride by burning lump coal directly. The CWS is a promising energy saving technique and the effectual substitute of oil. The study on the preparation and application of the CWS has made progresses in many aspects. The present paper studied the basal problems for applying the CWS on the rotary kilns during the calcining-dolomite process in the magnesium factory, summarized the key points for the application process of the CWS and gave the corresponding solutions.

Theoretical Models of Light Scattering Applied in Sizing Particles in Coal Water Slurry

Advantges and disadvantage of Mie scattering model and Fraunhofer diffraction model are discussed. The result shows that 1) the Fraunhofer diffraction model is simple in design and fast in operation, which is quite suitable for on-line control and 2) the intensity and energy distribution of diffracted light of both the Mie scattering model and the Fraunhofer theoretical model are compared and researched. Feasibility of using the Fraunhofer diffraction model to replace the Mie scattering model in measuring particles in coal water slurry is demonstrated.

Characterization of coal water slurry prepared for PRB coal

Powder River Basin(PRB)coal,which accounts for over 40%of the coal consumed for power generation in the United States,was investigated for preparation of coal water slurry(CWS).The static stability and rheology of the CWS were characterized as a function of loading.The coal loading was varied from 30%to 50%and both ionic(sodium polystyrene sulphonate(PSS))and nonionic(Triton X-100)surfactants were employed as additives.The addition of PSS to PRB slurries was found to yield poor static stability.On the other hand,Triton X-100 was found to be an effective surfactant,reducing the sedimentation by more than 50%compared to the one without surfactant in 45%CWS.Adding Triton X-100 reduces the viscosity of the CWS for coal loadings of30%and 40%.Although the viscosities for coal loading of 42.5%and 45%are higher when Triton X-100 is added,the static stability is significantly better than for samples without surfactant.The highest coal loading for PRB slurry with acceptable viscosity for pumping is 42.5%.

Flow Behavior of Clay-Silt to Sand-Silt Water-Rich Suspensions at Low to High Shear Rates: Implications for Slurries, Transitional Flows, and Submarine Debris-Flows

Water-rich clay to sand suspensions show a shear rate dependent flow behavior and knowledge of the appropriate rheological model is relevant for sedimentological, industrial and hydraulic studies. We present experimental rheological measurements of water-rich(40 to 60 wt%) clay to silt(population A) and silt to sand(population B) suspensions mixed in different proportions. The data evidence a shear rate dependent shear thinning-shear thickening transition. At lower shear rates, the suspensions organize in chains of particles, whereas at higher shear rates, these chains disrupt so increasing the viscosity. The viscosity, consistency and yield stress decrease as the A+B fraction decreases as the content of B particles increases. This behavior reflects the competing effects of the lubrication and frictional processes as a function of particle size and water content. Transitional flows form by the incorporation of small amounts of the finer fraction while ‘oceanic floods’ form at the estuary of rivers and the submarine debris-flows increase their velocity by incorporating water. The critical Reynolds number of the studied suspensions is ～2000±100 suggesting that the grainsize plays a major role in the laminar to turbulent transition. Our results have implications for the modeling of sediment flows and the hazard related to floods.

Main Influencing Factors on Service Life of High Chrome Refractories for Coal Water Slurry Gasifiers

The main characteristics of high chrome refractories for coal water slurry gasifiers were introduced. The damage mechanism of the refractories was analyzed by observing the microstructure of the used high chrome refractories with the aid of SEM. The main influencing factors on the service life of the refractories were summarized.

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.

Changing Concentrations of Heavy Metals in Stream Water as a Result of Slurry Application to Soil

Several studies focused on nutrients have shown that land use and management practices have a strong influence on stream chemistry. Much less is known about the relationship between heavy metal concentrations in stream water and land use. We compared the variability of trace element concentrations in the stream of a catchment exposed to different types of management practices and land use. This is a small catchment with previous agricultural diffuse and accidental pollution mainly due to the spreading of slurry. The agricultural land was reforested in July 1998. The concentrations of Fe, Mn, Cu and Zn in dissolved phase from surface water samples collected at the catchment outlet were determined over a period of approximately six years. The results suggest that dissolved metal concentrations, especially Cu and Mn, are controlled by the land use and management practices. The median concentrations of studied metals were the highest in the agricultural period. It was also during this period when they all presented the highest concentration peaks, coinciding with a time of heavy application of manure to the soil. Dissolved Fe and Mn showed high dependence of flow rate, whereas Cu and Zn concentrations seemed to be independent of flow.

CORRECTION OF WALL SLIP EFFECTS AND RHEOLOGICAL MEASUREMENT OF HIGH CONCENTRATED COAL WATER SLURRY

Coal-water slurry, a ncw liquid fuel, began to appcar during the world-wide petroleum crisis in the seventies of this century. Its applications to substitute petroleum drew great attention on the investigations of its preparation, combustion and transportation, etc. The rheological behavior is an important quality index for the fuel. However, the conventional viscosimeters designed for true fluids are not suited to the high concentrated slurry due to the complicated rheological bchavior. A special viscosimeter of tube type was rcpresented, which was designed and set up by the authors for the measurement of the theology of high concentrated coal-water slurry and experiments were conducted with two kinds of slurries from P. R. China. In consideration of the wall sliD effects the correction of the experimental data were made.

Preparation of Al-Zn-Mg-Cu alloy semisolid slurry through a water-cooled serpentine pouring channel

The semisolid slurry of Al-Zn-Mg-Cu alloy was prepared through a self-designed water-cooled copper serpentine pouring channel(WSPC) machine. Influences of pouring temperature, the number of turns and the cooling water flow rate on the microstructure of the semisolid Al-Zn-Mg-Cu alloy slurry were investigated. The results show that the semisolid Al-Zn-Mg-Cu alloy slurry with satisfactory quality can be generated by the WSPC when the pouring temperature is in the range between 680 ℃ and 700 ℃. At a given pouring temperature, the average grain size of primary α-Al decreases and the shape factor increases with the increase of the number of turns. When the cooling water flow rate is 450 L·h^(-1), the obtained semisolid slurry is optimal. During the preparation of the semisolid Al-Zn-Mg-Cu alloy slurry with low superheat pouring, the alloy melt has mixed inhibition and convection flow characteristics by "self-stirring". When the alloy melt flows through the serpentine channel, the chilling effect of the inner wall of the channel, the convection and mixed inhibition of the alloy melt greatly promote the heterogeneous nucleation and grain segregation. This effect destroys the dendrite growth mode under traditional solidification conditions, and the primary nuclei gradually evolve into spherical or nearspherical grains.

盾构废弃粉质黏土泥浆底部真空脱水试验研究

盾构施工中产生的废弃粉质黏土泥浆具有含水率高、强度低、颗粒粒径较小及难以快速固结的特点,脱水处置难度大;如何对其进行有效的脱水固化处理,是减少其在运输或存储过程中污染环境的关键。基于自行研制的废弃泥浆真空脱水装置,开展自重、自重+真空、自重稳定+真空、自重稳定+分级真空等4种不同形式下的室内脱水模型试验研究,分析废弃粉质黏土泥浆在不同的加载方式下泥—水界面沉降、孔隙水压力、脱水量以及脱水后残余泥浆含水率的变化规律,并对不同加载方式下对废弃粉质黏土泥浆的脱水效果进行对比。试验结果表明:4种脱水方式中,先对废弃粉质黏土泥浆进行自重脱水处理、再对其底部分级施加真空作用的加载方式对废弃粉质黏土泥浆的脱水效果最好,可有效降低废弃粉质黏土泥浆的含水率;采用该方法对初始含水率为97.50%的废弃粉质黏土泥浆进行脱水处理后,其含水率分布范围介于28.21%~34.25%,其内部孔隙水压力最小可达-72.92 kPa。同时,基于分段线性化的思想建立了废弃泥浆一维脱水理论分析模型,对废弃粉质黏土泥浆在脱水过程中的泥—水界面沉降进行数值模拟,并将数值模拟与试验结果进行了对比分析;随后通过对不同加载方式下脱水效率进行模拟分析探究了最佳加载方式。该研究可为盾构废弃粉质黏土泥浆快速脱水处理提供理论基础和实践依据。

SAP联合双液浆对软土地区隧道漏水漏砂封堵效果试验研究

在高承压水软土地区盾构隧道修建过程中经常出现漏水漏砂险情,注浆封堵是常用的抢险方法之一。而在承压水层或者地层出现空腔情况下注浆时,传统的双液浆在注入后抗冲刷能力差,浆液留存率较低,严重影响抢险效率,难以在抢险的黄金时期控制住险情。因此,提出一种隧道漏水漏砂抢险的新型注浆方式,即高分子吸水树脂(SAP)与双液浆联合注浆,并通过室内模型试验研究了此方法的有效性,分析SAP注入方式、SAP种类、双液浆水灰比、渗漏流速等对注浆封堵效果的影响,并探究最优的注浆方式与封堵机理。研究结果表明,SAP吸水后,颗粒大、动水留存率高、吸水速度不受温度影响,能够填充地层侵蚀空腔,封堵渗漏或者减小渗漏水流速。本文试验条件下,以水泥浆液为载体注入SAP为最优注入方式,水灰比0.6的水泥浆液与吸水后的B类SAP均匀混合后,与水玻璃进行双液注浆,能避免跑浆,实现地层空腔与渗漏水的完全封堵。本文提出的新型注浆方式能够大幅增加双液浆的动水留存率,同时弥补SAP强度较低的缺陷,保证注浆体的整体性和地层支撑性,实现基坑与隧道等地下工程漏水漏砂灾害的快速有效控制。

微咸水与沼液一体化灌溉对设施番茄干物质累积和产量品质的影响

【目的】探明微咸水与沼液一体化灌溉对设施番茄植株干物质累积、果实产量及品质的影响,获得适宜番茄生长发育的微咸水矿化度阈值。【方法】以设施番茄为研究对象,于2022年和2023年开展了两季大田试验,在番茄3个生育期(苗期、开花坐果期、成熟期)设置3个灌溉水矿化度(2、3、5 g/L),探求番茄干物质累积、产量、灌溉水利用效率、果实离子量和品质的响应规律,并采用主成分分析法和组合评价法分别对番茄果实品质及综合效益进行评价。【结果】苗期和开花坐果期使用5 g/L的微咸水与沼液一体化灌溉会抑制番茄各部位干物质量的增加;微咸水与沼液一体化灌溉均会降低番茄最终的产量,其降低主要是通过减少番茄单果质量来实现的,而对单株坐果数影响并不显著。但基于主成分分析法的番茄果实综合品质得分均有所提高;T4处理(苗期2g/L、开花坐果期3 g/L、成熟期5 g/L)番茄综合生产效益得分最高;各处理在一定程度上均降低了番茄果实对Na^(+)、Ca^(2+)的积累。【结论】基于组合评价法的番茄综合效益评价结果表明,在淡水资源紧缺微咸水资源丰富的地区,建议在番茄苗期使用2 g/L、开花坐果期使用3 g/L、成熟期使用5 g/L的微咸水与沼液一体化灌溉模式。