Iran breaks new ground with locally manufactured high-tech turboexpander despite sanctions

By Ivan Kesic

The unveiling and successful commissioning of Iran’s first domestically produced 3.5-MW turboexpander equipped with active magnetic bearings at the South Pars Gas Complex marks a major technological milestone, making Iran one of the leading countries in the world to master the production of this sophisticated industrial machinery.

Specialists at the refinery, working in partnership with a domestic knowledge-based company, achieved what had once seemed unattainable under illegal sanctions and severe restrictions on technology transfer: the complete design, manufacture, integration and commissioning of a high-speed turboexpander-compressor equipped with advanced magnetic-bearing technology.

The achievement was not an overnight breakthrough. It was the culmination of nearly four years of dedicated development, drawing on two decades of accumulated expertise in high-speed rotating equipment.

The project was born out of practical necessity. Reliance on foreign suppliers for spare parts and specialized maintenance had created a critical vulnerability for one of the world’s largest gas-processing facilities.

When the Fifth Refinery placed the order, its objective was not a technological showcase, but a dependable domestic replacement for equipment essential to maintaining production stability.

The successful project therefore carries significance far beyond the single machine installed in Unit 105. It represents a broader step toward industrial resilience, technological self-reliance and the development of advanced domestic manufacturing capabilities.

Turboexpander: Machine of precision and thermodynamic efficiency

A turboexpander is not simply another rotating machine in a gas-processing plant. It is a high-speed turbomachine that simultaneously provides deep refrigeration through gas expansion and recovers useful mechanical energy from the pressure drop.

The basic thermodynamic principle is elegant in its simplicity yet formidable in its engineering execution. High-pressure natural gas enters the expansion turbine, where it expands through a turbine wheel.

In an approximately adiabatic and near-isentropic expansion, the gas loses enthalpy, and its temperature falls substantially. The turbine extracts part of this energy as shaft power, which is typically connected directly to a centrifugal compressor on the same rotating assembly.

The recovered mechanical energy is therefore used internally, performing the dual function of producing the cryogenic temperatures required for hydrocarbon separation while simultaneously recompressing another gas stream.

The operating figures of the Iranian machine illustrate these functions with striking clarity.

According to the technical description provided by Mohammad Daneshmandi, head of the turboexpander team at Kavosh Sanat Toos, the machine installed in Unit 105 has a rated power of 3.5 MW and rotates at approximately 12,000 revolutions per minute.

On the expander side, the reported gas pressure falls from approximately 60 bar to 30 bar, while the temperature drops from approximately −30°C to a range of roughly −60°C to −70°C.

On the compressor side, the pressure rises from approximately 27 bar to 32 bar, with a flow rate of approximately 400 tonnes per hour. The first pressure drop, from approximately 60 to 30 bar, is an enormous pressure reduction by ordinary industrial standards.

Instead of dissipating that pressure differential in a throttling device, the turboexpander converts part of the available pressure energy into shaft work.

At the same time, the expansion produces the very low temperature required for cryogenic separation, making it possible to condense and separate heavier hydrocarbon components from the gas stream.

The reported temperature reduction from approximately −30°C toward −60 to −70°C moves the gas into a cryogenic processing regime in which hydrocarbon condensation and fractionation become substantially more effective.

A conventional valve can produce a pressure reduction and associated temperature change, but it does not recover the same useful shaft power.

Technical literature notes that turboexpanders can achieve isentropic efficiencies approaching 90 percent in appropriate applications.

The second half of the machine is equally significant. The recovered shaft power drives a centrifugal compressor, meaning that the same rotating assembly performs two complementary functions: the expander provides the refrigeration and mechanical energy, while the compressor uses that mechanical energy to raise the pressure of another gas stream.

The result is a compact integrated turbomachine rather than two completely independent units.

The Iranian team explicitly presented this as one of the principal advantages of the design, noting that the recovered expansion power eliminates the need for a separate approximately 3.5 MW compressor.

If the pressure drop were handled entirely by throttling, the available work associated with expansion would largely be lost. A turboexpander instead converts part of that otherwise wasted potential into mechanical power, which the compressor then consumes.

In effect, the process uses the pressure differential twice: first to generate refrigeration and shaft work, and then to provide useful recompression.

Magnetic bearings: Technology that sets the Iranian achievement apart

The other major technical feature of the Iranian-made machine is its bearing technology. It is equipped with magnetic bearings rather than conventional oil-lubricated bearings, a design choice that places it at the forefront of turboexpander technology.

At 12,000 rpm, rotor dynamics, vibration control, bearing loads, shaft alignment, thermal effects, and aerodynamic stability become critical design considerations.

Conventional oil bearings require a lubrication system and introduce the possibility of oil contamination, which can be detrimental in cryogenic processing.

Active magnetic bearings, by contrast, support the rotating shaft electromagnetically without physical contact during normal operation. They can also provide sophisticated electronic control of rotor position and vibration.

Active magnetic-bearing systems use electromagnetic actuators together with high-speed control electronics to maintain the rotor in its desired position.

The absence of conventional oil-film contact eliminates the lubrication system associated with traditional bearing arrangements and can reduce some maintenance requirements.

Reports state that the magnetic-bearing system means the equipment practically does not require major overhauls, preventive servicing, or scheduled maintenance after commissioning.

In engineering terms, magnetic bearings can indeed eliminate many wear mechanisms associated with conventional contact or oil-film bearing systems.

They do not, however, make an industrial turbomachine maintenance-free. Magnetic-bearing systems have controllers, sensors, power electronics, and auxiliary or touchdown bearings; turboexpanders also contain seals, rotating aerodynamic components, and other systems that require monitoring.

The defensible interpretation is that magnetic bearings can substantially reduce certain maintenance requirements, rather than eliminating maintenance.

The importance of the magnetic bearing technology in the Iranian achievement can be measured by the exclusive company it has placed Iran in.

With this, Iran has become the fourth country globally capable of producing turboexpanders with magnetic-bearing technology, after the United States, Germany, and France.

This particular ranking should be understood as reflecting the specific combination of technologies and industrial capabilities required for this class of equipment.

Active magnetic bearings themselves are not a new technology; they have been used internationally in turboexpanders for decades, with technical literature recording their adoption in petrochemical applications beginning in the 1990s.

However, the ability to design, manufacture, integrate, and commission a complete turboexpander-compressor system with magnetic bearings under domestic conditions, without dependence on the previous foreign OEM supply chain, is a substantial engineering feat that few nations have mastered.

The global industrial landscape for turboexpanders and related technologies is dominated by a relatively small number of established players.

The active magnetic bearing turboexpander market includes companies such as Baker Hughes, Chart Industries, JCL, Cryostar, Atlas Copco, Maruwa, and Nikkiso, alongside specialized firms like Zhejiang Boxu New Energy Technology and Nanjing Cigu Technology.

In the broader field of magnetic bearing technology, European companies such as Finland's SpinDrive have made significant advances, with SpinDrive securing growth funding in late 2025 to scale its magnetic levitation bearing technology for applications including turbo expanders.

In other words, in addition to the USA, Germany and France mentioned by the project team, there are also Japan and China. However, some of these companies are multinational and there is a strong transfer of technology, so it is not a completely independent national product.

The Iranian achievement therefore does not represent the introduction of entirely new technology but rather the successful domestication of a sophisticated industrial capability that had previously been the preserve of a limited number of technologically advanced nations.

Economic and strategic rationale

The background to the project was a problem with spare parts and dependence on foreign suppliers.

According to Daneshmandi, the Fifth Refinery placed the order approximately four years before the equipment's commissioning because shortages of spare parts for existing equipment represented a threat to production stability.

The project was therefore conceived as a practical replacement capability for an item considered critical to refinery operation.

A refinery does not require only the original purchase of a machine; it also requires spare parts, specialist maintenance, troubleshooting, overhaul capability, and engineering support.

If a critical turboexpander becomes unavailable for an extended period, the consequences can extend beyond the cost of the machine itself.

Local manufacturing can potentially shorten the supply chain, provide access to locally produced spare parts, and allow modifications or repairs to be performed without waiting for an overseas OEM.

The economic argument is also substantial. Iranian reporting estimates the avoided foreign-exchange expenditure associated with the project at approximately €4 to 6 million, reflecting the estimated cost of acquiring an equivalent imported unit and associated foreign procurement.

The project involved cooperation between South Pars and Kavosh Sanat Toos, with support from Iran's Vice Presidency for Science, Technology and Knowledge-Based Economy.

According to the project team, the development of these systems domestically contributed to breaking the constraints of sanctions, and approximately fifty to sixty systems had been installed in the South Pars complex, with plans to expand the number according to the needs of the gas company.

The South Pars application is particularly important because the Fifth Refinery is a large and complex gas-processing facility. The refinery processes gas from South Pars Phases 9 and 10.

A published engineering study of the refinery describes its design capacity as approximately 56.5 million cubic metres per day of sour gas, producing about 50 million cubic metres per day of sweet gas, together with approximately 80,000 barrels per day of gas condensate, 400 tonnes per day of sulfur, 2,600 tonnes per day of ethane, and 3,200 tonnes per day of LPG.

This scale helps explain why a single critical rotating machine can have an importance disproportionate to its physical size. Failure of a key item of cryogenic or gas-processing equipment can constrain an entire processing train.

The project team noted that any malfunction in these systems would lead to a reduction in refinery production capacity of between one-quarter and one-sixth of operational capability.

Development timeline and chronology

There is an important chronology to the technological achievement. The August 2025 announcement concerned the first Iranian-made turboexpander installed and commissioned at South Pars.

The announcement was made on 17 August 2025, when the refinery's manager, Kambiz Safti, reported that specialists at the refinery had successfully installed and commissioned the equipment during the year's major overhaul.

The equipment was described as a first-of-its-kind domestic manufacturing achievement in Iran and as an important step in localizing strategically important refinery equipment.

Later reports, including those from November 2025 and February 2026, provided considerably more technical detail and explicitly characterized the unit as the country's first domestically produced turboexpander with magnetic bearings.

These reports identified the machine's 3.5 MW rating, 12,000-rpm speed, Unit 105 location, pressure and temperature conditions, and the use of recovered expansion power to drive the compressor.

The project team described the development history as spanning approximately four years from design and development to industrial realization.

The term "first Iranian-made" should not be interpreted as meaning that Iran had never previously operated turboexpanders. South Pars had used turboexpanders long before the 2025 project.

The published engineering literature on the Fifth Refinery discusses turboexpanders as part of its existing process equipment. The novelty was domestic design, manufacturing, and commissioning of the replacement machine, not the introduction of turboexpansion itself to South Pars.

The project therefore represents the substitution of domestic capability for foreign dependency, rather than the creation of entirely new processing technology.

Fifth Refinery: Strategic asset for Iranian energy security

The South Pars Gas Complex is the center of Iran's natural-gas processing system and a major source of gas for domestic consumption and industry.

The Fifth Refinery itself is a large processing installation, and published engineering work has demonstrated that relatively small changes in its process bottlenecks can have measurable effects on overall gas production.

Within such a facility, the reliability of specialized rotating equipment can therefore have system-level consequences.

A locally manufactured turboexpander does not by itself transform Iran's gas-processing industry, but it can remove one particularly difficult dependency from the maintenance and procurement chain.

The broader context of the South Pars complex underscores the strategic importance of the achievement. The complex has been undergoing extensive rehabilitation and maintenance work, with major repairs at refineries using domestic technical capacity and Iranian equipment.

In August 2026, the Iranian authorities officially launched a rehabilitation project for the third refinery in the South Pars field, with the repair and commissioning of damaged units expected to contribute directly to reducing the country's gas supply deficit.

The South Pars gas field is a strategic national asset, and the ability to maintain and repair its processing infrastructure using domestic capabilities is essential to energy security.

The localization efforts at South Pars extend beyond the turboexpander project. The seventh refinery of the South Pars Gas Complex has succeeded in localizing more than 90 percent of industrial filters and valves, with items such as elbows, pipes, bolts and nuts, flanges, and gaskets completely supplied and purchased from domestic sources.

In the field of mechanical seal items, more than 80 percent localization has been achieved.

The fifth refinery's turboexpander project represents one of the most technically demanding of these localization efforts, but it is part of a broader pattern of reducing dependence on foreign suppliers across the entire gas processing value chain.

Technical assessment: achievement and context

The Iranian project is technically meaningful. It combines cryogenic gas processing, high-speed turbomachinery, energy recovery, integrated compression, and magnetic-bearing technology in a single industrial machine.

The fact that the equipment was commissioned in an operating refinery rather than merely demonstrated in a laboratory is particularly important.

The project thus represents not simply the substitution of an imported component with a locally manufactured one, but the development of a domestic capability in one of the more demanding categories of equipment used in modern natural-gas processing.

There is, however, insufficient publicly available information to independently assess several parameters essential to a formal engineering qualification.

The public reports do not provide a complete performance curve, expander isentropic efficiency, compressor polytropic efficiency, rotor mass, impeller diameter, blade geometry, materials specifications, vibration limits, magnetic-bearing controller architecture, backup-bearing design, seal arrangement, anti-surge system, detailed gas composition, or measured long-term availability.

The genuine significance of the Iranian achievement is more specific: the reported domestic design, manufacture, integration, and commissioning of a large industrial turboexpander-compressor using magnetic-bearing technology under Iranian conditions and without dependence on the previous foreign OEM supply chain.

That is a substantial engineering accomplishment, but it does not mean that Iran has surpassed or even matched the full capabilities of the leading international manufacturers across the entire range of sizes, pressures, temperatures, and applications.

Turboexpanders are highly specialized, expensive, and technically demanding machines. Historically, dependence on foreign manufacturers meant that failures could create a long supply-chain problem involving specialist components and services.

Domestic production potentially changes that equation by creating an Iranian engineering base capable of designing, manufacturing, commissioning, and eventually maintaining such machines.

The successful installation and commissioning of one machine establishes an important industrial milestone. The project represents a substantial achievement in industrial localization and a demonstration that Iran can develop capabilities in sophisticated machinery that previously required foreign technology transfer.

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