Heat requirement, consumption

The primary consumption of energy in the FCCU is the process heat required to achieve the following ... 

Natural gas is assuming a preponderant role in world energy supplies. Gas penetration in the energy sector is very large, reaching about 23 % world-wide in 2001 and with a forecast increase up to 28 % by 2025 Due to heating requirements, this sector has to deal with wide seasonal variations in consumption. 

In the older type of furnaces sulphuric acid 60 °Be (78 per cent HgS04) was used. Modern mechanical furnaces work with a concentrated acid of 93 to 96 per cent HaS04 to prevent the dilution of the hydrogen chloride with water vapour as this would hamper the manufacture of concentrated hydrochloric acid. Apart from this, diluted sulphuric acid introduces water into the process and the heat required for the evaporation of this water would increase the overall consumption of heat in the reaction. 

Based on W. Heepke s model, ibid., the fundamental equation of the oven of Gusen that expresses the average consumption of a cremation is ——-— r +———= 30.6, with L = heat difference of combustion gases between entry and exit + small losses W2 = vaporization heat of water of the corpse W2a = heat required to bring water steam up to the temperature of the exiting combustion gases W3 = heat of the ashes at the extraction from the oven Vis = loss of heat of the oven by radiation and conduction W7 = calorific value of the body (and coffin, if applicable) i]I lu = efficiency of coke. 

All heat requirements for the process are provided in the form of open steam at 400 psia. Some is used at the bottom of S-1 to strip HjS and the rest is fed to the twelfth plate in HT-1 to control the temperature of the hot towers and to compensate for heat losses and heat exchanger inefficiencies. Steam consumption is 1778/0.28 = 6400 mol/mol of DjO produced. This is much less than the 200,000 mol/mol DjO needed in water distillation. Additional energy in the amount of 680 kWh/kg D2O is used to circulate gas and pump liquid. This, however, is much less than is used in electrolysis or hydrogen distillation (Table 13.7). The low energy consumption of the GS process is due in large measure to the efficient heat recovery obtainable in the flow sheet Fig. 13.30, which follows Spevack s patent [S7]. 

High temperature transient heating of meat produces in closed containers makes sterilized canned meat items stable when stored at ambient temperature at a , = 1 (Potter, 1986). The product is heat processed and does not require further heating before consumption. Chilling and subsequent storage at -20°C also renders frozen meat items stable at = 1 (Potter, 1986). 

For continuous furnaces, the previous suggestions for sizes of vents and flues are not applicable. The multiplicity of designs is so great that each type and rate of heating requires a separate calculation. The fuel consumption, rate of flow of poc, and temperature at which they leave the furnace are determined either by calculation or by comparison with existing, similar furnaces. 

It is evident that the arrangement as shown in Fig. 3.8 reduces the energy consumption of the pervaporation process to a minimum value. Only the heat required for the evaporation of the permeate has to be supplied and is lost in the process, the sensible heat of the product can be recovered to any extent, limited only by the costs of the interchanger. 

Regeneration energy consumption 30-40% of a packed bed heat requirement... 

It is generally known that reducing the operating pressure of separation columns reduces energy consumption. This is because the lower the tower pressure, the less heat required for liquid to vaporize (thus less energy required) and the easier for vapor to penetrate into liquid on the tray deck (thus better separation). Yet many columns are operated well above their potential minimum pressure. One may ask If benefit of reducing pressure is well known, why is it not widely implemented There appears to be three primary reasons for this. 

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