Product Description
SCR denitrification process description
The dust concentration of the flue gas discharged by the natural gas heating furnace will be below 10mg/Nm.Supporting the hot blast stove regularly to SCR reducing agent thermal analysis;After the hot blast furnace is heated to about 180℃, after spraying ammonia and rectifier grid, it enters the SCR catalyst module to complete the NOx reduction process, and NOx is reduced to non-toxic and harmless N2 into the atmosphere.After denitration, the flue gas is cooled by GGH and discharged into the chimney by induced draft fan.
Features:
1. The operating temperature is low
2. High denitration efficiency
3. There will be no secondary pollution
4. Oxidation rate of SO2 < 1%
SCR denitrification process for steel heating furnace
Take a steel furnace as an example
Smoke volume: 51600Nm3/h
Flue gas temperature: 120~150℃
The inlet NOx acuities were 300 mg/Nm3
The denitration efficiency was 67%
NOX emissions acuities were 100 mg/Nm3
The process of "after natural gas heating furnace +SCR denitration + induced draft fan = standard discharge" is adopted
Suitable for: boiler, chain furnace, circulating fluidized bed, rotary kiln, etc.
SNCR and SCR are commonly used in flue gas denitrification. Compared with SNCR and SCR, SNCR has the following characteristics.
First, the biggest difference between SNCR and SCR is that no catalyst is used in the denitrification process, and it does not lead to oxidation of SO:/SOa, SO the chance of clogging the air preheater is very small.
Second, there is no pressure loss in the whole process, so there is no need to improve the pressure head of the induced draft fan, especially the transformation of the unit does not need to transform the induced draft fan, which saves investment and shortens the construction period.
Third, the equipment required by SNCR occupies a small area, and compared with SCR equipment, it is simple, the construction amount is reduced, and the project implementation time is shortened. For the transformation unit, it is more convenient for the project implementation under the condition of large site restrictions.
Fourth, the whole reduction process of SNCR process is carried out in the boiler, and there is no need to set up another reactor.
The reducing agent is injected into the flue gas through a nozzle mounted on the wall of the boiler.
The nozzles are arranged in the superheater area between the combustion chamber and the economizer. The heat of the boiler provides energy for the reaction, so that NOx is reduced here.
The cancellation of the reactor, the supporting steel structure of the reactor and its auxiliary flue reduces a large part of the investment, reduces most of the installation work, and is more convenient for future overhaul and maintenance work.
System principle
The treatment stages of nitrogen oxides in flue gas are generally divided into early fuel treatment, combustion process control and late flue gas denitrification.Fuel pretreatment is to remove nitrogen from fuel, no industrial application;Combustion process control is mainly to improve the combustion state, control excess air, reduce combustion temperature, etc.The late flue gas denitrification technology is mainly selective non-catalytic reduction reaction technology, selective catalytic reduction reaction technology and combined denitrification technology and the development of integrated denitrification technology.In addition, there are microbial method, electron beam method, activated carbon adsorption method and other technologies, but they have not been applied and promoted in engineering because of the operation cost, operation difficulty and other reasons.The most mature and widely used SCR denitration technology is recommended for the best technical route of gas heating furnace.
heating furnace is about 200℃.Considering that the flue gas volume of this project is small and the sulfur content of flue gas is high, in order to ensure the denitration efficiency and reduce the project cost.This project plans to equip a set of hot blast stove flue gas heating device, heating the original flue gas from 200℃ to 320℃.
Set up a SCR denitration reaction device, a set of reducing agent storage, pyrolysis, uniform distribution system.The flue gas enters the denitrification temperature before 320℃, after spraying ammonia, rectifier grid into the SCR catalyst module, complete the NOx reduction process, NOx is reduced to non-toxic and harmless N2 into the atmosphere;The flue gas after denitration enters the desulfurization tower through induced draft fan for subsequent desulfurization and dust removal treatment.
1. Denitration reactor is the main equipment of flue gas denitration unit.
2. Wear prevention measures should be designed for the parts in the SCR reactor that are easy to wear.
3. The reactor is equipped with catalyst.
4. The design of the reactor takes into account the replacement of different catalysts during its lifetime.
5. The catalyst and renewal inside the reactor shall be lifted.
6. Urea pyrolysis is used to produce ammonia to prevent adverse effects caused by thermal expansion after smoke ventilation.
7. The reactor shall be equipped with a sufficient number and size of manhole doors and observation holes.
8. The reactor shell is made of materials that meet the requirements of use
9. The reactor is required to verify that the pressure adsorption system design is in normal operation, and no air leakage is allowed.
10. The reactor structure design requires the equipment to consider thermal expansion and corrosion resistance to ensure the stable operation of the equipment.
11. The external supporting steel structure of the reactor meets the requirements of structural stability.
12. The top distribution system of the reactor shall be well sealed.
13. The reactor housing uses 6mm thick steel plate, which can withstand internal pressure, seismic load, catalytic load, and thermal pressure, etc.
14. The flue can withstand the following loads: flue dead weight, wind load, earthquake load, dust accumulation, lining and insulation weight, etc.
nsure the safe operation of the reactor, the following measures should be taken for the adsorption tower:
①Material: All equipment and materials are considered resistant to corrosion and wear.
②Uniform airflow: flow field simulation software is used to optimize the design of the adsorption tower, and optimize the layout of the flue gas inlet and outlet.
10）The test pressure of the reactor is required to be under the normal operating pressure of the adsorption system design, and no air leakage is allowed.
11）Thermal expansion, corrosion resistance and wear resistance should be considered in reactor structure design.
Ensure the stable operation of the device.
12）The external supporting steel structure of the reactor should meet the requirements of structural stability.
13）The top distribution system of the reactor shall ensure good tightness, no ash leakage is allowed, and all flange joints shall have gaskets.
14）The reactor housing is reinforced with 6mm thick steel plate and section steel, which can withstand internal pressure (design pressure ±9500), seismic load, catalyst load and thermal stress.
15）The flue is designed to withstand the following loads: flue dead weight, wind load, earthquake load, dust accumulation, lining and insulation weight, etc.
All flues shall be fitted with manhole doors and ash removal holes of sufficient number and size in place to facilitate maintenance and inspection of flues (including expansion joints and baffle doors) and removal of accumulated ash.
In addition, the manhole door and flue wall separate insulation, for easy opening.
The flue is provided with a sufficient number of test holes in appropriate locations according to the standard and a maintenance platform.
