| OCR Text |
Show - Page 8 - -% * Increase output by increasing the volume of fuel gas and by adding oxygen. The amount of combustion air is reduced. The volume of waste gas remains constant. Fig. 2 shows the influence of the oxygen concentration x 02 as well as that of the air temperature d r on the efficiency of a combustion process with a waste gas temperature of cf' = 1400°C. It can be seen, for example, that, to produce the same degree of efficiency, preheating of the combustion air (which may be uneconomical if expensive heat recovery facilities are required) can be replaced by oxygen enrichment of the combustion air. A substantial increase in the level of efficiency results from enriching combustion air that has already been preheated. To save primary energy : the volume of fuel is reduced by adding oxygen, the furnace output remaining constant. The volume of combustion air is reduced. The volume of waste gas is smaller. In addition to preheating the fuel and the combustion air, the use of oxygen is an alternative which can partly replace expensive imported forms of energy such as crude oil and natural gas which are required, for example, in the metallurgical industries. The electrical energy that is required in order to produce the oxygen can be generated with the aid of available sources of energy e.g. coal or lean gas. Fig. 5 illustrates the application of oxygen additions to save fuel, based on 1m3 fuel with air combustion and with Netherlands natural gas as the fuel. The Table assumes that the combustion air ( \ = 1.1) is not preheated, as is frequently the case in practice. > Fig. 4, similar to Fig 3, but having Sasol Gas as the fuel. |
