Background technology
Characteristics such as circulation fluidized-bed combustion boiler pollutes because of it is efficient, low, fuel tolerance is wide are obtaining development rapidly in recent ten years.The combustion system of CFBB has reflected the design feature of recirculating fluidized bed than the concentrated area, and there is bigger difference its combustion chamber with the burner hearth of conventional pulverized-coal fired boiler.Typical CFBB is divided into upper and lower two parts, and the top of combustion chamber is the oxidizing fire district, and the bottom mainly is reduction burning and Gu Liuqu, partly is made up of air-distribution device, emulsion zone, bed internal heating surface, gas-solid material separation device, material returning device etc.Its combustion process is: after coal and desulfurizing agent are admitted to burner hearth, the a large amount of inertia high-temperature materials that existed in the burner hearth rapidly surround, and fire burns, and desulphurization reaction takes place, and under the ascending air effect, move to upper furnace, to other heating surface heat releases of arranging in water-cooling wall and the stove.Oversize grain constantly slows down under gravity and other external force effect and departs from primary air, and finally form attached wall decline particle flux after being brought into the floating zone by ascending air.The solids that are entrained with burner hearth enter high-temperature separator with air-flow, and a large amount of solid materials comprise coal dust and desulfurizing agent, are separated to send burner hearth back to and carry out circulating combustion and desulfurization.Not separated superfine particle enters back-end ductwork with flue gas, further to heat releases such as heating surface, air preheater cooling, enters chimney by air-introduced machine and discharge atmosphere behind deduster.But because that combustion system of circulating fluidized bed boiler is a multivariable, close coupling, pure delay is big, the time the non-linear difficult control system that becomes, thereby under load has operating mode than great fluctuation process, the burning of CFBB is control difficulty especially automatically.
At first, need satisfy following main target with the burning in circulating fluid bed boiler control under the vapour load wide fluctuations: 1) Ran Shao security: the complete fluidisation (comprise in the burner hearth and reaching in the material returning device) that ensures the bed of material, be that bed of material noncoking, returning charge are not ended, and can not make the bed of material cross fluidisation; The interior each point temperature of control stove is with the assurance desulfurized effect, and difficult flame-out or coking, maintains 875 ± 25 ℃ as bed temperature.2) keep the stable of boiler export steam pressure: make CFBB under different load, can both keep the stable of boiler export steam pressure, and lifting load stably.3) ensure the economy and the feature of environmental protection of burning: rational coal-air ratio (oxygen content of smoke gas) under the different load, the reasonably adjustment of each several part temperature in thickness of feed layer (emulsion zone inventory) and circulating ash quantity (dilute-phase zone inventory) and the stove guarantees the economy that different load burns down and satisfies discharge index such as amount of sulfur contenting in smoke.
Secondly, be to judge and control the carbon content of thickness of feed layer in the stove, circulating ash quantity, emulsion zone and dilute-phase zone with the CFBC control difficult point under the vapour load wide fluctuations.But these variablees all are difficult to direct measurement, adopt bed of material differential pressure to characterize thickness of feed layer as existing method more, because bernoulli equation according to two interfaces of measuring point, the measured value of bed of material differential pressure is static pressure and the flow resistance sum that the bed of material produced, and under the operating mode of load large-scope change, the frictional resistance of material and furnace wall and air distribution plate be can not ignore, so even inventory is constant, if primary air fan strengthens, flow resistance strengthens, and bed of material differential pressure also can increase; Thereby adopt single bed of material differential pressure can't characterize the interior thickness of feed layer of stove accurately, be not suitable for the operating mode of load large-scope change.Simultaneously, when loading not simultaneously, interior each several part inventory of stove that CFBB itself is required and proportioning thereof be difference also, and the change of each several part inventory and proportioning thereof is a dynamic process, need take all factors into consideration steadily coming coal supply, deslagging, ash discharge, wind, secondary wind of the stable of boiler export pressure and burning, a plurality of variablees such as returning charge wind, air inducing are coordinated control.Prior art can't solve under with vapour load wide fluctuations, ensures the security and the economy of the popular fluidized bed combustion of circulation, and keeps problems such as the boiler export steam pressure is stable.
Summary of the invention
The utility model is at the deficiencies in the prior art, a kind of CFBB that makes has been proposed under the operating mode of load wide fluctuations, can realize the automatic operating that long-term safety is stable, reach the burning in circulating fluid bed boiler optimal control system under the load large-scope change of effects of energy saving and emission reduction.
The technical solution of the utility model is as follows:
A kind of burning in circulating fluid bed boiler optimal control system, it is characterized in that: it comprises DCS system, optimal controller, expert's logic judging circuit and human-computer interaction module, and wherein said optimal controller comprises material distribution estimator in boiler load regulating loop and the stove; Described DCS system is used to gather the measuring-signal of boiler process data, and material distribution estimator, expert's logic judging circuit are exported described measuring-signal in described boiler load regulating loop, stove, according to the control instruction of described expert's logic judging circuit input, to boiler output control signal; Described human-computer interaction module is to described boiler load regulating loop input material layer temperature setting value, outlet steam pressure setting value and outlet oxygen content setting value;
Described boiler load regulating loop is material distribution estimator output primary air flow calculated value, secondary air flow calculated value and fuel quantity calculating value in described stove; The measuring-signal input of described boiler load regulating loop connects the output of described DCS system, and the setting signal input connects the output of described human-computer interaction module, and the input of interim corrected signal connects the output of described expert's logic judging circuit;
The input of material distribution estimator connects the output of described boiler load regulating loop and DCS system in the described stove, to described expert's logic judging circuit output thickness of feed layer judged result, wherein can be expressed as in order to the bed pressure drop Δ P that judges thickness of feed layer in the stove:
ΔP=mg+κf(u
2,h,i)
Wherein h is a frequency, and u is an air quantity, and i is an electric current, and m is the gross mass of bed material, and the value of κ is by on-the-spot real data match;
In described expert's logic judging circuit logic judging circuit is set, its input connects the output of interior material distribution estimator of described stove and DCS system, thickness of feed layer judged result and measuring-signal according to input, export final controlled quentity controlled variable to described DCS system, and to described boiler load regulating loop input interim correction value of bed temperature and the interim correction value of secondary wind.
Comprise material layer temperature regulating loop, steam pressure regulating loop, flue gas oxygen sulfur content regulating loop in the described boiler load regulating loop.
Comprise coal-air ratio pid control module and multiplier in the described boiler load regulating loop, by described DCS system to described coal-air ratio pid control module input material layer temperature measured value, as feedback, described coal-air ratio pid control module is exported coal-air ratio to described multiplier by the interim correction value of material layer temperature of the material layer temperature setting value of described human-computer interaction module input and the input of expert's logic judging circuit.
Comprise the vapour pressure pid control module in the described steam pressure regulating loop, by described DCS system to described vapour pressure pid control module input outlet steam pressure measured value, outlet steam pressure setting value conduct feedback by described human-computer interaction module input, outlet flow measurement of steam value by the input of described DCS system compensates as dynamic Feedforward, and described vapour pressure pid control module is to described stove internal dynamics model output primary air flow calculated value; Described primary air flow calculated value and described coal-air ratio are imported described multiplier simultaneously, material distribution estimator output fuel quantity in described stove.
Comprise the oxygen content pid control module in the described oxygen content of smoke gas regulating loop, by described DCS system to described oxygen content pid control module input outlet measurement of oxygen content value, by described human-computer interaction module input outlet oxygen content setting value conduct feedback, compensate as dynamic Feedforward by the primary air flow measured value of described DCS system input with by the interim correction value of secondary air flow of described expert's logic judging circuit input, described oxygen content pid control module is material distribution estimator output secondary air flow calculated value in described stove.
Also comprise the combustion chamber draft regulating loop in the described optimal controller, comprise the negative pressure pid control module in the described combustion chamber draft regulating loop, by described DCS system input combustion chamber draft measured value, combustion chamber draft setting value conduct feedback by described human-computer interaction module input, as feedforward, described negative pressure pid control module is to described DCS system output air-introduced machine frequency by the primary air fan frequency of described DCS system input, overfire air fan frequency.
Described final controlled quentity controlled variable comprises coal supply frequency, deslagging ash discharge frequency, once instead expects that blower fan frequency, secondary are counter and expect the blower fan frequency.
Between described expert's logic judging circuit and DCS system, the burning dynamic correcting system is set, proofreaies and correct coal-air ratio according to the material layer temperature measured value of the final controlled quentity controlled variable of described expert's logic judging circuit input and the input of described DCS system.
Technique effect of the present utility model is as follows:
In the burning in circulating fluid bed boiler optimal control of the present utility model system, optimal controller comprises material distribution estimator in boiler load regulating loop and the stove; Wherein boiler load regulating loop material distribution estimator in stove is exported primary air flow calculated value, secondary air flow calculated value and fuel quantity calculating value; Material distribution estimator is to expert's logic judging circuit output thickness of feed layer judged result in the stove; Expert's logic judging circuit is exported final controlled quentity controlled variable according to the thickness of feed layer judged result of input and the measuring-signal of process data to the DCS system, and to boiler load regulating loop input interim correction value of bed temperature and the interim correction value of secondary wind.According to be provided with in the material distribution estimator in the stove stove internal dynamics model must come out of the stove in the variation tendency of thickness of feed layer, and then infer emulsion zone, dilute-phase zone inventory, the measuring-signal of inventory bonded boiler design parameter, execute-in-place experience and DCS system acquisition can characterize the thickness of feed layer in the stove accurately.
The utility model is big according to combustion system of circulating fluidized bed boiler multivariable, close coupling, pure delay, the time characteristics such as change, in stove, be provided with stove internal dynamics model in the material distribution estimator, in conjunction with expert's logic judging circuit, estimate each several part inventory and concentration of carbon, dynamically revise coal-air ratio.Interior each main state variables of the stove of only controlling well, as the emulsion zone inventory, the dilute-phase zone inventory, the emulsion zone concentration of carbon, dilute-phase zone thing concentration of carbon, close dilute-phase zone material ratio, could control each controlled volume well, make ciculation fluidized stove under with vapour load wide fluctuations, can input steady in a long-term move automatically, keep the boiler export steam pressure stable, ensure the security and the economy of the popular fluidized bed combustion of circulation, reserve the surplus of lifting load, improved the robot control system(RCS) operational percentage of burning in circulating fluid bed boiler process greatly, the disturbance of having avoided manual operation to introduce.
The utility model can adopt multiple modes such as OPC, real-time data base to be connected with various DCS, PLC control system, embeds original boiler control system, and it is convenient to transplant, implement.Can satisfy the needs (stablizing steam pressure) of thermic load, make boiler under 55%~100% load, control outlet steam pressure measured value setting value ± fluctuate in the 0.3MPa scope; Guarantee the economy of boiler combustion process, the unit's of making steam coal consumption is lower than manual operation; Keep the material layer temperature measured value setting value ± fluctuate in 25 ℃ of scopes.
The specific embodiment
Below in conjunction with accompanying drawing the utility model is described.
As shown in Figure 1, burning in circulating fluid bed boiler optimal control of the present utility model system comprises DCS system 1, optimal controller 2, expert's logic judging circuit 3, burning dynamic correcting system 4 and human-computer interaction module 5, wherein optimal controller 2 comprises material distribution estimator 23 in combustion chamber draft regulating loop 21, boiler load regulating loop 22 and the stove, wherein comprises material layer temperature regulating loop 221, steam pressure regulating loop 222, flue gas oxygen sulfur content regulating loop 223 in the boiler load regulating loop 22 again.DCS system 1 is a kind of industrial process control system, is used for gathering the measuring-signal of CFBB process data, and these measuring-signals are input in optimal controller 2, expert's logic judging circuit 3, the burning dynamic correcting system 4 carry out computing; Receive the control strategy of burning dynamic correcting system 4 outputs simultaneously, and convert these control strategies to control signal, output to respectively in the corresponding controller, the ruuning situation of CFBB is controlled.
Optimal controller 2 is in conjunction with the pre-set parameter of human-computer interaction module 5 inputs and the measuring-signal of DCS system 1 input, through the computing of material distribution estimator 23 in the stove that wherein is provided with, the inventory of the bed of material, carbon content and both judged results such as distribution situation in expert's logic judging circuit 3 output furnaces.
Be built-in with the pairing control strategy of different input parameter scopes in expert's logic judging circuit 3, the scope that the judged result parameter of importing according to material distribution estimator in the stove 23 falls into, the control strategy that comprehensive selection is made of intermediate quantity, each final controlled quentity controlled variables such as the interim correction value of bed temperature, the interim correction values of secondary wind.
Burning dynamic correcting system 4 is by the material layer temperature measured value of DCS system 1 input, proofread and correct the coal-air ratio of primary air flow and fuel quantity, proofread and correct the coal-air ratio of secondary air flow and fuel quantity by flue gas oxygen content, calculate current coal-air ratio in real time, when lifting load requires, earlier do preset, proofread and correct according to material layer temperature, flue gas oxygen content then according to existing coal-air ratio.
The operator is by the combustion chamber draft setting value of input combustion chamber draft regulating loop 21 in human-computer interaction module 5; And the material layer temperature of material layer temperature regulating loop 221 sets value in the boiler load regulating loop 22, the outlet steam pressure setting value of steam pressure regulating loop 222, the outlet oxygen content setting value of oxygen content of smoke gas regulating loop 223, the anti-material desired temperature of expert's logic judging circuit 3, amount of sulfur contenting in smoke higher limit.System is by human-computer interaction module 5, and realization audible alarm, ejection dialog box, operation note, history curve are monitored in real time to each control loop.
As shown in Figure 2, because there is not stronger coupling in combustion chamber draft regulating loop 21 with other burning loops, thereby adopt the single loop regulative mode, by DCS system 1 input combustion chamber draft measured value, primary air fan frequency, overfire air fan frequency, by human-computer interaction module 5 input combustion chamber draft setting values; With combustion chamber draft measured value input negative pressure pid control module, as feeding back, wind frequency and secondary wind frequency are as feedforward with the combustion chamber draft setting value; The negative pressure pid control module is given outside executing agency, i.e. air-introduced machine frequency converter by DCS system 1 output air-introduced machine frequency.According to the combustion chamber draft measured value to the dynamic response of primary air fan frequency, the overfire air fan frequency preceding feedforward parameter of adjusting, according to the combustion chamber draft measured value to the dynamic response of the air-introduced machine frequency negative pressure pid control module parameter of adjusting, the combustion chamber draft measured value setting value ± the 20Pa scope in variation.
As shown in Figure 3, Figure 4, boiler load regulating loop 22 adopts compound tandem regulative mode, by material layer temperature regulating loop 221, steam pressure regulating loop 222, flue gas oxygen sulfur content regulating loop 223 material distribution estimator 23 input secondary air flow, fuel quantity and primary air flows in stove respectively.
Material layer temperature regulating loop 221 is by DCS system 1 input material layer temperature measured value, by the interim correction value of expert's logic judging circuit 3 input material layer temperatures, by human-computer interaction module 5 input material layer temperature setting values; With the material layer temperature measured value carry out four select one and filtering handle, with the standard value input coal-air ratio pid control module after handling, material layer temperature setting value and the interim correction value of material layer temperature and as feeding back, the coal-air ratio pid control module is exported coal-air ratio to multiplier; Steam pressure regulating loop 222 is to multiplier input primary air flow calculated value simultaneously, and final multiplier is exported fuel quantity.According to the dynamic response characteristic of material layer temperature measured value to coal-air ratio, the feedforward compensation parameter of adjusting and coal-air ratio pid control module parameter.
Steam pressure regulating loop 222 is by DCS system 1 input outlet steam pressure measured value and outlet flow measurement of steam value, by human-computer interaction module 5 input outlet steam pressure setting values; Import the vapour pressure pid control module after will exporting steam pressure measured value differential, outlet steam pressure setting value exports the flow measurement of steam value and compensates as dynamic Feedforward as feedback, vapour pressure pid control module output primary air flow calculated value.According to dynamic response characteristic, adjust feedforward compensation parameter and the vapour pressure pid control module parameter of outlet steam pressure measured value to outlet flow measurement of steam value and primary air flow calculated value.
Oxygen content of smoke gas regulating loop 223 is by DCS system 1 input outlet measurement of oxygen content value, primary air flow measured value, by the interim correction value of expert's logic judging circuit 3 input secondary wind, by human-computer interaction module 5 input outlet oxygen content setting values; To export measurement of oxygen content value input oxygen content pid control module, outlet oxygen content setting value is as feedback, and primary air flow measured value and the interim correction value of secondary wind compensate as dynamic Feedforward, oxygen content pid control module output secondary air flow calculated value.According to outlet measurement of oxygen content value to primary air flow with to dynamic response characteristic, the feedforward compensation parameter of adjusting and the oxygen content pid control module parameter of secondary air flow calculated value.
Material distribution estimator 23 is by boiler load regulating loop 22 input primary air flow calculated values, secondary air flow calculated value and fuel quantity in the stove; The bed of material differential pressure, burner hearth differential pressure, material layer temperature, the material air-teturning temperature that cooperate 1 input of DCS system, primary air fan frequency, primary air fan electric current, overfire air fan frequency, overfire air fan electric current, are instead expected the blower fan electric current at returning charge blower fan frequency; Above-mentioned parameter stove internal dynamics model in stove is estimated inventory, the circulating ash quantity of the bed of material in the stove, judge in the stove that existing inventory (slag, ash) and material distribute and ratio (lime-ash than), whether satisfy the requirement that adds load shedding (promptly add and subtract a wind and fuel quantity).
Analyze theoretically when the bed fluidisation, all material particles is in suspended state, makes the force analysis and the law of conservation of momentum according to bed, and the bed pressure drop that can obtain fluid bed is
Wherein: A is material bed sectional area, and unit is m
2M is the gross mass of bed material, and unit is kg; ρ
p, ρ is for being respectively material density and wind density, unit is kg/m
3Suppose that the pressure drop of fluid bed equals the apparent weight of an interior material (gravity-buoyancy), irrelevant with wind speed.
And under actual condition, the frictional resistance of material and furnace wall and air distribution plate increases with the increase of wind speed, and according to peaceful (Fanning) formula of model, the flow resistance energy loss of fluid in straight tube is:
Ignore air quality, the bed pressure drop of fluid bed can be expressed as under the actual condition:
ΔP=mg+κu
2 (3)
Wherein, u is an air quantity, and unit is m
3/ s; The value of κ is by on-the-spot real data match, and promptly by a small amount of increase and decrease primary air flow, inventory is constant in the short time, the bed pressure drop Δ P data movement of record fluid bed.According to centrifugal fan characteristic curve and characteristic curve of pipeline, pipe resistance increases that air mass flow decline, the power of fan will make the blower fan same frequency under reduce, the blower fan electric current reduces, when air measuring is inaccurate, the bed pressure drop Δ P of also available blower fan frequency, blower fan current correction fluid bed, promptly the bed pressure drop Δ P of fluid bed can be expressed as:
ΔP=mg+κf(u
2,h,i) (4)
Wherein h is a frequency, and unit is HZ; I is an electric current, and unit is A.Equation (3), (4) all are suitable for emulsion zone, dilute-phase zone inventory in the stove.Then can draw emulsion zone, dilute-phase zone inventory m by bed of material differential pressure, burner hearth differential pressure, primary air flow calculated value, secondary air flow calculated value, primary air fan frequency, overfire air fan frequency, primary air fan electric current, overfire air fan electric current, the measuring-signal of the process data that inventory m bonded boiler design parameter, execute-in-place experience and DCS system 1 gather is comprehensively judged thickness of feed layer in the stove.According to measuring-signals such as the bed of material differential pressure under each load of boiler, burner hearth differential pressure, primary air flow calculated value, secondary air flow calculated value, returning charge air quantity, revise material distribution estimator 23 in the stove, make it realistic burning process process.
Expert's logic judging circuit 3 is according to primary air flow calculated value, secondary air flow calculated value, the fuel quantity of 22 inputs of boiler load regulating loop, thickness of feed layer judged result in conjunction with 23 inputs of material distribution estimator in the stove, judge through wherein built-in Expert Rules storehouse, provide intermediate quantities such as interim correction value of bed temperature and the interim correction value of secondary wind, and coal supply frequency, deslagging ash discharge frequency, once instead expect that blower fan frequency, secondary are counter and expect blower fan final controlled quentity controlled variable such as frequently.For example a) surpass setting value ± 0.2MPa when boiler export steam pressure measured value, and it is blocked up or thin excessively by the judgement bed of material (emulsion zone) of material distribution estimator 3 in the stove, in the time of can not adding checking, promptly provide of the negative-feedback of the interim correction value of corresponding bed temperature, by adjusting the interim correction value steady load of bed temperature as the coal-air ratio pid control module; B) when the material returning device temperature surpasses the material returning device desired temperature, can not reduce returning charge wind or increase secondary air flow, in order to avoid returning charge wind is too small or be blown into too much fuel and cause the material returning device coking to material returning device; C) when anti-material wind less than when setting value, can not strengthen primary air flow or secondary air flow, enter anti-glassware in order to avoid be blown into too much material, cause anti-material to stop; D) when amount of sulfur contenting in smoke during greater than amount of sulfur contenting in smoke higher limit 100, forbid increasing fuel quantity, when setting value greater than amount of sulfur contenting in smoke, initiatively subtract fuel quantity, this tactful priority is the highest.
The optimal control method step of burning in circulating fluid bed boiler optimal control of the present utility model system comprises:
1) bed of material differential pressure, burner hearth differential pressure, primary air fan frequency, overfire air fan frequency, primary air fan electric current, the overfire air fan electric current of importing according to DCS system 1, variablees such as the primary air flow measured value of boiler load regulating loop 22 inputs, secondary air flow measured value, fuel quantity are set up material distribution estimator 23 in the stove, the inventory of the bed of material, the estimated value of circulating ash quantity in the output furnace;
2) the preceding flue-gas temperature of material layer temperature, exit gas temperature, material air-teturning temperature, high temperature superheater, the low temperature superheater by 1 input of DCS system exports variable input expert logic judging circuits 3 such as oxygen content of smoke gas, outlet oxygen content, outlet sulfur content, generally by the distribution gradient of material layer temperature in stove, can judge whether coal-air ratio is suitable, if the high explanation of material layer temperature wind is little, the coal amount is big, need add wind and subtract coal; If the low explanation of material layer temperature wind is big, the coal amount is little, needs the checking coal.But in actual condition, have various situations about can only rule of thumb judge: if material layer temperature is lower, instead expect that temperature, exit gas temperature are higher, illustrate that the top that fuel concentrates on burner hearth burns, air quantity is excessive, need hold material (promptly not deslagging); If material layer temperature is higher, the outlet oxygen content reduces, the outlet sulfur content increases, and then the whole carbon content of boiler raises, and air quantity is too small, and the each several part temperature has the trend of rising, needs to reduce fuel quantity or increases air quantity.
3) when changing load, the fluctuation of boiler export steam pressure, calculate required fuel quantity, primary air flow calculated value, secondary air flow calculated value by material layer temperature regulating loop 221, steam pressure regulating loop 222, oxygen content of smoke gas regulating loop 223, dynamically revise coal-air ratio by burning dynamic correcting system 4;
4) judge whether to satisfy the condition of adding and subtracting fuel, air quantity by material distribution estimator 23 and expert's logic judging circuit 3 in the stove, and then selection control strategy, by exporting interim correction value of secondary wind and the interim correction value fuel metering of bed temperature amount, air quantity, and, make the stove internal state satisfy the requirement of increasing and decreasing load by regulating slag extractor frequency, the interior inventory of ash ejector frequency adjustment stove and ash, slag ratio example.
For example, under the permission of stove internal state such as thickness of feed layer, circulating ash quantity and each several part temperature, the plus-minus air quantity is kept the stable of outlet steam pressure measured value with load-responsive variation fast earlier, when the plus-minus air quantity be subjected to inner operating restriction (as the bed of material is blocked up can not checking, prevent coking; The bed of material is crossed to approach and can not be added wind, prevents fluidisation and returning charge termination) time, under the situation that material layer temperature allows, add and subtract coal-supplying amount earlier, suitably raising or reduction material layer temperature are kept the stable of boiler export steam pressure.
Said system satisfies the needs of load, as the 75t boiler under 40t/h~75t/h load, control outlet steam pressure measured value setting value ± fluctuate in the 0.3MPa scope; Guarantee the economy of boiler combustion process, the unit's of making steam coal consumption is lower than manual operation; Keep the material layer temperature measured value setting value ± fluctuate in 25 ℃ of scopes; Thickness of feed layer control waits within the specific limits; The discharging of worker's sulfur oxide, flue dust meets relevant national standard.The burning in circulating fluid bed boiler control and the optimization system of the load wide fluctuations after adjusting, the systems technology parameter is as shown in table 1:
Table 1 system input table
Should be pointed out that the above specific embodiment can make those skilled in the art more fully understand the utility model and create, create but limit the utility model never in any form.Therefore; although this specification is created the utility model with reference to drawings and Examples and is had been described in detail; but; those skilled in the art are to be understood that; still can create the utility model and make amendment or be equal to replacement; in a word, all do not break away from the technical scheme and the improvement thereof of the spirit and scope of the utility model creation, and it all should be encompassed in the utility model and create in the middle of the protection domain of patent.