Industry Overview: Waste to Energy

The waste to energy industry utilises several waste treatment methods. Municipal and industrial solid waste is converted into electricity, and sometimes into heat for industrial processing and district heating systems. The main process is of course incineration, but intermediate steps of pyrolysis, gasification, and anaerobic digestion are sometimes used to convert the waste into useful by-products that are then used to generate power through turbines or other equipment. This technology is gaining wide recognition globally as a greener and cleaner form of energy than traditional burning of fossil fuels, and as a means of reducing waste production.

Types of waste to energy

Incineration

Incineration is a waste treatment process that involves the combustion of energy rich substances contained within waste materials, typically at high temperatures around 1000 degrees C. Industrial plants for waste incineration are commonly referred to as waste-to-energy facilities and are often sizeable power stations in their own right. Incineration and other high-temperature waste treatment systems are often described as “thermal treatment”. During the process waste is converted into heat and steam that can be used to drive a turbine in order to generate electricity. This method currently has an efficiency of around 15-29%, although it does have potential for improvements.

Pyrolysis

Pyrolysis is a different waste treatment process where decomposition of solid hydrocarbon wastes, typically plastics, takes place at high temperatures without oxygen present, in an atmosphere of inert gases. This treatment is usually conducted at or above 500 °C, providing enough heat to deconstruct the long chain molecules including bio-polymers into simpler lower mass hydrocarbons.

Gasification

This process is used to make gaseous fuels from heavier fuels and from waste containing combustible material. In this process, carbonaceous substances are converted into carbon dioxide (CO₂), carbon monoxide (CO) and a small amount of hydrogen at high temperature. In this process, gas is generated which is a good source of usable energy. This gas can then be used to produce electricity and heat.

Plasma Arc Gasification

In this process, a plasma torch is used to ionise energy rich material. Syngas is produced which may then be used to make fertiliser or generate electricity. This method is more of a waste disposal technique than a serious means of generating gas, often consuming as much energy as the gas it produces can provide.

Reasons for Waste to Energy

As this technology is gaining wide recognition globally in regards to waste production and the demand for clean energy.

Avoids methane emissions from landfills
Offsets greenhouse gas (GHG) emissions from fossil fuel electrical production
Recovers and recycles valuable resources, such as metals
Produces clean, reliable base-loaded energy and steam
Uses less land per megawatt than other renewable energy sources
Sustainable and steady renewable fuel source (compared to wind and solar)
Destroys chemical waste
Results in low emission levels, typically well below permitted levels
Catalytically destroys nitrogen oxides (NOx), dioxins and furans using an selective catalytic reduction (SCR)

What are the Gas Hazards?

There are many processes to turn waste into energy, these include, biogas plants, refuse use, leachate pool, combustion and heat recovery. All these processes pose gas hazards to those working in these environments.

Within a Biogas Plant, biogas is produced. This is formed when organic materials such as agricultural and food waste are broken down by bacteria in an oxygen-deficient environment. This is a process called anaerobic digestion. When the biogas has been captured, it can be used to produce heat and electricity for engines, microturbines and fuel cells. Clearly, biogas has high methane content as well as substantial hydrogen sulphide (H₂S), and this generates multiple serious gas hazards. (Read our blog for more information on biogas). However, there is an elevated risk of, fire and explosion, confined space hazards, asphyxiation, oxygen depletion and gas poisoning, usually from H₂S or ammonia (NH₃). Workers in a biogas plant must have personal gas detectors that detect and monitor flammable gas, oxygen and toxic gases like H₂S and CO.

Within a refuse collection it is common to find flammable gas methane (CH₄) and toxic gases H₂S, CO and NH₃. This is because refuse bunkers are built several metres underground and gas detectors are usually mounted high up in areas making those detectors hard to service and calibrate. In many cases, a sampling system is a practical solution as air samples can be brought to a convenient location and measured.

Leachate is a liquid that drains (leaches) from an area in which waste is collected, with leachate pools presenting a range of gas hazards. These include the risk of flammable gas (explosion risk), H₂S (poison, corrosion), ammonia (poison, corrosion), CO (poison) and adverse oxygen levels (suffocation). Leachate pool and passageways leading to the leachate pool requiring monitoring of CH₄, H₂S, CO, NH₃, oxygen (O₂) and CO₂. Various gas detectors should be placed along routes to the leachate pool, with output connected to external control panels.

Combustion and heat recovery requires the detection of O₂ and toxic gases sulphur dioxide (SO₂) and CO. These gases all pose a threat to those who work in boiler house areas.

Another process that is classed as a gas hazard is an exhaust air scrubber. The process is hazardous as the flue gas from incineration is highly toxic. This is because it contains pollutants such as nitrogen dioxide (NO₂), SO₂, hydrogen chloride (HCL) and dioxin. NO₂ and SO₂ are major greenhouse gases, while HCL all of these gas types mentioned here are harmful to human health.

To read more on the waste to energy industry, visit our industry page.

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Why is gas detection crucial for drink dispense systems

Dispense gas known as beer gas, keg gas, cellar gas or pub gas is used in bars and restaurants as well as the leisure and hospitality industry. Using dispense gas in the process of dispensing beer and soft drinks is common practice worldwide. Carbon dioxide (CO₂) or a mix of CO₂ and nitrogen (N₂) is used as a way of delivering a beverage to the ‘tap’. CO₂as a keg gas helps to keep the contents sterile and at the right composition aiding dispensing.

Gas Hazards

Even when the beverage is ready to deliver, gas-related hazards remain. Those arise in any activity at premises that contain compressed gas cylinders, due to the risk of damage during their movement or replacement. Additionally, once released there is a risk of increased carbon dioxide levels or depleted oxygen levels (due to higher levels of nitrogen or carbon dioxide).

CO₂occurs naturally in the atmosphere (0.04%) and is colourless and odourless. It is heavier than air and if it escapes, will tend to sink to the floor. CO₂ collects in cellars and at the bottom of containers and confined spaces such as tanks and silos. CO₂ is generated in large amounts during fermentation. It is also injected into beverages during carbonation – to add the bubbles. Early symptoms of exposure to high levels of carbon dioxide include dizziness, headaches, and confusion, followed by loss of consciousness. Accidents and fatalities can occur in extreme cases where a significant amount of carbon dioxide leaks into an enclosed or poorly ventilated volume. Without proper detection methods and processes in place, everyone entering that volume could be at risk. Additionally, personnel within surrounding volumes could suffer from the early symptoms listed above.

Nitrogen (N₂) is often used in the dispensing of beer, particularly stouts, pale ales and porters, it also as well as preventing oxidisation or pollution of beer with harsh flavours. Nitrogen helps push the liquid from one tank to another, as well as offer the potential to be injected into kegs or barrels, pressurising them ready for storage and shipment. This gas is not toxic, but does displace oxygen in the atmosphere, which can be a danger if there is a gas leak which is why accurate gas detection is critical.

As nitrogen can deplete oxygen levels, oxygen sensors should be used in environments where any of these potential risks exist. When locating oxygen sensors, consideration needs to be given to the density of the diluting gas and the “breathing” zone (nose level). Ventilation patterns must also be considered when locating sensors. For example, if the diluting gas is nitrogen, then placing the detection at shoulder height is reasonable, however if the diluting gas is carbon dioxide, then the detectors should be placed at knee height.

The Importance of Gas Detection in Drinks Dispense Systems

Unfortunately, accidents and fatalities do occur in the drinks industry due to gas hazards. As a result, in the UK, safe workplace exposure limits are codified by the Health and Safety Executive (HSE) in documentation for the Control of Substances Hazardous to Health (COSHH). Carbon dioxide has an 8-hour exposure limit of 0.5% and a 15-minute exposure limit of 1.5% by volume. Gas detection systems help to mitigate gas risks and allow for drinks manufacturers, bottling plants and bar/pub cellar owners, to ensure the safety of personnel and demonstrate compliance to legislative limits or approved codes of practice.

Oxygen Depletion

The normal concentration of oxygen in the atmosphere is approximately 20.9% volume. Oxygen levels can be dangerous if they are too low (oxygen depletion). In the absence of adequate ventilation, the level of oxygen can be reduced surprisingly quickly by breathing and combustion processes.

Oxygen levels may also be depleted due to dilution by other gases such as carbon dioxide (also a toxic gas), nitrogen or helium, and chemical absorption by corrosion processes and similar reactions. Oxygen sensors should be used in environments where any of these potential risks exist. When locating oxygen sensors, consideration needs to be given to the density of the diluting gas and the “breathing” zone (nose level). Oxygen monitors usually provide a first-level alarm when the oxygen concentration has dropped to 19% volume. Most people will begin to behave abnormally when the level reaches 17%, and hence a second alarm is usually set at this threshold. Exposure to atmospheres containing between 10% and 13% oxygen can bring about unconsciousness very rapidly; death comes very quickly if the oxygen level drops below 6% volume.

Our Solution

Gas detection can be provided in the form of both fixed and portable detectors. Installation of a fixed gas detector can benefit a larger space such as cellars or plant rooms to provide continuous area and staff protection 24 hours a day. However, for worker safety in and around cylinder storage area and in spaces designated as a confined space, a portable detector can be more suited. This is especially true for pubs and beverage dispensing outlets for the safety of workers and those who are unfamiliar in the environment such as delivery drivers, sales teams or equipment technicians. The portable unit can easily be clipped to clothing and will detect pockets of CO₂using alarms and visual signals, indicating that the user should immediately vacate the area.

For more information about gas detection in drink dispense systems, contact our team.

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Oxygen Depletion Risks from Nitrogen in Pharmaceutical Processing

Within the air, a normal concentration of oxygen is 21%, while nitrogen makes up 78% of the rest of the atmosphere along with some trace gases. Inert gases such as nitrogen, argon and helium although aren’t toxic, they do not help to support human breathing. These are odourless, colorless and tasteless making them undetectable. An increase in the volume of any other gases that are not oxygen can lead to a circumstance in which individuals may be at risk of asphyxiation which can cause serious injury or even death. This removal of oxygen gas in the air we breathe makes having an oxygen depletion sensor not just useful, but essential to maintaining life.

How is Nitrogen used to control oxygen levels?

Nitrogen (N2) can be used to control levels of oxygen in a laboratory. When carrying out tasks within the pharmaceutical industry, when transferring products or packaging process, nitrogen is used. Nitrogen is used to take oxygen away from the packaging prior to it being sealed, to make certain the product is preserved. As a result of this the need for an oxygen deficiency monitor is very important. Fixed or portable devices have the ability to detect oxygen levels within a laboratory, plant or utility room. Fixed gas detection systems are suitable for monitoring an area or room, whereas a portable gas detector is designed to be worn on the person within your breathing area.

What are the Risks of Oxygen depletion?

There are three main reasons why monitors are needed; it is essential to detect oxygen deficiencies or enrichment as too little oxygen can prevent the human body from functioning leading to the worker losing consciousness. Unless the oxygen level can be restored to a normal level the worker is at risk of potential death. An atmosphere is deficient when the concentration of O2 is less than 19.5%. Consequently, an environment that has too much oxygen in it is equally dangerous as this constitutes a greatly increased risk of fire and explosion, this is considered when the concentration level of O2 is over 23.5%.

In the absence of adequate ventilation, the level of oxygen can be reduced surprisingly quickly by breathing and combustion processes. Oxygen levels may also be depleted due to dilution by other gases such as carbon dioxide (also a toxic gas), nitrogen or helium, and chemical absorption by corrosion processes and similar reactions. Oxygen sensors should be used in environments where any of these potential risks exist. When locating oxygen sensors, consideration needs to be given to the density of the diluting gas and the “breathing” zone (nose level). For example, helium is lighter than air and will displace the oxygen from the ceiling downwards whereas carbon dioxide, being heavier than air, will predominately displace the oxygen below the breathing zone. Ventilation patterns must also be considered when locating sensors.

Oxygen monitors usually provide a first-level alarm when the oxygen concentration has dropped to 19% volume. Most people will begin to behave abnormally when the level reaches 17%, and hence a second alarm is usually set at this threshold. Exposure to atmospheres containing between 10% and 13% oxygen can bring about unconsciousness very rapidly; death comes very quickly if the oxygen level drops below 6% volume. Oxygen sensors are often installed in laboratories where inert gases (e.g., nitrogen) are stored in enclosed areas.

How do Fixed or Portable Devices Detect Oxygen?

Crowcon offer a range of portable monitors; Gas-Pro portable multi gas detector offers detection of up to 5 gases in a compact and rugged solution. It has an easy-to-read top mount display making it easy to use and optimal for confined space gas detection. An optional internal pump, activated with the flow plate, takes the pain out of pre-entry testing and allows Gas-Pro to be worn either in pumped or diffusion modes.

T4 portable 4-in-1 gas detector provides effective protection against oxygen depletion. T4 multi gas detector now comes with improved detection of pentane, hexane and other long chain hydrocarbons. Offering you compliance, robustness and low cost of ownership in a simple to use solution. T4 contains a wide range of powerful features to make everyday use easier and safer.

Crowcon’s fixed detector XgardIQ is an intelligent and versatile fixed detector and transmitter compatible with Crowcon’s full range of sensor technologies. Available fitted with a variety of sensors for fixed flammable, toxic, oxygen or H2S gas detection. Providing analogue 4-20mA and RS-485 Modbus signals as standard, XgardIQ is optionally available with Alarm and Fault relays and HART communications. The 316 stainless steels are available with three M20 or 1/2“NPT cable entries. This device is also (SIL-2) Safety integrity level 2 certified fixed detector.

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What’s so Important about my Monitors Measuring Range?

What is a Monitor Measuring Range?

Gas monitoring is usually measured in PPM range (parts per million), percentage volume or percentage of LEL (lower explosive limit) this enables Safety Managers, to ensure that their operators are not being exposed to any potentially harmful levels of gases or chemicals. Gas monitoring can be done remotely to ensure that the area is clean before a worker enters the area as well as monitoring gas through a permanently fixed device or body worn portable device to detect any potentially leaks or hazardous areas during the course of the working shift.

Why are Gas Monitors essential and what are the Ranges of deficiencies or enrichments?

There are three main reasons why monitors are needed; it is essential to detect oxygen deficiencies or enrichment as too little oxygen can prevent the human body from functioning leading to the worker losing consciousness. Unless the oxygen level can be restored to a normal level the worker is at risk of potential death. An atmosphere is considered to be deficient when the concentration of O2 is less than 19.5%. Consequently, an environment that has too much oxygen in it is equally dangerous as this constitutes a greatly increased risk of fire and explosion, this is considered when the concentration level of O2 is over 23.5%.

Monitors are required when Toxic Gases are present of which can cause considerable harm to the human body. Hydrogen Sulphide (H2S) is a classic example of this. H2S is given off by bacteria when it breaks down organic matter, due to this gas being heavier than air, it can displace air leading to potential harm to persons present and is also a broad-spectrum toxic poison.

Additionally, gas monitors have the ability to detect flammable gases. Dangers that can be prevented through using a gas monitor are not only though inhaling but they are a potential hazard due to combustion. gas monitors with an LEL range sensor detects and alert against flammable gases.

Why are they important and how do they work?

Measurement or Measuring Range is the total range that the device can measure in normal conditions. The term normal meaning no overpressure limits (OPL) and within maximum working pressure (MWP). These values are usually found on the product website or specification datasheet. The measuring range can also be calculated by identifying the difference between the Upper Range Limit (URL) and the Lower Range Limit (LRL) of the device. When trying to determine the range of the detector it is not identifying the area of square footage or within a fixed radius of the detector but instead is identifying the yielding or diffusion of the area being monitored. The process happens as the sensors respond to the gases that penetrate through the monitor’s membranes. Therefore, the devices have the ability to detect gas that is in immediate contact with the monitor. This highlights the significance of understanding the measuring range of gas detectors and highlight their importance for the safety of the workers present in these environments.

Are there any products that are available?

Crowcon offer a range of portable monitors; The Gas-Pro portable multi gas detector offers detection of up to 5 gases in a compact and rugged solution. It has an easy-to-read top mount display making it easy to use and optimal for confined space gas detection. An optional internal pump, activated with the flow plate, takes the pain out of pre-entry testing and allows Gas-Pro to be worn either in pumped or diffusion modes.

The T4 portable 4-in-1 gas detector provides effective protection against 4 common gas hazards: carbon monoxide, hydrogen sulphide, flammable gases and oxygen depletion. The T4 multi gas detector now comes with improved detection of pentane, hexane and other long chain hydrocarbons. Offering you compliance, robustness and low cost of ownership in a simple to use solution. T4 contains a wide range of powerful features to make everyday use easier and safer.

The Gasman portable single gas detector is compact and lightweight yet is fully ruggedised for the toughest of industrial environments. Featuring simple single button operation, it has a large easy-to-read display of gas concentration, and audible, visual and vibrating alarms.

Crowcon also offer a flexible range of fixed gas detection products that can detect flammable, toxic and oxygen gases, report their presence and activate alarms or associated equipment. We use a variety of measurement, protection and communications technologies and our fixed detectors have been proven in many arduous environments, including oil and gas exploration, water treatment, chemical plants and steel mills. These fixed gas detectors are used in many applications where reliability, dependability and lack of false alarms are instrumental to efficient and effective gas detection. These include within the automotive and aerospace manufacturing sectors, on scientific and research facilities and in high-utilisation medical, civil or commercial plants.

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Sapphire hunters saved!

The Mine Hunters are on the search for sapphires. In this episode they head to South Western Madagascar, to one of the few places in the world where a single mine can produce sapphires of every color of the rainbow.

After a wall collapse, oxygen depletion is the biggest danger they face in these dangerous environments – tunnels which have been sealed off for some time, are long, narrow, and go deep under ground.

Unfortunately miner Fred runs out of Oxygen whilst inspecting the first muddy pit mine. His Tetra 3 gas detector goes in to alarm, allowing his friends to pull him out quickly and safely. Although the team here is on a budget, the one piece of kit they can not go without is clear – a life saving gas detector!

View the video here

Read more about the Mine Hunters series and watch other episodes.

Find out more about the Tetra 3 Gas Detector and other interesting applications such as Volcano research

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