After the founding of New China, large-scale water conservancy construction was carried out all over the country, which promoted the development of water conservancy science and technology. The following is my graduation thesis on water conservancy technology for your reference.

With the rapid development of the information age, social production has higher requirements for the promotion of mechanical automation and automatic control technology, higher requirements for the stability and safety of machinery operation, and the intelligent operation of machinery has become the general trend.

Keywords: mechanical hydraulic pressure; hydrotechnics

1. Service history of overspeed protection system of hydropower stations in China

At the initial stage of developing basic industries in China, most of the technologies and machines came from the former Soviet Union. For a long time after liberation, the design technology of hydro-generator set in the former Soviet Union was introduced into hydropower generation, and JSX mechanical speed signal was used as overspeed protection monitoring of hydro-generator set. However, due to the limitation of technology at that time, this type of mechanical speed annunciator can only send out overspeed protection signals, but can't take corresponding protection measures according to the signals, that is to say, it can only give an alarm and the machinery can't carry out corresponding protection operations; Another limitation is that this type of mechanical speed signal will appear false alarm or operation failure after long-term work. Until the mid-1980s, in view of the limitation that the former only reported signals but did not act, researchers added a mechanical and hydraulic overspeed protection device with an action part. However, due to the imperfection of electronic information technology at that time, the phenomenon of unsuccessful card swiping often led to refusal to perform surgery. After the reform and opening up, a large number of foreign products and technologies have been introduced into China, and several pure mechanical and hydraulic overspeed protection devices provided by foreign manufacturers have been applied in some hydropower stations. However, new problems have also emerged: the design of the snap ring connecting the pure mechanical and hydraulic overspeed protection devices with the main shaft of the hydro-generator is flawed, and a process of machining the teeth on the main shaft of the hydro-turbine needs to be added during installation to ensure that the device does not move axially on the main shaft of the hydro-turbine, that is, to ensure the stability of the device on the shaft. As we know, the material, size, thickness and length of bearings are strictly calculated. Re-machining the gear mouth on the main shaft of hydraulic turbine will inevitably affect the strength of the main shaft and cause great security risks. In addition, for economic construction, the time to get the goods, the procurement budget, the manpower and material resources spent, the mastery of foreign product technology and the after-sales maintenance service of its products are all important considerations. Therefore, it is urgent to adopt an efficient and reliable domestic overspeed protection system device, which can solve the above limitations.

2. Advantages of new mechanical and hydraulic overspeed protection devices

2. 1 Through the accumulation of technical knowledge and the experience feedback from previous field operation, we can know that the advantage of the mechanical-hydraulic overspeed protection device is that the obtained speed signal is not from the speed measuring device of the unit, but a water guide mechanism, which is closed by directly starting the emergency pressure distribution valve to operate the hydraulic circuit, because the centrifugal detector of the device itself drives the plunger to move radially through the centrifugal force that increases with the speed of the unit. It is completely another set of speed measuring methods and induction and operation devices on the same unit, which avoids the possible machine loss and runaway accidents after the failure of the electric speed measuring system and can ensure the safe execution of the hydro-generator set. China has produced a new type of mechanical hydraulic overspeed protection device, which is simple and easy to maintain. Compared with expensive foreign products, it has high reliability, less economic budget and is suitable for national conditions. It can be widely used in the operation of hydropower stations related to large, medium and small cities and villages in China.

2.2 technical points and ideas of a new type of mechanical hydraulic overspeed protection device

2.2. 1 In the case of governor failure, the new mechanical hydraulic overspeed protection device can realize "zero time" seamless connection, directly start the emergency pressure distribution valve to operate the hydraulic circuit to close the water guide mechanism, and realize emergency and safe shutdown.

2.2.2 The organic combination of new mechanical and hydraulic overspeed protection devices and electronic governor has actually completed the installation of two sets of overspeed protection devices. The new mechanical hydraulic overspeed protection device is essentially a backup protection device when the electric speed measuring system fails and the power supply system and the governor are out of control at the same time, which improves the working system of the overspeed protection device.

2.2.3 In view of the inevitable high temperature and bearing deformation caused by mechanical movement, as well as the high temperature and high pressure problems in the application scope, such as deep underground water intake of hydropower stations and deep underground oil production of petroleum industry, the new mechanical hydraulic overspeed protection device must overcome the difficulties of high pressure and high temperature. .

2.2.4 Standard hydraulic components have been widely used in the hydropower market. Applying standard hydraulic components to the new mechanical hydraulic overspeed protection device can not only save a lot of manufacturing time, improve the standardization of hydropower auxiliary products, but also reduce the difficulty of operation and maintenance.

3. The working principle of the device

3. 1 mechanical principle

A new type of mechanical hydraulic overspeed protection device is a two-stage control switch valve. The centrifugal detector consists of two semi-flange rings, a spring and a counterweight. The flange ring is installed on the big bearing. When the bearing rotates, the flange ring also rotates, and the centrifugal force generated by the rotation acts on the bearing plunger through the elastic force generated by the spring in the detector, eliminating the force and keeping it relatively static in the radial direction. The counterweight arranged on the flange ring enhances the stability of the movement of the two semi-flange rings. However, when the unit is in overspeed state and other overspeed protection devices cannot control the rotating speed normally, when the rotating speed of the unit reaches the set upper limit 17.8r/min, the centrifugal force generated by the plunger in the centrifugal detector is greater than the elastic force of the spring, which leads to the radial movement of the plunger. The direct result of radial displacement caused by the increase of centrifugal force is to increase the rotating radius of the plunger. When the radial displacement increases to a certain value, the plunger can directly hit the bump of the on-off valve, so that the on-off valve starts to act, and the electromagnetic pilot valve connected in series with the plunger acts on the emergency pressure distribution valve, and then the pressure oil pushes the emergency pressure distribution valve to switch the oil circuit, thus realizing the operation of quick stop. At the same time, the electrical contacts are connected and an emergency stop alarm is issued.

3.2 Working principle of hydraulic system

During the normal operation of the unit, the switch valve in the overspeed protection device is in the open state, and the electromagnetic pilot valve on the emergency pressure distribution valve does not act. At this time, the emergency pressure distribution valve is only used as a channel in the pipeline for the main pressure distribution valve to operate the guide vane relay, so that the pressure oil enters the guide vane relay through the channels of the main pressure distribution valve and the emergency pressure distribution valve. When the unit runs too fast, the governor can't adjust the speed, and the overspeed protection devices such as the electromagnetic reversing valve for emergency stop and the electromagnetic pilot valve on the emergency pressure distribution valve can't start normally, once the set critical value 1 17.8r/min is reached, the rotation radius of the plunger in the centrifugal detector increases due to centrifugal force, and it hits the bump of the on-off valve, so that the on-off valve enters the action program, and the oil on the left side of the emergency pressure distribution valve flows into the oil leakage tank. And the pressure oil on the other side of the discharged oil leads to the pressure difference between the pipelines on both sides. Due to the pressure generated by the right oil pressure, the right pressure oil pushes the piston of the emergency pressure distribution valve to the left, so that the pressure oil directly enters the closing cavity of the guide vane relay through the inner cavity of the emergency pressure distribution valve, at the same time, the pressure oil passage through the main pressure distribution valve is cut off, and the electric valve is closed through the guide vane relay. In this execution process, the pressure oil directly closes the guide vane relay through the inner cavity operation of the emergency pressure distribution valve, without passing through the main pressure distribution valve, which shortens the action route of the pressure oil, shortens the reaction time of the guide vane operation and reduces the fuel consumption. Another point that needs to be added is that when the emergency shutdown procedure is started to close the quick door at the entrance of the unit, the emergency shutdown procedure is also started to close the guide vane, which ensures the safety and reliability of shutdown.

4. Types of units available for mechanical and hydraulic overspeed protection devices in the operation of hydropower stations.

At present, the new mechanical hydraulic overspeed protection device based on standardized high-pressure anti-accident pressure distribution valve meets the requirements of various industrial times for mechanical products: high standardization, high pressure resistance, simple structure, convenient maintenance, economy and practicality. The mechanical hydraulic overspeed protection system can be used for axial flow, mixed flow, tubular flow and impulse turbine generator sets with rated speed within 2500r/min and bearing diameter within100 mm ~ 2500 mm. At present, it has been widely used in large, medium and small cities and rural hydropower stations in China, and many accidents have been avoided in operation, with good response. It should be pointed out that in practical application, in order to cooperate with the use of a new type of mechanical and hydraulic overspeed protection device, the hydropower station needs to install a maintenance gate on the diversion pipeline to facilitate the use and maintenance of the turbine. This device needs to increase a sum of money, but its overall cost is still less than the traditional overspeed protection device, which meets the needs of economy and practicality.

5. Concluding remarks

With the rapid development of the information age, social production has higher requirements for the promotion of mechanical automation and automatic control technology, as well as the stability and operation safety of machinery. Intelligent mechanical operation has become the general trend. At present, the mechanical and hydraulic overspeed protection system has become the last set of protection devices for overspeed protection when the electrical speed measurement system fails or the power supply and governor speed regulation fail at the same time, which can basically meet the needs of production. However, with the development of productivity, researchers have to adapt to the needs of production, carry out further technological innovation, and design safer and even fully intelligent overspeed protection devices.

refer to

1, Prediction and Planning of Water Conservancy Science and Technology Talents in Jiangxi Province in 2005 Chen Yunxiang Jiangxi Water Conservancy Science and Technology 2000-09-30

2. Development trend and research focus of rural water conservancy science and technology centered on water-saving irrigation, and Wu Jingshe Water Conservancy and Hydropower Science and Technology 2001-0/-20.

2. Huai 'an Water Conservancy Science and Technology Abstract: Water conservancy science and technology work is the key and foundation to realize water conservancy modernization. Through multi-level and all-round work measures, we will intensify the work of water conservancy science and technology, and push Huai 'an water conservancy modernization to a new level with the progress of water conservancy science and technology.

Keywords: Huai 'an Water Conservancy; science and technology

1 Take measures at the same time, organize carefully, and promote the scientific and technological work of water conservancy in an orderly manner.

In recent years, we have taken various forms to actively build various water conservancy science and technology service platforms to provide strong support for innovative water conservancy development. First, increase investment in agricultural and water conservancy research and experimental stations. There are three experimental stations of water conservancy science in Huai 'an, namely Lianshui, Huaiyin and Xuyi. Among them, Lianshui Experimental Station is one of the 100 national key experimental stations for agricultural water research approved by the Ministry of Water Resources, with 15 employees and 123 mu of experimental land. The experimental base, experimental shed and soil and water conservation experimental demonstration area have been built, which has created conditions for further research on the popularization and application of water conservancy science and technology in Huai' an city. The second is to build a new platform for innovative technical services. Huai 'an Water Conservancy Bureau and the Science and Technology Promotion Center of the Ministry of Water Resources signed a comprehensive cooperation framework agreement on water conservancy science and technology, which marked that Huai 'an entered a new stage in developing water through science and technology and improving the contribution rate of science and technology. Third, a strong technical talent has been established. Huai 'an Water Conservancy System includes 1 Grade A design unit, 1 Grade A construction enterprise and six secondary construction enterprises, with a total of about 4,000 employees. Among them, the total number of technicians accounts for about 50% of the total number of employees on the job, which provides talent support for the popularization of water conservancy science and technology in Huai' an city.

2. Insufficient investment, aging personnel structure, and problems still exist in water conservancy science and technology work.

Since the 11th Five-Year Plan, remarkable achievements have been made in water conservancy science and technology, but from the analysis of current water conservancy development strength, water conservancy development has not yet turned to the track of relying on scientific and technological progress. At present, water conservancy science and technology work still faces some problems.

2. 1 investment in science and technology is still insufficient.

With the expansion of water conservancy service field and the increase of scientific research cost, the current investment in science and technology still cannot meet the needs of water conservancy science and technology development in depth and breadth. No special scientific research fund and award fund have been set up.

2.2 The necessary research work in the preliminary work of water conservancy is not carried out enough.

Mainly reflected in the lack of awareness of scientific and technological innovation in engineering planning and design, the lack of internal motivation for innovation, the lack of design scheme preparation and technical support reserves, especially in rural water conservancy projects, the promotion and application of advanced technologies have not kept up.

2.3 Water environmental protection countermeasures need to be further strengthened.

The research progress of allowable pollution capacity of water body, groundwater recharge technology and water environment management mode in Huai 'an City can't keep up with the needs of economic and social development, especially the research on integrated technology of water peanut salvage and disposal and ecological dredging technology needs innovation and breakthrough.

2.4 New problems raised by the development of smart water conservancy

Under the premise of the development of global Internet of Things technology, the requirements of information exchange coding system and technical specifications of each system, the dynamic maintenance of central database and the intelligent functions of main application systems in Huai 'an water conservancy informatization construction will be a big challenge in the future.

2.5 Aging of water conservancy scientific research infrastructure

The three water conservancy research stations are short of funds for a long time, and supporting facilities are not in place in time. In addition, the equipment has not been properly maintained and updated in the implementation process, and it is seriously aging in the long-term implementation process. In addition, the data collection method is primitive and the accuracy is difficult to guarantee.

2.6 aging of water conservancy scientific research personnel structure

The staff are older, with lower academic qualifications and fewer professionals.

2.7 County development is very uneven.

A few counties and units do not pay enough attention to water conservancy science and technology work, and their awareness of scientific and technological innovation and popularization is weak. The measures to give priority to the development of science and technology have not been well implemented, and the necessary incentive measures are lacking.

3. Build the system and mechanism, and let the water conservancy work plug in the wings of science and technology.

During the "Thirteenth Five-Year Plan" period, a number of project studies will be carried out for hot and difficult work; Introduce, popularize and apply a number of advanced achievements in water conservancy science and technology, and build a number of water conservancy science and technology demonstration zones; Build a team of water conservancy scientific and technological talents with reasonable structure and high quality; Construction of water conservancy science and technology knowledge popularization base; Establish and improve the investment system and mechanism of water conservancy science and technology innovation led by enterprises and social forces, and continuously improve the investment intensity.

3. 1 Improve the four lifting systems

Popularization of science and technology is a key scientific and technological work to promote the transformation of water conservancy scientific and technological achievements into practical productive forces, promote the scientific and technological progress of water conservancy industry and serve the transformation from traditional water conservancy to modern water conservancy. It is necessary to strengthen the construction of extension system and improve it from four aspects. First, the promotion of survey and design technology, the promotion of mature technical products in the process of engineering design, the optimization of engineering layout and structural type, etc. Second, water conservancy construction enterprises, represented by water construction company, promote new products, new processes and new technologies in the process of project implementation to improve product quality and construction efficiency; Third, three water conservancy scientific research experimental stations in Huaiyin District, Lianshui County and Xuyi County, which use scientific methods and advanced devices to popularize basic water conservancy technologies; Fourthly, based on township water conservancy stations, the water conservancy science and technology extension system, including village group plumbers, promotes mature science and technology in the daily execution and maintenance of the project and gives full play to the project benefits.

3.2 Establish four research mechanisms

Science and technology research platform plays an important supporting role in the research, development and achievement transformation of water conservancy science and technology. Focusing on the overall situation of Huai 'an water conservancy development, we will carry out in-depth research and technical research on water conservancy modernization, water conservancy development system and mechanism, and management and protection of small rural water conservancy projects, and accelerate the improvement of the scientific and technological content of Huai 'an water conservancy construction management and the ability to serve a well-off society in an all-round way and build an important central city in northern Jiangsu. The first is the cooperation mechanism, which has extensive cooperation with Yangzhou University, Hohai University, scientific research institutes and other units in Huai 'an water conservancy system. These units provide 3-5 scientific research projects every year, which are connected with municipal and county water conservancy bureaus to carry out project research. Second, the reward and punishment mechanism, the establishment of water conservancy science and technology award fund, to stimulate the enthusiasm of the majority of scientific and technological personnel to innovate. Set up a supporting research fund for water conservancy projects and give financial support to projects approved by the Ministry and the province; Set up a scientific research achievement award fund, and give supporting awards to projects that receive superior awards according to different proportions of bonuses; The establishment of water conservancy academic papers award fund, the year-end organization of outstanding papers appraisal, the main author in the water conservancy junior and intermediate title evaluation to give extra points. The third is the introduction mechanism. Keep close contact with the Science and Technology Promotion Center of the Ministry of Water Resources and the Provincial Water Resources Department, and strive to give priority to reporting the latest water conservancy scientific and technological achievements and introducing and popularizing the "948" project in Huai 'an water conservancy work. The fourth is the innovation mechanism. In view of the hot and difficult problems in water conservancy work, guide and encourage all departments and units of the system to boldly use new ideas and measures to creatively carry out their work, break through key points, solve problems, improve efficiency, stimulate vitality, continuously improve innovation ability and work level, and promote water conservancy innovation and Excellence to a new level and produce fine products.

3.3 Establish multiple popular science platforms

During the "Thirteenth Five-Year Plan" period, we will actively popularize the knowledge of water conservancy science, focus on building five communication platforms, and explore the establishment of Huai' an water conservancy science education base relying on a number of regional water conservancy projects such as Sakura Garden; Open a column on Huai 'an water conservancy website, run an online water conservancy popular science garden well, and let the majority of water conservancy science and technology workers participate in the exchanges in water conservancy construction, rural water conservancy and urban water conservancy; Establishing QQ communication group, an instant communication platform for water conservancy science and technology workers in Huai 'an, can realize the sharing of scientific and technological information, widely and quickly transmit water conservancy scientific and technological information and solve problems encountered in work; Shoot and make water conservancy popular science videos; Run Huai 'an Water Conservancy magazine well, compile and distribute water conservancy popular science books, and increase the propaganda of popular science.

4. Careful selection and scientific layout, and actively promote the construction of water conservancy science and technology demonstration zones.

The water conservancy science and technology demonstration area is a demonstration area where water conservancy science and technology achievements are tested and demonstrated, integrated and matched, and the demonstration effect is brought into play. It can give full play to the demonstration role of water conservancy scientific and technological achievements in development, transformation, popularization and industrialization, promote the development of water conservancy science and technology and technological progress, promote the sustainable utilization of regional water resources and support the sustainable development of local economy and society. We have focused on the following water conservancy science and technology demonstration areas.

4. 1 Scientific development of modern ecological irrigation demonstration area

Focusing on ecological water conservancy projects, scientific water saving, standardization of supporting projects, humanization of scientific design, landscape of architectural image, scientific water dispatching, informatization of project management and organization of management team, we will actively publicize scientific and technological knowledge and build modern irrigation areas to better play a role in local economic development.

4.2 Water-saving and Efficient Pipeline Irrigation Demonstration Zone

Combined with the actual situation of the project area, the water-saving transformation of the project area is carried out by using pipeline water-saving irrigation technology to give full play to its role. Pipeline engineering can save a lot of water, reduce the occupation of cultivated land by water conveyance channels, reduce the cost of water lifting, save irrigation labor, promote industrial structure adjustment and reduce irrigation contradictions.

4.3 Ecological River Construction Demonstration Zone

Ecological management of rivers with a large area and a large quantity in rural areas will be carried out, and projects such as running water, clean water and purified water will be implemented, so that rivers can develop in harmony with surrounding ecosystems while meeting the requirements of flood control, waterlogging elimination, irrigation, water supply and navigation, maintain the ecological balance of rivers and maintain a good ecosystem.

4.4 Demonstration Zone of Modern Irrigation District with Long Vines and Guajie

In Xuyi County, a modern irrigation area of Changtenggua was built in combination with the irrigation area reconstruction project. Through the scientific transformation of the pumping station at the head of the canal, the water distribution canal system named Grapevine and the small reservoir and pond named Gua in the irrigation area, the schemes of water storage, water transfer, water lifting and water diversion are optimized by scientific means and managed by modern means, so as to maximize the efficiency and benefit of the irrigation area.

4.5 Soil and Water Conservation Science and Technology Demonstration Park

Construction of demonstration education bases for soil and water conservation along the abandoned Yellow River in Xuyi county and city. Sakura Garden has been established as the third batch of scientific and technological demonstration parks for soil and water conservation in China, forming a complete comprehensive protection system for soil and water loss in urban rivers in plain sand areas, which has played a role in demonstrating, guiding and radiating urban soil and water conservation.

4.6 Demonstration Zone for Comprehensive Improvement of Urban Water Environment

According to the principle of "smooth water, lively water, clear water and waterscape", we will strive to build an ecological water city. Smooth water flow, that is, build a safe water inlet and outlet system; Water activity, that is, to build a dynamic water system that complements and flows with each other; Clear water, that is, to build a crystal clear and rippling ecological water system; Waterscape is to build a scenic and unique landscape water system.

4.7 Water Conservancy Informatization Demonstration Zone

Using information technology to improve the modernization level of water conservancy project implementation and management. For example, the application of 3G technology in visual consultation of flood control command system, the launch of "flood control fast e-link" product and its application in the city's flood control system have effectively improved the emergency command ability of Huai 'an flood control command system, which is an information demonstration project in the whole province and even the whole country.

4.8 Water source protection demonstration area

Set up protected areas in surface drinking water sources and industrial centralized water sources, set clear geographical landmarks, obvious warning signs and protective facilities in primary and secondary drinking water source protected areas, prohibit all kinds of activities that pollute or may cause water pollution, and adopt modern scientific means to monitor to ensure the safety of water sources. Water science and technology work is the key and foundation to realize water modernization. Through multi-level and all-round work measures, we will intensify the work of water conservancy science and technology, and promote the modernization of Huai' an water conservancy to a new level with the progress of water conservancy science and technology.

refer to

1, Comprehensive Evaluation of China Water Conservancy Science and Technology Journals in 2000 Li Xiangdong, Journal of Heilongjiang Institute of Water Conservancy Jishan 2002- 12-30.

2. Calculation of the contribution rate of scientific and technological progress to Wang Bo's water conservancy economic growth: severe winter; Wu Jujiwei; Jiang Yusheng; Chen Zhenlin; China rural water and hydropower 2006-07- 15