Optimizing Gas Cooling Applications

Optimizing gas cooling applications represents a unique problem. Gasses produced by industrial chemical and power plants must be cooled and scrubbed of toxins before they're released into the atmosphere. These gasses must enter a cooling tower to be cooled and scrubbed; however, the temperature and chemical makeup of these gasses makes physical testing impossible. Therefore, it's difficult to assess the process and optimize the overall application.

Using CFD, however, we can virtually simulate these environments and scenarios to find an optimal solution for our customer. In this case, our customer wanted just that. By providing the cooling tower's layout and some specifics about the system and process, our customer hoped to assess the effectiveness of a new spray system for the gas cooling operation.

Enthalpy equilibrium calculations determined the initial required cooling parameters set by the customer. We then conducted Phase Doppler Interferometry (PDI) testing to verify the injector's spray characteristics, like flow rate, drop size and velocity. Using these results, we conducted our CFD model to examine the effects of different spray nozzle arrangements for the cooling process.

Our main focus was on reducing temperature at the outlet of the tower’s cooling section and reducing the spray's wall impingement, which can create buildup over time. A discrete phase model was applied when modeling the particle injections and a mixture model simulated the multiple gas species phases. Overall, we were very happy with the CFD results and determined the best injector layout for our customer.

In the end, the best results came from a three FloMax® injector layout operating at specific flow rates and pressures based on the application. As the spray interacts with the gas, the gas temperature is reduced to the required amount at the gas outlet, the spray evaporates almost completely, and wall impingement is minimized to 0.4% kg/m³ . 

Areas of potential wall wetting were determined and provided to the customer to indicate watch areas for potential buildup or corrosion. After installing the nozzles according to the positioning determined via CFD and initial startup of the process, the results were validated and no excess moisture was detected in field operation of the process unit.