Explosion decoupling inside connected ductwork to protect separators

Transcription

1 Back pressure flap ProFlapII Explosion decoupling inside connected ductwork to protect separators ProFlap back pressure flap prevents the spread of explosive pressure and explosion flame to other areas. fan mounting distance capturing back pressure flap separator explosion pressure relief Staff working at the collection points, or system components at the suction side, are protected against explosion impacts.

2 Function The task Numerous processes can create explosive dust/air mixtures inside industrial systems (eg., dust collectors, mixing machines, fluid bed granulators, mills, etc.). If ignition sources cannot be prevented due to process conditions, these systems are often equipped with constructive explosion preventive measures, such as pressure relief or pressure suppression. In this regard, ductwork is decoupled from the separators for protection so that no flames and explosion pressure can be transferred into other areas. mounting distance Sample application of an exhaust system that is equipped with explosion pressure relief: fan capturing back pressure flap separator explosion pressure relief The Solution Keller developed the back pressure flap series ProFlapII for effective explosion decoupling for nearly all industrial sectors. The ProFlapII is certified as a protective system according to EU Guideline 94/9/EG (ATEX 95) and is approved for decoupling of dust explosions of organic and mineral dusts. Following functions are patented: Monitoring function with sensor for wear and sediments Flap damper Flap blade locking ProFlapPlusII Normal operation During operation, the back pressure flap mounted on the suction side is kept open by the air flow. When fully stopped, the flap closes by its own weight. When the system starts up, the opening of the flap is restrained by a damping element in some designs. The downstream mounted back pressure flap is kept open by the air flow In the event of an explosion 2 During an explosion inside a protected system, the flap is closed by the pressure surge inside the ductwork. The explosion flame and the pressure cannot spread back into the ductwork. Operators at capturing points, or suction-side system parts, are protected against explosion impacts. The flap damping element (or the locking system in some versions) prevent the flap from opening following an explosion due to the occurring vacuum. During an explosion within a protected system the flap closes due to the pressure surge from spreading within the ductwork

3 Versions at a glance ProFlap II Standard design The standard design is available for dusts of dust explosion category St-1 (ProFlapII-St-1) and St-2 (ProFlapII- St-2) ProFlapPlusII Design including surveillance function ProFlapPlusII can be equipped with a monitoring package to extend the maintenance intervals. It is also available for both designs (St-1 and St-2) and consists of a wear sensor and a flap sensor. The wear sensor monitors the material removal in the housing and ensures adequate shock pressure resistance to the back pressure flap in case of an explosion. The flap sensor monitors the flap blade s end position and can detect an explosion early as well as wear or sediments at the flap blade. The sensors are connected to a terminal box. Signal evaluation is performed by the control unit of the system provided by the customer. As an alternative, a separate electrical control unit can be obtained from Keller (see accessories ). Stop flap blade Flap blade locking System in operation (flap blade opened) Air flow Flap sensor Wear sensor Flap blade Level sensor ProFlapII-US Version for absolute safety The American National Fire Protection Association NFPA establishes in its standard 69 stricter safety requirements for back pressure flaps. This is why the new ProFlapII-US series was equipped with a flap blade locking and a level sensor. The locking unit prevents the flap blade from opening following an explosion due to the vacuum. The level sensor detects sediments in the back pressure flap- early and reduces the risk of possible fire or explosion. The US-design is also available with an optional monitoring package (ProFlapPlusII-US). ProFlapII- St-1 ProFlapII- St-2 ProFlapPlusII- St-1 ProFlapPlusII- St-2 ProFlapII- US ProFlapPlusII- US Rotation damper X X Flap blade locking X X X X Flap sensor X X X Wear sensor X X X Level sensor X X 3

4 Dimensions, technical data Type Nominal Width Length L Width B Height H (standard) Height H (US- Version) Height S Weight Pressure loss on 20 m/s Pitch circle circumference Screw Size Screw Length NW mm mm mm mm mm Kg Pa mm ProFlapII_ M10 30 ProFlapII_ Ca M10 30 ProFlapII_ Ca M10 30 ProFlapII_ M10 30 ProFlapII_ M10 35 ProFlapII_ M10 35 ProFlapII_ M10 35 ProFlapII_ M10 35 ProFlapII_ M10 35 ProFlapII_ M10 35 ProFlapII_ Ca M12 35 ProFlapII_ Ca M12 35 ProFlapII_ Ca M12 35 ProFlapII_ Ca M12 35 ProFlapII_ Ca M12 35 ProFlapII_ Ca M12 35 Mounting position: horizontal, on the suction side (fan behind ProFlapII) Air flow velocity: m/s Temperatures: -10 to + 60 C Materials: housing: S235JRG2, flap: stainless steel Paint finish: RAL 3000 blazing red Nominal width Height Pivoting range Width Pitch circle circumference Installation length 4

5 Type Number of screws Pieces Possible Dust Explosion Class Max. KST-Wert Bar x m/s Max. reduced excess pressure (pred, max) in the container filter)* Pressure surge resistance of back pressure flap Min. installation distance at St1 Min. installation distance at St2 Max. installation distance at St1 Max. installation distance at St2 Bar Bar m m m m ProFlapII_140 8 St1 und St ProFlapII_160 8 St1 und St ProFlapII_200 8 St1 und St ProFlapII_250 8 St1 und St ProFlapII_280 8 St1 und St ProFlapII_315 8 St1 und St ProFlapII_355 8 St ProFlapII_ St ProFlapII_ St ProFlapII_ St ProFlapII_ St ProFlapII_ St ProFlapII_ St ProFlapII_ St ProFlapII_ St ProFlapII_ St Subject to modifications. * The ductwork between ProFlapII and explosion protected housing/filter will have the same max. reduced Pred, max (normally at least 2 mm sheet thickness, welded). ProFlapPlusII 5

6 Scope of applications Downstream explosion decoupling of dry dust separators when grinding fiberglass reinforced components for chemical and pharmaceutical industries for lumber industry for varnish dusts etc. for blasting plants Explosion decoupling for dryers, air separators, mills, silos, fluid bed granulators, etc. Solutions are also available for dust concentrations exceeding the lower explosion limits. Advantages certified according to the latest test standard CEN/TC 305/WG 3 N457 (Stand: 05/2012) applicable for organic and mineral dusts passive system, no triggering sensors required inexpensive in comparison to other decoupling systems modular monitoring package for system control and greater inspection intervals easy access using fasteners, without loose components ease of access for inspection with swiveling flap integrated consoles for easy assembly variable mounting distances (for suction ducts, the referenced distances are minimum dimensions) application feasible for dust concentrations beyond the lower explosion limits (specified distances must be strictly adhered to) Simulation systems When developing the monitoring sensors, up-to-date air flow simulation systems were used in order to deter- mine ideal positioning of the sensors. directly advancing flow flow advancing from below advancing flow from above laterally advancing flow CFD ProFlapII NS315 simulation parameters: velocity of oncoming flow : 20 m/s particle mass flow (silica): 5,7 g/s particle size distribution (silica): 10µm up to 500µm Effect of particles impacting on sheet metal (indication of abrasion): blue: no abrasion red: increased abrasion 6

7 Easy maintenance and safe To keep maintenance, inspection and service work as simple as possible, the back pressure flap is equipped with an inspection door. From size DN 630 the inspection doors are equipped with two additional gas pressure springs for an easier opening and closing function as well as with a support device to attach it in open position. Support device Gas pressure spring Accessories A separate electrical control cabinet is available with integrated switch amplifier for the wear sensor. Guidelines and Standards Back pressure flaps are subject to a design check according to EU Guideline 94/9/EC (ATEX 95), latest standard applicable. Quality assurance is audited according to 94/9/EC (ATEX 95) and is regularly controlled. It is therefore permissible to return the back pressure flaps into circulation as independent protection systems. 7

8 Back pressure flap ProFlapII Keller Lufttechnik alle Rechte vorbehalten. Änderungen vorbehalten. 04/2014