CN1667210A - Constant pressure water supply control device and method - Google Patents

Abstract

The invention discloses a constant pressure water-supply control device and the method, which includes PLC controller, drive and protection unit, the first frequency conversion pump and at least one power frequency pump. The input end of the PLC controller connects to pressure feedback signal, and the output end is connected to drive and protection unit, the input end of the first frequency conversion pump. The output of the drive and protection unit is separately connected to the first frequency conversion and at least one power frequency pump. The feature is that the output of the PLC controller and the drive and protection unit is connected to a second frequency conversion pump. The invention would improve the effect of energy conservation.

Description

Constant pressure water supply control device and method

Technical field

The present invention relates to a kind of constant pressure water supply control device and method.

Background technology

The hydraulic pressure of pipe network can only guarantee the water of building below 4 layers in the general city, and all the other each layers of top must " promote " hydraulic pressure could satisfy the water requirement.Adopted water tower, high level cistern or air pressure pot type supercharging equipment mostly, but they all must promote the water yield with the pressure that exceeds the actual used water height by water pump, its result has increased the shaft power and the energy loss of water pump in the past.Varying speed and constant pressure feed water is a kind of energy-conservation effective way, and it adopts ac variable speed technology to satisfy the requirement of constant pressure water supply, has avoided the energy dissipation of supplying water and causing owing to superpressure.But varying speed and constant pressure feed water all is to adopt a pump variable frequency at present, and the mode of many water pump power frequencies supplies water.The relation curve of lift H and flow Q when a variable frequency pump, two main frequency water pump operations have been shown among Fig. 3, curve 1,2 is for passing the isoeffect curve of 2 of A, B, and curve I is that the separate unit water pump is at rated revolution n _oThe time characteristic curve, curve I is that the separate unit water pump is at minimum revolution n _MinThe time characteristic curve, curve II is that two water pumps are at rated revolution n _oThe time characteristic curve, A to B is the efficient district of main frequency water pump among the figure, by above-mentioned than the rule as can be known, when pump rotary speed by n _oBe adjusted downward to n _MinThe time its efficient district for parabola 1 and 2 folded scopes be, if setting constant voltage value is H _b, as seen from the figure, the flow during 2 water pump power frequencies is Q _c, during 1 frequency conversion of 2 power frequencies, the minimum discharge of water pump parallel running is Q in efficient district _d, obvious Q _d＞Q _c, because the operating point of pipe network is arbitrarily, when flow Q at Q _cWith Q _dBetween when changing, the operating point of frequency modulation water pump will drop on outside the efficient district, that is to say the frequency modulation pump working in the poor efficiency district, thereby causes energy dissipation.

Summary of the invention

The object of the present invention is to provide a kind of constant pressure water supply control device and method of simple in structure, good energy-conserving effect, operate in the shortcoming that " poor efficiency district " wastes energy to overcome in the constant pressure water supply system separate unit frequency modulation water pump.

Another object of the present invention provides a kind of constant pressure water supply method.

For achieving the above object; the present invention includes the PLC controller; drive and protected location; first frequency converter; first water pump and at least one general pump; the input of PLC controller is connected to pressure feedback signal; its output connects respectively and drives and protected location; the input of first frequency converter; drive the input and at least one general pump that connect first frequency converter with the output of protected location respectively; output termination first water pump of first frequency converter; it is characterized in that: the output of described PLC controller and driving and protected location also is connected to second frequency converter, output termination second water pump of second frequency converter.

Constant pressure water supply method of the present invention may further comprise the steps:

Air pressure tank is set, and pressure store water;

Two frequency modulation water pumps and at least one main frequency water pump are set;

Water pump satisfies: α 〉=β, α=Q _b/ Q _a, $\mathrm{\β}=2\sqrt{H_b/H_a}.$

The minimum lift value in the said method in the efficient section of water pump constant voltage value water intaking pump or the 105%-140% of minimum lift value.

Advantage of the present invention: adopt in the constant pressure water supply system of two frequency modulation water pumps, when the water pump parameter satisfies: during α 〉=β, α=Q _b/ Q _a $\mathrm{\β}=2\sqrt{H_b/H_a},$ The pump capacity of parallel operation is continuous, and two frequency modulation water pumps all are operated in efficient district, operates in the shortcoming that " poor efficiency district " wastes energy thereby overcome in the constant pressure water supply system separate unit frequency modulation water pump, has improved energy-saving effect.

The present invention is further illustrated below in conjunction with the drawings and specific embodiments.

Description of drawings

Fig. 1 is a structural representation of the present invention.

Fig. 2 is the constant pressure water supply system that comprises two frequency modulation water pumps.

Fig. 3 is an identical variable frequency pump of model, the Q-H performance diagram of two main frequency water pump parallel operations.

Fig. 4 is two identical variable frequency pumps of model, the Q-H performance diagram of a main frequency water pump parallel operation.

Fig. 5 is the Q-H characteristic curve of water pump.

The specific embodiment

As shown in Figure 1; the present invention is by PLC controller 1; drive and protected location 2; first variable frequency pump 3; second variable frequency pump 4; first main frequency water pump 5; second main frequency water pump 6 is formed; the input of PLC controller 1 is connected to pressure feedback signal and switching signal; the input of its output and driving and protected location 2 couples; drive output termination first frequency converter 3 with protected location 2; the input of second frequency converter 4; drive output termination first variable frequency pump 3 with protected location 2; second variable frequency pump 4; first water pump 5; second water pump 6, the analog control signal of PLC controller 1 output to first variable frequency pump 3; the input of second variable frequency pump 4.

As shown in Figure 2, first variable frequency pump 3 in parallel, second variable frequency pump 4, first main frequency water pump 5, second main frequency water pump 6 on the inlet channel 7 of constant pressure water supply system, outlet conduit 8 is provided with air pressure tank 9, pressure meter 10, control device 11 respectively with first variable frequency pump 3, second variable frequency pump 4, first main frequency water pump 5, second main frequency water pump 6, pressure meter 10.

Fig. 4 is two identical variable frequency pumps of model, the Q-H performance diagram of a main frequency water pump parallel operation.Curve 1,2 is for passing the isoeffect curve of 2 of A, B among the figure; Curve I is that the separate unit water pump is at rated revolution n _oThe time characteristic curve; Curve I is that the separate unit water pump is at minimum revolution n _MinThe time characteristic curve; Curve II is that two water pumps are at rated revolution n _oThe time characteristic curve; Curve III is that 3 water pumps are with rated revolution n _oCharacteristic curve during parallel running; Curve IV be 2 with rated revolution n _oRunning, 1 with minimum revolution n _MinThe characteristic curve of parallel running during running; Curve V be 2 with minimum revolution n _MinRunning, 1 with rated revolution n _oThe characteristic curve of parallel running during running; Curve VI be 2 with minimum revolution n _MinCharacteristic curve during running; H _bBe design constant voltage value; H _aMaximum value for lift in the efficient section of pump characteristic; Q _b, Q _aBe respectively H _b, H _aCorresponding flow value.

As shown in Figure 4, flow when guaranteeing the efficient district parallel operation of 3 water pumps is continuous, and the unlikely frequency modulation pump operating point that makes drops on outside the efficient district, just must make the IV curve pass the B point or under the B point, corresponding V curve will pass the C point or under the C point, so just have:

Q _b≥2Q _e (1)

By proportional law of pump as can be known, the pass of similar operating condition point A, E is:

$Q_a/Q_e=\sqrt{H_a/H_e}$

As shown in Figure 4, when guaranteeing the work of 3 water pump unions, the operating point of main frequency water pump and frequency modulation water pump all drops in its corresponding efficient district, and the later characteristic curve of frequency modulation water pump revolution downward modulation can not pass below the E point, that is to say that the frequency modulation water pump is with minimum revolution n in efficient district _MinCharacteristic curve during operation must pass the E point, therefore has:

H _e＝H _b

Then $Q_a/Q_e=\sqrt{H_a/H_e}$ $Q_e=Q_a\sqrt{H_b/H_a}---\left(2\right)$

(2) formula substitution (1) just can be obtained (3) formula $Q_b/Q_a\≥2\sqrt{H_b/H_a}---\left(3\right)$

If Q _b/ Q _a=α $2\sqrt{H_b/H_a}=\mathrm{\β}$

Then can obtain α 〉=β (4)

Therefore, when 2 variable frequency pumps and 1 main frequency water pump parallel running, satisfy α 〉=β, just can guarantee that frequency modulation water pump and main frequency water pump are operated in efficient district, reach purpose of energy saving as long as set the water pump parameter.This conclusion is fit to equally 3 situations during with the charging pump parallel operation.

Fig. 5 represents the Q-H characteristic curve of water pump, wherein A～B segment table shows efficient section of water pump, three efficient points that provide in A, B, 3 expression water pumps of the C sample, and dash area is represented the amount of energy saving of frequency modulation water pump in different constant voltage values among the figure, as shown in Figure 5, when setting value, frequency modulation exit of pump constant voltage is H _cThe time amount of energy saving obviously be greater than constant voltage setting value and be H _bThe time amount of energy saving, the minimum lift value in the efficient section of general water pump constant voltage value water intaking pump or the 105%-140% of minimum lift value.

Above-mentioned water pump can be the identical DL of model, IS, LG water pump.

Claims (4)

1, a kind of constant pressure water supply control device; comprise PLC controller, driving and protected location, first variable frequency pump and at least one general pump; the input of PLC controller is connected to pressure feedback signal; its output connects the input of driving and protected location, first frequency converter respectively; driving connects first frequency converter and at least one general pump respectively with the output of protected location, and it is characterized in that: the output of described PLC controller and driving and protected location also is connected to second variable frequency pump.

2, constant pressure water supply control device according to claim 1, described water pump are the identical DL of model, IS or LG water pump.

3, a kind of constant pressure water supply method may further comprise the steps:

Air pressure tank is set, and pressure store water;

Two frequency modulation water pumps and at least one main frequency water pump are set;

Water pump satisfies: α 〉=β, α=Q _b/ Q _a, $\mathrm{\β}=2\sqrt{H_b/H_a}.$

4, constant pressure water supply method according to claim 3 is characterized in that: the minimum lift value in the efficient section of water pump constant voltage value water intaking pump or the 105%-140% of minimum lift value.

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