Purification Technology Edition Daily Question (Short Answer) [2018-2-5]

(1) Control the gas-liquid ratio properly. (2) Ensure that the parameters at the outlet of the purified gas meet the requirements. (3) Prevent the occurrence of high-pressure gas mixing with low-pressure gas; the H2S content in the thermoregenerated acidic gas should be above 30%, while the parameters of the lean liquid should be within acceptable limits. (4) The parameters of the water discharged from the water separation tower must meet the specified standards. (5) Control the system pressure and temperature properly. (6) Manage the tail gas washing tower effectively to ensure proper methanol recovery. (7) Adjust the amount of nitrogen used in gas lifting to improve its efficiency.

1. Control the vapor-liquid ratio properly； 2. Ensure the outlet parameters of the purified gas ； 3. Prevent the occurrence of high-serial-low phenomenon: the H2S content in the thermoregenerative acidic gas is greater than 30%, and the parameters of the lean liquid are within acceptable limits ； 4. The water discharge parameters from the water separation tower are within acceptable limits ； 5. Control the system pressure and temperature properly ； 6. Ensure proper operation of the exhaust gas scrubber tower and carry out effective methanol recovery ； 7. Adjust the nitrogen stripping amount to improve the stripping efficiency.

Key operating points: 1. The lower the temperature of the circulating methanol, the greater its solubility; therefore, a lower temperature for the methanol-poor stream is the goal for operation (the temperature for the methanol-poor stream is -50°C). The system is equipped with an acrylic refrigeration system to provide additional cooling, using the cooling effect resulting from the flashing (stripping) of exhaust gases to achieve the desired operating temperature. The main factors affecting the temperature of circulating methanol are: a. Cooling capacity supplementation from the propylene refrigeration system ； b. Nitrogen stripping flow rate ； c. Ratio of the flow rate of circulating methanol to the flow rate of shift gas. 2. The methanol circulation rate is used to control the gas composition parameters at the output section (ΣS≤0.1ppm), and it represents the primary means of regulation. The system is equipped with a proportional control system that ensures the circulation volume is proportional to the gas volume, thereby producing high-quality purified gas. 3. Pressure (the operating pressure of the main washing tower): According to Henry’s law, the higher the pressure, the better the absorption effect. The pressure in the purification main wash tower depends on the pressure of the shifted gas generated by gasification. The system uses Texaco gasifiers for gas production, and the pressure of the shifted gas entering the system is 5.4 MPa; due to this high pressure, the absorption efficiency is significantly improved. 4. Concentration (water content, regeneration degree of methanol): The water content in lean methanol is an important control parameter in normal production; the system is designed to keep this water content at ≤1%. A higher water content not only affects the efficiency of methanol absorption but also increases corrosion of the equipment. To achieve the recycling of methanol and obtain good absorption results, it is essential to effectively regenerate methanol. The methods used in the system for methanol regeneration include flashing, stripping, and thermal regeneration. Use a methanol-water separation tower to control the water balance in the solution system. 5. Parameters of the transformed gas (temperature and gas composition): The parameters of the transformed gas have a direct impact on the operation of the purification cycle. The system controls the composition of the transformed gas through the gas treatment section, and adjusts the HPC ratio by controlling the temperature of the carbon scrubbing tower. The composition of the transformed gas entering the system’s stage is 44% H2, 19% CO, 34% CO2, and 1.3% H2S.

(1) Control the gas-liquid ratio properly. (2) Ensure that the parameters at the outlet of the purified gas meet the requirements. (3) Prevent the occurrence of high-pressure gas mixing with low-pressure gas; the H2S content in the thermoregenerated acidic gas should be above 30%, while the parameters of the lean liquid should be within acceptable limits. (4) The parameters of the water discharged from the water separation tower must meet the specified standards. (5) Control the system pressure and temperature properly. (6) Manage the tail gas washing tower effectively to ensure proper methanol recovery. (7) Adjust the amount of nitrogen used in gas lifting to improve its efficiency.

(1) Control the gas-liquid ratio properly. (2) Ensure that the parameters at the outlet of the purified gas meet the requirements. (3) Prevent the occurrence of high-level gases mixing with low-level gases; the H2S content in the thermoregenerated acidic gas should be above 30%, while the parameters of the lean liquid should be within acceptable limits. (4) The parameters of the water discharged from the water separation tower must meet the specified standards. (5) Control the system pressure and temperature properly. (6) Manage the tail gas washing tower effectively to ensure proper methanol recovery. (7) Adjust the amount of nitrogen used in gas lifting to improve its efficiency

(1) Control the gas-liquid ratio properly. (2) Ensure that the parameters at the outlet of the purified gas meet the requirements. (3) Prevent the occurrence of high-level gases mixing with low-level gases; the H2S content in the thermoregenerated acidic gas should be above 30%, while the parameters of the lean liquid should be within acceptable limits. (4) The water discharged from the water separation tower must meet the specified standards. (5) Control the system pressure and temperature properly. (6) Manage the tail gas washing tower effectively to ensure proper methanol recovery. (7) Adjust the amount of nitrogen used in gas lifting to improve its efficiency.

Answer: (1) Control the gas-liquid ratio properly. (2) Ensure that the parameters at the outlet of the purified gas meet the requirements. (3) Prevent the occurrence of high-pressure gas mixing with low-pressure gas; the H2S content in the acid gas during thermal regeneration should be above 30%, while the parameters of the lean liquid should be within acceptable limits. (4) The parameters of the water discharged from the water separation tower must meet the requirements. (5) Control the system pressure and temperature properly. (6) Manage the tail gas washing tower effectively to ensure proper methanol recovery. (7) Adjust the amount of nitrogen used for stripping to improve the efficiency of this process.

(1) Control the gas-liquid ratio properly. (2) Ensure that the parameters at the outlet of the purified gas meet the requirements. (3) Prevent the occurrence of high-level gases mixing with low-level gases; the H2S content in the thermally regenerated acidic gas should be above 30%, while the parameters of the lean liquid should be within acceptable limits. (4) The water discharged from the water separation tower must meet the specified standards. (5) Control the system pressure and temperature properly. (6) Manage the tail gas washing tower effectively to ensure proper methanol recovery

(1) Control the gas-liquid ratio properly. (2) Ensure that the parameters at the outlet of the purified gas meet the requirements. (3) Prevent the occurrence of high-level gases mixing with low-level gases; the H2S content in the thermoregenerated acidic gas should be above 30%, while the parameters of the lean liquid should be within acceptable limits. (4) The parameters of the water discharged from the water separation tower must meet the specified standards. (5) Control the system pressure and temperature properly. (6) Manage the tail gas washing tower effectively to ensure proper methanol recovery. (7) Adjust the amount of nitrogen used in gas lifting to improve its efficiency

(1) Control the gas-liquid ratio properly. (2) Ensure that the parameters at the outlet of the purified gas meet the requirements. (3) Prevent the occurrence of high-pressure gas mixing with low-pressure gas; the H2S content in the thermoregenerated acidic gas should be above 30%, while the parameters of the lean liquid should be within acceptable limits. (4) The parameters of the water discharged from the water separation tower must meet the specified standards. (5) Control the system pressure and temperature properly. (6) Manage the tail gas washing tower effectively to ensure proper methanol recovery. (7) Adjust the amount of nitrogen used in gas lifting to improve its efficiency.