Reasons for the failure of diesel products to meet corrosion standards
Thread Content
I would like to ask everyone what the reasons are for unsatisfactory copper sheet corrosion in diesel products, as well as the corresponding solutions.
It is likely that the desulfurization effect is poor due to the high sulfur content in the diesel. It can be adjusted by the reaction temperature rise, steam injection into the desulfurization tower, and water injection volume
1. Hydrogen sulfide in diesel is not stripped in the stripping tower (two-tower stripping process). 2. Water enters the reflux zone of the stripping tower. 3. Poor water separation in the cold crude oil and light oil fractions results in water entrainment. 4. The temperature at the top of the stripping tower is controlled too low. 5. The stripping tower load is too low. 6. Low feed temperature in the stripping tower. 7. The hydrogen sulfide content in the recycled hydrogen is on the high side ； Handling: Just think about it by yourself :)
The levels of thiol and naphthenic acid are too high. Alkaline cleaning can be used to solve it
1. The sulfur content in the raw materials is high and the reaction temperature is low; adjust the ratio of the raw materials and increase the reaction temperature appropriately to meet the requirements regarding the sulfur content of the product. 2. The proportion of catalytic cracking diesel in the raw materials is not well controlled. 3. The hydrogen-to-oil ratio is too low; increase the load on the recycle hydrogen compressor to raise this ratio. 4. The space velocity is too high; reduce it appropriately. 5. There are fluctuations in the operation of the distillation unit, resulting in incomplete removal of H2S; precise adjustments are needed. 6. Internal leaks occur in components such as the high-pressure heat exchanger, leading to shutdowns. 7. Carbon deposition occurs on the catalyst; it needs to be regenerated or replaced
Is your diesel alkaline washed? ? If alkali washing is carried out, it is caused by sulfur; if no alkali washing is done, it is caused by hydrogen sulfide, thiols, and sulfur oxides. The dry point of gasoline being low causes larger molecular thiols to end up in diesel. Other factors have little impact, and these factors mainly depend on the dry point, flash point, and freezing point – they are not the main methods for adjusting sulfur content! !
The dry point of gasoline is low, so all the high-molecular-weight thioethers end up in diesel
Are there any friends who have conducted in-depth research on these issues? If it is caused by diesel acidity, it is generally required that the acidity of the oil produced be less than 7 mgKOH/100 ml. If this criterion is met, can the possibility of corrosion caused by naphthenic acids be ruled out? For cases caused by sulfides, can alkali washing be used? Are there any special requirements when comparing it with gasoline, liquefied gas, etc.?
It’s probably because the straight-run diesel does not meet the corrosion requirements; control the concentration of the alkaline solution properly and enhance the alkali washing process.
Exactly! ! ! Amazing! :victory: