Catalyst temperature increase (2 points for participation reward)

The heating rate should not be too fast, and the temperature difference between the upper and lower parts should not be too large

9. Precautions 9.1 When the temperature of the first bed layer rises to 200°C, the heating rate should be reduced, with a rate of 12°C/h being appropriate. 9.2 TIC‑7203 should be kept closed at all times to prevent the hot gas from furnace F‑7201 from mixing with the cold gas in TIC‑7203, thereby avoiding thermal shock. The heating furnace’s flame-out coil must cool down before it can be used to regulate the temperature of the first bed layer. 9.3 After entering the main reduction phase, the water output increases; the heating rate should be slow. Pay attention to the pressure increase, ensuring that it does not exceed 0.5 MPa each time, and follow the principle of alternating between increasing temperature without raising pressure, and raising pressure without increasing temperature. Strictly control the water vapor concentration at the outlet of the synthesis tower to be less than 4000PPM. 9.4 Water vapor concentration analysis: Water vapor concentration is analyzed once per hour at the beginning of catalytic reduction. Analysis of catalyst-reduced primary and residual water vapor concentrations is conducted once every half hour. 9.5 Operating conditions for starting up the heater F‑7201: Process gas outlet temperature: TI-7219 shall not exceed 475°C. Flue gas outlet temperature: TI‑7220 should be below 900°C. 9.6 Pay attention to the liquid level in the high-pressure separator to prevent liquid from entering the synthesis tower. Additionally, to prevent false levels, the liquid levels in the high-pressure separator and the medium-pressure flash tank can be appropriately increased during reduction. 9.7 When the outlet gas temperature TI‑7221 in the synthesis tower reaches around 250°C, pay attention to the operation of E‑7201, as medium-pressure steam begins to be generated at this point. 9.8 During the reduction process, to allow the gas entering the tower to deliver more heat to the synthesis tower, TV-7206 can be increased in size in order to raise the temperature at the inlet of the synthesis tower. Reduce TV-7206 once normal production is resumed to generate more by-product steam.

Is there a corresponding temperature rise curve for the catalyst?

It’s mainly about speed; if it’s the drying stage, there also needs to be sufficient time at a constant temperature, and manufacturers usually provide a heating curve

At the start of the temperature increase, it is advisable to keep the temperature difference within the bed at less than 50°C. The gas flow rate should be increased as much as possible to avoid excessive temperature differences; throughout the entire temperature increase process, the lower the pressure, the better； It prevents the temperature in the upper part of the catalyst layer from rising too much; when entering the reduction phase, the intense reduction reactions cause a sharp increase in the catalyst’s temperature. 5.2 When transitioning from steam heating to the reduction phase, the oxygen content in the semi-water gas should be less than 0.5%, in order to prevent the reduced catalyst from being oxidized again, which could lead to repeated oxidation-reduction cycles and a sharp rise in temperature. If the oxygen content in semi-water gas becomes excessively high and the temperature soars, the power supply should be cut off to lower the temperature at the exit of the electric furnace; the amount of gas supplied should be reduced while the amount of steam supplied should be increased. The furnace can also be shut down completely and cooled using steam, and only after the oxygen content reaches the acceptable level should the gas be reintroduced into the system, in order to prevent damage to the catalyst. 5.3 When reducing the catalyst, steam must be added simultaneously, and a high steam flow rate must be maintained to prevent it from being excessively reduced to metallic iron by hydrogen. Metallic iron can promote the reaction of CO and H2 to produce methane, and it may also cause CO to undergo disproportionation reactions; carbon deposits form on the catalyst, blocking its pores. 5.4 When starting the electric furnace, the gas supply should be activated first; when shutting down the furnace, the gas supply should be stopped 5–10 minutes later. 5.5 During the reduction period, the composition of semi-water gas shall be analyzed every half hour, and that of shift gas shall be analyzed hourly, to ensure accuracy. Release each drain valve every half hour. 5.6 Since the end caps between the saturated hot water towers and between the medium-pressure conversion sections are designed and manufactured to be non-pressure-resistant, during the heating and reduction process, the pressure difference between the upper and lower sections must be strictly controlled to not exceed 0.02 MPa. 5.7 The maximum temperature during the catalyst reduction process shall not exceed 480°C. 5.8 The temperature should be increased strictly at a controlled rate to prevent a decrease in catalyst strength. In 5.9, steam can be introduced only if the lowest temperature of the catalyst bed temperature for medium-temperature catalysts is greater than 150°C. In 5.10, a medium-temperature catalyst can normally react with CO and H2 at temperatures around 200–250°C. This is a highly exothermic reaction; as the temperature rises, the reaction rate increases and it becomes more intense. If not handled carefully, there is a risk of damaging the catalyst. Therefore, it is necessary to introduce the reducing gas slowly, and throughout the reduction process, close attention must be paid to the temperature rise in the catalyst bed, as well as to changes in temperature, pressure, and gas composition. The ratio of steam to reducing gases should be adjusted promptly, and the rate of temperature increase must be strictly controlled. In the event of a sudden rise in temperature, the supply of reducing gases should be reduced or completely stopped immediately, while cooling is achieved using steam. The relevant personnel must ensure proper coordination of the steam supply to prevent damage to the catalyst or disruption to the operation of other systems. 5.11 Maintaining a constant temperature of 150°C for the catalyst is primarily intended to reduce the axial temperature difference within the catalyst layer, thereby facilitating the evaporation of physical water. Maintain a temperature of 200°C in order to raise the temperature at the lowest point of the catalyst layer above the dew point temperature. The axial temperature difference should be between 50°C and 80°C. 5.12 The reduction process follows the \"three lows and two highs\" principle, namely low CO concentration, low O2 content, low temperature, high space velocity, and high steam ratio. 5.13 During the reduction phase, the temperature at the outlet of the electric furnace should be maintained at 300±10°C to prevent fluctuations in the catalyst temperature caused by variations in the furnace outlet temperature; the inlet temperature should not be adjusted below the temperature at which the catalyst is active. 5.14 During the heating and reduction process, power outages, water interruptions, gas supply disruptions, malfunctions in the gas or equipment shall be treated as emergency shutdown situations. 5.15 The load should be increased gradually, not too quickly, to avoid excessive fluctuations in the catalyst layer.

Control the heating curve according to the curve provided by the catalyst manufacturer

Follow the heating curve provided by the manufacturer strictly!

The manufacturer should provide the temperature rise curve; it ultimately depends on the catalyst manufacturer···········