The slag deposited on the wall tubes in the coal-fired boiler or radiant syngas cooler (RSC) of the entrained flow gasifier could reduce the heat transfer efficiency and degrade the tubes by corrosion. During the operation of the boiler or RSC, the rapping-off-ash method is an effective method to remove slag deposits, especially in a high-pressure environment. The operating parameters of the rapping-off-ash method are related to the modal parameters of wall tubes, including the natural frequency, damping ratio, and mode shapes. In

During the operation of entrained‐flow gasifiers, the ash deposits located on the wall tubes in the radiant syngas coolers (RSC) reduce the heat transfer efficiency. Syngas sootblowing is an effective method to remove the slag deposits in the RSC. In this study, a 3D numerical model was developed by combining the cohesive zone method (CZM) and the coupled Eulerian–Lagrangian analysis to investigate the deposit fracture process in RSC during sootblowing. The quasi‐static analysis using ABAQUS obtained the stress–strain curve of the slag sample, which agreed well with the experimental tests and provided the detailed mechanical parameters to the CZM model. The dynamic characteristics of deposit fracture were discovered. The main fracture occurred between 1.0 and 1.5 ms, and the shape of the fracture area was not round but elliptical. The RSC operating pressure (P) was also investigated. The study found that higher pressure led to lower fracture speed, longer sootblowing time, and more syngas consumption. Based on the same extent of deposit fracture, syngas consumption increased when P < 3.5 MPa, and the density of syngas (ρsyngas) has a more significant influence on the syngas consumption than the velocity of sootblowing syngas flow (vavg), especially when the sootblowing time is small.

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Slag or ash removal from water wall tubes in a radiant syngas cooler (RSC) is a routine task in operation, which can effectively increase the overall thermal efficiency. Rapping ash removal is one of the valid methods for shedding off the ash deposits in the high‐pressure surroundings of the RSC. In this study, the model of a real RSC was established by a numerical simulation based on the finite element software ABAQUS, and modal analysis and instantaneous response analysis (IRA) were researched to reveal the natural vibration characteristics of the RSC and aid the design of rapping ash removal. On the basis of the results of natural vibration characteristics and a subsequent harmony response, 16 Hz was set as the impact frequency, balancing off the vibrator number and the water‐tube displacement effect. It was indicated that ash deposit in the area around 1/2 longitudinal position was easy to remove due to great response to rapping action. Moreover, rapping at ½ position generally obtained greater displacement response in the whole RSC. A rapping design was proposed with six vibrators at the ½ longitudinal position and 16 Hz frequency, and then two rapping intervals were investigated comparatively. The case with a half‐cycle interval had a slightly larger response than the one‐cycle case, with a larger displacement in more circumferential tubes as well as with a greater sound pressure response in the RSC.