APEX® Technology

For Uniform Temperature Distribution

APEX-delfino® Temperature Equalizer

Background: Temperature of the Stream at the Outlet of the Heat Exchanger - Design vs Reality

For design of the downstream equipment, it is commonly assumed that the temperature of the process streams leaving industry’s typical heat exchanger, such as Air Preheater, is uniform. In practice however, the temperature of the stream leaving Air Preheater is not uniform. This is true to virtually any type of gas-to-gas heat exchanger. At some occasions the spread of the temperature gradient is not acceptable for the proper operation of the downstream equipment, for example ID fan, burners, SCR catalyst or bag filters to name a few.

In order to solve this issue and to reduce such a temperature gradient spread, our engineers at APEX-Research developed the APEX-delfino® Temperature Equalizer. It is a static device tailor-designed to “equalize” as much as possible the temperature gradient in a very short length of the stream at a minimum additional pressure drop.

Figure 1 presents a working principle of the APEX-delfino® Temperature Equalizer in a CFD (Computational Fluid Dynamics) simulation.

Figure 2 presents results of a CFD simulation of the APEX-delfino® Temperature Equalizer, compared with results of an experimental approach in our laboratory. Please notice the qualitative similarities of these results. The results of many flow experiments served as a validation method of the definition of CFD boundary conditions used for our simulations.

Figure 1. CFD simulation of the APEX-delfino® Temperature Equalizer.
Figure 2. CFD simulation results compared with flow experiment.
Mixing of two or more streams of different temperatures

APEX-delfino® Temperature Equalizer can also be used to “equalize” the temperature of two or  more separate streams meant to be mixed together.

Figure 3 presents a 3D model of an application, where the flue gas from the Thermal Oxidizer has to be cooled down before reaching the CORPEX® Gas Cooler and the DeNOx SCR catalyst downstream. The APEX-delfino® Temperature Equalizer in this case is working with 3 streams. The main hot stream is the flue gas entering with average temperature of 1010 °C (1850 F). The two other streams entering from the top and the bottom with average temperature of 319 °C (606 F) is a dryer gas used as a coolant. The mixing of all three streams and the outlet temperature gradient required by the design is achieved in a very short stream length equal less than 2 lengths of the device itself.

Figure 4 presents the CFD simulation results in terms of velocity and temperature of the mixed streams.

Figure 3. A 3D model of the Thermal Oxidizer, the APEX-delfino® Temperature Equalizer and the CORPEX® Gas Cooler used for the CFD simulations.

Figure 4. Results of the CFD simulation; velocity profile of the mixed stream (upper), temperature profile of the mixed stream (lower).