Can gaseous ammonia be added to the copper melt in the copper washing station to ensure the total ammonia level?
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This post was last edited by *aoye613 on 2009-9-13 09:32. Recently I came across a post about adding gaseous ammonia to the copper cleaning solution; we have also discussed this issue here. The cooling load is quite high, with the pressure of gaseous ammonia reaching 0.2 MPa, making it difficult to lower the temperature of the ammonia used in the synthesis process. Our management is considering whether it would be possible to add gaseous ammonia to the copper solution in order to reduce the cooling load. Personally, I think this idea is not easy to implement, as there are many challenges involved. For example, how can we ensure proper control over the total ammonia level? The pressure at the inlet of the copper pump is usually around 0.1 MPa – so how can we ensure that the gaseous ammonia is properly added? Additionally, it’s necessary to ensure that the added gaseous ammonia is absorbed by the copper solution, so as to avoid any gas blockages. I’d appreciate it if everyone could share their opinions.
It is a practice adopted by many companies in refining operations to use gaseous ammonia instead of liquid ammonia for adding ammonia to the system; the main advantages are: 1. It enables effective reduction of the pressure in the gaseous ammonia main pipeline, thereby improving the cooling efficiency of the ammonia cooler； 2. Reducing the load on the ice machine helps to save energy and reduce power consumption ； 3. Gaseous ammonia contains very little oil and water, which helps to improve the cleanliness of the copper melt ； 4. Stable pressure in the main ammonia pipeline facilitates control of ammonia addition to the refining system, among other advantages ； Method of adding ammonia to the system: The gas-liquid injection method is used, that is, a liquid-gas injector is constructed to introduce gaseous ammonia into the copper melt (similar to a steam injector used for heating and generating hot water) ； The optimal location for addition is in the middle of the copper melt water cooler; this facilitates absorption, ensures effective absorption, and also reduces the ammonia cooling load.
A ejector for producing ammonia water is installed in front of the copper melt water cooler; the copper melt is used to introduce gaseous ammonia into it and absorb it. The heat generated is cooled by a water cooler.
There’s no need for anything complicated; just add gaseous ammonia at the inlet of the copper tank. Add automatic venting at the end.
In the process of recycling copper melt at small nitrogen fertilizer plants, the traditional method of adding ammonia to the copper melt involves using an ammonia addition tank to introduce liquid ammonia into the system in a quantitative, regular, and gradual manner. To reduce the load on the ice machines, save electrical energy, and lessen the workload for workers, our factory uses gaseous ammonia instead of liquid ammonia in the ammonia addition process. More than half a year of operation has shown that the use of ammonia can not only reduce the energy consumption of ice-making machines and stabilize the composition of the copper melt, but it is also safe, simple to use, and requires low operating costs. In the process of refining copper melts in small nitrogen fertilizer plants, the traditional method of adding ammonia to the copper melt involves using ammonia tanks to introduce liquid ammonia into the system in a quantitative, regular, and gradual manner. To reduce the load on the ice machines, save electrical energy, and lessen the workload for workers, the Yangshan County Nitrogen Fertilizer Factory uses gaseous ammonia instead of liquid ammonia in the ammonia addition process. More than half a year of operation has shown that replacing it with ammonia not only helps to reduce the energy consumption of ice-making machines and stabilize the composition of the copper melt, but is also safe and simple to use, with low operational costs; it is an effective measure for saving energy. 1 The process is simple: gaseous ammonia is introduced in front of the outlet valve of the copper melt ammonia cooler; the ammonia, which has been regulated via a 32×3 pipeline and control valves, flows directly into the middle part of the copper melt water cooler (as shown in the attached diagram). To prevent backflow of ammonia gas into the pipeline, the ammonia gas line before the water-cooled valve is made into an inverted U shape, so that its height is 1–2 meters above the level of the copper melt in the regenerator. To facilitate the absorption of gaseous ammonia by the copper melt and prevent gas blockage, the flow direction of the gaseous ammonia should be consistent with that of the copper melt, and the distribution tubes (five pieces, 18×3) should be inserted into the cold exhaust tubes by about 100 mm. 2. It is easy to operate and safe; the composition of the copper melt remains stable. Operation is simple and safe – all that is required is to adjust the ammonia valve at the outlet of the ammonia cooling system in order to maintain a stable ammonia pressure of 2–2.5 kg/cm², and to adjust the opening degree of the control valve before the water cooler. Ammonia gas is continuously added to achieve the desired overall ammonia content in the copper melt. No adjustment is required when production is operating normally; as long as the copper melt is cooled with ammonia and ammonia is added during production, there is no need to supply additional ammonia to the system. Since it went into production, the composition of the copper melt has remained stable, and the total ammonia level is higher than that when ammonia is added (1.0–1.3)×10³ m
It is best to add gaseous ammonia between the water coolers, as this results in a lower temperature of the copper melt in the water, which facilitates its absorption. If gaseous ammonia is added to the copper melting tank, the high temperature of the copper melt makes absorption difficult, leading to gas blockages that can affect the operation of the copper pump. This also causes instability in the CO+CO levels. Additionally, venting such gases has an adverse impact on the environment and the landscaping of the factory.
First of all, I must say that the original poster’s analysis is very comprehensive. However, there is one thing I’m not quite sure about: if the pressure of gaseous ammonia is maintained at 2.0–2.5 Kg, can the temperature of the copper melt at the outlet of the ammonia cooling system be kept within the range of 8–15 degrees? Does some of the gaseous ammonia used for cooling also need to be used for freezing purposes? I would appreciate your guidance. Thank you!
This post was last edited by ZZJJAA70 on 2009-8-8 at 20:57. Automatic venting is arranged above the ammonia-cooled outlet; the pipes remain above the regenerator. By maintaining the pressure of gaseous ammonia at 2.0–2.5 Kg, the temperature of the copper melt at the ammonia-cooled outlet can be kept within the range of 8–15 degrees. Excess gaseous ammonia is sent to the main ammonia vent pipeline.
Should automatic venting be at the ammonia-cooled outlet or inlet? Here, the venting is done on the ammonia-cooled inlet copper melt pipeline, and it is controlled by valves; I’m not sure what the difference is between this and automatic venting
Ammonia under pressure works perfectly – it serves two purposes at once: it ensures that the total amount of ammonia in the refining process is adequate, and it also helps to reduce the pressure of gaseous ammonia.
Generally, the higher point of the ammonia cooler is used for gas venting to prevent gas accumulation from affecting the heat exchange efficiency； In the case of vertical ammonia cooling, it is necessary to determine how many tube passes there are; based on this, the number of venting points to be installed on the upper head should be decided. Generally, the copper melt enters and exits from the bottom, so the vents should be placed on the upper head ； Under normal ammonia cooling conditions, the addition of gaseous ammonia or liquid ammonia has little impact on ammonia cooling. During normal operation of gaseous ammonia, discharge should be carried out in small amounts and on multiple occasions, in order to keep the system stable and avoid aggressive operations.