[Haichuan Chemical Salary News] Tai Zhong Manufacturing’s largest DMO reactor in China has been successfully shipped

According to the Yellow River News Network (reporter Li Yuan), on August 19, the DMO reactors – key equipment needed for Hubei Sanning Chemical’s 600,000 tons per year ethylene glycol production project – were successfully shipped from Taiyuan Heavy Industry Group’s Tianjin Binhai Heavy Equipment Wharf. There are six such reactors in total. This shipment filled a gap in terms of the manufacturing and subsequent delivery of ultra-large pressure vessels by Taiyuan Heavy Industry Group, marking another achievement by the company in the field of manufacturing large-scale, high-end pressure vessel equipment in China.

This reactor is a key equipment for the ethylene glycol project, and it is also the largest DMO reaction heat exchanger in China at present. The entire unit is made of stainless steel, with each one weighing 266 tons. It is primarily used for the reaction of CO (carbon monoxide) and MN (methyl nitrite) to produce DMO process gas, with a catalyst playing a role in this reaction within the heat exchange tubes. Wang Jin, deputy manager of Tianjin Binhai Chemical Equipment Branch of Tai Zhong, explained that the high technical requirements, precise processing needs, and great manufacturing difficulties associated with these DMO reactors represent a first for Tai Zhong, which has extensive experience in manufacturing pressure vessels.

This reactor is a key equipment for the ethylene glycol project, and it is also the largest DMO reaction heat exchanger in China at present. The entire unit is made of stainless steel, with each one weighing 266 tons. It is primarily used for the reaction of CO (carbon monoxide) and MN (methyl nitrite) to produce DMO process gas, with a catalyst playing a role in this reaction within the heat exchange tubes. Wang Jin, deputy manager of Tianjin Binhai Chemical Equipment Branch of Tai Zhong, explained that the high technical requirements, precise processing needs, and great manufacturing difficulties associated with these DMO reactors represent a first for Tai Zhong, which has extensive experience in manufacturing pressure vessels.

Due to the special material of the reactor, its large size (diameter of 5540 millimeters) and thick tube sheet (220 millimeters), extremely high standards are required in terms of welding techniques, quality, and deformation control. During the manufacturing process, even the slightest amount of oil or steel debris can contaminate the all-stainless-steel structure, leading to unnecessary losses... Facing these numerous challenges, Tai Zhong began conducting thousands of tests related to processes and welding before equipment manufacturing, gathering a large amount of reliable data to ensure perfection throughout the product manufacturing process. The final product met all the design requirements upon inspection, and the pass rate for first-time radiographic testing of the welds was over 98%, earning high praise and recognition from the foreign supervisor and the customer.

China Chemical Industry News, October 24, 2018. Reporters from China Chemical Industry News learned recently from Yangmei Group Shenzhou Chemical Co., Ltd. that the company used a new type of radial bundle tube water-bed large-scale hydrogenation reactor developed by Nanjing Jutuo Chemical Technology Co., Ltd., which boasts complete independent intellectual property rights, to carry out technical upgrades to the hydrogenation B system of the first-phase 200,000 tons per year ethylene glycol production facility. This system was successfully put into operation on August 1 this year, and on August 7 the facility reached full capacity, with all performance indicators meeting the requirements specified in the process design. As of October 23, the device has been in continuous and stable operation for over two months. After industrial operation evaluations, the tower resistance was ≤22 KPa and the temperature distribution was ≤3°C. A single tower was capable of producing 100,000 tons per year of ethylene glycol via the hydrogenation of dimethyl oxalate (DMO), with all the product being of top quality. Once various aspects of the facility are further optimized, it is expected to achieve an annual production capacity of 200,000 tons of ethylene glycol. This achievement signifies the resolution of the \"bottleneck\" in scaling up single-reactor processes for coal-based ethylene glycol production, laying the foundation for the scaling up of single-series, single-reactor processes as well as entire plants for coal chemical products such as coal-based ethylene glycol and coal-based methanol.

Pioneering in hydrogenation reactors, Liu Xiaofeng, chairman of Yangmei Shenzhou Chemical Co., Ltd., told reporters that the DMO hydrogenation section of the company’s first-phase 200,000 tons per year ethylene glycol production facility originally consisted of two series, A and B, with a total of 4 shell-and-tube hydrogenation reactors. Since the shell-and-tube reactor operates in an axial flow regime, the resistance is high; the normal operating resistance for a single tower in the initial stage is 45 kPa to 55 kPa. Towards the end of the catalyst’s life, the resistance can reach up to 100 kPa, exceeding the design value and affecting the safe, long-term full-load operation of the device. In this technical upgrade, while keeping the existing process unchanged, a new radial bundle-type water-bed hydrogenation reactor developed by Nanjing Jutuo is employed. Only the two shell-and-tube reactors in System B are replaced, and some pipelines are adjusted to fit. The upgraded radial reactor makes use of the bubbles from the original reactors, allowing for natural circulation of saturated water within the reactor. Lu Jian, chairman and chief engineer of Nanjing Jutuo Company, told reporters that through extensive fundamental research and innovation, the company has focused on research related to methanol and ethylene glycol reactors and systems, as well as on the development and dissemination of new technologies. It has developed a radial bundle tube-type water-bed hydrogenation reactor suitable for DMO hydrogenation reactions using ethylene glycol, thereby breaking through the limitations associated with traditional shell-and-tube reactors that rely on large-scale single-series designs, and setting a precedent in this field in China.

Multiple technical breakthroughs have been achieved. Lu Jian said that this tubular water-bed reactor features several technical breakthroughs and notable advantages. First, a small tube sheet bundle tube structure is adopted. It overcame various limitations such as the difficulty in processing large tube sheets and the challenges associated with assembly, thereby breaking through the bottlenecks that prevented the enlargement of equipment. Second, multi-dimensional bending of seamless pipes is used. Welding at right angles to the flat tube sheet improves welding reliability and reduces the amount of welding required, thereby achieving intrinsic safety. Third, it has a larger surface area for heat exchange, resulting in strong heat transfer capacity, and no power is required to circulate the hot water. Outside the tube lies the catalyst reaction bed, which enables natural circulation, efficient heat transfer, and precise control of the bed temperature. Fourth, a radial flow is adopted, resulting in low resistance in the reactor bed. During methanol production, the pressure drop is reduced to about 0.1 MPa, while in the ethylene glycol reactor it drops to about 22 kPa. Compared with shell-and-tube axial-bed reactors, the pressure drop is much lower, resulting in significant energy savings; moreover, it is easy to scale up such reactors. Fifth, all heat exchange tubes adopt a full-length three-dimensional bent tube structure to automatically eliminate thermal stress. Wang Xuelin, general manager of Nanjing Jutuo Company, told reporters that the tube-in-tube water-bed reactor developed by the company has been successfully applied not only in the production of ethylene glycol via the hydrogenation of dimethyl oxalate, but also in the low-pressure synthesis of methanol from syngas and in the water-gas shift reaction. Currently, there are 5 units of this new type of reactor in use in the methanol production sector, with another 5 units set to go into operation. The largest single reactor among the operating methanol plants has a pressure of 5.5 MPa, and its production capacity can reach 600,000 tons per year. There is 1 unit in operation in the field of isothermal transformation, and 2 units are about to come online. In the field of coal-based ethylene glycol production, there is 1 plant in operation that produces ethylene glycol via the hydrogenation of dimethyl oxalate.