*2.1. Simplification of Chemical Equipment*

Figure 1 shows a schematic diagram about the vulnerable elbow in the coal chemical plant. First, the coal-water slurry is reacted with oxygen to form the mixture gas of syngas (60%) and CO<sup>2</sup> (40%) at the temperature of 1350 ◦C. Second, the mixture gas is cooled and the temperate decreases to 250 ◦C in the quench chamber. Finally, the mixture gas is departed from the quench chamber and introduced into the transmission pipeline at high speed flow with solid contaminants (sulfur-containing fly ash) eroding the wall. CO<sup>2</sup> is dissolved in water forming the saturated carbonic acid solution that results in the electrochemical corrosion of the pipeline under the operational service or out of service conditions. The erosion-corrosion phenomena around the elbow may lead to the serious leakage under the harsh working environments.
