EFFECTS OF HEATING RATE AND PARTICLE SIZE ON THE PRODUCTS YIELDS FROM RAPID PYROLYSIS OF BEECH-WOOD

ABSTRACT

Effects of pyrolysis temperature (300–1000 ^°C), heating rates (100, 500, 1000, and 10,000 ^°C/s), and particle sizes (53–63,104–120,177–270, and 270–500 urn) on the yields and formation rates of tar, light oils, total gases, and char from pyrolysis of beech-wood under 1 atm helium pressure were studied. Wood particles were pyrolyzed in strips of stainless steel wire mesh in a captive sample apparatus; and yields of products were measured in weight percent of original wood as a function of temperature for different heating rates and particle sizes. The overall weight loss achieved from pyrolysis of this wood was about 90%. The total yields of tar and light oils from pyrolysis of this wood accounted for up to 80% of the original wood above 400 ^°C. Due to the post-pyrolysis reactions of tar and light oils, the tar and light oils yields go through a maximum with pyrolysis temperature for all particle sizes and most heating rates studied here. As particle size increases from 53–63 μm to 270–500 μm the maximum tar yield decreases from 53% to about 38%. The maximum tar yield also decreases with increasing the heating rate from 70% at 100 ^°C/s to 48% at 10,000 ^°C/s heating rate. Theses results indicate that as the intra-panicle post-pyrolysis cracking reactions of tar increases at higher heating rates and with larger particles the tar yield decreases. Tar was also analyzed with GPC for the effects of above pyrolysis parameters on the tar molecular weight. The tar average molecular weight. remains relatively constant (M_w = 300 amu, M_n = 155 amu, and M_z = 483 amu) under helium atmosphere with pyrolysis temperature at 1000 ^°C/s heating rate and with 53/63 u m particle size. The average molecular weight of tar does not significantly varies with heaung rate, but it decreases as the particle size increases.     

THERMAL DECOMPOSITION OF SAUDI CRUDE OIL ASPHALTENES

Asphaltenes precipitated by the use of pentane, heptane and decane solvents from Saudi Arabian Light (AL) and Saudi Arabian Heavy (AH) crude oils 370^°C + residua have been investigated by thermal gravimetric analysis and pyrolysis - gas chromatographic analysis at 350^°C and 520^°C. Gas chromatographic analysis of the gases evolved during pyrolysis has shown that CO, CO₂ and CH₄ constitute the major portion of the gases evolved at 350^°C from pentane and heptane asphaltenes of AH residue and from pentane asphaltenes of AL residue. Whereas gases evolved from decane asphaltenes are dominated by CO₂ and C₂-C₄ hydrocarbon gases. At 520^°C, hydrogen and methane represent 56-80 vol %of the gases evolved from all the four asphaltenes. The amounts of C₁-C₄ hydrocarbon gases increased with an increase in the carbon number of the precipitating solvent at 350^°C and decreased at 520^°C. The presence of up to C₃₆ normal alkane hydrocarbon has been indicated in the maltenes produced from these asphaltenes. The loss of nitrogen from AH asphaltenes during pyrolysis remained low (1-6 wt %), whereas the losses of oxygen and sulphur ranged from 58 to 74 wt % and 10 to 29 wt %, respectively.     

CHARACTERIZATION OF COAL CHARS FROM A FLASH PYROLYSIS PROCESS BY CROSS POLARIZATION/MAGIC ANGLE SPINNING 13C NMR

Chars from the Illinois Springfield (No. 5) Coal are prepared by flash pyrolysis at progressively higher charring temperatures. The results of a study of these chars by ¹³C NMR with CP/MAS indicate that the initial stage of heating (300^°C) produces a char with aromatic carbon fraction (f_ar) of 68%, and successive heating gives chars with f_ar of 70% (400^°C), 73% (500^°C), 89% (600^°C), 95% (700^°C), and 96% (800^°C). However, the actual amount of aromatic and aliphatic carbon in the char can be calculated by using the NMR measurements, the organic carbon content of the char, and the weight of the char. The calculated values show that the amount of aromatic carbon in char remains relatively constant at each temperature, but the amount of aliphatic carbon in char is reduced during higher temperature charring. At 600^°C, both a large reduction of the aliphatic carbon content and a maximum weight loss occur. Evidently, the aliphatic-bond carbon in coal is the principal source of volatiles derived from coal. The apparent increase in aromaticity (f_ar) of the char heated to progressively higher temperatures is due to the loss of aliphatic-bond moieties and reduction in volume of materials.     

THE INCREASE OF EFFICIENCY OP PINE OIL BY HEATING AND USAGE IN THE FLOTATION OF OXIDIZED AHASRA COAL

The effect of heating temperature and time on the efficiency of pine oil was examined in the flotation of oxidized Amasra Coal in this work. Samples were taken from waste heap Amasra Coal which were collected in 1973-1978 and stored in atmospheric conditions. The optimized impeller speed was 1000 rpm, aeration rate was 35 ml/s and solid content of the pulp was 20% in the flotation tests. Motorin was added to the pulp as a collector. The pine oil was heated to 50^°C, 75^°C, 106^°C, 125^°C, 150^°C, 175^°C, 200^°C and used as a frother. The flotation resulta indicated that 125^°C was suitable temperature for heating. Increasing the heating time increased the efficiency of pine oil. The recovery of combustibles also Increased depending on the increase in the amount of oil heated for 5 hours at 125^°C.     

PRODUCTION OF OXYGENATED FUELS FROM BIOMASS: IMPACT OF FEEDSTOCK STORAGE

Biomass pyrolysis oils were produced from stored biomass feedstocks by rapid pyrolysis in a fluidized bed reactor. The feedstocks used for these studies were switchgrass, com stover, and hybrid poplar. The woody and herbaceous feedstocks were stored in chip piles and bales, respectively, unprotected in an open field for 6 months. At the end of the storage period, biomass samples were taken from the interior of bales and the centers of chip piles for pyrolysis studies. The materials were ground to pass -20/+80 mesh and dried to less than 10% moisture content before pyrolyzing in the fluidized bed reactor. Pyrolysis was conducted at 500^°C and with less than 0·4 s. vapor residence time. Total liquid yields were as high as 66% for the hybrid poplar and as low as 58% for the com stover. Moisture content of the oils was between 10% and 13%. Gas and char/ash yields were 10-15% and 12-22%, respectively. The char/ash yields were feedstock dependent, but storage influence was significant for only the com stover feedstock. Gas and liquid yields were not influenced by storage time. The oils were highly oxygenated and had higher heating values (HHV) of 23-24 MJlkg that decreased slightly with storage time for all the feedstocks except the switchgrass. The oils, as currently produced, are high in ash and alkali metals. Ultimately, they will be upgraded and used as boiler and turbine fuels.     

HYDROLIQUEFACTION OF TEXAS LIGNITE IN COAL- AND PETROLEUM-DERIVED SLURRY OILS

Hydroliquefaction of Texas lignite (68.5%. C daf) was conducted in a batch autoclave under hydrogen in a coal-derived slurry oil at 90 bar initial pressure for temperatures of 380-460^° C and residence time of 15-60 minutes, or a vacuum distillate from petroleum at 435^° C for 60 minutes and initial H₂-pressure of 60-150 bar, or a vacuum residue from the same petroleum at 435 and 460^° C for 60 minutes and initial H₂-pressure of 90-150 bar or tetralin at 435^°C, 60 minutes and 90 bar initial H₂-pressure. Red mud plus sodium sulfide were added as a catalyst for all experiments. Lignite conversion ranged from 50 to 83%. The products were separated into gases, residue, asphaltenes, oils B,P. above 200^° C, oils B.P. below 200^° C. Total liquid products from coal reached 57% in coal-derived slurry-oil, 56% in vacuum distillate and 64% in vacuum residue at optimum conditions with 32% of product oil B.P. below 200^° C in vacuum distillate and 24% in vacuum residue. When coprocessing lignite with vacuum residue at 120 bar initial pressure, 435^°C and 60 minutes residence time the total mass balance presented an oil yield of 73%. with 32% boiling below 200^°C.     

RECOVERY OF ORGANIC MATTER FROM GREEN RIVER OIL SHALE AT TEMPERATURES OF 400°C AND BELOW

Experiments to recover organic matter from Green River oil shale in high yields at temperatures of 400^°C and below are described. Three different recovery procedures are discussed: 1) experiments wherein liquid organic materials were extracted at atmospheric pressure and temperatures below 75^°C by solvents of different strengths, 2) autoclave experiments where liquid organics were recovered by heating the shale with a variety of solvents at temperatures between 300 and 400^°C and pressures between 5 and 32 MPa, and 3) an autoclave experiment where liquid organics were recovered by heating shale in an argon atmosphere for 1 hour at 400^°C. The liquid organic materials recovered in these experiments represent from four to 90 weight percent of the total organic material in the shale. The liquid organic materials have an average molecular weight of between 500 and 600 amu as compared to a typical shale oil that has an average molecular weight of 300 to 350 amu. Elemental analyses show that the liquid organic materials contain high percentages of hydrogen and nitrogen, as does shale oil. Moreover, the liquid organic materials also contain much larger concentrations of oxygen-containing compounds than shale oil. The experimental results suggest the possibility of developing a new process for recovering both organic and inorganic material from Green River shale.     

CHARACTERIZATION of ARAB MEDIUM CRUDE FRACTIONS WITH EMPHASIS ON KINEMATIC VISCOSITY - TEMPERATURE BEHAVIOR

Characterization of Arab medium Crude Oil, has been carried out in terms of API gravity, debutanized crude gravity, total sulfur content, Reid vapour pressure ash content, heating value, salt content, viscosity SUS, vanadium content as V₂O₅, pour point and analysis of various metals. Further, six true boiling point (TBP) fractions (IBP-95^°C, 95-205^°C, 205-260^°C, 260-345^°C, 345-455^°C and 455^°C+) of this crude were characterized in terms of API gravity, total sulfur contents H2S content, mercaptons content, molecular weight, elemental analyse; for total carbon, hydrogen and nitrogen, analyses of various metals and paraffin, aromatic and naphthene contents of lighter fractions. The kinematic viscosity-temperature data have been obtained for 95^°C+ TBP fractions for a wide range of temperatures.     

RAPID PYROLYSIS OF EASTERN CANADIAN COALS BY FREE FALL REACTORS

The effect of temperature was investigated on the rapid pyrolysis of Prince, Lingan and No. 26 coals in the temperature range of 525^° to 750^°C using a 600 cm high stainless-steel free fall reactor at atmospheric pressure.

The yields of char, condensibles and gaseous products were determined at 25^°C intervals. Gaseous products were analysed for H₂, CO, CO₂, CH₄ and C₂+.

Volatile product (condensible and gas) yields exceeded the volatile product in the A.S.T.M. methods at and above 700^°C.

Some experiments using Prince coal were repeated at reduced pressure (50 mm mercury) in both the 600 cm height stainless-steel and a 140 cm height quartz reactor in order to find out the effect of pressure and retention time.

The experimental results indicated that the condensable yield was higher at the lower pressure and at the shorter retention time. The effect of retention time was far more pronounced.     

CHARACTERIZATION OF KUWAITI CRUDE TBF-FRACTIONS WITH EMPHASIS ON KINEMATIC VISCOSITY - TEMPERATURE BEHAVIOR

Characterization of Kuwaiti crude oil, has been carried out in terms o API gravity, debutanized gravity, total sulfur content, Reid Vapor pressure ash content, heating value, salt content, viscosity SUS, vanadium content a: V2 O5, pour point and analysis of various metals. The true boiling poinl (TBP) fractions of this crude (IBP - 95^° C, 95 - 205^°C, 205 - 260^° C, 260 - 345^° C and 455^° C⁺;) were also characterized in terms of API gravity, total sulfui content, H₂S content, mercaptans content, molecular weight and elementa analyses for total carbon, hydrogen and nitrogen. The kinematic viscosity temperature data have been obtained for 95^°C⁺; TBP fractions for a wide range of temperatures.     

LIGNITE RETORTING USING SOLID HEAT CARRIER

A retorting pilot plant with capacity of 10 kg/h using hot char as solid heat carrier was constructed. This paper describes experimental results using four different lignites. The product char was used as solid heat carrier and the retorting temperature range was 450^°C-670^°C. The maximum yield of tar was up to 92% of the value of Fischer Assay. Produced gas and tar can be used as chemical feedstock and they are clean energy.     

PYROLYSIS STUDIES OF ORGANIC OXYGENATES. IV. NAPHTHALENE METHYL ETHER PYROLYSIS UNDER BATCH AUTOCLAVE CONDITIONS

Aryl alkyl ethers undergo two major kinds of thermal reactions at temperatures of about 450^°C. They cleave homolytically at the C-H alkyl bond to produce phenols and they cleave homolytically at the C-H alkyl bond, and rearrange to an aryloxy radical leading to carbonyl compounds and ultimately to other products. Results obtained with the methyl ethers of 1- and 2-naphthol and with anisole show clearly that relative kinetics for these pathways differ for different substrates. Unimolecular decomposition rates at 400^°C and at 450^°C show that 1-methoxy naphthalene decomposes faster than 2-methoxy naphthalene which in turn is more thermally reactive than anisole.     

KINETICS OF CORN COB CHAR GASIFICATION IN CARBON DIOXIDE

The Reactivity of corn cob char in CO₂ has been studied on a thermogravimetric balance to develop a rate equation for the design of biomass gasifiers operating on corn cob char. Experiments in the range of 650-1000^°C were conducted with cylindrical shaped pellets of 1 cm diameter having L/D=l. The average porosity of the pellets was 0.5. It was observed that the rate of the CO₂/char reaction decreased with increase in temperature from 650-750^°C and then increased with temperature upto 1000^°C.

The data obtained at temperatures 750^°C and above has been used to determine a rate equation for char gasification. It has been found that the reaction proceeds according to the Sharp Interface Model (SIM) with a first order chemical reaction as the rate controlling step. The activation energy is found to be 40 Kcal/mole with frequency factor being 1.2 × 10⁷ mm/sec. Analysis of the data obtained for the decreasing reaction rate regime (650-750^°C) indicates that the change in the ash structure result in this kind of behavior.     

COKE CHARACTERISTICS IN RELATION TO THE COLLOIDAL. MATTER OF PETROLEUM FOR THERMAL. PROCESSES

The purpose of this work is to research the characteristics of the production of coke in thermal and hydrothermal cracking from residual oils and their deasphalted oils Using ethyl acetate, because it allows the elimination of both resins and asphaltenes (colloidal matter) from the parent oil in only one step. This improves the deasphalted oil as coke precursors and basic nitrogen compounds present in the resin fraction are practically eliminated.

A 104 ml batch autoclave reactor with a cooling system was used for the thermal and hydrothermal cracking experiments. This reactor can withstand temperatures of up to 500^°C, pressures of 500 bar and a rocking velocity of 1 Hz. The influence of the temperature was investigated at 400, 425 and 450^°C and at 0, 20, 40, 80,     

STUDY ON THE CORROSIVENESS OP WOOD PYROLYSIS OILS

A study has been conducted on the rate of corrosion of wood pyrolysis oils in presence of carbon and stainless steel plates. Tests were performed to similate the conditions existing in storage tanks. The effect of temperature, water content and acetic/formic acid concentration on the rate of corrosion of metals was studied, as well as their possible interaction effects. The method used involved a factorial design of experiments. All primary effects with their interactions were found statistically significant using the Fischer criterion at Fonx for the analysis of variance. Stainless steel resisted corrosion activity under all sets of conditions used. Wood oils were found not corrosive or slightly corrosive for cast iron at ambiant temperature and low water content, whatever the acid concentration used. Increasing the temperature to 45^°C however dramatically increased the oil corrosion activity.     

SOAKER VISBREAK1NG OF SOME IRAQI RESIDUES

An attempt has been made to increase the fuel oil yield of two Iraqi residues using a soaker visbreaking process. This was carried out in a continuous laboratory scale unit at a range of mild conditions, namely, A20-A8O^°C and A3-109 sec. in the coil and 151-379 sec. in the soaker.

Physical properties of the products have been characterized and reported. The fuel oils obtained under the studied conditions remained stable compared with the original feedstocks. Furthermore, data on yield and characteristics of the different distillates from the visbroken products have been obtained. There was an increase in the distillates up to 350^°C (11%) for type A residue and (15%) for type B residue.     

低阶煤流化床热解气化新工艺

针对低阶煤流化床热解气化所遇到的问题,对热解炉供热模式、原料煤粒径与颗粒分级、热解气初级冷却与除尘、排灰方式等问题进行探讨,优化工艺过程。新工艺中选择高温半焦为热解炉提供热量,将原料煤磨制成亚毫米级粉粒,磨煤产生的少量粒径小于0.1 mm的细颗粒被分离出来,送往配套的气流床气化炉,与流化床气化炉气体带出的细粉一起进行熔渣气化,提高碳转化率。大量粒径为0.1~1.0 mm的颗粒进热解炉,热解炉出来的气体经适当馏分煤焦油冷却、捕集颗粒物,使温度降至350 ℃左右,采用间接换热模式进一步降温,由此将有机废水产量降至近零水平,实现清洁高效热解气化。以低阶煤4 600 t/d规模的流化床热解气化新工艺为例,干基煤粗粉进热解炉,干燥单元取水约480 kt/a,热解单元不产生有机废水,可产有效气体（氢气和一氧化碳）约1.09×10⁹ m³/a,产煤焦油约81 kt/a,系统碳转化率大于95%,煤焦油、煤气、半焦的产率分别为8.97%,110 m³/t,67.5%,半焦气化产物气中有效气体积分数大于80%。     

EFFECT OF IRON CATALYST ON THE COMPOSITION OF OIL FROM COAL LIQUEFACTION

The effect of two iron catalysts, red mud and CGS S-G, as well as C0-Mo/AI₂O3 and Ni-Mo/Al₂03 commercial catalysts on the composition of oil derived from the liquefaction of Japanese subbituminous coal have been investigated comparatively by conventional autoclave experiments at 440 and 450^°C under initial hydrogen pressure of 85kg/cm² G with tetralin to coal weight ratio of 3. From the results obtained at 450^°C, total conversion and the yield of gas revealed almost same level with four catalysts, but the oil product from molybdenum catalysts showed higher yield than that from iron catalysts. CGS S-G catalyst also showed higher yield of oil product than red mud catalyst. Reaction behavior of two iron catalysts were also tested by solvent recycle mode experiments.     

FREE RADICALS FORMED IN HYDROTREATED COAL LIQUID AND INFLUENCE OF OXYGEN

The behavior of radicals formed in hydrotreated coal liquid with heat treatment and the influence of oxygen have been investigated by electron spin resonance (e.s.r.) spectroscopy. A set of e.s.r. spectral lines identified as phenalenyl radical appears from 50^°C as the oil is heated in argon atmosphere. The radical concentration is enhanced with temperature, reaches a maximum between 130 and 150^°C and then decreases at higher temperatures. The radical is very stable even at 200^°C for the sample hydrotreated under mild condition, whereas the radical in the sample treated under severe conditions disappears drastically from 150^°C. When oxygen is introduced in the oil, the radical is converted into semiquinone and/or aryloxy radicals and stable molecules. The treatment in the presence of oxygen at higher temperatures is considered to accompany the formation of other aryloxy radicals by the reaction of aromatic hydrocarbons and oxygen.     

ASPHALTENE AND RESID PYROLYSIS: EFFECT OF REACTION ENVIRONMENT

Hondo and Maya vacuum resids and their isolated asphaltenes were pyrolyzed at 400, 425, and 450^°C (752, 797, 842^°F) for batch holding limes ranging from 20 to 180 minutes. Maltene, asphaltene, and coke product fractions were isolated by a solvent extraction sequence; gas yield was determined gravimetrically. Results were summarized in terms of a lumped reaction network. The variation of product yields, kinetics, and apparent activation energies with feedstock and asphaltene environment provided insight into asphaltene structure and thermal reaction pathways.