Thread Content
Status of the dry quenching project for Coking Oven No. 1 at X Steel’s coking plant. The dry quenching project for X Steel, carried out by XXX Group Company, was initiated in 1997; after several years of effort, it was put into trial operation on January 19, 2001. The relevant information is hereby provided to all parties; the details are as follows: 1) The heat recovered from red coke. In 2001, 221,924 tons of medium-pressure steam were produced per year. Based on the performance tests conducted in 2001 by X Steel Corporation and Nippon Steel Corporation on their dry quenching system, it was found that for every ton of coke dried in this way, 1,356,800 units of heat can be recovered (yielding 560–590 kilograms of medium-pressure steam with a superheating temperature of around 450°C and a steam pressure of 3.89 MPa). This allows for the recovery of 92.1% of the heat contained in the red coke. 2) Improve coke quality. During dry quenching, the red coke is not rapidly cooled by cold water, which prevents cracks from forming and damaging its structure. Moreover, within the dry quenching apparatus, the coke undergoes a process of \"slow cooling,\" which improves its maturity; as a result, the quality of the coke becomes more uniform and stable, along with higher mechanical strength. Comparing the quality of dry quenching and wet quenching in Shougang’s coking plant, it can be seen that the crush resistance strength increases by 6.1% for M40 grade, and by 1.0% for M10 grade; meanwhile, the moisture content decreases by 4.2% ； The volatile matter content decreased slightly (by 0.12%), which is mainly due to the ‘smothered combustion’ of coke in the dry quenching pre-storage chamber. 3) Starting at 17:00 on May 17, 2001, the demineralized water flow rate was increased from 29 t/h to 35 t/h to conduct a water volume test. At the same time, a coking workshop will adjust the coke pushing plan according to the planned scheme in order to achieve more uniform coke output. Starting from May 21, the number of dry quenching coke ovens in use per day increased from around 45 to around 57, while the dry quenching rate rose from 75% to 95%, an increase of 20%. 4) The weld at the upper part of the rotary seal valve cracked on average 1–2 times per week. From 13:00 to 15:40 on July 4, 2001, the discharge system was shut down, and a lining plate measuring 1320*300*30 mm was welded to the inner north side of the upper interface of the rotary seal valve used for dry quenching of coke, thereby completely resolving the problem of coke dust leakage in that area. 5) In mid-September 2001, a comparison test on coke quality was conducted in collaboration with the Research Institute to adjust the technical parameters of dry quenching of coke (coke discharge rates of 3 t/h, 50 t/h, and 7000 Nm3/h). 6) Starting from October 9, 2001, two units of dual-media filters and fine sand filters were put into operation in the demineralized water system (the spare equipment was removed), with the aim of preventing bacterial contamination of the demineralized water system caused by the spare equipment during its standby period. After changing the operation mode of the equipment, the safety filter operated stably, and the pressure difference between the fine sand filter and the safety filter remained essentially unchanged. 7) Annual maintenance of the dry quenching system was carried out from November 9 to 24, 2001. From November 9th to 12th, it was a period for maintenance; warm air drying began on the 19th. The furnace was put into use for baking red coke at 17:40 on the 21st, and normal production was resumed on the 24th. During its shutdown for maintenance, the main inspection, cleaning, and repair tasks carried out were as follows: ① On November 13, a comprehensive inspection of the dry quench tank and the 1DC masonry was conducted. Inspections revealed that one brick was broken in half in the third layer from the bottom between the 13th and 14th circulation holes of the dry quench tank, and two bricks each were bulging due to changes in furnace temperature below the outlet of the dry quench tank and the inlet of the boiler thermal expander; these issues were resolved by thermal maintenance personnel on November 16. ②Dust accumulation was found in certain areas of the gas circulation system, and relevant personnel were organized to clean it up. The specific details are as follows: a: There is approximately 3.54 m3 of dust accumulated at the entry points beneath the south and north 2DCs. b: 10 m3 of dust has accumulated in the hopper below the electromagnetic vibration feeder. c: 11.5 m3 of dust accumulated at the boiler inlet, at the outlet of the dry quench tank. ③An additional manhole is installed at the highest point on the western side of the dry quench tank and the environmental dust removal fan pipeline system to facilitate inspection and removal of dust accumulated in the pipes. This time, 0.5 m3 of dust was removed. ④The maintenance staff carried out inspections on the dry quenching system for coke, as well as equipment such as traction systems, coke tanks, cranes, and environmental dust removal systems; all individual tests and combined tests were completed successfully. ⑤The demineralized water station is undergoing cleaning and renovation of its water treatment system. 8) Dry quenching of coke eliminates the pollution in the primary forging plant area caused by large amounts of smoke and dust, as well as harmful gases containing numerous organic compounds that occur during wet quenching. According to tests conducted by the Beijing Environmental Monitoring Center, the dust emission concentration was 9.6 mg/m3, meeting the requirements specified in the **Comprehensive Emission Standards for Air Pollutants**. The amount of dust captured each year is 9,490 tons; the collected coke dust is humidified and then transported away to be used as raw material for sintering. IV. Experiences and lessons from the implementation process 1. The Japanese side is relatively standardized in its approach, which is worth learning from. In all aspects such as the signing of the basic and technical agreements, the management of design drawings, design consultations between China and Japan, construction guidance, commissioning of the project, and guidance during the trial production period, there are detailed management documents and technical materials that provide strong guidance for the project. Although China’s design firms, construction companies, and manufacturing plants possess rich practical experience, they lack systematic written summaries and continuous technical documentation, which hinders the improvement of their overall capabilities. 2. Large Japanese companies such as Yokogawa and Yaskawa have their own training centers, where training is provided on the use of the equipment they produce, in order to ensure that the equipment operates safely and stably during production. 3. There are differences between China and Japan regarding construction specifications and implementation standards. This led to conflicts between the two parties during the construction process. To avoid such conflicts, it should be emphasized at the time of signing the basic agreement that foreign equipment brought to China must comply with China’s installation and construction specifications as well as mandatory standards (such as the acceptance criteria for boilers). 4. The implementation of green aid program projects needs to be further standardized. At the inception of this project, China and Japan formed a research team; Japan provided special funding, while China’s participation came from the **Science and Technology Commission, the former Ministry of Metallurgy, Tsinghua University, and Shougang. As originally planned, a series of outcome studies should be conducted after the project goes into operation, but no work plan from the Japanese side has been seen so far. Please ask the relevant departments to take action and supervise this matter. The quality of the research work on this topic is directly related to the widespread adoption of the project. For another example: half a year after the project goes into operation, a \"Green Safety Helmet\" campaign will be carried out. Our side will send personnel to Nippon Steel in Japan for hands-on training, in order to further improve the skills of the staff, create favorable conditions for the normal operation of the coke dry quenching process, and address some of the issues that arise during production. The Japanese side will also send people to Shougang to provide technical guidance and help resolve problems that arise in production. Nippon Steel and Shougang had previously studied this matter in detail during the first half of 2001; Shougang approved the project, but there has been no further news from the Japanese side. V. Ideas for the promotion and dissemination of the project: When implementing its green assistance projects, X Steel has attached great importance to the issue of promotion and dissemination from the very beginning. It requires that clear goals be set for each stage, including design, manufacturing, construction, production, and maintenance. During the implementation of the projects, it strives to learn from, absorb, and apply Japanese technology, while finding its own approach based on China’s national conditions. To this end, all units of Shougang worked together closely to successfully complete the project tasks. 1. In terms of design: X Steel Design Institute was fully involved in this project from the outset of the negotiations, and conducted numerous field inspections to gather information. [This post was last edited by gxh60 on 2009-3-17 at 22:50]