Synthetic ammonia Ammonia synthesis process

We need to identify the section where the pressure difference occurs; only by knowing the exact location can we help you determine the cause. It is mainly improper operation that causes fluctuations in furnace temperature, leading to catalyst deactivation; poor gas composition can cause catalyst poisoning, or crystallization in the pipes can result in blockages. In any case, it is necessary to determine and analyze the cause based on the location where the resistance occurs.

I. Main reasons (1) High resistance in the synthesis tower. 1. The resistance of the synthetic catalyst gradually increases due to caking caused by high temperature or pressure. 2. When loading and unloading the catalyst, the stainless steel mesh at the bottom gets damaged, causing catalyst particles to fall into the heat exchanger and leading to blockages. Either the particle size of the catalyst used is too small or the amount filled in is excessive, resulting in high resistance. 3. The concentricity of the internal components during installation is not satisfactory, resulting in uneven gaps in the sleeves of these components; or the insulation material surrounding them is damaged, and this insulation material blocks the air passages, thereby increasing resistance. 4. Defects in the design and manufacture of the internal components result in high resistance. (II) The circulation heater experiences high resistance; impurities such as insulation materials inside the synthesis tower, oil residues, copper melt, and fine catalyst particles end up in the circulation heater, causing blockages in the gas passages and an increase in pressure difference. (III) The filler in the oil separator is clogged by oil, increasing resistance. (IV) The ammonia condenser experiences high resistance; water accumulated inside the coil freezes, blocking the coil and thereby creating resistance. (5) The cold exchanger and some pipelines have high resistance. The elevated level of carbon dioxide in the refined gas enters the synthesis system where it reacts with ammonia in the recycle gas, forming ammonium carbonate crystals that clog the heat exchange sections of the cold exchangers as well as the pipelines ahead of the synthesis tower, thereby creating resistance. (VI) The copper melt enters the synthesis system, increasing the system resistance. II. Treatment methods: 1. For the large pressure difference caused by the synthesis tower, identify the cause, replace the catalyst or internal components, readjust the gap between the inner and outer cylinders, or repair the insulation of the internal components. 2. Resistance caused by the circulator heater; stop the operation for maintenance and remove foreign objects from the internal components. 3. In cases of high resistance caused by issues such as cold exchangers, oil contamination, ammonia condensers, and blocked pipes, steam cleaning or heating is used during shutdown to remove crystals, oil residues, and copper liquid from the system

This post was last edited by zhming on 2012-4-12 at 14:33. The original poster’s description is quite broad; the synthesis section is a very large area. If the pressure difference in the circulation loop is high while the pressure difference in the synthesis tower is not, it could be caused by valves or other equipment such as filters. If the pressure difference in the synthesis tower is also high, then it might be a problem with the synthesis tower itself, the main pipeline leading to it, or the cold side pipelines. The probability of problems occurring in the synthesis tower is relatively low; in contrast, there’s a higher chance of issues with the main pipeline and cold side pipelines due to valves

This post was last edited by snowdfr on 2012-4-12 at 14:42. The reasons for an increase in pressure difference during normal operation include: 1. A decrease in the hydrogen-to-nitrogen ratio, resulting in an increased amount of nitrogen; since nitrogen is denser than hydrogen. 2. Excess amounts of CO and CO2 in the gas, which lead to the formation of carbonate crystals that block the tubes in the ammonia cooler or other heat exchangers. 3. An increase in system pressure. 4. As the catalyst loses its activity over time due to fragmentation or caking, it causes an increase in system resistance and thus a rise in pressure difference. 5. Damage to the internal components; this is unlikely, as if the internal components are damaged, production can basically no longer take place. We encountered this once: the pressure difference in the synthesis system exceeded the limit instantly, forcing a shutdown; upon inspection, it was found that the internal components were damaged.

⑴Local sintering of the catalyst. ⑵The equipment pipes in the system are blocked by oil, rust, and ammonium salts. ⑶Improper operation can result in a small valve opening or the valve head coming off. ⑷The internal components of the equipment are damaged, and parts are blocking the gas passages. ⑸Catalyst crushing. (6) Excessive production load and high space velocity. (7) Imbalanced hydrogen-to-nitrogen ratio, excessive nitrogen.

Our plant has experienced blockages in the condensation towers; it seems to be due to ammonium carbonate crystals, though no further analysis has been conducted. The pressure returned to normal after steam treatment – I’m not sure if this is helpful