Simple liquefaction

LIQUEFACTIO — is the Liquefying of a Mineral Body. It is either simple or testing. Simple Liquefaction is when a body is melted, and the process has no other object than to bring it into a flowing state. 

The Telearc process, a simple liquefaction process, was introduced for peak shaving of liquefied natural gas (LNG), which can provide high thermodynamic efficiency at a low investment and operating costs. A review of ten different LNG-peak shaving plants was published which describes all the parameters used to determine the suitability of a liquefaction process for... 

Figure 5.1-1. A simple liquefaction process without recycle.

However, each kilogram of methane through the compres.sor results in only 0.396 kg of LNG. as the remainder of the methane is recycled. Consequently, the compressor work required per kilogram of LNG produced is (650 kJ/kg)/0.396 kg = 1641 kJ/kg of L.N G produced. This is to be compared with 4149 kJ/kg of LNG produced in the simple liquefaction process. 

Condensation is the process of reduction of matter into a denser form, as in the liquefaction of vapor or steam. Condensation is the result of the reduction of temperature by the removal of the latent heat of evaporation. The removal of heat shrinks the volume of the vapor and decreases the velocity of, and the distance between, molecules. The process can also be thought of as a reaction involving the union of atoms in molecules. The process often leads to the elimination of a simple molecule to form a new and more complex compound. 

At temperatures only slightly below the liquefaction temperatures, the liquids freeze. The solids are all simple crystals in which the atoms are close-packed in a regular lattice arrangement. The narrow temperature range over which any one of these liquids can exist suggests that the forces holding the crystal together are very much like the forces in the liquid. 

Polymers have inherently high hydrocarbon ratios, making liquefaction of waste plastics into liquid fuel feedstocks a potentially viable commercial process. The objective is to characterise the thermal degradation of polymers during hydrogenation. LDPE is studied due to its simple strueture. Isothermal and non-isothermal TGA were used to obtain degradation kinetics. Systems of homopolymer, polymer mixtures, and solvent-swollen polymer are studied. The significant variables for... 

Rather than use the simple cycle shown in Figure 24.44 for the liquefaction of natural gas, much more complex arrangements using multiple cycles (with both pure and mixed refrigerants) and cascade systems can be used. 

Equations of state (EOS) offer many rich enhancements to the simple pV = nRT ideal gas law. Obviously, EOS were developed to better calculate p, V, and T, values for real gases. The point here is such equations are excellent vehicles with which to introduce the fact that gases cannot be really treated as point spheres without mutual interactions. Perhaps the best demonstration of the existence of intermolecular forces that can also be quantified is the Joule-Thomson experiment. Too often this experiment is not discussed in the physical chemistry course. It should be. The effect could not exist if intermolecular forces were not real. The practical realization of the effect is the liquefaction of gases, nitrogen and oxygen, especially. 

LNG is simple to re-gasify in order to deliver almost pure methane at the end users. In contrast to natural gas that contains typically around 90% methane, and some ethane, propane and heavier hydrocarbons, the liquefaction process involves pre-treatment of the gas in order to remove carbon dioxide, sulphur compounds, water, and petroleum gases with carbon number higher than one (butane, propane etc.). This is done in order to avoid formation of solids in the cold heat exchangers. The presence of nitrogen is usually limited at about 1% (refer Table 2 on page 81). 

Why is it, if indirect liquefaction processes are technically proven, the demand exists and is getting stronger for petroleum substitutes and there is so much coal available to us that people aren t standing in line to build coal liquefaction facilities in the United States today The answer is fairly simple. There are so many uncertainties associated with commercialization — not only technological, but also institutional, legal and regulatory— that the large capital investments required seem too risky to make. Coal liquefaction facilities are capital-intensive with cost in excess of 1 billion. 

When the catalyst is available in a small amount, a microreactor assembly is often used (Miller, 1987). This is a simple T-type reactor heated by a fluidized sand bath. The mixing is provided by mechanical agitation that shakes the reactor up and down within the fluidized bed. Because of the small amount of slurry, and an effective heat transfer in the fluidized sand bath, the heat-up period in such a reactor is small. The nature of mechanical agitation is, however, energy-efficient. The reactor provides only a small sample for the product analysis, which makes the usefulness of the reactor for detailed kinetic measurements somewhat limited. The reactor has been extensively used for laboratory catalyst screening tests in coal liquefaction. 

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