CN108332193A - A kind of coal-burned industrial boiler burning of super burn gas cleaning and flue gas purification system - Google Patents

Abstract

An ultra-gas-clean industrial boiler combustion and flue gas purification system, including a low NOx combustion device and a flue gas purification system, wherein the low NOx combustion device includes a main combustion chamber, a secondary combustion chamber, a burnout chamber, a CFB separator, etc.; The gas purification system includes high temperature dust collector, three-stage SCR adsorption reactor, low temperature dust collector, desulfurization tower and low and low temperature dust collector, etc. The inlet of the three-stage SCR adsorption reactor is sequentially provided with a three-stage SCR reducing agent inlet and a deflector. The middle part of the three-stage SCR adsorption reactor is provided with an adsorbent nozzle. A catalyst layer is arranged between the deflector and the nozzle of the adsorbent. The catalyst layer is provided in several layers. Several catalyst layers are filled with catalysts. The catalyst is a honeycomb vanadium-tungsten-titanium catalyst. The present invention adopts multi-stage purification measures for joint removal of SO ₂ , NOx, PM and heavy metals, so that coal-fired flue gas can reach the emission target of ultra-clean gas, and has practicability.

Description

A super-gas-clean coal-fired industrial boiler combustion and flue gas purification system

technical field

The invention relates to a coal-fired industrial boiler combustion and flue gas purification system, in particular to a coal-fired industrial boiler combustion and flue gas purification system with super gas cleanliness and low emission, which belongs to coal, solid waste, sludge, Combustion equipment and flue gas purification systems for solid fuels such as biomass are especially suitable for use in areas that have high requirements for flue gas emissions but actually lack natural gas and need to use coal instead of natural gas.

Background technique

my country is a country where coal is the main energy source, and coal accounts for more than 70% of my country's primary energy consumption. Due to the shortage of oil and natural gas reserves in our country, this status quo cannot be fundamentally changed in the next 10 to 20 years. Coal has played a huge role in China's development, especially the great progress since the reform and opening up. Nowadays, due to the influence of the environment, especially the pollution of PM2.5 smog, people point the culprit to the utilization of coal, put all the responsibility on coal burning, and take strict measures to simply limit coal burning, but this cannot really solve the problem. In fact, according to BP energy statistics in 2012, according to the R/P ratio, the natural gas in the world can be used for 56 years, the oil can be used for 53 years, and the coal can be used for 110 years. When natural gas and oil run out, coal must also be used. Instead of using coal as a last resort in the future, it is better to rationally plan natural gas, oil and coal now, complement each other and adjust their use, "coal is suitable for coal, and gas is suitable for gas".

As the problem of environmental pollution has become increasingly prominent, the state and localities have formulated very strict pollution discharge standards. For example, the Beijing Boiler Air Pollutant Emission Standard (DB11139-2015) stipulates that whether it is a coal-fired boiler or a gas-fired boiler, it must meet the requirements of the boiler’s particulate matter PM emission ≤5mg/m ³ , SO ₂ ≤10mg/m ³ , NO≤ 30 mg/m ³ . Due to the high ash and sulfur content in coal, the original emissions of particulate matter, NOx and SO ₂ from burning coal will be significantly higher than those from natural gas-fired boilers. Although pollution emissions can be reduced by investing more flue gas treatment facilities, conventional coal-fired boiler combustion methods and flue gas treatment methods have been difficult to meet the corresponding emission standards. At present, there is an urgent need in the market for an economical and efficient coal-fired industrial boiler whose flue gas emissions can meet the stringent local gas-fired boiler emission standards, that is, to achieve "coal-fired boiler super clean gas".

Contents of the invention

The present invention proposes an ultra-gas-clean coal-fired industrial boiler combustion and flue gas purification system, through the "quadruple ternary combination" to reduce PM (particulate matter), NOx (nitrogen oxides), SO ₂ (sulfur dioxide) and heavy metals and other four pollutants are controlled below the emission limits of gas-fired boilers.

The present invention is achieved through the following technical solutions:

A super gas-clean coal-fired industrial boiler combustion and flue gas purification system, including a low NOx combustion device and a flue gas purification system. The low NOx combustion device includes a main combustion chamber, an auxiliary combustion chamber, a burnout chamber, and a CFB separator and a feeding device arranged at the front end of the main combustion chamber; characterized in that:

The flue gas purification system includes a high-temperature dust collector, an economizer, a three-stage SCR adsorption reactor, an air preheater, a low-temperature dust collector, a desulfurization tower, and a low-low temperature dust collector connected in sequence through a flue; the CFB separator Connect with the high-temperature dust collector through the outlet flue of the CFB separator;

The middle part of the main combustion chamber is provided with a primary desulfurizer nozzle, and the upper part of the main combustion chamber is provided with a secondary SNCR denitrification reducing agent nozzle; the middle and lower part of the auxiliary combustion chamber is provided with a secondary desulfurizer nozzle;

Taking the flue gas flow direction as the front-to-back direction, the entrance of the three-stage SCR adsorption reactor is provided with a three-stage SCR reducing agent inlet and a deflector, and the deflector is arranged after the three-stage SCR reducing agent inlet; An adsorbent nozzle is arranged in the middle of the three-stage SCR adsorption reactor; a catalyst layer is also arranged between the deflector and the adsorbent nozzle.

In the above technical solution, the high temperature dust collector is a water-cooled cyclone dust collector.

In the above technical solution, the lower part of the high-temperature dust collector is provided with an ash cooler, and the outlet of the ash cooler is provided with an air lock; the shell of the high-temperature dust collector is surrounded by a water-cooled wall of the separator; the cold ash The device is water-cooled or air-cooled.

In the above technical scheme, the three-stage SCR adsorption reactor is an inverted U-shaped reactor, and the middle of the inverted U-shaped reactor is separated by a reaction partition wall; inside the top.

In the above technical solution, the upper part of the desulfurization tower is provided with a desulfurization absorption liquid feeding device for spraying alkaline absorption liquid.

In the above technical solution, the secondary SNCR denitrification reducing agent nozzle and the tertiary SCR reducing agent inlet are used to inject reducing agent, and the reducing agent includes urea solution, ammonia water, and ammonia solution.

In the above technical solution, the adsorbent nozzle is used for spraying the adsorbent, and the adsorbent is activated carbon powder.

In the above technical solution, calcium-based desulfurizers are selected as desulfurizers that are added to the main combustion chamber through the primary desulfurizer nozzle and into the secondary combustion chamber through the secondary desulfurizer nozzle, including limestone particles and quicklime particles.

In the above technical solution, the catalyst layer is provided with several layers. Several catalyst layers are filled with catalysts. The catalyst is a honeycomb vanadium-tungsten-titanium catalyst.

In the above technical solution, the low temperature dust collector is a bag filter.

In the above technical solution, the low and low temperature dust collector is a wet electrostatic precipitator.

Compared with the prior art, the present invention has the following advantages and outstanding effects: ① The present invention combines clean combustion CFB technology with flue gas purification technology, which can deeply reduce the emission of PM, SO ₂ , NOx and heavy metals. ② Compared with gas-fired boilers, under the same output conditions, the operating cost is low. ③ Since coal resources are more abundant than natural gas and oil resources, compared with gas and oil-fired boilers with the same emission standards, the coal-fired boiler system of the present invention has stronger applicability.

Description of drawings

Fig. 1 is a schematic diagram of an ultra-gas-clean industrial boiler combustion and flue gas purification system according to one embodiment of the present invention.

In the figure: 1-low NOx combustion device; 101-main combustion chamber; 102-feeding device; 103-first-level desulfurization agent nozzle; 104-secondary desulfurization agent nozzle; 105-second-level SNCR denitrification reducing agent nozzle; Drum; 107-feed water collection pipe; 108-CFB separator; 109-CFB separator outlet flue; 110-burnout chamber; 111-auxiliary combustion chamber; 2-flue gas purification system; Water outlet; 202 - high temperature dust collector; 203 - high temperature flue; 204 - economizer; 205 - water outlet of economizer; 206 - adsorbent nozzle; 207 - three-stage SCR adsorption reactor; 208 - catalyst layer; 209 - air preheater; 210 - low temperature dust collector; 211 - desulfurization absorption liquid feeding device; 212 - desulfurization tower; 213 - low and low temperature dust collector; 214 - feed water inlet of separator water wall; 216-reaction partition wall; 217-separator water wall; 218-deflector; 219-three-stage SCR reducing agent inlet; 3-ash cooler; 31-cooling medium outlet; 32-cooling medium inlet; 33-air lock device; 4-induced fan; 5-chimney.

Detailed ways

The specific embodiment of the present invention and working process will be further described below in conjunction with accompanying drawing.

The orientation terms such as up, down, left, right, front and rear in this application document are established based on the positional relationship shown in the drawings. If the drawings are different, the corresponding positional relationship may also change accordingly, so this should not be understood as limiting the scope of protection.

An ultra-gas-clean coal-fired industrial boiler combustion and flue gas purification system described in the present invention aims to reduce the PM, NOx, SO ₂ and heavy metals in the flue gas of coal-fired industrial boilers through "quadruple ternary combination". The emissions of various pollutants are reduced to below the emission limits of gas-fired boilers. The removal of each pollutant adopts a three-stage series connection or a three-way combination of three methods, namely: 1) The particulate matter PM passes through the three-way series connection method of first-level high-temperature cyclone dust removal + second-level low-temperature dust removal + third-level low-low temperature dust removal; 2) NOx passes through the ternary combination of primary CFB low NOx combustion + secondary SNCR (selective non-catalytic reduction) + tertiary SCR (selective catalytic reduction); 3) SO ₂ passes through primary furnace dry FGD ( Flue gas desulfurization, flue gas desulfurization) + secondary furnace dry FGD + tertiary flue gas wet FGD three-element series method; 4) Hg and other heavy metals are adsorbed by primary adsorbent + secondary FGD removal + tertiary dust removal Triple combination of removal.

As shown in Figure 1, an ultra-gas-clean coal-fired industrial boiler combustion and flue gas purification system includes a low NOx combustion device 1, a flue gas purification system 2, and an induced draft fan 4. Wherein, the low NOx combustion device 1 includes a main combustion chamber 101 , a secondary combustion chamber 111 , a burnout chamber 110 , a CFB (circulating fluidized bed) separator 108 and a feed device 102 arranged at the front end of the main combustion chamber 101 . The main combustion chamber 101 , the secondary combustion chamber 111 , and the burnout chamber 110 are arranged side by side in sequence and horizontally, and form a turn-back logistics channel. The CFB separator 108 is disposed at the outlet of the burnout chamber 110 . CFB separator 108 is preferably a cyclone separator.

The flue gas purification system 2 includes a high-temperature dust collector 202, an economizer 204, a three-stage SCR adsorption reactor 207, an air preheater 209, a low-temperature dust collector 210, a desulfurization tower 212, and a low-temperature dust collector 214, which are connected in sequence through the flue . The CFB separator 108 is connected with the high temperature dust collector 202 through the outlet flue 109 of the CFB separator.

The middle part of the main combustion chamber 101 is provided with a primary desulfurizer nozzle 103, the upper part of the main combustion chamber 101 is provided with a secondary SNCR denitrification reducing agent nozzle 105; the middle and lower part of the secondary combustion chamber 111 is provided with a secondary desulfurizer nozzle 104. Calcium-based desulfurizers are selected as desulfurizers that are fed into the main combustion chamber 101 through the primary desulfurizer nozzle 103 and into the secondary combustion chamber 111 through the secondary desulfurizer nozzle 104, including limestone particles and quicklime particles.

A drum 106 is arranged on the top of the low NOx combustion device 1 . The economizer 204 is provided with an economizer water outlet 205 and an economizer water inlet 215 .

The high temperature dust collector 202 is a water-cooled cyclone dust collector. At this time, the shell of the high-temperature dust collector 202 is surrounded by the water-cooled wall 217 of the separator. The upper part of the high temperature dust collector 202 is provided with a separator water wall hot water outlet 201 , and the lower part is provided with a separator water wall feedwater inlet 214 . The hot water outlet 201 of the water wall of the separator and the water outlet 205 of the economizer are connected to the boiler drum 106 through the feedwater collection pipe 107 .

The lower part of the high-temperature dust collector 202 is provided with an ash cooler 3 for cooling the removed hot ash. Cold ash device 3 selects water cooling or air cooling for use. The ash cooler 3 is provided with a cooling medium outlet 31 and a cooling medium inlet 32 . When the cooling medium is water, the cooling medium inlet 32 is fed with cooling water, and the cooling medium outlet 31 is connected to the separator water wall feedwater inlet 214 and the economizer water inlet 215 through pipes, as shown in FIG. 1 . When the cooling medium is wind, the cooling medium inlet 32 is fed with cold air, and the cooling medium outlet 31 is connected to the air preheater 209 through a pipe. The outlet of the ash cooler 3 is provided with an air locker 33 .

The low temperature dust collector 210 is a bag filter. The low and low temperature dust collector 213 is a wet electrostatic precipitator. The high temperature dust collector 202, the low temperature dust collector 210 and the low and low temperature dust collector 213 together constitute a three-stage deep dust removal.

Taking the flue gas flow direction as the front-to-back direction, the entrance of the three-stage SCR adsorption reactor 207 is provided with a three-stage SCR reducing agent inlet 219 and a deflector 218, and the deflector 218 is arranged at the three-stage SCR reducing agent inlet 219 after. The deflector 218 is used to guide the injected reducing agent. An adsorbent nozzle 206 is arranged in the middle of the three-stage SCR adsorption reactor 207 ; a catalyst layer 208 is also arranged between the deflector 218 and the adsorbent nozzle 206 . As an optimized technical solution, the three-stage SCR adsorption reactor 207 is an inverted U-shaped reactor, and the inverted U-shaped reactor is separated by a reaction partition wall 216 in the middle. The adsorbent nozzle 206 is disposed in the U-shaped top of the three-stage SCR adsorption reactor 207 .

The secondary SNCR denitrification reducing agent nozzle 105 and the tertiary SCR reducing agent inlet 219 are used to inject reducing agent, and the reducing agent is selected from urea solution, ammonia water or ammonia solution. The adsorbent nozzle 206 is used for injecting adsorbent, and the adsorbent is activated carbon powder. The catalyst layer 208 is provided in several layers. Several catalyst layers are filled with catalysts. The catalyst is a honeycomb vanadium-tungsten-titanium catalyst.

The low NOx combustion device 1, the two-stage SNCR and the three-stage SCR constitute a three-stage deep removal of NOx.

The desulfurization tower of the present invention is a wet FGD desulfurization tower, and the upper part of the desulfurization tower 212 is provided with a desulfurization absorption liquid feeding device 211 for spraying alkaline absorption liquid. Those skilled in the art can understand that dry or semi-dry desulfurization towers are also possible utilization schemes.

Low-nitrogen combustion of fuel coal in the low-NOx combustion device 1 first reduces the initial NOx emission concentration, and at the same time, the initial emission concentration of SO ₂ and dust is also greatly reduced under the action of the two-stage desulfurization and CFB separator in the furnace. Then through the temperature reduction, dust removal, desulfurization and denitrification of the high-temperature dust collector 202, the economizer 204, the three-stage SCR adsorption reactor 207, the air preheater 209, the low-temperature dust collector 210, the desulfurization tower 212 and the low-low temperature dust collector 214, to reach Ultra-clean and purified flue gas superior to gas is drawn by induced draft fan 4 and discharged through chimney 5 .

One of the examples:

For a 35t/h lean coal-burning industrial boiler, the ash content in coal is 15% and the sulfur content is 0.6%. When no environmental protection facilities are added, the fly ash content in the flue gas burned by the low NOx combustion device 1 is about 20000mg/m ³ , the SO ₂ emission is about 1500mg/m ³ , and the NOx is about 200mg/m ³ . Due to the comprehensive adoption of the "quadruple ternary combination" method, PM, SO ₂ , NOx, etc. are efficiently removed, and the removal effects of each level are as follows:

Dust removal refers to the removal of particulate matter (PM), and three-stage dust removal is adopted. The fly ash content in the original flue gas is 20000mg/m ³ . The efficiency of the high-temperature dust collector is about 95%, and the PM in the flue gas after high-temperature dust removal is about 1000mg/m ³ ; the dust removal efficiency of the bag filter is greater than 99%, and the particulate matter in the flue gas after the bag filter is less than 10mg/m ³ ;After passing through the wet FGD desulfurization tower, the flue gas will increase the particulate matter due to carrying salts, and finally capture it through wet electrostatic precipitator (capture efficiency is greater than 80%), and the PM emission in the final flue gas is less than 5mg/m ³ .

Desulfurization adopts a combination of two-stage desulfurization in the furnace and flue gas wet FGD. The SO ₂ in the original flue gas is about 1500mg/m ³ , and through the two-stage desulfurization in the furnace, the SO ₂ in the flue gas is reduced to 100mg/m ³ . The efficiency of wet FGD is greater than 90%. After wet FGD, SO ₂ in the flue gas is less than 10mg/m ³ .

Denitrification uses a combination of low NOx combustion, SNCR and SCR. The NOx in the flue gas after low NOx combustion is less than 200 mg/m ³ , the efficiency of SNCR can reach 60%, the efficiency of SCR can reach 80%, and the denitrification efficiency of the combination of SNCR and SCR can reach 92%, so the emission of NOx in the flue gas is 16 mg/m ³ .

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. a kind of coal-burned industrial boiler of super burn gas cleaning burns and flue gas purification system, including low NOx combustion apparatus（1）, cigarette Gas purification system（2）, the low NOx combustion apparatus（1）Including main combustion chamber（101）, subsidiary combustion chamber（111）, secondary furnace（110）、CFB Separator（108）With setting in the main combustion chamber（101）The feeding equipment of front end（102）；It is characterized in that：

The flue gas purification system（2）It include the hot precipitator being sequentially connected by flue（202）, economizer（204）, three-level SCR adsorptive reactors（207）, air preheater（209）, cold precipitator（210）, desulfurizing tower（212）With low cold precipitator （214）；The CFB separators（108）Pass through CFB separator outlet flues（109）With the hot precipitator（202）It is connected；

The main combustion chamber（101）Middle part be provided with first grade desulfurizing agent spout（103）, the main combustion chamber（101）Top setting There is two level SNCR denitration reducing agent spout（105）；The subsidiary combustion chamber（111）Middle and lower part be provided with two-grade desulfurizing agent spout （104）；

Using flue gas flow direction as front-rear direction, the three-level SCR adsorptive reactors（207）Inlet is provided with three-level SCR reducing agents Entrance（219）And deflector（218）, and the deflector（218）It is arranged in the three-level SCR reducing agent entrances（219）Later； In the three-level SCR adsorptive reactors（207）Middle part be provided with adsorbent spout（206）；In the deflector（218）And institute State adsorbent spout（206）Between be additionally provided with catalyst layer（208）.

2. a kind of coal-burned industrial boiler of super burn gas cleaning described in accordance with the claim 1 burns and flue gas purification system, special Sign is：The hot precipitator（202）Select water cooling cyclone dust collectors.

3. according to a kind of coal-burned industrial boiler burning of super burn gas cleaning as claimed in claim 1 or 2 and flue gas purification system, It is characterized in that：The hot precipitator（202）Lower part be provided with device for cooling ash（3）, the device for cooling ash（3）Outlet be provided with lock Gas device（33）；The hot precipitator（202）Shell is by separator water-cooling wall（217）It surrounds；The device for cooling ash（3）Select water cooling Or it is air-cooled.

4. a kind of coal-burned industrial boiler of super burn gas cleaning described in accordance with the claim 1 burns and flue gas purification system, special Sign is：The three-level SCR adsorptive reactors（207）For inverted U-shaped reactor, reaction partition wall is provided among inverted U-shaped reactor （216）It separates；Adsorbent spout（206）It is arranged in the three-level SCR adsorptive reactors（207）U-shaped at the top of in.

5. a kind of coal-burned industrial boiler of super burn gas cleaning described in accordance with the claim 1 burns and flue gas purification system, special Sign is：The desulfurizing tower（212）Top be provided with desulfurization absorbing liquid and feed device（211）, for spraying into alkaline absorption solution.

6. a kind of coal-burned industrial boiler of super burn gas cleaning described in accordance with the claim 1 burns and flue gas purification system, special Sign is：The two level SNCR denitration reducing agent spout（105）With three-level SCR reducing agent entrances（219）For spraying into reducing agent, The reducing agent includes urea liquid, ammonium hydroxide, ammonia solution.

7. a kind of coal-burned industrial boiler of super burn gas cleaning described in accordance with the claim 1 burns and flue gas purification system, special Sign is：The adsorbent spout（206）For spraying into adsorbent, the adsorbent selects active carbon powder.

8. a kind of coal-burned industrial boiler of super burn gas cleaning described in accordance with the claim 1 burns and flue gas purification system, special Sign is：Pass through the first grade desulfurizing agent spout（103）It is added to main combustion chamber（101）, pass through two-grade desulfurizing agent spout（104）Add Enter to subsidiary combustion chamber（111）Interior desulfurizing agent selects calcium-based desulfurizing agent, including limestone particle, quicklime particles.

9. a kind of coal-burned industrial boiler of super burn gas cleaning described in accordance with the claim 1 burns and flue gas purification system, special Sign is：The catalyst layer（208）If dried layer is arranged；The catalyst layer（28）It is filled with catalyst, the catalyst choosing With honeycomb type vanadium tungsten titanium catalyst.

10. a kind of coal-burned industrial boiler of super burn gas cleaning described in accordance with the claim 1 burns and flue gas purification system, special Sign is：The cold precipitator（210）Select bag filter；The low cold precipitator（213）Select wet-esp Device.