渣浆泵的性能参数
1.流量
渣浆泵的理论流量(Qt)与活塞直径、行程和往复运动次数有关,与推出压力无关
单作用渣浆泵的理论流量按式(2- 1)计算
Qt=Asn/60
式中 A---活塞截面积,m;
s----活塞行程,m;
n---往复泵的转速.次/min。
双作用往复活塞泵的理论流量按式(2-2)计算:
Qt=(2A-a)sn/60
式中a---活塞杆的截面积,m2.
往复泵的实际平均流量比理论要小,即,
Q= ηvQτ
式中ηv---容积效率,主要是由于阀门开 、团滞后,阀门、活塞填料函泄漏所造成的,ηv由实
验测定。
渣浆泵的瞬时流量取决于活塞截面积与活塞瞬时运动速度之积,由于活塞运动瞬时速度的不断变化,使得它的流量不均匀。实际生产中,为了提高流量的均勾性可以采用增设空气室,利用空气的压缩和膨胀来存放排出部分液体,从而提高流量的均句性。采用多缸泵也是提高流量均匀性的一个方法.多缸泵的瞬时流量等于同一瞬时各缸流量之和,只要各缸曲柄相对位置适当,就可使流量较为均匀。
2.扬程
和离心泵一样往复活塞泵的扬程也是泵加给单位质量液体的能量,称为往复活塞泵的扬程或压头,其计算公式为:
因为是靠挤压作用压出液体,往复活塞泵的扬程可以任意高,与流量无关。但实际上由于构造材料的强度有限,泵内的部件有泄漏,故往复泵的扬程仍有一限度,而且扬程太大,也会使电动机或传动机构负载过大而损坏。
往复活塞泵的排液能力与活塞位移有关,但与管路情况无关:而扬经则受管路的系压能力限制。这种性质称为正位移特性,具有这种特性的须统称为正位移菜,正位移采的流量不能用出口阀门来调节。
3. 功率和效率
渣浆泵的有效功率Pe为:
Performance parameters of slurry pump
1. Flow
The theoretical flow rate (QT) of slurry pump is related to piston diameter, stroke and reciprocating times, but not to push out pressure
The theoretical flow rate of single acting slurry pump is calculated according to formula (2-1)
Qt=Asn/60
Where a is the cross-sectional area of piston, m;
S --- piston stroke, m;
--- speed of reciprocating pump.
The theoretical flow of double acting reciprocating piston pump is calculated according to formula (2-2)
Qt=(2A-a)sn/60
Where a - cross sectional area of piston rod, M2
The actual average flow rate of reciprocating pump is smaller than the theoretical value,
Q= ηvQτ
In the formula, η V --- volumetric efficiency, which is mainly caused by the lag of valve opening and closing, and the leakage of valve and piston stuffing box
The results were compared with those of the control group.
The instantaneous flow of slurry pump depends on the product of piston cross-sectional area and piston instantaneous velocity. Because of the constant change of piston instantaneous velocity, its flow is not uniform. In actual production, in order to improve the flow uniformity, we can add an air chamber, and use the compression and expansion of air to store the discharged liquid, so as to improve the flow uniformity. The instantaneous flow of multi cylinder pump is equal to the sum of the same instantaneous flow of each cylinder. As long as the relative position of each cylinder crank is appropriate, the flow can be more uniform.
2. Lift
Like centrifugal pump, the head of reciprocating piston pump is also the energy added to the unit mass of liquid by the pump, which is called the head or pressure head of reciprocating piston pump
Because is presses out the liquid by the extrusion action, to the reactivation plug pump's lift may be arbitrarily high, has nothing to do with the flow. But in fact, due to the limited strength of structural materials, the components in the pump have leakage, so the head of reciprocating pump still has a limit, and if the head is too large, the motor or transmission mechanism will be damaged due to excessive load.
The discharge capacity of reciprocating piston pump is related to the displacement of piston, but has nothing to do with the condition of pipeline. This kind of property is called positive displacement characteristic, which must be called positive displacement characteristic. The flow rate of positive displacement can't be regulated by outlet valve.
3. Power and efficiency
The effective power PE of slurry pump is: