To delay the coking process and subsequent fouling of the furnace tubes with solid coke, the hot feed velocity through the tubes is controlled, typically between six to ten feet per second. Refiners can process heavier, cheaper crudes to increase their. There are two types of coking processes, fluid cokers and delayed cokers. In the training module on the delayed coker process, a typical coking process. Delayed coking schemes are most economical for heavyoil.
Delayed coking fundamentals colorado school of mines. Premium coke having a low coefficient of thermal expansion and containing reduced fluff coke is obtained by subjecting an aromatic mineral oil to reduced temperature delayed coking, thereafter converting uncoked oil in the coke drum to coke under delayed coking conditions by continuing coking in the presence of a aromatic mineral oil capable forming coke admixed with a non coking material. Process description gela refinery mostly treats heavy crude and residual products. In the delayed coking process, many of these lateforming volatiles remain trapped in the coke. Support facilities include closed blowdown, coke cutting and handling, and a water recovery system.
Delayed coking is one of the chemical engineering unit processes used in many petroleum refineries. Surface fouling causes contamination, promotes corrosion, reduces flow, increases maintenance, and ultimately inflates costs while worsening performance. In delayed coking, the temperature controls the quality of the coke produced. Coking process technologies available commercially differ in the type of reactor used and fall into two main categories.
Delayed coker overview a delayed coker or delayed coking unit also called a dcu or coker is a refinery unit employed to process the heaviest components of crude oil. Delayed coking process design, operations and optimization. In the delayed coking process, the aim is an economical conversion of residual feedstocks, especially vacuum residues short residues to lighter, more valueadded products and if possible, to produce a coke material of desired quality. Coking is the primary process used to upgrade petroleum residues. A significant number of recent projects have selected delayed coking due to the technologys ability to fully convert nondistillables. This process yields higher value liquid products and creates a solid carbonaceous residue called coke. The feed to coker is usually vacuum residue which is high on asphaltenes, resins, aromatics. The delayed coker unit animation describes the coking process in a step by step manner. Coking is a refinery process that produces 19% of finished petroleum product exports source. The cracking and coking reactions are initiated in the fired heater under controlled timetemperaturepressure conditions. Since world war ii the demand for light products e. The process promotes the release of these lateforming cracked volatiles, allowing them to escape into the gas phase by breaking the solid coke into small particles. However, larger units have tandem pairs of drums, some with as many as 8 dr. Refinery overhead plants management aims at saturating both coking units, by adapting other units downstream and upstream to reach this goal.
The coker cracks converts the asphaltlike feedstock to a combination of products for further processing to gasoline and diesel feedstock, a coallike material called petroleum coke, plus light gas. High velocities are maintained in the furnaces in order to prevent significant coke formation. The unit takes vacuum resid fresh feed, heats it and injects it into the main fractionator bottom, where it is mixed with an internal reflux recycle of heavy cracked material. Photograph of a 4drum delayed coking unit in a benica petroleum refinery in california. Attend delayed coker operations and reliability training or delayed coking process, design and troubleshooting training courses. Lecture 4 thermal cracking, visbreaking and delayed coking. The yield of coke from the delayed coking process ranges from about 18 to 30 percent by weight of the feedstock residual oil, depending. Delayed coking process is a thermal process which increases the molecular aggregation or association in petroleumbased residues or coal tar pitches leading to extended mesophase domains. Delayed coking article about delayed coking by the free. With refinery feed slates becoming more viscous, acidic or sulfur laden, global refiners are preparing for heavier crudes and bitumen from the middle east. The adjacent photograph depicts a delayed coking unit with 4 drums.
Delayed coking fundamentals pdf prepared by paul j. In order to maximize coking production and related light distillates it is equipped with two delayed coking units. Sep 17, 2017 the delayed coker unit animation describes the coking process in a step by step manner. The process involves adding small amounts of cracking catalyst and hydrogen to the hydrocarbon feedstock before it is charged to the coking drum. Although first delayed coking plant was built in1930, however delayed coking process has been evolving for 78 years, the past few years have seen changes in feed stock that has major. Delayed coking is a thermal cracking process to upgrade and convert petroleum residuum into liquid and gas product streams leaving behind a solid concentrated carbon material, petroleum coke.
It is already known that the chemical and physical properties and composition of the feedstock and processing conditions affect coke morphology. Premium coke having a low coefficient of thermal expansion and containing reduced fluff coke is obtained by subjecting an aromatic mineral oil to reduced temperature delayed coking, thereafter converting uncoked oil in the coke drum to coke under delayed coking conditions by continuing coking in the presence of a aromatic mineral oil capable forming coke admixed with a noncoking material circulated through the coke. Delayed coking process consists of furnaces, coke drums and a main fractionator. The reactions continue as the process stream moves to. Delayed coking valve number valve description design temperature range design pressure range pipe size recommended valve1 deg f deg c psig bar g inches dn cseries isolator 2.
Short contact time thermal conversion process rapid thermal processing that operates at moderate temperature and atmospheric pressure. Delayed coking delayed coking process is used to crack heavy oils into more valuable light liquid products with less valuable gas and solid coke as byproducts. Refining processes course curriculum, colorado school of mines, taught by. The inherent flexibility of the delayed coking process to handle different feedstocks promises the refiner a solution to the problem of decreasing residual fuel. Fccs, hydroprocessing, crude units, and others typical rtos are applied to continuous processes that operate at steadystate. This option can be utilized in improving the run length of coker heater. A catalytic delayed coking process is disclosed that gives increased distillate yield and reduced coke make. Another way to illustrate the basic coke drum operation will be employed in this section, the pressuretemperature profile for one complete cycle. Delayed coking variables there are three classes of variables affecting coking. Delayed coking process1 cracking chemistry oil refinery. Cracking and coking reactions are initiated in the furnaces under controlled timetemperaturepressure conditions. Temperature is used to control the severity of coking. Paul of great lakes carbon corporation of port arthur, tx.
In its simplest terms, delayed coking is a semibatch thermal cracking process using alternating drums that are switched offline after filling. This cracks the long chain heavy carbon and hydrogen molecules of the residual oil into coker gas oil and pet coke. A delayed coker is a type of coker whose process consists of heating a residual oil feed to its. Pdf delayed coking units convert heavy crude oil or topping refinery residue to.
Pdf advanced control of the delayed coking unit in. The block diagrams of the systems were constructed and the process transfer. Delayed coking is one of the unit processes used in many oil refineries. This document focuses on the coke drums, which are large cylindrical metal vessels that can be up to 120 feet tall and 29 feet in diameter. This process produces a solid coke which has a high carbon content. As the supply of lighter crude oils has diminished, refiners. This is achieved by holding them at an elevated temperature usually 750 k765 k over a period of time 12 to 36 h. Reproduced with permission from valero energy corporation. Delayed coking delayed coking is a type of thermal cracking in which the heat required to complete the coking reactions is supplied by a furnace, while coking itself takes place in drums operating continuously on a 24 h filling and 24 h emptying cycles. We are delighted to continue to support the development of duqm refinery and will draw on our experience of delivering our marketleading delayed coking technology and proprietary equipment at greenfield refineries across the globe, bob macdonald, ceo of woods specialist technical solutions business said. In the training module on the delayed coker process, a typical coking process and decoking cycle operation.
Coking is a refinery process that produces 19% of finished. Pdf process flow determines coker heater performance. The catalyst settles out in the coke and does not affect the utility of the coke. All of the heat necessary for coking is provided in the heater, whereas coking takes place in the coke drum. The main objective of the delayed coking unit is to convert low value residual products to lighter products of higher value and to produce a coke product. High velocities are maintained in the heaters in order to prevent significant coke formation. Coking is a refinery unit operation that upgrades material called bottoms from the atmospheric or vacuum distillation column into highervalue products and, as the name implies, produces. Delayed cooking is one of the most difficult refinery units to operate and control. Delayed coking produces 19% of finished product exports according to eia. Therefore, there are at least two coke drums in every delayed coking unit, and some units have more than two drums. Delayed coking process design, operations and optimization may 2012.
Delayed coker free download as powerpoint presentation. In delayed coking, the process is designed so that the coke forms in a drum. The adjacent photograph depicts a delayed coking unit. In brief, the process heats the residual oil from the vacuum distillation unit in a petroleum refinery to its thermal crackingtemperature in the heat transfer tubes of a furnace. Petroleum refining petroleum refining visbreaking, thermal cracking, and coking. Furthermore, implementing advanced process control apc on a delayed cooker is difficult. Research institute of petroleum processingripp shen haiping. Unit ontime capacity has been increased, contributing to the units cash flow. The hot product vapors and steam from the top of the drum are quenched by the incoming feed in the fractionator to prevent coking in the fractionator and to strip the lighter components of the vacuum residue feed. Delayedcoking process update acs symposium series acs. Delayed coking is a key technology for residue upgrading or zero fuel oil production. Oct 31, 2017 fouling, coking or simply sticking is a costly surface problem that occurs in most industrial applications. The process flow in all cases involves a crude unit including desalting followed by atmospheric and vacuum distillation. Important recent trends and new developments have contributed to profitable, reliable, and safe operation of delayed cokers.
A delayed coker is a type of coker whose process consists of heating a residual oil feed to its thermal cracking temperature in a furnace with multiple parallel passes. Uniform tube metal temperature resulting from a change in process flow enhances the run length of a delayed coker heater. Delayed coking is a type of thermal cracking in which the heat required to complete the coking reactions is supplied by a furnace, while coking itself takes place in drums operating continuously on a 24 h filling and 24 h emptying cycles. Maximize distilate yeilds hydrocracking altrernative. Bitumen silt which is a result the oil recovery process. The delayed coking process will be described by walking through the individual pieces of equipment with a brief description of the various process steps within the equipment. This presentation provides an overview of the delayed coking system found in. Hazards of delayed coker unit dcu operations august. Coking 101 an introduction to delayed coking prepared by. There are two kinds of coke produced by delayed coking of vdr.
The presentation has been designed for those professionals who are interested in the operation, process engineering, technical support or design of a delayed coking unit. Cracking begins in the furnace, continues in the transfer line, and finishes in the coke drum. Unique thermal cracking technology that solves some of the disadvantages of delayed coking. Delayed coking itself is environmentally friendly in a refinery context in that it helps upgrade and recover heavy and waste oils that would otherwise be a problem for disposal. Delayed coking process animation dcu unit operation. Delayed coking is a thermal cracking process used in petroleum refineries to upgrade and convert petroleum. The total fresh and recycled feed is then heated implementing coker advanced process control. Current situation of emerging technologies for upgrading. Petroleum downstream crash course 17 delayed coking. This cracks the heavy, long chain hydrocarbon molecules of the residual oil into coker gas oil and petroleum coke. Process description basic pressure temperature profile in the previous section, the delayed coking process was described by using the process flow diagram pfd and coke drum schematic. Numerous process rto models in romeotm within exxonmobil. Pdf advanced control of the delayed coking unit in khartoum. The porousity gives it a high surface area, which makes it burn faster as does a sheet of paper versus a wooden log.
Delayed coking process animation dcu unit operation duration. Londono principal process engineer delayed coking process advantages benefits of delayed coking foster wheeler in the delayed coking industry latest advances on sydecsm delayed coking agenda. Delayed coking was the first type of coker introduced in the refining market place. They are related to process operating variables, feedstock characterization and engineering variables as shown in table below. A delayed coker is a type of coker whose process consists of heating the residual oil feed to its thermal cracking temperature in a multi parallel pass furnace. Delayed coking is a thermal cracking process used in petroleum refineries to upgrade and convert petroleum residuum bottoms from atmospheric and vacuum distillation of crude oil into liquid and gas product streams leaving behind a solid concentrated carbon material, petroleum coke. Quote by principal design engineer delayed coking and the environment. Armin gunther and pietro di zanno, biomasstoliquid btl congress, berlin scroll down to pdf page 9 of 21 pdf pages. Consultant expert witness lng liquefied natural gas. The product yields, consisting of light ends, naphtha, distillates, heavy coker gas oil hcgo, the byproduct coke are dependant on the feedstock and qualities. Delayed coker operators with a pitpad system have made efforts, together with mechanical equipment suppliers, to improve the mechanical steps in the process, in particular with installation of top and bottom unheading equipment.
Hazards of delayed coker unit dcu operations august 2003. This results in excessive amounts of gas oil being sent to the delayed coker kbc has developed a detailed heater fouling model predicts coke deposited on the heater tubes used to estimate run length based on feed quality, operating conditions and heater geometry includes transfer line from the heater outlet to the vacuum tower. Petroleum refining visbreaking, thermal cracking, and coking. Delayed coking is the technology most used to upgrade vacuum residue into highvalue products, but in this process, secondary reactions produce coke. The process a refinerys delayed coking unit is not new technology, but is the most common process to upgrade the residual hydrocarbons remaining after upstream processing to remove water and soluble salts in the crude desalter. Also, by discussing some of the delayed coking process problems encountered in the industry, we hope to encourage new advances, solutions, and improvements for the future.
A delayed coker or delayed coking unit also called a dcu or coker is a refinery unit employed to process the heaviest components of crude oil. The preheated feed is flown into the bottom of the reactor, an isolated. Premature failure can lead to extra costs for operator overtime, additional manpower for manual valve operation, replacement costs and potential refinery downtime, not to mention the safety aspects of manual operation. Coking 101 an introduction to delayed coking process.
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