More than 90% of the world's ethylene is produced by tube furnace high-temperature cracking, and the cracking furnace is the core equipment of the ethylene plant. During ethylene production, coking on the inner walls of cracking tubes and quench waste boiler tubes leads to increased thermal resistance at the heat transfer interface and increased energy consumption of the device; increased tube wall temperature and shortened furnace tube life; reduced ethylene yield and yield. How to suppress coking, reduce cracking furnace energy consumption, extend operating cycles and furnace tube life are still world-wide technical problems. This project combines enhanced heat transfer technology with surface engineering technology, proposes an aluminum-chromium-silicon coating system to inhibit coking, carburizing and oxidation on the inner wall of the cracking furnace tube, and invents a cracking furnace composite furnace tube with a special surface ceramic layer. New technology for manufacturing. Composite compound diffusion barrier technology is used to improve the stability of the ceramic layer. Under cracking reaction conditions, the coking rate and carburizing rate on the coating surface were reduced by 72.5% and 80% respectively. The ceramic composite furnace tube has significant coking inhibition and anti-carburizing effects. The surface temperature of the coated furnace tube is about 30℃ lower than that of the untreated furnace tube. The temperature rise rate of the wall surface of the ceramic composite furnace tube is low, and the coke cleaning period is extended by 35~89%, which is 4.4% lower than that of the same furnace type. An inert metal coated furnace tube preparation technology has been developed, which can effectively inhibit the formation and deposition of coke scale on the surface of ethylene cracking and quenching waste boiler tubes. The coating inhibition rate can reach 80%. During the cleaning cycle of waste boiler operation, the steam generation per ton of raw material increased by an average of 2.44%; at the end of the operation cycle, the steam generation per ton of raw material increased by an average of 7.05%. The project has successfully developed high-temperature ceramic composite furnace tubes with coking inhibition functions, inert metal coated furnace tubes of quench waste boiler and their manufacturing technologies, realizing the industrial application of coking inhibition technology, reducing energy consumption, and breaking through The technical bottleneck of long-term and efficient operation of large-scale ethylene cracking furnaces has increased ethylene production and yield. The project has obtained 8 invention patents and has independent intellectual property rights. The only domestic manufacturing base for ethylene high-temperature cracking reaction furnace tubes with coking inhibition functions has been built. High-alloy ceramic composite cracking furnace tubes and inert metal coated quench waste boiler composite furnace tubes with coking inhibition function have good popularization and application prospects.  

Industrial application and assessment show that the cracking furnace uses ceramic composite coated furnace tubes, the temperature on the surface of the furnace tube is reduced by about 30℃ year-on-year, and the coke cleaning period is extended by 35~89%, which is 4.4% lower than that of the same furnace type. For a single ethylene cracking furnace of 100,000 tons/year, the direct economic benefits exceed 6 million yuan/year, and the economic benefits are significant. After using coking-inhibiting inert metal coating tubes for ethylene quench waste boiler, the heat exchange efficiency of the waste boiler is improved and the steam production rate is increased. In the latter part of the operating cycle, the output of high-pressure steam per ton of raw materials increased by an average of 7.05%. An average increase of 2.44% during the operating cycle. For a single 100,000-ton/year ethylene cracking unit quench waste boiler, it can produce 8000 tons/year of high-pressure steam, reduce the number of coke cleaning times by more than 30%, and direct economic benefits exceed 3.6 million yuan/year. The successful application of high temperature cracking coking inhibition technology in large ethylene cracking furnaces and quench waste boilers has solved the bottleneck problem that restricts ethylene production, has obvious energy conservation and consumption reduction effects, and significant economic benefits. At the same time, it has improved the technical level and international status of my country's ethylene production, and the social benefits are also very significant.