How pure can the recovered solvent be? Direct answer: there is no unified figure. the purity is determined by the single degree of components and the post-treatment link-the purity of the recovered liquid can reach more than 95% through the combined process of compression, condensation and membrane separation, and can be directly reused after simple dehydration or refining. The mixed solvent is recovered from the multi-component mixed tail gas. The purity discussion should first ask about the purpose, the mixed solvent used in this process and the raw materials that need to be fractionated and purified for sale shall be accounted for separately. The purity is not determined unilaterally by the device, and every link from collection to storage is added and subtracted. In this paper, the impact of the purity of the link and reuse check conditions.
The foundation of the collection link is fixed: the tail gas of different processes is mixed, the high boiling point and low boiling point components are mixed together, and the components of the recovered liquid are inherently mixed; Conditional workshops are collected according to the components, and the single-component system is managed separately, so the inherent condition of purity is one step higher than that of mixed collection. The upper limit of the process link: the condensation temperature and the membrane configuration determine the net, temperature fluctuations, membrane performance attenuation will make the light and heavy components cross-entrainment. The end point of the post-processing link is determined by sedimentation and water separation, filtration and impurity removal, distillation and cutting, and grading according to the target purity. Keep the results in the storage link: the cross contamination of air, water vapor and residual liquid in the tank can destroy the purity accumulated in front of the tank. Nitrogen sealing and special tank are the bottom line configuration.
Whether the recovered liquid can be directly reused shall be subject to the acceptance caliber of the following procedures: for rough washing and cleaning purposes in this procedure, the mixed solvent is usually available under the premise of controllable component fluctuation; For those used for reaction feeding and precision formula, batch testing shall be conducted according to the caliber of the raw materials, and the key indicators shall be released only when they meet the standards. There are three checks: each batch of samples is reserved to detect the main components and moisture, and the data is recorded in the ledger; The batch with fluctuation exceeding the limit is downgraded for use or rechecked after refining. Only when the detection method is consistent with the caliber of raw materials entering the factory can the data be comparable. The reuse ratio gradually climbs according to the batch data, and the risk of full-scale reuse is concentrated on the product quality side, which is not cost-effective.
When the purity is not enough, the purification path is selected according to the component relationship: if the boiling point difference of the components is large, the distillation cutting efficiency is high, which is the conventional path; Azeotropic system with water, azeotropic distillation or distillation after dehydration; If the impurity species are few and the content is low, there will be a margin for adsorption refining or membrane dehydration, and rectification is not necessary. Before the route selection, the composition of the recovered liquid should be analyzed. What are the impurities and how much they are. The analysis shows that the route naturally floats out. The process selection is based on the feeling that the process is reworked and the tuition is expensive. The inspection fee for this step is saved.
| Segment | influence | Gentry action |
|---|---|---|
| Collection sub-network | Base of composition of fixed recovery liquid | Collect by group |
| Condensation and film | Set the upper limit of net income. | Periodic measurement of parameter stability |
| Post-processing | Final purity end point | Water separation filter refined on demand |
| Tank Management | Breath and Residual Fluid Cross Contamination | Special nitrogen seal tank |
| Batch detection | Release Basis | Sample Retention Inspection Record |
| recycling ratio | Product quality risk | Stepwise climbing by data |
First-action management: network collection, special tank, batch testing three management actions with small input and quick effect; If the management is still not up to standard, the process will be moved according to the composition analysis conclusion, which is easy to waste money in reverse order.
Yes, depending on the use: the cleaning and coarse distribution of this process can be directly reused, and the value is immediate. The recovery value of single components requiring fractionation cutting is calculated according to fractionation cost. Systems with large quantity and stable components are usually cost-effective.
The following acceptance caliber shall prevail, and there are three conventional samples: main component content, moisture content and impurity spectrum; Sensitive indexes such as acidity and chromaticity used for reaction feeding are measured. Only when the test items are aligned with the caliber of the supplier's raw materials can the data have decision-making value.
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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