CN110787609A - Flue gas denitration device for tank furnace and denitration method thereof - Google Patents
Flue gas denitration device for tank furnace and denitration method thereof Download PDFInfo
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/76—Gas phase processes, e.g. by using aerosols
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/54—Nitrogen compounds
- B01D53/56—Nitrogen oxides
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/20—Reductants
- B01D2251/206—Ammonium compounds
- B01D2251/2062—Ammonia
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D2258/00—Sources of waste gases
- B01D2258/02—Other waste gases
- B01D2258/0283—Flue gases
Abstract
The invention relates to a flue gas denitration device and a denitration method for a pot-type furnace.A nozzle is uniformly distributed on a horizontal integrated flue of the pot-type furnace, 20% ammonia water is used as a denitration reducing agent, an ammonia water vaporizer evaporates the ammonia water into ammonia water vapor through low-pressure saturated steam, and the ammonia water vapor is mixed with preheated air for dilution to reduce the concentration of ammonia gas to less than 5%; the ammonia injection grid is added to a proper position of an outlet flue of a calcining furnace, so that the denitration efficiency can be high, the ammonia escape can be reduced, the emission of nitrogen oxides in a production line of the pot furnace reaches the standard, the service life of the flue is prolonged, flushing water in the denitration process can be recycled, and no wastewater is generated; compact structure, simple process, small occupied space and low cost investment.
Description
Technical Field
The invention relates to a flue gas denitration device for a tank furnace and a denitration method thereof.
Background
The main measures for controlling nitrogen oxide pollution and preventing and treating acid rain hazard in the field of global environmental management are flue gas denitration, wherein flue gas denitration mainly refers to removal of nitrogen oxide from flue gas, flue gas denitration technologies are generally divided into selective catalytic reduction denitration technology (SCR) methods, selective non-catalytic reduction technology (SNCR) methods and SNCR + SCR combined methods, and the main principle is as follows:
1. selective catalytic reduction denitration technology (SCR)
A selective catalytic reduction flue gas denitration technology comprises the steps that under the action of a catalyst and at the temperature of 300-400 ℃, a gaseous amino reducing agent (liquid ammonia, ammonia water and urea prepared into gaseous ammonia) is sprayed into flue gas and is subjected to reduction reaction with NOx in the flue gas to generate harmless N2And H2O (formula 1 to formula 4); the SCR technology is the most mature deep flue gas denitration technology at present, and the denitration efficiency can reach 95 percent at most;
4NO+4NH3+O2→4N2+6H2o (formula 1)
6NO+4NH3→5N2+6H2O (formula 2)
6NO2+8NH3→7N2+12H2O (formula 3)
2NO2+4NH3+O2→3N2+6H2O (formula 4)
SCR is a deep flue gas denitration technology commonly adopted by power station boilers;
2. selective non-catalytic reduction technology (SNCR)
The SNCR technology is characterized in that an amino reducing agent (such as ammonia gas, ammonia water and urea) solution is atomized into liquid drops by a mechanical spray gun and sprayed into a hearth, gaseous NH3 is generated by pyrolysis, and NH is carried out in a 950-1050 ℃ temperature region (usually a boiler convection heat exchange region) without a catalyst3Performing selective non-catalytic reduction reaction with NOx to reduce NOx into N2And H2O; the main chemical reaction is as follows:
ammonia 4NO +4NH3+O2→4N2+6H2O
Urea 2NO + (NH)2)2CO+1/2O2→2N2+2H2O+CO2
The SNCR process has narrow reaction temperature range, poor adaptability to coal types and load changes and certain limitation on ammonia injection amount control, so the SNCR has low denitration efficiency which is generally below 50 percent and has larger change along with boiler load;
the SNCR process has low investment cost and low operation cost, and is particularly suitable for small-capacity boilers;
3. SNCR/SCR mixed flue gas denitration technology
The SNCR/SCR mixed flue gas denitration technology is a combination of the SNCR and SCR technologies, a denitration reducing agent is sprayed into a hearth at the temperature window of 850-1100 ℃, and partial NOx is reduced into N2Residual NOx and unreacted NH in the flue gas3Entering a built-in flue type SCR reaction zone, and further completing denitration reduction reaction under the action of a catalyst; the technology can effectively reduce the usage amount of the catalyst of the SCR process, has the denitration efficiency of about 50-60%, and is mainly suitable for the conditions that the denitration efficiency requirement is not high, the SNCR alone cannot meet the requirement, or an SCR device is difficult to arrange;
the flue gas denitration processes have certain defects, and specifically comprise the following steps:
the system resistance of SCR is large in the operation process, and in addition, sticky dust in flue gas is adhered to the surface of the catalyst, so that the denitration effect and the flow area are influenced, the system resistance is further increased, the normal production is seriously influenced, the power consumption is increased, and both the technical adaptability and the economical efficiency are not ideal;
the SNCR installs the spray nozzle on the boiler front flue, spray the ammonia water, the front flue length is less than 3 meters, the space of denitration reaction and time can't meet the requirements;
the SNCR/SCR mixed flue gas denitration technology is mainly applied to the waste gas treatment of a power plant at present;
the production line for producing calcined petroleum coke usually needs to be provided with a plurality of groups of pot furnaces, waste heat flue gas in the production process needs to be subjected to desulfurization and dust removal after being absorbed by waste heat and then is discharged after reaching the standard, along with the increasing improvement of national environmental protection standards, the emission concentration standard of nitrogen oxides is getting tighter and tighter, the traditional flue gas denitration process cannot meet the increasingly strict emission standard requirements, viscous dust in the flue gas is easy to exceed the standard, and in addition, the increase of dust removal equipment does not have enough equipment space; the temperature of the flue gas of the tank furnace is usually as high as 800-1100 ℃, the furnace path is generally made of refractory materials, because the inner diameter of a flue is smaller, the process of directly spraying an ammonia water solution by using an SNCR spray gun is adopted, the solution is easily sprayed on the inner wall of the flue, the surface temperature of the refractory materials is rapidly reduced, the refractory materials are damaged, meanwhile, the water content of the flue gas of the tank furnace is high, if the concentration of nitrogen oxides is low, the consumption of a reducing agent is very low, in order to ensure the effect of the spray gun, the water content of the ammonia water diluted by desalted water in the sprayed reducing agent to be below 5 percent and added into a system is increased, and the water content can influence subsequent systems.
Disclosure of Invention
The invention aims to solve the technical problems that the denitration efficiency can be improved, ammonia escape is reduced, the problem that nitric oxide in a tank furnace production line is discharged up to standard and the service life of a flue is not influenced is solved, and the flue gas denitration device and the denitration method for the tank furnace are provided.
The invention relates to a flue gas denitration device for a pot type furnace, which comprises a production line which is formed by combining a plurality of pot type calcining furnaces and is used for producing calcined petroleum coke, wherein the outlet of each calcining furnace is connected to a high-temperature superheater of a waste heat boiler through a flue, and the denitration device is characterized in that: each calcining furnace is connected to a flue of the waste heat boiler and is provided with at least one reducing agent adding point, and the reducing agent is 20% ammonia water; the ammonia water is stored in an ammonia water storage tank, an inlet of the ammonia water storage tank is connected with an automatic ammonia water discharging device, an outlet of the ammonia water storage tank is connected with an ammonia water vaporizer through an ammonia water supply pump, an outlet of the ammonia water vaporizer is connected to a reducing agent adding point on a flue through an ammonia spraying grid through a mixed gas conveying pipeline, a mixer is arranged on the mixed gas conveying pipeline, and the mixer is also connected with a dilution fan;
an inlet at the top of one side of the ammonia water storage tank is connected to an automatic ammonia water discharging device through a pipeline, and is also connected with a process water conveying pipeline; an outlet at the lower part of the side wall of the other side of the ammonia water storage tank is connected to an ammonia water inlet of the wall of the ammonia water vaporizer through an ammonia water supply pump, and the ammonia water supply pump is connected with a pressure control loop;
the ammonia water supply pump comprises three full-flow multistage centrifugal pumps, and the three centrifugal pumps are connected in parallel between the ammonia water storage tank and the ammonia water vaporizer;
the bottom of the ammonia water vaporizer is provided with a steam inlet, the steam inlet is connected with a low-pressure saturated steam conveying pipeline, one side of the top of the ammonia water vaporizer is provided with an ammonia water vapor outlet, and the ammonia water vapor outlet is connected to the mixer through a conveying pipeline; the ammonia water vaporizer body is provided with an evaporator area positioned at the lower part and a buffer area positioned at the upper part, a tube array type heat exchange tube is arranged in the evaporator area, one end of the heat exchange tube is connected to an ammonia water inlet on the wall part of the ammonia water vaporizer, the other end of the heat exchange tube is connected to an ammonia water gas outlet, so that the tube side of the heat exchange tube forms an ammonia water circulation channel, and the shell side of the ammonia water vaporizer forms a low-pressure saturated steam circulation;
an ammonia discharge and flushing water outlet is formed in one side of the bottom of the ammonia water gasifier, the ammonia discharge and flushing water outlet is connected with a waste water pit through a waste water conveying pipeline, and the waste water pit is connected with a waste water treatment device through a waste water conveying pipeline; the other side of the bottom of the ammonia water vaporizer is provided with a drainage device;
an ammonia discharge and flushing water outlet is also formed in the position, below the side wall outlet, of the ammonia water storage tank, and the ammonia discharge and flushing water outlet of the ammonia water storage tank is also connected to the waste water pit through a waste water conveying pipeline;
a heater is arranged between the dilution fan and the mixer;
the ammonia gas concentration after the ammonia water vapor outlet is conveyed to the mixer and mixed with the preheated air is 3-5% (v%);
a waste water pump is arranged on the waste water conveying pipeline, and the waste water treatment device is a desulfurization system of a waste heat boiler;
the top of the outlet side of the ammonia water storage tank is also provided with a collecting pipeline which is connected to a pipeline between the ammonia water supply pump and the ammonia water vaporizer;
the automatic ammonia water discharging device comprises an ammonia water discharging pump, and the ammonia water discharging pump is connected between a tank car for transporting the ammonia water solution and an ammonia water storage tank through a conveying pipeline;
the ammonia water storage tank is a vertical normal-pressure container made of stainless steel materials, and the volume of the container is 45m3(ii) a A liquid level meter, a single suction valve, a water seal device and a spraying device are arranged outside the ammonia water storage tank;
an overhaul operating platform and a ladder climbing walkway are arranged outside the ammonia water storage tank;
a filter and a pressure instrument are embedded in the centrifugal pump, two of the three centrifugal pumps are common centrifugal pumps, and the other centrifugal pump is a standby centrifugal pump;
the invention also relates to a method for denitration by using the flue gas denitration device for the pot-type furnace, which is characterized by comprising the following steps: the method comprises the following steps:
firstly, dividing 640 tank furnaces into 4 groups of tank furnace groups, configuring 20 waste heat boilers to absorb waste heat, connecting an outlet of each tank furnace to a high-temperature superheater of the waste heat boilers through horizontal collection flues, and uniformly distributing 5-7 reducing agent adding points on each horizontal collection flue;
secondly, installing an SNCR ammonia spraying grid at each reducing agent adding point, wherein the SNCR ammonia spraying grid is sequentially installed and connected with a mixed gas conveying pipeline, a mixer, a heater, a dilution fan, an ammonia water vaporizer, an ammonia water supply pump, an ammonia water storage tank, an auxiliary facility automatic ammonia water unloading device, a collecting pipeline, a process water conveying pipeline, a drainage device, a wastewater conveying pipeline, a wastewater pump, a wastewater pit and a wastewater treatment device;
thirdly, storing enough 20% ammonia water in an ammonia water storage tank, and stably controlling the pressure through an adjusting feed pump of a pressure control loop so as to keep the pressure value within a proper parameter range;
fourthly, 20 percent ammonia water is delivered to an ammonia water vaporizer by an ammonia water supply pump,
fifthly, inputting low-pressure saturated steam with a certain pressure, enabling an ammonia water vaporizer to release latent heat through condensation of the low-pressure saturated steam to heat and vaporize the ammonia water, enabling the steam to enter a shell pass of an evaporator through a pipeline, condensing, releasing heat, cooling, exchanging heat with the ammonia water in a tube pass, enabling the ammonia water to absorb heat, raise temperature and evaporate, enabling the ammonia water to be changed into ammonia water vapor, mixing the ammonia water vapor with air which is conveyed by a dilution fan and heated by an electric heater to form mixed steam with the concentration of 3-5% (v%) ammonia gas, enabling the mixed steam to be discharged from a mixer and then sent to an SNCR ammonia spraying grid, and discharging steam condensate; evaporating 20% ammonia water to obtain ammonia/water vapor mixture;
sixthly, when the temperature of the ammonia water storage tank is higher, adding process water to absorb/dilute ammonia gas through a process water conveying pipeline so as to balance the pressure inside and outside the storage tank;
seventhly, flushing the ammonia water pipeline of the ammonia water flowing area during the shutdown of the system, collecting flushing water of the ammonia water pipeline into a waste water pit through a waste water conveying pipeline, and pumping the flushing water to a desulfurization system for recycling through a waste water pump;
the process water in the sixth step is desalted water, plasma water or condensed water, and the water quality meets the following conditions:
total hardness (as CaCO)3Is shown)<150μg/g
Conductivity < 250. mu.s/cm
·SiO2<15μg/g
Total amount of metal (iron, zinc, lead, manganese, chromium, nickel, copper) < 1. mu.g/g
Sodium < 5. mu.g/g
Orthophosphate, arsenic, mercury < 1. mu.g/g
Solid suspension <10NTU
Sulfate < 10. mu.g/g
The pH value is 7 to 9.
The invention relates to a flue gas denitration device and a denitration method for a pot-type furnace, wherein nozzles are uniformly distributed on a horizontal collection flue of the pot-type furnace, 20% ammonia water is used as a denitration reducing agent, an ammonia water vaporizer evaporates the ammonia water into ammonia water vapor through low-pressure saturated steam, and the ammonia water vapor is mixed with preheated air for dilution to reduce the concentration of ammonia gas to less than 5%. The ammonia injection grid is added to a proper position of an outlet flue of a calcining furnace, so that the denitration efficiency can be high, the ammonia escape can be reduced, the emission of nitrogen oxides in a production line of the pot furnace reaches the standard, the service life of the flue is prolonged, flushing water in the denitration process can be recycled, and no wastewater is generated; compact structure, simple process, small occupied space and low cost investment.
Drawings
FIG. 1 is a schematic diagram of a flue gas denitration apparatus for a tank furnace according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of an ammonia water evaporator in a flue gas denitration device for a tank furnace according to an embodiment of the invention.
Detailed Description
As shown in the figure, the equipment base of the flue gas denitration device for the pot-type furnace is that 4 groups of pot-type furnaces which are built for producing a calcined petroleum coke production line are 640 in total, 32 pots are one, 20 calcining furnaces are totalized, the outlet of each pot-type furnace is connected to a high-temperature superheater of a waste heat boiler through a horizontal collection flue, waste heat flue gas in the production process of the pot-type furnaces is sent to two sets of desulfurization devices through an induced draft fan and is discharged after sulfur dioxide and dust are removed through wet electric dust removal after waste heat is absorbed by the 20 waste heat boilers;
the process principle is as follows:
the selective non-catalytic reduction (SNCR) flue gas denitration technology is one of the main flue gas denitration technologies at present. NH in the narrow temperature range of 800-1250 ℃ of the flue gas without the action of a catalyst3Or urea and other amino reducing agents can selectively reduce NOx in the smoke and basically do not react with O in the smoke2Accordingly, the SNCR method has been developed. NH within the range of 800-1250 DEG C3Or the main reactions of urea to reduce NOx are:
ammonia as reductant 4NH3+4NO+O2→4N2+6H2O
Using urea as reducing agent CO (NH)2)2→2HN2+CO
NH2+NO→N2+H2O
NO+CO→N2+CO2
When the temperature is too high, part of the ammonia reducing agent is oxidized to generate NOXSide reactions occur:
4NH3+5O2→4NO+6H2O
the SNCR technology is a mature denitration technology and has wide application at home and abroad. Particularly, the SNCR has certain advantages on small coal-fired, oil-fired and gas-fired units or industrial boilers and kilns.
The main technical parameters and technical requirements are as follows:
and (3) treating the total smoke gas: 250000Nm3The/h/table cover is provided with two sets;
the original data of the smoke is automatically detected by the second party to be used as the basis of the final design;
flue gas temperature: SNCR at 850-1100 deg.C;
adopting an SNCR denitration process scheme, the SNCR denitration process requires that the denitration efficiency is not less than 50% or the NOx emission concentration is less than 50mg/m3；
The ammonia escape of the SNCR denitration process is less than 8mg/m3；
Ammonia water storage tank capacity 45m3(the requirement of a transport tank car is met), and the ammonia area meets the requirement of safety specifications;
2 portable nitrogen oxide detectors and ammonia escape detectors, 2 sets of nitrogen oxide on-line detectors (old people) and ammonia escape on-line detectors are arranged on site;
steam parameters: the pressure is 0.3Mpa, and the temperature is 150 ℃;
the denitration scheme comprises the following steps:
20% ammonia water is adopted as the engineering denitration reducing agent.
Combining practical conditions, this engineering adopts the ammonia water evaporimeter, evaporates the aqueous ammonia into the mist of ammonia/steam, and through the dilution of dilution wind, the concentration that reduces the ammonia is less than 5%. Is added into a proper position of an outlet flue of the calcining furnace through an ammonia injection grid.
20 sets of SNCR denitration devices are constructed in a matched manner for 20 calcining furnaces in the project, and a reducing agent adding point is positioned at a proper position of a flue between an outlet of the calcining furnace and a high-temperature superheater of a waste heat boiler. Each calcining furnace is provided with 2-3 adding points.
The specific technical structure is as follows:
1. ammonia water preparation and storage system
On the basis of the constructed equipment layout and site conditions, by referring to the denitration process in the prior art, a reducing agent adopts 20% ammonia water, the ammonia water is stored in an ammonia water storage tank, and an inlet of the ammonia water storage tank is connected with an automatic ammonia water discharging device to form an ammonia water preparation and storage system;
the automatic ammonia water unloading device comprises an ammonia water unloading pump, and the ammonia water unloading pump is connected between a tank car for transporting the ammonia water solution and an ammonia water storage tank through a conveying pipeline; the ammonia water is transported to an ammonia water storage area by a tank car and is conveyed to an ammonia water storage tank by an ammonia water discharge pump.
The project of the period is provided with 1 ammonia water storage tank with the volume of 45m3. The ammonia water storage tank is a vertical normal-pressure container made of stainless steel. The inlet of the ammonia tank medium is a tank truck unloading pipeline, and the outlet of the ammonia tank medium is a suction pipeline of an ammonia pump. In order to ensure that the ammonia water tank has enough ammonia water and the pressure is proper, the ammonia water tank needs to be provided with additional facilities such as a liquid level meter, a single suction valve, a water seal device, spraying and the like. In order to facilitate maintenance, inspection and operation, an overhaul operation platform needs to be configured outside the ammonia water tank, and corresponding stairs, ladder climbing walkways and the like are arranged.
2. Ammonia water supply system
The outlet of the ammonia water storage tank is connected with an ammonia water vaporizer through an ammonia water supply pump to form an independent high-flow transmission system, the system comprises three full-flow multistage centrifugal pumps which are connected in parallel between the ammonia water storage tank and the ammonia water vaporizer, two of the three centrifugal pumps are common centrifugal pumps, and the other centrifugal pump is a standby centrifugal pump, namely, two pumps and one standby pump are used; a filter is embedded in the centrifugal pump, and the filter is used for remotely controlling and monitoring the pressure instrument of the ammonia water conveying and circulating system;
the ammonia water supply pump is connected with a pressure control loop and used for adjusting the stable pressure required by the ammonia water supply pump for supplying ammonia water to the ammonia water vaporizing device, and 2 sets of the ammonia water supply pump are arranged.
3. Ammonia water evaporation system
An inlet at the top of one side of the ammonia water storage tank is connected to an automatic ammonia water discharging device through a pipeline, an outlet at the lower part of the side wall of the other side of the ammonia water storage tank is connected to an ammonia water inlet on the wall part of an ammonia water vaporizer through an ammonia water supply pump, a steam inlet is arranged at the bottom of the ammonia water vaporizer, the steam inlet is connected with a low-pressure saturated steam conveying pipeline, an ammonia water gas outlet is arranged at one side of the top of the ammonia water vaporizer, and the ammonia; the ammonia water vaporizer body is provided with an evaporator area positioned at the lower part and a buffer area positioned at the upper part, a tube array type heat exchange tube is arranged in the evaporator area, one end of the heat exchange tube is connected to an ammonia water inlet on the wall part of the ammonia water vaporizer, the other end of the heat exchange tube is connected to an ammonia water gas outlet, so that the tube side of the heat exchange tube forms an ammonia water circulation channel, and the shell side of the ammonia water vaporizer forms a low-pressure saturated steam circulation; an outlet of the ammonia water vaporizer is connected to a reducing agent adding point on the flue through an ammonia spraying grid by a mixed gas conveying pipeline, and a mixer is arranged on the mixed gas conveying pipeline; forming an ammonia water evaporation system;
the ammonia water vaporizer releases latent heat through low-pressure saturated steam condensation to heat and evaporate the ammonia water, steam enters an ammonia water vaporizer shell pass through a pipeline, is condensed, releases heat and cools, exchanges heat with the ammonia water in a tube pass, absorbs heat, heats and evaporates the ammonia water to become ammonia gas mixed gas, the ammonia gas mixed gas is delivered to an SNCR ammonia spraying grid after exiting the ammonia water vaporizer, and steam condensate water is discharged after being drained.
Ammonia water vaporizer body: a lower evaporator area and an upper buffer area are designed, the evaporator area completes ammonia water heat exchange and evaporation, and a tube type heat exchange tube is arranged inside the evaporator area; the buffer zone has the effects of stabilizing and buffering the ammonia gas mixture, and guiding and recovering the condensate.
The main control points are as follows: the pressure and the temperature of the ammonia mixed gas at the outlet of the ammonia water vaporizer, the ammonia water liquid level of the ammonia water vaporizer, the temperature and the pressure of the ammonia water, and the like; adjusting the adding amount of inlet low-pressure saturated steam, and controlling the pressure and temperature of outlet ammonia mixed gas; the adding amount of the imported ammonia water is adjusted, the liquid level of the ammonia water in the ammonia water vaporizer is controlled to be constant, and the evaporator is ensured to have enough evaporation area.
In the engineering, 2 sets of ammonia water vaporizers are arranged, 1 set of ammonia water vaporizers is shared by 10 calcining furnaces, and the ammonia water vaporizers are arranged at proper positions in the middles of the calcining furnaces nearby.
4. Dilution air system
The mixer is also connected with a dilution fan to form a dilution air system;
evaporating 20% ammonia water into mixed gas of ammonia gas/water vapor through saturated steam with a certain pressure, diluting the ammonia concentration of the mixed gas to 3-5% (v%) through a dilution fan, and entering a proper position of a flue through an ammonia injection grid to perform SNCR denitration reaction so as to ensure the safe and stable operation of the system, wherein the two dilution fans are arranged and one fan is used for standby;
and a heater is arranged between the dilution fan and the mixer to heat dilution air, so that the denitration reaction effect is ensured.
5. Water supply and drainage system and wastewater treatment system
A water supply and drainage system:
the top of the ammonia water storage tank is also connected with a process water conveying pipeline, one side of the bottom of the ammonia water vaporizer is provided with an ammonia discharge and flushing water outlet, the ammonia discharge and flushing water outlet is connected with a waste water pit through a waste water conveying pipeline, and the waste water pit is connected with a waste water treatment device through a waste water conveying pipeline; the other side of the bottom of the ammonia water vaporizer is provided with a drainage device;
an ammonia discharge and flushing water outlet is also formed in the position, below the side wall outlet, of the ammonia water storage tank, and the ammonia discharge and flushing water outlet of the ammonia water storage tank is also connected to the waste water pit through a waste water conveying pipeline;
the top of the outlet side of the ammonia water storage tank is also provided with a collecting pipeline which is connected to a pipeline between the ammonia water supply pump and the ammonia water vaporizer;
when the temperature of the ammonia water storage system is high, ammonia gas can be emitted from the storage tank, and at the moment, water is added to absorb/dilute the ammonia gas, so that the internal and external pressures of the storage tank are balanced, and the safe operation of the storage tank is ensured.
The invention also relates to a method for denitration by using the flue gas denitration device for the pot-type furnace, which is characterized by comprising the following steps: the method comprises the following steps:
firstly, dividing 640 tank furnaces into 4 groups of tank furnace groups, configuring 20 waste heat boilers to absorb waste heat, connecting an outlet of each tank furnace to a high-temperature superheater of the waste heat boilers through horizontal collection flues, and uniformly distributing 2-3 reducing agent adding points on each horizontal collection flue;
secondly, installing an SNCR ammonia spraying grid at each reducing agent adding point, wherein the SNCR ammonia spraying grid is sequentially installed and connected with a mixed gas conveying pipeline, a mixer, a heater, a dilution fan, an ammonia water vaporizer, an ammonia water supply pump, an ammonia water storage tank, an auxiliary facility automatic ammonia water unloading device, a collecting pipeline, a process water conveying pipeline, a drainage device, a wastewater conveying pipeline, a wastewater pump, a wastewater pit and a wastewater treatment device;
thirdly, storing enough 20% ammonia water in an ammonia water storage tank, and stably controlling the pressure through an adjusting feed pump of a pressure control loop so as to keep the pressure value within a proper parameter range;
fourthly, 20 percent ammonia water is delivered to an ammonia water vaporizer by an ammonia water supply pump,
fifthly, inputting low-pressure saturated steam with a certain pressure, enabling an ammonia water vaporizer to release latent heat through condensation of the low-pressure saturated steam to heat and evaporate the ammonia water, enabling the steam to enter a shell pass of the evaporator through a pipeline, condensing, releasing heat, cooling, exchanging heat with the ammonia water in a tube pass, enabling the ammonia water to absorb heat, raise temperature and evaporate to become ammonia gas mixed gas, sending the ammonia gas mixed gas out of the ammonia water vaporizer to an SNCR ammonia spraying grid, and discharging steam condensate water through a drainage device; evaporating 20% ammonia water to obtain ammonia/water vapor mixture;
sixthly, when the temperature of the ammonia water storage tank is higher, adding process water to absorb/dilute ammonia gas through a process water conveying pipeline so as to balance the pressure inside and outside the storage tank;
seventhly, flushing the ammonia water pipeline of the ammonia water flow passing area during the shutdown of the system, collecting flushing water of the ammonia water pipeline into a waste water pit through a waste water conveying pipeline, and pumping the flushing water to a desulfurization system through a waste water pump for recycling;
the process water in the sixth step is desalted water, plasma water or condensed water, and the water quality meets the following conditions:
total hardness (as CaCO)3Is shown)<150μg/g
Conductivity < 250. mu.s/cm
·SiO2<15μg/g
Total amount of metal (iron, zinc, lead, manganese, chromium, nickel, copper) < 1. mu.g/g
Sodium < 5. mu.g/g
Orthophosphate, arsenic, mercury < 1. mu.g/g
Solid suspension <10NTU
Sulfate < 10. mu.g/g
The pH value is 7 to 9.
The design idea is as follows:
1. proper ammonia steam nozzles are uniformly distributed in the horizontal collecting flue of the tank furnace.
2. The temperature of the flue gas of the pot furnace is 800-1100 ℃. The furnace path is made of refractory materials, the inner diameter of the flue is small, the traditional process of spraying the ammonia water solution by the SNCR spray gun is adopted, the solution is very easy to spray on the inner wall of the flue, the surface temperature of the refractory materials is rapidly reduced, the refractory materials are damaged, meanwhile, the water content of flue gas of the tank furnace is high, if the concentration of nitrogen oxide is low, the consumption of the reducing agent is very low, in order to ensure the effect of the spray gun, the concentration of ammonia water in the sprayed reducing agent is diluted to be below 5 percent by demineralized water, the water added into the system is increased, and the subsequent system is affected. Therefore, the technology of directly spraying ammonia water is not suitable, the ammonia water evaporator is adopted to vaporize the ammonia water in combination with actual conditions, the ammonia water is diluted by the dilution fan, the concentration of the ammonia gas is reduced to be less than 5%, the ammonia gas is added into a proper temperature area of a flue outlet through the grating, and the nitrogen oxide is ensured to be discharged up to the standard.
3. The reasonable production structure of allotting optimizes furnace temperature control, guarantees suitable flue gas temperature interval, improves denitration efficiency.
4. And reasonably adjusting the flow of the ammonia water and the temperature of the ammonia steam according to the data of the on-line monitoring of the nitrogen oxides and the ammonia escape.
5. The implementation process comprises the following steps:
1) and customizing and installing corresponding equipment according to the process flow diagram.
2) After the installation is finished, the debugging is elaborately carried out.
3) Organizing and training, checking and going on duty, and keeping compliance with safety regulations and operation regulations.
4) And the system is regularly patrolled and examined, so that accident potential can be eliminated in time, and the equipment is ensured to be well installed.
5) The improved NOx-removing agent has ideal effect, and the NOx can reach the standard and be discharged.
Claims (10)
1. The utility model provides a flue gas denitration device for pot-type stove, includes by the combination of many pot-type calciners the production line that constitutes, be used for producing the petroleum coke of calcining back, every calcine the high temperature over heater that the burning furnace export is connected to exhaust-heat boiler through the flue, its characterized in that: each calcining furnace is connected to a flue of the waste heat boiler and is provided with at least one reducing agent adding point, and the reducing agent is 20% ammonia water; the ammonia water is stored in an ammonia water storage tank, an inlet of the ammonia water storage tank is connected with an automatic ammonia water discharging device, an outlet of the ammonia water storage tank is connected with an ammonia water vaporizer through an ammonia water supply pump, an outlet of the ammonia water vaporizer is connected to a reducing agent adding point on a flue through an ammonia spraying grid through a mixed gas conveying pipeline, a mixer is arranged on the mixed gas conveying pipeline, and the mixer is also connected with a dilution fan;
an inlet at the top of one side of the ammonia water storage tank is connected to an automatic ammonia water discharging device through a pipeline, and is also connected with a process water conveying pipeline; an outlet at the lower part of the side wall of the other side of the ammonia water storage tank is connected to an ammonia water inlet of the wall of the ammonia water vaporizer through an ammonia water supply pump, and the ammonia water supply pump is connected with a pressure control loop;
the ammonia water supply pump comprises three full-flow multistage centrifugal pumps, and the three centrifugal pumps are connected in parallel between the ammonia water storage tank and the ammonia water vaporizer;
the bottom of the ammonia water vaporizer is provided with a steam inlet, the steam inlet is connected with a low-pressure saturated steam conveying pipeline, one side of the top of the ammonia water vaporizer is provided with an ammonia water vapor outlet, and the ammonia water vapor outlet is connected to the mixer through a mixed gas conveying pipeline; the ammonia water vaporizer body is provided with an evaporator area positioned at the lower part and a buffer area positioned at the upper part, a tube array type heat exchange tube is arranged in the evaporator area, one end of the heat exchange tube is connected to an ammonia water inlet on the wall part of the ammonia water vaporizer, the other end of the heat exchange tube is connected to an ammonia water gas outlet, so that the tube side of the heat exchange tube forms an ammonia water circulation channel, and the shell side of the ammonia water vaporizer forms a low-pressure saturated steam circulation;
an ammonia discharge and flushing water outlet is formed in one side of the bottom of the ammonia water gasifier, the ammonia discharge and flushing water outlet is connected with a waste water pit through a waste water conveying pipeline, and the waste water pit is connected with a waste water treatment device through a waste water conveying pipeline; the other side of the bottom of the ammonia water vaporizer is provided with a drainage device;
an ammonia discharge and flushing water outlet is also formed in the position, below the side wall outlet, of the ammonia water storage tank, and the ammonia discharge and flushing water outlet of the ammonia water storage tank is also connected to the waste water pit through a waste water conveying pipeline;
a heater is arranged between the dilution fan and the mixer.
2. The flue gas denitration device for the tank furnace as set forth in claim 1, wherein: and the ammonia gas concentration after the ammonia water vapor outlet is conveyed to the mixer and mixed with the preheated air is 3-5% (v%).
3. The flue gas denitration device for the tank furnace as set forth in claim 1, wherein: and a waste water pump is arranged on the waste water conveying pipeline, and the waste water treatment device is a desulfurization system of the waste heat boiler.
4. The flue gas denitration device for the tank furnace as set forth in claim 1, wherein: the top of the outlet side of the ammonia water storage tank is also provided with a collecting pipeline which is connected to a pipeline between the ammonia water supply pump and the ammonia water vaporizer.
5. The flue gas denitration device for the tank furnace as set forth in claim 1, wherein: the automatic ammonia water discharging device comprises an ammonia water discharging pump, and the ammonia water discharging pump is connected between a tank car for transporting the ammonia water solution and an ammonia water storage tank through a conveying pipeline.
6. The flue gas denitration device for the tank furnace as set forth in claim 1, wherein: the ammonia water storage tank is a vertical normal-pressure container made of stainless steel materials, and the volume of the container is 45m3(ii) a The outside of the ammonia water storage tank is provided with a liquid level meter, a single suction valve, a water seal device and a spraying device.
7. The flue gas denitration device for the tank furnace as set forth in claim 1, wherein: and an overhauling operation platform and a ladder climbing walkway are arranged outside the ammonia water storage tank.
8. The flue gas denitration device for the tank furnace as set forth in claim 1, wherein: the centrifugal pump is internally embedded with a filter and a pressure instrument, two of the three centrifugal pumps are common centrifugal pumps, and the other centrifugal pump is a standby centrifugal pump.
9. A method of denitration using the flue gas denitration device for a tank furnace according to any one of claims 1 to 8, characterized in that: the method comprises the following steps:
firstly, dividing 640 tank furnaces into 4 groups of tank furnace groups, configuring 20 waste heat boilers to absorb waste heat, connecting an outlet of each tank furnace to a high-temperature superheater of the waste heat boilers through horizontal collection flues, and uniformly distributing 5-7 reducing agent adding points on each horizontal collection flue;
secondly, installing an SNCR ammonia spraying grid at each reducing agent adding point, wherein the SNCR ammonia spraying grid is sequentially installed and connected with a mixed gas conveying pipeline, a mixer, a heater, a dilution fan, an ammonia water vaporizer, an ammonia water supply pump, an ammonia water storage tank, an auxiliary facility automatic ammonia water unloading device, a collecting pipeline, a process water conveying pipeline, a drainage device, a wastewater conveying pipeline, a wastewater pump, a wastewater pit and a wastewater treatment device;
thirdly, storing enough 20% ammonia water in an ammonia water storage tank, and stably controlling the pressure through an adjusting feed pump of a pressure control loop so as to keep the pressure value within a proper parameter range;
fourthly, 20 percent ammonia water is delivered to an ammonia water vaporizer by an ammonia water supply pump,
fifthly, inputting low-pressure saturated steam with a certain pressure, enabling an ammonia water vaporizer to release latent heat through condensation of the low-pressure saturated steam to heat and vaporize the ammonia water, enabling the steam to enter a shell pass of an evaporator through a pipeline, condensing, releasing heat, cooling, exchanging heat with the ammonia water in a tube pass, enabling the ammonia water to absorb heat, raise temperature and evaporate, enabling the ammonia water to be changed into ammonia water vapor, mixing the ammonia water vapor with air which is conveyed by a dilution fan and heated by an electric heater to form mixed steam with the concentration of 3-5% (v%) ammonia gas, enabling the mixed steam to be discharged from a mixer and then sent to an SNCR ammonia spraying grid, and discharging steam condensate; evaporating 20% ammonia water to obtain ammonia/water vapor mixture;
sixthly, when the temperature of the ammonia water storage tank is higher, adding process water to absorb/dilute ammonia gas through a process water conveying pipeline so as to balance the pressure inside and outside the storage tank;
and seventhly, flushing the ammonia water pipeline of the ammonia water flowing area during the shutdown of the system, collecting flushing water of the ammonia water pipeline into a waste water pit through a waste water conveying pipeline, and pumping the flushing water to the desulfurization system for recycling through a waste water pump.
10. The method of denitration by the flue gas denitration device for the tank furnace as set forth in claim 9, wherein: the process water in the sixth step is desalted water, plasma water or condensed water, and the water quality meets the following conditions:
total hardness (as CaCO)3Is shown)<150μg/g
Conductivity < 250. mu.s/cm
·SiO2<15μg/g
Total amount of metal (iron, zinc, lead, manganese, chromium, nickel, copper) < 1. mu.g/g
Sodium < 5. mu.g/g
Orthophosphate, arsenic, mercury < 1. mu.g/g
Solid suspension <10NTU
Sulfate < 10. mu.g/g
The pH value is 7 to 9.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111672319A (en) * | 2020-07-22 | 2020-09-18 | 天津中材工程研究中心有限公司 | Reducing agent preparation and supply system for low-temperature SCR denitration and working method |
| CN112705030A (en) * | 2021-01-26 | 2021-04-27 | 山西远航环境科技股份有限公司 | Denitration method of small-sized heat storage combustion furnace |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104415660A (en) * | 2013-09-02 | 2015-03-18 | 北京美斯顿科技开发有限公司 | Novel flue gas denitrification device of CO waste heat boiler |
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- 2019-11-15 CN CN201911120595.3A patent/CN110787609A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104415660A (en) * | 2013-09-02 | 2015-03-18 | 北京美斯顿科技开发有限公司 | Novel flue gas denitrification device of CO waste heat boiler |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111672319A (en) * | 2020-07-22 | 2020-09-18 | 天津中材工程研究中心有限公司 | Reducing agent preparation and supply system for low-temperature SCR denitration and working method |
| CN112705030A (en) * | 2021-01-26 | 2021-04-27 | 山西远航环境科技股份有限公司 | Denitration method of small-sized heat storage combustion furnace |
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