Breakthrough achieved in the renovation of the methanol synthesis system at China Coal Shaanxi Company

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Breakthrough achieved in the renovation of the methanol synthesis system at China Coal Shaanxi Company / Author/Source: Shaanxi Petroleum and Chemical Industry Federation / Date: 2020-12-03 / Clicks: 12 On November 29, the Shaanxi Petroleum and Chemical Industry Federation held a meeting in Xi’an to evaluate the scientific and technological achievements related to the “Development and application of key technologies for increasing the production capacity of the 1.8 million tons/year methanol synthesis system” developed by China Coal Shaanxi Yulin Energy and Chemical Co., Ltd. Experts deemed that this technology is at an internationally advanced level and contributes to advancing technological progress in the industry. Sun Zongli, the chief engineer of the Chemical Division of China Coal Shaanxi Company, explained that the original design called for an annual methanol production capacity of 1.8 million tons, as well as an annual consumption volume by the MTO unit of 1.8 million tons. Since the unit was put into operation in June 2014, it has been operating steadily. However, due to the large design margins in the methanol-to-olefins process and subsequent units, the maximum operating load of the methanol plant can only be increased to 103%, which is insufficient to meet the demand for methanol feedstock from those subsequent units; therefore, some methanol must be purchased externally. To fully unlock the potential of the methanol plant and increase its production capacity while further reducing energy consumption and waste, the company launched a research project in 2016 aimed at enhancing the capacity of the methanol synthesis system and optimizing its processes; key technologies related to this plant were studied as part of this project. In April 2017, a new gasifier was installed. On this basis, considering that the methanol synthesis reactor is a key component of the methanol production system, and that the gas distributor in the central tube of the radial reactor directly affects the uniform distribution of fluids within the reactor, the reactor pressure drop, and the carbon conversion rate – thereby influencing the methanol production capacity – they conducted in-depth studies on aspects such as gas distribution in the central tube, gas splitting, static pressure drops in the collection channels, and pressure drops caused by perforations in the central tube. By adjusting the opening ratio and area of the distributor in the central tube, they were the first to optimize the design of the opening ratio in large-scale methanol synthesis reactors, thereby improving the efficiency of methanol synthesis and enhancing methanol production capacity. The appraisal committee, headed by Researcher Xu Zhengang, the chief scientist at China National Coal Group Corporation, concluded that China National Coal Shaanxi Company also carried out the first industrial-scale trial use of a new catalyst for methanol synthesis, which increased the catalyst’s bulk density and specific surface area as well as the one-pass conversion rate of syngas, reduced the pressure drop across the catalyst bed, and achieved significant energy-saving effects ； The process technology of the methanol synthesis system was optimized, and an optimized operation mode featuring series-parallel coupling for the methanol synthesis tower was proposed, resulting in a significant increase in the production capacity of the synthesis system. The key technological innovations employed to increase the production capacity of this methanol synthesis system are highly advanced; they not only bring significant economic and social benefits to this company but also serve as a valuable model for domestic enterprises that produce olefins from coal (methanol). It is recommended that such technologies be promoted and applied more widely within the industry. It is reported that after this technology was applied in the 1.8 million tons per year methanol production facility of China Coal Shaanxi Company in September 2018, the system pressure drop decreased from 70 kPa to 20 kPa, the specific surface area of the catalyst reached 120 m2/g, and the one-pass conversion rate of syngas was 60%. The system has been operating steadily for over two years to date, with an annual methanol production volume of 2.15 million tons, representing a 20% increase in capacity. Since 2019, various technologies such as the synthesis reaction system for porous central tubes have been granted **patents.