Apparatus and method for mechanically reducing internal pressure of column in refinery or petrochemical process
Disclosed is an apparatus and method for mechanically reducing internal pressure of a column in a refinery or petrochemical process, which uses a safety relay valve for operating an emergency shutdown valve able to mechanically block the supply of a heat source in the process, thus reducing the mounting cost, simplifying the process and ensuring high reliability thanks to the use of mechanical signals.
1. An apparatus for mechanically reducing an internal pressure of a column in a refinery or petrochemical process, comprising:
an emergency shutdown valve for blocking supply of a heat source to the column positioned between a heat source and the column; and
a safety relay valve for mechanically operating the emergency shutdown valve using the internal pressure of the column connected with a emergency shutdown valve and the column through a pipe,
wherein the safety relay valve comprises a hollow valve body having at a lateral wall thereof ventilation ports through which compressed air in the column for operating the emergency shutdown valve flows, a plunger for opening or closing the ventilation ports with the compressed air while moving in the hollow valve body, a spring section having a predetermined pressure value being lower than that of the safety relay valve provided in the apparatus and connected to one end of the hollow valve body so as to apply pressure to the plunger, and a pressure transfer section connected to the other end of the hollow valve body so as to transfer the internal pressure of the column to the plunger.
2. The apparatus as set forth in claim 1 , wherein the plunger has a large-diameter portion having a diameter identical to an inner diameter of the hollow valve body and a small-diameter portion having a diameter less than the inner diameter of the hollow valve body, so as to control opening or closing of the ventilation ports while moving in the hollow valve body.
3. The apparatus as set forth in claim 1 , wherein the hollow valve body of the safety relay valve has a fixing pin for fixedly holding the plunger which is moved up.
4. The apparatus as set forth in claim 2 , wherein the large-diameter portion and the small-diameter portion of the plunger are disposed so that the compressed air is introduced into the emergency shutdown valve through the ventilation ports before the plunger is moved up, and are disposed so that the compressed air introduced into the emergency shutdown valve is discharged to an atmosphere when the plunger is moved up.
5. The apparatus as set forth in claim 1 , wherein the pressure transfer section has a disk for pushing up the plunger using the internal pressure of the column, and a discharge pipe for discharging a fluid in the column introduced into the pressure transfer section.