Whereas hydrogen has benefits that designate its ongoing use as a putative inexperienced substitute for a lot of different fuels, it does current a fairly distinct set of security challenges. However it appears the dangers may be mitigated with enough consciousness, and the deployment of acceptable applied sciences and finest practices, as Envirotec found in dialog with industrial security and gasoline detection professional Dräger. The agency assists organisations to work safely with hydrogen, and to equip their websites accordingly. Fuel detection methods are a key ingredient.
Hydrogen’s specific energy is with its versatility as a way to retailer, transport and distribute power over giant distances and between sectors – certainly, it’s the one at-scale expertise in a position to take action. It may be produced wherever renewable power akin to wind or photo voltaic is generated, after which transported to the place it’s required. That is the perfect, at the very least.
There are definitely similarities between hydrogen and methane, and among the present infrastructure for pure gasoline may be repurposed for it. Each are explosive, for one factor. However there are key variations when it comes to their properties and the particular dangers they current. Adam Pope, Advertising Supervisor and Fuel Detection Lead with Dräger suggests this isn’t at all times obvious to operators and workers who’ve labored with pure gasoline or LPG. “They’ll perhaps have some concept in regards to the Hindenburg catastrophe,” he muses, referencing the 1937 calamity that drew a line below an earlier period’s exploration of hydrogen as a gasoline, however they’ll usually be unfamiliar with hydrogen’s particular challenges, and the mandatory risk-mitigation methods.
For one factor, hydrogen’s flame traits are fairly distinct from different frequent fuels, in that it’s tough to detect with the bare eye in daylight (though it may be seen in darker situations). It additionally emits little or no warmth – so you possibly can’t really feel it till you might be in very shut proximity.
A technique it may be detected is by the electromagnetic radiation emitted when it burns – a signature that may be picked up by sure courses of detector.
A few of the key danger components particular to hydrogen are listed within the facet panel (“Hydrogen danger components”, see finish of article). Its flammability and propensity to leak from constructions place a premium on high-integrity storage. And leak detection is an important component of safeguarding.
These danger components will clearly be unfamiliar the place hydrogen is a current add-on to an organisation’s core experience. For instance, at a wind or photo voltaic power website the place the operators have opted to provide hydrogen through electrolysis.
Factors of vulnerability within the worth chain are explored in an e-book from Dräger.1 Even the place present infrastructure may be tailored there will probably be important new concepts to know. For instance, present gasoline pipelines, the place appropriate, would require new monitoring and upkeep regimes.
The e-book explains that “the likelihood of security incidents will increase when individuals are concerned”. The doc provides: “When heavy machines akin to vans are moved round, even minor bumps must be taken severely as they enhance the danger of leakage.”
Profiling a website
Gaining a full image of a website’s dangers is an important precursor to designing mitigation measures – and requires an individualised danger evaluation, one thing Dräger’s literature recommends “earlier than becoming a member of the hydrogen economic system”. There isn’t any customary danger profile, seemingly, and the dangers manifest in numerous methods in every website.
Hearth and gasoline mapping is one service the group introduces at this early stage, says Adam Pope, which is able to lead to a colour-coded 3d map of a website meant to afford a transparent understanding of the totally different dangers, and of the place leaked gases will journey in numerous circumstances.
Mounted gasoline and flame detection is the first means to guard a website from explosion danger, by alerting operators to the presence of a leak, in order that premises may be evacuated and processes can probably be shut down.
A spread of various applied sciences is used right here, every with totally different strengths and weaknesses. Greatest observe entails a mixture of applied sciences, as Adam explains.
Three layers of safety
Level detectors are the core expertise for gasoline detection and kind the inspiration of most security methods, he says. These will probably be positioned wherever there’s a hazard that gasoline can accumulate, akin to in confined areas. The draw back is that the gasoline should have the ability to make contact with the detector or it is likely to be missed.
The selection of sensor expertise is essential right here. As Adam factors out, the infrared sensors used to detect hydrocarbons are fully blind to hydrogen. As an alternative, catalytic bead (CatEx) sensors, or electrochemical (EC) sensors, can be utilized right here. CatEx sensors provide a strong technique to detect hydrogen as much as the explosive restrict (i.e., beneath 100% LEL, the Decrease Explosion Stage), offering a quick response time. EC sensors are sometimes used the place decrease (ppm) focus ranges of hydrogen are to be detected, and in addition provide a quick response time and excessive accuracy.
An earlier warning of leakage is out there with ultrasonic detectors, to be deployed as a further layer of detection the place acceptable. These exploit the truth that hydrogen’s small molecule measurement leads to a high-frequency noise, wherever there’s a leak. The acoustic sensor can detect leaks occurring as much as 7 – 15 m away from the leak supply, and ship an on/off sign that can be utilized to set off an alarm or computerized shutdown of kit.
Ultrasonic detectors are good for out of doors places, the place the wind may in any other case carry hydrogen away from level detectors.
The relative invisibility of hydrogen flames means a further layer of detection can typically be acceptable for a website, within the type of hydrogen flame detectors. Two applied sciences seem to face out: UV/IR detectors, and 3IR.2 A conventional choice for detecting hydrocarbon fires is a UV/IR detector, using one ultraviolet and one infrared sensor, and offering a swift response time however with some potential for false alarms, notably when making an attempt to detect hydrogen.
To help with hydrogen detection particularly, Dräger has adopted a expertise known as “3IR” – so-named for its use of three separate IR sensors, and that is included within the firm’s Flame 1750 H₂ detector. The 3IR expertise produces a low price of false alarms and a quick response – as Adam says, it might detect a 1m flame at a distance of as much as 40m, inside 5 seconds. It additionally supplies a large subject of detection compared to UV/IR. A case examine explores the small print of those claims, which can be the main focus of a current white paper.
Dräger’s flame-detection expertise accomplice Micropack carried out the evaluation and used HazMap3D software program to mannequin a posh industrial set up, and to point the detection protection obtainable with ten Dräger Flame 1750 H2 detectors. A color-coded evaluation displayed the detected fire-risk areas in inexperienced, and blind spots in crimson. And this seemingly confirmed that it supplied 64% protection, with 36% of the goal areas remaining outdoors the flame detector’s vary or obstructed. As compared, twenty UV/IR flame detectors in the identical set up achieved solely 44% protection, leaving 56% unprotected. The conclusion? 3IR expertise reduces price and will increase protection.
Multichannel strategy
Not like hydrocarbon combustion, which is usually detected by CO₂ emissions, hydrogen flames are primarily recognized by the presence of water vapour — a distinction that seems central to this detection methodology. The 3IR detector focuses on the two–4 µm area of the electromagnetic spectrum, the place hydrogen’s attribute spectral options are discovered. Every of the three separate IR sensors focuses on a selected area of this band: One focuses on the world the place combustion signatures are strongest, and the opposite two present reference channels, to assist distinguish any detected hydrogen flame signature from different potential warmth sources within the neighborhood. By a steady comparability of the three alerts, the detector is ready to filter out sources of false positives akin to welding gear or daylight.
Quite a lot of points come into play when safeguarding a website that makes use of or shops hydrogen in any method. When conducting a danger evaluation, Dräger advises on points akin to the location and selection of gasoline and flame detectors, along with issues akin to appropriate storage places for hydrogen, and figuring out the place any gasoline will go if it escapes.
Safeguarding a website can also contain integrating gasoline and flame detectors with an inside alarm administration system, and different methods that may, for instance, shut down processes which may carry an explosion danger when mixed with hydrogen.
Dräger supplies an end-to-end service which additionally incorporates third-party merchandise akin to alarms, “to create a seamless security infrastructure”.
Whereas the panorama of dangers is likely to be unfamiliar to many at this level – or the world is within the strategy of getting acquainted with them – a constant message from Dräger appears to be that every one the dangers may be managed. With consciousness of the suitable safeguards, choice of the suitable applied sciences, and placing best-practice into motion, this promising clear power supply can turn into as routine as every other type of gasoline.
Notes
[1] “Hydrogen: The way to meet the protection challenges.” Book obtainable from Dräger. https://www.draeger.com/Content material/Paperwork/Content material/hydrogen-safety-challenges-ebk-11064-en-master.pdf.
[2] “Detecting the Invisible: Understanding hydrogen flames and selecting the best detector”, PDF, obtainable from Dräger.
Hydrogen danger components – SIDE PANEL
The universe’s lightest component presents its personal distinctive set of danger components, a few of that are listed right here.
- Explosion danger: Whereas hydrogen just isn’t explosive by itself, it turns into extremely explosive when blended with air in sure concentrations. It additionally has a comparatively low ignition power. After manufacturing, hydrogen will are typically compressed to organize it for storage or transport, and this provides to the explosion danger. It additionally produces a a lot greater explosion than pure gasoline, with round 7x the explosion velocity.
- Leak danger: With its small molecule measurement, and low viscosity, hydrogen leaks extra readily than different fuels akin to methane. A container that’s “air-tight” for methane, may not essentially be “air-tight” for hydrogen. This additionally means pipelines and different constructions must be engineered to hydrogen-ready specs, and it will likely be essential to make sure there are common inspections of issues like joints in pipelines.
- Risk to constructions: The small measurement of molecules additionally accounts for hydrogen’s potential to embrittle constructions, by permeating their inside. To guard towards this, storage tanks are typically made from stainless-steel or composites.
- Kinds gasoline pockets: Its lightness is one essential distinction with methane, and the very fact of hydrogen’s being lighter than air means leaks usually are not so simply detected at floor stage, even when harmful quantities is likely to be accumulating beneath a close-by ceiling, as Dräger’s literature explains. The position of gasoline detectors ought to replicate this.
- Odourless: Hydrogen is odourless, like methane. An odourant marker is added to the latter (mostly a selected mix of mercaptans), to get round this nasal invisibility. Such a risk is being investigated and trialled with hydrogen, however the outcomes are nonetheless awaited.
