Fuel heating value

Utihties that reduce emissions below the number of allowances they hold may trade emissions credits on the open market. Owners of plants affected by Phase I regulations can also petition the EPA for a two-year extension for meeting Phase I emissions if they have selected a control option capable of reducing SO2 emissions by 90% or more, such as is capable by flue-gas desulfurization. Owners of these units can receive bonus allowances for 1997—1999 if they have operated at SO2 emissions below 0.52 kg/10 kj (1.2 lb/10 Btu) of fuel heating value input. 

Combustion effieieney is a measure of eombustion eompleteness. Combustion eompleteness affeets fuel eonsumption direetly, sinee the heating value of any unburned fuel is not used to inerease the turbine inlet temperature. To ealeulate eombustion effieieney, the aetual heat inerease of the gas is ratioed to the theoretieal heat input of the fuel (heating value). 

Boilers. Boiler efficiency will determine how much fuel is used, an important operating cost parameter. Pin the supplier down on just what efficiency is quoted and whether the basis is higher or lower fuel heating value. 

Supply side efficiency measures. Here we mean primarily increasing the efficiency of electricity production. Natural gas combined cycle power plants (NGCC) emit less C02 than single-cycle coal-fired power plants first, because natural gas emits about one-half the amount of C02 per fuel heating value than coal, and secondly, because the thermal efficiency of combined-cycle power plants is in the 45-50% range compared with the 35-38% range of single-cycle plants. In the... 

Figure 8.1 is based on field-erected cost for furnaces designed to elevate hydrocarbon streams to 700°F at 500 psi (maximum) with absorbed heat duties in excess of 10 mmBtu/h. All tube banks are carbon steel, except pyrolysis or reformer furnaces, which have stainless tubes. Process furnaces generally have overall fuel efficiency of 75% (lower fuel heating value conversion to actual absorbed heat). Although most furnace vendors claim much higher efficiencies, this 75% efficiency value is... 

In the case of C02-selective membranes in precombustion processes, the fuel heating value remains at the high-pressure retentate side (H2 and unconverted fuel) in the WGS separation process. The power-cycle efficiency for natural-gas-fuelled GTCC including C02-selective membranes in the WGS reactor appears less pressure dependent compared to hydrogen-selective membranes, due to the lower amount of C02 produced in the MSR + WGS reactions [24]. A relative simple simulation for precombustion capture made (based on C02/H2 selectivity of 50) [24], suggests that... 

A typical heat balance for Run LSF 34 on No. 6 oil is given in Table V. The calculated efficiencies are also given in the table. Heat input terms consist of the input heat from the fuel, the fuel sensible heat, and the makeup water sensible heat. The heat available from combustion of the fuel is calculated from the measured volumetric flow rate, the measured fuel heating value, and the measured fuel density at the nozzle temperature. The fuel sensible heat contains the fuel mass flow rate, the measured temperature at the nozzle, a reference temperature, and an estimated specific heat for the oil of 0.480 Btu/lb°F. The specific heat was taken from graphical information in the ASME Power Test Code. Similarly, the water sensible heat calculation contains a tabular value... 

The wood-derived biomass was delivered dry in batches of about 2 m in chipped and dried to < 10% moisture content. Two orujillo samples were delivered, after they had been dried up to about 10% moisture content. One of them is from the direct olive oil production process (orujillo ) and the other is washed (oruJillo 2) in order to diminish the potassium content as a mean to prevent bed-agglomeration. This potassium-reduction prelreaiment implies a fuel inorganic portion decrease so that a rise in the fuel heating value is caused. 

Since the diverted power must be replaced by additional steam expanded to the ultimate condensing pressure, the fuel heating value required to deliver this heat is given by... 

The fuel heating value is the total amount of energy that can be liberated by combustion of a fuel. The heating value may be normalized by mass, moles, or volume accordingly, it will have units of kj/kg, J/mol, or J/Nm. Customary units include Btu/lbm, Btu/lbmol, and Btu/scf. In the case of volume, some standard temperature and pressure must be chosen, such as 25°C and 1 atm. Two examples of unit volumes referenced to such conditions are the normal meter cubed (Nm ) and the standard cubic foot (scf). 

The fuel typically used in modern fired heater design is natural gas. Fuel heat values are important variables in economic operation of a furnace system. Heat value refers to the known differences in the heat energy released when different fuels burn. Natural gas has a heat value of 909 Btu/ft. ... 

However, this type of scheme prevents the application of many of the techniques covered in this chapter. It would be difficult to devise a feedforward scheme to deal with disturbances in feed rate, heater inlet temperature or fuel heating value. A better solution is illustrated in Figure 10.11. 

Fuel consumption The input fuel heating value per unit of time to a gas turbine, generally measured in Btu/h (kJ/h), also called heat consumption. It is generally stated in terms of the lower heating value (LHV) of the fuel by gas turbine manufacturers, but can also be in terms of pounds per hour, where typical heating values are 18,500 Btu/lb (42,940 kj/kg) for liquid fuels and 21,500 Btu/lb (49,902 kj/kg) LHV for natural gas. (Also see Specific Fuel Consumption. )... 

Schematically, CO2 capture can be achieved following three main strategies (Figure 39.1) [12] (1) oxy-combustion (or oxy-fuel combustion) where the fuel combustion is performed with pure or enriched O2 instead of air, so that a CO2/ H2O mixture is produced (2) pre-combustion, where the carbon from the fuel is removed prior to combustion (decarbonization) either as CO2, as coke, or in other forms, and whereby the primary fuel heating value is transformed into H2 through partial oxidation, steam reforming, or autothermal reforming with subsequent water-gas shift (WGS) reaction and (3) post-combustion, where CO2 recovery is performed at the end of pipe from a wet exhaust flue gas, usually at 10-30% (v/v) CO2 concentration. The target separations to achieve in these processes to make them feasible are O2/N2 for oxy-combustion, CO2/H2 for precombustion, and CO2/N2 for post-combustion CO2 capture.

Heat balance terms such as furnace stack heat loss as a fiiaction of fired fuel heating value and furnace efficiency are not calculated, mainly since these indices of performanee are not required in an optimization system that has the plant-wide operating profit as an objective function. These indices are remnants of local equipment or design optimization approaches. T5q)ically a plant s operation should not be constrained nor its performanee judged by these indices. Models can of course be easily used to ealculate these indices, and plant built to the furnace models to perform these calculations on-line. 

Fuel Heating value Lb flue gas per lb fuel Btu absorbed per sq ft (proj.)... 

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