NGL Unloading Compression Systems
NGL Unloading compressor skid for installation at a fractionation facility in Ohio.
The client was looking for an automated compression skid that would be designed to offload transport trailers delivering a Propane/ Butane mix (“Transmix”) as well as a heavier hydrocarbon mixture (“Light Condensate”).
The LACT Skid Off-load
Evaluating the customer’s needs, the facility layout, and the desired result the initial step was ti design a system that required a metered offload for custody transfer. This LACT skid flow rate is controlled by a VFD (variable frequency device) to control the compressor speed. The system is sized to offload the Transmix at a maximum rate of 400 gpm and the Condensate at a maximum rate of 300 gpm.
Choosing the Right Gas Compressor
For this application, we chose a Corken T891 double-acting, oil-free industrial gas compressor. Our reasoning; the gas compressor included a purge system to eliminate fugitive emissions that can result from worn or damaged seals. We knew the customer wanted to maintain the environmental aspects of the area as much as possible. Due to the gas compositions, we also included an oversized suction scrubber with two ultrasonic level switches to prevent liquid “slugging”. Liquid slugging is the result of medium to large quantities of entrained condensed gas or condensate entering the compressor. These liquids are not compressible and there is not enough space in the cylinder on the compression stroke to accommodate them. This results in tremendous rod loads and hydraulic pressure inside the compressor which can lead to damage and possible catastrophic failures.
NGL Unloading Compressor System Features
The skid also includes pressure and temperature switches and transmitters for automated start/stop function as well as equipment safety. Our selection of Class1, Div.2 instruments was to meet the area classification requirements. All of the piping was welded and tested in accordance with ASME B31.3 standards and tested at the fabrication shop prior to shipment to the site.
How does the NGL Compressor LACT Skid work?
The equipment has been on site for six months. The commissioning of the NGL gas compression system was done with support of the S&S Technical Electrical Engineers to ensure all equipment worked properly after the transport and site install. The operations personnel were trained in the use of the LACT skid to maintain the custody transfer and acquisition. The gas compression system has been working as designed and requested by the customer. They are anticipating the need for another NGL gas compression system at the site within the next 8-12 months.