Dust explosion protection/prevention 2005

Dust explosion protection/prevention 2005
Technological evolution The Livingston plant of Elementis Specialities is a shining example of correctly specified explosion protection systems Elementis Specialties, a speciality chemicals business and part of Elementis plc, is the first in Scotland, and the fourth in the UK, to be awarded third party certification for excellence in health, safety and environmental performance under the UK Chemical Industries Association Responsible Care initiative. This covers their Livingston facility in Scotland which manufactures rheological additives for paint and cosmetics. One of the ingredients used is a combustible organoclay which forms a potentially explosible dust cloud when mixed with air during processing. In the past, the company utilised explosion relief vents fitted to process vessels, allowing product to escape under pressure into the atmosphere. The company has now moved away from this approach says Gerry Clocherty, Director of European and Asian Operations at Elementis. ‘The trouble with explosion relief is the product that’s expelled into the atmosphere is followed by a flame which can ignite it and, in the worst cases, cause a fireball ten times the size of the vessel it came from!’ Now, explosion suppression is the primary basis of safety - stopping explosions in a matter of milliseconds before they have a chance to do any serious damage. Over the years, a number of Kidde Graviner explosion suppression systems have been installed. Renovation programme Recently, the company embarked on a major renovation programme involving the installation of a number of KEP explosion suppression systems to meet capacity expansion, protect new process vessels and take advantage of improvements in explosion suppression technology. During any dust explosion, fine particles suspended in the air ignite and burn rapidly, causing a fireball and a violent increase in pressure - the fireball travelling at about 10 m per sec and the pressure wave moving at about 330 m per sec. The fast-moving pressure wave is detected by an MEX-3 sensor that continually monitors the pressure inside the process vessel sending a signal to a control unit, which in turn activates a number of high rate discharge suppressors positioned strategically around the vessel. Powder suppressant is discharged into the vessel extinguishing the slower-moving fireball and suppressing the explosion. At Elementis, systems have been designed using explosion protection modelling software based on KEP's large database of explosion test results built up by the Kidde group research laboratory over thirty years. The software has the ability to model any type of explosion scenario. A number of innovative features have been incorporated at Elementis. Previously, suppressors used explosive detonators to discharge suppressant, now, new Protractor High Rate Discharge (PHRD) suppressors use two-piston, protractor operated actuators instead. These are safer to handle, ATEX compliant and dual redundant for extra reliability. Improvements have also been made in the explosion suppressant powder used. Two particle sizes KIDDEx suppresant has two particle sizes - larger for longer throw and smaller for greater interaction with the developing explosion. Tests show that this formulation suppresses explosions more efficiently than conventional sodium bicarbonate, says the company. Another new development is the ability to record the variation in pressure inside a process vessel. Connected to the MEX-3 sensor is a new FAB-3 field interface unit that records pressure data two seconds before and two seconds after the alarm criteria have been met. Data can then be viewed graphically and interrogated with Windows™-based software. Clocherty explains that this new development is useful in more ways than one. ‘The great thing about it is we can use it not only for analysing explosions, but also for monitoring the pressures inside our process vessels during routine trials or commissioning work’. Elementis has also installed a number of KEP explosion isolation systems to prevent pressure waves and fireballs from spreading down interconnecting pipelines to adjacent vessels. Active systems use explosion detection and control in conjunction with isolation devices such as suppressors and fast-acting valves downstream, while passive systems use barriers like rotary gate valves and screw feed conveyors that act as explosion chokes. Servicing and maintenance is also a key feature of any protection system. The period between inspections for the new MEX-3 sensors and PHRD suppressors is six months, compared to three months for older equipment, with servicing carried out by Kidde Fire Protection Services. Mike Hockham of KFPS says that if an explosion suppression system is activated, the procedure is for engineers to be rapidly on the scene to initiate an investigation into the cause of the explosion, carry out post-discharge checks, replace the suppressors, and confirm the integrity of the system before re-commissioning - very important at Elementis, where high value product is manufactured around the clock. Over Ł250,000 has been invested by Elementis in the new KEP systems. www.kfp.co.uk • It is reckoned that 2000 industrial explosions are recorded in the EU every year

Kidde Graviner explosion suppression systems Technological evolution
The Livingston plant of Elementis Specialities is a shining example of correctly specified explosion protection systems
Elementis Specialties, a speciality chemicals business and part of Elementis plc, is the first in Scotland, and the fourth in the UK, to be awarded third party certification for excellence in health, safety and environmental performance under the UK Chemical Industries Association Responsible Care initiative.
  This covers their Livingston facility in Scotland which manufactures rheological additives for paint and cosmetics. One of the ingredients used is a combustible organoclay which forms a potentially explosible dust cloud when mixed with air during processing.
   In the past, the company utilised explosion relief vents fitted to process vessels, allowing product to escape under pressure into the atmosphere. The company has now moved away from this approach says Gerry Clocherty, Director of European and Asian Operations at Elementis.
   ‘The trouble with explosion relief is the product that’s expelled into the atmosphere is followed by a flame which can ignite it and, in the worst cases, cause a fireball ten times the size of the vessel it came from!’ Now, explosion suppression is the primary basis of safety - stopping explosions in a matter of milliseconds before they have a chance to do any serious damage. Over the years, a number of Kidde Graviner explosion suppression systems have been installed.
Renovation programme

Recently, the company embarked on a major renovation programme involving the installation of a number of KEP explosion suppression systems to meet capacity expansion, protect new process vessels and take advantage of improvements in explosion suppression technology.
   During any dust explosion, fine particles suspended in the air ignite and burn rapidly, causing a fireball and a violent increase in pressure - the fireball travelling at about 10 m per sec and the pressure wave moving at about 330 m per sec. The fast-moving pressure wave is detected by an MEX-3 sensor that continually monitors the pressure inside the process vessel sending a signal to a control unit, which in turn activates a number of high rate discharge suppressors positioned strategically around the vessel. Powder suppressant is discharged into the vessel extinguishing the slower-moving fireball and suppressing the explosion.
   At Elementis, systems have been designed using explosion protection modelling software based on KEP's large database of explosion test results built up by the Kidde group research laboratory over thirty years. The software has the ability to model any type of explosion scenario. A number of innovative features have been incorporated at Elementis.
  Previously, suppressors used explosive detonators to discharge suppressant, now, new Protractor High Rate Discharge (PHRD) suppressors use two-piston, protractor operated actuators instead. These are safer to handle, ATEX compliant and dual redundant for extra reliability. Improvements have also been made in the explosion suppressant powder used.

Two particle sizes

KIDDEx suppresant has two particle sizes - larger for longer throw and smaller for greater interaction with the developing explosion. Tests show that this formulation suppresses explosions more efficiently than conventional sodium bicarbonate, says the company. Another new development is the ability to record the variation in pressure inside a process vessel.
   Connected to the MEX-3 sensor is a new FAB-3 field interface unit that records pressure data two seconds before and two seconds after the alarm criteria have been met. Data can then be viewed graphically and interrogated with Windows™-based software. Clocherty explains that this new development is useful in more ways than one. ‘The great thing about it is we can use it not only for analysing explosions, but also for monitoring the pressures inside our process vessels during routine trials or commissioning work’.
   Elementis has also installed a number of KEP explosion isolation systems to prevent pressure waves and fireballs from spreading down interconnecting pipelines to adjacent vessels. Active systems use explosion detection and control in conjunction with isolation devices such as suppressors and fast-acting valves downstream, while passive systems use barriers like rotary gate valves and screw feed conveyors that act as explosion chokes. Servicing and maintenance is also a key feature of any protection system.
   The period between inspections for the new MEX-3 sensors and PHRD suppressors is six months, compared to three months for older equipment, with servicing carried out by Kidde Fire Protection Services.
   Mike Hockham of KFPS says that if an explosion suppression system is activated, the procedure is for engineers to be rapidly on the scene to initiate an investigation into the cause of the explosion, carry out post-discharge checks, replace the suppressors, and confirm the integrity of the system before re-commissioning - very important at Elementis, where high value product is manufactured around the clock. Over Ł250,000 has been invested by Elementis in the new KEP systems.
www.kfp.co.uk
• It is reckoned that 2000 industrial explosions are recorded in the EU every year