There is a risk of a dust explosion in many food technology applications in which bulk goods are dried, sieved, conveyed or stored. Even today, many plant operators still rely on the good fortune of never being confronted with such a dust explosion, or at least getting off lightly. In most cases, however, this hope is abruptly dashed when, as a result of an explosion and the subsequent ingress of air into the plant, entire parts of the plant burn out, the entire material is contaminated and a long shutdown of the plant for essential cleaning and repair work becomes a reality.To avoid such a scenario, the German company Thorwesten Vent has developed a special pressure relief flap that has recently been convincing in use.
In summer 2023, a well-known manufacturer successfully commissioned a total of 72 of these automatically reclosing, reusable explosion vents on four drying lines at its food production facility in Eastern Europe. The explosion protection specialists in Beckum, Germany received the order at the beginning of 2021, but the calculations, design and installation of the vents had been repeatedly delayed due to the Covid-19 pandemic.
The special feature of the new type of vents, compared to conventional pressure relief devices (e.g. bursting discs), is the automatic, airtight resealing after pressure relief. This effectively prevents the permanent entry of atmospheric oxygen and the burning of the material or entire product lines. The flaps are designed in such a way that they do not need to be replaced after an explosion and they can be reused after a visual inspection.This technology therefore minimizes damages to the system components and significantly reduces or even avoids downtimes. In addition, the explosion vents have a low heat transfer coefficient, which contributes to better thermal insulation and minimizes condensation inside the plant.
The recently completed order included equipping two wheat starch flash dryers as well as two gluten ring dryers, including the process filters and a central dust extraction filter, with explosion flaps. The relief surfaces of these components had been calculated by Thorwesten Vent in compliance with current standards and in consultation with the client. All vents are also equipped with trace heating to ensure that the pressure relief systems function perfectly at all times, even in snow and ice.
As part of the current project, the Thorwesten Vent flaps were prepared for heating operation, but a decision on whether to switch on the heating will be made after the operating experiences gained have been analyzed. Should the need to heat the explosion vents arise at a later time, the customer can convert to a complete heating function by preparing the flaps for heating operation through the quick and easy installation of control modules.
“The latest project in Eastern Europe represents an important step for Thorwesten Vent in opening up the market in the food sector, after decades of success with our products in other areas worldwide. Our high quality standards, coupled with our experience in constructive explosion protection, also predestine us for equipping systems in this sector. We therefore have good reason to hope that a new safety awareness will prevail in the food industry in the future. Because anyone who continues to focus only on the minimum requirements for explosion protection today will probably have to live with the consequences tomorrow,” commented Berthold Bussieweke, Sales Manager at Thorwesten Vent, on the successful conclusion of the order.
The use of pressure relief flaps offers significant advantages, especially in the food industry, where an explosion can have particularly serious consequences. Whereas in other areas, contamination of the material plays a minor role, contamination of foodstuffs or raw materials for their production often results in a financial desaster.
