Acetone is a low boiling point ketone solvent with considerable dosage in coating, pharmaceutical and fine chemical industries. Its boiling point is about 56 ℃, and it volatilizes quickly at room temperature and is completely miscible with water. These two properties determine the two gates for acetone recovery: the condensation temperature level should be pressed deeply, and the condensate side should remove water. After the two passes, the recovery rate and reuse value of acetone are among the best in low boiling point solvents.
Acetone tail gas in the paint and resin industry comes from paint blending, spraying and drying. The pharmaceutical and fine chemical industries are mostly used as reaction solvents and washing solvents, and the reaction exhaust, vacuum pump outlet, centrifugation and drying processes are all carried. Scattered emissions from filling and sampling also account for a certain proportion. Acetone volatilizes quickly, and the negative pressure maintenance of the collection system and the wind speed at the hood are the keys to the collection efficiency-if the sealing is done well, the load entering the treatment section will be real and the recovered account will be right.
The normal temperature vapor pressure of acetone is high, and only part of the water-cooled two-stage condensation can be recovered. The yield depends on the low temperature section: the low temperature level is calculated according to the dew point of the intake air concentration, and the exhaust temperature is pressed to the range below the freezing point, and the condensation ratio of acetone increases obviously. Frost prevention and defrosting become the focus of operation: heat transfer deterioration and pressure difference rise after frosting on the heat exchange surface, defrosting cycle is arranged according to the pressure difference trend, and condensate low point heat tracing prevents freezing and blocking. The branch road with low concentration and large air volume still takes the route of concentration first and then condensation. It is not cost-effective to directly cool the branch road with large air volume. The operating parameters of the low temperature section are recorded day by day. When the temperature level, pressure difference and condensate volume are put together, the timing of defrosting is not guessed.
The cold recovery in the low-temperature section can be conveniently done: the heat exchange and precooling between the discharge condensate and the intake air will keep the cold in the system, thus saving the load and energy consumption in the low-temperature section.
Acetone is miscible with water, and the condensate is water-containing acetone, which should be dewatered before reuse: the condensate containing free water should first settle and divide into water, and the dissolved water should be dewatered by rectification. The acetone at the top of the tower should be classified according to the purity to meet the original use requirements, and the lower one should be used as cleaning solvent. The energy consumption of the dehydration tower is calculated according to the concentration of condensate. The higher the concentration of condensate, the less dehydration-this goes back to the collection end: the collection and sealing are well done, the concentration of condensate is high, and the accounts of the whole line are easy to calculate. The moisture content of dehydrated acetone is tested batch by batch, the test records correspond to the recovery ledger, and the direction of reuse is clear.
| Segment | Difficulty | Processing arrangements |
|---|---|---|
| Collecting end | Volatile fast and easy to escape | Negative pressure to maintain cowl air speed |
| Water cooling section | High vapor pressure at room temperature | Two-level pre-income burden reduction |
| Low temperature section | Frosting on heat exchange surface | Differential pressure trend defrosting |
| Condensate | mutual solubility with water | Sedimentation water separation and distillation |
| Reuse | Purity classification | Low-level cleaning |
| Winter | Low freeze | Heat tracing antifreeze drainage inspection |
It is related to the intake humidity and the condensate temperature, and the water content of the condensate in the low temperature section is usually lower than that in the normal temperature section. The moisture content is tested batch by batch, and the depth of dehydration is determined according to the detected value. The accounts are not determined by feeling.
The energy consumption increases obviously every time the temperature level is lowered a few degrees, and the temperature level is set according to the balance point between the recovery rate and the energy consumption, and unnecessary over-deep condensation is not done. The pre-cooling of the intake air recycles the cold energy, and the defrosting heat is included in the schedule to reduce repeated consumption.
The boiling point of butanone is about 80 ℃, which is higher than that of acetone. The condensation temperature is looser and the yield is easier to increase. Acetone is more volatile, the lower explosion limit is lower, and the requirements for explosion prevention and sealing are stricter. The difference between the two is concentrated in the low temperature section and the safety side.
This article by LuoyangWohong PetrochemicalEquipment Co., Ltd. arranges that the company provides design, manufacturing and operation and maintenance services for condensation recovery, membrane separation recovery and complete solvent recovery devices for chemical and pharmaceutical enterprises. If you need process evaluation or scheme configuration, please contact and exchange.
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