Recovering gases

Recover gases from purge stream 0.946 MJ/kg PE, which reduces the losses to 0 MJ/kg PE. Recovery costs in terms of exergy are minimal and have not been shown. 

Darivakis et al.23 conducted PE pyrolysis in an electrically heated sample holder under helium flow. Polymer weight loss was almost total at 700 °C, two product fractions being recovered gases and condensables, the latter being formed by tars and higher molecular weight volatilizable products. At a heating rate of 1000 °C s PE volatilization approached 100% in just 0.7-0.8 s. 

Recover gases Poly gasoline CiHt-i-tC4Hi = 0>Hi4 1,600-2,000 900-1025 ... 

Recover gases Poly gasoline 2.3(CaEt ) C1.inH4.4a 300-600 300-450 Phosphoric acid... 

Recover gases Poly gasoline x(CnHra) = C aaHlaa 70-190 Sulfuric acid... 

Krypton also may be recovered from spent fuel rods of nuclear power plants. It is produced, along with xenon, in fission of uranium and plutonium. This process, however, is not a major source of krypton, and the recovered gas also contains radioactive Kr-85 isotope. 

It may not be possible to detect GHB and related compounds with common urine or serum (body fluid) tests. In cases where an unused portion of the drug cannot be recovered, gas chromatography-mass spectrometry (a high-technology instrument that separates a chemical mixture and identifies its composition) can be used to detect GHB and related compounds from a sample of serum, plasma, blood, or urine. 

The potential for utilizing the recovered gas is extremely limited due to the distance of plant locations... 

Inflammable gas recovery system (Exhaust gas after burning recovered gas) 15 58 7... 

This equipment may be supplemented upstream by the washing with cumene of the different liquid streams recovered (gas treatment, separation of solids), and downstream by the purification of tbe light ends, by cooling and condensation, and the removal of sodium carbonate and catalyst in the separators, particularly by washing with water. 

The recovered gas is sent to the hydrocarbon recovery section, where the reaction components are separated from propane and both fractions are recycled inside BL as appropriate. Thus, the hydrocarbon efficiency is kept very high. 

Dehydration and acid removal for recover gas and sale of 0.5 X 10° cu ft/day to a chemical company to generate process steam... 

Qatargas is leading a major project to recover gas currently flared during LNG ship loading in Ras Laffan Port. The 1 billion JBQG Project is the largest project of its kind in Qatar and will enable BOG to be collected from LNG ships and compressed at a central facility. The compressed gas will then... 

Meanwhile, the polymer stream from the high pressme separator is fed to the low pressme separator. Although considerable ethylene has already heen removed from this stream, further recovery is still possible. This recovered gas is fed to a multiple stage compressor to get it back to feed pressin-e and then fed to the secondary compressor with the gas from the high pressime separator. Small purges (less than 2%) of the feed from the multiple stage compressor may be taken to control the buildup of inert gases, such as methane and ethane. 

The powder withdrawn fi om the gas phase reactor is separated from the associated gas and purged with nitrogen to remove residual hydrocarbon before it is transferred to extrusion. The recovered gas is compressed and returned to the gas phase reactor. Because most of the propylene from the loop reactor is consumed in the gas phase reactor, the recycle stream to the loop reactor is very small. 

Stripping deficiencies. Stripping the resid with exhaust steam is a cost-effective method to recover gas oil. A properly operated stripper may easily remove half of the gas oil that is left in the resid after it drops out of the... 

In a crude-short world, projects that recover gas oil (which is readily converted to gasoline) from resid will almost always have a good payout. Residual fuel prices must, in the long run, compete against coal, while gasoline prices are a direct function of crude oil costs. A few projects that have seen successful field application are as follows ... 

F have been used in this process. A modification of the process resulting in an appreciable reduction of hydrocarbon gas loss has been described by Freireich and Tennyson (1977). In this scheme, the gas from the second intermediate pressure flash is washed with. solvent in a small absorber. The overhead from this absorber is recompressed and recycled to the plant inlet. It is claimed that the value of the recovered gas amply compensates for the cost of the additional equipment, and that a payout as low as three months is realized with a fuel cost of 2 per MMbtu. 

There are two major types of VDU ojjerations in a modem refinery -feedstock preparation and lubricant production. Feedstock preparation is the most common ojjeration that recovers gas oU from the atmospheric residue as a feed to the downstream conversion units (e.g. FCC and hydrocracking units), which converts the gas oil into more valuable liquid products such as gasoline and diesel. Lubricant production is designed to extract petroleum fractions from the atmospheric residue to produce luboil with desirable viscosity and other related properties. 

When used to separate solid-solid mixtures, the material is ground to a particle size small enough to liberate particles of the chemical species to be recovered. The mixture of solid particles is then dispersed in the flotation medium, which is usually water. Gas bubbles become attached to the solid particles, thereby allowing them to float to the surface of the liquid. The solid partices are collected from the surface by an overflow weir or mechanical scraper. The separation of the solid particles depends on the different species having different surface properties such that one species is preferentially attached to the bubbles. A number of chemicals are added to the flotation medium to meet the various requirements of the flotation process ... 

If air is used as stripping agent, further treatment of the stripped material will be necessary. The gas might be fed to an incinerator or some attempt made to recover material by use of adsorption. 

This process thus enables gasoline production to be increased if the propylene can not be used for petrochemical manufacture. It recovers ethylene economically from fuel-gas. 

As small droplets of liquid are usually still present in the gas phase, demisting secWons are required to recover the liquid mist before it is carried over" in the gas stream out of the separator. The largest liquid droplets fall out of the gas quickly under the action of gravity but smaller droplets (less than 200 microns) require more sophisticated extraction systems. 

Dehydration can be performed by a number of methods cooling, absorption and adsorption. Water removal by cooling is simply a condensation process at lower temperatures the gas can hold less water vapour. This method of dehydration is often used when gas has to be cooled to recover heavy hydrocarbons. Inhibitors such as glycol may have to be injected upstream of the chillers to prevent hydrate formation. 

Condensable hydrocarbon components are usually removed from gas to avoid liquid drop out in pipelines, or to recover valuable natural gas liquids where there is no facility for gas export. Cooling to ambient conditions can be achieved by air or water heat exchange, or to sub zero temperatures by gas expansion or refrigeration. Many other processes such as compression and absorption also work more efficiently at low temperatures. 

When gases are rich in ethane, propane, butane and heavier hydrocarbons and there is a local market for such products it may be economic to recover these condensable components. Natural gas liquids can be recovered in a number of ways, some of which have already been described in the previous section. However to maximise recovery of the individual NGL components, gas would have to be processed in a fractionation plant. 

A complex gathering station may include facilities to separate produced fluids, stabilise crude for storage, dehydrate and treat sales gas, and recover and fractionate NGLs. Such a plant would also handle the treatment of waste products for disposal. 

Sales gas would be piped directly into the national gas distribution network (assuming one exists) and NGL products such as propane and butane can be stored locally in pressurised tanks. NGL products are often distributed by road or rail directly from the gathering station, although if ethane is recovered it is normally delivered by pipeline. 

New technology is applied to existing fields to enhance production. For example, horizontal development wells have been drilled in many mature fields to recover remaining oil, especially where the remaining oil is present in thin oil columns after the gas cap and/or aquifer have swept most of the oil. Lately, the advent of multi-lateral wells drilled with coiled tubing have provided a low cost option to produce remaining oil as well as low productivity reservoirs. 

A considerable percentage (40% - 85%) of hydrocarbons are typically not recovered through primary drive mechanisms, or by common supplementary recovery methods such as water flood and gas injection. This is particularly true of oil fields. Part of the oil that remains after primary development is recoverable through enhanced oil recovery (EOR) methods and can potentially slow down the decline period. Unfortunately the cost per barrel of most EOR methods is considerably higher than the cost of conventional recovery techniques, so the application of EOR is generally much more sensitive to oil price. 

The most common solvent employed is carbon dioxide gas, which can be injected between water spacers, a process known as WaterAlternating Gas (WAG). In most commercial schemes the gas is recovered and reinjected, sometimes with produced reservoir gas, after heavy hydrocarbons have been removed. Other solvents include nitrogen and methane. 

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