CN101013416A - Hydrodynamic general design and checking method of boiler - Google Patents

Abstract

The invention discloses a universal design and check method for boiler hydrodynamic pressure, which uses the pressure of component as the basic method for computing hydrodynamic pressure. Then set out the pressure equation for the boiler DC circulatory system or natural components of the various targets and form an equation group. Solve the equations to get a new group of pressure values and add the values to the pressure of the imported components of system to get the pressure value for a new component layer. A further update is done on the component's flow of the older layer and a set out new pressure equations to the components whose value has been update. Repeat until the pressure and flow accuracy of various components of the DC circulatory system or natural components in the boiler all meet the requirements. The invention propose a general hydrodynamic model of boiler which can meet any pipe layout, and the boiler water power system is no longer divided based on serial and parallel, which makes the development of calculation software for hydrodynamic pressure possible.

Description

The method of a kind of boiler hydrodynamics universal design and check

Technical field

The invention belongs to Thermal Power Engineering Field, relate to boiler performance and calculate (design and check are calculated) method, the method for especially a kind of boiler hydrodynamics universal design and check.

Background technology

The performance computation of boiler comprises the calculating of boiler heating power calculating, Calculation of Hydrodynamic, intensity calculating and other boiler auxiliarieses etc.In Calculation of Hydrodynamic, most critical be assignment of traffic and Calculation of Pressure Drop.Because partition characteristic directly has influence on the security of boiler operatiopn.The workload of carrying out boiler hydrodynamics calculating by hand is very big.Along with the increase of boiler capacity and the raising of parameter, system type is more various, and the hydrodynamic system complexity sharply increases, and hand computation is consuming time bigly can not satisfy the demand.

The high efficiency calculated of using a computer is obvious to all, adopts computing machine to replace hydrodynamic hand computation to become trend.Many scholars and unit all write the Calculation of Hydrodynamic program, but existing program is all at a certain concrete boiler.The hydrodynamic system of boiler is determined before establishment.When the hydrodynamic system of boiler changes, just must regroup calculation procedure.Existing Calculation of Hydrodynamic program all can't be accomplished general, mainly is because can't be described boiler hydrodynamics system's employing unified form complexity, flexible arrangement.The method of drawing the hydrodynamic property curve is often adopted in hand computation.There has been at present document to announce the Calculation of Hydrodynamic machine algorithm of drawing the hydrodynamic property curve, as:

[1] Tian Pu, Chen Tingkuan, Bi Qincheng. multistage connection in series-parallel water screen system Calculation of Hydrodynamic. boiler technology .Vol 5,1996:6-12.

[2] Shanghai generating set of equipments research institute. station boiler Calculation of Hydrodynamic method .JB/Z 201-83.

If adopt the method for drawing the hydrodynamic property curve, the stack of curve and calculating regression process more complicated and difficulty, there is certain inaccuracy in curve fitting.Draw the hydrodynamic property curve and remain series relationship and relation in parallel based on system unit, and for a lot of neither the special shape of the non-parallel connection of series connection is helpless.When adopting iteration Method, must adopt different alternative manners at different system types, if new system type, then must adopt new iterative algorithm.Therefore, the diversity of system type has caused computing machine to carry out boiler hydrodynamics and has calculated very that complexity can not realize general again.One of way that solves is exactly to seek a kind of Unified Form that can describe complicated and diversified hydrodynamic system.Up to now, the open source literature that does not also have relevant patent and other type.

Summary of the invention

In order to overcome the above-mentioned boiler hydrodynamics deficiency in calculating, the present invention has proposed the method for a kind of boiler hydrodynamics universal design and check from the similarity of boiler hydrodynamics system and circuit, pipe network.This method is convenient to Computer Processing, improves the efficient that boiler hydrodynamics is calculated, and shortens the cycle that boiler design is made, for the exploitation of boiler hydrodynamics general-purpose computations software lays the first stone.

To achieve these goals, technical scheme of the present invention is: the method for a kind of boiler hydrodynamics universal design and check, it is characterized in that, this method adopts the basic skills of parts pressure application as Calculation of Hydrodynamic, then the straight-flow system of boiler or each target component of natural cycle system are listed pressure equation, and decomposition pressure system of equations, find the solution this pressure equation group and obtain one group of new force value, the force value that these are new adds the force value of system entry parts, obtain the force value of new each parts of level, upgrade the flow of each inferior target component of last layer again, this each target component behind the renewal flow is listed new pressure equation group once more, so repeatedly, till the pressure of each target component of the straight-flow system of boiler or natural cycle system and flow satisfy design accuracy.

Method of the present invention has proposed to satisfy the universal model that the boiler hydrodynamics of any line arrangement mode is calculated, and the boiler hydrodynamics system no longer divides according to series connection and parallel connection.Adopt this method not only can carry out only existing the Calculation of Hydrodynamic of series connection and the steam generator system that concerns in parallel, and can exist neither the Calculation of Hydrodynamic of the steam generator system of the special pipeline of the non-parallel connection again of connecting.This method makes the division of boiler hydrodynamics system simple and clear, and having shortened greatly uses a computer carries out the computing time that boiler hydrodynamics is calculated, and makes the general boiler hydrodynamics software for calculation of exploitation become possibility.

Description of drawings

Fig. 1 is the basic model figure of the inventive method.

Fig. 2 is the algorithm flow chart of parts pressure application.

Fig. 3 is the synoptic diagram of a true boiler hydrodynamics system, altogether in solid circles represent target component, empty circles is represented non-target component, arrow is represented the working medium flow direction.

In order more to be expressly understood the present invention, the present invention is described in further detail below in conjunction with instantiation that accompanying drawing and inventor provide.

Embodiment

According to technical scheme of the present invention, the method for boiler hydrodynamics universal design and check at first adopts the basic skills of parts pressure application as Calculation of Hydrodynamic, then straight-flow system and natural cycle system is done some special processings respectively.

The parts pressure application is carried out according to the following steps:

1) pressure of parts is meant the inlet pressure of parts.Each parts to the boiler hydrodynamics system are numbered, and make that each parts all has unique number in the system.Can find each parts by call number during calculating.Wherein mixing header, allocation set case and steam-water separator are target component.

2) in order to reduce the size of system of equations matrix of coefficients, reach the purpose that reduces storage space and improve computing velocity, only each target component is listed pressure equation respectively, wherein, consider the system of equations uniqueness of solution, except that the pressure equation of system entry parts, with other pressure equation decomposition pressure system of equations, based on the flow equilibrium of certain node, can derive the expression formula of pressure equation according to the relation of pressure and flow:

${\mathrm{<figure-callout\; id="0"\; label="p"\; filenames="A20071001737900121.png"\; state="\{\{state\}\}">p</figure-callout>}}_0\underset{I=1}{\overset{m+n}{\mathrm{\&Sigma;}}}\frac{1}{R_I{G}_I^0}-\underset{I=1}{\overset{m+n}{\mathrm{\&Sigma;}}}\frac{p_I}{R_{\mathrm{<figure-callout\; id="0"\; label="I\; G\; I"\; filenames="A20071001737900121.png"\; state="\{\{state\}\}">I</figure-callout>}}{G}_I^{}{}_0^{}}=\underset{I=1}{\overset{n}{\mathrm{\&Sigma;}}}\frac{{\left(\stackrel{\&OverBar;}{\mathrm{\&rho;}}\mathrm{gh}\right)}_I}{R_{\mathrm{Io}}{G}_{\mathrm{Io}}^0}-\underset{I=1}{\overset{m}{\mathrm{\&Sigma;}}}\frac{{\left(\stackrel{\&OverBar;}{\mathrm{\&rho;}}\mathrm{gh}\right)}_I}{R_{\mathrm{Ii}}{G}_{\mathrm{Ii}}^0}-G_s$

Wherein:

P ₀, P _I: expression parts pressure, subscript 0 expression is to this parts row pressure equation, referring to Fig. 1.Subscript I table: show the 1st standard laid down by the ministries or commissions of the Central Government parts, Pa;

: the average density of expression pipe, kg/m ³

M, n: m inlet branch road of expression parts 0, n outlet branch road is referring to Fig. 1;

G _I ⁰Certain the bar inlet an of-last iteration level parts I or the flow of outlet branch road, kg/s;

G _Io ⁰, G _Ii ⁰Certain bar inlet an of-last iteration level parts I, the flow of outlet branch road, kg/s;

G _SThe flow that is similar to current source current of-outflow from parts 0, kg/s;

R _I, R _Io, R _Ii-expression G _I ⁰, G _Io ⁰And G _Ii ⁰The quasi-resistance coefficient, the value of R is determined by following formula:

For monophasic fluid

$R=\frac{1}{A^2}[(\mathrm{\&lambda;}\frac{l}{2d_n}+\frac{\mathrm{\&zeta;}}{2})\stackrel{\&OverBar;}{v}+|v_2-v_1\left|\right]$

For two-phase fluid

$R=\frac{1}{A^2}\left\{(\mathrm{\&phi;\&lambda;}\frac{l}{2{\mathrm{\&rho;}}^{\&prime;}}+\frac{\mathrm{\&zeta;}}{2{\mathrm{\&rho;}}^{\&prime;}})\right[1+\stackrel{\&OverBar;}{x}(\frac{{\mathrm{\&rho;}}^{\&prime;}}{{\mathrm{\&rho;}}^{\&prime;\&prime;}}-1)]+|x_c-x_j\left|(v^{\&prime;\&prime;}-v^{\&prime;})\right\}$

Wherein:

The A-pipe section is long-pending, m ²

d _n-ips, m;

The l-tube length, m;

λ-coefficient of frictional resistance;

Correction coefficient falls in φ-frictional resistance pressure;

ζ-coefficient of shock resistance;

ρ ', ρ " saturation water density, saturated vapor density, kg/m ³

V ', v ", v ₁, v ₂,

-saturation water, saturated vapour, pipe inlet, pipe outlet, the average specific volume of pipe, m ³/ kg;

x _j, x _c, -pipe inlet, pipe outlet, the average mass dryness fraction of pipe.

Find the solution above-mentioned pressure equation group, obtain new force value.These values are added the force value of system entry parts simultaneously, obtain the force value of new each parts of level.

Upgrade the flow of each parts according to following formula

$G=\sqrt{\frac{U}{R}}$

Wherein:

The new level of U-parts, frictional resistance and local Resistance Value sum, Pa;

The quasi-resistance coefficient of the new level of R-branch road, Pas ²/ m ²

When calculating straight-flow system, carry out according to the following steps with said new method:

Give the pressure and the flow value initialize of parts, utilization said new method iterative computation is till the pressure of parts and flow satisfy certain precision.

When calculating natural cycle system, carry out according to the following steps with said new method:

1) annexation that disconnects all drums and enter the parts of drum, all enter virtual collection case of exit interpolation of the parts of drum again, and the outlet that makes all enter the parts of drum is this virtual collection case.

2) suppose the enthalpy of owing of water in the circulating ratio of natural cycle system and the drum, give the pressure and the flow initialize of parts.

3) utilization said new method iterative computation is till the pressure of parts and flow satisfy design accuracy.

4) calculate the enthalpy of owing of water in the circulating ratio of natural cycle system and the drum, and and default relatively, and whether the pressure of comparison system entrance and exit equates.If satisfy precision, then stop to calculate; If do not satisfy precision, that upgrades water in circulating ratio, the drum owes enthalpy and inlet pressure, calculates since 3) recomputate, till satisfying design accuracy.

Referring to Fig. 3, this figure is the synoptic diagram of a boiler actual water power system.This steam generator system is a straight-flow system.Solid circles is represented target component among the figure, and empty circles is represented other parts except that target component, and arrow is represented the working medium flow direction.Have 5 target components in the system, be numbered 0～4.According to the step of parts pressure application, list pressure equation respectively to being numbered 1～4 target component.To be numbered 2 target component is example, and these parts have 1 inlet branch road and 2 outlet branch roads.Calculate the RG of these branch road correspondences respectively ⁰With Calculate the every coefficient in this parts pressure equation again, list the pressure equation of these parts at last.With the corresponding respectively pressure equation decomposition pressure system of equations of target component that is numbered 1～4, find the solution the new force value that can obtain each target component correspondence, these values are added the force value of system entry parts simultaneously, obtain the force value of new each parts of level.Upgrade the flow that each imports and exports branch road with these new force value, obtain the flow value of each parts of a new level.The pressure of new and old level and flow value if satisfy accuracy requirement, then stop to calculate, and gained pressure and flow are exactly the result that asks; If do not satisfy accuracy requirement, then list new pressure equation, according to the step double counting of introducing previously, till satisfying precision with new pressure and flow.

Claims (4)

1. the method for boiler hydrodynamics universal design and check, it is characterized in that, this method adopts the basic skills of parts pressure application as Calculation of Hydrodynamic, then the straight-flow system of boiler or each target component of natural cycle system are listed pressure equation, and decomposition pressure system of equations, find the solution this pressure equation group and obtain one group of new force value, the force value that these are new adds the force value of system entry parts, obtain the force value of new each parts of level, upgrade the flow of each inferior target component of last layer again, this each target component behind the renewal flow is listed new pressure equation group once more, so repeatedly, till the pressure of each target component of the straight-flow system of boiler or natural cycle system and flow satisfy design accuracy.

2. the method for claim 1 is characterized in that, described parts pressure application is carried out according to the following steps:

1) pressure of parts is meant the inlet pressure of parts, and each parts of boiler hydrodynamics system are numbered, and makes that each parts all has unique number in the system; Can find each parts by call number during calculating, wherein mixing header, allocation set case and steam-water separator are target component;

2) in order to reduce the size of system of equations matrix of coefficients, reach the purpose that reduces storage space and improve computing velocity, only each target component is listed pressure equation respectively, wherein, consider the system of equations uniqueness of solution, except that the pressure equation of system entry parts, with other pressure equation decomposition pressure system of equations, based on the flow equilibrium of certain node, the expression formula that derives pressure equation according to the relation of pressure and flow is:

$p_0\underset{I=1}{\overset{m+n}{\mathrm{\&Sigma;}}}\frac{1}{R_I{G}_I^0}-\underset{I=1}{\overset{m+n}{\mathrm{\&Sigma;}}}\frac{p_I}{R_I{G}_I^0}=\underset{I=1}{\overset{n}{\mathrm{\&Sigma;}}}\frac{{\left(\stackrel{-}{\mathrm{\&rho;}}\mathrm{gh}\right)}_I}{R_{\mathrm{Io}}{G}_{\mathrm{Io}}^0}-\underset{I=1}{\overset{n}{\mathrm{\&Sigma;}}}\frac{{\left(\stackrel{-}{\mathrm{\&rho;}}\mathrm{gh}\right)}_I}{R_{\mathrm{Ii}}{G}_{\mathrm{Ii}}^0}-G_S$

Wherein:

p ₀, p _I: expression parts pressure, subscript 0 expression is to this parts row pressure equation, and subscript I represents I standard laid down by the ministries or commissions of the Central Government parts, unit: Pa;

The average density of expression pipe, unit: kg/m ³

M, n: m inlet branch road of expression parts 0, n outlet branch road;

G _l ⁰Certain the bar inlet an of-last iteration level parts I or the flow of outlet branch road, unit: kg/s;

G _Io ⁰, G _Ii ⁰Certain bar inlet an of-last iteration level parts I, the flow of outlet branch road, unit: kg/s;

G _s-the flow that from these parts, flows out, unit: kg/s;

R _I, R _Io, R _Ii-expression G _I ⁰, G _Io ⁰And G _Ii ⁰The quasi-resistance coefficient, the value of R is determined by following formula:

For monophasic fluid

$R=\frac{1}{A^2}\&lsqb;(\mathrm{\&lambda;}\frac{l}{2d_n}+\frac{\mathrm{\&zeta;}}{2})\stackrel{-}{v}+|v_2-v_1|\&rsqb;$

For two-phase fluid

$R=\frac{1}{A^2}\{(\mathrm{\&phi;\&lambda;}\frac{l}{2{\mathrm{\&rho;}}^{\&prime;}}+\frac{\mathrm{\&zeta;}}{2{\mathrm{\&rho;}}^{\&prime;}})\&lsqb;1+\stackrel{-}{x}(\frac{{\mathrm{\&rho;}}^{\&prime;}}{{\mathrm{\&rho;}}^{\&prime;\&prime;}}-1)\&rsqb;+|x_c-x_j\left|(v^{\&prime;\&prime;}-v^{\&prime;})\right\}$

In the formula:

The A-pipe section is long-pending, unit: m ²

d _n-ips, unit: m;

The l-tube length, unit: m;

λ-coefficient of frictional resistance;

Correction coefficient falls in φ-frictional resistance pressure;

ζ-coefficient of shock resistance;

ρ ', ρ " saturation water density, saturated vapor density, unit: kg/m ³

V ', v ", v ₁, v ₂,

-be respectively saturation water specific volume, saturated vapour specific volume, pipe inlet specific volume, pipe outlet specific volume, the average specific volume of pipe, unit: m ³/ kg;

x _j, x _c,

-be respectively pipe inlet mass dryness fraction, pipe outlet mass dryness fraction, the average mass dryness fraction of pipe.

3. the method for claim 1, it is characterized in that the computing method of each target component pressure of described straight-flow system and flow are to give the pressure and the flow value initialize of parts, the calculating that iterates again is till the pressure of parts and flow satisfy design accuracy.

4. the method for claim 1 is characterized in that, the calculating of each target component pressure of described natural cycle system and flow is carried out according to the following steps:

Step 1, the annexation that disconnects all drums and enter the parts of drum is added a virtual collection case in all exits that enter the parts of drum, and the outlet that makes all enter the parts of drum is this virtual collection case;

Step 2 is supposed the enthalpy of owing of water in the circulating ratio of natural cycle system and the drum, gives the pressure and the flow value initialize of parts;

Step 3, the calculating that iterates is till the pressure of parts and flow satisfy design accuracy;

Step 4 is calculated the enthalpy of owing of water in the circulating ratio of natural cycle system and the drum, and and default relatively, and whether the pressure of comparison system entrance and exit equates; If satisfy precision, then stop to calculate; If do not satisfy precision, that upgrades water in circulating ratio, the drum owes enthalpy and inlet pressure, calculates to begin to recomputate from step 3, till satisfying design accuracy.

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