Catalytic Cracking Operation
The first problem is the coking of the lifting tube
The second problem is the catalyst runout
You all have any good tips, welcome to reply.
- By: fccu Friday, August 18, 2006 22:22 Reply (0) | Cite (0) Join the blog
troubleshooting FCC ...
/EngelhardKB/crep/TCR1_5.htm
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Article on Fluidization, Inclined Pipe
- By: fccu Tuesday, 18 July 2006 01:44 Reply (0) | Quote (0) Join the blog
Inclined Pipe Bridging
Inclined Pipe Bridging is more common, the phenomenon is slant pipe vibration, and a couple of other words, called trench flow, knuckle surge. It's pretty much the same thing, the fluidized state of the catalyst is disrupted. Instead of a uniform "emulsified" state, the gas phase is separated from the solid phase, which can affect the level or temperature control, and seriously damage the equipment.
Generally, small diameter inclined pipe is easier to bridge than large diameter
The inclined pipe with more bends is easier to bridge than straight inclined pipe
The catalyst with less fines is easier to bridge
Also, there is a lot to learn from the loosening point setting. It is generally accepted that as the altitude drops, the pressure rises and the volume of gas is compressed, it becomes easier to get out of the way.
- By: fccu Thursday, July 13, 2006 21:34 Reply (4) | Cite (0) Add to blog
Recommended forum
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Chemical forum, a lot of bull...
Thanks to Ade for the information
- By: fccu Thursday, July 6, 2006 06:13 Reply (0) | Cite (0) Add to blog
Lanzhou Petrochemical Co. Reporter Li Zhanji reported: Today at 3 p.m., Lanzhou Petrochemical Company held a press conference, the company's deputy director of safety Lu Jianguo on the fire accident occurred in the morning briefing.
The briefers said that on June 28, 8:05 am, the refinery 400,000 tons / year gas fractionation unit 507 heat exchanger head cover leakage (heat exchanger medium for the liquid hydrocarbons), triggering a fire. After the fire, Lanzhou Petrochemical Company Deputy Secretary of the Party Committee, Secretary of the Commission for Discipline Inspection, Chairman of the Labor Union, Li Zhenghua, and other members of the team immediately rushed to the location of the fire, promptly launched the emergency plan, and went all out to direct the fire-fighting and rescue work. Gansu Province Safety Production Supervision Administration Qi Yonggang, deputy director of the Gansu Provincial Environmental Protection Bureau Wang Xinzhong, deputy director of the Gansu Provincial Fire Brigade Tao Runren, deputy mayor of Lanzhou City Yao Guoqing and the relevant provincial and municipal authorities also rushed to the scene, the organization of the command of the rescue work.
The notifier said, the company fire brigade 8:06 minutes after receiving the fire report, 8:09 minutes rushed to the fire scene, and go all out to organize the fire extinguishing. Lanzhou City Fire Brigade and Xigu District Fire Brigade also rushed in time to support the fire extinguishing work, the fire was under control at 10:00 am. As liquid hydrocarbons at atmospheric pressure for liquefied gas, in order to prevent the open fire extinguished, liquefied gas diffusion, resulting in a secondary fire, is now using effective control measures to protect the combustion of liquid hydrocarbons remaining in the heat exchanger to burn net until.
The refinery promptly organized personnel to cut off the material at 8:15, reduce pressure relief, emergency organization device shutdown, close all the valves connected to the outside of the device, and cut off the power supply.
The notifier said that Lanzhou Petrochemical Company immediately started the environmental emergency plan, organized personnel to block the rainwater drainage system, closed all the discharges into the Yellow River, set up on-site cofferdams, introduced the accidental fire water into the refinery wastewater treatment plant for treatment, and activated the 30,000 cubic meter emergency regulating pool, so that the fire water was not discharged into the Yellow River. At the same time, to strengthen the atmosphere and water quality monitoring, sampling and analysis at regular intervals, by the environmental protection department monitoring, the atmosphere and the Yellow River water quality did not occur any pollution.
According to reports, in the firefighting and rescue process, involved in firefighting enterprise firefighters have 1 sacrifice; another 10 members were injured, including 6 severe burns, 4 moderate burns. Lanzhou Petrochemical General Hospital and the relevant experts in Lanzhou City, Gansu Province, has been to the hospital for treatment.
It is also reported that Lanzhou Petrochemical Company has set up a "6-28" fire accident leading group, under the scene of the rescue group, the accident investigation team, the comprehensive coordination group, the aftermath of the group, stabilize the production group, to carry out work in an orderly manner. At present, Lanzhou Petrochemical Company's main refining and chemical production units are running stably, and the mood of the workforce has remained stable.
Lanzhou Petrochemical Company said, in line with the staff responsible, responsible for the community attitude, seriously do a good job in the accident rescue, treatment of the injured, aftercare and accident investigation and analysis work.
The company has not yet allowed reporters to visit the scene.
- By: fccu Thursday, June 29, 2006 10:00 Reply (0) | Cite (0) Join the blog
steam desuperheater
Steam has to be superheated in order to be used. But there are places where too much superheating is not good, such as a reboiler that uses steam as a heat source. Because here the heat given off by the condensation process of the steam is mainly utilized, the sensible heat generated by the cooling of the gas phase is so small as to be negligible.
In this case, the steam temperature over the saturation temperature is too high, there is little benefit, but instead make the heat exchanger localized overheating, so to set up the desuperheater. In fact, it is very simple, it is the boiler feed water sprayed directly into the steam lines, using the back path temperature control of the amount of water sprayed.
One day when a plant started, found that the temperature difference of 3 to 5 degrees, is not down to the specified temperature, the regulator valve 100% full open also does not help. What's going on? I was instructed to find out the cause and solve the problem!
Look at the drawings, go to the site, ask the operator, the situation is this way, the temperature is already lower, I do not worry about what effect on the equipment, but how to switch the regulating valve, the temperature is not moving, always a problem.
I think, the temperature can not come down, there are two reasons, one is not enough cooling medium, that means the amount of water is not enough, there is a problem with the water system. The other reason is that the system steam is too hot. The system temperature is really high, but after the temperature measurement point, there are two other steam from the steam bag directly into the system, and the amount is not known.
Doing two heat balance calculations: 1, assuming the steam temperature is normal, calculating how much water was sprayed 。。。。 The result was very little, less than 10% of full scale
2. Assuming a normal amount of water, calculate the temperature of the steam entering the system. The result was very high, about 600 degrees, which obviously doesn't make sense.
My conclusion was that the water injection system was clogged and to open this system for cleaning. The report was given to the leader and I left work.
The next day at work, the leader told me that the reason found: the system steam with water, is already saturated steam, the boiler feed water sprayed in, there is no phase change, very little effect on the temperature, thermocouples simply can not detect the temperature change. What an accident!
- Author: fccu Thursday, June 29, 2006 09:48 Reply (0) | Cite (0) Join the blog
Wing valve grinding through
A plant reactor spinning points to grind a large hole out. Call.
The first feeling is that the catalyst system, wear and tear is a common thing, replace it with a good one....
But by all rights then, there should be material seals inside the legs, which is why the wing valve is set up, the flow should be slow, or open and close all at once.
Is there a problem with the installation? Wing valves have strict angle requirements, and each one should have been tested to determine the installation angle to ensure that it will open at a certain pressure, or it should seal. If it's installed crooked, and the wing valve keeps opening a crack, and the catalyst continues to flush, maybe it does.
But all of it flushed the hole out, there is a problem. And if this problem is not solved, the catalyst comes out of the hole, the valve plate is inactive, and as it cokes over time, the valve plate becomes even more inactive. In case there is an operational fluctuation, the spinning fractionation leg is not unloading well, and the catalyst will definitely run into the fractionation column.
Discussed half a day, the other side thinks that the material leg is too thick, the wing valve is open, hollister france, all flowed out. In fact, the thickness is not a problem, as long as the valve plate is sealed, maybe the valve plate is not so high sensitivity. Maybe over time, the rod that hangs the wing valve is too smooth---it opens accidentally, or too rough---it opens and closes.
The reasons are largely the same, and the conclusion is that it would be better to replace the wing valve with a counterbalance hammer type and do away with this doorstop design. That type of wing valve plate is mounted horizontally, wear-resistant lining, it is not easy to wear out.
- By: fccu Thursday, June 1, 2006 17:24 Reply (0) | Cite (0) Join the blog
MGD and MIP
mgd - maximize gas and diesel fuel, and its technology is characterized by: light and heavy feedstock oil fenzeng feed, gasoline back to refining.
The purpose of mgd is to convert gasoline into liquefied petroleum gas (LPG) and diesel fuel through gasoline refining. This technology was more popular in southern China in the late 1990s, when there was a surplus of gasoline and the price of LPG was high, and it could also increase the diesel to gasoline ratio. The technology is related to the season and the market.
mip - maximizing isoparaffins, the technology is characterized by a recirculating ramped pipe that circulates the catalyst to be generated from the stripping section back to the top of the lift pipe, creating a "second reaction zone".
The background of mip is that in the first few years, gasoline specifications called for 35% olefin content, and at that time, the main unit for gasoline production in refineries was the fcc, with very few blending components and means of blending. In the reaction zone, at low temperatures and long reaction times, isomerization reactions are favored, resulting in a lower olefin content in the product gasoline. Of course, there is a corresponding change in the catalyst.
This is my understanding. It should be based on the official information of the Institute of Petroleum. But as you can see, the development of technology is driven by the market and environmental regulations. With the construction of a large number of reformers, it should not be a problem to reach 18% olefin content in product gasoline. But accordingly, the aromatic content of reformed gasoline will become more and more of a concern.
Perhaps isomerization and alkylation units will be developed.
- By: fccu Monday, May 15, 2006 15:40 Reply (7) | Cite (0) Add to Blog
Petroleum Refining Process - Catalytic Cracking
One of the petroleum refining processes is the process of cracking heavy oils into cracked gasoline, gasoline, and diesel fuel by the action of heat and catalysts. It is the process of transforming heavy oil into cracked gas, gasoline and diesel fuel under the action of heat and catalyst. Raw materials used in the distillation of crude oil (or other petroleum refining process) from the heavy distillate; or heavy distillate mixed with a small amount of residual oil, solvent deasphalting after deasphalting residual oil; or all of the atmospheric residual oil or decompression residual oil. During the reaction process due to the deposition of non-volatile carbon-like substances on the catalyst, which condense to coke, the catalyst activity decreases and needs to be burned away with air (see catalyst regeneration) to restore catalytic activity and provide the heat required for the cracking reaction. Catalytic cracking is one of the main processes used in petroleum refineries to produce gasoline from heavy oil. The gasoline produced has a high octane number (around 80 in the motor method), good stability, and the cracked gas (a type of refinery gas) contains a lot of propylene, butene, and isomerized hydrocarbons.
History Catalytic cracking technology was successfully researched by E.J. Hoadley of France and industrialized in 1936 by the U.S. Socony Vacuum Oil Company in cooperation with Sun Oil Company, which at that time used a fixed-bed reactor, alternating between counter-celebration and catalyst regeneration. Due to the need for higher octane gasoline for gasoline engines with high compression ratios, FCC has been developed in the direction of both moving bed (reaction and catalyst regeneration are carried out in a moving bed reactor) and fluidized bed (reaction and catalyst regeneration are carried out in a fluidized bed reactor). Moving bed catalytic cracking was gradually eliminated due to the complexity of the equipment; fluidized bed catalytic cracking, with its simpler equipment, larger processing capacity and easier operation, has been greatly developed. in the 1960s, molecular sieve catalysts appeared, and due to its high activity, the cracking reaction was changed to be carried out in a tubular reactor (elevated-tube reactor), which is called elevated-tube catalytic cracking.
China built a moving bed catalytic cracking unit in Lanzhou in 1958, a fluidized bed catalytic cracking unit in Fushun in 1965, and a lift-tube catalytic cracking unit in Yumen in 1974. in 1984, China's catalytic cracking units***39 sets, accounting for 23% of crude oil processing capacity.
Catalyst The main component of the catalyst is aluminum silicate, and the catalytic role is played by the acidic active center (see solid acid catalyst). Moving bed catalytic cracking uses small spherical catalysts of 3 to 5 mm. In the early stage of fluidized bed catalytic cracking, powder catalysts were used, which had poor activity, stability and fluidization performance; since the 1940s, microspherical (40-80 μm) silica-aluminum catalysts have been developed, and the preparation process has been improved to make the catalysts more active, and the X-type molecular sieve silica-aluminum microsphere catalysts, which are high in activity and contain rare-earth elements, were developed at the beginning of the 1990s; and since the 1970s, Y-type molecular sieve microsphere catalysts (see Solid Acid Catalysts), which are even more active, have been developed. type molecular sieve microsphere catalysts (see Petroleum Refining Catalysts).
Chemical Reactions Unlike thermal cracking, which is carried out by a free radical reaction mechanism, catalytic cracking is carried out by a carbon-positive ion mechanism. The catalyst promotes cracking, isomerization and aromatization reactions, and the cracked products have higher economic value than thermal cracking, with more C3 and C4 in the gases and more isomers, more isomerized hydrocarbons in the gasoline, very little diolefins, and more aromatics. The main reactions include: ① decomposition, so that heavy hydrocarbons into light hydrocarbons; ② isomerization; ③ hydrogen transfer; ④ arylation; ⑤ condensation, coking reaction. Isomerization and aromatization convert low-octane straight-chain hydrocarbons into high-octane isomerized hydrocarbons and aromatics.
Process The catalytic cracking process consists of three parts: (1) catalytic cracking of feedstock oil; (2) catalyst regeneration; and (3) product separation. After heat exchange, the feedstock is mixed with refinery oil and sprayed into the lower part of the lift tube reactor, where it is mixed with high-temperature catalyst, gasified and reacted. The reaction temperature is 480~530℃ and the pressure is 0.14MPa (gauge pressure). The reacted oil and gas are separated from the catalyst in the settler and cyclone separator (referred to as cyclone separator), and then enter into the fractionation tower to separate gasoline, diesel fuel and heavy oil back to refining oil. The cracked gas is compressed and goes to the gas separation system. Coking catalyst in the regenerator with air to burn off coke after recycling, regeneration temperature of 600 ~ 730 ℃.
When using molecular sieve catalysts, in order to allow flexibility in the refinery's product program, the operating conditions can be changed according to market needs to obtain the maximum amount of gasoline, diesel or liquefied petroleum gas.
Types of Units There are various types of fluidized bed catalytic cracking units (FBCUs), which can be classified into two main types according to the relative positions of the reactor (or settler) and regenerator arrangement: (i) side-by-side type where the reactor and regenerator are arranged separately; and (ii) coaxial type where the reactor and regenerator are stacked on top of each other. Juxtaposition and due to the reactor (or settler) and regenerator position of the different heights and is divided into the same high parallel type and high and low juxtaposition of two types.
The main features are: ① catalyst transported by the U-tube dense phase; ② catalyst cycle between the reactor and regenerator mainly by changing the density of catalyst at both ends of the U-tube to regulate; ③ catalyst transported by the reactor to the regenerator, do not pass through the regenerator distribution plate, directly from the dense phase lifting tube into the distribution plate on the fluidized bed can reduce the distribution of the plate abrasion.
High and low parallel type Characterized by short reaction time, reducing the secondary reaction; catalyst cycle using slide valve control, more flexible.
Coaxial device form is characterized by: ① catalyst delivery between the reactor and regenerator using plug valve control; ② vertical lifting pipe and 90 ° wear-resistant elbow; ③ raw materials with multiple nozzles into the lifting pipe.
Development For a long time, fluidized bed catalytic cracking (FBC) feedstocks are mainly distillate from crude oil (diesel oil, decompression distillate, etc.) and thermal processed distillate, and the content of nickel and vanadium in the feedstocks (which can poison the catalyst) is generally less than 0.5 ppm. When using decompression residue as the feedstocks for FBC, the feedstocks are usually pretreated with various methods to remove most nickel, vanadium, and other metals before they are fed into the catalytic cracking unit. Since the 1970s, the demand for commercial residual oil has declined due to the conservation of petroleum resources. Therefore, it has become quite common for fluidized bed catalytic cracking units to blend reduced-pressure residue oil or directly process atmospheric residue oil. The main measures are: the use of anti-heavy metal poisoning catalysts; the addition of passivators to the feedstock, etc.
Source: Ocean Power Chemical Forum
- Author: fccu Tuesday, April 11, 2006 08:09 Reply (0) | Cite (0) Add to Bocai
New process of benzene separation from reformulated gasoline pumping and distillation
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2004-3-11 Views: 65
Recovery of pure benzene from catalytically reformed gasoline is not only a significant economic benefit, but also a need for the production of clean fuels. The Institute of Petrochemical Sciences has developed a new process of recovering pure benzene from catalytically reformed gasoline by extractive distillation of cyclobutanesulfone-COS composite solvent (SED), which has a very good separation effect.
The SED process consists of pre-fractionation, extraction distillation, solvent recovery, solvent regeneration, and product post-treatment units. De-pentane oil feed from the reformer enters the pre-fractionation tower after heat exchange, and gets C6 fraction at the top of the tower after ordinary distillation, and benzene-free high-octane gasoline components at the bottom of the tower. C6 fraction is used as the feed for extractive distillation, and enters the middle of the extractive distillation tower (ED tower) after preheating, and the circulating solvent enters from the top of the tower, and gets non-aromatic hydrocarbons at the top of the tower and rich solvents containing high-purity benzene at the bottom of the tower after extractive distillation. The rich solvent enters the solvent recovery tower (RC tower). The tower is operated under hydraulic pressure, benzene is extracted from the top of the tower, and the poor solvent at the bottom of the tower is recycled after heat exchange. A small portion of the poor solvent enters the solvent regeneration tank for regeneration under reduced pressure to keep the system solvent clean. The residual oil (non-aromatic product) from the ED tower can be used as naphtha or directly adjusted back to gasoline, or it can be hydrogenated to produce No. 6 solvent oil after residual oil extraction. Benzene from the top of the RC tower then enters the white earth tower to remove trace olefins, and qualified benzene products are produced at the bottom of the tower.
Co-solvent (COS) in addition to the role of stabilizing the operation, but also reduce the recovery tower bottom of the thermal intensity of the sulfone ring, reduce solvent decomposition and improve the role of stupid yield. Recovery tower operating at atmospheric pressure, in order to maintain the purity of benzene is not less than 99.95% of the conditions, with the increase in the content of co-solvents, the recovery of the bottom of the tower can be appropriately lowered operating temperatures, and benzene recovery rate increased gradually, especially co-solvents content increased from 5% to 19%, the benzene recovery rate increased rapidly from 91.2% to 99.5%, which fully demonstrates the role of the co-solvent to improve the recovery rate. Industrial recovery tower can be operated under reduced pressure, the content of co-solvent can be reduced, the appropriate content of 10% to 18%.
From the point of view of construction investment, the use of SED process than the cyclobutanesulfone-liquid extraction process tower system to reduce the number of 5, the total number of equipment to reduce the number of 17 or 19, saving construction investment of about 20 million yuan. From the consumption index, SED process and single-solvent extraction distillation process is comparable, compared with the cyclobutanesulfone liquid-liquid extraction process energy consumption and material consumption is significantly reduced, especially steam consumption is reduced by 25%, which can significantly reduce operating costs. From the point of view of product quality yield, the product quality of benzene of the three processes can meet the standard of superior products, but the benzene yield of single-solvent extraction and distillation process is very low, while the SED process and liquid-liquid extraction process have high product yield, which can reach more than 99.5%. In summary, compared with the existing process, the SED process has low investment, low energy consumption and high benzene product yield, which is an ideal process for debenzolization of reformed gasoline.
The new process was first industrially applied in the 150,000t/year reformed gasoline extraction distillation separation of benzene project at Dalian Petrochemical Plant, with an investment of 29.43 million yuan in the project construction. The device was fully calibrated and assessed, and the results showed that: benzene purity of 99.95%, crystallization point higher than 5.40 ℃, benzene yield of more than 99.15%. Steam consumption is expected to be reduced by 31%. By the end of September of the same year *** processing raw materials 87,000t, *** creating economic benefits of 2.721 million yuan. If the design load is calculated, the annual economic benefits can be created 10.471 million yuan.
The benzene recovery process by extractive distillation of reformed gasoline is an ideal technology for the production of benzene products and benzene-free clean gasoline by debenzolization of reformed gasoline.