The heat exchanger and the production pump are two of the most operationally critical and physically demanding pieces of equipment in a geothermal power facility, and they share a common vulnerability: both depend on the cleanliness of the fluid passing through them to deliver the performance and service life their specification assumes. When the fluid carries particles, scale precursors, and mineral deposits at the concentrations typical of Philippine geothermal brine, the gap between the equipment’s design performance and its actual delivered performance over time is largely a function of how well the upstream filtration system manages that particle and scaling load.
Facilities that manage geothermal brine filtration well protect capital equipment worth orders of magnitude more than the filtration system itself. Facilities that do not manage it well accumulate fouling and wear damage on their most expensive and most operationally critical equipment, often without a clear line of attribution back to the upstream filtration specification that allowed it to happen.
What Particle-Laden Brine Does to Heat Exchangers
Geothermal heat exchangers, whether plate-and-frame or shell-and-tube designs, operate by passing hot geothermal fluid on one side of a heat transfer surface and transferring energy to the working fluid on the other side. The efficiency of this transfer is a direct function of the cleanliness of that heat transfer surface. As silica, calcium carbonate, and other mineral species deposit on the brine-side surface, they form an insulating layer that degrades heat transfer coefficient progressively from the day the exchanger enters service.
This fouling is not a uniform, slow accumulation. Silica precipitation rate in geothermal brine is a strong function of temperature and pH, meaning fouling can accelerate during certain operating conditions and decelerate during others, producing unpredictable degradation in heat exchanger performance that makes capacity planning difficult. Particle deposition, distinct from chemical scale, adds a mechanical fouling component that further reduces effective heat transfer area.
The consequence is reduced power generation from the same geothermal resource, requiring either more wells to make up the lost output or acceptance of lower plant capacity. Cleaning a fouled geothermal heat exchanger requires taking the unit offline, which affects generation, and in severe cases requires acid cleaning or mechanical descaling that is both operationally disruptive and chemically hazardous. Prevention through effective upstream filtration is substantially less costly and disruptive than the cleaning cycles it avoids.
What Particle Ingress Does to Pump Components
Production pumps, reinjection pumps, and circulation pumps in a geothermal facility operate against the combined demands of high-temperature, chemically aggressive fluid and the mechanical stress of continuous operation under the process pressures involved. The pump components most sensitive to particle ingress are the seals and the wear ring surfaces, both of which depend on maintaining close mechanical tolerances that abrasive particles erode.
Sand, silica particles, and mineral precipitates in pump service act as a grinding compound between the rotating shaft and the stationary seal faces, and between the impeller wear rings and their mating surfaces. The progressive wear this causes increases internal clearances, reducing pump efficiency, increasing power consumption per unit of flow produced, and eventually requiring overhaul or replacement of components that would have served their full design life in clean fluid service.
Seal failure in particular carries consequences beyond the pump itself, since a failed pump seal in geothermal service releases hot, chemically aggressive fluid that creates safety exposure and contamination of surrounding equipment. Seal life in geothermal service is a direct function of particle load in the pumped fluid, and maintaining that particle load within acceptable limits through upstream filtration is the most effective intervention available for extending seal service intervals.
Bollfilter’s Role in Protecting Downstream Equipment
Bollfilter has more than 13 years of specific geothermal filtration experience, with installations protecting heat exchangers and pumps in geothermal facilities across Europe. The automatic backflushing filter Type 6.18 is the primary Bollfilter product for geothermal water and process water protection, providing continuous self-cleaning filtration that maintains particle removal performance under the variable particle load conditions geothermal brine presents, without the process interruptions that manual filter maintenance requires.
The filter’s placement in the system, upstream of the equipment it protects, determines both what it catches and what its failure to perform adequately allows downstream. Correct placement at the inlet to each heat exchanger or pump that requires protection, rather than a single point of filtration that may be bypassed by branch flows reaching individual equipment, ensures that the full particle load is intercepted rather than only the portion passing through a strategically placed but incompletely covering installation.
Ultra Power distributes Bollfilter’s automatic filtration range in the Philippines. For geothermal facility engineers evaluating the filtration strategy on existing installations or designing protection for new equipment, reviewing the actual particle load reaching heat exchangers and pumps, rather than the nominal specification of upstream filters, frequently reveals the gap between where filtration performance should be and where it actually is.
Have a Project to Discuss?
Our engineers are ready to help you specify the right solution for your facility.
Contact Us