CN210057883U - Denitration system of dry-method cement rotary kiln - Google Patents
Denitration system of dry-method cement rotary kiln Download PDFInfo
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- CN210057883U CN210057883U CN201920275266.5U CN201920275266U CN210057883U CN 210057883 U CN210057883 U CN 210057883U CN 201920275266 U CN201920275266 U CN 201920275266U CN 210057883 U CN210057883 U CN 210057883U
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Abstract
The utility model discloses a denitration system of dry process cement rotary kiln, through setting up reductant injection system respectively at dore and C5 whirlwind section of thick bamboo, two way aqueous ammonia reductants measure the distribution alone, at first control dore spout the ammonia nitrogen concentration requirement that the ammonia reductant quantity made it satisfy the discharge port, the ammonia nitrogen concentration who spouts ammonia reductant quantity when dore reaches the maximum value and export the flue gas still does not satisfy the environmental protection requirement start the injection system of C5 whirlwind section of thick bamboo, spout ammonia through the secondary and make it with the NOx further chemical combination in the flue gas, reduce into nitrogen gas and water with it. The denitration system can make the ammonia nitrogen of the outlet flue gasThe concentration is stably controlled at 100mg/Nm3The environment-friendly requirement is met; and the consumption of ammonia water is low, and the operation cost is low.
Description
Technical Field
The utility model relates to a flue gas denitration technical field, concretely relates to dry process cement rotary kiln's deNOx systems.
Background
The common NOx control method for the dry-method cement rotary kiln mainly comprises the following steps: optimizing the combustion conditions of the kiln and the decomposing furnace to reduce the generation of ammonia nitrogen; the blending scheme is changed, and a mineralizer is blended to reduce the sintering temperature and time of the clinker, improve the sintering easiness of the clinker and reduce the generation of ammonia nitrogen; a low NOx burner is adopted; the stage combustion technology in a kiln tail decomposing furnace and a pipeline is adopted. However, even if the four methods are used in combination, the NOx emission of the cement kiln can hardly reach 500mg/Nm3The following.
In order to reduce the emission concentration of ammonia nitrogen, many newly-built cement dry production lines begin to adopt a selective non-catalytic reduction (SNCR) denitration method or a Selective Catalytic Reduction (SCR) denitration method to further reduce the emission concentration of NOx so as to achieve the emission concentration of NOx of 100mg/Nm3The requirement of environmental protection within the scope is met. But the existing denitration system has unsatisfactory use effect, and mainly has the problems of low denitration efficiency, large ammonia water consumption and high operation cost; NOx emission concentration control is unstable and high peaks often occur that exceed environmental requirements.
The SNCR is a method for spraying a nitrogen-containing chemical agent into flue gas at 850-1050 ℃ to reduce NOx in the flue gas to generate nitrogen and water. Generally speaking, the temperature range of the upper part of the decomposing furnace just meets the reaction temperature window of SNCR, namely 850-1050 ℃, the SNCR method has good denitration effect, no catalyst is needed, and the construction and operation cost is lower than that of SCR. Therefore, the existing dry-method cement rotary kiln generally adopts a denitration spray gun arranged in a decomposing furnace and adopts an SNCR method for denitration, but the problem that the use cost is high due to excessive ammonia water spraying or the periodic nitrogen oxides exceed the standard due to insufficient ammonia water spraying is often caused by the pure SNCR denitration technology adopted on the decomposing furnace.
SUMMERY OF THE UTILITY MODEL
Aiming at solving the problems that the SNCR denitration technology is used in the prior art, the NOx emission concentration control is unstable and cannot meet the environmental protection requirement, the ammonia water consumption is large, and the operation is easyThe implementation cost is high; the utility model provides a utility model people are through the interior flow field and the temperature field distribution of stove to various dore furnaces in the cement trade to and after deep research and a large amount of analysis work have been done to the fuel characteristic, the discovery also accords with SNCR's reaction temperature window with the air intake or the air outlet of the C5 whirlwind section of thick bamboo that the dore furnace export is connected, set up the spray gun group through optimizing in dore furnace and the suitable position of the C5 whirlwind section of thick bamboo, can effectually promote NOx's desorption rate, can fall the NOx concentration of kiln tail flue gas to 100mg/Nm3As described below, the amount of ammonia used can be reduced significantly.
The utility model provides a denitration system of dry process cement rotary kiln, through setting up aqueous ammonia injection system respectively at dore and C5 cyclone, two way aqueous ammonia measure the distribution alone, at first control dore spout the ammonia volume and make it satisfy the ammonia nitrogen concentration requirement of discharge port, the injection system who starts C5 cyclone when dore spout the ammonia volume and reach the maximum value and the ammonia nitrogen concentration of export flue gas still does not satisfy the environmental protection requirement, it makes it further chemical combination with the NOx in the flue gas to spout ammonia through the secondary, reduce into nitrogen and water with it, the ammonia nitrogen concentration stable control of export flue gas is within 100mg/Nm3, satisfy the environmental protection requirement.
The utility model discloses a first technical scheme be: a denitration system of a dry-method cement rotary kiln comprises a reducing agent conveying module, a metering distribution module and a plurality of groups of mixed injection modules; the mixed injection module is respectively arranged in the temperature ranges of the decomposing furnace of the rotary cement kiln and the C5 cyclone cylinder, which accord with the SNCR reaction temperature window, and is used for injecting a reducing agent into the decomposing furnace and the C5 cyclone cylinder to reduce NOx in the flue gas to generate nitrogen and water; the reducing agent delivery module is used for delivering the reducing agent, and the metering and distributing module is used for quantitatively distributing the reducing agent delivered by the reducing agent delivery module to each mixed injection module.
The utility model discloses a second technical scheme be the improvement on first technical scheme, the utility model discloses a second technical scheme be: the temperature range is 850-1050 ℃. The temperature window restricts the selection of the position of the spraying point, and simultaneously determines the retention time of the reducing agent in the decomposing furnace, and the components of O2, CO, H20, H2, CHi and the like in the flue gas have certain influence on the reaction of NH3 x. For O2, the SNCR reaction does not occur in the absence of oxygen, with oxygen concentrations between 0.5% and 2.2% and little change in the final NOx concentration. The denitration efficiency is higher in the temperature range of 850-1050 ℃.
The utility model discloses a third technical scheme be the improvement on first or second technical scheme, the utility model discloses a third technical scheme be: the mixed injection module comprises an annular spray gun group, the annular spray gun group comprises a plurality of denitration spray guns, the denitration spray guns are radially inserted into the decomposing furnace and the C5 cyclone cylinder and are uniformly distributed in the circumferential direction, and the injection central line of each single spray gun and the radial lines of the decomposing furnace and the C5 cyclone cylinder form an included angle of 5-15 degrees. The included angle between the spray gun and the radial direction is set, so that the spray gun can generate a rotational flow effect during spraying, and the effective coverage of a spraying system is higher, thereby improving the denitration efficiency, reducing the ammonia escape amount and reducing the denitration operation cost; meanwhile, the influence of ammonia escape on dust removal and waste heat power generation equipment can be reduced, and the corrosion of the equipment is reduced.
The utility model discloses a fourth technical scheme be the improvement on the third technical scheme, the utility model discloses a fourth technical scheme be: the denitration spray gun is a two-fluid PQ-02 type spray gun, the atomization pressure of the spray gun is 0.5-0.8 Mpa, and the atomized particles are 20-80 um.
The spray gun is the key equipment of SNCR denitration, and its atomization effect is direct to be related to whole deNOx systems's denitration efficiency. The environmental-friendly PQ-02 spray gun of the Western general is a second generation two-fluid spray gun, and ammonia water is atomized by the aid of driving force of compressed air, so that the spray gun can have good atomization effect and penetration capacity in a high-temperature and high-dust environment. The integrally manufactured PQ-02 spray gun has the characteristics of wear resistance, corrosion resistance, high temperature resistance and capability of quickly adjusting the spray angle, can efficiently atomize a reducing agent and fully mix with compressed air, and can check the use condition of the spray gun in real time through the flow indicating function to quickly find the abnormal condition of the spray gun.
The utility model discloses a fifth technical scheme be the improvement on the third technical scheme, the utility model discloses a fifth technical scheme be: the mixed injection module also comprises a compressed air ring pipe, a reducing agent ring pipe and a cleaning water ring pipe which sequentially surround the periphery of the annular denitration spray gun group; the compressed air ring pipe is connected with a compressed air inlet of each denitration spray gun through a branch pipe and used for providing a spraying power source for the spray guns so that the reducing agent is atomized and reaches a spraying distance; the reducing agent ring pipe is connected with the reducing agent inlet of each denitration spray gun through a branch pipe and used for providing a reducing agent for the spray guns; the cleaning water ring pipe is connected with the cleaning water inlet of each denitration spray gun through a branch pipe and used for providing a cleaning water source to clean the spray guns.
Spray gun spun aqueous ammonia atomizing through compressed air, the aqueous ammonia after the atomizing reacts with the flue gas intensive mixing, keeps normally open state during compressed air operation, provides the injection power supply for the spray gun on the one hand, and on the other hand protects the spray gun not to be blockked up or burn out as the cooling cleaning medium of spray gun. When the spray gun operates normally, the cleaning water pipeline is in a closed state, and only when ammonia spraying is stopped, cleaning water is opened to flush the spray gun, so that the spray gun is prevented from being blocked or corroded.
The utility model discloses a sixth technical scheme be the improvement on the third technical scheme, the utility model discloses a sixth technical scheme be: the reducing agent conveying module comprises a reducing agent conveying pump, and the reducing agent conveying pump is used for conveying the reducing agent in the reducing agent storage tank to the denitration spray gun group through the metering and distributing module.
The utility model discloses a seventh technical scheme be the improvement on the sixth technical scheme, the utility model discloses a seventh technical scheme be: the metering distribution module comprises a flowmeter, a pressure transmitter, a flow regulating valve and branch pipelines; the total inlet of each branch pipeline is connected with the outlet of the reducing agent conveying module, the outlet of each branch pipeline is sequentially provided with a flow regulating valve, a flow meter and a pressure transmitter, the outlet of each branch pipeline is respectively connected with the reducing agent inlet of each annular spray gun group, the flow regulating valves are used for regulating the flow of the reducing agent entering each annular spray gun group, the flow meters are used for metering the flow, and the pressure transmitters are used for detecting the injection pressure of the reducing agent entering each annular spray gun group.
The utility model discloses an eighth technical scheme be the improvement on the seventh technical scheme, the utility model discloses an eighth technical scheme be: the denitration system also comprises a PLC control system and an ammonia nitrogen concentration detector arranged at the flue gas discharge port, wherein the ammonia nitrogen concentration detector, the flowmeter, the pressure transmitter, the flow regulating valve and the reducing agent delivery pump are respectively connected with the PLC control system; the ammonia nitrogen concentration detector transmits the detected outlet ammonia nitrogen concentration value to the PLC control system, and the PLC control system controls the opening of the flow regulating valve according to the outlet ammonia nitrogen concentration.
The utility model discloses denitration system's control method does:
1. firstly, setting the distribution proportion of the reducing agent sprayed into the decomposing furnace and the C5 cyclone cylinder according to factors such as the distribution of flow fields and temperature fields in the decomposing furnace of different furnace types, fuel characteristics and the like; setting the NOx emission concentration of the flue gas outlet according to the emission requirement;
2. the PLC control system compares the real-time value of the NOx detected on line with a set value in real time and calculates the absolute value A of the difference value of the real-time value and the set value; setting an upper limit value and a lower limit value of the absolute value A of the difference value;
3. the PLC control system respectively supplies reducing agents to the decomposing furnace and the C5 cyclone cylinder according to a set proportion; when the real-time value of NOx exceeds a set value and the absolute value A of the difference reaches the upper limit, or the real-time value of NOx does not exceed the set value but has an ascending trend, the PLC control system firstly controls a flow regulating valve on a branch pipeline supplying a decomposing furnace in a metering and distributing module to increase the opening degree and increase the input quantity of a reducing agent in the decomposing furnace, the increase quantity is linearly related to the absolute value A of the difference, and the larger the absolute value A of the difference is, the larger the increase quantity is; when the reducing agent in the decomposing furnace is increased to a certain amount, the concentration of the outlet Nox is reduced, the absolute value A of the difference is reduced, and the current input amount of the reducing agent is maintained when the absolute value A of the difference is reduced to a set lower limit; if the concentration of the reducing agent in the decomposing furnace is increased to the maximum, the concentration of the outlet Nox still cannot meet the requirement, the PLC control system controls a flow regulating valve on a branch pipeline supplying the C5 cyclone cylinder in the metering and distributing module to increase the opening degree, the input quantity of the reducing agent in the C5 cyclone cylinder is increased, the increase quantity is linearly related to a difference absolute value A, and the increase quantity is larger when the difference absolute value A is larger; when the reducing agent in the C5 cyclone cylinder is increased to a certain amount, the concentration of the outlet Nox is reduced, and the current input amount of the reducing agent is maintained when the absolute value A of the difference is reduced to a set lower limit;
4. when the real-time value of NOx is lower than a set value and reaches an upper limit, the PLC control system firstly controls a flow regulating valve of a branch pipeline of the C5 cyclone cylinder to reduce the opening degree and reduce the input amount of a reducing agent in the cyclone cylinder, the reduction amount is linearly related to a difference absolute value A, and the larger the difference absolute value A is, the larger the reduction amount is; when the reducing agent in the cyclone cylinder is reduced to a certain amount, the concentration of the outlet Nox rises, the absolute value A of the difference value is reduced, the current input amount of the reducing agent is maintained when the absolute value A of the difference value is reduced to a set lower limit, the set maintaining time is T1, if the real-time value of NOx in the maintaining time T is always lower than the set value, the PLC control system closes the flow regulating valve on the branch pipeline of the C5 cyclone cylinder, and the reducing agent is stopped being supplied to the C5 cyclone cylinder; meanwhile, the opening degree of a flow regulating valve on a branch pipeline of the decomposing furnace is controlled to be reduced, the input amount of a reducing agent in the decomposing furnace is reduced, the reduction amount is linearly related to the absolute value A of the difference, and the larger the absolute value A of the difference is, the larger the reduction amount is; when the reducing agent of the decomposing furnace is reduced to a certain amount, the concentration of the outlet Nox is increased, the absolute value A of the difference is reduced, and the current input amount of the reducing agent is maintained when the absolute value A of the difference is reduced to a set lower limit;
5. the holding time is set to be T2, and when the NOx real-time value is lower than the set value all the time in the holding time T2, the input amount of the reducing agent of the decomposing furnace is adjusted downwards again, and the input amount of the reducing agent is further reduced.
As the time from ammonia spraying to the reaction zone is required to be 2-3 minutes for kiln tail detection, the control and adjustment of the output quantity of the reducing agent has larger hysteresis, and in order to reduce the hysteresis effect, the system adopts the trend control method, and adjusts the input quantity of the reducing agent in the decomposing furnace and the C5 cyclone cylinder step by step, the temperature in the decomposing furnace is higher, and the ammonia nitrogen concentration in the flue gas is high, so that the denitration effect in the decomposing furnace is controlled firstly, and when the denitration effect in the decomposing furnace does not meet the requirement, the denitration effect in the C5 cyclone cylinder is controlled, so that the total denitration efficiency is improved.
The utility model has the advantages that:
(1) this application is through setting up aqueous ammonia injection system respectively at dore and C5 cyclone, two way aqueous ammonia measure the distribution alone, the ammonia volume of spouting of at first control dore makes it satisfy the ammonia nitrogen concentration requirement of discharge port, the ammonia volume of spouting when dore reaches the maximum value and the ammonia nitrogen concentration of export flue gas still does not satisfy the environmental protection requirement the time start-up injection system of C5 cyclone, it further combines with NOx in the flue gas through the secondary ammonia of spouting makes, reduce into nitrogen gas and water with it, the ammonia nitrogen concentration stable control of export flue gas is within 100mg/Nm3, satisfy the environmental protection requirement.
(2) This application is through adopting the high-efficient spray gun crowd of annular, and every spray gun slant inserts, and the effective jet distance of spray gun exceeds 3 meters, and the coverage of spray gun fog crown to the flue is higher. And a plurality of inclined spraying guns are matched for use, a certain rotational flow effect can be generated, the effective coverage area of a spraying system is higher, the denitration efficiency is improved, the ammonia escape amount is reduced, the denitration operation cost is reduced, the influence on dust removal and waste heat power generation equipment is reduced, and the consumption of related equipment spare parts is reduced.
Drawings
Fig. 1 is a front view of embodiment 1 of the denitration system of the dry method cement rotary kiln according to the present invention, in which a reducing agent delivery module and a metering and distributing module are omitted.
Fig. 2 is a side view of fig. 1.
Fig. 3 is a schematic structural diagram of the mixed injection module of embodiment 1 of the denitration system of the dry cement rotary kiln of the present invention.
Fig. 4 is a schematic structural view of the denitration lance of the mixed injection module of embodiment 1 of the denitration system of the dry method cement rotary kiln of the present invention.
Fig. 5 is a schematic layout diagram of the annular denitration lance group of the decomposing furnace of embodiment 1 of the denitration system of the dry cement rotary kiln of the present invention.
Fig. 6 is a schematic diagram of a simulation of a mist field effect formed by the denitration lance group shown in fig. 5, wherein a is a jet blind area, b is a flow field coverage area, and c is a mist overlapping area.
Fig. 7 is an installation schematic diagram of the denitration lance of embodiment 1 of the denitration system of the dry cement rotary kiln of the present invention.
Fig. 8 is a schematic control flow diagram of embodiment 2 of the denitration system control method of the dry-process rotary cement kiln of the present invention.
Fig. 9 and 10 are schematic control diagrams of embodiment 2 of the denitration system control method for the dry-process rotary cement kiln according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and a preferred embodiment.
Referring to fig. 1 and 2, the denitration system of the dry-method cement rotary kiln comprises a decomposing furnace 01 and a C5 cyclone 02, wherein an outlet of the decomposing furnace 01 is connected with an inlet of the C5 cyclone 02, flue gas is finally discharged through an outlet of the C5 cyclone 02, and an online ammonia nitrogen concentration detector is arranged at an outlet of the C5 cyclone 02. The diameter of a hearth of the decomposing furnace 01 is 5000mm, the diameter of a C5 cyclone 02 is 6000mm, and the capacity of the rotary kiln is 2000 tons/day.
The denitration system comprises a raw agent conveying module, a metering distribution module and two groups of mixed injection modules, wherein the first group of mixed injection modules are arranged at the middle upper part of a rotary cement kiln decomposing furnace 01, such as an area A shown in figure 1; the second group of mixed jet modules is arranged at the air inlet of the C5 cyclone 02, as shown in the B area in FIG. 1. Still include PLC control system and set up the ammonia nitrogen concentration detector at the exhanst gas outlet. The operation temperature of the area A is 850-1050 ℃, and the operation temperature of the area B is 850-1050 ℃.
In this embodiment, the reducing agent used in the denitration system is ammonia water. The two groups of mixed injection modules are respectively used for injecting ammonia water into the decomposing furnace and the C5 cyclone cylinder. Each group of mixed injection modules comprises an annular denitration spray gun group, and a compressed air ring pipe 2, an ammonia water ring pipe 3 and a cleaning water ring pipe 4 which sequentially surround the periphery of the annular denitration spray gun group.
In this embodiment, each annular denitration spray gun group comprises four denitration spray guns 1, each denitration spray gun 1 is a Siepu environmental-friendly PQ-02 type two-fluid spray gun, the atomization pressure of each spray gun is 0.5-0.8 Mpa, the atomization particles are 20-80 um, and the effective spray distance of each spray gun is 3 m.
Referring to fig. 4, the denitration lance 1 has a structure in which an ammonia water channel 107 is axially disposed at a central portion of the denitration lance, a cleaning water inlet 103 axially communicated with the ammonia water channel 107 is disposed at a rear end of the ammonia water channel 107, and the cleaning water inlet 103 is closed by a plug 105 during operation; an ammonia water inlet 101 which is radially communicated with the ammonia water channel 107 is also arranged. The front end of the ammonia water passage 107 is connected with an ammonia water nozzle 108. The outside of aqueous ammonia passageway 107 is equipped with compressed air passageway 106, and the rear end of compressed air passageway 106 is equipped with the compressed air import 102 with compressed air passageway 106 warp-wise intercommunication, and the front end of compressed air passageway 106 is equipped with atomizing spout 104, and the aqueous ammonia that spouts from the spout of aqueous ammonia shower nozzle 108 spouts from atomizing spout 104 after the compressed air atomizing.
Referring to fig. 5, the annular denitration spray gun group is arranged on a decomposing furnace 01, the annular denitration spray gun group arranged on a cyclone cylinder is the same as that of the decomposing furnace, four denitration spray guns 1 respectively penetrate through a protective sleeve 5 and are inserted along the radial directions of the decomposing furnace and a C5 cyclone cylinder, the end surfaces of the four denitration spray guns do not exceed the inner walls of the decomposing furnace and the inner wall of the cyclone cylinder, an included angle α between the injection central line of each spray gun and the radial lines of the decomposing furnace and the C5 cyclone cylinder is 15 degrees, the four denitration spray guns 1 are uniformly distributed in the circumferential directions of the decomposing furnace and the C5 cyclone cylinder, and the protective sleeve is a high-temperature-resistant sleeve and is arranged on the side walls of the decomposing furnace and the C5 cyclone cylinder in a welding mode in advance.
In other implementations, spray guns with different quantities can be arranged according to rotary cement kilns with different production capacities, so that the reducing agent can cover the flue to the maximum extent, and the denitration effect is ensured.
Referring to fig. 6, a is a spray blind area, b is a flow field coverage area, and c is a spray overlapping area. As can be seen from figure 6, the coverage of the flue of the decomposing furnace by the obliquely arranged spray gun fog crown is higher, and the dead zone of the spray is smaller.
Referring to fig. 3, fig. 3 is a view illustrating the mixing and spraying module provided on the decomposing furnace 01, and the mixing module provided on the cyclone is the same as that of the decomposing furnace. The compressed air ring pipe 2 is connected with a compressed air inlet 102 of each denitration spray gun through a branch pipe, a compressed air pipe network or an air compressor is communicated with the compressed air ring pipe 2 through a pipeline, and the compressed air pipe network or the air compressor provides a jet power source for the spray guns. Ammonia water ring pipe 3 passes through the branch pipe and is connected with the aqueous ammonia import 101 of every denitration spray gun, and ammonia water ring pipe 3 passes through the pipeline to be connected with flow distribution module, provides the aqueous ammonia for the denitration spray gun. The cleaning water ring pipe 3 is connected with the cleaning water inlet 103 of each denitration spray gun through a branch pipe, and the cleaning water pipe network is connected with the cleaning water ring pipe 3 through a pipeline to provide a cleaning water source for the denitration spray guns.
Please refer to fig. 7 for the installation of the denitration spray gun overhaul platform, and a steel platform and a guardrail are arranged below the denitration spray gun with the installation height of 1.3-1.5 m, so that the ammonia injection system can be safely operated and overhauled conveniently.
In this implementation, former agent transport module includes aqueous ammonia delivery pump and pipeline, and the aqueous ammonia delivery pump can be equipped with one or more, and the import of delivery pump passes through the pipeline to be connected with the aqueous ammonia storage tank, and the aqueous ammonia is transported by special tank car, in unloading the ammonia pump and transferring to the aqueous ammonia storage tank. The export of delivery pump passes through the import intercommunication of pipeline with distribution metering module, and the pump export is furnished with the manometer, and real-time supervision pump pressure installs pressure sensor simultaneously, and pressure sensor and delivery pump are connected with PLC control system electricity, and pressure sensor provides real-time pressure signal to PLC control system, and whole pump station can realize on the spot and remote control.
In the implementation, the metering distribution module comprises a flowmeter, a pressure transmitter, a flow regulating valve and branch pipelines; the main inlet of each branch pipeline is connected with the outlet of the ammonia water delivery pump, and the outlet of each branch pipeline is respectively connected with the ammonia water ring pipes 3 of the two mixed injection modules. The outlet of each branch pipeline is sequentially provided with a flow regulating valve, a flowmeter and a pressure transmitter, wherein the flow regulating valve is used for regulating the flow of the reducing agent entering each annular spray gun group, the flowmeter is used for metering the flow, and the pressure transmitter is used for detecting the injection pressure of the ammonia water entering each annular spray gun group. The flowmeter, the pressure transmitter and the flow regulation are electrically connected with the PLC control system.
Taking the denitration system described in embodiment 1 as an example, a method for controlling the denitration system will be described as follows:
1. first, a decomposing furnace is set andthe distribution proportion of the reducing agent sprayed into the cyclone cylinder is C5; setting the NOx emission concentration of a flue gas outlet; in the implementation, the dosage ratio of the decomposing furnace to the C5 cyclone reducing agent is set to be 5:1, and the NOx emission concentration at the smoke outlet is 90mg/Nm3。
2. The PLC control system compares the real-time value of the NOx detected on line with a set value in real time and calculates the absolute value A of the difference value of the real-time value and the set value; setting an upper limit value and a lower limit value of the absolute value A of the difference value; in the present embodiment, it is assumed that the upper limit of the absolute value A of the difference is 5mg/Nm3Lower limit value of 1mg/Nm3；
3. The PLC control system supplies reducing agents to the decomposing furnace and the C5 cyclone respectively according to set proportion. When the real-time value of NOx exceeds the set value and the absolute value A of the difference reaches 5mg/Nm3I.e. NOx real-time value of 95mg/Nm3When the current is over; or when the real-time value of the NOx does not exceed the set value but has an ascending trend, namely the absolute value A of the difference value is larger and larger; the PLC control system firstly controls a flow regulating valve on a branch pipeline for supplying the decomposing furnace in the metering and distributing module to increase the opening degree, the input quantity of the reducing agent in the decomposing furnace is increased, the increase quantity is linearly related to a difference absolute value A, and the increase quantity is larger when the difference absolute value A is larger; when the reducing agent in the decomposing furnace is increased to a certain amount, the concentration of the outlet Nox is reduced, the absolute value A of the difference is reduced, and when the absolute value A of the difference is reduced to 1mg/Nm3Maintaining the current input amount of the reducing agent; if the concentration of the reducing agent in the decomposing furnace is increased to the maximum, the concentration of the outlet Nox still cannot meet the requirement, the PLC control system controls a flow regulating valve on a branch pipeline supplying the C5 cyclone cylinder in the metering and distributing module to increase the opening degree, the input quantity of the reducing agent in the C5 cyclone cylinder is increased, the increase quantity is linearly related to a difference absolute value A, and the increase quantity is larger when the difference absolute value A is larger; when the reducing agent in the C5 cyclone is increased to a certain amount, the concentration of outlet Nox is reduced, and when the absolute value of the difference A is reduced to 1mg/Nm3Maintaining the current input quantity of the reducing agent;
4. when the real-time value of NOx is lower than the set value and reaches the upper limit of 5mg/Nm3When the reducing amount is linearly related to the absolute value A of the difference value, the larger the absolute value A of the difference value is, the PLC control system firstly controls the flow regulating valve of the branch pipeline of the C5 cyclone cylinder to reduce the opening degree and reduce the input amount of reducing agent in the cyclone cylinderThe greater the reduction; when the reducing agent in the cyclone cylinder is reduced to a certain amount, the concentration of the outlet Nox rises, the absolute value A of the difference is reduced, and when the absolute value A of the difference is reduced to 1mg/Nm3The current input amount of the reducing agent is maintained constantly, the maintaining time is set to be 10 minutes, if the real-time NOx value is always lower than the set value within 10 minutes, the PLC control system closes the flow regulating valve on the branch pipeline of the C5 cyclone, and the reducing agent is stopped being supplied to the C5 cyclone; meanwhile, the opening degree of a flow regulating valve on a branch pipeline of the decomposing furnace is controlled to be reduced, the input amount of a reducing agent in the decomposing furnace is reduced, the reduction amount is linearly related to the absolute value A of the difference, and the larger the absolute value A of the difference is, the larger the reduction amount is; when the reducing agent in the decomposing furnace is reduced to a certain amount, the concentration of the outlet Nox rises, the absolute value A of the difference is reduced, and when the absolute value A of the difference is reduced to 1mg/Nm3Maintaining the current input quantity of the reducing agent;
5. setting the maintaining time to be 15 minutes, and when the NOx real-time value is always lower than the set value within 15 minutes, adjusting the input quantity of the reducing agent of the decomposing furnace downwards again, and further reducing the input quantity of the reducing agent.
The denitration system is operated by the control method of the embodiment 2, the operation process is continuously monitored for 180 hours, and the NOx emission index can be stabilized at 100mg/Nm when the denitration system is normally operated3The following; the fluctuation amount of the emission concentration of NOx is not more than +/-15 mg/Nm3(ii) a The consumption of ammonia is about 5 kg/ton clinker cement.
Parts which are not specifically described in the above description are prior art or can be realized by the prior art.
Claims (8)
1. A denitration system of a dry-method cement rotary kiln comprises a reducing agent conveying module, a metering distribution module and a plurality of groups of mixed injection modules; the mixed injection module is respectively arranged in temperature intervals of a decomposing furnace of a rotary cement kiln and a C5 cyclone cylinder, which accord with an SNCR reaction temperature window, and is used for injecting a reducing agent into the decomposing furnace and the C5 cyclone cylinder to reduce NOx in flue gas to generate nitrogen and water; the reducing agent delivery module is used for delivering the reducing agent, and the metering and distributing module is used for quantitatively distributing the reducing agent delivered by the reducing agent delivery module to each mixed injection module.
2. The denitrification system of claim 1, wherein the temperature range is 850 ℃ to 1050 ℃.
3. The denitration system of claim 1 or 2, wherein the mixed injection module comprises an annular spray gun group, the annular spray gun group comprises a plurality of denitration spray guns, the denitration spray guns are inserted along the radial direction of the decomposing furnace and the C5 cyclone cylinder and are uniformly distributed in the circumferential direction, and the injection central line of a single spray gun forms an included angle of 5-15 degrees with the radial line of the decomposing furnace and the C5 cyclone cylinder.
4. The denitration system of claim 3, wherein the denitration lance is a two-fluid PQ-02 type lance, the atomization pressure of the lance is 0.5 to 0.8MPa, and the atomized particles are 20 to 80 μm.
5. The denitrification system of claim 3, wherein the mixed injection module further comprises a compressed air loop, a reducing agent loop and a cleaning water loop surrounding the annular denitrification lance group in sequence; the compressed air ring pipe is connected with a compressed air inlet of each denitration spray gun through a branch pipe and used for providing a spraying power source for the spray guns so that the reducing agent is atomized and reaches a spraying distance; the reducing agent ring pipe is connected with the reducing agent inlet of each denitration spray gun through a branch pipe and used for providing a reducing agent for the spray guns; the cleaning water ring pipe is connected with the cleaning water inlet of each denitration spray gun through a branch pipe and used for providing a cleaning water source to clean the spray guns.
6. The denitration system of claim 3, wherein the reducing agent delivery module comprises a reducing agent delivery pump for delivering the reducing agent in a reducing agent storage tank to the denitration lance population via the metering and dispensing module.
7. The denitrification system of claim 6, wherein the metering and distribution module comprises a flow meter, a pressure transmitter, a flow regulating valve and a branch line; the total inlet of each branch pipeline is connected with the outlet of the reducing agent conveying module, the outlet of each branch pipeline is sequentially provided with a flow regulating valve, a flow meter and a pressure transmitter, the outlet of each branch pipeline is respectively connected with the reducing agent inlet of each annular spray gun group, the flow regulating valves are used for regulating the flow of the reducing agent entering each annular spray gun group, the flow meters are used for metering the flow, and the pressure transmitters are used for detecting the injection pressure of the reducing agent entering each annular spray gun group.
8. The denitration system of claim 7, further comprising a PLC control system and an ammonia nitrogen concentration detector arranged at the flue gas discharge port, wherein the ammonia nitrogen concentration detector, the flowmeter, the pressure transmitter, the flow regulating valve and the reducing agent delivery pump are respectively connected with the PLC control system; the ammonia nitrogen concentration detector transmits the detected outlet ammonia nitrogen concentration value to the PLC control system, and the PLC control system controls the opening of the flow regulating valve according to the outlet ammonia nitrogen concentration.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109821392A (en) * | 2019-03-05 | 2019-05-31 | 南京西普环保科技有限公司 | A kind of denitrating system and its control method of dry method cement rotary kiln |
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