Tube Bomb Research Articles

Cu3Si formed by vacuum evaporation deposition enhances hydrogenation of silicon tetrachloride

The efficient conversion of SiCl4 to SiHCl3 still presents considerable challenges for the Siemens process. The enhancement of solid-solid interaction between catalyst and silicon particles in hydrogenation of SiCl4 is viewed as a top priority. In this study, CuCl catalyst and silicon particles mixture heated at the vacuumized tube bomb reactor is found to be an effective pretreatment strategy for obtaining excellent catalytic performance as much as 21.2% under the optimum conditions. The vacuum evaporation deposition is favorable for the deposition uniformly of gaseous CuCl on the surfaces of silicon particles and the formation of Cu3Si. The moderate temperature and time of the vacuum evaporation deposition pretreatment will promote the growth of copper compounds and shorten the induction period of SiCl4 hydrogenation reaction. When CuCl and free copper of the pretreated sample are dissolved by NH4OH, the SiCl4 conversion still maintains 19.8%. Cu3Si is employed as the active phase expresses good catalytic performance where the conversion of SiCl4 is positively correlated with the content of Cu3Si.

Shaped-Cumulative Charge as a Pyrotechnic Mean for a Pipe Bomb Deactivation

The aim of solved problem is a development of a new invasive means for improvised explosive devices deactivation. The idea is a quick and reliable disposal of improvised explosive device with construction system as a tube bombe. Such tube bomb has to be deactivated, dismantled and to do not explode. The development of shaped – cumulative charge was conceptually solved in a way to pushed down metal end caps of the tube bomb, to pick up explosive with a detonating fuse and to prevent from its explosion. Dismantled parts put to forensic test, for the improvised explosive device constructer revelation.

The Influence of Alkyl Group on Needle Coke Formation

Co-carbonization properties of toluene soluble (TS) of coal tar pitch and waste polystyrene (WPS) were studied in a tube bomb to correlate the content of alkyl groups in the mesophase pitches with coefficient of thermal expansion (CTE) and anisotropic orientation. The alkyl contents, which were increased from 12.0% to 33.3% by adding WPS into TS, improved the properties of resultant needle coke in terms of optical texture and CTE value. The anisotropic indices of average length of vectors parallel to the CTE axis and average length of anisotropic unit vectors increased from 20.8 μm to 28.4 μm and 23.4 μm to 28.8 μm, respectively, and CTE value decreased from 0.8×10-6 /°C to 0.1×10-6 /°C. Due to the increasing alkyl groups, the lower viscosity of the carbonization system favored the development of flow texture and uniaxial orientation. And the sufficient gas evolution of good timing in co-carbonization forced the uniaxial arrangement of bulk mesophase molecules at the solidification stage.

물-페놀 혼합 용매의 근임계 하에서의 크래프트 리그닌의 저분자화

식물계 바이오매스는 석유로부터 얻어지는 화학물질들을 대체할 수 있는 물질로 제안되고 있다. 특히 식물계 바이오매스의 15-30%를 이루고 있는 리그닌은 복잡한 방향족 중합체로 이루어져 있어, 리그닌의 저분자화 공정에 의해 다양한 방향족 화합물을 얻을 수 있다. 본 연구에서는 국내에서 가장 많이 배출되는 크래프트 리그닌을 출발 물질로 선정하고, <TEX>$^{13}C$</TEX>-Muclear Magnetic Resonance(<TEX>$^{13}C$</TEX>-NMR), Fourier Transform Infrared Spectroscopy (FT-IR), Elemental Analysis(EA)을 통해 원료물질의 화학적 구조를 분석하였다. 크래프트 리그닌의 저분자화 는 물-페놀 혼합 용매의 근임계 영역에서 수행되었으며, tube bomb reactor를 사용하였다. 최적의 반응조건을 찾기 위해 물-페놀의 비율, 반응온도(<TEX>$300-400^{\circ}C$</TEX>)를 변화시키며 실험을 수행하였다. 또한 기체상 수소를 대신하여 수소발생 용매인 formic acid 사용에 따른 영향을 조사하였다. 액상 생성물의 화학 종류 및 양은 GC-MS를 통해 분석하였고, 고체 잔류물(char)은 FT-IR을 통해 분석하였다. GC-MS 분석 결과 페놀이 첨가된 경우 anisole, o-cresol(2-methylphenol), p-cresol(4-methylphenol), 2-ethylphenol, 4-ethylphenol, dibenzofuran, 3-methyl cabazole, xanthene이 생성되는 것을 확인하였다. Plant biomass has been proposed as an alternative source of petroleum-based chemical compounds. Especially, aromatic chemical compounds can be obtained from lignin by depolymerization processes because the lignin consist of complex aromatic materials. In this study, kraft lignin, the largest emitted substance among several kinds of lignin in Korea, was used as a starting material and was characterized by solid-state <TEX>$^{13}C$</TEX>-Muclear Magnetic Resonance(<TEX>$^{13}C$</TEX>-NMR), Fourier Transform Infrared Spectroscopy(FT-IR), Elemental Analysis(EA). The depolymerization of kraft lignin was studied at water-phenol mixture solvent in near critical region and the experiments were conducted using a batch type reactor. The effects of water-to-phenol ratio and reaction temperature(<TEX>$300-400^{\circ}C$</TEX>) were investigated to determine the optimum operating conditions. Additionally, the effects of formic acid as a hydrogen-donor solvent instead of <TEX>$H_2$</TEX> gas were examined. The chemical species and quantities in the liquid products were analyzed using gas chromatography-mass spectroscopy(GC-MS), and solid residues(char) were analyzed using FT-IR. GC-MS analysis confirmed that the aromatic chemicals such as anisole, o-cresol(2-methylphenol), p-cresol(4-methylphenol), 2-ethylphenol, 4-ethylphenol, dibenzofuran, 3-methyl cabazole and xanthene were produced when phenol was added in the water as a co-solvent.

Hydrogen production from the gasification of lignin with nickel catalysts in supercritical water

Hydrogen production from the gasification of lignin with Ni/MgO catalysts in supercritical water was conducted using stainless steel tube bomb reactor. Ni/MgO catalysts were prepared by impregnation method and were calcined at 773–1173 K in air for 8 h. The results of characterization for reduced Ni/MgO catalysts showed that Ni metal and NiO–MgO phase are formed after the reduction of calcined catalyst by H 2 . Furthermore, Ni metal surface area, which was calculated by CO chemical adsorption technique, decreased with increase in calcination temperatures. It was found that the carbon yield of gas products was increased with increase in Ni metal surface area except 10 wt% Ni/MgO (773 K) catalyst. Thus, it can be supposed that there is an optimal Ni particle size for the gasification of lignin in supercritical water. It should be noted that 10 wt% Ni/MgO (873 K) catalyst showed the best catalytic performance (carbon yield 30%) under reaction condition tested. It was concluded that Ni/MgO catalyst is a promising system for the gasification of lignin in supercritical water.

Catalytic Hydrodesulfurization of Dibenzothiophene through Partial Oxidation and a Water−Gas Shift Reaction in Supercritical Water

We conducted a comparative study of catalytic hydrodesulfurization of dibenzothiophene (DBT) with NiMo/Al2O3 at 673 K and 30 MPa, in various atmospheres (H2−SCW, CO−SCW, CO2−H2−SCW, and HCOOH−SCW), using a tube bomb reactor. Higher conversion of DBT was obtained in CO−SCW, CO2−H2−SCW, and HCOOH−SCW than in H2−SCW. These results clearly indicate that a water−gas shift reaction in supercritical water (SCW) produces species which can hydrogenate DBT more effectively than H2 gas. We also conducted another experiment for the partial oxidation of a DBT−hexylbenzene mixture in SCW. Even in the presence of oxygen, effective hydrogenation of DBT took place. This result is probably because CO forms through the partial oxidation of hexylbenzene and converts to the hydrogenating species through a water−gas shift reaction. We think the catalytic desulfurization of heavy oils in SCW will be a promising new technology, since even by introducing oxygen or air instead of hydrogen, an excellent hydrogenating atmosphere can...

Carbonization of coal-tar pitch under controlled atmosphere—Part II: Effect of temperature and pressure on the electrical property evolution of the formed green coke

The carbonization of an industrial coal-tar pitch was studied by using a tube bomb, as a function of carbonization temperature (550 °C–580 °C) and inert gas pressure (1–20 bar), and resultant green cokes were evaluated according to electrical resistivity determined using the Van der Pauw method. At 550 °C, the carbonization pressure increase leads to an uniaxial arrangement of the produced green coke sample and to a progressive increase of the resistivity component perpendicular to the tube bomb axis. At 580 °C, these changes appear only above 15 bar. These results are in good agreement with those obtained in the first part of this work, confirming the intimate correlation between carbonization temperature and pressure and the necessity of a compromise between them, to produce green cokes with oriented uniaxial texture.

Carbonization of coal-tar pitch under controlled atmosphere—Part I: Effect of temperature and pressure on the structural evolution of the formed green coke

The carbonization of an industrial coal-tar pitch was studied, by using a tube bomb, as a function of carbonization temperature (520 °C–580 °C) and inert gas pressure (1–20 bar) and resultant green cokes were evaluated according to yield and observation under polarized light microscopy. At 520 °C, green cokes present large isotropic domains as well as Brooks and Taylor's spheres whatever the pressure applied, indicating that the pyrolysis duration seems to be too short to obtain an entirely anisotropic texture. When carbonization temperature increases, samples present an entirely anisotropic texture. An increase of carbonization pressure from 5 to 10 bar leads to a sharp increase of the coke yield and of the uniaxial arrangement, this latter being progressive with increasing pressure at 550 °C and appearing only at pressures greater than 15 bar at 580 °C. Carbonization temperature and pressure are intimately correlated. The temperature increase involves a higher solidification rate, whereas the pressure increase delays the volatile departure and consequently the solidification rate. It is necessary to obtain a compromise between them so as to produce green cokes with oriented uniaxial texture.

Study on Mechanism of Formation and Quality Improvement of Petroleum-based Needle Coke.

Needle coke which has been the best filler of graphite electrodes need to be upgraded because the quality of graphite electrodes for electric arc furnace is improved with progress of steel making technique.The role of respective feedstock based on mechanism of formation of needle coke is overviewed in terms of pretreatment of the feedstocks, such as modification of FCC decant oil (FCCDO), solvent deasphaltene process, and heat treatment of low sulfur vacuum residue (LSVR), to improve the characteristics of the needle coke.The mechanism of formation of needle coke is traced through the observation of the carbonization process using tube bomb which can provide nearly the same condition as delayed coker. Coefficient of thermal expansion (CTE), which is the most important property of needle coke, is strongly influenced by uni-axial orientation of flow texture in the coke. Gas evolution of solidification, therefore, is important for production of low CTE coke as well as formation of bulk mesophase. The carbonization condition, especially pressure and temperature, influences the above important factor. Furthermore, the cocarbonization of LSVR with FCCDO produced excellent needle coke of low CTE because formation of bulk mesophase and gas evolution at solidification were improved. As the amount of mosaic coke of high CTE affects the CTE of needle coke, in the present study, the modification of FCCDO and LSVR was studied to eliminate the formation of mosaic coke.Addition of high aromatic pitch, dewaxing and heat treatment were highly effective for elimination of mosaic coke by modification of FCCDO. On the other hand, elimination of asphaltene by solvent extraction and heat treatment with hydrogen donor were highly effective as modification of LSVR.

Effects of pressurized pretreatment on the preparation of mesophase pitch

Spinnable mesophase pitch as a precursor of high-performance carbon fiber was prepared from coal-tar pitch by using two-stage heat treatment, which consisted of pretreatment under pressure as a first stage and successive heat treatment under normal pressure as a second stage. Employing two different types of pressure reactor, a tube bomb and a laboratory autoclave, the effect of the pressurizing system was compared. The pretreatment under pressure of raw pitch was very effective in increasing the yield of mesophase pitch and developing its texture. The structural modification of the pitch induced by the pretreatment is discussed in terms of the chemical reactions of the pitch components.

Properties of fluid catalytic cracking decant oils of different origins in their single carbonization and cocarbonization with a petroleum vacuum residue

Eight decant oils of fluid catalytic cracking (FCC-DO) were compared in terms of their structure and carbonization properties in their single carbonization and cocarbonization with a low sulfur vacuum residue (LSVR) to reveal structure-reactivity correlation in the needle coke production. Although eight oils all provided (at 500{degrees} C under 16 kg/cm{sup 2} of pressure) lumps of needle cokes in a tube bomb, their coefficients of thermal expansion (CTE) ranged from {minus}0.15 {times} 10{sup {minus}6} (shrink, oil E) to 0.6 {times} 10{sup {minus}6}{degrees} C{sup {minus}1} (oil A). Their cocarbonization with LSVR at 480 {degrees} C under 8 kg/cm{sup 2} provided lump cokes of variable quality in terms of CTE and amount of bottom mosaic cokes. It should be noted that the best FCC-DO in its single carbonization was not always a better partner in the cocarbonization. In the cocarbonization, the best FCC-DO (G) gave a needle coke with the low CTE of 0.6 {times} 10{sup {minus}6}{degrees} C{sup {minus}1} and no bottom mosaic cokes while the worst oil (A2) gave a CTE of 1.2 {times} 10{sup {minus}6}{degrees} C{sup {minus}1} and bottom mosaic coke 1.4 mm thick. The oils consisted principally of saturate and light and heavy aromatic fractions, the contents of whichmore » varied from one oil to another. The roles of FCC-DO in the cocarbonization particularly in the formation of bottom mosaic texture, are discussed.« less

Co-carbonization of ethylene tar pitch and coal tar pitch to form needle coke

The co-carbonization of ethylene tar pitch (ETP) and coal tar pitch (CTP) was studied in a tube bomb. A small amount of CTP was found to effectively modify the carbonization properties of ETP to produce excellent needle coke of low nitrogen content without formation of mosaic coke at the reactor bottom (bottom mosaic coke) in a wide range of carbonization temperatures and pressures. Blending 30–50 wt% CTP into ETP provided lump coke of thin lamellar flow texture, with a good CTE value and nitrogen content after calcination at 1000 °C. The influences of carbonization temperature and pressure on the nitrogen remaining in the coke were also investigated.

A study of the carbonization of ethylene tar pitch and needle coke formation

Carbonization of ethylene tar pitch (ETP) and its hydrogenated products was studied in a tube bomb to find the appropriate carbonization conditions for producing a good needle coke. At the relatively low temperature of 460 °C under a pressure of 784 kPa for 10 h, ETP produced lump coke of low CTE and of excellent flow texture without any mosaic coke being formed at the bottom of the reactor (bottom mosaic coke). A higher carbonization temperature (480 °C) gave a mosaic texture coke of large CTE, although the carbonization was complete in 6 h. A lower carbonization temperature (440 °C) or pressures above 784 kPa resulted in bottom mosaic coke. The catalytic hydrogenation of ETP improved the anisotropic texture of coke carbonization at 480 °C, but could not eliminate the mosaic coke forming at the reactor bottom. N.m.r. and g.p.c. analysis revealed that ETP contained some olefins and high molecular weight substances in the major 2–3 ring aromatic hydrocarbons. The roles of such minor components in the formation of needle and mosaic cokes are discussed.

Cocarbonization properties of dewaxed FCC decant oils with low sulfur vacuum residue leading to production of needle coke.

Cocarbonization properties of a particular FCC decant oil (FCC-DO) of paraffinic nature with low sulfur vacuum residue (LSVR) were studied in an attempt to find guiding principles of its thermal modification for production of better quality needle coke, using a tube bomb, as these oils do not always make excellent coke of homogeneous quality because of difference existing in the oils properties. FCC-DO was heattreated under some conditions of temperature and residence time before cocarbonization with LSVR, to eliminate the unfavorable bottom mosaic coke. The heattreatment of FCC-DO removed paraffins and alkyl groups of longer chains on aromatic ring, which increased the aromaticity. Highly aromatized FCC-DOs increased solvency, at early stage cocarbonization, dissolving viscous mesophase derived from the most reactive portion in LSVR which is believed to cause bottom mosaic structure. The coefficient of thermal expansion (CTE) of the coke was maintained at optimum range for graphite electrodes by selecting adequate carbonization conditions for the particular feed.

Carbonization in the tube bomb leading to needle coke: III. Carbonization properties of several coal-tar pitches

Carbonization properties of several coal-tar pitches of different origins were studied, by using tube bomb, to correlate their analytical characteristics with their carbonization properties and to find their respective optimum carbonization conditions for the production of excellent needle coke. The pitch rich in naphthenic structure produced an excellent needle coke of low CTE and uni-axially arranged flow texture under a wider range of carbonization conditions, whereas the pitches of high oxygen and alkyl contents or of very high aromaticity gave cokes of larger CTE under the standard carbonization conditions of 500 °C, 8 kg/cm 2, because of more mosaic texture or poor uni-axial orientation in the resultant cokes. However, the two kinds of poor pitches were found to produce better cokes under their respective appropriate conditions. The former one did at a slightly lower carbonization temperature of 480 °C and the latter one did under a lower carbonization pressure of 4 kg/cm 2. A lower temperature allowed the development of bulk mesophase through the moderation of carbonization reactions for the former reactive pitch. The lower pressure improved uni-axial arrangement of mesophase molecules at the solidification stage through the sufficient gas evolution of good timing for the latter highly aromatic pitch. The higher pressure of carbonization delayed the solidification to be off-timing to the gas evolution. The mechanism of needle coke formation was discussed to explain the respective optimum conditions for the pitches of different analytical characteristics.

Carbonization in the tube bomb leading to needle coke: I. Cocarbonization of a petroleum vacuum residue and a FCC-decant oil into better needle coke

The cocarbonization of a Fluidized Catalytic Cracking decant oil (FCCDO) with a petroleum low sulfur vacuum residue (LSVR) was studied at a temperature range of 460 to 480°C by evaluating the qualities of coke lumps produced in a tube bomb in terms of their CTE and anisotropic development. The cocarbonization certainly improved the orientation of flow texture and CTE of the resultant coke, providing the smallest CTE as low as 0.10 × 10 −6/° C and 0.36 × 10 −6/° C at particular FCCDO/LSVR mixing ratios of 5 5 and 7 3 according to the respective carbonization temperatures of 460 and 480°C. The natures of bulk mesophase and gas evolution at the solidification stage for the axial-rearrangement of mesophase aromatic component, both of which essentially define the coke quality, are strongly influenced by the carbonization reactivities of blended feedstocks and carbonization conditions. FCCDO may moderate the carbonization progress of reactive LSVR and LSVR supply the sufficient gas evolution during the solidification, leading to excellent flow texture of axial arrangement. The formation of mosaic coke in the bottom part of the lump which may deteriolate the quality of the coke produced in a commercial coker appeared to be caused by the phase separation between the paraffin and asphaltene fractions. Such a separation at a early stage of the carbonization was found to be controlled by the blending and the carbonization conditions.

Carbonization in the tube bomb leading to needle coke: II. Mechanism of cocarbonization of a petroleum vacuum residue and a FCC-decant oil

Cocarbonization of a FCC decant oil (FCCDO) and a vacuum residue of low sulfur crude (LSVR) was studied at 460 and 480°C through the sequential microscopic observation and analyses of the carbonization intermediates produced in a tube bomb to discuss how the best needle coke was produced from their mixture of a particular ratio subjective to the carbonization temperature. The cocarbonization moderates the reactivity of LSVR to allow the formation of the mesophase of low viscosity comparable to that from FCCDO alone as indicated by the solubility change and allows at same time more evolution of gas at the solidification stage which may originate from LSVR. Thus, the better uni-axial arrangement of mesophase components is achieved in the cocarbonization, leading to the production of better needle coke. Such a cocarbonization is strongly influenced by the carbonization temperature, defining the best ratio of the mixing at the respective temperature because of the reactivity subjective to the temperature. The formation mechanism of the bottom mosaic coke is also discussed from a view of solubility of the reactive portion of the asphaltene in the cocarbonization matrix.

Study of carbonization using a tube bomb: evaluation of lump needle coke, carbonization mechanism and optimization

The carbonization of three representative feedstocks derived from petroleum and coal tar was studied using a tube bomb, where the carbonization temperature and pressure are freely set up and carbonization progress is pursued at the desired stages. The coke lumps produced in the bomb are evaluated by optical anisotropy defined through a montage technique and coefficient of thermal expansion, which are semi-quantitatively correlated. The carbonization into needle coke follows the three major stages: the formation and growth of liquid crystal spheres; their coalescence into bulk mesophase; and the uni-axial rearrangement of mesophase molecules into a solid coke. The nature of bulk mesophase and gas evolution for the rearrangement define the quality of the needle coke. These factors are sharply influenced by the reactivity of feedstocks, carbonization temperature and pressure. Chemical analyses of the feedstocks and the carbonization intermediates describe the chemistry of the carbonization reaction, providing a structural basis for the reactivity. Based on such a mechanistic understanding of the carbonization, guiding principles to optimize the carbonization conditions of respective feedstocks into their best needle coke are proposed according to their structure and reactivity.

Improvements to needle-coke quality by pressure reductions from a tube reactor

Needle coke of excellent uniaxial orientation and thermal expansion of 0.6 × 10 −6/° C was produced at 460°C in a tube bomb from a low sulfur petroleum vacuum residue by reducing the carbonization pressure from 15 to 7 kg/cm 2G at the solidification stage. Both timing and rate of pressure reduction are critical to the uniaxial arrangement of mesophase molecules that governs the coke quality. Reduction of pressure before the formation of bulk mesophase or after the solidification did not induce an improvement. Excess gas evolution by the larger rate of pressure reduction creates excessive porosity, although the uniaxial arrangement may be improved. A too-small rate is not effective in modifying the lamellar arrangements at the solidification stage.

Optimization of carbonization conditions for needle coke production from a low-sulphur petroleum vacuum residue

The optimum carbonization conditions for converting a low-sulphur petroleum vacuum residue in a tube bomb in terms of pressure and temperature into better needle coke of low CTE, with less production of poor bottom coke, were studied by observation of the resultant cokes and sequential analyses of carbonization intermediates by means of solvent fractionation and gas evolution. Carbonization at 460°C under 15 kg cm−2 G produced the best needle coke. The quality of the resultant needle coke was strongly influenced by viscosity changes of the system, the solidification range and gas evolution in the carbonization progress. The first two characteristics reflect the rates of condensation (such as QI formation) and devolatilization of soluble fractions, strongly influencing the growth of anisotropic units. The last characteristic reflects the pyrolytic cracking reaction to define the timing of gas evolution during carbonization, influencing the axial orientation of anisotropic texture as well as the porosity in the resultant coke. Both profiles varied very much, depending on the carbonization temperature. Finally, the formation of a bottom coke of fine mosaic texture is discussed from the viewpoint of the co-carbonization concept.