CN101776893B - Production potential optimizing system and method for air distillation tower - Google Patents

Abstract

The invention discloses a production potential optimizing system for an air distillation tower, which comprises a field intelligent instrument connected with the air distillation tower, a control station, a database and an upper computer, wherein the upper computer comprises an optimization computing module. The system adopts the following process: setting structural parameters and operating parameters of the tower, and specifying an initial value of feeding air flow; assuming components of a liquid phase of each tower plate; for each tower plate, respectively calculating the equilibrium temperature and components of a vapor phase; for each tower plate, calculating enthalpies of the vapor phase and the liquid phase; and calculating the flow of the vapor phase and the liquid phase of each tower plate; judging whether the following formula (3) is established, if so, continuing, otherwise, updating the components of the liquid phase of each tower plate; and judging whether the purities of nitrogen and oxygen of a product meet a constraint condition, if so, adding an iteration step delta to the feeding air flow and returning for continuous iteration, otherwise, finishing the iteration and outputting a result. The invention also provides a production potential optimizing method for the air distillation tower. The system and the method make the air distillation tower meet the production requirement of product purity, have the highest production capacity and improve the energy-saving property.

Description

Air separation column production potential optimization system and method

Technical field

The present invention relates to empty branch field, especially, relate to a kind of air separation column production potential optimization system and method.

Background technology

The application of oxygen, nitrogen and argon gas is very extensive.Oxygen can be used for iron and steel manufacturing, chemical process, metal processing, glass manufacturing, petroleum recovery and refining, papermaking, health care service, space flight national defence etc.Nitrogen is widely used for blanket gas in metallurgical industry, petroleum recovery and refining, Metal Production and processing, electronics industry, chemical industry.Argon gas as protection gas, at electronics, illuminating industry also has very important application simultaneously in aircraft manufacturing, shipbuilding, atomic energy industry and mechanical industry department.Cryogenic air separation process is a difference of utilizing component boiling points such as oxygen in the air, nitrogen, argon, uses the method for rectifying to separate the low temperature liquid air and obtain highly purified oxygen, nitrogen, argon product.It is a current domestic and international air separation sector application method the most widely.In air separation industries, energy cost has accounted for 75% of air products price.Therefore under the situation that energy crisis is constantly deepened, the energy efficiency that improves air separation technology has important society and economic implications.

Process optimization is the key that production run is designed and developed, and has effect very significantly for improving the process economy benefit.It is meant, procedures system performance, characteristics under the given constraint condition, the device parameter and the operating conditions that find the efficiency index that makes system or objective function to reach minimum (maximum).The optimization of air separation column production potential is meant, keeping product purity to satisfy under the prerequisite of production requirement, finds to make and reduce the operating conditions of air separation column output maximum energy consumption of unit product, thereby reach energy saving purposes.

Summary of the invention

The deficiency higher for the energy consumption of unit product that overcomes existing air separation industries process, that energy saving is relatively poor, the invention provides and a kind ofly can keep product purity to satisfy making under the prerequisite of production requirement air separation column productive capacity maximum, and improve the air separation column production potential optimization system and the method for energy saving.

The technical solution adopted for the present invention to solve the technical problems is:

A kind of air separation column production potential optimization system comprises the field intelligent instrument and control station, database and the host computer that are connected with air separation column; Intelligence instrument is connected with control station, database, host computer, and described host computer comprises:

The computation optimization module, in order to computation optimization, adopt following process to finish:

1) structural parameters and the operating parameter of setting tower are specified feeding air flow initial value;

2) suppose each column plate liquid phase composition;

3), calculate its equilibrium temperature by the bubble point method respectively and vapour phase is formed to each column plate;

4), calculate the enthalpy of vapour-liquid phase respectively to each column plate;

5) calculate the vapour-liquid phase flow rate of each column plate by formula (1) (2):

$V_{j+1}{H}_{j+1}^G+U_{j-1}{H}_{j-1}^L+F_j{H}_j^F-(V_j+S_j^G)H_j^G-(U_j+S_j^L)H_j^L-Q_j=0---\left(1\right)$

$V_{j+1}+U_{j-1}+F_j^G+F_j^L-(V_j+S_j^G)-(U_j+S_j^L)=0---\left(2\right)$

Wherein, V represents the vapour phase flow, and U represents the liquid phase flow, and F represents feed rate, H ^FExpression charging enthalpy, S represent that side carries flow, H ^GAnd H ^LBe respectively vapour-liquid phase enthalpy, subscript j-1, j, j+1 represent j-1, j, j+1 piece plate respectively, and subscript L represents liquid phase, and subscript G represents vapour phase, and Q represents the energy that column plate spreads out of;

6) judge whether following formula (3) is set up,, then continue 7 if set up), otherwise the updating all column plates liquid phase is formed, and returns 3) iteration;

$V_{j+1}{y}_{i,j+1}+U_{j-1}{x}_{i,j-1}+F_j{z}_{i,j}-(V_j+S_j^G)y_{i,j}-(U_j+S_j^L)x_{i,j}<0.0001---\left(3\right)$

Wherein, x is that liquid phase is formed, and y is that vapour phase is formed, and z is a feed composition, subscript i=1,2,3 expression components, corresponding successively nitrogen, argon, oxygen;

7) whether the purity of judging product nitrogen gas, oxygen satisfies constraint, if do not satisfy then finishing iteration, the output result, the feeding air flow of back is maximum air inlet amount, if satisfy then the air feed flow is increased an iteration step length Δ, return 2) continue iteration.

As preferred a kind of scheme: described host computer also comprises: bubble point method module, and in order to calculate its equilibrium temperature by the bubble point method and vapour phase is formed, its process is as follows:

3.1) supposition column plate equilibrium temperature;

3.2) calculate the vapor-liquid equilibrium constant, adopt following process to finish:

$\ln {\mathrm{\&Phi;}}_i^L=\ln \frac{\mathrm{RT}}{P(v^L-b^L)}-\frac{b_i}{b^L}(1-Z^L)+{\mathrm{\&xi;}}^L{a}^L(\frac{b_i}{b^L}-\frac{2\underset{m}{\mathrm{\&Sigma;}}{x}_m{a}_{i,m}}{a^L})/b^L\mathrm{RT}---\left(4\right)$

$\ln {\mathrm{\&Phi;}}_i^G=\ln \frac{\mathrm{RT}}{P(v^G-b^G)}-\frac{b_i}{b^G}(1-Z^G)+{\mathrm{\&xi;}}^G{a}^G(\frac{b_i}{b^G}-\frac{2\underset{m}{\mathrm{\&Sigma;}}{x}_m{a}_{i,m}}{a^G})/b^G\mathrm{RT}---\left(5\right)$

$K_i={\mathrm{\&Phi;}}_i^L/{\mathrm{\&Phi;}}_i^G---\left(6\right)$

y _i＝K _ix _i (7)

Wherein, Φ represents fugacity coefficient, and subscript L represents liquid phase, and subscript G represents vapour phase, and R is a gas law constant, and T is a temperature, and P is a column plate pressure, subscript m=1,2,3 expression components, corresponding successively nitrogen, argon, oxygen, molar volume v, physical parameter b ^G, b ^L, b _i, a ^G, a ^L, a _{I, m}, ξ ^G, ξ ^L, vapour phase compressibility factor Z ^G, liquid phase compressibility factor Z ^LCalculate by the rerum natura module;

3.3) check

Whether set up, set up then finishing iteration, return result of calculation, otherwise, upgrade the column plate equilibrium temperature, return 3.2) the continuation iteration.

As preferred another kind of scheme: described host computer also comprises: the enthalpy module, and in order to calculate vapour-liquid phase enthalpy of mixing, its process is as follows:

$H_i^{*}=c_i+d_{i}T+e_i{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">T</figure-callout>}}^2+f_i{\mathrm{<figure-callout\; id="3"\; label="T"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">T</figure-callout>}}^3+h_i{T}^4---\left(8\right)$

$H^{*}=\underset{i}{\mathrm{\&Sigma;}}{y}_i{H}_i^{*}---\left(9\right)$

$H^G=H^{*}-\mathrm{RT}(1-Z^G)-{\mathrm{\&xi;}}^G(a^G-T\frac{{\mathrm{da}}^G}{\mathrm{dT}})/b^G---\left(10\right)$

$H^L=H^{*}-\mathrm{RT}(1-Z^L)-{\mathrm{\&xi;}}^L(a^L-T\frac{{\mathrm{da}}^T}{\mathrm{dT}})/b^L---\left(11\right)$

H wherein _i ^*The enthalpy of representing i pure component ideal gas, H ^*Be potpourri ideal gas enthalpy, c, d, e, f, h are constant.

As preferred another scheme: described host computer also comprises: the rerum natura module, and in order to calculate physical parameter, its process is as follows:

$a_{i,m}={\mathrm{\&Omega;}}_{\mathrm{ai},m}{R}^2{T}_{\mathrm{ci},\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">m</figure-callout>}}^2/P_{\mathrm{ci},m}---\left(12\right)$

b _i＝Ω _bRT _ci/P _cia (13)

$T_{\mathrm{ci},m}=\sqrt{T_{\mathrm{ci}}{T}_{\mathrm{cj}}}(1-k_{i,m})---\left(14\right)$

$V_{\mathrm{ci},m}=0.125{(V_{\mathrm{ci},m}^{1/3}+V_{\mathrm{ci},m}^{1/3})}^3---\left(15\right)$

Z _ci，m＝0.5(Z _ci+Z _cm) (16)

P _ci，m＝RT _ci，mZ _ci，m/V _ci，m (17)

Ω _ai，m＝0.5(Ω _ai+Ω _am) (18)

To vapour phase:

$a^G=\underset{i}{\mathrm{\&Sigma;}}\underset{m}{\mathrm{\&Sigma;}}{y}_i{y}_m{a}_{i,m}---\left(19\right)$

$b^G=\underset{i}{\mathrm{\&Sigma;}}{y}_i{b}_i---\left(20\right)$

Order

A ^G＝a ^GP/R ²T ² (21)

B ^G＝b ^GP/RT (22)

α ^G＝2B ^G-1 (23)

${\mathrm{\&beta;}}^G=A^G-{3B}^G-{5B}^{G^2}---\left(24\right)$

${\mathrm{\&gamma;}}^G=2({\mathrm{<figure-callout\; id="3"\; label="B\; G"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">B</figure-callout>}}^{G^{}}+B^{G^2})-A^G{B}^G---\left(25\right)$

Getting initial value is 1-0.6P _r, separate following equation with Newton method, promptly obtain vapour phase compressibility factor Z ^G

$Z^{{\mathrm{<figure-callout\; id="3"\; label="G"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">G</figure-callout>}}^3}+{\mathrm{\&alpha;}}^{\mathrm{<figure-callout\; id="2"\; label="G\; Z\; G"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">G</figure-callout>}}{Z}^{G^{}}{{}^2}^{}+{\mathrm{\&beta;Z}}^G+{\mathrm{\&gamma;}}^G=0---\left(26\right)$

Then,

v ^G＝RT/PZ ^G (27)

${\mathrm{\&xi;}}^G=0.242536\ln \frac{v^G+3.561553b^G}{v^G-0.561553b^G}---\left(28\right)$

To liquid phase:

$a^L=\underset{i}{\mathrm{\&Sigma;}}\underset{m}{\mathrm{\&Sigma;}}{x}_i{x}_m{a}_{i,m}---\left(29\right)$

$b^L=\underset{i}{\mathrm{\&Sigma;}}{x}_i{b}_i---\left(30\right)$

Order

A ^L＝a ^LP/R ²T ² (31)

B ^L＝b ^LP/RT (32)

α ^L＝2B ^L-1 (33)

${\mathrm{\&beta;}}^L=A^L-{3B}^L-{5B}^{L^2}---\left(34\right)$

${\mathrm{\&gamma;}}^L=2({\mathrm{<figure-callout\; id="3"\; label="B\; L"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">B</figure-callout>}}^{L^{}}+B^{L^2})-A^L{B}^L---\left(35\right)$

Getting initial value is P _r(0.106+0.078P _r), separate following equation with Newton method, promptly obtain liquid phase compressibility factor Z ^L

${\mathrm{<figure-callout\; id="3"\; label="Z\; L"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">Z</figure-callout>}}^{L^{}}+{\mathrm{\&alpha;}}^{\mathrm{<figure-callout\; id="2"\; label="L\; Z\; L"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">L</figure-callout>}}{Z}^{L^{}}{{}^2}^{}+\mathrm{\&beta;}{Z}^L+{\mathrm{\&gamma;}}^L=0---\left(36\right)$

Then,

v ^L＝RT/PZ ^L (37)

${\mathrm{\&xi;}}^L=0.242536\ln \frac{v^L+3.561553b^L}{v^L-0.561553b^L}---\left(38\right)$

Ω _ai＝C _i-D _iτ+E _iτ ²-W _iτ ³?(39)

Ω _b＝0.070721 (40)

τ＝0.01T (41)

Wherein, A, B, α, β, γ, τ are intermediate variables, and C, D, E, W are constants, T _c, P _c, V _c, Z _cBe respectively critical temperature, pressure, volume and compressibility factor, P _rBe reduced pressure, R is a gas law constant, k _{I, m}The mutual coefficient of binary of representing i component and m component is a constant, and subscript c represents the character of critical point, and subscript r represents reduced state, subscript i, and m represents the two-component mixture of i component and m component, Ω _a, Ω _bIt is intermediate variable.

Further, described host computer also comprises: display module as a result is used for that the computation optimization result is passed to control station and shows, and by fieldbus the computation optimization result is delivered to operator station and shows.

The production potential optimization method that a kind of air separation column production potential optimization system realizes, described optimization method may further comprise the steps:

1) structural parameters and the operating parameter of setting tower are specified feeding air flow initial value;

2) suppose each column plate liquid phase composition;

3), calculate its equilibrium temperature by the bubble point method respectively and vapour phase is formed to each column plate;

4), calculate the enthalpy of its vapour-liquid phase to each column plate;

5) simultaneous formula (1) (2) is calculated the vapour-liquid phase flow rate of each column plate:

$V_{j+1}{H}_{j+1}^G+U_{j-1}{H}_{j-1}^L+F_j{H}_j^F-(V_j+S_j^G)H_j^G-(U_j+S_j^L)H_j^L-Q_j=0---\left(1\right)$

$V_{j+1}+U_{j-1}+F_j^G+F_j^L-(V_j+S_j^G)-(U_j+S_j^L)=0---\left(2\right)$

Wherein, V represents the vapour phase flow, and U represents the liquid phase flow, and F represents feed rate, H ^FExpression charging enthalpy, S represent that side carries flow, and subscript j-1, j, j+1 represent j-1, j, j+1 piece plate respectively, and Q represents the energy that column plate spreads out of;

6) judge whether formula (3) is set up,, then continue step 7) if set up, otherwise, upgrade liquid phase and form, return 3) iteration;

$V_{j+1}{y}_{i,j+1}+U_{j-1}{x}_{i,j-1}+F_j{z}_{i,j}-(V_j+S_j^G)y_{i,j}-(U_j+S_j^L)x_{i,j}<0.0001---\left(3\right)$

7) whether the purity of judging product nitrogen gas, oxygen satisfies constraint, if do not satisfy then finishing iteration, the output result, the feeding air flow of back is maximum air inlet amount, if satisfy then the air feed flow is increased an iteration step length Δ, return step 2) continue iteration..

As preferred a kind of scheme: in the described step 3), the bubble point method is calculated its equilibrium temperature and vapour phase, adopts following process to finish:

3.1) supposition column plate equilibrium temperature;

3.2) calculate the vapor-liquid equilibrium constant, adopt following process to finish:

$\ln {\mathrm{\&Phi;}}_i^L=\ln \frac{\mathrm{RT}}{P(v^L-b^L)}-\frac{b_i}{b^L}(1-Z^L)+{\mathrm{\&xi;}}^L{a}^L(\frac{b_i}{b^L}-\frac{2\underset{m}{\mathrm{\&Sigma;}}{x}_m{a}_{i,m}}{a^L})/b^L\mathrm{RT}---\left(4\right)$

$\ln {\mathrm{\&Phi;}}_i^G=\ln \frac{\mathrm{RT}}{P(v^G-b^G)}-\frac{b_i}{b^G}(1-Z^G)+{\mathrm{\&xi;}}^G{a}^G(\frac{b_i}{b^G}-\frac{2\underset{m}{\mathrm{\&Sigma;}}{x}_m{a}_{i,m}}{a^G})/b^G\mathrm{RT}---\left(5\right)$

$K_i={\mathrm{\&Phi;}}_i^L/{\mathrm{\&Phi;}}_i^G---\left(6\right)$

y _i＝K _ix _i (7)

Wherein, Φ represents fugacity coefficient, and subscript L represents liquid phase, and subscript G represents vapour phase, and R is a gas law constant, and P is a column plate pressure, subscript m=1,2,3 expression components, corresponding successively nitrogen, argon, oxygen, molar volume v, physical parameter b ^G, b ^L, b _i, a ^G, a ^L, a _{I, m}, ξ ^G, ξ ^L, vapour phase compressibility factor Z ^G, liquid phase compressibility factor Z ^LCalculate by the physical parameter computing method;

3.3) check Whether set up, set up then finishing iteration, return result of calculation, otherwise, upgrade the column plate equilibrium temperature, return 3.2) the continuation iteration.

As preferred another kind of scheme: in the described step 4), enthalpy computing method process is as follows:

$H_i^{*}=c_i+d_{i}T+e_i{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">T</figure-callout>}}^2+{\mathrm{<figure-callout\; id="3"\; label="f\; i\; T"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">f</figure-callout>}}_i{T}^{}{}^3+h_i{T}^4---\left(8\right)$

$H^{*}=\underset{i}{\mathrm{\&Sigma;}}{y}_i{H}_i^{*}---\left(9\right)$

$H^G=H^{*}-\mathrm{RT}(1-Z^G)-{\mathrm{\&xi;}}^G(a^G-T\frac{{\mathrm{da}}^G}{\mathrm{dT}})/b^G---\left(10\right)$

$H^L=H^{*}-\mathrm{RT}(1-Z^L)-{\mathrm{\&xi;}}^L(a^L-T\frac{{\mathrm{da}}^T}{\mathrm{dT}})/b^L---\left(11\right)$

H wherein _i ^*The enthalpy of representing i pure component ideal gas, H ^*Be potpourri ideal gas enthalpy, c, d, e, f, h are constant.

As preferred another scheme: described physical parameter computing method process is as follows:

$a_{i,m}={\mathrm{\&Omega;}}_{\mathrm{ai},m}{R}^2{T}_{\mathrm{ci},\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">m</figure-callout>}}^2/P_{\mathrm{ci},m}---\left(12\right)$

b _i＝Ω _bRT _ci/P _cia (13)

$T_{\mathrm{ci},m}=\sqrt{T_{\mathrm{ci}}{T}_{\mathrm{cj}}}(1-k_{i,m})---\left(14\right)$

$V_{\mathrm{ci},m}=0.125{(V_{\mathrm{ci},m}^{1/3}+V_{\mathrm{ci},m}^{1/3})}^3---\left(15\right)$

Z _ci，m＝0.5(Z _ci+Z _cm) (16)

P _ci，m＝RT _ci，mZ _ci，m/V _ci，m(17)

Ω _ai，m＝0.5(Ω _ai+Ω _am) (18)

To vapour phase:

$a^G=\underset{i}{\mathrm{\&Sigma;}}\underset{m}{\mathrm{\&Sigma;}}{y}_i{y}_m{a}_{i,m}---\left(19\right)$

$b^G=\underset{i}{\mathrm{\&Sigma;}}{y}_i{b}_i---\left(20\right)$

Order

A ^G＝a ^GP/R ²T ² (21)

B ^G＝b ^GP/RT (22)

α ^G＝2B ^G-1 (23)

${\mathrm{\&beta;}}^G=A^G-{3B}^G-{5B}^{G^2}---\left(24\right)$

${\mathrm{\&gamma;}}^G=2({\mathrm{<figure-callout\; id="3"\; label="B\; G"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">B</figure-callout>}}^{G^{}}+B^{G^2})-A^G{B}^G---\left(25\right)$

Getting initial value is 1-0.6P _r, separate following equation with Newton method, promptly obtain vapour phase compressibility factor Z ^G

${\mathrm{<figure-callout\; id="3"\; label="Z\; G"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">Z</figure-callout>}}^{G^{}}+{\mathrm{\&alpha;}}^{\mathrm{<figure-callout\; id="2"\; label="G\; Z\; G"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">G</figure-callout>}}{Z}^{G^{}}{{}^2}^{}+{\mathrm{\&beta;Z}}^G+{\mathrm{\&gamma;}}^G=0---\left(26\right)$

Then,

v ^G＝RT/PZ ^G (27)

${\mathrm{\&xi;}}^G=0.242536\ln \frac{v^G+3.561553b^G}{v^G-0.561553b^G}---\left(28\right)$

To liquid phase:

$a^L=\underset{i}{\mathrm{\&Sigma;}}\underset{m}{\mathrm{\&Sigma;}}{x}_i{x}_m{a}_{i,m}---\left(29\right)$

$b^L=\underset{i}{\mathrm{\&Sigma;}}{x}_i{b}_i---\left(30\right)$

Order

A ^L＝a ^LP/R ²T ² (31)

B ^L＝b ^LP/RT (32)

α ^L＝2B ^L-1 (33)

${\mathrm{\&beta;}}^L=A^L-{3B}^L-{5B}^{L^2}---\left(34\right)$

${\mathrm{\&gamma;}}^L=2({\mathrm{<figure-callout\; id="3"\; label="B\; L"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">B</figure-callout>}}^{L^{}}+B^{L^2})-A^L{B}^L---\left(35\right)$

Getting initial value is P _r(0.106+0.078P _r), separate following equation with Newton method, promptly obtain liquid phase compressibility factor Z ^L

${\mathrm{<figure-callout\; id="3"\; label="Z\; L"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">Z</figure-callout>}}^{L^{}}+{\mathrm{\&alpha;}}^{\mathrm{<figure-callout\; id="2"\; label="L\; Z\; L"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">L</figure-callout>}}{Z}^{L^{}}{{}^2}^{}+\mathrm{\&beta;}{Z}^L+{\mathrm{\&gamma;}}^L=0---\left(36\right)$

Then,

v ^L＝RT/PZ ^L (37)

${\mathrm{\&xi;}}^L=0.242536\ln \frac{v^L+3.561553b^L}{v^L-0.561553b^L}---\left(38\right)$

Ω _ai＝C _i-D _iτ+E _iτ ²-W _iτ ³(39)

Ω _b＝0.070721 (40)

τ＝0.01T (41)

Wherein, A, B, α, β, γ, τ are intermediate variables, and C, D, E, W are constants, T _c, P _c, V _c, Z _cBe respectively critical temperature, pressure, volume and compressibility factor, P _rBe reduced pressure, R is a gas law constant, k _{I, m}The mutual coefficient of binary of representing i component and m component, k _{I, m}Be constant, subscript c represents the character of critical point, and subscript r represents reduced state, subscript i, and m represents the two-component mixture of i component and m component, Ω _a, Ω _bIt is intermediate variable.

Further, in described step 7), host computer is passed to control station with the computation optimization result and is shown, and by fieldbus the computation optimization result is delivered to operator station and shows.

Beneficial effect of the present invention mainly shows: air separation column is carried out the production potential computation optimization, instruct and produce, excavate the device production potential, improve output under the prerequisite that keeps product purity to meet the demands, reduce energy consumption of unit product, thereby improve productivity effect.

Description of drawings

Fig. 1 is the hardware structure diagram of production potential optimization system proposed by the invention.

Fig. 2 is an air separating tower structure synoptic diagram of the present invention.

Fig. 3 is the functional block diagram of host computer of the present invention.

Embodiment

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

Embodiment 1

With reference to Fig. 1, Fig. 2, Fig. 3, a kind of air separation column energy-saving potential optimizing system, comprise the field intelligent instrument 2, data-interface 3, control station 4, database 5 and the host computer 6 that are connected with air separation column 1, intelligence instrument 2 is connected with fieldbus, described fieldbus is connected with data-interface 3, described data-interface 3 is connected with control station 4, database 5 and host computer 6, and described host computer 6 comprises:

The computation optimization module, in order to computation optimization, adopt following process to finish:

1) structural parameters and the operating parameter of setting tower are specified feeding air flow initial value;

2) suppose each column plate liquid phase composition;

3), calculate its equilibrium temperature by the bubble point method respectively and vapour phase is formed to each column plate;

4), calculate the enthalpy of vapour-liquid phase respectively to each column plate;

5) calculate the vapour-liquid phase flow rate of each column plate by formula (1) (2):

$V_{j+1}{H}_{j+1}^G+U_{j-1}{H}_{j-1}^L+F_j{H}_j^F-(V_j+S_j^G)H_j^G-(U_j+S_j^L)H_j^L-Q_j=0---\left(1\right)$

$V_{j+1}+U_{j-1}+F_j^G+F_j^L-(V_j+S_j^G)-(U_j+S_j^L)=0---\left(2\right)$

Wherein, V represents the vapour phase flow, and U represents the liquid phase flow, and F represents feed rate, H ^FExpression charging enthalpy, S represent that side carries flow, H ^GAnd H ^LBe respectively vapour-liquid phase enthalpy, subscript j-1, j, j+1 represent j-1, j, j+1 piece plate respectively, and subscript L represents liquid phase, and subscript G represents vapour phase, and Q represents the energy that column plate spreads out of;

6) judge whether following formula (3) is set up,, then continue 7 if set up), otherwise the updating all column plates liquid phase is formed, and returns 3) iteration;

$V_{j+1}{y}_{i,j+1}+U_{j-1}{x}_{i,j-1}+F_j{z}_{i,j}-(V_j+S_j^G)y_{i,j}-(U_j+S_j^L)x_{i,j}<0.0001---\left(3\right)$

Wherein, x is that liquid phase is formed, and y is that vapour phase is formed, and z is a feed composition, subscript i=1,2,3 expression components, corresponding successively nitrogen, argon, oxygen;

7) whether the purity of judging product nitrogen gas, oxygen satisfies constraint, if do not satisfy then finishing iteration, the output result, the feeding air flow of back is maximum air inlet amount, if satisfy then the air feed flow is increased an iteration step length Δ, return 2) continue iteration.

Bubble point method module 8, in order to calculate its equilibrium temperature by the bubble point method and vapour phase is formed, its process is as follows:

3.1) supposition column plate equilibrium temperature;

3.2) calculate the vapor-liquid equilibrium constant, adopt following process to finish:

$\ln {\mathrm{\&Phi;}}_i^L=\ln \frac{\mathrm{RT}}{P(v^L-b^L)}-\frac{b_i}{b^L}(1-Z^L)+{\mathrm{\&xi;}}^L{a}^L(\frac{b_i}{b^L}-\frac{2\underset{m}{\mathrm{\&Sigma;}}{x}_m{a}_{i,m}}{a^L})/b^L\mathrm{RT}---\left(4\right)$

$\ln {\mathrm{\&Phi;}}_i^G=\ln \frac{\mathrm{RT}}{P(v^G-b^G)}-\frac{b_i}{b^G}(1-Z^G)+{\mathrm{\&xi;}}^G{a}^G(\frac{b_i}{b^G}-\frac{2\underset{m}{\mathrm{\&Sigma;}}{x}_m{a}_{i,m}}{a^G})/b^G\mathrm{RT}---\left(5\right)$

$K_i={\mathrm{\&Phi;}}_i^L/{\mathrm{\&Phi;}}_i^G---\left(6\right)$

y _i＝K _ix _i (7)

Wherein, Φ represents fugacity coefficient, and subscript L represents liquid phase, and subscript G represents vapour phase, and R is a gas law constant, and T is a temperature, and P is a column plate pressure, subscript m=1,2,3 expression components, corresponding successively nitrogen, argon, oxygen, molar volume v, physical parameter b ^G, b ^L, b _i, a ^G, a ^L, a _{I, m}, ξ ^G, ξ ^L, vapour phase compressibility factor Z ^G, liquid phase compressibility factor Z ^LCalculate by the rerum natura module;

3.3) check

Whether set up, set up then finishing iteration, return result of calculation, otherwise, upgrade the column plate equilibrium temperature, return 3.2) the continuation iteration;

Enthalpy module 9, in order to calculate vapour-liquid phase enthalpy of mixing, its process is as follows:

$H_i^{*}=c_i+d_{i}T+e_i{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">T</figure-callout>}}^2+{\mathrm{<figure-callout\; id="3"\; label="f\; i\; T"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">f</figure-callout>}}_i{T}^{}{}^3+h_i{T}^4---\left(8\right)$

$H^{*}=\underset{i}{\mathrm{\&Sigma;}}{y}_i{H}_i^{*}---\left(9\right)$

$H^G=H^{*}-\mathrm{RT}(1-Z^G)-{\mathrm{\&xi;}}^G(a^G-T\frac{{\mathrm{da}}^G}{\mathrm{dT}})/b^G---\left(10\right)$

$H^L=H^{*}-\mathrm{RT}(1-Z^L)-{\mathrm{\&xi;}}^L(a^L-T\frac{{\mathrm{da}}^T}{\mathrm{dT}})/b^L---\left(11\right)$

H wherein _i ^*The enthalpy of representing i pure component ideal gas, H ^*Be potpourri ideal gas enthalpy, c, d, e, f, h are constant;

Rerum natura module 10, in order to calculate physical parameter, its process is as follows:

$a_{i,m}={\mathrm{\&Omega;}}_{\mathrm{ai},m}{R}^2{T}_{\mathrm{ci},\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">m</figure-callout>}}^2/P_{\mathrm{ci},m}---\left(12\right)$

b _i＝Ω _bRT _ci/P _cia (13)

$T_{\mathrm{ci},m}=\sqrt{T_{\mathrm{ci}}{T}_{\mathrm{cj}}}(1-k_{i,m})---\left(14\right)$

$V_{\mathrm{ci},m}=0.125{(V_{\mathrm{ci},m}^{1/3}+V_{\mathrm{ci},m}^{1/3})}^3---\left(15\right)$

Z _ci，m＝0.5(Z _ci+Z _cm) (16)

P _ci，m＝RT _ci，mZ _ci，m/V _ci，m(17)

Ω _ai，m＝0.5(Ω _ai+Ω _am) (18)

To vapour phase:

$a^G=\underset{i}{\mathrm{\&Sigma;}}\underset{m}{\mathrm{\&Sigma;}}{y}_i{y}_m{a}_{i,m}---\left(19\right)$

$b^G=\underset{i}{\mathrm{\&Sigma;}}{y}_i{b}_i---\left(20\right)$

Order

A ^G＝a ^GP/R ²T ² (21)

B ^G＝b ^GP/RT (22)

α ^G＝2B ^G-1 (23)

${\mathrm{\&beta;}}^G=A^G-{3B}^G-{5B}^{G^2}---\left(24\right)$

${\mathrm{\&gamma;}}^G=2({\mathrm{<figure-callout\; id="3"\; label="B\; G"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">B</figure-callout>}}^{G^{}}+B^{G^2})-A^G{B}^G---\left(25\right)$

Getting initial value is 1-0.6P _r, separate following equation with Newton method, promptly obtain vapour phase compressibility factor Z ^G

${\mathrm{<figure-callout\; id="3"\; label="Z\; G"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">Z</figure-callout>}}^{G^{}}+{\mathrm{\&alpha;}}^{\mathrm{<figure-callout\; id="2"\; label="G\; Z\; G"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">G</figure-callout>}}{Z}^{G^{}}{{}^2}^{}+{\mathrm{\&beta;Z}}^G+{\mathrm{\&gamma;}}^G=0---\left(26\right)$

Then,

v ^G＝RT/PZ ^G (27)

${\mathrm{\&xi;}}^G=0.242536\ln \frac{v^G+3.561553b^G}{v^G-0.561553b^G}---\left(28\right)$

To liquid phase:

$a^L=\underset{i}{\mathrm{\&Sigma;}}\underset{m}{\mathrm{\&Sigma;}}{x}_i{x}_m{a}_{i,m}---\left(29\right)$

$b^L=\underset{i}{\mathrm{\&Sigma;}}{x}_i{b}_i---\left(30\right)$

Order

A ^L＝a ^LP/R ²T ² (31)

B ^L＝b ^LP/RT (32)

α ^L＝2B ^L-1 (33)

${\mathrm{\&beta;}}^L=A^L-{3B}^L-{5B}^{L^2}---\left(34\right)$

${\mathrm{\&gamma;}}^L=2({\mathrm{<figure-callout\; id="3"\; label="B\; L"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">B</figure-callout>}}^{L^{}}+B^{L^2})-A^L{B}^L---\left(35\right)$

Getting initial value is P _r(0.106+0.078P _r), separate following equation with Newton method, promptly obtain liquid phase compressibility factor Z ^L

${\mathrm{<figure-callout\; id="3"\; label="Z\; L"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">Z</figure-callout>}}^{L^{}}+{\mathrm{\&alpha;}}^{\mathrm{<figure-callout\; id="2"\; label="L\; Z\; L"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">L</figure-callout>}}{Z}^{L^{}}{{}^2}^{}+\mathrm{\&beta;}{Z}^L+{\mathrm{\&gamma;}}^L=0---\left(36\right)$

Then,

v ^L＝RT/PZ ^L (37)

${\mathrm{\&xi;}}^L=0.242536\ln \frac{v^L+3.561553b^L}{v^L-0.561553b^L}---\left(38\right)$

Ω _ai＝C _i-D _iτ+E _iτ ²-W _iτ ³(39)

Ω _b＝0.070721 (40)

τ＝0.01T (41)

Wherein, A, B, α, β, γ, τ are intermediate variables, and C, D, E, W are constants, T _c, P _c, V _c, Z _cBe respectively critical temperature, pressure, volume and compressibility factor, P _rBe reduced pressure, R is a gas law constant, k _{I, m}The mutual coefficient of binary of representing i component and m component, k _{I, m}Be constant, subscript c represents the character of critical point, and subscript r represents reduced state, subscript i, and m represents the two-component mixture of i component and m component, Ω _a, Ω _bIt is intermediate variable;

Described host computer also comprises: display module 11 as a result, are used for that the computation optimization result is passed to control station and show, and by fieldbus the computation optimization result is delivered to operator station and shows.

The hardware structure diagram of the air separation column energy-saving potential optimizing system of present embodiment as shown in Figure 1, described optimization system core by comprise computation optimization module 7, bubble point method module 8, enthalpy module 9, rerum natura module 10, the host computer 6 of display module 11 and man-machine interface constitutes as a result, comprise in addition: field intelligent instrument 2, data-interface 3, control station 4, database 5 and fieldbus.Air separation column 1, intelligence instrument 2, data-interface 3, control station 4, database 5, host computer 6 link to each other successively by fieldbus, realize uploading and assigning of information flow.Optimization system is moved on host computer 6, can carry out message exchange with first floor system easily.

The functional block diagram of the optimization system of present embodiment mainly comprises computation optimization module 7, bubble point method module 8, enthalpy module 9, rerum natura module 10, display module 11 etc. as a result as shown in Figure 3.

Described production potential optimization method is implemented according to following steps:

1) structural parameters and the operating parameter of setting tower are specified feeding air flow initial value;

2) suppose each column plate liquid phase composition;

3), calculate its equilibrium temperature by the bubble point method respectively and vapour phase is formed to each column plate;

4), calculate the enthalpy of its vapour-liquid phase to each column plate;

5) simultaneous formula (1) (2) is calculated the vapour-liquid phase flow rate of each column plate:

$V_{j+1}{H}_{j+1}^G+U_{j-1}{H}_{j-1}^L+F_j{H}_j^F-(V_j+S_j^G)H_j^G-(U_j+S_j^L)H_j^L-Q_j=0---\left(1\right)$

$V_{j+1}+U_{j-1}+F_j^G+F_j^L-(V_j+S_j^G)-(U_j+S_j^L)=0---\left(2\right)$

Wherein, V represents the vapour phase flow, and U represents the liquid phase flow, and F represents feed rate, H ^FExpression charging enthalpy, S represent that side carries flow, and subscript j-1, j, j+1 represent j-1, j, j+1 piece plate respectively, and Q represents the energy that column plate spreads out of;

6) judge whether formula (3) is set up,, then continue step 7) if set up, otherwise, upgrade liquid phase and form, return the step 3) iteration;

$V_{j+1}{y}_{i,j+1}+U_{j-1}{x}_{i,j-1}+F_j{z}_{i,j}-(V_j+S_j^G)y_{i,j}-(U_j+S_j^L)x_{i,j}<0.0001---\left(3\right)$

Wherein, x is that liquid phase is formed, and y is that vapour phase is formed, and z is a feed composition, subscript i=1,2,3 expression components, corresponding successively nitrogen, argon, oxygen;

7) whether the purity of judging product nitrogen gas, oxygen satisfies constraint, if do not satisfy then finishing iteration, the output result, the feeding air flow of back is maximum air inlet amount, if satisfy then the air feed flow is increased an iteration step length Δ, return step 2) continue iteration:

Embodiment 2

With reference to Fig. 1, Fig. 2, Fig. 3, a kind of air separation column production potential optimization method, described production potential optimization method may further comprise the steps:

1) structural parameters and the operating parameter of setting tower are specified feeding air flow initial value;

2) suppose each column plate liquid phase composition;

3), calculate its equilibrium temperature by the bubble point method respectively and vapour phase is formed to each column plate;

4), calculate the enthalpy of its vapour-liquid phase to each column plate;

5) simultaneous formula (1) (2) is calculated the vapour-liquid phase flow rate of each column plate:

$V_{j+1}{H}_{j+1}^G+U_{j-1}{H}_{j-1}^L+F_j{H}_j^F-(V_j+S_j^G)H_j^G-(U_j+S_j^L)H_j^L-Q_j=0---\left(1\right)$

$V_{j+1}+U_{j-1}+F_j^G+F_j^L-(V_j+S_j^G)-(U_j+S_j^L)=0---\left(2\right)$

Wherein, V represents the vapour phase flow, and U represents the liquid phase flow, and F represents feed rate, H ^FExpression charging enthalpy, S represent that side carries flow, and subscript j-1, j, j+1 represent j-1, j, j+1 piece plate respectively, and Q represents the energy that column plate spreads out of;

6) judge whether formula (3) is set up,, then continue 7 if set up), otherwise, upgrade liquid phase and form, return 3) iteration;

$V_{j+1}{y}_{i,j+1}+U_{j-1}{x}_{i,j-1}+F_j{z}_{i,j}-(V_j+S_j^G)y_{i,j}-(U_j+S_j^L)x_{i,j}<0.0001---\left(3\right)$

Wherein, x is that liquid phase is formed, and y is that vapour phase is formed, and z is a feed composition, subscript i=1,2,3 expression components, corresponding successively nitrogen, argon, oxygen;

7) whether the purity of judging product nitrogen gas, oxygen satisfies constraint, if do not satisfy then finishing iteration, the output result, the feeding air flow of back is maximum air inlet amount, if satisfy then the air feed flow is increased an iteration step length Δ, return step 2) continue iteration.

In the described step 3), the bubble point method is calculated its equilibrium temperature and vapour phase, adopts following process to finish:

3.1) supposition column plate equilibrium temperature;

3.2) calculate the vapor-liquid equilibrium constant, adopt following process to finish:

$\ln {\mathrm{\&Phi;}}_i^L=\ln \frac{\mathrm{RT}}{P(v^L-b^L)}-\frac{b_i}{b^L}(1-Z^L)+{\mathrm{\&xi;}}^L{a}^L(\frac{b_i}{b^L}-\frac{2\underset{m}{\mathrm{\&Sigma;}}{x}_m{a}_{i,m}}{a^L})/b^L\mathrm{RT}---\left(4\right)$

$\ln {\mathrm{\&Phi;}}_i^G=\ln \frac{\mathrm{RT}}{P(v^G-b^G)}-\frac{b_i}{b^G}(1-Z^G)+{\mathrm{\&xi;}}^G{a}^G(\frac{b_i}{b^G}-\frac{2\underset{m}{\mathrm{\&Sigma;}}{x}_m{a}_{i,m}}{a^G})/b^G\mathrm{RT}---\left(5\right)$

$K_i={\mathrm{\&Phi;}}_i^L/{\mathrm{\&Phi;}}_i^G---\left(6\right)$

y _i＝K _ix _i (7)

Wherein, Φ represents fugacity coefficient, and subscript L represents liquid phase, and subscript G represents vapour phase, and R is a gas law constant, and P is a column plate pressure, subscript m=1,2,3 expression components, corresponding successively nitrogen, argon, oxygen, molar volume v, physical parameter b ^G, b ^L, b _i, a ^G, a ^L, a _{I, m}, ξ ^G, ξ ^L, vapour phase compressibility factor Z ^G, liquid phase compressibility factor Z ^LCalculate by the physical parameter computing method;

3.3) check

Whether set up, set up then finishing iteration, return result of calculation, otherwise, upgrade the column plate equilibrium temperature, return 3.2) the continuation iteration.

In the described step 4), enthalpy computing method process is as follows:

$H_i^{*}=c_i+d_{i}T+e_i{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">T</figure-callout>}}^2+{\mathrm{<figure-callout\; id="3"\; label="f\; i\; T"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">f</figure-callout>}}_i{T}^{}{}^3+h_i{T}^4---\left(8\right)$

$H^{*}=\underset{i}{\mathrm{\&Sigma;}}{y}_i{H}_i^{*}---\left(9\right)$

$H^G=H^{*}-\mathrm{RT}(1-Z^G)-{\mathrm{\&xi;}}^G(a^G-T\frac{{\mathrm{da}}^G}{\mathrm{dT}})/b^G---\left(10\right)$

$H^L=H^{*}-\mathrm{RT}(1-Z^L)-{\mathrm{\&xi;}}^L(a^L-T\frac{{\mathrm{da}}^T}{\mathrm{dT}})/b^L---\left(11\right)$

H wherein _i ^*The enthalpy of representing i pure component ideal gas, H ^*Be potpourri ideal gas enthalpy, c, d, e, f, h are constant.

Described physical parameter computing method process is as follows:

$a_{i,m}={\mathrm{\&Omega;}}_{\mathrm{ai},m}{R}^2{T}_{\mathrm{ci},\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">m</figure-callout>}}^2/P_{\mathrm{ci},m}---\left(12\right)$

b _i＝Ω _bRT _ci/P _cia (13)

$T_{\mathrm{ci},m}=\sqrt{T_{\mathrm{ci}}{T}_{\mathrm{cj}}}(1-k_{i,m})---\left(14\right)$

$V_{\mathrm{ci},m}=0.125{(V_{\mathrm{ci},m}^{1/3}+V_{\mathrm{ci},m}^{1/3})}^3---\left(15\right)$

Z _ci，m＝0.5(Z _ci+Z _cm) (16)

P _ci，m＝RT _ci，mZ _ci，m/V _ci，m(17)

Ω _ai，m＝0.5(Ω _ai+Ω _am) (18)

To vapour phase:

$a^G=\underset{i}{\mathrm{\&Sigma;}}\underset{m}{\mathrm{\&Sigma;}}{y}_i{y}_m{a}_{i,m}---\left(19\right)$

$b^G=\underset{i}{\mathrm{\&Sigma;}}{y}_i{b}_i---\left(20\right)$

Order

A ^G＝a ^GP/R ²T ² (21)

B ^G＝b ^GP/RT (22)

α ^G＝2B ^G-1 (23)

${\mathrm{\&beta;}}^G=A^G-{3B}^G-{5B}^{G^2}---\left(24\right)$

${\mathrm{\&gamma;}}^G=2({\mathrm{<figure-callout\; id="3"\; label="B\; G"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">B</figure-callout>}}^{G^{}}+B^{G^2})-A^G{B}^G---\left(25\right)$

Getting initial value is 1-0.6P _r, separate following equation with Newton method, promptly obtain vapour phase compressibility factor Z ^G

${\mathrm{<figure-callout\; id="3"\; label="Z\; G"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">Z</figure-callout>}}^{G^{}}+{\mathrm{\&alpha;}}^{\mathrm{<figure-callout\; id="2"\; label="G\; Z\; G"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">G</figure-callout>}}{Z}^{G^{}}{{}^2}^{}+{\mathrm{\&beta;Z}}^G+{\mathrm{\&gamma;}}^G=0---\left(26\right)$

Then,

v ^G＝RT/PZ ^G (27)

${\mathrm{\&xi;}}^G=0.242536\ln \frac{v^G+3.561553b^G}{v^G-0.561553b^G}---\left(28\right)$

To liquid phase:

$a^L=\underset{i}{\mathrm{\&Sigma;}}\underset{m}{\mathrm{\&Sigma;}}{x}_i{x}_m{a}_{i,m}---\left(29\right)$

$b^L=\underset{i}{\mathrm{\&Sigma;}}{x}_i{b}_i---\left(30\right)$

Order

A ^L＝a ^LP/R ²T ² (31)

B ^L＝b ^LP/RT (32)

α ^L＝2B ^L-1 (33)

${\mathrm{\&beta;}}^L=A^L-{3B}^L-{5B}^{L^2}---\left(34\right)$

${\mathrm{\&gamma;}}^L=2({\mathrm{<figure-callout\; id="3"\; label="B\; L"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">B</figure-callout>}}^{L^{}}+B^{L^2})-A^L{B}^L---\left(35\right)$

Getting initial value is P _r(0.106+0.078P _r), separate following equation with Newton method, promptly obtain liquid phase compressibility factor Z ^L

${\mathrm{<figure-callout\; id="3"\; label="Z\; L"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">Z</figure-callout>}}^{L^{}}+{\mathrm{\&alpha;}}^{\mathrm{<figure-callout\; id="2"\; label="L\; Z\; L"\; filenames="H2009101571752E00011.png"\; state="\{\{state\}\}">L</figure-callout>}}{Z}^{L^{}}{{}^2}^{}+\mathrm{\&beta;}{Z}^L+{\mathrm{\&gamma;}}^L=0---\left(36\right)$

Then,

v ^L＝RT/PZ ^L (37)

${\mathrm{\&xi;}}^L=0.242536\ln \frac{v^L+3.561553b^L}{v^L-0.561553b^L}---\left(38\right)$

Ω _ai＝C _i-D _iτ+E _iτ ²-W _iτ ³(39)

Ω _b＝0.070721 (40)

τ＝0.01T (41)

Wherein, A, B, α, β, γ, τ are intermediate variables, and C, D, E, W are constants, T _c, P _c, V _c, Z _cBe respectively critical temperature, pressure, volume and compressibility factor, P _rBe reduced pressure, R is a gas law constant, k _{I, m}The mutual coefficient of binary of representing i component and m component, k _{I, m}Be constant, subscript c represents the character of critical point, and subscript r represents reduced state, subscript i, and m represents the two-component mixture of i component and m component, Ω _a, Ω _bIt is intermediate variable.

In described step 7), host computer is passed to control station with the computation optimization result and is shown, and by fieldbus the computation optimization result is delivered to operator station and shows.

Air separation column production potential optimization system and method proposed by the invention, be described by above-mentioned concrete implementation step, person skilled obviously can be in not breaking away from content of the present invention, spirit and scope to device as herein described with method of operating is changed or suitably change and combination, realize the technology of the present invention.Special needs to be pointed out is, the replacement that all are similar and change apparent to one skilled in the artly, they all can be regarded as being included in spirit of the present invention, scope and the content.

Claims (4)

1. an air separation column production potential optimization system comprises the field intelligent instrument and control station, database and the host computer that are connected with air separation column, and intelligence instrument is connected with control station, database and host computer, it is characterized in that: described host computer comprises:

The computation optimization module, in order to computation optimization, adopt following process to finish:

1) structural parameters and the operating parameter of setting tower are specified feeding air flow initial value;

2) suppose each column plate liquid phase composition;

3), calculate its equilibrium temperature by the bubble point method respectively and vapour phase is formed to each column plate;

4), calculate the enthalpy of vapour-liquid phase respectively to each column plate;

5) calculate the vapour-liquid phase flow rate of each column plate by formula (1) (2):

Wherein, V represents the vapour phase flow, and U represents the liquid phase flow, and F represents feed rate, H ^FExpression charging enthalpy, S represent that side carries flow, H ^GAnd H ^LBe respectively vapour-liquid phase enthalpy, subscript j-1, j, j+1 represent j-1, j, j+1 piece plate respectively, and subscript L represents liquid phase, and subscript G represents vapour phase, and Q represents the energy that column plate spreads out of;

6) judge whether following formula (3) is set up,, then continue 7 if set up), otherwise the updating all column plates liquid phase is formed, and returns 3) iteration;

Wherein, x is that liquid phase is formed, and y is that vapour phase is formed, and z is a feed composition, subscript i=1,2,3 expression components, corresponding successively nitrogen, argon, oxygen;

7) whether the purity of judging product nitrogen gas, oxygen satisfies constraint, if do not satisfy then finishing iteration, the output result, the feeding air flow of back is maximum air inlet amount, if satisfy then the air feed flow is increased an iteration step length Δ, return 2) continue iteration;

Described host computer also comprises: bubble point method module, and in order to calculate its equilibrium temperature by the bubble point method and vapour phase is formed, its process is as follows:

3.1) supposition column plate equilibrium temperature;

3.2) calculate the vapor-liquid equilibrium constant, adopt following process to finish:

y _i＝K _ix _i (7)

Wherein, Φ represents fugacity coefficient, and subscript L represents liquid phase, and subscript G represents vapour phase, and R is a gas law constant, and T is a temperature, and P is a column plate pressure, subscript m=1,2,3 expression components, corresponding successively nitrogen, argon, oxygen, molar volume v, physical parameter b ^G, b ^L, b _i, a ^G, a ^L, a _{I, m}, ξ ^G, ξ ^L, vapour phase compressibility factor Z ^G, liquid phase compressibility factor Z ^LCalculate by the rerum natura module;

3.3) check

Whether set up, set up then finishing iteration, return result of calculation, otherwise, upgrade the column plate equilibrium temperature, return 3.2) the continuation iteration;

Described host computer also comprises: the enthalpy module, and in order to calculate vapour-liquid phase enthalpy of mixing, its process is as follows:

Wherein

The enthalpy of representing i pure component ideal gas, H ^*Be potpourri ideal gas enthalpy, c, d, e, f, h are constant;

Described host computer also comprises: the rerum natura module, and in order to calculate physical parameter, its process is as follows:

b _i＝Ω _bRT _ci/P _cia (13)

Z _ci，m＝0.5(Z _ci+Z _cm) (16)

P _ci，m＝RT _ci，mZ _ci，m/V _ci，m (17)

Ω _ai，m＝0.5(Ω _ai+Ω _am) (18)

To vapour phase:

Order

A ^G＝a ^GP/R ²T ² (21)

B ^G＝b ^GP/RT (22)

α ^G＝2B ^G-1 (23)

Getting initial value is 1-0.6P _r, separate following equation with Newton method, promptly obtain vapour phase compressibility factor Z ^G

Then,

v ^G＝RT/PZ ^G (27)

To liquid phase:

Order

A ^L＝a ^LP/R ²T ² (31)

B ^L＝b ^LP/RT (32)

α ^L＝2B ^L-1 (33)

Getting initial value is P _r(0.106+0.078P _r), separate following equation with Newton method, promptly obtain liquid phase compressibility factor Z ^L

Then,

v ^L＝RT/PZ ^L (37)

Ω _ai＝C _i-D _iτ+E _iτ ²-W _iτ ³ (39)

Ω _b＝0.070721 (40)

τ＝0.01T (41)

Wherein, A, B, α, β, γ, τ are intermediate variables, and C, D, E, W are constants, T _c, P _c,

V _c, Z _cBe respectively critical temperature, pressure, volume and compressibility factor, P _rBe reduced pressure, R is a gas law constant, k _{I, m}The mutual coefficient of binary of representing i component and m component, k _{I, m}Be constant, subscript c represents the character of critical point, and subscript r represents reduced state, subscript i, and m represents the two-component mixture of i component and m component, Ω _a, Ω _bIt is intermediate variable.

2. air separation column production potential optimization system as claimed in claim 1, it is characterized in that: described host computer also comprises:

Display module is used for that the computation optimization result is passed to control station and shows as a result, and by fieldbus the computation optimization result is delivered to operator station and shows.

3. production potential optimization method of realizing with air separation column production potential optimization system as claimed in claim 1, it is characterized in that: described optimization method may further comprise the steps:

1) structural parameters and the operating parameter of setting tower are specified feeding air flow initial value;

2) suppose each column plate liquid phase composition;

3), calculate its equilibrium temperature by the bubble point method respectively and vapour phase is formed to each column plate;

4), calculate the enthalpy of its vapour-liquid phase to each column plate;

5) simultaneous formula (1) (2) is calculated the vapour-liquid phase flow rate of each column plate:

Wherein, V represents the vapour phase flow, and U represents the liquid phase flow, and F represents feed rate, H ^FExpression charging enthalpy, S represent that side carries flow, and subscript j-1, j, j+1 represent j-1, j, j+1 piece plate respectively, and Q represents the energy that column plate spreads out of;

6) judge whether formula (3) is set up,, then continue step 7) if set up, otherwise, upgrade liquid phase and form, return 3) iteration;

Wherein, x is that liquid phase is formed, and y is that vapour phase is formed, and z is a feed composition, subscript i=1,2,3 expression components, corresponding successively nitrogen, argon, oxygen;

7) whether the purity of judging product nitrogen gas, oxygen satisfies constraint, if do not satisfy then finishing iteration, the output result, the feeding air flow of back is maximum air inlet amount, if satisfy then the air feed flow is increased an iteration step length Δ, return step 2) continue iteration;

In the described step 3), the bubble point method is calculated its equilibrium temperature and vapour phase, adopts following process to finish:

3.1) supposition column plate equilibrium temperature;

3.2) calculate the vapor-liquid equilibrium constant, adopt following process to finish:

y _i＝K _ix _i (7)

Wherein, Φ represents fugacity coefficient, and subscript L represents liquid phase, and subscript G represents vapour phase, and R is a gas law constant, and T is a temperature, and P is a column plate pressure, subscript m=1,2,3 expression components, corresponding successively nitrogen, argon, oxygen, molar volume v, physical parameter b ^Gb ^L, b _i, a ^G, a ^L, a _{I, m}, ξ ^G, ξ ^L, vapour phase compressibility factor Z ^G, liquid phase compressibility factor Z ^LCalculate by the physical parameter computing method;

3.3) check

Whether set up, set up then finishing iteration, return result of calculation, otherwise, upgrade the column plate equilibrium temperature, return 3.2) the continuation iteration;

In the described step 4), enthalpy computing method process is as follows:

Wherein

The enthalpy of representing i pure component ideal gas, H ^*Be potpourri ideal gas enthalpy, c, d, e, f, h are constant;

Described physical parameter computing method process is as follows:

b _i＝Ω _bRT _ci/P _cia (13)

Z _ci，m＝0.5(Z _ci+Z _cm) (16)

P _ci，m＝RT _ci，mZ _ci，m/V _ci，m (17)

Ω _ai，m＝0.5(Ω _ai+Ω _am) (18)

To vapour phase:

Order

A ^G＝a ^GP/R ²T ² (21)

B ^G＝b ^GP/RT (22)

α ^G＝2B ^G-1 (23)

Getting initial value is 1-0.6P _r, separate following equation with Newton method, promptly obtain vapour phase compressibility factor Z ^G

Then,

v ^G＝RT/PZ ^G (27)

To liquid phase:

Order

A ^L＝a ^LP/R ²T ² (31)

B ^L＝b ^LP/RT (32)

α ^L＝2B ^L-1 (33)

Getting initial value is P _r(0.106+0.078P _r), separate following equation with Newton method, promptly obtain liquid phase compressibility factor Z ^L

Then,

v ^L＝RT/PZ ^L (37)

Ω _ai＝C _i-D _iτ+E _iτ ²-W _iτ ³ (39)

Ω _b＝0.070721 (40)

τ＝0.01T (41)

Wherein, A, B, α, β, γ, τ are intermediate variables, and C, D, E, W are constants, T _c, P _c, V _c, Z _cBe respectively critical temperature, pressure, volume and compressibility factor, P _rBe reduced pressure, R is a gas law constant, k _{I, m}The mutual coefficient of binary of representing i component and m component, k _{I, m}Be constant, subscript c represents the character of critical point, and subscript r represents reduced state, subscript i, and m represents the two-component mixture of i component and m component, Ω _a, Ω _bIt is intermediate variable.

4. production potential optimization method as claimed in claim 3 is characterized in that: in described step 7), host computer is passed to control station with the computation optimization result and is shown, and by fieldbus the computation optimization result is delivered to operator station and shows.

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