How to set the condensation temperature of the solvent recovery unit? Direct answer: According to the target concentration of tail gas and the dew point of the components, not the lower the better-the conventional practice is to calculate the dew point interval of the mixed gas according to the target emission concentration, and then leave a safety margin down; every time the temperature goes down, the refrigeration energy consumption rises non-linearly, and the risk of heat exchange surface frosting and high boiling point component condensation and blocking also follows. After the set value is put into operation, it shall be adjusted back according to the measured emission concentration. If there is a difference between the drawing calculation and the running in the device, the measured correction shall be calculated as the final version. In this paper, the setting logic, component differences and callback methods are clarified for the reference of process and operation and maintenance personnel.
The dew point of the mixed gas is determined by the components and partial pressure: the lower the target concentration, the lower the corresponding dew point temperature. The device must press the air temperature below the dew point and leave the supercooling degree to continue to condense the components. The multi-component system should be calculated separately-the light component should have a lower temperature, and the heavy component should be condensed at a higher temperature. For a two-stage condensation device, the first stage is set according to the heavy component recovery and the second stage is set according to the light component and the target concentration. Only when the inter-stage connection is smooth can there be a balance between energy consumption and recovery rate. If the calculation is inaccurate, it shall be calculated according to the physical property data of the medium, or the operating value of similar devices shall be used as the starting point, and then corrected according to the actual measurement after operation. The starting point data is only responsible for making the device produce the first qualified products.
The temperature goes deeper, and the cost is three layers: the refrigeration energy consumption rises nonlinearly, and the electricity bill will soon be visible; The heat exchange surface frosts, and the frost layer in turn deteriorates the heat exchange, falling into a cycle of colder and colder, more and colder. High boiling point components and wax precipitate, condense and block pipelines and valves, and the cleaning frequency increases. Therefore, the set temperature pursues a reasonable low temperature under the premise of reaching the standard, not the extreme low temperature-a device with sufficient emission margin. If the temperature is adjusted back several degrees, the electricity charge will be lowered, and the recovery rate will hardly move. Many devices in this account have not been calculated.
Different solvent systems have different temperature strategies: toluene with high boiling point can get good recovery rate at a higher temperature, and the set value need not be radical; Methanol and acetone with low boiling point have low dew point and require deep temperature. Condensation alone is often uneconomical, and the combination of membrane separation or adsorption check is more reasonable. The water-bearing system should also be ice-proof and blocked, and the temperature should be considered together with dehydration configuration. In a system with large fluctuations in medium composition, the temperature is adjusted along with the feed concentration, and the fixed value is not pleasing at both ends.
| Medium | boiling point characteristics | Temperature Strategy |
|---|---|---|
| toluene aromatics | High boiling point and easy to condense | Temperature position need not be radical |
| Methanol Acetone | Low boiling point Low dew point | Combined membrane or adsorption check |
| Esters | medium boiling point | Conventional two-stage condensation can be |
| aqueous system | Ice Blocking Risk | Temperature and dehydration matching |
| multi-component mixing | Dew point interval width | Graded set temperature segment recovery |
| Large fluctuation of concentration | Unstable working condition | Linkage regulation with feed |
The common caliber is to leave a section according to dew point to deal with concentration fluctuation, and the amplitude is related to the requirements of medium and residual amount. After putting into operation, it is revised according to the measured emission data, and the paper value is only used as the starting point but not as the end point.
Looking at the medium: for systems with a high proportion of light components, the yield of the condensation section is inherently limited, and the standard and multiple collection depend on the combined process. If the medium is dominated by recombination, it is not normal. Check the heat exchange efficiency and inter-stage working conditions.
The error is directly offset setting and interlocking, the virtual low temperature leads to waste of energy consumption, and the virtual high temperature leads to emission fluctuation. Calibrate according to cycle, and the calibration record is saved with the device file, which is the basic item of operation management.
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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