In chemical processing facilities, maintaining stable temperature control of jacketed reactors is critical. Steam injection heating of hot water can deliver improved temperature control, which equates to improved product quality, increased production efficiency and reduced operation costs.
Typically, in jacketed vessel heating, the chemical solution in the jacketed vessel is heated by introducing live steam to the jacket in a controlled ramp-up manner. After the desired chemical reaction takes place, the vessel goes through a cool down phase to bring the solution back to safe handling temperatures.
Unfortunately, live steam in the jacket can produce hot spots around the jacket, and condensate can form in the bottom of the jacket. In addition, the time it takes to remove the steam from the jacket to go to a cooling phase can cause a lengthy delay in the temperature control loop. Live steam in the jacket can also create hot spots and has the potential to crack and damage glass lined vessels and welds on steel tanks.
Steam injection heating of water to heat the jacket offers a more reliable and controllable solution than the live steam method. Instead of introducing live steam to the jacket, a ProSonix (PSX) direct steam injection heater instantaneously heats water that then surrounds the jacketed vessel at an even temperature.
When placed on the heat/cool recirculation loop, the PSX heater gives operators control to precisely adjust the water temperature up or down in the re-circulation loop. The temperature control is so precise that set-points are achieved at +/- 1 °F and the temperature is maintained for the duration of the cycle. Once the heating cycle is complete, the PSX heater can be closed to allow for the cooling process to begin. The transition from heating to cooling can be seamless since there is no need to purge the of steam prior to cooling.
In an article in the Instrument Society of America (ISA), “How To Achieve Tight Industrial Process Recirculation Temperature Control,” steam injection heating to produce hot water was cited to provide jacketed vessel heating improvements over live steam…
“The addition of hot water instead of steam directly into the coil or jacket provides a more uniform heat distribution, a dramatically smoother transition between heating and cooling, and a more efficient and maintainable system. For rapid heating, the use of direct steam injection heaters and pressurized water as shown in Figure 1 can provide hot water temperatures well above 100°C. If the injection heater has hundreds of small orifices, the bubbles are extremely small and are rapidly and quietly mixed into the water. The use of jacket outlet temperature reduces the possibility of bubbles hitting the temperature sensor.1”
The direct steam injection heating method is effective for both continuous reactors and batch reactors. With continuous reactors, it is imperative to maintain the temperature set-point and reduce temperature swings. The same is true for batch reactors which also require a stable response to temperature changes in order to avoid process upsets like an exothermic reaction.
Contact ProSonix today to learn how your process can benefit from a PSX heater.
1. Gregory K. McMillan, ISA Interchange – How to Achieve Tight Industrial Process Recirculation Temperature Control July 29, 2015 – Ref: https://automation.isa.org/how-to-make-transitions-between-cooling-and-heating-smooth-and-fast/