Heating value analyses

All standardized heating value analyses measirre the heat released from the fuel when bimied with enough air to fully oxidize the fuel (carbon forms carbon dioxide, hydrogen forms water, etc.), normalized by the mass of the fuel, not the mass of all combustion products. This value determines the amoimt of fuel reqirired to release a given amoimt of heat during combustion. It does not directly indicate the peak temperatnres of the resnlting flames. These temperatures play an important role in some... 

Natural gas analysis has considerable economic importance. In fact, commercial contracts increasingly specify not just volume but the calorific or heating value as well. Today the calorific value of a natural gas calculated from its composition obtained by chromatography is recognized as valid. There is therefore a large research effort devoted to increasing the precision of this analysis. 

There also exist relatively simple correlations between the heating value of motor fuels and certain characteristics such as density and composition by chemical family supplied by FIA analysis. Refer to Chapter 3. 

Values of thermal conductivity are temperature-dependent and vary widely for different materials. Table 1 summarizes the thermal conductivity values of a few materials relevant to heat-exchanger analysis (1,2). 

The proximate analysis of charcoal is 20-25% volatile matter, 70—75% fixed carbon, and 5% ash. Charcoal briquets have lower heating values than charcoal lumps, because of additives in the briquets. The higher heating value of lump charcoal is - 28 kJ/kg (12,000 Btu/lb). The higher heating value of briquets is 23 to 25 kj/kg ( -- 9,900-10,800 Btu/lb). 

Figure 27-11 gives the theoretical air requirements for a variety of combustible materials on the basis of fuel higher heating value (HHV). If only the fuel lower heating value is known, the HHVean be calculated from Eq. (27-6). If the ultimate analysis is known, Eq. (27-7) can be used to determine HHV. 

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

Ultimate analysis-an analysis to determine the amounts of basic feed constituents. These constituents are moisture, oxygen, carbon, hydro- gen, sulfur, nitrogen, and ash. In addition, it is typical to determine chloride and other elements that may contribute to air emissions or ash- disposal problems. Once the ultimate analysis has been completed, Dulong s formula can be used to estimate the heating value of the sludge, Dulong s formula is ... 

A window consisting of a single piece of clear glass can also he treated with R-value analysis. As with the wall, there is convective and radiative heat transfer at the two surfaces and conductive heat transfer through the glass. The resistance of the window is due to the two surface resistances and to the conductive resistance of the glass, For typical window glass, R = 0.003 (W/ni -°C)" (0.02 (Btu/h-ft -°F) ) so the total resistance of the window is = (0.12 + 0.003 + 0.04) (W/m -- C) ... 

During operation, the owner/operator of an incinerator must conduct sufficient waste analyses to verify that the waste feed is within the physical and chemical composition limits specified in the permit. This analysis may include a determination of a waste s heat value, viscosity, and content of hazardous constituents, including POHCs. Waste analysis also comprises part of the trial burn permit application. U.S. EPA stresses the importance of proper waste analysis to ensure compliance with emission limits. 

From that same section, we know that the steady state gain and the time constant are dependent on the values of flow rate, liquid density, heat capacity, heat transfer coefficient, and so on. For the sake of illustration, we are skipping the heat transfer analysis. Let s presume that we have done our homework, substituted in numerical values, and we found Kp = 0.85 °C/°C, and xp = 20 min. 

Uncertainties with the availability and suitability of biomass resources for energy production are primarily due to their varying moisture content, and to a lesser degree to their chemical composition and heating value. As the moisture content of biomass increases, the efficiency of thermal conversion process decreases. At some point more energy may have to be expended to dry the biomass than it contains. Uncertainties can be reduced by conducting a detailed chemical and physical analysis of the biomass sources. 

Tables 2.5 and 2.6 provide a database on the key features of the technologies considered in this study along with the producer gas heating values and compositions. A considerable amount of data is missing, which is indicative of the need for comprehensive performance information to be organized into design practice literature to guide developers. These tables do, however, form the starting basis for the analysis presented in the sections that follow.

Bulk physical property tests, such as density and heating value, as well as some compositional tests, such as the Orsat analysis and the mercuric nitrate method for the determination of unsaturation, are still used. However, the choice of a particular test is dictated by (1) the requirements of the legislation, (2) the properties of the gas under study, and (3) the selection by the analyst of a suitable suite of tests to meet the various requirements. For example, judgment by the analyst is necessary whether or not a test that is applied to liquefied petroleum gas is suitable for process gas or natural gas insofar as inference from the nonhydrocarbon constituents will be minimal. 

Table 6.12 shows the proximate analysis data and higher heating values (HHV) of samples. The HHV (MJ/kg) of the moss and alga samples as a function of fixed carbon (FC), wt.% can be calculated from ... 

Before Southdown accepts any waste materials for recycling as fuel, a chemical analysis must be performed to identify their chemical composition. Wastes that cannot be blended to meet standards for content, heat value, and compatibility with cement production are not accepted. For instance, cement cannot be made with fuels that have a high chlorine content. 

After taking suitable coal samples for analysis, removing the blockage and filling the cavity with refractory cement, the thlrd burn test was carried out on the same channel. Figure 5 shows time-data plots for this burn. Because much of the moisture had been driven forward by the preceding burn, only a relatively low-BTU product gas was produced but by cyclical Injection of steam and air, heat values could be periodically Increased. 

Another interesting limit is the quasistatic limit r 0. Based on the numerical solution of the saddle point equations (160)-(162), it was suggested in Ref. 117 that T q) converged to a constant value over a finite range of work values. Figure 15a shows the results obtained for the heat distributions, whereas the path temperature is shown in Fig. 15b. A more detailed analysis [134] has shown that a plateau is never fully reached for a finite interval of heat values when r 0. The presence of a plateau has been interpreted as the occurrence of a first-order phase transition in the path entropy s q) [134]. 

Spore bioburden data are collected to screen for heat-resistant organisms. Organisms surviving heat-resistance testing are to be submitted to the terminal sterilization laboratory for D-value analysis. D-values are then compared to established models for the component sterilization process. 

Differential thermal analysis was performed with the DuPont 900 differential thermal analyzer the heating rate was usually 10°C. per minute. To determine heats of reaction, the calorimeter attachment to the Du Pont instrument was employed. Planimeter determinations of peak areas were converted to heat values by using standard calibration curves. For the infrared spectra either a Beckman IR5A instrument or a Perkin Elmer 521 spectrophotometer with a Barnes Engineering temperature-controlled chamber, maintained dry, was used. Specimens for infrared were examined, respectively, as Nujol mulls on a NaCl prism or as finely divided powders, sandwiched between two AgCl plates. For x-ray diffraction studies, the acid-soap samples were enclosed in a fine capillary. Exposures were 1.5 hours in standard Norelco equipment with Cu Ko radiation. For powder patterns the specimen-to-film distance was 57.3 mm. and, for long-spacing determinations, 156 mm. 

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