Selection of parameters for tubular turbine of Zhi

Jinyintai hydropower station is located in Hexi Town, Langzhong City, Sichuan Province. It is the third step from top to bottom in the hydropower planning of the Cangxi Hechuan section of the Jialing River. The maximum head is 15.66m, the minimum head in flood season is 3M, and the installed capacity is 99mw. According to the application scope of water turbine runner divided by China's "provisional series type spectrum of large and medium-sized water turbine runner", the power station belongs to the water head section below 20m, and both axial-flow and tubular models can be selected. However, for low head runoff power stations, bulb tubular units have the following advantages compared with axial-flow units: the NS value of the optimal working condition of the unit is higher; The excavation depth of the bottom plate is small; Large unit flow and high unit speed; The efficiency of the unit is high and the range of high efficiency area is large; The minimum operating head is low; The unit is light in weight and small in size; Save civil engineering quantities. At present, it has become the mainstream to select tubular turbines for water head sections below 20m

in the design process of the power station, through the technical and economic comparison between the axial flow type and the tubular type, the tubular type is selected. The following is a brief introduction to the parameters of the hydraulic turbine

2 selection of main parameters of hydraulic turbine

the main parameters of the power station are as follows: the maximum head is 15.66m, and the weighted average head is 132. The current situation and development trend of fixtures 93m, rated head 12.5m, minimum head 3.0m. The number of installed units is 3, and the unit capacity is 33MW

according to the basic parameters of the power station, the inquiry of hydro generator set expressed by Canadian cm consulting company in its report entitled "recycling and regeneration of plastic shopping bags and other PE films" was sent to four manufacturers, Dongfang Electric Machinery Co., Ltd., Harbin Electric Machinery Co., Ltd., Tianjin Alstom hydropower equipment Co., Ltd. and Fuchunjiang Fuji Electric Machinery Co., Ltd. The above four manufacturers recommended the turbine models and runner parameters applicable to Jinyintai power station in their reply, as shown in Table 1 and table 2

therefore, due to the large differences in unit parameters recommended by various manufacturers, in order to determine reasonable bulb unit parameters, a series of bulb unit parameters that have been produced are statistically analyzed. Combined with the data in the re inquiry of various manufacturers, the formula recommended at home and abroad is used for calculation to determine NS, q '1, n' 1 η、σ Etc

2.1 determination of specific speed ns and specific speed coefficient K

specific speed is a basic characteristic parameter of hydraulic turbine, which comprehensively reflects the energy, cavitation, efficiency and other characteristics of hydraulic turbine, as well as the design and manufacturing level of hydraulic turbine. According to the statistics in Table 3, the NS value of bulb units above 20000 kW that have been put into operation and under construction in China recently is between 750 ~ 1087m · kW, and most of the rated water heads of 10m and above are near 800m · kW; K values are between 2600 and 3100

secondly, according to different statistical formulas 4. The spring tension and compression testing machine should pay attention to keeping the jaw of the fixture or the relatively sliding surface clean to avoid collision The debris left in the jaw should be cleared in time for analysis and calculation:

the domestic recommended statistical formula is ns = (2500 ~ 3100) HR － 0.5,

considering the large amount of sediment in the power station, the average sediment concentration over the years is 2.57kg/m3, and the average sediment concentration through the machine in flood season is 3.25kg/m3. Due to the large capacity of the bulb unit, the turbine and generator should not choose too large specific speed and specific speed coefficient. At the same time, larger ns will cause σ The value of Y is relatively large, which leads to the deep excavation of the machine pit and increases the civil engineering investment. NS is about 780m · kW, and K is about 2760

2.2 unit flow and runner diameter

according to the formula, NS and N ′ 1, Q ′ 1 η of In order to reduce the runner diameter, the value of Q ′ 1 should be increased, but a larger value of Q ′ 1 will cause σ The value of Y is large, which leads to large excavation volume and civil engineering investment. From the parameters of bulb units with a unit flow of more than 20000 kW that have been put into operation or are under construction in China recently (see Table 3), it can be seen that Q '1 is generally between 2.2 ~ 3.2m3/s. if the design head of the power station is high, the corresponding Q' 1 is small. Below, Q ′ 1 is estimated and analyzed according to different empirical formulas

according to the statistical curve of Swedish KMW company, when HR = 12.5m, Q ′ 1 = 2.333m3/S; 2.3 selection of unit speed and unit speed

analyze and calculate n '1 according to empirical formula

as mentioned above, according to the domestic recommended statistical formula n ′ 1 = [(620 ~ 650) - 10 hr]/3, n ′ 1 = 165 ~ 175r/min

according to the Swedish KMW formula, n ′ 1 = - 3.33 HR + 215, get n ′ 1 = 173r/min

according to the statistical formula of tianchuansuo, n ′ 1 = 0.1ns + 92 = 170r/min