[Weekly Topic] June 28 – July 4, 2011

1. The reaction conditions are mild, and the catalyst can be used for a long time； 2. It can reduce the occurrence of negative methanation reactions ； 3. The range of available raw coal is wider.

There are still some issues with the sulfur-tolerant shift process in current Texaco water-coal slurry gasification units. Firstly, there is the problem of the water-to-vapor ratio; a low water-to-vapor ratio imposes significant operational constraints. Secondly, it is difficult to introduce gas into the shift reactor, as the low water-to-vapor ratio makes it easy for the reactor to overheat. Again, the transformation pipeline suffers severe corrosion during normal gas guiding processes.

Reply to 1# sxtblo: 1. Since the outlet temperature of the low-temperature reformer is around 200°C, the lubricant components present in the gas are not prone to volatilization. Moreover, oils are the main toxic substances in fully low-temperature reforming processes, and they can easily cause catalyst deactivation; therefore, it is necessary to strengthen the removal of oils from the incoming gas. 2. It is necessary to ensure an adequate level of hydrogen sulfide in the gas; if the total sulfur content in the gas is less than 150 mg/m3, the allowable level of hydrogen sulfide in semi-water gas can be increased. 3. To reduce the harm caused by H2S to the operational processes and equipment in various stages following the conversion process, it is necessary to enhance the secondary desulfurization capacity after conversion. 4. During operation, it is necessary to strengthen the drainage of the oil separator and the water replacement in the saturated hot water tower, in order to prevent oils and solid particles from entering the bed layer. 5. Strictly prevent the O2 content in semi-water gas from exceeding the limit; cobalt-molybdenum catalysts are sensitive to O2, and high O2 levels can easily cause deactivation and sintering of the low-temperature shift catalysts. If the O2 content increases during production, do not raise the furnace temperature by increasing the steam pressure; instead, reduce the amount of cold blast gas supplied to the auxiliary line in order to lower the bed temperature. 6. During operation, it is necessary to maintain a low reaction temperature at the hot spots, as well as a low steam-to-gas ratio; the temperature at these hot spots should generally not exceed 350°C, with a steam-to-gas ratio of 0.3–0.4. 7. After the low-temperature transformer is shut down and depressurized, the inlet and outlet valves of the low-temperature transformer should be closed. 8. After short-term parking, wait until the low-temperature converter inlet temperature exceeds 150°C before connecting the low-temperature converter when starting the vehicle. 9. When parking for an extended period, turn on the electric heater while driving to use gas to raise the temperature, and then start the operation once the temperature is normal.

The main ones are furnace temperature, water-to-gas ratio, and waste boiler

The key control points are as follows: 1. Stable furnace temperature; 2. Stable load; 3. Stable desalinated water quality; 4. Stable steam pressure; 5. Enhanced system blowdown; 6. Control of O2 content; 7. Stable composition of inlet gas (H2S content); 8. Stable operating control system pressure difference

1. Converter inlet temperature, 2. Steam-to-gas ratio, 3. Temperature inside the furnace, 4. Pressure

Why is overheating more likely when the water vapor content is low? Is it because methylation reactions occur easily?