Challenges in Energy-Intensive Industries

Energy-intensive industries - such as petrochemical plants and oil & gas pipelines - are currently in focus when it comes to achieving sustainability goals ("Net-Zero"). One of these goals is to limit the ecological footprint (i.e. the emissions that increase the greenhouse effect and cause global warming)  and thus, achieve decarbonization.

The discussion about decarbonization and the associated reduction of carbon dioxide and methane is in full swing in many companies. But which emissions (greenhouse gases) still exist and which of them have a negative impact on our climate? 

Understanding Greenhouse Gas Emissions

A distinction is made between fugitive emissions and fluorinated emissions. Fugitive emissions are caused by combustion or exhaust gases, which include carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). Emissions of fluorinated greenhouse gases ("F-gases") are usually produced deliberately, which is why they are not discussed in this article.

In 2022, the industry as a whole emitted around 196 million tons of greenhouse gases  which is less than twenty years ago but slightly more than in 2010. By 2050, the industry is aiming for this to be drastically reduced — a challenge for all sectors.

Emissions from petrochemical plants and pipelines

The oil and gas pipelines alone, which transport the product to refineries for further processing, release almost 50 tons of emissions into the atmosphere per year, and the chemical process industry an additional 25 tons per year. Methane, accounting for 6% of anthropic greenhouse emissions, is a major component of crude oil. This is up to 30 times more harmful than carbon dioxide.

Emission leaks in petrochemical plants, especially in multi-stage crude oil processing, are very low thanks to strict measurements and monitoring, which reduces the danger to people and nature in the immediate vicinity. However, to bring the medium to the processing plant in advance, it must be transported through the crude oil pipeline network which in Europe are growing rapidly.

Although pipeline transport can be considered a particularly safe and effective form of transport, it has a common critical point for almost all energy-intensive industries, which often leads to potential emissions: the emission of gases from the medium transported in the pipeline. However, this does not occur through the pipeline itself, but through the necessary components used. 

Compressor stations are used to compensate for pressure losses and thus regulate the volume flow. And for the distribution and shut-off of the medium, automated industrial valves with large sizes and high-pressure ranges are used. 

Due to the type of valves and their associated valve actuator, unintentional fugitive emissions can escape into the atmosphere. 

Valve sealants that have become brittle or leaks in the packing of the industrial valve can also cause emissions to escape. 

Expertly-designed valve actuators fitted on high-performance isolation valves specifically engineered to reduce emissions minimize the costs incurred when a fluid medium is lost due to leaking. In addition to the cost of the leaked medium, which could be measured in hundreds of euros per year, the lost flow medium causes secondary costs, such as a lower yield of end products. The loss of flow medium also means lost energy, as pumps or compressors are more heavily used to compensate for the leakage. Consequently, minimizing fugitive emissions through proper actuator design and maintenance can save a significant amount of capital.

Surprisingly, emission leaks in process plants are mainly caused by valves.

Standards for valves provide basic guidelines

Basic guidelines on fugitive emissions in actuators are provided by standards such as German federal immission control “TA-Luft” (VDI 2440), which ensures the use of suitable gaskets for flange connections and fittings. High quality is defined in reference to VDI 2440 and a specific leakage rate. The latter must be proven by a type test in a laboratory. 

DIN EN ISO 15848-1:2017-07 contributes significantly to the measurement, testing, and qualification procedures for fugitive emissions and goes hand in hand with the qualification procedure for the type testing of valves (ISO 15848-1:2015 + Amd.1:2017).

Especially in midstream applications, 90° shut-off valves are used almost exclusively due to their design-related advantages, such as a very low leakage rate, high-pressure rating, and nominal size with a simultaneously wide temperature range. Two types have been successfully established for decades: Butterfly valves and ball valves. 

In the case of butterfly valves, soft-seated valves are often used for the requirements of a long service life with the best long-lasting sealing function; high-performance valves for high pressure and temperature requirements with a simultaneously large nominal width; and lined valves for highly corrosive liquefied gases and slurries.

Ball valves offer full (or optionally reduced) passage with a sealing integrity like no other. These are therefore the first choice in terms of fugitive emissions in accordance with ISOV 15848-1. 

For this reason, an either-or-decision is typically made. 

Special C-ball design offers significant performance advantages 

The C-ball valve looks similar to a conventional ball valve, but the ²XC ball valve acts along two vectors of movement to allow opening and closing of the valve without friction or wearing at the seat and “C” contact.

Due to the kinetic energy transmitted through the stem and against a fixed seat, this "C" ball shape moves along two motion vectors to close and seal against a tight fit.

The unrestricted bi-directional valve requires no venting, which allows optimized pipe routing with fewer shut-off valves at 30% less weight compared to traditional rigid top-entry ball valves. These specially designed and tested sealings eliminate or minimize any emission leaks.

Valve Automation 

Another aspect of emission leaking in valves packages lies in its operation.

But what options are available for automating industrial valves to reduce unwanted emissions and at the same time keep the costs associated with the optimizations as low as possible?

Pipeline applications and very high required torques often rule out conventional pneumatic or electric actuator technology in general, as the required operating pressure or voltage supply can only be guaranteed with additional effort and costs. 

In addition, pneumatically operated actuators are usually designed in such a way that a low (permanent) leakage of control air is indispensable.

For these reasons, basically two types of actuators can be considered, especially in oil and gas pipelines and petrochemical: basically, either gas motor-operated or fluid-powered. In the case of fluid-powered ones, we then distinguish self-contained actuators (Gas-Over-Oil, Direct-Gas) or emission-controlled actuator technologies.

Gas motors, a subgroup of combustion engines, use compressed pipeline gas to drive pneumatic actuators that operate the valve. However, gas motors are no longer comparable with state-of-the-art valve automation. Although gas motors do not require electrical energy, they are very rarely used nowadays, partly because of their considerable methane emissions.

However, larger valves, especially those that have to move quickly, require correspondingly closing valve torque figures to reliably achieve the desired function. 

For this purpose, self-controlled systems (gas-over-oil actuators) have emerged as the best option. They offer the advantage that no separate supply is required. The actuators are used in pipelines that usually run hundreds of kilometers through underdeveloped areas where no low-pressure pneumatic instrument air or high-pressure hydraulic supply lines are available. The pipeline itself is under high pressure and thus provides a "dedicated" source of supply for intrinsically fluid-controlled systems (gas-over-oil). Unfortunately, emission discharges are not 100% avoidable here either. 

Another option for valve automation that is almost emission-free is the use of electric or electro-hydraulic valve actuators. With the electro-hydraulic alternative, gas recovery takes place thanks to the replacement of the existing pneumatic and/or hydraulic components. These are additionally automated with "smart" accessories, i.e., electro-pneumatic components that lead to less methane ventilation and reduced temporary medium leakage. The first successfully installed solar cells and battery storage systems have successfully advanced the application of this alternative, especially for electric actuators. To pressurize the hydraulic fluid in the electro-hydraulic solution and thus actuate the actuator in a spring-close or double-acting manner, it must be ensured that the voltage supply to the motor is maintained without interruption. 

On the other hand, the use of pure DC electric valve actuators and the selection of the component using a battery pack and solar system completely excludes any possible leakage, but the requirements for the closing times, which have to be realized quickly, must be taken into account as it usually results in exclusion under high-pressure ratings and nominal sizes. In addition, aspects such as a missing hand pump, which moves the valve into a safe position in an emergency - even without a power supply - and, above all, the mandatory power supply (solar power in the case of a solar panel) must be considered. The same applies to an oil pump operated by an electric motor that pumps oil from the oil tank into the bladder or piston accumulator. When the pressure required for the system is reached, the pump switches off automatically. As soon as one of two solenoid valves (either for opening or for closing) receives a signal from the control system, it opens the corresponding line and hydraulic oil flows from the accumulator into the hydraulic cylinder. Emissions are significantly reduced during operation compared to other types but cannot be completely eliminated. 

Full emission control with all the advantages of self-contained actuator technology

Is it possible to carry out valve actuation for natural gas pipelines with all the advantages of intrinsic medium (gas-powered) actuators, but at the same time monitor emissions - analogous to the unique C-ball design described above? 

A completely smart emission-controlled solution is ensured by an ECAT system (Emissions Controlled Actuation Technology). In principle, this actuator system is similar in design to an own-medium operated valve control system and therefore offers all the above-mentioned full advantages of the intrinsically fluid-operated actuator, especially for applications in ecologically sensitive areas. In addition, it scores points in direct comparison to conventional drive technology, especially in the high-pressure range. (Fig. 5) 

The existing pressure of the medium is utilized by either scotch yoke or rotary vane variants. Emission-free electrohydraulic automated valves use a combination of an electric motor and a spring-return, hydraulically-operated actuator to ensure fail-safe valve operation. However, once the stroke is complete, the integral pump is actuated by a (solar-powered) electric motor to reverse the hydraulic fluid, thereby immediately returning the gas to the pipeline for the next actuation. 

In many existing proven actuator combinations, the mechanical actuator itself can be retained and only the existing gas-oil hydraulic system is replaced with the patented ECAT. This retrofit has been proven to eliminate more than 99% of all gas emissions with a short-term return on investment. 

Conclusion

The "Fit for 55" climate target of the European Climate Change Act emphasizes reducing net greenhouse gas emissions by at least 55% by 2030.

Actuators in petrochemical pipelines contribute 60% to greenhouse gas emissions. The adoption of emission-controlled technology like ECAT, in conjunction with the innovative C-ball valve, presents a compelling solution for achieving energy efficiency and decarbonization goals in pipeline applications. By retrofitting existing systems and adopting these advancements, industries can reduce emissions and increase reliability and service life, contributing to a sustainable and greener future.

Author:

   Knut Riegel, Sr. Sales Manager, Emerson Final Control Germany

Personal Profile

Knut Riegel, Sr. Sales Manager for Business Impact Partners at Emerson, is a value-driven professional in valves, actuators, and regulators. Knut holds both a Process Automation and Business degree and has spent more than 15 years working in the flow control process industry. He is an active member of several industry associations and serves as an SME for topics around process automation.