Purification and refrigeration issues

Both are widely used; each has its advantages and disadvantages! Many choose propylene because it is considered non-toxic.

Either one is possible. In terms of practical operation: acrylic acid does not require operation under negative pressure, whereas ammonia does. Acrylic acid is flammable and explosive, making it relatively dangerous; meanwhile, even a slight leak of ammonia can be detected by its smell； The consumption of propylene units is slightly lower than that of ammonia units

There are many ammonia absorption refrigeration units with complex processes, but it is still possible to recover low-pressure steam. In short, ammonia compression refrigeration is widely used nowadays; it is better than propylene and safer

For ammonia-based refrigeration, it is actually best to use the new mixed-refrigeration process. That is, compression and absorption refrigeration; this process is relatively simple, and liquid ammonia at 5 degrees is obtained as a result, yielding better cooling effects

There is something inappropriate in the question raised by the poster; ammonia absorption refrigeration cannot use gaseous ammonia at a pressure of 80 KPa. Generally, the optimal operating pressure for gaseous ammonia in ammonia absorption refrigeration systems is around 3 bar. Operating under negative pressure results in high energy consumption, which is not economical. There are two approaches for the refrigeration units used in low-temperature methanol washing systems: one is compression refrigeration, and the other is a combination of compression refrigeration and ammonia absorption refrigeration. Ammonia absorption refrigeration cannot be used alone.

Ammonia absorption refrigeration can utilize the thermal energy of coal gas as a heat source for ammonia distillation, thereby cooling the syngas. However, in actual production, fluctuations in the load of the syngas occur due to changes in its flow rate, so a low-pressure steam stream is generally used as a backup heat source. Compared to ammonia compression refrigeration, ammonia absorption refrigeration can save a large amount of compression work, as well as a significant amount of steam or electrical energy. There are many ammonia absorption refrigeration units; they require a large amount of space and need significant heat exchange capacity through circulating water. Compressed refrigeration units require less space, and the initial investment for compressed refrigeration is roughly similar to that for ammonia absorption refrigeration. Ammonia compression refrigeration and its application depend mainly on the local hydrological resources, as ammonia absorption refrigeration requires a large amount of circulating water for heat exchange. On the other hand, considering production scale, the ammonia absorption refrigeration process is suitable mainly for small to medium-sized cooling applications; from an energy efficiency perspective, it is clearly less efficient than compression refrigeration for large-scale cooling systems. In addition, it is necessary to take into account the upstream process flow as well as the overall steam balance of the entire plant. For plants with a shortage of steam and water, or those that use a waste heat recovery system in their upstream conversion processes, a compression process should be chosen; whereas in environments where there is an excess of water and steam, an ammonia absorption refrigeration process can be utilized. This approach allows for savings in investment costs related to large compressors, reduces power consumption, and lowers overall costs. Therefore, it is not absolutely necessary to comprehensively consider under what circumstances which process should be used. Additionally, it is necessary to consider the cooling capacity required for low-temperature methanol washing and ammonia synthesis; in cases where a large cooling capacity is needed, ammonia compression refrigeration is chosen, as the compressors used in such situations are typically high-power centrifugal compressors that enable timely provision of cooling capacity. Easy to operate. For small-scale applications, the ammonia absorption refrigeration process should be chosen in order to save energy and reduce consumption.

Our company adopts the new ammonia hybrid refrigeration technology. . . . . . . . . . . . . .

Ammonia absorption refrigeration requires operation under negative pressure, resulting in higher operating costs. Propylene is not used, and it is non-toxic; we generally opt for propylene-based refrigeration.

Reply to 9# NHD83: Does compression refrigeration have any advantages over absorption refrigeration in terms of ease of operation? Is the temperature required for compressing propylene lower than that for compressing ammonia? Although propylene has low toxicity, it poses a greater explosion risk, so this isn’t a advantage!

Reply to 9# NHD83: Are you involved in NHD purification technology?