Technical Discussion on Closed drain system Knock Out Drum system Common venting system Water Seal Drum Remote Ignition system Flare system By D DAS
Need of CD, KOD,Water Seal Drum,Remote Ignition system and flare If we observe deeply the function of these systems, the main purpose comes at same roof that is SAFETY In process industry the undesired substances which are hazardous should be dispatched safely and which can not be dispatched should feed to flare system observing envormental situation.
FLARE SYSTEM PIPING Network Of LPG Recovery Plant 16 mid steel line Gas out to flare Burn Pit area n Upset Gas from plant Gas in 16 SRV out nrv KOD Water in Scrubbers CD Water drain From storage Water Seal Drum Fuel line to flare Air in Ignition Switch board Spark point Burn Pit area LCV Liquid pump To tank farm Horton sphere Common venting CD Closed Drain KOD Knock Out Drum SRV Safety Relief Valve. LCV Level control valve Water
Closed drain Closed drain means to drain liquids on closing condition from closed vessel not to be drained openly,the liquid which is undesired and separated on process. In our plant Closed Drain vessel is provided to collect liquid hydrocarbon ( as condensate) which leaves scrubbers such as Inlet gas suction scrubber (PV- 16.01),Booster compressor suction scrubber (PV-16.02), Regen gas scrubber (PV- 16.05) and Inlet filter separator( FC-12.01) through Level Control Valve or By passed valve and meet a common 3 line to CD and collected Liquid in CD is dispatched by pumping to central tank farm through 2.75 line. The top of closed drain vessel (gas vapour) enters to the top of Knock Out Drum, More over If Liquid of CD becomes beyond high level it overflows to the KOD through a non returned valve.the high level may arise if liquid is not transferred properly and timely. To get Indication of liquid level, Level Gauge Glass and Level switches are provided. Specification of CD :- radius= 0.62992mtr,height= 1.9304mtr, volume=2.4067m 3 material :- carbon steel
Knocked out drum The top of KOD is a common line 16 of plant which is connected with Pressure Safety Valves and Pilot Operated Safety Relief valve s vent ports. Released Gas from PSV and POSRV during plant upset enters into KOD via this common line and moves to wards flare through water Seal Drum. To get Indication of liquid level, Level Gauge Glass and Level switch are provided. There are two types of KOD such as horizontal and vertical. it is also known as vapor-liquid separator and flash drum. For high liquid separation and much volume gas, horizontal KOD is used. In our plant we are using horizontal KOD, It separates vapour from liquid, so that Liquid in the vent stream can not extinguish the flame or cause irregular combustion and smoking. At bottom of KOD a 2 line from LPG storage tank is provided with NRV to drain liquid and vapor. More over it is used to drain vapor of ethylmercaptan after injecting mercaptan in to LPG storage vessel which we use regularly. KOD bottom liquid which is deposited at over flow of closed drain vessel transferred to central tank farm as same procedure as of CD.
Water Seal Drums In petroleum refineries, petrochemical and chemical plants, elevated flares are the ultimate safety device. They are used to safely dispose of excess process gas that is generated from time to time by minor and occasionally major plant upsets. A water seal drum is mounted in the main flare gas line The gas line from KOD at first enters into water, Gas leaves water with bubbles to the top of the seal drum and moves to wards flare tips. A make up water level is maintained at seal drum and it over flows through drain pipes. The water seal s function is to prevent the entry of air and the development of an explosive mixture in the main plant piping.
Common Venting Line In common venting line Horton Sphere s Pressure Safety Valve s vent ports are commonly connected to a line which moves to flare through another Water Seal Drum as shown in figure. If pressure released through PSV of Horton Sphere the gas will move to flare point by this line.
Flare System In flare system the flare is ignited with remote ignition system. In remote ignition an electrical Spark plug,reliable Insulated electrical wire, step up transformer and air- gas combustible mixer are used. When Air and Gas are allowed to mix at pressure 0.6kg/cm 2 & 0.3kg/cm 2 respectively and assumed that the mixer is combustible and this mixer passes through a High Tension Electrical Plug chamber,one end of the plug is connected with step up side of transformer and other end to the body. The transformer is placed in the ignition panel. When we pushed on Ignition switch which is connected to step in of the transformer which develops 06KV from 230 volt AC, a spark is generated which we can see through the mirror of plug chamber and this spark ignites the combustible mixer and it is taken to burn pit area with the help of ½ line. Parallel to the ignition line another 3/4 pilot line is laid to the burn pit area which tip is kept near to ignition line, when fuel is available in the line we see flame after igniting the combustible mixer, The Common Venting Line and The Flare Line from water seal drums are laid to the burn pit area and tips are kept near by fuel and ignition line. Water seal drums should over flows before igniting the flare.
THE END Thank You