CN115263821A - Centrifugal pump pipeline system with suction inlet filter screen backwashing function and using method - Google Patents
Centrifugal pump pipeline system with suction inlet filter screen backwashing function and using method Download PDFInfo
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- CN115263821A CN115263821A CN202210728449.4A CN202210728449A CN115263821A CN 115263821 A CN115263821 A CN 115263821A CN 202210728449 A CN202210728449 A CN 202210728449A CN 115263821 A CN115263821 A CN 115263821A
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- 238000000034 method Methods 0.000 title claims abstract description 34
- 238000011001 backwashing Methods 0.000 title claims abstract description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 68
- 239000007788 liquid Substances 0.000 claims abstract description 36
- 230000002159 abnormal effect Effects 0.000 claims abstract description 23
- 238000004364 calculation method Methods 0.000 claims description 12
- 230000001133 acceleration Effects 0.000 claims description 4
- 230000005484 gravity Effects 0.000 claims description 4
- 238000005406 washing Methods 0.000 abstract description 4
- 238000004458 analytical method Methods 0.000 abstract description 2
- 238000011010 flushing procedure Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 6
- 238000004891 communication Methods 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 238000004140 cleaning Methods 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 238000007689 inspection Methods 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000012271 agricultural production Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/70—Suction grids; Strainers; Dust separation; Cleaning
- F04D29/708—Suction grids; Strainers; Dust separation; Cleaning specially for liquid pumps
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
- B01D29/62—Regenerating the filter material in the filter
- B01D29/66—Regenerating the filter material in the filter by flushing, e.g. counter-current air-bumps
- B01D29/68—Regenerating the filter material in the filter by flushing, e.g. counter-current air-bumps with backwash arms, shoes or nozzles
Abstract
The invention discloses a centrifugal pump pipeline system with a suction inlet filter screen backwashing function, which comprises a centrifugal pump (7), a motor (3), a first three-way connecting pipe (9), a second three-way connecting pipe (17), a third three-way connecting pipe (20), a main inlet filter screen (19), an auxiliary inlet filter screen (22), a plurality of other pipelines, a valve, an inlet pressure gauge (13), an outlet pressure gauge (12), a liquid level meter (25) and a controller (27), wherein the pipeline system can suck water from a water pool (26) through the main inlet filter screen (19) or the auxiliary inlet filter screen (22); the invention also discloses a using method of the management system, the test calibration is carried out before the formal operation, the data table is obtained, the operation process of the pipeline system is divided into a normal mode and an abnormal mode, and if the pipeline system is in the abnormal mode through analysis and judgment, the switching state of the relevant valve is changed, the inlet filter screen is backflushed, and then the pipeline system returns to the normal mode. The pipeline system has the advantages of simple structure, low cost, stable and reliable use method, wide adaptability and easy realization, and can save manpower and effectively realize the automatic washing of the filter screen.
Description
Technical Field
The invention relates to the technical field of centrifugal pumps, in particular to a centrifugal pump pipeline system with a suction inlet filter screen backwashing function and a using method thereof.
Background
As the most widely used pump door, centrifugal pumps are widely used in industrial and agricultural production and resident living occasions. One common application for centrifugal pumps is to pump water from a sump and to a user. In many cases, because a certain amount of solid impurities exist in the water tank, a filter screen needs to be installed on a water suction port of the centrifugal pump to prevent the solid impurities from being sucked into the centrifugal pump and a water conveying pipeline. However, the filter screen inevitably adsorbs a large amount of solid impurities in the using process, the filter screen is easy to block for a long time, the flow resistance is increased, the energy waste is caused, and the water absorption capacity of the centrifugal pump is influenced. Therefore, the filter screen of the suction port is frequently cleaned during the operation of the centrifugal pump.
Among the present well-known technical scheme, adopt artifical periodic inspection usually and use extra special washing unit to carry out the filter screen clearance to the suction opening, not only consumed a large amount of cost of labor like this, increased fixed equipment input cost moreover, the normal water delivery work of centrifugal pump is still influenced to filter screen clearance process simultaneously. Therefore, a new technical scheme is urgently needed to be developed to realize the effective washing of the suction inlet filter screen.
Disclosure of Invention
In order to solve the technical problems, the invention provides the centrifugal pump pipeline system with the suction inlet filter screen backwashing function and the use method, which have the advantages of simple structure, low cost, stability, reliability, wide adaptability and easiness in realization, and can greatly save the labor cost without additionally arranging a special flushing device.
According to one aspect of the present invention, there is provided a centrifugal pump piping system having a suction port filter screen backwashing function, the piping system being provided with a centrifugal pump, a motor for driving the centrifugal pump to operate, and a first three-way connection pipe, a second three-way connection pipe, a third three-way connection pipe, and a four-way connection pipe, the first three-way connection pipe including a first three-way connection pipe first passage, a first three-way connection pipe second passage, and a first three-way connection pipe third passage, the second three-way connection pipe including a second three-way connection pipe first passage, a second three-way connection pipe second passage, and a second three-way connection pipe third passage, the third three-way connection pipe including a third three-way connection pipe first passage, a third three-way connection pipe second passage, and a third three-way connection pipe third passage, the four-way connection pipe including a four-way connection pipe first passage, a four-way connection pipe second passage, a four-way connection pipe third passage, and a four-way connection pipe third passage; the inlet of the centrifugal pump is sequentially communicated with an inlet main pipe, a first three-way connecting pipe first passage, a first three-way connecting pipe third passage, a first communicating pipe, a second three-way connecting pipe first passage, a second three-way connecting pipe second passage, a main suction pipe and a main inlet filter screen and can suck water from a water pool, and the outlet of the centrifugal pump is sequentially communicated with an outlet main pipe, a four-way connecting pipe third passage, a four-way connecting pipe first passage and an outlet pipeline and sends the water to a water using link; the fourth passage of the four-way connecting pipe is communicated with the third passage of the second three-way connecting pipe through a second communicating pipe; the four-way connecting pipe second passage is communicated with the first three-way connecting pipe second passage through a third communicating pipe, a third three-way connecting pipe first passage, a third three-way connecting pipe third passage and a fourth communicating pipe in sequence; the third tee joint pipe second passage is communicated with the auxiliary suction pipe and the auxiliary inlet filter screen in sequence and can absorb water from the water pool; a first valve is arranged on the first communicating pipe, a second valve is arranged on the second communicating pipe, a third valve is arranged on the third communicating pipe, a fourth valve is arranged on the fourth communicating pipe, and an outlet valve is arranged on the outlet pipeline; an inlet pressure gauge is arranged on an inlet main pipe of the centrifugal pump, an outlet pressure gauge is arranged on an outlet main pipe of the centrifugal pump, and a liquid level meter is arranged in the water pool and used for measuring the liquid level height of the liquid level meter; the first valve, the second valve, the third valve, the fourth valve, the outlet valve, the inlet pressure gauge, the outlet pressure gauge and the liquid level meter are all electrically connected with the controller.
In the centrifugal pump pipeline system with the suction inlet filter screen backwashing function, the motor is a constant-speed motor.
Above-mentioned centrifugal pump pipe-line system with suction inlet filter screen back flush function, first valve, second valve, third valve and fourth valve are electric gate valve, the outlet valve is aperture adjustable electric butterfly valve.
According to another aspect of the invention, a method for using the centrifugal pump pipeline system with the suction port filter screen backwashing function is provided:
carrying out test calibration before the pipeline system is formally operated: first, the main inlet screen is manually inspected and cleaned to ensure that it is free of any clogging; secondly, opening the first valve and closing the second valve, the third valve and the fourth valve; then, the centrifugal pump is started, the outlet valve is gradually adjusted from the minimum allowable opening degree to the maximum allowable opening degree, and the gauge pressure value P of the inlet pressure gauge in the adjusting process is continuously recorded according to a fixed time interval1Gauge pressure value P of outlet pressure gauge2And the height h of the free liquid level in the pool from the bottom of the pool measured by the liquid level meterw(ii) a And finally, a series of data recorded in the adjustment process are arranged into a data table and stored in the controller, the first row and the second row of the data table are respectively an A value and a B value, and the A value and the B value of each column of the data table are calculated by the acquired data at the same moment in the following way:
A＝P2-P1 (1)
in the formula, P1Inlet gauge pressure value P measured for inlet pressure gauge1，P2Outlet gauge pressure value P measured for outlet pressure gauge2，hwThe height of the free liquid level in the water tank from the bottom of the water tank measured by the liquid level meter is rho and g respectively representing the density and the gravity acceleration of water;
the operation process of the pipeline system is divided into a normal mode and an abnormal mode, wherein the normal mode is a default operation mode; under the normal mode, the first valve is open state, and second valve, third valve and fourth valve are closed state, and the export valve is in certain aperture according to the water delivery needs, according to fixed time interval circulation execution following step:
step z1, measuring the inlet gauge pressure value P1Outlet gauge pressure value P2And the height h of the free liquid level from the bottom of the poolwCalculating to obtain A value and B value;
step z2, for the value A obtained by calculation in step 1, obtaining a value B' corresponding to the value A by a method of inquiring a data table and performing linear interpolation:
inquiring two A values closest to the A value obtained by the calculation in the step 1 and B values corresponding to the A values in the data table from the data table, and obtaining a B' value in a linear interpolation mode:
wherein A is the value A obtained by calculation in the step 1; a. The1And A2Respectively are two A values which are closest to the A value calculated in the step 1 in the data table and have A1<A2；B1And B2Are respectively the sum of A in the data table1And A2Each corresponding value of B, and A1And B1In the same column, A2And B2Are in the same column;
step z3, comparing the B value obtained by calculation in the step 1 with the B' value obtained by table lookup and interpolation in the step 2: if B/B' > e, interrupting the execution cycle of the normal mode and entering an abnormal mode; if B/B' is less than or equal to e, maintaining the normal mode and returning to the step 1 to start the next cycle; wherein e is between 1.05 and 1.2;
if the pipeline system enters an abnormal mode, the following steps are sequentially executed:
step y1, closing the first valve and the third valve, opening the second valve and the fourth valve, adjusting the outlet valve to the maximum allowable opening degree, and maintaining the state for t seconds, wherein t is between 10 seconds and 200 seconds;
step y2, opening the first valve and the third valve, closing the second valve and the fourth valve, adjusting the outlet valve to the maximum allowable opening degree, and maintaining the state for t seconds, wherein t is between 10 seconds and 200 seconds;
and step y3, closing the third valve, adjusting the outlet valve to a certain opening degree according to the water delivery requirement, ending the abnormal mode and returning to the normal mode.
The following describes the implementation principle of the technical solution of the present invention.
Under the normal working mode of the pipeline system, water in the water pool sequentially passes through the main inlet filter screen, the main suction pipe, the second three-way connecting pipe, the first communicating pipe, the first three-way connecting pipe (provided with the first valve) and the inlet main pipe to enter the centrifugal pump, is pressurized by the centrifugal pump and then is delivered to a water using link through the outlet main pipe, the four-way connecting pipe and the outlet pipeline (provided with the outlet valve). The bottom of the water tank is taken as a zero-height surface, and the elevation of the inlet pressure gauge is recorded as h1Then, under the normal working mode, the column Bernoulli equation between the free liquid level in the water tank and the centrifugal pump inlet main pipe is as follows:
where v is the flow velocity in the tube, hsFor the loss of resistance between the water flow from the main inlet screen to the inlet header, hsThe calculation of (a) can be written as:
ζ in the formulalAnd ζjRespectively representing the on-way drag loss coefficient and the local drag loss coefficient of the flow process.
Substituting formula (5) for formula (4) and finishing to obtain:
the flow-head characteristic curve of a typical centrifugal pump varies as follows: as the flow increases, its head decreases. For a specific centrifugal pump, there is a definite one-to-one correspondence between the flow (which can be represented by the flow velocity v in the pipe) and the lift (which can be represented by the pressure difference between the outlet and the inlet of the centrifugal pump), that is, the flow can be written as a function of the lift, so the flow velocity v in the pipe can be written as P2-P1Function of (c):
v＝f(P2-P1) (7)
substituting the formula (1), the formula (2) and the formula (7) into the formula (6) to obtain:
equation (8) indicates that for a certain value of a, there is a unique value of B corresponding to it. If the main inlet screen is blocked during operation, the local drag loss coefficient ζjWill increase significantly, and in the case of a value being unchanged, will also increase significantly its corresponding B value.
According to the principle, before the pipeline system is formally operated, test calibration is carried out to obtain a series of data tables consisting of the A value and the B value corresponding to the A value. When the pipeline system runs in a normal mode, calculating to obtain an A value and a B value corresponding to the A value according to the measured data, and obtaining a B' value corresponding to the A value from the data table through table lookup and interpolation based on the calculated A value; local drag loss coefficient ζ if the primary inlet screen is cloggedjThe value of B' is obviously larger than the value of B, and under the condition, the filter screen at the inlet of the controller is seriously blocked, the execution cycle of the normal mode is interrupted, and the abnormal mode is entered.
In the abnormal mode, in step y1, the first valve and the third valve are closed, the second valve and the fourth valve are opened, the outlet valve is adjusted to the maximum allowable opening degree, and the state is maintained for t seconds. Under the condition, the centrifugal pump runs at a larger flow rate, and the centrifugal pump sequentially passes through the auxiliary inlet filter screen, the auxiliary suction pipe, the third tee joint pipe, the fourth communicating pipe (provided with the fourth valve), the first tee joint pipe and the inlet main pipe to suck water from the water tank. Water sucked into the centrifugal pump enters the four-way connecting pipe through the outlet main pipe and is divided into two parts in the four-way connecting pipe: one is sent to the water-consuming part via an outlet pipe (on which an outlet valve is mounted) as usual; the other strand flows to the main inlet filter screen through a second communicating pipe (provided with a first valve), a second three-way connecting pipe and a main suction pipe, washes the main inlet filter screen and then flows back to the water tank, and under the condition, the water flow direction passing through the main inlet filter screen is opposite to the normal mode, so that the main inlet filter screen can be well backwashed.
Similarly, in step y2 in the abnormal mode, the centrifugal pump still operates at a relatively large flow rate, the centrifugal pump sucks water through the main inlet filter screen, and the pressurized water flows out of the centrifugal pump and is divided into two parts: one strand is sent to a water using link as usual; and the other strand is used for back washing the auxiliary inlet filter screen through a third communicating pipe (provided with a third valve), a third three-way connecting pipe and an auxiliary suction pipe so as to remove solid impurities adsorbed on the auxiliary inlet filter screen.
And after the steps y1 and y2 are completed, returning to the normal mode.
The invention has the beneficial effects that:
1. the pipeline system provided by the invention carries out back flushing on the filter screen of the suction inlet by dividing a part of the flow transported by the self operation of the centrifugal pump, does not need to add an additional special flushing device except various conventional and cheap pipe fittings, a pressure gauge, a liquid level meter and a controller, can be realized by slightly modifying the existing pipeline system of the centrifugal pump, and has the advantages of simple structure, low cost, wide adaptability and easy realization.
2. The method grasps the characteristics of the flow-lift curve of the centrifugal pump and applies the Bernoulli equation to establish the correlation among the inlet pressure, the outlet pressure, the water tank liquid level height and the suction inlet filter screen resistance coefficient of the centrifugal pump, analyzes and compares the test data of the operation process with the data calibrated in advance to judge whether the suction inlet filter screen is obviously blocked or not, and realizes the automatic and accurate judgment and the cleaning as required of the suction inlet filter screen under the condition of not needing a flowmeter and other relatively precise and expensive instruments. And when the back flushing of the main inlet filter screen is finished, the back flushing of the auxiliary inlet filter screen is carried out, and then the normal operation mode is returned. The suction inlet filter screen of the pipeline system is thoroughly washed, the labor cost can be greatly saved, and the back washing process always maintains water supply for users, so the device also has the advantages of stability and reliability.
Drawings
Fig. 1 is a schematic diagram of a centrifugal pump piping system according to an embodiment of the present invention, in which fig. 1 is a second communication pipe, 2 is a second valve, 3 is a motor, 4 is an outlet pipe, 5 is a four-way connection pipe, 6 is an outlet main pipe, 7 is a centrifugal pump, 8 is an inlet main pipe, 9 is a first three-way connection pipe, 10 is a first communication pipe, 11 is an outlet valve, 12 is an outlet pressure gauge, 13 is an inlet pressure gauge, 14 is a fourth communication pipe, 15 is a fourth valve, 16 is a first valve, 17 is a second three-way connection pipe, 18 is a main suction pipe, 19 is a main inlet strainer, 20 is a third three-way connection pipe, 21 is an auxiliary suction pipe, 22 is an auxiliary inlet strainer, 23 is a third communication pipe, 24 is a third valve, 25 is a liquid level gauge, 26 is a water tank, and 27 is a controller.
Fig. 2 is a schematic diagram of a first three-way connection pipe and a pipeline directly connected to the first three-way connection pipe in an embodiment of the present invention, in which fig. 8 is an inlet main pipe, 9 is the first three-way connection pipe, 10 is a first connection pipe, 14 is a fourth connection pipe, 91 is a first passage of the first three- way connection pipe 9, 92 is a second passage of the first three- way connection pipe 9, and 93 is a third passage of the first three-way connection pipe 9.
Fig. 3 is a schematic diagram of a second three-way connection pipe and a pipeline directly connected to the second three-way connection pipe in the embodiment of the present invention, in which fig. 1 is a second connection pipe, 10 is a first connection pipe, 17 is the second three-way connection pipe, 18 is a main suction pipe, 171 is a first passage of the second three- way connection pipe 17, 172 is a second passage of the second three- way connection pipe 17, and 173 is a third passage of the second three-way connection pipe 17.
Fig. 4 is a schematic diagram of a third three-way connection pipe and a pipeline directly connected to the third three-way connection pipe in the embodiment of the present invention, in which fig. 14 is a fourth connection pipe, 20 is the third three-way connection pipe, 21 is an auxiliary suction pipe, 23 is the third connection pipe, 201 is a first passage of the third three- way connection pipe 20, 202 is a second passage of the third three- way connection pipe 20, and 203 is a third passage of the third three-way connection pipe 20.
Fig. 5 is a schematic diagram of a four-way connection pipe and pipes directly connected thereto in an embodiment of the present invention, in which fig. 1 is a second connection pipe, 4 is an outlet pipe, 5 is the four-way connection pipe, 6 is an outlet header, 23 is a third connection pipe, 51 is a first passage of the four- way connection pipe 5, 52 is a second passage of the four- way connection pipe 5, 53 is a third passage of the four- way connection pipe 5, and 54 is a fourth passage of the four-way connection pipe 5.
Fig. 6 is a front view of the main inlet screen in the embodiment of the present invention, in which 19 is the main inlet screen, 191 is the filtering holes of the main inlet screen 19, and 192 is the mesh strip of the main inlet screen 19.
Fig. 7 is a top view of a main inlet screen 19, 191 is the filtering holes of the main inlet screen 19, and 192 is the mesh strip of the main inlet screen 19 according to an embodiment of the present invention.
Fig. 8 is a schematic diagram illustrating the components of the steps and the switching manner of the normal mode and the abnormal mode of the pipeline system according to the embodiment of the present invention.
Detailed Description
The invention is further described below with reference to the drawings and examples.
As shown in fig. 1 to 5, a centrifugal pump piping system having a suction port filter screen backwashing function is provided with a centrifugal pump 7, a motor 3 for driving the centrifugal pump 7 to operate, and a first three-way connection pipe 9, a second three-way connection pipe 17, a third three-way connection pipe 20, and a four-way connection pipe 5, wherein the first three-way connection pipe 9 includes a first three-way connection pipe first passage 91, a first three-way connection pipe second passage 92, and a first three-way connection pipe third passage 93, the second three-way connection pipe 17 includes a second three-way connection pipe first passage 171, a second three-way connection pipe second passage 172, and a second three-way connection pipe third passage 173, the third three-way connection pipe 20 includes a third three-way connection pipe first passage 201, a third three-way connection pipe second passage 202, and a third three-way connection pipe third passage 203, and the four-way connection pipe 5 includes a four-way first passage 51, a four-way connection pipe second passage 52, a four-way connection pipe third passage 53, and a connection pipe third passage 54; an inlet of the centrifugal pump 7 is sequentially communicated with an inlet main pipe 8, a first three-way connecting pipe first passage 91, a first three-way connecting pipe third passage 93, a first communicating pipe 10, a second three-way connecting pipe first passage 171, a second three-way connecting pipe second passage 172, a main suction pipe 18 and a main inlet filter screen 19 and can suck water from the water tank 26, and an outlet of the centrifugal pump 7 is sequentially communicated with an outlet main pipe 6, a four-way connecting pipe third passage 53, a four-way connecting pipe first passage 51 and an outlet pipeline 4 and sends water to a water using link; the four-way connecting pipe fourth passage 54 is communicated with the second three-way connecting pipe third passage 173 through a second communicating pipe 1; the four-way connecting pipe second passage 52 is communicated with the first three-way connecting pipe second passage 92 sequentially through the third communicating pipe 23, the third three-way connecting pipe first passage 201, the third three-way connecting pipe third passage 203 and the fourth communicating pipe 14; the third three-way connecting pipe second passage 202 is communicated with the auxiliary suction pipe 21 and the auxiliary inlet filter screen 22 in sequence and can suck water from the water pool 26; a first valve 16 is arranged on the first communicating pipe 10, a second valve 2 is arranged on the second communicating pipe 1, a third valve 24 is arranged on the third communicating pipe 23, a fourth valve 15 is arranged on the fourth communicating pipe 14, and an outlet valve 11 is arranged on the outlet pipeline 4; an inlet pressure gauge 13 is arranged on an inlet main pipe 8 of the centrifugal pump 7, an outlet pressure gauge 12 is arranged on an outlet main pipe 6 of the centrifugal pump 7, and a liquid level meter 25 is arranged in the water tank 26 and used for measuring the liquid level height of the liquid level meter; the first valve 16, the second valve 2, the third valve 24, the fourth valve 15, the outlet valve 11, the inlet pressure gauge 13, the outlet pressure gauge 12 and the liquid level meter 25 are all electrically connected with the controller 27.
In the centrifugal pump pipeline system with the suction inlet filter screen backwashing function, the motor 3 is a constant-speed motor.
In the centrifugal pump pipeline system with the suction inlet filter screen backwashing function, the first valve 16, the second valve 2, the third valve 24 and the fourth valve 15 are all electric gate valves, and the outlet valve 11 is an electric butterfly valve with an adjustable opening degree.
As shown in fig. 6 and 7, the main inlet screen 19 may be a cylindrical structure with an upper opening and a large number of filtering holes formed in the bottom and the side wall, and the main inlet screen 19 may be welded to the nozzle of the main suction pipe 18. The structural mounting of the secondary inlet screen 22 is referred to the primary inlet screen 19.
The use method of the centrifugal pump pipeline system with the suction inlet filter screen backwashing function comprises the following steps:
carrying out test calibration before the pipeline system is formally operated: first, the main inlet screen 19 is manually inspected and cleaned to ensure that it is free of any clogging; next, the first valve 16 is opened and the second valve 2, the third valve 24, and the fourth valve 15 are closed; the centrifugal pump 7 is then started, opening the outlet valve 11 from its minimum allowableGradually adjusting the pressure to the maximum allowable opening degree, and continuously recording the gage pressure value P of the inlet pressure gauge 13 in the adjusting process according to a fixed time interval 112 gauge pressure value P of outlet pressure gauge2And the height h of the free liquid level in the tank 26 from the bottom of the tank 26, measured by the level gauge 25w(ii) a Finally, a series of data recorded in the adjustment process is organized into a data table and stored in the controller 27, the first row and the second row of the data table are respectively the a value and the B value, and the a value and the B value of each column of the data table are calculated by the collected data at the same time in the following manner:
A＝P2-P1 (1)
in the formula, P1Inlet gauge pressure value P measured for the inlet pressure gauge 131，P2Outlet gauge pressure value P measured for outlet pressure gauge 122，hwThe height of the free liquid level in the water tank 26 from the bottom of the water tank 26 measured by the liquid level meter 25, wherein rho and g are the density and the gravity acceleration of water respectively;
as shown in fig. 8, the operation process of the pipeline system is divided into a normal mode and an abnormal mode, wherein the normal mode is a default operation mode; in the normal mode, the first valve 16 is in an open state, the second valve 2, the third valve 24 and the fourth valve 15 are in a closed state, the outlet valve 11 is in a certain opening degree according to the water delivery requirement, and the following steps are executed in a circulating mode according to a fixed time interval:
step z1, measuring the inlet gauge pressure value P1Outlet gauge pressure value P2And the height h of the free liquid level from the bottom of the basin 26wCalculating to obtain A value and B value;
step z2, for the value A obtained by calculation in step 1, obtaining a value B' corresponding to the value A by a method of inquiring a data table and performing linear interpolation:
inquiring two A values closest to the A value calculated in the step 1 and B values corresponding to the two A values in the data table from the data table, and obtaining a B' value in a linear interpolation mode:
wherein A is the value A obtained by calculation in the step 1; a. The1And A2Respectively are two A values which are closest to the A value calculated in the step 1 in the data table and have A1<A2；B1And B2Are respectively A in the data table1And A2Each corresponding value of B, and A1And B1In the same column, A2And B2Are in the same column;
step z3, comparing the B value obtained by calculation in the step 1 with the B' value obtained by table lookup and interpolation in the step 2: if B/B' > e, interrupting the execution cycle of the normal mode and entering an abnormal mode; if B/B' is less than or equal to e, maintaining the normal mode and returning to the step 1 to start the next cycle; wherein e is between 1.05 and 1.2;
if the pipeline system enters an abnormal mode, the following steps are sequentially executed:
step y1, closing the first valve 16 and the third valve 24, opening the second valve 2 and the fourth valve 15, adjusting the outlet valve 11 to the maximum allowable opening degree, and maintaining the state for t seconds, wherein t is between 10 seconds and 200 seconds;
step y2, opening the first valve 16 and the third valve 24, closing the second valve 2 and the fourth valve 15, adjusting the outlet valve 11 to the maximum allowable opening degree, and maintaining the state for t seconds, wherein t is between 10 seconds and 200 seconds;
and step y3, closing the third valve 24, adjusting the outlet valve 11 to a certain opening degree according to water delivery requirements, ending the abnormal mode and returning to the normal mode.
Specifically, when the centrifugal pump 7 is started, in order to avoid the air-bound phenomenon, a vacuum pump may be used to evacuate all suction pipes before the inlet of the centrifugal pump 7, so that water is poured into the centrifugal pump, and then the motor 3 is started and drives the centrifugal pump 7 to work.
Examples
A chemical plant uses a centrifugal pump to take water from a pool and transport it to a workshop for use, and the structural composition of the centrifugal pump piping system and the structure of the main inlet screen 19 are shown in fig. 1 to 7.
In this embodiment, nominal diameters of all pipelines are equal, structures, installation manners and installation heights of the main inlet filter screen 19 and the auxiliary inlet filter screen 22 are all the same, the controller 27 is a programmable logic controller PLC, the liquid level meter 25 is a pressure gauge installed at the bottom of the water tank 26, and the liquid level height is obtained through conversion of pressure, the minimum allowable opening of the outlet valve 11 is 10%, and the maximum allowable opening is 100%.
Carrying out test calibration before formal operation of a pipeline system: first, the main inlet screen 19 is manually checked and cleaned to ensure that it is free of any clogging; secondly, the first valve 16 is opened and the second valve 2, the third valve 24 and the fourth valve 15 are closed; then, the centrifugal pump 7 is started, the opening degree of the outlet valve 11 is gradually adjusted from 10 percent to 100 percent according to the speed of 5 percent/minute, and the gauge pressure value P of the inlet pressure gauge 13 in the adjusting process is continuously recorded according to the time interval of 1 minute 112 gauge pressure value P of outlet pressure gauge2And the height h of the free liquid level in the tank 26 from the bottom of the tank 26, measured by the level gauge 25w(ii) a Finally, a series of data recorded in the adjustment process is organized into a data table and stored in the controller 27, wherein the first row and the second row of the data table are respectively the A value and the B value, and 19 groups of data with one-to-one correspondence of the A value and the B value are obtained.
On a certain day, the pipeline system runs in a normal mode, the first valve 16 is in an open state, the second valve 2, the third valve 24 and the fourth valve 15 are in a closed state, the outlet valve 11 is in an opening degree of 70% according to the water delivery requirement, and the controller 27 performs data acquisition and calculation analysis according to 1 minute. At a certain moment, the gauge pressure value P of the inlet is measured1= 40kPa, outlet gauge pressure value P2=160kPa, height h of free liquid level from bottom of pool 26w=2m, the density ρ and g of the taken water are the density ρ =1000kg/m3 of the water, and the acceleration of gravity g =9.8m/s, respectively2The values a and B thus calculated are: a =200kpa, b =7.08m.
The two values of A closest to the value of A calculated above are searched from the data table as: a. The1＝170kPa，A2=245kPa; the corresponding two B values in the data table are: b1＝6.85m，B2=5.73m. Linear difference yields B' =6.40m. In this example, e is 1.08, since B/B' =1.11 at this time>e, interrupting the execution cycle of the normal mode and entering an abnormal mode, wherein in the step y1, the first valve 16 and the third valve 24 are closed, the second valve 2 and the fourth valve 15 are opened, and the state maintaining time in the steps y1 and y2 in the abnormal mode is t =50 seconds. And in the abnormal mode, after the step y3 is executed, the pipeline system is recovered to the normal mode for operation.
It should be noted that in rare cases, the filter screen still cannot be cleaned effectively after back flushing, in which case the pipeline system will automatically enter the abnormal mode many times in a short time. When the pipeline system enters the abnormal mode n times within the time W, wherein W is between 10 minutes and 100 minutes, and n is between 2 and 5, the system is considered to be in the special mode. Once the system is in the ad hoc mode, controller 27, on the one hand, issues an alarm to maintenance personnel requesting manual cleaning and inspection of primary and secondary inlet screens 19, 22; on the other hand, the first valve 16 and the fourth valve 15 are opened, and the second valve 2 and the third valve 24 are closed, so that the centrifugal pump 7 temporarily performs double suction from the main inlet strainer 19 and the auxiliary inlet strainer 22 at the same time. And after the maintenance personnel dispose, manually returning the pipeline system to the normal mode.
The pipeline system of this embodiment divides a part in the flow that centrifugal pump self operation was carried and carries out the back flush of sunction inlet filter screen, need not add extra special washing unit except that conventional low-priced various pipe fittings, manometer, level gauge and controller, can add the transformation slightly and can realize on the basis of current centrifugal pump pipeline system, so simple structure, low cost, adaptability are wide and easily realize.
The method grasps the characteristics of the flow-lift curve of the centrifugal pump and applies the Bernoulli equation to establish the correlation between the inlet pressure, the outlet pressure, the water tank liquid level height and the suction inlet filter screen resistance coefficient of the centrifugal pump, analyzes and compares the test data of the operation process with the data calibrated in advance to judge whether the suction inlet filter screen is obviously blocked or not, and realizes the automatic and accurate judgment and the cleaning as required of the suction inlet filter screen under the condition of not needing a flowmeter and other relatively precise and expensive instruments. And when the back flushing of the main inlet filter screen is finished, the back flushing of the auxiliary inlet filter screen is carried out, and then the normal operation mode is returned. The method can thoroughly wash the filter screen at the suction inlet of the pipeline system, greatly save labor cost, and always maintain water supply for users in the back washing process, thereby having the advantages of stability and reliability.
Claims (4)
1. A centrifugal pump pipeline system with a suction inlet filter screen backwashing function is characterized by being provided with a centrifugal pump (7), a motor (3) used for driving the centrifugal pump (7) to operate, a first three-way connecting pipe (9), a second three-way connecting pipe (17), a third three-way connecting pipe (20) and a four-way connecting pipe (5), wherein the first three-way connecting pipe (9) comprises a first three-way connecting pipe first passage (91), a first three-way connecting pipe second passage (92) and a first three-way connecting pipe third passage (93), the second three-way connecting pipe (17) comprises a second three-way connecting pipe first passage (171), a second three-way connecting pipe second passage (172) and a second three-way connecting pipe third passage (173), the third three-way connecting pipe (20) comprises a third three-way connecting pipe first passage (201), a third three-way connecting pipe second passage (202) and a third four-way connecting pipe third passage (203), and the four-way connecting pipe (5) comprises a four-way connecting pipe first passage (51), a four-way connecting pipe second passage (52), a third four-way connecting pipe (53) and a third four-way connecting pipe (54); an inlet of the centrifugal pump (7) is sequentially communicated with an inlet main pipe (8), a first three-way connecting pipe first passage (91), a first three-way connecting pipe third passage (93), a first connecting pipe (10), a second three-way connecting pipe first passage (171), a second three-way connecting pipe second passage (172), a main suction pipe (18) and a main inlet filter screen (19) and can absorb water from a water tank (26), and an outlet of the centrifugal pump (7) is sequentially communicated with an outlet main pipe (6), a four-way connecting pipe third passage (53), a four-way connecting pipe first passage (51) and an outlet pipeline (4) and sends water to a water using link; the four-way connecting pipe fourth passage (54) is communicated with the second three-way connecting pipe third passage (173) through a second communicating pipe (1); the four-way connecting pipe second passage (52) is communicated with the first three-way connecting pipe second passage (92) sequentially through a third communicating pipe (23), a third three-way connecting pipe first passage (201), a third three-way connecting pipe third passage (203) and a fourth communicating pipe (14); the third tee joint pipe second passage (202) is sequentially communicated with the auxiliary suction pipe (21) and the auxiliary inlet filter screen (22) and can absorb water from the water tank (26); a first valve (16) is arranged on the first communicating pipe (10), a second valve (2) is arranged on the second communicating pipe (1), a third valve (24) is arranged on the third communicating pipe (23), a fourth valve (15) is arranged on the fourth communicating pipe (14), and an outlet valve (11) is arranged on the outlet pipeline (4); an inlet pressure gauge (13) is arranged on an inlet main pipe (8) of the centrifugal pump (7), an outlet pressure gauge (12) is arranged on an outlet main pipe (6) of the centrifugal pump (7), and a liquid level meter (25) is arranged in the water tank (26) and used for measuring the liquid level height of the liquid level meter; the first valve (16), the second valve (2), the third valve (24), the fourth valve (15), the outlet valve (11), the inlet pressure gauge (13), the outlet pressure gauge (12) and the liquid level gauge (25) are all electrically connected with the controller (27).
2. The centrifugal pump piping system with suction port screen backwashing function of claim 1, wherein the motor (3) is a constant speed motor.
3. The centrifugal pump pipeline system with the suction inlet filter screen backwashing function of claim 1, wherein the first valve (16), the second valve (2), the third valve (24) and the fourth valve (15) are all electric gate valves, and the outlet valve (11) is an electric butterfly valve with an adjustable opening degree.
4. The use method of the centrifugal pump pipeline system with the suction inlet filter screen backwashing function, which is applied to any one of claims 1 to 3, is characterized in that:
carrying out test calibration before the pipeline system is formally operated: first, the main inlet screen (19) is manually checked and cleaned to ensure that it is free of any clogging phenomena; then, the first valve (16) is opened and the second valve (2) is closed,A third valve (24) and a fourth valve (15); then, the centrifugal pump (7) is started, the outlet valve (11) is gradually adjusted from the minimum allowable opening degree to the maximum allowable opening degree, and the gauge pressure value P of the inlet pressure gauge (13) in the adjusting process is continuously recorded according to a fixed time interval1Outlet pressure gauge (12) gauge pressure value P2And the height h of the free liquid level in the pool (26) measured by the liquid level meter (25) from the bottom of the pool (26)w(ii) a Finally, a series of data recorded in the adjustment process are arranged into a data table and stored in a controller (27), the first row and the second row of the data table are respectively an A value and a B value, and the A value and the B value of each column of the data table are calculated by the collected data at the same time in the following mode:
A＝P2-P1 (1)
in the formula, P1An inlet gauge pressure value P measured for an inlet pressure gauge (13)1，P2An outlet gauge pressure value P measured for the outlet pressure gauge (12)2，hwThe height of the free liquid level in the pool (26) from the bottom of the pool (26) measured by the liquid level meter (25) is rho and g which are the density and the gravity acceleration of water respectively;
the operation process of the pipeline system is divided into a normal mode and an abnormal mode, wherein the normal mode is a default operation mode; in a normal mode, the first valve (16) is in an open state, the second valve (2), the third valve (24) and the fourth valve (15) are in a closed state, the outlet valve (11) is in a certain opening degree according to water delivery requirements, and the following steps are executed in a circulating mode according to fixed time intervals:
step z1, measuring the inlet gauge pressure value P1Outlet gauge pressure value P2And the height h of the free liquid level from the bottom of the water tank (26)wCalculating to obtain A value and B value;
step z2, for the value A calculated in the step 1, obtaining a value B' corresponding to the value A by a method of inquiring a data table and performing linear interpolation:
inquiring two A values closest to the A value obtained by the calculation in the step 1 and B values corresponding to the A values in the data table from the data table, and obtaining a B' value in a linear interpolation mode:
wherein A is the value A obtained by calculation in the step 1; a. The1And A2Respectively are two A values which are closest to the A value calculated in the step 1 in the data table and have A1<A2；B1And B2Are respectively the sum of A in the data table1And A2Each corresponding value of B, and A1And B1In the same column, A2And B2In the same column;
step z3, comparing the B value obtained by calculation in the step 1 with the B' value obtained by table lookup and interpolation in the step 2: if B/B' > e, interrupting the execution cycle of the normal mode and entering an abnormal mode; if B/B' is less than or equal to e, maintaining the normal mode and returning to the step 1 to start the next cycle; wherein e is between 1.05 and 1.2;
if the pipeline system enters an abnormal mode, the following steps are sequentially executed:
step y1, closing the first valve (16) and the third valve (24), opening the second valve (2) and the fourth valve (15), adjusting the outlet valve (11) to the maximum allowable opening degree, and maintaining the state for t seconds, wherein t is between 10 seconds and 200 seconds;
step y2, opening the first valve (16) and the third valve (24), closing the second valve (2) and the fourth valve (15), adjusting the outlet valve (11) to the maximum allowable opening degree, and maintaining the state for t seconds, wherein t is between 10 seconds and 200 seconds;
and step y3, closing the third valve (24), adjusting the outlet valve (11) to a certain opening degree according to the water delivery requirement, ending the abnormal mode and returning to the normal mode.
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