Pre-hydrogenation reactor pressure difference rises
Thread Content
Part of the naphtha processed by the continuous reforming unit of my device is imported (from the Gulf). Due to the overhaul of the device in 2008, this naphtha was stored for nearly 10 months. Recently, due to the processing of this naphtha, the pressure drop of the pre-hydrogenation bed increased (from 0.040Mpa to 0.090Mpa). When this naphtha is not blended, the bed pressure drop does not rise, but does it rise once it is blended? Analysis of the naphtha colloid content is 1.86mg/100ml ； It is a pity that this naphtha is not blended. I hope everyone can give me some ideas on how to deal with this naphtha so that it can continue to be used as a raw material for pre-hydrogenation?
Wouldn't it be enough to add less? It's the colloid that's causing trouble... Don't be impatient, just add it slowly and process it...: lol
It can be divided into small batches and used in atmospheric and vacuum pressure, diesel hydrogenation, pre-hydrogenation equipment and other equipment, and finally used as the raw material for pre-hydrogenation.
This is my personal opinion: You can consider hydrogenating gasoline and diesel in small quantities in batches, and then returning the cut naphtha, but this will increase the processing cost. Or directly blend gasoline in small batches.
Consider it from a processing point of view: In the case of a small amount of blending, the amount of circulating hydrogen is increased, that is, the hydrogen-to-oil ratio is increased, and the blending amount is controlled by the bed temperature rise. There is also what was mentioned above that can directly blend and stabilize the gasoline.
Appropriately increase the amount of hydrogenation, match the temperature and pressure well, and prevent the top pressure from being too high and compressing the reactor.
It means that if it has been stored for a long time and is not well protected, it will produce gum-like things. way: 1. Blending a small amount for a long time can increase the hydrogen-to-oil ratio and increase the hydrogen partial pressure. 2. You can send the pressure to normal and reduced pressure for a while. 3. Send gasoline and diesel for hydrogenation. 4. Consider sending catalyst. 5. Consider blending other oil products, such as gasoline.
Why didn’t you consider using nitrogen protection during storage?
The causes of increased bed pressure drop are:: ①The feed oil from the upstream unit is unstable in nature, such as containing dienes and other unstable substances. It quickly condenses and cokes in high-temperature areas such as furnace tubes and high-temperature exchangers to form carbon powder particles and deposit on the surface of the catalyst bed. ； ②The raw oil storage tank is not isolated from oxygen. Under the action of oxygen, some compounds containing sulfur, nitrogen, olefins and other compounds polymerize to form colloid. After entering the reaction system, they are further condensed and coked under the influence of high temperature to form carbon powder and deposit on the bed surface. ； ③The raw material contains iron ions. After the iron ions enter the reactor with the raw oil, they quickly generate ferrous sulfide under the action of hydrogen sulfide, which is deposited on the surface of the catalyst bed and forms a hard shell, hindering the passage of reactants. At the same time, iron sulfide will also cause heavy parts (such as high dry point and high carbon residue) to generate coke, and the coke will accumulate in the pores of the catalyst. ； ④The raw materials contain silicon, sodium, calcium and other metal impurities and inorganic salts, which deposit on the surface of the catalyst, blocking the catalyst pores and causing the catalyst particles to stick to each other and form caps. ； ⑤The raw material oil brings in more mechanical impurities from the upstream device, the filter is incomplete or out of line, etc., and is deposited between the catalyst particles after entering the reactor. ； ⑥The raw oil or new hydrogen contains chlorine. Firstly, it corrodes the equipment and produces a large amount of iron ions, which in turn causes the bed pressure drop to rise. Secondly, under the action of high temperature, chlorine ions condense and coke with certain compounds in the raw material in high-temperature parts such as furnace tubes and high-temperature exchangers to generate carbon powder particles, which are deposited on the top of the catalyst bed. For the full cycle process, the direct entry of circulating oil into the cracking reactor will also cause the pressure drop in the first bed of the cracking reactor to rise.: ①Impurities or Fe from the fractionation system during startup or production are brought into the cracking reactor by the circulating oil. ； ②The refined catalyst is pulverized and the fine powder is brought into the cracking reactor.