Recycle gas rate

As with hydrogen partial pressure, the recycle gas/feed ratio should be maintained at the design ratio. The actual calculation for the gas-to-oil ratio, can be defined as  

Gas-to-oil ratio recommendations vary between licensors and/or catalyst vendors but in general the minimums recommended are as follows (a) 4,000 SCFB (675 nm /m ) for amorphous catalyst systems and 5,500 SCFB (925 nm /m ) for zeolitic catalyst systems. 

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Conventional hydroforming is carried out at temperatures of 850° to 1000° F. and pressures of 150 to 300 pounds per square inch gage. Recycle gas rates normally range between 2000 and 4000 cubic feet per barrel of naphtha. Reaction periods of 2 to 12 hours are normally employed in the fixed-bed units. 

All of the pilot plant tests were made at 60 liquid volume percent per pass conversion below the recycle cut point. Temperatures were adjusted as necessary to maintain this conversion. Total pressure and recycle gas rate were held constant for all of the runs with a given feed. 

Preparation of Jet Fuel - When the Illinois H-Coal and SRC-II syncrudes are hydrotreated at severe conditions [2300 psia hydrogen partial pressure 0.5 liquid hourly space velocity (LHSV), volumes of feed per volume of catalyst per hour between 750°F and 800°F average catalyst temperature 8000 standard cubic feet per barrel (SCF/bbl) recycle gas rate], the... 

Figure 3. Hydrotreating of shale oil with ICR 106 0.6 LHSV 8000 scf/bbl recycle gas rate.

Due to its flexible nature, the same ANN architecture can be applied in which the input and output parameters based on the H-Oil units are given in Table 1. There are twenty input nodes, ten from eaeh train (A and B). They cover the fresh and recycle liquid feed rates, feed API, makeup and recycle gas rates, hydrogen partial pressure, reactor pressure, exotherm, reactor average temperature and catalyst addition rate. The model also consists nine hidden and six output nodes. However, the number of nodes in each layer or the inclusion of which process parameters can be modified as occasion arises, such as changes in process requirement, model refinement or data availability. 

Catalyst Recycle gas rate (SCFB) 500 Co-Mo/alumina 700 400 Ni-Mo/alumina 1500... 

In many processes, compressors are very expensive in capital. In revamp situations, if it is found that the new operating condition is above the choke point, changing operating pressure or reducing recycle gas rate could avoid the need to replace the compressor. 

Solvent Circulation Rate, 1193 Recycle Gas Rate, 1194 Water Disposition, 1195... 

Fresh butane mixed with recycled gas encounters freshly oxidized catalyst at the bottom of the transport-bed reactor and is oxidized to maleic anhydride and CO during its passage up the reactor. Catalyst densities (80 160 kg/m ) in the transport-bed reactor are substantially lower than the catalyst density in a typical fluidized-bed reactor (480 640 kg/m ) (109). The gas flow pattern in the riser is nearly plug flow which avoids the negative effect of backmixing on reaction selectivity. Reduced catalyst is separated from the reaction products by cyclones and is further stripped of products and reactants in a separate stripping vessel. The reduced catalyst is reoxidized in a separate fluidized-bed oxidizer where the exothermic heat of reaction is removed by steam cods. The rate of reoxidation of the VPO catalyst is slower than the rate of oxidation of butane, and consequently residence times are longer in the oxidizer than in the transport-bed reactor. 

A large quantity of hydrogen-rich separator gas is normally recycled with the feed stream. Recycle rates may vary from 2,000 to 10,000 MSCF/B. The recycle gas serves to suppress catalyst coke make but normally has relatively little direct effect on gasoline yields or catalyst requirement. However, at lower recycle levels, where an increase in recycle rate may significantly increase reactor hydrogen partial pressure, the effect is similar to a small increase in total... 

The cold gas recycle (CGR) ratio values (Figure 4) are metered values and are more consistent than the HGR and total gas recycle ratio values which were calculated from gas analyses. Although the calculated total recycle gas flow rate was erratic, catalyst bed temperatures were uniform and easily controlled by varying recycle rate and bed inlet tem-... 

Another factor that may account for the relatively higher rate of deactivation with the HGR reactor system is the entrainment in the catalyst bed of oil vapors from the hot recycle gas compressor. This occurrence was evidenced by traces of heavy oil collected downstream of the HGR reactor. Such oil vapors would tend to decompose thermally... 

First-stage reactor conditions space velocity, vol/vol hr feed gas flow rate, lb/hr recycle flow rate, lb/hr recycle molecular weight reactor temperatures, °C... 

When produced from natural gas the synthesis gas will be impure, containing up to 5 per cent inerts, mainly methane and argon. The reaction equilibrium and rate are favoured by high pressure. The conversion is low, about 15 per cent and so, after removal of the ammonia produced, the gas is recycled to the converter inlet. A typical process would consist of a converter (reactor) operating at 350 bar a refrigerated system to condense out the ammonia product from the recycle loop and compressors to compress the feed and recycle gas. A purge is taken from the recycle loop to keep the inert concentration in the recycle gas at an acceptable level. 

A breakthrough in hydro formylation was achieved with the introduction of a tri-arylphosphine-modified, in particular triphenylphosphine-modified, rhodium catalyst. [5] This innovation provided simultaneous improvements in catalyst stability, reaction rate and process selectivity. Additionally, products could be separated from catalyst under hydro formylation conditions. One variant is described as Gas Recycle (Figure 2.1) since the products are isolated from the catalyst by vaporization with a large recycle of the reactant gases. [6] The recycle gas is chilled to condense butanals. 

When the rate of rise of the bubble exceeds the velocity of the gas in the continuous phase, the gas leaving the top of the bubble is recycled and it re-enters the base. As a result, the gas in the bubble comes into contact with only those solid particles which immediately surround the bubble. Davidson 60 has analysed this problem and shown that if the inertia of the gas is neglected, the diameter dc of the cloud of recycling gas... 

Anaerobic Filter. An anaerobic filter consists of packed support media that traps biomass as well as facilitates attached growth of biomass as a biofilm (Fig. 8). Such a reactor configuration helps in the retention of suspended biomass as well as gas-liquid-solid separation. The flow of liquid can be upward or downward, and treatment occurs due to attached and suspended biomass. Treated effluent is collected at the bottom or top of the reactor for discharge and recycling. Gas produced in the media is collected underneath the bioreactor cover and transported for storage or use. Volumetric loading rates vary from 5 to 20 kg COD/m day with HRT values of 0.5-4 days. 

Naphtha transfer line Recycle gas transfer line Reheat outlet Primary reactor Secondary reactor Pressure, lb./sq. inch gage Feed rate, bbl./day Space velocity, vol./hour/vol. 

In the manufacture of methyl chloride a mixture of methane and chlorine is mixed with recycled gas and fed into a reactor. The CH4 Cl2 ratio is 4-5. The reactor temperature is maintained by regulating the gas feed rate. In methane chlorination plants, 95-96% chlorine yields and 90-92% methane yields are typical.176 All four chloromethanes are formed with a typical composition of 35 wt% methyl chloride, 45 wt% methylene dichloride, 20 wt% chloroform, and a small amount of carbon tetrachloride.178 The reaction, however, may be regulated so that either mono- or tetrachlorination predominates.177 179 180... 

In the process (Figure 9-37), the residue feed is slurried with a small amount of finely powdered additive and mixed with hydrogen and recycle gas prior to preheating. The feed mixture is routed to the liquid phase reactors. The reactors are operated in an up-flow mode and arranged in series. In a once through operation conversion rates of >95% are achieved. Typically the reaction takes place at temperatures between 440 and 480°C and pressures between 150 and 250 bar. Substantial conversion of asphaltenes, desulfurization and denitrogenation takes place at high levels of residue conversion. Temperature is controlled by a recycle gas quench system. 

Equation (3.89) is the sieve tray liquid entrainment flood gas loading equation. Equation (3.89) sets the maximum gas rate VM- At a higher Vm, excess gas-liquid froth buildup would reach the tray above and recycle liquid to it. This liquid recycle would build up to a point at which the liquid would block any vapor passage, resulting in a flooded column and costly shutdown. 

The feed is vaporized by reactor effluent heat-exchange and enters into the dehydration reactor. The dehydration reactor effluent is mixed with preheated recycle gas and enters the conversion reactors. Although Figure 10 shows four parallel or "swing conversion reactors, a lesser or greater number of reactors may be used depending upon the feed rate and regeneration frequency desired. 

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