Vacuum pump exhaust in vacuum distillation, vacuum drying and decompression evaporation processes is an invisible large source of solvent loss: the pump pumps the solvent vapor away together while vacuuming. If the exhaust port is directly discharged, the solvent will escape with the exhaust air, and the recovered book gap is often here. The condensation recovery of the exhaust gas of the vacuum pump is to stop the road that has run away: the exhaust gas is collected centrally, cooled and condensed, the solvent is returned to the tank, and the exhaust gas is checked again, thus making up the book gap of the loss.
Vacuum pump tail gas has three characteristics: high concentration-high partial pressure of solvent in the pump cavity and close to saturation of exhaust gas, which is the type with the highest concentration in each tail gas; Liquid-pump outlet exhaust entrains pump working fluid and condensate, with large moisture content; Temperature and pressure fluctuate with working conditions-vacuum degree and evaporation amount change at different stages of distillation, and exhaust load changes accordingly. Configuration according to the principle of high concentration priority separate manifold, not mixed with the workshop low concentration tail gas, mixed discharge will dilute the high concentration stock, condensation yield but decreased.
The collection starts from the pump outlet: the exhaust port is equipped with a gas-liquid separator to separate and reuse the entrained liquid first; the separated exhaust gas is introduced into the recovery main pipe through a check valve. When multiple pumps share the main pipe, each branch is equipped with an isolation valve, so that maintenance will not affect each other. The main pipe slopes to the condensate tank along the course, with a drain port at the low point; the pipe diameter is calculated according to the pump full load superposition, leaving a working condition fluctuation margin. Different types of vacuum pumps have different exhaust characteristics: the water ring pump has a lot of water in the exhaust, the dry pump has a dry exhaust, and the manifold design is calculated separately according to the pump type, not according to one mode. There are also several key points in construction and acceptance: air tightness test shall be conducted after welding of main pipes, and leakage points of flanges and valves shall be checked one by one; After the manifold is completed, each pump shall be tested one by one to check the actions of the branch isolation valve and check valve. After the system is put into operation, the exhaust volume of each pump running separately and superimposed operation shall be measured one round each, and compared with the calculated value to find out the reason for the pipe section with large deviation. The effect of the collection system is half in the design and half in the construction and acceptance, and the later operation and management is relieved.
The condensation yield of high-concentration tail gas is high. Conventional two-stage condensation: the first-stage normal temperature condensation recovers the big head, the second-stage low-temperature condensation presses down the remaining steam, and the condensed exhaust gas enters the control section to meet the discharge standard. Pay attention to frosting management with wet tail gas, and defrost is arranged according to pressure difference trend. Condensate is classified according to source: condensate from distillation process has high purity and is directly remixed after detection; Condensate mixed with impurities is used according to quality degradation. The condensing load is calculated according to the maximum exhaust condition of the pump, and the buffer volume is set to cut the peak under the condition of large fluctuation.
| Segment | Features | Configuration Schedule |
|---|---|---|
| Pump outlet | High concentration of belt liquid | Gas-liquid separator first |
| Manhole | Multi-pump sharing | Branch isolation plus check |
| Condensation | High concentration and high yield | Two-stage condensation control section |
| Condensate | Large qualitative differences | Tank collection, inspection and reallocation |
| defrosting | With wet and easy frosting | Differential Pressure Trend schedule |
| Reconciliation | Invisible loss | Check the feeding by month |
The condensing section has certain resistance. During configuration, the pipe diameter and the pressure drop of the heat exchanger shall be calculated according to the allowable back pressure of the pump. The standard configuration will not affect the vacuum process. In case of abnormal pressure difference during operation, check whether the condensing section is blocked first.
Yes, the utilization rate of equipment can be improved by sharing, but isolation valves and check valves shall be set up for each branch, so that maintenance and working condition differences do not interfere with each other. The total load shall be calculated according to the superimposed peak value, leaving fluctuation allowance.
The condensate of the water ring pump has high water content, which shall be determined according to the quality inspection, and shall be degraded or incorporated into dilute liquid for treatment. The pump working fluid shall be replaced regularly to reduce the cross-influence on the condensate, and the ledger shall be recorded separately.
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.
Mr. Li 13526990215
Hotline
