CN203147727U - Utility boiler operation system based on CO - Google Patents

Abstract

An embodiment of the utility model provides a utility boiler operation system based on CO. The system comprises a boiler system, a DCS and a utility boiler adjusting system, wherein the boiler system comprises a hearth, a coal economizer, a coal mill, an air preheater, a dust remover, a primary air fan, an forced draught blower, an induced draft fan and a CO detecting device. The coal economizer and the coal mill are respectively connected with the hearth, the air preheater is connected with the economizer, the dust remover, the primary air fan and the forced draught blower are respectively connected with the air preheater, the induced draft fan is connected with the dust remover, and the CO detecting device is connected with the air preheater. The DCS is connected with the boiler system and acquires smoke exhausting temperature, CO concentration, smoke exhausting oxygen content, unburned carbon content in fly ash and fan power loss in the boiler system. The utility boiler operation system based on the CO can effectively improve economical efficiency and safety of boiler operation, accords with a current energy conservation and emission reduction strategy, and has great significance to safe and economical operation of the boiler.

Description

Power station boiler operation system based on CO

Technical Field

The utility model relates to a thermal power factory, especially about the boiler system in the thermal power factory, specific say a power plant boiler operation system based on CO.

Background

At present, the operation of the power station boiler in China faces two major pressures: on the premise of variable coal quality, energy conservation and consumption reduction are carried out; and in the technical transformation of the utility boiler, the boiler is subjected to emission reduction. On this basis, it is necessary to make appropriate combustion optimization adjustments to the operating process of the utility boiler.

The combustion optimization adjustment of the boiler operation, namely, the optimization test is carried out on the main parameters influencing the combustion working condition according to the indexes of the quality of the combustion process, so that the combustion process meets the requirements of safety, reliability, economy, high efficiency and low pollution. The main factors influencing the combustion condition include the properties of the coal quality entering the furnace, the total air quantity, the air distribution mode, the powder preparation system and the like, wherein the optimal control of the air quantity is the most complex. Because the control on the air volume directly influences the change of the boiler operation oxygen quantity, the change of the operation oxygen quantity not only directly influences the change of the exhaust heat loss and the boiler thermal efficiency, but also causes the change of other operation parameters, such as unburned carbon content of ash slag, exhaust temperature, total power consumption of a blower, total power consumption of an induced draft fan and the like, and simultaneously, the change of the oxygen quantity also influences the safety of the boiler operation, such as slagging, high-temperature corrosion and the like. Therefore, the optimization control of the combustion process in the furnace is essentially to comprehensively consider and coordinate the heat efficiency of the boiler and relevant operation parameters, and the air quantity needs to be controlled to achieve good combustion control.

At present, the control of the air quantity in the operation of the power station boiler in China is mainly designed by utilizing the linear relation between the boiler load and the air quantity, the opening of a blower or the opening of a secondary air baffle. In the control system, the load instruction of the boiler is directly sent to the air volume control system, and when the load instruction is changed, the air volume instruction and the opening degree of the blower under the new working condition can be quickly obtained through the action of the feedforward loop. However, the boiler is only an approximate linear system, the air volume obtained only by the feedforward loop cannot guarantee the oxygen content index load requirement, and the oxygen content in the flue gas, especially the oxygen content at the inlet of the air preheater, is generally used as an oxygen content correction parameter in the prior art to obtain the accurate air volume. The oxygen content of the tail flue gas is monitored in real time by installing monitoring instruments such as a zirconia oxygen meter and the like at the inlet of the air preheater, and the oxygen content is used as correction of air flow control in the operation of the boiler, so that the air flow is adaptive to the fuel quantity and the load of the operation of the boiler, the optimal air/coal ratio is further ensured, the pulverized coal is completely combusted in a hearth, and the economy and the safety of combustion are ensured.

The combustion optimization control based on the oxygen content in the flue gas mainly has the following defects that (1) the oxygen content cannot directly reflect the quality of the mixing condition of air and coal powder in the furnace, only an excess air coefficient can be provided, and even if the oxygen content is sufficient, if local oxygen deficiency in the furnace is caused by poor mixing and a reducing atmosphere area is presented, incomplete combustion loss is increased; (2) air leakage in the flue has great influence on the measured oxygen amount, while the hearth and the flue of a common boiler always run under negative pressure, and air leakage from the outside of the boiler into the boiler is difficult to avoid; (3) the cross section of a flue in a large boiler unit is large, flue gas is difficult to be uniformly mixed, and serious gas component layering phenomenon is caused as a result, only 1-2 oxygen amount measuring points at the inlet of an air preheater of the existing power plant boiler unit exist, the detected oxygen amount value is not very representative, and certain errors are caused.

SUMMERY OF THE UTILITY MODEL

The embodiment of the utility model provides a power plant boiler operation system based on CO adopts and uses CO control as the main, and oxygen content control is the theory of assisting, through gathering CO concentration and combining the boiler operational parameter to confirm the poor consumption of boiler operation among the power plant distributed control system, further realizes the optimization and the control of the boiler amount of wind, improves the economic nature and the security of boiler operation, accords with current energy saving and emission reduction tactics, has great meaning to power plant boiler's safe economic operation.

The utility model aims at providing a power boiler operation system based on CO, including boiler system, distributed control DCS system and power boiler adjustment system, wherein, boiler system include: a hearth; the coal economizer and the coal mill are respectively connected with the hearth; the air preheater is connected with the economizer; the dust remover, the primary fan and the blower are respectively connected with the air preheater; the induced draft fan is connected with the dust remover; the CO detection device is connected with the air preheater; the distributed control DCS system is connected with the boiler system; and the power station boiler adjusting system is connected with the distributed control DCS system.

Preferably, the CO detection device specifically includes an air pump; the sampling pipe and the dust filter are respectively connected with the air suction pump; and the sampling probe is connected with the dust filter.

Preferably, the CO detection device further comprises a protective cover connected with the sampling probe.

Preferably, the CO detection device further comprises a temperature controller connected with the sampling probe.

Preferably, the CO detection device further comprises a purge probe connected to the sampling probe.

Preferably, the CO detection device further comprises a differential pressure monitor connected to the sampling probe.

Preferably, the CO detection device further comprises an electromagnetic valve connected with the purging probe.

Preferably, the boiler system further comprises a deslagging device connected with the hearth.

The utility model has the advantages that the CO control is adopted as the main idea, the oxygen control is adopted as the auxiliary idea, the consumption difference of the boiler operation is determined by collecting the CO concentration and combining the boiler operation parameters in the power plant decentralized control system, the optimization and the control of the boiler air volume are further realized, and the reduction of the boiler thermal efficiency, the slag formation and the high-temperature corrosion caused by overhigh CO emission concentration and small total air volume can be avoided; also can avoid CO to discharge concentration and cross the boiler thermal efficiency reduction and the auxiliary engine power consumption increase that low, the total amount of wind caused greatly excessively, adopt the technical scheme of the utility model can gain better air volume control to improve boiler thermal efficiency and effectively reduce NOX and discharge concentration, reach energy saving and emission reduction's effect, have fine economic nature, improve the economic nature and the security of boiler operation, accord with current energy saving and emission reduction strategy, have great significance to power plant boiler's safe economic operation.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without inventive exercise.

Fig. 1 is a schematic structural diagram of a CO-based utility boiler operation system according to an embodiment of the present invention;

fig. 2 is a block diagram of a first embodiment of a CO detection apparatus according to an embodiment of the present invention;

fig. 3 is a block diagram of a second embodiment of the CO detection device in the embodiment of the present invention;

fig. 4 is a schematic structural diagram of a second embodiment of the utility model of a CO-based utility boiler operation system provided by the embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

Fig. 1 is a schematic structural diagram of a CO-based utility boiler operation system provided by an embodiment of the present invention, as can be seen from fig. 1, the system includes: a boiler system 100, a distributed control DCS system 200, a utility boiler adjustment system 300,

wherein, the boiler system 100 includes: a hearth 101; an economizer 102 and a coal mill 108 respectively connected with the furnace 101; an air preheater 103 connected to the economizer 102; a dust collector 104, a primary air fan 105 and a blower 106 connected to the air preheater 103, respectively; an induced draft fan 107 connected with the dust remover 104; a CO detection device 109 connected to the air preheater 103;

the distributed control DCS system 200 is connected with the boiler system 100 and collects the exhaust gas temperature, the CO concentration, the exhaust gas oxygen content, the fly ash carbon content and the fan power consumption in the boiler system in real time. In a specific embodiment, the inlet of the boiler air preheater is selected as the CO collection point in consideration of the high temperature and high dust characteristics in the furnace, which is in contrast to the O monitored in the key part of most current utility boiler operations₂The measuring point positions are basically consistent. The cigaretteThe gas temperature is about 360 ℃ generally, and the smoke concentration is 20-50 g/m³Left and right. The DCS is a comprehensive control system which is generated along with the continuous rise of modern large-scale industrial production automation and the increasing complexity of process control requirements, is a product combining computer technology, system control technology, network communication technology and multimedia technology, can provide a window-friendly human-computer interface and a strong communication function, and is modern equipment for completing process control and process management.

The utility boiler adjusting system 300 is connected with the distributed control DCS system 200, and outputs the optimized power of a blower, the optimized power of a coal mill and the optimized power of a primary fan in the boiler system according to the exhaust gas temperature, the CO concentration, the exhaust gas oxygen content, the fly ash carbon content and the power consumption of the fan.

In a specific embodiment, the work flow of the utility boiler adjustment system is as follows:

(1) and respectively determining the exhaust smoke temperature, the CO concentration, the exhaust smoke oxygen content, the fly ash carbon content and the consumption difference corresponding to the power consumption of the fan.

Boiler operation parameters in a distributed control system, such as exhaust gas temperature, exhaust gas oxygen content, fly ash carbon content, CO concentration and the like, are utilized to calculate the thermal efficiency of the boiler in real time according to GB/T10184-1988 'power station boiler performance test rules', consumption difference analysis is carried out on parameters influencing the boiler operation economy, the change of each parameter is converted into the change of power supply coal consumption, key parameters influencing the boiler economy are determined, and the boiler economy is evaluated on line. Among them, the calculation method of boiler thermal efficiency has been studied by many scholars, for example, Li Zhi et al in 2005, 03 th page 28-29 published "power station boiler efficiency on-line calculation method", but in this document do not consider the incomplete combustion loss, i.e. the influence of CO emission loss on boiler thermal efficiency, the utility model discloses a calculation method of the influence of incomplete combustion loss, i.e. CO emission loss, on boiler thermal efficiency, the calculation method can be seen in GB/T10184-1988 power station boiler performance test procedure ".

For example, the relation between the change of the controllable parameters of the thermal power generating unit and the coal consumption is published in pages 29 to 33 of thermal power generation at the 4 th stage of 2002 by Chenhong Wei et al, but the relevant parameters in the literature do not consider the CO concentration, and the change of the CO concentration also has an influence on the analysis of the consumption difference of the oxygen content of the exhaust smoke. The utility model provides a utilize the thermal deviation method to deduce the computational formula of the change of these two parameters of CO dense and oxygen volume to the influence of power supply coal consumption according to GB/T10184-1988 power plant boiler performance test regulation.

The consumption difference corresponding to the CO concentration is calculated by the following formula:

$\frac{{\∂b}_g}{\∂\mathrm{CO}}=\frac{{\∂b}_g}{{\∂\mathrm{\η}}_{\mathrm{gl}}}(\frac{{\∂\mathrm{\η}}_{\mathrm{gl}}}{\∂\mathrm{CO}}+\frac{{\∂\mathrm{\η}}_{\mathrm{gl}}}{\∂\mathrm{\α}}\frac{\∂\mathrm{\α}}{\∂\mathrm{CO}})$

$=\frac{b_g}{{\mathrm{\η}}_{\mathrm{gl}}}.(\frac{12636(V_{\mathrm{gy}}^0+(a-1)V_r^0)}{Q_r}-\frac{(C_p^{\mathrm{gy}}{V}_r^0+C_p^{H_{2}O}1.61d_k{V}_r^0)({\mathrm{\θ}}_{\mathrm{py}}-t_0)+12636{\mathrm{COV}}_r^0}{Q_r}\·\frac{21\×0\·5}{{(21-O_2+0.5\mathrm{CO})}^2})$

wherein, b_gThe unit is g/(kw.h) for the power supply coal consumption of the unit; CO is the CO concentration at the inlet of the air preheater and has a unit of percent; eta_glIs the thermal efficiency of the boiler, and the unit is%; alpha is the boiler exhaust air excess coefficient;

the theoretical dry smoke gas quantity is m 3/kg;

is the theoretical amount of air, in m³/kg；Q_rThe unit is kJ/kg for inputting the heat of the boiler;

the average specific heat capacity of the dry smoke is expressed in kJ/(m)³·℃)；

Is the average specific heat capacity of water vapor and has the unit of kJ/(m)³·℃)；d_kThe moisture content of the dry flue gas is g/kg; theta_pyThe unit is the temperature of exhaust gas; t is t₀Is ambient temperature in units of; o is₂The oxygen content at the inlet of the air preheater is given in%.

The consumption difference corresponding to the oxygen content of the discharged smoke is carried out by the following formula:

$\frac{{\∂b}_g}{{\∂O}_2}=\frac{{\∂b}_g}{{\∂\mathrm{\η}}_{\mathrm{gl}}}\frac{{\∂\mathrm{\η}}_{\mathrm{gl}}}{\∂\mathrm{\α}}\frac{\∂\mathrm{\α}}{{\∂O}_2}$

$=\frac{b_g}{{\mathrm{\η}}_{\mathrm{gl}}}\·\frac{(C_p^{\mathrm{gy}}{V}_r^0+C_p^{H_{2}O}1.6d_k{V}_r^0)({\mathrm{\θ}}_{\mathrm{py}}-t_0)+12636{\mathrm{COV}}_r^0}{Q_r}\·\frac{21}{{(21-O_2+0.5\mathrm{CO})}^2}$

wherein, b_gFor supplying power to units of boilers with coal consumption, unitThe bit is g/(kw · h); eta_glIs the thermal efficiency of the boiler, and the unit is%; alpha is the boiler exhaust air excess coefficient;is the theoretical amount of air, in m³/kg；Q_rThe unit is kJ/kg for inputting the heat of the boiler;

the average specific heat capacity of the dry smoke is expressed in kJ/(m)³·℃)；

Is the average specific heat capacity of water vapor and has the unit of kJ/(m)³·℃)；d_kThe moisture content of the dry flue gas is g/kg; theta_pyThe unit is the temperature of exhaust gas; t is t₀Is ambient temperature in units of; o is₂Oxygen at the inlet of the air preheater in%; CO is the CO concentration at the inlet of the air preheater in%.

(2) And determining an evaluation parameter omega of the boiler operation according to the exhaust gas temperature, the CO concentration, the exhaust gas oxygen content, the fly ash carbon content and the consumption difference corresponding to the power consumption of the fan. ω is determined by the following equation:

$\mathrm{\ω}=\frac{{\∂b}_g}{{\∂\mathrm{\θ}}_{\mathrm{py}}}+\frac{{\∂b}_g}{\∂\mathrm{CO}}+\frac{{\∂b}_g}{{\∂O}_2}+\frac{{\∂b}_g}{{\∂C}_{\mathrm{fh}}}+\frac{{\∂b}_g}{{\∂W}_{\mathrm{fj}}}$

wherein,、

、

、、

the exhaust gas temperature, the CO concentration, the oxygen content of the exhaust gas, the carbon content of the fly ash and the consumption difference corresponding to the power consumption of the fan are respectively.

(3) And outputting the optimized power of a blower, the optimized power of a coal mill and the optimized power of a primary fan in the boiler system.

Firstly, adjusting the secondary air quantity sent into a hearth by a blower according to the real-time information of the oxygen content and the CO concentration of an inlet of an air preheater in a DCS system, and controlling the CO concentration to be within a numerical range, such as 100-200 ppm. That is, when the CO concentration is higher than the range, the power of the blower in the boiler system is increased to increase the secondary air volume, whereas, the power of the blower in the boiler system is decreased to decrease the secondary air volume.

Secondly, on the premise that the CO concentration is in the numerical range, the coal quantity entering the boiler and the primary air quantity output by the primary fan and entering the hearth along with the pulverized coal are reasonably optimized, so that the evaluation parameter omega of the operating economy of the boiler is continuously reduced to be close to 0, and the adjustment and optimization of an air quantity system are realized. In a specific embodiment, on the premise that the CO concentration is in the range of 100-200 ppm, the preset value can be set to be 0 by adjusting the power of the coal mill and the primary air fan, namely, the preset value is obtained

And continuously approaching 0, wherein the power corresponding to the primary air fan is the optimized power, and the power corresponding to the coal mill is the optimized power.

In specific practical application, the power station boiler adjusting system can continuously repeat the optimization process, gradually determine the optimal operation condition according to the real-time boiler evaluation result and the air volume optimization result, and realize accurate control of the air volume of the boiler and safe and economic operation of the unit. In a specific embodiment, when the evaluation parameter of the boiler operation is close to a preset value, the corresponding boiler operating condition parameter at the moment is stored as an optimal operating condition. In practical applications, the utility boiler adjustment system can be implemented by a general processor, or a digital signal processor, or an application specific integrated circuit ASIC, or a field programmable gate array FPGA.

Fig. 4 is a schematic structural diagram of a second embodiment of the CO-based utility boiler operation system according to the embodiment of the present invention, and as can be seen from fig. 4, the boiler system 100 further includes a deslagging apparatus 109 connected to the furnace 101. In the optimization and adjustment process of the boiler, attention is paid to the slag removal amount in a boiler furnace, if obvious slag bonding phenomenon occurs, namely if the slag removal amount exceeds a preset threshold (the preset threshold can be set according to different actual use requirements), on the premise that an evaluation parameter omega is smaller, the air volume entering the furnace can be properly increased, namely, the secondary air volume is increased.

In other specific embodiments, in consideration of the unevenness of combustion at two sides in the hearth and the possible flue gas distribution unevenness in the flue, probe sampling devices of CO can be installed at the inlets of the two air preheaters and transmitted to the dispersion control system in real time to be displayed, so that the secondary air distribution effect at two sides in the hearth can be monitored in real time. Through the monitoring to both sides CO concentration, can know the quality of the burning condition in the stove, in time discover local oxygen deficiency phenomenon to can be through the contrastive analysis of both sides CO concentration, fuel and air distribution in the reasonable adjustment stove distribute, guarantee both sides temperature and oxygen volume distribution's homogeneity.

The utility model discloses an outstanding characteristics lie in the CO concentration of gathering the boiler, in concrete embodiment, go on through CO detection device to the collection of CO concentration. Fig. 2 is a block diagram of a first embodiment of a CO detection device in an embodiment of the present invention, and as can be seen from fig. 2, the CO detection device specifically includes an air pump 1091; a sampling pipe 1092 and a dust filter 1093 which are respectively connected to the air pump 1091; and a sampling probe 1094 connected with the dust filter 1093, wherein under the action of the air suction pump, the flue gas enters the sampling pipe, is filtered by the dust filter and then flows to the sampling probe.

Fig. 3 is a block diagram of a second embodiment of the CO detection device in the embodiment of the present invention, and as can be seen from fig. 3, the CO detection device further includes a protective cover 1095 connected to the sampling probe, and a temperature controller 1096 connected to the sampling probe for controlling the temperature of the sampling probe. And the purging probe 1097 connected with the sampling probe is used for purging the sampling probe. And a differential pressure monitor 1098 connected with the sampling probe monitors the differential pressure of the sampling probe in real time, and controls the purging probe to perform purging operation when the differential pressure of the sampling probe is too high. And an electromagnetic valve 1099 connected with the purging probe is used for switching on or off the purging probe.

Under the effect of the air pump, the tested flue gas enters the main cavity of the sampling probe through the sampling pipe inserted into the flue, flows to the outlet of the sampling probe through the dust filter, and the temperature controller controls the temperature of the probe to be 100-120 ℃, so that the moisture in the flue gas is not likely to be condensed to cause the blockage of the probe. The protective cover covers outside the main cavity body and mainly plays a role in protecting the sampling probe. In order to find the blockage problem in the probe filter and the sampling channel in time, the probe differential pressure monitor can monitor the differential pressure of the probe in real time on line, and once the differential pressure is too high, the probe is purged. In addition, in order to improve the reliability of the monitoring system, two sampling probes are installed at one CO measuring point, when one probe is used for sampling, the other probe is used for purging compressed air for instruments equipped in a power station boiler system, and a pipeline of the purging probe is isolated by an electromagnetic valve. The flue gas after passing through the dust filter is cooled by the condenser, and the moisture in the flue gas is fully removed, so that the influence of the moisture on the measurement precision is reduced.

To sum up, the utility model discloses a beneficial achievement is: a power station boiler method and system based on CO, adopt and control CO as the main idea, oxygen content control is supplementary, confirm the consumption difference of boiler operation through gathering CO concentration and combining the boiler operation parameter in the decentralized control system of the power plant, further realize the optimization and control of the boiler air volume, can avoid reducing, slagging scorification and high-temperature corrosion of boiler thermal efficiency that CO discharge concentration is too high, the total air volume is slightly small to cause; also can avoid CO emission concentration to cross the boiler thermal efficiency reduction and the auxiliary engine power consumption increase that excessively low, the total amount of wind caused greatly, adopt the technical scheme of the utility model can gain better air volume control to improve boiler thermal efficiency and effectively reduce NO_XThe emission concentration reaches the effect of energy conservation and emission reductionThe method has good economy, improves the economy and safety of boiler operation, accords with the current energy-saving and emission-reduction strategy, and has great significance for safe and economical operation of the power station boiler.

The present invention has been explained by using specific embodiments, and the explanation of the above embodiments is only used to help understand the method and the core idea of the present invention; meanwhile, for the general technical personnel in the field, according to the idea of the present invention, there are changes in the specific implementation and application scope, to sum up, the content of the present specification should not be understood as the limitation of the present invention.

Claims (8)

1. The utility boiler operation system based on CO is characterized by comprising a boiler system, a Distributed Control System (DCS) system and a utility boiler adjusting system, wherein the boiler system comprises: a hearth; the coal economizer and the coal mill are respectively connected with the hearth; the air preheater is connected with the economizer; the dust remover, the primary fan and the blower are respectively connected with the air preheater; the induced draft fan is connected with the dust remover; the CO detection device is connected with the air preheater; the distributed control DCS system is connected with the boiler system; and the power station boiler adjusting system is connected with the distributed control DCS system.

2. The CO-based utility boiler operating system of claim 1, wherein the CO detection means specifically comprises a suction pump; the sampling pipe and the dust filter are respectively connected with the air suction pump; and the sampling probe is connected with the dust filter.

3. The CO-based utility boiler operating system of claim 2, wherein said CO detection means further comprises a shield coupled to said sampling probe.

4. The CO-based utility boiler operating system of claim 2, wherein the CO detection means further comprises a temperature controller connected to the sampling probe.

5. The CO-based utility boiler operating system of claim 2, wherein said CO detection means further comprises a purge probe connected to said sampling probe.

6. The CO-based utility boiler operating system of claim 2, wherein said CO detection means further comprises a differential pressure monitor connected to said sampling probe.

7. The CO-based utility boiler operating system of claim 2, wherein said CO detection means further comprises a solenoid valve connected to said purge probe.

8. The CO-based utility boiler operating system of claim 1, wherein said boiler system further comprises a slag removal device coupled to said furnace.

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