Abstract
In view of the three-stage flash evaporation system of the coal gasification plant, a combination of theoretical analysis and numerical simulation was used to establish the erosion damage evaluation model in the black water angle valve. The influence of the inlet flash evaporation ratio on the inlet velocity, the outlet flash evaporation ratio and the outlet velocity of the low-pressure black water angle valve are systematically studied, the mechanism of erosion damage to the carbon steel valve body by the solid medium in black water was analyzed according to the micro-cutting theory. The results show that the inlet velocity w 1, the outlet flash evaporation ratio x 2, the outlet velocity w 2 of angle valve have linear correlation with the inlet flash evaporation ratio x 1.The upstream volume erosion ratio of the angle valve at the inlet flash ratio x 1 = 3 wt.% is 114 times as much as that at zero inlet flash ratio. Meanwhile, the downstream volume erosion ratio of the angle valve at x 1 = 3 wt.% is only 2.7 times as much as that at zero inlet flash ratio. The prevention strategies to reduce the erosion damage to black water angle valve are proposed by inhibiting the inlet flash evaporation ratio and reducing the inlet flow rate etc. This study is expected to provide guidance for the erosion resistance design and operation of the black water angle valve.
Highlights
The coal reserves is the most abundant resources among fossil fuels in China, which is much more than oil and natural gas, coal chemical industry has entered into the process of large-scale industrialization under the overall layout of China energy strategy
Velocity, curvature radius, particle mass flow rate, particle diameter, average curvature radius/pipe diameter and bend direction etc.) that influence the erosion by numerical simulation methods, and established the correlation between the Stoke number and the maximum erosion area with three collision mechanisms which explains how the Stoke number influence erosion area; Mansouri et al [11] used an Eulerian–Lagrangian approach to perform the numerical erosion modeling of a 90° sharp bend in water– sand slurry flow
Standard wall-function and low-Re number approach were employed for resolving the near wall region, and the results showed that with low-Re number model, the accuracy of theerosion prediction resulting from small particle will be significantly improved; Guo-Fu et al [12] did experimental research on the erosion appearance of austenitic stainless steel A182F347 under the SiO2 and Al2O3 combined abrasive particle condition, the erosion mechanism of austenitic stainless steel A182 F347 under the liquid-solid two-phase flow system was revealed; Parsi et al [13] pointed the fact that in H-H elbow, maximum erosion occurred at the top of the elbow’s outer wall and highly related to parameters such as phase distributions, particle concentration and particle velocity under multiphase flow conditions
Summary
Low pressure black water valve LV-0301A is a singleseat angel valve with the side entry and bottom exit of 1000-Class 150 (Inlet d1 = 254 mm, Outlet d2 = 254 mm). The valve body is made of carbon steel, and seat and spool are made of tungsten carbide. Black water remains saturated at the bottom of mid-pressure flash tank, before entering the lowpressure black water angle valve, the pressure drop from connecting pipe may cause a partial flash evaporation, and accompanied with gas-liquid-solid multiphase flow. The medium of the black water angle valve LV-0301A is considered as saturated water
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