CN107315908A - A kind of coal-fired boiler combustion efficiency online rapid calculation method - Google Patents

Abstract

The invention discloses a kind of coal-fired boiler combustion efficiency online rapid calculation method, the quick obtaining of coal burning boiler of power station and Control of Industrial Boiler Burning Processes efficiency is realized, the foundation of science is provided for the good runing adjustment of boiler.The efficiency of combustion calculation formula of boiler is as follows：；WhereinηRepresent the efficiency of combustion of boiler, %；q ₃Represent that the heat of boiler gas heat loss due to incomplete combustion accounts for the percentage of input heat, %；q ₄Represent that the heat of boiler heat loss of imperfect solid combustion accounts for the percentage of input heat, %.The present invention by the data of live easy measurement are carried out analysis realize coal-fired boiler combustion efficiency in line computation, also achieve boiler gas, the synchronous calculating of solid incomplete combustion loss.Computational methods highly versatile, efficiency calculation can be carried out for coal burning boiler of power station and industry coal-boiler by the computation model simultaneously.

Description

A fast online calculation method for coal-fired boiler combustion efficiency

technical field

The invention belongs to the technical field of boilers, and in particular relates to an online fast calculation method for the combustion efficiency of a coal-fired boiler.

Background technique

Nearly 45% of my country's coal resources are used for power generation and heating. As of the end of 2014, coal-fired units accounted for about 62% of the total number of generating units. At the same time, there are still a large number of industrial coal-fired boilers with low unit efficiency. The combustion efficiency of coal-fired boilers is relatively low, resulting in a waste of energy and serious environmental pollution. Therefore, improving the combustion efficiency of coal-fired boilers has a very close relationship with the implementation of energy-saving and emission-reduction strategies. Combustion efficiency is an extremely important index to indicate the economical efficiency of boiler operation. Quickly and accurately calculating the real-time combustion efficiency of the boiler can keep abreast of the operating status of the boiler and make corresponding control adjustments. Pollution matters.

At present, the calculation of boiler combustion efficiency model requires elemental analysis of pulverized coal, analysis of flue gas components and detection of carbon content in ash. However, it takes a long time to detect the carbon content of ash and slag, and the boiler operating conditions often change, so the measured boiler combustion efficiency cannot guide the boiler operation adjustment in time. Therefore, it is very necessary to establish an online calculation model of boiler combustion efficiency that meets the requirements of fast and accurate.

Contents of the invention

The purpose of the present invention is to provide an online rapid calculation method for coal-fired boiler combustion efficiency, realize the rapid acquisition of combustion efficiency of power station coal-fired boilers and industrial coal-fired boilers, and provide scientific basis for good operation regulation of boilers. The formula for calculating the combustion efficiency of a boiler is as follows:

η=100-q ₃ -q ₄ .

Among them, η represents the combustion efficiency of the boiler, %; q ₃ represents the percentage of heat loss from the incomplete combustion of boiler gas to the input heat, %; q ₄ represents the percentage of heat loss from incomplete combustion of boiler solid to heat input, %. In order to realize the rapid calculation of the combustion efficiency of coal-fired boilers, the present invention simplifies the calculation formulas for the heat loss of gas and solid incomplete combustion, as follows:

(1) Calculation of heat loss from incomplete combustion of gas

The heat loss of gas incomplete combustion only calculates the heat loss caused by combustible gas CO, and the calculation formula is as follows:

q ₃ =V _gy /Q _d ×126.36×CO×100.

The calculation formula of each parameter is as follows:

① Calculation of input heat

Select the low-level calorific value Q _d , kJ/kg, of pulverized coal fed into the boiler to replace the input heat of the boiler for calculation.

②Calculation of dry flue gas volume

The calculation formula of dry flue gas volume V _gy is as follows:

Among them, the volume fraction of CO and _CO2 can be obtained through the online flue gas analyzer configured by the boiler itself or directly accessed and read from the DCS system in real time.

(2) Calculation of heat loss from solid incomplete combustion

The heat loss of solid incomplete combustion only calculates the heat loss caused by slag, fly ash and coal leakage.

The formula for calculating the heat loss of solid incomplete combustion of industrial coal-fired boilers is as follows:

Among them, A _ar is the received base ash of coal, and C _lz , C _fh , and C _lm are the carbon content of slag, fly ash and coal leakage, %. For C _lz , C _fh , and C _lm , the images of slag, fly ash, and coal leakage are mainly processed based on digital image processing method, and the carbon content is predicted by BP neural network.

The heat loss caused by incomplete combustion of coal-fired boilers in power stations ignores the heat loss caused by coal leakage, and the calculation formula is as follows:

The beneficial effects that the present invention has are:

The invention realizes the on-line calculation of the combustion efficiency of the coal-fired boiler by analyzing the data that is easy to measure on site, and also realizes the simultaneous calculation of the incomplete combustion loss of the boiler gas and solid. At the same time, the calculation method is highly versatile, and the calculation model can be used for efficiency calculations for both power station coal-fired boilers and industrial coal-fired boilers.

Description of drawings

The specific implementation manners of the present invention will be described in further detail below in conjunction with the accompanying drawings.

Figure 1 is the hardware structure diagram of the CO and CO ₂ two-in-one gas detector

Figure 2 is a flow chart of boiler combustion efficiency calculation.

detailed description

The present invention will be further described below in conjunction with accompanying drawing.

The online rapid calculation method of the combustion efficiency of the coal-fired boiler of the present invention realizes the rapid acquisition of the combustion efficiency of the coal-fired boiler of the power station and the coal-fired boiler of the industry, and provides a scientific basis for good operation regulation of the boiler. The formula for calculating the combustion efficiency of a boiler is as follows:

η=100-q ₃ -q ₄

Among them, η represents the combustion efficiency of the boiler, %; q ₃ represents the percentage of heat loss from the incomplete combustion of boiler gas to the input heat, %; q ₄ represents the percentage of heat loss from incomplete combustion of boiler solid to heat input, %. In order to realize the rapid calculation of the combustion efficiency of coal-fired boilers, the present invention simplifies the calculation formulas for the heat loss of gas and solid incomplete combustion, as follows:

(1) Calculation of heat loss from incomplete combustion of gas

The heat loss of gas incomplete combustion only calculates the heat loss caused by combustible gas CO, and the calculation formula is as follows:

q ₃ =V _gy /Q _d ×126.36×CO×100

The calculation formula of each parameter is as follows:

① Calculation of input heat

Select the low-level calorific value Q _d , kJ/kg, of pulverized coal fed into the boiler to replace the input heat of the boiler for calculation.

②Calculation of dry flue gas volume

The calculation formula of dry flue gas volume V _gy is as follows:

Among them, the volume fraction of CO and _CO2 can be obtained through the online flue gas analyzer configured by the boiler itself or directly accessed and read from the DCS system in real time.

(2) Calculation of heat loss from solid incomplete combustion

The heat loss of solid incomplete combustion only calculates the heat loss caused by slag, fly ash and coal leakage.

The formula for calculating the heat loss of solid incomplete combustion of industrial coal-fired boilers is as follows:

Among them, A _ar is the received base ash of coal, and C _lz , C _fh , and C _lm are the carbon content of slag, fly ash and coal leakage, %. For C _lz , C _fh , and C _lm , the images of slag, fly ash, and coal leakage are mainly processed based on digital image processing method, and the carbon content is predicted by BP neural network, as shown in the patent application CN201710427783.5.

The heat loss caused by incomplete combustion of coal-fired boilers in power stations ignores the heat loss caused by coal leakage, and the calculation formula is as follows:

As shown in Figure 1, the CO, CO ₂ two-in-one gas detector detects the concentration of CO and CO ₂ in the flue gas through a carbon monoxide sensor and a carbon dioxide sensor, and displays the corresponding values on the LED display.

The present invention simplifies the efficiency calculation model of the existing boiler inverse balance method, and the detection parameters required by the present invention are shown in the following table:

Table 1 Parameters required for detection model

For the efficiency calculation of industrial coal-fired boilers, 7 items need to be obtained. Since the carbon content of the coal-fired boiler leakage in the power station is taken as 0 in the detection model, six parameters need to be obtained for the efficiency calculation of the coal-fired boiler in the power station. Taking a 15t/h industrial coal-fired boiler and a 1025t/h power station coal-fired boiler as examples, the original calculation data are shown in Table 2. First calculate the volume fraction of CO ₂ and the volume of dry flue gas, and on this basis, calculate the various heat losses of the boiler and the combustion efficiency of the boiler. The specific calculation process is shown in Figure 2. The calculation results are shown in Table 3.

Table 2 Raw data of heat balance test of pulverized coal furnace

Table 3 calculation results

Claims (3)

1. a kind of coal-fired boiler combustion efficiency online rapid calculation method, is calculated by the way that formula is calculated as below：

η=100-q₃-q₄

Wherein η represents the efficiency of combustion of boiler, %；q₃Represent that the heat of boiler gas heat loss due to incomplete combustion accounts for input heat Percentage, %；q₄Represent that the heat of boiler heat loss of imperfect solid combustion accounts for the percentage of input heat, %；

The wherein calculating of (1) gas incomplete combustion heat loss：

Gas incomplete combustion heat loss only calculates the heat loss that fuel gas CO is brought, and calculation formula is as follows：

q₃=V_gy/Q_d×126.36×CO×100

Wherein parameters calculation formula is as follows：

1. the calculating of heat is inputted

The net calorific value as received basis Q of selection feeding boiler coal-ash_d, kJ/kg；Calculated instead of boiler input heat；

2. the calculating of dry flue gas volume

Dry flue gas volume V_gyCalculation formula is as follows：

<mrow> <msub> <mi>V</mi> <mrow> <mi>g</mi> <mi>y</mi> </mrow> </msub> <mo>=</mo> <mrow> <mo>(</mo> <mn>1.1296</mn> <mo>-</mo> <mn>0.02028</mn> <msub> <mi>Q</mi> <mi>d</mi> </msub> <mo>/</mo> <mn>1000</mn> <mo>)</mo> </mrow> <mo>+</mo> <mfrac> <mrow> <mo>(</mo> <mn>0.10162</mn> <mo>+</mo> <mn>0.04399</mn> <msub> <mi>Q</mi> <mi>d</mi> </msub> <mo>/</mo> <mn>1000</mn> <mo>)</mo> </mrow> <mrow> <msub> <mi>CO</mi> <mn>2</mn> </msub> <mo>/</mo> <mn>100</mn> </mrow> </mfrac> </mrow>

Wherein CO, CO₂The online flue gas analyzer that volume fraction can be configured by boiler itself is obtained or directly from DCS system In in real time access read；

(2) calculating of heat loss of imperfect solid combustion

Heat loss of imperfect solid combustion only calculates the heat loss that clinker, flying dust and leakage ribbing are come.

2. coal-fired boiler combustion efficiency online rapid calculation method as claimed in claim 1, it is characterised in that：

The heat loss of imperfect solid combustion calculation formula of industry coal-boiler is as follows：

<mrow> <msub> <mi>q</mi> <mn>4</mn> </msub> <mo>=</mo> <mfrac> <mrow> <mn>328.66</mn> <msub> <mi>A</mi> <mrow> <mi>a</mi> <mi>r</mi> </mrow> </msub> </mrow> <msub> <mi>Q</mi> <mi>d</mi> </msub> </mfrac> <mrow> <mo>(</mo> <mfrac> <mrow> <mn>80</mn> <msub> <mi>C</mi> <mrow> <mi>l</mi> <mi>z</mi> </mrow> </msub> </mrow> <mrow> <mn>100</mn> <mo>-</mo> <msub> <mi>C</mi> <mrow> <mi>l</mi> <mi>z</mi> </mrow> </msub> </mrow> </mfrac> <mo>+</mo> <mfrac> <mrow> <mn>15</mn> <msub> <mi>C</mi> <mrow> <mi>f</mi> <mi>h</mi> </mrow> </msub> </mrow> <mrow> <mn>100</mn> <mo>-</mo> <msub> <mi>C</mi> <mrow> <mi>f</mi> <mi>h</mi> </mrow> </msub> </mrow> </mfrac> <mo>+</mo> <mfrac> <mrow> <mn>5</mn> <msub> <mi>C</mi> <mrow> <mi>l</mi> <mi>m</mi> </mrow> </msub> </mrow> <mrow> <mn>100</mn> <mo>-</mo> <msub> <mi>C</mi> <mrow> <mi>l</mi> <mi>m</mi> </mrow> </msub> </mrow> </mfrac> <mo>)</mo> </mrow> </mrow>

Wherein A_arFor the As-received ash content of coal, C_lz、C_fh、C_lmRespectively clinker, flying dust, leak coal phosphorus content, %.For C_lz、 C_fh、C_lmIt is based primarily upon digital image processing method to handle clinker, flying dust, leakage coal image, it is predicted by BP neural network Phosphorus content.

3. coal-fired boiler combustion efficiency online rapid calculation method as claimed in claim 1, it is characterised in that：

The heat loss of imperfect solid combustion of coal burning boiler of power station ignores the heat loss that leakage ribbing is come, and calculation formula is as follows：

<mrow> <msub> <mi>q</mi> <mn>4</mn> </msub> <mo>=</mo> <mfrac> <mrow> <mn>328.66</mn> <msub> <mi>A</mi> <mrow> <mi>a</mi> <mi>r</mi> </mrow> </msub> </mrow> <msub> <mi>Q</mi> <mi>d</mi> </msub> </mfrac> <mrow> <mo>(</mo> <mfrac> <mrow> <mn>10</mn> <msub> <mi>C</mi> <mrow> <mi>l</mi> <mi>z</mi> </mrow> </msub> </mrow> <mrow> <mn>100</mn> <mo>-</mo> <msub> <mi>C</mi> <mrow> <mi>l</mi> <mi>z</mi> </mrow> </msub> </mrow> </mfrac> <mo>+</mo> <mfrac> <mrow> <mn>90</mn> <msub> <mi>C</mi> <mrow> <mi>f</mi> <mi>h</mi> </mrow> </msub> </mrow> <mrow> <mn>100</mn> <mo>-</mo> <msub> <mi>C</mi> <mrow> <mi>f</mi> <mi>h</mi> </mrow> </msub> </mrow> </mfrac> <mo>)</mo> </mrow> <mo>.</mo> </mrow> 1