The expected temperature range that needs to be dealt with during the operation of pumps is crucial for making the correct selection, not only involving the type and structural form of centrifugal pumps, but also the selection of pump components. Although temperature may seem like a familiar concept, in industrial applications, it can make operations more complicated or equipment less reliable.
During the pump selection process, both the ambient temperature on the site and the temperature of the pumped medium must be considered.
Impact on structural materials:
If the centrifugal pump is pumping certain chemicals, corrosion may occur due to temperature changes. Fluids that boil hot have a greater corrosive effect on materials than fluids at lower temperatures. Therefore, it is important to check the chemical compatibility at the pumped temperature.
At very low temperatures (-150℃ or below), many materials such as standard carbon steel become brittle, so special component materials must be used in systems that pump LNG or other low-temperature liquids. By adding certain elements or forging metals with certain grain structures, parts that can withstand even these extreme conditions can be produced.
For packing seals, as the temperature increases, heat is transmitted from the seal packing cover to the bearings through the shaft. This will significantly shorten the bearing life and may even cause the bearings to lock up.
Liquids that are affected by temperature will have their viscosity changed during the pumping process. For example, heating honey will make it thinner and change its pumping behavior. Therefore, understanding how temperature changes during the pumping process will affect product viscosity and ensure the correct pump (type and structure) is selected.
Metal components will expand at different rates at high temperatures. This is particularly important in the selection process of centrifugal pumps and will affect the structural materials you choose.
Insulation or keeping temperatures low:
In some cases, your application may require a certain temperature to be maintained. This can be achieved by maintaining flow conditions or using insulation jackets/overall insulation.
For example: When the medium temperature exceeds 160°C, a pump supported by the pump feet at the centerline is used; when the medium temperature exceeds 200°C, a radially split structure pump is used; when the medium temperature is around 400°C and the pump pressure is not too high, such as the tower bottom slurry pump in the petrochemical industry, OH2 pumps are usually used to minimize possible leakage points; when the medium temperature is around 400°C, and even though the pressure is not too high, but single-stage pumps or two-stage pumps cannot meet the requirements (such as the feed pump for the radiation furnace in the petrochemical industry), BB5 pumps are usually used to ensure safety; when transporting low-temperature media, it is recommended to use VS6 vertical barrel bag pumps for easy cold preservation; when the fluid viscosity is high at normal temperature, easy to solidify and crystallize, insulation jackets or overall heating/insulation should be designed for the pump; centrifugal pumps are usually not suitable if the viscosity of the pumped fluid is too high at the pumping temperature.
For example: when the centrifugal pump is used to pump a medium that is below zero and not too low, usually, low-temperature carbon steel or austenitic stainless steel materials are used; when the pumped medium is below zero and relatively low, usually, austenitic stainless steel materials are used; for high-temperature slurry with catalyst particles, OH2 pumps with lining and impeller made of wear-resistant cast iron material are selected; when the pumped medium is high-temperature slurry without catalyst particles, OH2 pumps with lining and impeller made of CA-6NM material are selected.
Mechanical seal and system selection
For example: at normal temperature, type A seals are usually chosen, with the maximum operating temperature reaching 176°C; at low temperatures, type B seals are usually chosen, with the maximum operating temperature 176°C; for high-temperature working conditions, type C seals are usually chosen, with the maximum operating temperature up to 400°C; for pumps with an operating temperature greater than or equal to the spontaneous combustion point of the pumped medium, arrangement methods 2 or 3 are usually selected; for high or low-temperature working conditions, PLAN62 seal flushing plan is usually required.