It is difficult to deal with the condensed water produced by steam regeneration after organic waste gas is adsorbed by resin. Can it be replaced by hot nitrogen regeneration?
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It is difficult to deal with the condensed water produced by steam regeneration after organic waste gas is adsorbed by resin. Can it be replaced by hot nitrogen regeneration? What are the disadvantages?
The gas after hot nitrogen regeneration also needs to be cooled. The cooled gas and liquid phases need to be separated. The separated liquid phase can be stored and utilized, while the gas phase cannot be evacuated directly but needs to be returned to the inlet of the adsorption device. As for the cooling step, it depends on the saturated vapor pressure of the physical and chemical properties of your adsorbate. For example, if the characteristic pollutant in organic waste gas is benzene, it needs to be cooled to at least -50°C before benzene can condense. Of course, this increases the investment and operating costs of the device.
“Then it needs to be cooled to at least -50°C before benzene will condense." Sir, the liquefaction temperature of benzene is not that low. In our project, benzene is blown off with water vapor, which is also cooled by circulating water. Is there any difference between these two working conditions? Thanks
Because most of what you use for cooling with circulating water is water vapor. After the water vapor condenses, it forms liquid droplets and washes out part of the benzene in the gas, but most of the benzene is discharged with the non-condensable gas.； The tail gas is regenerated with hot nitrogen and cooled with circulating water. The benzene cannot be completely condensed. You can refer to the table below for the saturated vapor pressure of benzene series at different temperatures.
It is difficult to deal with the condensed water produced by steam regeneration after organic waste gas is adsorbed by resin. Can it be replaced by hot nitrogen regeneration? What are the disadvantages? ——Feasible - it does not need to be completely condensed, as long as it is not oversaturated after re-adsorption after condensation. ——The disadvantage is efficiency. After the steam is condensed, the water vapor washes away the solvent. Now that nitrogen is used, the desorption effect may not be good. ——Energy consumption, nitrogen has high energy consumption between heating and cooling.
If the characteristic pollutant is benzene, you cannot rely on the low-temperature condensation method to expect the exhaust gas to meet the standard. Because the freezing point of benzene is 5.5°C, if the temperature is lower than this, the system will be blocked by crystallization and cannot operate at all. It can only be processed by returning to the adsorption system after pressurization by fans to ensure that exhaust emissions meet standards.
Hot nitrogen cannot be used. The resin itself is a water-containing material, especially the resin used for waste gas, with a moisture content of nearly 60%. Hot nitrogen regeneration will take away the water, causing the resin to lose water and break, affecting its use. The best method is to pass the condensed water through the resin again, and regenerate the saturated resin with steam. This is how we are currently designing it.