So how does direct steam injection work? As shown in figure 1, the water or process fluid enters at the inlet (A) and flows past the injector (B). It is then discharged at the outlet (C). Steam enters at the inlet (D) and travels down through the injector (B), where it is diffused into the water or process fluid. Heating is regulated by controlling the amount of steam injected using an actuator to move a stem/plug to expose the required area for the sonic-velocity steam to flow through the injector (B). The turbulent nature of this high velocity discharge enables steam to instantaneously penetrate, disperse and efficiently produce uniform heating.
Direct steam injection heaters that control steam flow using internal modulation regulate both the steam flow and mixing by employing a stem/plug assembly inside the heater. Controlling the position of the stem/plug regulates the steam discharge area of the diffuser and, in turn, controls the amount of full-pressure steam that is allowed to pass through the injector. This control method uses full line-pressure steam to ensure sonic steam velocity, turbulent mixing, good temperature control and even heating distribution.
Direct steam injection technology provides many benefits to its users. First, the technology requires little or no maintenance due to its self-cleaning design. Direct steam injection has been used on products as thick as tomato paste or as tough as hard water with little or no cleaning required. The internal modulation feature of direct steam injection heaters allows for complete control of the heating process to maximize output requirements and minimize maintenance concerns.
Second, the heaters are compact and efficient. They can be mounted directly inline or above the area where the instantaneous heating process is required, so floor space is not required or consumed.
Third, due to its compact design, minimal piping is needed to install the unit within the process. The complete utilization of the steam within the heating process also saves the users the addition of a condensate return system. The elimination of these systems reduces installation, service and maintenance costs. Processes that are concerned with the injection of the steam directly into the process fluid may effectively treat the steam in the boiler with boiler chemicals.
Direct steam injection heaters do not require time to warm up or consume any production materials prior to production or full process flow at a required temperature, reducing your waste factor. The high velocity steam provides for instantaneous temperature control and optimal production runs as soon as the heater is turned on. They are 100 percent efficient because the steam generated from the boiler is directly injected into the process fluid, providing complete heat transfer and energy utilization.
If they suit your process, direct steam injection heaters can help you optimize your end product and achieve effective process heating. PH