In the early morning of April 24, the Qilu Petrochemical Victory Refinery was suddenly full of fire, reflecting half of the sky.
Source: Hydrogen Sink
Subsequently, Sinopec Qilu Petrochemical issued a brief fact sheet: the hydrogen in the compressor area of the continuous reforming workshop in the Shengli refinery in Linzi District, Zibo, Shandong Province, was leaked and caught fire at 0:02, and the hydrogen process was removed at 0:20 after 18 minutes, and the open flame was extinguished at 1:20 an hour later, fortunately there were no casualties.
The beginning of the year
On January 6, 2022, Yu Zishuo, who had only been newly hired in the Qilu Petrochemical Shengli Refinery for half a year, was commended by the senior leaders of Qilu Petrochemical Company and successfully avoided an accident. Because on the morning of December 30, 2021, Yu Zishuo was inspecting the equipment, and suddenly the hydrogen sulfide alarm instrument he carried with him sounded an alarm, and then a rotten egg smell struck, he quickly evacuated the scene and reported to the squad leader at the first time. Then, according to the procedure, it was returned to the leakage point for operation, avoiding personnel poisoning or fire and explosion accidents.
Yu Zishuo received the commendation order (Source: China News Network)
In the external publicity, Qilu Petrochemical also emphasized that the good news of "operating profit of more than 5 billion yuan to the best level in history" can not be separated from the safety management management behind it, strict words are the first, fine words are the ballast stone for Qilu Petrochemical to run out of the benefit "acceleration", and emphasize that "the safe and stable operation of the device is the biggest benefit of the enterprise".
(Source: China News Network)
But even with this emphasis on safety, accidents have occurred. We may wish to take a closer look at the continuous reforming and hydrocracking device of the incident. But the child has no mother, it is a long story. You need patience to read it.
Construction history
From its establishment in 1966 to 1996, qilu Petrochemical Shengli Refinery has been processing Shengli crude oil and isolated island crude oil, which is basically a "fuel-based" refinery. With the completion and commissioning of the Qilu 300kt/a ethylene project in 1987, in order to provide cracking raw materials for ethylene production, Shengli Refinery gradually evolved into a "fuel-chemical" refinery. In order to improve the yield of light oil and provide more high-quality cracking raw materials for ethylene production, since 1996, it has successively purchased light crude oil such as the Middle East for blending. However, due to the small amount of imported crude oil, it is far from solving the contradiction between improving the yield of light oil in the whole plant and satisfying the high-quality cracking materials for ethylene projects.
On October 30, 1997, the feasibility study report of the oil refining and expansion project of Shengli Refinery of Qilu Petrochemical Company was evaluated and approved by the China International Engineering Consulting Corporation commissioned by the State Planning Commission and submitted to the State Planning Commission, which marked the completion of the preparatory work for the refining and expansion project of Qilu Petrochemical Company. The refinery renovation and expansion project is one of the four major renovation projects (refining, ethylene, fertilizer and caustic soda) of Qilu Petrochemical Company during the "Ninth Five-Year Plan" period, and the investment in the feasibility report is estimated at nearly 3.6 billion yuan. The estimated budget for the follow-up project is 3.172 billion yuan, and the project covers an area of 125,800 square meters.
The renovation and expansion projects include: "two constructions, five reforms and one supporting facility", that is, the construction of a new 600,000 tons / year continuous reforming device, 1.4 million tons / year hydrocracking unit, the reconstruction and expansion of VRDS device, No. 3 atmospheric vacuum distillation unit, No. 2 sulfur recovery device, No. 1 hydrogen production device, No. 2 hydrogen refining device, oil storage and transportation, public system and other supporting projects. The actual investment of the renovation and expansion project was 3 billion yuan, which took nearly 4 years to complete. According to the requirements of "less input, high output, timely input and rapid output" of Sinopec Corporation, the reconstruction and expansion project is divided into three stages:
(1) From July 1997 to October 1998, the No. 3 atmospheric pressure reduction device and the three 50,000 cubic meters of crude oil tanks in the west of the imported crude oil tank area, the storage and transportation of some oil products, the loading and transformation of the vehicle and the supporting work of the system were completed, with the transformation of the No. 3 atmospheric pressure reduction distillation device as the core;
(2) From November 1998 to December 1999, complete the VRDS device, the No. 1 hydrogen production unit, the No. 2 hydrogen refueling device, the three 50,000 cubic meters of crude oil tanks in the east of the imported crude oil tank area, the No. 2 torch 10,000 cubic meter gas cabinet, and the supporting projects of the water supply and drainage system and the railway transportation system in the north area;
(3) From March 1998 to November 2000, the dismantling and construction of the No. 2 sulfur unit was completed, and the new continuous reforming - hydrocracking joint device and its system supporting pipeline, medium pressure steam pipeline, No. 2 torch facility, nitrogen supply facility, reforming and hydrogenation raw material tank farm and other tank areas were reconstructed and expanded, as well as the transformation of circulating water and purified water treatment facilities, mainly with the newly built continuous reforming and hydrocracking unit as the center, which realized the intermediate handover of the project on November 23, 2000. Qualified products were produced at 7 o'clock on March 5, 2001.
Continuous reforming device
Using the French IFP second-generation ultra-low pressure continuous reforming technology, only the right to purchase patents, the Petrochemical Research Institute provides basic data, the Beijing Design Institute of Sinopec Group carries out the basic design and detailed engineering design of the process package, and the domestic project construction is carried out by itself. The continuous regeneration of the catalyst adopts a local equipment, and the control part of the regeneration system is improved on the basis of the digestion and absorption introduction device.
Through three processes: feedstock pretreatment, reforming reaction and continuous regeneration of catalysts, low-octane naphtha is turned into a high-octane gasoline component rich in aromatics. The raw materials used in the plant are various hydro-naphtha distillates and Middle Eastern crude oil direct distilled naphtha. The products are high octane unleaded gasoline components, hydrogen and C6+ components. Some of the C6+ components are extracted by the reforming device to produce light and heavy finishing liquids, which are supplied to the olefin plant as chemical raw materials.
Process flow diagram of the continuous reforming unit
Hydrocracking unit
After repeated comparison and selection, the 3936-3824 two-stage series of 3936-3824 developed by Fushun Petrochemical Research Institute was selected to pass the hydrocracking process technology and catalyst (the catalyst configuration scheme was changed to 3936 and ZHC-01 after the catalyst configuration scheme), and the hydrogen purification adopted the pressure swing adsorption (PSA) process developed by Chengdu Huaxi.
The raw materials are Sha Light, Sha Zhong, Kuwait VGO (the ratio of the three is 46:8:46) and tar wax oil, and the hydrogen used is hydrogen with a purity of 99.9% after being purified by pressure swing adsorption (PSA). The main products are liquefied gas, naphtha, jet coal, diesel and tail oil. Among them, aviation coal is a high-quality jet fuel, and the tail oil is supplied to Qilu 450kt/a ethylene project as a high-quality cracking raw material to prolong the operation cycle of the cracking furnace and increase the company's economic benefits.
After the accident, Shengli Refinery stopped the continuous reforming device and the hydrocracking unit urgently, and cut off the hydrogen process, although it was removed, but the hydrogen remaining in the pipe system adopted protective combustion measures. As for which part of the hydrogen leak occurred, which triggered the flash explosion and fire, further investigation and analysis are needed.
Source: Hydrogen Sink
But safety is no small matter, even if you usually pay attention to it, there may still be hidden dangers, so the safety work should still be done in detail and then done in detail, after all, "there is no safety, everything is zero"
Night view of Qilu Petrochemical Shengli Refinery (Author: Liu Yuping)