CN104036084A - Distributed parametric modeling method for tubular receiver of tower solar thermal power plant - Google Patents

Abstract

The invention discloses a distributed parametric modeling method for a tubular receiver of a tower solar thermal power plant. According to the method, an overall mass conservation and energy conservation model of the tubular receiver of the tower solar thermal power plant, an mass conservation and energy conservation model of a steam drum, and a distributed mass conservation and energy conservation model of a receiving panel are established; the models are solved by a simultaneous method, and temperature rise features of tube wall metal of the tubular receiver are analyzed. The method has the advantages that distributed modeling is adopted, the feature that energy received by the tubular receiver is non-uniformly distributed is considered, simulation results are closer to actual situations than those obtained through existing lumped parameter models, the temperature rise features of the metal of the tubular receiver under solar radiation disturbances can be simulated by the method, and the safety operation problem of the tubular receiver is solved accordingly.

Description

The distribution parameter modeling method of tower type solar thermo-power station tubulose receiver

Technical field

The present invention relates to technical field of solar, particularly relating to medium is the tubular type receiver of water.

Background technology

Tower type solar thermo-power station is to utilize condenser system (Jing Chang) to assemble sun power, and in tower top receiver, working medium absorbs and is converted into heat energy, and then utilizes this heat energy to produce superheated vapor, and pushing turbine generating, finally realizes the conversion of solar energy to electrical.

In tower-type solar thermal power generating system, solar receiver is to realize the most key core technology of generating, and therefore, the modeling and simulation of receiver is the basis of whole power station being carried out to modeling and simulation.

Set up at present the lumped parameter dynamic model of tower type solar tubulose receiver.The each variable of model in lumped parameter model and locus are irrelevant, and it is homogeneous that variable is regarded as in whole system.This model has been simulated the actual motion state of receiver comparatively really.But lumped parameter model is supposed the energy even of accepting to assemble on panel and is distributed, and under actual conditions, accepting to receive solar radiant energy on panel is uneven distribution, has central energy high, the feature that periphery energy is low.Therefore, the dynamic property that lumped parameter model can only analog receiver entirety, can not obtain the each position of receiver dynamic property, as cycle rate, factor of created gase etc.Especially in the time of solar radiation disturbance, it is the same that lumped parameter is given tacit consent to each position metal temperature, and under actual conditions, on receiver panel, the temperature characterisitic of each position metal has very big-difference.

In order to improve receiver model, obtain result more accurately, receiver is carried out to distribution parameter modeling herein, to accepting panel gridding.In distributed parameter model, variable is relevant with locus, and therefore can simulate dash receiver is the dynamic perfromance of internal flow in uneven distribution situation at the energy receiving, more closing to reality situation, and simulation result is more accurate.

In addition, according to receiver apparatus code requirement, increasing temperature and pressure must be slow, temperature rise should not exceed 55 DEG C/h, the expansion situation of tackling each swelling heat pressure-containing member in the process of boosting exercises supervision, and finds non-homogeneous expansion or is stuck, and should take measures in time to be eliminated.Distributed model can well obtain the intensification dynamic perfromance of the each position of dash receiver metal, and therefore, to receiver, safe operation has directive function.

Summary of the invention

In order to overcome above-mentioned the deficiencies in the prior art, the invention provides a kind of distribution parameter modeling method of tower type solar thermo-power station tubulose receiver.Comprise:

Step (1) is set up total quality conservation, the modeling of energy conservation of tower type solar thermo-power station tubulose receiver.

If Fig. 1 is tubular type receiver model schematic diagram, (a) figure is front schematic view, and (b) figure is side schematic view.

Receiver operation principle: be steam water interface in upper collecting chamber, wherein water, because gravity declines naturally, enters tedge through downtake, absorb sun power vaporization and form steam, because steam water interface density is less than the density of water, therefore naturally rise and get back to upper collecting chamber, so circulation.

Due to the complicacy of receiver model, when modeling, answering system is simplified, and makes following hypothesis simultaneously:

1. whole vapo(u)rization system is saturated mode;

2. ignore evaporating area Working fluid flow resistance and gravity head and change, power pressure synchronously changes everywhere, identical with upper collecting chamber pressure;

3. on dash receiver tedge xsect, vapour-liquid is even, and water is identical with the flow velocity of steam.

The distribution parameter modeling method of tower type solar thermo-power station tubulose receiver comprises the following steps:

1) set up total quality conservation, the modeling of energy conservation of tower type solar thermo-power station tubulose receiver;

Measure solar radiation on same day DNI value, according to thermo-power station mirror-reflection area, mirror field efficiency, stage efficiency, heliostat reflectivity and receiver efficiency, calculate the solar heat Q that offers working medium in receiver sheet; Measure feedwater flow q _f, steam flow q _s;

Energy Q computing formula is as follows:

Q=DNI × S _m× η _{mirror field efficiency}× η _trunc× η _ref× η _clr(1)

Wherein, DNI represents solar radiant energy value; S _mfor mirror-reflection area; η _{mirror field efficiency}represent the average efficiency of Jing Chang, for mirror field atmospheric transmissivity, cosine efficiency and shade block the average of efficiency achievement; η _refrepresent the efficiency of blocking at that time; η _refrepresent heliostat reflectivity; η _clrthe cleanliness that represent heliostat, these values all obtain from actual mirror field situation;

The tubulose receiver system mass conservation is as follows:

$\frac{d}{\mathrm{dt}}[{\mathrm{\ρ}}_s{V}_{\mathrm{st}}+{\mathrm{\ρ}}_w{V}_{\mathrm{wt}}]=q_f-q_s---\left(2\right)$

Tubulose receiver system energy conservation is as follows:

$\frac{d}{\mathrm{dt}}[{\mathrm{\ρ}}_s{h}_s{V}_{\mathrm{st}}+{\mathrm{\ρ}}_w{h}_w{V}_{\mathrm{wt}}-{\mathrm{\ρV}}_t+m_t{C}_p{T}_m]=Q+q_f{h}_f-q_s{h}_s---\left(3\right)$

Wherein, ρ is density, and h is specific enthalpy, C _pfor metal heat, T is temperature, and V is volume, and p is system pressure; Subscript s represents steam, and w represents water, and m represents metal, and t represents whole system; V _st, V _wtbe respectively total vapour volume and water volume, V _tfor whole system cumulative volume, have:

V _t＝V _st+V _wt (4)

2) set up the tower type solar thermo-power station tubulose receiver drum mass conservation, modeling of energy conservation;

Steam and aqueous mixtures enter drum from dash receiver tedge, and feedwater also enters drum, and water flows out and enters downtake from drum, and steam leaves drum from valve, and subscript d represents drum, V _sd, V _wdrepresent respectively the volume of steam and water under drum liquid level, q _sdunder expression drum liquid level, water flashes to the flow of steam, q _cdrepresent the flow of steam-condensation Cheng Shui on drum liquid level, q _rthe working medium flow that represent to flow out receiver sheet, flows into drum, α _rrepresent working medium flow q _rin quality of steam number percent, under drum liquid level, mass balance equation is as follows:

$\frac{d}{\mathrm{dt}}\left({\mathrm{\ρ}}_s{V}_{\mathrm{sd}}\right)={\mathrm{\α}}_r{q}_r-q_{\mathrm{sd}}-q_{\mathrm{cd}}---\left(5\right)$

Wherein:

$q_{\mathrm{cd}}=\frac{h_w-h_f}{h_c}{q}_f+\frac{1}{h_c}({\mathrm{\ρ}}_s{V}_{\mathrm{sd}}\frac{{\mathrm{dh}}_s}{\mathrm{dt}}+{\mathrm{\ρ}}_w{V}_{\mathrm{wd}}\frac{{\mathrm{dh}}_w}{\mathrm{dt}}-(V_{\mathrm{sd}}+V_{\mathrm{wt}})\frac{\mathrm{dp}}{\mathrm{dt}}+m_d{C}_p\frac{{\mathrm{dT}}_s}{\mathrm{dt}})---\left(6\right)$

Q _sdbe an empirical model, β is empirical parameter:

$q_{\mathrm{sd}}=\frac{{\mathrm{\ρ}}_s}{T_d}(V_{\mathrm{sd}}-V_{\mathrm{sd}}^0)+{\mathrm{\α}}_r{q}_{\mathrm{dc}}+{\mathrm{\α}}_r\mathrm{\β}(q_{\mathrm{dc}}-q_r)---\left(7\right)$

Wherein h _c=h _s-h _f, the enthalpy difference of expression water vapor and water; be illustrated in and there is no vapour volume in condensation situation water drum; T _dit is the residence time of steam in drum;

V _wdfor the cumulative volume of water in drum, equal the total water volume V of system _wtdeduct the volume V of water in downtake _dcvolume with water in dash receiver wherein subscript dc represents downtake, and subscript r represents dash receiver, represent the average external volume number percent of steam in whole dash receiver:

l is liquid level of steam drum, equals in drum water volume V under liquid level _wdwith vapour volume V under liquid level _sddivided by the long-pending A of drum average cross-section _d, concrete formula is as follows:

$l=\frac{V_{\mathrm{wd}}+V_{\mathrm{sd}}}{A_d}---\left(9\right)$

3) set up tower type solar thermo-power station tubulose receiver receiver sheet distributed energy conservation, mass conservation model;

Dash receiver is made up of m root pipe altogether, every pipe is divided into n section, dash receiver can be divided into m × n little module, consider i (0 < i≤m) root VERTICAL TUBE, to its j, (0≤j≤n) section is carried out module modeling, in this section, ρ (i, j) represents steam-water mixing density, q (i, j) representation quality flow rate, A (i, j) represents the cross-sectional area of pipe, V (i, j) be volume, h (i, j) is specific enthalpy, Q (i, j) be available to the heat of this section of fluid, z (i, j) is this segment length;

Obtain quality, energy conservation equation is as follows, wherein, q _dc, q _rrepresent respectively this section of entrance, outlet rate of flow of fluid:

$\left\{\begin{array}{c}\frac{d}{\mathrm{dt}}({\mathrm{\&rho;}}_s{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v(i,j)V(i,j)+{\mathrm{\&rho;}}_w(1-{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v(i,j))V(i,j))=q_{\mathrm{dc}}(i,j)-q_r(i,j)\\ \frac{d}{\mathrm{dt}}({\mathrm{\&rho;}}_s{h}_s{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v(i,j)V(i,j)+{\mathrm{\&rho;}}_w{h}_w(1-{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v(i,j))V(i,j)-{\mathrm{pV}}_r(i,j)+m_r(i,j)C_p{T}_s)\\ =q_{\mathrm{dc}}(i,j)({\mathrm{\&alpha;}}_r(i,j-1)h_c+h_w)+Q(i,j)-({\mathrm{\&alpha;}}_r(i,j)h_c+h_w)q_r(i,j)\end{array}\right.---\left(10\right)$

α in above formula _r(i, 0), expression be the inlet steam content of first paragraph pipe, because entrance is saturation water, therefore there is α _r(i, 0)=0;

Dash receiver metal pipe-wall temperature is T _m, dash receiver metal quality is m _r, metal heat is C _p, the energy that metal receives is Q _m, heat interchanging area is A _i, convective heat-transfer coefficient is h _i, tube wall is carried out to dynamic modeling:

$m_r{C}_p\frac{{\mathrm{dT}}_m}{\mathrm{dt}}=Q_m(i,j)-A_i{h}_i(T_m(i,j)-T_s(i,j))---\left(11\right)$

Tube wall passes to receiver internal working medium heat and is

Q(i,j)＝A _ih _i(T _m(i,j)-T _s(i,j)) (12)

Can obtain the inlet flow rate q of i root pipe according to the momentum conservation of dash receiver and downtake _dc0, represent the contained vapour volume number percent of fluid in i root pipe, V ₀(i) volume of expression i root pipe, k is dash receiver and downtake closed circuit friction factor:

$\frac{1}{2}{\mathrm{kq}}_{\mathrm{dc}0}^2\left(i\right)={\mathrm{\&rho;}}_w{A}_{\mathrm{dc}}({\mathrm{\&rho;}}_w-{\mathrm{\&rho;}}_s)g{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_{v0}\left(i\right)V_0\left(i\right)---\left(13\right)$

Wherein

$\begin{array}{c}{V}_0\left(i\right)=\underset{j=1}{\overset{n}{\mathrm{\&Sigma;}}}V(i,j)\\ {\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_{v0}\left(i\right)=\frac{\underset{j=1}{\overset{n}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_{v0}(i,j)\&times;V(i,j)}{V_0\left(i\right)}\end{array}+---\left(14\right)$

4) set up water and steam physical property relational model;

5) utilize the method for simultaneous solution to solve described tubulose receiver distributed model.

Described step 3) in tower type solar thermo-power station tubulose receiver receiver sheet distributed energy conservation, mass conservation model inference step as follows:

Row are write quality, energy conservation equation:

$\left\{\begin{array}{c}A(i,j)\frac{\&PartialD;\mathrm{\&rho;}(i,j)}{\&PartialD;t}+\frac{\&PartialD;q(i,j)}{\&PartialD;z(i,j)}=0\\ \frac{\&PartialD;\mathrm{\&rho;}(i,j)h(i,j)}{\&PartialD;t}+\frac{1}{A(i,j)}\frac{\&PartialD;q(i,j)h(i,j)}{\&PartialD;z(i,j)}=\frac{Q(i,j)}{V(i,j)}\end{array}\right.---\left(15\right)$

α _mrepresent the shared mass percent of steam in fluid, h _s, h _wrepresent respectively the specific enthalpy of saturated vapour and saturation water, fluid specific enthalpy h (i, j) can be expressed as:

h(i,j)＝α _m(i,j)h _s+(1-α _m(i,j))h _w＝α _m(i,j)h _c+h _w (16)

When stable state, quality, energy conservation are:

$\left\{\begin{array}{c}\frac{\&PartialD;q(i,j)}{\&PartialD;z(i,j)}=0\\ \frac{\&PartialD;q(i,j)h(i,j)}{\&PartialD;z(i,j)}=q(i,j)h_c\frac{{\&PartialD;\mathrm{\&alpha;}}_m(i,j)}{\&PartialD;z(i,j)}=\frac{Q(i,j)A(i,j)}{V(i,j)}\end{array}\right.---\left(17\right)$

Can be obtained by (17):

${\mathrm{\&alpha;}}_m(i,j)=\frac{Q(i,j)A(i,j)}{q(i,j)h_{c}V(i,j)}z(i,j)---\left(18\right)$

In this section, heat Q (i, j) sometime, sectional area A (i, j), flow q (i, j), volume V (i, j) is definite value, visible α _m(i, j) and z (i, j) are linear.Do following normalizing: establishing ξ is a linear coefficient, corresponding to tedge length, α _rfor this section outlet quality of steam number percent, along the mass ratio of length be:

α _m(i,j)＝α _r(i,j)ξ0≤ξ≤1 (19)

And volume ratio α _v(i, j) and mass ratio α _mthe relation of (i, j) is as follows:

${\mathrm{\&alpha;}}_v(i,j)=\frac{{\mathrm{\&rho;}}_w{\mathrm{\&alpha;}}_m(i,j)}{{\mathrm{\&rho;}}_s+({\mathrm{\&rho;}}_w-{\mathrm{\&rho;}}_s){\mathrm{\&alpha;}}_m(i,j)}---\left(20\right)$

Thereby can obtain average external volume ratio

${\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v(i,j)={\&Integral;}_0^1{\mathrm{\&alpha;}}_v(i,j)---\left(21\right).$

Described step 2) the vapoury percent by volume of whole dash receiver inner fluid for each module equivalence and, result is as follows:

${\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v=\frac{\underset{i=1}{\overset{m}{\mathrm{\&Sigma;}}}\underset{j=1}{\overset{n}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v(i,j)}{m\&times;n}---\left(22\right).$

Described step 4) set up water and steam physical property relational model be water and steam character international association announce industrial standard IAPWS-IF97.

Compared with prior art, the present invention has the following advantages:

The solar radiant energy of having considered to be gathered on dash receiver due to the modeling method of tubulose receiver of the present invention is uneven distribution, adopt distributed modeling, dash receiver is carried out to gridding, therefore can go out each position interior media dynamic perfromance of receiver by analogue simulation, obtain steam production and liquid level of steam drum more accurately.And described model can emulation show that the each position of dash receiver pipe surface temperature is subject to the impact of solar radiation disturbance, relate to the security of receiver operation, this result can provide foundation for Power Plant Design focusing strategy.

Brief description of the drawings

Fig. 1 is tubular type receiver model schematic diagram, and Fig. 1 (a) is front schematic view, and Fig. 1 (b) is side schematic view;

Fig. 2 is tubular type receiver receiver sheet i root VERTICAL TUBE distributed model schematic diagram;

Fig. 3 is energy distribution schematic diagram on receptacle;

Fig. 4 is distributed parameter model and lumped parameter model system pressure comparison diagram;

Fig. 5 is that distributed parameter model compares comparison diagram with the shared quality of lumped parameter model dash receiver outlet steam;

Fig. 6 is distributed parameter model and lumped parameter model dash receiver outlet working medium flow comparison diagram;

Fig. 7 is vapour volume number percent comparison diagram in distributed parameter model and lumped parameter model dash receiver;

Fig. 8 is distributed parameter model and lumped parameter model liquid level of steam drum comparison diagram;

Fig. 9 is distributed parameter model receiver pipe surface temperature.

Embodiment

Below in conjunction with accompanying drawing, the present invention is further described.

Measure solar radiation on same day DNI value, according to thermo-power station mirror-reflection area, mirror field efficiency, stage efficiency, heliostat reflectivity and receiver efficiency, calculate the solar heat Q that offers working medium in receiver sheet; Measure feedwater flow q _f, steam flow q _s.

Energy Q computing formula is as follows:

Q=DNI × S _m× η _{mirror field efficiency}× η _trunc× η _ref× η _clr(1)

Mass of system conservation:

$\frac{d}{\mathrm{dt}}[{\mathrm{\&rho;}}_s{V}_{\mathrm{st}}+{\mathrm{\&rho;}}_w{V}_{\mathrm{wt}}]=q_f-q_s---\left(2\right)$

System capacity conservation:

$\frac{d}{\mathrm{dt}}[{\mathrm{\&rho;}}_s{h}_s{V}_{\mathrm{st}}+{\mathrm{\&rho;}}_w{h}_w{V}_{\mathrm{wt}}-{\mathrm{\&rho;V}}_t+m_t{C}_p{T}_m]=Q+q_f{h}_f-q_s{h}_s---\left(3\right)$

Wherein, ρ is density, and h is specific enthalpy, C _pfor metal heat, T is temperature, and V is volume, and p is system pressure; Subscript s represents steam, and w represents water, and m represents metal, and t represents whole system; V _st, V _wtbe respectively total vapour volume and water volume, V _tfor whole system cumulative volume, have:

V _t＝V _st+V _wt (4)

Step (2) is set up the tower type solar thermo-power station tubulose receiver drum mass conservation, modeling of energy conservation.

As shown in Fig. 1 (b), steam and aqueous mixtures enter drum from dash receiver tedge, and feedwater also enters drum, and water flows out and enters downtake from drum, and steam leaves drum from valve, and subscript d represents drum, V _sd, V _wdrepresent respectively the volume of steam and water under drum liquid level, q _sdunder expression drum liquid level, water flashes to the flow of steam, q _cdrepresent the flow of steam-condensation Cheng Shui on drum liquid level, q _rthe working medium flow that represent to flow out receiver sheet, flows into drum, α _rrepresent working medium flow q _rin quality of steam number percent, under drum liquid level, mass balance equation is as follows:

$\frac{d}{\mathrm{dt}}\left({\mathrm{\&rho;}}_s{V}_{\mathrm{sd}}\right)={\mathrm{\&alpha;}}_r{q}_r-q_{\mathrm{sd}}-q_{\mathrm{cd}}---\left(5\right)$

Wherein:

$q_{\mathrm{cd}}=\frac{h_w-h_f}{h_c}{q}_f+\frac{1}{h_c}\left(\begin{array}{c}{\mathrm{\&rho;}}_s{V}_{\mathrm{sd}}\frac{{\mathrm{dh}}_s}{\mathrm{dt}}+{\mathrm{\&rho;}}_w{V}_{\mathrm{wt}}\frac{{\mathrm{dh}}_w}{\mathrm{dt}}\\ -(V_{\mathrm{sd}}+V_{\mathrm{wt}})\frac{\mathrm{dp}}{\mathrm{dt}}+m_d{C}_p\frac{{\mathrm{dt}}_s}{\mathrm{dt}}\end{array}\right)---\left(6\right)$

Q _sdbe an empirical model, β is empirical parameter:

$q_{\mathrm{sd}}=\frac{{\mathrm{\&rho;}}_s}{T_d}(V_{\mathrm{sd}}-V_{\mathrm{sd}}^0)+{\mathrm{\&alpha;}}_r{q}_{\mathrm{dc}}+{\mathrm{\&alpha;}}_r\mathrm{\&beta;}(q_{\mathrm{dc}}-q_r)---\left(7\right)$

Wherein h _c=h _s-h _f, the enthalpy difference of expression water vapor and water; be illustrated in and there is no vapour volume in condensation situation water drum; T _dit is the residence time of steam in drum.

V _wdfor the cumulative volume of water in drum, equal the total water volume V of system _wtdeduct the volume V of water in downtake _dcvolume with water in dash receiver wherein subscript dc represents downtake, and subscript r represents dash receiver, represent the average external volume number percent of steam in whole dash receiver:

$V_{\mathrm{wd}}=V_{\mathrm{wt}}-V_{\mathrm{dc}}-(1-{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v)V_r---\left(8\right)$

L is liquid level of steam drum, equals in drum water volume V under liquid level _wdwith vapour volume V under liquid level _sddivided by the long-pending A of drum average cross-section _d, concrete formula is as follows:

$l=\frac{V_{\mathrm{wd}}+V_{\mathrm{sd}}}{A_d}---\left(9\right)$

Step (3) is set up tower type solar thermo-power station tubulose receiver and is accepted panel distributed energy conservation, mass conservation model.

As shown in Figure 2, the total m root pipe composition of dash receiver one, is divided into n section by every pipe, dash receiver can be divided into m × n little module, consider i (0 < i≤m) root VERTICAL TUBE, to its j, (section of 0≤j≤n) is carried out module modeling, in this section, ρ (i, j) represent steam-water mixing density, q (i, j) representation quality flow rate, A (i, j) represent the cross-sectional area of pipe, V (i, j) is volume, h (i, j) be specific enthalpy, Q (i, j) is available to the heat of this section of fluid, z (i, j) is this segment length.

Row are write quality, energy conservation equation:

$\left\{\begin{array}{c}A(i,j)\frac{\&PartialD;\mathrm{\&rho;}(i,j)}{\&PartialD;t}+\frac{\&PartialD;q(i,j)}{\&PartialD;z(i,j)}=0\\ \frac{\&PartialD;\mathrm{\&rho;}(i,j)h(i,j)}{\&PartialD;t}+\frac{1}{A(i,j)}\frac{\&PartialD;q(i,j)h(i,j)}{\&PartialD;z(i,j)}=\frac{Q(i,j)}{V(i,j)}\end{array}\right.---\left(10\right)$

α _mrepresent the shared mass percent of steam in potpourri, h _s, h _wrepresent respectively the specific enthalpy of saturated vapour and saturation water, fluid specific enthalpy h (i, j) can be expressed as:

h(i,j)＝α _m(i,j)h _s+(1-α _m(i,j))h _w＝α _m(i,j)h _c+h _w (11)

When stable state, quality, energy conservation are:

$\left\{\begin{array}{c}\frac{\&PartialD;q(i,j)}{\&PartialD;z(i,j)}=0\\ \frac{\&PartialD;q(i,j)h(i,j)}{\&PartialD;z(i,j)}=q(i,j)h_c\frac{{\&PartialD;\mathrm{\&alpha;}}_m(i,j)}{\&PartialD;z(i,j)}=\frac{Q(i,j)A(i,j)}{V(i,j)}\end{array}\right.---\left(12\right)$

Can be obtained by (12):

${\mathrm{\&alpha;}}_m(i,j)=\frac{Q(i,j)A(i,j)}{q(i,j)h_{c}V(i,j)}z(i,j)---\left(13\right)$

In this section, heat Q (i, j) sometime, sectional area A (i, j), flow q (i, j), volume V (i, j) is definite value, visible α _m(i, j) and z (i, j) are linear.Doing following normalizing: establishing ξ is a linear coefficient (corresponding to tedge length), is this section outlet quality of steam number percent, along the mass ratio of length is:

α _m(i,j)＝α _r(i,j)ξ 0≤ξ≤1 (14)

And volume ratio α _v(i, j) and mass ratio α _mthe relation of (i, j) is as follows:

${\mathrm{\&alpha;}}_v(i,j)=\frac{{\mathrm{\&rho;}}_w{\mathrm{\&alpha;}}_m(i,j)}{{\mathrm{\&rho;}}_s+({\mathrm{\&rho;}}_w-{\mathrm{\&rho;}}_s){\mathrm{\&alpha;}}_m(i,j)}---\left(15\right)$

Thereby can obtain average external volume ratio

${\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v(i,j)={\&Integral;}_0^1{\mathrm{\&alpha;}}_v(i,j)---\left(16\right)$

The vapoury percent by volume of whole dash receiver inner fluid for each module equivalence and, result is as follows:

${\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v=\frac{\underset{i=1}{\overset{m}{\mathrm{\&Sigma;}}}\underset{j=1}{\overset{n}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v(i,j)}{m\&times;n}---\left(17\right)$

By formula (10), at length dimension z (i, j) integration, revised quality, energy conservation equation are as follows, wherein, and q _dc, q _rrepresent respectively this section of entrance, outlet rate of flow of fluid:

$\left\{\begin{array}{c}\frac{d}{\mathrm{dt}}({\mathrm{\&rho;}}_s{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v(i,j)V(i,j)+{\mathrm{\&rho;}}_w(1-{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v(i,j))V(i,j))=q_{\mathrm{dc}}(i,j)-q_r(i,j)\\ \frac{d}{\mathrm{dt}}({\mathrm{\&rho;}}_s{h}_s{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v(i,j)V(i,j)+{\mathrm{\&rho;}}_w{h}_w(1-{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v(i,j))V(i,j)-{\mathrm{pV}}_r(i,j)+m_r(i,j)C_p{T}_s)\\ =q_{\mathrm{dc}}(i,j)({\mathrm{\&alpha;}}_r(i,j-1)h_c+h_w)+Q(i,j)-({\mathrm{\&alpha;}}_r(i,j)h_c+h_w)q_r(i,j)\end{array}\right.---\left(18\right)$

In above formula, relate to α _r(i, 0), expression be the inlet steam content of first paragraph pipe, because entrance is saturation water, therefore there is α _r(i, 0)=0.

If dash receiver metal pipe-wall temperature is T _m, metal quality is m _r, metal heat is C _p, the energy that metal receives is Q _m, heat interchanging area is A _i, convective heat-transfer coefficient is h _i, tube wall is carried out to dynamic modeling:

$m_r{C}_p\frac{{\mathrm{dT}}_m}{\mathrm{dt}}=Q_m(i,j)-A_i{h}_i(T_m(i,j)-T_s(i,j))---\left(19\right)$

Tube wall passes to receiver internal working medium heat and is

Q(i,j)＝A _ih _i(T _m(i,j)-T _s(i,j)) (20)

Can obtain the inlet flow rate q of i root pipe according to the momentum conservation of dash receiver and downtake _dc0, represent the contained vapour volume number percent of fluid in i root pipe, V ₀(i) volume of expression i root pipe, k is dash receiver and downtake closed circuit friction factor:

$\frac{1}{2}{\mathrm{kq}}_{\mathrm{dc}0}^2(i,)={\mathrm{\&rho;}}_w{A}_{\mathrm{dc}}({\mathrm{\&rho;}}_w-{\mathrm{\&rho;}}_s)g{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_{v0}\left(i\right)V_0\left(i\right)---\left(21\right)$

Wherein

$\begin{array}{c}{V}_0\left(i\right)=\underset{j=1}{\overset{n}{\mathrm{\&Sigma;}}}V(i,j)\\ {\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_{v0}\left(i\right)=\frac{\underset{j=1}{\overset{n}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_{v0}(i,j)\&times;V(i,j)}{V_0\left(i\right)}\end{array}+---\left(22\right).$

Step (4) is set up water and steam physical property relational model.Because model hypothesis whole system of the present invention is saturated mode, region 4 (saturated mode) equation in the industrial standard IAPWS-IF97 that therefore water and steam relational model is announced with reference to water and steam character international association.

Step (5) utilizes the method for simultaneous solution to solve described tubulose receiver distributed model.Simultaneous method solves and can on different software platforms, realize, as AMPL, GAMS, gPROMS etc.

The platform that solves of the embodiment of the present invention is gPROMS.GPROMS process simulation software is the universal process analog platform of new generation that process equipment and flow process is carried out to simulation modeling and design optimization, originates from Imperial College of Britain, has process simulation ability advanced in the world and multinomial distinctive emulation technology.

1) distributed parameter model and lumped parameter model contrast

According to actual DNI value on July 25th, 2013, utilize full Jing Chang to focus on the modeling and simulating of receiver, obtaining the gross energy that receiver receives is 300.44KW, lumped parameter model to receiver and distributed parameter model carry out emulation respectively, keep drum inflow and steam bleeding amount constant in 0.132kg/s, emulation is to 100s, and the energy that receiver receives steps to 330KW, relatively simulation result.

As shown in Figure 4, because distributed parameter model is identical with the energy that lumped parameter model receiver receives, inflow is identical with displacement, and according to energy conservation, system pressure (the being Temperature of Working) result that two kinds of model emulations obtain is basically identical.

As shown in Figure 5, lumped parameter model outlet quality of steam ratio is less than distributed parameter model outlet quality of steam ratio, this is because lumped parameter model receiver energy distribution is even, and energy is inhomogeneous on distributed parameter model receiver, there is intermediate energy high, the feature that both sides energy reduces gradually, more tallies with the actual situation.

As shown in Figure 6, lumped parameter model outlet working medium flow is greater than distributed parameter model outlet working medium flow, this is because lumped parameter model receiver energy distribution is even, and energy is inhomogeneous on distributed parameter model receiver, there is intermediate energy high, the feature that both sides energy reduces gradually, more tallies with the actual situation.

As shown in Figure 7, in lumped parameter model dash receiver, vapour volume number percent is greater than vapour volume number percent in distributed parameter model dash receiver, this be due to cycle rate square with dash receiver in the proportional relation of vapour volume number percent, the cycle rate of lumped parameter model, it is the outlet working medium flow shown in Fig. 6, cycle rate than distributed parameter model is high, therefore vapour volume number percent is higher than vapour volume number percent in distributed parameter model dash receiver in lumped parameter model dash receiver.

As shown in Figure 8, lumped parameter model liquid level of steam drum is greater than distributed parameter model liquid level of steam drum, this is because the total vapour volume of two kinds of models is identical, and lumped parameter model vapour volume in dash receiver is greater than distributed parameter model vapour volume in dash receiver, therefore the vapour volume of distributed parameter model in drum is greater than lumped parameter model, thereby cause lumped parameter model liquid level of steam drum to be greater than distributed parameter model liquid level of steam drum.

2) dash receiver pipe surface temperature is analyzed

Fig. 9 is the distributed parameter model of tower type solar thermo-power station tubulose receiver, the energy step 10% that receiver receives in the time of 100s, certain metal intensification situation of 5 sections on receiver, and receiver lumped parameter model (receiving uniform heat distribution), the energy step 10% in the time of 100s, receiver being received, receiver bulk metal intensification situation.As shown in Figure 6, after energy step, metal temperature all rises, but distributed parameter model section 3 (receiver interlude, accept energy thick) the obviously section of being greater than 2,3,4,5 (receiver edge sections of intensification, accept energy less), because section 2 and section 4 are positioned at antimere on receiver, therefore two curves overlap substantially; In like manner, section 3 and 5 two curves of section also overlap substantially.Concrete numerical value is as shown in table 3, lumped parameter model metal programming rate is 36.85 DEG C/h, can only reflect the average heating speed of whole receiver, distributed parameter model can represent different parts metal intensification situation, as the programming rate of section 3 has reached 44.08 DEG C/h, approach 55 DEG C/h of code requirement, if solar radiation disturbance is larger, just may cause receiver local heating too fast, breaking-up equipment.

Table 3

Model

The intensification number of degrees in 200s (DEG C)

Programming rate

		(℃/h)
			Lumped parameter model	2.05	36.85
Distribution parameter segment model 1	1.80	32.45
			Distribution parameter segment model 2	2.21	39.76
Distribution parameter segment model 3	2.45	44.08
			Distribution parameter segment model 4	2.21	39.78
Distribution parameter segment model 5	1.80	32.45

Claims (4)

1. a distribution parameter modeling method for tower type solar thermo-power station tubulose receiver, is characterized in that, comprises the following steps:

1) set up total quality conservation, the modeling of energy conservation of tower type solar thermo-power station tubulose receiver;

Measure solar radiation on same day DNI value, according to thermo-power station mirror-reflection area, mirror field efficiency, stage efficiency, heliostat reflectivity and receiver efficiency, calculate the solar heat Q that offers working medium in receiver sheet; Measure feedwater flow q _f, steam flow q _s;

Energy Q computing formula is as follows:

Q=DNI × S _m× η _{mirror field efficiency}× η _trunc× η _ref× η _clr(1)

Wherein, DNI represents solar radiant energy value; S _mfor mirror-reflection area; η _{mirror field efficiency}represent the average efficiency of Jing Chang, for mirror field atmospheric transmissivity, cosine efficiency and shade block the average of efficiency achievement; η _refrepresent the efficiency of blocking at that time; η _refrepresent heliostat reflectivity; η _clrthe cleanliness that represent heliostat, these values all obtain from actual mirror field situation;

The tubulose receiver system mass conservation is as follows:

$\frac{d}{\mathrm{dt}}[{\mathrm{\&rho;}}_s{V}_{\mathrm{st}}+{\mathrm{\&rho;}}_w{V}_{\mathrm{wt}}]=q_f-q_s---\left(2\right)$

Tubulose receiver system energy conservation is as follows:

$\frac{d}{\mathrm{dt}}[{\mathrm{\&rho;}}_s{h}_s{V}_{\mathrm{st}}+{\mathrm{\&rho;}}_w{h}_w{V}_{\mathrm{wt}}-{\mathrm{\&rho;V}}_t+m_t{C}_p{T}_m]=Q+q_f{h}_f-q_s{h}_s---\left(3\right)$

Wherein, ρ is density, and h is specific enthalpy, C _pfor metal heat, T is temperature, and V is volume, and p is system pressure; Subscript s represents steam, and w represents water, and m represents metal, and t represents whole system; V _st, V _wtbe respectively total vapour volume and water volume, V _tfor whole system cumulative volume, have:

V _t＝V _st+V _wt (4)

2) set up the tower type solar thermo-power station tubulose receiver drum mass conservation, modeling of energy conservation;

Steam and aqueous mixtures enter drum from dash receiver tedge, and feedwater also enters drum, and water flows out and enters downtake from drum, and steam leaves drum from valve, and subscript d represents drum, V _sd, V _wdrepresent respectively the volume of steam and water under drum liquid level, q _sdunder expression drum liquid level, water flashes to the flow of steam, q _cdrepresent the flow of steam-condensation Cheng Shui on drum liquid level, q _rthe working medium flow that represent to flow out receiver sheet, flows into drum, α _rrepresent working medium flow q _rin quality of steam number percent, under drum liquid level, mass balance equation is as follows:

$\frac{d}{\mathrm{dt}}\left({\mathrm{\&rho;}}_s{V}_{\mathrm{sd}}\right)={\mathrm{\&alpha;}}_r{q}_r-q_{\mathrm{sd}}-q_{\mathrm{cd}}---\left(5\right)$

Wherein:

$q_{\mathrm{cd}}=\frac{h_w-h_f}{h_c}{q}_f+\frac{1}{h_c}({\mathrm{\&rho;}}_s{V}_{\mathrm{sd}}\frac{{\mathrm{dh}}_s}{\mathrm{dt}}+{\mathrm{\&rho;}}_w{V}_{\mathrm{wd}}\frac{{\mathrm{dh}}_w}{\mathrm{dt}}-(V_{\mathrm{sd}}+V_{\mathrm{wt}})\frac{\mathrm{dp}}{\mathrm{dt}}+m_d{C}_p\frac{{\mathrm{dT}}_s}{\mathrm{dt}})---\left(6\right)$

Q _sdbe an empirical model, β is empirical parameter:

$q_{\mathrm{sd}}=\frac{{\mathrm{\&rho;}}_s}{T_d}(V_{\mathrm{sd}}-V_{\mathrm{sd}}^0)+{\mathrm{\&alpha;}}_r{q}_{\mathrm{dc}}+{\mathrm{\&alpha;}}_r\mathrm{\&beta;}(q_{\mathrm{dc}}-q_r)---\left(7\right)$

Wherein h _c=h _s-h _f, the enthalpy difference of expression water vapor and water; be illustrated in and there is no vapour volume in condensation situation water drum; T _dit is the residence time of steam in drum;

V _wdfor the cumulative volume of water in drum, equal the total water volume V of system _wtdeduct the volume V of water in downtake _dcvolume with water in dash receiver wherein subscript dc represents downtake, and subscript r represents dash receiver, represent the average external volume number percent of steam in whole dash receiver:

$V_{\mathrm{wd}}=V_{\mathrm{wt}}-V_{\mathrm{dc}}-(1-{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v)V_r---\left(8\right)$

L is liquid level of steam drum, equals in drum water volume V under liquid level _wdwith vapour volume V under liquid level _sddivided by the long-pending A of drum average cross-section _d, concrete formula is as follows:

$l=\frac{V_{\mathrm{wd}}+V_{\mathrm{sd}}}{A_d}---\left(9\right)$

3) set up tower type solar thermo-power station tubulose receiver receiver sheet distributed energy conservation, mass conservation model;

Dash receiver is made up of m root pipe altogether, every pipe is divided into n section, dash receiver can be divided into m × n little module, consider i (0 < i≤m) root VERTICAL TUBE, to its j, (0≤j≤n) section is carried out module modeling, in this section, ρ (i, j) represents steam-water mixing density, q (i, j) representation quality flow rate, A (i, j) represents the cross-sectional area of pipe, V (i, j) be volume, h (i, j) is specific enthalpy, Q (i, j) be available to the heat of this section of fluid, z (i, j) is this segment length;

Obtain quality, energy conservation equation is as follows, wherein, q _dc, q _rrepresent respectively this section of entrance, outlet rate of flow of fluid:

$\left\{\begin{array}{c}\frac{d}{\mathrm{dt}}({\mathrm{\&rho;}}_s{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v(i,j)V(i,j)+{\mathrm{\&rho;}}_w(1-{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v(i,j))V(i,j))=q_{\mathrm{dc}}(i,j)-q_r(i,j)\\ \frac{d}{\mathrm{dt}}({\mathrm{\&rho;}}_s{h}_s{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v(i,j)V(i,j)+{\mathrm{\&rho;}}_w{h}_w(1-{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v(i,j))V(i,j)-{\mathrm{pV}}_r(i,j)+m_r(i,j)C_p{T}_s)\\ =q_{\mathrm{dc}}(i,j)({\mathrm{\&alpha;}}_r(i,j-1)h_c+h_w)+Q(i,j)-({\mathrm{\&alpha;}}_r(i,j)h_c+h_w)q_r(i,j)\end{array}\right.---\left(10\right)$

α in above formula _r(i, 0), expression be the inlet steam content of first paragraph pipe, because entrance is saturation water, therefore there is α _r(i, 0)=0;

Dash receiver metal pipe-wall temperature is T _m, dash receiver metal quality is m _r, metal heat is C _p, the energy that metal receives is Q _m, heat interchanging area is A _i, convective heat-transfer coefficient is h _i, tube wall is carried out to dynamic modeling:

$m_r{C}_p\frac{{\mathrm{dT}}_m}{\mathrm{dt}}=Q_m(i,j)-A_i{h}_i(T_m(i,j)-T_s(i,j))---\left(11\right)$

Tube wall passes to receiver internal working medium heat and is

Q(i,j)＝A _ih _i(T _m(i,j)-T _s(i,j)) (12)

Can obtain the inlet flow rate q of i root pipe according to the momentum conservation of dash receiver and downtake _dc0, represent the contained vapour volume number percent of fluid in i root pipe, V ₀(i) volume of expression i root pipe, k is dash receiver and downtake closed circuit friction factor:

$\frac{1}{2}{\mathrm{kq}}_{\mathrm{dc}0}^2\left(i\right)={\mathrm{\&rho;}}_w{A}_{\mathrm{dc}}({\mathrm{\&rho;}}_w-{\mathrm{\&rho;}}_s)g{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_{v0}\left(i\right)V_0\left(i\right)---\left(13\right)$

Wherein

$\begin{array}{c}{V}_0\left(i\right)=\underset{j=1}{\overset{n}{\mathrm{\&Sigma;}}}V(i,j)\\ {\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_{v0}\left(i\right)=\frac{\underset{j=1}{\overset{n}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_{v0}(i,j)\&times;V(i,j)}{V_0\left(i\right)}\end{array}+---\left(14\right)$

4) set up water and steam physical property relational model;

5) utilize the method for simultaneous solution to solve described tubulose receiver distributed model.

2. the distribution parameter modeling method of tower type solar thermo-power station tubulose receiver according to claim 1, it is characterized in that described step 3) in tower type solar thermo-power station tubulose receiver receiver sheet distributed energy conservation, mass conservation model inference step as follows:

Row are write quality, energy conservation equation:

$\left\{\begin{array}{c}A(i,j)\frac{\&PartialD;\mathrm{\&rho;}(i,j)}{\&PartialD;t}+\frac{\&PartialD;q(i,j)}{\&PartialD;z(i,j)}=0\\ \frac{\&PartialD;\mathrm{\&rho;}(i,j)h(i,j)}{\&PartialD;t}+\frac{1}{A(i,j)}\frac{\&PartialD;q(i,j)h(i,j)}{\&PartialD;z(i,j)}=\frac{Q(i,j)}{V(i,j)}\end{array}\right.---\left(15\right)$

α _mrepresent the shared mass percent of steam in fluid, h _s, h _wrepresent respectively the specific enthalpy of saturated vapour and saturation water,

Fluid specific enthalpy h (i, j) can be expressed as:

h(i,j)＝α _m(i,j)h _s+(1-α _m(i,j))h _w＝α _m(i,j)h _c+h _w (16)

When stable state, quality, energy conservation are:

$\left\{\begin{array}{c}\frac{\&PartialD;q(i,j)}{\&PartialD;z(i,j)}=0\\ \frac{\&PartialD;q(i,j)h(i,j)}{\&PartialD;z(i,j)}=q(i,j)h_c\frac{{\&PartialD;\mathrm{\&alpha;}}_m(i,j)}{\&PartialD;z(i,j)}=\frac{Q(i,j)A(i,j)}{V(i,j)}\end{array}\right.---\left(17\right)$

Can be obtained by (17):

${\mathrm{\&alpha;}}_m(i,j)=\frac{Q(i,j)A(i,j)}{q(i,j)h_{c}V(i,j)}z(i,j)---\left(18\right)$

In this section, heat Q (i, j) sometime, sectional area A (i, j), flow q (i, j), volume V (i, j) is definite value, visible α _m(i, j) and z (i, j) are linear, do following normalizing: establishing ξ is a linear coefficient, corresponding to tedge length, α _rfor this section outlet quality of steam number percent, along the mass ratio of length be:

α _m(i,j)＝α _r(i,j)ξ0≤ξ≤1 (19)

And volume ratio α _v(i, j) and mass ratio α _mthe relation of (i, j) is as follows:

${\mathrm{\&alpha;}}_v(i,j)=\frac{{\mathrm{\&rho;}}_w{\mathrm{\&alpha;}}_m(i,j)}{{\mathrm{\&rho;}}_s+({\mathrm{\&rho;}}_w-{\mathrm{\&rho;}}_s){\mathrm{\&alpha;}}_m(i,j)}---\left(20\right)$

Thereby can obtain average external volume ratio

${\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v(i,j)={\&Integral;}_0^1{\mathrm{\&alpha;}}_v(i,j)---\left(21\right).$

3. the distribution parameter modeling method of tower type solar thermo-power station tubulose receiver according to claim 1, is characterized in that described step 2) the vapoury percent by volume of whole dash receiver inner fluid for each module equivalence and, result is as follows:

${\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v=\frac{\underset{i=1}{\overset{m}{\mathrm{\&Sigma;}}}\underset{j=1}{\overset{n}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_v(i,j)}{m\&times;n}---\left(22\right).$

4. the distribution parameter modeling method of tower type solar thermo-power station tubulose receiver according to claim 1, it is characterized in that described step 4) set up water and steam physical property relational model be water and steam character international association announce industrial standard IAPWS-IF97.