1. Concrete Spun Pile Mould:
Concrete Spun Pile Mould is a kind of steel mould, it is mainly apply to Concrete Spun Pile Plant to produce the Centrifugal Reinforced Technology (PHC ) Concrete Spun Pile, In order to meet customer's requirement to produce high strength PHC concrete pile, Jiangsu Haiheng Company have long term cooperation relationship with Japan spun pile factories for improve the design and technology of mould and use advanced processing equipment, HH's spun pile mould has got the leader market share in the countries like Japan, Vietnam, Indonesia, Malaysia, Thailand, Myanmar, Cambodia etc.
Our Mould Advantages:
1. Mould's tongue-and-groove is designed by the dislocation of upper and lower shell boards, matchboard is plane surface. Slurry does not leak and it is easy to clean mould.
2. The tyre is "T" type forgings. Tyre and its support plate are as whole.
3. Self-developed six-meter press machine of mould inside shell. The inside shell seam extends from two meters to six meters, to minimize welds and mould strength and improve the external appearance of the products
4. Welding process uses CO2 arc shield weld which makes its appearance simple and weld seam neat. Our company cooperated with colleges to introduce [robot welding project".
5. Long lathe, manufacture the whole set mould under fifteen-meter length, greatly increases concentricity of the tyre and flange.
Spun pile Mould Specification:
Inside diameter(mm)
Wheel base(mm)
Wheel Diameter(mm)
Length(mm)
Ø300
2000
510
7-11
Ø350
2000
610
7-11
Ø400
2000
610
7-12
Ø450
2000
710
7-12
Ø500
2000
710
7-12
Ø550
2000
810
7-12
Ø600
2000
810
7-15
Ø800
2000
1010
7-15
Ø1000
2000
1210
7-15
If you have any questions, please contact with us directly. Concrete Pile Moulds are produced by High Quality and Esay transportation, quick assembling, good rigidity and smooth working. Welcome you can visit our Factory.For inqury,Please send mail directly to us.
Concrete Spun Pile,Reinforced Concrete Spun Pile Mould,Phc Spun Pile Mould,Pretensioned Concrete Spun Pile Mould Jiangsu Haiheng Building-Materials Machinery Co.,Ltd , https://www.jshaiheng.com
I. General situation of the unit
The CLN600-24.2/538/566 steam turbines produced by the Dongfang Steam Turbine Plant are the typical supercritical, intermediate reheat, impulse, and three-cylinder four-row steam turbines of the Jiangsu Power Resources Changshu No. 2 Power Plant Phase I project. Steam, single-shaft, double-back pressure, condensing steam turbines, and HGl952/25.4-YM1 supercritical, single furnace, once reheat, balanced ventilation, open-air layout, solid slag discharge, steel framework, and Harbin Boiler Works, Full-suspension structure Î -type Boiler-type direct current boiler and Dongfang Electric Machinery Factory supplied QFSN-600-2-22 water-hydrogen-hydrogen three-phase synchronous turbo-generator to form a unit generator set.
Turbine Digital Electrohydraulic Control (DEH) system and decentralized control system (DCS) using Hitachi's HIACS 5000M system; bypass using CCI AG's 40% boiler maximum continuous condition (BMCR) and 52% BMCR high and low voltage secondary Series bypass system. The default startup mode of the unit is the activation of the medium pressure cylinder [1].
Second, start the process and analysis [2]
2.1 From ignition to revolution
(1) high pressure cylinder warm
When the medium pressure cylinder is started, because the high pressure cylinder does not enter steam or only a small amount of steam, the high pressure cylinder is not sufficiently heated, and the high pressure cylinder wall is thicker than the medium pressure cylinder, so that the heating of the high pressure cylinder lags behind the medium pressure cylinder, if started If the warm tank is not sufficiently warmed above 150°C, the steam turbine will lag due to the delay in the heating of the high-pressure cylinder. An effective measure to achieve preheating is to increase steam pressure in the cylinder by introducing steam into the high pressure cylinder, so that the temperature of the cylinder metal is increased to a saturated temperature corresponding to the steam pressure or higher. Normally this pressure is specified as 0.4-0.5 MPa. When the temperature of the inner surface of the first-stage rear cylinder metal is lower than 15O°C, the high-pressure cylinder should be warmed up. When the inner metal temperature of the first level of the high-pressure inner cylinder is higher than this value, No warming up is required. The preheated steam of the high pressure cylinder shall not be less than 28°C, and the preheating steam pressure shall not be higher than 0.7MPa, otherwise the unit will generate additional thrust. During the high-pressure cylinder warm-up cylinder, adjust the metal temperature rise rate of the cylinder by adjusting the warm-up valve, the steam trap trap, and the high-return valve front trap to strictly control the metal temperature rise rate within the allowable range. The suffocating time is determined according to the "high pressure cylinder preheating suffocation time curve" provided by the manufacturer. The high pressure cylinder warm-up system is shown in Figure 1. 
(2) Valve housing warm-up
When the temperature of the inner wall or outer wall of the high pressure control valve (CV) is lower than 150°C, the steam chamber of the regulating valve must be warmed up before the turbine is driven to prevent the steam chamber of the regulating valve from being subjected to excessive thermal shock when the turbine is started. The main steam valve (MSV) does not open until warm-up of the regulator valve steam chamber is completed until warm-up is completed. The main steam for preheating enters the steam chamber of the regulating valve through the pre-open valve of the main steam valve No. 2 to preheat the four CV valve housings at the same time.
(3) Bypass operation
As the boiler heats up and boosts, the pressure before the high pressure bypass (hereinafter referred to as high side) reaches l.0 MPa, and the high side opening increases to maintain 1.0 MPa until the opening reaches 30%. The pressure before the high side rose to 1.lMPa. The high-side control mode was transferred from the minimum pressure control to the pressure ramp control to maintain the 30% opening, and the pressure was gradually increased to 8.73MPa. After that, transfer to the constant pressure control method. Low pressure bypass (hereinafter referred to as low side) control pressure to 1.lMPa.
2.2 From punch to inverted cylinder
(1) Friction check
When the actual speed reaches 200r/min, click "CLOSE ALL VALVE" on the control screen. The high pressure MSV and the high and medium pressure regulators are all closed. The medium pressure main steam valve (RSV) remains fully open and the turbine speed can gradually decrease. , And the steam flow noise disappears, which facilitates the transmission of the sound of the turbine operation and friction checks. During this period, the unit is not allowed to stop. After that, set the corresponding rate of rise and target speed, and the crew will re-acceleration.
(2) Speed ​​control
If warm-up mode is selected and the unit speed is below 400r/min, the CV will slowly open and the high pressure cylinder will be warmed up. When the speed reaches 400r/min, the CV valve position will be maintained and the medium pressure regulator (ICV) will gradually open. If the warm-up mode is not selected, the CV is not turned on and only the medium-voltage control door is turned on.
During the first few startups, it was found that in the warm-up mode, the CV is gradually turned off during the speed fluctuation, and the high pressure cylinder cannot be warmed up with a certain opening degree. The thermal inspection CV action conforms to the DEH internal logic function: ICV control for upshifting and CV control for downshifting. This logic means that the fluctuation of the speed will cause the CV to close, the high pressure cylinder cannot be warmed up, and the function is abnormal, which is forcedly maintained by the thermal engineering. CV valve position, ensure the normal warm-up.
(3) Grid connection with initial load
After the medium-speed warm-up is over, the unit raises the speed to the rated speed. When the DEH receives the input signal from the same period, the turbine speed oscillates in a certain pattern around 300 Or/min. When the conditions meet the same conditions, the oil switch is closed and the unit is automatically added. Load until the actual load rises to 5%.
2.3 Steam Turbine Inverted
(1) Selection of Main Steam Parameters for Inverted Cylinder
When the main steam pressure is constant, different inlet steam temperatures correspond to different high exhaust steam temperatures. Therefore, reasonable selection of main steam parameters can make the temperature difference between the main steam and the high pressure cylinder metal smaller, and reduce the thermal shock of the high pressure cylinder in the reversed cylinder process. And thermal stress. The selection of the main steam pressure should be based on the required high and low side capacity to allow the flow required to switch loads through the unit belt, taking into account whether the boiler startup characteristics can reach and maintain the pressure.
(2) Selection of Inverted Steam Steam Parameters
1 ICV stability. It is expected that the speed or load can increase steadily during start-up. The reheat steam pressure is too high. The volumetric flow rate of the steam entering the medium-pressure cylinder is smaller. The ICV opening and load curve is steeper, which is not conducive to the stability of the unit switching process. .
2 High pressure cylinder overheating problem. The reheat steam pressure is too high. When the cylinder is reversed, the pressure at the exhaust port of the high pressure cylinder is high, and the expansion ratio of the high pressure cylinder is small (the ratio of the initial pressure and the back pressure), which may cause the tail of the high pressure cylinder to overheat.
3 ICV flow capacity problem. The ICV flow rate is related to the reheat steam pressure. It can be known from the valve characteristics that when the reheat steam temperature is constant, the higher the reheat steam pressure, the greater the flow through the ICV at the same opening, and the ICV must pass through high when the cylinder is inverted. All the steam coming from the side brings the unit to the reversed cylinder load and the reheat steam pressure cannot be too low. The choice of reheat steam temperature should be based on the start-up characteristics of the boiler and the selected reheat steam pressure.
(3) Selection of inverted cylinder load
The advantages of the medium pressure cylinder start-up are played, and the medium and low pressure cylinders are accelerated; heating and expansion are performed, and the higher the reversed cylinder load, the more advantageous. However, the actual in-cylinder load of the unit is limited by factors such as axial thrust and main and reheat steam parameters, high bypass capacity, and ICV opening.
In general, the axial thrust under switching load should be much smaller than the unit's ultimate axial thrust. The size of the reversed cylinder load is mainly determined by the flow rate entering the intermediate pressure cylinder. Because the high bypass capacity and the selected main and reheat steam parameters of different units are different, the ICV opening degree when switching is different, so the reversed cylinder load value is also different. From the standpoint of safe start-up of the unit and better economy, it is recommended that the initial load of a 600 MW unit be 30-50 MW.
(4) Inverted cylinder process and analysis
When the reverse cylinder starts, click "LOAD UP" on the control screen to increase the load, the load starts to rise, and the high side starts to close. When the ICV opening is about 80%, the CV starts to open and the main steam is gradually transferred from the high side to the high pressure cylinder. With the establishment of the high-pressure cylinder pressure, the high-row counter-stop valve is opened, the vacuum valve (VV) is closed, and the high and low-side valves are gradually and fully closed, and the high-pressure cylinder ends in isolation and enters the normal flow state, and the cylinder is completed. The entire process of the invert cylinder stage is 1-2 minutes, and the high exhaust steam temperature has a brief rise and fall after the cylinder is started. After the load reaches 120MW, the CCS instruction is valid, and the DEH can accept the CCS instruction. In this function, the target load is 120MW when the pressure cylinder is started, and the load change rate is 30MW/min.
When the cylinder is inverted, the steam flow rate must not be lower than the start curve. Based on the steam flow rate, the load point at the end of the downhole cylinder can be estimated. The current problem is that LOAD UP must be loaded to 120 MW to stop the opening of the door. However, in the actual operation, the GOV SET manual increase/decrease button can be manually operated as long as the high side is turned off. At this time, the LOAD UP is overloaded. CV due to the presence of a pre-open valve, and the pre-open valve stroke accounted for 10% of the entire valve stroke, in the CV feedback 10% or less when the high-pressure cylinder does not actually enter the steam, so the high pressure cylinder does not immediately enter the steam in the cylinder switching CV open process The high pressure cylinder starts to enter the steam after CV is opened to 10%. In this stage, the flow of the high bypass valve has the problem of keeping constant during the continuous reduction process, which is unfavorable to the bypass control and causes the fluctuation of the main steam pressure. Since the LOAD UP process is fast and the load speed is 30 MW/min, it is necessary to pay attention to changes in the steam pressure during the process of inverting the cylinder to ensure the water level of the steam separator is stable.
At 20:48 on January 25, 2005, when Unit 1 reversed to the 1st cylinder, the main steam pressure changed rapidly from 8.80 MPa to 6.58 MPa due to the rapid opening of the CV and the slow shutdown of the high side. The water tank has a false water level, the boiler 35% water supply valve automatically shuts down, the water level in the storage tank begins to plummet, the water level is low, the jumper pump, the low inlet flow rate of the economizer protects the MFT, and the jumper jumps. Afterwards, the parameters for thermal adjustment were used to speed up the high side valve closing rate, and the manufacturer agreed to reduce the load rate to 24 MW/min. The problem was solved.
ICV is not fully open when the cylinder is reversed. If the low side is not fully closed at this time, the low side will not be closed in the automatic mode. Therefore, the pressure before the low side control valve increases with the load, and the pressure of the hot steam must be higher. Raise, open the low side to maintain pressure, then manually close the low side valve. The high-side control maintains the main steam pressure gradually closing when the CV is turned on, and attention should be paid to changes in the main steam pressure during the switching between the high side and the CV. After CV opens the high pressure cylinder inlet steam, if the main steam pressure drops due to the closure of the high side lagging behind the opening speed of the CV, pay attention to the change of the water separator level, and if necessary, manually close the CV to stabilize the main steam pressure. Operate the GOV SET increase/decrease button on the DEH panel to stop LOAD UP from continuing loading.
In the process of switching, it is necessary to strengthen the monitoring of the operation of the high-line check valve to ensure that the pressure difference between the front and rear of the valve is normal. The high-ventilation vent valve should be automatically closed after the CV is opened, and attention should be paid to changes in the temperature of the high-row metal. Before the cylinder is inverted, the steam trap before the MSV can be automatically withdrawn to avoid the influence of steam shut-off on the steam pressure during the cylinder inversion process. After the completion of the inverted cylinder operation, the automatic drainage is put in. After the end of the inverted cylinder, the bypass control should be checked. The control of the bypass is automatically controlled by the constant pressure control and the follow-up mode.
(5) Selection of the load at the end of the inverted cylinder
The load value of the end point of the turbine's reverse cylinder directly affects the stability of the boiler and turbine during the start-up process. In order to avoid overheating of the last stage of the high pressure cylinder, it must be ensured that the high pressure cylinder has sufficient flow, and the opening of the CV should be increased as much as possible. Therefore, the load should be raised from the 5% initial load to the end of the turbine's reverse cylinder at a short time.
When the load at the end point of the reversed cylinder is too high, the boiler combustion rate cannot keep up, resulting in a low main steam pressure. If the boiler combustion rate is manually intervened, the main steam pressure is likely to be too high, and the high side pressure is exceeded to make the high side valve. Always on. However, the load at the end of the inverted cylinder can not be too low, because the inlet of the high pressure cylinder is limited, and the deviation between the inlet temperature of the high pressure cylinder and the metal temperature of the low pressure cylinder must be controlled within a certain range, and the exhaust pressure of the high pressure cylinder must be high. For the set value of reheat steam pressure, the high pressure cylinder high flow back pressure can be avoided and the high pressure cylinder last stage blade can overheat. At the same time, it is ensured that the high row check valve can be smoothly opened, otherwise the high row check valve cannot be opened and the medium pressure cylinder fails to start.
2.4 Lifting load after inversion
After the completion of the cylinder inversion operation, the metal temperatures of the high and medium pressure cylinders and the low pressure cylinders have reached the temperature levels of the high and medium pressure cylinder joint starting belts with 20%-25% of the rated load. In order to prevent the cylinders from being cooled, the main steam and reheat steam parameters need to be quickly increased, the load is increased to a load of 20%-25% ECR, the lift load rate is 5 MW/min, and a low-load warm-up is performed. After the standby group is loaded with the load corresponding to the cylinder temperature, it is loaded to the full load according to the start-up curve provided by the manufacturer.
Third, the role of the bypass system in the start of the IP cylinder
The start-up of the medium pressure cylinder requires high operation of the bypass system, especially the bypass system can be put into automatic operation mode when the turbine is inverted, and the high-side system gradually closes as the high-pressure control door is gradually opened, and the two should be used in the process. Better matching to avoid sudden changes in main steam pressure and load when the cylinder is inverted.
The bypass system plays a decisive role in the starting mode of the medium pressure cylinder in two aspects.
(1) In terms of function, in high- and low-pressure series bypass systems, the high-side can achieve high pressure cylinder warming and medium pressure cylinder startup before unit start-up and high pressure cylinder isolation at the same time; low-side control reheat steam pressure, in In the early stage of startup, the low side can complete the adjustment and control of the operating parameters of the start of the IP cylinder, and recover part of the working medium.
(2) The capacity of the bypass system determines the ability to adjust and control the unit's revolution parameters, and the inverting load. The bypass capacity is large. The inversion pressure of the medium pressure cylinder starts is high. The advantages of the medium pressure cylinder startup method are: obvious. However, it is not unlimited. It is limited by axial thrust, and it has no practical significance to further increase the load switching point.
IV. Advantages of Medium Pressure Cylinder Startup
(1) When the unit is started cold, the temperature of the high pressure rotor has exceeded 150°C after the preheating of the rotor. When the medium pressure cylinder is started, the temperature rise of the medium pressure rotor is faster than that of the high and medium pressure joints, and the rotor can be made as quickly as possible. The low temperature brittle transition temperature improves the safety of the rotor.
(2) When the medium pressure cylinder is started, due to low parameters and large flow rate, it is beneficial to low speed and low load warm-up, so that the temperature of the medium and low pressure connecting pipes can meet the load requirements quickly, so as to achieve rapid start and load. The purpose is to shorten the start-up time.
(3) When the medium pressure cylinder is used to start, it effectively solves the problems of low reheater flow and slow heating of the medium pressure cylinder when the high pressure cylinder is started, and the high and medium pressure cylinders are heated evenly and the temperature rise is reasonable, making the cylinder easy to expand. Unit expansion is easy to control.
(4) The medium pressure cylinder can be started by closing the high row check valve, and the vacuum valve can be opened to isolate the high pressure cylinder to operate in a vacuum state, thereby avoiding the long load due to empty load or low load when the conventional high pressure medium pressure cylinder is jointly started. High-pressure cylinder over-temperature problem caused by time operation.
(5) When the medium pressure cylinder is started, the reheat steam flow is larger than the flow rate of the reheat steam when the high pressure and medium pressure are jointly started, which is favorable for protecting the boiler reheater.
(6) The starting pressure ratio of the medium-pressure cylinder and the starting pressure of the medium-pressure cylinder combined into the low-pressure cylinder are large, which can effectively reduce the pressure of the low-pressure end-stage temperature and the temperature of the exhaust cylinder.
(7) When the unit is started in hot state, the use of medium pressure cylinder to start can quickly increase the reheat steam temperature, so that the reheat steam temperature and the medium pressure cylinder temperature can be better matched, reducing the temperature due to the low reheat steam temperature Thermal Stress. At the same time, the phenomenon of negative differential expansion when the unit is hot started can be effectively controlled and mitigated.
(8) Compared with the joint start-up of high and medium pressure cylinders, the start-up operation mode of the medium-pressure cylinder is more flexible, and the single-machine-operated operation and idle-load operation time are not limited, and it is more favorable for the unit to start the peak-sharing task.
V. Conclusion
China Power's Changshu No.2 Power Plant Phase I Project Two domestically produced 600MW supercritical turbo-generator sets are started using medium-pressure cylinders. This starting method has many advantages and is conducive to quick start in various conditions.
Turbine inversion is a key operation in the process of the start of the medium pressure cylinder, and it should be achieved in the condition of the inverted cylinder. The problems found in the debugging process have been well resolved through improvement. During the period of commissioning and several intermediate pressure cylinders after commissioning, the metal temperature rise rate of the high and medium pressure cylinders and the thermal stress of the high and medium pressure rotors are within the design requirements, and the cylinder of the turbine generator set And the life of the rotor has little effect [5]. When the cold state and the warm state start, the startup time of the unit is shortened, the amount of fuel in the start is reduced, and the economy is improved. When the hot and hot states start, the temperature matching and stress control are reasonable, and the safety is more obvious.
Analysis of Start-up of Intermediate Pressure Cylinder of 600MW Supercritical Unit Steam Turbine
The start-up of a steam turbine should be steadily ramped up with a load within a reasonable range of life losses to prevent abnormal conditions such as overexpansion of expansion, cylinder temperature difference overshoot, dynamic and static part friction, shaft vibration, etc., without compromising host safety and auxiliary equipment. In the case of abnormal operation of the thermal control device, the start-up time is minimized and the start-up consumption is reduced to obtain the best safety and economic benefits. The traditional high and medium pressure cylinder joint start-up method is due to the low exhaust temperature of the high pressure cylinder during the start-up phase, the low temperature of the reheat steam, the slow temperature increase of the medium pressure and medium pressure rotors, and the slow expansion of the cylinder, and even the possibility of medium pressure The turbine rotor speed has been set when the cylinder rotor temperature has not exceeded the brittle transition temperature of the metal, thus limiting the start-up speed. Medium pressure cylinder start can well meet the above requirements, medium pressure cylinder start is a large capacity high-parameter condensing steam turbine generator unit with an intermediate reheat, the high pressure cylinder does not enter steam or only a small amount of steam, with The medium pressure regulating valve inlet steam rushes, and after the standby group has a certain load, it switches to the conventional high-medium pressure combined steam inlet mode and continues to carry the load until full load.