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Nitrogen inertisation: what is it?

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Technology and safety are at the heart of what we do at Contec. Nitrogen inertisation, also known as inerting, is one of the safeguards we implement.

Flammable products and substrates for tire pyrolysis require extraordinary concern for safety during production and, above all, for employees. In combination with very high temperatures, these materials create hazardous conditions.

Thanks to technological developments and no compromises in our plant’s safety, Contec has implemented several safeguards to minimise risks, such as inerting systems. Although some of these measures aren’t legally required, our company policy is safety first!

The inertisation of the installation parts at risk of fire or explosion is a crucial part of our plant’s safety and one of our implemented safeguards. 

In addition, personal protection measures such as personal gas detectors, detectors at critical points in the plant, and often duplicated (redundant) control and measurement equipment make Contec not only a pioneer in what it does but also a safe place to work.

What is an inerting system (inertisation)?

Inertisation is a method of protecting a production process from combustion.

This is achieved by reducing the oxygen concentration in any machine or equipment to a level at which it’s impossible to create and sustain a combustion reaction (i.e. fire). Oxygen concentration is reduced by pumping an inert gas, such as nitrogen, into a closed system. 

Inerting systems are fairly new and not commonly used as a fire prevention method in the manufacturing industry. Traditionally, the focus is on detecting a fire as quickly as possible and extinguishing it effectively (and not necessarily preventing it). 

This method is not widely used because installing an inerting system is expensive. Since it’s not a preventive method required by law, most companies skip these ‘unnecessary’ costs.

How does nitrogen inertisation work?

To illustrate the formation of a fire (i.e. combustion), let’s look at the ‘triangle of combustion’:  the three main factors necessary to initiate ignition at any time and place. There must be: 

  • A combustible material for fuel (a substance that can burn) 
  • An ignition source/heat (initiator of ignition and later sustaining the combustion process), 
  • And an oxidant (oxygen from the air). 

In many publications, there is still a fourth element: free radicals, i.e., chemical compounds or elements formed during decomposition and oxidation and have free bonds that can lead to a combustion chain reaction. 

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Replacing air with an inert (non-combustible) gas removes the oxidiser from the system, thereby preventing fire even in extreme heat. The easiest inert gas to obtain is nitrogen since it makes up 78 per cent of our atmosphere (NASA), and its density is close to that of air, making it easily distributed in a pipeline or tank. 

Oxygen in the air is about 21 per cent by volume, and with nitrogen inertisation, we can reduce oxygen concentration by over 90 per cent. The amount of nitrogen applied is selected individually for each part of the installation with the help of pressure regulators. 

In most cases, conditions are considered non-flammable when the oxygen level is below 13 per cent by volume – which makes Contec’s plant highly protected against fire. Specially-trained employees have no direct contact with nitrogen (the gas is only injected into hermetic parts of the installation).

Safety standards at Contec 

Safety is an absolute priority for Contec, ensuring that the pyrolysis process continues without risking our employees and plants. Air compressors and nitrogen generators are required to produce and distribute the right amount of nitrogen in the equipment. Installation elements with explosive condition risks are equipped with additional inert gas injectors.

Mainly, nitrogen is injected into reactors, the oil condensation system, oil tanks, carbon black tanks, and the mill. The inertisation system is designed to provide continuous and easy access to it. There is the possibility of minor modifications even during production, thanks to shut-off valves and complete redundancy. 

To maintain the continuous operation of the entire inertisation, it’s necessary to continuously monitor it through control and measurement apparatus. An additional function of nitrogen is to increase the quality of pyrolysis products preventing partial oxidation in the reactors.

Risks: close to zero

Contec has introduced solutions like inertisation, reducing combustion risks to nearly zero. 

Nitrogen purging is carried out only in closed elements of the installation, and gas is injected only into selected and closed spaces or pipelines where there is no risk of the presence of operators — thus also protecting our workers. 

In addition, installation components are equipped with Pressure Safety Valves (PSVs), which open automatically in the event of a sudden increase in pressure. Methane and carbon monoxide concentration analysers have been installed on the plant, and employees have multigas detectors for personal protection that measure oxygen, flammable gases, carbon monoxide, and hydrogen sulphide concentrations at their current location. 

With this series of solutions, process operators can focus on production parameterisation to customise products, while keeping our plant, equipment, and team safe.

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