F Shaanxi Institute of Hydraulic Research I—the hydraulic gradient of the transport slurry, mm; B Calculate the flow cross section formula The round pipe is Q l =Aυl (37) W———solid weight in unit volume of pulp, kg/m 3 ; A———over flow area, m 2 ; Laser Marking Machine,Laser Marking System,Laser Marking Printer Machine,Fiber Laser Marking Machine Jinan Bodor CNC Machine Co., Ltd. , https://www.lasercuttings.nl
δ k , δ g , δ 0 ———The density of slurry, solid and water, t/m 3 .
The rest of the symbols are the same as before.
b Applicable conditions The applicable conditions of the formula of Shaanxi Institute of Hydraulic Research are: d 50 =0.07～0.21 mm, δ g =4.51-2.92 ton/ m3 , C V =0.487～39.4%, and the calculation result should be multiplied by the safety factor in practical application. The critical flow rate has a safety factor of 1.2 and the head loss has a safety factor of 1.3.
In recent years, some people have tried to deduce the full-concentration hydraulic calculation formula applicable to both high- and low-concentration slurry transport. However, the formulas confirmed by various aspects have not been found so far. The Saskatchewan Research Association of Canada has proposed an empirical formula for calculating unit head loss:
i m =A(D) B (31)
Where i m ———the hydraulic gradient of the slurry expressed by the water column, %;
D———pipe diameter, cm;
B——-the function of concentration;
A—function of average flow rate and slurry concentration.
In the formula, A and B are determined by experiments, and they will vary with the concentration of the slurry and the flow rate. The concentration adaptation range of this is wider than any of the above formulas, but this formula must be used in actual pipeline test results. Therefore, this formula is not an independent formula. In short, the full-concentration hydrometer type that people hope is currently being researched and verified has not yet appeared.
(2) The calculation of the hydraulic flow of the self-flow pipe and the trough self-flow pipe and trough is much simpler than the pressure transmission. First, the slurry is a Newtonian fluid; the calculated parameters are only overcurrent (determined by critical flow rate) and slope. At present, there are many calculation formulas for transportation at home and abroad. In China, BC Knoroz, A.П. Eugene, and Nienig are more commonly used, but most people think that the Nieig formula is more in line with objective reality. Select it as follows:
A Calculate the critical flow rate formula [next]
The rectangular groove is Q l =mH 2 l Ï… l (38)
C Calculate the slope formula. Straight line slope: J n =nJ s (39)
Slope at the turn:
S———the weight of water in a unit volume of pulp, kg/m 3 ;
H l ———critical water depth, m;
Β—the correction coefficient of the slurry flow rate;
m———the aspect ratio of the rectangular groove slope, m=2～4, the large flow rate takes a small value; the small flow rate takes a large value;
K———safety factor, generally 1.25;
J s —- hydraulic gradient when conveying critical flow of clean water, mm;