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Introduction to the methanation injection cycle process. Basic methanation processes: 1. Through in-depth research and comparative analysis of the Topsoe methane synthesis technique and the Davy methane synthesis technique, we have gained a thorough understanding of the key aspects of both technologies. Topso technology is a good one, but it requires a high-pressure waste heat boiler; a high-pressure boiler must be installed as part of the system for operation, and this brings numerous issues regarding construction and operational management. 2. Through actual operation, we found that the pressure drop in the methane reactor system is very low, ranging from 7–10 KPa; it is generally between 10–25 KPa, and even when it is higher, it stays within the range of 30–35 KPa. Combined with our understanding of the theory behind injection technology as well as our many years of practical experience in its application, using the pressure of the desulfurized process gas as a driving force to enable an injection cycle process eliminates the need for a cycle gas compressor, representing a significant breakthrough in the methanation synthesis process. 3. We use a combination of multiple injectors to enable adaptation to different gas volumes while maintaining the same shape of the fluid ejected by the nozzles; flow rate adjustments within 10% of the total flow are carried out using needle-type regulation. II. Advantages of the jet cycle 1. Equipment investment costs are **reduced to about 1/3, and it requires less space. 2. Save electricity by transferring the power of low-efficiency circulators to high-efficiency large compressors ； 3. Being merely static pipelines, the number of safety management points is greatly reduced. With no moving parts, compressor-related accidents are completely avoided; there is no need for maintenance nor associated costs, **thus enhancing the reliability of long-term operation. III. Projects That Are Already in Operation 1. Shanxi Juyuan Coal Chemical – Explanation of Actual Operating Conditions and Relevant Data a. Initial design parameters (Northwest Research Institute): Amount of coke oven gas: 28,000 Nm3/h; actual amount: 14,500 Nm3/h ； No cyclic process; Operational performance: The reaction temperature can reach up to 650°C, the catalyst needs to be replaced every 2–3 months, or at most every 6 months, which prevents stable production. b. Jet cycle modification: The jet cycle process was put into use in October 2016 ； The design cycle ratio is 1.0 v/v, with the reactor temperature controlled at 520°C. During actual operation, the recycle ratio was 1.3 v/v (1850/1400); the temperature in the first reactor was 461°C, and that in the second reactor was 456°C. After operating stably for 1 year, very significant results were achieved. 2. Operational status and data of Fuyangyuan in Xiangyuan, Shanxi a. Initial design parameters (Xindi Yard): Coke oven gas volume: 18,000 Nm3/h ； Circulator power: 400kw × 2 units ； Operational performance: Operation is problem-free. Compared to the jet cycle process, which has higher power consumption, the use of a mixed refrigeration (MRC) compressor in the preliminary processes such as compression results in a total power consumption of 2000 kw.h/t (1.379 kw.h/Nm3). Of this amount, the MRC compressor accounts for 600 kw.h/t (0.414 kw.h/Nm3), while the power consumption associated with the process itself is 1400 kw.h/t (0.966 kw.h/Nm3). This power consumption rate is 1.5 times higher than that of Jingbao’s 850–900 kw.h/t (0.58–0.62 kw.h/Nm3); the power consumption per ton of LNG is 450 kw.h/t higher, resulting in an additional power consumption of over 16 million kw.h per year. The initial idea was to apply various technologies from our previous energy-saving upgrades to the compressor systems at Jingbao Xin’ao, but it was later decided to use the jet cycle process first in order to address the issue of having the circulation machine and the heating furnace operating simultaneously. b. Modification of the injection cycle – Design concept: Respect the original process; air is introduced separately for the first and second reaction stages, following a two-stage circulation system, with a circulation ratio of 1.6 v/v for the first stage and 1.0 v/v for the second stage ； With a total air intake of 16,000 Nm3/h, the air intake for Stage 1 is 10,000 Nm3/h, and that for Stage 2 is 6,000 Nm3/h ； The reaction temperature is controlled at 500℃ ； The ultimate goal is to shut down the recycle gas compressor and the heating furnace. Operational performance: Put into operation on September 2, 2017. Total desulfurization gas flow rate is 19,000 Nm3/h; the circulation ratio in the first stage is 2.0 v/v, and that in the second stage is 1.3 v/v ； Reactor temperatures: 432.70°C in Stage 1, 422.20°C in Stage 2, and 256.20°C in Stage 3. The reaction temperature is much lower than the designed value, resulting in excellent performance; the objectives of the retrofitting were thus achieved. Even when operating at a low load (9000 Nm3/h), with both sets of injectors in use (without any adjustments), the temperature in Stage 1 reactor remained at 432.70°C. Welcome all friends to discuss and provide guidance together. My email address is sihuiforever@163.com