Table 1 Physical Properties of Petroleum Pitch and Solvent Oil Fig. 1 Process Flow Diagram of the Bench Scale Fluidized Bed Coker Table 2 Physical Pro

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2 Table 1 Physical Properties of Petroleum Pitch and Solvent Oil Fig. 1 Process Flow Diagram of the Bench Scale Fluidized Bed Coker Table 2 Physical Properties of Typical Core Particles for Fluidized Bed Coking Test

3 Fig. 4 Viscosity of Petroleum Pitch (ASP) and Fluid Catalytic Cracker Cycle Stock Solution Measured by Emila Rotating Rheometer Fig. 2 Viscosity of Petroleum Pitch (ASPL-1) and Anthracene Oil Solution Measured by Emila Rotating Rheometer Fig. 3 Viscosity of Petroleum Pitch (ASP-1) and Anthracene Oil Solution Measured by Emila Rotating Rheometer

4 Table 4 Thermal Cracking Yield on Solvent Oil in the Bench Scale Fluidized Bed

5 Table 5 Thermal Cracking Yield on Petroleum Pitch in the Bench Scale Fluidized Bed Fig. 5 Liquid Level Change of Pitch Tank Charged with Petroleum Pitch (ASPL) Fig. 6 Liquid Level Change of Pitch Tank Charged with Petroleum Pitch (ASP) Table 6 Thermal Treating Data of Molten Petroleum Pitch (ASPL-1) in Stirred Tank under 1Kg/cm2 G Nitrogen Pressure

6 134 Fig. ことがわがった ASPのス2に示す ASPか 7 SEMI Photograph 熱分解生成物収率を Table of Coke Attached on Alumina Bead 5 のケーらのコーク収率は, 原料の固定炭素の70 %であり, ASPLの場合とほぼ同じ割合である流動層からサンプリングした, コークの付着した無機粒子の走査型電子顕微鏡写真をFig. 7に示すコークの表面には, 顕著な凹凸があるこれはピッチが, 高粘性であり微粒化の困難な原料であることと, 固定炭素が大きいのでピッチがコーク化するときに体積収縮が小さいことによる ASPLとASPから得られたコークの表面状態はほとんど差がない 4. 考察 Fig. 8 Process of 4.1 Diagram of Two Stage Cracking Residue プロセスの合理化ピッチガス化実験プラントは, 60:40の Flow Vacuum ASPLとアントラセン油を割合で混合して低粘性油とし, それを熱分解する様わち, (1)分解温度, (2)滞留時間, (3)炭化水素分圧であり, コークの収率は熱分解の過酷度に比例して増加し, 原料のC/Hがに設計した低粘性油を熱分解する運転は, 比較的容易であっ大きければ大きい程, その傾向は大きくなる4) また, 液収率たが, 工業装置を想定した場合には, アントラセン油を使用すを最大にするためには低温のでることは, 以下の理由でプロセスの短所となる反応が重要であり, コークとガスの収率を最小にする場合にのコーキング (1) アントラセン油を安定的に確保しなければならないは, 生成油のAPI比 (2) アントラセン油は熱安定性が良いので, 単なる希釈剤とこの低温分解の概念はフレキシコーキングプロセスで実現されして働き, 熱分解生成物収率の改善に寄与しない重を下げることによって実現される5) ており, このプロセスは分解温度が )と (3) アントラセン油を取り扱うための貯槽や移送装置等が必低く, 滞留時間も短く, かつ炭化水素分圧が低いフレキシコーキン要であるグプロセスで, 分解温度をさらに低下させることが可能ならしたがって, 石油ピッチを単味で熱分解できればより合理的でば, 分解油収率はさらに増加することが予想されるしかしなあるので, 実験プラントの運転終了後に, 石油ピッチ単味の熱がら, フレキシコーキングプロセスのコーク化反応器は, コークの固気流動層であり, 熱分解残さが流動コークの表面に残る分解実験を試みて, 運転可能であることを確認したプロセスの集中合理化について述べる ASPLとために, 反応温度を低下させると粒子同志の付着が起こり, 安減圧残油を水蒸気分解して得られた残さの石油ピッ定的な流動を継続することが困難になるあるいは, 反応温度チで, 鉄鋼用のバインダーピッチに使用されているこのピッを低下させると, コーク化反応器の必要容積が膨大になり, 実チが, 鉄鋼用ではなく, 本プロセスのための中間原料であると用的ではないしたがって, 仮定した場合には, Fig. 8に示す様に, ないものと考えられる次に, ASPは, ピッチは高温の溶融反応温度を510 以下にはできるこの場合, 水蒸気分解反応器とコーク化槽から発生するガ合理化されたピッチガス化プロセスは, 減圧残油を, の低温で水蒸気分解したのちに, その水蒸気分解残さ状態のままでコーク化槽に供給されて, 最終的な熱分解を受けスの成分は同じであるので, 混合しても差し支えないガスをである石油ピッチを, 600 の混合することにより, 反応器下流の蒸留ガス精製等の装置 2段階プロセスであるプロセスフローダイヤグラムをFig. を, 重複して設ける必要がなく合理化できる 8に示す 4.2 High 減圧残油の2段階熱分解 BTU 水蒸気分解反応器は, 液相反応器であるために, 固気流動層ガスの製造実験において, を決定する因子は, 原料油のC/Hと固気流動層でさらに熱分解するタールとコークの量反応器のような分解温度の下限がないので, 低温で熱分解残さ残留炭素と運転条件すなが流動状態を保つ様に, 適度に熱分解して分解油を得て, 残さ石油学会誌 J. Japan Petrol. Inst., Vol. 26, No. 2, 1983

7 Table 7 Typical Physical Properties of Feedstock of the Commercial Steam Cracking Unit7) Table 8 Comparison of Product Yield: Steam Cracking and Pitch Gasification vs. Flexicoking

8 136 Nomenclature ASPL, ASPL-1=Petroleum pitch obtained by steam cracking of a vacuum residue. Coking values of these pitches are about 48%. cp ASP, ASP-1=Petroleum pitch obtained by steam cracking of a vacuum residue. Coking values of these pitches are about 60%. =centipoise References (1974). 2) Inatani, T., Kaji, K., Tanaka, M., Fujita, K., 4th Miami International Conference on Alternative Energy Sources, Miami Beach, Dec., (1981). 3) Suzuki, A., Tanaami, K., Takahashi, F., Sakai, N., J. Japan Petrol. Inst., 26, 57(1983). 4) Martin, S. W., Wills, L. E., "Advances in Petroleum Chemistry and Refining", Kobe, K. A. Ed., Vol. 2, 357 (1959): Linden, H. R., Pettyjohn, E. S., Inst. Gas Technol., Research Bull., No. 12 (April, 1952). 5) Martin, S. W., Wills, L. E., "Advances in Petroleum Chemistry and Refining", Kobe, K. A. Ed., Vol. 2, 357 (1959). 6) Grosse, F. D., Schroeder, H. F., "Flexicoking", (July 1977), Exxon Research and Engineering Co. 7) Aiba, T., Suzuki, T., Wakamatsu, T., AIChE 88th Natl. Meet., Philadelphia, June, 8-12 (1980). 8) Ozaki, H., Yamane, M., Yoshikai, O., J. Japan Petrol. Inst., 17, 879 (1974). 9) Yamane, M., Shoji, T., Ozaki H., Nenryo Kyokai Shi

9 137 Summary Development of Pitch Gasification Process (Part 2) Thermal Cracking of Petroleum Pitch in the Bench Scale Fluidized Bed Akira SUZUKI* and Kazuo TANAAMI* Thermal cracking runs on a sample of pitch were made to get the basic data for designing a test plant for production of reducing gas (H2+CO) by gasification of the pitch. The pitch obtained by steam cracking of a vacuum residue is classified into ASPL and ASP whose physical properties are shown in Table 1. ASPL and ASP both are hard pitches with softening points by flow tester were conducted with a gas-solid fluidized bed thermal cracking apparatus as shown in Fig. 1. The fluidized bed comprises a 2 or 3 inch vertical cylinder filled with some inorganic particles of 0.53mm in diameter as shown in Table 2. Viscosities of molten petroleum pitch and its solution were measured prior to each run. The results are shown in Figs. 2 to 4. Viscosities of ASPL-1 and ASP at 300 though the viscosity of the petroleum pitch was high, it could be lowered by diluting with a solvent such as anthracene oil. Table 3 shows the percentage of residue remaining after soluble matters in anthracene oil were removed by filtration. In ASPL, only small quantities of matters insoluble in the solvent were found, but in ASP large quantities of matters insoluble in the solvent were found. Thermal cracking tests were conducted using anthracene oil or a FCC cycle stock as solvent for diluting the petroleum pitch. When anthracene oil was used, a higher degree of thermal stability with lower yields of gas and coke was obtained than when the FCC cycle stock was used, as shown in Table 4. The ASPL diluted with anthracene oil was thermally cracked at 600 process. The one-pass yields of coke from ASPL based on the quantity of its fixed carbon amounted to 72 to 78%. The test plant was designed based on the above results. Thermal degradation tests were made on ASPL-1 in its molten state. The results are shown in Table 6. Although the physical properties of the pitch heated at temperatures should be used when it is necessary to keep the pitch in a molten state for a long time. Thermal cracking tests on ASPL were conducted. The pitch was easy to handle and it could be atomized readily. Thermal cracking yields of the pitch are shown for case 4 in Table 5, and the level changes in the pitch tank are shown in Fig. 5. Thermal cracking tests on ASP were conducted, too. Yields of thermal cracking products are shown for case 5 in Table 5, and the level changes in the pitch tank are shown in Fig. 6. A comparison of Figs. 5 and 6 indicates that ASP is more difficult to handle than ASPL. Fig. 7 shows some SEM photographs of coke from ASPL and ASP. Both cokes have irregular faces. Fig. 8 is a process flow diagram of the two-stage thermal cracker including the coker of the pitch obtained by steam cracking of a vacuum residue. Temperatures to produce 65.4% by weight of cracked oil from a vacuum residue containing 21.4% Conradson carbon residue. Yields of products obtained by the two-stage thermal cracking process and those by flexicoking process are compared and shown in Table 8. As a result it is expected that the two-stage thermal cracking process yields 4% more cracked oil than the flexicoking Keywords Fluidized bed, Petroleum pitch, Thermal cracking, Two stage cracking, Vacuum residue, Viscosity

Table 1 Properties of parent coals used Ebenezer, Massel Buluck ; Australia, Datong; China Table 2 Properties of Various chars CY char: Captured char

Table 1 Properties of parent coals used Ebenezer, Massel Buluck ; Australia, Datong; China Table 2 Properties of Various chars CY char: Captured char by cyclone char: Carbonized char at 1273 K 気流層石炭