Study on the materials of coal liquefaction pilot plant (The 3rd Report) - Letdown valve and block valve -

摘要

Letdown valves and block valves in 150t/d Bituminous coal liquefaction pilol plant (PP) were operated under the most severe abrasive environments such as the high temperature of coal slurry at 380 approx 460 deg C and the high pressure difference, 16.7 approx 18.7MPa. In these conditions, the erosion and the abrasion were predicted on the parts of these valves. Letdown valves are installed at the line between high temp. separator and atmospheric column. The liquid level in high temp. separator is controlled and the pressure of fluid is depressurized up to the operating pressure of atmospheric columm. Block valves were installed at the line to the blow down system and were operated at intermittently, for protecting the pressure increase at liquefaction reactors. The nondestructive inspection such as visual, penetration test etc. and the fracture tests such as hardness, micro structure, SEM view etc. were carried outr for these at intermittently, for protecting the pressure increase at liquefaction reactors. The nondestructive inspection such as visual, penetration test etc. and the fracture tests such as hardness, micro structure, SEM view etc. were carried out for these valves. The fine grain based tungsten carbide (WC) and the sintered diamond for letdown valve and SUSF321/Stellite + Plasma Chemical Vapor Deposition (PCVD) treatment for block valve, are useful for coal liquefaction plant, in which the function of protect for the erosion and the abrasion is enhanced. The adequacy of the selecting materials in PP was confirmed through this inspection study. Basically, the most proper material selections, by the evaluation of he materials based on these results of this inspections, by the evaluation of the materials based on these results of this inspection study, are expected for the material selection of commercial plant in the long period operation.