View of setting the valve of Xiaowan Power Station

Accident gates, quick gates for access doors, accident gates for access doors, and access doors without flying protection devices Ministerial standard “Technical Code for Electromechanical Design of Hydroelectric Power Plants” (Trial) SDJ173-85 (Applies to Units) approved by the Ministry of Water Resources and Electric Power in 1986 Capacity: 10~300MW): When using water, inlet valve should be installed before each turbine.

In the water pressure unit of the Zhongshuitou unit, the inlet valve should not be installed before the turbine, but a fast gate should be installed at the inlet of the pressure water pipe.

The preparation of the clause states that “the establishment of a fast gate or accident gate in the inlet of a water pipeline is an effective protective measure to prevent the expansion of accidents associated with the equipment (such as the shutdown of the unit when the accident is shut down, the breaking of some guide vanes, or the rupture of the penstock). The experience of design and operation of hydropower plants shows that this is generally economically reasonable, and fast gates should be set at the inlets of the water conveyance channels in the middle and high head hydraulic power plants, and low-head hydropower plants can be equipped with accidental gates to save investment.

When the water delivery pipe is a clear pipe, a quick gate must be provided at the water inlet to prevent the accident from expanding when the bright pipe bursts. “Rapid Gates. Access Doors Although the provisions only specify the pressure heads of the head unit, the preparation instructions include high heads. The Xiaowan Power Station should be included.

In 1995, the industry standard “Water gates and steel gates for water conservancy and hydropower projects 4.1 When units or steel pipes were required to be gated for accident protection, rapid gates and maintenance gates should be installed at the inlet of the dam-type power station; diversion-type power stations, except at the inlet of pressure pipelines. Outside the rapid gate, accident gates should be installed at the entrance of long water intakes.

In summary, it can be considered that the setting of the inlet gate is to protect the unit and the steel pipe, and it is also convenient for the maintenance of the unit and the steel pipe. In order to prevent the expansion of the crew flight accident, if there is no inlet valve, a quick gate must be provided at the inlet. For the low head riverbed power station, when the unit has a reliable anti-flying device, the accidental gate can be used to protect the pressure water pipe to save investment. For the high and low head power station water intakes, fast gates are installed, which not only protects the unit but also protects the unit. Steel pipe, so the unit pressure 1 coder profile: Wu Ciguang (1iW male, Zhejiang Zhejiang Jiangren, professor-level senior engineer, is mainly engaged in the hydropower machinery design work. eserved.http:// fast valve into the water valve (bright tube, Shallow buried pipes) Access doors, accident gates (underground pipes), access gate inlet valves, and inlet rapid gates for technical and economical comparisons High heads and diversion-type power stations Mid-head and post-dam or hybrid plants Low-head and river-bed The view of the power station on the installation of the valve in the Xiaowan Power Plant Wu Ciguang (China Hydropower Consultancy Kunming Company, Kunming, Yunnan, 6551) The installation of the valve in the Zhengxiaowan hydraulic turbine is not only technically feasible, but also economically reasonable, and can be used by the owners and relevant departments to make decisions.

Whether a water inlet valve is provided in front of the turbine or not is specifically stipulated in the former Ministry of Water Resources and Power (10MW).

Responsible editor of the national standards approved by the State Development Planning Commission<<Hydroelectric power generation according to the requirements of the specification can be listed in Table 1. Station Design Specification (Trial) GBJ71 Table 1 Installation of Pressure Water Pipe Inlet Gates and Turbine Advance Water Valves (Small Hydropower station) maximum water head or power station form turbine inlet or pressure water inlet valve valve water and water inlet fly in Yunnan hydroelectric power 2 (1) 1 year supplement water turbine before the water pipeline should not be installed to protect the unit and then into the water valve, so as to avoid waste, so The preliminary design of the Xiaowan Power Station did not include an inlet valve before the turbine and a quick gate at the inlet. The same was true for the Ertan Power Station, which had already been built.

However, the function, nature and operation mode of the inlet quick gate and the turbine advance valve are different. The former is called the hydraulic building gate. Its role is to prevent the expansion of the accidents of the pressure pipe and the unit equipment behind the gate (for the shallow-buried steel pipe and the uncovered steel pipe also include the protection of the plant) and to facilitate the inspection of the pressure pipe and the unit. Equipment, its opening and closing operations are determined according to the above needs, and has nothing to do with the operation of the unit; the latter called the turbine auxiliary equipment, its role is only to protect the unit, to prevent the expansion of the unit accident and overhaul the unit, its opening and closing in addition to protection In addition to overhauling the unit, more is a random group of starting and stopping and opening and closing. Its operation is part of the unit operating procedure. Its role in the low head and Zhongshuitou power station can be replaced by the fast gate part of the inlet (but The operation of the fast gate is still independent and not in the unit operation procedure.) The role of the inlet valve in the higher mid-head and high-head power stations is that the fast gate at the inlet is difficult to completely replace, so the maximum head is specified in the small hydropower station. When it is larger than 150m, after the fast gate is set at the inlet, the inlet valve is also installed in front of the turbine. Actually, it is not only a small hydropower station, but also a large one. Hydropower plants should also be the case, due to a variety of reasons, the leakage of cavitation in the gap between guide vanes still exists, especially high-headed or poly-silt hydropower stations.

The effects of the inlet valve and the inlet gate are different. They are shown as follows: (1) There is a difference in the effect of preventing the flight crew from expanding. When the unit load rejection and speed control system failure, the unit over-speed to 150%, over-speed protection action, inlet valve began to close, generally off the end of 60s, but about 20s or so the unit will rise from 150% n to the time under the water head The speed of the fly, for 20s or more (no more than 40s), the speed then drops. For single-enthalpy pressure water pipes whose heads are larger than 150m or 200m, the general pipelines are long and the amount of water is large, and the closing time of the fast gates at the inlet is 120s. The unit is overspeeded by 150% n. The gates are closed and they reach the time of less than 20s. Under the head of water, the speed of rotation, after 60 ~ 100s, although the gate has been fully closed, but due to the water in the pipe, the speed of the flyaway is likely to exceed the conventional allowable value of 120s, so the water inlet in the high and medium head power station is fast The gate and the inlet valve are different in the effect of preventing flight and protecting the unit.

(2) There are differences in the role of protecting turbines from erosion damage caused by guide vanes, upper and lower wear plates, and rotor blade inlet sides. Because the inlet valve is shut down by a random group, there is only tail water pressure before and after the shutdown, there is no pressure difference, no erosion damage. If there is no fast gate, the differential pressure of the hydrostatic head of the power station will be received before and after the guide vane. Inevitably, high-speed jets and gap erosion damage will occur in the upper and lower end faces of the guide vane and the gap between the facades, so that the guide vane face, facade, and shaft The upper and lower ends of the neck, the upper and lower wear plates and even the inlet side of the rotor blades are damaged to varying degrees. With the development of modern manufacturing technology, the guide vane end face and facade gap can be made very small and sealed well, but it cannot Completely eliminated. In the case of high head hydraulic turbines, even if the new guide vanes are completely closed during installation (which is actually impossible), the national standard “Hydraulic Generator Set Installation Specifications” (GB8564~88, Sections 3.5.l and 3.5.2) Permissible values) However, under the action of water pressure, the deformation of the guide vanes and the top cover is relatively large, and the deformation will bring gaps. If the compensation of deformation is taken into account in the design, the new guide vanes are completely sealed under water pressure, but In case of water leakage, the contact pressure between all the sealing surfaces must be several times or even ten times the water pressure. This is even more difficult to achieve. Therefore, all water turbines are not exceptional when the volute water guide vane is pressurized. The large noise caused by leakage of the guide vane clearance is especially serious. High head units are particularly serious. Sometimes the guide vane leakage can impinge on the rotating part of the unit after the high pressure oil pushes up the thrust head. We can compare the leakage sound of the guide vanes before and after the inlet valve is closed in the turbine pit, and we can gain a deep impression of the protection effect of the inlet valve on the guide vane.

This gap damage is exacerbated by the increase of water head and sediment content. It is understood that the overhaul period of the Liujiaxia hydropower station unit is controlled by damage to the guide vanes and the upper and lower wear plates. Although Mantou Bay's water head is not high, it contains a certain amount of damage. Sedimentation, in order to avoid the rapid damage of the guide vanes and the introduction of the valve technology, a valve has been added to the Manwan Hydropower Plant. It now appears that the desired effect has been achieved. Other inlet valves, such as butterfly valves and ball valves, can also protect the guide vanes, and the inlet quick gates are closed due to the non-random group shutdown, and cannot protect the vanes from being damaged when they are stopped. There are few problems in the middle and low head Shuihe hydropower stations, but the problem is very serious in the high water heads and sandy currents.

(3) The stopping effect and time are different. With the inlet valve, the guide vanes and the upper and lower wear plates are protected. After the guide vanes are fully closed, there is little water leakage. With the inlet valve closed, there is no leakage of the guide vanes, and the unit can quickly be braked to brake speed. Stopped. There is no water inlet valve, the guide vane alone closes, the leakage is small at the beginning, the effect is acceptable. After a few years, the guide vane is gradually damaged, the leakage water is gradually increased, and the time for the unit speed to drop to the braking speed is longer and longer. At braking speeds, brakes have to be applied at high speeds, not only for a long period of shutdown, but also for the generators to be contaminated by dust, and the gates are heavily worn. This phenomenon is particularly prominent in the peaking units with a large number of shutdowns. It is understood that the leakage of guide vanes in the Liujiaxia turbine from 3 to 4 years has increased from 1.5m3/s to 7m3/s, and the speed is difficult to reduce to 35%n. It is necessary to carry out major repairs; Wujiangdu has similar conditions (of course, the water is clear, and development will not So fast) Electrical brakes were added later, but electrical brakes would bring other problems.

The general shutdown of the water valve, especially the standby shutdown of the accident, is not related to the ability and need of the inlet water valve and the quick gate opening. Wu Diguang's views on setting the valve in the Xiaowan Power Plant are different, which directly affects the unit startup time. The quick gate is closed without normal shutdown of the random group. When the unit restarts, it only needs to open the guide vane. The startup speed is very fast. As long as the quick gate is not closed, it will not have any effect on the unit startup time. However, when the accident is shut down after the accident, maintenance or long-term shutdown and the quick gate is closed, the water in the pressure pipe behind the gate must first be filled. When the water starts filling, the water level in the pipe rises quickly, but as the water level rises, the guide vane The amount of water leakage increases, and the water volume of the bypass pipe must be less than the amount of water leakage from the guide vane. The large medium-high head power station not only has a long water pipe, but also has a large body of water to be filled. The amount of water leakage from the guide vane is also high due to the high head. In particular, it is time-consuming to fill the guide vanes after they have been damaged by abrasion. The specification requires that the water pressure of the turbine pressure water pipe should not exceed 30 minutes, and in fact, it may not be enough for several hours. The rapid gate must be opened by still water, and the maximum is only The allowable pressure difference between the front and the back of the gate is only 1 Liu Jiaxia Power Station has to plug cotton wool into the guide vane to open the quick gate. In the first half of 1994, the No. 6 cylinder valve of Manwan Hydropower Station was not put into operation. Before the quick gate was opened, the bypass valve was used to fill the pressure steel pipe with 7 water. Because the guide vane leaked, the water was filled for less than a few hours, adding a Y300mm water pipe. Water can only increase the water level in the pipe. The water level difference between the front and the back of the gate is still 16m, and the required water pressure difference before the gate opening cannot be achieved. Therefore, the quick gate opening is not only time-consuming, but also sometimes difficult. It can not meet the requirements for peaking and accident backup in the system. It can only stop the rapid gate, or change the rapid gate to a working gate, and the dynamic water is turned on. Not only greatly increase the capacity and cost of hoists, but also it is not safe. Since the inlet valve is close to the turbine, the volume of the bypass pipe to be filled before the valve is opened is very small, and the water turbine with a negative suction height does not need to be filled with water. Before the valve is opened, the volute is filled with the downstream water. After the valve opens, the pressure of the volute immediately rises, and the rise value depends on the ratio of the bypass flow rate and the amount of water leakage from the guide vane (when the guide vane leakage is large, the pressure difference between the valve before and after the valve cannot meet the design requirements. The butterfly valve or ball valve cannot be opened). According to GB/TI 4478-93, the national standard “Basic Technical Requirements for Large and Medium-sized Turbine Inlet Valves”, it is allowed to open normally when the pressure difference between the two sides of the valve is not more than 30% of the maximum hydrostatic pressure, and for the hydrostatic pressure of 250m. The water valve, which is allowed to open at a pressure difference of 75m, is much larger than the opening capacity of the quick gate, and the entire opening time is much shorter. For the hydraulically balanced cylinder valve on the circumference, there is no need for the bypass tube to charge the horizontal pressure, and the dynamic water can be turned on under the maximum hydrostatic pressure, so the cylinder valve is particularly suitable for the unit that bears the peak load and accident backup in the system.

(5) Only with the quick inlet gate and the additional inlet valve, the water leakage of the turbine during shutdown is different. The former is actually the leakage of the guide vane. According to the national standard “Water Turbine Basic Technical Conditions” GB/T15468― In 1995, it was stipulated that under the rated water head, new guide vanes leaked, such as 5.8% after Liu Jiaxia overhauled. The latter is the water leakage of the inlet valve. According to the national standard, the basic technology of the inlet valve for large and medium turbines/14478-93, the leakage of the butterfly valve and the ball valve is not greater than: K, and the double-plate butterfly valve sealed by air is 0.402 solid sealed double flat butterfly valve is 0.223, ball valve is 0.103. Take Xiaowan as an example, the actual situation of some power stations is estimated: there is a fast inlet gate, there is no inlet valve, and the water leakage amount of the newly commissioned guide vane is rated. 3% of flow rate is about 1m3/s. Suppose 10 years later, when the speed of turning off the guide vanes is reduced, the speed drops below the brake speed and must be overhauled (the Liujiaxia water contains more sediment, but the water head is low, and occurs after about 3 to 4 years. Similarly, the leakage of water is about 7m3/s which is 27% of the rated flow. At this time, the amount of water leakage from the guide vane is 8m3/s (2.2% of the rated flow). One machine is overhauled each year, and six years is an overhaul cycle. The average annual leakage during each overhaul cycle is 3. When there is a water inlet valve, the leakage of the new ball valve is calculated according to the specifications.) The specifications of the valve are not stipulated, and the measured value of Manwan is approximately the amount of water leakage from the guide vane. 3%, the new valve is 0.03m3 //is the largest in the inlet valve, in large The average annual water leakage during the repair cycle is 0. / It is 3% of the amount of water leakage from the guide vane when only the rapid gate of the inlet is set. (6) The effect on the pressure steel pipe is different. When only the fast gate of the inlet is provided, the quick gate is closed during pressure water pipe accidents, overhauls, unit accidents, maintenance, and long-term shutdowns. The probability is higher than the pressure water pipe accident, maintenance, and inlet valve accident after setting the water inlet width. There are many more shut-downs during maintenance, and more frequent filling and discharging of water is not good for pressure pipes.

There is no doubt that adding additional inlet valves will increase investment. Taking Xiaowan as an example, if a butterfly valve is used, the diameter is about 8.5m and the weight is more than 900t. Moreover, the use of a butterfly valve with such a large diameter as the head of pressure of about 3(1) m has no precedent at home and abroad, and is not only expensive, but also Technically difficult, the diameter of the steel pipe also has to increase, and the factory building must be widened, which is unreasonable. If the ball valve is used, the diameter is about 6.5m and the weight is more than 1250t. It is almost the same as the weight of the turbine. There is no precedent at home and abroad, the price is more expensive, the technical difficulty even exceeds that of the turbine, and the factory building must be wider. This is unrealistic. If the cylinder valve is used, the outer diameter of the cylinder valve is about 9.0m, the thickness is about 0.3m, and the height is about 1.35m. The weight of the cylinder is about 88t. (There are already larger cylinder valves in operation in foreign countries. The cylinder outer diameter of the cylinder of Xiaolangdi Power Station in China 8.39m thick 0.145m, high 1.715m, the cylinder should not be greater than 3% of the rated flow of the turbine, (actually often does not weigh about plus, plus the relay and the valve due to the top cover, etc. increase Yunnan hydropower In 2001, the weight of the supplement was about 150 tons. Only 17% of the ball valve weight was 12%. After the valve was set, the weight of the turbine was increased from 1260t to 1410t. The price will also increase by 12% to about RMB 6 million (one machine The entire power station is about 36 million yuan, but the diameter of the steel pipe will not increase, the size of the plant will not increase, and there will be experience in power stations such as Manwan, Xiaolangdi, and Dachaoshan. It is understood that Manwanduan valve has been operating more than 8,800 times so far. Each cylinder valve has operated nearly 1 800 times, and the hydrodynamic shut-off test has been done. Its reliability is credible. Therefore, the use of the cylinder valve at Xiaowan Power Station is not only technically possible, but also economically acceptable.

From the above preliminary analysis, even if the increase in investment caused by the size change of the plant and the steel pipe is not taken into account, the investment in the butterfly valve or ball valve and its operating system in front of the large medium and high head hydraulic turbines will be faster than the rapid gate and hydraulic pressure at the inlet. The hoist is expensive, so it is not advisable to install a butterfly valve or ball valve in front of a large medium and high head hydraulic turbine. Instead, it should rely on the fast gate protection unit installed at the inlet. However, the price of adding a cylinder valve and its operating system to a large-scale hydraulic turbine is comparable to the price of a fast gate at the inlet and the price of the hydraulic hoist. The management and maintenance are also relatively convenient. Therefore, in large and giant power plants, It is necessary and reasonable to protect the unit and the operation of the system is reliable and flexible.

The Xiaowan generating unit undertakes the important tasks of frequency modulation, peak regulation and accident backup in the system. The monthly average output of the power station is as shown.

In addition to the high load in August and September, and the average load in July and October, the load rate of the remaining eight months is less than half. For the stable operation of the unit, the load should be concentrated as much as possible to avoid 50% of rated load is operating below the load, so there are no less than two generators on average each year (a total of about 18 units in shutdown, after deducting two months of one machine overhaul period each year, the annual shutdown leakage time is about 16500 hours (since Xiaowan is Incomplete adjustment of reservoirs for many years, not annual flood discharge, and flood discharge only operates at full load in August, all six machines are in operation, so the impact of flood discharge is not deducted.) Since the valves are installed, the average annual leakage of each machine is reduced. 3m3 / s, the entire power plant so more power generation 0.98X108kW ° h, such as by 0.17 yuan / kWli count, an annual increase of 66.66 million yuan, even if you do not consider extending the overhaul cycle to reduce the workload of maintenance work, only to reduce the benefits of water leakage, In 2 to 3 years, the investment in the cylinder valve and its hydraulic device can be recovered. Therefore, it is economically reasonable. It is not necessary to reduce the inlet gate to compensate for the increase in the number of cylinder valves.

One of the quick gates at the inlet is to protect the pressure pipes, but whether all the pressure pipes require fast gate protection, in the current ministerial standard, "Design Specification for Hydropower Station Penstocks" SDI44-85, provides: Underground underground pipelines shall be provided with fast gates and necessary overhaul facilities at the first end of the pipeline.

Underground buried pipes, if the length of the water intake from the intake to the steel pipe is long, or the internal pressure of the steel pipe is large, and the buried depth is not large, an accidental gate shall be provided at the head end.

Therefore, after the turbine tank width is added in front of the turbine, the protection of the buried pipe of the Xiaowan Hydropower Station can include accidental gates and access gates at the intake. As in the Dachaoshan Hydropower Station, of course, the quick gates and maintenance gates should be safer and more reliable. This is determined by the hydraulic design.

In short, the preliminary design of the Xiaowan Hydropower Station is in line with the current regulations, but it is beneficial to add an inlet valve in front of a high head unit like Xiaowan. Butterfly valves and ball valves are technically very difficult and economically expensive and should not be used. Although the current spool valve is still part of the turbine, it must be dismantled with the turbine and cannot meet the need for overhaul of the turbine. The inlet gate must be closed during inspections, but this is perfectly acceptable in the single-tube single-phase Xiaowan Power Station. Now that there are practical experiences in power stations such as Manwan, Xiaolangdi, and Dachaoshan, the addition of the valve on the turbine is not only more secure and reliable, it can better protect the turbine and prolong the overhaul cycle, and it is technically feasible and economically feasible. Reasonably, if the volute is to be used for hydrostatic testing later, the cylinder can also be used as one of the bulkheads of the volute. Therefore, it is recommended that a valve be installed on the Xiaowan turbine to meet the requirements for frequency regulation, peak regulation and emergency backup.

Pre Solder Brass Fittings

Pre solder Brass Fittings's solder ring is as smooth as yorkshire and it is real no lead according to Rohs,pre solder brass fittings,solder ring brass fittings,pegler solder ring brass fittings,connex solder ring brass fittings,SR brass fittings,solder ring brass pipe fittings

presolder brass fittings,solder ring brass fittings,pegler solder ring brass fittings,connex solder ring brass fittings,SR brass fittings,solder ring brass pipe fittings

Taizhou Runde Company , https://www.zjpressfittings.com