Quench tower

Tower Internals and Equipment Modification. Tower capacity expansion can be achieved through the use of random or stmctured packing, or through the use of higher capacity trays such as the UOP multiple downcomer tray. Packing has been used in the gasoline fractionator, water quench tower, caustic and amine towers, demethanizer, the upper zone of the deethanizer, debutanizer, and condensate strippers. Packing reduces the pressure drop and increases the capacity. 

The coke is taken to a quench tower, where it is cooled with a water spray or by circulating an inert gas (e.g., nitrogen), a process known as dry quenching. The coke is then screened and sent to a blast furnace or to storage. 

In a typical gas oil design, the lighter products overhead from the quench tower/primary fractionator are compressed to 210 psi, and cooled to about 100°F. Some Q plus material is recovered from the compressor knockout drums. The gases are ethanolamine and caustic washed to remove acid gases sulfur compounds and carbon dioxide, and then desiccant dried to remove last traces of water. This is to prevent ice and hydrate formation in the low temperamre section downstream. 

A typical ethane cracker has several identical pyrolysis furnaces in which fresh ethane feed and recycled ethane are cracked with steam as a diluent. Figure 3-12 is a block diagram for ethylene from ethane. The outlet temperature is usually in the 800°C range. The furnace effluent is quenched in a heat exchanger and further cooled by direct contact in a water quench tower where steam is condensed and recycled to the pyrolysis furnace. After the cracked gas is treated to remove acid gases, hydrogen and methane are separated from the pyrolysis products in the demethanizer. The effluent is then treated to remove acetylene, and ethylene is separated from ethane and heavier in the ethylene fractionator. The bottom fraction is separated in the deethanizer into ethane and fraction. Ethane is then recycled to the pyrolysis furnace. 

In the production of dichloroethane (EDC) by oxyhydrochlorination of ethylene, the products from the reaction are quenched by direct contact with dilute HC1 in a quench tower. The gaseous stream from this quench tower is fed to a condenser and the uncondensed vapours recycled to the reactor. A typical composition for this stream is shown in the diagram below operating pressure 4 bar. Calculate the outlet stream compositions leaving the condenser. 

Quench pools/catch tanks and quench towers... 

Quench Pools/Catch Tanks and Quench Towers Two types of quench systems are commonly used the quench pool/catch tank (also called passive scrubber) and quench tower. 

Quench tower The type shown in Fig. 23-56, with a superimposed baffle plate section, is often used when complete condensation of the incoming vapors is not required. The exiting vapors are usually cooled to 150 to 200°F in the baffle plate section. This type is often used in petroleum refineries. 

Quench tower foaming was caused by inappropriate recipes for antifoam and emulsifier additions. 

Figure 8.3 Exit gases from the furnace and quench tower of an olefin plant enter a compressor before distillation. Ice forms on the outside of the compressor even on warm days because of the cooling effect. (Courtesy of BP Chemicals, Alvin, Texas)...

Effluents from the naphtha and gas oil cracking coils are at 1300°F and 1200°F, respectively. They are combined in the line just before discharge into a quench tower that operates at 5 psig and 235°F at the top. Water is sprayed into the top of this tower. The... 

The EDC cracking is an integral part of this process. Key points in the plant design include the cracking furnaces, which utilize alloy tubes such as Inconel or Incoloy, a quench tower for lowering process tempera-... 

Because of high reactor temperatures, the hydrocarbon volatiles vaporize immediately, and are vented from the reactor to a quench tower (Item 3), where they are sprayed with cooled, recycled, heavy oil, and the larger molecules (molecules containing eight carbon atoms (C8) or more) are condensed. The condensate leaves from the bottom of the quench tower and is collected in the heavy oil receiver (Item 4). Compounds that are not condensed (i.e., light oil, C3-C7) in the quench tower enter a non-contact condenser that uses cold water The light oils, C3 to C7, are condensed and collected in the light oil receiver (Item 6). 

Solids collected in PAS filters and removed from quench towers and scrubbers... 

The cracked gas stream is cooled and purified in the primary fractionator (3) and quench water tower (5). Waste heat is recovered by a circulating oil cycle, generating dilution steam (4) and by a water cycle (5) to provide heat to reboilers and process heaters. The cracked gas from the quench tower is compressed (6) in a 4- or 5-stage compressor and dried in gas and liquid adsorbers (8). C02 and H2S are removed in a caustic-wash system located before the final compressor stage. 

Raw gas from the quench tower is compressed in a multistage centrifugal compressor (5) to greater than 500 psig. 

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