Volume hourly space velocity

The volume hourly space velocity, in comparison with the vaporized hydrocarbon feedstock, is normally around 1600 to 2000 h for primary reforming. In high-pressure treatment (2.5 to 3.10 Pa absolute), they reach 5000 In post-combustion, which serves to reduce the quantities of residual methane in the dry gas to 0.1 to 0.3 per cent, the volume hourly space velocities range from about 2500 to 3000... 

High-temperature conversion employs catalysts based on iron oxides (80 to 95 per cent weight) and chromium (5 to 10 per cent weight) which can withstand the presence of small amounts of sulfur products without an excessive loss of activity. They operate between 300 and 450°C, and as high as 550 C, with volume hourly space velocities of 300 to 3000 h and lead to residual CO contents of 1 to 2 per cent volume. 

VHSV volume hourly space velocity, Lfee[Pg.359]

Bravo et al. [14] coated commercial CuO/ZnO/Al203 catalyst into capillaries and achieved 97% conversion at 97% carbon dioxide selectivity at a volume hourly space velocity (VHSV) of 3.91 (h which is a typical value and is comparable... 

The quantity of catalyst used for a given plant capacity is related to the Hquid hourly space velocity (LHSV), ie, the volume of Hquid hydrocarbon feed per hour per volume of catalyst. To determine the optimal LHSV for a given design, several factors are considered ethylene conversion, styrene selectivity, temperature, pressure, pressure drop, SHR, and catalyst life and cost. In most cases, the LHSV is ia the range of 0.4—0.5 h/L. It corresponds to a large quantity of catalyst, approximately 120 m or 120—160 t depending on the density of the catalyst, for a plant of 300,000 t/yr capacity. 

Both catalyst space velocity and bed geometry play a role. The gas hourly space velocity (GHSV) is used to relate the volumetric flow rate to the catalyst volume. GHSV has units of inverse hour and is defined as the volume flow rate per catalyst volume. 

GHSV (gas hourly space velocity) = (volumes of feed as gas at STP/h)/(vohime of reactor or its content of catalyst) = SCFH gas feed/fF. 

LHSV (liquid hourly space velocity) = (volume of liquid feed at 60°F/h)/(fF of reactor) = SCFH hquid feed/fF. 

Normally, catalytic reformers operate at approximately 500-525°C and 100-300 psig, and a liquid hourly space velocity range of 2-4 hr" Liquid hourly space velocity (LHSV) is an important operation parameter expressed as the volume of hydrocarbon feed per hour per unit volume of the catalyst. Operating at lower LHSV gives the feed more contact with the catalyst. 

Catalytic evaluation of the different pillared clays was performed using a microactivity test (MAT) and conditions described in detail elsewhere (5). The weight hourly space velocity (WHSV) was 14-15 the reactor temperature was 510 C. A catalyst-to-oil ratio of 3.5-3.8 was used. The chargestock s slurry oil (S.O., b.p. >354 C), light cycle oil (LCGO, 232 C < b.p. <354 C) and gasoline content were 62.7 vol%, 33.1 vol% and 4.2 vol% respectively. Conversions were on a vol% fresh feed (FF) basis and were defined as [VfVp/V ] x 100, where is the volume of feed... 

Space Velocity The volume or weight of a gas or liquid which flows through a catalyst bed or reaction zone per unit time divided by the volume or weight of catalyst. The terms liquid hourly space velocity (LHS V), and weight hourly space velocity (WHS V), are used to describe this type of flow measurement. High values correspond to short reaction times. 

Note Typically in reformer design, liquid hourly space velocity (LHSV) is defined as fresh liquid charge volumetric flow rate divided by catalyst volume. Catalyst volume includes the void fraction and is defined by WJpp( — e).]... 

The most common unit of <2rel is bed volumes per hour (BV/li). Space velocity is also used in catalytic reactors, especially in three-phase fixed-beds, and is referred to as liquid hourly space velocity (LHS V) for the liquid phase, and gas hourly space velocity (GHSV) for gas phase. As mentioned above, space-time and space velocity are measured under the entrance conditions. However, for space velocity, other conditions are frequently used (Fogler, 1999). For example, the LHSV is measured at 60 to 75 °F, and GHSV at standard temperature and pressure. 

Gas phase studies were performed at 0.1 MPa total pressure with a flow rate of loo cc/min H2 and loo cc/min He (Linde). The helium stream was diverted through a saturator containing the liquid reactant UAL (Aldrich) such that its volume fraction in the inlet to the reactor was 0.5%. The gas hourly space velocity was 120 lh g1 catalyst. Prior to reaction, the catalyst was pretreated at 673 K for at least 2 hours following a 1 K/min rise to the reduction temperature. The reactor was coaled under... 

Terpene catalytic hydrodesulfurization was performed in a pilot-plant reactor at 200°C, 1 atm. The volume of catalyst was 70 cm the liquid hourly space velocity of terpene 0.4 h"1 and the hydrogen to terpene molar ratio of 7. The catalysts were pretreated in situ in a flow of N2 at 260°C then sulfided in H2S/H2 (1 9) from 260°C to 370°C. After 5 h-on-stream, the catalysts were cooled down to the reaction temperature in H2S/H2. The hydrocarbons were analyzed by GC on a CP Wax 57 CB capillary column at 65°C and the sulfur contents were determined by microcoulometry using the ASTM D312077 norm. The... 

Where C is the wt% sulfur in product/wt% sulfur in the charge, k is the reaction rate constant, and LHSV is the liquid hourly space velocity (volume of liquid feed per hour per volume of catalyst). 

The liquid hourly space velocity is the ratio of the hourly volume flow of liquid in, say, barrels to the catalyst volume in barrels, and the reciprocal of the liquid hourly space velocity gives the contact time. Since the catalyst volume for the process will be constant, the space velocity will vary directly with the feed rate. A decrease in the liquid hourly space velocity (or, alternatively, an increase in the contact time) will usually bring about an increase in the efficiency (or extent) of the hydrodesulfurization process (Figure 5-14) (Frost and Cottingham, 1971). In order to maintain a fixed rate of hydrodesulfurization when the feed rate is increased, it may be necessary to increase the temperature. 

Since the liquid hourly space velocity is a ratio that involves the use of the volume of catalyst in the reactor, it is also possible to use the data to estimate the additional catalyst required to increase the efficiency of the process. This is especially relevant when the activity of different catalysts is to be compared, and such comparisons are only meaningful if estimations can be made of the quantities of catalyst required to obtain a predetermined performance. For example, to intimate that one catalyst is twice as active as another catalyst signifies that one unit of the first catalyst will function as efficiently as two units of the second catalyst. Such differences in catalyst performance can, however, only be deter-... 

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... 

Fluid volume Channel width Water-gas shift reaction Weight hourly space velocity... 

In most applications, the reaction occurs between a dissolved gas and a liquid-phase reactant in the presence of a solid catalyst. In some cases, the liquid is an inert medium and the reaction takes place between the dissolved gases at the solid surface. These reactors have many diverse applications in catalytic processes and are used extensively in the chemical industry. Trickle-bed reactors have been developed by the petroleum industry for hydrodesulfurization, hydrocracking, and hydrotreating of various petroleum fractions of relatively high boiling point. Under reaction conditions, the hydrocarbon feed is frequently a vapor-liquid mixture that reacts at liquid hourly space velocities (LHSV in volume of fresh feed, as liquid/volume of bed, hr) in the... 

A 1,0 mL amount of catalyst with particle size 40/60 mesh was charged to the quartz reactor. The reactor was operated at a temperature of 816 C and pressure of 300 psig with gas hourly space velocity of 7200. The volume feed ratios of C(VCH4 and H20/CH4 were 1.25 and 1.0, respectively. 

Liquid hourly space velocity (L.H.S.V.) = volumes of liquid charged per hour per gross volume of catalyst. Liquid volume has been corrected to 60°F in all cases. 

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