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Solving the Challenges for Melamine Development – A Look at the New Process for Melamine Production via Pressurized Vapor Phase Method. Author/Source: China Chemical Industry News. Date: 2022-07-01. Clicks: 10. Editor’s Note: Recently, the China Petroleum and Chemical Industry Federation released the \"List of Green and Low-Carbon Processes in the Petrochemical Industry (2021 Edition)\". The 2021 edition of the catalog includes 9 additional entries and 10 additional processes compared to the 2020 edition, for a total of 40 entries. The newly selected green and low-carbon processes cover areas such as coal chemistry, silicone chemistry, fine chemicals, inorganic chemicals, and organic chemicals. They offer advantages in terms of product quality, energy and material consumption during the production process, emissions of waste substances, carbon emissions, and process safety. They are also expected to play a role in helping enterprises build new projects, upgrade existing ones, and promote the use of green and low-carbon processes in the industry. To this end, starting today, a series of reports titled \"Green and Low-Carbon Processes in the Petrochemical Industry 2021\" will be launched to showcase these newly selected green and low-carbon processes in the petrochemical sector for readers’ reference. The comprehensive energy consumption for producing this product is only 30% to 60% of that of advanced foreign technologies; the anhydrous melamine exhaust gas with a pressure of over 0.3 megapascals can be used to produce urea in a convenient and cost-effective manner, and it can also be utilized to manufacture other products flexibly, depending on the existing or desired industrial chain of the manufacturer... The new pressurized vapor-phase melamine production process developed by Sichuan Jinxiang Sairui Chemical Co., Ltd. (hereinafter referred to as Sichuan Jinxiang) has been included in the “List of Green Petrochemical Processes (2021 Edition)” due to its superior performance in key technical aspects such as raw material consumption, energy usage, and emissions of waste substances, compared to mainstream advanced foreign technologies. It is difficult to achieve a balance with traditional processes. Currently, the urea-based route is widely used in global melamine production, and it can generally be divided into three methods: high-pressure liquid-phase quenching, low-pressure liquid-phase quenching, and low-pressure gas-phase quenching. Among them, the high-pressure liquid phase quenching method does not require a catalyst; it features efficient process equipment, a small size, stable operation over long periods, and consistent product quality. However, its drawback is that it generates a large amount of process wastewater, and it has high energy consumption and investment requirements. The operating conditions for low-pressure liquid phase quenching are relatively mild, and the investment required is lower than that of the high-pressure method; however, its drawback is that the purification process is complex, and the options and value for utilizing the gas streams with high water content are limited. The low-pressure gas phase quenching method has a simple process, requires little space, results in lower investment costs, and does not generate process wastewater; its exhaust gases can be easily recycled. However, its disadvantages include low efficiency, difficulty in operating stably over long periods, and unstable product quality. To this end, Sichuan Jinxiang has developed a new process for producing melamine using pressurized vapor method, based on the low-pressure vapor quenching technique, thereby solving the problem of balancing environmental protection and economic efficiency in melamine production. At present, this process has been put into use in various manufacturing enterprises in China, and the related technology has also been exported to countries such as Germany and Russia. Self-developed technologies boost quality and efficiency. To address the issues of low reaction efficiency and numerous by-products in the vapor-phase method, Sichuan Jinxiang has independently developed a new type of fluidized-bed reaction system with high conversion rates and yields, tailored to the characteristics of melamine catalytic reactions. This system makes clever use of a large number of molten salt heating coils as internal components in the diameter fluidized bed reactor, and it features a scientifically designed circulation flow pattern for the catalyst particles in the dense phase region of the fluidized bed, thereby enhancing the orderly flow of particles and gas and ensuring stable catalyst activity. Even at reaction temperatures of 370°C to 375°C, the one-pass yield of melamine can reach 95%. In contrast, the reaction temperature for similar technologies in other parts of the world ranges from 390°C to 400°C, with yields of only 82% to 90%. This technology addresses the technical shortcomings of existing processes, such as low urea conversion rates and excessive by-product formation, while reducing the energy consumption required for the recovery of unreacted materials and by-products. Through the optimized design of various process parameters and adjustments to the equipment, Sichuan Jinxiang increased the production capacity per unit volume of its process equipment, reduced the size of such equipment, thereby enabling further expansion of the production capacity of its manufacturing lines. It also decreased the hardware investment and labor costs associated with producing each unit of melamine. According to statistics, this manufacturing process can achieve an annual production capacity of over 50,000 tons per line, and the capital investment per ton of melamine is only 54% to 72% of that required by existing technologies. Optimizing processes to save energy and reduce emissions: To achieve energy-efficient and efficient production processes, Sichuan Jinxiang has utilized technological innovations to increase the reaction pressure in existing similar processes from less than 0.2 MPa to at least 0.5 MPa. This increase enhances the rate of chemical reactions within the reactor, while also reducing the gas compression energy required by the fluidized bed reactor, thereby lowering the overall energy consumption of the system. The power consumption per unit of product under the existing process technologies ranges from 1,060 to 1,560 kWh, whereas it is no more than 600 kWh for products manufactured using this new process. At the same time, Sichuan Jinxiang has also developed technologies such as large-scale and high-efficiency molten salt heating systems, ultra-large gas-solid cyclone separators, a new type of large-scale high-temperature-resistant glass fiber gas-solid filtration system designed specifically for melamine, as well as online high-efficiency cleaning techniques for its filter elements, in order to further reduce energy consumption in the production process. According to statistics, the comprehensive energy consumption per unit of product using this process is only 30% to 60% of that of advanced foreign technologies, while the investment per unit of product is only 22% to 60% of that in advanced foreign technologies. Furthermore, the anhydrous melamine off-gas with a pressure of over 0.3 MPa produced by this process can be used, in conjunction with the company’s own catalytic decomposition purification technology and the production process for nitro compound fertilizers, to produce phosgene and compound fertilizer products. It can also be utilized to manufacture other products based on existing industrial chains, thereby enhancing the economic viability of melamine off-gas and expanding its application areas.