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Pump Selection And Modelling Calculation
- Feb 12, 2018 -

A pump is a fluid machine that transports liquid or liquid-solid two-phase flow with additional energy. Often used in air pollution control projects. such as Wet desulfurization project, wet dust Removal project, air-water heat exchanger cooling water cycle, etc.

1. Pump classification

Many kinds of pumps, there are centrifugal pumps, reciprocating pumps, rotary pumps, jet pumps and so on. The main use of the Air Pollution Control project is centrifugal pump. Commonly used are: clean water pumps, pumps, mud pumps, sand pump, corrosion-resistant pumps (acid, lye pump) and so on.

2. Centrifugal Pump Performance parameter

Flow: Unit time suction or the volume of the tunnel fluid, generally by the process proposed.

Lift: The amount of energy added by the pump to the outlet of the unit volume liquid. Usually expressed in m liquid column. The head calculation is the important basis of the pump selection, which is decided by the laying, installation and operating conditions of the pipe network system. Sketch, plane and vertical layout of the process before calculating

Pipeline length, diameter and pipe type and quantity, the final calculation of resistance.

3. Pump selection methods and procedures

① lists the underlying data

A. The physical property of the media: the name of the media, the proportion of the transport conditions, viscosity, corrosion and so on.

B. The medium contains solid particle size and content.

C. Operating conditions: temperature, pressure (inlet side equipment pressure, discharge side equipment pressure, discharge side pipe pressure drop), flow (normal, minimum and maximum).

D. The position of the pump: ambient temperature, altitude, pipeline level, elevation requirement, inlet and discharge side equipment liquid level to pump center distance and pipeline equivalent length etc.

② determine flow and lift

A. Flow: The pump should be selected according to the maximum flow considerations, if only the normal flow, should be based on the device and the specific conditions of the process to adopt 1.1 of the safety factor. The above refers to volume flow.

B. Lift (or pressure difference): According to the pump layout, using Bernoulli equation to find the pump head.

③ Select pump type and pump specific model

According to the characteristics of the media, the determined flow, lift, and the selection of the principle of the pump and the scope of work to select the appropriate type of pump. Then choose the specific model of the pump from the sample and specification of the pump manufacturer, and list the model as well as the performance parameters (flow, lift or pressure difference, efficiency, critical suction vacuum height or critical cavitation allowance) based on the water.

Performance of ④ Accounting pump

According to the actual situation of the pump performance accounting. List the calculated performance parameters, such as the selected pump is available if the process requirements are met. When necessary, the performance curve of the calculation and the performance curve of the piping system can be drawn to determine the working point of the pump.

⑤ Determine the geometry installation height of the pump

⑥ calculation of pump shaft power

⑦ selected pump material and shaft seal

⑧ determine the consumption of cooling water (or heating steam)

⑨ Selection of Motor

⑩ determine the standby rate and number of pumps

4. Centrifugal Pump Parallel and series

① Parallel

In the project, when the flow requirements have a greater change, that is, in a certain period of time to reduce or increase the flow, or a pump can not meet the flow requirements, can be used two pumps or multiple pumps parallel work. Pump parallel operation when the flow is less than the flow of each pump alone, and pipeline resistance curve steeper (that is, the greater the pipeline resistance), parallel operation, the more traffic.

② Series

In the project, when the use of a single pump, its flow has been able to meet, and the head can not reach the predetermined requirements or the original equipment can not be used, requirements for the higher head of the system, you can use two or more pumps series to achieve the required lift. However, we should pay attention to the pump series, the pump body strength can be satisfied to ensure safety.

In order to give full play to the efficiency of single pump, regardless of series, parallel work, it is advisable to use the same specifications of the pump.

5. Centrifugal Pump Installation and operation

Pump in the installation and operation of certain requirements.