The Enalysis software provides YELLOW (Warning) and RED (Severe) flags to identify compressor limits and allow for action to be taken to prevent possible damage to the compressor package. Reciprocating compressor packages are restricted to operating under conditions that ensure the mechanical ratings of the compressor are not exceeded. Exceeding one or more limits of the compressor can result in catastrophic failures requiring expensive repairs and resulting in costly downtime. Yellow warning flags indicate that a limit is being approached and red severe flags indicate that a limit has been reached.

This post will provide Detechtion Technologies’ recommended steps for troubleshooting Blowby and “Gauge Maintenance”. These two concepts, along with their possible causes, were discussed in detail in E-Tips 1.3 - 1.7.

“Gauge Maintenance” is the term used by Detechtion Technologies when the monitored compressor parameters are thermodynamically impossible according to the Enalysis software model. This occurs when the calculated expected discharge temperature is greater than the actual measured discharge temperature for a cylinder.

Blowby can result without any physical damage to wear components or unaccounted pressure drops. Improper valve springing can lead to valve flutter, allowing gas to recirculate each compression cycle. Alternatively, high rates of lubrication can lead to oil coating the valve plate and seat, which leads to an increase in pressure differential required to break the stiction when the two surfaces separate. Both are examples of inefficiencies in the compression process and can cause Blowby to flag on an Enalysis report.

This post will look at how unaccounted pressure drops effect the Blowby calculated in an Enalysis report from Detechtion Technologies. Enalysis requires a suction and discharge pressure and temperature for each cylinder in order to calculate the thermodynamic performance of that cylinder. While suction temperature, suction pressure and discharge pressure can be common for all cylinders on a compression stage, the discharge temperature must be unique to each cylinder. The location of each these values is important when it comes to understanding and troubleshooting Blowby on an Enalysis report.

As mentioned in the last E-Tip, “Blowby” is a term used by Detechtion Technologies to quantify inefficiencies in the compression process. Blowby is an indication of the health and efficiency of the valves and piston rings inside every cylinder. In short, it is a measure of the number of molecules of gas that are being re-circulated and recompressed within a cylinder. As more gas is re-circulated and recompressed, the temperature rise across the cylinder increases, more horsepower is required and the cylinder’s capacity to compress gas decreases. There are several things that can result in Blowby to flag on an Enalysis report. This article focuses on the effect of damaged cylinder wear components. While the most common culprits are valves and piston rings, this also includes piston rod packing, VVCP seals, valve gaskets, etc. Essentially, any component that is meant to prevent the passage of gas under normal working conditions, could lead to Blowby when it becomes damaged.

More than two thirds of the unplanned downtime of reciprocating compressors can be attributed to issues with the wearing components in a cylinder. Early identification of these issues combined with a reliable quantification of the level risk and impact on production and/or power consumption allows for proactive scheduling of maintenance. This may mean stretching out the runtime despite rising discharge temperatures in order to align the work with a prescheduled maintenance interval or changing out components earlier to avoid future unscheduled downtime oil field assets.