The hazards of light hydrocarbons to hydrogenation unit operations
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Our unit primarily hydrogenates mixed feedstocks of some secondary processed products (coke gas, slag along with naphtha, non-aromatic C5) to produce naphtha, which is used as a raw material for ethylene cracking. The products are mainly light oils; there is usually a relatively large amount of light hydrocarbons as by-products. If these are not removed, they can affect the operation of the recycle hydrogen compressor, the quality of the products, and the efficiency of amine solution regeneration. From a theoretical perspective, how do light hydrocarbons affect amine solution regeneration? And what else can be done with such light hydrocarbons if they are to be recovered and reused? (Solve)
After checking the relevant information, here are the answers to your questions:
1. The feed gas carries liquid hydrocarbons into the desulfurization tower, resulting in contamination of the amine solution. During the process, it is not possible to completely remove all the hydrocarbons and floating oils; these substances floating on the surface of the amine solution reduce its surface tension, causing foaming. The higher the oil content, the more severe the foaming. Over time, this contamination further affects the purity of the raw gas being purified as well as the regenerated acid gas, and it also leads to losses of amine solution. Additionally, when the amine solution deteriorates, its solubility in liquid hydrocarbons increases. On one hand, this causes an excess of hydrocarbons to dissolve in the flash tank, leading to an increase in pressure there. On the other hand, the polymerous organic compounds resulting from the degradation of the amine solution, which are carried along with the liquid hydrocarbons, end up in the subsequent dewaxing system. Even after passing through alkaline water, these compounds remain dissolved in the liquid hydrocarbons, resulting in failed oil test results for those hydrocarbons.
2. In our facility, light hydrocarbons are directly discharged into the low-viscosity system, from where they are pumped into storage tanks for contaminated oil
1. The feed gas carries liquid hydrocarbons into the desulfurization tower, resulting in contamination of the amine solution. During the process, it is not possible to completely remove all the hydrocarbons and floating oils; these substances floating on the surface of the amine solution reduce its surface tension, causing foaming. The higher the oil content, the more severe the foaming. Over time, this contamination further affects the purity of the raw gas being purified as well as the regenerated acid gas, and it also leads to losses of amine solution. Additionally, when the amine solution deteriorates, its solubility in liquid hydrocarbons increases. On one hand, this causes an excess of hydrocarbons to dissolve in the flash tank, leading to an increase in pressure there. On the other hand, the polymerous organic compounds resulting from the degradation of the amine solution, which are carried along with the liquid hydrocarbons, end up in the subsequent dewaxing system. Even after passing through alkaline water, these compounds remain dissolved in the liquid hydrocarbons, resulting in failed oil test results for those hydrocarbons.
2. In our facility, light hydrocarbons are directly discharged into the low-viscosity system, from where they are pumped into storage tanks for contaminated oil
Consider installing an additional refinery gas recovery unit to recover hydrogen-rich gas, gas from flare tanks, and hydrodesorption off-gases. This will help reduce emissions. Moreover, after desulfurization using amine solutions, the hydrogen-rich gas, flare gas, and other off-gases can be fed into this recovery unit, where they are compressed and subjected to diesel absorption/stripping processes, thereby producing crude hydrogen, liquid hydrocarbons, and naphtha, thus increasing profitability
Light hydrocarbons are desulfurized and then integrated into the fuel gas pipeline network