JP2004197621A - Operating method of centrifugal pump with different kinds of pumping abilities - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for appropriately operating one centrifugal pump having two different kinds of pumping abilities according to the operating state by giving the pump a pumping ability ¾dH/dQ¾ of a small pump and a pumping ability ¾dH/dQ¾ of a large pump. <P>SOLUTION: When the centrifugal pump 8 comprising piping and equipment for liquid feeding to load resistance needs a high lift, it is operated by using a normal rotation 12 wherein the rotating direction of impellers 9 of the centrifugal pump 8 matches the direction of a discharging port 11, and when the pump 8 needs a low lift, it is operated by using a reverse rotation 13 wherein the rotating direction of the impellers 9 of the centrifugal pump 8 is different from the direction of the discharging port 11. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００１９】
すなわち、十分に低い揚程を必要とする場合は、遠心ポンプ８のインペラー９の回転方向を吐出口１１の方向と異なった方向の逆転１３により運転することにより１台の遠心ポンプ８を２種のポンプ性能の異なるポンプとして運転する。この場合、遠心ポンプ８は内蔵する直流モータで直接駆動されるＤＣポンプとする。直流モータは電圧を変えることで回転数を容易に変更できるので、本発明に使用するモータをＤＣポンプとすることで、回転数を変更しかつＤＣポンプのインペラー９の回転方向を逆転とすることを併用することで、目的とする全揚程の高さを容易に達成することができ、さらに｜dH/dQ｜の大きいポンプ性能の性能曲線を得ることができるので、１台の遠心ポンプ８でポンプ性能の制御が容易にコントロールすることができる。遠心ポンプ８のインペラー９の正転逆転は、モータ駆動ロジックＩＣには正転逆転端子が通常は設けられており、Ｈ／Ｌ信号をこの端子に与えることで容易に入力して行うことができる。遠心ポンプ８は以上のように回転数の変更が容易にできるＤＣモータにより駆動するＤＣポンプとしているが、インペラー９の正転逆転による本発明の効果は、ＡＣモータにより駆動するものであってもよいことはいうまでもない。
【００２０】
【発明の効果】
以上説明したように、本発明は、遠心ポンプにおいて、インペラーの回転方向を正転および逆転に変更することで、回転速度を落とすことと合わせて、ポンプ性能が｜dH/dQ｜の小さい性能曲線のものから｜dH/dQ｜の大きい性能曲線のものに変更することで、低揚程で使用する場合に良好な制御特性の遠心ポンプとすることが可能であり、従来のもののように配管や機器など負荷抵抗を、遠心ポンプの吐出口に流量バルブを設け、低回転数時に流量バルブを閉じることで負荷抵抗を増加し、揚程を減らして負荷曲線の寝ている部分を立ち上がらせる必要を無くすなど、余分な設備を必要とせずに１台の遠心ポンプを２種の異なるポンプ性能のポンプとして運転することができる。
【図面の簡単な説明】
【図１】全揚程と揚水量の関係でポンプ性能を示すグラフである。
【図２】本発明における実施例のポンプ性能を示すグラフである。
【図３】本発明に使用する遠心ポンプのインペラーの部分を模式的に示す側面図である。
【図４】本発明に使用するＤＣポンプの一部断面で示す側面図である。
【図５】図４のＤＣポンプの吸込口側から見た正面図である。
【符号の説明】
１ 性能曲線
１’ 性能曲線
２ 性能曲線
２’ 性能曲線
３ 負荷曲線
４ 性能曲線
４’ 性能曲線
５ 性能曲線
５’ 性能曲線
６ 性能曲線
６’ 性能曲線
７ 性能曲線
８ 遠心ポンプ
９ インペラー
１０ 軸心
１１ 吐出口
１２ 正転
１３ 逆転
１４ 吸込口
１５ 液流方向
１６ 外装
１７ ステータ
１８ 回転子
Ａ 動作点
Ｂ 動作点
Ｃ 動作点
Ａ’ 動作点
Ｂ’ 動作点
Ｃ’ 動作点
ｘ 変化量
ｍ 変化量
ｎ 変化量
ｐ 変化量
ｑ 変化量[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of operating a centrifugal pump, and in particular, a centrifugal pump with a built-in DC motor used to supply hot water from a heat source device such as a heating device (the centrifugal pump with a built-in DC motor is referred to as a “DC pump” in the present invention). ).
[0002]
[Prior art]
A centrifugal pump that pumps a large amount of liquid as an industrial pump has a spiral impeller, and discharges the liquid by centrifugal force from a shaft center of the impeller to a pump discharge port arranged in the same direction as the rotation direction of the impeller. And sent. In such a centrifugal pump, as shown in FIG. 1, when the total head [m] is plotted on the vertical axis and the pumping rate [l / m] is plotted on the horizontal axis, the same operating point is plotted on a performance curve diagram. For the centrifugal pump passing through A, a pump with a low cutoff head and a large open pumping amount shown by the performance curve 1 and a small | dH / dQ | (where dH indicates a change in the head and dQ indicates a change in the pumping amount). There are two types of centrifugal pumps: a high-performance centrifugal pump and a high-performance pump with a high cutoff head and a low open-water yield, | dH / dQ |. On the other hand, the load resistance received from the piping and equipment connected to the centrifugal pump is shown in the performance curve diagram as a load curve 3 composed of a quadratic curve.
[0003]
By the way, when the rotation speed of the centrifugal pump connected to the load resistance such as piping or equipment is reduced by controlling the rotation speed of the motor to be driven, the head and the amount of pumped water follow this load curve 3. Will decrease. However, when the number of rotations is reduced to a certain degree or less, as the head becomes lower, the method of decreasing the amount of pumped water rapidly increases, and the load curve 3 falls. Accordingly, a slight change in the head causes a large change in the amount of pumped water, and the amount of pumped water is likely to vary, resulting in poor controllability. That is, in FIG. 1, the performance curve 1 shows a performance curve 4 as the head decreases as the rotation speed is reduced. If the rotation speed is further reduced from this state and the head is reduced by the variation x, the performance curve 4 ′ is obtained. Become. That is, the operating point A ′ at the intersection with the load curve 3 becomes the operating point C ′. The pumping amount at this time is the change amount p. The amount of change p is determined by the operating point A at the intersection of the performance curve 1 and the load curve 3 at the intersection with the load curve 3 of the performance curve 1 'when the rotational speed is reduced and the head is reduced by the change x. It is clearly larger than the change amount m of the pumping amount at the time of C, which indicates that the pumping amount is likely to fluctuate with a slight change in the head.
[0004]
Next, assuming that the performance curve passes through the same operating point, the centrifugation of the pump performance indicated by the performance curve 1 having a low deadline head (a head when the pumping amount is 0) and a large open pumping amount | dH / dQ | A pump and a centrifugal pump having a large pump performance of | dH / dQ | indicated by a performance curve 2 having a high cutoff head and a small open pumping amount are compared. In this case, when the rotational speed of the centrifugal pump having the pump performance of the performance curve 1 is reduced and the head is reduced by the variation x so as to obtain the performance curve 1 ', the operating point A which is the intersection with the performance curve 1 becomes the load curve 3 Move along the line to become the operating point C, and the change in the pumping amount becomes the change amount m in the pumping amount between the operating point A and the operating point C. On the other hand, the rotation speed of the centrifugal pump having a large pumping performance of | dH / dQ | with a high cutoff head and a small open pumping amount indicated by the pumping performance of the performance curve 2 passing through the same operating point A is reduced to a performance curve 2 '. As described above, when the head is reduced by the variation x in the same manner as described above, the operating point A of the performance curve 2 moves along the load curve 3 to become the operating point B, and the variation of the pumped water is the operating point A and the operating point B. The amount of change n in the amount of water pumped during the period is n.
[0005]
As is clear from FIG. 1, the change m in the pumping amount is larger than the change n in the pumping amount. Therefore, for these two types of pump performance, the change in the pumping amount is the same as the change x in the same head. The change n of the pumping amount of the pump performance with a large | dH / dQ | is smaller than the changing amount m of the pumping amount with a small | dH / dQ | of the former. Therefore, it can be said that a centrifugal pump having a large pump performance of | dH / dQ | has less fluctuation, that is, variation in the pumping amount even if the head changes due to a change in the number of revolutions, and has better controllability. However, a centrifugal pump having a large pump performance of | dH / dQ | tends to have a lower maximum efficiency than a pump having a small pump performance of | dH / dQ |.
[0006]
For the reasons described above, users usually want to operate with low pump performance of | dH / dQ | with high pump efficiency. However, in the region where the head below the load curve 3 is close to zero where the head is low and the controllability is low due to the low pumping rate and the amount of water being pumped down, the pump is operated with a large pump performance of | dH / dQ |. I want to reduce the possibility that controllability becomes worse. Therefore, in order to satisfy these two kinds of demands of the user with one centrifugal pump, a flow valve is provided at the discharge port of the centrifugal pump, the valve is normally operated with the flow valve opened, and the flow valve is operated at a low rotation speed. Closing the valve will increase the load resistance and reduce the head.However, by raising the sleeping part of the load curve, it is possible to reduce the fluctuation of the pumped water with respect to the fluctuation of the head to ensure controllability. Has taken.
[0007]
[Non-patent document 1]
Hiroshi Yamada, "Practical motor control circuit design guide" published by Sogo Denshi Publishing Co., Ltd. [Non-Patent Document 2]
Masayoshi Omachi, "Circulating Pump Design" Published by Power Corporation [0008]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to provide a single centrifugal pump, particularly a single DC pump, with a small pump performance of | dH / dQ | without providing a flow valve at the discharge port of the centrifugal pump as described above. By providing two different pump performances, that is, a large pump performance of | dH / dQ | and a single centrifugal pump, it is possible to operate this one centrifugal pump as a pump with two different pump performances, depending on the operating conditions as appropriate. To provide.
[0009]
[Means for Solving the Problems]
Means of the present invention for solving the above-mentioned problems are as follows. According to the first aspect of the present invention, in the case of operating one centrifugal pump for supplying a load resistance consisting of a pipeline and equipment, when a high head is required, Operate the centrifugal pump with the impeller rotating in the forward direction that matches the direction of the discharge port.If a low head is required, operate the centrifugal pump impeller with the reverse direction different from the direction of the discharge port. This is a method of operating one centrifugal pump as a pump having two different pump performances.
[0010]
According to the second aspect of the present invention, the centrifugal pump is a DC pump directly driven by a built-in direct current motor, and one centrifugal pump of the means of the first aspect operates as two types of pumps having different pump performances. Method.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a graph showing pump performance in relation to the total head and the amount of pumped water. FIG. 2 is a graph showing the pump performance of the embodiment of the present invention. FIG. 3 is a side view schematically showing an impeller part of a centrifugal pump used in the present invention, FIG. 4 is a side view showing a partial cross section of a DC pump used in the present invention, and FIG. It is the front view seen from the suction port side of the pump.
As shown in FIG. 3, the impeller 9 of the centrifugal pump 8 has a blade shape spirally bent rearward in a direction opposite to the rotation direction of the forward rotation 12. Therefore, the pump efficiency and the pump performance are different when the impeller 9 is rotated forward 12 by the impeller shaft 10 and when the impeller 9 is rotated backward 13. The present invention utilizes the difference in pump efficiency and pump performance due to the difference in the rotation direction of the impeller 9. That is, the direction of rotation of the impeller 9 is the same as the direction of the spiral that coincides with the direction of the discharge port 11 extending in the tangential direction of the rotation circle at the tip of the impeller 9, and the direction of rotation of the impeller 9 is defined as normal rotation 12. When the direction of rotation of the impeller 9 is different from the direction of the discharge port 11 to the direction of the spiral of the impeller, and the direction of rotation of the impeller 9 is the reverse rotation 13, the direction of the forward rotation 12 of the impeller 9 is good in pump efficiency and | dH / dQ | Small pump performance. On the other hand, in the direction of the reverse rotation 13 of the impeller 9, the pump efficiency is inferior and the pump performance of | dH / dQ | is large. The present invention takes advantage of these differences in pump efficiency and pump performance.
[0012]
Therefore, according to the first aspect of the present invention, in the operation of one centrifugal pump 8 for supplying a load resistance consisting of a pipeline and equipment, when a high head is required, the rotation of the impeller 9 of the centrifugal pump 8 is required. The direction of rotation is indicated by the arrow 12 which coincides with the direction of the discharge port 11. The pump 12 is operated at a high pump efficiency and a small pump performance of | dH / dQ |, and when a low head is required, the impeller of the centrifugal pump 8 is used. This is a method of operating with a pump performance of | dH / dQ |, which is inferior in pump efficiency, as a reverse rotation 13 in which the rotation direction of 9 is indicated by a reverse arrow direction different from the direction of the discharge port 11. In the above description, the direction of the discharge port 11 refers to the liquid flow direction 15 of the liquid sent out of the discharge port 11 shown in FIG.
[0013]
In the above, the motor for driving the centrifugal pump 8 may be a DC motor or an AC motor. However, the DC motor is easier to control the number of rotations. In the method of the invention, the centrifugal pump 8 is operated as a DC pump.
[0014]
The centrifugal pump 8 used in the present invention will be described. As shown in FIGS. 4 and 5, the centrifugal pump 8 is connected to a DC motor integrally incorporated in an exterior 16 and to the DC motor through an axis 10. It consists of a driven impeller 9. In the DC motor, the stator 17 side and the rotor 18 side on which the magnet is fitted are hermetically sealed, and the liquid to be pumped flows through the narrow gap between the stator 17 side and the rotor 18 side and the shaft 10. . In the stator, the centrifugal pump 8 has a suction port 14 for sucking the liquid to be pumped to the right side in FIG. 4, and the liquid sucked from the suction port 14 is centrifugally applied to the discharge port 11 from inside the impeller 9 from the shaft 10. Sent and pumped.
[0015]
A specific operation example of the present invention will be described with reference to Table 1 and FIG. It is operated by a single centrifugal pump 8 that feeds a load resistance consisting of a pipeline and equipment. When a high total head is required, the rotation direction of the impeller 9 of the centrifugal pump is driven by the forward rotation 12 which coincides with the direction of the discharge port, as shown in Tables a to d. 3000 rotations. Increase pumping volume from 0.0 liters per minute to 15.0 liters per minute. The relationship between the pumping amount and the total head in this case is a graph of a small performance curve of | dH / dQ |, as shown in a performance curve 6 in FIG. 2, where the pumping amount is from 0.0 liter / min to 15.0 / min. Even at liters, the total head does not decrease so much from 8.0m to 6.5m.
[0016]
On the other hand, the same rotation speed of the impeller 9 is set to 3000 revolutions per minute, but the impeller 9 is operated by the reverse rotation 13 opposite to the direction of the discharge port. In this case, as shown in e to f in Table 1 and the performance curve 7 in FIG. 2, when the pumping amount is increased from 0.0 liters per minute to 7.5 liters per minute, the total head is increased from 6.1 m. It is extremely reduced to 1.5 m, and becomes a graph of a large performance curve of | dH / dQ |. Accordingly, the rotation direction of the impeller 9 is simply switched from the direction of the forward rotation 12 to the direction of the reverse rotation 13 without lowering the rotation speed of the impeller 9. And a performance curve with a large | dH / dQ |
[0017]
On the other hand, when the total head is reduced by setting the rotation direction of the impeller 9 to the same direction of the forward rotation 12, the rotation speed of the impeller 9 is reduced from 3000 rotations per minute to 2140 rotations per minute, whereby i to i in Table 1 are reduced. m, or as shown by the performance curve 6 'in FIG. However, in this case, a performance curve of | dH / dQ | is small as seen in the performance curve 6 'of FIG. Therefore, in FIG. 2, when the load curves are tentatively overlapped as in FIG. 1, in a portion where the total head is low, the performance curve 7 having a large | dH / dQ | is better than the performance curve 6 'having a small | dH / dQ | Also, the fluctuation of the pumping amount seen from the load curve is small, and the control is easy.
[0018]
[Table 1]

[0019]
That is, when a sufficiently low head is required, one centrifugal pump 8 is driven by two rotations of the impeller 9 of the centrifugal pump 8 in the reverse direction 13 different from the direction of the discharge port 11 so that one centrifugal pump 8 is driven by two types. Operate as pumps with different pump performance. In this case, the centrifugal pump 8 is a DC pump directly driven by a built-in DC motor. Since the rotation speed of a DC motor can be easily changed by changing the voltage, the rotation speed is changed and the rotation direction of the impeller 9 of the DC pump is reversed by using a DC pump as the motor used in the present invention. With the use of a single centrifugal pump 8, it is possible to easily achieve the desired height of the total head and to obtain a performance curve of large pump performance of | dH / dQ |. Control of pump performance can be easily controlled. Normal rotation and reverse rotation of the impeller 9 of the centrifugal pump 8 can be easily performed by inputting an H / L signal to this terminal, which is usually provided with a normal rotation reverse rotation terminal in the motor drive logic IC. . As described above, the centrifugal pump 8 is a DC pump driven by a DC motor whose rotation speed can be easily changed. However, the effect of the present invention due to the forward / reverse rotation of the impeller 9 is not limited to the case where the centrifugal pump 8 is driven by an AC motor. It goes without saying that it is good.
[0020]
【The invention's effect】
As described above, according to the present invention, in the centrifugal pump, by changing the rotation direction of the impeller to forward rotation and reverse rotation, the pump performance is reduced along with the reduction of the rotation speed, and the performance curve of small | dH / dQ | By changing from the one with a large performance curve of | dH / dQ |, it is possible to make a centrifugal pump with good control characteristics when used at low heads, as with conventional piping and equipment. By installing a flow valve at the discharge port of the centrifugal pump and increasing the load resistance by closing the flow valve at low rotation speed, reducing the lift and eliminating the need to raise the sleeping part of the load curve In addition, one centrifugal pump can be operated as a pump having two different pump performances without requiring extra equipment.
[Brief description of the drawings]
FIG. 1 is a graph showing pump performance in relation to the total head and the amount of pumped water.
FIG. 2 is a graph showing the pump performance of an example according to the present invention.
FIG. 3 is a side view schematically showing an impeller part of a centrifugal pump used in the present invention.
FIG. 4 is a side view showing a partial cross section of a DC pump used in the present invention.
FIG. 5 is a front view of the DC pump of FIG. 4 as viewed from a suction port side.
[Explanation of symbols]
Reference Signs List 1 Performance curve 1 'Performance curve 2 Performance curve 2' Performance curve 3 Load curve 4 Performance curve 4 'Performance curve 5 Performance curve 5' Performance curve 6 Performance curve 6 'Performance curve 7 Performance curve 8 Centrifugal pump 9 Impeller 10 Shaft center 11 Discharge port 12 Forward rotation 13 Reverse rotation 14 Suction port 15 Liquid flow direction 16 Exterior 17 Stator 18 Rotor A Operating point B Operating point C Operating point A 'Operating point B' Operating point C 'Operating point x Change m Change n Change Quantity p Change q Change

Claims (2)

In the operation of a single centrifugal pump that supplies liquid to a load resistance consisting of a pipeline and equipment, if a high head is required, operate the centrifugal pump by rotating the impeller in the forward direction that matches the direction of the discharge port. When a low head is required, the centrifugal pump operates as a pump having two different pump performances, characterized in that the rotation direction of the impeller of the centrifugal pump is operated by reverse rotation different from the direction of the discharge port. how to. The method according to claim 1, wherein the centrifugal pump is a DC pump directly driven by a built-in DC motor.

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