Practical Process Engineering

Back pressure regulator+ flame arrester+ thermal shutoff bypass (all in one)

Hydraulic flame arresters are particularly suitable to protect plants which supply heavily contaminated, sticking, polymerizing or even foaming substances into thermal combustion units. The flammable mixtures are passed through a water seal with a defined immersion depth. The mixture flow is prorated up and passed to the individual sparge pipes. The sparge pipes have small drill holes and therefore produce defined bubble columns. In case of an ignition in the flowing gas mixture the flame is prevented from transmission into the inlet line. The following parameters have a significant effect on the flame arresting efficiency of the device in case of deflagrations, detonations or short time burning: • Mixture volume flow • Immersion depth from the water seal’s surface to the upper edges of the drill holes in the sparge pipes • Water temperature in the hydraulic flame arrester • Sizes, form and density of the bubbles and therefore the precise drill hole diameter in the sparge pipes. If the mixture ignites under certain operating conditions within the hydraulic flame arrester and burns directly on the liquid surface prevention of flame transmission can only be guaranteed for a limited amount of time. Therefore, a number of temperature sensors are installed in the gas space and when reaching a specified temperature they trigger appropriate emergency functions upstream in the system connected (shut down, inerting, etc.). A high accuracy volume flow meter must be installed as an essential technical safety element. It has to guarantee that the maximum allowable volume flow, on which the design of the hydraulic flame arrester has been based, is recorded and limited so that emergency functions are triggered if the off gas volumes exceed the safe level. In addition, a minimum flame-transmission-proof immersion height is necessary, i.e. an adequate water level must be guaranteed by suitable measuring equipment.

1- Immersion tank 2- Sparge pipes 3- Manifolds 4- Inspection glasses 5- Nozzle (minimum=1) 6- Exhaust gas nozzle 7,8- Level measurments nozzles 9, 10- Level control nozzles 11- Draining nozzle

Hydraulic flame arrester

In-line detenation flame arrester + pressure reliefe valve equiped with shock absorber -Applicable as a detonation-proof check valve in suction lines of storage tanks - Optimum for use as an overflow valve in venting and recovering vapour lines

Small and unidirectional detonation flame arrester with right angle design

Ecentric in-line flame arrester prevents collection of condensate. Also, it allows to install it close to the ground level.

In line flame arrester with temperature transmitter at both side for short-time burning detection

NOTE: When installing the deflagration flame arrester, make sure that the distance between potential ignition sources and the location of the installed device, does not exceed the L/D ratio (pipe length/pipe diameter), for which the device was approved. According to EN ISO 16852 the installation limits are (L/D)max ≤ 50 for deflagration flame arresters of explosion groups IIA and IIB3 (NEC groups D to C) and (L/D)max ≤ 30 for explosion group IIC (NEC group B). The manufacturer must be consulted for exact L/D. Please note that detenotion flame arresters have no limitation on location. But, they should be loacated somewhere accessable to inspection and maintenace crew.

#MESG

#MESG

#MESG

#Flame_Arrester_Location - End of line: At the opening of a system part to the atmosphere It protects against atmospheric deflagrations and stabilised burning — either short time burning or endurance burning. They can only be connected on one side and can not be installed in the pipe. - In line: In the pipe It protects against deflagration , stable or unstable detonations in pipes. Stable detonation flame arresters avoid an explosion transmission of deflagrations and stable detonations. In-line flame arresters which are tested against unstable detonations protect from deflagrations, stable and unstable detonations. - Pre-volume: At the opening of an equipment onto a connecting pipe They are flame arresters which avoid flame transmission from the inside of an explosion proof vessel to the outside or to a conntected pipe. The flame arresters should be located according to their specified use. In the case of in-line deflagration flame arresters, make sure that the allowable L/D (L = distance between the ignition source and the installation location of the flame arrester, D = pipe diameter) is not exceeded and that the in-line deflagration flame arresters are not installed too far from the ignition source, so that they are not subject to a detonation because the path is too long. The allowable L/D is stated in the manufacturers manual of the flame arrester.

#Explosion_groups Different gases have different flame propagation capacities and are therefore categorized into explosion groups corresponding to their hazard level. The yardstick for this is the MESG = Maximum Experimental Safe Gap, a characteristic number measured in the laboratory for the flame propagation ability of the product. The MESG or standard gap width is the largest gap width between the two parts of the interior chamber of a test setup which, when the internal gas mixture is ignited and under specified conditions, prevents ignition of the external gas mixture through a 25 mm long gap, for all concentrations of the tested gas or vapour in air. The MESG is a property of the respective gas mixture [EN 1127-1]. The test setup and methods are specified in EN 60079-20-1. The most explosive composition is close to the stoichiometric mixture of the gas/vapour-air mixture.

b) Liquid seal flame arrester In liquid seal flame arresters liquid barriers stop the entering deflagration and/or detonation before it reaches the protected components. Two different types exist: 1. The liquid product flame arrester: the liquid product is used to form a liquid seal as a barrier for flame transmission. 2. The hydraulic flame arrester: it is designed to break the flow of an explosive mixture into discrete bubbles flowing through water which acts like a liquid barrier. c) Dynamic flame arresters High velocity flame arresters are designed to produce flow velocities under operating conditions which exceed the flame velocity of the explosive mixture thus preventing flame transmission.

Flame quenching: By heat dissipation in the boundary layer “s”, transferring it to the large surface of the gap-length compared to the gap-width “D” and cooling-down the product below its ignition temperature the flame is extinguished. The gap width and the gap length of the flame arrester element determines its extinguishing ability. The narrower and longer the gap, the greater the extinguishing effectiveness. The wider and shorter the gap, the lower the pressure loss. The optimum solution between the two conditions is determined by experiments.

#Flame_Arresters Flame arresters are devices that are installed at the opening of an enclosure or to the connecting pipe of a system of enclosures and whose intended function is to allow flow but prevent the transmission of flame. Flame arresters are subdivided into different types depending upon the combustion process (Endurance burning, Deflagration, Detonation and the various sub-groups) and in accordance to the installation (in-line, end-of-line, in equipment). Master types are a) static dry flame arresters b) static liquid seal flame arresters c) dynamic flame arresters a) Static dry flame arresters Flame arrester elements made of wound corrugated metal strips can be manufactured with consistantly reproducible flame quenching gaps. The gap-size can be adjusted in accordance to the flash-back capability of the explosive mixture. When a mixture ignites in a gap between two walls, the flame spreads towards the non-combusted mixture. The expansion in volume of the combusted mixture pre-compresses the non-combusted mixture and accelerates the flame. 👇🏼👇🏼👇🏼👇🏼