Optimization of a Sootblowing System for Effective Deposit Removal in Radiant Syngas Cooler Using Numerical Simulation

Abstract

The radiant syngas cooler (RSC) absorbs heat and generates steam, which is an indispensable part of the entrained-flow gasification system. The fly ash particles and molten slag adhere to the membrane wall of the RSC, resulting in an increasing thermal resistance of the membrane wall and a decreasing efficiency of the gasification system. The impact force of high-pressure airflow from the sootblowers can remove ash and slag deposits. In this study, a two-dimensional model of sootblowing without an impact wall surface and a three-dimensional model of water wall tubes in the industrial-scale RSC for a 2000 t/d entrained-flow coal gasifier are established. The effects of impingement angle, distance, and pneumatic supply pressure of sootblowers are numerically investigated to improve the sootblowing efficiency. The sootblowing gas flow characteristics and deposit removal performance analysis are studied as well. The results show that the core region of the sootblowing jet is located at a distance of 42 mm from the nozzle, exhibiting a jet velocity of 340 m/s under basic operating conditions. The effective impact distance range is insufficient when the pneumatic supply pressure is below 6.8 MPa. The effective sootblowing region reaches the largest area when the sootblowing angle is 30°and the sootblowing distance is 110 mm for radiation screens. The practical installation of sootblowers would be more optimal by selecting a smaller impact angle which can enhance the efficiency in a sootblowing system. The shorter sootblowing distance is suitable for removing high strength deposits, but it is not conducive to overall removal of ash and slag. The effective sootblowing area increases from 29.3 to 355.0 cm 2 when the pneumatic supply pressure of the sootblower is raised from 6.9 to 8.1 MPa.