CN105944533A - Method of denitrating three-waste co-combustion boiler flue gas with waste gas discharged from production of urea - Google Patents
Method of denitrating three-waste co-combustion boiler flue gas with waste gas discharged from production of urea Download PDFInfo
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- CN105944533A CN105944533A CN201511017073.2A CN201511017073A CN105944533A CN 105944533 A CN105944533 A CN 105944533A CN 201511017073 A CN201511017073 A CN 201511017073A CN 105944533 A CN105944533 A CN 105944533A
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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
- B01D53/74—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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- 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
- B01D2251/2067—Urea
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/02—Other waste gases
- B01D2258/0283—Flue gases
Abstract
The invention discloses a method of denitrating three-waste co-combustion boiler flue gas with waste gas discharged from production of urea. The method includes the steps of: recycling the gas discharged from a tail gas column of a urea production apparatus; transporting the gas to a tail gas separator through a pipeline; transporting the gas to a high-temperature section of the three-waste co-combustion boiler flue gas through a pressurizing fan blower; and with the ammonia gas in the tail gas as a reducing agent or the urea as a reducing agent, uniformly ejecting the tail gas into an 850-1250 DEG C temperature range zone of the boiler flue gas without a catalyst, so that the NOx in the three-waste co-combustion boiler flue gas is selectively reduced to N2 and H2O under the condition of existence of a part of oxygen, thereby achieving emission reduction of the NOx.
Description
Technical field
The invention belongs to Coal Chemical Industry, cogeneration of heat and power field, particularly relate to a kind of waste gas pair utilizing urea production to discharge
The three wastes mix the method that combusting boiler flue gas carries out denitration.
Background technology
NOx emission is one of major pollutants of atmospheric environment.For reducing the NOx emission water of coal fired thermal power plant
Flat, China is the most formal issued " fossil-fuel power plant atmospheric pollutant emission standard " (GB13223-1996), " in
People's republic of China atmospheric pollution Protection Code " (in JIUYUE, 2000 is implemented), " thermal power plant's Air Pollutant Emission mark
Accurate " a series of countries and the standard of industry, the regulation such as (GB13223 2011), it is desirable to domestic all thermoelectricitys
Factory and other coal combustion equipments are intended to take the Mitigation options of necessity to control NOx emission.
" fossil-fuel power plant atmospheric pollutant emission standard " (GB13223-2011) requirement, existing fluidized-bed combustion boiler from
Rise on July 1st, 2014, newly-built fluidized-bed combustion boiler performed NOx emission concentration from 1 day January in 2012
200mg/Nm3Standard, key area perform 100mg/Nm3NOx emission concentration standard.This standard is very
More strict to the discharge standard than European and American developed countries, have expressed the Chinese government and pollute controlling thermoelectricity NOx
The firm resolution of thing discharge, also reflects that the order of severity of China's environmental pollution and pollution treatment reduce discharging the urgent of situation
Property.
Summary of the invention
The purpose of the present invention is to propose to that a kind of cost is relatively low, alkali resistance utilizes carbamide with acid resistance preferably one
The three wastes are mixed the method that combusting boiler flue gas carries out denitration by the waste gas producing discharge.
The present invention adopts the following technical scheme that to achieve these goals
The three wastes are mixed the method that combusting boiler flue gas carries out denitration, its feature by a kind of waste gas utilizing urea production to discharge
It is: reclaim the gas of tail gas tower discharge in urea plant, be pipelined to Reconstruction of End Gas Separator, then
Be transported to the three wastes through booster fan and mix combusting boiler fume high-temperature section, by the ammonia in tail gas as reducing agent or
Person uses carbamide as reducing agent, and uniformly spraying into boiler smoke temperature range on the premise of not using catalyst is
The region of 850～1250 DEG C, under conditions of with the presence of part oxygen, optionally mixes combusting boiler flue gas the three wastes
In NOx be reduced to N2And H2O, to reach to reduce discharging the purpose of NOx.
The three wastes are mixed the method that combusting boiler flue gas carries out denitration by described a kind of waste gas utilizing urea production to discharge,
It is characterized in that: the oxygen volume content of described part oxygen existence condition is 3 6%.
The three wastes are mixed the method that combusting boiler flue gas carries out denitration by described a kind of waste gas utilizing urea production to discharge,
It is characterized in that: the time of reduction reaction is 0.4-0.6s.
The three wastes are mixed the method that combusting boiler flue gas carries out denitration by described a kind of waste gas utilizing urea production to discharge,
It is characterized in that: in reaction, amino and the mol ratio of NO are at 1.2-1.5.
The principle of the present invention is:
1, SNCR denitration principle
SNCR technology (SNCR), is the reducing agent (ammonia or ammonia) containing amino
The region that boiler smoke temperature range is 850～1250 DEG C is uniformly sprayed on the premise of not using catalyst,
Under conditions of part oxygen, optionally the NOx in flue gas is reduced to N2And H2O, to reach
Reduce discharging the purpose of NOx.
Ammonia or the ammonia is used as the main chemical reactions of reducing agent to be:
4NO+4NH3+O2→4N2+6H2O
4NH3+2NO2+O2→3N2+H2O,
2, the advantage of SNCR denitration technology
2.1, technological process is simple, and cost of investment is low, does not use catalyst, and operating cost is low, and economic advantages are obvious.
2.2, need not boiler is carried out structural transformation, the construction period is short.
2.3, production technology is had no adverse effects, without adjusting the operation of other equipment after transformation use.
2.4, SNCR denitration is wide to environmental suitability, and its by-product is mainly N2 and H2O, therefore will not to environment
Produce secondary pollution.
2.5, liquid or solid waste material is not produced compared with SCR.
2.6, being relatively suitable for China's existing medium small boiler transformation, denitration efficiency is about 50%～60%, it is possible to and
Low nitrogen burning or grading combustion technology are used in conjunction with.
SNCR technology is put into operation use certified highly developed gas denitrifying technology, at present in state
Inside promoting the use of, effect is fine.Domestic Scientific Research institutes, authoritative department are unanimously assert in the recent period, SNCR technology
It it is the gas denitrifying technology of the mature and reliable being best suitable for China's practical situation.
3, the influence factor of SNCR denitration efficiency
3.1, temperature range
The reduction reaction of NOx occur within the scope of a specific temperature (optimal reaction temperature interval 850 DEG C～
1250℃).If temperature is too low, the reaction of NH3 is incomplete, easily causes NH3 escape and forms secondary pollution；
And temperature too high (more than 1400 DEG C), NH3 is then oxidized easily as NOx.Visible too high or too low for temperature
Loss and the NOx removal rate that will cause reducing agent decline.
3.2, reactant and the degree of flue gas mixing
The mixability of reducing agent and flue gas determines process and the speed of reaction, and reducing agent and flue gas are in boiler flue
Being the reaction of mixing limit, limit, the effect of mixing directly determines the height of denitration efficiency.SNCR denitration efficiency is low
One of the most former be exactly mixed problem, such as, the NOx concentration of local is too high, it is impossible to be reduced agent reduction,
The NOx concentration causing the low local of denitration efficiency is too low, and reducing agent the most all occurs reduction reaction, causes reduction
Agent utilization rate is low, also increases the escaping of ammonia.Therefore, the mixability of reducing agent and flue gas is whether abundant, directly
Affect denitration effect.
3.3, the time of Solution dwell
Solution dwell (chemical reaction) time: the total time that within the scope of suitable temperature, reactant stops in reactor.
In at this moment, the reducing agent such as NH3 or carbamide and the mixing of flue gas, evaporation of water, the decomposition of reducing agent and
The steps such as the reduction of NOx must be fully completed, and typically wanting seeking time is 0.5s.And the ammonia of spray pattern is at boiler water
The time of staying length of flat flue depends on that the size of horizontal flue, flue gas flow through the speed of flue, solution atomization
The factors such as the form that situation, mist field mix with flue gas.
3.4, ammonia nitrogen ratio (NSR)
I.e. amino and the molar ratio of NO in reaction, react according to SNCR, and reduction 1mol NO needs 1mol ammonia
Or 0.5mol carbamide, but in reality, the amount of reducing agent is bigger than this amount, because real reaction is more complicated,
And gas mixing is uneven, preferable denitration effect to be reached and be necessary for increasing reduction dosage.Along with ammonia nitrogen ratio
Increasing denitration efficiency to increase, the escaping of ammonia also can increase, and cost raises, the economy (NSR) of current boiler SNCR,
General control is at about 1.2-1.5.
3.5, other factors
Oxygen content, the content of initial NOx in flue gas, reducing agent type and state etc. all can affect the height of denitration efficiency
Low.
Beneficial effects of the present invention: urea plant system high pressure section, intermediate pressure section, low pressure stage and evaporation prilling section are put
In empty tail gas, ammonia content is the most higher, not only increases ammonia cost, also has certain pollution to surrounding, pass through
The modes such as washing, hydrolysis all can not thoroughly solve ammonia emission problem, mixes combusting boiler carry out by being recovered to the three wastes
After denitration, not only reducing denitration cost, reached denitration effect, the more important ammonia that solves is to surrounding
Pollute.
Accompanying drawing explanation
Fig. 1 is under different temperatures, the different reducing agents (carbamide or the ammonia) reduction efficiency to NOx；
Fig. 2 is that the three wastes are mixed combusting boiler flue gas and carry out the technique stream of denitration by the waste gas utilizing urea production to discharge
Cheng Tu.
Detailed description of the invention
Embodiment 1,
75t/h three-waste mixed fired boiler denitration technology scheme
1, project profile
The three-waste mixed fired boiler of this TV station 75t/h, main ignition temperature is at 950-1050 DEG C, under current boiler situation at full capacity
It is about 450-500mg/m after the discharge capacity conversion of NOx3, operation oxygen amount is 8%-10%.
2, design condition
2.1, the major parameter of three-waste mixed fired boiler
Table 2.1 Boiler Main Parameter
2.2, the load of boiler: 60-110%
2.3, three-waste mixed fired boiler compound granularity≤10mm, fuel is gas-making cinder, gangue, colm.
3, the selection of the three-waste mixed fired boiler denitration scheme of 75t/h
SNCR denitration technique is selected according to three-waste mixed fired boiler practical situation
3.1, due to a set of denitrating system original in factory, former denitrating system is mainly used for 3 recirculating fluidized beds in factory
Denitration in Boiler, therefore this is planned to the three-waste mixed fired boiler denitrating system of construction, can save and above make ammonia
Conveying and dilution part, the ammonia after directly former denitrating system being diluted is transported to battery limit (BL), 75 tons of mixed combustions of the three wastes
Stove battery limit (BL) design flow distribution module and spraying system, the compressed gas of atomization uses tail gas tower row in urea plant
The gas put, the First air that purging elegance exports with primary air fan.
(1) injection metering and distributor
Injection metering and distribution module are set before this TV station three-waste mixed fired boiler, each module by 6 flow measurements and
Operated pneumatic valve equipment forms.For accurate measurement and independent control to each inlet zone of boiler reactant flow and
Concentration.This TV station three-waste mixed fired boiler respectively sets three spray guns and sprays into reducing agent in stove in upper flue both sides.
(2) spraying system
Spray gun is the critical component of SNCR system, and the size of its atomization affects the reaction speed of reducing agent and NOx
Degree, spray pattern and air-flow rigidity effects reducing agent and the mixability of flue gas, atomizing particle size is the least, the easiest
Obtain higher NOx removal efficiency.The spray gun atomizing particle degree that my company uses is thin (typically up to 18～40
About μm) and even size distribution, profile exponent N ＞ 2.Adding its architectural characteristic, fluid apertures, pore are equal
Relatively big, and hole count is many, so being difficult to blocking occur.The two-fluid air atomization spray gun that my company uses is porous
Injection structure, the jet face of formation is fan-shaped, covers eject position to greatest extent, it is ensured that reducing agent and flue gas
Good mixing.
Low nitrogen burning+denitrating system performance guarantee value
| Project name | 100% rated load | Remarks |
| Initial NOx concentration (mg/Nm3) | 450-500 | |
| NOx emission concentration (mg/Nm3) | ≤200 | |
| Denitration efficiency (%) | ≥65 | SNCR |
| The escaping of ammonia rate (ppm) | ≤10 |
Embodiment 2,
The three wastes are mixed the method that combusting boiler flue gas carries out denitration by a kind of waste gas utilizing urea production to discharge, and reclaim carbamide
In process units, the gas of tail gas tower discharge, is pipelined to Reconstruction of End Gas Separator, more defeated through booster fan
Deliver to the three wastes and mix combusting boiler fume high-temperature section, as reducing agent or use carbamide conduct by the ammonia in tail gas
Reducing agent, uniformly sprays into the region that boiler smoke temperature range is 950 DEG C on the premise of not using catalyst,
Under conditions of with the presence of part oxygen, the NOx optionally three wastes mixed in combusting boiler flue gas is reduced to N2
And H2O, to reach to reduce discharging the purpose of NOx.The oxygen volume content of described part oxygen existence condition is 5%.
The time of reduction reaction is 0.4s.In reaction, amino and the mol ratio of NO are 1.2.
Out of stock response data see table:
| Project name | 100% rated load | Remarks |
| Initial NOx concentration (mg/Nm3) | 450-500 | |
| NOx emission concentration (mg/Nm3) | ≤200 | |
| Denitration efficiency (%) | ≥65 | SNCR |
| The escaping of ammonia rate (ppm) | ≤10 |
Claims (4)
1. the three wastes are mixed the method that combusting boiler flue gas carries out denitration by the waste gas utilizing urea production to discharge, it is characterized in that: reclaim the gas of tail gas tower discharge in urea plant, it is pipelined to Reconstruction of End Gas Separator, it is transported to the three wastes through booster fan again and mixes combusting boiler fume high-temperature section, as reducing agent or use carbamide as reducing agent by the ammonia in tail gas, the region that boiler smoke temperature range is 850～1250 DEG C is uniformly sprayed on the premise of not using catalyst, under conditions of with the presence of part oxygen, the NOx optionally three wastes mixed in combusting boiler flue gas is reduced to N2And H2O, to reach to reduce discharging the purpose of NOx.
The three wastes are mixed the method that combusting boiler flue gas carries out denitration by a kind of waste gas utilizing urea production to discharge the most according to claim 1, it is characterised in that: the oxygen volume content of described part oxygen existence condition is 3 6%.
The three wastes are mixed the method that combusting boiler flue gas carries out denitration by a kind of waste gas utilizing urea production to discharge the most according to claim 1, it is characterised in that: the time of reduction reaction is 0.4-0.6s.
The three wastes are mixed the method that combusting boiler flue gas carries out denitration by a kind of waste gas utilizing urea production to discharge the most according to claim 1, it is characterised in that: in reaction, amino and the mol ratio of NO are at 1.2-1.5.
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| CN201511017073.2A CN105944533A (en) | 2015-12-29 | 2015-12-29 | Method of denitrating three-waste co-combustion boiler flue gas with waste gas discharged from production of urea |
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| CN201511017073.2A CN105944533A (en) | 2015-12-29 | 2015-12-29 | Method of denitrating three-waste co-combustion boiler flue gas with waste gas discharged from production of urea |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5547650A (en) * | 1994-03-24 | 1996-08-20 | The Regents Of The University Of California | Process for removal of oxides of nitrogen |
| CN103111185A (en) * | 2013-01-17 | 2013-05-22 | 李鑫 | Melamine tail gas utilization method |
| CN104014232A (en) * | 2014-06-24 | 2014-09-03 | 山东大学 | Method for performing smoke desulfurization and denitrification by using urea co-production preparation technology |
| CN204159203U (en) * | 2014-10-30 | 2015-02-18 | 临沂龙源节能技术有限公司 | A kind of flue gas denitrification system being exclusively used in three-waste fluidized mix combustion furnace |
-
2015
- 2015-12-29 CN CN201511017073.2A patent/CN105944533A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5547650A (en) * | 1994-03-24 | 1996-08-20 | The Regents Of The University Of California | Process for removal of oxides of nitrogen |
| CN103111185A (en) * | 2013-01-17 | 2013-05-22 | 李鑫 | Melamine tail gas utilization method |
| CN104014232A (en) * | 2014-06-24 | 2014-09-03 | 山东大学 | Method for performing smoke desulfurization and denitrification by using urea co-production preparation technology |
| CN204159203U (en) * | 2014-10-30 | 2015-02-18 | 临沂龙源节能技术有限公司 | A kind of flue gas denitrification system being exclusively used in three-waste fluidized mix combustion furnace |
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Application publication date: 20160921 |