Pump Information and Detail

Pumping liquids is almost everywhere in the chemical and petrochemical processes. The many different materials require special attention are processed, the selection of materials for the construction of the various pump components, seals, and hydraulic system of the individual problems. A variety of pump types have been developed to meet the many specific conditions found in chemical plant systems, but can, as all these are not discussed here, the omission of some does not meanthat they may not be suitable for a service. In general, the final pump selection and performance data are recommended by the manufacturers, the conditions that meet the specified criteria, the process engineer. It is important that the designer of the process, the system offers completely familiar with the activities of each pump for a service, so that these objects can be properly as control instruments and valves in the full knowledge of the system are evaluated.

A pump is a physical deviceWhich is used to deliver fluids from one place to another through pipes. Over the years, numerous pump designs have evolved to respond to different demands.

Defining the basic requirements for the application to have suction and pressure, pressure loss in the transmission and the flow rate. Special requirements may be in food, are pharmaceutical, nuclear, and other industries, the selection of materials requirements of the pump to be imposed. The principal means of transmitting energy to the liquidCauses are that gravity flow, displacement, centrifugal force, electromagnetic force, the transfer of momentum, mechanical impulse and a combination of these energy transfer mechanisms. Gravity and centrifugal force are the most common energy-transfer process in action.

Pump designs are largely standardized. at the request of experience, have resulted in numerous standards. As special projects and develop new situations apply to pumps, these standards are updatedand revised. Common pump standards are:

1. American Petroleum Institute (API) Standard 610, Centrifugal Pumps for Refinery Service.
2. American Water Works Association (AWWA) E101, Deep Well Vertical Turbine Pumps.
3. Underwriters Laboratories (UL) UL 51, UL343, UL1081, UL448, UL1247.
4. National Fire Protection Agency (NFPA) NFPA-20 centrifugal pumps fire pumps.
5. American Society of Mechanical Engineers (ASME).
6. American National Standards Institute.
7. HydraulicStandards Institute (application).

In these standards, planning, construction, testing and details as the selection of materials, shop inspection and tests, drawings and other purposes required clearances, construction methods, and so on.

Are the most common types of pumps in a chemical plant uses centrifugal and positive displacement pumps. Occasionally regenerative turbine pumps, axial flow pumps and lifting stations used.
Modern practice is to use centrifugal positivelyDisplacement pumps where possible because they are generally less expensive, require less maintenance and less space. Conventional centrifugal pumps operate at speeds from 1200 to 8000 rpm. Very high-speed centrifugal pumps that can operate up to 23,000 rpm and higher, are used for low capacity, high head applications. Most centrifugal pumps will operate with a nearly constant head over a wide range of capacities.

Positive displacement pumps are either oscillating or rotating.Piston pumps are piston, piston and diaphragm types. Rotary lobe pumps are: single lobe, multiple lobe, rotary vane, eccentric screw pumps and gear. Positive displacement pumps operate with near-constant capacity over a wide divergence in the head, so they usually need for services that are installed, high capacity at moderate heads. A special application of small piston pumps in gas processing plants is the injection of liquids (eg methanol and corrosionInhibitor) in process streams, where their constant capacitance properties desirable.

Axial-flow pumps are available for certain services, which uses very high capacity at low heads.

Regenerative turbine pumps are used for services with limited capacity at high heads. Ejectors are used to the investment costs for the installation of a pump when a suitable motive fluid (often steam) is avoided, and are generally low-efficiency equipment. These types of pumps are rarely usedGas industry.

In order to fulfill it properly to a good and thorough ratinghizing a centrifugal pump would have to plant system designers to a minimum, follow these steps.

1. Understand the basics of performance of the pump itself.
2. Understand the details required for a mechanical pump to function properly in a system.
3. Calculate the friction and other pressure losses for each "side" of the pump suction and discharge.
4. Find the suction andPrint page headers for the mechanical system to connect to the pump.
5. Determine the most important available net positive suction head (NPSH) for the pump suction side of a mechanical system, and compare it with the manufacturer required net positive suction head (NPSH) by the pump itself, this requires that the designer a preliminary actual pump Selecting one or more manufacturers make to use the actual numbers.
6. Make necessary corrections permissible NPSH of the pump (withCharts, where) if applicable, and compare with the available NPSH. The available must always be several feet (mm) larger than the required corrections.
7. Make corrections to viscosity provided the required power when the liquid is thicker than water.
8. Study of specific speed index, in particular, if to assume that future changes in the system are needed.
9. When liquid is pumped) at elevated temperature (usually above 90 ° F (32.2o C), check the temperature risethe pump and the minimum flow through the pump is required.
10. Share pump brake power corrections for liquids with a specific gravity of different water. Select the relevant driver (electric motor, usually) PS PS-loss order that meet between the driver and the pump shaft is still an adequate performance of the pump at input shaft requirements.
11. If the pump has some unique service or specialty needs to recognize this in the final size and selection.Consult a reliable manufacturer that produces pumps for the type of service and applications, and they have to verify the analysis of the application of your system.

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