Combustion of mono-fractional droplets of coal-oil mixtures

The ignition of oil and coal particles and the combustion time of the coal-oil mixtures droplet, have been discussed on the basis of a mathematical model. When the COM droplets are larger than those of pure oil then ignition of the COM spray is more difficult. Combustion of the oil part of the mixture needs less time as it has a larger surface area. It has been found that when suitably fine coal particles are used in COM preparation and when the particles do not agglomerate, the overall combustion time of the COM droplet can be shorter than that of pure oil droplets of the same size.     

Low viscosity COM (coal oil mixture) using tall-oil as an additive

Tall oil, an inexpensive by-product from pulp manufacturing (about one-tenth of the cost to those of ordinary surfactants), was found as an effective additive for COM (coal oil mixture) to provide good stability and low viscosity. The viscosity of COM (coal concentration: 50%) was as low as 2 Pa at 70 °C after 25 day-storage by addition of only 1% of tall-oil to COM. Tall-oil supported an increase in concentration of coal from 46% to 52.5%, maintaining usable viscosity. Structural viscosity (SV) of COM was proposed by the authors and defined as follows: SV = η(2.2)−η(22); where η(2.2) and η(22) are the viscosities at low shear rate (2.2 s⁻¹) and high shear rate (22 s⁻¹), respectively. The SV was found to be a good parameter for predicting the sedimentation stability and the viscosity of COM after long-term storage in the case of Miike-COM.     

马来酸酐-丙烯酸酯类共聚物作油煤浆燃料稳定剂研究

以马来酸酐与丙烯酸酯的共聚物为稳定剂,当共聚物中,n(马来酸酐):n(丙烯酸丁酯)=1:5,用吡啶中和,稳定剂的添加量为0.4%时,油煤浆(COM)燃料在3个星期后的棒惯时间仍然小于2 s,碳粉的最高质量含量可达59.4%.该稳定剂用量少、原料易得,有较好的应用前景.     

Determination of the stability of coal-oil mixtures (COM) by infrared analysis

The stability of coal-oil mixtures (COM) may be assessed by using infrared (i.r.) spectroscopy. An i.r. spectrum of a COM has analytical bands at 540 cm^?1 for coal and at 810 cm^?1 for oil; these bands are used to determine the change in concentration of coal in a COM with time. The i.r. spectra provides information on the possible interactions between the two materials and an indication of the physico-chemical properties of such mixtures.     

COM燃料用稳定剂的研究

使在ｐＨ值为４．５的酸性水溶液中缩合１０ｍｉｎ的０．１ｍｏｌ六羟甲基三聚氰胺先与８０ｍｏｌＰＯ加成后,再与４０ｍｏｌＥＯ加成,将共聚加成物再用０．３ｍｏｌＴＭＩ进行端基交联,所得化合物对高浓度煤粉在燃油中的分散具有优异的稳定性。添加０．４％,可使ｗ（煤粉）＝５５％的ＣＯＭ燃料４周后的棒贯时间仍小于２ｓ。此研究为制备高浓度、高稳定性的ＣＯＭ开发了一种优质稳定剂。     

Coal-oil mixture technology in the US

Coal-oil mixtures (COMs) have undergone periodic development over the last 100 years. However, commercial usage of COM has never been implemented because of the low cost and ready availability of oil, except during periods of national emergencies. The current interest in COMs was stimulated by the oil crisis of 1973, followed by substantial increase in the price of oil. The potential market of existing oil-fired combustors within the US for conversion to COM is substantial, consisting of oil-fired utility boilers, industrial boilers, blast furnaces and process heaters. The utilization of COM involves preparation, storage, transportation and combustion. COM fuels are prepared by either dry- or wet-grinding processes. In addition, by introducing coal beneficiation into the process, a low-sulphur, low-ash COM can be prepared. The COM preparation processes under development produce a variety of COM types which have differing characteristics. These differences arise primarily from methods used to stabilize the coal suspension in the oil. The preparation, stability, and rheology of COMs, and the status of processes under development within the US are discussed. Recently, short-term combustion tests (<500 h) have been performed. However, extended tests are still required to demonstrate reliable and long-term operation. Details of the required retrofit and the combustion tests are examined. The US COM programme, as it is planned, is expected to provide the basis for commercialization of COMs in the mid-80s. It is concluded that the market for this fuel is potentially large and the economics for commercialization favourable, as long as there is sufficient difference between coal and oil prices.     

Effect of particle size and shape on settling using an integral approach

This study was undertaken to investigate a settling system having no chemical interactions between the liquid and solid in an effort to establish a base for analysis of the more complex coal—oil systems that have great potential to be used as a fuel in boilers. Glass spheres and crushed glass particles in a model oil having similar properties to No. 6 fuel oil were employed. Particle size and shape, concentrations of solids, temperature and initial mixture heights were studied by use of Smiles integral analysis for settling. A pseudo-diffusion coefficient was determined which predicted the settling behavior over the entire settling time.     

Rheological propertis of coal—oil mixture fuels

The rheological properties of coal—oil mixtures (COM) of a bituminous coal in four types of oil, grade 2, grade 4, light grade 6 and heavy grade 6, have been studied. Variables investigated were the coal concentration (0 – 60 wt.%), coal particle size (10 < d₅₀ < 40 μm), temperature (25 – 90 °C) and time effects (0 – 6 days).

Rheograms were obtained using the Ferranti-Shirley cone and plate viscometer. The COM was classified as a Newtonian fluid at coal concentrations up to 30 wt.% and as a Bingham plastic at higher values. The relative viscosity was found to increase rapidly with coal concentration, reaching 100 for a 60 wt.% of COM.

Both COM viscosity and yield stress decrease with increasing median particle size and decreasing slope of the particle size distribution. This effect is stronger at high solids concentrations.

The COM viscosity is much less sensitive to temperature than the base oil. The COM yield stress increases up to 350 Pa with increasing coal concentration, decreasing temperature and ageing.     

内旋式移动床煤热解新工艺开发及试验

采用2t/d外热内旋式移动床热解试验装置,通过控制反应器物料热解区及粉尘沉降气室区的温度,研究了内旋式移动床工艺温度分布对13mm以下神木煤热解产物产率及性质的影响规律。结果表明：物料热解温度控制为650℃和700℃时,煤料均实现了较好热解,半焦挥发分V_daf降低至10.36%～11.95%;相同物料热解温度,提高粉尘沉降气室温度后,辐射传热作用增强,半焦和焦油产率降低,煤气产率升高;在物料热解温度700℃,粉尘沉降气室温度500℃时,焦油收率Tar_d最高,为7.44%;物料热解温度为650℃,焦油模拟蒸馏360℃以下馏分含量为63.3%～72.0%,物料热解温度700℃时为67.5%～72.2%;相同物料热解温度,提高粉尘沉降气室温度后,焦油中轻油组分减少,洗油和沥青质含量增加,煤气中氢气含量增加;粉尘沉降气室温度达到550℃时,挥发物二次反应作用明显强于450℃和500℃;各工艺条件下,焦油中喹啉不溶物含量均低于1%,最低为0.51%。     

Settling stability of coal slurries prepared by wet grinding in the szego mill

Static sedimentation experiments on coal-#2 oil and coal-water slurries, wet ground in a Szego mill, were conducted. These slurries contain more flaky particles as compared to those conventionally ground. Concentration and size distribution of the coal, diameter and height of the settling columns and settling time were the independent variables. Coal concentration and particle size distribution along the columns, and settling rates were measured. Despite their particle shape differences, these slurries were similar to others in terms of settling stability due to particle flocculation.     

Molecular modeling of the structure and properties of coal organic matter

The algorithms and results of molecular modeling of the structure and (physicochemical and processing) properties of coal organic matter (COM) and its components (macerals) based on two approaches, (1) a generalized model of the COM structure and (2) the concept of a self-associated multimer in the COM structure of have been presented. A set of structural parameters characterizing the molecules of organic and hetero-organic compounds that simulate the structure of coals is used in the first approach, and the structure of the organic substance of coal in the second approach is treated as a mixture of superimposed individual components with known values of the properties of interest reflecting the structural features of the organic matter and elemental composition of coal.     

WTW车用煤基燃料的经济性与环保性研究

为了研究WTW车用燃料的经济性与环保性,利用GREET模型对煤间接液化合成油、煤直接液化合成油、煤制天然气和整体煤气化联合循环发电IGCC 4种煤基燃料进行WTW计算,并对比分析了4种燃料在WTW各个阶段的能耗和CO2排放量。结果表明：4种煤基燃料的能耗由大到小为煤制天然气〉煤间接液化合成油〉煤直接液化合成油〉IGCC,其中煤间接液化合成油、煤直接液化合成油及煤制天然气的能耗都约为传统柴油或汽油的2倍,IGCC的总能耗是传统汽油的3/5左右;CO2排放排序为：煤间接液化合成油〉煤制天然气〉煤直接液化合成油〉IGCC,其中煤间接液化合成油、煤直接液化合成油和煤制天然气的CO2排放量都为传统柴油或汽油的1.6～3.1倍,IGCC的CO2排放量是传统汽油的7/10左右;煤间接、直接液化合成油和煤制天然气都有一定的市场竞争力,IGCC成本较高,且高于传统发电成本。     

Thermal separation of coal-oil suspensions in a fluidised bed

A series of experiments were made on the thermal separation of various mixtures of coal in oil using a fluidized bed reactor. The majority of experiments were carried out on a mixture of 30% w/w Edmonton coal in 70% w/w Leduc crude oil in a temperature range of 700–900°F. The products of the reaction were a char, an oil and a gas. At temperatures above 700°F. the solid particles became dry and free-flowing; no agglomeration or channelling in the bed was apparent. An increase in reactor temperature in the 700–900°F. range decreased the amount of residual oil on the char from about 2% to 0.1% at the same time the heating value of the char rose from 11,900 to 12,600 Btu/lb. Carbon residue of the product oil was substantially less than that of the original oil, the reduction being about 50% in the case of Leduc oil and 75% for Lloydminster oil.     

粉体粒度对神府煤制备高性能水煤浆的影响

神府煤内水含量高、氧碳比高,不利于湿法气化制备高性能水煤浆。选择神府同一矿区的原煤、洗煤,通过干磨湿配制浆,并对煤浆性能进行分析。结果表明,煤的可磨指数HGI与磨矿时间共同决定粉体的粒度分布,粉体粒度与煤浆的流动性及稳定性直接相关,磨矿过程应尽可能使粉体粒度偏细。粒度〉0.20 mm的粉体主要影响煤浆的稳定性,较多的大颗粒会因重力沉降作用导致煤浆性能变差;粒度〈0.076 mm的粉体主要影响煤浆的流动性,合适的质量比配能与大颗粒形成双级或多级级配。SFR、SFX制浆性能较好时粒度〈0.076 mm的粉体分别占45%、50%。     

Non-isothermal liquefaction of liptobiolith coal in supercritical water flow and effect of zinc additives

The liquefaction of liptobiolith coal in water vapor and supercritical water (SCW) flow at uniform increase in temperature from 300 up to 470 °C and in SCW flow at 400 °C (30 MPa) with addition of zinc shavings to coal has been investigated. Temperature dependences of the yield of liquid and volatile products and kinetic parameters of the process have been obtained. The yields of oil, resin, asphaltene and volatile products in relation to the coal organic matter (COM) are 23.2, 16.1, 5.1 and 14.1%, respectively. CO₂, CO, H₂S and C₁–C₄ alkanes prevail in the composition of volatile products. The generation of oil, resin and asphaltene are found to have occurred in terms of the simultaneous chemical reactions of cleavage of the COM aliphatic CC bonds, while the volatile products result from the consecutive transformations of the COM components in the bulk and SCW solution. Participation of H₂O molecules in thermochemical transformations of COM leads to increase in the oxygen amount in the conversion products and residue by 13.2%. Hydrogen and heat evolution during zinc oxidation by SCW provides for the hydrogenation of COM in situ. Addition of zinc to coal results in increase in the volatile products yield up to 48.6% and decrease in the conversion residue yield up to 20.8%. Under these conditions the yield of resin does not change, while the yields of oil and asphaltene decrease up to 21.2 and 2.5%, respectively. Based on the sulfur balance it is revealed that ≈40% of sulfur atoms pass into ZnS owing to the reactions of H₂S with Zn and ZnO resulting in the removal of H₂S from the volatile conversion products.     

Characterization of coal—oil mixtures by a pseudo diffusivity parameter

For the use of coal—oil mixtures as combustion fuels stable maintenance of the solid—liquid suspension is vital and for this reason the settling properties of these mixtures were studied with a system of ultrasonic sensors. The sedimentation theory of Smiles, which relies on unsteady state diffusion analogies, was applied successfully to the coal-oil mixtures and pseudo diffusion coefficients were determined.     

脱酚混合油作为废水脱酚萃取剂的研究

进行了从低温煤焦油的脱酚混合油中蒸馏切取不同馏分作为废水脱酚萃取剂的试验,结果表明,其分配比和萃取率均高于轻苯和洗油,为低温煤焦油的综合利用开发了新途径。     

Grinding of coal-oil slurries with the szego mill

Grinding of coal in fuel oil for coal-oil mixtures (COM) preparation is simpler and may give better slurry properties than dry grinding followed by dispersion in oil. A 42 weight percent slurry of 600–840 μm particles of Pittsburgh coal in #2, #4, and #6 fuel oils has been ground with the novel Szego mill. Particle size distributions at different residence times are reported down to a 10 μm median size, together with energy consumption data. Low mill hold-ups and high rotational speeds enhanced the rate of grinding.     

催化裂化（FCC）油浆作煤直接液化溶剂的研究进展

煤制油工艺等煤炭清洁高效转化技术是能源化工领域的研究热点,溶解性好、提供/传递氢能力强且热稳定性高,其溶剂选择、使用是影响煤制油工艺经济运行的关键。本文以煤液化溶剂作用为基础,通过对液化自身产物、废塑料及FCC油浆等煤直接液化溶剂的组成、性质及作用效果的综合评述,指出煤、溶剂、氢气间的混合并非理想混合,与煤H/C适宜、极性相近的溶剂在共处理过程表现出良好的协同作用,液化过程的转化率、轻质产物选择性明显提高。分析表明,协同作用的大小取决于煤、溶剂的组成、性质匹配。煤-重质烃共处理工艺利用富芳烃油浆溶解性好、提供/传递氢能力强的特点强化了煤热解加氢反应的进行,同时煤加氢液化产生的多孔残煤具有吸附性强的特点,有助于重质烃改质,使共处理转化率显著提高、轻质产物选择性增大。最后指出,煤-重质烃共处理的协同作用为改善煤、中质/重质芳烃的综合利用提供了可能。     

Single droplet combustion of coal-oil/methanol/water mixtures

Single droplet combustion of coal-oil/methanol/water mixtures was investigated. A microexplosion occured during the gas-phase combustion period of emulsified fuels and caused secondary atomization of fuel droplets. The microexplosion during the combustion of a coal-oil/methanol/water mixture was the most violent of all the sample fuels and its apparent overall burning rate coefficient was maintained at the highest value over the range of ambient air temperatures used, 850–1000 °C. It was concluded that an appropriate addition of water and/or methanol could improve the combustion characteristics of coal/oil mixtures. The apparent overall burning rate coefficient of a methanol/coal/oil mixture was 2–3 times higher than that of a coal/oil mixture. However, that of a water/coal/oil mixture was 2–10 times higher than that of a coal/oil mixture.