Isopropyl alcohol is used in a large amount in electronic cleaning, pharmaceutical and coating industries, with a boiling point of about 82 ℃ and complete mutual solubility with water. These two properties determine its recovery route: condensation recovery is not difficult, temperature requirements are loose, and the real workload is on the condensate side-mutual solubility with water means that condensate cannot be directly reused in static layering like aromatic hydrocarbons, dehydration takes the distillation route, and the recovery configuration is a combination of condensation and distillation.
The recovery economy of isopropanol is strongly related to the water content of the incoming gas: the working condition with less water in the incoming gas, the concentration of condensate is high, the distillation load is small, and the recovery cost is controllable.
The boiling point of isopropanol determines that most of the condensation between normal temperature and frozen water can be recovered: primary normal temperature pre-cooling, secondary frozen water temperature level ending, discharge control section series adsorption treatment residue. The condensate is divided into two ways according to the concentration detection: the high concentration is directly dehydrated by distillation, and the low concentration is mixed in batches and used in the process that is not sensitive to moisture. The scale of the distillation tower is calculated according to the amount of condensate and the target purity, and the waste water from the tower kettle is measured and then enters the sewage system, and the accounts are closed.
The load calculation of the condensing section is based on the measured intake air volume and concentration: the exhaust air of the cleaning process is intermittent, with large difference between the peak and the average value. The main body of the device is selected according to the median load, and the peak is undertaken by the buffer and check sections. The efficiency of investment and the stability of operation are both accounted.
Isopropyl alcohol and water do not form azeotrope, and high concentration extraction can be obtained by ordinary rectification, which is more convenient than ethanol recovery: high concentration isopropyl alcohol is extracted from the top of the tower for reuse, and the water phase in the bottom of the tower is processed after reaching the standard. The energy consumption management of distillation depends on the reflux ratio and feed preheating: the feed and the discharge of the tower kettle are preheated by heat exchange, the reflux ratio is adjusted according to the target purity, and the two items are done well, and the unit energy consumption of the rectification section is reduced. The operating parameters of the tower are recorded shift by shift, and after the correspondence between purity and energy consumption is found out, the management of operating costs has a grip.
The management of the water phase in the tower kettle does not leak accounts: after the solvent content reaches the standard, it will enter the sewage system, and if it exceeds the standard, it will be treated with reflux or load reduction. There will be two accounts for measurement and detection, and the environmental protection account and the solvent loss account will be matched.
The long-term operation of the distillation tower also has to focus on two points: the packing state in the tower and the heat exchange surface of the reboiler, the pressure difference trend and the purity of the tower top are their windows-the slow rise of the pressure difference is accompanied by purity fluctuations, most of which are signals of packing fouling or changes in feed water quality, and cleaning is arranged according to the trend, and unequal problems are concentrated.
| Segment | Features | Configuration Schedule |
|---|---|---|
| Primary precooling | Recovery part of normal temperature section | Cooling before entering the condensing unit |
| secondary condensation | Freezing Water Temperature End | Temperature level calculated by dew point |
| condensate shunt | Large difference in concentration | Grading detection is processed separately |
| distillation dewatering | non-azeotropic ordinary distillation | High-concentration extraction and reuse at the top of the tower |
| tower kettle wastewater | Trace solvent | Sewage after detection and measurement |
| Discharge gate | low concentration residue | adsorption series treatment |
Classification: The high-purity liquid recovered from rectification can be recycled for cleaning after reaching the standard. Batches directly blended with condensate are used in processes with loose purity requirements. The particle and metal impurity index of cleaning liquid shall be tested separately, and then work after reaching the standard.
General ledger: with more water, distillation energy consumption will increase, but the unit price of isopropanol is high, and recovery under most working conditions is still cost-effective. In the scheme stage, the measured intake water volume and distillation load are calculated, and the proportion of energy consumption is determined by the allocation scale.
First metering and then entering: after the solvent content of the water phase of the tower kettle reaches the standard, it will enter the sewage system, and the excessive reflux or load reduction treatment will be carried out. There are two accounts for measurement and testing, and the environmental protection account is in line with the solvent loss account.
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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