ProSonix I-Series improves centrifuge feed temperature and FOG recovery while reducing steam demand and eliminating recurring sparger maintenance.
The Challenge
An industrial wastewater processor was heating a 20,000-gallon tank of fats, oils, and greases (FOG) just to deliver a 50 GPM stream to a centrifuge at the required process temperature.
The existing system used direct steam sparging to heat the tank. The sparger was prone to plugging and fouling, creating recurring maintenance problems and inconsistent heating performance.
Heating a large tank of FOG to high temperatures also presented an inherent process challenge. As the bulk temperature increased, localized overheating around the steam sparger could cause flashing and steam loss, making it increasingly difficult and inefficient to raise the temperature of the entire tank. In some operating conditions, achieving temperatures approaching 200°F was simply not practical.
As a result, the system struggled to consistently deliver FOG to the centrifuge at the temperature needed for effective separation. When the FOG entered the centrifuge at insufficient temperature, separation performance suffered and recoverable product remained in the waste stream.
Tank heating also required significant steam. The customer estimated steam consumption of approximately 10,000–20,000 lb/hr during the heating cycle.
Rather than continue trying to heat the entire 20,000-gallon tank, the facility looked at a different approach: heat only the 50 GPM process stream going to the centrifuge.
The Solution: Heat the FOG at the Point of Use
The facility installed a ProSonix PSX I-Series Direct Steam Injection Heater directly in the process line feeding the centrifuge.
Instead of heating and maintaining the entire 20,000-gallon tank at temperature, the I-Series heats the FOG inline immediately before it reaches the centrifuge. The heater was designed to raise the FOG temperature from 65°F to 200°F at 50 GPM.
This provided the required centrifuge feed temperature while eliminating the need for tank heating.
Design Conditions
| Parameter | Design Condition |
| Application | FOG Heating |
| FOG Flow | 50 GPM |
| Inlet / Outlet Temperature | 65°F / 200°F |
| Steam Pressure | 110 PSIG |
| Required Steam Flow | ~2,975 lb/hr |
| Heat Transfer | 3.04 MMBtu/hr |
| Pressure Drop | 0.8 PSI |
| Heater | PSX202 I-Series |
The I-Series is designed for difficult process streams such as FOG, slurries, and sludges, where buildup, fouling, and excessive pressure drop can create problems for conventional heating equipment.
At the design condition, calculated pressure drop through the heater is only 0.8 PSI, minimizing additional load on the FOG pumping system. The I-Series also incorporates an integral actuator for steam-flow control, eliminating the need for a separate steam control valve and simplifying installation.
The Results
Improved Centrifuge Separation and Product Recovery
Thoroughly and uniformly heating the FOG to the required 200°F immediately before the centrifuge improved the conditions for separation.
Better separation allows more valuable by-products to be recovered from the FOG stream for beneficial reuse or resale rather than remaining in the waste stream.
Lower Steam Demand and No Tank Heating
The previous process heated a 20,000-gallon tank, with customer-estimated steam consumption of approximately 10,000–20,000 lb/hr during heating.
At the I-Series design condition, calculated steam requirement is approximately 2,975 lb/hr to continuously heat the 50 GPM FOG stream from 65°F to 200°F.
While these figures represent different operating conditions, they illustrate the fundamental advantage of the new process: steam is applied only to the FOG being sent to the centrifuge rather than to the entire tank.
16 Months Without Required Heater Maintenance
Reliability has also improved.
The previous tank sparger experienced recurring plugging and fouling. In contrast, the ProSonix I-Series has operated for approximately 16 months with no reported operational issues and no required heater maintenance.
For a difficult FOG application, eliminating a recurring maintenance problem has been an important benefit of the installation.
Estimated Payback of Less Than One Year
The economics extend beyond reduced steam demand. Improved product recovery, elimination of tank heating, and lower maintenance requirements all contribute to the value of the installation.
Based on these combined benefits, the customer estimated a payback period of less than one year.
The original installation was intended to test the I-Series for this FOG heating application. After approximately 16 months of successful operation, the customer is now planning to install ProSonix I-Series heaters at nine additional plants with the same application.
Results at a Glance
20,000-Gallon Tank Heating Eliminated
FOG is heated inline immediately before the centrifuge rather than heating the entire tank.
65°F → 200°F at 50 GPM
Provides the elevated feed temperature needed for improved centrifuge separation and product recovery.
~2,975 lb/hr Design Steam Requirement
Steam is applied directly to the process stream instead of heating and maintaining temperature in a large tank.
0.8 PSI Slurry Pressure Drop
Minimizes additional load on the FOG pumping system.
~16 Months With No Required Heater Maintenance
Eliminates the recurring plugging and fouling experienced with the previous tank sparger.
Estimated Payback of Less Than One Year
Based on the customer’s assessment of product recovery, energy, and maintenance benefits.
Nine Additional Plants Planned
Following the successful initial installation, the customer plans to implement the same ProSonix I-Series solution at nine additional facilities.