Practical Exercise on Purification Technology Version [017]

Common causes: 1) The catalyst temperature is too low, affecting the conversion rate； 2) Excessive load or too rapid increase in dosage leads to an increased gas space velocity, exceeding the maximum space velocity allowed when the catalyst is operating under normal conditions ； 3) Insufficient steam pressure; cannot be added ； 4) Low steam consumption results in an excessively low steam-to-gas ratio, or the steam-to-gas ratio is not properly adjusted in each section ； 5) Reverse sulfidation occurs, reducing the catalyst’s activity ； 6) Unstable operation, with fluctuations in pressure and temperature. The solution is: 1) Increase the reaction temperature ； 2) Reduce load or increase load gradually ； 3) Increase steam pressure or reduce load to lower system pressure ； 4) Increase the steam consumption and make adjustments strictly in accordance with the process operation parameters ； 5) Increase the inlet hydrogen sulfide concentration and inlet temperature, or re-sulfurize ； 6) Stable operation, stable pressure, and temperature.

(1) Reasons: ① The catalyst temperature is too low, affecting the conversion rate； ②Excessive load or too rapid increase in dosage leads to an increased gas space velocity, exceeding the maximum space velocity allowed when the catalyst is operating under normal conditions ； ③Insufficient steam pressure; cannot be added ； ④The low steam capacity results in an excessively low steam-to-gas ratio, or the steam-to-gas ratio in each section is not adjusted properly ； ⑤Reverse sulfidation occurs, reducing the catalyst’s activity ； ⑥Unstable operation, fluctuations in pressure and temperature ； ⑦The saturated tower has no liquid level, breaking through the U-shaped water seal.   (2) Treatment methods ① Increase the reaction temperature ； ②Reduce load or increase load gradually ； ③Increase the steam pressure or reduce the load to lower the system pressure ； ④Increase the steam consumption and make adjustments strictly in accordance with the process operation parameters ； ⑤Increase the inlet hydrogen sulfide concentration and inlet temperature, or re-sulfurize ； ⑥Stable operation, with stable pressure and temperature ； ⑦Establish the saturation column liquid level and close the U-tube valve.

(1) The main reasons for the increased carbon monoxide content in the transformed gas: ① Sudden increases or decreases in operating temperature, with large and frequent temperature fluctuations. ②The space velocity is too high, resulting in overproduction. ③Due to fluctuations in steam pressure and system pressure, the amount of steam added is too low. ④Catalyst poisoning, deactivation, aging, caking, crushing and pulverization, gas skew. ⑤Water is introduced into the catalyst layer, causing a significant drop in the bed temperature. ⑥The device has failed. A common fault is the corrosion and perforation of the tubes in the heat exchanger, allowing semi-water gas to leak into the exchange area ； If the water level in the water seal between the saturated tower and the hot water tower is too low, or if the pressure difference between them is too large, semi-water gas will flow from the saturated tower through the water seal and into the hot water tower. ⑦Improper operation. If the increase in dosage is too rapid and excessive, and the steam supply is not adjusted in a timely manner {when the system pressure and steam pressure fluctuate, the steam supply is not adjusted promptly} ； When the temperature of the catalyst bed drops, the vapor volume is significantly reduced, causing the gas-to-vapor ratio in the bed to become too low. (2) Treatment methods: ① The temperature of the catalyst bed must be strictly maintained within the normal operating range. Close attention should be paid to changes in the catalyst bed temperature, as well as to gas composition and pressure. Any changes in temperature should be adjusted promptly, with the fluctuation range of the bed temperature being less than ±10°C per hour. ②Overproduction is prohibited. ③The amount of steam added should be moderate, and it needs to be adjusted promptly according to conditions such as operating temperature, pressure, and gas flow rate. ④When catalyst activity decreases, high-temperature shift catalysts can have their operating temperature increased appropriately within their active temperature range, while low-temperature shift catalysts can be resulfurized; if necessary, the catalyst should be replaced. ⑤Control the liquid level in the saturated tower carefully; it is strictly prohibited to allow water to enter the catalyst bed. ⑥If a leak occurs in the heat exchanger, it can be detected by the changes in the composition of the reformate gas at the outlet of the reformer and at the outlet of the heat exchanger, allowing for timely repair or replacement. ⑦If semi-water gas breaks through the water seal in the saturated hot water tower and enters the shift gas, the following phenomena will occur: the circulating hot water pump trips or operates continuously to evacuate air, causing a large amount of water in the water seal to evaporate and the water level in the seal to drop. Air leakage, if caused by an excessive pressure difference between the saturated tower and the hot water tower, can be detected using the pressure gauges on these two towers. Once it is confirmed that the issue is due to the reasons mentioned above, water should be added to the saturated tower immediately to maintain the proper liquid level. At the same time, the cause of pump cavitation should be investigated, the fault fixed, and the hot water circulation restored ； Identify the cause of the large pressure difference between the saturated tower and the hot water tower, eliminate it, or reduce production accordingly. ⑧Operators must maintain stable operating conditions, operate with care, and make adjustments promptly.

Common causes: 1) The catalyst temperature is too low, affecting the conversion rate； 2) Excessive load or too rapid increase in dosage leads to an increased gas space velocity, exceeding the maximum space velocity allowed when the catalyst is operating under normal conditions ； 3) Insufficient steam pressure; cannot be added ； 4) Low steam consumption results in an excessively low steam-to-gas ratio, or the steam-to-gas ratio is not properly adjusted in each section ； 5) Reverse sulfidation occurs, reducing the catalyst’s activity ； 6) Unstable operation, with fluctuations in pressure and temperature. The solution is: 1) Increase the reaction temperature ； 2) Reduce load or increase load gradually ； 3) Increase steam pressure or reduce load to lower system pressure ； 4) Increase the steam consumption and make adjustments strictly in accordance with the process operation parameters ； 5) Increase the inlet hydrogen sulfide concentration and inlet temperature, or re-sulfurize ； 6) Stable operation, stable pressure, and temperature.

Common causes: 1) The catalyst temperature is too low, affecting the conversion rate； 2) Excessive load or too rapid increase in dosage leads to an increased gas space velocity, exceeding the maximum space velocity allowed when the catalyst is operating under normal conditions ； 3) Insufficient steam pressure; cannot be added ； 4) Low steam consumption results in an excessively low steam-to-gas ratio, or the steam-to-gas ratio is not properly adjusted in each section ； 5) Reverse sulfidation occurs, reducing the catalyst’s activity ； 6) Unstable operation, with fluctuations in pressure and temperature. The solution is: 1) Increase the reaction temperature ； 2) Reduce load or increase load gradually ； 3) Increase steam pressure or reduce load to lower system pressure ； 4) Increase the steam consumption and make adjustments strictly in accordance with the process operation parameters ； 5) Increase the inlet hydrogen sulfide concentration and inlet temperature, or re-sulfurize ； 6) Stable operation, stable pressure, and temperature.

Common causes: 1) The catalyst temperature is too low, affecting the conversion rate； 2) Excessive load or too rapid increase in dosage leads to an increased gas space velocity, exceeding the maximum space velocity allowed when the catalyst is operating under normal conditions ； 3) Insufficient steam pressure; cannot be added ； 4) Low steam consumption results in an excessively low steam-to-gas ratio, or the steam-to-gas ratio is not properly adjusted in each section ； 5) Reverse sulfidation occurs, reducing the catalyst’s activity ； 6) Unstable operation, with fluctuations in pressure and temperature. The solution is: 1) Increase the reaction temperature ； 2) Reduce load or increase load gradually ； 3) Increase steam pressure or reduce load to lower system pressure ； 4) Increase the steam consumption and make adjustments strictly in accordance with the process operation parameters ； 5) Increase the inlet hydrogen sulfide concentration and inlet temperature, or re-sulfurize ； 6) Stable operation, stable pressure, and temperature.

Common causes: 1) The catalyst temperature is too low, affecting the conversion rate； 2) Excessive load or too rapid increase in dosage leads to an increased gas space velocity, exceeding the maximum space velocity allowed when the catalyst is operating under normal conditions ； 3) Insufficient steam pressure; cannot be added ； 4) Low steam consumption results in an excessively low steam-to-gas ratio, or the steam-to-gas ratio is not properly adjusted in each section ； 5) Reverse sulfidation occurs, reducing the catalyst’s activity ； 6) Unstable operation, with fluctuations in pressure and temperature. The solution is: 1) Increase the reaction temperature ； 2) Reduce load or increase load gradually ； 3) Increase steam pressure or reduce load to lower system pressure ； 4) Increase the steam consumption and make adjustments strictly in accordance with the process operation parameters ； 5) Increase the inlet hydrogen sulfide concentration and inlet temperature, or re-sulfurize ； 6) Stable operation, stable pressure, and temperature.

Reason: 1. The catalyst temperature is too low, affecting the conversion rate； 2. Excessive load or too rapid increase in dosage leads to an increased gas space velocity, exceeding the maximum space velocity allowed when the catalyst is operating under normal conditions ； 3. Insufficient steam pressure; unable to add ； 4. Low steam consumption results in an excessively low steam-to-gas ratio, or the steam-to-gas ratio is not properly adjusted in various sections ； 5. Reverse sulfidation occurs, reducing the catalyst’s activity ； 6. Unstable operation, with fluctuations in pressure and temperature. The solution is: 1. Increase the reaction temperature ； 2. Reduce load or increase load gradually ； 3. Increase steam pressure or reduce load to lower system pressure ； 4. Increase the steam consumption and make adjustments strictly in accordance with the process operation parameters ； 5. Increase the inlet hydrogen sulfide concentration and inlet temperature, or re-sulfurize ； 6. Stable operation, stable pressure, and temperature.

Reason: 1) The inlet temperature of the shift converter is too low, affecting the conversion rate. 2) Excessive load or too rapid increase in dosage. 3) Reverse sulfidation occurs, reducing the catalyst's activity. 4) Unstable operation, with fluctuations in pressure and temperature. The solution is: 1) Increase the reaction temperature ； 2) Reduce load or increase load gradually ； 3) Increase the concentration of imported hydrogen sulfide, or re-sulfurize. 4) Stable operation, stable pressure, and temperature.

Answer: Reasons: 1) The inlet temperature of the shift converter is too low, affecting the conversion rate. 2) Excessive load or too rapid increase in dosage. 3) Reverse sulfidation occurs, reducing the catalyst's activity. 4) Unstable operation, with fluctuations in pressure and temperature. The solution is: 1) Increase the reaction temperature ； 2) Reduce load or increase load gradually ； 3) Increase the concentration of imported hydrogen sulfide, or re-sulfurize. 4) Stable operation, stable pressure, and temperature.