Big encyclopedia of oil and gas. Centrifugal pumps - commissioning features

5.3.1. Suction pipeline.

Special attention attention should be paid to the tightness of the suction pipeline, which should be as short as possible, with the least number of bends, without sharp transitions, sharp corners.

The suction piping must have a slope towards the pump. This is necessary for complete removal air when filling the pump. An air vent is installed at the highest point of the centrifugal pump housing.

At the end of the suction pipeline for pumps installed in the pits of washing water, check valve, which should be dense. The lower edge of the suction pipeline of a centrifugal pump must be at least 0.5 m below the level of the pumped liquid to prevent air from entering the pump.

5.3.2. Pressure pipeline.

The pump is connected to the discharge pipeline through a non-return valve and a gate valve. The non-return valve is necessary to protect the pump from hydraulic shocks that may occur due to the reverse flow of the pumped liquid during a sudden power outage. pump motor.

The discharge pipeline valve is used to disconnect the centrifugal pump from the pressure pipeline during repairs, to start the pump into operation, and also to regulate the performance and pressure of the pump.

5.3.3. The procedure for preparing a centrifugal pump for start-up.

Before turning on the centrifugal pump, you must:

a) check the presence of lubrication in the bearings;

b) inspect the glands, which should be tightly packed, but not tight. The stuffing box must be tightened in such a way that the pumped liquid

could seep out between the impeller shaft and stuffing box. Excessive tightening of the stuffing box accelerates shaft wear, increases friction losses and reduces the efficiency of the unit;

c) check whether the suction and discharge pipelines are in order, whether the flanges are tightened;

d) check the presence of grounding el. engine and coupling half guards;

e) if there is cooling sealing water, adjust its supply.

After checking the serviceability of the unit and its readiness for action, proceed with filling the pump and the suction pipeline with the pumped liquid. To do this, open the valve on the suction pipe. The pump is considered to be filled if a continuous stream of liquid comes out of the air vent, without air bubbles. Then fully open the valve on the suction pipe. Simultaneously with filling the pump, the tightness of the suction pipe is checked.

5.3.4. The procedure for starting and stopping a centrifugal pump.

After the pump motor is turned on and has reached full number revolutions, gradually open the valve to pressure pipeline completely, which protects the centrifugal pump motor from overload. At the same time, you should not work too long with low flow, as this leads to significant heating of the liquid in the pump and can lead to its destruction.

When stopping the centrifugal pump, gradually close the valve on the pressure pipe and then turn off the pump motor.

5.3.5. How to care for a centrifugal pump during operation.

long and uninterrupted work centrifugal pump is highly dependent on the careful care of the pump. Care is reduced to monitoring the pump during operation and timely lubrication of its bearings.

During operation of the centrifugal pump, it is necessary:

a) periodically check the readings of the pressure gauge on the pressure pipeline. A large fluctuation of the pressure gauge pointer indicates a leak in the suction pipe or the absence of a pumped liquid;

b) periodically check the temperature of the bearings of the unit, the steady temperature of the bearings should not exceed 80 0 С;

c) monitor the tightness of the stuffing boxes - it is necessary that fluid seep through the stuffing box. When the stuffing box is heated, loosen the pressure of the stuffing box bushings. A prerequisite normal operation centrifugal pump is a good centering of the stuffing box, because misalignment causes friction against the protective sleeve of the impeller shaft, which leads to their destruction;

d) periodically add grease to the pump bearings.

5.3.6. Interactions of the personnel of the CTC-1 and CTC-2 when pumping water from the pits

washing water.

a) advantage in pumping out wash water is given to the workshop where the discharge is carried out aggressive waters(after acid washings, micro-washings, RVP washing);

b) when pumping out washing water by workshops into one collector (at treatment facilities) the following pumping order is established:

odd hours - pumps out CTC-1;

even hours - pumps out CTC-2.

c) the right to unscheduled pumping of wash waters to treatment facilities is granted to the workshop in which the pits overflowed.

A pump in which centrifugal force creates fluid movement and the necessary pressure is called a centrifugal pump. They are widely used in the municipal and industrial sectors. Despite the low efficiency and the need to fill water after each stop, centrifugal pumps have a number of advantages:

simplicity and low cost of installing the pump and its operation;
relatively small dimensions and weight;
quite simple installation and dismantling;
high, reliable performance;
constant and uniform water supply;
the ability to pump both water and mixtures.

Filling water from the pipeline

Filling with water is the main condition that ensures the start-up of a centrifugal pump. In principle, the whole essence of the operation of this type of pump lies in the movement of fluid.

It is worth noting a few points that are important to consider when pouring liquid. It is only carried out if there is a foot valve on the suction line. Determining the sufficient level of water in the pump is simple: as soon as water comes out of the tap through which the air is released, the liquid filling must be stopped.

An ejector can be used for filling. It is necessary when filling from a pressure pipeline with high pressure. In this case, the ejector lowers the pressure and allows you to easily fill water into the centrifugal pump, which is planned to be launched.

Note that when using an ejector, air is pumped out until the ejector starts pumping water. When this happens, the centrifugal pump is started.

Another way to fill the pump with water from the pipeline is to use a vacuum pump. Note, however, that it is used when water is poured at fairly large and automated pumping stations. Filling with a vacuum pump is similar to filling by sucking air with an ejector.

Filling water from the tank

It is possible to start a pump of this type by pouring water from the tank.

Before starting the pump, upper part the tank is filled with liquid. What's happening? Water passing through the pressure pipe to the upper part of the tank contributes to the increase in level and vacuum in the lower compartment. Due to these processes, water enters the lower tank through the pipe, and from there it is already pumped.

Pump start features

Note that the stages of starting the pump do not depend on the method of water supply. It is important to remember that before starting the centrifugal pump, it is imperative to unscrew the valve near the pressure gauge and start the electric motor. The pressure pipe valve must be in closed position. The valve of the vacuum gauge and the valves on the pipes for supplying water to the glands must be opened only when the pump rotation speed reaches required amount revolutions, and the pressure gauge will show the desired pressure.

When starting the pump, it is worth remembering other important details.

So, the cooling of bearings is carried out due to the water that is poured into it. Water comes to them when the taps on the water supply pipes are opened. In this case, after opening them, you can open the valve of the pressure pipeline.

Maintenance of a centrifugal pump

When working with a pump of this type, you need to remember the rules for its maintenance:

It is necessary to check that the rings (intended for lubrication) rotate freely on the shaft, and that the bearings have a temperature within the operating temperature range.
In bearings, the amount of oil must be constant. Oil change is carried out no later than after 1000 hours. When changing the oil, the bearing housings are also cleaned.
From time to time, the pump seals need to be tightened.
It should always be remembered that the rotating parts of a centrifugal pump are quite dangerous. When working on the pump, follow the safety precautions and regulations.

If finished preparatory work to start, the auxiliary and auxiliary units are operating normally, the pump and suction pipe are full, then the drive motor can be started.

To prevent dry friction it is forbidden to start the pumps without filling with liquid. Centrifugal pumps, working with excessive pressure at the inlet, can be included in the work only when required pressure at the suction of the pump. After the AIR electric motors reach the operating speed, according to the readings of pressure and current for centrifugal pumps, the gate valve is opened at the pressure until the pressure on the discharge pipe shows the operating pressure value. If the valve is opened too far, the drive motor may be overloaded.

Centrifugal pump units with a low speed are usually put into operation with a closed pressure valve. Vane pumps with high rotational speed should be put into operation with an open valve in the discharge pipeline, because the power consumed by the drive motor for a closed valve can be several times higher than the pump power in working area.

When self-priming centrifugal pumps are started, the valves on the pressure pipe must be fully open to remove the suction air. Centrifugal console pumps with a closed or slightly ajar pressure valve can work normally for a short time, and then an unacceptably high heating of the pumped liquid occurs.

In no case should the operation of the pump be controlled by throttling on the suction or supply pipe.

Automatic pumping units or pumping units are included in the work according to the developed scheme. For such pumping units at start-up, only control actions are carried out.

Piston and rotary pumps operate on the displacement principle and are self-priming pumps. However, it should be borne in mind that these pumps must be freed from air and filled with liquid before the first start-up. Running dry leads to intensive wear of seals and piston rings, and in rotary pumps - to heating of the casing liner, discharge screws or rotating pistons and burning of the rubber casing in single-screw pumps.

Volumetric pumps must not be started with the valve closed on the pressure pipe, as in this case an impermissible increase in pressure is possible, which can cause damage. Starting volumetric pumps with a closed valve on the discharge pipeline is possible only at low discharge pressure and low flow if there is a safety valve in the discharge pipeline.

This starting mode should be abandoned at high discharge pressure and high flow due to the necessary large sizes safety valves and possible overpressure.

Uninterrupted water supply country house or cottages - an important task in terms of creating comfortable living conditions. Its solution lies in two planes: the choice of appropriate equipment and its connection. Often the question arises: how to start surface pump. While seemingly simple, this is not an easy task. The work requires special knowledge and skills.

the sources of water on the site are a quicksand well or an Abyssinian well;
Directly adjacent to the estate adjoins a reservoir suitable for watering the garden.

The condition for the operation of the equipment is the shallow depth of the source - no more than 8-9 m. Therefore, the surface pump is not suitable for lifting water from wells.

At the same time, if there are appropriate conditions, it will be possible to organize an uninterrupted supply of water or an efficient irrigation system with its help.

Autonomous water supply

The surface pump is a kind of intermediary between the source and communications on the site. It “sucks in” water and pressurizes it further down the chain into the distribution system.

Street speakers are a thing of the past. They are being replaced by full-fledged aqueducts. In the case of using a surface pump, it is recommended to provide a storage tank in order to always have a supply of water.

The presence of a container is especially important in the summer, when water consumption traditionally increases or with a small capacity of the well. For example, the productivity of the Abyssinian well is 10-40 l / min., In the summer, during peak hours, interruptions may occur. Therefore, an extra "cube" of water in reserve will not hurt.

To install surface equipment, you will not need much space if there is no need for a pumping station.

Watering in the garden

Another area of application for surface pumping equipment is watering and irrigation on personal plot. The source of water can be ordinary or abyssinian well, spring or reservoir.

In the last two cases, the equipment is installed in the immediate vicinity of the source, because. the height of the water rise is small, they lay communications to the irrigation system or water the plants from a hose.

Devices are sensitive to impurities, small stones, soil particles that can get into the water. Therefore, to start a surface pump, you need additional system filtration, or you will have to abandon operation if the bottom of the reservoir is silted or overgrown with algae.

The best option for placing pumping equipment is installation on a specially equipped concrete foundation

Types of surface pumps: their advantages and disadvantages

Key criterion for measuring equipment efficiency of this type- coefficient useful action. The indicator varies depending on the type of device. There are three of them in total:

centrifugal;
vortex;
With external ejector.

Most high efficiency possess centrifugal models, in vortex the loss of performance reaches 55%. Equipment with an external ejector is practically not used anymore due to low efficiency.

However, there are advantages that are generally inherent in surface equipment:

affordable cost;
compactness and light weight;
ease of installation, unpretentiousness in daily operation and maintenance;
centrifugal pumps successfully cope with the presence in the system air locks;
for effective work no significant water layer is required (from 80 cm).

The disadvantages include:

low lifting capacity (the maximum depth of the source is 8-9 m);
susceptibility to the presence of various impurities in water;
noise at work;
the need for thermal insulation of equipment during operation in the cold season (ideally - separate room, in which t does not fall below 0°C);
in individual cases- low efficiency.

IMPORTANT TO KNOW: When installing surface equipment, the formula for the ratio of vertical and horizontal surfaces is 1:4. That is, when water is taken from a depth of 3 m, the pump is located at a distance of 12 m from the source. If the suction depth exceeds 4 m, the diameter of the pipes is increased by ¼ inch. In standard cases, inch pipes are used.

Filling the incoming line with water - milestone in the installation and start-up of a surface pump

How to connect a surface pump correctly

In addition to the standard set of hoses and fittings, to connect the equipment you will need:

non-return valve with a filter (mesh) - it is necessary to prevent the return of water back to the source;
a hydraulic accumulator with a pressure gauge to maintain the working pressure in the system (2.6-3 bar);
pressure switch for setting the device on / off mode.

The first stage of pump installation is the selection of a suitable site at an appropriate distance from the well. Ideally, a basement or other room that can be equipped under pumping station.

The device is securely fixed in the selected location on the prepared concrete foundation. To dampen vibrations, metal studs are implanted into the concrete, on which the device is mounted.

a check valve is attached to one end of the hose, and the pump itself is connected to the other. In this way, the incoming line is mounted; sanitary flax;
then the line and the pump are filled with water - the so-called spilling of the system;
mount a hydroaccumulator tank (optimum capacity 60-80 l);
connect the equipment to the distributor of the common house water supply;
conduct a pilot inclusion;
escalate operating pressure in expansion tank;
carry out a control check of the water pressure, carry out the final adjustment of the pressure and mode of operation of the equipment.

An example of mounting a surface pump on a special reinforcement platform

It is important to provide in the working circuit devices responsible for auto mode pump operation. In particular, as an alternative for a hydraulic accumulator and a pressure switch, a flow switch with pressure switch functions can be considered.

The device automatically gives a signal to turn on the station when the pressure drops to 1.5-2.5 bar. This prevents the operation of the equipment "dry", i.e. in the event of a drop in the water level at the source.

In most cases, own knowledge and skills are not enough for the competent performance of the entire complex of works. The best way install and connect a system for providing a house and a plot with water - contact qualified specialists. Professionals will determine best option water supply systems, equipment connection diagram and upon completion of work will provide recommendations for practical operation.

Video: surface self-priming pump

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Regional State

autonomous educational institution

secondary vocational education

ACHINSKY COLLEGE OF OIL AND GAS

Centrifugal Pump Operation

Completed by: Nikiforov S.V.

Achinsk 2016

All work on preparation for start-up, start-up and shutdown of the centrifugal pump is carried out by order of the shift supervisor or shift supervisor.

1. Preparation for launch.

When preparing a centrifugal pump for start-up, after reading the entries in the shift log, you must:

Check the connection of instrumentation,

The presence of grease in the bearings,

Technical condition of the clutch with the engine,

The presence and serviceability of the protective shield on it,

Grounding of the electric motor and starter.

If a centrifugal pump sucks liquid, then before starting the pump and the suction pipe are filled with the pumped liquid. If the pump is flooded or the liquid is supplied under pressure, then it is filled with liquid by opening the valve on the suction pipeline.

When the pumped liquid is installed above the level, the pump can be filled in one of the following ways:

Open the valve on the bypass line from the discharge pipeline, while turning off the vacuum gauge to avoid damage;

Suck out air and vapors from the pump and the suction pipeline, for which the pump is connected to a vacuum pump or ejector;

Pour the liquid through the funnel, before filling the pump, open the taps to release air or vapors from the casing.

In the case of water-cooled bearings and seals, before starting the pump, fill in water by opening the taps on the corresponding pipelines.

Before starting low-performance pumps, manually turn the shaft by removing the guard on the valve on the suction pipeline, the pressure gauge valve and start the engine. When the pump reaches full speed and the pressure gauge shows the correct pressure, open the vacuum gauge cock and gradually open the valve on the pressure pipe. In order to avoid heating of the liquid, the operation of the pump with the discharge valve closed ( idling) should last no more than 2-3 minutes.

For normal operation of the pump, its almost silent stroke is characteristic.

2. The principle of operation of centrifugal pumps

The device of the centrifugal pump is shown in fig. 2.1.

Inside the pump housing 1, which, as a rule, has a spiral shape, the impeller 3 is rigidly fixed on the shaft 2. The impeller consists of rear and front discs, between which blades 4 are installed, bent from the radial direction in the direction opposite to the direction of rotation of the impeller. With the help of nozzles 5 and 6, the pump housing is connected to the suction and pressure pipelines.

The principle of operation of a centrifugal pump is to convert, due to centrifugal force, the electrical energy consumed by the engine into static flow energy (pressure rises).

The water flow entering the center of a rotating impeller with radially curved blades, under the action of centrifugal force, changes the direction of its movement from axial to radial, and moving along the blades is collected in the casing channel located behind the periphery of the impeller.

In a spiral channel resembling a confuser in shape, the kinetic energy of the flow is partially converted into static energy and a flow with a higher pressure exits the discharge pipe.

In this way, Electric Energy consumed by the electric motor is spent on increasing the water pressure, while the efficiency of the pump with air-cooled electric motor (dry rotor) can reach 70-80%.

The operating parameters of centrifugal pumps are strictly dependent on the rotational speed of the impeller, for example: a twofold increase in rotational speed leads to an increase in flow by a factor of two, an increase in pressure by a factor of four and an increase in energy consumption by an eightfold.

3.Pump stop.

Stop the pump in the following sequence:

Slowly close the gate valve on the discharge pipeline;

Close the valve of the vacuum gauge (pressure gauge);

Stop the engine;

Close the valve on the suction pipe;

Close the pressure gauge valve;

Release the pump from the pumped liquid, if it is provided by the instruction.

4. Care of a running pump

centrifugal pump start

Bearings must be lubricated while the pump is running. With ring lubrication of bearings, the rings must rotate freely with the shaft, maintain a normal level of lubricant in the crankcase. It is also necessary to support normal temperature bearings. Every 800-1000 hours of pump operation, the used oil should be drained from the bearing housings, flushed and filled with fresh oil. The driver must follow technical condition glands. Hydraulic sealing glands must be tightened so that the liquid leaks out continuously in separate drops. During the operation of the pump, it is necessary to maintain the specified mode, to record the readings of instrumentation in a replaceable log.

It is forbidden to start the electric pump with the valve on the suction line closed; operate the electric pump without installing control and blocking devices specified in the operational documents; leave pumped liquid and coolant in the switched off electric pump, if they can change their state of aggregation at a temperature environment; operate the electric pump without cooling it.

During the operation of centrifugal pumps, malfunctions may occur that the driver must eliminate. The pump "may fail to operate after start-up due to:

Leaks in the suction line, in this case it is necessary to inspect the pipeline and eliminate leaks;

The presence of air or liquid vapor in the pump housing, it is necessary to refill the pump;

clogging of pipes and vessels - inspect, clean pipes and vessels.

Vibration and pump noise are caused by:

Loose fundamental bolts - tighten the bolts;

Installing the pump shaft and the electric motor is not on the same straight line - make the correct alignment;

Partial clogging of the impellers - inspect and clean the pump;

Shaft deflection, sticking of rotating parts, wear of bearings - replace damaged parts;

Cavitation - stop the pump and take action to reduce the suction lift.

5. Labor safety when working on pumping units

At the workplace of the driver must be created safe conditions labor: the distances between the pumping units must ensure Free access and the ability to monitor the operation of the pump; stairs and ladders should be comfortable, lighting should be good, ventilation and heating should be sufficient.

The workplace should be equipped with a gas mask of a certain type and brand.

The driver must:

Ensure that moving and rotating parts of the machine are protected;

When the pump is running, do not tighten bolts and studs on moving parts and do not replace seals and valves;

Avoid leakage of flammable and poisonous liquids;

Do not scatter oiled cleaning materials, but store them in metal closed boxes;

Always have a rubber mat near the starting electrical equipment;

As portable lighting, use a portable lamp with a voltage of 12 V, and in some workshops only an explosion-proof one;

Know where fire extinguishers are stored and be able to use them;

Know how to call the fire brigade and gas rescuers;

Know and execute job description driver.

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