Cooler absorbers

Cooler Absorbers When the absorption of a gas is accompanied by the evolution of heat, an important function of the absorption equipment is the removal of the heat generated. This may be accomplished by using a number of towers in series, the liquid from each tower being circulated through an external cooler. There are different types of cooler-absorbers in which processes of this type can be carried out in a single unit. The materials of which these cooler-absorbers are constructed should be of high thermal conductivity and resistant to corrosion by the substances used in the process. As an example, in the manufacture of hydrochloric acid of the... 

Figure 9-88 illustrates a falling film type absorber using water jacketed tubes in the cooler-absorber. The tails tower removes last traces of HCl in the vents. Figure 9-89 is a preliminary selection chart for this type of unit. 

To select correct size tails tower and cooler absorber, to meet your specific requirements, follow the dotted line in the two charts. For example, using a 75% concentration of feed gas, 90 cooling water, and absorbing 2,000 Ibs./hr. HCI,- a 92 tube cooler absorber would be required in con unction with a 24" diameter tower. To produce acid over 20 Be to 22 Be, use 12-foot long tubes in ail instances where cooling water temperature falls to left of black dotted line in cooler absorber selection chart. Use 9-foot long tubes where temperature point is to the right of the dotted line. 

The objective of absorption equipment is to provide intimate contact between the liquid concerned and gas, thus facilitating the absorption process. When a large volume of gas is absorbed per unit volume of liquid, a marked rise in temperature may result and devices for the removal of the heat evolved are then an important feature of the equipment. Apart from packed towers, the types of equipment described here include agitated vessels, bubble-plate towers, cooler-absorbers and spray towers. 

Hydrochloric acid Production, purification, recovery Heat exchangers, gas coolers, absorbers, chlorine burners, strippers, thermowells ... 

A similar installation was employed by Dobratz et al. (1933), who evaluated three difieient absorption tubes in the cooler-absorber (IM-in. ID Karbate, 1-in. ID tantalum, and 0.88-in. ID stainless steel) and investigated the production of 36 to 40% hydrochloric acid solutions. Hiese authors presort complete data, including heat-transfo and absorption-coefficient correlations for the cooler-absorber, but give no data on the performance of their 4-in. by 4-ft packed tail-gas scrubbing tower. 

Fig. 1. A typical process flowsheet for acrolein manufacture. A, Fixed-bed or fluid-bed reactor B, quench cooler C, absorber D, stripper E and F,...

Because this reaction is highly exothermic, the equiUbrium flame temperature for the adiabatic reaction with stoichiometric proportions of hydrogen and chlorine can reach temperatures up to 2490°C where the equiUbrium mixture contains 4.2% free chlorine by volume. This free hydrogen and chlorine is completely converted by rapidly cooling the reaction mixture to 200°C. Thus, by properly controlling the feed gas mixture, a burner gas containing over 99% HCl can be produced. The gas formed in the combustion chamber then flows through an absorber/cooler to produce 30—32% acid. The HCl produced by this process is known as burner acid. 

Commercially, the burner chamber and the absorber cooler sections are combined as a single unit for small-scale production. However, in large capacity plants, these units are separated. A typical commercial unit is schematically described in Figure 5 (32). 

Dual-Pressure Process. Dual-pressure processes have a medium pressure (ca 0.3—0.6 MPa) front end for ammonia oxidation and a high pressure (1.1—1.5 MPa) tail end for absorption. Some older plants still use atmospheric pressure for ammonia conversion. Compared to high monopressure plants, the lower oxidation pressure improves ammonia yield and catalyst performance. Platinum losses are significantiy lower and production mns are extended by a longer catalyst life. Reduced pressure also results in weaker nitric acid condensate from the cooler condenser, which helps to improve absorber performance. Due to the spHt in operating conditions, the dual-pressure process requires a specialized stainless steel NO compressor. 

Real objects, when they are ia an environment generally hotter or cooler than themselves, radiate, absorb, and reflect energy. The portion radiated is called the emissivity S. If the portion reflected is r, then... 

A second mechanism of heat transport is illustrated by a pot of water set to boil on a stove - hotter water closest to the flame will rise to mix with cooler water near the top of the pot. Convection involves the bodily movement of the more energetic molecules in a liquid or gas. The third way, that heat energy can be transferred from one body to another, is by radiation this is the way that the sun warms the earth. The radiation flows from the sun to the earth, where some of it is absorbed, heating the surface. 

A - ABSORBER FD - FLASH DRUMS C - COMPRESSORS 1C - INTERCOOLED COMPRESSORS P- PUMP T - HYDRAULIC TURBINE D - DEHYDRATOR AC - AFTER COOLERS X- THROTTLE G GENERATOR... 

The amine cooler is typically an air-cooled, fin-fan cooler, which low-er.s the lean amine temperature before it enters the absorber. The lean amine entering the absorber should be approximately 10°F warmer than the sour gas entering the absorber. Lower amine temperatures may cause the gas to cool in the absorber and thus condense hydrocarbon liquids. Higher temperatures would increase the amine vapor pressure and thus increase amine losses to the gas. The duty for the cooler can be calculated from the lean-amine flow rate, the lean-amine temperature leaving the rich/lean exchanger and the sour-gas inlet temperature. 

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