Synthetic Ammonia Process Technology Exchange Area [Daily Question 2009-03-02]
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Synthetic Ammonia Process Technology Exchange Area [Daily Question 2009-03-02] How is a high-activity catalyst heated and reduced? What issues should be noted? This post was last edited by jindin312 on 2009-3-2 10:19.]
The topic is too broad; here is a preliminary response: Although the requirements for heating and reduction of transformation catalysts are not as stringent as those for synthesis and conversion catalysts, the quality of this heating and reduction process directly affects the catalyst’s activity and service life, so it deserves close attention. Therefore, for the temperature-raising reduction of the conversion catalyst, corresponding temperature-raising and reduction plans as well as temperature rise curves should also be established. General steps: 1. Purge with air ； 2. Heat the electric furnace using inert gas (or air) ； 3. Raise to a certain temperature (as required by the catalyst), then proceed with the temperature-raising reduction of semi-water gas (if air is used initially, it must be replaced with an inert gas) ； 4. After the heating reduction is complete, resume normal production. Precautions for heating and reduction: 1. Develop a comprehensive heating and reduction plan ； 2. Carry out heating and reduction strictly in accordance with the temperature curve for heating and reduction ； 3 Over-temperature is strictly prohibited ； 4. Maintain an appropriate airspeed ； 5 Coordinate well with other relevant work sections, etc. This post was last edited by jingsan on 2009-3-2 15:09]
How is temperature-induced reduction carried out for highly variable catalysts? 1. Based on the heating and reduction procedure for the catalyst used, draw the heating curve; at the same time, check that the electric heaters and electrical instruments are in good condition and functioning properly ； 2. Open the condenser vent valve, close the gas outlet valve of the condenser, the steam valve, the quench gas valve, as well as the vent valves of all equipment, along with the drain valve and the backwash valve. Add soft water to the saturated hot water tower until the normal liquid level is reached. Add cooling water to the condenser tower to the normal liquid level. Follow the heating curve, and steam should also be introduced during the heating process. 3 When the temperature of the catalyst bed rises to near the maximum allowable temperature for the catalyst, maintain this temperature for several hours. If the carbon monoxide content in the exhaust gas meets the production specifications, and if there is an increase in temperature in each section of the catalyst with that increase corresponding to the conversion rate of each section, then it can be considered that the reduction process is complete. What issues should be noted? 1. During the heating and reduction process, it is necessary to prevent excessive temperature differences; when the temperature difference exceeds 100 degrees Celsius, the temperature should be maintained at a constant level promptly ； 2 Superheated steam must be used only when the bed temperature rises by more than 20 degrees Celsius above the dew point temperature at that pressure. In atmospheric pressure systems, superheated steam can only be used once the bed temperature rises above 150 degrees Celsius. 3. The temperature of the heated gas must not exceed the maximum allowable temperature of the catalyst ； 4 During the entire heating and reduction process, each area should be drained by backwashing once every 0.5 hours ； When using 5 in semi-water gas reduction, it is necessary to increase the frequency of analysis and control the oxygen content and carbon monoxide content to prevent the catalyst from overheating ； 6 When reaching the reduction endpoint, the pressure should be increased slowly to prevent a sharp rise in temperature ； When reducing 7 high-varying catalysts, it is necessary to achieve \"three lows and two highs\": low carbon monoxide content, low oxygen content, low temperature, high space velocity, and high gas-to-gas ratio ； 8 Before powering on the electric heater, air should be supplied first; in case of an emergency, the power supply to the electric heater must be cut off first. The temperature of the gas at the outlet of the electric heater must not exceed 400 degrees Celsius.
Our boss said that after low-temperature heating and reduction, when no hydrogen is consumed, the pressure still needs to be increased. Why is that?