CN101929736B - Temperature control method for heating furnace based on heat accumulating type nozzle - Google Patents
Temperature control method for heating furnace based on heat accumulating type nozzle Download PDFInfo
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- CN101929736B CN101929736B CN2009100538441A CN200910053844A CN101929736B CN 101929736 B CN101929736 B CN 101929736B CN 2009100538441 A CN2009100538441 A CN 2009100538441A CN 200910053844 A CN200910053844 A CN 200910053844A CN 101929736 B CN101929736 B CN 101929736B
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Abstract
The invention discloses a temperature control method for a heating furnace based on a heat accumulating type nozzle. When the flow of air and gas is larger than that of a balance point, a continuous simulation control mode is adopted for controlling; when the flow of air and gas is smaller than that of the balance point, the adopted continuous simulation control is stopped; burning and stopping controls are carried out on partial nozzles in the heating furnace; the heating furnace is roughly adjusted to the temperature 30 DEG C lower than a set temperature, heating is carried out by reutilizing the continuous simulation control mode to the set temperature while the gas flow starts to be increased based on PID adjustment, and a stable feedback control state is realized. The method provided by the invention can adapt to the temperature control requirements of the heating furnace based on the heat accumulating type nozzle, utilize an organic DCS system to perform digital discrete control programming, make full use of the original system, and save investment, thus having good application and promotion prospects.
Description
Technical field
The invention belongs to manufacture field, relate in particular to a kind of temperature control method for heating furnace based on heat-accumulating burner.
Background technology
Hot-blast stove is in the cold-rolling process flow process band steel to be carried out heated type to dry one of important procedure of handling; General hot-blast stove all adopts traditional radiant tube to heat; The control system is conventional PID (Proportional Integral Derivative Controller; Proportional integral derivative controller is called for short PID) the closed-loop simulation continuous control system, through regulating the flow-control furnace temperature of burning gases.Heat-accumulating burner has well energy-saving and cost-reducing characteristic, in hot-blast furnace transformation, widely apply, but owing to two kinds of burner combustion characteristics are different, its control system just can not indiscriminately imitate conventional closed-loop simulation continuous control mode simply, needs to do corresponding consideration.
In the tradition hot-blast furnace transformation; When using heat-accumulating burner to substitute former traditional type burner, the original conventional PID closed-loop simulation control system of utilizing is also arranged, but it is only applicable to the little occasion of variations in temperature; This moment, gas flow can be not too small, can not cause that EGT crosses problems such as height.If be applied in the occasion that variations in temperature is big, pace of change is higher (as continuously to the heating of different size band steel); The gas flow wide variation will appear; EGT can sharply raise because of the heat-accumulating burner characteristic when gas flow is too small; Cause original furnace temperature simulation continuous control system can not stablize and accurate control furnace temperature, so essential other method that adopts.If do not consider to invest the problem of utilizing with original system; General all is to adopt the digital discrete control system that is suitable for heat-accumulating burner to substitute original system; Will cause like this that investment strengthens, original system is scrapped and a series of problems such as new system debug risk increase, greatly restrict security and the economy transformed.
The heat-accumulating burner operation principle: heat storage type combustion mainly is made up of burner, heat storage, switched system and control system.Two burners use in pairs, and work periodicity interactive combustion-stop burning and move.
As shown in Figure 1, when burner A burnt, burner B then stopped to burn, and as the high-temp waste gas discharge-channel.In A when burning,, air at first obtains preheating through the heat storage of A, then with get into A in coal gas mix and burn.And also having reduced self temperature after air and the heat exchange of A heat storage, high-temp waste gas is combustion gas after burner B is by its heat energy of heat storage absorption of B.
The transfer valve action gets into next cycle, and burner B begins to burn.
When burner B burnt, original burner A then stopped to burn also conversely as the high-temp waste gas discharge-channel.In B when burning,, air obtains preheating through the heat storage of B, then with get into B in coal gas mix and burn.And also having reduced self temperature after air and the heat exchange of B heat storage, high-temp waste gas is combustion gas after burner A is by its heat energy of heat storage absorption of A.So go round and begin again and carry out periodicity interactive combustion-stop and burn operation.
Because the heat storage surface area reaches 800-1000m
2/ m
3, commutating period, the toxic emission Controllable Temperature realized limit waste heat recovery built in very low level, cuts down the consumption of energy between 10s-30s; Also have effects such as the temperature uniformity of improvement, raising heating intensity simultaneously.
Though regenerative combustion technology is comparative maturity, at home and abroad, the temperature control mode based on heat-accumulating burner is but had nothing in common with each other, effect is not very good yet.Because heat-accumulating burner need commutate and exhaust gas utilization, so with the traditional type burner very big difference is arranged, hot-blast stove adopts in addition is that the mode of warm-up cycle wind is come the heating tape steel, and these are all given to control based on the temperature of heat-accumulating burner and bring difficulty.Therefore; Employing can't realize stable control to temperature, and very easily cause EGT too high based on the existing PID control model of traditional type burner; Not only have a strong impact on the service life and the precision of equipment such as reversal valve; Also often cause cigarette temperature control system protection action, cut off main coal gas, influence ordinary production.
Therefore, if former temperature control system is not carried out corresponding improvement, just can't stablize based on the Control for Kiln Temperature of heat-accumulating burner, precision is not high yet.
Characteristic through heat-accumulating burner and traditional burner compares, and, can find out that heat-accumulating burner is different fully with the characteristic of traditional burner like Fig. 2, shown in Figure 3.
In the tradition burner combustion, EGT T and air, gas flow V are proportional relationships, and best combustion space-time coal guarantees making full use of of the energy than being (empty coal is than fixing) that automatic constant is regulated with this simultaneously.And in the heat-accumulating burner burning; EGT T and air, gas flow V are inversely prroportional relationships; When temperature control system needs V significantly to reduce, will cause the fast rise of T, when EGT acquires a certain degree, just can not realize temperature control by reducing V more like this.Otherwise EGT will exceed limit value to be caused the defencive function action and closes main coal gas.So, must confirm an equalization point, should not control temperature according to the empty coal of tradition than constant adjusting air, gas flow again in the left side of this equalization point (dash area in left side shown in the dotted line), must take alternate manner.
Because These characteristics when traditional burner stove is transformed, if continue to use original control mode fully, can cause the Control for Kiln Temperature system mode unstable.Conclude and get up to mainly contain following two problems:
(1) when temperature is higher than setting value; Former temperature control system can reduce the input of air, gas flow V gradually, because the ins and outs of heat-accumulating burner, EGT can raise rapidly when V reduces to certain (as 40%) below the value; Surpass safety margin; Cause defencive function action, cut off main coal gas hot-blast stove is shut down that this 40% is an equalization point;
(2) when temperature reaches setting value, former temperature control system to the control action of heat-accumulating burner a little less than, can't realize fast and stable control, cause temperature to continue to rise stability of a system variation;
Summary of the invention
The purpose of this invention is to provide a kind of temperature control method for heating furnace based on heat-accumulating burner; It is incompatible to solve the original system Control for Kiln Temperature of using heat-accumulating burner to bring; And the big problem of digital discrete control system investment, consideration simultaneously reduces the action frequency of coal gas open and close valve, makes full use of grand master pattern quasi-continuous control systemic-function; Develop simple and easy Digital Discrete and control system, organically combine both characteristics and realize furnace temp control based on the heat-accumulating burner transformation.
Technical conceive of the present invention is following: utilize heat-accumulating burner EGT T and air, the inversely proportional relation of gas flow V; And EGT T can too high these characteristics under greater than the situation of certain flow V; (so-called " equalization point " is meant through testing and confirms a flow value a selected flow equilibrium point; EGT may significantly raise when less than it, causes the main coal gas of system protection action cut-out; EGT can be not too high when greater than it; System protection is failure to actuate, and can carry out normal temperature control), greater than this equalization point the time, use grand master pattern quasi-continuous control system; Less than this equalization point the time, adopt simple and easy Digital Discrete to control system; Promptly this moment, flow V no longer reduced, but carried out the adjusting of flow V through the discrete control mode (ON/OFF mode) of closing or connect some burners, at first furnace temperature was controlled certain value in advance; Make flow V can get back to big position once more, simulate continuous control then.Briefly; When being exactly big flow with the simulation continuous control of original system; Control with simple and easy Digital Discrete newly developed during low discharge; The Control for Kiln Temperature requirement that adapts to heat-accumulating burner is controlled in the mating die quasi-continuous again, has so not only made full use of original system, has also reduced the action frequency of coal gas open and close valve.
The objective of the invention is to realize like this: a kind of temperature control method for heating furnace based on heat-accumulating burner, air, gas flow are controlled with simulation continuous control mode during greater than equalization point; When air, gas flow during less than equalization point; Stop to simulate continuous control, the part burner in each burner of stove carried out burning, stop control, at first with the furnace temperature coarse adjustment to below the design temperature 30 ℃; And then input simulation continuous control mode heats up to the design temperature direction; Gas flow is regulated according to PID and is begun to increase, and up to design temperature, gets into the stable state of FEEDBACK CONTROL at last.
Characteristic according to heat-accumulating burner; With gas flow V 40% as equalization point; Furnace temp control to based on heat-accumulating burner should take to simulate continuous control mode and the control strategy that the Digital Discrete control mode combines, and realizes temperature controlled reliable and stable.
The A mode, the simulation continuous control
When air, gas flow during greater than equalization point, owing to can not have the too high problem of EGT, so still adopt the control valve of original system to simulate continuous control.When needs with flow further reduce could satisfied temperature control when requiring, the A mode is by " blockades ", flow is fixed on equalization point (40%) and locates, commentaries on classics is controlled by following B mode.Certainly the A mode need be optimized and revised the control parameter again according to the characteristic of heat-accumulating burner, to realize the stable control in this zone.
The B mode, Digital Discrete control
When needs air, gas flow are controlled, adopt Digital Discrete control in less than equalization point.
Discrete control is exactly that the part burner in each burner of stove is carried out burning, stop control.At first through stop burning the part burner with the furnace temperature coarse adjustment to 30 ℃ (being preparatory controlling temperature) below the design temperature; And then input A mode heats up to the design temperature direction; Gas flow is regulated according to PID and is begun to increase, and up to design temperature, gets into the stable state of FEEDBACK CONTROL at last.
Furnace temperature adopt A, B dual mode still can't be accurate to ± 10 ℃ in the time, can carry out temperature closed loop through the mode of extraneous air dilution and regulate, to reach the purpose of meticulous control.
Preferably, described temperature control method for heating furnace based on heat-accumulating burner when EGT during near limit value, feeds extraneous air dilution cooling, to reach fast cooling control.
Preferably, described temperature control method for heating furnace based on heat-accumulating burner is when EGT surpasses heating furnace early warning temperature, with main gas cutting.
The present invention makes it compared with prior art owing to adopted above technical scheme, has the following advantages and good effect:
1) through the present invention, not only adapted to the Control for Kiln Temperature requirement of heat-accumulating burner, also can carry out Digital Discrete control programming by former DCS system, made full use of original system, saved investment.
2) through the present invention; Can alleviate largely and adopt the digital discrete control system be suitable for heat-accumulating burner to substitute that original system causes that investment strengthens, original system is scrapped and a series of problems such as new system debug risk increase; Reduce and transform risk; Make full use of original system, under the situation that satisfies the control requirement, reduce investment.
Description of drawings
Come the present invention is described further below in conjunction with accompanying drawing and specific embodiment.
Fig. 1 is the heat-accumulating burner schematic diagram;
Fig. 2 is the characteristic sketch map of traditional burner;
Fig. 3 is the characteristic sketch map of heat-accumulating burner;
Fig. 4 is temperature control sketch map.
Among the figure, heat storage 1.
The specific embodiment
Stove with eight burners is an example below, and control describes to Digital Discrete, and burner is numbered A1, A2, A3, A4, B1, B2, B3, B4, and is as shown in table 1.Five patterns (concrete data are only for reference, and different stoves need obtain corresponding data through test) are arranged, carry out burning, stop control, realize coarse adjustment temperature.The method that general consideration is taked to feedover realizes that whole temperature control overall strategy is controlled according to mode shown in the table 1.
The control of table 1 Digital Discrete
| Design temperature | 380℃ | 300℃ | 250℃ | Standby | Stop using |
| Control model | MODE1 | MODE2 | MODE3 | MODE4 | MODE5 |
| A1 | On | OFF | OFF | OFF | OFF |
| A2 | On | On | OFF | OFF | OFF |
| A3 | On | On | On | OFF | OFF |
| A4 | On | On | On | On | OFF |
| B1 | On | OFF | OFF | OFF | OFF |
| B2 | On | On | OFF | OFF | OFF |
| B3 | On | On | On | OFF | OFF |
| B4 | On | On | On | On | OFF |
When design temperature from hypermutation when low, can directly drop into the corresponding modes in the B mode; And change to when high from low when design temperature; For reducing the heating-up time, need at first drop into MODE1, and cooperate the A mode to carry out the full speed intensification; When actual temperature surpasses 20 ℃ of design temperatures; Drop into corresponding modes again and make temperature drop to the preparatory controlling temperature below the design temperature,, finally reach design temperature so that the A mode can continue to work.
As shown in Figure 4, typical temperature controlled processes.In first temperature-rise period, the A mode drops into, and the B mode is launched MODE1, whole burner combustions, and this moment, gas flow reached maximum (100%), heated up with maximum capacity.When reaching or during near design temperature, according to PID control, flow begins to descend; When being reduced to 40% left and right sides; If furnace temperature does not drop to setting value, then should not reduce flow again, but adopt certain the pattern closed portion burner in the B mode to carry out the temperature control coarse adjustment for preventing that EGT is too high.When coarse adjustment made temperature drop to uniform temperature (controlling temperature generally hangs down 30 ℃ than design temperature in advance), the A mode dropped into once more, and gas flow begins to carry out PID again regulates up to design temperature, gets into according to FEEDBACK CONTROL then and stablizes state of a control.
Furnace temperature is set at 250 ℃ when producing certain product, and this moment, the A mode was in stable closed-loop control state, and gas flow V is about 75%, and the corresponding pattern of B mode is MODE3, and promptly A1, A2 and B1, B2 are in the OFF state.When producing another kind of product, need furnace temperature to rise to 300 ℃.At this moment, the A mode is according to the closed-loop control characteristic, and gas flow V rises to 100% very soon, and the corresponding pattern of B mode becomes MODE1 simultaneously, and promptly A1, A2 and B1, B2 switch to the ON state, make all burner standard-sized sheets, cooperates the A mode to be rapidly heated.When near or when reaching 300 ℃, gas flow V progressively is decreased to 40% because the inertia of temperature; Actual temperature still can rise, and the B mode becomes MODE2 by MODE1 when reaching 320 ℃, and temperature progressively reduces; The A mode drops into once more and heats up after dropping to 270 ℃ of preparatory controlling temperatures; Gas flow V progressively increases, and furnace temperature is basicly stable near 290 ℃-310 ℃ when reaching 81% left and right sides, gets into to stablize state of a control.After this gas flow V will regulate according to variations such as strip speed, specifications, and its scope is generally at 50%-90%.When equipment occurring or control when unusual, EGT can rise, and when near limit value (400 ℃) (generally at 390 ℃), will feed extraneous air and dilute cooling, and EGT is lowered fast.In case this measure can't prevent EGT further to rise, then, EGT just cuts off main coal gas when arriving 400 ℃.
In sum; The present invention can be alleviated largely and adopts the digital discrete control system be suitable for heat-accumulating burner to substitute that original system causes that investment strengthens, original system is scrapped and a series of problems such as new system debug risk increase; Reduce and transform risk; Make full use of original system, under the situation that satisfies the control requirement, reduce investment, thereby possess good prospect for promotion and application.
Be noted that above enumerate be merely a specific embodiment of the present invention, obviously the invention is not restricted to above embodiment, many similar variations are arranged thereupon.If those skilled in the art all should belong to protection scope of the present invention from all distortion that content disclosed by the invention directly derives or associates.
Claims (3)
1. temperature control method for heating furnace based on heat-accumulating burner is characterized in that:
When the flow of air and the composite combustion gas of coal gas during, control with simulation continuous control mode greater than equalization point; When the flow of air and the composite combustion gas of coal gas during less than equalization point; Stop to simulate continuous control, the part burner in each burner of stove carried out burning, stop control, at first with the furnace temperature coarse adjustment to below the design temperature 30 ℃; And then input simulation continuous control mode heats up to the design temperature direction; Gas flow is regulated according to PID and is begun to increase, and up to design temperature, gets into the stable state of FEEDBACK CONTROL at last.
2. the temperature control method for heating furnace based on heat-accumulating burner as claimed in claim 1 is characterized in that: when EGT during near limit value, feed extraneous air dilution cooling, to reach fast cooling control.
3. the temperature control method for heating furnace based on heat-accumulating burner as claimed in claim 2 is characterized in that: when EGT surpasses heating furnace early warning temperature, with main gas cutting.
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| CN2009100538441A CN101929736B (en) | 2009-06-25 | 2009-06-25 | Temperature control method for heating furnace based on heat accumulating type nozzle |
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| CN102636039A (en) * | 2011-02-11 | 2012-08-15 | 宝山钢铁股份有限公司 | Small flow control method for regenerative furnace |
| CN103088191B (en) * | 2011-10-27 | 2015-09-30 | 宝钢工业炉工程技术有限公司 | The method for early warning of vertical continuous annealing furnace radiation pipe burner tip and interchanger thereof |
| CN103305683B (en) * | 2013-05-28 | 2014-11-19 | 首钢总公司 | Low-power burner combustion control system and method for continuous annealing furnace |
| CN104407642B (en) * | 2014-12-01 | 2016-09-07 | 杭州电子科技大学 | A kind of continuous casting billet sensing heating process temp. control method controlled based on iterative learning |
| CN106801139A (en) * | 2017-01-19 | 2017-06-06 | 本钢板材股份有限公司 | Annealing furnace optimization of air-fuel ratio method |
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