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What factors determine the CO content entering the synthesis tower? How is the CO content entering the system determined? As can be seen from the previous calculations, if the CO conversion rate in the reactor remains constant, increasing the CO content fed into the reactor will increase production. Once the process flow and internal component structure are determined, the space velocity remains constant; within the limits of available adjustment options, the maximum CO content entering the tower reaches a certain limit value. In syngas, calculations of the heat balance show that converting 1% of CO results in an adiabatic temperature rise of 29–30°C in the reaction gases. If the temperature exiting the tower is maintained at 270°C and the temperature of the gas entering the catalyst basket is 30°C, then the adiabatic temperature rise can reach: 270 – 30 = 240°C. In this case, the CO concentration in the reaction mixture could reach 8%, but such a situation is actually impossible. A tower exit temperature of 270°C means that the temperature at the reaction hot spots within the bed could exceed 300°C, which is not acceptable for catalyst operation. Additionally, the active temperature range of the catalyst is relatively narrow (220–290°C). By feeding the material directly into the bed without preheating it, it becomes possible to achieve a uniform temperature within the bed quickly; however, no company currently possesses the capability to do this. Taking the isothermal type internal component as another example, in Process 1, if the percentage of CO reacting at a bed outlet temperature of 240°C is 3.5%, then the temperature increase is: 3.5% × 30 = 105°C. This is the temperature upon entering the catalyst basket ； 240 – 105 = 135°C. In processes two and three, the percentage of CO involved in the reaction is 5.5%, so the temperature increase is: 5.5 × 30 = 165°C. Therefore, the temperature entering the catalyst basket must be reduced to 240 – 165 = 75°C. This increases the difficulty in designing and manufacturing the internal components, and it may also lead to a larger temperature difference within the bed during operation. In production, the level of CO content entering the tower is determined by the volume of gas circulated by the circulator and by the CO content in the raw gas fed into the system (in other words, it is determined by the CO content in the raw gas). The CO content in the gas fed into the system can be calculated as follows: According to the calculations in question (3), the total gas flow rate entering the tower in Process 1 is 40,000 Nm3/h. The gas flow rate from stage 5 or 6 of the ammonia synthesis system compressor is 24,000 Nm3/h; thus, the circulation volume is 40,000 – 24,000 = 16,000 Nm3/h. If the CO content in the gas fed into the system is X%, then: (24,000 × X% + 16,000 × 0.5%) ÷ 40,000 = 4%. Solving for X gives X = 6.3%. For Processes 2 and 3, the total gas flow rate is 45,000 Nm3/h, and the circulation volume is 45,000 – 24,000 = 21,000 Nm3/h. If the CO content in the gas fed into the system is X%, then: (24,000 × X% + 21,000 × 0.5%) ÷ 45,000 = 6%. Solving for X gives X = 10.8%