Rethink Your 1st Stage Suction Scrubber
Filtration and Separation Basics by JCI
In an earlier post (Waxes and Paraffins) we discussed the challenges that result from the presence of waxy hydrocarbons, paraffins, and asphaltenes in natural gas, and the headaches that can result. Often, owners find out too late that these contaminants will pose a significant problem for operations and that their compressor station or production facility is not properly equipped to handle such contaminants.
On any compressor package, the suction scrubbers are designed to separate condensate and water from natural gas before entering the compressor. Most understand what will happen when you attempt to compress an incompressible fluid, the results are usually catastrophic. The first stage scrubber is particularly critical, since it is the final separation device upstream of the compressor and will typically be exposed to the highest volume of liquids and most challenging contaminants, when compared to the second, third, or fourth stage scrubbers. It is at the first stage where we see the highest frequency of failures for compressors.
Conventional suction scrubbers manufactured by JCI include a vertically mounted mesh/vane mist eliminator. In normal, clean service, these cost-effective suction scrubbers will provide reliable, efficient removal of entrained liquids from natural gas. Refer to Figure 1 for a conventional compressor suction scrubber configuration.
Figure 1 - Conventional Compressor Suction Scrubber
Figure 2 - Compressor Valves with Wax Build-Up
Through the evolution of hydraulic fracturing in the natural gas industry, and the economics driving the production of liquid rich natural gas, we are seeing more and more cases of the presence of waxy hydrocarbons, paraffins, and asphaltenes in natural gas. As a result, the heavier hydrocarbon components (i.e. waxy hydrocarbon components or paraffins) tend to stick to the mesh and vane devices, building up over time and resulting in carryover into the compressor. Figure 2 shows compressor valves that were damaged in service due to wax buildup. Not only are these valves expensive, but changeouts result in lost revenue while the compressor is shut down for time intensive and expensive repairs.
JCI has seen many similar instances of compressor failures and as a result, we believe that it is time that you rethink your first stage suction scrubber design. JCI has a patent pending cyclonic suction scrubber that is proven to efficiently separate these harsh contaminants, resulting in reliable, low maintenance operation. JCI’s cyclonic suction scrubber design, depicted in Figures 3a, 3b, and 3c, can be utilized in new compressor packages with either an inline orientation, offset side in / side out, or side in / top outlet orientations. Existing suction scrubbers can easily be replaced without the need for expensive piping rework. Many times, scrubbers can be replaced in less than a day, approximately the same time it takes to replace damaged suction valves. As an added benefit, JCI’s cyclonic suction scrubber can be designed for additional flow capacity in the same vessel shell size, which makes it an ideal option for debottlenecking an existing compressor package.
