Is the nitrogen content in the refined oil from the reforming unit high?
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Our facility has recently encountered a high nitrogen content in the refined oil; the nitrogen level in the naphtha tank is 1.2 PPm, while the total nitrogen content in the refined oil is as high as 1 ppm. However, the alkaline nitrogen level is very low, at only 0.03 PPm. It seems that the nitrogen content in the naphtha has not been effectively removed after pre-hydrogenation. The temperature for the pre-hydrogenation reaction is 288 degrees, and the pressure is 1.9 Mpa. If anyone has encountered a similar problem, please share your insights!
There’s no way to increase the reaction pressure either!
Generally, denitration is achieved by increasing the reaction pressure, while desulfurization is achieved by raising the reaction temperature. If the pressure resulting from high demand reaches the design pressure (in the absence of a new hydrogen compressor), the only option is to work on reducing the impurity content in the hydrogenation feedstock
I’m not sure about the distribution of nitrogen content in naphtha. Can reducing the dry point help to decrease the amount of nitrogen in the feedstock, or can it reduce those components of nitrogen that are difficult to remove?
What catalyst do you use for the pre-hydrogenation reaction? Also, how should the reaction pressure be designed to be 1.9? Which process? Now, the options are either to consider using raw materials with a lower nitrogen content or to add a separate denitration catalyst.
The pre-hydrogenation catalyst we use is RS-1 from the China Institute of Petroleum Research; the reaction pressure should be around 2.2 Mpa, while the pressure in the high-pressure tank is 1.9 Mpa. The nitrogen content in the feedstock remains very low!
If the molecular structure of organic nitrogen is complex, such as in the case of non-alkaline nitrides or polycyclic nitrides, it cannot be removed under your conditions of pre-hydrogenation. Nitrogen removal relies heavily on reaction pressure, and your current operating conditions do not allow for an increase in this pressure; therefore, the only option is to adjust the raw materials used for pre-hydrogenation, by changing the tanks or mixing in smaller amounts of alternative materials.
Is the pressure drop across the bed of the pre-hydrogenation reactor high? Is it necessary to perform head removal?
First, check the corrosion inhibitor to see if it contains nitrogen and whether too much of it has been added