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1. Reactivity of coal: The reactivity of coal refers to its ability to react with various gasification agents (such as CO2, H2, and water vapor) under certain conditions. It is usually determined at a specific temperature by introducing CO2 at a certain flow rate, with the reduction rate of CO2 being used as an indicator of the coal’s reactivity. The higher the reduction rate of CO2, the better the activity of the coal. This method for evaluating the reactivity of coal has been in use. But personally, I think it’s not quite suitable for the current development of large-scale fluidized-bed gasification technology. As is known, the atmosphere in a fluidized bed is very complex; under high temperature and pressure conditions, coal coke reacts with CO2 and water vapor, while it is also affected by the products CO and H2. Therefore, current research on the reaction kinetics of coke and water vapor under pressurized conditions is more important, and this remains a weak area in China. Moreover, there are even fewer studies on the gasification reaction kinetics under conditions more similar to those of a fluidized bed. 2. Disadvantages of coal water slurry gasification: First, coal water slurry gasification requires a high amount of oxygen. The oxygen consumption is generally above 400 Nm3/1000 Nm3 (CO+H2). To reduce this oxygen consumption, it is necessary to use coal with low ash content and low ash melting point, as well as coal that has good slurry-forming properties, so that high-concentration coal slurries can be produced and the amount of oxygen consumed due to the evaporation of large quantities of water in the gasifier can be reduced. II. Furnaces in hot standby mode: Gasification furnaces generally need to be shut down for maintenance after operating for about two months, or when faults occur, and planned shutdowns are required. A backup furnace must be at a temperature of over 1000°C before it can be used to process materials. If a cold standby furnace is temporarily heated to above 1000°C, it will inevitably affect the production of the entire system; hence, it is necessary for backup furnaces to be in a hot standby state. Maintaining a hot standby furnace requires significant energy; it needs 150–1500 Nm3/h of gas, 150–1500 Nm3/h of air, as well as some extracted steam and cooling water. By strengthening management, optimizing operations to ensure long-duration operation of each furnace, carrying out planned shutdowns, and raising the temperature of the backup furnace before maintenance, it becomes unnecessary to have a hot standby furnace. III. The short service life of refractory materials in gasification furnaces: The bricks on the fire-facing side of these refractory materials are one of the key materials that determine whether a gasification furnace can operate for a long time and help reduce production costs. Currently, the most widely used bricks in the world are French bricks, Austrian bricks, and American bricks. The characteristic of French bricks is that they perform well at low operating temperatures and can adapt to large variations in operating temperature ； Austrian bricks and American bricks perform well at high operating temperatures, but they tend to become brittle when the operating temperature varies greatly. Our country has chosen French bricks (Safefire Refractories Company), with a lifespan of 1 to 1.5 years. At the Weihe Fertilizer Plant, the fire-facing bricks in all three gasification furnaces were replaced after one year of operation; each set of bricks cost 750,000 dollars, and the replacement process for a single furnace took a long time, disrupting production for two months. At present, our country is developing refractory materials that are inexpensive, resistant to high-temperature erosion, and have a long service life. At the same time, during installation we must ensure the quality of furnace construction, and strengthen management in operations to reduce fluctuations in furnace temperature, thereby artificially extending the lifespan of the bricks exposed to the fire. IV. Short lifespan of the thermocouples in the gasification furnace chamber: Due to the different expansion coefficients of the furnace shell and the refractory bricks when heated, shear forces are generated, which in turn affects the thermocouples. Each time the furnace temperature changes during startup and shutdown, we strive to control the temperatures of the enclosure and the furnace chamber properly, in order to prevent damage to the thermocouples and to guide our subsequent actions. If the thermocouple fails, we can determine the furnace temperature by observing changes in the CH4 content in the syngas, as well as the color of the slag discharged from the furnace, as well as the size and shape of its particles. This requires a high level of expertise and accumulated experience; we can also use other process parameters in the system to control the furnace temperature and maintain normal operation of the system. V. Short lifespan of the process burner: The stable operation of the burner is another important factor in properly operating the gasification furnace. The burners have a short lifespan (about 1.5 months) and are expensive (80,000 dollars per unit). According to data from Ube in Japan, burners are the main cause of frequent shutdowns of gasification furnaces; therefore, it is essential to closely monitor their operation during use. In Russia, we are able to assess the operation status of the burners each year by examining factors such as the cooling water system for the burners, the pressure difference in the gasification furnace, and the composition of the gases. We have also implemented interlocks specifically for the burner system; if the operation conditions deteriorate, the gasification furnace stops operating. Otherwise, in mild cases, uneven combustion from the burners can cause erosion of the refractory bricks, while in severe cases, the burners themselves may be damaged. VI. High investment in gasification equipment: We use the Texaco gasification process, which requires us to pay patent fees to Texaco Development Company. In addition, many special materials, equipment, valves, instruments, etc. need to be imported from abroad, and their prices are usually several times higher than those available domestically. Regarding design issues, most people in the country believe that with the successive commissioning of projects in Lunan, Shanghai, Weihua, and Huaihua, we have acquired extensive design experience and production skills, and domestic design institutes are fully reliable for undertaking such projects. VII. Short lifespan of the quenching ring: The quenching ring has a short service life (about 1 year), and it requires efforts from many enthusiastic individuals to develop improvements for it.