The most popular situation that China's major tech

2022-07-31
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The long-term dependence on import of major technical equipment of mechanical engineering in China has been puzzling the industry. According to statistics, in 2003, the import and export of mechanical products reached US $39.239.5 billion, and the total import volume increased by 50.91% year-on-year. China Machinery Industry Federation major equipment project office the current situation that China's major technical equipment for mechanical engineering has been relying on imports for a long time has plagued the industry. According to statistics, in 2003, the import and export of mechanical products reached US $39.239.5 billion, and the total import volume increased by 50.91% year-on-year. Major equipment project office of China Machinery Industry Federation introduction to China Construction Machinery Information: in the past 2003, the Three Gorges project has successively realized water storage, navigation and the production and power transmission of six sets of hydro generators. In the first year of this year, it is under intense construction. Why should the Three Gorges Project continue for fiveorsix years? It will cost US $60 billion to complete the project in 2009? Also some people don't understand: the follow-up project still needs to be done

in the past 2003, the Three Gorges project has successively realized water storage, navigation and the commissioning and power transmission of six sets of hydro generators. In the first year of this year, it is under intense construction. Why should the Three Gorges Project continue for fiveorsix years? It will cost US $60 billion to complete the project in 2009? Some people also wondered: what else should the follow-up project do, and what other arduous projects should the builders of the Three Gorges overcome? At the Three Gorges construction site, we are looking for answers for the vast number of caregivers and interrogators

the width of the dam gap is 35mm, one third of the gap. In 2006, it can continue to be the Three Gorges Dam with the "dragon"

axis located in Sandouping, Yichang City, with a total length of 2309m. Because the design scheme determines that the Three Gorges project must be divided into three phases for construction diversion, the main project is divided into three phases for sectional construction. At the end of the second phase of the project, the completed length of the Three Gorges Dam will be 1586 meters, about two-thirds of the total dam length. In other words, the dam has not been cast on the riverbed of the original diversion channel, and there is a gap about one third of the dam length. The reason why the initial water storage in front of the dam was carried out in June, 2003 (so that the Three Gorges power station can bring benefits into play as soon as possible) is that the RCC cofferdam, a rolled temporary water retaining structure, and the dam on the left bank are "hand in hand side by side", and the gap of 600 to 700 meters was filled with "body", so that the initial water storage of 139 meters, navigation and power generation were realized in 2003

according to the construction scheme of "open channel navigation and phase III diversion" approved by the Three Gorges Project Construction Committee of the State Council, 2004-2009 is the phase III construction stage of the Three Gorges Project. At this time, the main buildings to be completed in the construction stage are mainly the dam on the right bank and the power station on the right bank. The mechanical and electrical equipment installation project is mainly carried out around the 12 water turbine generator units of the power station on the right bank and the world's largest vertical ship lift at the corner of the left bank

4.31 million cubic meters of concrete shall be poured for the dam on the right bank. According to the annual construction plan, nearly half of the total pouring amount will be completed in 2004, about more than 2million cubic meters. By the end of 2006, the whole dam will be poured to the dam crest elevation of 185m. In this way, the RCC cofferdam, the aforementioned temporary water retaining structure, can be removed in September, 2006, and the reservoir water level will be raised to an elevation of 156 meters in October of that year

as the dam on the right bank is poured to the top within three years, a series of construction projects of auxiliary dam buildings, such as complex curtain grouting, joint grouting, 22 bottom outlets plugging and the production and installation of dozens of gates of various types, will be completed one by one when the dam is impounded again in 2006. Among them, the total length of curtain grouting is about 80000 meters, joint grouting is nearly 60000 square meters, and metal structure installation is 62600 tons

the power station on the right bank is to be built, and 12 large units will be completed in 2009.

the Three Gorges power station, which is arranged behind the Three Gorges Dam, is composed of left and right power plants. Among them, the left bank power station to be completed will be installed with 14 700000 kW turbines, and the right bank power station to be formed in phase III project will be installed with 12 700000 kW units

the civil engineering of the power station is mainly the capital construction of the plant. After digging nearly 2million cubic meters of foundation rock, 1.38 million cubic meters of concrete will be poured. During the four-year process, 22200 tons of metal structures will be installed successively. For the installation of generator units in the power station, the total installed tonnage of 12 units is 61700 tons. It is planned that 6 units will be put into operation in 2007 and 2008 respectively. Among them, the power generation arrangement in 2007 is: two units are put into operation before the flood season, two units are put into operation during the flood season, and two units are put into operation at the end of the year

the construction of the power station on the right bank is a systematic project. As far as the special equipment of the power station is concerned, in addition to the procurement, installation and commissioning of 12 sets of main machines, the manufacturing and installation of 12 sets of auxiliary machines are also very heavy, such as the speed regulation system, excitation system, and the supporting large transformers and auxiliary equipment: there are many components, strict technology, and short supply period. The procurement should be completed within twoorthree years and the quality and warranty period should be in place. The builders of the Three Gorges project have to overcome numerous difficulties one by one

in addition, the units on the right bank will be put into operation in 2007, and the power transmission and transformation project will also be started synchronously in 2004. In the third phase of the project, the Three Gorges power transmission and transformation project plans to build 3942 kilometers of 500 kV AC transmission lines, accounting for 60% of the total scale of the Three Gorges power transmission and transformation project; 500kV AC substation capacity is 15million KVA, accounting for 66% of the total scale; The 500kV DC transmission line is 2075km, accounting for 67% of the total scale. Among them, the Three Gorges Guangzhou DC transmission project is scheduled to be put into operation in 2004 and can be expanded in the first quarter according to user requirements. The Three Gorges Shanghai DC transmission project is scheduled to be put into operation in the first half of 2008

the underground power station will increase its capacity by 4.2 million KW by adding 6 machines to the "cavern"

the Three Gorges underground power station is to drill a hole in the "baiyanjian" on the right side of the dam to form an underground powerhouse, and then install 6 700000 kW units in the big belly powerhouse to generate power. Its main buildings include: headrace channel and intake tower, headrace tunnel, main power house, installation site, tailrace tunnel, bus shaft, 500kV substation, etc. Since the power generation equipment is installed in the hinterland of the mountain, there is no need for land acquisition and immigration, so it is easy and labor-saving. In the future, this underground power station will add 6 more generating units to the Three Gorges power station, increasing its total installed capacity from 26 to 32. The additional installed capacity of power generation is equivalent to building 1.5 Gezhouba hydropower station or 2.3 Xiaolangdi Hydropower Station. Of course, the biggest advantage of its construction is to maximize the utilization index of water inventory and maximize the time period for peak shaving without abandoning water in the Three Gorges Project

in the preliminary design report of the Three Gorges project published in 1993, it is mentioned that there is an underground powerhouse on the right bank for later expansion. In the summer of 2001, some media reported that the total installed capacity of the Three Gorges power station would increase from 18.2 million kW to 22.4 million KW, but it did not attract the attention of the Chinese people. At present, the experts' discussion and demonstration have come to an end. According to the current demand of the power market, the construction plan and commencement report were approved by the Three Gorges Construction Commission of the State Council at the end of last year, and the civil engineering of the Three Gorges underground power station was approved in principle. This marks that the "Three Gorges underground power station" has moved from behind the scenes to in front of the stage in 2004

in order to finish the pre construction project in dry land before water storage, the pre construction project of underground power station was started as the "first bid" in August, 2001. At the beginning of the new year in 2004, two contracts were signed for the excavation of adits for underground power stations and the excavation and support of tailrace; With the approval of several bidding documents for the underground power station, such as the civil construction of underground caverns of the Three Gorges underground power station and the procurement of underground power station inlet quick gate and dam crest gantry crane, the bidding for the civil engineering and metal structure manufacturing and installation works of the Three Gorges underground power station will also be launched one after another within this year

after the completion of the Three Gorges underground power station and the power station behind the dam, the total installed capacity of the Three Gorges power station will be increased to 22.4 million KW, and the water utilization coefficient is expected to exceed 90%. The completion of the underground power station will not only enable the Three Gorges power station to make better use of water resources and generate more power, but also increase the peak load regulation capacity of the Three Gorges power station. The experts who demonstrated the underground power station said that the enhancement of peak shaving capacity can increase the time of peak shaving without abandoning water in the Three Gorges project, which undoubtedly plays an important role in supplementing the increasing demand for peak shaving in central and eastern China and the stability of the power system in the future

passenger ships need to cross the dam quickly, and the vertical ship lift has entered the key problem solving stage.

there are two navigation buildings in the Three Gorges project, one is the stepped double track five level ship lock, and the other is the vertical ship lift like an elevator. The former has been put into operation on June 16, 2003. According to the statistics in November, it has reached the level of 194 ships passing through the daily average (25.6 times of double track five-level lock). However, it takes about 3 hours for each ship to pass through the five level lock. In order to shorten the time for passenger ships to pass through the dam, the Three Gorges will build a special channel for passengers to pass through the dam quickly: the vertical ship lift has entered the design and manufacturing process since 2004 according to the optimized design scheme

from a technical point of view, this is the last technical difficulty that the Three Gorges Project will overcome. It is a super large elevator, which rises at a constant speed through a water bearing box (which can hold a 3000 ton passenger ship). We have to move forward and lower all the time. The maximum lifting height of the ship lift is 113 meters, and the maximum lifting weight is 11800 tons (the weight of the ship carrying box is 2800 tons, including 9000 tons of water and heavy-duty ships). After the completion of this ship lift, it will be the largest ship lift of the same type in the world. The largest vertical ship lift in the world today is the stelleby vertical ship lift on the Belgian central canal. Its maximum lifting height is only 73 meters and its maximum lifting weight is only 8800 tons

experts say that this set of ship lift mechanical equipment has large processing capacity and high precision requirements. Some domestic mechanical equipment manufacturing enterprises have no processing experience, and there are a series of technical problems in their manufacturing. In addition, its security requirements are unparalleled. Especially for the lifting system and automatic control system of ship lift, the requirements are extremely high. Because large passenger ships usually carry thousands of passengers, safety must be absolutely guaranteed

in order to ensure the absolute safety of ship lift operation, the owner of the Three Gorges project organized dozens of domestic experts to review and make decisions on the two schemes in the past year. While listening to the report on comparison of schemes for the main part of the Three Gorges ship lift issued by the Yangtze River Water Resources Commission, the designer, and on the basis of full study and comparison of different schemes, confirmed the reliability of this ship lift - gear rack climbing, long nut column and short screw drive and safety device. It is considered that even in case of water leakage or overload accident, the braking locking operation can be carried out automatically according to the set limit load, so as to avoid accidents

when talking about the construction of the Three Gorges vertical ship lift, liyongan, general manager of China Three Gorges Corporation, said recently that the technical design of the ship box section and its auxiliary equipment should be completed this year, and the detailed design of the equipment manufacturing of the ship box driving part and the accident safety mechanism should be completed by the end of next year. It is also emphasized that the design and manufacturing of the vertical ship lift should be well done, the design contract should be signed as soon as possible, and the supply and installation plan should be implemented year by year, so as to ensure that the vertical ship lift can be completed on schedule and run without accidents in the future

in addition to the main engineering projects, there are still some supporting and auxiliary projects before 2009, and some conductive materials are transparent, which need to be completed in the process of interleaving. In order to ensure and guarantee the emergency standby power supply of the Three Gorges power plant, the power station composed of two 50000 kW units is entering the construction stage. In order to predict and monitor minor changes in dams, power stations and ship locks, and to verify and prevent siltation and earthquake series changes in the reservoir area, the

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