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. 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. A catalytic delayed coking process is disclosed that gives increased distillate yield and reduced coke make. Quote by principal design engineer delayed coking and the environment. Research institute of petroleum processingripp shen haiping. Delayed coking is a thermal cracking process used in petroleum refineries to upgrade and convert petroleum. With refinery feed slates becoming more viscous, acidic or sulfur laden, global refiners are preparing for heavier crudes and bitumen from the middle east.
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. 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. In delayed coking, the process is designed so that the coke forms in a drum. Numerous process rto models in romeotm within exxonmobil. In the training module on the delayed coker process, a typical coking process. Delayed coking variables there are three classes of variables affecting coking. Delayed coking is one of the unit processes used in many oil refineries. 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. Petroleum refining petroleum refining visbreaking, thermal cracking, and coking. Important recent trends and new developments have contributed to profitable, reliable, and safe operation of delayed cokers. Delayed coking process consists of furnaces, coke drums and a main fractionator. Coking service high cycle erosive conditions temperature cycling high pressure water service high pressure steam blowdown 1 recommend isolator 2. Delayed coking fundamentals pdf prepared by paul j. 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.
This cracks the heavy, long chain hydrocarbon molecules of the residual oil into coker gas oil and petroleum coke. In delayed coking, the temperature controls the quality of the coke produced. Pdf process flow determines coker heater performance. Maximize distilate yeilds hydrocracking altrernative. In the delayed coking process, many of these lateforming volatiles remain trapped in the coke. Delayed coking is one of the chemical engineering unit processes used in many petroleum refineries. Refining processes course curriculum, colorado school of mines, taught by.
Delayed coking was the first type of coker introduced in the refining market place. There are two types of coking processes, fluid cokers and delayed cokers. There are two kinds of coke produced by delayed coking of vdr. 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. 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. Refiners can process heavier, cheaper crudes to increase their. 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.
Temperature is used to control the severity of coking. Sep 17, 2017 the delayed coker unit animation describes the coking process in a step by step manner. Unique thermal cracking technology that solves some of the disadvantages of delayed coking. They are related to process operating variables, feedstock characterization and engineering variables as shown in table below. This presentation provides an overview of the delayed coking system found in.
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. The adjacent photograph depicts a delayed coking unit. The block diagrams of the systems were constructed and the process transfer. Refinery overhead plants management aims at saturating both coking units, by adapting other units downstream and upstream to reach this goal. Photograph of a 4drum delayed coking unit in a benica petroleum refinery in california. Coking is a refinery process that produces 19% of finished petroleum product exports source. 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. It is already known that the chemical and physical properties and composition of the feedstock and processing conditions affect coke morphology. Attend delayed coker operations and reliability training or delayed coking process, design and troubleshooting training courses. Delayed coking schemes are most economical for heavyoil upgrading. Process description gela refinery mostly treats heavy crude and residual products.
The product yields, consisting of light ends, naphtha, distillates, heavy coker gas oil hcgo, the byproduct coke are dependant on the feedstock and qualities. Petroleum refining visbreaking, thermal cracking, and coking. Uniform tube metal temperature resulting from a change in process flow enhances the run length of a delayed coker heater. The porousity gives it a high surface area, which makes it burn faster as does a sheet of paper versus a wooden log. The reactions continue as the process stream moves to. Delayed coking process design, operations and optimization may 2012. A delayed coker is a type of coker whose process consists of heating a residual oil feed to its. 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. Delayed coking schemes are most economical for heavyoil.
The process involves adding small amounts of cracking catalyst and hydrogen to the hydrocarbon feedstock before it is charged to the coking drum. The cracking and coking reactions are initiated in the fired heater under controlled timetemperaturepressure conditions. This is achieved by holding them at an elevated temperature usually 750 k765 k over a period of time 12 to 36 h. In delayed coking, the feed material is typically the. The inherent flexibility of the delayed coking process to handle different feedstocks promises the refiner a solution to the problem of decreasing residual fuel. In the training module on the delayed coker process, a typical coking process and decoking cycle operation. Delayed coking process1 cracking chemistry oil refinery.
Oct 31, 2017 fouling, coking or simply sticking is a costly surface problem that occurs in most industrial applications. Paul of great lakes carbon corporation of port arthur, tx. Cracking begins in the furnace, continues in the transfer line, and finishes in the coke drum. 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. 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. High velocities are maintained in the heaters in order to prevent significant coke formation. Surface fouling causes contamination, promotes corrosion, reduces flow, increases maintenance, and ultimately inflates costs while worsening performance. 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. Support facilities include closed blowdown, coke cutting and handling, and a water recovery system. 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. However, larger units have tandem pairs of drums, some with as many as 8 dr. Petroleum downstream crash course 17 delayed coking. Furthermore, implementing advanced process control apc on a delayed cooker is difficult.
Hazards of delayed coker unit dcu operations august 2003. Cracking and coking reactions are initiated in the furnaces under controlled timetemperaturepressure conditions. This option can be utilized in improving the run length of coker heater. 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 coker free download as powerpoint presentation. Pdf advanced control of the delayed coking unit in. The preheated feed is flown into the bottom of the reactor, an isolated.
Impact of feed properties and operating parameters on. The adjacent photograph depicts a delayed coking unit with 4 drums. The delayed coker unit animation describes the coking process in a step by step manner. The feed to coker is usually vacuum residue which is high on asphaltenes, resins, aromatics. 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. In its simplest terms, delayed coking is a semibatch thermal cracking process using alternating drums that are switched offline after filling. All of the heat necessary for coking is provided in the heater, whereas coking takes place in the coke drum. Pdf advanced control of the delayed coking unit in khartoum. 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. Fccs, hydroprocessing, crude units, and others typical rtos are applied to continuous processes that operate at steadystate. 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.
Consultant expert witness lng liquefied natural gas. As the supply of lighter crude oils has diminished, refiners. 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. Therefore, there are at least two coke drums in every delayed coking unit, and some units have more than two drums. 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. 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. 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. Delayed coking process design, operations and optimization. The delayed coking process is a thermal process and consists of fired heaters, coke drums and a main fractionator. 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. The process flow in all cases involves a crude unit including desalting followed by atmospheric and vacuum distillation. Reproduced with permission from valero energy corporation.
Two diagrams are essential in this effort, figure 1, the process flow diagram pfd, and figure 2, coke drum schematic. Since world war ii the demand for light products e. Another way to illustrate the basic coke drum operation will be employed in this section, the pressuretemperature profile for one complete cycle. Delayedcoking process update acs symposium series acs. Coking 101 an introduction to delayed coking prepared by. Short contact time thermal conversion process rapid thermal processing that operates at moderate temperature and atmospheric pressure. 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. High velocities are maintained in the furnaces in order to prevent significant coke formation. Delayed coking process animation dcu unit operation. This process produces a solid coke which has a high carbon content. The catalyst settles out in the coke and does not affect the utility of the coke. Unit ontime capacity has been increased, contributing to the units cash flow. Process description each dcu module contains a fired heater, two in some cases three coking drums, and a fractionation tower.
Delayed coking process animation dcu unit operation duration. 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. Delayed cooking is one of the most difficult refinery units to operate and control. This cracks the long chain heavy carbon and hydrogen molecules of the residual oil into coker gas oil and pet coke. Coking is a refinery process that produces 19% of finished. Delayed coking article about delayed coking by the free. Pdf delayed coking units convert heavy crude oil or topping refinery residue to. In order to maximize coking production and related light distillates it is equipped with two delayed coking units. Bitumen silt which is a result the oil recovery process. 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. 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. Current situation of emerging technologies for upgrading. Delayed coking is the technology most used to upgrade vacuum residue into highvalue products, but in this process, secondary reactions produce coke.
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. Lecture 4 thermal cracking, visbreaking and delayed coking. Hazards of delayed coker unit dcu operations august. Coking is the primary process used to upgrade petroleum residues.
Coking 101 an introduction to delayed coking 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 process yields higher value liquid products and creates a solid carbonaceous residue called coke. 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. Delayed coking produces 19% of finished product exports according to eia. Delayed coking fundamentals colorado school of mines. The total fresh and recycled feed is then heated implementing coker advanced process control. 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. 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. A significant number of recent projects have selected delayed coking due to the technologys ability to fully convert nondistillables.307 815 655 487 1130 1478 302 568 1557 777 1254 1318 363 173 1496 1008 731 1198 728 1018 75 304 430 819 337 278 317 981 1328 198 1215 1215