CN1570784A - Control method for operation pinch point of crude oil heat exchange network - Google Patents

Abstract

This invention is a control method for crude oil heat transferring network operation clamps, which is to establish a mechanism model for heat transfer to dynamically obtain exit temperature variables of each heat transfers in the network. If it is to locate N heat transfers in the network, its mathematical module of minimal temperature difference of its clamps would be: DeltaT min=MIN(DeltaT 1, DeltaT 2, ..., DeltaT i, ..., DeltaT N), wherein, DeltaT i stands for heat transferring difference between heat and cool logistics involved in number i heat transfer. By ..., DeltaT i, ..., DeltaT N)), using the said model, we can obtain minimal temperature difference and corresponding heat and cool logistics in the crude oil heat transferring network and to control the temperature difference of operation clamps by adding a side path for heat transfer to keep it at its best to obtain the minimal public construction quantity.

Description

The control method of crude oil heat exchange network operation pinch point

Technical field

The present invention relates to the control technology field of petrochemical complex, is a kind of operation pinch point control method of crude oil heat exchange network concretely.

Background technology

Petrochemical enterprise be China with can the rich and influential family, and the crude oil atmospheric vacuum distillation device energy-wasting is very big, account for whole refinery oil refining with can 20%～30%, the height key of this plant energy consumption depends on that the energy recovery of normal decompression heat exchanger network utilizes level.

Current, in for the big quantity research that improves heat exchanger network energy recovery level, mainly concentrate in the utilization of pinch technology, the proposition of pinch technology is an important breakthrough in the synthetic field of heat exchanger network, it is based on the second law of thermodynamics, with energy recovery to greatest extent be utilized as starting point again, temperature in the heat exchanger network " folder point " has limited the maximum heat yield that may reach, fully grasp the characteristic of " folder point ", can carry out Optimal design of heat exchanger network effectively, and the pinch technology method is simple and practical, and engineering technical personnel can bring into play engineering design and production experience for many years, reasonably consider the engineering factor that some are necessary.Pinch technology is from being born and through two during the last ten years development, it uses degree of depth and range is all constantly being widened, and has obtained obvious energy-saving effect in worldwide, has nowadays developed into a general utility tool of heat exchanger network design.

The problem that exists in the actual heat exchanger network energy recovery process: comparatively perfect when (one) pinch technology is used for the new design of heat exchanger network, because the design of most of heat exchanger networks is all carried out at a certain specific operating conditions.But after heat exchanger network put into operation, the working condition in the chemical process changed in a certain scope of being everlasting, and during the operating conditions fluctuation, how the folder point temperature difference and public work change, and also do not have document to relate to this type of research at present.(2) present, for the control of actual heat exchanger network, only control the finishing temperature of heat exchange logistics usually, the temperature of logistics intermediate node is not then regulated.When the heat exchanger network operating conditions fluctuates like this, just can not in time cold and hot logistics in the heat exchanger network be controlled on the best potential temperature coupling, cause heat exchanger network heat recovery amount to reduce.(3) present, the heat exchanger network major part is to link together with concrete device, and network is more complicated, therefore analyses in depth and carry out complex optimum for the operating conditions of heat exchanger network just to seem particularly important.

If can be according to the actual mechanical process of folder point principle analysis heat exchanger network, find out bottleneck place wherein, from control the problem that the angle analysis heat exchanger network exists operational process, thereby adjust the control strategy of heat exchanger network, improve the control effect, just can really realize the maximization of heat exchanger network heat recovery amount in operation, reach energy saving purposes.

Summary of the invention

The object of the present invention is to provide a kind of control method of crude oil heat exchange network operation pinch point, can implement to control the transformation range of heat exchanger network operation pinch point minimum temperature difference, realize the optimization of operation pinch point, reach minimum public work consumption.

The object of the present invention is achieved like this: a kind of control method of crude oil heat exchange network operation pinch point, and wherein, the heat exchanging device carries out modelling by mechanism, thereby dynamically draws the outlet temperature variable quantity of each heat interchanger in the crude oil heat exchange network;

If establish N platform heat interchanger is arranged in the crude oil heat exchange network, then its operation pinch point minimum temperature difference dynamic mathematical models are: Δ T _Min=MIN (Δ T ₁, Δ T ₂..., Δ T _i..., Δ T _N)), Δ T wherein _iIt is the heat transfer temperature difference that participates in the hot and cold logistics of heat exchange in the i platform heat interchanger;

According to resulting result behind the described modelling by mechanism, utilize described operation pinch point minimum temperature difference dynamic mathematical models, draw the minimum temperature difference in the crude oil heat exchange network and the cold and hot logistics of operation pinch point correspondence;

Heat interchanger is set up bypass, thereby the some temperature difference is pressed from both sides in control operation indirectly, makes it to remain on the optimum value, and then draws minimum public work consumption.

Minimum temperature difference in the described crude oil heat exchange network is (T _{H, i}-T _{C, i}), the cold and hot logistics of described operation pinch point correspondence is respectively T _{C, i}, T _{H, i}

With cold flow at T _{C, i}Certain heat interchanger of upstream is set up bypass, and bypass can be added on this cold flow, also can be added on the hot-fluid with the cold flow heat exchange, and bypass can stride across a heat interchanger also can stride across many heat interchanger; Simultaneously with hot-fluid at T _{H, i}Certain heat interchanger of upstream is also set up bypass, and bypass can be added on this hot-fluid, also can be added on the cold flow with this hot-fluid heat exchange, and same, bypass can stride across a heat interchanger also can stride across many heat interchanger;

Control T by the flow of regulating added bypass _{H, i}, T _{C, i}Thereby the some temperature difference (T is pressed from both sides in control operation indirectly _{H, i}-T _{C, i}), make it not to be subjected to operation to be disturbed and remain on the optimum value.

The operation pinch point position is determined by temperature enthalpy chart; Wherein, when hot complex curve moves, must make corresponding mobile to cold flow curve corresponding in each heat interchanger in the cold complex curve.

Describedly set up bypass and be meant: set up bypass by the appropriate location in heat exchanger network, and installation operation valve, come the temperature of the control operation folder point hot and cold logistics in place by the control bypass flow, and then the control operation folder point temperature difference, make it in the device operational process, to maintain near the design load all the time, the variation range of control heat exchanger network operation pinch point minimum temperature difference realizes the optimization of operation pinch point in real time, thereby reduces the public work consumption of heat exchanger network to greatest extent.

Described heat interchanger is a shell-and-tube heat exchanger; Described shell-and-tube heat exchanger mechanism model comprises: analyzed for the fluid infinitesimal, write the dynamic mathematical models of shell side, tube side, pipe outer wall, inside pipe wall according to heat mobile equilibrium equation row.

Described heat interchanger is a steam generator; Described steam generator mechanism model comprises: analyzed for the fluid infinitesimal, write the dynamic mathematical models of tube side, inside pipe wall, pipe outer wall, steam generating amount according to heat mobile equilibrium equation row.

Described shell-and-tube heat exchanger is set up discretization model, that is: the heat-exchanger model as distributed parameter model is carried out the segmentation discretize, being considered as lumped parameter model on each section handles, simultaneous obtains the lumped parameter model of each section again, then finish the calculating of solving model, comprise the discretize mathematical model of shell side, tube side, pipe outer wall, inside pipe wall.

Described steam generator is set up discretization model, that is: the model steam generator as distributed parameter model is carried out the segmentation discretize, being considered as lumped parameter model on each section handles, simultaneous obtains the lumped parameter model of each section again, then finish the calculating of solving model, comprise the discretize mathematical model of tube side, pipe outer wall, inside pipe wall, steam generating amount.

Described operation pinch point minimum temperature difference is meant: after the heat exchanger network that utilizes pinch technology to design puts into operation, and the minimum value of the hot-fluid and the actual temperature difference of cold flow in the heat exchanger network.

Described operation pinch point is meant: after the heat exchanger network that utilizes pinch technology to design put into operation, the position that occurs the minimum value of the hot-fluid and the cold flow temperature difference in the actual heat exchanger network was exactly an operation pinch point.

Method of the present invention is used for crude oil heat exchange network, a simple network with minimum public work of pinch technology design is adopted in utilization under a certain specific operation condition, from designing and operating two energy recovery situations the different angles analysis heat exchanger networks, provide the control method of heat exchanger network folder point minimum temperature difference in the operating process, analyze the situation of change of public work, and compare with the conventional controlling schemes of heat exchanger network, reduce the public work consumption by control operation folder point minimum temperature difference, the present invention is according to the pinch technology principle, in heat exchanger network, set up bypass and control bypass flow, control the medium temperature of some logistics in the actual heat exchanger network, then control the operation pinch point temperature difference in the actual heat exchanger network, make heat exchanger network in operational process, be in the state of minimum public work consumption all the time, reach energy saving purposes.

As seen, compare with the control technology of existing heat exchanger network, the present invention not only controls the temperature eventually that participates in the heat exchange logistics, but also control the medium temperature of some heat exchange logistics, the potential temperature coupling of heat exchange logistics can be changed with the change of practical operation condition, thereby make that the heat transferred at whole heat exchange networking is at one's best all the time.

Description of drawings

Fig. 1: determine heat exchanger network folder point and minimum public work (design) by temperature enthalpy chart;

Fig. 2: the conventional controlling schemes of heat exchanger network;

Fig. 3: determine the heat exchanger network operation pinch point;

Fig. 4: heat exchanger network operation pinch point controlling schemes;

Fig. 5: control method schematic flow sheet of the present invention.

Embodiment

The present invention is a kind of control method of crude oil heat exchange network operation pinch point, and as shown in Figure 5, this method heat exchanging device carries out modelling by mechanism, thereby dynamically draws the outlet temperature variable quantity of each heat interchanger in the crude oil heat exchange network;

If establish N platform heat interchanger is arranged in the crude oil heat exchange network, then its operation pinch point minimum temperature difference dynamic mathematical models are: Δ T _Min=MIN (Δ T ₁, Δ T ₂..., Δ T _i..., Δ T _N)), Δ T wherein _iIt is the heat transfer temperature difference that participates in the hot and cold logistics of heat exchange in the i platform heat interchanger;

According to resulting result behind the described modelling by mechanism, utilize described operation pinch point minimum temperature difference dynamic mathematical models, draw the minimum temperature difference in the crude oil heat exchange network and the cold and hot logistics of operation pinch point correspondence;

Heat interchanger is set up bypass, thereby the some temperature difference is pressed from both sides in control operation indirectly, makes it to remain on the optimum value, and then draws minimum public work consumption.

Minimum temperature difference in the crude oil heat exchange network of the present invention is (T _{H, i}-T _{C, i}), the cold and hot logistics of described operation pinch point correspondence is respectively T _{C, i}, T _{H, i}

With cold flow at T _{C, i}Certain heat interchanger of upstream is set up bypass, and bypass can be added on this cold flow, also can be added on the hot-fluid with the cold flow heat exchange, and bypass can stride across a heat interchanger also can stride across many heat interchanger; Simultaneously with hot-fluid at T _{H, i}Certain heat interchanger of upstream is also set up bypass, and bypass can be added on this hot-fluid, also can be added on the cold flow with this hot-fluid heat exchange, and same, bypass can stride across a heat interchanger also can stride across many heat interchanger;

Control T by the flow of regulating added bypass _{H, i}, T _{C, i}Thereby the some temperature difference (T is pressed from both sides in control operation indirectly _{H, i}-T _{C, i}), make it not to be subjected to operation to be disturbed and remain on the optimum value.

The operation pinch point position is determined by temperature enthalpy chart; Wherein, when hot complex curve moves, must make corresponding mobile to cold flow curve corresponding in each heat interchanger in the cold complex curve.

Describedly set up bypass and be meant: set up bypass by the appropriate location in heat exchanger network, and installation operation valve, come the temperature of the control operation folder point hot and cold logistics in place by the control bypass flow, and then the control operation folder point temperature difference, make it in the device operational process, to maintain near the design load all the time, the variation range of control heat exchanger network operation pinch point minimum temperature difference realizes the optimization of operation pinch point in real time, thereby reduces the public work consumption of heat exchanger network to greatest extent.

Described heat interchanger is a shell-and-tube heat exchanger; Described shell-and-tube heat exchanger mechanism model comprises: analyzed for the fluid infinitesimal, write the dynamic mathematical models of shell side, tube side, pipe outer wall, inside pipe wall according to heat mobile equilibrium equation row.

Described heat interchanger is a steam generator; Described steam generator mechanism model comprises: analyzed for the fluid infinitesimal, write the dynamic mathematical models of tube side, inside pipe wall, pipe outer wall, steam generating amount according to heat mobile equilibrium equation row.

Described shell-and-tube heat exchanger is set up discretization model, that is: the heat-exchanger model as distributed parameter model is carried out the segmentation discretize, being considered as lumped parameter model on each section handles, simultaneous obtains the lumped parameter model of each section again, then finish the calculating of solving model, comprise the discretize mathematical model of shell side, tube side, pipe outer wall, inside pipe wall.

Described steam generator is set up discretization model, that is: the model steam generator as distributed parameter model is carried out the segmentation discretize, being considered as lumped parameter model on each section handles, simultaneous obtains the lumped parameter model of each section again, then finish the calculating of solving model, comprise the discretize mathematical model of tube side, pipe outer wall, inside pipe wall, steam generating amount.

Described operation pinch point minimum temperature difference is meant: after the heat exchanger network that utilizes pinch technology to design puts into operation, and the minimum value of the hot-fluid and the actual temperature difference of cold flow in the heat exchanger network.

Described operation pinch point is meant: after the heat exchanger network that utilizes pinch technology to design put into operation, the position that occurs the minimum value of the hot-fluid and the cold flow temperature difference in the actual heat exchanger network was exactly an operation pinch point.

The present invention mainly is based on the heat interchanger modelling by mechanism, the outlet temperature situation of change of each heat interchanger in the performance analysis heat exchanger network; Use for reference the pinch technology principle, propose the notion of operation pinch point and provide the computing method of operation pinch point minimum temperature difference; Take to set up the method for bypass, control the variation range of heat exchanger network operation pinch point minimum temperature difference in real time, realize the optimization of operation pinch point, reduce the public work consumption to greatest extent.

Described based on the heat interchanger modelling by mechanism, the outlet temperature situation of change of each heat interchanger is meant in the performance analysis heat exchanger network: according to exchanger heat balance equation and heat transfer equation, calculate the dynamic change relation between the hot and cold logistics outlet temperature of heat interchanger and hot and cold logistics inlet temperature of this heat interchanger and the flow.

The ultimate principle of the pinch technology that the present invention is pointed is meant: there is a minimum heat transfer temperature difference in the hot and cold logistics in the heat exchanger network in heat recycle process, this place is the folder point, and it is restricting the heating and cooling public work consumption of heat exchanger network minimum.

During the design of heat exchanger network, minimum temperature difference Δ T _MinBig more, required total heat interchanging area reduces, and the heat exchanger network cost of equipment reduces, but public work expense (operation cost) increases; Minimum temperature difference Δ T _MinMore little, required total heat interchanging area increases, and the heat exchanger network cost of equipment increases, but public work expense (operation cost) reduces.So minimum temperature difference Δ T _MinHave an optimum value, heat exchanger network cost of equipment that this value is corresponding and public work expense (operation cost) sum are minimum.

In the present invention, operation pinch point can obtain by temperature enthalpy chart, with as shown in Figure 1 the heat exchange system of being made up of two strands of cold flows of two strands of hot-fluids is example, when hot complex curve is moved to the ABC position, makes that the minimum temperature difference between hot complex curve and the cold complex curve A ' B ' C ' D ' is Δ T just _Min, promptly BP is the folder point of this heat exchanger network.Folder point location tables is shown a thermodynamic limitation point, and this point has limited the further heat interchange between the hot and cold stream thigh, makes cold and hot public work consumption all reach minimum value, and coupling is an energetic optimum between stream thigh at this moment.

According to the folder design method of points, obtain the global design scheme that this heat-exchange system has minimum public work, as shown in Figure 2.

In the present invention, the notion of described proposition operation pinch point and the computing method that provide the operation pinch point minimum temperature difference are meant: utilize after the heat exchanger network of pinch technology design puts into operation, because heat exchanger network exists, when utilizing temperature enthalpy chart to determine folder point position, cold and hot complex curve can move arbitrarily in the time of just can not designing as heat exchanger network again, satisfies Δ T until minimum temperature difference _MinWhen this moment, hot complex curve moved, must make corresponding mobile to cold flow curve corresponding in each heat interchanger in the cold complex curve.Be temperature variation corresponding move of the cold and hot complex curve of described temperature enthalpy chart with heat interchanger.

At this moment, resulting minimum temperature difference Δ T _MinIt also no longer is the optimum minimum temperature difference that obtains according to technical economical analysis, but the minimum value of hot-fluid and the actual temperature difference of cold flow in the heat exchanger network, the minimum value that the present invention defines the actual temperature difference of this hot and cold stream is the operation pinch point minimum temperature difference, and the position that this minimum temperature difference occurs is exactly the operation pinch point of actual heat exchanger network.The position of the operation pinch point temperature difference and operation pinch point can be drawn by temperature enthalpy chart shown in Figure 3 and be obtained.

The method that this method is taked to set up bypass is meant: set up bypass by the appropriate location in heat exchanger network (such as cold flow one side of E-103 in Fig. 4), and installation operation valve, come the temperature of the hot and cold stream in control operation folder point place by the control bypass flow, the point temperature difference is pressed from both sides in control operation indirectly, make it in the device operational process, to maintain near the design load all the time, control the variation range of heat exchanger network operation pinch point minimum temperature difference in real time, realize the optimization of operation pinch point, thereby reduce the public work consumption of heat exchanger network to greatest extent.

By the definition of front heat exchanger network operation pinch point as can be seen, determine that operation pinch point needs the import and export temperature of the hot and cold logistics of each heat interchanger in the heat exchanger network, but in the crude oil heat exchange network of reality, usually only measure the preceding gentleness just of changing of each heat exchange logistics and change back temperature eventually, and each heat interchanger import and export place does not establish temperature point in heat exchanger network.Therefore, the present invention carries out modelling by mechanism by the heat exchanging device, and utilize the heat interchanger mechanism model to build the emulation system of whole crude oil heat exchange network, and go out the gateway temperature of each heat interchanger by simulation calculation, ask the operation pinch point position of calculating crude oil heat exchange network then.On this basis, take to set up the control measure of bypass, the operation pinch point at control crude oil heat exchange networking.

Below adopt specific embodiment that method of the present invention is described:

(1) sets up the heat interchanger dynamic mathematical models

Mainly be made up of two types heat interchanger in the crude oil heat exchange network, a class is a shell-and-tube heat exchanger, and commonly used has single tube monoshell, two pipe monoshells, four pipe monoshells and six pipe monoshells several, and shell-and-tube heat exchanger proportion in crude oil heat exchange network is bigger; Another kind of is steam generator, negligible amounts, but the heat recovery ability is strong.Because this two classes heat interchanger heat transfer mechanism exists than big difference, thereby should carry out modelling by mechanism respectively.

1. shell-and-tube heat exchanger mechanism model

At monoshell Cheng Dan tube side shell-and-tube contra-flow heat exchanger, fluid 1 and fluid 2 all do not have axially to mix, and do not have phase transformation, belong to distributed parameter system.

Before setting up the dynamic mechanism mathematical model of single tube monoshell shell-and-tube contra-flow heat exchanger, at first suppose:

(1) fluid flows near plug flow regime;

(2) fluid and heat exchanger tube specific heat Cp ₁, Cp ₂, Cp remains unchanged;

(3) fluid and heat exchanger tube coefficient of heat conductivity λ ₁, λ ₂, λ remains unchanged;

(4) fluid viscosity coefficient μ ₁, μ ₂Remain unchanged;

(5) the each point temperature is identical on the same cross section.

In order more accurately to investigate the dynamic process of heat interchanger, consider the influence of flow to heat transfer coefficient, the present invention is with shell journey heat transfer coefficient K ₀, K _iBe expressed as the function of flow.

At first row are write the dynamic equation of fluid 1 in the shell side, get one section infinitesimal dx for fluid 1 and analyzed, heat mobile equilibrium equation is: the rate of change of amount of stored heat in (unit interval inner fluid 1 is brought the heat of infinitesimal into)-(unit interval inner fluid 1 leaves the heat that infinitesimal is taken away)+(the heat exchanger tube outer wall is passed to the heat of fluid 1 infinitesimal in the unit interval)=fluid 1 infinitesimal

According to heat mobile equilibrium equation, can obtain the dynamic model of shell-side fluid:

$\frac{\&PartialD;{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">T</figure-callout>}}_1}{\&PartialD;t}=-\frac{m_1}{{\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">M</figure-callout>}}_1}\&CenterDot;\frac{\&PartialD;{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">T</figure-callout>}}_1}{\&PartialD;x}+\frac{\mathrm{n\&pi;}{d}_0{K}_0}{M_1{C}_{p1}}[T_{W0}-T_1]$

Equally, can obtain the dynamic mathematical models of tube side, pipe outer wall, inside pipe wall, specific as follows:

Tube side:

$\frac{\&PartialD;{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="A20041003816200221.png,A20041003816200241.png"\; state="\{\{state\}\}">T</figure-callout>}}_2}{\&PartialD;t}=-\frac{m_2}{{\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="A20041003816200221.png,A20041003816200241.png"\; state="\{\{state\}\}">M</figure-callout>}}_2}\&CenterDot;\frac{\&PartialD;{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="A20041003816200221.png,A20041003816200241.png"\; state="\{\{state\}\}">T</figure-callout>}}_2}{\&PartialD;x}+\frac{\mathrm{n\&pi;}{d}_i{K}_i}{M_2{C}_{p2}}[T_2-T_{\mathrm{Wi}}]$

The pipe outer wall:

$\frac{\&PartialD;{\mathrm{<figure-callout\; id="0"\; label="T\; W"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">T</figure-callout>}}_W}{\&PartialD;t}=\frac{2\mathrm{n\&pi;\&lambda;}(T_{\mathrm{Wi}}-T_{W0})}{M_W{C}_P\ln ({\mathrm{<figure-callout\; id="0"\; label="d"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">d</figure-callout>}}_0/d_i)}-\frac{\mathrm{n\&pi;}{d}_0{K}_0}{M_W{C}_P}[T_{W0}-T_1]$

Inside pipe wall:

$\frac{\&PartialD;T_{\mathrm{Wi}}}{\&PartialD;t}=\frac{-2\mathrm{n\&pi;\&lambda;}(T_{\mathrm{Wi}}-T_{W0})}{M_W{C}_P\ln ({\mathrm{<figure-callout\; id="0"\; label="d"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">d</figure-callout>}}_0/d_i)}+\frac{\mathrm{n\&pi;}{d}_i{K}_i}{M_W{C}_P}[T_2-T_{\mathrm{Wi}}]$

Above various in:

m ₁Shell-side fluid 1 flow, kg/s

m ₂ Tube side fluid 2 flows, kg/s

Cp ₁Shell-side fluid 1 specific heat, kJ/kgK

Cp ₂ Tube side fluid 2 specific heats, kJ/kgK

Cp heat exchanger tube specific heat, kJ/kgK

K _iThe tube side heat transfer coefficient, W/m ²K

K ₀The shell side heat transfer coefficient, W/m ²K

T ₁Shell-side fluid 1 temperature, K

T ₂ Tube side fluid 2 temperature, KT _W0The heat exchanger tube outside wall temperature, K

T _WiThe heat exchanger tube inner wall temperature, K

μ ₁The viscosity of shell-side fluid 1, Pas

μ ₂The viscosity of tube side fluid 2, Pas

λ ₁Shell-side fluid 1 coefficient of heat conductivity, W/mK

λ ₂ Tube side fluid 2 coefficient of heat conductivity, W/mK

M ₁The quality of shell-side fluid 1 unit length, kg/m

M ₂The quality of tube side fluid 2 unit lengths, kg/m

M _WThe quality of heat exchanger tube unit length, kg/m

N heat exchanger tube number

d _iThe heat exchanger tube internal diameter, m

d ₀The heat exchanger tube external diameter, m

As a same reason, can set up the mathematics mechanism model of two pipe monoshells, four pipe monoshells, several shell-and-tube heat exchangers of six pipe monoshell pipes.

2. steam generator mechanism model

Steam generator is generally all arranged in the crude oil heat exchange network, normally, owing in the steam generator phase transformation is arranged, thereby its mathematical model will be set up separately according to its heat-transfer mechanism with some side line heating deoxidation water generates steam of normal decompression.

At the steam generator that produces steam with tube side fluid 1 heating deoxygenated water 2, at first suppose:

(1) tube side fluid 1 flows near plug flow regime;

(2) fluid 1 and heat exchanger tube specific heat Cp1, Cp remain unchanged;

(3) fluid 1 and heat exchanger tube specific heat λ ₁, λ remains unchanged;

(4) fluid 1 viscosity coefficient μ ₁Remain unchanged;

During even running, deoxygenated water is in state of saturation in the whole steam generator, and the temperature homogeneous equals the boiling point T under the normal running environment of steam generator _Water

In order more accurately to investigate the dynamic process of steam generator, consider the influence of flow to heat transfer coefficient, the present invention is with tube side heat transfer coefficient K _iBe expressed as the function of flow.And shell side heat transfer coefficient K.It is the function of the boiling heat transfer coefficient under the steam generator operating conditions.

The modeling method and the shell-and-tube heat exchanger of tube side fluid 1, inside pipe wall are identical, can get:

Tube side:

$\frac{\&PartialD;{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">T</figure-callout>}}_1}{\&PartialD;t}=-\frac{m_1}{{\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">M</figure-callout>}}_1}\&CenterDot;\frac{\&PartialD;{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">T</figure-callout>}}_1}{\&PartialD;x}-\frac{\mathrm{n\&pi;}{d}_i{K}_i}{M_1{C}_{p1}}[T_1-T_{\mathrm{Wi}}]$

Inside pipe wall:

$\frac{\&PartialD;T_{\mathrm{Wi}}}{\&PartialD;t}=\frac{-2\mathrm{n\&pi;\&lambda;}(T_{\mathrm{Wi}}-T_{W0})}{M_W{C}_P\ln ({\mathrm{<figure-callout\; id="0"\; label="d"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">d</figure-callout>}}_0/d_i)}+\frac{\mathrm{n\&pi;}{d}_i{K}_i}{M_W{C}_P}[T_1-T_{\mathrm{Wi}}]$

What contact with the pipe outer wall is that the temperature homogeneous is T _WaterDeoxygenated water, thereby the pipe outer wall heat balance be calculated as follows:

The pipe outer wall:

$\frac{\&PartialD;{\mathrm{<figure-callout\; id="0"\; label="T\; W"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">T</figure-callout>}}_W}{\&PartialD;t}=\frac{2\mathrm{n\&pi;\&lambda;}(T_{\mathrm{Wi}}-T_{W0})}{M_W{C}_P\ln ({\mathrm{<figure-callout\; id="0"\; label="d"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">d</figure-callout>}}_0/d_i)}-\frac{\mathrm{n\&pi;}{d}_0{K}_0}{M_W{C}_P}[T_{W0}-T_{\mathrm{Water}}]$

When heat interchanger is in the even running state, can think required heat when heat that hot-fluid reduces equals the deoxygenated water vaporization and generates saturated vapour, thereby the steam production model can obtain steam generator and normally move the time:

Steam production:

$m_{\mathrm{Steamer}}=\frac{{\mathrm{Cp}}_1({\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">T</figure-callout>}}_{1,\mathrm{in}}-{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">T</figure-callout>}}_{1,\mathrm{out}})}{H}$

Above various in:

m ₁ Tube side fluid 1 flow, kg/s

Cp ₁ Tube side fluid 1 specific heat, kJ/kgK

Cp heat exchanger tube specific heat, kJ/kgK

K _iThe tube side heat transfer coefficient, W/m ²K

K ₀The shell side heat transfer coefficient, W/m ²KT ₁ Tube side fluid 1 temperature, K

T _{1, in} Tube side fluid 1 temperature in, K

T _{1, out} Tube side fluid 1 outlet temperature, K

T _WaterThe boiling temperature of shell side deoxygenated water under service condition, K

L _W0The heat exchanger tube outside wall temperature, K

L _WiThe heat exchanger tube inner wall temperature, K

μ ₁The viscosity of tube side fluid 1, Pas

λ ₁ Tube side fluid 1 coefficient of heat conductivity, W/mK

M ₁The quality of tube side fluid 1 unit length, kg/m

M _WThe quality of heat exchanger tube unit length, kg/m

N heat exchanger tube number

d _iThe heat exchanger tube internal diameter, m

d ₀The heat exchanger tube external diameter, m

m _SteamerSteam generating amount, kg/s

The latent heat of vaporization of H deoxygenated water under service condition, kJ/kg

(2) the segmentation discretize of heat-exchanger model

Because above-mentioned heat interchanger, model steam generator all are distributed parameter models, for ease of asking calculation, it is carried out the segmentation discretize, on each section, be considered as lumped parameter model and handle, simultaneous obtains the lumped parameter model of each section again, finishes the calculating of solving model then.If heat interchanger is divided into the N section, discrete back model is as follows:

1. shell-and-tube heat exchanger discretization model

Shell side

$\frac{\&PartialD;{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">T</figure-callout>}}_{1,n}}{\&PartialD;t}=[-\frac{m_1}{{\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">M</figure-callout>}}_1\mathrm{\&Delta;}{x}_n}-\frac{\mathrm{n\&pi;}{d}_0{K}_0}{M_1{C}_{p1}}]{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">T</figure-callout>}}_{1,n}+\frac{\mathrm{n\&pi;}{d}_0{K}_0}{M_1{C}_{p1}}{\mathrm{<figure-callout\; id="0"\; label="T\; W"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">T</figure-callout>}}_W+\frac{m_1}{{\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">M</figure-callout>}}_1\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="x\; n\; T"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">x</figure-callout>}}_n}{T}_{}{}_{1,n-1}$

The pipe outer wall

$\frac{\&PartialD;{\mathrm{<figure-callout\; id="0"\; label="T\; W"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">T</figure-callout>}}_W}{\&PartialD;t}=[-\frac{2\mathrm{n\&pi;\&lambda;}}{M_W{C}_P\ln ({\mathrm{<figure-callout\; id="0"\; label="d"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">d</figure-callout>}}_0/d_I)}-\frac{\mathrm{n\&pi;}{d}_0{K}_0}{M_W{C}_P}]{\mathrm{<figure-callout\; id="0"\; label="T\; W"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">T</figure-callout>}}_W+\frac{\mathrm{n\&pi;}{d}_0{K}_0}{M_W{\mathrm{<figure-callout\; id="1"\; label="C\; P\; T"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">C</figure-callout>}}_P}{T}_{}{}_{1,n}+\frac{2\mathrm{n\&pi;\&lambda;}}{M_W{C}_P\ln ({\mathrm{<figure-callout\; id="0"\; label="d"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">d</figure-callout>}}_0/d_i)}{\mathrm{<figure-callout\; id="1"\; label="T\; W"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">T</figure-callout>}}_W$

Inside pipe wall

$\frac{\&PartialD;T_{\mathrm{Wi},n}}{\&PartialD;t}=[-\frac{2\mathrm{n\&pi;\&lambda;}}{M_W{C}_P\ln ({\mathrm{<figure-callout\; id="0"\; label="d"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">d</figure-callout>}}_0/d_i)}-\frac{\mathrm{n\&pi;}{d}_i{K}_i}{M_W{C}_P}]T_{\mathrm{Wi},n}+\frac{\mathrm{n\&pi;}{d}_i{K}_i}{M_W{\mathrm{<figure-callout\; id="2"\; label="C\; P\; T"\; filenames="A20041003816200221.png,A20041003816200241.png"\; state="\{\{state\}\}">C</figure-callout>}}_P}{T}_{}{}_{2,n}+\frac{2\mathrm{n\&pi;\&lambda;}}{M_W{C}_P\ln ({\mathrm{<figure-callout\; id="0"\; label="d"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">d</figure-callout>}}_0/d_i)}{\mathrm{<figure-callout\; id="0"\; label="T\; W"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">T</figure-callout>}}_W$

Tube side

$\frac{\&PartialD;{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="A20041003816200221.png,A20041003816200241.png"\; state="\{\{state\}\}">T</figure-callout>}}_{2,n}}{\&PartialD;t}=[-\frac{m_2}{{\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="A20041003816200221.png,A20041003816200241.png"\; state="\{\{state\}\}">M</figure-callout>}}_2\mathrm{\&Delta;}{x}_n}-\frac{\mathrm{n\&pi;}{d}_i{K}_i}{M_2{C}_{p2}}]{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="A20041003816200221.png,A20041003816200241.png"\; state="\{\{state\}\}">T</figure-callout>}}_{2,n}+\frac{\mathrm{n\&pi;}{d}_i{K}_i}{M_2{C}_{p2}}{T}_{\mathrm{Wi},n}+\frac{m_2}{{\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="A20041003816200221.png,A20041003816200241.png"\; state="\{\{state\}\}">M</figure-callout>}}_2\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="2"\; label="x\; n\; T"\; filenames="A20041003816200221.png,A20041003816200241.png"\; state="\{\{state\}\}">x</figure-callout>}}_n}{T}_{}{}_{2,\mathrm{<figure-callout\; id="1"\; label="n\; +"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">n</figure-callout>}+1}$

Above various in:

T _{1, n}, T _{2, n}, T _{W0, n}, T _{Wi, n}, represent the temperature of n section fluid 1, fluid 2, pipe outer wall and inside pipe wall respectively, n=1,2,3 ... N;

T _1，0＝T _1，in；

T _2，N+1＝T _2，in；

Δ x _nBe the length of n section, m

The discretize mechanism model of two pipe monoshells, four pipe monoshells and six pipe monoshell shell-and-tube heat exchangers can obtain by same procedure is discrete according to its mathematics mechanism model separately respectively.

2. steam generator discretization model

Tube side

$\frac{\&PartialD;{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">T</figure-callout>}}_{1,n}}{\&PartialD;t}=[-\frac{m_1}{{\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">M</figure-callout>}}_1\mathrm{\&Delta;}{x}_n}-\frac{\mathrm{n\&pi;}{d}_i{K}_i}{M_1{C}_{p1}}]{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">T</figure-callout>}}_{1,n}+\frac{\mathrm{n\&pi;}{d}_i{K}_i}{M_1{C}_{p1}}{T}_{\mathrm{Wi},n}+\frac{m_1}{{\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">M</figure-callout>}}_1\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="x\; n\; T"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">x</figure-callout>}}_n}{T}_{}{}_{1,n-1}$

Inside pipe wall

$\frac{\&PartialD;T_{\mathrm{Wi},n}}{\&PartialD;t}=[-\frac{2\mathrm{n\&pi;\&lambda;}}{M_W{C}_P\ln ({\mathrm{<figure-callout\; id="0"\; label="d"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">d</figure-callout>}}_0/d_i)}-\frac{\mathrm{n\&pi;}{d}_i{K}_i}{M_W{C}_P}]T_{\mathrm{Wi},n}+\frac{\mathrm{n\&pi;}{d}_i{K}_i}{M_W{\mathrm{<figure-callout\; id="1"\; label="C\; P\; T"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">C</figure-callout>}}_P}{T}_{}{}_{1,n}+\frac{2\mathrm{n\&pi;\&lambda;}}{M_W{C}_P\ln ({\mathrm{<figure-callout\; id="0"\; label="d"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">d</figure-callout>}}_0/d_i)}{\mathrm{<figure-callout\; id="0"\; label="T\; W"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">T</figure-callout>}}_W$

The pipe outer wall

$\frac{\&PartialD;{\mathrm{<figure-callout\; id="0"\; label="T\; W"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">T</figure-callout>}}_W}{\&PartialD;t}=[-\frac{2\mathrm{n\&pi;\&lambda;}}{M_W{C}_P\ln ({\mathrm{<figure-callout\; id="0"\; label="d"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">d</figure-callout>}}_0/d_i)}-\frac{\mathrm{n\&pi;}{d}_0{K}_0}{M_W{C}_P}]{\mathrm{<figure-callout\; id="0"\; label="T\; W"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">T</figure-callout>}}_W+\frac{\mathrm{n\&pi;}{d}_0{K}_0}{M_W{C}_P}{T}_{\mathrm{Water}}+\frac{2\mathrm{n\&pi;\&lambda;}}{M_W{C}_P\ln ({\mathrm{<figure-callout\; id="0"\; label="d"\; filenames="A20041003816200231.png"\; state="\{\{state\}\}">d</figure-callout>}}_0/d_i)}{\mathrm{<figure-callout\; id="1"\; label="T\; W"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">T</figure-callout>}}_W$

Steam generating amount

$m_{\mathrm{Steamer}}=\frac{{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">m</figure-callout>}}_1{\mathrm{Cp}}_1({\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">T</figure-callout>}}_{1,\mathrm{in}}-{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="A20041003816200221.png"\; state="\{\{state\}\}">T</figure-callout>}}_{1,\mathrm{out}})}{H}$

Above various in:

T _{1, n},, T _{W0, n}, T _{Wi, n}, represent the temperature of n section fluid 1, pipe outer wall and inside pipe wall respectively, n=1,2,3 ... N;

T _1，0＝T _1，in；

T _1，out＝T _1，N

(3) set up the crude oil heat exchange network emulation system

1. set up separate unit Heat-Exchanger Simulation unit

For shell-and-tube heat exchanger, with the inlet flow rate of hot and cold two bursts of logistics, temperature as four inputs, utilize the heat interchanger discretization model to calculate the hot and cold stream temperature of heat exchanger exit, it and the flow of hot and cold stream are exported in the lump, set up the shell-and-tube heat exchanger simulation unit of four outputs of one four inputs, and a parameter is set in this simulation unit, therefore be used for being provided with the number of tube passes of heat interchanger, the heat interchanger of two pipe monoshells, four pipe monoshells and six pipe monoshells can be with this simulation unit emulation.For steam generator, boiling point with deoxygenated water under flow, temperature and the on-stream pressure of tube side hot fluid inlet is input, utilize the steam generator discretization model to calculate the steam production of tube side fluid at temperature, flow and the steam generator of outlet, as output, set up the steam generator simulation unit of one three input three outputs.Utilize the design data of heat exchanger network, by emulation experiment, the adjustment model partial parameters makes two realistic models accurate.

2. set up the crude oil heat exchange network emulation system

According to the framed structure of actual crude oil heat exchange network, utilize the simulation unit of aforementioned tube shell heat exchanger and steam generator, connect and compose the emulation system of crude oil heat exchange network, concatenate rule is as follows:

(1) in the heat exchanger network, for logistics k, upstream heat interchanger p and the downstream heat exchanger q that flows through adjacent, then q platform heat interchanger logistics k inlet temperature equals p platform heat interchanger logistics k outlet temperature, that is: T _{K, i, q}=T _{K, 0, p}If logistics k does not shunt between heat interchanger or converges, then q platform heat interchanger logistics k flow equals p platform heat interchanger logistics k flow, that is: m _{K, i, q}=m _{K, 0, p}

(2) in the heat exchanger network,, after flowing out, heat interchanger p is divided into two-way for logistics k, one road inflow heat exchanger q wherein, and another road inflow heat exchanger r, then the inflow temperature of logistics k is the outflow temperature of logistics k among the heat interchanger p, that is: T among heat interchanger q, the r _{K, i, q}=T _{K, i, r}=T _{K, 0, p}The flow sum of logistics k equals the flow of logistics k among the heat interchanger p, that is: m among heat interchanger q, the r _{K, i, q}+ m _{K, i, r}=m _{K, 0, p}(3) in the heat exchanger network, two-way logistics k of the same race merges into one the tunnel respectively after heat interchanger p and heat interchanger q flow out, inflow heat exchanger r again, and then the inflow temperature of logistics k is the weighted mean value that logistics k flows out temperature among heat interchanger p, the q among the heat interchanger r, that is: $T_{k,i,r}=\frac{T_{k,0,p}{m}_{k,0,p}+T_{k,0,q}{m}_{k,0,q}}{m_{k,0,p}+m_{k,0,q}};$ Among the heat interchanger r flow of logistics k be among heat interchanger p, the q logistics k flow and, i.e. m _{K, i, r}=m _{K, 0, p}+ m _{K, 0, q}

(4) determine the operation pinch point position and the operation pinch point temperature difference of crude oil heat exchange network

Supposing has N platform heat interchanger in the crude oil heat exchange network according to the pinch technology design, and its operation pinch point temperature difference dynamic mathematical models are:

Δ T _Min=MIN (Δ T ₁, Δ T ₂..., Δ T _i..., Δ T _N)), Δ T wherein _iIt is the heat transfer temperature difference that participates in the hot and cold logistics of heat exchange in the i platform heat interchanger.

According to top minimum temperature difference dynamic mathematical models, the crude oil heat exchange network emulation system that utilization is built, this heat exchanger network is carried out dynamic simulation to be calculated, can obtain the dynamic change of heat exchanger network minimum temperature difference, hot public work and cold public work, and then definite operation pinch point temperature difference and corresponding minimum public work consumption thereof.Because the public work consumption that calculates according to the folder point design method is a Min., thereby no matter be hot public work and cold public work, still total public work, when folder point difference variation, the minimum public work of the actual public work in production scene during always greater than design.If can make actual public work to greatest extent near minimum public work by control heat exchanger network minimum temperature difference, then can reduce the operation cost of heat exchanger network.Therefore, the present invention proposes the operation pinch point control strategy, reduces the actual public work of heat exchanger network by the indirect control heat exchanger network folder point temperature difference.

(5) heat exchanger network operation pinch point controlling schemes design

According to a folder point principle, a folder point temperature difference reduces then that public work reduces, and therefore for reducing public work, needs to reduce a folder point minimum temperature difference.But the reduction minimum temperature difference, required heat interchanging area (cost of equipment) will increase, thereby there is an optimum value in minimum temperature difference.Heat exchanger network is in operational process, because the structure of heat exchanger network is determined, the cost of equipment of heat exchanger network is also just fixing, if can control the minimum temperature difference of heat exchanger network, make it to remain on design load and do not change, also will make the actual public work of network to greatest extent near minimum public work with the interference of operating conditions.The present invention is by the temperature of the control folder point cold and hot logistics in place, control the operation pinch point temperature difference of heat exchanger network indirectly, make it to maintain optimum value, to reach the purpose that reduces public work, it is the operation pinch point control strategy, controlling schemes is as follows: ask the result of calculation according to the dynamic mechanism model of heat exchanger network, utilize the minimum temperature difference dynamic mathematical models: Δ T _Min=MIN (Δ T ₁, Δ T ₂..., Δ T _i..., Δ T _N)), asking the minimum temperature difference of calculating in the crude oil heat exchange network is (T _{H, i}-T _{C, i}), the cold and hot logistics of operation pinch point correspondence is T respectively _{C, i}, T _{H, i}, thereby can be with cold flow at T _{C, i}Certain heat interchanger of upstream (not necessarily adjacent) is set up bypass, and bypass can be added on this cold flow, also can be added on the hot-fluid with the cold flow heat exchange, and bypass can stride across a heat interchanger also can stride across many heat interchanger; Simultaneously with hot-fluid at T _{H, i}Certain heat interchanger of upstream (not necessarily adjacent) is also set up bypass, and bypass can be added on this hot-fluid, also can be added on the cold flow with this hot-fluid heat exchange, and same, bypass can stride across a heat interchanger also can stride across many heat interchanger.Control T by the flow of regulating added bypass like this _{H, i}, T _{C, i}Thereby the some temperature difference (T is pressed from both sides in control operation indirectly _{H, i}-T _{C, i}), make it not to be subjected to operation to be disturbed and remaining on the optimum value, thereby the crude oil heat exchange network of actual motion is satisfied in the whole temperature of logistics heat exchange on the basis of technological requirement to greatest extent near design point, improve the heat recovery amount as much as possible, reduce public work, realize energy-saving and cost-reducing.

Beneficial effect of the present invention is: according to the pinch technology principle, by in heat exchanger network, setting up bypass and controlling the method for bypass flow, control the medium temperature of some logistics in the actual heat exchanger network, then control the operation pinch point temperature difference in the actual heat exchanger network, make heat exchanger network in operational process, be in the state of minimum public work consumption all the time, reach energy saving purposes.

As seen, compare with the control technology of existing heat exchanger network, the present invention not only controls the temperature eventually that participates in the heat exchange logistics, but also control the medium temperature of some heat exchange logistics, the potential temperature coupling of heat exchange logistics can be changed with the change of practical operation condition, thereby make that the heat transferred at whole heat exchange networking is at one's best all the time.

Above embodiment only is used to illustrate the present invention, but not is used to limit the present invention.

Claims (10)

1, a kind of control method of crude oil heat exchange network operation pinch point is characterized in that, the heat exchanging device carries out modelling by mechanism, thereby dynamically draws the outlet temperature variable quantity of each heat interchanger in the crude oil heat exchange network;

If establish N platform heat interchanger is arranged in the crude oil heat exchange network, then its operation pinch point minimum temperature difference dynamic mathematical models are: Δ T _Min=MIN (Δ T ₁, Δ T ₂..., Δ T _i..., Δ T _N)), Δ T wherein _iIt is the heat transfer temperature difference that participates in the hot and cold logistics of heat exchange in the i platform heat interchanger;

According to resulting result behind the described modelling by mechanism, utilize described operation pinch point minimum temperature difference dynamic mathematical models, draw the minimum temperature difference in the crude oil heat exchange network and the cold and hot logistics of operation pinch point correspondence;

Heat interchanger is set up bypass, thereby the some temperature difference is pressed from both sides in control operation indirectly, makes it to remain on the optimum value, and then draws minimum public work consumption.

2, the control method of crude oil heat exchange network operation pinch point as claimed in claim 1 is characterized in that, the minimum temperature difference in the described crude oil heat exchange network is (T _{H, i}-T _{C, i}), the cold and hot logistics of described operation pinch point correspondence is respectively T _{C, i}, T _{H, i}

With cold flow at T _{C, i}Certain heat interchanger of upstream is set up bypass, and bypass can be added on this cold flow, also can be added on the hot-fluid with the cold flow heat exchange, and bypass can stride across a heat interchanger also can stride across many heat interchanger; Simultaneously with hot-fluid at T _{H, i}Certain heat interchanger of upstream is also set up bypass, and bypass can be added on this hot-fluid, also can be added on the cold flow with this hot-fluid heat exchange, and same, bypass can stride across a heat interchanger also can stride across many heat interchanger;

Control T by the flow of regulating added bypass _{H, i}, T _{C, i}Thereby the some temperature difference (T is pressed from both sides in control operation indirectly _{H, i}-T _{C, i}), make it not to be subjected to operation to be disturbed and remain on the optimum value.

3, the control method of crude oil heat exchange network operation pinch point as claimed in claim 1 is characterized in that, the operation pinch point position is determined by temperature enthalpy chart; Wherein, when hot complex curve moves, must make corresponding mobile to cold flow curve corresponding in each heat interchanger in the cold complex curve.

4, the control method of crude oil heat exchange network operation pinch point as claimed in claim 1, it is characterized in that, describedly set up bypass and be meant: set up bypass by the appropriate location in heat exchanger network, and installation operation valve, come control operation folder point place cold by the control bypass flow, the temperature of hot logistics, and then the control operation folder point temperature difference, make it in the device operational process, to maintain near the design load all the time, control the variation range of heat exchanger network operation pinch point minimum temperature difference in real time, realize the optimization of operation pinch point, thereby reduce the public work consumption of heat exchanger network to greatest extent.

5. method according to claim 1 is characterized in that, described heat interchanger is a shell-and-tube heat exchanger; Described shell-and-tube heat exchanger mechanism model comprises: analyzed for the fluid infinitesimal, write the dynamic mathematical models of shell side, tube side, pipe outer wall, inside pipe wall according to heat mobile equilibrium equation row.

6. method according to claim 1 is characterized in that, described heat interchanger is a steam generator; Described steam generator mechanism model comprises: analyzed for the fluid infinitesimal, write the dynamic mathematical models of tube side, inside pipe wall, pipe outer wall, steam generating amount according to heat mobile equilibrium equation row.

7. method according to claim 5, it is characterized in that, described shell-and-tube heat exchanger is set up discretization model, that is: the heat-exchanger model as distributed parameter model is carried out the segmentation discretize, being considered as lumped parameter model on each section handles, simultaneous obtains the lumped parameter model of each section again, finishes the calculating of solving model then, comprises the discretize mathematical model of shell side, tube side, pipe outer wall, inside pipe wall.

8. method according to claim 6, it is characterized in that, described steam generator is set up discretization model, that is: the model steam generator as distributed parameter model is carried out the segmentation discretize, being considered as lumped parameter model on each section handles, simultaneous obtains the lumped parameter model of each section again, finishes the calculating of solving model then, comprises the discretize mathematical model of tube side, pipe outer wall, inside pipe wall, steam generating amount.

9. method according to claim 1 and 2 is characterized in that, described operation pinch point minimum temperature difference is meant: after the heat exchanger network that utilizes pinch technology to design puts into operation, and the minimum value of the hot-fluid and the actual temperature difference of cold flow in the heat exchanger network.

10. method according to claim 1 and 2, it is characterized in that, described operation pinch point is meant: after the heat exchanger network that utilizes pinch technology to design put into operation, the position that occurs the minimum value of the hot-fluid and the cold flow temperature difference in the actual heat exchanger network was exactly an operation pinch point.

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