Treatment of liquid ammonia in the gas entering the synthesis tower

With high pressure, your flow rate is also high, which means the load on the electric furnace must be high as well, increasing power consumption. The pressure during the operation of the synthesis tower is generally around 20 MPa, and the load on the electric furnace remains constant; without this pressure, the load on the electric furnace would not be sufficient. Additionally, reducing pressure can speed up the heating rate. This post was last edited by snowdfr on 2009-3-24 12:16]

Due to improper level control or delayed ammonia release, which leads to an excessively high liquid level, liquid ammonia ends up entering the synthesis tower. Once liquid ammonia enters the tower, it increases the ammonia concentration within it, thereby suppressing the synthesis reaction and reducing the heat generated by the reaction. Meanwhile, the evaporation of liquid ammonia in the tower requires heat, which results in a significant drop in the temperature of the catalyst bed. In severe cases, this temperature drop can cause damage to the internal components of the synthesis tower. Handling: 1. Quickly lower the level of liquid in the separator; if the level gauge is faulty, repair it promptly. 2. Shut down the auxiliary line of the synthesis tower to reduce the circulation volume, thereby suppressing the drop in temperature; if the temperature falls below the reaction threshold, gas supply, pressure reduction, and power application for heating can be stopped. 3. When the temperature starts to rise normally, the circulation rate should be increased gradually to prevent a sudden spike in temperature. Generally, the temperature recovers quickly after the liquid-related issue is resolved, so it is necessary to exercise control in advance.

Safety must be considered first. The synthesis reaction deteriorates when liquid ammonia is used, and the system pressure rises sharply. When the bed temperature drops below the activation point, the synthesis reaction can no longer proceed. Therefore, at this point the supply valve should be closed first, and the system pressure should be controlled using the vent valve. Additionally, the temperature increase process follows what was mentioned on floor 2.

The purpose of reducing pressure before increasing temperature is as follows: 1. If the pressure is not reduced, the system pressure remains high, which means that the velocity of the circulating gas is high. As a result, the circulating gas passes through the catalyst layer in the synthesis tower at high speed, and it is carried out of the tower before it has time to react or before the reaction can proceed fully. Since the temperature of the incoming circulating gas is low, it carries away a large amount of heat upon leaving the synthesis tower; therefore, this not only prevents an increase in the temperature of the synthesis tower but also causes the temperature of the catalyst bed to drop. 2. When the temperature in the synthesis tower drops, it is usual to increase the venting rate, reduce the amount of circulating gas, and increase the amount of fresh gas, in order to lower the concentrations of ammonia and inert gases at the inlet. This helps to increase the reaction rate of the synthesis reaction and rapidly raise the temperature of the catalyst bed. Increasing the venting volume necessarily leads to a decrease in pressure

If the pressure is not appropriately reduced during the heating process, once the temperature exceeds the activation temperature, the reaction becomes quite intense due to the high pressure, and the rate of temperature rise will become uncontrollable, with a high risk of overheating.

If the pressure does not decrease, a high power level from the electric furnace is required, which is generally difficult to achieve; as a result, it is hard to raise the temperature to the range necessary for activity.

Generally, liquid presence in the synthesis tower leads to temperature differences (between liquid ammonia, copper melt, and oil-water mixtures). The measures taken to address this issue are to rapidly reduce the level of the cooling fluid, empty the oil level at the front of the tower, and in case of overpressure in the system, immediately activate the venting system to prevent liquid-containing gas from re-entering the tower； Reduce the circulation rate to prevent further drop in tower temperature, while raising the temperature of the electric furnace ； If the situation is not satisfactory, promptly contact the dispatch system to reduce production volume, and inform the relevant teams to lower the liquid level (in the copper washing and compression units). The separator should be drained, and when the electric furnace has insufficient load, the pressure in the synthesis tower should be reduced in order to raise its temperature again; when the tower temperature is too low, catalyst activity decreases, so the synthesis pressure can be lowered to below 15 MPa to rapidly increase the tower temperature ； In short, after an accident occurs, the priority is to minimize its impact as quickly as possible while ensuring safety, to handle the situation promptly, and to resume production as soon as feasible.

Without a pressure reduction, the volume of gas flowing through the tower is high, meaning there is a large amount of gas entering the tower; at the same time, the catalyst temperature is low, resulting in less heat generated by the reaction. In such cases, it is necessary to use an electric heater to warm the gas and supply the missing heat in order to maintain the optimal catalyst temperature. Since more gas enters the tower, this means that the power of the electric furnace increases. Under normal conditions, however, the power of the electric furnace remains constant; in order to raise the temperature at the hot spots quickly, the amount of gas is reduced, which in turn leads to a decrease in pressure and an increase in temperature. With constant power, the volume of gas decreases, resulting in more heat per unit of gas.