The amount of chlorine-containing solvent used in the processes of cleaning, degreasing and pharmaceutical intermediates is not small: dichloromethane and trichloroethylene in the cleaning agent and volatile gas on the degreasing tank have high recovery value, but the treatment is not a set of ideas with alcohol ester solvents. The chlorine-containing components are selective in their compatibility with the membrane material, and the tendency to hydrolyze also poses additional process constraints. The recovery of chlorine-containing system simply copy the alcohol ester scheme, light performance is not as expected, heavy membrane damage. This paper explains the treatment idea of chlorine-containing solvent tail gas, the applicable boundary of membrane separation and the key points of supporting design.
There are three particularities: first, the membrane material is compatible-rubbery organic vapor membrane has the ability to enrich most organic components, but chlorine-containing components have swelling and plasticizing effects on some membrane materials. Compatibility evaluation and small-scale test verification should be conducted before selection, and cannot be inferred only by medium table. Second, hydrolysis tendency-some chlorine-containing components decompose into acid when exposed to water, condensate system should prevent corrosion and control moisture, and material selection should be upgraded; third, the operation boundary-the reactivity of chlorine-containing components with strong alkali and active metals, and the medium residue of cleaning and maintenance operations shall be in accordance with special regulations. The three particularities determine that the chlorine-containing system should be designed separately and not mixed with alcohol esters.
The safe route of chlorine-containing tail gas is condensation-based and membrane separation check: tail gas is collected and condensed first, the large head of the high-concentration section is recovered, and the condensate is reused after dehydration detection; The uncondensed low-concentration tail gas is enriched by the membrane unit, and the enriched gas returns to the condensation inlet for circulation, and the interception side meets the standard for discharge. The role of the membrane section in the chlorine-containing system is the gatekeeper section of the closing. The parameter calibration is done separately according to the chlorine-containing component and does not share the calibration curve with the alcohol ester system. The dehumidification section is more important than the conventional configuration in the chlorine-containing system-moisture not only affects the membrane condition, but also is the source of hydrolysis acid, dew point control is strictly controlled.
The supporting design revolves around anti-corrosion and water control: corrosion-resistant materials are selected for condensate pipelines and storage tanks, and gaskets and seals are checked according to the medium; The system keeps positive pressure slightly dry to reduce moisture entry. The residual liquid purging and replacement procedures for the maintenance window are prepared separately. In monitoring, the concentration of the discharge outlet and the moisture index in the system are double online, and the load is reduced before the moisture limit is checked. The compliance caliber of waste liquid and waste gas is aligned with local requirements at the scheme stage-most chlorine-containing waste liquid is managed according to hazardous waste caliber, and the detection frequency and ledger requirements for recycling are more detailed. These constraints are written into the design input to avoid supplementary procedures after completion.
Suggestions to users: for the recovery scheme of chlorine-containing system, the medium list, moisture conditions and operating temperature level will be completed in the evaluation stage-the scheme with incomplete information will cost much more in the later stage than the evaluation time spent in the earlier stage. Don't save the compatibility test. Thousands of dollars of test fees will block hundreds of thousands of renovation risks.
| Segment | Configuration points | Attention |
|---|---|---|
| Compatibility Assessment | Small-scale verification of membrane material | not inferred from the media table |
| Process route | Condensation as the main film | Separate calibration of parameters |
| Dehumidification water control | Dew point control is strict | waterproof solution acid production |
| Material selection | Corrosion resistant material seal | Check by medium |
| Monitoring Configuration | concentration moisture double online | Reduce the load first if the limit is crossed. |
| Compliance caliber | Hazardous waste and reuse detection | Scenario Phase Alignment |
Mixed collection is not recommended. The hydrolysis and corrosion characteristics of chlorine-containing components are special, and the recovery path and detection caliber are also different. Collected in groups and treated separately, the recovery value and the life of the device are more guaranteed.
Under the premise of full compatibility evaluation and dehumidification and water control, the membrane life can be maintained at a normal level. Without verification, it will be put into use directly. The risks of swelling and acid production all point to the membrane material, and the small test link cannot be saved.
According to the batch after testing, the caliber is divided: the reuse index is reached, and the rest is entrusted for disposal according to the local hazardous waste caliber; The frequency of testing and the requirements of the ledger are strict, which is the difference between the chlorine-containing system and the conventional system.
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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