LHSV space velocity

S0 = initial number of active sites, and LHSV = space velocity. 

C and 6.9 MPa (70.3 kg/cm ) in 100% selectivity (113). The neoalcohol was also produced in selectivities of 99% by employing zirconium hydroxide catalysts (114,115). The rates of the latter process, however, are reportedly low at Hquid hourly space velocity (LHSV) of <1 kg/catalyst-h. A catalyst from... 

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. 

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

ALLreviations reactors Latch (B), continuous stirred tank (CST), fixed Led of catalyst (FB), fluidized Led of catalyst (FL), furnace (Furn.), multituLular (MT), semicontinuous stirred tank (SCST), tower (TO), tuLular (TU). Phases liquid (L), gas (G), Loth (LG). Space velocities (hourly) gas (GHSV), liquid (LHSV), weight ( VHSV). Not available, NA. To convert atm to kPa, multiply Ly 101.3. 

The reactor feed may be preheated and the feed pressure may alter. The volumetric flowrate of gases depends on the reactor temperature and pressure at fixed mass flowrate. In many cases, the feed is liquid at room temperature, while the reaction mixture is a gas at the higher temperature in the reactor. In these instances, the performance of the reactor is represented as conversion and selectivity against the liquid hourly space velocity (LHSV). This is defined as... 

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. 

A vapor phase process for deparaffmization of light gas oils performed by the BP works in this way The gas oil, boiling range 230-320°C, is passed over a 5-A molecular sieve at 320°C and a pressure of 3.6 bar. The space velocity is 0.63 vol liquid gas oil per vol molecular sieve and per hour, [liquid hourly space velocity (lhsv) = 0.63] the adsorption period takes 6 min. Together with the gas oil vapor 120 vol N2 per vol liquid gas oil is led over the sieve as carrier and purge gas. After the adsorption period the loaded molecular sieve is purged at the same temperature with pure N2 for 6 min. Subsequently, the adsorbed /z-alkanes are desorbed by 1 vol liquid /z-pentane per vol molecular sieve and per hour. The /z-pentane is recovered from the /z-alkane//z-pentane mixture by simple distillation [15]. The IsoSiv process of the Union Carbide Corporation works in a similar way [16]. The purity of the isolated /z-alkanes is >98%. 

The catalytic tests [temperature = 543-703 K liquid hourly space velocity (LHSV) = 2,0 h gas hotuly space velocity (GHSV) (if not differently reported) = 510 h PYC/formaldehyde acetal =1 1 moEmol were carried out in... 

Hydrodearomatization (HDA) was investigated on the mentioned catalysts in temperature range 260-360°C, at total pressures 35-80 bar, hydrogen to hydrocarbon ratios (H2/HC thereafter) 200-1000 Nm3/m3 and liquid hourly space velocity (thereafter LHSV) 0.75-4.0 h"1. The experiments were carried out on catalysts of steady-state activity, in continuous operation. 

LHSV liquid-hourly space velocity (m lefill/(m ata yst h))... 

The spent acid strength is maintained at about 90 wt% H2SO4. The molar isobutane/alkene feed ratio ranges from 7 1 to 10 1. Typical operating alkene space velocities (LHSV) range from 0.2 to 0.6 h-1 (corresponding to WHSVs from 0.06 to 0.19 h 1). The optimum reaction temperatures range from 279 to 283 K, but some units are operated at temperatures up to 291 K. 

Because of its large reactor volume, the auto-refrigerated process can operate at very low alkene space velocities of about 0.1 h-1 LHSV (WHSV ca. 0.03 h 1). This design helps in increasing the octane number of the product and lowering acid consumption. The reaction temperature is maintained at about 278 K to minimize side reactions. Spent acid is withdrawn as 90-92 wt% acid. The isobutane concentration in the hydrocarbon phase is kept between 50 and 70 vol%. 

Both phases are substantially in plug flow. Dispersion measurements of the liquid phase usually report Peclet numbers, uLdp/D, less than 0.2. With the usual small particles, the wall effect is negligible in commercial vessels of a meter or so in diameter, but may be appreciable in lab units of 50 mm dia. Laboratory and commercial units usually are operated at the same space velocity, LHSV, but for practical reasons the lengths of lab units may be only 0.1 those of commercial units. 

The key process variables for C8A isomerization are the temperature, pressure, weight- or Hquid-hourly space velocity (WHSV or LHSV) and hydrogen partial... 

A West Texas gas oil is cracked in a tubular reactor packed with silica-alumina cracking catalyst. The liquid feed mw = 0.255) is vaporized, heated, enters the reactor at 630°C and 1 atm, and with adequate temperature control stays close to this temperature within the reactor. The cracking reaction follows first-order kinetics and gives a variety of products with mean molecular weight mw = 0.070. Half the feed is cracked for a feed rate of 60 m liquid/m reactor hr. In the industry this measure of feed rate is called the liquid hourly space velocity. Thus LHSV = 60 hr Find the first-order rate constants k and k " for this cracking reaction. 

Noble Metal Catalysts. Rh-based catalysts have been investigated on different supports, resulting in different H2 and CO yields. Gasoline and naphtha POX over a supported Rh catalyst were reported by Fujitani et al. For y-alumina supported Rh catalyst, maximum yields of 96% of both H2 and CO were reported with 0.2 wt% Rh loading at 700°C, an air equivalence ratio of 0.41, and a liquid hourly space velocity (LHSV) of 2 h A 0.05 wt% Rh supported on zirconia yielded 98% H2 and 85% CO at 725°C, an... 

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. 

Space velocities (hourly) gas (GHSV), liquid (LHSV), weight (WHSV). 

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