Removing hazardous vapours from tanks using nanotechnology

Apr 16 2020


Ecochlor is providing a technology which removes VOC vapours from fuel and cargo tanks, and suppresses further evaporation from fuel and sludge with a liquid suppressant.

Maritime equipment company Ecochlor, headquartered in Maynard, Massachusetts, is providing a service to the maritime industry which promises to clear a tank of VOC (volatile organic compound) vapours in a fraction of the time that air purging or gas inerting requires.

 

Fuel and cargo tanks contain hazardous VOC vapours, especially when sludge is present in the bottom of the tank.

 

VOC vapours must be managed for several reasons. They have to  be removed before filling the tank with a different cargo. They carry a risk of explosion, when mixed with oxygen in the right ratio. They must also be reduced to a safe level for any person to enter the tank for inspections or maintenance in order to prevent unhealthy exposure for workers.

 

VOC vapor management conventionally involves inerting the tank by pumping a non-reactive gas, such as nitrogen, into the tank to displace oxygen. This removes the explosive hazard but means a worker cannot safely enter the tank, as breathable atmosphere has been removed.

 

Ecochlor’s new technology is licensed from NanoVapor Inc, based in the Woodlands, Texas. It utilizes a liquid suppressant which is blown into the tank together with compressed air, creating extremely small “nano” droplets. The nano droplets work at a liquid surface level, creating a molecular layer that quickly suppress any VOC vapor formation in the tank, as well as preventing further evaporation without removing breathable atmosphere. This allows workers to safely enter the tank without risk of asphyxiation or explosion.

 

While the technology is new, “it is important to use standard sensors to measure VOC vapor in the tank, and determine that the technology has worked as described”, says Andrew Marshall, Vice President, Business Development, Ecochlor.

 

According to Mr Marshall, “The NanoVapor method can be up to 90 per cent faster than using normal air ventilation,” as well as better for the environment. “This nanotechnology is completely non-toxic, non-corrosive, non-reactive, and biodegradable. It is completely safe for human contact.”

 

Other tank inerting technologies, such as filling the tank with water to suppress and remove VOCs, also create a waste disposal challenge. According to Ecochlor, NanoVapor leaves no waste to clean up or contaminate the environment.

 

 

Shell Oil conducted a study in which compared NanoVapor to all possible alternatives for removing VOC vapour from petrol underground storage tanks, such as air purging, water filling, inerting with nitrogen, and dry ice (CO2). Upon completion, Shell chose NanoVapor as their “global best practice” for fuel storage tank degassing for maintenance and inspections.

 

Ecochlor is the exclusive marine agent for the product.

 

About the technology

The technology was initially developed for use in aviation, where VOC vapours must also be removed from a fuel tank in the course of maintenance. Since development, it has been utilized in tanks at retail petrol (gas) stations.

 

It has been optimised for hydrocarbons categorised as C5 or heavier, including gasoline, diesel, jet fuel and heavy fuel oil.

 

The technology comprises a container of liquid suppressant, and a portable  hardware delivery unit which blows the nano droplets into the tank using compressed air. The system weighs only 45kg, is about the size of a filing cabinet, and has no moving parts. It is connected to a compressed air input, and the output is connected to the tank vent. The delivery unit will use about 1 litre of liquid suppressant per hour.

 

There are a number of demonstration videos on the Ecochlor website, including using the fluid above an open container of petrol, and then lighting a match above the petrol to see that there is no VOC igniting.

 

In December 2019, NanoVapor received a product type approval certificate from Lloyd’s Register.

 

Using in practice

The shipowner takes out a contract with Ecochlor to use the NanoVapor technology.

 

Ecochlor also provides a chemical related service for ballast water treatment, and in that, there is a requirement for an Ecochlor technician to visit the ship twice a year, and can do chemical resupply at the same time. The same ship visit can be used to replenish the NanoVapor suppressant.

 

It will be initially available for use in bunker tanks, and towards the second half of 2020 the company plans to look at cargo tank applications.

 

The technology has not yet been extensively used in the maritime sector, although if it is reliable enough for aviation, the maritime sector ought to be comfortable with it, Mr Marshall says.

 

“We’re building our body of knowledge on exactly how the system behaves and performs across a variety of applications.”

 

“We want to get to a point where we can give a specific answer to a question like, ‘I’ve got a bunch of suezmaxes, I want to be able to degas, how much and how long,’” he says.

 

So far, conversations are going on with “a couple of cruise lines, a couple of very large tanker organizations, some Korean bulkers and some Japanese chemical tanker companies,” he said.

 

“If someone wants to take part in those demonstrations they are more than welcome to contact us.”

 

“Beyond that, there’s a question of how else we can use this technology.  A number of owners that we spoke to have been quite creative in their thinking

 

“We’re adding a process. People have to think slightly differently about how they are doing things onboard. We’re taking baby steps to make sure the roll out is done properly.”

 

Enclosed space death

Mr Marshall believes that the technology could also directly reduce the number of enclosed space deaths, one of the biggest causes of death on ships today.

 

Deaths are often associated with asphyxiation, especially when rescue attempts are made to retrieve an already compromised worker in the enclosed space.

 

The root cause of these incidents has been attributed by a number of commentators to be time pressure (see Jan-Feb 2020 issue, reports from Tanker Operator’s Hamburg conference). People do not follow the full procedures for entering an enclosed space because they are also under pressure to get the task completed by a deadline, and feel their job may be at risk.

 

“It is tough to fix the problem of seafarers feeling under time pressure, but the pressure might be reduced a little if a service like this can make the tank free of gases much faster,” Mr Marshall says.

 



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