Centrifugal compressors in Oil & Gas

Turbomachinery Magazine, November/December 2021,

The latest products, services, and trends including hydrogen compression, carbon capture, and bigger machines.

Centrifugal compressors lie at the heart of oil and gas and industrial operations. They represent one or the most vibrant areas of the turbomachinery landscape and are supported by a thriving vendor community. These include Baker Hughes, Howden, Siemens Energy, Elliott Group, Atlas Copco Gas & Process, Kobelco, Mitsubishi Compressor, Man Energy Solutions, Ingersoll Rand, and Sundyne Let’s hear from each of them concerning the latest trends, products, and services.

BAKER HUGHES

“The energy supply chain, including natural gas and hydrogen, requires varying levels of compression, depending on the type of gas and the application,” said Leonardo Baldassarre, Executive General Manager, Engineering, And Platform Leader, Compressors, Pumps And Expanders, Turbomachinery & Process Solutions, Baker Hughes.

Accordingly, Baker Hughes provides centrifugal compressor and pumps as well as reciprocating compressors. Its portfolio spans from horizontally split machines to barrel type. They can range from almost atmospheric compressors to very high pressure (up to more than 820 bars for centrifugal or above 2000 bars for reciprocating compressors) and from a few hundred cubic meters per hour to several hundred thousand cubic meters per hour flow. They can also accommodate any type of gas, from H2 to heavy refrigerating gases and from almost inert gases to very corrosive ones.

For example, the Baker Hughes High Pressure Ratio Compressor (HPRC) is a high-speed rotor-compressor with a small footprint and high-performance stages for various applications, including hydrogen. These compressors can spin impellers at very high speeds, thus reaching high pressure ratios while handling very large flows.

“Today, we are working to leverage this architecture to increase impeller tip speeds, particularly for H2,” said Baldassarre. “This requires the development of high strength alloys coupled with an aero and mechanical impeller design aimed to minimize stresses.”

Typically, components are tailored to customer needs and applications. The OEM designs each compressor with a mix of custom and standardized components for a specific plant and for a specific gas composition, flow, and pressure.

In addition, the company is focusing on how to maximize the use of any energy cascade through optimized bottom cycles like sCO2. Another area of attention is connected to energy storage either associated with compressed gas or with batteries.

“Today, we are working to leverage this architecture to increase impeller tip speeds, particularly for H2,” said Baldassarre. “This requires the development of high strength alloys coupled with an aero and mechanical impeller design aimed to minimize stresses.”

Typically, components are tailored to customer needs and applications. The OEM designs each compressor with a mix of custom and standardized components for a specific plant and for a specific gas composition, flow, and pressure.

In addition, the company is focusing on how to maximize the use of any energy cascade through optimized bottom cycles like sCO2. Another area of attention is connected to energy storage either associated with compressed gas or with batteries.

SIEMENS ENERGY

Siemens Energy offers:

Siemens Energy offers: Single-shaft centrifugal compressors with features such as: dry gas sealing systems; up to four process stages; up to 10 impellers per casing; intercooling, side streams, and extractions; standard oil lubricated or active magnetic bearings; optional adjustable inlet guide vanes (IGV); and ultra-low temperature service.

Pipeline compressors with features such as: Flange sizes (20’’, 24‘’, 30’’, 36’’, 42’’); max inlet flow rates of up to 106,700 m³/h); maximum working pressure of up to 2250 psi; Up to five stages; and a maximum power rating of up to 75,000 BHP / 56 MW).

Custom-designed compressors covering performance requirements outside the above ranges such as those required for compressor head stations and natural gas storage and withdrawal operations.

Integrally geared compressors: Multi-shaft machines (several pinion shafts with two impellers each are arranged around a central bull gear). For each pinion shaft a combination of shaft speed and impeller size must be realized. All impellers are of overhung design and can be fitted with adjustable inlet guide vanes in front of each impeller. Inter-stage cooling of the gas stream can be done after each impeller discharge. The combination of these features allows for high volume flows, energy efficiency under part load, and a compact design. For small- to medium-size compressor sizes, Siemens Energy offers a package design. The package includes the compressor, driver, process gas coolers, lube oil console, process piping, and all tubing and wiring. This design leads to reduced on-site installation time. For large-size units, all main train components are delivered separately on site and installation is on a concrete foundation.

The RF compressor product line, for example, is strong in the midstream pipeline market and comes in a variety of frame sizes. They are available in beam-style (RFBB) and axial inlet (RFA) configurations. Components such as casings, bearings, shafts, dry gas seals, and the interface with package hardware are standardized. The flowpath is customized for each project’s specific process conditions to achieve high efficiency. The RFA model’s single impeller design limits internal flowpath losses. The VIGV option is also available to change the operating map as process conditions change. Another feature is single dry gas seals; this feature can cut fugitive emissions in half compared to the standard bearing design.

The company is seeing three major trends in the market right now: decarbonization; methane reduction; and standardization. With the focus on decarbonization, there is more attention being given to train efficiency because it has a direct impact on compressor efficiency: a more efficient compressor burns less fuel. For methane reduction, using dry gas seals with the RFA compressor model can slash primary vent leakage.

“We also offer a capture and recompression solution, which is more economical with the RFA model due to low leakages,” said Scott Tackett, Sales Director, Midstream Compression for Siemens Energy Industrial Applications Business.

MAN ENERGY SOLUTIONS

MAN offers a wide range of horizontally and vertically split centrifugal compressors, radial isotherm compressors, gear-type compressors, and integrally sealed compressors.

MAN’s High-Speed Oil-Free Integrated Motor compressor (HOFIM) has a high-speed motor, driving a one or two multi-stage centrifugal compressor levitated by active magnetic bearings. The unit is hermetically sealed and encapsulated. Due to the modular concept, it provides flexibility in component and process configuration. Components usually seen on conventional topside compressor solutions such as gearbox, lubrication oil system, instrumentation, and valving are not required. This results in a compact design that facilitates fast installations. The motor power has a range from 1 to 18 MW, depending on which frame size it is used.

HOFIM units are used in subsea compression applications as well on platforms, or onshore applications. The technology is also used in the electro-thermal energy management system MAN ETES (Electro-Thermal Energy Storage). MAN ETES is a tri-generation energy management system that uses i.e., surplus renewable electricity to generate heat and cold for storage in insulated reservoirs. For this use case, the electrothermal process allows the distribution of the generated heat and cold to users according to demand and margins, but also offers the option of converting it back into electricity. The HOFIM compresses the CO2 working fluid to its supercritical state at 140 bar and around 120°C.

MAN has delivered two subsea HOFIM units for Equinor’s Åsgard subsea compressor station in Norway. Since operation start in 2015, they have performed with an availability of above 99%. “Subsea compression requires an extremely reliable remotely operated compressor on the seafloor,” said David Kodz, Solution Manager Subsea & Unmanned Compression + ETES at MAN Energy Solutions. “The compression unit is qualified for wet gas operation and significantly reduces the process complexity by eliminating liquid separation. The technology allows for fully remote and unmanned operation.”

Beyond subsea, MAN operates in many other markets. In CCUS, MAN supplies the compression technology for purifying CO2 and storing the CO2 in a depleted oil field or a saline aquifer. It also operates in liquid air energy storage (LAES) and molten salt energy storage (MOSAS).

ATLAS COPCO GAS AND PROCESS

Atlas Copco Gas and Process provides both integrally geared and non-geared centrifugal turbocompressors for hydrocarbon processing, power generation (both renewable and conventional), and industrial gases. The integrally geared compressors cover pressures up to 205 bar (up to eight stages), flows up to 500,000 m3/h, and have maximum input power of 35 MW. The Compander is also integrally geared: Here compressor and expander functionalities are installed on one single gearbox and skid. The Compander is used in many hydrocarbon processing applications, including small-scale LNG, chemical/ petrochemical, as well as supercritical CO2.

For the non-geared compressors, Atlas Copco Gas and Process provides solutions for polyolefines and main air, respectively. These compressors for PP/PE handle flows up to 65,000 m3/h, with a maximum input power of 10 MW and maximum pressure of 45 bar. The company’s non-geared compressors for main air handle flow volumes of up to 500,000 m3/h, with a maximum input power of 30 MW.

“The overarching trend in the industry is decarbonization, which impacts many areas of centrifugal compression and is driving advancement,” said Ulrich Schmitz, Atlas Copco Gas and Process.

For hydrogen transportation, the company already has a cryogenic (-253°C) integrally geared compressor solution for hydrogen carrier vessels. For applications where the hydrogen content is 100% and the gas is non-cryogenic, compressor suppliers are focusing a lot of their R&D efforts on developing efficient compression technology, said Ulrich Schmitz, Marketing Manager at Atlas Copco Gas and Process.

ELLIOTT GROUP

Elliott Group provides the following centrifugal compressor lines:

Single-Stage: Elliott’s TC and PH compressor product lines are single-stage overhung compressors. Their typical application is in services that require lower head requirements than that of a multi-stage between-bearing compressor. The low maintenance design with axial flow inlet and ability for rear pull rotor removal make these compressors a good fit for processes in dirty and corrosive applications such as petrochemical plants, refineries, natural gas processing, coal gasification, and ethylene oxide/ethylene glycol (EOEG). To further expand peak operating range, adjustable inlet guide vanes can be installed to improve performance for changing conditions or partial load operation. Single-stage compressor designs are standardly available with inlet flows up to 90,000 ACFM and an 800 PSI discharge rating.

Multi-stage: The M and MB compressor product lines are between-bearing centrifugal compressors. They are typically used in hydrocarbon markets including oil & gas production and processing, petroleum refining, petrochemical processing, cryogenic refrigeration, and industrial gases. Elliott’s M line of compressors are horizontally split while the MB product line is a vertically split configuration. M-line compressors are typically applied for lower pressure and fouling services. The MB-line is better suited for high pressure and clean gas service. Both of these compressors share major components of rotor design, bearing and sealing options, and aerodynamics staging, ensuring reliability. While utilizing many standard components, each is engineered to order based on customer specifications to optimize aero performance, rotordynamics, and reliability. Elliott Group’s M and MB line of compressors provide compression solutions for inlet flows from 1700 to over 850,000 acfm and pressures up to 10,000 psi.

The EDGE M-line compressor is the most commonly applied compressor in Elliott’s product line. This model is available in 15 standard frame sizes. The horizontally split casing makes this compressor a good fit for dirty, corrosive or fouling services that provide maintenance challenges to vertically split compressors. The frame size uses standard casing and endwall designs, while the aerodynamics components are custom tailored to the application. The EDGE compressor design uses a fully scalable aerodynamics flow path to allow scaling across all frame sizes. Stage line ups are available in straight through, sideload, isocooled, back-to-back, and double flow configurations. Advances in stage and nozzle design have increased flow coefficients beyond 0.25 and increased capacity per frame with the largest double flow compressor capable of volume flows in excess of 850,000 cfm. M-line compressors allow end users to achieve greater capacity without the typical frame increase of previous generation compressors without negatively impacting reliability or serviceability.

“Bearing and seal systems are being improved to reduce fugitive emissions and reduce or eliminate lubricating oil,” said Ronald Josefczyk, Director of Global Engineering for Engineered Products, Elliott Group.

He also noted that many processes are focusing on casing and footprint reduction. Single large trains of equipment have lower efficiency losses per volume and points for fugitive emissions than parallel compressor configuration. Further, Elliott continues to extend the flow capacity of its product lines through full 3D high-flow stage design facilitating economy of scale improvement.

MHI COMPRESSOR

MHI Compressor Group manufactures and services API 617 beam-style and integrally geared (Part 2 & 3) centrifugal compressors at its Hiroshima, Japan and Pearland, TX facilities. It offers a range of custom designed compression varying from low pressure / high flow compressors (horizontally split) to high pressure / low flow compressor (vertically split). This includes upstream, such as FPSOs and CO2 reinjection, to mid and downstream in NGL processing, LNG, ethylene, ammonia, propane dehydrogenation (PDH), carbon capture, refining, and power generation.

“Globally we’re seeing a rise of energy transition related projects that support various decarbonization objectives,” said Clayton Jurica, MHI Compressor.

In addition, the company is strong in syngas compression. Synthesis gas, a relatively low mole weight gas mixture, plays a key role in many petrochemical plants such as ammonia and methanol. Based on the low mole weight and compression ratio capabilities, there is a requirement for many stages of compression, sometimes handled in multiple compressor bodies along with intercooling, in order to provide adequate discharge pressure and temperature for the overall process requirements. In North America, the company reports positive momentum on several blue ammonia projects in which the owner intends to export the ammonia to utilize as a fuel or as a carrier for hydrogen. There is also more interest in energy transition and decarbonization.”

“This covers the entire energy value chain such as carbon capture at new and existing facilities as well as plants utilizing electrolysis, Autothermal Reforming (ATR), and/or Methane Pyrolysis to produce hydrogen and ammonia,” said Clayton Jurica, Director of New Unit Equipment at MHI Compressor International.

INGERSOLL RAND

he Ingersoll Rand Turbo-AIR and MSG integrally geared centrifugal compressor product lines provide flexible, high-performance oil-free compressor technology for industries powered by air or gas. Since they are oil-free, they are a good fit for industries that need to avoid oil contamination for product safety or quality. They are equipped with features to reduce energy expenditure and other costs.

  • Maestro Controllers continuously optimize the operation of the compressor by monitoring operating parameters and adjusting discharge pressure and outlet flow to match the user’s demand for a given application.
  • VIGVs offer efficient flow control.
  • Non-contacting seals ensure energy efficiency does not diminish over time.
  • A pinion bearing, gear design and stainless-steel compression elements deliver durability.
“The cost of power over the life of the compressor will dwarf the capital cost in most cases,” said Sam Gooldy, Ingersoll Rand.

For example, the Ingersoll Rand MSG TurboAIR NX 5000 is an oil-free air and nitrogen compressor that provides optimized energy efficiency and operational flexibility. It generates oil-free air or nitrogen that meets IS0 8573-1 standard. The VIGV design enables a 35% turndown range, enabling it to be used in various demand scenarios to compress air or nitrogen for a process. During periods of low or fluctuating demand, the operator can adjust production without the need to shut it down or deploy energy-wasting blow-off.

While reliability measured in decades as an absolute, we see today’s compressor owners focus more and more on efficiency as the first among equals. As power costs seem to be on a perpetual march ever higher, we don’t see this changing any time soon.

Sam Gooldy, Senior Global Product Manager at Ingersoll Rand, said that a couple of years ago, a typical 7,500 cfm compressor discharging at 125 psig would require about 1500hp of power at full flow. The Turbo-AIR NX can achieve that same flow and pressure, but it only consumes 1400hp.

HOWDEN

The Howden Centrifugal Compressor group includes brands such as Turblex, HV-Turbo, Kühnle, Kopp & Kausch, Bryan Donkin, CKD, and Roots. Each brand offers single-stage and multi-stage centrifugal turbocompressors. Dual vanes are available on many of the single-stage models, and several have the option for both inlet guide vanes and variable diffuser vanes for process power optimization. A few typical applications include process air for environmental processes like wastewater, combustion air, compression for sulfuric acid plants, mechanical vapor recompression (steam compression), and process gas compression. These models can be configured to meet API-617 and API-672 specifications.

he Roots OIB single-stage centrifugal compressor, for example, has its beginnings in the early 1930’s. It can handle a wide range of applications from standard industrial to high specification API type process requirements. The OIB standard design features hydrodynamic tilting pad radial bearings and a double acting tilting pad thrust bearing along with a variety of seal options.

According to David C. Hokey, Howden Roots Turbo Product Leader, many companies are exhibiting interest in digital solutions for plant equipment partly due to the need for crews to look ahead to schedule maintenance.

Howden Uptime serves the need for digital services such as the digital twin. Using physics data on how customer equipment operates and responds to the environment, as well as data provided by the sensors, the digital twin is used to analyze and simulate real world conditions, including response to changes, and how to improve operation.

SUNDYNE

Sundyne offers four different centrifugal compressors. These are single- and multi-stage designs for API 617 as well as fit-for-purpose applications in oil & gas production, natural gas processing, power generation, hydrocarbon processing, and chemical processing. Each model is custom-built to provide pulsation- and vibration-free operation, and to deliver oil-free process gas with zero emissions.

The Sundyne LMC vertical integrally geared process gas compressor is a fit-for-purpose design that offers single-stage compression with: Flows to 3,550 acfm (6,000 am³/hr); maximum working pressure 1,440 psi (100 bar); maximum Speed: 34,200 RPM; temperature range -200 to +500oF (-130 to +260 o C); and a design that is 25% the size of reciprocating, barrel, or rotary screw compressors.

The Sundyne BMC integrally geared process gas compressor is an API 617 horizontal single-stage compressor that provides: Flows to 3,550 acfm (6,000 am³/hr); maximum working pressure 1,440 psi (100 bar); maximum speed: 34,200 RPM; and a temperature range of -200 to +500oF (-130 to +260 o C).

The Sundyne LF 2X80 base mounted integrally geared multi-stage process gas compressor can be outfitted to meet API standards or engineered as a fit-for-purpose compressor. It has one-to-four stages of centrifugal compression on a single gearbox and delivers: Flows to 6,000 acfm (10,200 am³/hr), maximum working pressure 1,440 psi (100 bar); maximum speed: 32,000 RPM (60 Hz), 32,000 RPM (50 Hz); and temperature range of -200 to +500oF (-130 to +260 o C).

The Sundyne LF 2000 API 617/ISO 10439 base-mounted, integrally geared, multi-stage process gas compressor is API-compliant. It features one-to-six stages of centrifugal compression on a single gearbox, providing: Flows to 10,000 acfm (17,000 am³/hr); maximum working pressure 5,000 psi (350 bar); maximum speed of 42,000 RPM (60 Hz), 42,000 RPM (50 Hz); and temperature range -200 to +500oF (-130 to +260 o C).

The Sundyne LF 2000 multi-stage centrifugal compressor (known as a Pinnacle) has been deployed for midstream, hydrocarbon processing, and chemical manufacturing applications. This includes fuel gas boost for power generation, hydrogen recycle, mole sieve dehydration, regeneration of demethanizers, waste gas, and specialty chemical production. Its horizontal configuration features a modular baseplate that simplifies skid packaging and installation. Packaging and instrumentation are customizable. Sundyne Pinnacle machines are built to run continuously for up to 7 years without interruption. These machines are being deployed as feed gas compressors for amine scrubbing applications to reduce CO2 from flue emissions. With Amine scrubbing, CO2 and other sour impurities in the gas require stainless steel or NACE-compliant corrosion-resistant materials. Flash conditions due to heating and cooling processes require high head. Pinnacle compressors meet these requirements.

he company has observed an increase in inquiries and business for single- and multi-stage compressors in transportation of green hydrogen (with producers in the Middle East and Africa with large solar infrastructures), cleaner synthetic fuels and feedstocks (with companies in Europe to process hydrogen), CO2 and methanol to make fuels for industrial vehicles and cleaner feedstocks for chemical manufacturing. Finally, Sundyne expanded its testing facilities to mimic the specific manner in which a machine will operate once it’s deployed.