Does an atmospheric pressure tower stop operating for tower cleaning during a single operating cycle?

Remember: Pressure distillation columns never develop salt buildup. Salt formation only occurs in the initial distillation column, and the duration of operation affects a company’s production costs. The operational cycle is more than three years; there is no such thing as shutting down the column for cleaning. If the trays are damaged, the operation can be stopped for repairs

What was said upstairs is correct – it indicates that the tower has not been cleaned during the two production cycles. Keep in mind that salt formation due to straight distillation is unlikely; salts, sulfur compounds, and heavy metals increase in concentration depending on the density of the crude oil fractions. Therefore, salt formation occurs in the fractionation towers used in thermal cracking processes such as coking and catalytic cracking, but generally not in the initial distillation tower. It is recommended that you read carefully the first few pages of the questions and answers related to atmospheric and vacuum distillation techniques

This post was last edited by LQ198619 on 2017-8-6 at 15:30. OP, is the atmospheric pressure unit designed as a fractionating tower or a flash tower? If it’s a flash tower, and the feedstock contains high levels of salts that cannot be removed through electrical desalination, salts will accumulate at the upper part of the atmospheric pressure tower. Our atmospheric and vacuum distillation unit experienced salt accumulation in its upper section once before.

The tower is only boiled during shutdowns; now a major overhaul is carried out every four years

The atmospheric column of the atmospheric and vacuum distillation unit has not been washed; currently, the salt deposition problem is not severe, but salt deposition does occur in the fractionation column.

Regarding tower cleaning, I just want to ask: why shut down the operation if the tower isn’t cleaned? If the tower isn’t cleaned, when the manhole is opened, your production manager will be asked to go in and remove the tray sections – it’s dangerous and filthy. It takes effort to shut down the operation, so it’s necessary to thoroughly inspect the equipment to ensure a safe environment. If the tower isn’t cleaned and welding work needs to be done inside, I wonder who would dare issue a permit for working in a confined space. After cleaning the tower, there’s still a strong odor of oil and gas inside (it takes more than a week of full ventilation). If cleaning isn’t necessary, then no operators should go in for inspections; rather, let the person who gave the order not to clean the tower go in instead. Cleaning the tower is simple: during shutdown for purging, before stopping the steam supply, use a normal top circulation pump or a gasoline return pump (depending on the actual process in place) to pump water into the tower. Close all the extraction valves on the tower and allow the water to flow from top to bottom; then simply open a drain pump at the bottom of the tower to discharge the water. It would be best if there are conditions to cook in a tower.

Take a look at the OP’s question and explain it in detail.

For corrosion prevention reasons, the top reflux temperature in our atmospheric pressure column is raised to above 100°C, which results in the accumulation of large amounts of ammonium salts in the top circulation and the corresponding trays, causing the tray pressure drop to increase by more than 20 kPa. It was finally agreed to remove the ammonium salts by washing the tower without shutting it down. Lower the top return temperature, inject water into the top return, and cut off water in the top circulation. A large amount of ammonium salts was discharged from the top circulation pump.