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渣漿泵串聯(lián)的解析法
設(shè)兩臺(tái)離心泵串聯(lián)工作，分別由兩臺(tái)泵實(shí)測(cè)或泵特性曲線上取點(diǎn)得到幾組揚(yáng)程.流量數(shù)據(jù).用最小二乘祛回歸得到泵的特性方程分別為:
式中的系數(shù)a1、b1、a2、b2可由式(1 - 69)計(jì)算得到。
按照兩泵串聯(lián)后的總揚(yáng)程等于兩泵在同一流量時(shí)的揚(yáng)程之和，即Q=Ql=Qll時(shí)Hl+ll= Hl+ Hll的原則，有:則兩臺(tái)相同泵串聯(lián)后的特性方程為:
H=A-BQ2
將其與管路特性方程聯(lián)立，即可解得系統(tǒng)工作點(diǎn)。多臺(tái)離心泵串聯(lián)工作也可按此原則進(jìn)行計(jì)算。
3.復(fù)雜管路系統(tǒng)工作點(diǎn)的確定
對(duì)于復(fù)雜管路系統(tǒng)來(lái)說(shuō)，根據(jù)水力特點(diǎn)，并聯(lián)時(shí)管路交叉點(diǎn)的壓力相等，總流量等于各支管流量之和；串聯(lián)時(shí)各管段流量相等，總摩阻等于各管段摩阻之和進(jìn)行疊加。對(duì)于交匯及分支管路系統(tǒng)，求解過(guò)程如下。
1) 泵在分支管路上工作的裝置特性
經(jīng)過(guò)一臺(tái)泵(或幾臺(tái)泵申聯(lián)、并聯(lián))將油品同時(shí)輸往一處或幾處時(shí)，要采取分支管路來(lái)工作，如圖1- 48(a)所示。油品由管1經(jīng)過(guò)泵后再沿管2和管3分別輸送到兩油罐內(nèi)。三個(gè)油罐中液面對(duì)于泵軸線的標(biāo)高差為z1、z2和z3。
(1) 圖解法。
畫(huà)出吸入管路特性(h-Q)1以及排出管路的特性(h-Q)2和(h-Q)3。因管2和管3是并聯(lián)工作,需按并聯(lián)相加得管路特性(h-Q)2+3。然后再和(h-Q)1串聯(lián)相加，得到整個(gè)管路系統(tǒng)的總管路特性(h-Q)at ,它和泵的性能曲線H-Q相交于M點(diǎn)，即為分支管路的工作點(diǎn)。
M點(diǎn)相應(yīng)的流量Qw就是管1中的流量Q。為確定管2和管3中的流量，過(guò)M點(diǎn)作垂線與管路特性(h-Q)2+3相交于A點(diǎn),從A點(diǎn)引水平線與(h Q)2相交于點(diǎn)2，與(h-Q)3相交于點(diǎn)3，則點(diǎn)2和點(diǎn)3相應(yīng)的流量Q2和Q3即為管2和管3中的流量,并且Qm=Qa=Q2+Q3=Q1。
(2) 解析法。
由泵實(shí)測(cè)或泵特性曲線上取點(diǎn)得到幾組揚(yáng)程、流量數(shù)據(jù),用最小二乘法回歸得到泵的特性方程為H=a-bQ2，系數(shù)a、b可由式(1- 69)計(jì)算得到。
管路1的特性方程為:
管路2的特性方程為:
h2=z2+k2Q2
管路3的特性方程為:
h3=z3+k3Q3
管路2和管路3先并聯(lián)然后與管路1串聯(lián)，根據(jù)管道并聯(lián)原則有:
h2=h3, Q=Q1=Q2 + Q3
管路總特性為:
h=h1 +h2或h=h1 + h3
對(duì)于系統(tǒng)來(lái)說(shuō):
h= H,Q1 =Q渣漿泵廠家
解方程組即可求得Q1、Q2、Q3。
Analytical method of slurry pump in series
Two centrifugal pumps are designed to work in series, and several groups of head and flow data are obtained from the measured data of two pumps or the points on the pump characteristic curve. The characteristic equations of pumps are obtained by least square regression
The coefficients A1, B1, A2 and B2 in the formula can be calculated by formula (1-69).
According to the principle that the total head of two pumps in series is equal to the sum of the heads of two pumps at the same flow, that is, when q = QL = QLL, HL + ll = HL + HL, the characteristic equation of two pumps in series is as follows:
H=A-BQ2
The working point of the system can be obtained by combining it with the characteristic equation of pipeline. Several centrifugal pumps in series can also be calculated according to this principle.
3. Determination of working point of complex pipeline system
For the complex pipeline system, according to the hydraulic characteristics, the pressure at the crossing point of the pipeline is equal in parallel, and the total flow is equal to the sum of the flow of each branch pipe; the flow of each pipe section is equal in series, and the total friction is equal to the sum of the friction of each pipe section for superposition. For the intersection and branch pipeline system, the solution process is as follows.
1) Device characteristics of pump working on branch pipeline
When oil products are transported to one or several places at the same time through one pump (or several pumps applying for connection or parallel connection), branch pipeline shall be adopted for operation, as shown in Fig. 1-48 (a). The oil is pumped by tube 1 and then transported to two oil tanks along tube 2 and tube 3 respectively. The elevation difference of the three oil tanks to the pump axis is Z1, Z2 and Z3.
(1) Graphic method.
Draw the characteristics of suction line (H-Q) 1 and discharge line (H-Q) 2 and (H-Q) 3. Because tube 2 and tube 3 work in parallel, it is necessary to add the characteristics (H-Q) 2 + 3 in parallel. Then add (H-Q) 1 in series to get the total pipeline characteristic (H-Q) at of the whole pipeline system. It intersects the performance curve H-Q of the pump at point m, which is the working point of the branch pipeline.
The corresponding flow QW at point m is the flow Q in tube 1. In order to determine the flow in pipe 2 and pipe 3, make a vertical line through point m to intersect with the pipeline characteristic (H-Q) 2 + 3 at point a, lead the horizontal line from point a to intersect with (H q) 2 at point 2, and intersect with (H-Q) 3 at point 3, then the corresponding flow Q2 and Q3 at point 2 and point 3 are the flow in pipe 2 and pipe 3, and QM = QA = Q2 + Q3 = Q1.
(2) Analytical method.
Several groups of head and flow data are obtained from the measured pump or the points on the pump characteristic curve. The characteristic equation of the pump is h = a-bq2 by least square regression. The coefficients a and B can be calculated by formula (1-69).
The characteristic equation of pipeline 1 is as follows:
The characteristic equation of pipeline 2 is:
H2=z2+k2Q2
The characteristic equation of pipeline 3 is as follows:
H3=z3+k3Q3
Pipeline 2 and pipeline 3 are connected in parallel and then in series with pipeline 1. According to the principle of pipeline parallel connection, they are as follows:
h2=h3, Q=Q1=Q2 + Q3
The general characteristics of the pipeline are:
H = H1 + H2 or H = H1 + H3
For the system:
H = h, Q1 = q slurry pump manufacturer
Q1, Q2 and Q3 can be obtained by solving the equations.
