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Show 3 Oil r X Natural Gas Figure 2: Gas Atomized MA Atomizer burners are provided with one liquid by-product waste gun, one diesel gun for backup, and one gas nozzle. Atomizer: Several of the conventional methods for atomization have been considered for these boilers. Steam atomization is the most economical and common method of atomization for the conventional diesel and #6 fuel oils. However, P F O has components that have the tendency to polymerize at elevated temperatures which could lead to atomizer plugging or cap fouling with carbon. Air atomization requires the use of a compressor with its associated parasitic electrical power cost. Low pressure gas atomization is ideal for this application as it is available at useful pressures for atomization and is essentially free as it is no longer valuable for processing in the ethylene unit. The atomizers chosen for this application are gas atomized Mechanical Assist (MA) which require low gas pressure (25 psig) and high liquid pressure (125 psig) , see Figure 2. These atomizers produce a fine spray with heavy liquids up to a maximum viscosity of 100 SSU. Atomization with this gun is accomplished in two stages. In the first stage, liquid is atomized mechanically in a mixing chamber where the liquid is also mixed with the off-gas. In the second stage, the two-component mixture passes through orifices in a specially drilled cap at a high velocity providing excellent droplet disbursement of oil particles in the size range of 20 to 200|im. The orifices are specially drilled in order to provide the flame shape and turn down requirements for each oil type and furnace configuration. Figure 3 is a cross section of a typical low pressure atomized M A gun showing the liquid waste pressure atomized through a simplex tip, impacted with the swirling off-gas, and exiting through the plain-orifice cap. Primary atomization of the liquid occurs at the simplex tip and secondary atomization will occur as a result of the shear through the cap with the off-gas, see Figure 4. Combustion Feasibility Test Results: With the boilers a critical part of the plant, a combustion test firing of P F O atomized with the low pressure gas is conducted. The objectives of the Large Orifice Off Gas Mixin3 Liquid" hamhpr .... "* Waste Off Gas Chamber Spinner Figure 3: MA Atomizer Detail Figure 4: MA Atomizer Parts |
