Treatment and Recovery Technology of Dibromopropane Waste Gas

1,2-Dibromopropane is a colorless to yellow liquid. The melting point is -55.2 ℃, the boiling point is 140~142 ℃, and the saturated vapor pressure is 1.33kPa (35.7 ℃). Insoluble in water, miscible in ethanol, ether, acetone, chloroform.

Dibromopropane has a high boiling point and is prone to volatilization during industrial production and application, causing environmental pollution. The commonly used processes for treating dibromopropane waste gas include low-temperature condensation, incineration, and activated carbon adsorption.

The low-temperature condensation method is a process that utilizes the relationship between the saturated vapor pressure of dibromopropane and the decrease in temperature, reducing the temperature to below zero degrees and allowing it to liquefy as much as possible from gaseous dibromopropane. This process has a good recovery effect on high concentration dibromopropane waste gas, but incomplete condensation still results in high concentration waste gas emissions, making it difficult to achieve standard emissions.

Incineration method is a commonly used low concentration exhaust gas treatment process, commonly known as RTO (Regenerative Combustion), which decomposes dibromopropane at high temperatures. After combustion, acidic gases are generally formed, which have a significant impact on the service life of RTO equipment and are prone to form dioxin like pollutants. Due to various reasons, the practical application of this process is very limited.

Activated carbon adsorption method is a process that utilizes the adsorption properties of activated carbon to adsorb dibromopropane from exhaust gas, and then recovers dibromopropane through steam blowing. The adsorption effect of activated carbon in this process is greatly affected by moisture, and the adsorption performance decreases significantly after multiple blow off regenerations; And dibromopropane is easily catalyzed and decomposed by impurities in activated carbon, producing acidic gases. When it comes into contact with water, it becomes acidic and severely corrodes equipment, shortening the service life of pipeline equipment.

In response to the current problems in the treatment of dibromopropane waste gas, Jiangsu Haipu Functional Materials Co., Ltd. has developed HDV type polymer nano adsorbent, which can adsorb and remove dibromopropane from waste gas. After adsorption saturation, the nano adsorbent is desorbed and regenerated using steam, and dibromopropane steam can be condensed and recovered. The specific process is as follows:

The specific process is as follows: the waste gas of dibromopropane in the workshop is first extracted by the induced draft fan and then subjected to secondary condensation. The temperature of the first stage condensation is around 25 ℃, and the temperature of the second stage condensation is around 10 ℃. The condensed and liquefied dibromopropane is received in a storage tank, and the uncondensed dibromopropane waste gas is connected to an adsorption tower containing nano adsorbents for adsorption enrichment (adsorption temperature at room temperature, adsorption pressure at~2kpa). After adsorption, the waste gas can be discharged in compliance with standards. After the adsorbent is saturated, low-pressure steam is introduced into the adsorption tower for stripping (at a temperature of around 100 ℃). The mixture of blown dibromopropane and water vapor can be separated and recovered by condensation liquefaction, settling and layering. The temperature of the nano adsorbent after steam desorption is relatively high. After cooling to room temperature with clean air, it can be reused for adsorption. The adsorption tower is usually configured with 3 units, 2 for adsorption and 1 for desorption as a backup. The actual engineering application effect is very good.

This process can achieve a removal rate of over 99% for dibromopropane in exhaust gas and meet emission standards.

Advantages of HDV type nano adsorbent:

(1) Controllable pore structure and high pore volume;

(2) Has good physical and chemical stability, is resistant to acid, alkali, and organic solvents, has high thermal stability and mechanical strength, and is wear-resistant;

(3) The surface exhibits high hydrophobicity, and humidity has no effect on adsorption performance;

(4) Easy to regenerate and stable adsorption performance;

(5) No hazardous waste is generated without the need for replacement.