In addition to the main suction and discharge pipelines, there are many additional pipelines in the pipeline layout of the pump. Today we will talk about the routing strategies for the additional pump pipelines.
Empty and clean pipes
Vent: Except for the self-exhausting pump, all need to set up a venting pipeline for driving. In order to prevent air resistance, an operating venting pipeline should be set on the inlet pipeline; the venting of the vacuum system should be returned to the gas phase space of the suction equipment to transport liquefied petroleum. The gas pump should be equipped with a venting pipeline that discharges into the closed system on the pump inlet or outlet pipeline.
For material systems that need to be vented frequently during operations such as transporting asphalt, the venting pipeline should be returned to the suction equipment, and steam tracing should be provided.
Drain: The shell of the horizontal pump should be equipped with a drain valve. If the material between the inlet shut-off valve cannot be drained through the pump body, a drain valve should be provided on the pipeline, and a drain valve should be provided between the check valve and the shut-off valve on the outlet pipeline of the centrifugal pump.
Heat pump and anti-condensation pipeline:
If the temperature of the material conveyed by the centrifugal pump exceeds 200 °C, it is necessary to set up anti-condensation and heating pump pipelines, so that a small amount of material is drawn from the operating pump through the discharge pipeline and flows through the pump body of the standby pump, and then returned to the pump inlet, so that the standby pump is in a hot standby state. , to prevent the backup pump and the medium in the suction and discharge pipelines from solidifying, to ensure the warm pump and easy to start.
If the air temperature is lower than the freezing point of the material, a heating pump bypass is also required to prevent the material from freezing in the pump body. In addition, an anti-condensation bypass is required between the inlet and outlet of the pump, and the connection point between the pipeline and the main pipe should be as close to the shut-off valve as possible. , to prevent dead ends. Anti-condensation bypass with steam electric heat tracing.
Low Flow Protection Pipes:
If the centrifugal pump may run below the allowable minimum flow of the pump, a pump low-flow protection pipeline should be set up to make a part of the fluid return from the pump discharge port to the passenger container at the pump suction port. When the centrifugal pump operates below 20% of the rated flow in a short time, a limited flow orifice bypass should be installed (with a shut-off valve or a regulating valve): the total flow should be at least 20% of the rated flow. If the fluid passes through the bypass orifice, it may flash. When it is necessary to consider adding corresponding cooling measures.
If the centrifugal pump runs below 30% of the rated flow for a long time, an orifice-type regulating bypass should be set up, and the bypass should be connected to the suction equipment of the pump.
The pump transports liquids whose saturated vapor pressure is greater than atmospheric pressure or is in a flashing state at room temperature, especially for vertical pumps. A balanced pipeline should be set between the pump inlet and the cut-off to prevent steam from entering the pump body and causing cavitation. The balance pipeline should be as close as possible to the inlet. Lead out and return to the gas phase space of the liquid aspiration device. The balance pipeline shall be provided with a shut-off valve.
The pressure difference between the two sides of the outlet cut-off valve of the high-lift pump is large, and the one-way force of the valve is large. Especially the large-diameter valve is not easy to open. A DN20 bypass should be set before and after the valve, and the bypass valve should be opened before the main valve is opened. , to balance the pressure on both sides of the main valve.