I would like to ask about the differences between the quench cooler, quench oil tower, and quench water tower in an ethylene plant
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I would like to ask about the differences between the quench cooler, quench oil tower, and quench water tower in an ethylene plant. My understanding is that the quench cooler of the cracking furnace is a heat exchanger, where the oil and gas do not come into contact with the quench water; whereas in the quench oil tower and quench water tower, the quench oil and quench water come into direct contact with the oil and gas, and then they are separated using an oil-water separator, is that correct? I would like to ask the experts here
After leaving the reactor, the pyrolysis gas is cooled in a waste heat boiler to a temperature of around 400–500°C. It is then cooled further in a quench tank, where the quench oil comes into direct contact with the pyrolysis gas, reducing its temperature to about 200°C before it enters the quench oil tower.
The quench cooler is actually a mixer, with the quench oil mixing directly with the pyrolysis gas to rapidly lower its temperature. The quench oil tower serves both cooling and fractionation purposes. In its lower section, quench oil is used to remove heat and separate heavy components through counter-current contact with the pyrolyzer, while in its upper section, gasoline is used as a reflux stream; this not only lowers the temperature of the pyrolysis gases but also helps to separate light fuel oils. In the quench tower, the quench water comes into countercurrent contact with the pyrolysis gas to cool it down, causing heavy gasoline and dilution steam to condense into water and be separated out.
The quench cooler is essentially a mixer that uses quench oil sprayed directly to lower the temperature of the pyrolysis gas. The quench oil tower can also be referred to as an oil washing tower or a gasoline fractionation tower; it utilizes quench oil, oil circulation, and gasoline reflux to separate the heavier components in the pyrolysis gas that are above the diesel range, while also recovering heat. The quench water tower can be called a water washing tower as well; it uses circulating quench water to separate water and gasoline from the pyrolysis gas, thereby recovering low-grade heat
For a quench oil tower equipped with mid-stage reflux, what is the effect of extracting side-stream cracked diesel on the top temperature and bottom temperature of the quench oil tower? What is the reason for this?
With all other conditions remaining constant, the more diesel fuel that is recovered through cracking, the fewer light components there will be in the quench tower; as a result, the temperature at the top of the tower decreases while the temperature in the reactor increases, mainly because the components within the tower become heavier
The quench heat exchanger is used to generate high-pressure steam and reduce the temperature of the pyrolysis gas. Quickly terminate the reaction. Prevent the occurrence of secondary reactions. A quencher uses quench oil to directly mix with and cool the material coming out of the quench heat exchanger. An oil cooling tower is a gasoline distillation tower. The gasoline fraction is separated from the top of the tower. Diesel is taken out from the middle, while fuel oil is taken out from the bottom of the tower or the viscosity-reduction tower. A water cooling tower is used to condense the diluted steam.
The pyrolysis gas exits the radiation section and first passes through a quenching boiler, where ultra-high pressure steam is generated; the temperature is then reduced to 400 degrees before the gas enters a quencher. Here, quenching oil mixes with the pyrolysis gas to lower its temperature to 200 degrees, after which it enters an oil-cooling tower. The temperature at the top of this tower is 105 degrees, while the temperature at the bottom depends on the density of the pyrolysis feedstock. The gas then proceeds to a water-cooling tower, where the temperature at the bottom is around 85 degrees and the temperature at the top is around 40 degrees
The pyrolysis gas is directly cooled to 250°C using quench oil before entering the quench oil tower; the purpose of this is (). A. Reduce the cost of the pyrolysis gas transmission line B. Improve heat recovery efficiency C. Prevent coking in the pyrolysis gas transmission line
The function of the quench oil tower is to receive the pyrolysis gas coming from the pyrolyzer, and to cool it gradually through the quench oil section, the oil coiling section, and the gasoline section within the tower. At the same time, the heat from the pyrolysis gas is recovered through the quench oil circulation and oil coiling circulation, and this heat is used to generate dilution steam or to heat other process fluids. The function of the quench water tower is to cool the pyrolysis gas coming from the quench oil tower by bringing it into contact with quench water reflux; this process simultaneously condenses the heavier components in the pyrolysis gas, allowing the lighter components to be sent on to the pyrolysis gas compressor system