CN103937957B - Pulse-combustion formula furnace pressure feedforward optimizing and controlling method - Google Patents

Abstract

The invention provides a kind of pulse-combustion formula furnace pressure feedforward optimizing and controlling method, comprise step: step I: when heating steel billet, the usage quantity of the combustion air of accumulative current combustion mouth, PID setter is exported and compensates; Step II: when stack gases temperature is greater than 650 DEG C, carries out disturbance compensation to the warm braw amount of supporting by the arm of supporting by the arm warm air of lowering the temperature for process furnace; Step II I: when process furnace charging oven door opening, close time, by PID controller lock, and respectively PID setter output valve is increased, reduces compensation.The present invention has beneficial effect: (1) reduces furnace pressure control lag, increases control accuracy; (2) warm braw amount will be supported by the arm through row disturbance compensation, the furnace pressure influence of fluctuations doping warm braw and bring can be eliminated; (3) the furnace pressure influence of fluctuations that stove door switch causes is eliminated; (4) reduce fuel consumption, strand oxidization burning loss, improve fuel availability and strand heating quality, strand heating quality is reliable and stable.

Description

Pulse-combustion formula furnace pressure feedforward optimizing and controlling method

Technical field

The invention belongs to metallurgical Controlling Technology technical field, especially large-scale heater for rolling steel heating strand Combustion System technique, particularly, relates to pulse-combustion formula furnace pressure feedforward optimizing and controlling method.

Background technology

General heater for rolling steel furnace pressure controls to adopt traditional proportional integral derivative controller (PID setter) to control, and this control mode is classic feedback controling mode.Namely by furnace pressure transmitters sense furnace pressure, again detected pressure value is converted into current signal, this signal is sent in PID setter, compare with furnace pressure set(ting)value there, and according to comparing obtained difference, PID setter provides furnace pressure modified value signal, as flue shutter steady arm setting point, drive actuating mechanism controls flue shutter aperture size, and then also just control furnace pressure.

In traditional furnace pressure negative feedback control, when controll plant (furnace pressure) effect of being disturbed, when controlled volume departs from set-point, PID setter just can work, and changes the output of object, thus the impact of compensating disturbance.So this traditional negative feedback control has larger hysteresis quality, the actual detected value of furnace pressure is fluctuated larger.The phenomenon that the generation of process furnace is inhaled cold wind or burned with anger, increases oxidization burning loss and gas quantity.Therefore be necessary to introduce burner hearth feedforward Optimized-control Technique, stablize furnace pressure.

Summary of the invention

For defect of the prior art, the object of this invention is to provide a kind of pulse-combustion formula furnace pressure feedforward optimizing and controlling method.

According to pulse-combustion formula furnace pressure feedforward optimizing and controlling method provided by the invention, comprise the steps:

Step I: when heating steel billet, the usage quantity of the combustion air of accumulative current combustion mouth, exports PID setter and compensates, to reduce furnace pressure control lag.

Preferably, in step I, according to following formula, the output of PID setter is compensated:

$u(k+i)=\frac{{\mathrm{\Σ}}_{n=1}^N{K}_2{A}_n{B}_n\left(i\right)}{A},i=\mathrm{0,1}$

Wherein, u (k+i) is the output of PID setter, K ₂for combustion air flow penalty coefficient, A _nbe the n-th burner air flow quantity, A is whole burner air flow quantity summations, B _ni () is for basis funciton is at t=iT _stime value, wherein, t is the time, T _sfor the sampling period, i is the on off state of the n-th burner, and wherein, i=1 is that burner is opened, and i=0 is that burner is closed, and N is the quantity of whole burner.

Preferably, also comprise the steps:

Step II: when stack gases temperature is greater than threshold value, carries out disturbance compensation to the warm braw amount of supporting by the arm of supporting by the arm warm air of lowering the temperature for process furnace, eliminates the furnace pressure influence of fluctuations doping warm braw and bring.

Preferably, described temperature threshold is 650 DEG C.

Preferably, in Step II, compensate supporting by the arm the output of warm braw amount according to following formula:

$g(k+i)=\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{K}_1{T}_n$

Wherein, g (k+i) exports for supporting by the arm warm braw amount, K ₁for supporting by the arm warm air flow penalty coefficient, T _nbe that the n-th burner supports by the arm warm braw flow, N is the quantity of whole burner.

Preferably, also comprise the steps:

Step II I: when process furnace charging oven door opening, by PID controller lock, and increase compensation is carried out to PID setter output valve; When process furnace charging fire door is closed, by PID controller lock, and reduction compensation is carried out to PID setter output valve.

Compared with prior art, the present invention has following beneficial effect:

(1) reduce furnace pressure control lag, increase control accuracy;

(2) warm braw amount will be supported by the arm through row disturbance compensation, the furnace pressure influence of fluctuations doping warm braw and bring can be eliminated;

(3) the furnace pressure influence of fluctuations that stove door switch causes is eliminated;

(4) reduce fuel consumption, strand oxidization burning loss, improve fuel availability and strand heating quality, strand heating quality is reliable and stable.

Accompanying drawing explanation

By reading the detailed description done non-limiting example with reference to the following drawings, other features, objects and advantages of the present invention will become more obvious:

Fig. 1 is principle schematic of the present invention.

In figure:

B ₁represent No. 1 burner;

B ₂₀represent No. 20 burners;

A ₁represent No. 1 burner air flow quantity;

A ₂₀represent No. 20 burner air flow quantitys;

A represents the air total flux of whole burner;

Δ MV represents system feedforward control amount;

A/M expression signal converting unit.

Embodiment

Below in conjunction with specific embodiment, the present invention is described in detail.Following examples will contribute to those skilled in the art and understand the present invention further, but not limit the present invention in any form.It should be pointed out that to those skilled in the art, without departing from the inventive concept of the premise, some distortion and improvement can also be made.These all belong to protection scope of the present invention.

Pulse-combustion formula furnace pressure provided by the invention feedforward optimizing and controlling method, comprising: combustion air flow feed forward control method, support by the arm warm air flow feed forward control method, fire door compensating control method.

Combustion air flow feed forward control method

When heating steel billet, because the combustion air flow entering process furnace is comparatively large, the load variations of heating is very fast, therefore furnace pressure can produce fluctuation, now adopt feedforward optimal control, i.e. the usage quantity of the combustion air of accumulative current combustion mouth, PID setter is exported and compensates.Furnace pressure control lag can be reduced, increase control accuracy.

The mathematic(al) representation of this method is:

$u(k+i)=\frac{{\mathrm{\Σ}}_{n=1}^N{K}_2{A}_n{B}_n\left(i\right)}{A},i=\mathrm{0,1}$

Wherein u (k+i) is the output of PID setter, K ₂for combustion air flow penalty coefficient, A _nbe the n-th burner air flow quantity, A is whole burner air flow quantity summations, B _ni () is for basis funciton is at t=iT _stime value, wherein, t is the time, T _sfor the sampling period, i is the on off state of the n-th burner, and wherein, i=1 is that burner is opened, and i=0 is that burner is closed, and N is the quantity of whole burner.

Support by the arm warm air flow feed forward control method

In order to protect air heat exchanger, when stack gases temperature is greater than 650 DEG C, process furnace additionally uses supports by the arm warm air mode and lowers the temperature.Due to doping of warm braw, furnace pressure can produce fluctuation, now adopts feedforward optimal control, will support by the arm warm braw amount and carry out disturbance compensation, and can eliminate the furnace pressure influence of fluctuations doping warm braw and bring.

The mathematic(al) representation of this method is:

$g(k+i)=\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{K}_1{T}_n$

Wherein g (k+i) exports for supporting by the arm warm braw amount, K ₁for supporting by the arm warm air flow penalty coefficient, T _nbe that the n-th burner supports by the arm warm braw flow, N is the quantity of whole burner.

Fire door compensating control method

When process furnace charging is door opened, because loading side is near flue, has large quantity of air and enter, in order to prevent furnace pressure to fluctuate, feedforward optimal control can be adopted, by PID controller lock, and increase compensation is carried out to output valve.When process furnace discharging door is opened, in order to prevent large quantity of air from entering in stove, causing the oxidation of steel billet, feedforward optimal control can be adopted, by PID controller locking, and reduction compensation is carried out to output valve.Eliminate the furnace pressure influence of fluctuations that stove door switch causes, improve the precision controlled.

Prove through production practice, this furnace pressure feed forward control techniques provided by the invention reduces fuel consumption, strand oxidization burning loss, improves fuel availability and strand heating quality, make heavy slab process furnace gas unit consumption drop to 1.09GJ/t, strand heating quality is reliable and stable.

Above specific embodiments of the invention are described.It is to be appreciated that the present invention is not limited to above-mentioned particular implementation, those skilled in the art can make various distortion or amendment within the scope of the claims, and this does not affect flesh and blood of the present invention.

Claims (5)

1. a pulse-combustion formula furnace pressure feedforward optimizing and controlling method, is characterized in that, comprise the steps:

Step I: when heating steel billet, the usage quantity of the combustion air of accumulative current combustion mouth, exports PID setter and compensates, to reduce furnace pressure control lag;

In step I, according to following formula, the output of PID setter is compensated:

$u(k+i)=\frac{{\mathrm{\Σ}}_{n=1}^N{K}_2{A}_n{B}_n\left(i\right)}{A},i=\mathrm{0,1}$

Wherein, u (k+i) is the output of PID setter, K ₂for combustion air flow penalty coefficient, A _nbe the n-th burner air flow quantity, A is whole burner air flow quantity summations, B _ni () is for basis funciton is at t=iT _stime value, wherein, t is the time, T _sfor the sampling period, i is the on off state of the n-th burner, and wherein, i=1 is that burner is opened, and i=0 is that burner is closed, and N is the quantity of whole burner.

2. pulse-combustion formula furnace pressure feedforward optimizing and controlling method according to claim 1, is characterized in that, also comprise the steps:

Step II: when stack gases temperature is greater than temperature threshold, carries out disturbance compensation to the warm braw amount of supporting by the arm of supporting by the arm warm air of lowering the temperature for process furnace, eliminates the furnace pressure influence of fluctuations doping warm braw and bring.

3. pulse-combustion formula furnace pressure feedforward optimizing and controlling method according to claim 2, is characterized in that, in Step II, compensates supporting by the arm the output of warm braw amount according to following formula:

$g(k+i)=\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{K}_1{T}_n$

Wherein, g (k+i) exports for supporting by the arm warm braw amount, K ₁for supporting by the arm warm air flow penalty coefficient, T _nbe that the n-th burner supports by the arm warm braw flow, N is the quantity of whole burner.

4. pulse-combustion formula furnace pressure feedforward optimizing and controlling method according to claim 2, it is characterized in that, described temperature threshold is 650 DEG C.

5. pulse-combustion formula furnace pressure feedforward optimizing and controlling method according to claim 1, is characterized in that, also comprise the steps:

Step II I: when process furnace charging oven door opening, by PID controller lock, and increase compensation is carried out to PID setter output valve; When process furnace charging fire door is closed, by PID controller lock, and reduction compensation is carried out to PID setter output valve.