Our country is a large agricultural country. With the development of agriculture, the demand for chemical fertilizers is increasing, and the demand for synthetic ammonia is also greater. In the production process of ammonia synthesis, removal of CO2 is a relatively important process, and its energy consumption accounts for about 10% of the total energy consumption. The overall energy consumption level of my country’s ammonia synthesis process is relatively high. For small chemical fertilizer plants, in the whole ammonia synthesis process, the decarbonization technology is very backward, which has become a restrictive factor to reduce the overall cost of ammonia synthesis. Therefore, it will have far-reaching practical significance to choose a suitable low-energy decarbonization process.
In the early 1970s, the MDEA decarburization process was first industrialized in the United States and Germany, and gradually popularized and applied in developed countries. my country began to introduce the MDEA production process in the mid-1980s, and began to apply it to the decarburization process of synthetic ammonia in the early 1990s. MDEA decarbonization process has become one of the most economical decarbonization processes in the world. Dimethylethanolamine will be widely used in China.
The MDEA decarburization process refers to the use of MDEA aqueous solution as the absorbent,
Add a certain amount of activator, absorb the CO2 in the ammonia conversion gas under pressurized conditions, and the rich liquid absorbed by MDEA is regenerated under reduced pressure, and CO2, H2S, etc. are precipitated, and the purity of CO2 can reach 98%, which can be directly used as a commodity Or synthetic urea raw materials.
The MDEA decarburization process is divided into “semi-decarburization” and “full decarburization” processes
“Semi-removal” refers to the removal of 1/3 to 2/3 of CO2 in the shift gas. For manufacturers who co-produce liquid ammonia, this process can achieve the best economic results.
“Full removal” refers to the complete removal of CO2 in the shift gas, so that the CO2 content in the purified gas is ≤0.11%. At the same time, it has a good desulfurization effect, so that the total sulfur content of the purified gas is ≤5ppm. For manufacturers who co-produce methanol, this kind of The process is more suitable.
