Method and apparatus for quenching the coke drum vapor line in a coker

• US 6,758,945 B1
• Filed: 09/14/2000
• Issued: 07/06/2004
• Est. Priority Date: 09/14/2000
• Status: Expired due to Term

• Current Assignee: Motiva Enterprises LLC
• Original Assignee: Shell Oil Company (Shell Plc)
• Inventors: Haik, Stephen Michel
• Primary Examiner(s): Caldarola, Glenn
• Assistant Examiner(s): WACHTEL, ALEXIS A
• Application Number:
  US09/661,979
• Time in Patent Office: 1,391 Days
• Field of Search: 700/270, 700/282, 201/1, 201/30, 208/48.R, 208/48.Q, 208/131, 208/DIG.1, 203/1, 203/2, 202/227
• US Class Current: 202/227
• CPC Class Codes: C10B 55/00 Coking mineral oils, bitumen, tar, and the like or mixtures thereof with solid carbonaceous material cracking oils C10G
• CPC Class Codes: C10G 9/005 Coking (in order to produce liquid products mainly)
• CPC Class Codes: Y10S 208/01 Automatic control

Abstract

A method and apparatus for quenching the coke drum vapor line from a coke drum to the main fractionator in a coker unit whereby the volume of quench liquid prevents the drum vapor line from plugging with carbon-based deposits. A differential pressure control technique is utilized to quench the drum vapors being delivered to the fractionator as opposed to a temperature, delta temperature, uninsulated vapor line, or fixed flow rate control as used in the prior art. Vapor line quench control by differential pressure prevents over-quenching of the vapor line during a coke drum switch, unit startup, or slowdown as well as under-quenching during drum warm-ups. It improves the fractionator recovery time from a drum switch and overall liquid product yield during the drum cycle which can be produced by over-quenching. It also prevents the vapor line from drying out at anytime, an under-quenched condition, as long as the quench oil quality and conditions do not vary significantly.

Claims

1. A delayed coker comprising:

an active coke drum having a pressure transducer for measuring the pressure within said drum, said coke drum being adapted to receive hot fractionator bottoms from a fractionator, to capture the carbon from said bottoms and to pass vapors from said bottoms to a vapor line;

means for injecting a quench liquid into said vapor line;

a fractionator, adapted to receive said vapors from said vapor line, to receive a hydrocarbon feed material thereinto and having means for measuring the pressure therein;

a controller for receiving pressure signals from said coke drum and said fractionator and for calculating the pressure differential therebetween;

means for generating a signal representing the feed rate supplied to said fractionator and supplying said signal to said controller; and

means within said controller for evaluating said pressure differential and said feed flow input rate data and generating, in response thereto, a signal for controlling a selected amount of quench liquid to be injected into said vapor line.

2. The apparatus of claim 1 further including at least one additional coke drum in parallel with said active coke drum.

3. In a delayed coker unit having a coke drum and a fractionator connected by a vapor line, a method for measuring and controlling the amount of flow of quench liquid injected into said vapor line, comprising the steps of:

measuring the pressure within said coke drum;

measuring the pressure within said fractionator;

measuring the total flow rate of a liquid feed supplied to said fractionator;

supplying, to a controller, said measured pressures and said measured total flow rate of feed liquid being supplied to said fractionator;

using coke drum vapor line thermodynamics to evaluate the relationship between said pressure differential and said feed flow input rate data;

determining, from said relationship, the amount of quench liquid which must be supplied to said vapor line in order to maintain a desired flow rate of liquid through said vapor line and into said fractionator;

generating, in response to said relationship, a signal for controlling a selected amount of quench liquid which must be injected into said vapor line in order to result in the desired flow rate of liquid through said vapor line and into said fractionator; and

controlling the flow rate of quench liquid injected in said vapor line by supplying said generated signal to a supply valve for opening and closing said valve in response to said generated signal.