CN101982620A - Energy-saving control method for water supply project - Google Patents

Abstract

The invention provides an energy-saving control method for a water supply project, characterized by comprising the following steps: determining maximum hours of a maximum day, average hours of the maximum day and minimal water utilization amount according to a pipe network plane adjustment arrangement diagram and a water utilization change curve; selecting five flow quantities for calculation of the pipe network adjustment, solving an integrated resistance coefficient S of the pipe network, determining a pipe network characteristic curve; determining that the total number of machine sets is not more than 5 according to a crossed point of a water pump characteristic curve and the pipe network characteristic curve, when a fixed speed pump and a variable speed pump run together, setting the designed flow quantity QT of the water pump to be 70% of the flow quantity at the maximum hour of the maximum day and the number of the variable speed pumps to be 40% of the total number of the machine sets, reducing the rotating speed of the variable speed pump by 30% at most, arranging a water pressure sensor at the most unfavorable point on the pipe network, indicating a frequency converter of the water pump to automatically adjust the rotary speed, and adjusting the change of water utilization amount and lifting of the water pump. The invention uses a method of water supply by the speed pump or water co-supply by the variable speed pump and the fixed speed pump to realize that the water supply amount is changed as the change of the resident water utilization amount, so that the water pump runs in a high-efficiency region, overcomes the defects of a fragmental constant voltage, reduces electrical consumption of the water pump and is energy-saving and environment-friendly.

Description

The water supply project energy-saving control method

Technical field

The present invention relates to energy-saving design and control method in the municipal engineering water supply industry.

Background technology

In traditional water supply technology, the selection of water supply pump existing problems.At first, water supply pump is flow when maximum of maximum day by urbanite water consumption, and the water pump of operation can be efficiently put in selection in pump efficiency.Yet in the actual moving process, 24 hourly consumptions are to change constantly, and maximum hourly consumption only was 4～6 hours in 24 hours.That is to say that water pump only is 4～6 hours every days in the time of efficient district operation, other times all in non-efficient district operation, cause a large amount of energy wastes.Secondly, in several water pump cooperations, because the pipe network actual flow is less than design discharge, the actual lift that causes single water pump assembly is less than rated lift, it promptly is the flow that has increased single water pump assembly, cause the net positive suction head curve to go up curved the rising suddenly, occur cavitation erosion easily, influence safe operation.

Current pipe network theoretical curve characteristic equation still can not be set up, and understands the operating mode that cooperates operation less than parallel water pump machine unit characteristic curve with pipe system performance curve.Original method though adopted speed-variable pump, is a constant pressure water supply, makes energy-saving run step into circumscribed mistaken ideas again.

Summary of the invention

Technical problem to be solved by this invention provides a kind of method of a kind of water supply and energy saving that carries out in conjunction with the urban water use system-head curve, water pump assembly is being moved in efficient scope, and the method is easy and simple to handle, and technology is reasonable.

For solving the problems of the technologies described above, the invention provides a kind of energy saving method for water supply engineering, it is characterized in that comprising the following steps:

1, determines node serial number, assignment of traffic and the length of pipe section parameter of pipe network according to pipe network planimetric adjustment arrangement diagram, determine maximum day when maximum, maximum when per day and minimum water supply volume according to the urban water use change curve;

2, choose five flows, comprising hour flow, flow when maximum, other three flows are chosen arbitrarily, carry out the pipe network compensating computation according to five flows, determine corresponding lift H and least favorable point H _Z, according to system-head curve equation H=H _Z+ SQ ², and then try to achieve the overall drag coefficient S of pipe network, determine pipe system performance curve;

3, according to pump characteristic and pipe system performance curve intersection point, determine no more than 5 of the total platform number of unit, when constant speed pump and speed-variable pump cooperation, the design discharge Q of water pump _TGet 70% of maximum day flow when maximum, the platform number of speed-variable pump accounts for 40% of the total platform number of unit, and the speed-variable pump rotating speed is maximum to reduce by 30%, and speed-variable pump platform number is calculated by following formula:

${\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="HSA00000311426000011.png,HSA00000311426000031.png"\; state="\{\{state\}\}">n</figure-callout>}}_1=\frac{b\&CenterDot;n-a}{b+\mathrm{\&eta;}\&CenterDot;c-c}$

n ₁---variable frequency pump platform number

N---the total platform number of work water pump

η---speed governing percentage (20%～30%)

A---(n-1) flow of platform working barrel (l/s)

B---(n-1) flow of platform single pump (l/s)

C---when n platform pump all moves, the flow of single pump (l/s)

Be variable frequency pump when work entirely, with low discharge one end design discharge Q in efficient section _TSelect pump;

4, control automatically: the least favorable point is established hydraulic pressure sensor on pipe network, the frequency converter of the signal indication water pump of hydraulic pressure sensor feedback makes water pump by the water requirement, regulates rotating speed at any time automatically, reach real-time feedback water supply volume information, regulate the variation of water pump output and lift.

Advantage of the present invention: from the fundamental characteristics of water pump operation, take into full account the relation between pump capacity, lift and the efficient, and in conjunction with townsfolk's characteristic of water use and urban pipe network characteristic and a kind of water supply and energy saving that carries out subtracts the method for consumption.Adopt speed-variable pump water supply or speed-variable pump and constant speed pump to unite the method for water supply, realize that water-supply quantity changes along with the variation of urbanite water consumption amount, make water pump operation at high efficient area, give full play to the operating efficiency of water pump, overcome the drawback of segmentation constant voltage, in time reduce the power consumption of water pump simultaneously, reach real energy-conserving and environment-protective.If 50% water supply realizes energy saving water supply, more than 3,300 hundred million degree then can be saved in the annual whole nation.

Description of drawings

Fig. 1 is curve of water consumption figure;

Fig. 2 is pipe system performance curve overall drag coefficient " S " logarithm calculating chart;

Fig. 3 is pipe system performance curve figure;

Fig. 4 is an energy-conservation schematic diagram after the frequency conversion;

Fig. 5 is pump efficiency and discharge relation figure;

Fig. 6 is flow and net positive suction head graph of a relation.

The specific embodiment

(1), determines the pipe network layout plan

With reference to Fig. 1, arrange node serial number, assignment of traffic and the length of pipe section of pipe network, wherein supply water as topographical elevation difference big (surpassing more than 20 meters) or strip one end, should consider the subregion problem; Press the urban water use change curve and determine maximum day when maximum, maximum when per day and minimum water supply volume;

(2) determine the characteristic curve of pipe network

With reference to Fig. 2, Fig. 3, carry out pipe network adjustment waterpower and calculate, should adopt corresponding economic velocity by different tube diameters during adjustment, the employing of every section caliber economic velocity, local non-avaible, can be as follows with reference to the universal experience data:

DN(mm)	V(m/s)	DN(mm)	V(m/s)
				200	0.7～0.8	700	1.4～1.5
300	0.8～0.9	800	1.5～1.6
				400	1.0～1.2	900	1.6～1.7
500	1.2～1.3	1000	1.7～1.8
				600	1.3～1.4	1200	1.8～2.0

Choose five flows, comprising hour flow, flow when maximum, other three flows are chosen arbitrarily; Respectively five flows are carried out the pipe network compensating computation, determine corresponding lift H and least favorable point H _Z, according to system-head curve equation H=H _Z+ SQ ², calculate Lg (H-H through logarithm _Z)=lgS+2lgQ and then try to achieve the overall drag coefficient S of pipe network determines pipe system performance curve;

(3) configuration of water pump assembly

With reference to Fig. 1, Fig. 3, the configuration of water pump assembly should be divided into constant speed pump and speed-variable pump associated working or all use two kinds of situations of speed-variable pump, analyze according to pump characteristic and pipe system performance curve cooperating, determine no more than 5 of the total platform number of unit, when constant speed pump and speed-variable pump cooperation, the design discharge Q of water pump _TShould get 70% of maximum day flow when maximum.(4.17/6＝70％)

With reference to Fig. 5, Fig. 6, when selecting pump, do not serve as according to selecting with efficient point, and with low discharge one end in efficient section by design discharge Q _TSelect.Can guarantee that so unit is moving always in efficient scope, also can guarantee not overburden of pump working simultaneously, not produce cavitation erosion, the HPSH curve is with curved Q increases in, safe operation, and when whole employing speed-variable pumps work, the curve of can water pump efficiently the putting selection that is as the criterion.

With reference to Fig. 4, because pipe system performance curve has been arranged, by the digitlization equation H=H of pipe network _Z+ SQ ²With pump characteristic equation cooperating, the hydraulic pressure that just can guarantee system changes on characteristic curve always at any time, overcome artificial constant voltage operation, this is the key point of energy-saving design, wherein, shaded area is energy-conservation design power, and the top rectangular area is the artificial waste energy of constant voltage, the design discharge Q of water pump _TGet 70% of maximum day flow when maximum, the platform number of speed-variable pump accounts for 40% of the total platform number of unit, and the speed-variable pump rotating speed is maximum to reduce by 30%, and speed-variable pump platform number is calculated by following formula:

${\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="HSA00000311426000011.png,HSA00000311426000031.png"\; state="\{\{state\}\}">n</figure-callout>}}_1=\frac{b\&CenterDot;n-a}{b+\mathrm{\&eta;}\&CenterDot;c-c}$

n ₁---variable frequency pump platform number

N---the total platform number of work water pump

η---speed governing percentage (20%～30%)

A---(n-1) flow of platform working barrel (l/s)

B---(n-1) flow of platform single pump (l/s)

C---when n platform pump all moves, the flow of single pump (l/s)

Be speed-variable pump when work entirely, with low discharge one end design discharge Q in efficient section _TSelect pump; And be as the criterion with the curvilinear equation of efficient point.

(4) the automatic control of energy-saving design method

Traditional method for designing, uncontrollable for the hydraulic pressure of least favorable point.

Wherein Hz is the hydraulic pressure of least favorable point, SQ ²Be the pipe network head loss, its two pressure that sum provides for water pump.When water supply volume was big, the pipe network head loss increased, and the least favorable point does not reach the hydraulic pressure of requirement.When water supply volume hour, the pipe network head diminishes, and causes least favorable point hydraulic pressure too high.

The automatic control of energy-saving design is least favorable point on pipe network, establishes hydraulic pressure Hz sensor, frequency converter by remote control indication water pump makes water pump by the water requirement, regulates rotating speed at any time automatically, reach real-time feedback water supply volume information, regulate the variation of water pump output and hydraulic pressure.

The test example

Certain water supply network engineering after having carried out pipe net arrangement and pipe network adjustment, selects 3 variable frequency pumps and 2 constant speed pumps to be used in the urban water supply.In the process of actual motion, when flow not simultaneously, variable frequency pump carries out the water yield and lift automatically to be regulated, and every pump is all moved under high efficiency.

When Q=2300 (L/s), 3 governor impellers operations, H=35 (m), if adopt new method, governor impeller general power P accents=701.18kw, if adopt conventional method, general power P decides=974.92kw.

The pump power formula: $W\left(\mathrm{kw}\right)=\frac{K}{102}[H_z\left(m\right)\&CenterDot;Q(l/s)+S(s/m^5)\&CenterDot;\frac{{\left(\frac{Q}{1000}\right)}^2\&times;(l/s)}{3}]$

The maximum reduction of speed of this patent measuring and calculating unit is 30%, the unlikely efficient that influences frequency conversion.

Claims (1)

1. a water supply project energy-saving control method is characterized in that comprising the following steps:

(1) determines node serial number, assignment of traffic and the length of pipe section parameter of pipe network according to pipe network planimetric adjustment arrangement diagram, determine maximum day when maximum, maximum when per day and minimum water supply volume according to the urban water use change curve;

(2) choose five flows, comprising hour flow, flow when maximum, other three flows are chosen arbitrarily, carry out the pipe network compensating computation according to five flows, determine corresponding lift H and least favorable point H _Z, according to system-head curve equation H=H _Z+ SQ ², and then try to achieve the overall drag coefficient S of pipe network, determine pipe system performance curve;

(3) according to pump characteristic and pipe system performance curve intersection point, determine no more than 5 of the total platform number of unit, when constant speed pump and speed-variable pump cooperation, the design discharge Q of water pump _TGet 70% of maximum day flow when maximum, the platform number of speed-variable pump accounts for 40% of the total platform number of unit, and the speed-variable pump rotating speed is maximum to reduce by 30%, and speed-variable pump platform number is calculated by following formula:

$n_1=\frac{b\&CenterDot;n-a}{b+\mathrm{\&eta;}\&CenterDot;c-c}$

n ₁---variable frequency pump platform number

N---the total platform number of work water pump

η---speed governing percentage (20%～30%)

A---(n-1) flow of platform working barrel (l/s)

B---(n-1) flow of platform single pump (l/s)

C---when n platform pump all moves, the flow of single pump (l/s)

Be variable frequency pump when work entirely, with low discharge one end design discharge Q in efficient section _TSelect pump;

(4) control automatically: the least favorable point is established hydraulic pressure sensor on pipe network, the frequency converter of the signal indication water pump of hydraulic pressure sensor feedback makes water pump by the water requirement, regulates rotating speed at any time automatically, reach real-time feedback water supply volume information, regulate the variation of water pump output and lift.

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