RU2814338C1 - Method of increasing uniformity of piston pump feed - Google Patents

Abstract

FIELD: pump building.

SUBSTANCE: invention relates to a method of increasing uniformity of piston pump feed and can be used in oil and gas and mining industries. Method of increasing uniformity of piston pump delivery includes correction of instantaneous delivery of pump depending on instantaneous values of angle φ of crankshaft rotation and angular speed ω of its rotation. According to the invention, the value of the average delivery of the multi-cylinder piston pump Q _av is calculated, the value of the instantaneous delivery of the pump is calculated and the equality Q = Q_av is constantly maintained, for this purpose, value of instantaneous angular speed ω of crankshaft rotation during one turn through angle φ is corrected by means of controlled drive.

EFFECT: invention is aimed at reducing cyclic loads, vibration, noise, as well as improving reliability of equipment operation due to reduction of pressure pulsations in working chambers of the pump, pipelines connected to the pump, pipeline valves and elements of the hydraulic system.

1 cl, 3 dwg

Description

The invention relates to pump engineering, in particular to methods for smoothing pulsations in the supply of piston pumps, including several pistons with a common drive part and a crankshaft, and can find application in the oil and gas and mining industries.

The operation process of a piston pump is characterized by the presence of pulsations in the supply of the pumped liquid, which is associated with a periodic change in the volume of the working chamber occupied by it, which alternately communicates with the inlet and outlet of the pump, as well as the peculiarities of the kinematics of the drive part of the pump.

There is a known method for reducing the uneven flow of a piston pump by using several pistons with a common drive part (Bashta T.M., Rudnev S.S., Nekrasov B.B. et al. Hydraulics, hydraulic machines and hydraulic drives, M., “Mechanical Engineering ", 1982, pp. 284 - 288). The effectiveness of the method depends on the number of pistons in the pump, and the reduction in supply pulsation occurs more effectively with an odd number.

The disadvantage of this method is the need to increase the number of pistons to reduce the pulsation of the working fluid supply, which makes it difficult to ensure an acceptable reduction in the unevenness of the working fluid supply during the practical implementation of the method based on design considerations.

The closest to the claimed method is a method for compensating for pulsations in the supply of a volumetric pump, which consists in adjusting the pump supply by forming a pulsating flow of liquid created by using the energy of an external source, in which the liquid is taken from the suction channel of the pump and directed to the pressure channel, and the amount of the corrective flow rate of the liquid at each moment of time is set forcibly (RU 2115827, published on July 20, 1998).

However, the known method is complicated by the fact that it requires the use of a special hydraulic machine with a synchronizing connection between the drive shaft of the hydraulic machine and the drive shaft of the pump, which does not provide sufficient efficiency in compensating for pulsations (smoothing unevenness) of the piston pump supply, increasing cyclic loads, vibration, noise, and reducing operational reliability equipment.

The technical result consists in reducing cyclic loads, vibrations, noise, as well as increasing the reliability of equipment operation by reducing pressure pulsations in the working chambers of the pump, pipelines connected to the pump, pipeline fittings and elements of the hydraulic system by maintaining constant equality of the values of the instantaneous pump flow Q and its average feed Q _av during operation.

The technical result is achieved by the fact that the method of increasing the uniformity of supply of a piston pump includes adjusting the instantaneous supply of the pump depending on the instantaneous values of the angle ϕ of rotation of the crankshaft and the angular speed ω of its rotation. According to the invention, the average flow rate of a multi-cylinder piston pump Q _av is preliminarily calculated _. depending on the number of cylinders, area, stroke and frequency of strokes of the piston, rod area, flow coefficient α, the value of the instantaneous pump flow is calculated

$$Q=\text{α}{\displaystyle \sum _{i=1}^n{Q}_i},$$

where Q _i is the instantaneous flow of a separate pumping chamber,

n - number of pumping chambers,

and constantly maintain the equality Q = Q _avg. , for which, using an adjustable drive, the value of the instantaneous angular velocity ω of rotation of the crankshaft is adjusted during one rotation through an angle ϕ according to a given dependence.

The inventive method makes it possible to reduce cyclic loads, vibration, noise, and also increase the reliability of equipment operation by reducing pressure pulsations in the working chambers of the pump, pipelines connected to the pump, pipeline fittings and elements of the hydraulic system.

In addition, it becomes possible to reduce the uneven supply of a piston pump without taking liquid from the suction channel of the pump and directing it into the pressure channel using a hydraulic machine with a synchronizing connection between the drive shaft of the hydraulic machine and the drive shaft of the pump. This makes it possible to simplify the implementation of the proposed method and make it more reliable, since the number of elements is reduced, because the hydraulic machine is excluded from the equipment.

The amount of instantaneous supply of a separate i -th pumping chamber Q _i calculated as follows:

$$Q_i=v_i{F}_i,$$

Wherev _i - instantaneous piston speed;F _i - piston area ini-camera.

$$v_i=r\text{ω}\frac{\sin (\text{φ}+\text{β})}{\cos \text{β}},$$

where r is the radius of the crank;

ω - instantaneous angular speed of rotation of the pump crankshaft;

ϕ - angle of rotation of the pump crankshaft;

β - connecting rod lift angle.

Here

$$\text{λ}=r/l;sin\text{β}=\text{λ}\sin \text{φ},$$

where l is the length of the connecting rod.

Respectively

$$Q_i=r\text{ω}\frac{\sin \left(\text{φ}+\arcsin \left(\frac{r}{l}\sin \text{φ}\right)\right)}{\cos \left(\arcsin \left(\frac{r}{l}\sin \text{φ}\right)\right)}{F}_i$$

(Kasyanov V.M. Hydraulic machines and compressors. Textbook for universities, M., “Nedra”, 1981, pp. 108 - 113).

Thus, the instant supply of a separateith pumping chamberQ _i depends on the magnitude of the instantaneous angular velocity ω and the position of the crankshaft, characterized by the angle ϕ. From the last formula it can be seen that at a value of instantaneous angular velocity ω =0 instantaneous feed $$Q_i$$ =0, which characterizes the case when the crankshaft does not rotate. Change in angular velocity ω leads to a change in instantaneous feed $$Q_i$$ , making it non-zero.

The use of an adjustable drive can change the value of the instantaneous angular speed of rotation of the crankshaft ω during one rotation of the crankshaft, What allows you to change the instantaneous feed of a separateith pump chamber during one rotation of the crankshaft and the pump as a whole.

For a multi-cylinder pump, the instantaneous flow is determined by the sum of the flows of the individual pump chambers, i.e.

$$Q=\text{α}{\displaystyle \sum _{i=1}^n{Q}_i},$$

where α is the feed coefficient.

The method is illustrated in Fig. 1, Fig. 2 and Fig. 3.

Figures 1 and Figure 2 show a diagram of the implementation of the proposed method using the example of a three-piston pump, where Figure 1 is a diagram of the pump, side view, Fig. 2 is a diagram of the pump, top view.

Figure 3 shows a graph of Q versus ϕ.

Curves relating to instantaneous flows by individual pump chambersQ _i , are shown by thin dotted lines, and the instantaneous flow of the pumpQ shown by curve A, which obtained by adding up the instantaneous flow rates of individual pumping chambersQ _i . The pump operation process is characterized by maximum flowQ _max, minimum feedQ _min, as well as average feedQ _Wed., which is represented on the graph by straight line B. The presence of maximum flow during pump operationQ _max and minimum feedQ _min causes uneven pump flow.

A three-piston pump includes three pumping chambers 9 , each of which contains a piston 1 that reciprocates in cylinder 2 , a suction valve 3 and a discharge valve 4, a connecting rod 5 , and a crankshaft 6 , while the cranks of the crankshaft 6 are offset relative to each other at an angle of 120°. The fluid flow is created when the crankshaft 6 rotates due to the alternating connection of the cylinder 2 with the suction 7 and discharge 8 lines of the main pipelines through the suction valve 3 and the discharge valve 4 .

The magnitude of the instantaneous supply of the individual i -th pumping chamber Q _i calculated as follows:

$$Q_i=v_i{F}_i,$$

Wherev _i - instantaneous piston speed;F _i - piston area ini-camera.

$$v_i=r\text{ω}\frac{\sin (\text{φ}+\text{β})}{\cos \text{β}},$$

where r is the radius of the crank;

ω - instantaneous angular speed of rotation of the pump crankshaft;

ϕ - angle of rotation of the pump crankshaft;

β - connecting rod lift angle.

Here

$$\text{λ}=r/l;sin\text{β}=\text{λ}\sin \text{φ},$$

where l is the length of the connecting rod.

Respectively

$$Q_i=r\text{ω}\frac{\sin \left(\text{φ}+\arcsin \left(\frac{r}{l}\sin \text{φ}\right)\right)}{\cos \left(\arcsin \left(\frac{r}{l}\sin \text{φ}\right)\right)}{F}_i.$$

(Kasyanov V.M. Hydraulic machines and compressors. Textbook for universities, M., “Nedra”, 1981, pp. 108 - 113).

Thus, the instant supply of a separateith pumping chamberQ _i depends on the magnitude of the instantaneous angular velocity ω and the position of the crankshaft, characterized by the angle ϕ. From the last formula it can be seen that at a value of instantaneous angular velocity ω = 0, the instantaneous feed $$Q_i$$ = 0, which characterizes the case when the crankshaft does not rotate.

Change in angular velocity ω leads to a change in instantaneous feed $$Q_i$$ , making it non-zero. The use of an adjustable drive changes the value of the instantaneous angular velocity of rotation of the crankshaft ω during one rotation, which allows you to change the instantaneous feed of a separateith pump chamber during one rotation of the crankshaft and the pump as a whole.

For a multi-cylinder pump, the instantaneous flow is determined by the sum of the flows of individual n pump chambers, i.e.

$$Q=\text{α}{\displaystyle \sum _{i=1}^n{Q}_i},$$

where α is the feed coefficient.

When a three-piston pump operates, the crankshaft 6 rotates with a constant instantaneous angular velocity ω =const.

Based on the above formulas, graphs of the dependence of Q on ϕ were constructed.

The average pump flow is determined by the formula:

$$Q_{\text{Wed}}=\alpha azFSn,$$

Where $$a$$ - coefficient , for double-acting pumps $$a=1-f/F$$ ,

where f is the area of the rod;

F - piston area (for single-acting and differential pumps $$a=1$$ );

z - number of cylinders;

S - piston stroke;

n is the piston stroke frequency.

By changing the value of the instantaneous angular velocity of the crankshaft ω in the process of turning through an angle ϕ by using an adjustable drive, it is possible to change the instantaneous flow with a separate pumping chamberQ _i , and instant pump deliveryQ during one crankshaft rotation6.

Maintaining the instantaneous angular speed of rotation ω during each rotation of the crankshaft 6 of the pump, based on the condition of ensuring a constant instantaneous pump flow Q equal to its average flow Q _avg , i.e. Q = Q _avg , allows to reduce the unevenness of pump flow.

Claims (23)

A method for increasing the uniformity of supply of a piston pump, including adjusting the instantaneous supply of the pump depending on the instantaneous values of the angle ϕ of rotation of the pump crankshaft and its angular speed ω of rotation, characterized in that preliminarily calculate the average flow rate of a multi-cylinder piston pump Q _{c p} using the formula: where α is the feed coefficient, - coefficient, and for double-acting pumps , for single-acting and differential pumps ; f - rod area, F - piston area, z - number of cylinders; S - piston stroke; n - piston stroke frequency, and calculate the amount of instantaneous pump flow using the formula: where n is the number of pumping chambers, Q _i is the instantaneous flow of a separate pumping chamber, which is calculated by the formula: , where r is the radius of the crank, ω - instantaneous angular speed of rotation of the pump crankshaft, ϕ - angle of rotation of the pump crankshaft, F _i - piston area in the i- chamber, l - connecting rod length, and constantly maintain the equality Q = Q _cf , for which, using an adjustable drive, the value of the instantaneous angular velocity ω of rotation of the crankshaft is adjusted during one rotation by an angle ϕ.