The working condition of tail gas is rarely stable: the emission of batch production fluctuates with the working procedure, the gas volume of intermittent operation fluctuates from big to small, but the design of condensation and check section is done according to the stable working condition-there is a lack of one link in the middle, and the fluctuation directly hits the processing equipment. The buffer tank is the component to make up for this link: the gas volume is stored at the peak and released at the trough. The load of the treatment section is stable, and the recovery rate, emission and equipment life are all benefited.
The buffer tank is often regarded as an accessory with a tank. The selection is random and the arrangement is casual. There are many problems in the actual operation: the volume is not enough to buffer and the disturbance is amplified by the wrong position, and the drainage and condensation are not managed to pollute the system in turn. The buffer tank as a serious equipment selection management, its role can be fulfilled.
The volume of the buffer tank is determined by the amplitude and period of fluctuation, not by giving an integer: first measure or estimate the peak and mean of the gas volume, and under the condition of large fluctuation, the buffer volume is estimated by multiplying the difference between the peak and mean by the duration, and then leave a margin of 10. In the case of intermittent batch production, the gas impact at the moment of batch switching is the design point. The buffer tank flattens the peak value of the impact, and the selection of the treatment section can be taken near the average value. Instead, the main investment is saved-the money of the buffer tank is saved from the scale of the treatment section. Most of this account is cost-effective.
The pressure grade and material shall be determined according to the nature of incoming gas: normal pressure or slightly negative pressure conditions shall be selected according to the container specifications. Attention shall be paid to sealing and corrosion prevention in occasions containing solvents. Material upgrading shall be considered in advance when condensate in the tank is accumulated. The tank accessories are fully equipped at one time: the cost of the liquid level gauge, pressure gauge and discharge valve is not high. If you want to refit after commissioning, you need to re-open the hole and stop the machine. The plan stage is in place at one time, and the subsequent management is convenient.
The buffer tank is installed between the gas source side and the treatment section, and the position close to the fluctuation source has the best effect: the fluctuation comes from batch switching and is installed after the collection main pipe merges; The fluctuation comes from desorption and regeneration and is installed on the desorption gas return road. Avoid direct connection of the inlet and outlet pipelines of the tank-the intake air directly rushes to the outlet, the buffering effect is discounted, the intake pipe conducts flow in the tank, the gas phase enters and exits from the upper part of the tank, and the condensate sinks at the bottom of the tank without disturbance. The bottom of the tank is provided with a discharge port and liquid level observation. The condensate is regularly discharged and recycled to the stratified tank. After a long storage, the condensate is brought up again by the air flow, and the buffer tank becomes a secondary pollution source instead.
If multiple streams of incoming gas flow into a buffer tank, pay attention to the large difference in components and do not force the tank to be closed: incompatible condensate is mixed in the tank, layering and recycling are troublesome, and it is safer to separate buffer and remit.
| Selection item | Based on | Attention point |
|---|---|---|
| Volume | Fluctuation amplitude and period | Peak difference multiplied by duration plus margin |
| Pressure rating | Gas condition | Select by Vessel Specification |
| Location | Near the source of fluctuation | After the manifold or on the road |
| Takeover mode | Anti-straight rush | Upper inlet and outlet of gas phase in the tank |
| Deflation | Condensate accumulation | Periodic discharge recovery stratification tank |
| Sub-tank | Component difference | Separate buffer for incompatible incoming gas |
The workload is mainly based on pipeline opening and foundation construction, which is arranged at the shutdown maintenance window. The tank body is prefabricated first, and the on-site installation period is calculated in days. The opening position and basic conditions can be confirmed in the scheme stage.
The condensation in the tank of the incoming gas containing high boiling point solvent is intensified in winter, so the heat preservation or tracing depends on the working conditions; most of the normal temperature conditions can not be done. The tanks arranged outdoors in the north shall be checked for heat preservation before winter and treated together with pipeline antifreeze.
No. Excessive tank investment and land occupation are wasted, the residence time of the gas phase in the large volume tank becomes longer, and the low load period brings new problems instead. Select the type according to the actual measurement of fluctuation, leaving a margin of one.
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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