Heat value of gas

Gas burning equipment Usage factor Heating value of gas Use of hoods... 

Fuel gas gas analysis, available pressure, low heating value of gas. 

Another common impurity of natural gas is nitrogen. Since nitrogen has essentially no calorific value, it lowers the heating value of gas, Gas purchasers may set a minimum limit of heating value (normally approximately 9.50 Biu/scl). In some cases it may be necessary to remove the nitrogen to satisfy this requirement. This is done in very low temperaliire plants or with permeable membranes. These proces [Pg.4]

In most instances gas processing plants are installed because it is more economical to extract and sell the liquid products even though this lowers the heating value of gas. The value of the increased volume of liquids sales may be significantly higher than the loss in gas sales revenue because of a decrease in heating value of the gas. 

A similar correlation was obtained for R and the heating value of byproduct gas. Figure 14 compares gas heating value (B.t.u. per cubic foot) with R (r = —0.87) and demonstrates that the heating value of gas decreases gradually as coal rank increases through the 0.7-1.9 R range. 

Figure 14. Relationship between reflectance and heating value of gas, B.t.u. per cubic foot...

Figure 15 compares the heating value of gas, as expressed in B.t.u. per pound of coal, to the R of the samples analyzed. In general, as the R of vitrinite in coal increases, the heating values decrease (r = —0.72). As indicated by the low coefficient of correlation in Figure 5 (r = —0.72), a close relationship between R and gas heating value does not exist. Therefore, any reference to these data can only be in very general terms. 

Figure 4. Effect of hydrogen feed to coal ratio on increasing the heating value of gas by dilute-phase hydrogenation...

The effect of reactor pressure was mainly to shift the methane concentration in the gas. However, the heat content of the gas generated (net gas yield/lb maf wood x heating value of gas) was, if anything, increased by lowering the reactor pressure. 

Oakridge National Laboratory. (2010). Lower and Higher Heating Values of Gas, Liquid and Solid Euels. In Lower and Higher Heating Values of Gas, Liquid and Solid Fuels, Retrieved from http // cta.oml.gOv/bedb/appendix a/Lower and Higher Heating Values of Gas Liquid and Solid Fuels.xls. Accessed October 10, 2013. 

Material produced or extracted Disappearance of gas, cu ft per gal product Decrease in heating value of gas, Btu per gal product... 

The 120,000 is the average per gallon heating value of the liquid product, and the 1,786 is the heating value of gas No. 14. Of course, money must be spent to build and operate the plant out of the extra 17.2.cents per thousand cu ft. 

Measured in MJ/m or Btu/ft, the Wobbe Index has an advantage over the calorific value of a gas (the heating value per unit volume or weight), which varies with the density of the gas. The Wobbe Index Is commonly specified in gas contracts as a guarantee of product quality. A customer usually requires a product whose Wobbe Index lies within a narrow range, since a burner will need adjustment to a different fuel air ratio if the fuel quality varies significantly. A sudden increase in heating value of the feed can cause a flame-out. 

The absorber tail gas contains about 20 mol % hydrogen and has a higher heating value of ca 2420 kj/m (65 Btu/SCF). With increased fuel costs and increased attention to the environment, tail gas is burned for the twofold purpose of generating steam and eliminating organic and carbon monoxide emissions. 

Another hydrogenation process utilizes internally generated hydrogen for hydroconversion in a single-stage, noncatalytic, fluidized-bed reactor (41). Biomass is converted in the reactor, which is operated at about 2.1 kPa, 800°C, and residence times of a few minutes with steam-oxygen injection. About 95% carbon conversion is anticipated to produce a medium heat value (MHV) gas which is subjected to the shift reaction, scmbbing, and methanation to form SNG. The cold gas thermal efficiencies are estimated to be about 60%. 

The initial biogas recovered is an MHV gas and is often upgraded to high heat value (HHV) gas when used for blending with natural gas suppHes. The aimual production of HHV gas ia 1987, produced by 11 HHV gasification facihties, was 116 x 10 m of pipehne-quaUty gas, ie, 0.004 EJ (121). This is an iacrease from the 1980 production of 11.3 X 10 m . Another 38 landfill gas recovery plants produced an estimated 218 x 10 m of MHV gas, ie, 0.005 EJ. Additions to production can be expected because of landfill recovery sites that have been identified as suitable for methane recovery. In 1988, there were 51 sites ia preliminary evaluation and 42 sites were proposed as potential sites (121). 

The conversion of coal to gas on an industrial scale dates to the early nineteenth century (14). The gas, often referred to as manufactured gas, was produced in coke ovens or similar types of retorts by simply heating coal to vaporize the volatile constituents. Estimates based on modem data indicate that the gas mixture probably contained hydrogen (qv) (ca 50%), methane (ca 30%), carbon monoxide (qv) and carbon dioxide (qv) (ca 15%), and some inert material, such as nitrogen (qv), from which a heating value of approximately 20.5 MJ/m (550 Btu/fT) can be estimated (6). 

Blue gas, or blue-water gas, so-called because of the color of the flame upon burning (10), was discovered in 1780 when steam was passed over incandescent carbon (qv), and the blue-water gas process was developed over the period 1859—1875. Successfiil commercial appHcation of the process came about in 1875 with the introduction of the carburetted gas jet. The heating value of the gas was low, ca 10.2 MJ /m (275 Btu/fT), and on occasion oil was added to the gas to enhance the heating value. The new product was given the name carburetted water gas and the technique satisfied part of the original aim by adding luminosity to gas lights (10). 

Medium Heat- Value Gas. Medium heat-value (medium Btu) gas (6,7) has a heating value between 9 and 26 MJ/m (250 and 700 Btu/fT). At the lower end of this range, the gas is produced like low heat-value gas, with the notable exception that an air separation plant is added and relatively pure oxygen (qv) is used instead of air to partially oxidize the coal. This eliminates the potential for nitrogen in the product and increases the heating value of the product to 10.6 MJ /m (285 Btu/fT). Medium heat-value gas consists of a mixture of methane, carbon monoxide, hydrogen, and various other gases and is suitable as a fuel for industrial consumers. 

TOSCO tar oils have high viscosity and may not be transported by conventional pipelines. Heating values of product gas on a dry, acid gas-free basis are in the natural gas range if butanes and heavier components are included. 

Eig. 8. Cost of electricity (COE) comparison where represents capital charges, Hoperation and maintenance charges, and D fuel charges for the reference cycles. A, steam, light water reactor (LWR), uranium B, steam, conventional furnace, scmbber coal C, gas turbine combined cycle, semiclean hquid D, gas turbine, semiclean Hquid, and advanced cycles E, steam atmospheric fluidized bed, coal E, gas turbine (water-cooled) combined low heating value (LHV) gas G, open cycle MHD coal H, steam, pressurized fluidized bed, coal I, closed cycle helium gas turbine, atmospheric fluidized bed (AEB), coal J, metal vapor topping cycle, pressurized fluidized bed (PEB), coal K, gas turbine (water-cooled) combined, semiclean Hquid L, gas turbine... 

The energy consumption (lower heating value of the feedstock plus fuel) of the low pressure process has successively improved from over 38.3 GJ/1 when it was first introduced to 29.0—30.3 GJ/thy the mid-1990s. Natural gas-based reforming plants have advanced to the point where the scope for stiU further gains in efficiency is small and the gains costiy to obtain. 

Fuel. Propylene has a net heating value of 45.8 MJ/kg (19,700 Btu/lb) and is often contained in refinery fuel-gas streams. However, propylene is diverted from streams for refinery fuel use in large quantities only when economics for other uses are unfavorable, or equipment for propylene recovery does not exist or is limited in capacity. Propylene is also contained in Hquid petroleum gas (LPG), but is limited to a maximum concentration of 5 vol % in certain grades (83) (see Liquefied PETROLEUM gas). 

If the substitute fuel is of the same general type, eg, propane for methane, the problem reduces to control of the primary equivalence ratio. For nonaspiring burners, ie, those in which the air and fuel suppHes are essentially independent, it is further reduced to control of the fuel dow, since the air dow usually constitutes most of the mass dow and this is fixed. For a given fuel supply pressure and fixed dow resistance of the feed system, the volume dow rate of the fuel is inversely proportional to. ypJ. The same total heat input rate or enthalpy dow to the dame simply requires satisfactory reproduction of the product of the lower heating value of the fuel and its dow rate, so that WI = l- / remains the same. WI is the Wobbe Index of the fuel gas, and... 

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