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1 Basic Information of the Company: After more than a decade of development, Hebei Kaiyue Group Chemical Co., Ltd. has evolved into a large-scale private enterprise group that focuses on coal chemical industries such as fertilizers, methanol, and formaldehyde, with industries like forestry, real estate, and coal sales serving as supplementary sectors. The company currently has nearly a thousand employees and possesses dozens of production lines that are at the advanced level in China, including those for producing formaldehyde, methanol, ammonium bicarbonate, 1370-width cold-rolled thin sheets, as well as full-hydrogen bell-type annealing furnaces. It also has high-density boards, medium-density boards, and melamine-faced panels. There are over 2,400 sets of various production equipment, several kilometers of dedicated railway tracks, a 50,000 m2 dedicated railway freight station, 50,000 m2 of commercial buildings, 500,000 m2 of factory land, and 200,000 m2 of factory buildings. Its subsidiary, the Formaldehyde Company, with an annual production capacity of 320 kt of formaldehyde, has become China’s largest formaldehyde producer. It also made it into the top 100 of China’s industries in three sectors: fertilizers, methanol, and the woodworking industry. 2 The significance of the dimethyl ether project: Dimethyl ether is recognized worldwide as an ideal clean fuel. Its properties are similar to those of liquefied petroleum gas, making it a potential substitute for liquefied gas. No modifications to the equipment used are required; it causes no environmental pollution, has no carcinogenic effects on humans, does not corrode metals, and boasts stable performance. Its safety level is higher than that of propane and butane. Dimethyl ether itself contains 34.8% oxygen, and its cetane number is greater than 55, which is higher than that of diesel. Using it as a fuel alternative to diesel helps to reduce the smoke and particles generated during combustion, as well as nitrogen oxide emissions; moreover, its combustion products contain no sulfur, and the exhaust gas does not contain formaldehyde. Dimethyl ether can also be used as a raw material in the fine chemical industry; it has a wide range of applications and promising market prospects for development. 3 Project Construction Status: In September 2006, based on market research and taking into account the company’s actual conditions, the company decided to build a 100kt/a dimethyl ether production facility, using a two-step gas-phase catalytic dehydration process for methanol. The plant was successfully commissioned at the end of May 2007, and its operation has been satisfactory. The catalyst used is of the 3H202 type, manufactured by Sanji Hua Chemical Factory in the Gongzhuling ** Agricultural Science and Technology Park; the amount of catalyst used is 13.5 tons. 4 Brief introduction to the process route: Using crude methanol as the raw material, methanol is first added to a vaporization tower, where it is heated using an external heat exchanger to cause vaporization. The vaporized methanol then passes through a heat exchanger to exchange heat with the gas coming out of the reactor, before entering the reactor for catalytic dehydration. After dehydration, the gas contains methanol, dimethyl ether, water, and some non-condensable gases generated as by-products; after cooling and condensation, a crude dimethyl ether mixture is formed, while the non-condensable gases are washed before being discharged. The crude dimethyl ether is refined through distillation to produce pure dimethyl ether, and the liquid at the bottom of the distillation tower contains some unreacted methanol, which is recovered and reused in the production of dimethyl ether. The reactor structure consists of a two-stage quenched fixed-bed reactor, with methanol vapor as the quenching gas. 5 Catalyst heating reaction: For heating the catalyst, an electric furnace is used as the heat source, with methanol vapor serving as the heat carrier. The entire heating process takes approximately 14 hours and can be roughly divided into two stages: the heating stage and the stabilization stage. The first phase takes about 6 hours, and the second phase takes about 8 hours. The temperature rise of the catalyst is shown in Table 1. http://www.nmtech.com.cn/jishuwang/upload1/0804211111079332.jpg During the catalyst heating phase, the heating rate should be controlled at around 20°C/h. In the stable phase, attention must be paid to the outlet temperature; it is essential to maintain stability in this temperature, and the heating power of the electric furnace should be adjusted frequently. The entire heating process of the catalyst proceeded smoothly and steadily, with no spike in temperature, which is generally in line with the expectations. When the reactor inlet temperature reaches around 220°C, the temperature in the upper part of the catalyst bed exceeds the inlet temperature, indicating that the catalyst has become active and is carrying out catalytic dehydration reactions. 6 System Operation Status (1) System Pressure: Pressure at the top of the methanol vaporization tower: 0.66～0.75 MPa ； Reactor inlet pressure: 0.66～0.70MPa ； Reactor outlet pressure: 0.64～0.68MPa ； Distillation tower pressure: 0.70～0.78 MPa. (2) Reactor temperature: Inlet temperature at Stage 1: 240～248℃ ； Optimal temperature range: 372～390℃ ； Temperature after second cold shock: 360～380℃ ； Second-stage hot spot temperature: 369～382°C. (3) Dimethyl ether selectivity: Methanol feed rate: ~24.7 m3/h ； Methanol usage: ~428.44 t/d ； Dimethyl ether production: ~307.38 t/d. Calculations show that the selectivity for dimethyl ether is greater than 99.82%, with very few side reactions. (4) One-way conversion rate of methanol; Reflux flow rate of distillation column bottom liquid: ~12.2 m3/h ； Methanol content: ~33% ； Specific gravity 0.95. Methanol feed rate: ~24.7 m3/h ； Methanol content: ~99% ； Specific gravity ~0.81. Calculations show that the one-way conversion rate of dimethyl ether is ~80.7%. (5) Product quality and methanol consumption: The dimethyl ether content in the product is ~99.8% ； Methanol consumption per ton of dimethyl ether (in terms of pure methanol) ~ 1.394 t. 7 Conclusion The JH202 methanol-to-dimethyl ether catalyst produced by the Sanji Chemical Factory in the Gongzhuling **Agricultural Science and Technology Park has, based on its recent use in our company, demonstrated low consumption levels, a low activation temperature, high activity, good selectivity, minimal by-products, and a methanol consumption rate that is lower than that of similar catalysts.