CN101122297A - Energy-saving type constant pressure fluid conveying machine parallel arrangement - Google Patents
Energy-saving type constant pressure fluid conveying machine parallel arrangement Download PDFInfo
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Abstract
The invention discloses a an energy-saving constant-pressure parallel connecting device for a fluid conveying machine, and is capable of supplying the gas and water required to every production unit in a large amount in flexible and diverse ways while meeting the condition of constant pressure. The device comprises an eccentric fluid conveying machine with the function of frequency conversion, a manometer, a power meter, a flow meter and a controller. A performance curve of the parallel connecting device, a system resistance curve at the loading side and other files are built into the controller together with the equivalent efficiency curve files provided by the manufacturer via a result of theoretical analysis. When the device is in operation, the files built in and the files actually measured by the manometer, the power meter and the flow meter are compared to get the best energy-saving condition, which will be the guideline for operating of the device.
Description
Technical Field
The invention provides an energy-saving constant-pressure fluid conveying machine parallel device and an operation method, which meet the requirements of safety, rapidness and energy saving of multi-machine parallel operation through academic analysis and verification, and enable an operation reference to be unified and formatted, thereby reducing the construction cost.
Background
In recent years, due to rapid progress of process technology, products are increasingly miniaturized and diversified more and more precisely. In order to produce the precise and miniature diversified products in a large amount and at a low cost, the quality requirements of the current high-tech factory are increasingly strict day by day, and the scale of the factory is continuously enlarged. It poses a challenge to the service personnel who maintain the high-tech factory building or the construction companies who design and build the high-tech factory building, so the relevant personnel have no full capacity to actively seek solution decision or develop new technology to meet the needs.
It is well known that the use of fluid delivery mechanisms to supply water and air at sufficient flow rates and constant pressures to various demand units is an essential requirement that must be met by modern high-tech plants. When the plant scale is small, the flow rate required can be met only by using a single fluid conveying machine, at the moment, because the operation of a single machine is used, the stability control of the pressure is simple and easy, the operation is executed only according to an operation manual provided by a manufacturer of the fluid conveying machine, and the requirement that the fluid pressure is kept stable can be met mostly. However, in order to reduce the production cost and meet the diversification of products, the factory is continuously enlarged in scale and the production process is flexible, so that the single machine can not meet the requirement at all, a multi-machine parallel connection mode is further adopted to provide water and air with sufficient flow and stable pressure for a demand unit, meanwhile, when the production process is changed, the flow and pressure of the water and the air must be changed as soon as possible to meet the requirement of a new process, and when the production process is used in parallel, the operation mode is far more complicated and dangerous than the single machine operation mode, and the machine damage is easily caused carelessly. Machine manufacturers are also unable to provide multiple parallel operating programs. Therefore, no matter the plant construction company or the plant maintenance personnel use the accumulated experience as the reference for the parallel operation of multiple machines. The operation reference planned by the method has various styles and complex specifications, and is not subjected to academic analysis or experimental authentication, so that whether the planned operation reference meets the basic requirements of safety and rapidness cannot be known. In addition, the multi-machine parallel system consumes considerable energy, can effectively reduce the energy consumption and has absolute benefit for reducing the production cost. This energy saving requirement cannot be known from the current operation standard based on experience.
Additionally, when a centrifugal fluid delivery machine such as a pump, blower, etc. is typically purchased, the manufacturer will provide a map of the relevant mechanical properties, such as pressure and flow in FIG. 1, with the vertical and horizontal coordinates representing pressure and flow, respectively. The performance curve of the maximum applicable speed starts from the ordinate and ends at a certain position in the figure. This position represents the critical point of use. The area to the right of this position, which is an unusable area, is known from the analogous theorem (affnity) for fluid-conveying machines from which the relationship between rotational speed (N) and flow rate (Q), pressure (P) and power (HP) is shown below.
Using the data of the performance curve of the maximum applicable rotation speed, the equation of the binomial relation between the pressure (P) and the rotation speed (N) can be obtained by the theory analysis and calculation, such as
P＝C 1 N 2 +C 2 N+C 3 ------(2)
P＝C 1 Q 2 +C 2 Q+C 3 ------(3)
Using equations (2) and (3), the present invention can plot performance curves for each rotational speed below the maximum applicable rotational speed in the graph, as shown by the dashed line. Other equivalence ratio curves, isopower curves, are also typically plotted in the data graph, as shown in FIG. 1.
In the past, a number of patents related to parallel connection devices of fluid conveying machinery have been proposed, and taiwan patent No. 506683 "parallel fan" discloses an integrally formed frame, in which a plurality of fans can be placed in parallel to achieve the purpose of parallel fan. The related art is not mentioned at all as to how to control the rotation of the fans in parallel. Regarding the related art for controlling fluid delivery machines, taiwan patent No. I225908, "method for controlling pump system", discloses a method for automatically controlling the operating parameters related to a centrifugal pump to pump fluid to a discharge port. The scheme is limited to the control of a single centrifugal pump, and the control method utilizes the sensors arranged on the pump to measure the suction and discharge port pressure, the differential pressure, the pump rotating speed, the water temperature and other data, compares the data with the prestored data, and adjusts according to the difference between the data and the prestored data. In addition, taiwan patent No. M253699, "a device for controlling a pump system", discloses various devices for controlling a single centrifugal pump, which is similar to the operation of the previous case. The pre-stored data of the cases are obtained by using a large amount of implementation data, rather than by mathematical derivation. The advantage of this method is that it can easily and quickly know the various states of the pump as the basis for control. However, there are two limitations, one is only suitable for single machine operation and can not be used in parallel with multiple machines. And the second is that the control range is limited by various items of data stored in advance. Whether the operation process is energy-saving or not cannot be known at all.
Disclosure of Invention
The invention aims to provide an energy-saving constant-pressure parallel device of a fluid conveying machine, which can supply gas and water required by production to each production unit in a large amount and flexibly and variously under the condition of constant pressure.
Therefore, the invention provides an energy-saving constant-pressure fluid conveying machinery parallel device, which is formed by connecting a performance curve of the constant-pressure fluid conveying machinery parallel device, a system impedance curve and an equivalent ratio curve of a load side and other data in parallel and a multi-component branch system, wherein the branch system comprises:
the device comprises a centrifugal fluid conveying machine with a frequency conversion function, a pressure gauge, a power meter, a flow meter and a controller.
Preferably, the performance curve data of the parallel device of the constant pressure fluid delivery machine can be calculated according to the relation between the flow rate and the pressure of the parallel fluid delivery machine.
Preferably, the data of the system impedance curve on the load side can be obtained by calculating the relationship between the flow and the impedance derived from the pipeline configuration on the load side.
Preferably, the equivalent ratio curve data can be stored in a database of flow and pressure functions instead of data provided by the machine manufacturer.
Preferably, the centrifugal fluid conveying machine with frequency conversion function can be formed by a centrifugal pump with frequency conversion function.
Preferably, the centrifugal fluid conveying machine with frequency conversion function can be composed of a centrifugal air extractor with frequency conversion function.
Preferably, the centrifugal fluid conveying machine with frequency conversion function can be composed of a centrifugal air feeding mechanism with frequency conversion function.
Preferably, the pressure gauge is used for detecting the fluid pressure of the fluid conveying pipeline so as to ensure a constant pressure state.
Preferably, the power meter is used for measuring the output power of the centrifugal fluid conveying machine with frequency conversion function, and the flow rate is obtained by substituting the measured power into a formula of flow rate = (power × constant)/(pressure), wherein the constant is a unit conversion value.
Preferably, the flow meter is used for measuring the output flow of the centrifugal fluid conveying machine with frequency conversion function, so as to ensure that the flow output by each machine is the same.
Preferably, the controller may be a Programmable Logic Controller (PLC) or a computer, and is configured to build in the performance curve data of the parallel device of the constant pressure fluid conveying machine as described above and execute the operation.
Preferably, the controller may be a Programmable Logic Controller (PLC) or a computer, which is embedded with the data of the system impedance curve on the load side as described above and performs the operation.
Preferably, the controller may be a Programmable Logic Controller (PLC) or a computer, which has the equivalent ratio curve data as described above built therein and performs the calculation.
Preferably, a Programmable Logic Controller (PLC) can control the rotation speed of the centrifugal fluid conveying mechanical pump, the exhaust fan and the air blower with frequency conversion function according to the operation result.
Preferably, the computer can control the rotation speed of the centrifugal fluid conveying mechanical pump, the exhaust fan and the blower with frequency conversion function according to the operation result.
The details of the "parallel connection device of energy-saving constant-pressure fluid transportation machine" related to the present application are sequentially introduced by the following theoretical analysis formula derivation and the following example description. When a plurality of centrifugal fluid conveying machines are connected in parallel, the flow distribution condition of the load side pipeline system needs to be calculated firstly because the flow distribution condition is closely related to the flow of the load side pipeline system.
The piping system on the load side of the parallel device of the fluid transfer machine of fig. 2 will be described as an example. The total number of the pipe sections ((1) to (9)) and 10 nodes (1 to 10) including the fluid inlet and outlet and the confluence point, that is, both end points of all the pipe sections) are provided. Where nodes 1, 2, 5, 6 are branch inlets and nodes 9 and 10 are total outlets. A fluid transport mechanism is provided on each of the tubes 8, 9, and arrow symbols (←) on the drawings are used to determine the position of a fake in the programThe direction is not intended to represent the actual direction of fluid flow. The whole system requires the flow Q of each pipe section n The subscript n is the pipe section number and represents the flow rate of the different pipe sections. There are 9 unknowns (Q) because there are 9 pipe sections 1 ’Q 2 ’…’Q 9 ) 9 linearly independent equations are required to solve. Using the continuous equation established by flow conservation at the node, such as node 3, the flow in pipe 3 is equal to the sum of the flows in pipes 1 and 2. Can be expressed as formula (4)
Q 1 +Q 2 -Q 3 ＝0 (4)
Similarly, nodes 4, 7 and 8 can write three flow conservation equations of formula (5), formula 6 and formula (7)
Q 3 +Q 4 -Q 5 ＝0 (5)
Q 5 +Q 6 -Q 7 ＝0 (6)
Q 7 -Q 8 -Q 9 ＝0 (7)
The other nodes ( nodes 1, 2, 5, 6, 9 and 10) have no traffic conservation relationship and therefore cannot write a traffic equation that can be used to solve.
The other 5 equations needed for the solution can be derived from the concept of conservation of energy. Considering pipe 3, the nodes at the two ends are node 3 and node 4, respectively, if the flow flows from node 3 to node 4, it means that node 3 has a larger full pressure value than node 4, and the fluid flowing through pipe 3 will cause the loss of full pressure due to friction or pipeline structure, and is expressed as Δ P 3 The full voltages at node 3 and node 4 are denoted P 3 And P 4 Then the relationship of two nodes can be written as
ΔP 3 ＝P 3 -P 4 (8)
Total pressure loss Δ P of pipe 3 3 And can be represented by K 3 Q 3 2 (will be described later), wherein K 3 Represents the total loss coefficient of the tube 3, so equation (8) can be written as
Each pipeline has different structures and devices, so that the full pressure loss coefficients K have different values, and the full pressure loss coefficients of different pipe sections are distinguished by subscripts. The left side of the equal sign of the formula (9) contains an unknown number Q 3 And the unknown number on the right of the equal sign is P 3 And P 4 This adds one equation but two more unknowns. Assuming that the full pressure conditions at all ports are known (i.e., nodes 1, 2, 5, 6, 9, and 10), when fluid is flowing from node 1, it flows through tubes 1, 3, 5, 7, and 79, finally, flow out of node 10, using equation (8)Can be written as
ΔP＝P 1 -P 10 (10)
Wherein Δ P is the total of the total pressure loss of each pipe section and the total pressure changed by the fluid conveying machine, and is expressed by a mathematical formula
ΔP＝ΔP 1 +ΔP 3 +ΔP 5 +ΔP 7 +ΔP 9 -ΔP s9 (11)
Wherein Δ P s9 For the value of the total pressure changed by the fluid-conveying machine while passing through the pipe 9, it will be mentioned later how to handle Δ P s9 . Can be written by substituting formula (11) for formula (10)
ΔP s9 -ΔP 9 -ΔP 7 -ΔP 5 -ΔP 3 -ΔP 1 ＝P 10 -P 1 ＝C 1 (12)
Because of P 10 And P 1 Is known, usually ambient atmospheric conditions, and therefore C 1 Is a constant. Finally, the delta P is changed into KQ 2 Of the type (1), can obtain
Other equations can be obtained analogously, respectively
From formula (4) to formula(7) And equations (13) to (17) have a total of 9 linearly independent equations, in which Δ P is present in addition to the 9 flow unknowns s8 And Δ P s9 Two unknowns, which must be determined from the performance curve of the fluid conveying machine.
The prior formula (3) is well matched by using a quadratic polynomial expression, so that the performance curve of the fluid conveying machine at a certain fixed rotating speed can be written into
Wherein C is S1 、 C S2 、 C S3 、 C S1 ′、C S2 ' and C S3 ' both are constant, and the subscript S denotes the fluid transport machine.
Each of the left-hand side terms of formulae (13) to (17) etc. (except for Δ P) s8 And P s9 ) All are a full pressure loss coefficient multiplied by the square of the pipeline flow. Therefore, in order to reduce Δ P s8 And Δ P s9 Incorporating the calculation of the equation set, the equations (18) and (19) are written by the fitting method
Wherein
Substituting formula (21) into formula (13) to obtain
Similarly, equations (14) to (17) may be substituted with equations (20) and (21). It can be found that the left side of the equal number has G except that the flow is unknown 8 And G 9 Two unknowns, and therefore two sets of equations need to be added, i.e., one more unknowns is added to one fluid transport machine. G can be written out by the process of the formula 8 And G 9 In relation to the flow of the pipe
Therefore, the current system has 11 equations and 11 unknowns in total, and all the pipeline flows can be solved.
K of formulae (13) to (17) n (n =1, 2, 9.. Times., 9) are known numbers, which are the total pressure loss coefficient of the pipeline, and include two parts, namely, the loss of fluid flowing through the pipeline due to friction, and the minor loss (MinorLoss) caused by various devices and fittings installed in the pipeline system, so that the K value of each loss coefficient can be obtained by examining the pipeline loss coefficient.
When fluid delivery machines of the same model are connected in parallel, the flow rate of the performance curve increases by a factor as the number of fluid delivery machines in parallel increases. Fig. 3 is a performance curve of different numbers of fluid delivery machines connected in parallel at a fixed rotation speed. Comparing the performance curves of the single fluid conveying machine and the two fluid conveying machines connected in parallel on the drawing, under the condition of providing the same pressure, the flow provided by the two fluid conveying machines connected in parallel is twice of that provided by the single fluid conveying machine. Likewise, three parallel units provide three times the flow rate at the same pressure. In other words, the overall performance curve changes with different numbers of fluid delivery mechanisms connected in parallel. If the performance curve of a single fluid conveying machine is
P＝C s1 Q 2 +C s2 Q+C s3 (25)
Wherein C is s1 、C s2 、C s3 Is constant, Q n (n =1, 2, 3,. And n) represents the flow rate for a combination of parallel fluid delivery machines, and the subscript n represents the number of fluid delivery machines. When n fluid conveying machines are connected in parallel, under the same pressure condition, the flow rate can be changed into n times, namely Q n Is represented by the formula (25) = n.Q
Equation (26) is a performance curve equivalent to that of a single fluid transport machine.
A complex pipeline system, if the system setting is unchanged, the total pressure loss of the system is in direct proportion to the square of the total flow, and a P-Q diagram is drawn to form a curve, namely a system impedance curve. Can be written as
Wherein K sys Is a fixed constant, Q sys Is the total flow of the system, Δ P sys Is the total pressure loss of the system. Therefore, the impedance curve of the system can be obtained by knowing the pressure of the system at a certain flow rate under the condition that the system is not changed. Fig. 4 is a cross point of the system impedance curve and a single fluid delivery machine, where the flow and pressure are the corresponding points, i.e., the total flow of the system and the total pressure loss of the system, and therefore referred to as the operating point. In the pipeline system of a single fluid conveying machine, if the performance curve and the system impedance curve of the fluid conveying machine are known, the total flow of the system is equal to the pressure provided by the fluid conveying machine because the total pressure loss of the system is equal to the pressure provided by the fluid conveying machineThe flow rate of the fluid conveying machine is obtained by substituting the formula (27) into a performance curve equation
The flow Q of the intersection point (operating point) of the two curves can be obtained by a formula method sys
The fluid conveying machine with a certain fixed rotating speed is arranged in a pipeline system, and the flow rate can be obtained by the formula (29). If the determined flow rate is not the expected value, the rotation speed of the fluid transfer machine can be changed and adjusted. When the rotating speed of the fluid conveying machine is different, the performance curve of the fluid conveying machine is different, and the operating point is changed accordingly. The performance curve of the fluid conveying machine can be calculated by a similar theorem (affinity Law), and the relation (1) of the flow rate and the rotating speed, the pressure and the rotating speed, and the power and the rotating speed is shown.
Fig. 5 is a graph illustrating the performance curves of a fluid delivery machine at 1750rmp and 2275rpm, where points a and B are operating points at different speeds for a fixed system. The formula (27) can obtain a relational expression between the points A and B
From equation (1), point A on the 1750rmp performance curve is calculated as point C on the 2275rmp performance curve, and the two-point relationship can be written as
Substituting formula (31) into formula (32)
Comparing the equations (30) and (33), it can be found that the point B is the point C, i.e. the known operating point a, i.e. the operating point B of the different speed performance curves and the system impedance curves can be calculated by using the similar theorem. If the point B is the target flow and pressure of the system, but the required rotation speed of the fluid delivery mechanism is unknown, the parameter K can be calculated by the equation (27) sys Can be written as
The performance curve of the fluid transport machine 1750rpm is shown in the formula (25), and the required numbers of the formula (25) and the formula (37) are substituted into the formula (29) to obtain the system flow Q A . Then, the formula (1) is used to obtain N sys
The original rotation speed of the fluid conveying machine is adjusted to N sys The required flow can be obtained. The equation after the rotational speed of the fluid delivery machine is adjusted by the formula (1) is
The coefficient is arranged to obtain
Using the above principles, a plant pipeline configuration is shown as FIG. 6, FIG. 7 is the relevant data, FIG. 8 is the performance curve of a single plant, and the equation for the performance curve is
P＝-0.8889Q 2 +6.6667Q+700 (38)
This example addresses the situation where three fluid handling machines are connected in parallel, each fluid handling machine being of the same type and rotational speed. Three fluid conveying machines are equivalent to a single fluid conveying machine, and the parallel performance curve obtained by the formula (26) is
P＝-0.0988Q 2 +2.2222Q+700 (39)
K is obtained from the formula (27) sys
Formula (39) and formula (40) substituted by formula (29)
However, the total flow required by the system is only 40cfs, and the total flow 41.9cfs is calculated as shown in fig. 9, so that the rotation speed of the fluid delivery mechanism must be reduced. Suppose that the rotation speed of equation (38) is 1750 rpm From formula (35) can be obtained
From the equation (37), the equation when the rotation speed of the single fluid transportation machine is reduced to 1670rpm is given
P＝-0.8889Q 2 +6.3619Q+637.46 (41)
The total flow obtained after recalculation of the fluid delivery machine by method one was 40cfs, as detailed in figure 10 for three machines in parallel, with nearly equal outlet flows and consistent pressures.
In the same way, the required rotation speed when the two machines are connected in parallel can be obtained, and the rotation speed must be increased to 1850rpm so as to meet the system requirement. As shown in the results of the two-machine parallel connection in fig. 10, the flow rates at the outlets are almost the same, and the pressure error value is only within 2% of the system requirement.
The curvature of equivalence ratio is obtained by the manufacturer according to the actual performance test of the machine, as shown in fig. 1, and cannot be derived from theory. Therefore, only the data provided by the manufacturer can be directly used.
Drawings
FIG. 1 is a data diagram of a centrifugal fluid delivery machine.
FIG. 2 shows a parallel arrangement of multiple centrifugal fluid handling machines and a load-side piping system.
Figure 3 shows performance curves for a single, two and three fluid transport machines in parallel.
Fig. 4 shows a fluid transport machine performance curve versus a system impedance curve.
Figure 5 shows the performance curves and system impedance curves for a fluid delivery machine at 1750rpm and 2275 rpm.
Fig. 6 shows the piping structure on the load side.
FIG. 7 shows the data for the various sections of the system and the working fluid.
FIG. 8 shows a performance curve for a fluid delivery machine at 1750 rpm.
FIG. 9 shows the distribution of the flow rate at each outlet for a 1750rpm fluid delivery machine.
FIG. 10 shows the respective outlet flow distribution for a fluid delivery machine at 1670 rpm.
FIG. 11 shows the system flow demand Q T Pressure requirement of P T And meanwhile, the performance curve of the parallel connection of the single machine and the double machines.
FIG. 12 shows the performance curves for two-machine and three-machine parallel.
FIG. 13 shows a pressure and flow data plot including an equivalent curve.
FIG. 14 shows a conventional method and a pressure operation method according to the present embodiment.
FIG. 15 shows the layout of the elements of the device.
Fig. 16 shows a system control architecture diagram.
Description of reference numerals:
61: a centrifugal fluid conveying machine with frequency conversion function.
62: power meter
63: pressure gauge
64: flow meter
65: controller for controlling a motor
66: load side
Detailed Description
When applied to actual conditions, the allowable operation time is short, and the desired result cannot be obtained by calculating the formula obtained by the above theoretical derivation, so that the result obtained by using the above formula must be directly used in the actual conditions.
Suppose the flow required by the system is Q T At a constant pressure P T When a certain brand pump (in principle, the same brand and the same type are used) is selected, the single pump can provide the maximum flow Q 1 Maximum pressure of P 1 . Basic data shows that if Q t ＞Q 1 One pump cannot meet the flow demand, and P 1 ＞P T The pressure can meet the requirement.
The traditional operation mode is as follows: (the system impedance can be calculated from the piping configuration diagram and the flow rates through each piping, i.e., the system impedance at each flow rate can be obtained and plotted as a system impedance curve).
(1) The first pump was turned on, as shown in fig. 11, and the demand could not be met, the single unit performance curve (solid line) could not meet the system impedance curve at operating point O, P = P T ，Q＝Q T 。
(2) And starting the second pump according to the same conditions of the first pump, wherein the performance curve (- - -) formed by the parallel connection of the two pumps and the system impedance curve meet at an X point above an operation point O and is larger than the system requirement, and the rotating speed of the two pumps is timely reduced to reduce the performance curve (- -) and meet at the operation point O.
(3) If the third pump is additionally started, the operation mode is similar to the operation mode of the double parallel connection, and the rotation speed of each pump is adjusted in time, so that the performance curve and the impedance curve of the 3 parallel systems can be intersected at an operation point O, as shown in fig. 12.
(4) Similarly, the number of the starting pumps is continuously increased, and as long as the rotating speed of each pump is properly adjusted, the performance curve and the system curve of the parallel pumps can be intersected at the operating point O.
(5) More than two pumps are connected in parallel in the system, so that the flow and pressure requirements of the system can be met. But in view of energy saving, the aim of saving energy most can be achieved by connecting a plurality of the devices in parallel. In addition, when the system flow demand changes and the system impedance curve changes, how to adjust the number of the parallel connection units can achieve the best state. It is an important subject to be solved by the present invention.
It is known from the pump theory that when a plurality of pumps are connected in parallel, if the output flow Q of each pump is the same, the energy-saving state is easily obtained. Example (c): q 1 ＝Q 2 ＝Q 3 Is in a state of Q 1 ≠Q 1 ≠Q 3 The state of (1) is energy-saving. Therefore, it is the primary task to make the output flow Q of each pump the same.
In order to obtain the same flow rate of each pump, a power meter is arranged on each pump, and the flow rate Q of each pump can be calculated by using the data measured by the power meter, and the formula is as follows
P is the system pressure and must be stable, constant is the product of unit conversion value and pump efficiency, each state is the same, and the efficiency should also be the same. Knowing the power HP, the flow Q can be determined, i.e. HP if the power of the pumps is the same 1 ＝HP 2 ＝HP 3 Then Q is obtained 1 ＝Q 2 ＝Q 3 。
If a flowmeter is installed in each pump, the flow rate Q can be directly measured, but the flowmeter error is large, the response speed is slow, and the use of a power meter is more convenient.
The method can be used when a plurality of pumps are connected in parallel, and a better energy-saving state is obtained. However, it is still impossible to determine the number of pumps to be used in parallel, which is optimal. Such as Q 1 ＝Q 2 ＝Q 3 Preferably, or Q 1 ＝Q 2 Is better.
The system takes 2 pumps in parallel as an example, and 2 parallel performance curves and the performance curve of the state in each pump are respectively adjusted by a front power meter
And a constant pressure requirement P 1 ＝P 2 ＝P T ) Collectively plotted on a pressure-flow meter, as shown in fig. 12.
The dotted line is a performance curve of 2 pumps connected in parallel, the rotating speed of each pump is properly adjusted, the dotted line can be intersected with the system impedance curve at an operating point O, the solid line is a performance curve of each pump, and O on the curve 2 Is counted as a flow
Pressure of P T A point of (c). When 3 parallel units are connected in parallel, the performance curves of the 3 parallel units and the performance curves of the respective units in this state are adjusted by the power meter
And meets the requirement of constant pressure P 1 ＝P 2 ＝P 3 ＝P T ) In FIG. 12. A dotted line (-. Cndot. -) shows 3 parallel performance curves, and the same appropriate adjustment of the pump speeds can intersect the system curve at the operating point O. O is 3 The point is that the flow rate is
Pressure of P T The position of (a). When 2 parallel-connected units and 3 parallel-connected units are connected in parallel, the system P can be achieved T 、Q T Although the pressure P of each pump used in parallel connection T But supplied with flow rates of respectively
And
indicating different rotation speeds of two parallel systems and a seating point Q 2 And Q 3 As well as different.
As mentioned above, manufacturers provide equal efficiency maps for each pump. By plotting the iso-efficiency map in fig. 12, fig. 13 can be obtained.
The dashed lines of the hyperbolic curves are respectively illustrated as equal efficiency (η), 70%, 60%, 50% curves, and are directly plotted from data provided by the machine manufacturer. The dotted line is the connection of the valley of each equivalent ratio curve, since it is necessary to achieve a constant pressure P T Limitation of (2), Q 2 And Q 3 And point O will be at the same P T On the horizontal line of (a). Taking the figure as an example, O 2 Point is 60% efficiency, and Q 3 About 65% efficiency, then parallel total output power (HP) T The output power (HP) can be output by a single machine Single machine Multiplied by the number n of parallel stations.
(HP) T ＝(HP) Single machine X number of parallel units (n) (43)
From the formulae (45) and (46), (HP) T3 Less than (HP) T2 Represents the total output work of 3 parallel-connected devicesThe rate will be less than the total output power of 2 parallel connections, i.e. in this state 3 parallel connections are more energy efficient than 2 parallel connections.
The system impedance curve changes as the supply flow rate of the system changes in response to production demand, and shifts to the right and vice versa as the flow rate increases. When the flow rate is increased, as in the foregoing principle, the solution can be divided into two ways: (1) The number of the pumps used is not increased, but the number of the pumps used at present is increased, so that the purpose of increasing the flow is achieved. (2) The number of the used pumps is increased, the rotating speed is not required to be increased, even the rotating speed is reduced, and the purpose of increasing the flow is achieved. The highest selection is selected, the parallel total power of the two paths can be obtained according to the above principle, and the operation principle of selecting the one with the lower parallel total power is selected. When the flow rate is reduced, the same principle can be solved in two ways: (1) The number of the pumps used is not reduced, but the rotating speed of the pumps used at present is reduced, so as to achieve the purpose of reducing the flow. (2) The number of pumps used is reduced, the rotating speed is not required to be reduced, even the rotating speed is increased, and the purpose of reducing the flow is achieved. In which case, the operation principle is to be selected to be the one with lower total power in parallel, similarly to the above method.
When the system impedance curve is changed, no matter the process of selectively increasing or decreasing or even maintaining the original number of pumps, the important operation action of changing the pump speed is derived. It is well known that in high-tech precision factories, great importance is attached to the maintenance of a standard or set operating environment, and improper changes in the operating environment will seriously jeopardize the product in the manufacturing process. The newspaper smells that the short-term voltage supply of the power system is unstable, and the paper immediately causes the damage of manufacturers in the area. Similarly, when the pump speed changes, the pressure of the supply fluid changes according to the principle of the performance curve, and the change in the fluid pressure is as much as the voltage of the power system changes. With some carelessness, the damage of the factory can be immediately caused. At present, the time for allowing adjustment of a common operating system is very short, and the pressure is changed by changing the rotating speed, so that the operating system needs reaction time to tend to be stable. Therefore, when the flow rate needs to be increased, the rotating speed is usually increased rapidly, when the pressure is found to exceed the constant pressure setting, the rotating speed is reduced, and when the pressure is found to be lower than the constant pressure setting, the rotating speed is increased again to increase the fluid pressure. Therefore, after a period of time, the rotating speed is repeatedly adjusted, and finally the requirement of setting constant pressure is met. The change in pressure (P) versus time (T) can be represented by the dashed line in fig. 14.
The pressure P of the fluid is the source of the driving force, and the improper variation of the pressure of the fluid in the system will cause the sudden change of the supply flow rate at the outlet end, which will cause an absolute damage to the product in the manufacturing process, and this condition will always bother manufacturers and operation and maintenance personnel. As for the reduction of the flow demand, it is also unknown how the pump speed should be reduced or even the number of used pumps should be reduced, and therefore, most of them take the measures that should not change, that is, maintain the system operation condition, and the excess flow becomes the backflow. At this time, it is obvious that precious energy is wasted wastefully, which is a big regret.
The invention has rapid and energy-saving measures aiming at the flow increasing and decreasing process. It can be seen from the foregoing that the method of the present invention can rapidly determine the optimum number of pumps and the rotation speed of each pump when the system impedance curve changes (i.e., the flow rate changes), so that the rotation speed of the pump can be rapidly and directly adjusted to a state slightly lower than the optimum rotation speed, i.e., a slightly lower constant pressure setting, and the rotation speed is then finely adjusted to the optimum rotation speed after the pressure change is confirmed. The change may be as in the solid line change condition of fig. 14. At this time, the fluid pressure in the system will not change in magnitude, and the supply flow at the outlet end will not be suddenly changed. Has a tremendous contribution to the stability of the processed product.
According to the requirements of the above embodiments, the parallel connection device of energy-saving constant pressure fluid delivery machine of the present invention can be composed of a plurality of centrifugal fluid delivery machines 61 with frequency conversion function, power meters 62, pressure meters 63, flow meters 64, controllers 65 and load side devices 66, as shown in fig. 15, and the respective functions and the interrelation relationship therebetween, the control procedure can be obtained from the system control architecture of fig. 16.
From the above data, the energy-saving parallel connection device for constant-pressure fluid transportation machinery provided by the present invention calculates various required data of the fluid transportation machinery in the parallel connection device through theoretical analysis and formula derivation, and controls each parallel connection machinery according to the data, thereby achieving the purpose of safe and fast operation. In the process, different efficiencies can be obtained for different machines connected in parallel, so that the most energy-saving machine number can be found. Therefore, the technical content disclosed in the present application is completely different from the content of the above-mentioned published patent application, and the novelty and the advancement presented by the result of the research and development of the present application are undoubted, and can assist the international technical manufacturers to greatly reduce the cost and increase the international competitiveness.
Claims (18)
1. An energy-saving constant-pressure fluid conveying machinery parallel device is formed by connecting a performance curve of the constant-pressure fluid conveying machinery parallel device, a system impedance curve of a load side, an equivalent ratio curve and a multi-component branch system in parallel, and is characterized in that a branch system comprises:
the device comprises a centrifugal fluid conveying machine with a frequency conversion function, a pressure gauge, a power meter, a flow meter and a controller.
2. The parallel device of energy-saving constant pressure fluid transportation machine as claimed in claim 1, wherein the performance curve data of the parallel device of constant pressure fluid transportation machine can be calculated according to the relationship between the flow rate and the pressure of the parallel fluid transportation machine.
3. The parallel connection apparatus for energy-saving constant pressure fluid transportation machine according to claim 1, wherein the data of the system impedance curve at the load side can be obtained by calculating the relationship between the flow rate and the impedance derived from the pipeline configuration at the load side.
4. The parallel device for energy-saving constant pressure fluid delivery machine as claimed in claim 1, wherein the equivalent ratio curve data can be stored in a database of flow and pressure functions by changing the data provided by the machine manufacturer.
5. The parallel connection device of energy-saving constant-pressure fluid delivery machine according to claim 1, wherein the centrifugal fluid delivery machine with frequency conversion function is composed of a centrifugal pump with frequency conversion function.
6. The parallel connection device of energy-saving constant-pressure fluid delivery machines according to claim 1, wherein the centrifugal fluid delivery machine with frequency conversion function is composed of a centrifugal blower with frequency conversion function.
7. The parallel device of energy-saving constant-pressure fluid delivery machines according to claim 1, wherein the centrifugal fluid delivery machine with frequency conversion function is composed of a centrifugal blower with frequency conversion function.
8. The parallel device of energy-saving constant pressure fluid delivering machine according to claim 1, wherein the pressure gauge is used to detect the fluid pressure of the fluid delivering pipeline to ensure the constant pressure state.
9. The parallel device of energy-saving constant pressure fluid transportation machine according to claim 1, wherein the power meter is used to measure the output power of the centrifugal fluid transportation machine with frequency conversion function, and the power measured by the power meter is substituted into the formula of flow = (power x constant)/(pressure) to obtain the flow rate, wherein the constant is a unit conversion value.
10. The parallel device of energy-saving constant-pressure fluid delivery machines according to claim 1, wherein the flow meter is used to measure the output flow of the centrifugal fluid delivery machine with frequency conversion function, so as to ensure the output flow of each machine to be the same.
11. The parallel device of energy-saving constant-pressure fluid delivery machine as claimed in claim 1, wherein the controller is formed by a programmable logic controller and performs the calculation of the performance curve data of the parallel device of constant-pressure fluid delivery machine.
12. The parallel energy efficient constant pressure fluid delivery machine assembly as recited in claim 1, wherein the controller is configured as a programmable logic controller and implements computation of load side system impedance profile data.
13. The parallel device of energy-saving constant pressure fluid transportation machine as claimed in claim 1, wherein the controller is composed of programmable logic controller and executes the equivalent ratio curve data.
14. The energy-saving parallel connection device for constant pressure fluid delivery machines as claimed in claim 1, wherein the controller is formed by a computer and performs the calculation of the performance curve data of the parallel connection device for constant pressure fluid delivery machines.
15. The parallel energy-efficient constant-pressure fluid-transporting machine as claimed in claim 1, wherein the controller is formed by a computer and performs the operation of the system impedance curve data on the load side.
16. The parallel device of energy-saving constant pressure fluid delivering machine according to claim 1, wherein the controller is formed by a computer and executes equivalent ratio curve data.
17. The parallel device of energy-saving constant pressure fluid transportation machines according to claim 11, wherein the programmable logic controller controls the rotation speed of the centrifugal fluid transportation machine pump, the suction fan and the blower with frequency conversion function according to the operation result.
18. The parallel connection device of energy-saving constant pressure fluid transportation machine according to claim 14, wherein the computer controls the rotation speed of the centrifugal fluid transportation machine pump, the suction fan and the blower with variable frequency according to the calculation result.
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| CN200610115451A CN100580256C (en) | 2006-08-10 | 2006-08-10 | Energy-saving type constant pressure fluid conveying machine parallel arrangement |
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| CN200610115451A CN100580256C (en) | 2006-08-10 | 2006-08-10 | Energy-saving type constant pressure fluid conveying machine parallel arrangement |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103452824A (en) * | 2013-09-06 | 2013-12-18 | 武汉理工大学 | Fan and water pump energy saving system adopting minimum power algorithm based on flow-power curve |
| CN104154005A (en) * | 2014-07-08 | 2014-11-19 | 扬州大学 | Diesel engine pump station speed governing optimizing operation method based on lowest unit flow fuel consumption |
| CN106643919A (en) * | 2016-08-24 | 2017-05-10 | 福建龙净环保股份有限公司 | Gas flow measuring method and device |
| CN113944645A (en) * | 2020-07-15 | 2022-01-18 | 依必安派特穆尔芬根有限两合公司 | System and method for optimally adjusting multiple fan arrangements |
-
2006
- 2006-08-10 CN CN200610115451A patent/CN100580256C/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103452824A (en) * | 2013-09-06 | 2013-12-18 | 武汉理工大学 | Fan and water pump energy saving system adopting minimum power algorithm based on flow-power curve |
| CN104154005A (en) * | 2014-07-08 | 2014-11-19 | 扬州大学 | Diesel engine pump station speed governing optimizing operation method based on lowest unit flow fuel consumption |
| CN104154005B (en) * | 2014-07-08 | 2016-01-20 | 扬州大学 | Based on the diesel engine pumping plant speed governing optimizing operation method that specific discharge fuel consumption is minimum |
| CN106643919A (en) * | 2016-08-24 | 2017-05-10 | 福建龙净环保股份有限公司 | Gas flow measuring method and device |
| CN106643919B (en) * | 2016-08-24 | 2020-06-30 | 福建龙净环保股份有限公司 | Flue gas flow measuring method and measuring device |
| CN113944645A (en) * | 2020-07-15 | 2022-01-18 | 依必安派特穆尔芬根有限两合公司 | System and method for optimally adjusting multiple fan arrangements |
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| CN100580256C (en) | 2010-01-13 |
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