Separation of natural gas

FIGURE 2 Separation of natural gas into hydrocarbon constituents. 

Butane is obtained during the separation of natural gas into its components. Natural gas consists primarily (70 to... 

The airless heat sink oven maintains the valves, columns and the detector at a constant temperature, typically 80°C. Temperature control of the above components is critical to repeatable analytical results. It is the valves and the columns that work in conjunction to effect the separation of natural gas into its standard eleven components. Temperature changes will alter the separating characteristics of the system and are therefore minimized. 

Depending on the kind of the substance they are designed to process, separators can be labeled as gas-oil separators and "gas separators (Fig. 2.1). Gas-oil separators are used for separation of oil from oil gas, and gas separators - for separation of natural gas from droplets of condensate, water, and solid particles. Gas separators, as a rule, process gas-liquid mixtures with a rather small content of the liquid phase. But they can also operate in the so-called flood regime (when a large volume of liquid enters the separator as a result of accidental injection of water or accumulation of condensate in pipes). 

Horizontal drum Separates gas, oil and water as for example as an early separation of natural gas upstream of drying or to handle sour water. Typically a relatively small load of hydrocarbon. Often called a flash drum . 

The last section Applied Aspects of Membrane Gas Separation contains three chapters. Brunetti et al. start their contribution with a brief review of membrane materials and membranes used in gas separation and survey the main directions of industrial applications of gas separation (hydrogen recovery, air separation, etc.). In the second part of their chapter they present a new concept for comparison of membrane and other, more traditional, methods for gas separation. Their approach includes a consideration of engineering, economical, environmental and social indicators. Something similar had been written 15 years ago [2] but this analysis is now rather outdated. White (Chapter 15) focuses on a specific but very important problem in industrial gas separation membrane separation of natural gas. The main emphasis is on cellulose acetate based membranes that have the longest history of practical applications. This chapter also contains the results of field tests of these membranes and considers approaches how to reduce the size and cost of industrial membrane systems. The final chapter is an example of detailed engineering... 

Figure 6.7 is a typical thick film application, the separation of natural gas components using a 50-meter column. The film thickness is five micrometers of polydimethylsiloxane, chemically bonded. Note the excellent resolution of methane, ethane, propane, and n-butane peaks one, two, three, and four. This column is well suited for volatile compounds but should not be used for high molecular weight samples, as it would require excessively... 

Although there is very little interaction between water and the porous polymer, the water peak will be retained at low temperatures. Fig. 7-52 shows the separation of natural gas at a temperature of 100 °C. 

Similarly, 2-methylpentane runs through the column faster than its linear isomer n-hexane, while 2,2-dimethylbutane, the isomer of hexane with the shortest linear chain, elutes even faster. Thus, mixtures of 2-methylbutane, n-pentane, 2,2-dimethylbutane, 2-methylpentane, and n-hexane can be easily separated with this new type of microporous MOF column. The potential applications of this mi-croporous MOF column in the efficient GC separation of natural gas and alkane mixtures are remarkable and foreseeable. The column could be used to identify the impurities in natural gas, and to monitor the amounts of mono- and multibranched alkanes formed in cracking reactions. 

The recovery and separation of natural gas liquids from raw natural gas is a relatively simple operation, which relies principally on the differences in boiling points and vapor pressures of the various components. (These... 

Condensable Hquids also are recovered from high pressure gas reservoirs by retrograde condensation. In this process, the high pressure fluid from the reservoir produces a Hquid phase on isothermal expansion. As the pressure decreases isotherm ally the quantity of the Hquid phase increases to a maximum and then decreases to disappearance. In the production of natural gas Hquids from these high pressure wells, the well fluids are expanded to produce the optimum amount of Hquid. The Hquid phase then is separated from the gas for further processing. The gas phase is used as a raw material for one of the other recovery processes, as fuel, or is recompressed and returned to the formation. 

The largest use of NMP is in extraction of aromatics from lube oils. In this appHcation, it has been replacing phenol and, to some extent, furfural. Other petrochemical uses involve separation and recovery of aromatics from mixed feedstocks recovery and purification of acetylenes, olefins, and diolefins removal of sulfur compounds from natural and refinery gases and dehydration of natural gas. 

A Bureau of Mines system for the separation of hehum from natural gas is shown in Fig. 11-119. Since the major constituents of natural gas have boiling points very much different from that of helium, a distillation column is not necessary and the separation can be accomphshed with condenser-evaporators. 

Temperature The level of the temperature measurement (4 K, 20 K, 77 K, or higher) is the first issue to be considered. The second issue is the range needed (e.g., a few degrees around 90 K or 1 to 400 K). If the temperature level is that of air separation or liquefact-ing of natural gas (LNG), then the favorite choice is the platinum resistance thermometer (PRT). Platinum, as with all pure metals, has an electrical resistance that goes to zero as the absolute temperature decreases to zero. Accordingly, the lower useful limit of platinum is about 20 K, or liquid hydrogen temperatures. Below 20 K, semiconductor thermometers (germanium-, carbon-, or silicon-based) are preferred. Semiconductors have just the opposite resistance-temperature dependence of metals—their resistance increases as the temperature is lowered, as fewer valence electrons can be promoted into the conduction band at lower temperatures. Thus, semiconductors are usually chosen for temperatures from about 1 to 20 K. 

Sealing of turboexpander and compressor process gas from die bearing housing differs for air separation and natural gas applications. The bearing housing is usually sealed in cold expanders and for cases when die process gas contains heavy hydrocarbon components, which may cause condensation in die bearing housing. 

Since going online in 1993, the joint venture has reaped large dividends from the P15/P18 blocks of Holland s Rijn field, some 40 km (25 miles) from Rotterdam. BP-Amoco processes 13 MMm (500 MMft ) of natural gas from the field each day also, nearly 2,000 m (12,300 bbl) of condensate are produced daily. The project marks the first time Dutch gas has been produced to sales specification at an offshore location. Seven reservoirs, developed separately, are tied back... 

By 1993, the structure of the interstate pipeline industi y had undergone dramatic changes. The interstates, which once had acted as both transporters and merchants of natural gas, bundling the sale and transmission of gas into one sei"vice, were required to separate these seiwices and give pipeline customers the opportunity to contract for only those services they needed. 

Louisiana, is the dclivei y site for these contracts. Henry Hub consists of an interconnection of seven interstate pipelines, two interstates and one gathering system. These interconnections allow natural gas to move from major production areas to major consumption areas. The transportation of natural gas to and from Henry Hub is contracted separately by the seller and buyer, respectively. 

NGL are those portions of natural gas which are recovered as liquids in separators, field facilities or gas processing plants. Natural gas liquids include, but are not limited to, heavier hydrocarbon components, natural gasoline and condensate they may include small quantities of nonhydrocarbons. 

Mehra (2) [Named after the inventor] A gas separation process utilizing absorption in a solvent at moderate pressures. Developed by Advanced Extraction Technologies and applied to hydrogen recovery, nitrogen rejection, and recovery of natural gas liquids. 

Condensate - Liquid hydrocarbons that have been separated from natural gas, usually by cooling the process stream which "condense" the "entrained" liquid. Typically the fractions of C3, C4 and C5 or heavier. 

Natural Gas Liquids (NGL) - The portions of natural gas that are liquefied at the surface in production separators, field facilities, or gas processing plants, leaving dry natural gas. They include but are not limited to ethane, propane, butane, natural gasoline, and condensate. 

---