Total heat input

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... 

An advantage of a stoker-fired furnace is its easy adaptability to firing almost any unsized solid fuels. Bark, bagasse, or refuse can normally be fired on a stoker to supplement the coal with a minimum amount of additional equipment. Thus, such supplementaiy waste fuels may be able to contribute a higher percentage of the total heat input in a stoker-fired furnace than in a PC furnace without expensive equipment modifications. 

It is additionally recommended in the British Gas publication Guidance Notes on the Installation of Gas Pipework, Boosters and Compressors in Customers Premises (lM/16) that for buildings containing plant over 2 MW total heat input and being supplied with gas at pressures above 1 bar, a remotely operable valve shall be fitted in the gas supply to the building. In the case of large boiler houses, provision for remote operation of the valves shall be provided both inside and outside the building. 

In addition to the use of such manual valves, automatically operated valves may be considered as an additional safeguard in certain installations. These can be connected to (among other interlocks) panic buttons sited within the building, which they are protecting. This is a recommended requirement for buildings containing plant of over 2 MW total heat input and supplied with gas at above 1 bar. 

The primary mode of heat transfer at the wall is forced convection of the vapor phase. As the liquid does not wet the heating surface during film boiling, heat transfer due to drop-wall collisions is relatively small, resulting in low wall-drop heat transfer (only a few percent of the total heat input). Most of the droplet evaporation occurs because of vapor-drop heat transfer. Just after dryout, the... 

Since the total heat input represents the time integral of the heat transfer rate, it is evident from equations 10.1.9, 10.2.7, and 10.2.8 that... 

Various relationships have been recommended for computing the heat added to a vessel that is engulfed in fire. For regulated materials the OSHA 1910.106 criterion20 is mandatory. Other standards are also available.21 Crozier,22 after analysis of the various standards, recommended the following equations for determining the total heat input Q ... 

A is the area absorbing heat (in ft2) for the following geometries for spheres, 55% of total exposed area for horizontal tanks, 75% of total exposed area for vertical tanks, 100% of total exposed area for first 30 ft, and Q is the total heat input to the vessel (in Btu/hr). 

Q is the total heat input through the surface of the vessel (Btu/hr),... 

The total heat input is found using Equation 9-36 ... 

By comparing Figs 7.1, 7.2 and 7.3 it is obvious that Mv (the manipulated variable) represents the flowrate of the hot stream. The load U enters the loop at this point as changes in any of the load variables will affect the heat entering the system. Thus the total heat input to the process will be due to U and to Mv. The reasons when and why the net effect of U and Mv may be represented by a simple... 

Q = Total heat input to wetted surface of vessel. 

In the first iteration, a reduction in the length and diameter successfully corrected most discrepancies except those of the outlet pressure and the residence time. To meet the latter specification, the diameter was further reduced. Simultaneously, the inlet pressure had to be increased to account for the resulting increase in pressure drop. Furthermore, as the heat transfer area decreased with diameter, the radiant temperature must also increase to supply a constant total heat input. 

This subject is discussed in detail in Chap. 5, along with the use of auxiliary reboilers and condensers as well as the idea of using total heat input controllers. 

Next, starting at each of two temperatures (Tq), add a fixed quantity of heat to the liquid, observe the final temperature (Tf), and subtract the heat absorbed by the container from the total heat input to determine the amount of the heat added to the liquid, Q. ... 

The supercooled stream from the A unit flows directly to the worker unit. There is normally a 5-8°C (10-15°F) temperature rise across the B unit most of which results from latent heat of crystallization mechanical power does not add significantly to the total heat input. The plasticized fat from the B unit is forced through a special extrusion valve that also maintains an internal pressure of 17-20 bar... 

While accurate estimation of flue gas volumes requires heat and material balance and iterative calculations, a few mles of thumb can be used to produce a rough estimate. The heat required to raise the soil temperature to 1400°F is equal to the weight of soil (moisture free, 32,000 x 0.9) times the temperature difference (1400—60) times the specific heat [approximately 0.30Btu/(lb°F)], or 12 MBtu/h (1 MBtu = lO Btu). To vaporize the 3200 Ib/h water, 3 MBtu/h is required. Available heat at a kiln exhaust gas temperature of 1500°F at 50% excess air is 45%, so a total of 33 MBtu/h is required. Adding in radiation loss brings this to 35 MBtu/h. The secondary combustion chamber takes approximately an equal amount of heat, or 35 Btu/h. Adding these two produces total heat input of 70 MBtu/h. 

Discussion. The "thermal efficiency" of this boiler—that is, the net usable heat output in steam divided by total heat input in coal—is purported to be 85%. To cite such efficiencies—energy ratios—is misleading. As shown by the foregoing overall analysis of the boiler, the "available energy" of the steam, its useful energy, is much less than its energy content hence, the energy efficiency, nj, cited for the boiler is 2-1/2 times its true efficiency, Hji, of 33.8%. 

In addition, the First Law of Thermodynamics states that the change in internal energy and the work done in expansion are driven by the total heat input according to the equation ... 

Ethyl acetate is to be produced from the acetic acid and ethyl alcohol feed used in the illustrations of Secs. 14.1 and 14.2. If the feed and the product streams are both at 100°C, and 37.2 percent of the acid is converted to the ester, determine the total heat input into any reactor to produce 2500 kg of the ester. Show that this heat input is equivalent to that obtained in the illustrations in the previous sections. 

The preliminary experimental campaign was focused on the establishment of the kiln base line in terms of NO production with its original monochannel burner 80% of total heat input was supplied by the main burner and the rest through the auxiliary burner installed on the Lepol grate. 

Total heat input 21,300 + 4,700 Log mean temp, difference 148 F Assume over-all heat-transfer coefficient U Q 26 000... 

Tool travel speed influences total heat input... 

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