High‐speed reciprocating compressors, driven by natural gas engines or electric motors, provide the advantages of lower capital cost, shorter installation time and compactness. They have become the most common equipment type applied in the upstream and much of the midstream natural gas compression markets.
However, as high‐speed (≥700 rpm) engine and electric motor‐driven reciprocating compressor packages have been applied, concerns often arose with regard to efficiency, vibration, pulsation, controls, ancillary components and systems, pipeline throughput and diagnostics. Existing industry specifications are of limited value for the purposes of procuring, designing and applying high‐speed compressor packages. API 618, intended for low‐speed process compressors, is generally too complex, much of it is not applicable to high‐ speed compressors, and it lacks enough detail in some important areas. Its pulsation and vibration standard only applies to low‐speed compressors, leaving confusion in the marketplace about what standard should be applied to high‐speed units. In the absence of a standard, many units are fabricated without a proper analysis. In particular, the range of potential operating conditions is typically not adequately explored during the selection, procurement or manufacturing processes. The former API 11P (no longer in print) and the current ISO 13631, intended primarily for field gas compressors, provide no in‐depth guidance in many of the areas of concern. Neither fully provides the more comprehensive direction required.
To address this issue, in October 2013 a new GMRC Guideline for High‐Speed Compressor Packages for Natural Gas Transmission & Storage Applications was released for large horsepower (≥2000 hp), high‐speed (≥700 rpm) engine and electric motor‐driven reciprocating compressor packages. Then, in June 2015, a new Guideline and Recommended Practice for Control of Torsional Vibrations in Direct‐Driven Separable Reciprocating Compressors was issued. Both of these Guidelines were the result of GMRC research programs led by ACI Services Inc. as the contractor, and they have been well‐received by the industry. A new 3‐day Short Course covering the content of the 2013 Gas Transmission and Storage Package Guideline was launched in June 2015; and a new 3‐hour short course covering the content of the 2015 Torsional Guideline was developed and first introduced at the 2015 GMC.
The aforementioned GMRC Guidelines are useful for field gas or upstream compression applications, however they do not address a number of key application issues. The upstream compression sector applies higher‐speed (up to 1800 rpm) reciprocating compressor packages that are generally under 2000 hp. Field gas applications have a number of characteristics that are not covered in the 2013 Guideline. These include the need to handle wet gas, dirty gas, and wider variations in gas analysis including sour, CO2 and N2 content; on‐skid fuel gas conditioning; high pressure ratios requiring multiple stages with intercooling; engine accessory end drives for auxiliary equipment; portability; outdoor packages; and integrated enclosures for cold weather packages. In addition, a tutorial on efficient operating practices and current guidance on best practices for reducing greenhouse gas (GHG) emissions would be helpful for field gas compressor packagers and operators.
Accordingly, this is a report of Phase II of a three‐phased program that adds some limited updates to the 2013 Guideline (Phase I) and develops a new GMRC High‐Speed Compressor Package Guideline for Field Gas (Upstream) Applications (Phases II and III). Phase II is the project investigative effort, which surveyed the industry to determine needs, best practices and required content for the new Guideline. The new Guideline will develop a set of guidelines and recommended practices for high‐speed reciprocating and screw compressor package selection, integration, design, installation, commissioning, and operation. While portions of the final document may be applicable to other applications, the principal use is targeted for field gas and upstream gas processing compressor applications. The document will provide the end user with more reliable procedures and references for selecting, specifying, procuring, applying and operating high‐speed units with more predictable and reliable results, and it will provide packagers with a more comprehensive and detailed specification for designing and building high‐speed compressor packagers that meet customer and equipment OEM expectations.