CN101718504A - Method and device for controlling flexible operation of novel heat exchanger network - Google Patents

Abstract

The invention provides a method for controlling the flexible operation of a novel heat exchanger network. The method comprises the following steps: identifying the sensitive fluid in the heat exchanger network, and arranging a by-pass regulating device on the sensitive fluid; acquiring the temperature and flow parameters of the sensitive fluid at an inlet; solving the optimal by-pass opening degree according to the changes in the temperature and flow parameters and the preset structure information of the heat exchanger network; and adjusting the opening degree of the by-pass regulating device according to the obtained optimal by-pass opening degree. The invention improves the self-regulating capacity of the entire heat exchanger network, reduces the consumption of heat/cold utility works, achieves the energy conservation and improves the working efficiency.

Description

The control method of flexible operation of novel heat exchanger network and device thereof

Technical field

The present invention relates to a kind of control method and device thereof of heat-exchange network, be specifically related to a kind of control method and device thereof of flexible operation of novel heat exchanger network.

Background technology

Heat-exchange network is widely used in fields such as petrochemical industry, energy source and power, and the high efficiency of its operation, reasonability are directly connected to the overall performance of industrial system.In real process, heat-exchange network usually is subjected to the influence of various disturbances, makes actual operating mode off-design operating mode, causes the unprecedented soaring of the migration significantly of runnability and operating cost.When operating mode was abominable, the operation of heat-exchange network can't be satisfied actual needs.Therefore, adopt suitable control measure, make the operation of heat-exchange network satisfy technological requirement all the time and keep lower operating cost, significant.

Heat-exchange network mainly by regulating the adjusting that public work realizes the logistics outlet parameter, guaranteed the stable of target fluid outlet parameter in the past.This control method fails to set about disturbance suppression from heat-exchange network inside, cause frequent in disturbance or situation that disturbance is big under, the rapid increase of public work expense.

Summary of the invention

The objective of the invention is to, a kind of control method and device thereof of flexible operation of novel heat exchanger network are provided, by the control method that responsive fluid bypass is set and adopts bypass to regulate, to improve self regulating power of heat-exchange network integral body, reduce the consumption of hot and cold public work, energy savings, the operational efficiency that improves.

For achieving the above object, the present invention adopts following technical scheme:

A kind of control method of flexible operation of novel heat exchanger network may further comprise the steps:

1) the responsive fluid in the identification heat-exchange network, and on described responsive fluid, bypass regulating device is set;

2) obtain the temperature and the flow parameter of the responsive fluid in porch;

3), find the solution best bypass aperture according to the variation of this temperature and flow parameter with preestablish the structural information of heat-exchange network;

4) regulate the aperture of bypass regulating device according to the best bypass aperture of finding the solution.

Further, in the described step 1), the identification of described responsive fluid may further comprise the steps successively:

A) obtain structural parameters, fluid parameter and the heat exchanger parameter of heat-exchange network under the design conditions;

B), utilize heat-exchange network steady-state simulation technology to realize the simulation of heat-exchange network with the parameter informationization of heat-exchange network;

C) suction parameter of fluid in the change heat-exchange network utilizes simulation to obtain the fluid issuing parameter, and given different suction parameter obtains corresponding outlet parameter response curve;

D) outlet parameter response curve is analyzed in the interval that allows according to technology, obtains the flexible characteristic of heat-exchange network;

E) if the flex region of certain fluid between less than a certain value, this fluid is responsive fluid.

Further, in described step 3),, utilize Monte Carlo random sampling technology to obtain the initial bypass aperture of heat-exchange network, utilize steepest descent method to obtain best bypass aperture then according to heat-exchange network structural parameters and the fluid parameter that measures in real time.

The present invention also provides a kind of flexible operation of novel heat exchanger network control device, comprising:

The heat-exchange network of forming by one or more heat exchangers, each heat exchanger comprise the first fluid pipeline and second fluid circuit, the porch of the porch of described first fluid pipeline and second fluid circuit is provided with flow sensor and temperature sensor respectively, the porch of the responsive fluid circuit in the described heat-exchange network is provided with bypass, the exit of responsive fluid circuit is provided with an electric T-shaped valve, described bypass is connected with the electric T-shaped valve of corresponding responsive fluid circuit respectively, the control end of described electric T-shaped valve and flow sensor, temperature sensor is connected with a control computer, described control computer is according to the flow and the temperature information that obtain, in conjunction with the structural information that preestablishes heat-exchange network, carry out best bypass aperture and calculate the aperture of regulating described electric T-shaped valve according to result of calculation.

Further, also be connected with analog multichannel switch and A/D converter in turn between described hygrosensor and flow probe and the described control computer 5.

Further, described control computer is connected with described analog multichannel switch.

Further, between the control end of described electric T-shaped valve and described control computer, also be connected with D/A converter.

The present invention compares with heat-exchange network control system in the past, has following beneficial effect:

A, compact conformation of the present invention, cost is lower, application is convenient, and heat-exchange network control system in the past often adopts complicated control system, complex structure, cost of investment height;

B, on the basis of heat-exchange network numerical simulation, obtained suitable bypass regulated quantity by optimizer, the realization of control only need be regulated the aperture of electric T-shaped valve, does not increase extra controlling cost, and can reduce the operating cost of network;

C, on control rate, the best bypass that the operation optimizer of heat-exchange network obtains is regulated parameter and is only needed several seconds, therefore from the angle of Industry Control, can satisfy the rate request of controlling fully; And the heat-exchange network numerical simulation can obtain higher solving precision, and therefore the parameters precision height is regulated in the bypass that obtains, thereby has guaranteed the precision of control.The present invention can be widely used in occasions such as chemical industry, oil, energy source and power.

Description of drawings

Fig. 1 is the structural representation of flexible operation of novel heat exchanger network control device embodiment of the present invention;

Fig. 2 is that the control schematic diagram is regulated in the bypass of single heat exchanger in the flexible operation of novel heat exchanger network control device of the present invention.

Label declaration:

10,20,30 heat exchangers, 7,17,27,37 temperature sensors

11,12,21,22,31,32 electric T-shaped valves, 50 control computers

3,13,23,33 fluid intake places, 51 analog multichannel switches

4,14,24,34 fluid outlet 52A/D converters

5,15,25,35 public work 53D/A converters

6,16,26,36 flow sensors

The specific embodiment

Embodiment one

A kind of control method of flexible operation of novel heat exchanger network,

1) the responsive fluid in the identification heat-exchange network, and on described responsive fluid, bypass regulating device is set;

2) obtain the temperature and the flow parameter of the responsive fluid in porch;

3), find the solution best bypass aperture according to the variation of this temperature and flow parameter with preestablish the structural information of heat-exchange network;

4) regulate the aperture of bypass regulating device according to the best bypass aperture of finding the solution.

At present, the steady-state simulation technology of heat-exchange network is comparatively ripe, and the present invention directly utilizes the steady-state simulation technology of existing heat-exchange network to realize the simulation of heat-exchange network.The computation model of single heat exchanger is as follows in the wherein typical heat-exchange network:

t _ho-t _ci-δt _hi+δt _co＝0(1)

Rt _ho-t _ci-Rt _hi+t _co＝0(2)

Wherein:

$R=\frac{(1-X_h)W_h{C}_{\mathrm{ph}}}{(1-X_c)W_c{C}_{\mathrm{pc}}}---\left(3\right)$

S＝(1-X _h)W _hC _ph(4)

$\mathrm{\δ}=\exp \left[(R-1)\frac{\mathrm{KA}}{S}\right]---\left(5\right)$

In the following formula: the t representation temperature, W represents flow, and C represents specific heat capacity, and K represents the heat exchanger coefficient of heat transfer, and it (is to close bypass at 0 o'clock that X represents the bypass aperture; Be to close main road, all by-pass flows at 1 o'clock), A represents the heat exchanger heat exchange area, subscript: on behalf of hot fluid, c, h represent cold fluid, p to represent level pressure, i to represent fluid inlet, o to represent fluid issuing.

By following formula as can be known: know any two temperature of heat exchanger inlet and outlet, can try to achieve two other temperature.For example:

$\left[\begin{array}{c}{t}_{\mathrm{ho}}\\ t_{\mathrm{co}}\end{array}\right]=\left[\begin{array}{cc}\frac{\mathrm{R\δ}-\mathrm{\δ}}{\mathrm{R\δ}-1}& \frac{\mathrm{\δ}-1}{\mathrm{R\δ}-1}\\ \frac{\mathrm{R\δ}-R}{\mathrm{R\δ}-1}& \frac{R-1}{\mathrm{R\δ}-1}\end{array}\right]\left[\begin{array}{c}{t}_{\mathrm{hi}}\\ t_{\mathrm{ci}}\end{array}\right]---\left(6\right)$

If the rerum natura C of fluid _pWith the pass of temperature t be function f (t):

After the fluid heat exchange, the mixed fluid temperature (F.T.) t ' of that part of fluid that comes out with bypass _HoAnd t ' _CoSolving equation is:

$t_{\mathrm{ho}}=\frac{\mathrm{R\δ}-\mathrm{\δ}}{\mathrm{R\δ}-1}\·t_{\mathrm{hi}}+\frac{\mathrm{\δ}-1}{\mathrm{R\δ}-1}\·t_{\mathrm{ci}}=\mathrm{\φ}(R,\mathrm{\δ},t_{\mathrm{hi}},t_{\mathrm{ci}})---\left(7\right)$

Iterative equation (7) and (8) can obtain t ' _HoAnd t ' _CoWherein: φ is a cold fluid outlet temperature solved function, and Φ is a hot fluid outlet temperature solved function, and R is the ratio of hot fluid main road heat-capacity flowrate and cold fluid main road heat-capacity flowrate, and S is the heat-capacity flowrate of hot fluid main road.

Heat-exchange network at reality, utilize the mathematics solving model of above-mentioned heat exchanger, realize finding the solution of heat-exchange network by flowsheeting, can predict the outlet parameter that fluid in the heat-exchange network of back takes place in disturbance, for the flexible characteristic identification and the control of heat-exchange network lays the foundation.

The present invention utilizes existing heat-exchange network steady-state simulation technology to obtain the performance curve of fluid outlet parameter under the different suction parameter effects.Wherein, in described step 1), the identification of described responsive fluid may further comprise the steps successively:

A, can utilize design drawing etc. to obtain structural parameters, fluid parameter and the heat exchanger parameter of heat-exchange network under the design conditions;

B, with the parameter informationization of heat-exchange network, utilize existing heat-exchange network steady-state simulation technology to realize the simulation of heat-exchange network;

The suction parameter of fluid utilizes simulation to obtain the fluid issuing parameter in C, the change heat-exchange network, and given different suction parameter obtains corresponding outlet parameter response curve;

D, according to the interval that technology allows, analyze outlet parameter response curve, obtain the flexible characteristic of heat-exchange network;

E, if the flex region of certain fluid between less than a certain value, this fluid is responsive fluid.

Wherein, in described step 3),, utilize Monte Carlo random sampling technology to obtain the initial bypass aperture of heat-exchange network, utilize steepest descent method to obtain best bypass aperture then according to heat-exchange network structural parameters and the fluid parameter that measures in real time.

In order to obtain the bypass aperture of heat-exchange network the best, the annual operating cost of getting heat-exchange network is an object function, i.e. the expense F of public work ₁Object function is:

minf＝minF(F ₁) (9)

Wherein:

$F_1=(\underset{i=1}{\overset{N_c}{\mathrm{\Σ}}}{C}_{\mathrm{CU}}{q}_{{\mathrm{CU}}_i}+\underset{j=1}{\overset{N_h}{\mathrm{\Σ}}}{C}_{\mathrm{HU}}{q}_{{\mathrm{HU}}_j})\·t---\left(10\right)$

In the following formula: N _cThe cold public work expense of the unit of representative; N _hThe hot public work expense of the unit of representative; q _CuRepresent cold public work amount; q _HuRepresent hot public work amount; T represents a year running time.

Utilize random sampling technology in Monte Carlo to obtain [0,1] and go up equally distributed stochastic variable, these stochastic variables are represented the bypass aperture, and 0 representative is closed, and 1 represents standard-sized sheet.Adopt multiplicative congruential method to produce a series of pseudo random number, iterative formula is:

x _n+1＝mod(λx _n，M)(11)

r _n+1＝x _nM ^-1(12)

Wherein, λ takes advantage of the factor, and M is a modulus, and x is the bypass aperture.It is the congruence expression of modulus that first formula is called with M, promptly removes λ x with M _nAfter the remainder that obtains be designated as x _N+1As given initial value x ₀, the r that calculates ₁, r ₂... be in [0,1] and go up equally distributed random number.With these random numbers as the bypass initial opening.

The iterative formula of steepest descent method is:

x ⁽ⁱ⁺¹⁾＝x ⁽ⁱ⁾+λ _id ⁽ⁱ⁾(13)

Wherein:

${\mathrm{\λ}}_i=-\frac{\▿f{\left(x^{\left(i\right)}\right)}^T\▿f\left(x^{\left(i\right)}\right)}{\▿f{\left(x^{\left(i\right)}\right)}^{T}H\left(x^{\left(i\right)}\right)\▿f\left(x^{\left(i\right)}\right)}---\left(14\right)$

$d^{\left(i\right)}=\▿f\left(x^{\left(i\right)}\right)/\left|\right|\▿f\left(x^{\left(i\right)}\right)\left|\right|---\left(15\right)$

Utilize above-mentioned solution formula, can obtain best bypass aperture.In formula (13)-(14): i is an iterations, and x is the bypass aperture, λ _iBe the iteration optimal step size, d is the iteration descent direction.

In the present embodiment,, utilize Monte Carlo random sampling technology to obtain the initial bypass aperture of heat-exchange network, utilize steepest descent method to obtain best bypass aperture then according to heat-exchange network structural parameters and the fluid parameter that measures in real time.Because the Monte Carlo random sampling can enlarge the region of search of separating, in comprehensive steepest descent method, total energy obtains globally optimal solution, i.e. Zui Jia bypass aperture.When disturbance makes that enough the heat-exchange network runnability reduces, in time send the regulating command of bypass aperture, regulate the performance of in time improving heat-exchange network by bypass, guarantee fluid issuing parameter in the heat-exchange network, runnability is controlled at optimum range all the time.

Embodiment two

As shown in Figure 1, 2, a kind of flexible operation of novel heat exchanger network control device comprises:

Comprise by one or more heat exchangers 10,20,30 heat-exchange networks of forming, each heat exchanger comprise the first fluid pipeline and second fluid circuit, the porch 3 of described first fluid pipeline, the porch 13 of 23 and second fluid circuit, 33 are provided with flow sensor 6 respectively, 16,26,36 and temperature sensor 7,17,27,37, the porch of the responsive fluid circuit in the described heat-exchange network is provided with bypass, the exit of responsive fluid circuit is provided with electric T-shaped valve 11,12,21,22,31,32, an and bypass (concrete bypass number is determined by flexible identification in the heat-exchange network), described bypass is connected 11 with the electric T-shaped valve of corresponding responsive fluid circuit respectively, 12,21,22,31,32 are connected, described electric T-shaped valve 11,12,21,22,31,32 control end and flow sensor 6,16,26,36, temperature sensor 7,17,27,37 and one control computer 50 is connected.

Wherein, model such as Fig. 2 are regulated in the bypass of single heat exchanger in the heat-exchange network.

Wherein, public work 5,15,25,35 is connected on electric T-shaped valve 31,12,21, the 32 first fluid pipeline or second fluid circuit afterwards.

The present invention is by the aperture of the described electric T-shaped valve 11,12,21,22,31,32 of adjusting, thereby the adjusting ratio between change main line fluid and the bypass flow realizes the control to target fluid.In the whole control process, detect disturbance size and form by flow sensor 6,16,26,36 and temperature sensor 7,17,27,37, in conjunction with the structural information that preestablishes heat-exchange network, calculate by the best bypass aperture that control computer 50 is carried out among the embodiment one, aperture according to result of calculation is regulated described electric T-shaped valve 11,12,21,22,31,32 realizes the control of target fluid outlet temperature.

Wherein, what described hygrosensor 7,17,27,37 and flow probe 6,16,26,36 can adopt simulation also can adopt numeral, adopts the hygrosensor 7,17,27,37 and the flow probe 6,16,26,36 of simulation in the present embodiment.And between described hygrosensor 7,17,27,37 and flow probe 6,16,26,36 and described control computer 5, also be connected with analog multichannel switch 51 and A/D converter 52 in turn.Described analog multichannel switch 51 is used for the switch control of described hygrosensor 7,17,27,37 and flow probe 6,16,26,36.Temperature that described A/D converter 3 is used to obtain and flow analog signals are converted to data signal and send into described control computer 50.

Wherein, described control computer 50 is connected with described analog multichannel switch 51, and described control computer 50 connects the Push And Release of the described analog multichannel switch 51 of control by this.

Wherein, between the control end of described electric T-shaped valve 11,12,21,22,31,32 and described control computer 50, also be connected with D/A converter 53, be used for the data signal of described control computer 50 outputs is converted to analog signal, to control the best bypass aperture of described electric T-shaped valve 11,12,21,22,31,32.

Wherein, described heat exchanger 1 can be a shell-and-tube, various types of heat exchangers such as plate-fin.

Wherein, hygrosensor 7,17,27,37 can adopt the detector of types such as thermocouple, RTD.

Wherein, described flow probe 6,16,26,36 can adopt turbine flowmeter or orifice flowmeter etc.

Wherein, described control computer 50 can adopt PLC controller, single-chip microcomputer, microcomputer etc., it is as the core of heat-exchange network flexible operation controller, major function is: functions such as the input and output of data, the calculating of bypass regulated quantity, calculating comprise that calculating is optimized in heat-exchange network analog computation, bypass adjusting and calculating etc. is controlled in the bypass adjusting.

Wherein, described multiway analog switch 51 and A/D converter 52 can be selected general-purpose device for use according to required precision and speed, constitute analog input channel, under the control of described control computer 50, realize the temperature and the isoparametric touring detection of flow of fluid intake in the heat exchanging network, convert data volume to by A/D and be transferred to described control computer 50.

Wherein, described D/A converter 53 can be selected general D/A chip for use according to required precision and speed, the current signal of outputting standard (4～20mA or 0～10V) or voltage signal (0～10V or other optional scope), the executing agency that is used to provide fluid bypass to regulate is the signal of described electric T-shaped valve 11,12,21,22,31,32, realizes the bypass adjusting.

Claims (9)

1. the control method of a flexible operation of novel heat exchanger network is characterized in that may further comprise the steps:

1) the responsive fluid in the identification heat-exchange network, and on described responsive fluid, bypass regulating device is set;

2) obtain the temperature and the flow parameter of the responsive fluid in porch;

3), find the solution best bypass aperture according to the variation of this temperature and flow parameter with preestablish the structural information of heat-exchange network;

4) regulate the aperture of bypass regulating device according to the best bypass aperture of finding the solution.

2. the control method of flexible operation of novel heat exchanger network according to claim 1, it is characterized in that: in the described step 1), the identification of described responsive fluid may further comprise the steps successively:

A, the structural parameters that obtain heat-exchange network under the design conditions, fluid parameter and heat exchanger parameter;

B, with the parameter informationization of heat-exchange network, utilize heat-exchange network steady-state simulation technology to realize the simulation of heat-exchange network;

The suction parameter of fluid utilizes simulation to obtain the fluid issuing parameter in C, the change heat-exchange network, and given different suction parameter obtains corresponding outlet parameter response curve;

D, according to the interval that technology allows, analyze outlet parameter response curve, obtain the flexible characteristic of heat-exchange network;

E, if the flex region of certain fluid between less than a certain value, this fluid is responsive fluid.

3. the control method of flexible operation of novel heat exchanger network according to claim 1 and 2, it is characterized in that: in described step 3), according to heat-exchange network structural parameters and the fluid parameter that measures in real time, utilize Monte Carlo random sampling technology to obtain the initial bypass aperture of heat-exchange network, utilize steepest descent method to obtain best bypass aperture then.

4. the control method of flexible operation of novel heat exchanger network according to claim 3, it is characterized in that: utilize Monte Carlo random sampling technology to obtain the initial bypass aperture of heat-exchange network and be specially: utilize random sampling technology in Monte Carlo to obtain [0,1] goes up equally distributed stochastic variable, this stochastic variable is represented the bypass aperture, adopt multiplicative congruential method to produce a series of pseudo random number, iterative formula is:

x _n+1＝mod(λx _n，M)

r _n+1＝x _nM ^-1

Wherein, λ takes advantage of the factor, and M is a modulus, as given initial value x ₀, the r that calculates ₁, r ₂... be in [0,1] and go up equally distributed random number, with these random numbers as the bypass initial opening.

5. the control method of flexible operation of novel heat exchanger network according to claim 4 is characterized in that: utilize steepest descent method to obtain best bypass aperture and be specially:

Iterative formula according to steepest descent method:

x ⁽ⁱ⁺¹⁾＝x ⁽ⁱ⁾+λ _id ⁽ⁱ⁾

Wherein:

${\mathrm{\λ}}_i=-\frac{\▿f{\left(x^{\left(i\right)}\right)}^T\▿f\left({\left(x\right)}^{\left(i\right)}\right)}{\▿f{\left(x^{\left(i\right)}\right)}^{T}H\left(x^{\left(i\right)}\right)\▿f\left(x^{\left(i\right)}\right)}$

$d=\▿f\left(x\right)/\left|\right|\▿f\left(x\right)\left|\right|$

Utilize above-mentioned solution formula, obtain best bypass aperture.

6. flexible operation of novel heat exchanger network control device, it is characterized in that comprising: the heat-exchange network of forming by one or more heat exchangers, each heat exchanger comprise the first fluid pipeline and second fluid circuit, the porch of the porch of described first fluid pipeline and second fluid circuit is provided with flow sensor and temperature sensor respectively, the porch of the responsive fluid circuit in the described heat-exchange network is provided with bypass, the exit of responsive fluid circuit is provided with an electric T-shaped valve, described bypass is connected with the electric T-shaped valve of corresponding responsive fluid circuit respectively, the control end of described electric T-shaped valve and flow sensor, temperature sensor is connected with a control computer, described control computer is according to the flow and the temperature information that obtain, in conjunction with the structural information that preestablishes heat-exchange network, carry out best bypass aperture and calculate the aperture of regulating described electric T-shaped valve according to result of calculation.

7. flexible operation of novel heat exchanger network control device according to claim 6 is characterized in that: also be connected with analog multichannel switch and A/D converter in turn between described hygrosensor and flow probe and the described control computer 5.

8. flexible operation of novel heat exchanger network control device according to claim 7 is characterized in that: described control computer is connected with described analog multichannel switch.

9. according to the described flexible operation of novel heat exchanger network control device of arbitrary claim in the claim 6 to 8, it is characterized in that: between the control end of described electric T-shaped valve and described control computer, also be connected with D/A converter.

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