How to recycle styrene waste gas? Condensation recovery configuration of polymerization and storage and transportation links

The amount of styrene in the resin, rubber and coating industry is not small, but its exhaust characteristics are easy to be ignored: the boiling point is moderate, there is obvious volatilization at room temperature, and it is easy to polymerize when heated or in contact with impurities. Styrene vapor will be brought out from the storage tank breathing, loading and exhausting of the polymerization kettle. If only simple collection and discharging are done, materials will be lost and the burden of back-end management will become heavier. The recovery of styrene waste gas should consider both recovery efficiency and polymerization risk.

Gas Source Characteristics and Recovery Route

The size and respiration of atmospheric storage tanks are intermittent emissions, and the concentration changes with temperature and liquid level. Exhaust in loading process is concentrated and large in short time. The exhaust of polymerization or reaction kettle may bring mist and a small amount of polymer particles. The common point of these types of gas sources is that the components are relatively single. The mainstream practice is to first condense and liquefy the recovery, and then further process the residual low concentration exhaust gas. Since the boiling point of styrene is not very low, conventional refrigerants can generally meet most of the liquefaction requirements. Whether to add cryogenic cooling depends on the exhaust gas concentration and the actual recovery target, and it is not necessary to add cryogenic cooling.

Configuration steps

1. Measure the exhaust concentration and temperature separately by point, distinguish between continuous and intermittent sources, and do not combine the two types of gas sources simply.
2. Do airtight collection in the storage tank area to reduce the dilution of air source by unorganized emission.
3. Determine the condensation temperature level according to the components, and set the condensate intermediate tank behind the condenser and leave the sampling port.
4. For the air source with particles, separate or filter before entering the condensation section to avoid fouling on the heat exchange surface.
5. The recovered condensate is returned to production or centralized processing according to quality, and the recovered amount is included in the material ledger for reconciliation.

How to prevent self-gathering risks

Exhaust comparison of different links

Comparison item	Tank Size Breathing	Loading exhaust	Reaction kettle exhaust
Emission mode	Intermittent, liquid level changes with temperature	Concentrated, short-term flow	Fluctuation with lot
Component characteristics	Single, low concentration	High concentration with few droplets	Possible mist and particles
Configuration focus	Closed collection and anti-dilution	Load adaptation and condensate discharge	Front-end separation and anti-scaling

Styrene is easy to polymerize when heated, exposed to light or in contact with impurities. Once the polymer adheres to the pipeline and heat exchange surface, cleaning will be very troublesome. The control method is mainly to compress the high-temperature residence time: the exhaust gas passes through the high-temperature section as soon as possible, the condensate is discharged in time and does not stay in the tank for a long time, and the pipeline avoids long-distance dead corners and low-point effusion. Condensate intermediate tank to maintain the appropriate temperature range and do a good job of liquid phase protection, than simply rely on heating more secure. When the process requires the addition of polymerization inhibition components, the method of addition should be consistent with the process of the user.

Concerns in operation

The condensation outlet temperature and the amount of condensate are the two most direct observation indicators, and the simultaneous decline of both usually indicates that the heat exchange surface is fouled or the cooling capacity is reduced. The collection effect of the tank area is assisted by the odor and pressure state around the tank area, which is more intuitive than just looking at the instrument. The quality of the recovered condensate should be analyzed regularly. When the moisture content or added components change, the reuse method needs to be reconfirmed.

Information to be confirmed before configuration

The air volume, concentration, temperature and daily emission period of each point are clearly sorted out, and the total load is estimated in combination with the volume of the storage tank and the loading frequency, so that the scale of the device is not easy to deviate too much.