CN103836642B - A kind of gas furnace many burners pulse burning control technique method - Google Patents

Abstract

The invention provides a kind of gas furnace many burners pulse burning control technique method.The key of this control method is the difference being calculated the actual temperature in design temperature and gas furnace by controller, is calculated by temperature signal and maximal duty cycle in conjunction with burner work is converted to multiple timings variable pulse signal by PID, exports as control signal.The different control air valve of described multiple timings variable pulse signal according to mode of heating and the open and-shut mode of gas valve, and control the work period of burner controller.The method makes burner according to the burning of certain rule, thus effective control combustion temperature, ensure the temperature homogeneity in gas furnace, improve efficiency of combustion.

Description

A kind of gas furnace many burners pulse burning control technique method

Technical field

The present invention relates to a kind of burner combustion method, particularly a kind of heat treatment gas furnace many burners pulse-combustion method.

Background technology

Along with widely using of natural gas of industry fuel, gas furnace kind and quantity constantly increase, and traditional burner combustion control method has been difficult to adapt to higher heat treatment temperature technological requirement.

At present in gas furnace Combustion System, main flame continuous control and the large and small fire of adopting controls two kinds of modes.Large and small fire Combustion System is divided into again simple break-make pulse-combustion and fixed pulse width burning, and the former lacks the orderly regular distribution of heat energy, and can only meet a part of gas furnace temperature requirements, the latter has certain deficiency in harmonious combustion.

Realize the requirement of higher thermal treatment process, adopt above-mentioned method for controlling combustion, in a lot of combustion gas low temperature oven, temperature homogeneity requirement cannot be reached.

Summary of the invention

The object of the invention is for gas furnace provides a kind of new burner pulse-combustion method, the method is based on the digitlization allocation rule of heat energy, and computer heating control and the cooling that can realize gas furnace control.

Technical scheme of the present invention is as follows:

A kind of gas furnace many burners pulse burning control technique method, comprises the following steps:

A. set temperature sensor, by the actual temperature in described temperature sensor measurement gas furnace;

B. controller is set, gathers the actual temperature in gas furnace that described temperature sensor measurement obtains, and input the maximal duty cycle of design temperature and the work of setting burner, minimum work period; Calculate the temperature signal of actual temperature and described design temperature in gas furnace, and described temperature signal to be calculated by PID and maximal duty cycle in conjunction with burner work is converted to the output of multiple timings variable pulse signal;

C. gas valve, air valve are set respectively; When controller is set as PULSE HEATING control mode, described multiple timings variable pulse signal control air valve and gas valve opening and closing simultaneously; When controller is set as pulse cooling control mode, gas valve is normally closed, the opening and closing of described multiple timings variable pulse signal control air valve;

D. arrange burner controller, when described multiple timings variable pulse signal is high level, burner controller is put little fighting and is carried out fire defector under the control of described controller, maintains burner combustion.

Its further technical scheme is: in described step b, and method temperature signal being converted to the output of multiple timings variable pulse signal is as follows:

By PID computing formula (1), temperature signal is converted to power percentage signal:

$u\left(t\right)=K_{p}e\left(t\right)+K_i\∫e\left(t\right)\mathrm{dt}+K_d\frac{\mathrm{de}\left(t\right)}{\mathrm{dt}}---\left(1\right)$

U (t) be the power percentage signal of output in formula (1), the difference that e (t) is design temperature and actual temperature, K _p, K _i, K _dbe respectively proportionality constant, integral constant, derivative constant;

Power percentage signal u (t) is converted to the pulse width T on of the multiple timings variable pulse signal controlling burner work by through type (2):

Ton=u(t)Tonmax（2）

In formula (2), Tonmax is the maximal duty cycle of burner work, and the value of u (t) is 0 ~ 100%, when u (t) is less than 5%, and combustion furnace job insecurity, pulse signal is closed, and burner does not burn;

The span of pulse width T on is Ton=(0, K ₁p), the operating interval of multiple timings pulse is: Tr=K ₂pe ^1-p, wherein P is power output, K ₁, K ₂for constant, K ₁span be 60 ~ 100, K ₂span be 5 ~ 15.

Its further technical scheme is: the operating interval of adjacent two burners is greater than zero.

Its further technical scheme is: when the timing conversion of described pulse, and multiple burner combustion sequence timing is converted to inverse time sequence by up time sequence by described controller, or is converted to up time sequence by inverse time sequence.

Advantageous Effects of the present invention is:

In the present invention, the width Ton of pulse signal changes with temperature signal, and adjacent pulse time interval Tr is also change, and this makes the burner big fire time not be changeless, so stove combustion in time and spatially more balanced, compares economize energy.In burning, furnace atmosphere is uniformly mixed relatively more abundant, and heat exchange degree is ardent, and in-furnace temperature uniformity is good.And this pulse control method is applicable to the Combustion System of high/low temperature stove.

After many burner combustions stove adopts this method, it also avoid the same time has the working time of 2 and above burner to overlap completely, can avoid the big ups and downs of air fuel gas pressure.In addition, the work schedule of many burners can timing automaticly automatically change in two kinds of situations are burnt in the burning of up time sequence and inverse time sequence, improves the exchange of the thermal efficiency and heat.

Accompanying drawing explanation

Fig. 1 is control system composition frame chart of the present invention.

Fig. 2 is the embodiment schematic diagram that a kind of burner is arranged.

The time sequential pulse distribution diagram that Fig. 3-a is power output when being 100% full power.

The time sequential pulse distribution diagram that Fig. 3-b is power output when being 75% of full power.

The time sequential pulse distribution diagram that Fig. 3-c is power output when being 50% of full power.

The time sequential pulse distribution diagram that Fig. 3-d is power output when being 10% of full power.

Detailed description of the invention

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described further.

The control that the present invention is directed to multiple burner in gas furnace proposes a kind of new control method, does not relate to the Combustion System situation of basic single burner.Each burner energy normal combustion, needs air valve and gas valve to provide air and combustion gas respectively, and ensures certain reasonably air-fuel ratio, also needs burner controller to provide the function such as igniting and fire inspection.

Before burner work, the maximal duty cycle time Tonmax of setting burner combustion and minimum duty cycle time Tonmin.

As shown in Figure 1, after controller receives the actual temperature of temperature sensor measurement, contrast with design temperature, obtain temperature signal, carry out PID calculating, export a power percentage signal.Its control law is:

$u\left(t\right)=K_{p}e\left(t\right)+K_i\∫e\left(t\right)\mathrm{dt}+K_d\frac{\mathrm{de}\left(t\right)}{\mathrm{dt}}---\left(1\right)$

Wherein: u (t) is the power percentage signal exported, the difference that e (t) is design temperature and actual temperature, K _p, K _i, K _dbe respectively proportionality constant, integral constant, derivative constant, K _p, K _i, K _dthree constants can gather examination method by experiment and determine.First by K _pbe adjusted to a smaller value, increase K gradually _p, observed responses curve, until obtain reacting fast, that overshoot is little line of response.Then by K _pbe reduced to original 50% ~ 80%, then a higher value will be adjusted to the time of integration, reduce the time of integration gradually, and corresponding adjustment K _i, examination is gathered to the response be comparatively satisfied with repeatedly.Finally will be adjusted to derivative time is zero, increases derivative time gradually, correspondingly changes Kd and the time of integration simultaneously, and examination is gathered repeatedly, the control effects that final acquisition is satisfied and pid control parameter.Said method is existing known technology, specifically can see the textbook in PID automatic control field or instructive manuals.

The size u (t) of this power percentage signal can be converted to the multiple timings variable pulse signal Ton controlling burner work:

Ton=u(t)Tonmax（2）

The value of u (t) is 0 ~ 100%, and when u (t) is less than 5%, combustion furnace job insecurity, pulse signal will be closed, and burner stops burning.

From (1) and (2) two formulas, the work pulsewidth Ton that different temperature signals e (t) is corresponding different, achieves the control of pulse-width.

The span of pulse width is Ton=(0, K ₁p), the operating interval of pulse is: Tr=K ₂pe ^1-p, wherein, P is power output, K ₁, K ₂for constant, K ₁span be 60 ~ 100, K ₂span be 5 ~ 15.

Fig. 2 is the distribution mode of multiple burner in a gas furnace, and in figure, four converter noses are numbered B1, B2, B3 and B4 respectively.

Fig. 3-a, Fig. 3-b, Fig. 3-c and Fig. 3-d show several specific timing chart.The time sequential pulse distribution diagram that Fig. 3-a is power output when being 100% full power, now burner total power burning.The time sequential pulse distribution diagram that Fig. 3-b is power output when being 75% of full power.The time sequential pulse distribution diagram that Fig. 3-c is power output when being 50% of full power, now each burner work pulsewidth is the half of maximum, and adjacent two burners are staggered the time work, form a burning whirlpool, are beneficial to the transmission of heat.The time sequential pulse distribution diagram that Fig. 3-d is power output when being 10% of full power, now each burner work very short time, but can ensure the reliable and stable work of each burner, this time is also that burner can minimum cycle time of reliably working.If when power output is less than 5%, combustion furnace job insecurity, pulse will be closed.As we know from the figure, distribution of pulses is even and has sequential, and this method can overcome the concentrated combustion problem that flocks together that traditional control method brings.

In order to improve the exchange of the thermal efficiency and heat, in the present invention, the work schedule of multiple burner can timing transitions, during the conversion of multiple timings variable pulse signal sequence, multiple burner combustion sequence timing is converted to inverse time sequence by up time sequence by described controller, or is converted to up time sequence by inverse time sequence.The combustion order of four burners as shown in Fig. 3-a is up time sequence: B1-B2-B3-B4, timing automaticly can change into inverse time sequence: B4-B3-B2-B1.

When gas furnace realizes heating process, controller control air valve and gas valve opening and closing simultaneously, the work period of pulse signal control air valve and gas valve.When gas furnace realizes process for cooling, gas valve is closed always, the work period of a pulse signal control air valve.

In the present invention, because the work pulsewidth of burner combustion is change, namely the burner big fire time is not changeless, so stove combustion in time and spatially more balanced, compares economize energy, improves efficiency of combustion.In burning, furnace atmosphere is uniformly mixed relatively more abundant, and heat exchange degree is ardent, and in-furnace temperature uniformity is good.And this pulse control method is applicable to the Combustion System of high/low temperature stove.

Above-described is only the preferred embodiment of the present invention, the invention is not restricted to above embodiment.Be appreciated that the oher improvements and changes that those skilled in the art directly derive without departing from the spirit and concept in the present invention or associate, all should think and be included within protection scope of the present invention.

Claims (1)

1. gas furnace many burners pulse burning control technique method, comprises the following steps:

A. set temperature sensor, by the actual temperature in described temperature sensor measurement gas furnace;

B. controller is set, gathers the actual temperature in gas furnace that described temperature sensor measurement obtains, and input the maximal duty cycle of design temperature and the work of setting burner, minimum work period; Calculate the temperature signal of actual temperature and described design temperature in gas furnace, and described temperature signal to be calculated by PID and maximal duty cycle in conjunction with burner work is converted to the output of multiple timings variable pulse signal;

C. gas valve, air valve are set respectively; When controller is set as PULSE HEATING control mode, described multiple timings variable pulse signal control air valve and gas valve opening and closing simultaneously; When controller is set as pulse cooling control mode, gas valve is normally closed, the opening and closing of described multiple timings variable pulse signal control air valve;

D. arrange burner controller, when described multiple timings variable pulse signal is high level, burner controller is put little fighting and is carried out fire defector under the control of described controller, maintains burner combustion;

In described step b, method temperature signal being converted to the output of multiple timings variable pulse signal is as follows:

By PID computing formula (1), temperature signal is converted to power percentage signal:

$u\left(t\right)=K_{p}e\left(t\right)+K_i\∫e\left(t\right)dt+K_d\frac{de\left(t\right)}{dt}---\left(1\right)$

U (t) be the power percentage signal of output in formula (1), the difference that e (t) is design temperature and actual temperature, K _p, K _i, K _dbe respectively proportionality constant, integral constant, derivative constant;

Power percentage signal u (t) is converted to the pulse width T on of the multiple timings variable pulse signal controlling burner work by through type (2):

Ton＝u(t)Tonmax(2)

In formula (2), Tonmax is the maximal duty cycle of burner work, and the value of u (t) is 0 ~ 100%, when u (t) is less than 5%, and combustion furnace job insecurity, pulse signal is closed, and burner does not burn;

The span of pulse width T on is Ton=(0, K ₁p), the operating interval of multiple timings pulse is: Tr=K ₂pe ^1-p, wherein P is power output, K ₁, K ₂for constant, K ₁span be 60 ~ 100, K ₂span be 5 ~ 15.