Fractional heat recovery

The fractional heat recovery rj is defined as the ratio of the actual temperature rise of the gas (or of the solids) to that for complete heat transfer between the gas and the solids, that is, according to Fig. 10... 

Fig. 43. Number of heat-transfer stages and fractional heat recovery in dilute-phase heat transfer for particles under accelerative motion.

An Ecoprofile is an assessment of the environmental and resource impacts of a waste disposal process. This paper describes ecoprofiles for six different ways of disposing the plastic fraction in municipal solid waste -two material recycling processes that include separation of the plastic waste, material recycling without separation of the plastic waste, pyrolysis, incineration with heat recovery, and landfill. 17 refs. 

In a methanol plant (Figure 4.3), the synthesis gas passes from the reformer furnace to a heat recovery section where it is cooled to room temperature. The synthesis gas is then compressed to 750 to 1,500 psia (5,170 to 10,345 kPa) and fed to the converter vessel through preheat exchangers. Methanol is formed as the gas passes over catalyst beds in the converter vessel at 400 to 600° F (205 to 315 C). The methanol product is then cooled and fed to separators and then to fractionators to complete the purification. 

The Uhde reformer is top-fired and has a proprietary "cold" outlet manifold system to enhance reliability. Heat recovery utilizes process heat for high-pressure steam generation, feed preheat and for heat required in the fractionation section. 

In soybean plants using hot dehulhng, the cracked soybeans are shocked by hot air to aid in the separation of the hull fraction from the meats fraction. The hot air conditioner uses either a hot air fluidized bed to heat and convey or hot air spouting to heat and a belt to convey. The hot air is partially recirculated for heat recovery. Hot air conditioners for soybean plants are provided by Buhler of Switzerland, Crown Iron Works of the United States, and Escher Wyss of Germany. 

All commercially available fractionation processes can give comparable performances. Basically, each process uses a deaerator, heat source, fractionation column, condensing system, and vacuum source. These processes may differ in the internals of the column, in the manner of evaporation and condensation, and in the piping arrangement for better heat recovery, but they can give equally good results. 

In a typical thermofor catalytic cracking unit, the preheated feedstock flows by gravity through the catalytic reactor bed. The vapors are separated from the catalyst and sent to a fractionating tower. The spent catalyst is regenerated, cooled, and recycled. The flue gas from regeneration is sent to a carbon monoxide boiler for heat recovery. 

Adsorbed and entrained vapors are removed from the retorted shale by steam in the spent shale stripper. Stripped shale is sent to the heat recovery section. The overhead products from the spent shale stripper are combined with the retort vapors and are further superheated with steam to reduce condensation coking and quenched with fractionator bottoms in a quench tower. 

Burner infegrated heat recovery implies that flue gases are basically extracfed from fhe burner however, a fraction of flue gases, possibly... 

Direct-contact condensers (Fig. 15.14f). These are used for minimizing pressure drop in vacuum condensation. To accomplish this, the direct-contact zone contains low-pressure-drop internals such as packings, or is a spray chamber. Another common application is intermediate heat removal ("pumparounds ) in refinery fractionators. Here the main purpose is to maximize heat recovery at the highest possible temperature levels. A third common application is intermediate heat removal from absorbers or reactive distillation columns in which an exothermic reaction takes places. In all these applications, condensation... 

Understand Process Characteristics H2, H2S, and NH3 and light ends are removed from reaction effluents through a series of separation and flashes, resulting in the reaction products in a liquid form, which goes to the stripper, the feed heater, and then to the main product fractionator. The task of the product fractionation is to separate different products based on their product specihcations such as distillation endpoint, ASTM D-86 T90% or T95% point, and so on. Side draws from the column go to the product strippers where kerosene and diesel products are made. The net draw from the column bottom is called unconverted oil (UCO), which is recycled back to the reaction section for nearly complete conversion. There are two pump-arounds, namely, kerosene and diesel pumparounds, as a main feature of heat recovery from the main fractionation column. 

A heat exchanger network is a combination of several heat exchangers interconnected. Figure 7.3 shows a typical example of the heat exchanger network where feed is preheated by several process streams before being heated by a furnace to a desirable temperature required for fractionation. The terminal temperature of the exchanger network (7 ) is the same as the furnace inlet temperature (FIT). Clearly, the network terminal temperature represents collective heat recovery by individual heat exchangers in the network. 

What sections should be included in the boundary In general, a process includes feed preparation, reaction, fractionation and separation, heat recovery, and product delivery sections. To avoid suboptimal solutions for AT , these sections should be included when determining ATmin opt-... 

Let us see the effect on total cost. If the heat recovery system for reaction and fractionation sections are designed separately, ATuun opt will be at around 60 °F for the reaction section resulting in the total annualized cost at around 13MM/year... 

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