CN105320790A - Design method of throttle valve with pressure drop linearly changed with opening degree as well as valve core - Google Patents

Abstract

The invention discloses a design method of a throttle valve with pressure drop linearly changed with the opening degree. The design method comprises the following steps: a mathematic model of a valve core contour is established according to a target of a linear relationship between the pressure drop of the throttle valve and the opening degree, flow characteristics, an open area and geometric conditions of a valve core, a locus equation to be met by the contour of the valve core is deduced through an equivalent area curve equation, a contour curve of the valve core is obtained through the locus equation, and the valve core structure of the throttle valve is obtained. The managed pressure regulation linearity and the valve core contour curve with higher precision can be obtained with the design method, and the design method is more efficient and general.

Description

The method for designing of the throttling valve of pressure drop aperture linear change and spool

Technical field

The present invention relates to petroleum drilling technology field, the spool of the method for designing being specifically related to a kind of throttling valve of pressure drop aperture linear change and the throttling valve that adopts this method for designing to design, this throttling valve is in particular in controlled pressure drilling.

Background technology

In managed pressure drilling technology (ManagedPressureDrilling---MPD), the variation range of General Requirements bottomhole wellbore pressure is less than 50psi, and the change of pressure adjusts primarily of the throttling valve for pressure control.Therefore, the success ratio of controlled pressure drilling process implementing is directly had influence on for the performance of the throttling valve of pressure control.And the spool of good linear adjustment is the key of the pressure control performance determining throttling valve.

Variable valve is as the final element in hydropneumatic control system, essential in regulating system.Spool is as the critical component of variable valve, and the profile of spool directly determines the flow-adjusting characteristics of variable valve, its reasonably design for the performance of variable valve and production efficiency significant.At present, the spool of domestic throttling valve mainly comprises on this several simple " orthoscopic " profile spool of aciculiform, wedge shape and tubular.The reliability of the throttling valve of aciculiform spool is high, but outlet eddy-currents is more, and spool is easily shaken, easily broken.The restriction effect of the throttling valve of old-fashioned tubular spool is poor, and adjustable extent is little, easily occurs that spool stings bad and obscission.And, use in the throttling valve liquid of old-fashioned tubular spool containing sand time, valve rod and spool erosion serious.Erosion resistance, the reliability of wedge shape valve core are strong, poor linearity.In a word, pressure control poor linearity, the degree of regulation of existing domestic throttling valve are low, can not meet the requirement of MPD technology.

In addition, efficient, the general method for designing of neither one is gone back in the design of current spool.Method for designing that is main or that combine with experience, flow test and correction of the flank shape now.But such method for designing process is complicated, efficiency is low, the R&D cycle is long, development cost are high, seriously reduces the efficiency of enterprise.

Summary of the invention

Technical matters to be solved by this invention is, provides a kind of method for designing of throttling valve of pressure drop aperture linear change, and this method for designing can obtain the linearity of pressure control adjustment and the contour curve of the better spool of precision, and this method for designing is more efficient and general.

Technical solution of the present invention is, provide a kind of method for designing of throttling valve of pressure drop aperture linear change, it comprises the following steps:

The mathematical model of spool profile is set up according to the pressure drop characteristic of the target of the pressure drop of throttling valve and the linear relationship of aperture, throttling valve, area of passage and spool geometric condition, the equation of locus that the outline line deriving spool by equivalent area curvilinear equation should meet, drawn the contour curve of spool by this equation of locus, thus obtain the valve core structure of throttling valve.

Compared with prior art, the method for designing of the throttling valve of pressure drop aperture linear change of the present invention has the following advantages.The contour curve of spool can be obtained by the method, compared with the profile spool of existing orthoscopic, adopt meet the pressure control linearity of the spool of the curved profile of the pressure drop of throttling valve and the linear relationship of aperture and degree of regulation all better.And this method for designing can be commonly used to the design of a series of spool, then obtain contour curve and the valve core structure of corresponding spool according to the target of concrete spool and design parameter, more general.Therefore this method for designing can improve design efficiency, more efficiently.

In one embodiment, the pass between pressure drop Δ P and spool aperture L is: wherein K, C are constant, and Δ P is pressure drop before and after valve, L _maxrepresent the maximum opening of valve.Pressure drop also can be described as pressure reduction, at maximum opening L _maxtime corresponding maximum pressure drop Δ P _max, for specific spool, its maximum pressure drop Δ P after having designed _maxwith maximum opening L _maxbe a definite value, the aperture L of pressure drop Δ P and spool is linear.

In one embodiment, by the geometric condition d=D-2x of spool, and the pass obtained between the horizontal ordinate x of N point and area of passage Ar is: wherein D, d are respectively the circular diameter up and down of conical ring body, L _mNfor bus is long, θ is angle, and x is the horizontal ordinate of N point on valve core outline.Set up the relation between point on spool profile and area of passage.

In one embodiment, the pressure drop characteristic of throttling valve comprises the continuity equation of Bernoulli equation that the fluid through this throttling valve should meet and fluid, by pressure drop characteristic equation, aperture L and area of passage A _rbetween relation and linear relationship between pressure drop Δ P and spool aperture L set up the mathematical model of spool profile, this mathematical model is by the equivalent area curvilinear equation obtained $x^2-\mathrm{Dx}+\frac{\cos \mathrm{\θ}}{\mathrm{\π}}\sqrt{\frac{Q^2{A}^2\mathrm{\ρ}}{2\mathrm{A\ΔP}+Q^2\mathrm{\ρ}}}=0$ Represent.Point on the equivalent curve of areas is equal with the area of passage that some M is formed.

In one embodiment, if order $F=x^2-\mathrm{Dx}+\frac{\cos \mathrm{\θ}}{\mathrm{\π}}\sqrt{\frac{Q^2{A}^2\mathrm{\ρ}}{2\mathrm{A\ΔP}+Q^2\mathrm{\ρ}}}=0,$ The equivalent area curve family that under obtaining each aperture, the equivalent curve of areas forms, and by meeting formula

$\left\{\begin{array}{c}F=0\\ \frac{\∂F}{\∂\mathrm{\θ}}=0\end{array}\right.$ Solve the equation of locus that the outline line that obtains spool should meet.The F=0 equivalent area curve family that under representing each aperture, the equivalent curve of areas forms, due to valve core outline and all equivalent curves of areas all tangent, so spool profile should meet system of equations $\left\{\begin{array}{c}F=0\\ \frac{\∂F}{\∂\mathrm{\θ}}=0\end{array}\right..$

In a preferred embodiment, be 72m in discharge capacity ³designing a kind of size under the operating mode of/h is 2 " spool contour curve, and make its pressure drop Δ P and spool aperture L in its 20%-80% effective travel linear.2 " namely two inches, 50.8mm is equivalent to herein.In controlled pressure drilling, the spool of this size uses more.Therefore, the pressure control linearity and degree of regulation can be ensured preferably.

In a preferred embodiment, if Media density ρ=1.7g/cm ³, spool effective travel is within 30mm, if Δ P _max=10MPa, L _max=30mm, in above formula, parameters adopts following unit: the unit cm of area of passage A ²; The unit of pressure drop Δ P is 100KPa; The unit of fluid density ρ is g/cm ³; The unit of flow Q is m ³/ h, the system of equations that can obtain about x, y, θ is as follows:

$\left\{\begin{array}{c}{x}^2-50.8x+\frac{\cos \mathrm{\θ}}{\mathrm{\π}}\sqrt{\frac{{72}^2\×1.7}{{5.09}^2\×10\×(1-\frac{L}{30})+{72}^2\×1.7}}=0\\ \frac{\∂(x^2-50.8x+\frac{\cos \mathrm{\θ}}{\mathrm{\π}}\sqrt{\frac{{72}^2\×1.7}{{5.09}^2\×10\×(1-\frac{L}{30})+{72}^2\×1.7}})}{\∂\mathrm{\θ}}=0\\ L=y+x\tan \mathrm{\θ}\end{array}\right..$ The equation of locus that spool contour curve should meet can be obtained by system of equations.

In a preferred embodiment, in the open range being less than 30mm, get a point every 1mm, and value is assigned to L, obtain the spool point of throttling valve from L=0mm to L=30mm aperture.Facilitate value and calculating.Preferably, aided solving and curve is come by computer software.

In a preferred embodiment, matching is carried out to the spool point obtained, obtains the curvilinear equation that the contour curve of spool and this contour curve meet:

y＝-2.1721x ⁵+26.496x ⁴-130.27x ³+326.88x ²-428.56x+218.06(1.198≤x≤3.064)。

In a preferred embodiment, the contour curve equation of spool is simulated, draw the curve of aperture and pressure drop to verify.After the contour structure matching out of spool, whether linear in 20%-80% effective travel by the curve of checking aperture and pressure drop, if satisfy condition, then the spool profile of this design meets designing requirement, the linearity that when adopting this throttling valve to carry out controlled pressure drilling, pressure control regulates and precision all better.

The invention still further relates to a kind of spool of throttling valve, in particular for the spool of the throttling valve in drilling well, its adopt above-mentioned in method for designing design.This throttling valve can be the valve of throttling valve or other type, such as flow speed control valve.

Accompanying drawing explanation

It is the schematic diagram of a kind of orifice size of the throttling valve that method for designing according to the present invention designs shown in Fig. 1.

It is the pressure schematic diagram of the restriction in Fig. 1 shown in Fig. 2.

The contour surface curve of spool under arbitrary aperture of the throttling valve in Fig. 2 shown in Fig. 3.

It is the structural representation of the contour surface curve family of the spool in Fig. 3 shown in Fig. 4.

It is the spool contour curve obtained according to the spool matching of Fig. 4 shown in Fig. 5.

It is the aperture-pressure drop relationships curve of the spool in Fig. 5 shown in Fig. 6.

Embodiment

Below in conjunction with the drawings and specific embodiments, the invention will be further described.

According in an embodiment of method for designing of the present invention, at discharge capacity 72m ³designing a kind of size under the operating mode of/h is 2 " contour curve of the spool of (namely 2 inches, be equivalent to 50.8mm).It is easily understood that the spool of design 2 inches is only exemplary in specific embodiment in the present invention, method for designing of the present invention is applicable to the spool of any size, such as 1.5 inches, 3 inches, 5 inches or other size any etc.

In one embodiment, when the spool of design 2 inches, require that aperture L and pressure drop are linear in the effective travel of the 20%-80% of this spool.Wherein, the Media density ρ=1.7g/cm of employing ³, the effective travel of spool is not more than 30mm.

1) following formula can be adopted to represent according to the target of the linear relationship between the aperture of spool and pressure drop:

$\mathrm{\ΔP}=(1-\frac{L}{L_{\max }})\mathrm{\Δ}{P}_{\max }---(8-1)$

2) according to Fig. 1, when certain given spool position, if the minor increment between spool and valve seat is MN, then area of passage A _rit is exactly the lateral area of the conical ring face MNN1M1 in figure.

Area formula by conical ring face:

$A_r=\mathrm{\π}(\frac{D}{2}+\frac{d}{2})L_{\mathrm{MN}}---(7-2)$

In addition, d=D-2x, d, d are respectively the upper and lower circular diameter of conical ring body, L _mNfor bus is long.Have after substitution:

$x^2-\mathrm{Dx}+\frac{A_r}{\mathrm{\π}}\cos \mathrm{\θ}=0---(7-3)$

D is maximum diameter, and θ is angle, and x is the horizontal ordinate of N point on valve core outline.

3) according to Fig. 2, area of passage A is set up _rand the relational expression between pressure drop Δ P:

From Bernoulli equation:

$\frac{p_1}{\mathrm{\ρg}}+\frac{v_1^2}{2g}=\frac{p_2}{\mathrm{\ρg}}+\frac{v_2^2}{2g}\⇒h=\frac{\mathrm{\Δp}}{\mathrm{\ρg}}=\frac{v_2^2-v_1^2}{2g}---(7-4)$

Have according to fluid flowing continuity equation:

A＝A ₁，Q＝A ₁v ₁＝A ₂v ₂(7-5)

Simultaneous (7-4) and (7-5):

$A_r=A_2=\sqrt{\frac{Q^2{A}^2\mathrm{\ρ}}{2\mathrm{A\ΔP}+Q^2\mathrm{\ρ}}}---(7-6)$

4) spool profile mathematical model is set up:

Simultaneous formula (7-1), (7-3) and (7-6) obtain equivalent area curvilinear equation:

$x^2-\mathrm{Dx}+\frac{\cos \mathrm{\θ}}{\mathrm{\π}}\sqrt{\frac{Q^2{A}^2\mathrm{\ρ}}{2\mathrm{A\ΔP}+Q^2\mathrm{\ρ}}}=0---(7-7)$

Formula (7-7) represents under a certain aperture, with M point for benchmark, and the curve (i.e. the equivalent curve of areas) that the truncated cone bus that the side surface area of θ corresponding in span is equal is formed.Point on the equivalent curve of areas is equal with the area of passage that some M is formed, and as MC1, MC2, MC3 etc., sees Fig. 3.

5) make $F=x^2-\mathrm{Dx}+\frac{\cos \mathrm{\θ}}{\mathrm{\π}}\sqrt{\frac{Q^2{A}^2\mathrm{\ρ}}{2\mathrm{A\ΔP}+Q^2\mathrm{\ρ}}}=0---(7-8)$

Then F=0 represents the equivalent area curve family of the equivalent area Curves composition under each aperture, as shown in Figure 4.

Due to the outline line of spool and all contour surface curves all tangent, so spool contour curve meets:

$\left\{\begin{array}{c}F=0\\ \frac{\∂F}{\∂\mathrm{\θ}}=0\end{array}\right.---(7-9)$

Solve the profile equation that formula (7-9) can draw spool.

6) parameters adopts following unit: the unit of area of passage A is cm ²; The unit of pressure drop Δ P is 100KPa; The unit of fluid density ρ is g/cm ³; The unit of flow Q is m ³/ h.Substitute into designing requirement: Q=72m ³/ h, D=50.8mm, ρ=1.7g/cm ³, Δ P _max=10Mpa, L _max=30mm, can obtain the system of equations about x, y, θ:

$\left\{\begin{array}{c}{x}^2-50.8x+\frac{\cos \mathrm{\θ}}{\mathrm{\π}}\sqrt{\frac{{72}^2\×1.7}{{5.09}^2\×10\×(1-\frac{L}{30})+{72}^2\×1.7}}=0\\ \frac{\∂(x^2-50.8x+\frac{\cos \mathrm{\θ}}{\mathrm{\π}}\sqrt{\frac{{72}^2\×1.7}{{5.09}^2\×10\×(1-\frac{L}{30})+{72}^2\×1.7}})}{\∂\mathrm{\θ}}=0\\ L=y+x\tan \mathrm{\θ}\end{array}\right.---(8-2)$

7) every 1mm, a point is got for aperture, value is assigned to L, solving equation group (8-2), obtain the spool point of throttling valve from L=0mm to L=30mm aperture as following table 8-1 with this:

Table 8-1 spool different opening respective coordinates value (unit: mm)

Aperture L	X-coordinate	Y-coordinate	Aperture L	X-coordinate	Y-coordinate
						1	11.98	-0.9762	15	16.79	-14.9128
2	12.20	-1.9704	16	17.40	-15.8924
						3	12.43	-2.9606	17	18.09	-16.8795
4	12.68	-3.9829	18	18.86	-17.8418
						5	12.93	-4.9517	19	19.75	-18.8147
6	13.21	-5.9768	20	20.77	-19.7742
						7	13.50	-6.9754	21	21.95	-20.7141
8	13.80	-7.9454	22	23.33	-21.6188
						9	14.13	-8.9430	23	24.98	-22.4600
10	14.49	-9.9547	24	26.84	-23.1302
						11	14.87	-10.9426	25	28.83	-23.5927
12	15.28	-11.9245	26	30.64	-23.9299
						13	15.74	-12.9320	27	30.64	-23.9299
14	16.24	-13.9263

8) obtain the outline line of spool as shown in Figure 5 according to the coordinate figure obtained, obtaining contour curve equation by matching is: y=-2.1721x ⁵+ 26.496x ⁴-130.27x ³+ 326.88x ²-428.56x+218.06 (1.198≤x≤3.064).

9) go out contour curve according to method design of the present invention, use Matlab software programming program to simulate, the aperture-pressure fall-off curve of drafting as shown in Figure 6.

As shown in Figure 6, in whole stroke, along with the increase of spool aperture, pressure drop is descending.The linear relationship of aperture-pressure drop in the 20%-80% of stroke and the open range of 6mm to 24mm is good, meets designing requirement completely.

The invention still further relates to a kind of spool of throttling valve, in particular for the spool of the throttling valve in drilling operation, it adopts above-mentioned method design of the present invention to form.

Although invention has been described in conjunction with specific embodiments, but be appreciated that without departing from the scope of the invention, various improvement or replacement can be carried out to it.Especially, only otherwise there is structural conflict, the feature in each embodiment all can be combined with each other, and the combined type feature formed still is within the scope of the present invention.The present invention is not limited to specific embodiment disclosed in literary composition, but comprises all technical schemes fallen in the scope of claim.

Claims (10)

1. a method for designing for the throttling valve of pressure drop aperture linear change, comprises the following steps:

The mathematical model of spool profile is set up according to the pressure drop characteristic of the target of the pressure drop of throttling valve and the linear relationship of aperture, throttling valve, area of passage and spool geometric condition, the equation of locus that the outline line deriving spool by equivalent area curvilinear equation should meet, drawn the contour curve of spool by this equation of locus, thus obtain the valve core structure of throttling valve.

2. method according to claim 1, is characterized in that, the pass between pressure drop Δ P and spool aperture L is: wherein K, C are constant, and Δ P is pressure drop before and after valve, L _maxrepresent the maximum opening of valve.

3. method according to claim 1 and 2, is characterized in that, by the geometric condition d=D-2x of spool, $A_r=\mathrm{\π}(\frac{D}{2}+\frac{d}{2})L_{\mathrm{MN}}$ And $L_{\mathrm{MN}}=\frac{x}{\cos \mathrm{\θ}}$ Obtain horizontal ordinate x and the area of passage A of N point _rbetween pass be: wherein D, d are respectively the circular diameter up and down of conical ring body, L _mNfor bus is long, θ is angle, and x is the horizontal ordinate of N point on valve core outline.

4. method according to claim 3, is characterized in that, the pressure drop characteristic of throttling valve comprises the continuity equation of Bernoulli equation that the fluid through this throttling valve should meet and fluid, by pressure drop characteristic equation, aperture L and area of passage A _rbetween relation and linear relationship between pressure drop Δ P and spool aperture L set up the mathematical model of spool profile, this mathematical model is by the equivalent area curvilinear equation obtained $x^2-\mathrm{Dx}+\frac{\cos \mathrm{\θ}}{\mathrm{\π}}\sqrt{\frac{Q^2{A}^2\mathrm{\ρ}}{2\mathrm{A\ΔP}+Q^2\mathrm{\ρ}}}=0$ Represent.

5. method according to claim 4, is characterized in that, if order $F=x^2-\mathrm{Dx}+\frac{\cos \mathrm{\θ}}{\mathrm{\π}}\sqrt{\frac{Q^2{A}^2\mathrm{\ρ}}{2\mathrm{A\ΔP}+Q^2\mathrm{\ρ}}}=0,$ The equivalent area curve family that under obtaining each aperture, the equivalent curve of areas forms, and by meeting formula

$\left\{\begin{array}{c}F=0\\ \frac{\∂F}{\∂\mathrm{\θ}}=0\end{array}\right.$ Solve the equation of locus that the outline line that obtains spool should meet.

6. the method according to any one of Claims 1 to 5, is characterized in that, is 72m in discharge capacity ³designing a kind of size under the operating mode of/h is 2 " spool contour curve, and make its pressure drop Δ P and spool aperture L in its 20%-80% effective travel linear.

7. method according to claim 6, is characterized in that, if Media density ρ=1.7g/cm ³, spool effective travel is within 30mm, if Δ P _max=10MPa, L _max=30mm, in above formula, parameters adopts following unit: the unit of area of passage A is cm ²; The unit of pressure drop Δ P is 100KPa; The unit of fluid density ρ is g/cm ³; The unit of flow Q is m ³/ h, the system of equations that can obtain about x, y, θ is as follows:

$\left\{\begin{array}{c}{x}^2-50.8x+\frac{\cos \mathrm{\θ}}{\mathrm{\π}}\sqrt{\frac{{72}^2\×1.7}{{5.09}^2\×10\×(1-\frac{L}{30})+{72}^2\×1.7}}=0\\ \frac{\∂(x^2-50.8x+\frac{\cos \mathrm{\θ}}{\mathrm{\π}}\sqrt{\frac{{72}^2\×1.7}{{5.09}^2\×10\×(1-\frac{L}{30})+{72}^2\×1.7}})}{\∂\mathrm{\θ}}=0\\ L=y+x\tan \mathrm{\θ}\end{array}\right..$

8. method according to claim 7, is characterized in that, gets a point, and value is assigned to L in the open range being less than 30mm every 1mm, obtains the spool point of throttling valve from L=0mm to L=30mm aperture.

9. method according to claim 8, is characterized in that, carries out matching to the spool point obtained, and obtains the curvilinear equation that the contour curve of spool and this contour curve meet:

Y=-2.1721x ⁵+ 26.496x ⁴-130.27x ³+ 326.88x ²-428.56x+218.06 (1.198≤x≤3.064); Preferably, the contour curve equation of spool is simulated, draw the curve of aperture and pressure drop to verify.

10. a spool for throttling valve, is characterized in that, the method design according to any one of claim 1 ~ 9 forms.