CN112156593A - Lime kiln flue gas treatment system and treatment process thereof - Google Patents
Lime kiln flue gas treatment system and treatment process thereof Download PDFInfo
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- CN112156593A CN112156593A CN202011143201.9A CN202011143201A CN112156593A CN 112156593 A CN112156593 A CN 112156593A CN 202011143201 A CN202011143201 A CN 202011143201A CN 112156593 A CN112156593 A CN 112156593A
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Abstract
The invention discloses a lime kiln flue gas treatment system, which comprises a dust remover connected with a lime kiln through an inlet flue, and further comprises an atomized water generation device with an injection end arranged in the inlet flue, wherein an atomized water injection control device is connected between the atomized water generation device and the inlet flue, an outlet flue of the dust remover is connected to an SCR (selective catalytic reduction) reactor, and an induced draft fan and a flue gas temperature lifting device are arranged on the outlet flue; the invention can achieve the purpose of flue gas desulfurization by spraying a small amount of atomized water, and does not need to additionally add a desulfurizing agent and desulfurization equipment, thereby simplifying the installation of the equipment; in the denitration process, the flue gas temperature is raised, medium-low temperature SCR denitration is realized, the using amount of the catalyst is reduced by more than 30% compared with that of a pure low-temperature catalyst, deposition of ammonium sulfate and adhesion of the surface of the catalyst can be delayed, the service life of the catalyst is prolonged, capital investment of an SCR reactor is reduced, and long-term safe and stable standard reaching of the discharge value of the lime kiln is ensured.
Description
Technical Field
The invention relates to the technical field of flue gas treatment in enterprise production, in particular to a lime kiln flue gas treatment system and a specific treatment process of the system.
Background
With the steady pace of the national adherence to the green sustainable development, some heavily-polluted enterprises respond to the national call, reform and optimally upgrade the homeopathic resources, and make due contribution in the aspect of executing the environment-friendly ultralow emission modification, and the environment-friendly upgrade modification of the lime kiln for building material production is one of the heavily-polluted enterprises.
The lime kiln flue gas for building material production is characterized in that:
1) the range of the change of the exhaust gas temperature is large and is generally between 80 and 160 ℃;
2) the dust concentration is lower than that of the smoke discharged by the general thermal power industry, and the highest dust concentration is about 10g/Nm3The dust components mainly comprise CaO and MgO, and the total mass ratio of the CaO and the MgO is more than 70%;
3) the concentration of the sulfur dioxide is less than or equal to 200mg/Nm3The concentration of nitrogen oxide is less than or equal to 300mg/Nm3；
In order to achieve the environmental protection ultra-low emission limit value, the commonly used treatment scheme of the flue gas of the lime kiln for building material production at present is SDS dry desulfurization and low-temperature SCR denitration. However, the flue gas temperature required by the SDS dry desulfurization treatment process is more than or equal to 140 ℃, sodium-based sodium bicarbonate can only perform popcorn type reaction with sulfur dioxide at the temperature to remove sulfur dioxide, and when the kiln tail flue gas temperature does not reach the temperature, the desulfurization reaction rate can be greatly reduced, so that in order to ensure the emission limit value, the desulfurization efficiency can be improved only by spraying more sodium bicarbonate, the flue gas treatment cost of an enterprise is increased undoubtedly, in addition, the sodium-based desulfurization agent has toxic effect on iron making, and the sodium-based desulfurization agent is introduced into the sodium-based desulfurization agent, so that the recovered desulfurization ash can not be directly used as a lime additive of a sintering plant, and can only be recovered and treated by a factory which has danger of recovering solid wastes, and the generated recovery cost also becomes part of the production cost of the industry. The low-temperature denitration catalyst is more sensitive to sodium, calcium and other components in flue gas, the alkali metal occupies the active center of the catalyst to cause the activity of the catalyst to be reduced, and when the flue gas temperature is below 200 ℃, the temperature interval generated by ammonium sulfate salt is just the temperature interval, ammonium sulfate salt is adhered to catalyst pores to cause the pore blockage of the catalyst and the inactivation of the catalyst, the catalyst needs to be periodically heated and regenerated to ensure the denitration efficiency to a certain extent, so that the production cost of an enterprise cannot be reduced.
By utilizing active ingredients such as CaO, MgO and the like in the dust and adding a certain amount of activated water, when the temperature of the flue gas is ensured to be higher than the condensation temperature plus 20 ℃, the activated CaO and MgO carry out a chemical combination reaction with SO2 in the flue gas, SO that SO2 is removed; medium-low temperature SCR denitration is adopted for denitration, and the reaction temperature of the catalyst is improved by heat exchange and/or heating equipment on the premise of reducing energy consumption as much as possible, so that the temperature interval for generating the ammonium sulfate salt is avoided, and the service life of the catalyst is prolonged; in the long-term operation, the method is favorable for the safety, stability and ultralow standard reaching of the lime kiln, reduces the overall capital investment and saves the operation cost.
Disclosure of Invention
The invention aims to solve the technical problem of providing a lime kiln flue gas treatment system which does not use a desulfurization catalyst, has less denitration catalyst consumption, less equipment investment and low operation cost.
In order to solve the technical problems, the technical scheme of the invention is as follows: lime kiln flue gas processing system, including the dust remover, the inlet flue of dust remover is connected to the exhanst gas port of lime kiln, still includes atomized water and generates the device, the injection end that atomized water generated the device is located in the inlet flue, atomized water generate the device with still be connected with atomized water injection controlling means between the inlet flue, the outlet flue of dust remover is connected to the SCR reactor, install draught fan and flue gas temperature hoisting device in proper order along flue gas advancing direction on the outlet flue.
According to a preferable technical scheme, the atomized water generating device comprises a process water tank, a process water pump is installed on a water outlet pipeline of the process water tank, injection pipes are arranged on the water outlet pipeline at the water outlet end of the process water pump in parallel, the end parts of the injection pipes are respectively connected with a double-fluid spray gun, the injection ends of the double-fluid spray guns are arranged in the inlet flue, the outer ends of the double-fluid spray guns are also communicated with a gas storage tank, and the gas storage tank is connected to a high-pressure gas source.
As a preferred technical scheme, the atomized water spray control device comprises a thermal resistor and an online CEMS instrument which are sequentially installed on the inlet flue, the thermal resistor and the online CEMS instrument are respectively connected to the input end of the atomized water spray controller, and the atomized water spray control device further comprises an electromagnetic flowmeter and an electric regulating valve which are connected in series on the water outlet pipeline, and the electromagnetic flowmeter and the electric regulating valve are respectively connected to the output end of the atomized water spray controller.
As a preferred technical scheme, the water outlet pipeline is also connected with a manual regulating valve, and the manual regulating valve and the electric regulating valve are arranged in parallel; and a gas supply control valve is connected in series on a pipeline between the gas storage tank and the double-fluid spray gun and is connected to the output end of the atomized water spray controller.
As a preferable technical solution, the thermal resistor and the online CEMS meter are respectively disposed between the two-fluid spray gun and the dust remover.
As a preferable technical scheme, the flue gas temperature raising device comprises a built-in pipeline burner arranged in the outlet flue, and the built-in pipeline burner is respectively connected to a combustion gas source and a combustion-supporting blower arranged outside the outlet flue through pipelines.
As a preferable technical scheme, the flue gas temperature raising device comprises a static mixer communicated with a flue gas inlet end of the SCR reactor, the flue gas inlet end of the static mixer is connected in parallel with a heat exchanger and a hot blast stove, a heat exchange channel communicated with the static mixer of the heat exchanger is connected to the outlet flue, and another heat exchange channel of the heat exchanger is connected to a flue gas outlet end of the SCR reactor.
The invention also discloses a treatment process of the lime kiln flue gas treatment system, which comprises a desulfurization process and a denitration process, wherein the desulfurization process is arranged on the flue gas inlet side of the dust remover, and the denitration process is arranged on the flue gas exhaust side of the dust remover;
the desulfurization process utilizes the reaction of atomized water and active ingredients CaO and MgO in the lime kiln flue gas to respectively generate Ca (OH)2、Mg(OH)2Using Ca (OH)2、Mg(OH)2With SO in lime kiln flue gas2Reacting to realize flue gas desulfurization, comprising the following steps:
S1-1presetting a reaction formula related to the desulfurization process in the atomized water injection controller,
CaO+H2O＝Ca(OH)2；
MgO+H2O＝Mg(OH)2；
calculating the reference water spraying amount by matching the atomized water spraying controller with the reaction formula;
presetting a smoke exhaust temperature monitoring limit value, namely the smoke dew point temperature plus 20 ℃, in the atomized water injection controller, wherein the real-time detection value of the thermal resistor is not less than the smoke dew point temperature plus 20 ℃ in the whole desulfurization process, or else, entering S1-6；
S1-2The atomized water spraying controller controls the electric regulating valve to be opened, the atomized water is matched with high-pressure gas sent by the gas storage tank and enters the double-fluid spray gun, the double-fluid spray gun mixes water and the high-pressure gas to atomize water and sprays the atomized water into the inlet flue, the atomized water reacts with CaO and MgO in the lime kiln smoke to generate calcium hydroxide and magnesium hydroxide and release heat;
S1-3calcium hydroxide, magnesium hydroxide and SO in lime kiln flue gas2Reacting to generate a desulfurization product;
the thermal resistor detects the temperature of the flue gas at the air inlet end of the dust remover in real time and transmits the temperature to the atomized water spraying controller;
the online CEMS instrument detects SO in the flue gas at the air inlet end of the dust remover in real time2And transmitted to the atomized water spray controller;
the electromagnetic flow meter detects the water yield of the water outlet pipeline in real time to obtain the actual water spraying amount, and transmits the actual water spraying amount to the atomized water spraying controller;
S1-4comparing the reference water spraying amount with the actual water spraying amount by using the atomized water spraying controller, and judging SO in the flue gas by using the atomized water spraying controller when the actual water spraying amount is less than the reference water spraying amount2When the emission concentration reaches the ultralow emission standard, the atomized water injection controller controls the opening degree of the electric regulating valve to be reduced, and the detection value of the thermal resistor is increased;
when the actual water spraying amount is larger than or equal to the reference water spraying amount, the atomized water spraying controller judges SO in the flue gas2When the emission concentration does not reach the ultralow emission standard, the atomized water injection controller controls the opening of the electric regulating valve to increase;
S1-5and step S1-3The generated desulfurization product enters the dust remover, the dust remover intercepts the desulfurization product generated by reaction, calcium hydroxide which is not completely reacted, magnesium hydroxide which is not completely reacted and dust in the lime kiln smoke, a filter cake layer is formed on the inner wall of the dust remover, and the filter cake layer and SO (sulfur oxide) remained in the lime kiln smoke2Continuing to react to complete the flue gas desulfurization;
S1-6lengthening the length of the inlet flue or/and increasing the inner diameter of the inlet flue;
the denitration process comprises the following steps:
S2-1and feeding the flue gas in the dust remover into the SCR reactor by using the outlet flue and the induced draft fan, and when the flue gas flows through the flue gas temperature lifting device, lifting the temperature of the flue gas by using the flue gas temperature lifting device to ensure that the temperature of the flue gas entering the SCR reactor is not lower than 260 ℃, avoiding a temperature interval for generating ammonium sulfate salt, and completing denitration after the flue gas passes through the SCR reactor and directly discharging the denitration gas to the outside.
As an improvement to the technical scheme, SO in the lime kiln flue gas2Is initially richDegree less than or equal to 200mg/Nm3。
Due to the adoption of the technical scheme, the invention has the following beneficial effects: according to the self component characteristics and the reaction heat release characteristics of the lime kiln flue gas, the aim of flue gas desulfurization can be achieved by controlling and spraying a small amount of atomized water through chemical formula balance calculation without additionally adding a desulfurizing agent and desulfurization equipment, so that the installation of the equipment is simplified to a great extent; in the denitration process, the flue gas temperature is raised, medium-low temperature SCR denitration is realized, the using amount of the catalyst is reduced by more than 30% compared with that of a pure low-temperature catalyst, deposition of ammonium sulfate can be effectively delayed, and the ammonium sulfate is prevented from adhering to the surface of the catalyst, so that the service life of the catalyst is prolonged, the capital investment of an SCR reactor and the cost for subsequent catalyst replacement are reduced, and the long-term safe and stable standard reaching of the environment-friendly emission value of the lime kiln is favorably ensured.
Drawings
The drawings are only for purposes of illustrating and explaining the present invention and are not to be construed as limiting the scope of the present invention. Wherein:
FIG. 1 is a schematic structural diagram of an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of another flue gas temperature raising device according to an embodiment of the present invention;
in the figure: 1-bag dust collector; 2-inlet flue; 3-a process water tank; 4-water outlet pipeline; 5-a process water pump; 6-two-fluid spray gun; 7-a gas storage tank; 8-thermal resistance; 9-on-line CEMS meter; 10-atomized water spray controller; 11-an electromagnetic flow meter; 12-an electric regulating valve; 13-manual regulating valve; 14-a gas supply control valve; 15-outlet flue; 16-an SCR reactor; 17-a draught fan; 18-built-in duct burner; 19-a combustion-supporting blower; 20-a heat exchanger; 21-a static mixer; 22-hot blast stove.
Detailed Description
The invention is further illustrated below with reference to the figures and examples. In the following detailed description, certain exemplary embodiments of the present invention are described by way of illustration only. Needless to say, a person skilled in the art realizes that the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Accordingly, the drawings and description are illustrative in nature and not intended to limit the scope of the claims.
As shown in fig. 1, the lime kiln flue gas treatment system comprises a dust remover, wherein the dust remover in the embodiment adopts a bag-type dust remover 1, an inlet flue 2 of the dust remover is connected to a flue gas discharge port of the lime kiln, the lime kiln flue gas treatment system further comprises an atomized water generation device, a spray end of the atomized water generation device is arranged in the inlet flue 2, atomized water is formed by the atomized water generation device and is sprayed into the inlet flue 2, and the atomized water reacts with CaO and MgO in lime kiln flue gas to generate Ca (OH)2、Mg(OH)2And the products are all in medium-strong alkalinity and can be matched with SO in the lime kiln smoke2Reacting to generate calcium sulfite or calcium sulfate powder, entering the bag-type dust remover 1 along with the flue gas, enabling dust carried in the lime kiln flue gas and unreacted alkaline substances to be adhered to the outer wall of the bag-type dust remover 1 to form a filter cake layer together, and enabling the unreacted SO in the lime kiln flue gas to be completely reacted in the dust removing process of the bag-type dust remover 12Continuously reacts with alkaline substances in the filter cake layer, thereby further removing SO in the flue gas2And the ultra-low emission of harmful substances in the smoke is achieved.
Specifically, the atomized water generating device comprises a process water tank 3, a process water pump 5 is installed on a water outlet pipeline 4 of the process water tank 3, injection pipes are arranged on the water outlet pipeline 4 at the water outlet end of the process water pump 5 in parallel, the end part of each injection pipe is connected with a two-fluid spray gun 6, the injection end of each two-fluid spray gun 6 is arranged in the inlet flue 2, the outer end of each two-fluid spray gun 6 is also communicated with a gas storage tank 7, and the gas storage tank 7 is connected to a high-pressure gas source. The high-pressure gas and the water form atomized water under the action of the two-fluid spray gun 6, and the atomized water is sprayed into the inlet flue 2 to react with CaO and MgO in the lime kiln flue gas.
The atomized water generating device and the inlet flue 2 are also connected with an atomized water spraying control device for detecting the flue gas temperature and SO in the inlet flue 2 in real time2The content of the components is as follows,the injection quantity of the double-fluid spray gun 6 can be adjusted in time through the detection result, so that the aims of thorough desulfurization and energy conservation are fulfilled. The atomized water spraying control device comprises a thermal resistor 8 and an online CEMS instrument 9 which are sequentially arranged on the inlet flue 2, wherein the thermal resistor 8 and the online CEMS instrument 9 are respectively connected to the input end of an atomized water spraying controller 10, the atomized water spraying control device also comprises an electromagnetic flowmeter 11 and an electric regulating valve 12 which are connected in series on the water outlet pipeline 4, and the electromagnetic flowmeter 11 and the electric regulating valve 12 are respectively connected to the output end of the atomized water spraying controller 10. Wherein the thermal resistor 8 and the online CEMS instrument 9 are respectively arranged between the two-fluid spray gun 6 and the dust remover, the thermal resistor 8 feeds back the exhaust gas temperature in the inlet flue 2, and the online CEMS instrument 9 feeds back SO in the exhaust gas2The discharged concentration, the thermal resistor 8 and the online CEMS instrument 9 are interlocked with the electromagnetic flow meter 11 and the electric regulating valve 12, the atomized water spray controller 10 automatically regulates the opening degree of the electric regulating valve 12 according to each detection value, the sprayed atomized water quantity is adjusted, and various information can be displayed in real time through the atomized water spray controller 10. The atomized water spray controller 10 includes a microprocessor, a display screen, a hard disk, a memory, a system bus, a communication interface, etc., which are well known to those skilled in the art and will not be described in detail herein.
A manual regulating valve 13 can be connected and installed on the water outlet pipeline 4, and the manual regulating valve 13 and the electric regulating valve 12 are installed in parallel to realize manual regulation and control of the atomized water quantity; and a gas supply control valve 14 is connected in series on a pipeline between the gas storage tank 7 and the two-fluid spray gun 6, and the gas supply control valve 14 is connected to the output end of the atomized water spray controller 10, so that automatic gas supply control is realized, compressed gas is saved, and the purpose of indirectly reducing energy consumption is achieved.
The structures are matched to complete the desulfurization process of the lime kiln flue gas, most of the desulfurization is completed at the smoke inlet side of the bag-type dust collector 1, and only a small part of residual SO is left2Is completed inside the bag-type dust collector 1.
In this embodiment, an outlet flue 15 of the dust remover is connected to an SCR reactor 16, and an induced draft fan 17 and a flue gas temperature raising device are sequentially installed on the outlet flue 15 along the flue gas advancing direction. The desulfurized flue gas is discharged from the bag-type dust collector 1 into the SCR reactor 16, and the SCR reactor 16 completes the denitration process of the lime kiln flue gas, so that the denitration process of the system is completed on the smoke discharge side of the dust collector. The temperature of the flue gas discharged from the bag-type dust collector 1 is about 80 ℃, the flue gas is sent to the flue gas temperature lifting device through the induced draft fan 17 to be heated, namely the flue gas is heated to at least 260 ℃ before entering the SCR reactor 16, the flue gas is denitrated at the temperature, the temperature interval of generation of ammonium sulfate salt is successfully avoided, the service life of the denitration catalyst is prolonged, and the use volume of the catalyst is reduced by more than 30% compared with that of a pure low-temperature catalyst. The SCR reactor 16 and the denitration catalyst disposed therein are well known to those skilled in the art and will not be described in detail herein.
Specifically, the flue gas temperature raising device comprises a built-in pipeline burner 18 arranged in the outlet flue 15, and the built-in pipeline burner 18 is respectively connected to a combustion gas source and a combustion-supporting blower 19 arranged outside the outlet flue 15 through pipelines. Fig. 2 shows another arrangement form of the flue gas temperature raising device, that is, the device includes a static mixer 21 communicated with the smoke inlet of the SCR reactor 16, the smoke inlet of the static mixer 21 is connected in parallel with a heat exchanger 20 and a hot blast stove 22, a heat exchange channel of the heat exchanger 20 communicated with the static mixer 21 is connected to the outlet flue 15, another heat exchange channel of the heat exchanger 20 is connected to the smoke outlet of the SCR reactor 16, and heat in flue gas discharged from the SCR reactor 16 is recycled to reduce energy consumption of the flue gas temperature raising device. Of course, the structure can also be arranged in parallel with the related structure of the built-in pipeline burner 18, so that the structure can be selected according to actual conditions, and the system can be in an energy-saving operation state during operation.
Through economic and technical analysis, the amount of the smoke gas of the lime kiln and the combustion medium can be selected according to the amount of the smoke gas and the combustion mediumThe proper flue gas temperature raising device generally has the flue gas volume of less than or equal to 20000m3When the temperature of the flue gas is increased to 260 ℃ or higher, the built-in pipeline combustor 18 is economical, the combustion medium can be selected from blast furnace gas, coke oven gas or fuel gas nearby, and the high-temperature hot air for combustion is directly mixed with the flue gas, so that the temperature of the flue gas is increased to 260 ℃ for denitration; when the smoke gas amount is more than or equal to 20000m3In the case of the specific design, the flue gas temperature raising device can adopt a mode of combining the GGH heat exchanger 20 with the hot blast stove 22 so as to recycle the heat of the hot blast stove 22, and the energy consumption can be greatly reduced.
The embodiment also discloses a treatment process of the lime kiln flue gas treatment system, which comprises a desulfurization process and a denitration process, wherein the desulfurization process is arranged on the flue gas inlet side of the dust remover, and the denitration process is arranged on the flue gas exhaust side of the dust remover.
Wherein, the desulfurization process utilizes the reaction of the atomized water and the effective components CaO and MgO in the lime kiln flue gas to respectively generate Ca (OH)2、Mg(OH)2Using Ca (OH)2、Mg(OH)2With SO in lime kiln flue gas2And (4) reacting to realize flue gas desulfurization. The key technology of the process is that the amount of sprayed atomized water is controlled, the alkaline oxide is activated, the temperature of the flue gas is kept to be higher than the dew point temperature of the flue gas by more than 20 ℃, the normal operation of the bag-type dust collector 1 can be ensured, the bag-type dust collector 1 is ensured not to be stuck, and therefore chemical balance calculation is required to be carried out firstly. Specifically, the desulfurization process comprises the following steps:
S1-1presetting a reaction formula related to the desulfurization process, CaO + H, in the atomized water injection controller 102O＝Ca(OH)2；
MgO+H2O＝Mg(OH)2；
And calculating the reference water spraying amount by matching the atomized water spraying controller 10 with the reaction formula. The reaction is essentially the digestion heat release process of the CaO, the sprayed water quantity is controlled to be just capable of completely generating calcium hydroxide from calcium oxide in ash as a reference, the calcium hydroxide can float up and down, and SO in flue gas is removed2Emission concentration ofAnd the exhaust gas temperature is interlocked with the electric regulating valve 12 to obtain the reference water spraying amount.
Presetting a smoke exhaust temperature monitoring limit value, namely smoke dew point temperature plus 20 ℃, in the atomized water injection controller 10, wherein the real-time detection value of the thermal resistor 8 is not less than the smoke dew point temperature plus 20 ℃ in the whole desulfurization process so as to ensure that the bag-type dust remover 1 normally operates and does not stick up bags, otherwise, entering S1-6。
S1-2The atomized water spraying controller 10 controls the electric regulating valve 12 to be opened, the atomized water is matched with high-pressure gas sent by the gas storage tank 7 and simultaneously enters the two-fluid spray gun 6, the two-fluid spray gun 6 mixes atomized water with the high-pressure gas and sprays the atomized water into the inlet flue 2 to react with CaO and MgO in the lime kiln smoke to generate calcium hydroxide and magnesium hydroxide and release heat, and the specific chemical formula is as follows:
Ca(OH)2+SO2＝CaSO3+H2O；
Mg(OH)2+SO2＝MgSO3+H2O。
S1-3calcium hydroxide, magnesium hydroxide and SO in lime kiln flue gas2Reacting to generate desulfurization products, and also comprising some desulfurization products such as sulfate.
The thermal resistor 8 detects the temperature of the flue gas at the air inlet end of the dust remover in real time and transmits the temperature to the atomized water spraying controller 10; the online CEMS instrument 9 detects SO in the flue gas at the air inlet end of the dust remover in real time2And transmitted to the atomized water spray controller 10; the electromagnetic flow meter 11 detects the water yield of the water outlet pipeline 4 in real time to obtain the actual water spraying amount, and transmits the actual water spraying amount to the atomized water spraying controller 10;
S1-4comparing the reference water spray amount with the actual water spray amount by using the atomized water spray controller 10, and when the actual water spray amount is less than the reference water spray amount, determining SO in the flue gas by using the atomized water spray controller 102The emission concentration has reached the ultra-low emission standard, at which time the atomized water spray controller 10 controls the opening degree of the electric regulating valve 12 to be reducedThe water consumption of the operation can be reduced, so that the water cost is reduced, and the smoke temperature is slightly increased along with the reaction heat release, so that the detection value of the thermal resistor 8 is increased.
When the actual water spray amount is not less than the reference water spray amount, the atomized water spray controller 10 determines the SO in the flue gas2The emission concentration does not reach the ultralow emission standard, at the moment, the atomized water injection controller 10 controls the opening of the electric regulating valve 12 to increase, the injection amount of atomized water is increased, the gas-solid reaction is converted into the gas-liquid reaction to a certain extent, and the reaction rate is improved.
S1-5And step S1-3The generated desulfurization product enters the dust remover, the dust remover intercepts the desulfurization product generated by reaction, calcium hydroxide which is not completely reacted, magnesium hydroxide which is not completely reacted and dust in the lime kiln smoke, a filter cake layer is formed on the inner wall of the dust remover, and the filter cake layer and SO (sulfur oxide) remained in the lime kiln smoke2And (5) continuing to react to finish the flue gas desulfurization.
S1-6The length of the inlet flue 2 is lengthened or/and the inner diameter of the inlet flue 2 is increased, so that the advancing speed of the flue gas is reduced, the desulfurization reaction time is prolonged, and the desulfurization efficiency and quality can be guaranteed to a certain extent.
The desulfurization process of the embodiment is particularly suitable for desulfurization treatment of lime kiln flue gas, and SO in the lime kiln flue gas is obtained2Initial concentration of not more than 200mg/Nm3And the desulfurization effect is optimal. Through the steps, the desulfurizer in the process is based on the effective components CaO and MgO in the ash, and no sodium-based desulfurizer is introduced, so that the dust collected from the bag-type dust remover 1 can be recycled as an additive of the calcium element of the sintering machine, and therefore, the process has no dangerous solid waste recycling cost and can create certain economic value.
The denitration process of the embodiment comprises the following steps:
S2-1the flue gas in the dust remover is conveyed to the SCR reactor 16 by utilizing the outlet flue 15 and the induced draft fan 17, and the flue gas flows through the flue gas at the temperatureWhen the device is lifted, the flue gas temperature is lifted by the flue gas temperature lifting device, so that the temperature of the flue gas entering the SCR reactor 16 is more than or equal to 260 ℃, a temperature interval for generating ammonium sulfate salt is avoided, and the flue gas is subjected to denitration after passing through the SCR reactor 16 and directly discharged.
According to the invention, the aim of flue gas desulfurization can be achieved by controlling and spraying a small amount of atomized water according to the self component characteristics and the reaction heat release characteristics of the lime kiln flue gas through chemical formula balance calculation without additionally adding a desulfurizing agent and desulfurization equipment, so that the equipment installation is simplified to a great extent; in the denitration process, the flue gas temperature is raised, medium-low temperature SCR denitration is realized, the using amount of the catalyst is reduced by more than 30% compared with that of a pure low-temperature catalyst, deposition of ammonium sulfate can be effectively delayed, and the ammonium sulfate is prevented from adhering to the surface of the catalyst, so that the service life of the catalyst is prolonged, the capital investment of the SCR reactor 16 and the cost for subsequent catalyst replacement are reduced, and the long-term safe and stable standard reaching of the environment-friendly emission value of the lime kiln is favorably ensured.
The description of the present invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to practitioners skilled in this art. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.
Claims (9)
1. Lime kiln flue gas processing system, including the dust remover, the import flue of dust remover is connected to the flue gas discharge port of lime kiln, its characterized in that: still include the atomized water and generate the device, the injection end that the atomized water generated the device is located in the import flue, the atomized water generate the device with still be connected with the atomized water injection controlling means between the import flue, the export flue of dust remover is connected to the SCR reactor, install draught fan and flue gas temperature hoisting device in proper order along flue gas advancing direction on the export flue.
2. The lime kiln flue gas treatment system of claim 1, wherein: the atomized water generating device comprises a process water tank, a process water pump is installed on a water outlet pipeline of the process water tank, injection pipes are arranged on the water outlet pipeline at the water outlet end of the process water pump in parallel, the end part of each injection pipe is connected with a double-fluid spray gun respectively, the injection ends of the double-fluid spray guns are arranged in the inlet flue, the outer ends of the double-fluid spray guns are communicated with a gas storage tank, and the gas storage tank is connected to a high-pressure gas source.
3. The lime kiln flue gas treatment system of claim 2, wherein: the atomized water spraying control device comprises a thermal resistor and an online CEMS instrument which are sequentially arranged on the inlet flue, wherein the thermal resistor and the online CEMS instrument are respectively connected to the input end of the atomized water spraying controller, and the atomized water spraying control device also comprises an electromagnetic flowmeter and an electric regulating valve which are connected in series on the water outlet pipeline, and the electromagnetic flowmeter and the electric regulating valve are respectively connected to the output end of the atomized water spraying controller.
4. The lime kiln flue gas treatment system of claim 3, wherein: the water outlet pipeline is also connected with a manual regulating valve, and the manual regulating valve and the electric regulating valve are installed in parallel; and a gas supply control valve is connected in series on a pipeline between the gas storage tank and the double-fluid spray gun and is connected to the output end of the atomized water spray controller.
5. The lime kiln flue gas treatment system of claim 3, wherein: the thermal resistor and the online CEMS instrument are respectively arranged between the two-fluid spray gun and the dust remover.
6. The lime kiln flue gas treatment system of claim 1, wherein: the flue gas temperature lifting device comprises a built-in pipeline burner arranged in the outlet flue, and the built-in pipeline burner is respectively connected to a combustion gas source and a combustion-supporting air blower which are arranged outside the outlet flue through pipelines.
7. The lime kiln flue gas treatment system of claim 6, wherein: the flue gas temperature lifting device comprises a static mixer communicated with the smoke inlet end of the SCR reactor, the smoke inlet end of the static mixer is connected with a heat exchanger and a hot blast stove in parallel, a heat exchange channel communicated with the heat exchanger and the static mixer is connected to the outlet flue, and the other heat exchange channel of the heat exchanger is connected to the smoke outlet end of the SCR reactor.
8. The process of claim 3, wherein: the method comprises a desulfurization process and a denitration process, wherein the desulfurization process is arranged on the smoke inlet side of the dust remover, and the denitration process is arranged on the smoke exhaust side of the dust remover;
the desulfurization process utilizes the reaction of atomized water and active ingredients CaO and MgO in the lime kiln flue gas to respectively generate Ca (OH)2、Mg(OH)2Using Ca (OH)2、Mg(OH)2With SO in lime kiln flue gas2Reacting to realize flue gas desulfurization, comprising the following steps:
S1-1presetting a reaction formula related to the desulfurization process in the atomized water injection controller,
CaO+H2O＝Ca(OH)2；
MgO+H2O＝Mg(OH)2；
calculating the reference water spraying amount by matching the atomized water spraying controller with the reaction formula;
presetting a smoke exhaust temperature monitoring limit value, namely the smoke dew point temperature plus 20 ℃, in the atomized water injection controller, wherein the real-time detection value of the thermal resistor is not less than the smoke dew point temperature plus 20 ℃ in the whole desulfurization process, or else, entering S1-6；
S1-2The atomized water injection controller controls the electric regulating valve to be opened and is matched with the high-pressure gas sent by the gas storage tankEntering the double-fluid spray gun during contract, mixing water and high-pressure gas by the double-fluid spray gun to atomize the water, spraying the atomized water into the inlet flue, reacting with CaO and MgO in the lime kiln flue gas to generate calcium hydroxide and magnesium hydroxide and release heat;
S1-3calcium hydroxide, magnesium hydroxide and SO in lime kiln flue gas2Reacting to generate a desulfurization product;
the thermal resistor detects the temperature of the flue gas at the air inlet end of the dust remover in real time and transmits the temperature to the atomized water spraying controller;
the online CEMS instrument detects SO in the flue gas at the air inlet end of the dust remover in real time2And transmitted to the atomized water spray controller;
the electromagnetic flow meter detects the water yield of the water outlet pipeline in real time to obtain the actual water spraying amount, and transmits the actual water spraying amount to the atomized water spraying controller;
S1-4comparing the reference water spraying amount with the actual water spraying amount by using the atomized water spraying controller, and judging SO in the flue gas by using the atomized water spraying controller when the actual water spraying amount is less than the reference water spraying amount2When the emission concentration reaches the ultralow emission standard, the atomized water injection controller controls the opening degree of the electric regulating valve to be reduced, and the detection value of the thermal resistor is increased;
when the actual water spraying amount is larger than or equal to the reference water spraying amount, the atomized water spraying controller judges SO in the flue gas2When the emission concentration does not reach the ultralow emission standard, the atomized water injection controller controls the opening of the electric regulating valve to increase;
S1-5and step S1-3The generated desulfurization product enters the dust remover, the dust remover intercepts the desulfurization product generated by reaction, calcium hydroxide which is not completely reacted, magnesium hydroxide which is not completely reacted and dust in the lime kiln smoke, a filter cake layer is formed on the inner wall of the dust remover, and the filter cake layer and SO (sulfur oxide) remained in the lime kiln smoke2Continuing to react to complete the flue gas desulfurization;
S1-6lengthening the inletThe length of the inlet flue or/and the inner diameter of the inlet flue is increased;
the denitration process comprises the following steps:
S2-1and feeding the flue gas in the dust remover into the SCR reactor by using the outlet flue and the induced draft fan, and when the flue gas flows through the flue gas temperature lifting device, lifting the temperature of the flue gas by using the flue gas temperature lifting device to ensure that the temperature of the flue gas entering the SCR reactor is not lower than 260 ℃, avoiding a temperature interval for generating ammonium sulfate salt, and completing denitration after the flue gas passes through the SCR reactor and directly discharging the denitration gas to the outside.
9. The process of claim 8, wherein: SO in the lime kiln flue gas2Initial concentration of not more than 200mg/Nm3。
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| CN115582016A (en) * | 2022-11-08 | 2023-01-10 | 山东万达环保科技有限公司 | Special ultralow-temperature desulfurization and denitrification process for lime kiln |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115582016A (en) * | 2022-11-08 | 2023-01-10 | 山东万达环保科技有限公司 | Special ultralow-temperature desulfurization and denitrification process for lime kiln |
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