Why refineries should pay attention to valve performance in hydroprocessing

Hydroprocessing is as an integral part of any refining complex. 
The hydrocracking process can be considered the refinery workhorse for cracking heavy feeds into commercially attractive lighter distillates, while hydrotreating does exactly what the name suggests. It is used in the treatment of contaminants in the feed, resulting in improved output purity and enabling compliance with ever-stricter environmental regulations. 

Optimizing flow control in these processes can improve the quality of the output, the profitability of the process, and the overall sustainability of your operations.  

Ensuring output quality accurately

With growing pressure to improve the efficiency of diesel engines and reduce fuels’ sulfur content, finetuning processes to deliver their fullest potential is vital. The process’s accuracy, predictability, and stability are directly correlated with the quality of its output and thus the product’s value. Flow control technology’s potential to deliver great improvements to the of the process and output quality lies in control valve applications in the many hydrotreatment and hydrocracking processes.

Highly engineered control valve assemblies, with rotary valves such as the Neles™ R series segment, or linear globe control valves (GB series) with a wide range of severe service constructions, coupled with robust actuators and the most energy-efficient valve positioner – the Neles NDX™ – provide the most consistent control performance with the best possible accuracy and enabling the highest process stability.

A good example is the hydrogen quenching required to maintain the temperature equilibrium between the reactor bed’s inlet and outlet within +/-0.5 °C. Hydrogen keeps the catalyst clean by inhibiting the formation of coke, thereby minimizing the rate of catalyst de-activity, as well as maximizing product selectivity. Furthermore, the reactor average temperature is gradually increased to compensate for loss in any catalyst activity. 

A valve with good control accuracy capable of withstanding high pressure in the range of 100–180 bar G, sustaining the impact of stress corrosion cracking (due to traces of H2S) and arresting any potential leaks of flammable gas into the atmosphere, is a must.  The other desired attributes of this control valve are its capacity to respond quickly to any process variations, thereby maintaining process output equilibrium. Optimized hydrogen consumption, noise suppression, and anti-cavitation are also desired attributes.  

Optimizing costs through process efficiency

As with every business, being profitable is one of the first compulsory requirements. Maximizing profitability by being able to optimize the cost of production is important when running demanding industrial processes with valuable feedstock. 
In the furnace section, process costs can be optimized by regulating the proportion of fuel gases with variable heating capacities, along with variable amounts of fuel, during start-up and running conditions. Fuel gases are highly flammable in nature and deemed dirty for a control valve.

Neles rotary control valves have again proven themselves in controlling wide ranges of fuels with differing heating capacities and volumes supplied to the furnace due to their wide rangeability, thereby eliminating the need for split-range or multiple-valve configurations. This helps with optimal combustion, efficient fuel consumption, less maintenance – which serves to improve process efficiency – and lower operating costs.

Additionally, patented Neles Q-trimTM designs ensure noise abatement at source with a unique self-flushing feature. A single-piece body and fire-safe construction with live-loaded packing ensure the valve is less prone to fugitive emissions. All these paired with intelligent controls that facilitate data driven lifecycle services aim to maintain quality and performance over a long and predictable operating life.

Safety and sustainability are a must

Every single industrial process and plant, including every refinery, pay close attention to both safety and sustainability. In addition to the purity of the fuels produced, hydrotreating and hydrocracking processes address the challenges of fugitive emissions and valve seat leakage.

Reliable emergency shutdown (ESD) and certified fuel gas shut-off valves must provide a fast and consistent tight shut-off in emergencies. At the same time, they must have the required fire safety and fugitive emissions certifications to provide the refinery owner and personnel with peace of mind.

ESD valves must overcome any operational challenges, despite extended periods of non-operation, thus minimizing the risk of catastrophic failure with dire environmental consequences.

A great example of such a valve is the Jamesbury™ polymer seated ball valve utilizing Jamesbury Xtreme™ flexible lip-seal technology, besides being fire-safe according to API 607 and with third-party fugitive emissions approvals according to international standards like the ISO 15848 and the API 641. Xtreme, which is a form of molecular-enhanced PTFE, has superior material recovery characteristics and compensates for any wear between ball and seat, ensuring lasting seat tightness over high-cycle frequency and extended lifetimes. 
Complementing them are the field-proven Neles metal-seated design ball valves and their B1 series pneumatic actuators, coupled with intelligent solenoids like Neles ValvGuard™, which can perform dedicated partial stroke testing on demand or automatically, while capturing comprehensive online diagnostics to ensure reliable performance when required. High pneumatic capacity eliminates the need for additional instrumentation in most cases, thus enhancing the reliability and efficiency of the ESD valve assembly. Neles SwitchGuard™ is a similar built-for-purpose intelligent solenoid for securing the availability of other automated on/off valves. 

Trust – the final measure of quality

When selecting valve technologies for any application, the decision eventually comes down to the vendor you trust most to deliver on their promise. Valmet’s long history and proven track record in deploying mission-critical valve technologies for the oil and gas industry across the globe go a long way to alleviating any concerns about quality, efficiency, or sustainability.