JPH0355720B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Field of Industrial Application This invention relates to a method of manufacturing a dendritic piping network, such as a dust collection piping network, which provides a desired constant flow rate to the fluid in each branch pipe. (b) Conventional technology When determining the capacity and suction pressure of a fluid suction device such as a fan in the production of conventional dust collection piping networks, etc.
First, assuming a desired standard flow rate, the pipe diameter of each branch pipe is determined based on the required amount of suction fluid from each suction branch pipe. The diameter of the pipe downstream of the merging section is determined on the assumption that the mixed fluid from the two merging pipes flows at the desired standard flow rate. Then, roughly calculate the fluid resistance for each line from the suction port to the discharge port, select one or several lines that are thought to have the maximum pressure loss, calculate the pressure loss, and calculate the maximum pressure loss. The required suction pressure of the fluid suction device is determined by the value, and the capacity of the suction device is determined by the sum of the required suction amount of each suction port. It was customary to install a partition damper. (A study of dendritic dust collection piping design method: Yasuhiro Hayashi: Pollution and Countermeasures VOL18 No. 4, P392-P394) (c) Problems to be solved by the invention However, actual equipment manufactured according to this manufacturing procedure During operation, the operator opens and closes the damper installed in each suction branch pipe to control the fluid flow rate while checking the suction situation at each suction point, but this operation requires considerable effort. It requires skill, and opening and closing the damper of one suction port changes the suction situation of other suction ports, so it is difficult to adjust as desired, especially when there are many suction ports and there are 10 to several dozen locations. It becomes almost impossible to maintain the desired standard flow rate at the time, causing various troubles. In addition, since the shape of the damper for controlling the flow rate is not symmetrical with respect to the center of the pipe, the fluid at the position of the damper is in a state of uneven flow with respect to the center axis of the pipe, which causes wear of the pipe and the damper itself. For example, if we take a dust collection piping network as an example, areas where the flow rate is slow will cause poor suction at the suction port due to dust accumulation, and areas where the flow rate is high will cause wear on the pipe walls and damper itself, which requires constant cleaning. Repairs will be repeated. This consumes a large amount of maintenance costs and time. The present invention provides a piping network in which the flow velocity of each branch pipe always maintains a desired constant value without requiring the operator's skill, and which does not cause various troubles due to unintentional imbalance of flow velocity as in the past. The purpose is to (d) Means for Solving the Problems An example in which the present invention is applied to a dust collection piping network will be described as follows. FIG. 1 is a piping system diagram of the dust collection piping network. As shown in the figure, Si, Sj, Sk, and Sl indicate the suction ports for dust-containing air, respectively. Symbols ○A, ○B, and ○C indicate the confluence of each branch pipe of the piping network, and, respectively. A, B, and C indicate a dust collector, fan, and chimney, respectively. , , indicates the position of the resistor attached to each suction branch pipe. d indicates the diameter of each branch pipe.
Also qi, ti, pi, pi, tj, pj, qk, tk, pk and ql,
tl and pl are the amount of suction gas (m ³ /
m, temperature °C, pressure mmAq. Further, FIGS. 2 and 4 show the shape of the resistor in the embodiment. 6th
The figure shows an example in which a resistor is provided to the suction branch pipe in the embodiment. In Fig. 1, when fluid flows through each branch pipe at a set flow rate, in order to equalize the static pressure of the fluid from both branch pipes merging at each merging point, each of , , , A resistor having a certain shape and dimensions calculated by the following procedure is attached to the position. The shape and dimensions of the resistor and the specifications of the suction machine are determined as follows. That is, (a) the state quantities qi, ti, pi, of the dust-containing gas at each suction port Si, Sj, Sk, and Sl of each suction branch pipe;
First, determine the pipe diameter d of each suction branch pipe based on the suction dust-containing gas amount, temperature, pressure, and desired set flow rate values of qj, tj, pj, qk, tk, pk, ql, tl, and pl. The pipe diameter of the downstream branch pipe that joins the suction branch pipe is determined based on the state quantity and the desired set flow rate value for the joined mixed fluid. (b) Next, by calculating the fluid resistance of the pipe, we first calculate the static pressure at the confluence part ○a of the most advanced suction branch pipe when the fluid flows at the set flow rate in the suction branch pipe in the above-mentioned suction state, and the amount of water that flows there. Find the static pressure when flowing at the same set velocity in the suction branch pipe, calculate the differential pressure, and record the differential pressure as a plus in the suction branch pipe with the higher static pressure. (c) Next, at the downstream confluence part ○B of the branch pipe downstream of the confluence point ○A of the suction branch pipe, calculate the value of the lower static pressure that you want to find at the confluence part ○B. , find the static pressure at that point ○○ from the pressure loss of the downstream branch pipe (the pressure loss of the branch pipe is found from the state of the mixed fluid that has joined from the suction branch pipe, the desired set flow rate, and the pipe diameter), and separately at that point. Find the static pressure at that point ○B from the fluid in the suction state, the desired set flow rate, and the pipe diameter from the other suction branch pipe that joins ○B, calculate the differential pressure, and use the one with the higher static pressure. Account for each suction branch pipe on the branch pipe side as a plus. (d) Gradually proceed with the calculation downstream in this way until you reach the most downstream confluence point ○c. (e) Furthermore, based on the lower static pressure of both branch pipes at the most downstream confluence point ○c, taking into account the pressure loss of the straight pipe section, dust collector, chimney, etc. on the downstream side, and the most downstream Calculate the suction wind pressure and air volume of the fan based on the air volume at the confluence part ○C. (f) At each branch pipe merging point, add up the value counted as the plus of the calculated differential pressure for each suction branch pipe. (g) Equal to the magnitude of each of the above integrated pressures when fluid flows at the desired set flow rate in each suction branch pipe,
Each resistor (second
Figure 4) is determined. ，，
, should be located at a location convenient for installation to the suction branch pipe and maintenance. (e) Effects Therefore, when operating the fan, if the fluids from the branch pipes that merge at each junction flow at the desired set flow rate, the static pressures will be equal to each other and an equilibrium state will be reached. Therefore, the flow rate in each branch pipe will flow at the desired constant flow rate of the set value. (F) Embodiment FIGS. 3 and 5 show resistors in other embodiments. When using an aperture mechanism as a resistor, the desired set flow rate,
Determined using a known relational expression between the pipe diameter, opening ratio, fluid density, (Re), etc., and the integrated pressure (pressure loss). An example of determining the aperture ratio when a pipe orifice of the type shown in FIG. 2 is used as a resistor will be described below with reference to FIG. 1.
Now, the suction fluid in each suction branch pipe is at room temperature and atmospheric pressure (Hmm
Ag) air. Assume that the pressure loss when fluid flows through each branch at a set flow rate is as follows. Suction branch pipe h1 mmAg 〃 h2 〃 〃 h4 〃 〃 h6 〃 Branch pipe h3 〃 〃 h3 〃 However, h2＜h1＜h4＜h3＜h5＜h6＜(h1＋h3＋h5)
shall be. Differential pressure at confluence part ○A (H-h2) - (H-h1) = (h1-h2) mmAg Differential pressure at confluence part ○B (H-h4) - {(H-h1) - h3 } = (h1 + h3 - h4) mmAg Differential pressure at confluence part ○ C (H - h6) - {(H - h1) - h3 - h5} = {h1 + h3 + h5) - h6} mmAg Accounted for each suction branch pipe Differential pressure suction branch pipe △p1=0 Suction branch pipe △p2=(h1-h2) mmAg Suction branch pipe △p4=(h1+h3-h4) mmAg Suction branch pipe △p6={(h1+h3+h5)-h6}mmAg Pipe orifice To determine the aperture ratio (S ₀ /S), the coefficient D is calculated using the following equation, and the aperture ratio is determined by interpolation and extrapolation from a relationship chart between the coefficient D and the aperture ratio. (Note 1) D=△p/u ² ρ/2gc △p; Differential pressure recorded in each suction branch pipe above (△p2,
△p4, △p6); Set flow rate m/s ρ; Air density Kg/m ³ gc; Gravity unit conversion factor, Kg・m/Kg・s ²

[Table] After determining the opening ratio S ₀ /S, the pipe diameter d of the suction branch pipe
The hole diameter d ₀ of the tube orifice is determined by the following formula. d ₀ = d×√ ₀ Using the above as a specific example, the dendritic piping network shown in FIG. 1 will be described in the case where the handled fluid is air at room temperature and atmospheric pressure (15° C., H ₀ mmAg). (1) Desired flow velocity is 15 m/s for all branch pipes. (2) The amount of suction air Q at the suction ports Si, Sj, Sk, and Sl is 40m ³ /m, 30m ³ /m, and 20m ³ /m, respectively.
10m ³ /m. (3) Calculate the pressure loss when fluid flows through each branch pipe at the desired set flow rate of 15 m/S. The following describes how to determine the dimensions of the resistor attached to each suction branch pipe under the following conditions. Note that changes in volume due to air pressure and temperature fluctuations are omitted. 1 Determination of pipe diameter Suction branch pipe 〃 〃 〃 2 Static pressure and differential pressure at each confluence point ○ Point A: Static pressure from the suction branch pipe. (H ₀ −50) mm
Ag Static pressure from the suction branch pipe (H ₀ -40) mmAg Differential pressure (H ₀ -40) - (H ₀ -50) = 10 mmAg ○ Point B; Static pressure from the branch pipe {(H ₀ -50) - 60}=
(H ₀ −110) mmAg Static pressure from the suction branch pipe (H ₀ −50) mmAg Differential pressure (H ₀ −50) − (H ₀ −110) = 60 mmAg ○ Point C; Static pressure from the branch pipe (H ₀ −110) −80=
(H ₀ −190) mmAg Static pressure from suction branch pipe (H ₀ −100) mm
Ag Differential pressure (H ₀ -100) - (H ₀ -190) = 90mmAg 3 Differential pressure to be recorded in each suction branch pipe (△P) mmAg Suction branch pipe △P ₂ = 10mmAg 〃 △P ₄ = 60mmAg 〃 △ P ₆ = 90mmAg 〃 △P ₁ = 0mmAg 4 Determining the dimensions of the resistor (orifice) (1) Determining the coefficient D The above formula △P=D. ²・ρ/2gc, that is, D=
△P×2gc/U ² .From ρ; 1.293×273/273+15=1.226Kg/m ³ 2.gc=9.8×2=19.6Kgm/Kg. S For ² suction branch pipes D ₂ =10×19.6/15 ² ×1.226≒0.71 For suction branch pipes D ₄ =60×19.6/15 ² ×1.226≒4.26 For suction branch pipes D ₆ =90×19.6/ 15 ² ×1.226≒6.39 For the suction branch pipe D ₁ = 0 (2) Determination of the orifice opening ratio (S ₀ /S) From the relationship chart between the coefficient D and the opening ratio shown above (P12), the orifice of the suction branch pipe Aperture ratio S ₀ /S=
0.73 Orifice opening ratio of suction branch pipe S ₀ /S=
0.50 Orifice opening ratio of suction branch pipe S ₀ /S=
0.44 Orifice opening ratio of suction branch pipe S ₀ /S=
1.00 (3) Dimensions of orifice attached to suction branch pipe Orifice of suction branch pipe Outer diameter d20 = 0.21mφ Suction branch pipe orifice outer diameter d40 = 0.17mφ Suction branch pipe orifice outer diameter d60 = 0.12mφ No orifice is required for the suction branch pipe.If the orifice is narrowed and installed at the pipe flange, it goes without saying that the outer diameter must be increased by the narrowing allowance. Note 1: See Chemical Engineering Handbook, 3rd edition, p.110. (g) Effects (i) Original technical effects Therefore, by setting this flow rate to a standard flow rate that does not cause dust accumulation and does not cause pipe wall wear, it is possible to avoid the problems that occur in the past. It is possible to obtain a piping network that flows at a constant desired set flow rate without any problems. In addition, from the viewpoint of preventing wear on the resistor and the tube, the shape of the resistor is preferably symmetrical to the central axis of the attached tube, and the resistor in the example is symmetrical to the central axis of the tube, which prevents wear. Maintains constant loss pressure for a long time. Incidentally, the resistor shown in FIGS. 2 and 4 has the effect of smoothing out the excess current generated behind the resistor. In addition, the resistor shown in FIGS. 3 and 5 has the advantage that it can be made in a simple shape and at low cost in actual use. (ii) Economic effects Effects include savings in maintenance and repair costs, reduction in downtime for mechanical equipment, and reduction in machine wear as conventional problems are resolved. (iii) Environmental and hygienic effects Contributes to environmental sanitation both inside and outside the factory and to prevention of industrial accidents.

[Brief explanation of drawings]

The figures show an embodiment of a dust collecting piping network according to the present invention, and FIG. 1 is a piping system diagram, and FIGS. 2 and 3 show an example of a resistor provided to a suction branch pipe. Fourth
FIG. 5 is a central sectional view of FIG. 2 and FIG. 3, respectively. FIG. 6 is an example of a suction branch pipe provided with a resistor. A: Dust collector, B: Fan, C: Chimney, ○I, ○B,
○C; Branch pipe confluence, Si, Sj, Sk, Sl; Suction port,,
,,,,,; Branch pipe, ,,,
; Suction branch pipe, di, dj, dk, dl, da, db, dc,
dd, de; pipe diameter, ,,; each suction branch pipe,
, , resistors attached to , qi, qj, qk, ql;
Suction air volume at each Si, Sj, Sk, and Sl suction ports
m ³ /m, ti, tj, tk, tl; Air temperature near the inlet of each Si, Sj, Sk, Sl ℃, pi, pj, pk,
pl: Air pressure near the suction port of each Si, Sj, Sk, Sl, mmAq, 1: Suction branch pipe, 2: Bolt nut,
3; Resistor.

Claims (1)

[Scope of Claims] 1. In a dendritic piping network with a suction device and other accessories such as in a dust collection piping network system, each suction branch pipe, . By providing resistors each having a certain shape and size, when the fluid flows through each branch pipe at a desired constant flow rate, each of the confluence points ○A, ○B, and ○C of the branch pipe , both branch pipes that join there,
A method for manufacturing a dendritic piping network that maintains the flow velocity in the pipe at a desired constant value, characterized by equalizing the static pressure of the fluid from and. , , , should be located at a location that is convenient for installation to the suction branch pipe and for maintenance. 2. The method of manufacturing a dendritic piping network according to claim 1, wherein the resistor has an orifice shape determined by the following calculation procedure. (a) State quantities qi, ti, pi, qj of each fluid at each suction port Si, Sj, Sk, Sl of each suction branch pipe,
Suction gas amount of tj, pj, qk, tk, pk, ql, tl, pl.
temperature. Based on the pressure and desired set flow rate values, first determine the pipe diameter d of each suction branch pipe, and the pipe diameter of the downstream branch pipe that merges from the suction branch pipe is determined by the above-mentioned value for the combined mixed fluid. The pipe diameter is determined based on the state quantity and the desired set flow rate. (b) Next, by calculating the fluid resistance of the pipe, first, we calculate the static pressure when the fluid flows at the set flow rate in the suction branch pipe in the above-mentioned suction state at the confluence part ○A of the most advanced suction branch pipe, and the other fluids that merge there. Find the static pressure when flowing at the same set velocity in the suction branch pipe, calculate the differential pressure, and record the differential pressure as a plus in the suction branch pipe with the higher static pressure. (c) Next, at the downstream confluence point ○B of the branch pipe on the downstream side of the confluence point ○A of the suction branch pipe, the value of the lower static pressure obtained at the confluence point ○A and the downstream branch From the pressure loss of the pipe, find the static pressure at that point ○○, and separately from the fluid in the suction state from the other suction branch pipe that joins that point ○○ and the desired set flow rate and pipe diameter, calculate the static pressure at that point. ○ Find the static pressure at B, calculate the differential pressure, and record it as a plus for each suction branch pipe on the side of the branch pipe with the higher static pressure. (d) Gradually proceed with the calculation downstream in this way until you reach the most downstream confluence point ○c. (e) Furthermore, based on the lower static pressure of both branch pipes at the most downstream confluence point ○c, taking into account the pressure loss of the straight pipe section, dust collector, chimney, etc. on the downstream side, and the lowest static pressure, Calculate the suction wind pressure and air volume of the suction machine based on the air volume at the downstream confluence part ○C. (f) At the junction of each branch pipe, the value counted as the plus of the calculated differential pressure is accumulated for each suction branch pipe. (g) When fluid flows through each suction branch pipe at the desired set flow rate, find the shape and dimensions of the resistor that exhibits a constant loss pressure equal to the magnitude of each integrated pressure above. 3. The method of manufacturing a dendritic piping network according to claim 1, wherein the shape and dimensions of the resistor are determined by the calculation procedure described in item 2 above, and a disk-shaped resistor having a hole in the center is provided.