Pump is the use of additional energy delivery liquid or liquid-solid two-phase flow of fluid machinery. In the air pollution control projects often used. Such as wet desulfurization project, wet dust project, gas - water heat exchanger cooling water cycle.
1. Pump classification
Many types of pumps, centrifugal pumps, reciprocating pumps, rotary pumps, jet pumps and so on. In the air pollution control project is the main use of centrifugal pumps . Commonly used are: water pump, pump, mud pump, sand pump, corrosion-resistant pump (acid, lye pump) and so on.
2. Centrifugal pump performance parameters
Flow: pumping unit per unit time or the volume of liquid tunnel, the general proposed by the process.
Head: the unit volume of liquid delivered by the pump to the outlet to increase the value of energy. General use m liquid column said. Head calculation is an important basis for pump selection, pipe network system by laying, installation and operating conditions. Calculate the process sketch before drawing, plan and vertical layout
Pipeline length, pipe diameter and pipe type and quantity, the final calculation of system resistance.
3. Pump selection methods and procedures
① list the basic data
a. Physical properties of the medium: the name of the medium, the specific gravity under the conveying conditions, viscosity, corrosion and the like.
b. The medium contains the solid particle size and content.
c. Operating conditions: temperature; pressure (inlet side equipment pressure, discharge side equipment pressure, discharge side piping pressure drop); flow (normal, minimum and maximum).
d. Pump location: ambient temperature; altitude; pipeline level, elevation requirements; inlet and discharge side of the device to pump center distance and pipeline equivalent length and so on.
② determine the flow and lift
a. Flow rate: pump should be considered when the maximum flow rate; if only given the normal flow rate, the device and the process should be based on the specific circumstances of 1.1 safety factor. The above refers to the volume flow.
b. Head (or pressure): According to the pump layout, using Bernoulli equation to find the pump head.
③ select the pump and pump specific models
According to the characteristics of the media, has been identified the flow, head, and the selection of principles and the working range of the pump to choose the right type of pump. Then select the pump specific model number from the pump manufacturer's catalog and instructions and list the model and water-based performance parameters (flow, head or pressure differential, efficiency, critical suction vacuum level, or critical cavitation allowance ).
④ calculate the performance of the pump
According to the actual performance of the pump performance. The listed performance parameters are listed, if the process requirements are met, the selected pump is available. If necessary, draw the calculated performance curve and piping system performance curve to determine the pump operating point.
⑤ determine the geometry of the pump installation height
⑥ calculate the pump shaft power
⑦ selected pump material and shaft seal
⑧ determine the cooling water (or heating steam) consumption
⑨ selection of motor
⑩ to determine the pump standby rate and the number of units
Centrifugal pumps in parallel and in series
① parallel
In the project, when there is a big change in the flow rate requirements, that is, in a certain period of time required to reduce or increase the flow; or a pump can not meet the flow requirements, you can use two or more pumps to work in parallel. When the pump is working in parallel, the flow rate is less than the sum of the flow rates when the pumps are operated individually. The steeper the pipe resistance curve (ie, the greater the pipe resistance), the more the flow decreases in parallel operation.
② series
In the project, when using a single pump, the flow has been able to meet, and head less than the predetermined requirements or the original equipment can not be used, require the switch to higher lift system, you can use two or more pumps Series to achieve the desired lift. But pay attention to the pump in series, the pump body strength can meet, in order to ensure safety.
In order to give full play to the efficiency of a single pump, regardless of series, parallel work, should adopt the same specifications of the pump.
Centrifugal pump installation and operation
Pump installation and operation have certain requirements.
Hexagon Nipple,Black Hexagon Nipple,Hose Nipple
Ball Valves,Butterfly Valves,Check Valves Co., Ltd. , http://www.nspressfittings.com
没有评论:
发表评论