MCT PROCESS PILOT PLANT EXPERIMENTAL RESULTS

On the basis of the valuable research results gained from the bench size experimental facility, Beijing Huashi and Sanju Environment Protection and New Material Co., Ltd (hereinafter referred as “Sanju”) decided to expand the scale of the experiment by building a pilot plant together, in Nov. 2013.
The optimisation of the reaction model; completion of the detailed design of the process; and control scheme design throughout the process were carried out base on the massive experimental data gained during the pilot plant operation, which laid the foundation of development of the process design package.

Fig.2 the Pilot Plant
Key Results Obtained
1. Several reaction models were built through studying the pilot plan operation, such as plug-flow suspended bed model; circulated suspended bed model which represents the status of materials backmixing inside the vessel etc. Meanwhile the reactor design is continuously optimised to get the best match to the MCT process.
2. Obtained the change pattern of several key parameters such as reaction percentage conversion, heating rate control, flowage inside the reactor etc., regarding to the reactor inlet hydrogen/oil ratio.
3. The pilot plan operation helped developed the materials’ local flowage model inside the vessel, this include the bubble terminal velocity model, three phase micro-distribution model and micro-recycle model etc., these model together can represent the flow pattern of the reacting materials.
4. Obtained the effects of the superficial velocity of both gas and liquid inside the reactor vessel, on the parameters such as gas holdups and solid concentration, thereupon the dimension of the reactor can be calculated accordingly.
5. Tested the “Runaway (temperature)” and analysed its evolution process and mechanism. A dedicated feedforward control system, and developed a complete emergency precaution against the extreme operation condition of the suspended bed reactor.
6. A more precise mass balance was obtained during the pilot plan operation which provides the source of database for the process design package.
7. Through the comparison of the reaction status using cold hydrogen and cold VGO as the cooling agent respectively, the point of injection was found and know how to maximise the effectiveness of each.
8. The experimental data and parameters obtained during the operation provided abundant resources to the further development of the design package and the final process set-up.
9. Obtained different product distribution through modifying the inlet raw composition and the reaction condition. The products were tested, analysed and researched in terms of the reaction mechanism. This laid the foundation of the development of the targeted suspension bed technology in the future.
10. Through studying the coking condition of the equipment, dedicated improvements were made and successfully achieved long-term stable operation. This also provided valuable experience of the avoidance of coking to the process design package.
11. Developed the suspended bed hydrotreating stabiliser theory and technique.  Suspended bed hydrotreating stabiliser is a reactor that receives the products of the suspended bed hydrocracking vessel, which were mostly thermalcracked, and let them go through hydrogenation situation and hydrofining process under a relatively moderate environment.  This can significantly lower the sulphur, nitrogen, oxygen and unsaturated hydrocarbon contents in the product compare to the traditional suspended bed hydrotreating process, thereby stabilise the product and higher its quality with minimum extra costs.
12. Through optimising the operation condition of equipment which can coke easily such as HTHP/HTLP separator and vacuum tower, a series of techniques to ensure a long-term stable operation of the residue purging system was developed.
13. Massive amount of physiochemical properties data was recorded during the operation. This provided the key resources to the property data correction, fitting of thermodynamic equations, and the construction of reaction model in the future development.

MCT工藝中試階段成果
2013年11月，在小試裝置取得的重要成果的基礎上，公司與三聚環保新材料股份有限公司合作，進一步擴大實驗的規模，開展中試實驗。

通過中試集中采集了大量數據，優化了反應模型，完善了整個工藝流程的各個環節，制定了整個裝置關鍵的控制方案，為工藝包的開發奠定了基礎。

圖2  實驗中試裝置
主要實驗內容及取得的重要成果：
1、通過中試階段建立了多種反應器模型，如活塞流懸浮床模型、帶有大量內部循環的循環懸浮床模型等。通過不斷優化反應器模型，使反應器的設計更適應懸浮床加氫反應過程的實現。
2、通過改變反應器入口氫油比，得到了入口氫油比對反應轉化率、溫升控制、反應器流態化等參數的影響規律。
3、通過中試建立了局部流動機理模型。如氣泡終端速度模型、三相微觀分布模型、微循環流模型等，局部模型的建立表征了反應流動狀態。
4、反應器內氣體表觀流速、液體表觀流速等參數對氣含率、固含率等參數的影響規律，為反應器的尺寸設計提供了重要依據。
5、測試“飛溫”的演變過程，研究了懸浮床“飛溫”的機理，研發了針對性的前饋控制方案，找到了懸浮床操作中最極端工況的預防措施。
6、通過對中試裝置進行標定的過程，得到了更為精確的物料平衡數據，為工藝包的開發提供了準確的數據來源。
7、通過對比冷氫和冷油對反應器降溫的差異性，得到了各自適用的用點，以及如何才能發揮其各自的最大作用。
8、通過中試得到了全流程的工藝操作參數，為進一步的工藝包的開發、工藝流程的確定，提供了豐富的實驗數據來源。
9、通過加工不同的原料，并改變操作條件，得到不同的產品分布。再對產品性質進行化驗分析，并從反應機理上進行研究。為定向懸浮床技術的開發奠定了基礎。
10、通過分析中試裝置每個部位的結焦和堵塞情況，并對結焦和堵塞原因加以理論分析，結合了焦團聚結理論、焦團分散理論，焦炭吸附理論等一系列理論進行了深入研究，為工藝包設計中如何避免結焦堵塞提供了寶貴的經驗。
11、研究開發了懸浮床加氫穩定反應器的理論和工藝。所謂加氫穩定反應器，指的是在相對溫和的條件下，對以熱裂化為主的反應產物進行加氫飽和、加氫精制和加氫穩定的過程，可大幅降低常規懸浮床加氫工藝中硫、氮、氧和不飽和烴等雜質，以最小的代價提高油品的安定性，降低油品雜元素含量，顯著提升油品質量。
12、通過不斷優化熱高分、熱低分、減壓塔等易結焦部位的操作條件，找出了確保殘渣分離系統長周期運行的一系列處理手段。
13、通過中試裝置，采集了大量的物性數據參數，為工藝流程模擬中物性參數的修正、熱力學狀態方程的擬合、反應模型的建立提供了重要的基礎數據來源。