A distillation column is a contact device for the distillation of tower vapours, this device is also known as a distillation column. Concerning the types of distillation towers, today's presentation is about the cleaning of distillation towers.
To ensure that the
Distillation Tower is washed clean, to avoid cross-contamination and to ensure the quality of the product, the following protocols should be followed.
Solvent reflux: according to the needs of the actual situation, at the end of the distillation operation, the distillation kettle can be inhaled to the appropriate amount of solvent, rising temperature and atmospheric pressure reflux, will be adsorbed in the tower material as far as possible all brought out! The principle of solvent selection is to use the recovery solvent of the process!
Clear water overflow: directly from the distillation kettle's feed valve to the kettle to add the appropriate amount of water or through the tower top vacuum will be sucked into the kettle, with water preliminary washing; according to the actual situation to decide whether the washing water will be put away!
Alkaline water washing: vacuum to the kettle to suck in about 1% of alkali, then raise the temperature to 100-110°C, full reflux for 60min and collect the fraction, wash the pipes and equipment with alkaline water.
Hot water overflow: add an appropriate amount of water to the distillation kettle, raise the temperature and reflux for 30min, then collect the whole to achieve the purpose of washing away the alkaline water from the equipment and pipes.
Vacuum drying: Vacuum drying is used to dry the distillation tower, the operator can observe through the sight glass to confirm that there is no water accumulation in the distillation kettle, the temperature of the gas phase in the kettle reaches 80~90℃, and the drying operation can be considered over after maintaining for 60min!
Methanol washing: vacuum to the kettle into the qualified recovery grade methanol solvent, warm up for full reflux, appropriate amount collected to each collection tank; note that methanol reflux before and after are to take samples for analysis (including each collection tank).
Compare the changes in the quantity and content of impurities in the methanol solvent before and after washing the tower. After methanol washing, the operation is still carried out by means of vacuum drying, with the temperature of the gas phase in the kettle reaching 50-60°C and maintaining it for 60min to be considered as the end of the drying operation.
Solvent washing: according to the production requirements of different species, vacuum then suck in the appropriate amount of solvent into the kettle, raise the temperature for full reflux, collect the appropriate amount to each collection tank, pay attention to the reflux before and after still to take samples for analysis; solvent washing is still dried by vacuum drying, drying temperature and time according to the specific circumstances of the selected solvent.
Check and confirm: The washing operation is considered to be finished when the analyst has checked and confirmed that the equipment is qualified; otherwise, repeat step 7 and wash again until qualified.
Before the equipment is put into use, the operator has to check the equipment carefully to make sure that the safety accessories are available, the vacuum level is in line with the requirements, the feeding requirements are available and the relevant forms are filled in before production.
Cleaning process
The cleaning process is divided into four categories: spray cleaning, circulating cleaning, soaking cleaning (trough dipping method and irrigation dipping method) and wiping cleaning, the specific process depends on the site equipment.
Spray cleaning: spray cleaning is a circular cleaning technology, in the cleaning process, the chemical cleaning solution will be sprayed evenly to the inner surface of the system to be cleaned, with the gravity of the cleaning solution and flow along the container wall to the bottom, so that the cleaning solution and the inner wall of the container to make full contact, the chemical reaction to achieve the requirements of the cleaning system. By adjusting the position of the shower head, the cleaning liquid can be sprayed to the top of the container and the inner wall of the container to ensure the cleanliness of the entire container cleaning.
Circulation cleaning; circulation cleaning is the use of cleaning pump station as an additional power, through the cleaning fluid in the cleaning system for circulation, so that the cleaning fluid and equipment, pipelines and oil on the inner surface of the reaction, in order to achieve the purpose of degreasing.
Soak cleaning: soak cleaning is a dissolution stripping cleaning technology. In the cleaning process, the cleaned equipment or pipe fittings will be immersed in the chemical cleaning solution, with the help of the cleaning solution dissolution stripping effect, so that the cleaning solution and the grease on the surface of the cleaned parts for full contact. By heating up to accelerate its chemical reaction and dissolution speed to achieve the purpose of degreasing.
Wipe cleaning: wipe cleaning method is mainly for the weld, with the above methods can not deal with the equipment and pipe fittings and the above methods after the treatment of the local use of wipe cleaning method.
Drying process
According to the equipment cleaning and drying requirements, use oil-free dry air to blow the finished pipeline or equipment after cleaning, blow until the export dew point reaches the acceptance standard requirements.
Indicators of oil-free dry air
Air volume: about 25-30m3/min
Dew point: ≤ -40℃
Oil content: ≤0.01mg/m3 (21℃)
Dust particles: ≤0.01?m (21℃)
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Source: Xianji.com
