Figure 2 - uploaded by Joon Ahn
Content may be subject to copyright.
Economizer designs to improve flow uniformity: (a) the original design; (b) installation of corbels and guide vanes.
Source publication
Non-furnace boilers can improve the efficiency of industrial once-through boilers. However, temperature non-uniformity occurs in the economizer connected vertically to the boiler. Heat transfer performance is degraded by temperature non-uniformity. To solve this problem, a corbel was installed on the side wall of the economizer, and a baffle was in...
Contexts in source publication
Context 1
... tube banks are arranged in a staggered array. This setup ensures a higher heat transfer coefficient in the compact heat exchanger than the in-line one [11]; however, as shown in Figure 2a, the flow resistance on the side-wall side is small, so the flow escapes significantly toward this side. To solve this problem, a corbel was installed on the side wall, as shown in Figure 2b [12]. ...
Context 2
... setup ensures a higher heat transfer coefficient in the compact heat exchanger than the in-line one [11]; however, as shown in Figure 2a, the flow resistance on the side-wall side is small, so the flow escapes significantly toward this side. To solve this problem, a corbel was installed on the side wall, as shown in Figure 2b [12]. However, side wall corbels cannot prevent the large flow separation that occurs at the economizer inlet. ...
Context 3
... vanes have been applied to the transition ducts of gas engines and heat recovery steam generators to improve temperature uniformity [17]. As shown in Figure 2b, it was also applied to the economizer in this study. However, the temperature uniformity upstream of the economizer was not satisfactory. ...
Context 4
... this study, first, the effect of the existing guide vane (Figure 2b) was reviewed by performing CFD by considering a case without a baffle and the economizer (including the duct) with the installation of the existing guide vane. Next, CFD was performed on the TGV extending from the duct inlet to the tubes to uniformly distribute the flow in the transition duct and compare the output to the results obtained by previous studies. ...
Context 5
... the water side, the Nusselt number was obtained using the Dittus-Boelter equation according to the Reynolds number [23,24]. The heat transfer coefficient at each tube pass was obtained from the Nusselt number, and the convective boundary conditions were imposed alongside the design bulk temperature, as shown in Figure 2. The design data was obtained through the energy balance in each row mentioned in this section (Figure 3). ...
Context 6
... the overall surface efficiency was calculated. The resulting temperature distribution on the gas side is presented in Figure 2, along with the calculated water side. ...
Context 7
... quality of the produced steam was 99.7%. As shown in Figure 2b, after improving the design of the economizer, the thermal efficiency based on the high heating value of the boiler improved from 91.2% to 92.6%. The NOx concentration in the exhaust gas was about 10 ppm, and there was little difference according to the economizer design change. ...
Context 8
... was designed in such a way that the mass flow was divided in proportion to the cross-sectional area and continued from the inlet to the outlet. As will be discussed in detail later, in Figure 2b, the existing baffle increased the pressure drop in the economizer by about 15%. In TGV 1, the possibility of causing an additional pressure drop was raised as four guide vanes, twice as many as before, were installed. ...
