CN112403257A - high-CO-concentration flue gas coupling low-temperature SCR temperature control method and system - Google Patents

high-CO-concentration flue gas coupling low-temperature SCR temperature control method and system Download PDF

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CN112403257A
CN112403257A CN201911070042.1A CN201911070042A CN112403257A CN 112403257 A CN112403257 A CN 112403257A CN 201911070042 A CN201911070042 A CN 201911070042A CN 112403257 A CN112403257 A CN 112403257A
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CN112403257B (en
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魏进超
康建刚
李俊杰
彭杰
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Zhongye Changtian International Engineering Co Ltd
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    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
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    • B01D53/8628—Processes characterised by a specific catalyst
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01D53/86—Catalytic processes
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
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    • F23J15/08—Arrangements of devices for treating smoke or fumes of heaters
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    • B01D2258/00—Sources of waste gases
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Abstract

The invention provides a temperature control method of high CO concentration flue gas coupling low-temperature SCR, which is characterized in that high CO concentration flue gas is divided into three paths, the first path of flue gas is introduced into a main reaction tower for CO catalytic oxidation, the second path of flue gas is introduced into an adjusting tower for CO catalytic oxidation, the third path of flue gas is directly conveyed through a bypass flue gas conveying pipeline, and the temperature of the flue gas entering an SCR reactor is controlled within a certain temperature window through a device for regulating and controlling CO conversion heat production quantity and a control system. The technical scheme of the invention realizes the replacement or regeneration of the catalyst of the CO reaction tower without shutdown; the temperature rise of the flue gas is controlled by controlling the CO conversion rate, so that the temperature rise caused by CO catalytic oxidation is accurately regulated and controlled; thereby guaranteed the temperature of flue gas in getting into the SCR reactor at the optimum active reaction temperature window, and then guaranteed denitration efficiency.

Description

high-CO-concentration flue gas coupling low-temperature SCR temperature control method and system
Technical Field
The invention relates to a denitration and decarburization method and a denitration and decarburization system, in particular to a denitration and decarburization method and a denitration and decarburization system for high-CO-concentration flue gas, and belongs to the technical field of flue gas purification.
Background
For industrial flue gas, especially for flue gas of sintering machine in steel industry, the flue gas desulfurization and denitration technology is a flue gas purification technology applied to chemical industry for generating multi-nitrogen oxide and sulfur oxide. Nitrogen oxides and sulfur oxides are one of the main sources of air pollution. The simultaneous desulfurization and denitration technology for flue gas is mostly in research and industrial demonstration stages at present, but because the simultaneous desulfurization and denitration can be realized in one set of system, particularly along with the simultaneous desulfurization and denitration of NOXThe control standard is becoming more and more strict, and the desulfurization and denitrification technology is receiving increasing attention from various countries.
In the prior art, Selective Catalytic Reduction (SCR) method is adopted for denitration, and the temperature is generally controlled to be about 150 ℃ and 400 ℃; if the selective non-catalytic reduction SNCR method is adopted for denitration, the temperature is controlled to be between 800 and 1100 ℃ in general. In the prior art, the temperature of the flue gas to be treated is preferentially adjusted to a temperature range suitable for desulfurization treatment, the temperature is generally lower, and then the flue gas subjected to desulfurization is heated to raise the temperature to the temperature range suitable for denitration. In the process, because the amount of the flue gas to be treated is large, a large amount of fuel is consumed for heating the flue gas subjected to desulfurization treatment, so that resource waste and secondary environmental pollution are caused.
In addition, because the flue gas to be treated is generated by the combustion of fuel, the flue gas contains a certain amount of carbon monoxide because the combustion is sufficient and the fuel cannot be completely and fully combusted. In the prior art, the national emission standard of carbon monoxide is not specifically specified at present, so that the flue gas to be treated is directly discharged after being subjected to desulfurization and denitrification treatment, and the carbon monoxide in the flue gas is not specifically treated and utilized, so that the carbon monoxide is directly discharged. Meanwhile, carbon monoxide is colorless, odorless and nonirritating gas; the solubility in water is very low, and the water is extremely insoluble; the explosion limit of the mixture with air is 12.5 to 74.2 percent; carbon monoxide is easy to combine with hemoglobin to form carboxyhemoglobin, so that the hemoglobin loses the oxygen carrying capacity and function, and the tissues are suffocated and die when the oxygen carrying capacity and function are serious; carbon monoxide has toxic effects on systemic histiocytes, and especially on the cerebral cortex. Therefore, the direct emission of carbon monoxide is very polluting to the environment.
The CO catalytic oxidation and removal of the sintering flue gas is coordinated with SCR denitration, and is one of the most promising technical schemes for successfully applying the SCR technology to the sintering flue gas denitration. When the flue gas with high CO concentration is denitrated by adopting a low-temperature SCR process, the flue gas temperature rise effect special for the CO catalytic oxidation process creates the possibility of efficiently removing NOx by the low-temperature SCR. However, there is an optimal active reaction temperature window for both low and medium temperature SCR catalysts. When the CO catalytic oxidation removal is determined in cooperation with the SCR denitration process, in order to ensure that the SCR catalytic reaction process is maintained at an ideal stable denitration level for a long time, the temperature rise effect of CO heat generation on flue gas needs to be relatively stable. However, with the change of the flue gas amount, the temperature of the raw flue gas, the concentration of CO in the flue gas, other components in the flue gas and the like, the heat production process of catalytic oxidation of CO will change, which in turn causes the fluctuation of the temperature of the flue gas before entering the SCR reactor, and affects the denitration reaction process.
The SCR catalyst has higher catalytic activity only under a specific temperature window, when the concentration of CO is higher and the heat generation in the catalytic oxidation process is overhigh, the catalytic activity of the low-temperature SCR catalyst is probably inhibited due to the high flue gas temperature, and the flue gas generally has volatility, so how to control the flue gas temperature before entering the SCR reactor becomes the key point and difficulty of successful application of CO catalytic oxidation removal and SCR denitration to sintering flue gas denitration.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to adjust the different trends of the flue gas by analyzing the concentration of CO in the flue gas with high CO concentration according to the characteristics of the flue gas with high CO concentration, so that the temperature of the flue gas entering the SCR reactor is in an optimal active reaction temperature window. The invention provides a temperature control method of high CO concentration flue gas coupling low-temperature SCR, which is characterized in that high CO concentration flue gas is divided into three paths, the first path of flue gas is introduced into a main reaction tower for CO catalytic oxidation, the second path of flue gas is introduced into an adjusting tower for CO catalytic oxidation, the third path of flue gas is directly conveyed through a bypass flue gas conveying pipeline, and the temperature of the flue gas entering an SCR reactor is controlled within a certain temperature window through a device for regulating and controlling CO conversion heat production quantity and a control system. The technical scheme of the invention realizes the replacement or regeneration of the catalyst of the CO reaction tower without shutdown; the temperature rise of the flue gas is controlled by controlling the CO conversion rate, so that the temperature rise caused by CO catalytic oxidation is accurately regulated and controlled; thereby guaranteed the temperature of flue gas in getting into the SCR reactor at the optimum active reaction temperature window, and then guaranteed denitration efficiency, be the basis of the high-efficient, long-life service of SCR catalyst simultaneously.
According to a first embodiment of the invention, a high CO concentration flue gas coupled low temperature SCR temperature control method is provided.
A high CO concentration flue gas coupling low temperature SCR temperature control method comprises the following steps:
1) identifying and obtaining the total smoke quantity Q of the smoke with high CO concentration, the CO concentration C in the smoke with high CO concentration and the temperature T of the smoke with high CO concentration0；
2) Dividing the high CO concentration flue gas into three paths, introducing the first path of flue gas into a main reaction tower for CO catalytic oxidation, and recording the flue gas amount of the main reaction tower as Q1(ii) a Introducing the second path of flue gas into an adjusting tower for CO catalytic oxidation, and recording the flue gas volume of the adjusting tower as Q2(ii) a The third path of flue gas is directly conveyed through a bypass flue gas conveying pipeline, and the conveying amount of the bypass flue gas is recorded as Q3；
3) Mixing the flue gas discharged after CO catalytic oxidation of the main reaction tower, the flue gas discharged after CO catalytic oxidation of the regulating tower and the flue gas in the bypass flue gas conveying pipeline to obtain SCR reaction flue gas, wherein the temperature of the mixed SCR reaction flue gas is T1；
4) Controlling the quantity Q of flue gas introduced into the regulating tower2And introducing by-pass flue gasFlue gas quantity Q of conveying pipeline3Thereby adjusting the temperature T of the mixed SCR reaction flue gas1So that the temperature T of the SCR reaction flue gas1Reach the temperature T of the SCR reaction windowIs suitable for。
In the invention, the heat W increased according to the mixed SCR reaction flue gas comes from the heat W of the main reaction tower for CO catalytic oxidation1And regulating the tower to perform CO catalytic oxidation W2(ii) a Namely:
W＝W1+W2。
the temperature rise delta T of the flue gas after the CO catalytic oxidation in the main reaction tower and the CO catalytic oxidation in the regulating tower is as follows:
Figure BDA0002260665620000031
according to the CO catalytic oxidation process, the following steps are provided:
W1＝Q1·C·f(GHSV1)·η……II；
W2＝Q2·C·f(GHSV2)·η……III；
f(GHSV1)＝a·GHSV1+k……IV；
f(GHSV2)＝a·GHSV2+k……V；
GHSV1＝Q1/V……VI；
GHSV2＝Q2/V……VII；
to obtain:
Figure BDA0002260665620000032
wherein: q: the total smoke gas amount of the smoke gas with high CO concentration; q1: the flue gas amount of the main reaction tower; q2: adjusting the flue gas amount of the tower; q3The conveying capacity of the bypass flue gas is obtained; cp: specific heat capacity of flue gas; delta T: the variation of the flue gas temperature before and after CO catalytic oxidation; f (GHSV 1): the CO catalytic oxidation conversion rate of the main reaction tower; f (GHSV 2): adjusting the catalytic oxidation conversion rate of CO under the tower; a is the space velocity and the CO catalytic oxidation conversion rate in the main reaction tower and the regulating towerA relationship constant of (1) is a negative value; k is a reaction constant of space velocities in the main reaction tower and the regulating tower and the catalytic oxidation conversion rate of CO, and is a positive value; GHSV1: space velocity of main reaction tower, GHSV1 ∈ [5000,20000 ]]；GHSV2: adjusting the reaction space velocity of the tower, GHSV 2E [5000,20000 ]](ii) a V: the filling amount of the catalyst in the main reaction tower and the regulating tower; w1: the main reaction tower generates heat; w2: regulating the heat production of the tower; c: the CO concentration in the flue gas with high CO concentration; eta: conversion of CO to CO at Unit flow2The heat evolution.
According to the formula VIII, the flue gas quantity Q of the main reaction tower is adjusted1Regulating the flue gas quantity Q of the tower2Bypass flue gas conveying capacity Q3The temperature rise delta T of the flue gas after CO catalytic oxidation in the main reaction tower and CO catalytic oxidation in the regulating tower can be regulated, and the temperature T of the SCR reaction flue gas can be regulated1。
Preferably, the high CO concentration flue gas is adjusted to enter the main reaction tower completely, so that Q is enabled1＝Q，Q2＝Q3When the smoke gas is 0, CO catalytic oxidation is carried out on the smoke gas through the main reaction tower, and then the SCR reaction smoke gas after CO catalytic oxidation is conveyed to the SCR reactor; and (3) judging:
a) when T is1Greater than TIs suitable forDuring the time, adjust and carry high CO concentration flue gas to main reaction tower and bypass pipeline respectively, adjust gradually and carry the flue gas volume that gets into bypass pipeline, promptly: q1Is gradually decreased, Q3Gradually increasing; so that the temperature T of the SCR reaction flue gas detected in time1Reach the temperature T of the SCR reaction windowIs suitable for；
b) When T is1Is equal to TIs suitable forAnd (3) keeping the existing operation condition, namely: q1＝Q，Q2＝Q30; the high CO concentration flue gas completely enters a main reaction tower;
c) when T is1Less than TIs suitable forDuring the process, the flue gas with high CO concentration is respectively conveyed to the main reaction tower and the regulating tower by regulation, the flue gas volume conveyed into the regulating tower is gradually regulated, namely: q1Is gradually decreased, Q2Gradually increase, Q30; for the timely detection of SCR reaction fumesTemperature T1Reach the temperature T of the SCR reaction windowIs suitable for。
In the invention, in the step c), when the amount of the flue gas conveyed into the regulating tower is equal to the amount of the flue gas in the main reaction tower, namely Q1＝Q2Q/2; according to the formula VIII, a is a negative number, and the temperature rise delta T at the moment is the maximum value, namely CO in the flue gas is catalyzed and oxidized to the maximum extent, the heat emitted by CO in the flue gas is the maximum, and the temperature rise of the mixed SCR reaction flue gas reaches the maximum value; if T is at this time1Is still less than TIs suitable forThe mixed SCR reaction smoke is heated by an external heat source, so that the temperature T of the SCR reaction smoke detected in time1Reach the temperature T of the SCR reaction windowIs suitable for。
In the present invention, in step c), the total CO conversion Z in the flue gasGeneral assemblySatisfies the formula:
Zgeneral assembly＝Q1·C·f(GHSV1)+Q2·C·f(GHSV2)……IX；
Derived from the above equation:
Figure BDA0002260665620000041
according to the formula X, a is a negative number, and under the condition that the total flue gas flow Q is not changed, when Q is used1＝Q2When Q/2, the total CO conversion Z in the flue gasGeneral assemblyThe maximum, namely the CO in the flue gas is catalyzed and oxidized to the maximum extent, and the heat emitted by the CO in the flue gas is utilized to the maximum extent; if T is at this time1Is still less than TIs suitable forThe mixed SCR reaction smoke is heated by an external heat source, so that the temperature T of the SCR reaction smoke detected in time1Reach the temperature T of the SCR reaction windowIs suitable for。
Preferably, the external heat source is a hot blast stove connected to a conveying pipeline of the SCR reaction flue gas, and the high-temperature flue gas generated by the hot blast stove is mixed with the mixed SCR reaction flue gas to increase the temperature of the flue gas entering the SCR reactor.
Preferably, the SCR reaction window temperature T is suitably in the range 150 ℃ to 200 ℃.
According to a second embodiment of the invention, a high CO concentration flue gas coupled low temperature SCR temperature control treatment system is provided.
A system for coupling high CO concentration flue gas with low temperature SCR temperature control treatment comprises: a CO main reaction tower, a CO regulating tower and a bypass flue gas conveying pipeline. The total flue gas pipeline which is introduced with the flue gas with high CO concentration is divided into three paths: the first pipeline is connected with the CO main reaction tower, the second pipeline is connected with the CO regulating tower, and the bypass flue gas conveying pipeline. The CO main reaction tower discharges flue gas after CO catalytic oxidation through a third pipeline, and the CO regulating tower discharges flue gas after CO catalytic oxidation through a fourth pipeline. The tail ends of the third pipeline, the fourth pipeline and the bypass flue gas conveying pipeline are combined and connected into a fifth pipeline. The end of the fifth pipe is connected to the SCR reactor.
Preferably, the first pipeline is provided with a first air valve. The second pipeline is provided with a second air valve. And a third air valve is arranged on the bypass flue gas conveying pipeline.
Preferably, the apparatus further comprises: the system comprises a raw flue gas temperature measuring sensor, a raw flue gas CO concentration detection sensor, a raw flue gas flow sensor, a first gas flow sensor, a second gas flow sensor and a third gas flow sensor. The raw flue gas temperature measuring sensor, the raw flue gas CO concentration detecting sensor and the raw flue gas flow sensor are arranged on the main flue gas pipeline. The first gas flow sensor is disposed on the first conduit. The second gas flow sensor is disposed on the second conduit. And the third gas flow sensor is arranged on the bypass flue gas conveying pipeline. And a first temperature measuring sensor is arranged on the fifth pipeline.
Preferably, the third pipeline is provided with a fourth air valve. And a fifth air valve is arranged on the fourth pipeline.
Preferably, the apparatus further comprises: a hot blast stove. And the air outlet of the hot blast stove is connected to the fifth pipeline through a sixth pipeline.
Preferably, a second temperature measuring sensor is arranged on the fifth pipeline and is positioned at the downstream of the connection position of the sixth pipeline.
In the invention, the CO catalytic oxidation process is accompanied with a large amount of heat release, when the catalyst is applied to the field of low-temperature SCR, the heat can enable low-temperature flue gas to rise to a certain temperature, and the problems that the catalytic efficiency of the current low-temperature catalyst is low at low temperature (less than 150 ℃), water vapor is easy to condense and separate out to corrode the catalyst, equipment and the catalyst, and the like are solved; when the heat source is applied to the field of medium-high temperature SCR, the part of heat can partially or even completely replace the heat supplementing effect of an external heat source on the flue gas, and the problem of high energy consumption of flue gas heating is solved.
Fig. 3 is a schematic diagram of a reaction device capable of adjusting the temperature of the flue gas at the SCR inlet, the device is composed of a CO reaction tower, a CO reaction standby tower, a flue gas bypass, a hot blast stove, and an SCR reactor, the flue gas containing CO and NOx in normal conditions (or in design conditions) undergoes CO catalytic oxidation conversion in the CO reaction tower, and then releases heat to heat the decarbonized flue gas (flue gas containing NOx), and the flue gas containing NOx at a temperature meeting the requirement enters the SCR reactor to be removed and becomes clean flue gas, and the clean flue gas is discharged out of the system.
The standby tower for the CO reaction has two functions: firstly, the standby tower is used as a standby tower after the catalyst in the reaction tower is poisoned and inactivated, and when the standby tower is started, the catalyst in the reaction tower can be regenerated in the tower or taken out for regeneration, so that the normal operation of a main system is not influenced; secondly, when the heat released by the flue gas after passing through the CO reaction tower under special conditions is not enough to enable the flue gas to reach the target flue gas temperature of the SCR reaction, partial flue gas is shunted, namely the volume of the catalyst is increased, so that the absolute total CO conversion amount is increased, and the release amount of the CO conversion heat is increased.
As shown in FIG. 2, CO catalytic oxidation is carried out at a space velocity (GHSV) < 20000h-1When the CO reaction space velocity is designed to be about 10000 in the process, the CO conversion rate and the space velocity linearly change, and the CO conversion rate f (GHSV) ═ a GHSV + k, a is a constant less than 0. Assuming that the total amount of flue gas is Q, the concentration of CO in the flue gas is C, and the volumes of catalysts in the reaction tower and the standby tower are V, the flue gas amount in the reaction tower is Q1, and the flue gas amount of the standby tower split flow (Q-Q1), at this time, the whole system:
Figure BDA0002260665620000061
the upper typeWhen Q1At Q/2, there is a maximum, i.e. maximum CO conversion, so that when the standby column is subjected to flue gas splitting, i.e. the flue gas quantity in the reaction column is gradually reduced, i.e. Q1Q gradually goes to Q1At the Q/2 change, the system CO conversion gradually approaches a maximum, i.e., the heat production increases to a maximum.
When the heat regulation effect of the standby tower reaches the maximum value and still cannot meet the target flue gas temperature of the SCR, a downstream hot blast stove is required to be started to supplement heat for the flue gas.
The flue gas bypass conveying pipeline has the following functions: under special conditions (the smoke quantity is greatly increased in a short time or the CO concentration is greatly improved), when the temperature of the smoke exceeds the target smoke temperature of SCR reaction by the heat released by the smoke after passing through the CO reaction tower, partial smoke is shunted, so that the absolute CO conversion quantity of the whole system is reduced, and the release quantity of the CO conversion heat is reduced.
In the invention, the space velocity is equal to the amount of flue gas/volume of catalyst, the volume of catalyst is increased, the space velocity is reduced, and the CO conversion rate is increased.
In the invention, under normal conditions, only K1 and K4 are started, CO and NOx-containing flue gas is subjected to CO catalytic oxidation conversion in a CO reaction tower, heat is released to heat decarbonized flue gas (NOx-containing flue gas), and NOx in the NOx-containing flue gas with the temperature meeting the requirement enters an SCR reactor to be removed and changed into clean flue gas to be discharged out of a system.
And secondly, when the inlet flue gas temperature of the SCR reactor is less than the denitration target flue gas temperature, only opening K1, K2, K4 and K5, and adjusting the opening degree of a K2 valve to control the flue gas volume entering the standby tower so as to gradually increase the inlet flue gas temperature of the SCR reactor to the target value.
And thirdly, when the adjusting function of the middle standby tower is exerted to the maximum value, half of the smoke amount is shunted by the standby tower, the smoke temperature at the inlet of the SCR reactor is still lower than the target value, and the hot blast stove is started to supplement heat for the smoke.
And fourthly, when the inlet flue gas temperature of the SCR reactor is higher than the denitration target flue gas temperature, only opening K1, K3 and K4, adjusting the opening degree of a K3 valve to control the flue gas volume entering the bypass flue gas conveying pipeline, and gradually reducing the inlet flue gas temperature of the SCR reactor to the target value.
In the technical scheme of the invention, the high CO concentration flue gas passes through the main reaction tower and the regulating tower, and carbon monoxide in the desulfurized flue gas is converted into carbon dioxide, which specifically comprises the following steps:
2CO+O2＝＝＝＝2CO2。
carbon monoxide in the flue gas is utilized to react with oxygen to generate carbon dioxide, which is an exothermic reaction, the carbon monoxide in the flue gas is converted into carbon dioxide through the main reaction tower and the regulating tower, and the heat released by the reaction is used for heating the flue gas, so that the effect of heating the flue gas entering the SCR reactor is realized; meanwhile, the carbon monoxide in the flue gas is removed, and the pollution of the carbon monoxide in the flue gas to the environment is avoided.
Through years of research and engineering practice, the designer of the invention provides that carbon monoxide is converted into carbon dioxide by utilizing the carbon monoxide component existing in the flue gas to be treated, the reaction releases heat, and the temperature of the flue gas with high CO concentration can be automatically raised by utilizing the released heat, so that the aim of raising the temperature of the flue gas entering a denitration system is fulfilled; meanwhile, the pollutant carbon monoxide in the flue gas is treated.
In the invention, the high CO concentration flue gas is conveyed to a carbon monoxide treatment system (a main reaction tower and an adjusting tower), in the carbon monoxide treatment system (the main reaction tower and the adjusting tower), carbon monoxide in the high CO concentration flue gas is subjected to conversion reaction (namely, carbon monoxide is combusted to generate carbon dioxide reaction), and the released heat is directly absorbed by the flue gas, thereby achieving the effect of temperature rise.
According to the characteristics of the high-CO-concentration flue gas, the high-CO-concentration flue gas is divided into three paths, the first path of flue gas is introduced into a main reaction tower for CO catalytic oxidation, the second path of flue gas is introduced into an adjusting tower for CO catalytic oxidation, and the third path of flue gas is directly conveyed through a bypass flue gas conveying pipeline. The temperature of the mixed flue gas of the three paths of flue gases is adjusted by controlling different flow rates of the three paths of flue gases, so that the temperature T of the mixed flue gas, namely the SCR reaction flue gas1Reach the temperature T of the SCR reaction windowIs suitable for。
The flue gas is subjected to catalytic oxidation of CO in the main reaction tower and the regulating tower, heat is released in the process, and the heat is directly absorbed by the flue gas, so that the temperature of the flue gas is increased. And the efficiency of CO catalytic oxidation of the flue gas in the main reaction tower and the regulating tower is directly related to the amount of the flue gas treated by the main reaction tower and the regulating tower. The less the flue gas treatment amount of the main reaction tower and the regulating tower is, the higher the catalytic oxidation efficiency of CO is, so that the flue gas amounts respectively entering the main reaction tower and the regulating tower can be regulated, the conversion rate of CO in the original flue gas (namely the flue gas with high CO concentration) is controlled, the temperature rise amount of the treated mixed flue gas is further controlled, namely the temperature of the mixed flue gas is controlled, the temperature of the flue gas before entering an SCR reactor is ensured, and the temperature T of the SCR reaction flue gas is ensured1Reach the temperature T of the SCR reaction windowIs suitable forAnd the best denitration effect is ensured.
According to the heat W increased by the mixed SCR reaction flue gas, the heat W comes from the heat W of the main reaction tower for CO catalytic oxidation1And regulating the tower to perform CO catalytic oxidation W2(ii) a Namely: w ═ W1+W2。
Figure BDA0002260665620000071
From the above calculation formula, the flue gas amount Q of the main reaction tower is adjusted1Regulating the flue gas quantity Q of the tower2Bypass flue gas conveying capacity Q3The temperature rise delta T of the flue gas after CO catalytic oxidation in the main reaction tower and CO catalytic oxidation in the regulating tower can be regulated, and the temperature T of the SCR reaction flue gas can be regulated1。
In the formula, as the constant a is a negative number, the delta T is maximized, namely CO in the flue gas is catalyzed and oxidized to the maximum extent, the heat emitted by CO in the flue gas is maximized, and the temperature rise of the mixed SCR reaction flue gas reaches the maximum value; is needed (Q)1 2+Q2 2) The value is smallest, and1 2+Q2 2)≥(Q1-Q2)2only when Q is1＝Q2When (Q)1 2+Q2 2) Minimum value. Therefore, the amount of flue gas conveyed into the regulating tower is regulated to be equal to the amount of flue gas in the main reaction tower, namely Q1＝Q2＝Q/2，Q3When the temperature of the mixed SCR reaction flue gas is equal to 0, CO in the flue gas is catalyzed and oxidized to the maximum degree under the process condition, the heat emitted by the CO in the flue gas is the maximum, and the temperature rise of the mixed SCR reaction flue gas reaches the maximum value.
In addition, according to the conversion amount of CO in the flue gas, the following can be obtained:
Figure BDA0002260665620000081
in the above formula, the constant a is a negative number, so that the conversion amount of CO is maximized, that is, CO in the flue gas is catalyzed and oxidized to the maximum extent; at the moment, the maximum heat released by CO in the flue gas is utilized, and the temperature rise of the SCR reaction flue gas reaches the maximum value after mixing. Is needed (Q)1 2+Q2 2) The value is smallest, and1 2+Q2 2)≥(Q1-Q2)2only when Q is1＝Q2When (Q)1 2+Q2 2) The value is minimal. Therefore, the amount of flue gas conveyed into the regulating tower is regulated to be equal to the amount of flue gas in the main reaction tower, namely Q1＝Q2＝Q/2，Q3When the temperature of the mixed SCR reaction flue gas is equal to 0, CO in the flue gas is catalyzed and oxidized to the maximum degree under the process condition, the heat emitted by the CO in the flue gas is the maximum, and the temperature rise of the mixed SCR reaction flue gas reaches the maximum value.
In the system, the main reaction tower, the adjusting tower and the bypass flue gas conveying pipeline are arranged, so that the amount of flue gas entering the main reaction tower, the adjusting tower and the bypass flue gas conveying pipeline can be respectively adjusted according to process requirements. When the flue gas completely enters the bypass flue gas conveying pipeline, CO in the flue gas is not subjected to catalytic oxidation, the temperature of the flue gas cannot be increased by utilizing the CO in the flue gas, and at the moment, the temperature of the flue gas conveyed to the SCR reactor is the temperature of the original flue gas. When the flue gas is regulated to enter the main reaction tower and the regulating tower, CO in the flue gas conveyed to the main reaction tower and the regulating tower is subjected to catalytic oxidation, heat is released by the CO in the main reaction tower and the regulating tower through catalytic oxidation, and the heat is directly absorbed by the flue gas, so that the temperature of the flue gas is increased, and the temperature of the flue gas before entering the SCR reactor is regulated. When the flue gas is completely input into the main reaction tower and the regulating tower, and the input flue gas amount in the main reaction tower and the regulating tower is the same, CO in the flue gas is catalyzed and oxidized to the maximum extent, the CO in the flue gas is utilized fully, the heat emitted by CO components in the flue gas is utilized most, namely, the temperature rise amount of the mixed flue gas reaches the maximum after passing through the main reaction tower and the regulating tower.
By adopting the technical scheme of the invention, the temperature T of the SCR reaction window is determinedIs suitable forThe temperature of the flue gas before entering the SCR reactor can be regulated by timely and accurately regulating the flue gas conveying amount of the high CO concentration, which is introduced into the main reaction tower for CO catalytic oxidation, the second flue gas is introduced into the regulating tower for CO catalytic oxidation, and the flue gas is directly conveyed by the bypass flue gas conveying pipeline, so that the denitration efficiency of the SCR is ensured; and effectively utilizes CO in the flue gas, reduces the emission of pollutants and fully utilizes energy resources.
In the treatment system provided by the invention, the high-CO-concentration flue gas can be detected by the original flue gas temperature measuring sensor, the original flue gas CO concentration detecting sensor and the original flue gas flow sensor. The flue gas volume conveyed into the main reaction tower is detected through the first gas flow sensor, the flue gas volume conveyed into the adjusting tower is detected through the second gas flow sensor, and the flue gas volume conveyed through the bypass flue gas conveying pipeline is detected through the third gas flow sensor. The amount of the flue gas conveyed into the main reaction tower is adjusted through the first air valve and the fourth air valve, the amount of the flue gas conveyed into the adjusting tower is adjusted through the second air valve and the fifth air valve, and the amount of the flue gas conveyed through the bypass flue gas conveying pipeline is adjusted through the third air valve.
In the treatment system provided by the invention, when the amount of the flue gas conveyed into the regulating tower is equal to the amount of the flue gas in the main reaction tower, namely Q is1＝Q2＝Q/2，Q3When T is equal to 0, if T is present1Is still less than TIs suitable forThe mixed SCR reaction smoke is heated by an external heat source, so that the SCR reaction detected in timeTemperature T of flue gas1Reach the temperature T of the SCR reaction windowIs suitable for. High-temperature gas can be input into the fifth pipeline through the combustion of the hot blast stove, and the temperature of the flue gas before entering the SCR reactor is adjusted to reach the temperature T of the SCR reaction windowIs suitable for。
Preferably, the gas combustion amount of the hot blast stove is controlled according to the temperature of the flue gas in the fifth pipeline detected by the second temperature measuring sensor.
In this application, the high CO concentration flue gas includes desulfurized flue gas. The technical scheme of the invention is suitable for any flue gas desulfurization and denitration process and is also suitable for any flue gas. The carbon monoxide treatment system of the present invention may be any treatment system known in the art for catalyzing the conversion of carbon monoxide.
In the present invention, the main reaction tower and the conditioning tower are of a box structure, a tower structure or a tubular structure. The main reaction tower and the regulating tower comprise a catalyst layer, a flue gas inlet and a flue gas outlet.
Preferably, the height of the main reaction column and the height of the conditioning column are from 1 to 50m, preferably from 2 to 45m, more preferably from 3 to 40 m.
Preferably, the height of the CO catalyst layer in the main reaction column and the rectifying column is 5 to 90%, preferably 8 to 80%, more preferably 10 to 60% of the height of the main reaction column and the rectifying column.
Compared with the prior art, the invention has the following beneficial effects:
1. according to the technical scheme, the temperature of the flue gas entering the SCR reactor is controlled within a certain temperature window through a device for regulating and controlling the CO conversion heat production quantity and a control system.
2. According to the invention, by arranging the regulating tower, when the catalyst in the CO reaction tower is poisoned and needs to be replaced or regenerated, the CO reaction regulating tower can be used as a CO regeneration reaction site, so that the system is not stopped.
3. According to the technical scheme, when the temperature of the flue gas at the denitration inlet is lower than the target value, the regulating tower can be used for flue gas shunting, namely the volume of the catalyst is increased, the reaction space velocity is reduced, the CO conversion rate is increased, and the heat production quantity is increased.
4. According to the technical scheme, when the temperature adjusting function of the standby tower reaches the maximum, the hot blast stove can be used as a guarantee measure for further heating of the flue gas.
5. According to the technical scheme, when the temperature of the flue gas at the denitration inlet is higher than the target value, the flue gas bypass can be used for flue gas shunting, namely the total amount of CO participating in CO catalytic oxidation is reduced, and the heat production quantity is reduced.
Drawings
FIG. 1 is a flow chart of a high CO concentration flue gas coupling low temperature SCR temperature control method of the present invention;
FIG. 2 is a schematic diagram of the judgment in the high CO concentration flue gas coupling low temperature SCR temperature control method of the present invention;
FIG. 3 is a schematic structural diagram of a high CO concentration flue gas coupling low temperature SCR temperature control processing system according to the present invention;
FIG. 4 is a plot of CO conversion versus space velocity for a catalytic CO oxidation process.
Reference numerals:
1: a main reaction tower; 2: a conditioning tower; 3: a bypass flue gas conveying pipeline; 4: a hot blast stove; 5: an SCR reactor; k1: a first air valve; k2: a second air valve; k3: a third air valve; k4: a fourth air valve; k5: a fifth air valve; t0: a raw flue gas temperature sensor; n0: a raw flue gas CO concentration detection sensor; g0: a raw flue gas flow sensor; g1: a first gas flow sensor; g2: a second gas flow sensor; g3: a third gas flow sensor; t1: a first temperature sensor; t2: a second temperature measuring sensor; l0: a total flue gas duct; l1: a first conduit; l2: a second conduit; l3: a third pipeline; l4: a fourth conduit; l5: a fifth pipeline; l6: and a sixth pipeline.
Detailed Description
According to the embodiment of the invention, a high CO concentration flue gas coupling low-temperature SCR temperature control treatment system is provided.
A system for coupling high CO concentration flue gas with low temperature SCR temperature control treatment comprises: a CO main reaction tower 1, a CO adjusting tower 2 and a bypass flue gas conveying pipeline 3. The total flue gas pipeline L0 through which the flue gas with high CO concentration is introduced is divided into three paths: the main CO reaction tower 1 is connected through a first pipeline L1, the CO regulating tower 2 is connected through a second pipeline L2, and the bypass flue gas conveying pipeline 3 is connected. The CO main reaction tower 1 discharges flue gas after CO catalytic oxidation through a third pipeline L3, and the CO regulating tower 2 discharges flue gas after CO catalytic oxidation through a fourth pipeline L4. The tail ends of the third pipeline L3, the fourth pipeline L4 and the bypass smoke conveying pipeline 3 are combined and connected into a fifth pipeline L5. The end of the fifth pipe L5 is connected to the SCR reactor 5.
Preferably, the first pipeline L1 is provided with a first air valve K1. The second pipeline L2 is provided with a second air valve K2. And a third air valve K3 is arranged on the bypass flue gas conveying pipeline 3.
Preferably, the apparatus further comprises: a raw flue gas temperature measuring sensor T0, a raw flue gas CO concentration detecting sensor N0, a raw flue gas flow sensor G0, a first gas flow sensor G1, a second gas flow sensor G2 and a third gas flow sensor G3. The original flue gas temperature measurement sensor T0, the original flue gas CO concentration detection sensor N0 and the original flue gas flow sensor G0 are arranged on the total flue gas pipeline L0. The first gas flow sensor G1 is disposed on the first pipe L1. A second gas flow sensor G2 is provided on the second conduit L2. A third gas flow sensor G3 is provided on the bypass flue gas conveying duct 3. The fifth pipeline L5 is provided with a first temperature sensor T1.
Preferably, the third line L3 is provided with a fourth air valve K4. A fifth air valve K5 is provided on the fourth pipeline L4.
Preferably, the apparatus further comprises: and a hot blast stove 4. The air outlet of the hot blast stove 4 is connected to a fifth conduit L5 via a sixth line L6.
Preferably, a second temperature sensor T2 is provided on the fifth pipeline L5 downstream of the connection position of the sixth pipeline L6.
Example 1
As shown in fig. 3, a system for coupling a high CO concentration flue gas with a low temperature SCR temperature control process includes: a CO main reaction tower 1, a CO adjusting tower 2 and a bypass flue gas conveying pipeline 3. The total flue gas pipeline L0 through which the flue gas with high CO concentration is introduced is divided into three paths: the main CO reaction tower 1 is connected through a first pipeline L1, the CO regulating tower 2 is connected through a second pipeline L2, and the bypass flue gas conveying pipeline 3 is connected. The CO main reaction tower 1 discharges flue gas after CO catalytic oxidation through a third pipeline L3, and the CO regulating tower 2 discharges flue gas after CO catalytic oxidation through a fourth pipeline L4. The tail ends of the third pipeline L3, the fourth pipeline L4 and the bypass smoke conveying pipeline 3 are combined and connected into a fifth pipeline L5. The end of the fifth pipe L5 is connected to the SCR reactor 5.
Example 2
Example 1 was repeated except that the first conduit L1 was provided with a first air valve K1. The second pipeline L2 is provided with a second air valve K2. And a third air valve K3 is arranged on the bypass flue gas conveying pipeline 3.
Example 3
Example 2 was repeated except that the apparatus further included: a raw flue gas temperature measuring sensor T0, a raw flue gas CO concentration detecting sensor N0, a raw flue gas flow sensor G0, a first gas flow sensor G1, a second gas flow sensor G2 and a third gas flow sensor G3. The original flue gas temperature measurement sensor T0, the original flue gas CO concentration detection sensor N0 and the original flue gas flow sensor G0 are arranged on the total flue gas pipeline L0. The first gas flow sensor G1 is disposed on the first pipe L1. A second gas flow sensor G2 is provided on the second conduit L2. A third gas flow sensor G3 is provided on the bypass flue gas conveying duct 3. The fifth pipeline L5 is provided with a first temperature sensor T1.
Example 4
Example 3 was repeated except that the third line L3 was provided with the fourth air valve K4. A fifth air valve K5 is provided on the fourth pipeline L4.
Example 5
Example 4 was repeated except that the fifth pipeline L5 was provided with a second temperature sensor T2 downstream of the connection point of the sixth pipeline L6.
Example 6
As shown in fig. 1, a method for controlling the temperature of a high CO concentration flue gas coupled with a low-temperature SCR includes the following steps:
1) identifying and obtaining the total smoke quantity Q of the smoke with high CO concentration, the CO concentration C in the smoke with high CO concentration and the temperature T of the smoke with high CO concentration0；
2) Dividing the high CO concentration flue gas into three paths, introducing the first path of flue gas into a main reaction tower for CO catalytic oxidationAnd the flue gas volume of the main reaction tower is marked as Q1(ii) a Introducing the second path of flue gas into an adjusting tower for CO catalytic oxidation, and recording the flue gas volume of the adjusting tower as Q2(ii) a The third path of flue gas is directly conveyed through a bypass flue gas conveying pipeline, and the conveying amount of the bypass flue gas is recorded as Q3；
3) Mixing the flue gas discharged after CO catalytic oxidation of the main reaction tower, the flue gas discharged after CO catalytic oxidation of the regulating tower and the flue gas in the bypass flue gas conveying pipeline to obtain SCR reaction flue gas, wherein the temperature of the mixed SCR reaction flue gas is T1；
4) Controlling the quantity Q of flue gas introduced into the regulating tower2And the amount of flue gas Q introduced into the bypass flue gas conveying pipeline3Thereby adjusting the temperature T of the mixed SCR reaction flue gas1So that the temperature T of the SCR reaction flue gas1Reach the temperature T of the SCR reaction windowIs suitable for。
Example 7
In the process of the embodiment 6, the heat W increased according to the mixed SCR reaction flue gas comes from the heat W of the main reaction tower for CO catalytic oxidation1And regulating the tower to perform CO catalytic oxidation W2(ii) a Namely:
W＝W1+W2。
the temperature rise delta T of the flue gas after the CO catalytic oxidation in the main reaction tower and the CO catalytic oxidation in the regulating tower is as follows:
Figure BDA0002260665620000121
according to the CO catalytic oxidation process, the following steps are provided:
W1＝Q1·C·f(GHSV1)·η……II；
W2＝Q2·C·f(GHSV2)·η……III；
f(GHSV1)＝a·GHSV1+k……IV；
f(GHSV2)＝a·GHSV2+k……V；
GHSV1＝Q1/V……VI；
GHSV2＝Q2/V……VII；
to obtain:
Figure BDA0002260665620000122
wherein: q: the total smoke gas amount of the smoke gas with high CO concentration; q1: the flue gas amount of the main reaction tower; q2: adjusting the flue gas amount of the tower; q3The conveying capacity of the bypass flue gas is obtained; cp: specific heat capacity of flue gas; delta T: the variation of the flue gas temperature before and after CO catalytic oxidation; f (GHSV 1): the CO catalytic oxidation conversion rate of the main reaction tower; f (GHSV 2): adjusting the catalytic oxidation conversion rate of CO under the tower; a is a relation constant of space velocities in the main reaction tower and the regulating tower and the CO catalytic oxidation conversion rate, and is a negative value; k is a reaction constant of space velocities in the main reaction tower and the regulating tower and the catalytic oxidation conversion rate of CO, and is a positive value; GHSV1: space velocity of main reaction tower, GHSV1 ∈ [5000,20000 ]]；GHSV2: adjusting the reaction space velocity of the tower, GHSV 2E [5000,20000 ]](ii) a V: the filling amount of the catalyst in the main reaction tower and the regulating tower; w1: the main reaction tower generates heat; w2: regulating the heat production of the tower; c: the CO concentration in the flue gas with high CO concentration; eta: conversion of CO to CO at Unit flow2The heat evolution.
According to the formula VIII, the flue gas quantity Q of the main reaction tower is adjusted1Regulating the flue gas quantity Q of the tower2Bypass flue gas conveying capacity Q3The temperature rise delta T of the flue gas after CO catalytic oxidation in the main reaction tower and CO catalytic oxidation in the regulating tower can be regulated, and the temperature T of the SCR reaction flue gas can be regulated1。
Example 8
Example 7 was repeated, except that the flue gas having a high CO concentration was adjusted to be fed entirely into the main reaction column so that Q was1＝Q，Q2＝Q3When the smoke gas is 0, CO catalytic oxidation is carried out on the smoke gas through the main reaction tower, and then the SCR reaction smoke gas after CO catalytic oxidation is conveyed to the SCR reactor; and (3) judging:
a) when T is1Greater than TIs suitable forDuring the process, the flue gas with high CO concentration is respectively conveyed to a main reaction tower and a bypass conveying pipeline by regulation, and the flue gas is gradually regulated and conveyed into the main reaction tower and the bypass conveying pipelineThe flue gas amount entering the bypass conveying pipe is as follows: q1Is gradually decreased, Q3Gradually increasing; so that the temperature T of the SCR reaction flue gas detected in time1Reach the temperature T of the SCR reaction windowIs suitable for；
b) When T is1Is equal to TIs suitable forAnd (3) keeping the existing operation condition, namely: q1＝Q，Q2＝Q30; the high CO concentration flue gas completely enters a main reaction tower;
c) when T is1Less than TIs suitable forDuring the process, the flue gas with high CO concentration is respectively conveyed to the main reaction tower and the regulating tower by regulation, the flue gas volume conveyed into the regulating tower is gradually regulated, namely: q1Is gradually decreased, Q2Gradually increase, Q30; so that the temperature T of the SCR reaction flue gas detected in time1Reach the temperature T of the SCR reaction windowIs suitable for。
Example 9
Example 8 is repeated, except that in step c), when the amount of flue gas fed into the regulating column is regulated to be equal to the amount of flue gas in the main reaction column, Q1＝Q2Q/2; according to the formula VIII, a is a negative number, and the temperature rise delta T at the moment is the maximum value, namely CO in the flue gas is catalyzed and oxidized to the maximum extent, the heat emitted by CO in the flue gas is the maximum, and the temperature rise of the mixed SCR reaction flue gas reaches the maximum value; if T is at this time1Is still less than TIs suitable forThe mixed SCR reaction smoke is heated by an external heat source, so that the temperature T of the SCR reaction smoke detected in time1Reach the temperature T of the SCR reaction windowIs suitable for。
Example 10
Example 8 is repeated, except that in step c), the total CO conversion Z in the flue gas isGeneral assemblySatisfies the formula:
Zgeneral assembly＝Q1·C·f(GHSV1)+Q2·C·f(GHSV2)……IX；
Derived from the above equation:
Figure BDA0002260665620000131
according to the formula X, a is a negative number, and under the condition that the total flue gas flow Q is not changed, when Q is used1＝Q2When Q/2, the total CO conversion Z in the flue gasGeneral assemblyThe maximum, namely the CO in the flue gas is catalyzed and oxidized to the maximum extent, and the heat emitted by the CO in the flue gas is utilized to the maximum extent; if T is at this time1Is still less than TIs suitable forThe mixed SCR reaction smoke is heated by an external heat source, so that the temperature T of the SCR reaction smoke detected in time1Reach the temperature T of the SCR reaction windowIs suitable for。
Example 11
Example 9 is repeated except that the external heat source is a hot blast stove connected to the conveying pipeline of the SCR reaction flue gas, and the high-temperature flue gas generated by the hot blast stove is mixed with the mixed SCR reaction flue gas to increase the temperature of the flue gas entering the SCR reactor. The SCR reaction window temperature T is suitably 150-200 ℃.
Example 12
Example 10 is repeated except that the external heat source is a hot blast stove connected to the conveying pipeline of the SCR reaction flue gas, and the high-temperature flue gas generated by the hot blast stove is mixed with the mixed SCR reaction flue gas to increase the temperature of the flue gas entering the SCR reactor. The SCR reaction window temperature T is suitably 150-200 ℃.

Claims (11)

1. A high CO concentration flue gas coupling low temperature SCR temperature control method is characterized in that: the method comprises the following steps:
1) identifying and obtaining the total smoke quantity Q of the smoke with high CO concentration, the CO concentration C in the smoke with high CO concentration and the temperature T of the smoke with high CO concentration0；
2) Dividing the high CO concentration flue gas into three paths, introducing the first path of flue gas into a main reaction tower for CO catalytic oxidation, and recording the flue gas amount of the main reaction tower as Q1(ii) a Introducing the second path of flue gas into an adjusting tower for CO catalytic oxidation, and recording the flue gas volume of the adjusting tower as Q2(ii) a The third path of flue gas is directly conveyed through a bypass flue gas conveying pipeline, and the conveying amount of the bypass flue gas is recorded as Q3；
3) The flue gas and the fuel discharged after the CO in the main reaction tower is catalyzed and oxidizedMixing flue gas discharged after CO catalytic oxidation of the tower section with flue gas in a bypass flue gas conveying pipeline to obtain SCR reaction flue gas, wherein the temperature of the mixed SCR reaction flue gas is T1；
4) Controlling the quantity Q of flue gas introduced into the regulating tower2And the amount of flue gas Q introduced into the bypass flue gas conveying pipeline3Thereby adjusting the temperature T of the mixed SCR reaction flue gas1So that the temperature T of the SCR reaction flue gas1Reach the temperature T of the SCR reaction windowIs suitable for。
2. The high CO concentration flue gas coupling low temperature SCR temperature control method of claim 1, wherein: according to the heat W increased by the mixed SCR reaction flue gas, the heat W comes from the heat W of the main reaction tower for CO catalytic oxidation1And regulating the tower to perform CO catalytic oxidation W2(ii) a Namely:
W＝W1+W2；
the temperature rise delta T of the flue gas after the CO catalytic oxidation in the main reaction tower and the CO catalytic oxidation in the regulating tower is as follows:
Figure FDA0002260665610000011
according to the CO catalytic oxidation process, the following steps are provided:
W1＝Q1·C·f(GHSV1)·η……II；
W2＝Q2·C·f(GHSV2)·η……III；
f(GHSV1)＝a·GHSV1+k……IV；
f(GHSV2)＝a·GHSV2+k……V；
GHSV1＝Q1/V……VI；
GHSV2＝Q2/V……VII；
to obtain:
Figure FDA0002260665610000012
wherein: q: the total smoke gas amount of the smoke gas with high CO concentration; q1: the flue gas amount of the main reaction tower; q2: adjusting the flue gas amount of the tower; q3The conveying capacity of the bypass flue gas is obtained; cp: specific heat capacity of flue gas; delta T: the variation of the flue gas temperature before and after CO catalytic oxidation; f (GHSV 1): the CO catalytic oxidation conversion rate of the main reaction tower; f (GHSV 2): adjusting the catalytic oxidation conversion rate of CO in the tower; a is a relation constant of space velocities in the main reaction tower and the regulating tower and the CO catalytic oxidation conversion rate, and is a negative value; k is a reaction constant of space velocities in the main reaction tower and the regulating tower and the catalytic oxidation conversion rate of CO, and is a positive value; GHSV1: space velocity of main reaction tower, GHSV1 ∈ [5000,20000 ]]；GHSV2: adjusting the reaction space velocity of the tower, GHSV 2E [5000,20000 ]](ii) a V: the filling amount of the catalyst in the main reaction tower and the regulating tower; w1: the main reaction tower generates heat; w2: regulating the heat production of the tower; c: the CO concentration in the flue gas with high CO concentration; eta: conversion of CO to CO at Unit flow2The heat evolution.
3. The high CO concentration flue gas coupling low temperature SCR temperature control method of claim 2, wherein: according to the formula VIII, the flue gas quantity Q of the main reaction tower is adjusted1Regulating the flue gas quantity Q of the tower2Bypass flue gas conveying capacity Q3The temperature rise delta T of the flue gas after CO catalytic oxidation in the main reaction tower and CO catalytic oxidation in the regulating tower can be regulated, and the temperature T of the SCR reaction flue gas can be regulated1。
4. The high CO concentration flue gas coupling low temperature SCR temperature control method of claim 3, wherein: regulating to make the high CO concentration fume completely enter the main reaction tower to make Q1＝Q，Q2＝Q3When the smoke gas is 0, CO catalytic oxidation is carried out on the smoke gas through the main reaction tower, and then the SCR reaction smoke gas after CO catalytic oxidation is conveyed to the SCR reactor; and (3) judging:
a) when T is1Greater than TIs suitable forDuring the time, adjust and carry high CO concentration flue gas to main reaction tower and bypass pipeline respectively, adjust gradually and carry the flue gas volume that gets into bypass pipeline, promptly:Q1is gradually decreased, Q3Gradually increasing; so that the temperature T of the SCR reaction flue gas detected in time1Reach the temperature T of the SCR reaction windowIs suitable for；
b) When T is1Is equal to TIs suitable forAnd (3) keeping the existing operation condition, namely: q1＝Q，Q2＝Q30; the high CO concentration flue gas completely enters a main reaction tower;
c) when T is1Less than TIs suitable forDuring the process, the flue gas with high CO concentration is respectively conveyed to the main reaction tower and the regulating tower by regulation, the flue gas volume conveyed into the regulating tower is gradually regulated, namely: q1Is gradually decreased, Q2Gradually increase, Q30; so that the temperature T of the SCR reaction flue gas detected in time1Reach the temperature T of the SCR reaction windowIs suitable for。
5. The high CO concentration flue gas coupling low temperature SCR temperature control method of claim 4, wherein: in the step c), when the amount of the flue gas conveyed into the regulating tower is equal to that in the main reaction tower, Q is obtained1＝Q2Q/2; according to the formula VIII, a is a negative number, and the temperature rise delta T at the moment is the maximum value, namely CO in the flue gas is catalyzed and oxidized to the maximum extent, the heat emitted by CO in the flue gas is the maximum, and the temperature rise of the mixed SCR reaction flue gas reaches the maximum value; if T is at this time1Is still less than TIs suitable forThe mixed SCR reaction smoke is heated by an external heat source, so that the temperature T of the SCR reaction smoke detected in time1Reach the temperature T of the SCR reaction windowIs suitable for。
6. The high CO concentration flue gas coupling low temperature SCR temperature control method of claim 4, wherein: in step c), the total CO conversion Z in the flue gasGeneral assemblySatisfies the formula:
Zgeneral assembly＝Q1·C·f(GHSV1)+Q2·C·f(GHSV2)……IX；
Derived from the above equation:
Figure FDA0002260665610000031
according to the formula X, a is a negative number, and under the condition that the total flue gas flow Q is not changed, when Q is used1＝Q2When Q/2, the total CO conversion Z in the flue gasGeneral assemblyThe maximum, namely the CO in the flue gas is catalyzed and oxidized to the maximum extent, and the heat emitted by the CO in the flue gas is utilized to the maximum extent; if T is at this time1Is still less than TIs suitable forThe mixed SCR reaction smoke is heated by an external heat source, so that the temperature T of the SCR reaction smoke detected in time1Reach the temperature T of the SCR reaction windowIs suitable for。
7. The high CO concentration flue gas coupling low-temperature SCR temperature control method of claim 5 or 6, wherein: the external heat source is characterized in that a hot blast stove is connected to a conveying pipeline of the SCR reaction flue gas, and the high-temperature flue gas generated by the hot blast stove is mixed with the mixed SCR reaction flue gas to improve the temperature of the flue gas entering the SCR reactor; and/or
The SCR reaction window temperature T is suitably 150-200 ℃.
8. A system for applying the high CO concentration flue gas coupling low temperature SCR temperature control method of any one of claims 1-7, characterized in that the system comprises: a CO main reaction tower (1), a CO adjusting tower (2) and a bypass flue gas conveying pipeline (3); the total flue gas pipeline (L0) which is introduced with the flue gas with high CO concentration is divided into three paths: the device is connected with a CO main reaction tower (1) through a first pipeline (L1), a second pipeline (L2) is connected with a CO adjusting tower (2), and a bypass flue gas conveying pipeline (3) respectively; the CO main reaction tower (1) discharges flue gas subjected to CO catalytic oxidation through a third pipeline (L3), and the CO regulating tower (2) discharges flue gas subjected to CO catalytic oxidation through a fourth pipeline (L4); the tail ends of the third pipeline (L3), the fourth pipeline (L4) and the bypass flue gas conveying pipeline (3) are combined and connected into a fifth pipeline (L5), and the tail end of the fifth pipeline (L5) is connected to the SCR reactor (5).
9. The high CO concentration flue gas coupling low temperature SCR temperature control device of claim 8, characterized in that: a first air valve (K1) is arranged on the first pipeline (L1), a second air valve (K2) is arranged on the second pipeline (L2), and a third air valve (K3) is arranged on the bypass flue gas conveying pipeline (3).
10. The high CO concentration flue gas coupling low temperature SCR temperature control device of claim 8 or 9, further comprising: a raw flue gas temperature measuring sensor (T0), a raw flue gas CO concentration detecting sensor (N0), a raw flue gas flow sensor (G0), a first gas flow sensor (G1), a second gas flow sensor (G2) and a third gas flow sensor (G3); a raw flue gas temperature measuring sensor (T0), a raw flue gas CO concentration detection sensor (N0) and a raw flue gas flow sensor (G0) are arranged on the total flue gas pipeline (L0); the first gas flow sensor (G1) is disposed on a first conduit (L1); a second gas flow sensor (G2) is arranged on the second pipeline (L2), and a third gas flow sensor (G3) is arranged on the bypass flue gas conveying pipeline (3); the fifth pipeline (L5) is provided with a first temperature measuring sensor (T1).
11. The high CO concentration flue gas coupling low temperature SCR temperature control device of any one of claims 8-10, wherein: a fourth air valve (K4) is arranged on the third pipeline (L3), and a fifth air valve (K5) is arranged on the fourth pipeline (L4); and/or
The device also includes: the air outlet of the hot blast stove (4) is connected to the fifth pipeline (L5) through a sixth pipeline (L6); preferably, a second temperature sensor (T2) is provided on the fifth line (L5) downstream of the connection point of the sixth line (L6).
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