Feed to the process

Hydrogen lost in purge = 1554U Hydrogen feed to the process = 1554a + 269.2... 

Recycle waste streams directly. Sometimes waste can be reduced by recycling waste streams directly. If this can be done, it is clearly the simplest way to reduce waste and should be considered first. Most often, the waste streams that can be recycled directly are aqueous streams which, although contaminated, can substitute part of the freshwater feed to the process. 

Hydrocarbon solvents marketed by each manufacturer differ ia composition from those of other manufacturers, even if the specification properties are similar. This means that hydrocarbon solvents are not specified on the basis of molecular content. The composition of a hydrocarbon solvent depends on the cmde feed to the process as well as the specific process steps the solvent undergoes duriag manufacture. Because each manufacturer uses a different feed and a somewhat different manufacturiag scheme, hydrocarbon solvents differ somewhat ia thek properties, even ia situations where the solvent performs the same. 

Most treatment options for detoxifying the hazardous constituents from RCRA facilities must have a uniform feed to the process. However, the media in which hazardous constituents are located are not generally homogeneous. Thus, some form of pretreatment of the waste or waste medium will probably be required to prepare the waste for further treatment by chemical, biological or thermal means. 

However, once the controller performance is reestablished, the percentage of methane produced is recovered. On the other hand, the response of the VFA concentration along E3 is illustrated in Figure 11b. Observe that the response of the VFA at the beginning of E3 is similar to that obtained in El and E2 whereas the response becomes oscillating after pure vinasses are feed to the process. Nevertheless, there are not signs of a maintained accumulation of VFA during the experiment. 

This process seems much simpler than the Ziegler process, and you may wonder why it has not crowded Ziegler out. The problem is the olefin feed. Where do you get a ready supply of olefins the right size to feed to the process The answer is you have to malce them, and therein lies the rub. Normal paraffins from petroleum waxes or other chemical processes provide the feedstock to a two-step process, chlorination and dehydrochlorination, which produces an olefin corresponding to the paraffin. 

Perhaps the most significant advantage of using froth flotation to beneficiate fly ash is the ability to process ash that has been impounded in disposal ponds and landfills. This is advantageous for several reasons. First, it effectively de-couples ash beneficiation from ash production. There is no need for the utility to alter disposal practices or install additional ash handling equipment in order to accommodate ash processing since the feed to the processing plant... 

Feed ethylbenzene with steam If the feed to the process consists of ethylbenzene diluted with steam in the ratio 15 moles steam 1 mole ethylbenzene, determine the new fractional conversion at equilibrium a e. 

The above work concentrated most of its attention on the use of zinc chloride as the molten halide and on the use of bituminous coal extract as feed to the process. Hydrocracking of the extract (1) and regeneration by a fluidized-bed combustion technique of the spent catalyst melt (2) from the process were both demonstrated in continuous bench-scale units. 

C. Benzene (C6H6) is converted to cyclohexane (C6H12) by direct reaction with H2. The fresh feed to the process is 260 L/min of C6H6 plus 950 L/min of H2 at 100°C and 150 kPa. The single pass conversion of H2 in the reactor is 48% while the overall conversion of H2 in the process is 75%. The recycle stream contains 80% H2 and the remainder benzene (no cyclohexane). 

The effluent from the adiabatic reactor is quenched with liquid from the separator. This quenched stream is the hot-side feed to the process-to-process heat exchanger, where the cold stream is the reactor feed stream prior to the furnace. The reactor effluent is then cooled with cooling water, and the vapor (hydrogen, methane) and liquid ( benzene, toluene, diphenyl) are separated. The vapor stream from the separator is split. Part is purged from the process to remove the methane byproduct and the remainder is sent to the compressor for recycle back to the reactor. 

Makeup toluene liquid and hydrogen gas are added to both the gas and toluene recycle streams. This combined stream is the cold-side feed to the process-to-process heat exchanger. The cold-side exit stream is then heated further up to the required reactor inlet temperature in the furnace, where heat is supplied via combustion of fuel. 

A labeled flowchart of a chemical process involving reaction, product separation, and recycle is shown in Figure 4.5-1. Note the distinction between the fresh feed to the process and the feed to the reactor, which is the sum of the fresh feed and recycle stream. If some of the stream variables shown in Figure 4.5-1 were unknown, you could determine them by writing balances on the overall process and about the reactor, separator, and mixing point. 

The flowchart shown in Figure 4.7-2 for the production of ethylene oxide from ethylene illustrates this situation. The reaction is 2 C2H4 + O2 2 C2H4O. A mixture of ethylene and air constitutes the fresh feed to the process. The effluent from the reactor passes to an absorber and is contacted with a liquid solvent. All of the ethylene oxide is absorbed into the solvent. The gas stream leaving the absorber, which contains nitrogen and unreacted ethylene and oxygen, is recycled to the reactor. 

The fresh feed to the process contains hydrogen, carbon dioxide, and 0.400 mole% inerts (I). The reactor effluent passes to a condenser that removes essentially all of the methanol and water formed and none of the reactants or inerts. The latter substances are recycled to the reactor. To avoid buildup of the inerts in the system, a purge stream is withdrawn from the recycle. 

The feed to the reactor (not the fresh feed to the process) contains 28.0 mole% CO2, 70.0 mole% H2, and 2.00 moIe% inerts. The single-pass conversion of hydrogen is 60.0%. Calculate the molar flow rates and molar compositions of the fresh feed, the total feed to the reactor, the recycle stream, and the purge stream for a methanol production rate of 155 kmol CH OH/h. 

J4. An evaporation-crystallization process of the type described in Example 4.5-2 is used to obtain solid potassium sulfate from an aqueous solution of this salt. The fresh feed to the process contains 19.6 wt% K2SO4. The wet filter cake consists of solid K2SO4 crystals and a 40.0 wt% K2SO4 solution, in a ratio 10 kg crystals/kg solution. The filtrate, also a 40.0% solution, is recycled to join the fresh feed. Of the water fed to the evaporator, 45.0% is evaporated. The evaporator has a maximum capacity of 175 kg water evaporated/s. 

The feed to the reactor (not the fresh feed to the process) contains 3 moles of ethylene per mole of oxygen. The single-pass conversion of ethylene is 20%, and for every 100 moles of ethylene consumed in the reactor, 90 moles of ethylene oxide emerges in the reactor products. A multiple-unit process is used to separate the products ethylene and oxygen are recycled to the reactor, ethylene oxide is sold as a product, and carbon dioxide and water are discarded. 

The fresh feed to the process flows at a rate of60,000 kg/h and contains 25.0 mole% isobutane. 25.0% butylene, and 50.0% -buiane. which is chemically inert in this process. The fresh feed combines with three separate recycle streams, as shown in the flowchart, and the combined stream enters the reactor. Essentially all of the butylene fed to the reactor is consumed. A portion of the reactor effluent is recycled to the reactor inlet and the remainder passes to a decanter, in which the aqueous (sulfuric acid) and hydrocarbon phases are allowed to separate. ITie acid is recycled to the reactor, and the hydrocarbons pass to a distillation column. ITie overhead from the column contains iso-octane and n-butane, and the bottoms product, which is recycled to the reactor, contains only isobutane. The stream entering the reactor contains 200 moles of isobutane per mole of butylene, and 2 kg of 91 wt% H2S04(aq) per kg of hydrocarbon. ITie stream obtained by combining the fresh feed and isobutane recycle contains 5.0 moles of isobutane per mole of butylene. 

The fresh feed to the process is a mixture of A and hydrogen that is mixed with a recycle stream consisting of the same two species. The resulting mixture, which contains 3 kmol A/kmol H2, is fed to the reactor, which operates at an absolute pressure of 10.0 atm. The reaction products are in equilibrium. The effluent from the reactor is sent to a separation unit that recovers all of the S in essentially pure form. The A and hydrogen leaving the separation unit form the recycle that is mixed with fresh feed to the process. Calculate the feed rates of hydrogen and A to the process in kmol/h and the recycle stream flow rate in SCMH (standard cubic meters per hour). 

Fresh feed (pure ethanol) is blended with a recycle stream (95 mole% ethanol and 5% acetaldehyde), and the combined stream is heated and vaporized, entering the reactor at 280 C. Gases leaving the reactor are cooled to -40 C to condense the acetaldehyde and unreacted ethanol. Off-gas from the condenser is sent to a scrubber, where the uncondensed organic compounds are removed and hydrogen is recovered as a by-product. The condensate from the condenser, which is 45 mole% ethanol, is sent to a distillation column that produces a distillate containing 97 mole% acetaldehyde and a bottoms product that constitutes the recycle blended with fresh feed to the process. The production rate of the distillate is 1000 kg/h. The pressure throughout the process may be taken as 1 atm absolute. 

It is evident that we have produced one of our desired products here, nearly pure pentane. We now have to separate the near-azeotropic stream, p2. An ideal situation occurs if we can recycle it back to the liquid/liquid extractor. If its composition is close to that of the original feed to the process, we could simply mix it with the feed. Our two separation devices then would process this feed, giving us a pure pentane product and, by material balance, a second stream which is the feed but with this same amount of pentane missing. 

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