CN1157555C - Method and device for detecting boiler heat efficiency - Google Patents

Abstract

The present invention belongs to the technique of heat engineering detection, which discloses a simple method and a device for detecting the heat efficiency of a boiler. Gas or liquid fuel basically does not generate ash when being burnt, the heat loss of a boiler burning a no-ash fuel is radiation loss delta eta 1, waste heat loss delta eta 2 and incomplete-burning heat loss delta eta 3. The radiation loss delta eta 1 is determined through looking up a heat engineering manual according to the capacity and the structure of the boiler, and the sensor 2 of the present invention 1 is used for detecting the moisture contents of air and smoke 4 discharged by the boiler 3; the waste heat loss delta eta 2 and the incomplete-burning heat loss delta eta 3 are calculated by using the method given by the present invention through combining the hydrogen-carbon ratio and the heat productivity of pressure and the fuel, and the heat efficiency of the boiler is eta =1-delta eta 1-delta eta 2-delta eta 3.

Description

Detect the method and apparatus of boiler thermal output

The present invention relates to boiler thermal technology detection technique, specifically, it relates to a kind of simple and easy method and device that detects boiler thermal output.

Boiler thermal output is boiler quantity of heat given up and the ratio of importing heat, and it is an important indicator of boiler performance.To the detection of boiler thermal output, be boiler manufacturing sector, energy management department and boiler user's a regular job.It all is of great importance for improving boiler quality, energy savings, protection environment, improving business economic benefit and social benefit.

The conventional method that detects boiler thermal output has two kinds, a kind of positive balance method of crying, the another kind of counter balancing method that cries.The positive balance method is by measuring boiler quantity of heat given up and fuel input heat, calculate boiler thermal output, and counter balancing method is by measuring the anti-thermal efficiency that pushes away of various thermal loss of boiler, and the boiler thermal output that two kinds of methods draw should equate or be approaching.

Detecting boiler thermal output is very a trouble and an elaboration, needs several technician, in same section official hour, utilize multiple thermal meter, measure many thermal parameters simultaneously, respectively, and then, calculate boiler thermal output according to record data.Because the complicacy of this work, at present, most boiler users can not detect boiler thermal output regularly, can not find the problem in the boiler operatiopn in time.The boiler that moves under poor efficiency has not only been wasted the fuel of a large amount of preciousnesses, has aggravated the pollution to environment, is also indicating sometimes to have certain potential safety hazard.

The boiler common fuel has gaseous fuel, liquid fuel and solid fuel.Gaseous fuel does not produce ash content, and the liquid fuel ash content also seldom usually below 0.1%, therefore, can be called ash free fuel with gaseous fuel and liquid fuel, and most of ash free fuels are hydrocarbons, available CH _nExpression, n is the fuel hydrogen carbon ratio.When boiler uses ash free fuel, can not consider the ash content thermal loss, can think that the thermal loss of boiler has three: the one, the boiler radiation loss, note is made Δ η ₁The 2nd, the boiler exhaust gas thermal loss, note is made Δ η ₂The 3rd, the heat loss due to incomplete combustion, note is made Δ η ₃Utilize counter balancing method,, look into relevant thermal technology's handbook, determine the boiler radiation loss, by detecting boiler exhaust gas thermal loss and heat loss due to incomplete combustion, just can calculate boiler thermal output at first according to boiler capacity and structure.Some solid fuel if ash content also seldom, also can be similar to the method for having only three thermal loss according to above-mentioned, is determined boiler thermal output.

Detect the boiler exhaust gas thermal loss, need to measure exhaust gas temperature and exhaust smoke level.The method of mensuration exhaust smoke level has multiple, for example can determine exhaust smoke level by measuring flue gas flow rate, and also having a kind of method is to calculate exhaust smoke level by oxygen content in the mensuration flue gas.Measure the instrument of flue gas flow rate, for example hot-wire anemometer, more complicated and damage easily.Measure the sensor of oxygen content of smoke gas, be based on that electrochemical principle makes, cost an arm and a leg, serviceable life is short.

Boiler uses the heat loss due to incomplete combustion of ash free fuel, refers to the heat that inflammable gas imperfect combustion or after-flame is taken away in the boiler exhaust gas, and contained inflammable gas comprises CO in the flue gas, H ₂, CH ₄Deng.For surveying the content of each inflammable gas in flue gas, all need sensor special.For instance, in order to measure the concentration of CO in the flue gas, fixed electric potential electroanalysis formula gas sensor commonly used utilizes CO to be oxidized to CO in electrolyte ₂, between electrode, produce electric current simultaneously, according to this size of current, just know the concentration of CO.This also is a kind of electrochemical sensor, and its price is also very expensive, and the life-span is also short.In addition, the electrochemical sensor volume is all bigger, itself is all thermo-labile, therefore when utilizing electrochemical sensor to measure in the flue gas certain combustable gas concentration, can not directly put in the high-temperature flue gas electrochemical sensor, but parts such as the conduit of bleeding, aspiration pump, filtration, dehumidifying will be set, after a small amount of flue gas processing and cooling, send into electrochemical sensor and detect.As seen, existing detection heat loss due to incomplete combustion's apparatus structure complexity, volume are big, cost is high, the life-span is short.

Boiler uses ash free fuel, and not only contained solid particulate matter can be ignored in the smoke evacuation, and other objectionable constituent (for example sulfide) are also less.From environmental angle, country is wideling popularize ash free fuels such as rock gas, therefore, to the detection of the thermal efficiency of the boiler that uses ash free fuel, will be a more and more important job of all departments such as boiler for producing, use, management.But, regrettably, yet there are no simple and easy, detection method and pick-up unit efficiently so far.

Publish by China Machine Press, Lin Zonghu, open that license-master forever compiles " boiler handbook one book has disclosed the method for conventional sense boiler thermal output and used measuring instrument in detail.

The objective of the invention is at the boiler that uses ash free fuel, provide a kind of simple and easy method and device that detects its thermal efficiency, this detection method only needs to measure at the scene that related parameter is arranged on a small quantity, and this pick-up unit is of portable form, its cost is low, the long-life, easy and simple to handle, use reliable.

For achieving the above object, for the boiler that uses ash free fuel, the present invention releases temperature and the humidity that a kind of need are measured surrounding air and boiler smoke at the scene, in conjunction with known conditions such as atmospheric pressure, boiler capacity and fuel performances, just can provide the method for boiler thermal output.

Before the particular content of this method of elaboration, the several problems relevant with this method are described earlier:

Since the air humidity table normally at normal pressure, promptly 10 ⁵Pa pressure is formulated, and real atmosphere pressure may be not equal to normal pressure, for this reason, utilizing before the doing of actual measurement, wet-bulb temperature look into the air water capacity to the air humidity table, carry out non-normal pressure correction to wet-bulb temperature, and its correction formula is

$t_w^{\′}=t_w+(8+\frac{t_w}{3})(1-P)$

T ' in the formula _wBe non-normal pressure correction wet-bulb temperature, t ' _w, t _wUnit be ℃, P is an atmospheric pressure, unit is 10 ⁵Pa.This formula is to show " soft air and hydrocarbon combustion gas thermodynamic properties chart " (Higher Education Publishing House, 1989) book with reference to Yan Jialu, Shang Demin, provides after deliberation.

2. as long as air is unsaturated, promptly as long as do, wet-bulb temperature is unequal, actual measurement wet-bulb temperature just has deviation with theoretical wet-bulb temperature, and especially when air themperature was higher, the wet-bulb temperature deviation was just more obvious.For this reason, with reference to the paper " modifying factor of wet-bulb temperature and calculating formula " of " Engineering Thermophysics journal " (1988.8) Shang Demin, Yan Jialu, provide the unsaturated correction formula of following wet-bulb temperature after deliberation:

$t_w^{\′\′}=t_w^{\′}{\left(\frac{t_w^{\′}}{99.63}\right)}^{0.031(0.02t-1)}$ (when t 〉=99.63 ℃)

$t_w^{\′\′}=t_w^{\′}{\left(\frac{t_w^{\′}}{t}\right)}^{0.16\exp (-0.017t)}$ (when t≤99.63 ℃)

3. use CH _nRepresent ash free hydrocarbon fuels, n is a H:Cmoleratio in the fuel, represents nitrogen oxygen mol ratio in the air (its value is 3.76), CH with x _nThe reaction equation of perfect combustion is in boiler

$C{H}_n+(1+\frac{n}{4})(O_2+x{N}_2)={\mathrm{CO}}_2+\frac{n}{2}{H}_{2}O+(1+\frac{n}{4})x{N}_2---\left(1\right)$

Above-mentioned combustion reaction formula equal sign right side does not promptly contain inflammable gas, oxygen-free gas yet in the products of combustion.The amount of actual air for combustion that participates in burning equals the needed theoretical air requirement of chemical reaction just, and promptly excess air coefficient α is 1.But the Actual combustion situation often is not like this, and the normal amount of actual air for combustion that participates in burning that makes in order to make the fuel after-flame is greater than theoretical air requirement, and just excess air coefficient is greater than 1.

If the generation rough burning, in the rough burning product, i.e. residual inflammable gas in the flue gas, the inflammable gas in the flue gas mainly is CO, H ₂, CH ₄Deng.Write in " oil-burning gas-fired boiler " (Xi'an Communications University publish, 2000) book that " the rough burning product of liquid fuel and gaseous fuel has CO, CH by Zhao Qinxin, Hui Shien chief editor ₄And H ₂Deng, because CH ₄, H ₂Content than CO much less, therefore, be that content with CO is considered as the rough burning product amount in this flue gas in engineering reality.”

4. in above-mentioned combustion reaction, products of combustion does not contain H ₂, promptly think in the hydrocarbon fuel hydrogen all with the oxygen water generation reaction.Hydrocarbon fuel CH _nHydrogen content (mass component of hydrogen) X _HFor

$X_H=\frac{n}{12+n}$

Per two hydrogen atoms and the reaction of oxygen atom generate a hydrone, and the quality of the water of generation is made k with the ratio note of the quality of the hydrogen that participates in reaction, and it equals the ratio of a molecular weight water and two hydrogen atom quality:

$k=\frac{18}{2}=9$

In every kilogram of fuel X is arranged _HKg of hydrogen, every kilogram of fuel combustion generates kX _HKg water, note is made m _v, promptly

$m_V=k{X}_H=9\&times;\frac{\mathrm{<figure-callout\; id="12"\; label="n"\; filenames="C0112607100181.png,C0112607100191.png"\; state="\{\{state\}\}">n</figure-callout>}}{12+n}---\left(2\right)$

5. boiler furnace porch air water capacity note is made d ₁, boiler smoke water capacity note is made d ₂, the dry air amount note that participates in 1 kilogram of fuel combustion is made m _a, the dry flue gas note of generation is made m _g, the steam vapour amount m that generates during the difference of flue gas and air institute containing water vapor should equal to burn _v, it is as follows to list equation:

d ₂m _g－d ₁m _a＝m _v (3)

In the formula

m _a＝m _Aα (4)

m _g=m _a-Δ m=m _Aα-Δ m (5) m _AIt is the theoretical air requirement that 1 kilogram of fuel combustion needs; α is an excess air coefficient; Δ m is for participating in the dry air m of 1 kilogram of fuel combustion _aWith the dry flue gas m that generates _gDifference.With (4), (5) formula substitution (3) formula, it is as follows that arrangement provides excess air coefficient α calculating formula:

α＝(m _v+d ₂Δm)/[m _A(d ₂-d ₁)] (6)

M in the formula _vCalculate m by (2) formula _AExport as by (1) formula

m _A＝(1+n/4)(32+3.76×28)/(12+n)

＝137.28(1+0.25n)/(12+n) (7)

6.1 kg of carbon hydrogen fuel CH _nBurning, hydrogen in the fuel and airborne oxidation synthetic water, the oxygen amount m that consumes in the air _oBe calculated as follows:

$m_o=\frac{\mathrm{<figure-callout\; id="12"\; label="n"\; filenames="C0112607100181.png,C0112607100191.png"\; state="\{\{state\}\}">n</figure-callout>}}{12+n}\&times;8---\left(8\right)$

(8) n/ on formula equal sign right side (12+n) is 1 kilogram of CH _nThe quality of contained protium in the fuel, then it being multiply by 8 is that the quality of oxygen consumed is 8 times of hydrogen because when oxygen and hydrogenation synthetic water.

1 kg of carbon hydrogen fuel CH _nBurning, carbon in the fuel and airborne oxidation are closed, and generate CO ₂Or CO enters dry flue gas, enters the carbonaceous amount m of dry flue gas _cFor

$m_c=\frac{12}{12+n}---\left(9\right)$

Calculate m by (8) formula _o, calculate m by (9) formula _c, 1 kilogram of fuel C H then _nDuring burning, participate in the dry air m of burning _aWith the dry flue gas m that generates _gΔ m of poor quality be:

$\mathrm{\&Delta;m}=m_a-m_g=m_o-m_c=\frac{8n-12}{12+n}---\left(10\right)$

With (2), (7), (10) formula substitution (6) formula, and put in order, obtained another expression formula of excess air coefficient α:

$\mathrm{\&alpha;}=\frac{9n+d_2(8n-12)}{137.28(d_2-d_1)(1+0.25n)}---\left(11\right)$

7. working as excessive air coefficient is α, participates in 1 kilomol fuel C H _nThe air of burning is α (1+0.25n) (32+3.76 * a 28) kilomol, 1 kilogram of fuel C H _nThe exhaust gas volumn m that burning generates _GFor

m _G＝[(12+n)+α(1+0.25n)(32+3.76×28)]/(12+n)

＝[12+n+137.28α(1+0.25n)]/(12+n) (12)

8. scrutinize fuel oil that relevant document provides and a large amount of testing results of gas fired-boiler heat loss due to incomplete combustion, the key factor that influences the heat loss due to incomplete combustion is an excess air coefficient.Under excess air coefficient α 〉=1 condition, comprehensive measured data provides following heat loss due to incomplete combustion's Δ η ₃The approximate treatment formula:

Δ η ₃=0.01 α ^-7.27(being suitable for α 〉=1) (13)

When excessive air coefficient α less than 1 the time, the air that just participates in burning is not enough, the air capacity of shortcoming is suitable with the fuel quantity of participating in reaction, that is suitable with the heat loss due to incomplete combustion, heat loss due to incomplete combustion's Δ η ₃Can be similar to and represent with following formula:

Δ η ₃=1.01-α (being suitable for α≤1) (14)

Based on above-mentioned principle, the method that the detection that the present invention provides uses the ash free fuel boiler thermal output is divided into following several steps:

1. the concrete fuel that uses at boiler is searched relevant thermal technology's handbook, determines its (low level) thermal value Q (kJ/kg);

2. reach according to boiler capacity whether back-end surfaces is arranged, look into thermal technology's handbook, determine boiler radiation loss Δ η ₁

3. determine the water capacity d of surrounding air ₁The concrete practice is to utilize wet-and-dry bulb thermometer, the dry-bulb temperature t of mensuration surrounding air ₁With wet-bulb temperature t _W1, in conjunction with atmospheric pressure, wet-bulb temperature is carried out non-normal pressure correction and unsaturated correction, look into the air humidity table, draw the water capacity d of surrounding air ₁(kg/kg);

4. determine the water capacity d of boiler smoke ₂The concrete practice is to utilize wet-and-dry bulb thermometer, the dry-bulb temperature t of mensuration boiler smoke ₂With wet-bulb temperature t _W2, in conjunction with atmospheric pressure, wet-bulb temperature is carried out non-normal pressure correction and unsaturated correction, look into the air humidity table, draw the water capacity d of boiler smoke ₂(kg/kg);

5. utilize air water capacity d ₁, humidity of flue gas d ₂, boiler fuel CH _nHydrogen-carbon ratio n, calculate excess air coefficient α according to (11) formula:

$\mathrm{\&alpha;}=\frac{9n+d_2(8n-12)}{137.28(d_2-d_1)(1+0.25n)}$

6. utilize excess air coefficient α and boiler fuel CH _nHydrogen-carbon ratio n, calculate 1 kilogram of fuel C H according to (12) formula _nThe exhaust gas volumn m that burning generates _G(kg/kg):

m _G＝[12+n+137.28α(1+0.25n)]/(12+n)

7. look into thermal technology's handbook, determine at t ₁And t ₂Between the average level pressure quality specific heat of flue gas, and use c _pExpression, unit is kJ/kg ℃, is calculated as follows boiler exhaust gas thermal loss Δ η ₂:

$\mathrm{\&Delta;}{\mathrm{\&eta;}}_2=\frac{m_G{c}_p(t_2-t_1)}{Q}$

8. utilize excess air coefficient α, calculate heat loss due to incomplete combustion's Δ η by (13) formula or by (14) formula ₃:

Δ η ₃=0.01 α ^-7.27(when α 〉=1)

Δ η ₃=1.01-α (when α≤1)

9. be calculated as follows boiler thermal output η:

η＝1-Δη ₁-Δη ₂-Δη ₃

With step, detect the device that uses the ash free fuel boiler thermal output and comprise according to the method described above:

Dry-bulb temperature sensor.That is temperature probe, its sensitive element thermoelectricity commonly used is thermal resistance occasionally, and temperature-measuring range is-30 ℃ to 300 ℃;

Wet bulb temperature sensor.It is that bag is made with wet gauze in the thermoelectricity sensitive element outside of temperature probe such as thermal resistance occasionally, and temperature-measuring range-30 is ℃ to 100 ℃;

Analog amplify circuit.Two analog amplify circuits are arranged, and one is the dry-bulb temperature amplifying circuit, and another is the wet-bulb temperature amplifying circuit;

The simulation potentiometer.Two simulation potentiometers are arranged, and one is atmospheric pressure simulation potentiometer, according to environment atmospheric pressure, adjusts the potentiometer output voltage, as the atmospheric pressure simulating signal.Another is a boiler capacity simulation potentiometer, according to boiler capacity, adjusts the potentiometer output voltage, as the boiler capacity simulating signal;

The fuel options button.According to the kind of boiler fuel, determine the figure place of fuel options button.Different fuel, its hydrogen-carbon ratio and thermal value are inequality usually, utilize the fuel options button, provide the hydrogen-carbon ratio of selected fuel and the analog voltage signal of thermal value;

The back-end surfaces options button.Whether boiler is provided with back-end surfaces, and its radiation loss is different.Setting up the back-end surfaces options button, is exactly for when the definite boiler radiation loss, except considering boiler capacity, will consider also whether boiler tail has heating surface, and it is a switching regulator button, and the on-off two states is arranged, to there being or not having the afterbody heating surface;

Analog to digital conversion circuit.It is by an analog to digital converter, and input, output, operation circuit are formed.Its analog quantity incoming line comprises fuel hydrogen carbon ratio aanalogvoltage, the heat output of fuel aanalogvoltage of fuel options button, atmospheric pressure aanalogvoltage, the boiler capacity aanalogvoltage of dry-bulb temperature amplifier out, wet-bulb temperature amplifier out, fuel options button.Relevant with the following single-chip microcomputer circuit with outlet line of the control of analog to digital converter links to each other;

Single chip circuit.It mainly comprises single-chip microcomputer, address latch, memory under program, instruction key, and the address that picked out by single-chip microcomputer, data, operation circuit etc.Under the control of single-chip microcomputer running program and instruction key, the output signal of analog to digital converter enters single chip circuit, through single-chip microcomputer internal arithmetic, processing procedure, at last by the single-chip microcomputer output terminal, provide digitized result,, deliver to display and show then by decoding scheme.Instruction key is one and often opens button, press this key successively, it sends following 8 instructions successively to single-chip microcomputer: survey air parameter, survey Gas Parameters and calculate, show boiler thermal output, show the air consumption coefficient, show the boiler radiation loss, show the boiler exhaust gas thermal loss, show the heat loss due to incomplete combustion, show exhaust gas temperature;

Display and decoding scheme.It comprises one three static number display, three code translators that have latch function, input and output connection lines etc.The input signal of code translator and control signal are from single-chip microcomputer, and the output signal of code translator is given display;

Voltage table.This is a D.C. voltmeter, and its input end is received the output terminal of wet-bulb temperature amplifier, in testing process, according to the voltage table indication, judges whether wet bulb temperature sensor is stable;

Instrument case and panel board.Instrument case is a rectangle, is divided into two parts at the bottom of lid and the box, and the height dimension at the bottom of the box is bigger slightly than lid.The wet and dry bulb temperature sensor leaves in the lid together with wiring.The bottom is a battery at the bottom of box, and panel board is settled in upper edge at the bottom of box.In panel board bottom, lift a circuit board, aforementioned several circuit are all on this piece circuit board.On panel board, sensor socket, power switch, D.C. voltmeter, three bit digital displays, fuel options button, back-end surfaces options button, instruction key, two simulation potentiometers etc. are arranged.

Advantage of the present invention is:

1. boiler thermal output detection method of the present invention is based on counter balancing method, not only provides the thermal efficiency, gives three kinds of main thermal loss and air consumption coefficient simultaneously, and these all are the significant datas of assessment boiler performance.Boiler thermal output detection method of the present invention only needs the dry-bulb temperature and the wet-bulb temperature of testing environment air and boiler smoke at the scene, single can the detection, and method is easy, high efficiency;

2. boiler thermal output pick-up unit of the present invention, except power supply station with the battery, all other parts comprises sensor, does not have the loss of principle.Therefore, boiler thermal output pick-up unit of the present invention is durable in use, and maintenance cost is low;

3. boiler thermal output pick-up unit of the present invention has characteristics such as cost is low, in light weight, simple in structure, dependable performance, is a kind of portable apparatus.

Fig. 1 is the Circuits System schematic diagram of boiler thermal output pick-up unit of the present invention;

Fig. 2 is the wet and dry bulb temperature sensor general assembly drawing of boiler thermal output pick-up unit embodiment of the present invention;

Fig. 3 is the dashboard layout figure of boiler thermal output pick-up unit embodiment of the present invention;

Fig. 4 is the interior arrangenent diagram of the instrument case of boiler thermal output pick-up unit embodiment of the present invention;

Fig. 5 is that boiler thermal output pick-up unit of the present invention detects synoptic diagram at the scene;

Fig. 6 is the computer program process flow diagram of the present invention's method and apparatus of detecting boiler thermal output.

Below in conjunction with drawings and Examples the present invention is described in further detail.

Fig. 1 provides the Circuits System of boiler thermal output pick-up unit of the present invention, this system is divided into eight parts: first's single chip circuit, it is made up of single-chip microcomputer 1, address latch 2, memory under program 3, instruction key 7, address, data, control three buses and input and output circuit.Single-chip microcomputer model 80C31, address latch model 74LS373, memory under program model 27C256; Second portion is an analog amplify circuit, comprises the dry-bulb temperature sensor of making of thermopair 10, and dry-bulb temperature amplifier 11 is with the wet bulb temperature sensor 12 that thermopair outsourcing wet gauze is made, wet-bulb temperature amplifier 13, thermocouple cold end compensator 14 etc.The resistance R in the dry-bulb temperature amplifier 11 wherein _a, R _b, R _cSelection principle be: when dry-bulb temperature changed in-30～300 ℃ of scopes, the output voltage of dry-bulb temperature amplifier 11 should be between 0～3.5V.Resistance R in the wet-bulb temperature amplifier 13 _d, R _e, R _fSelection principle be: when wet-bulb temperature changed in-30～100 ℃ of scopes, the output voltage of wet-bulb temperature amplifier 13 was between 0～3.5V.Thermocouple cold end compensator 14 is to utilize a thermistor R _tWith another fixed resistance R _gConstitute a voltage divider, thermistor R _tBe in same temperature environment with thermocouple cold junction, this voltage divider provides the voltage signal relevant with thermocouple cold junction, after analog to digital converter and single-chip microcomputer processing, thermopair is carried out cold junction compensation; Third part fuel options button aanalogvoltage circuit is comprising fuel hydrogen carbon ratio mimic channel and heat output of fuel mimic channel.R among the figure ₁～R ₆Constitute 3 voltage dividers, provide the hydrogen-carbon ratio aanalogvoltage of 3 kinds of fuel respectively, R ₇～R ₁₂Constitute other 3 voltage dividers, provide the thermal value aanalogvoltage of these 3 kinds of fuel respectively; The 4th partial simulation potentiometer circuit comprises atmospheric pressure analog electrical potentiometer circuit 17, boiler capacity analog electrical potentiometer circuit 18.Wherein atmospheric pressure simulation potentiometer 17 output aanalogvoltages are 0～5V, corresponding atmospheric pressure is 100～50kPa, boiler capacity simulation potentiometer 18 output voltages 0～5V, corresponding boiler capacity is 0～25MW, the full scale resistance of two potentiometers is 10k; The 5th part analog-digital converter circuit, it comprises 4, two OR-NOT circuit of an analog to digital converter 5,6, reaches input, output, operation circuit.Wherein the model of analog to digital converter 4 is ADC0809, and two OR-NOT circuit 5,6 usefulness a slice 74LS02 serve as; The 6th part display decoding scheme, it is by three identical code translators 8 and input, exports the static number decoding scheme that line constitutes.Each code translator input binary-coded decimal is exported 7 n segment display n font sign indicating numbers.Code translator model MC14513, it has and latchs, deciphers, drives function concurrently; The 7th part display 9, it is one three a bit digital static display, 7 diode displaying fields is arranged on every, other has a diode displaying radix point; No. 1 about 12V voltage of 1.5V battery series connection of the 8th part power supply 19,8 joints provides the 5V stabilized voltage supply through voltage stabilizer, voltage stabilizer model LM7805 again.

Below Circuits System principle shown in Figure 1 is described in further detail.

Have 8 path analoging switch of latch function in 4 of the analog to digital converters, can change the input analog voltage signal timesharing of 8 tunnel 0～5V, output terminal has three-state to latch impact damper, directly links on the data bus of single-chip microcomputer 1.The ALE pin OPADD of single-chip microcomputer 80C31 latchs the permission signal, is connected to the G pin of address latch 2.The frequency of ALE pin is 1/6 of single-chip microcomputer 1 clock frequency, the clock frequency of single-chip microcomputer 1 is selected 3MHz for use, then ALE pin output frequency is 500kHz, meets the requirement of analog to digital converter ADC0809 to clock frequency, so the input end of clock CLK of analog to digital converter 4 is received on the ALE pin of single-chip microcomputer 1.The address decoding pin A of analog to digital converter 4, B, C respectively with low three A of single chip circuit address bus ₀, A ₁, A ₂Link to each other, with the IN of gating analog to digital converter 4 ₀～IN ₇In a WR passage.With P _2.7(address bus most significant digit) is as chip selection signal, when starting analog to digital conversion, by the write signal and the P of single-chip microcomputer 1 _2.7Through rejection gate 5, the address latch ALE and the conversion of control analog to digital converter 4 start two ports of START, therefore ALE and START are connected together, and also start conversion when analog to digital converter 4 latchs channel address.When reading transformation result, with the read signal RD and the P of single-chip microcomputer 1 _2.7Pin, through rejection gate 6, the positive pulse of generation is as the output permission signal OE of analog to digital converter 4, in order to open ternary output latch.

Temperature signal with the dry-bulb temperature sensor 10 of thermopair making is gathered through dry-bulb temperature amplifier 11, enters the analog quantity input port IN of analog to digital converter 4 ₀Moisture signal by the wet bulb temperature sensor 12 of thermopair outsourcing wet gauze making is gathered through wet-bulb temperature amplifier 13, enters the analog quantity input port IN of analog to digital converter 4 ₁Use thermistor R _tWith another fixed resistance R _gConstitute voltage divider as thermocouple cold end compensator 14, this compensator output simulating signal enters the analog quantity input end IN of analog to digital converter 4 ₂Fuel options button 15,16 has the switches of two groups of interlocks, and one group of switch 15 wherein is used for the aanalogvoltage circuit of gating fuel hydrogen carbon ratio, and selected fuel hydrogen carbon ratio analog voltage signal enters the analog quantity input port IN of analog to digital converter 4 ₃Another organizes switch 16, is used for the aanalogvoltage circuit of gating heat output of fuel, and selected heat output of fuel analog voltage signal enters the analog quantity input port IN of analog to digital converter 4 ₄, according to local atmospheric value, adjust atmospheric pressure simulation potentiometer 17, export the atmospheric pressure analog voltage signal, enter the analog quantity input port IN of analog to digital converter 4 ₅According to tested boiler capacity, adjust boiler capacity simulation potentiometer 18, export the boiler capacity analog voltage signal, enter the modulus amount input port IN of analog to digital converter 4 ₆

The P of single-chip microcomputer 1 _1.4Pin connect one often open over the ground button 7a, this key is called instruction key.8 place's question and answer routines have been set up in the computer program, are they successively: survey air parameter? survey Gas Parameters and calculating? show the thermal efficiency? show the air consumption coefficient? show the boiler radiation loss? show the boiler exhaust gas thermal loss? do you show the heat loss due to incomplete combustion? show exhaust gas temperature? proceed to when computer program before each of these 8 question and answer routines, by program at first with the P of single-chip microcomputer 1 _1.4Pin puts 1, checks this bonded state then, if closed, promptly 0 level is represented "Yes", and program is carried out downwards, if not closed, promptly 1 level is represented "No", and wait in the program original place.

The P of single-chip microcomputer 1 _1.5Pin links to each other with ground by a switching regulator button 7b, and button 7b is the back-end surfaces options button, if tested boiler has back-end surfaces, button 7b connects, and does not have back-end surfaces, and button 7b disconnects.Single-chip microcomputer except considering boiler capacity, also will be checked this bonded state when definite boiler radiation loss.The P of single-chip microcomputer 1 _1.0～P _1.3Port output result, it is one group of binary-coded decimal, again by code translator 8, last digital indicator 9 by 3 provides numeric results.Digital indicator 9 is the quiescent operation mode, and the LE pin that has the code translator 8 of latch function allows end for latching; The LE pin of 3 code translators 8 is respectively with the P of single-chip microcomputer 1 _3.3, P _3.4, P _3.5Link to each other, single-chip microcomputer 1 timesharing is by P _3.3～P _3.5Send latch signal respectively, 3 code translators 8 from left to right from a high position to the low level, latch the binary-coded decimal that single-chip microcomputer 1 is sent respectively, deliver to continuous display 9 after the decoding and show.All there is a radix point in each lower right corner of display, when needing, connects power supply by the software and hardware cooperation and lights.Whole power supplys 19 of circuit is 5V voltage sources that the battery of 12V provides through voltage stabilizer.

Fig. 2 is the general assembly drawing of the wet and dry bulb temperature sensor of boiler thermal output pick-up unit embodiment of the present invention.Dry-bulb temperature sensor 10 employing external diameters are 1 millimeter armoured thermocouple, and the thermopair material is nickel chromium triangle and nisiloy, and this thermopair is 4 centimetres from sleeve extension length.It is 1 millimeter armoured thermocouple that wet bulb temperature sensor 12 adopts external diameters, counts from the end on 3 centimetre lengths in appearance, and bag is with 4～5 pull-up fat cotton gauzes, and soaks with pure water and to make.Wet-bulb temperature thermocouple wire material is nickel chromium triangle and constantan, and this thermopair extension length from sleeve 20 is 8 centimetres.Parallel distance is 0.5 centimetre between the two sensors 10,12.Sleeve 20 is a stainless-steel tube, 1.2 centimetres of external diameters, long 9 centimetres.Sleeve 20 other ends link to each other with metal hose 21,1 centimetre of metal hose 21 external diameter, long 6 centimetres.The other end of metal hose 21 links to each other with stationary pipes 22, and stationary pipes 22 is a stainless-steel tube, 1.2 centimetres of external diameters, long 10 centimetres.Be handle 23 at last, make, 2 centimetres of external diameters, long 10 centimetres with nylon.4 leads of two sensors and sensor mask line amount to 5 lines and pass from above-mentioned each linkage section, after coming out from handle 23, receive 4 core shielding lines 24, and together with screen layer, totally 5 lines are received one 5 n pin package n 25, and the length of shielding line 24 is 2 meters.

Fig. 3 provides the dashboard layout figure of boiler thermal output pick-up unit embodiment of the present invention.Panel board 27 is a rectangle, and power switch 28 is settled in its lower left corner, in order to the 5V direct supply of connection or stopping device inner circuit system.Is wet and dry bulb temperature sensor socket 29 in the middle of the left side, it is 5 cores, and wherein 1 core is communicated with the ground wire of circuit board, and with plug 25 on to be connected the pin of conductor shielding layer continuous, and do, the wet-bulb temperature signal distinguishes each and uses two cores.The right of sensor socket 29 is back-end surfaces options button 7b, and it is a switching regulator button, provides the information that boiler has or do not have the afterbody heating surface with the on-off of this key to single-chip microcomputer, with the radiation loss of decision boiler.Panel board 27 lower rights are mounted with atmospheric pressure simulation potentiometer 17 and boiler capacity simulation potentiometer 18.These two potentiometers all are rotary small-sized synthetic carbon film potentioneters, and power is 0.5W, and resistance is 10k.When detecting boiler thermal output work, at first to the knob of these two potentiometers be adjusted to the relevant position according to local atmospheric pressure and tested boiler capacity.On the panel board, the range of atmospheric pressure is from 100kPa to 50kPa, and the range of boiler capacity is to 25MW from 0.If the unit of tested boiler capacity is not W, but kcal/h or evaporation capacity t/h can convert by following formula:

1t/h=60 * 10 ⁴The below is a fuel options button 15,16 in the kcal/h=0.6978MW panel board, this is a piano key switch that 8 key positions are arranged, a kind of boiler fuel is represented in each key position, two single-pole single-throw switch (SPST)s are all being controlled in each key position, and each single-pole single-throw switch (SPST) is used for the output control of an analog voltage-dividing circuit.When a certain key position is pressed, promptly choose this fuel, and this key position is controlled, simulate two aanalogvoltages of this fuel hydrogen carbon ratio and thermal value and send.A D.C. voltmeter 26 is settled in the panel board upper left corner, and it is pointer, and full scale is 5V.Whether the input end of this piece voltage table is connected on the output terminal of wet-bulb temperature amplifier, stable in order to the indication detection signal.Because it is longer than dry-bulb temperature that wet-bulb temperature is stablized required time, when wet-bulb temperature was stablized, dry-bulb temperature was stable already.When the voltage table pointer is stablized, press right-hand instruction key 7a of panel board immediately, instruction program is done, the wet-bulb temperature parametric measurement.If the voltage table pointer is stable, slowly not according to instruction key 7a image data, wet bulb moisture evaporate to dryness, voltage table pointer begin again to move, and this moment, image data was incorrect again.Instruction key 7a one often opens button, and it is connected on the single-chip microcomputer, and when program proceeded to some question and answer routines, whether this key of single-chip microcomputer self-verifying was closed, continues downwards or wait in the original place with decision.The panel board upper right side is 3 a digital indicator 9, and it each all is made up of 7 sections light emitting diodes, from left to right is followed successively by high-order to low level, there is a radix point in the lower right corner of each, be a light emitting diode, when needing, light by the software and hardware cooperation.

Fig. 4 is the interior arrangenent diagram of the instrument case of boiler thermal output pick-up unit embodiment of the present invention.Instrument case is divided into lid 30 and box body 32 two parts, has folding to link to each other between two parts.Wet and dry bulb temperature sensor and sleeve 20 etc. are placed in the lid.Lay panel board 27 in the upper edge of box body 32, in Fig. 4, can see D.C. voltmeter 26 and the three bit digital displays 9 settled on the panel board.All on a circuit board 33, this piece circuit board is positioned at box body 32 to whole circuit of boiler thermal output pick-up unit of the present invention, is lifted on below the panel board 27.In the bottom of circuit board 33, just at the bottommost of box body 32, laying No. 1 battery 31 of 8 joints of series connection, every joint 1.5V can see 4 joints wherein from Fig. 4.

Fig. 5 is that boiler thermal output pick-up unit of the present invention detects synoptic diagram at the scene.The figure shows finish the doing of surrounding air, wet-bulb temperature detected after, the detection hole horizontal of sleeve 20 from the bottom of the chimney 35 of boiler 34 inserted, make the sensitive element of wet and dry bulb temperature sensor place the flue center, and make flue gas and sensor vertical current mistake.Note observing the D.C. voltmeter on the box body 32, when the voltage table pointer by slowly moving to transfixion, press instruction key immediately, gather dried, the wet-bulb temperature signal of flue gas, change, calculate, and the boiler thermal output that will draw at last, the air consumption coefficient, every thermal loss etc. are presented on the display of panel board successively by instruction.

Fig. 6 is the process flow diagram of the computer program of the present invention's method and apparatus of detecting boiler thermal output, is described in detail as follows:

Flow process 1: energized, computing machine is started working;

Flow process 2: initialization, comprising atmospheric pressure P, boiler capacity G, fuel hydrogen carbon ratio n, heat output of fuel Q, flue gas specific heat c _pDeng, wherein atmospheric pressure P and boiler capacity G are by adjusting corresponding potentiometer knob setting on the panel board, fuel hydrogen carbon ratio n and heat output of fuel Q are by pressing the fuel used key bits corresponding of fuel options button, connecting corresponding simulation bleeder circuit and set, flue gas specific heat c _pRelevant with flue-gas temperature, general optional c _p=1.1kJ/kg ℃ with this specific heat numerical value write-in program;

Flow process 3: according to relevant thermal technology's handbook, whether the boiler radiation loss has back-end surfaces relevant with boiler capacity G and boiler.To there be under back-end surfaces and two kinds of situations of no afterbody heating surface the relation of boiler radiation loss and boiler capacity list the table of comparisons respectively, table is deposited in the computer program, and in computer program, one section look-up routine is set, just can provide boiler radiation loss Δ η ₁

Flow process 4: whether inquiry gets ready, and immediately the testing environment air related parameter arranged? if, press instruction key, carry out downwards, if not, wait in the program original place;

Flow process 5: utilize the wet and dry bulb temperature sensor, the dry-bulb temperature t of testing environment air ₁With wet-bulb temperature t _W1The sensitive element of the used wet and dry bulb temperature sensor of boiler thermal output pick-up unit of the present invention is all made with thermopair, and the thermoelectrical potential of wet and dry bulb temperature sensor is amplified through simulation, enters analog to digital converter again and is transformed into digital quantity.In the temperature range that boiler detects, linear corresponding relation is good between thermoelectrical potential and the temperature, therefore, analog-to-digital digital quantity and dut temperature relation are simple, the converting digital amount is handled a little, can provide with the thermocouple cold junction is dried, the wet-bulb temperature of benchmark, passes through cold junction compensation again, promptly provides the dry-bulb temperature t of ambient atmosphere ₁With wet-bulb temperature t _W1

Flow process 6:, with an atmospheric air water capacity table, after deliberation, can utilize atmospheric pressure P, to wet-bulb temperature t for only because water capacity is relevant with three factors such as dry-bulb temperature, wet-bulb temperature, atmospheric pressure _W1Carry out non-normal pressure correction, amendment type is as follows:

$t_{w1}^{\&prime;}=t_{w1}+(\frac{t_{w1}}{3}+8)(1-P)$

Consider the deviation of wet-bulb temperature and theoretical wet-bulb temperature, wet-bulb temperature carried out unsaturated correction:

$t_{w1}^{\&prime;\&prime;}=t_{w1}^{\&prime;}{\left(\frac{t_{w1}^{\&prime;}}{t}\right)}^{0.16\exp (-0.017t)}$

T in the formula _W1, t ' _W1, t " _W1, t unit be ℃ that the unit of P is 10 ⁵Pa.Because single-chip microcomputer 80C31 can not carry out the complex mathematical computing, the unsaturated correction of wet-bulb temperature is finished by tabling look-up, and this table utilizes above-mentioned unsaturated correction formula to calculate;

Flow process 7: the dry-bulb temperature t that utilizes surrounding air ₁And the wet-bulb temperature t of following formula correction " _W1, look into the water capacity d of surrounding air ₁Be provided with an air water capacity table in computer program, it is to utilize wet and dry bulb temperature to look into the table of water capacity, and this is a wet and dry bulb temperature and the water capacity table of comparisons under the normal pressure.For the air under any atmospheric pressure, utilize dry-bulb temperature t ₁With revised wet-bulb temperature t " _W1, can utilize this table to look into water capacity d equally ₁

Flow process 8: whether inquiry gets ready, detect the related parameter that has of boiler smoke immediately? if, press instruction key, program is carried out downwards, if not, wait in the program original place;

Program 9: utilize the wet and dry bulb temperature sensor, detect the dry-bulb temperature t of boiler smoke ₂With wet-bulb temperature t _W2The reason identical with flow process 6 when detecting boiler smoke, also will be carried out cold junction compensation to the testing result of wet and dry bulb temperature sensor.The check point of boiler smoke parameter is at the root of chimney, and should prevent from mouthful to leak the influence of air to testing result by detecting in chimney;

Flow process 10: the reason identical with flow process 7, in order to simplify the water capacity table of boiler smoke, utilize atmospheric pressure P, to wet bulb t _W2Carry out non-normal pressure correction;

${\mathrm{<figure-callout\; id="2"\; label="t\; w"\; filenames="C0112607100181.png"\; state="\{\{state\}\}">t</figure-callout>}}_w^2={\mathrm{<figure-callout\; id="2"\; label="t\; w"\; filenames="C0112607100181.png"\; state="\{\{state\}\}">t</figure-callout>}}_w+(\frac{{\mathrm{<figure-callout\; id="2"\; label="t\; w"\; filenames="C0112607100181.png"\; state="\{\{state\}\}">t</figure-callout>}}_w}{3}+8)(1-P)$

Equally also will carry out unsaturated correction to wet-bulb temperature, amendment type is as follows:

${\mathrm{<figure-callout\; id="2"\; label="t\; w"\; filenames="C0112607100181.png"\; state="\{\{state\}\}">t</figure-callout>}}_w^2={\mathrm{<figure-callout\; id="2"\; label="t\; w"\; filenames="C0112607100181.png"\; state="\{\{state\}\}">t</figure-callout>}}_w^2{\left(\frac{{\mathrm{<figure-callout\; id="2"\; label="t\; w"\; filenames="C0112607100181.png"\; state="\{\{state\}\}">t</figure-callout>}}_w^2}{99.63}\right)}^{0.031(0.02t-1)}$ (when t 〉=99.63 ℃)

${\mathrm{<figure-callout\; id="2"\; label="t\; w"\; filenames="C0112607100181.png"\; state="\{\{state\}\}">t</figure-callout>}}_w^2={\mathrm{<figure-callout\; id="2"\; label="t\; w"\; filenames="C0112607100181.png"\; state="\{\{state\}\}">t</figure-callout>}}_w^2{\left(\frac{{\mathrm{<figure-callout\; id="2"\; label="t\; w"\; filenames="C0112607100181.png"\; state="\{\{state\}\}">t</figure-callout>}}_w^2}{t}\right)}^{0.16\exp (-0.017t)}$ (when t≤99.63 ℃)

The reason identical with flow process 7 revised by tabling look-up;

Flow process 11: the dry-bulb temperature t that utilizes boiler smoke ₂, the wet-bulb temperature t of correction " _W2, look into the water capacity d of boiler smoke ₂In computer program, boiler smoke water capacity table and flow process 8 used air water capacity tables are similar, just the temperature range difference.Equally, when carrying out this flow process, utilized the look-up routine of one section humidity of flue gas, according to t ₂, t " _W2, find d ₂

Flow process 12: calculate excess air coefficient α.The air water capacity d that utilizes flow process 8 to obtain ₁The humidity of flue gas d that obtains with flow process 12 ₂, and the given fuel hydrogen carbon ratio n of flow process 2, be calculated as follows excess air coefficient α:

$\mathrm{\&alpha;}=\frac{9n+d_2(8n-12)}{137.28(d_2-d_1)(1+0.25n)}$

Flow process 13: calculate 1 kg of carbon hydrogen fuel CH _nThe exhaust gas volumn m that burning generates _GWhen excessive air coefficient is α, participate in 1 kilomol fuel C H _nThe air of burning is α (1+0.25n) (32+3.76 * a 28) kilomol, does not consider a small amount of water vapor that contains in the air, then 1 kilogram of fuel C H _nThe exhaust gas volumn m that burning generates _GBe calculated as follows:

m _G＝[12+n+137.28α(1+0.25n)]/(12+n)

Flow process 14: calculate boiler exhaust gas thermal loss Δ η ₂Look into thermal technology's handbook, determine at environment temperature t ₁With flue-gas temperature t ₂Between the average level pressure quality specific heat of flue gas, and use c _pExpression, the exhaust gas volumn m that utilizes given heat output of fuel Q of flow process 2 and flow process 13 to draw _G, be calculated as follows boiler exhaust gas thermal loss Δ η ₂:

$\mathrm{\&Delta;}{\mathrm{\&eta;}}_2=\frac{m_G{c}_p(t_2-t_1)}{Q}$

Flow process 15: use the fuel oil of hydrocarbon fuel or heat loss due to incomplete combustion's Δ η of gas fired-boiler ₃Depend primarily on excess air coefficient α, can calculate by the following correlation that provides by the measured data arrangement:

Δ η ₃=0.01 α ^-7.27(when α 〉=1)

Δ η ₃=1.01-α (when α≤1) single-chip microcomputer 80C31 can not carry out exponent arithmetic, at the Δ η of α 〉=1 o'clock ₃Table look-up by single-chip microcomputer and to provide;

Flow process 16: hydrocarbon fuel combustion does not produce ash content basically, and the thermal loss that uses the hydrocarbon fuel boiler has only three: boiler radiation loss Δ η ₁, boiler exhaust gas thermal loss Δ η ₂, heat loss due to incomplete combustion's Δ η ₃, so boiler thermal output is calculated as follows:

η＝1-Δη ₁-Δη ₂-Δη ₃

Flow process 17: press instruction key 7a successively, press altogether 6 times, 3 digital indicator on the panel board shows boiler thermal output η, excess air coefficient α, boiler radiation loss Δ η successively ₁, boiler exhaust gas thermal loss Δ η ₂, heat loss due to incomplete combustion's Δ η ₃With exhaust gas temperature t ₂Deng 6 data.

Claims (10)

1. a detection uses the method for ash free fuel boiler thermal output, and this method is made up of the following step;

(1) at no ash content boiler fuel CH _n, determine its hydrogen-carbon ratio n, and find its net calorific value Q (kJ/kg) from thermal technology's handbook;

(2) reach according to boiler capacity whether back-end surfaces is arranged, look into thermal technology's handbook, determine boiler radiation loss Δ η ₁:

(3) measure the ambient atmosphere temperature t ₁With exhaust gas temperature t ₂, according to t ₁And t ₂, find the average level pressure quality specific heat c of boiler smoke from thermal technology's handbook _p(kJ/kg ℃);

(4) determine excess air coefficient α;

(5) determine the exhaust gas volumn m that every kilogram of fuel combustion generates _G(kg/kg);

(6) be calculated as follows boiler exhaust gas thermal loss Δ η ₂

$\mathrm{\&Delta;}{\mathrm{\&eta;}}_2=\frac{m_G{c}_p(t_2-t_1)}{Q}$

(7) determine heat loss due to incomplete combustion's Δ η ₃

(8) be calculated as follows boiler thermal output η:

η＝1-Δη ₁-Δη ₂-Δη ₃

The method is characterized in that:

(1) method of determining excess air coefficient α is: measure surrounding air water capacity d earlier ₁With boiler smoke water capacity d ₂, utilize d then ₁And d ₂, and given boiler fuel CH _nHydrogen-carbon ratio n, utilize following formula to calculate excess air coefficient α:

$\mathrm{\&alpha;}=\frac{9n+d_2(8n-12)}{137.28(d_2-d_1)(1+0.25n)}$

(2) measure surrounding air water capacity d ₁With boiler smoke water capacity d ₂Method be: at first be used in wet bulb thermometer, measure the dry-bulb temperature t of surrounding air and boiler smoke respectively ₁, t ₂(℃) and wet-bulb temperature t _W1, t _W2(℃), if environment atmospheric pressure P is not equal to normal pressure (10 ⁵Pa), according to following formula, at first to wet-bulb temperature t _W1And t _W2Carry out non-normal pressure correction respectively:

$t_w^{\&prime;}=t_w+(8+\frac{t_w}{3})(1-P)$

T in the formula _w' be non-normal pressure correction wet-bulb temperature, unit is ℃, and P is an atmospheric pressure, and unit is 10 ⁵Pa, surrounding air and boiler smoke institute containing water vapor all are undersaturated usually, wet-bulb temperature has deviation, again to wet-bulb temperature t _W1' and t _W2' carry out unsaturated correction by following formula respectively:

$t_w^{\&prime;\&prime;}=t_w^{\&prime;}{\left(\frac{t_w^{\&prime;}}{99.63}\right)}^{0.031(0.02t-1)}$ (t≥99.63℃)

$t_w^{\&prime;\&prime;}=t_w^{\&prime;}{\left(\frac{t_w^{\&prime;}}{t}\right)}^{0.16\exp (-0.017t)}$ (t≤99.63℃)

Then, utilize the air humidity table under the normal pressure, by t ₁, t _W1" find the water capacity d of surrounding air ₁, by t ₂, t _W2" find the water capacity d of boiler smoke ₂,

(3) determine the exhaust gas volumn m that every kilogram of fuel combustion generates _GMethod be: utilize above-mentioned fixed excess air coefficient α and given boiler fuel CH _nHydrogen-carbon ratio n, be calculated as follows every kilogram of fuel C H _nThe exhaust gas volumn m that burning generates _G(kg/kg):

m _G＝[12+n+137.28α(1+0.25n)]/(12+n)

(4) determine boiler heat loss due to incomplete combustion Δ η ₃Method be: utilize above-mentioned fixed excess air coefficient α, be calculated as follows heat loss due to incomplete combustion's Δ η ₃:

Δ η ₃=0.01 α ^-7.27(when α 〉=1)

Δ η ₃=1.01-α (when α≤1).

2. a detection uses the device of ash free fuel boiler thermal output, it is made of following part: sensor, simulation potentiometer, fuel options button, back-end surfaces options button, display, D.C. voltmeter, analog amplify circuit, cold junction compensation circuit, analog to digital conversion circuit, single chip circuit, display decoding scheme, power supply, panel board and instrument case is characterized in that:

(1) said sensor is dry-bulb temperature sensor and wet bulb temperature sensor, said simulation potentiometer is atmospheric pressure simulation potentiometer and boiler capacity simulation potentiometer, said fuel options button, determine key total by the boiler fuel kind, under each fuel key position, have and this fuel hydrogen carbon ratio and thermal value corresponding simulating bleeder circuit, can switch and export the fuel hydrogen carbon ratio of arbitrary key position and the analog voltage signal of thermal value, said back-end surfaces options button is a switching regulator button, the on-off two states is arranged, to there being or not having the afterbody heating surface, said analog amplify circuit is dry-bulb temperature amplifying circuit and wet-bulb temperature amplifying circuit, in the said analog to digital conversion circuit, the analog quantity that enters analog to digital converter comprises: dry-bulb temperature, wet-bulb temperature, atmospheric pressure, boiler capacity, the fuel hydrogen carbon ratio, heat output of fuel, The Cold-Junction Compensation for Thermocouple;

(2) annexation of above-mentioned device is: the temperature signal that dry-bulb temperature sensor is gathered through the dry-bulb temperature amplifier, enters the input port IN of analog to digital converter ₀, the moisture signal that wet bulb temperature sensor is gathered through the wet-bulb temperature amplifier, enters the input port IN of analog to digital converter ₁, thermocouple cold end compensator output simulating signal enters analog to digital converter input end IN ₂, the analog voltage-dividing signal of fuel options button gating fuel hydrogen carbon ratio enters the input end IN of analog to digital converter ₃, the analog voltage-dividing signal of gating heat output of fuel enters the input end IN of analog to digital converter ₄, atmospheric pressure simulation potentiometer output atmospheric pressure signal enters analog to digital converter input end IN ₅, boiler capacity simulation potentiometer provides the boiler capacity signal and enters analog to digital converter input end IN ₆, the output terminal of analog to digital converter is access to the data channel of single-chip microcomputer, and the back-end surfaces options button provides has or the switching signal of not having an afterbody heating surface directly is sent to an input port of single-chip microcomputer.

3. according to the described boiler thermal output pick-up unit of claim 2, it is characterized in that: the sensitive element of dry-bulb temperature sensor is that external diameter is 1 millimeter a armoured thermocouple, and the thermocouple wire material is nickel chromium triangle and nisiloy; The sensitive element of wet bulb temperature sensor is to be 1 millimeter armoured thermocouple with the external diameter that 4～5 layers of wet cotton gauze are wrapping, and the thermocouple wire material is nickel chromium triangle and constantan.

4. according to the described boiler thermal output pick-up unit of claim 2, it is characterized in that: said cold junction compensation circuit, be to be in the thermistor of same temperature environment with wet and dry bulb temperature sensor thermocouple cold junction by one, with the bleeder circuit that another fixed resistance constitutes, its voltage division signal is sent into analog to digital converter.

5. according to the described boiler thermal output pick-up unit of claim 2, it is characterized in that: said fuel options button is one group of piano key switch, it has a plurality of keys position corresponding with fuel type, two single-pole single-throw switch (SPST)s of each key position control, each single-pole single-throw switch (SPST) is used for the output control of an analog voltage-dividing circuit, when a certain key position is pressed, hydrogen-carbon ratio and two analog voltage-dividing signals of thermal value of the corresponding fuel in this key position are promptly sent respectively.

6. according to the described boiler thermal output pick-up unit of claim 2, it is characterized in that: said analog to digital conversion circuit, comprise an analog to digital converter, two rejection gates and input, output and operation circuit, wherein analog to digital converter is the ADC0809 that 8 analog quantity input ends are arranged, and two rejection gates are served as with a slice 74LS02.

7, according to the described boiler thermal output pick-up unit of claim 2, it is characterized in that: said single chip circuit is to reach address, data, control bus therebetween by single-chip microcomputer, address latch, memory under program, instruction key, externally output, input link are formed, the single-chip microcomputer model is 80C31, the address latch model is 74LS373, the memory under program model is 27C256, and instruction key is a keyswitch open in usual.

8. according to the described boiler thermal output pick-up unit of claim 2, it is characterized in that: said display decoding scheme is by 3 identical code translators and input thereof, the static state that the output line constitutes shows decoding scheme, each code translator can both be exported 7 n segment display n graphemic codes, code translator model MC14513, it has concurrently latchs, decoding, drive function, latch on it and allow end, work as single machine output end, timesharing is sent into binary-coded decimal and is latched the permission signal to code translator, 3 code translators are according to from a high position to the low level, from left to right, drive 3 static number display, show the output content of single-chip microcomputer.

9. according to the described boiler thermal output pick-up unit of claim 2, it is characterized in that: on said panel board, be mounted with wet and dry bulb temperature sensor socket, D.C. voltmeter, display, instruction key, fuel options button, back-end surfaces options button, atmospheric pressure simulation potentiometer, the boiler capacity simulation potentiometer of power switch, 5 cores.

10. according to the described boiler thermal output pick-up unit of claim 2, it is characterized in that: said analog amplify circuit, The Cold-Junction Compensation for Thermocouple circuit, analog to digital conversion circuit, single chip circuit, display decoding scheme etc. all are placed on the circuit board, and this piece circuit board is in instrument case.

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