I need help with several questions regarding the pyrolysis gas quench tower!
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In industrial quenching systems, there are quenching heat exchangers and quenching towers; what is the situation with quenching towers, which use water as the quenching agent? Since the temperature of the pyrolysis gas coming out of the quench heat exchanger is still around 600 degrees, if it is sent directly into the quench tower for direct cooling with water, wouldn’t that amount of heat be wasted? What if the quench tower is replaced with a waste heat boiler? Thank you!
Pyrolysis gas is a mixture of substances produced as a result of the reaction; rapid cooling is employed to ensure a high content of the desired products within the pyrolysis products, thereby yielding a high yield of those desired products. If it is replaced with a waste heat boiler, the temperature of the pyrolysis gas will not be able to drop to the desired level, allowing further reactions to occur; as a result, the concentration of the desired components in the pyrolysis gas decreases, leading to a lower yield of the product.
Hello, I first cool the pyrolysis gas using an emergency cooling indirect heat exchanger to below 600 degrees; at this temperature, the polymerization reaction and some of the pyrolysis reactions should have come to an end. Then, the pyrolysis gas is further cooled in an emergency cooling tower. I was thinking of using water for direct spraying to achieve cooling – how would that work? (In my simulations, the temperature of the pyrolysis gas dropped to around 80 degrees right away.) How is it done in industry?
In industrial applications where rapid cooling of pyrolysis gas is required, water spraying is commonly used for cooling (the pyrolysis gas must be insoluble in water)； After cooling the temperature below 600, a heat exchanger is used for further cooling; the cooling rate is slower than that achieved by water spraying, and more area and volume of heat exchange equipment are required ； Therefore, water spraying is used for cooling, taking advantage of the latent heat of vaporization of water to lower the temperature. This method offers a fast cooling rate and good results, enabling effective reduction of further reactions of the pyrolysis gas.
Hello, I have the process simulated using Aspen here. Please take a look and let me know if there are any changes needed. Also, after passing through the initial distillation column, the temperature at the top of the column is -21 degrees, while the gas phase fraction remains 1. I’m not sure why this is happening. Later on, I plan to use compression and flashing to remove C6+, but liquid will only be produced at normal temperature when the pressure reaches 2 MPa. I checked the physical properties of the components, and at atmospheric pressure, the boiling points of some of these components are only around 100 degrees. I’m not sure what’s going on; I’d appreciate your advice!
The purpose of rapid cooling is to prevent the formation of dioxins