Q & A > Question Details
I have some question about R2R(RFCC) VOV (Variable orifice valve) in #2 Regenerator Flue Gas Duct .
Recently we experienced the hot spot of VOV Body.
Its temperature by thermo vision is 590 ‘C.
So we concerned about damage of VOV body Refractory.
Could you suggest the possible cause or countermeasure for this problem? (steam jacketing?)
In 2010 TA we plugged 5 orifice hole of total 10 orifice hole. And the half of VOD Disc is eroded. And current VOV opening is 65% and Delta P is 1.2 kg/cm2 G.
05/08/2013 A: Prabhat Choudhary , IOCL, prabhatchoudhary26@gmail.com
Steam jacketing or steam lancing is the only option till you take a shut down and go for refractory repair. Orifice chamber hot spot comes normally just near the spring support due to less or improper relative movement between refractory and metal body.in our unit this temp also found raised up to 550 degC level.
13/08/2011 A: Bob Kalaria, KBR, bhavdip.kalaria@kbr.com
Steam Jacketing is a good option. However, it is not a permanent solution. The main reason for refractory erosion is because the DP through the VOV valve is too high. Ideally this DP should be about 0.35-0.5 kg/cm2 range. High DP will cause high vena contracta velocity at valve throat. With this high DP, I believe the throat velocity is too high and is causing the refractory erosion.
As you did before, plugging the orifice will improve this situation. In order to maintain 0.35 to 0.5 kg/cm2 DP through VOV, you may need to plug more orifices.