FOG Feedstock Filtration System

oil and gasrenewable fuelsFOGbag filtrationmulti-skid systemsfeedstock conditioning

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Project Overview

A renewable fuels producer in Louisiana needed bulk filtration for fats, oils, and grease (FOG) feedstock sourced from industrial waste streams. The filtration system had to protect downstream equipment, manage high solids and variable viscosity, and integrate cleanly into an existing plant layout with limited space.

Customer relied on Fil-Trek to define the filtration approach, select the media, size the housings and system, and manufacture. All of this work was completed in-house by Fil-Trek, leveraging our end-to-end design and manufacturing capabilities.

Project Requirements

Service: fats, oils, and grease from industrial waste streams, used as renewable fuels feedstock.
Duty: bulk removal of suspended solids and debris upstream of downstream refining equipment.
Particle removal: remove particles larger than 10 microns.
Layout: multiple housings on skids, with common inlet, outlet, and drain headers, matched to plant piping and structural modules.
Repeatable design: same vessel and filtration concept duplicated across several skid sizes for different flow rates and services.
Operator access: safe, direct platform access for bag changeouts, with minimal manual effort and no loose tools for opening closures.
Fabrication: butt-welded construction, full NDE and PMI per project specification, with allowance for field insulation.
Structural integrity: skid and manifold design verified for operating, lifting, transport, and wind & seismic loads.

Fil-Trek Solution

Fil-Trek designed and supplied a multi-skid, multi-bag filtration system using LP Series multiple bag housings and MeraFelt filter bags. The system combined customized vessel design with different skid sizes.

To match the plant piping and the required turndown, Fil-Trek supplied three skid types:

Two skids, each with three LP Series housings in series.
Two skids, each with four LP Series housings in series.
Two skids, each with six LP Series housings in series.

Each skid was built with:

Common inlet, outlet and drain manifolds tying all housings together.
Nozzle orientations and elevations set for direct tie-in to plant piping.

Filtration media selection

The FOG feedstock required a combination of bulk solids removal and stable differential pressure across a viscous, sometimes inconsistent stream. Fil-Trek specified:

Filter type: MeraFelt depth filter bags, Size 2.
Media: Polyester, selected for compatibility with FOG and expected cleaning chemicals.
Rating: 10-micron.

Across 26 housings at 6 bags per housing, the installed capacity is 156 bags in service. For initial operation and commissioning, 500 filter bags were supplied as part of the package, giving the plant sufficient spares for early optimization of changeout intervals.

Operator-friendly and ergonomic design

Fil-Trek incorporated:

Spring-assisted head lifts on each housing (slam-free design), reducing the manual effort required to operate the lids.
T-bolt style, tool-less closures that do not require impact wrenches or hand tools to open and close the vessels.
Skids were designed with galvanized, heavy-duty serrated grating to provide slip-resistant walking surfaces.
Platforms were placed between housings so operators can stand directly adjacent to each vessel during bag changeout.
Step heights and platform elevations were selected to keep bag sealing surfaces within a comfortable ergonomic working envelope.

Tailored Custom Solution to Meet Specifications:

Design was configured specifically for this FOG duty along with the customer’s specifications.

FEA was performed: to evaluate skid designs per operating loads, wind and seismic loads; to evaluate the effect of piping loads on vessel nozzles and check local stresses at nozzle and support intersections.
Butt-welded vessel design.
NDE: RT, PMI, LPI.
Surface preparation and painting followed the customer - specified coating system.
Vessels were stenciled with equipment tag numbers and marked for center of gravity to simplify handling and installation.