CN103937957A - Pulse combustion type furnace hearth pressure feedforward optimization control method - Google Patents

Abstract

The present invention provides a pulse combustion type furnace hearth pressure feedforward optimization control method, which comprises: 1, when a steel billet is heated, accumulating combustion-supporting air consumption of a current combustion nozzle, and carrying out compensation on PID adjuster output; 2, when the flue waste gas temperature is more than 650 DEG C, carrying out disturbance compensation on the warm mixed wind amount of warm mixed air for heating furnace cooling; and 3, when the heating furnace material feeding door is opened or closed, locking the PID adjuster, and respectively carrying out increase compensation and decrease compensation on the PID adjuster. The pulse combustion type furnace hearth pressure feedforward optimization control method has the following beneficial effects that: (1) the furnace pressure adjustment lag is reduced, and the control accuracy is increased; (2) the warm mixed wind amount is subjected to disturbance compensation so as to eliminate the furnace pressure fluctuation influence caused by warm wind mixing; (3) the furnace pressure fluctuation influence caused by opening/closing of the furnace door is eliminated; and (4) the fuel consumption and the casting billet oxidation combustion loss are reduced, the fuel utilization rate and the casting billet heating quality are increased, and the casting billet heating quality is stable and reliable.

Description

Pulse-combustion formula furnace pressure feedforward optimizing and controlling method

Technical field

The invention belongs to the metallurgical Technology field of controlling, technique is controlled in the burning of especially large-scale heater for rolling steel heating strand, particularly, relates to pulse-combustion formula furnace pressure feedforward optimizing and controlling method.

Background technology

General heater for rolling steel furnace pressure control adopts traditional proportional integral derivative controller (PID setter) to control, and this control mode is classic feedback controling mode.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 the difference relatively obtaining, 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 controlled 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, make the actual detected value fluctuation of furnace pressure larger.The phenomenon that the generation of process furnace is inhaled cold wind or burned with anger, has increased 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: in the time of heating steel billet, the usage quantity of the combustion air of the current burner of accumulative total, to PID setter, output compensates, to reduce furnace pressure control lag.

Preferably, in step I, according to following formula, to PID setter, output compensates:

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

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

Preferably, also comprise the steps:

Step II: in the time that stack gases temperature is greater than threshold value, to carrying out disturbance compensation for the warm braw amount of supporting by the arm of supporting by the arm warm air of process furnace cooling, eliminates and dope the furnace pressure influence of fluctuations that warm braw brings.

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) is for supporting by the arm the output of warm braw amount, K ₁for supporting by the arm warm air flow penalty coefficient, T _nbe that n burner supported by the arm warm braw flow, the quantity that N is whole burners.

Preferably, also comprise the steps:

Step II I: in the time of process furnace charging oven door opening, by PID controller lock, and PID setter output valve is increased to compensation; In the time that process furnace charging fire door is closed, by PID controller lock, and PID setter output valve is reduced to compensation.

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

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

(2) will support by the arm warm braw amount through row disturbance compensation, and can eliminate and dope the furnace pressure influence of fluctuations that warm braw brings;

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

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

Brief description of the drawings

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

Fig. 1 is principle schematic of the present invention.

In figure:

B ₁represent burner No. 1;

B ₂₀represent burner No. 20;

A ₁represent burner air flow quantity No. 1;

A ₂₀represent burner air flow quantity No. 20;

A represents the air total flux of whole burners;

Δ MV represents system feed forward 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 further to understand the present invention, but not limit in any form the present invention.It should be pointed out that to those skilled in the art, without departing from the inventive concept of the premise, can also make some distortion and improvement.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

In the time of heating steel billet, owing to entering, the combustion air flow of process furnace is larger, and the load variations of heating is very fast, therefore furnace pressure can produce fluctuation, now adopt feedforward optimal control, the usage quantity that adds up the combustion air of current burner, to PID setter, output compensates.Can reduce furnace pressure control lag, 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 n burner air flow quantity, A is whole burner air flow quantity summations, B _n(i) be that basis funciton is at t=iT _stime value, wherein, t is the time, T _sfor the sampling period, the on off state that i is n burner, wherein, i=1 is that burner is opened, i=0 is that burner is closed, the quantity that N is whole burners.

Support by the arm warm air flow feed forward control method

In order to protect air heat exchanger, in the time that stack gases temperature is greater than 650 DEG C, process furnace has also adopted 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, can eliminate and dope the furnace pressure influence of fluctuations that warm braw brings.

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) is for supporting by the arm the output of warm braw amount, K ₁for supporting by the arm warm air flow penalty coefficient, T _nbe that n burner supported by the arm warm braw flow, the quantity that N is whole burners.

Fire door compensating control method

Feed when door opened when process furnace, because loading side is near flue, has large quantity of air and enter, in order to prevent furnace pressure fluctuation, can adopt feedforward optimal control, by PID controller lock, and output valve is increased to compensation.In the time that process furnace discharging door is opened, in order to prevent that large quantity of air from entering in stove, cause the oxidation of steel billet, can adopt feedforward optimal control, by PID controller lock, and output valve is reduced to compensation.Eliminate the furnace pressure influence of fluctuations that stove door switch causes, improve the precision of controlling.

Prove through production practice, this furnace pressure feed forward control Techniques For Reducing provided by the invention fuel consumption, strand oxidization burning loss, improved 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 will be appreciated that, the present invention is not limited to above-mentioned specific implementations, and 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 (6)

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

Step I: in the time of heating steel billet, the usage quantity of the combustion air of the current burner of accumulative total, to PID setter, output compensates, to reduce furnace pressure control lag.

2. pulse-combustion formula furnace pressure feedforward optimizing and controlling method according to claim 1, is characterized in that, in step I, according to following formula, to PID setter, output compensates:

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

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

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

Step II: in the time that stack gases temperature is greater than temperature threshold, to carrying out disturbance compensation for the warm braw amount of supporting by the arm of supporting by the arm warm air of process furnace cooling, eliminates and dope the furnace pressure influence of fluctuations that warm braw brings.

4. pulse-combustion formula furnace pressure feedforward optimizing and controlling method according to claim 3, 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) is for supporting by the arm the output of warm braw amount, K ₁for supporting by the arm warm air flow penalty coefficient, T _nbe that n burner supported by the arm warm braw flow, the quantity that N is whole burners.

5. pulse-combustion formula furnace pressure feedforward optimizing and controlling method according to claim 3, is characterized in that, described temperature threshold is 650 DEG C.

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

Step II I: in the time of process furnace charging oven door opening, by PID controller lock, and PID setter output valve is increased to compensation; In the time that process furnace charging fire door is closed, by PID controller lock, and PID setter output valve is reduced to compensation.