Coke drum with air injection system for skirt junction

Abstract

A coke drum includes a coke drum vessel having a substantially cylindrical wall and a conical bottom portion; a skirt downwardly depending from a transition of the cylindrical wall into the conical bottom portion, an inner annular space being defined between the skirt and the conical bottom portion; and a fluid injection system communicated with the inner annular space for injecting fluid at a desired temperature to heat or cool the inner annular space. The fluid injection system allows the inner annular space and junction of the skirt with the coke drum vessel to be heated or cooled to minimize temperature difference between these areas and a batch of coke to be introduced into the drum.

We claim: 
     
         1 . A coke drum, comprising:
 a coke drum vessel comprising a substantially cylindrical wall and a conical bottom portion;   a skirt downwardly depending from a transition of the cylindrical wall into the conical bottom portion, an inner annular space being defined between the skirt and the conical bottom portion; and   a fluid injection system communicated with the inner annular space for injecting fluid at a desired temperature to heat or cool the inner annular space.   
     
     
         2 . The coke drum of  claim 1 , wherein the fluid injection system comprises a toroid tube in the inner annular space and communicated with a source of the fluid. 
     
     
         3 . The coke drum of  claim 1 , wherein the fluid injection system has a fluid inlet and a fluid outlet, and at least one baffle in the inner annular space between the fluid inlet and the fluid outlet. 
     
     
         4 . The coke drum of  claim 1 , further comprising a bottom wall section connected between the skirt and the conical bottom portion and closing off the inner annular space. 
     
     
         5 . The coke drum of  claim 1 , wherein the fluid injection system comprises a first toroid tube defining a fluid inlet, a second toroid tube defining a fluid outlet, and a series of baffles in the inner annular space between the first toroid tube and the second toroid tube. 
     
     
         6 . The coke drum of  claim 5 , wherein the series of baffles direct flow of fluid along the skirt and conical surfaces of the drum. 
     
     
         7 . The coke drum of  claim 1 , wherein the fluid injection system injects fluid around an entire circumference of the inner annular space. 
     
     
         8 . A process for protecting a coke drum from thermal stresses, comprising the steps of:
 determining coke temperature of coke to be introduced to a coke drum, wherein the coke drum comprises:
 a coke drum vessel comprising a substantially cylindrical wall and a conical bottom portion; 
 a skirt downwardly depending from a transition of the cylindrical wall into the conical bottom portion, an inner annular space being defined between the skirt and the conical bottom portion; and 
 a fluid injection system communicated with the inner annular space for injecting fluid at a desired temperature to heat or cool the inner annular space; and 
   introducing fluid at a temperature substantially similar to the coke temperature through the fluid injection system and into the inner annular space, whereby temperature of the inner annular space and a junction of the skirt with the coke drum vessel is adjusted to be substantially similar to the coke temperature.   
     
     
         9 . The process of  claim 8 , wherein the fluid injection system comprises a toroid tube in the inner annular space and communicated with a source of the fluid. 
     
     
         10 . The process of  claim 8 , wherein the fluid injection system has a fluid inlet and a fluid outlet, and at least one baffle in the inner annular space between the fluid inlet and the fluid outlet. 
     
     
         11 . The process of  claim 8 , further comprising a bottom wall section connected between the skirt and the conical bottom portion and closing off the inner annular space. 
     
     
         12 . The process of  claim 8 , wherein the fluid injection system comprises a first toroid tube defining a fluid inlet, a second toroid tube defining a fluid outlet, and a series of baffles in the inner annular space between the first toroid tube and the second toroid tube. 
     
     
         13 . The process of  claim 12 , wherein the series of baffles direct flow of fluid along the skirt and conical surfaces of the drum. 
     
     
         14 . The process of  claim 8 , wherein the fluid injection system injects fluid around an entire circumference of the inner annular space. 
     
     
         15 . A method for adapting an existing coke drum, comprising the steps of:
 providing an existing coke drum having a substantially cylindrical wall transitioning to a conical bottom portion, and having a skirt downwardly depending from a transition from the substantially cylindrical wall to the conical bottom portion; and   positioning a fluid injection system relative to an inner annular space defined between the skirt and conical bottom portion whereby temperature of a junction of the skirt and the coke drum can be adjusted by introducing fluid at a desired temperature through the fluid injection system and into the inner annular space.