Acetone is widely used in pharmaceutical, coating, electronic cleaning and other industries: it has strong solubility, fast volatilization and mutual solubility with water. These characteristics make it very useful in technology, and at the same time, it also makes its waste gas recovery a little special-it is completely miscible with water, and it is difficult to remove water by static stratification in the recovery liquid. Therefore, the recovery, collection and condensation of acetone waste gas are the main body, and the disposal of the recovered liquid should be planned in advance.
The acetone waste gas in the pharmaceutical industry mainly comes from the reaction, extraction, crystallization, centrifugation and drying; the coating industry mainly comes from the paint, spraying and drying section. Similar to the aforementioned ester solvents, the coating and drying sections are dominated by continuous exhaust, while the pharmaceutical workshop is mostly intermittent exhaust with scattered points.
The collection ideas of the two types of working conditions are different: the continuous exhaust process is suitable for centralized collection and unified treatment; The intermittent, point-dispersed process is more suitable for grouping collection by point, giving priority to the treatment of points with large gas volume and high concentration.
Acetone has low boiling point and high vapor pressure at room temperature, so it can be condensed with less deep cold, so condensation is a common recovery method. It is also a solvent that is completely miscible with water, which brings two consequences: one is that when the exhaust contains water, the condensate is a mixture of acetone and water, which is difficult to separate by water; The second is that the recovery liquid must be reused and the dehydration problem must be solved first.
In addition, acetone is easy to volatilize. If the recovery liquid storage tank is not tightly sealed, it will continue to volatilize during storage, and the respiratory gas of the storage tank should also be included in the collection scope.
The first principle of collection is to reduce non-organization volatilization. The most direct and effective way to change the opening operations of feeding, sampling and discharging in the pharmaceutical workshop to closed or semi-closed. In the coating process, it is necessary to ensure that the exhaust air in the spray room and drying section is kept at the design air volume. Insufficient air volume will directly lead to the increase of workshop concentration.
When multiple devices are combined and collected, it is necessary to see whether the operating periods of each device coincide. The high degree of coincidence can be combined; the combined concentration of the staggered peak operation is diluted, and the efficiency of the recovery section decreases.
Acetone exhaust gas volume, medium high concentration, condensation section according to the classification design is more common.
| Segment | Configuration considerations | Description |
|---|---|---|
| Pre-cooling | Heat exchange with recovered cold air | Reduce the cooling load and reduce the accumulation of liquid in the pipeline. |
| Condensation section | According to the concentration and water content of the temperature level | When the concentration is high, most of it can be recovered first and then checked at the back. |
| Anti-frost | Low temperature section according to the water condition design defrosting | Alternate operation or set defrosting link when water content is too high |
| Dehydration | Acetone is miscible with water and requires special treatment | Select distillation or special dehydration unit according to reuse index |
| Storage tank | Keep airtight and include collection | Reduces continued volatilization during storage |
| Material | Compatibility with ketones and aqueous systems | Avoid dissolution and corrosion caused by long-term contact |
The acetone recovery liquid is mostly a mixture of acetone and water, which needs to be dehydrated before reuse. Depending on the process requirements can choose distillation purification, or as a low-grade use reuse. If the process has clear requirements for water content, the capacity of the dehydration section should be determined according to the target at the scheme stage.
Recycled liquid storage should pay attention to airtight and ventilated, storage period should not be too long. For high purity requirements, it is also necessary to pay attention to the impurity components in the recovery liquid.
By static stratification can not do, need to use distillation or special dehydration unit treatment. The dehydration depth shall be determined according to the requirements of the process for moisture content, and the configuration of this section shall be clarified in the scheme stage.
Low concentration, high air volume conditions can be considered after adsorption enrichment condensation, but acetone is easy to desorb,activated charcoalThe upper residence time is short, and the selection should be calculated according to the actual concentration and air volume. Most occasions are still dominated by condensation.
It depends on the requirements of the process for moisture content and impurities. Where the requirements are not strict, it can be used in low-requirement processes after simple dehydration. Strict requirements need to be purified to the specified indicators before reuse.
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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