CN113559692A - Double-tower double-circulation semi-dry desulfurization device, process and application - Google Patents
Double-tower double-circulation semi-dry desulfurization device, process and application Download PDFInfo
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Abstract
The invention belongs to the technical field of flue gas desulfurization, and particularly provides a double-tower double-circulation semidry desulfurization device, a process and application. The double-tower double-circulation semi-dry desulfurization device comprises a primary semi-dry desulfurization tower and a secondary semi-dry desulfurization tower, wherein the primary semi-dry desulfurization tower and the secondary semi-dry desulfurization tower are connected through a connecting flue, and the primary dry desulfurization tower comprises a flue gas inlet which is used for being communicated with a process flue gas pipeline; the flue gas outlet of the first-stage semi-dry desulfurization tower and the flue gas outlet of the second-stage semi-dry desulfurization tower are connected with a rotary blowing bag-type dust remover, and the bottom of the rotary blowing bag-type dust remover conveys desulfurization ash to the first-stage semi-dry desulfurization tower and the second-stage semi-dry desulfurization tower. Solves the problem that the CFB circulating fluidized bed semidry method flue gas desulfurization process in the prior art can not adapt to the sulfur content of coalHigher working conditions, i.e. original sulfur dioxide concentration over 2000mg/Nm3The operating conditions of (a).
Description
Technical Field
The invention belongs to the technical field of flue gas desulfurization, and particularly provides a double-tower double-circulation semidry desulfurization device, a process and application.
Background
The statements herein merely provide background information related to the present disclosure and may not necessarily constitute prior art.
At present, in order to meet the increasingly severe environmental protection requirements of the country, the CFB circulating fluidized bed semi-dry desulphurization technology is made with unique advantages, combines the advantages of the dry desulphurization technology, such as simple flow, small occupied area, convenient maintenance and repair, and overcomes the defects of wet desulphurization, such as no waste water generation, no need of antiseptic treatment for a chimney, transparent exhaust at the outlet of the chimney, no obvious 'white dragon' phenomenon, and the like; the semi-dry flue gas desulfurization by CFB circulating fluidized bed is a desulfurization technique suitable for national conditions of China, and is not only suitable for SO of large-scale, but also medium-and small-scale industrial boilers2The pollution and smoke dust synchronous treatment is an ideal method.
The CFB circulating fluidized bed semi-dry flue gas desulfurization technology takes calcium hydroxide (or calcium hydroxide digested by calcium oxide) as an absorbent, mainly comprises the following parts: the system comprises a flue system, an absorption tower system, a desulfurization bag-type dust collector system, an absorbent storage and supply system, a material recirculation system, a desulfurization byproduct discharge system, a process water system, a compressed air system, a steam system, an electrical instrument control system and the like.
Boiler flue gas enters the bottom of a desulfurizing tower from an outlet of an air preheater through a flue, the flue gas is fully and rapidly mixed with calcium hydroxide solid particles and products (ash) circulating inside and outside in the desulfurizing tower to react, acid gas in the flue gas is removed, the flue gas after the purification reaction is laterally discharged from the top of an absorption tower, and the flue gas is dedusted by a bag type deduster and then discharged into a chimney through an induced draft fan. The bottom of the absorption tower is provided with a set of water spraying device which sprays quantitative atomized water into the flue gas, so that on one hand, the reaction temperature is optimized, the moisture content of the flue gas is improved, and on the other hand, a liquid film formed on the surface of solid dust particles is favorable for the removal reaction of pollutants, and a higher pollutant removal effect is created. And the process water system also can be used as the overtemperature protection of the bag-type dust remover when the process water system is not desulfurized.
The inventor finds that the efficiency of the CFB circulating fluidized bed semi-dry flue gas desulfurization process is not high, the actual desulfurization efficiency is only 95% and is far lower than that of the wet flue gas desulfurization process under the condition that the calcium-sulfur ratio is generally (1.3-1.5), so the practicability is not high, at the moment, if the desulfurization efficiency is increased, the calcium-sulfur ratio can be only increased by a plurality of times, but the limit efficiency of the semi-dry desulfurization process is 98.25%, namely, the original sulfur dioxide concentration cannot exceed 2000mg/Nm3If the original sulfur dioxide concentration exceeds 2000mg/Nm3The sulfur dioxide concentration can not be stably controlled to be 35mg/Nm only by the semi-dry desulfurization system3As follows, the CFB circulating fluidized bed semidry method flue gas desulfurization process cannot adapt to the working condition of high sulfur content in coal, namely the original sulfur dioxide concentration exceeds 2000mg/Nm3The operating conditions of (1).
Disclosure of Invention
Aiming at the problem that the CFB circulating fluidized bed semidry method flue gas desulfurization process in the prior art can not adapt to the working condition of high sulfur content in coal, namely the original sulfur dioxide concentration exceeds 2000mg/Nm3The operating conditions of (a).
In one or some embodiments of the invention, a double-tower double-circulation semidry desulfurization device is provided, which comprises a first-stage semidry desulfurization tower and a second-stage semidry desulfurization tower, wherein the first-stage semidry desulfurization tower and the second-stage semidry desulfurization tower are connected through a connecting flue, and the first-stage semidry desulfurization tower comprises a flue gas inlet which is used for connecting a process flue gas pipeline;
the flue gas outlet of the first-stage semi-dry desulfurization tower and the flue gas outlet of the second-stage semi-dry desulfurization tower are connected with a rotary blowing bag-type dust remover, and the bottom of the rotary blowing bag-type dust remover conveys desulfurization ash to the first-stage semi-dry desulfurization tower and the second-stage semi-dry desulfurization tower.
In one or some embodiments of the present invention, a double-tower double-circulation semi-dry desulfurization process is provided, wherein the double-tower double-circulation semi-dry desulfurization process is performed in the double-tower double-circulation semi-dry desulfurization device, and comprises the following steps:
and (3) introducing the flue gas of the first-stage semi-dry desulfurization tower and the flue gas of the second-stage semi-dry desulfurization tower into a rotary blowing bag-type dust remover, and returning the unreacted desulfurization ash in the rotary blowing bag-type dust remover to the first-stage semi-dry desulfurization tower and the second-stage semi-dry desulfurization tower for further reaction under the action of first-stage fluidized air and second-stage fluidized air.
In one or more embodiments of the invention, the double-tower double-circulation semidry desulfurization device or the double-tower double-circulation semidry desulfurization process is applied to desulfurization under high working conditions;
the high-working-condition desulfurization, namely the original sulfur dioxide concentration exceeds 2000mg/Nm3。
One or some of the above technical solutions have the following advantages or beneficial effects:
1) the invention discloses a double-tower double-bed layer circulation semidry method desulfurization device, under the working condition that the calcium-sulfur ratio is 1.3-1.5, the flue gas passes through the double-tower double-bed layer circulation semidry method desulfurization device, the desulfurization efficiency of each stage of desulfurization tower is considered according to 95 percent, so the removal rate of pollutants in the flue gas passing through the two stages of desulfurization towers is extremely high and reaches up to 99.75 percent,
2) in the invention, the second-stage semi-dry absorption tower continuously participates in the reaction in the second-stage semi-dry desulfurization tower by using the escaped slaked lime which is not reacted in the first-stage semi-dry absorption tower, the gas-solid contact is strengthened and the reaction surface of the absorbent is continuously updated by the absorbent in the two-stage semi-dry desulfurization tower, the utilization rate of the slaked lime is extremely high, the operation cost is reduced, the device solves the problem that a semi-dry desulfurization system in the industry is not suitable for the working condition of high-sulfur coal desulfurization, and the desulfurization efficiency of the semi-dry method is greatly improved.
3) The method of the invention is not provided with a new device, and can be completed only by combining the devices in the prior art, such as a semi-dry desulfurization tower, a rotary blowing bag-type dust remover and the like, and correspondingly connecting the pipelines, so that the method has the advantages of low process modification cost and high practicability, and is suitable for industrial use.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate embodiments of the disclosure and, together with the description, serve to explain the disclosure and not to limit the disclosure.
FIG. 1 is a schematic view of a process flow of a double-tower double-circulation semi-dry desulfurization process shown in example 1 of the present invention;
FIG. 2 is a flow chart of the operation of a fluidization fan of a fluidization self-balancing ash bucket.
Fig. 3 is a flow chart of the operation of the external circulation return air chute fluidizing fan.
Wherein, 1, slaking lime bin; 2. a first-stage semi-dry desulfurization tower; 3. a second-stage semi-dry desulfurization tower; 4. rotating and blowing a bag-type dust collector; 5. a primary external circulation return air chute; 6. a secondary external circulation return air chute; 7. a first-stage fluidization self-balancing ash bucket; 8. a secondary fluidization self-balancing ash bucket; 9. a high pressure reflux spray gun in the process water system; 10. a slaked lime delivery chute; 11. a fluidization fan of a fluidization self-balancing ash bucket; 12. an external circulation return air chute fluidizing fan; 13. connecting the flue;
Detailed Description
The technical solutions in the embodiments of the present disclosure will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present disclosure, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the disclosure without making any creative effort, shall fall within the protection scope of the disclosure.
Aiming at the problem that the CFB circulating fluidized bed semidry method flue gas desulfurization process in the prior art can not adapt to the working condition of high sulfur content in coal, namely the original sulfur dioxide concentration exceeds 2000mg/Nm3The operating conditions of (a).
In one or some embodiments of the present invention, a double-tower double-circulation semidry desulfurization apparatus is provided, which includes a first-stage semidry desulfurization tower 2 and a second-stage semidry desulfurization tower 3, which are connected by a connecting flue 13, wherein the first-stage semidry desulfurization tower 2 includes a flue gas inlet for connecting a process flue gas pipeline;
the flue gas outlets of the first-stage semi-dry desulfurization tower 2 and the second-stage semi-dry desulfurization tower 3 are connected with a rotary blowing bag-type dust remover 4, and the bottom of the rotary blowing bag-type dust remover 4 conveys desulfurization ash to the first-stage semi-dry desulfurization tower 2 and the second-stage semi-dry desulfurization tower 3.
The double-tower is a two-stage desulfurizing tower, the double circulation is that the unreacted and complete desulfurized ash circulates to the two-stage desulfurizing tower, the double circulation system can enable the unreacted and complete desulfurized ash to be completely reacted, and the desulfurizing efficiency is greatly improved under the condition of not needing high calcium-sulfur ratio.
Furthermore, an air preheater is arranged at the outlet of the process flue gas pipeline, the inlet of the first-stage semi-dry desulfurization tower 2 is connected with the flue at the outlet of the air preheater, the inlet of the second-stage semi-dry desulfurization tower 3 is provided with a homogeneous diversion device, and the outlet of the first-stage semi-dry desulfurization tower 2 is connected with the homogeneous diversion device at the inlet of the second-stage semi-dry desulfurization tower 3.
Further, the outlet of the second-stage semi-dry desulfurization tower 3 is laterally and vertically connected with a rotary blowing bag-type dust remover 4;
preferably, the system also comprises a slaked lime bin 1, wherein the slaked lime bin 1 is a first-stage semi-dry desulfurization tower 2 and is used for conveying slaked lime into the first-stage semi-dry desulfurization tower 2;
preferably, the slaked lime bin 1 conveys slaked lime from the bottom to the first-stage semi-dry desulfurization tower 2.
Preferably, the rotary blowing bag-type dust collectors 4 are two, the second-stage semi-dry desulfurization tower 3 is sequentially connected with a first-stage rotary blowing bag-type dust collector and a second-stage rotary blowing bag-type dust collector, the first-stage rotary blowing bag-type dust collector conveys desulfurization ash to the first-stage semi-dry desulfurization tower 2, and the second-stage rotary blowing bag-type dust collector conveys desulfurization ash to the second-stage semi-dry desulfurization tower 3;
preferably, a circulating return air chute is arranged below the rotary blowing bag-type dust collector 4 and faces the direction of the semi-dry desulfurization tower;
preferably, a fluidization self-balancing ash bucket is arranged below the rotary blowing bag-type dust collector 4;
preferably, one end of the fluidization self-balancing ash hopper is connected with the circulating return air chute, and the other end of the fluidization self-balancing ash hopper is connected with the ash storehouse;
further preferably, the fluidization self-balancing ash bucket is connected with the circulating return air chute and the ash warehouse through an inflator pump.
Specifically, two-stage fluidization self-balancing ash buckets are correspondingly arranged at the bottoms of the two-stage rotary blowing bag-type dust remover, a first-stage fluidization self-balancing ash bucket 7 is connected with a first-stage external circulation return air chute 5 through a first-stage inflator pump, and a second-stage fluidization self-balancing ash bucket 8 is connected with a second-stage external circulation return air chute 6 through a second-stage inflator pump;
specifically, taking the first-stage circulation as an example, the first-stage external circulation return air chute 5 is connected with a cylinder below the venturi section of the first-stage semi-dry desulfurization tower and is used for conveying the circulating desulfurization ash stored in the first-stage fluidization self-balancing ash bucket 7 to the first-stage semi-dry desulfurization tower 2 for reaction; further, the desulfurized ash completely reacted in the first stage is discharged to an ash silo through a first-stage silo pump;
further, as shown in fig. 3, the external circulation return air chutes correspond to the external circulation return air chute fluidization fan 12, the external circulation return air chute fluidization fan 12 includes a two-stage chute fluidization fan, and the one-stage chute fluidization fan is connected with the bottom fluidization groove of the one-stage external circulation return air chute 5 after passing through the one-stage chute steam heater; the second-stage chute fluidizing fan is connected with the bottom fluidizing tank of the second-stage external circulation return air chute 6 after passing through the second-stage chute steam heater; furthermore, a 15kpa roots blower is preferably selected as the chute fluidization blower to provide fluidization air so as to prevent hardening caused by poor fluidity of the circulating desulfurization ash.
Further, as shown in fig. 2, the fluidization self-balancing ash bucket fluidization fan 11 includes a two-stage ash bucket fluidization fan 11. The first-stage ash bucket fluidization fan is connected with the first-stage fluidization self-balancing type ash bucket bottom fluidization groove after passing through the first-stage ash bucket steam heater; the second-stage ash bucket fluidization fan is connected with the second-stage fluidization self-balancing type ash bucket bottom fluidization groove through a second-stage ash bucket steam heater; furthermore, the ash bucket fluidization fan is preferably a 40kpa roots fan and is used for providing fluidization air to prevent the ash bucket wall plate from being too low in temperature to condense out moisture in the desulfurized ash, so that the ash bucket is prevented from caking.
Preferably, the system also comprises a process water system, wherein the process water system is used for spraying water into the first-stage semi-dry desulfurization tower 2;
preferably, the bottom of the first-stage semi-dry desulfurization tower 2 is provided with a high-pressure reflux spray gun, and process water enters the first-stage semi-dry desulfurization tower 2 from the high-pressure reflux spray gun;
preferably, the flue gas inlet of the first-stage semi-dry desulfurization tower 2 is positioned at the bottom of the tower, a Venturi turbulence structure is arranged at the flue gas inlet, a conical section is arranged above the Venturi turbulence structure, and the high-pressure backflow spray gun is arranged at the conical section.
Furthermore, the process water system adopts a high-pressure reflux spray gun, the spray gun is connected with a cone at the upper part of a venturi of the first-stage semi-dry desulfurization tower 2, and the spray gun has the function of reducing the temperature of high-temperature flue gas entering the absorption tower to the optimal temperature with the highest desulfurization efficiency and no corrosion of the absorption tower after spraying water, SO that slaked lime and SO are reduced2The reaction of (2) is a rapid ionic reaction, thereby improving the desulfurization efficiency. Furthermore, the spray gun is connected with a multi-stage centrifugal water pump, and the multi-stage centrifugal water pump is connected with a process water tank.
Preferably, the device also comprises a chimney, wherein a fan is arranged above the rotary blowing bag-type dust remover 4, and purified gas is led out to enter the chimney.
Preferably, the slaked lime bin 1 body is provided with a pulse bag-type dust collector and a safety balance valve to maintain the stability of the pressure in the powder bin;
further, the slaked lime bin 1 is also provided with a radar level indicator and a high level and a low level for detecting the level of the powder bin.
Furthermore, the slaked lime bin 1 adopts a chute feeding mode, the slaked lime feeding chute is connected with a cylinder below a venturi of the first-stage semi-dry desulfurization tower 2, and the second-stage semi-dry desulfurization tower 3 continues to participate in reaction in the second-stage semi-dry desulfurization tower 3 by using the unreacted escaped slaked lime in the first-stage semi-dry desulfurization tower 2, so that the internal circulation rate and the external circulation rate of the slaked lime in the two-stage desulfurization tower are both two times of those of the traditional semi-dry desulfurization tower, the utilization rate of the slaked lime is greatly increased, the molar ratio of calcium to sulfur in the reaction is reduced on the premise of ensuring that the two-stage desulfurization efficiency is 99.75%, and the operation cost is saved; furthermore, the feeding chute is connected with the slaked lime powder bin through a slaked lime adjusting variable-frequency feeding device.
In one or some embodiments of the present invention, a double-tower double-circulation semi-dry desulfurization process is provided, wherein the double-tower double-circulation semi-dry desulfurization process is performed in the double-tower double-circulation semi-dry desulfurization device, and comprises the following steps:
introducing the flue gas of the first-stage semi-dry desulfurization tower 2 and the flue gas of the second-stage semi-dry desulfurization tower 3 into a rotary blowing bag-type dust remover 4, and returning the unreacted desulfurization ash in the rotary blowing bag-type dust remover 4 to the first-stage semi-dry desulfurization tower 2 and the second-stage semi-dry desulfurization tower 3 for further reaction under the action of first-stage and second-stage fluidized air;
preferably, the completely reacted desulfurized ash enters the ash storehouse through a fluidization self-balancing ash bucket.
Preferably, the method further comprises the following water spraying step:
the process water system sprays atomized water into the venturi of the primary absorption tower through the high-pressure reflux spray gun, and is used for reducing the temperature of flue gas in the primary absorption tower;
preferably, the amount of atomized water injected is determined by setting the temperature of the desulfurization tower.
Preferably, the method further comprises the following lime hydrate conveying step: conveying slaked lime from a slaked lime bin 1 to a first-stage semi-dry desulfurization tower 2, and utilizing escaped slaked lime which is not reacted in the first-stage desulfurization tower by a second-stage semi-dry desulfurization tower 3; through the double circulation of the two-stage desulfurizing tower, the absorbent concentration inside the first-stage semi-dry desulfurizing tower 2 and the second-stage semi-dry desulfurizing tower 3 is higher, and the severe friction among circulating ash particles enables the unreacted absorbent covered by the calcium salt hard shell to be exposed again to continue to participate in the reaction.
Specifically, the present invention provides several embodiments,
example 1
A130 t/h circulating fluidized bed boiler of a certain power plant is designed, and the process flow of the double-tower double-bed circulating semi-dry desulfurization device is shown in the figure I.
The specific design basis is as follows;
sulfur content of the coal: less than or equal to 1.6 percent
Original sulfur dioxide concentration: 4000mg/Nm3
Boiler flue gas amount: 250000m3H (working condition)
The invention relates to a double-tower double-bed circulating semidry desulfurization device, which is used for monitoring flue gas SO subjected to desulfurization treatment on line by using CEMS (continuous emission monitoring System)2The emission concentration index is as follows;
when the boiler is in the full load working condition, the SO in the flue gas at the chimney is continuously monitored2The discharge concentration is stable and continuously less than or equal to 35mg/m3SO according to the different bed pressures of the primary and secondary desulfurization towers2The discharge concentration fluctuates between 20 and 30;
working condition primary desulfurization tower bed pressure is 1000Pa, secondary desulfurization tower bed pressure is 1200Pa, SO2The discharge concentration is stable and continuously less than or equal to 30mg/m3The desulfurization efficiency is 99.25%;
the bed pressure of the primary desulfurization tower is 1320Pa, the bed pressure of the secondary desulfurization tower is 1400Pa, and SO is generated under the other working condition2The discharge concentration is stable and continuously less than or equal to 20mg/m3The desulfurization efficiency is 99.50 percent;
under the two working conditions, the consumption of the slaked lime is the same, the consumption of the desulfurizer is about 1.02t (the calculated calcium-sulfur ratio is 1.2), and the utilization rate of the slaked lime is extremely high and is 1.25 times of that of the slaked lime in the common semi-dry process because the calcium-sulfur ratio in the common semi-dry process is generally more than 1.5.
In the embodiment 2, a power plant circulating fluidized bed boiler 260t/h is designed, and the process flow of the double-tower double-bed circulating semi-dry desulfurization device is shown in the figure I.
The specific design basis is as follows;
sulfur content of the coal: less than or equal to 2.0 percent
Original sulfur dioxide concentration: 5000mg/Nm3
Boiler flue gas amount: 498000m3H (working condition)
The invention relates to a double-tower double-bed circulating semidry desulfurization device, which is used for monitoring flue gas SO subjected to desulfurization treatment on line by using CEMS (continuous emission monitoring System)2The emission concentration index is as follows;
when the boiler is in the full load working condition, the SO in the flue gas at the chimney is continuously monitored2The discharge concentration is stable and continuously less than or equal to 30mg/m3SO according to the different bed pressures of the primary and secondary desulfurization towers2The discharge concentration fluctuates between 20 and 30;
working condition primary desulfurization tower bed pressure of 1350Pa, and working condition secondary desulfurization tower bed pressure of 1500Pa, SO2The discharge concentration is stable and continuously less than or equal to 30mg/m3The desulfurization efficiency is 99.40 percent;
the bed pressure of the primary desulfurization tower is 1500Pa, the bed pressure of the secondary desulfurization tower is 1500Pa, and SO is added under the other working condition2The discharge concentration is stable and continuously less than or equal to 20mg/m3The desulfurization efficiency is 99.60 percent;
under the two working conditions, the consumption of the slaked lime is the same, and the consumption of the desulfurizing agent is about 2.75t (the calculated calcium-sulfur ratio is 1.2). The calcium-sulfur ratio of the common semidry method is generally more than 1.5, so the utilization rate of the slaked lime of the invention is extremely high and is 1.25 times of the utilization rate of the common semidry method slaked lime.
It can be seen from examples 1 and 2 that the present invention has good operational flexibility. When the desulfurization efficiency needs to be improved, no equipment needs to be added, and the SO can be controlled by adjusting the pressure drop of the primary semi-dry desulfurization tower and the secondary semi-dry desulfurization tower by adjusting the opening of the electric adjusting valve on the primary return chute and the secondary return chute according to the actual working conditions in operation2The final discharge concentration is that the higher the thickness of the bed layer is, the stronger the adsorption of the dense bed layer particles in the high-density turbulent fluidized bed tower is, the water sprayed in can be quickly evaporated, SO that the slaked lime and the SO are enabled to be discharged2The reaction is a rapid ion reaction, the utilization rate of the absorbent is higher, so that the reaction interface of the absorbent particles continuously rubs and is updated by collision in the absorption tower, and the heat transfer and mass transfer of the desulfurization reaction are greatly enhanced; the desulfurization efficiency is improved, the consumption of the absorbent is reduced, and the pollutants are ensured to stably and continuously reach the standard;
as shown in fig. 1, the present embodiment provides a dual-tower dual-cycle semi-dry desulfurization process, which includes the following steps:
1) the double-circulation desulfurization process comprises the following steps:
and (2) introducing the flue gas into the primary semi-dry desulfurization tower 2, discharging the desulfurized ash containing certain unreacted absorbent from the primary semi-dry desulfurization tower 2 and the secondary semi-dry desulfurization tower 3 by being carried by the airflow from outlets at the tops of the primary semi-dry desulfurization tower 2 and the secondary semi-dry desulfurization tower 3, and performing gas-solid separation by rotating and blowing a bag-type dust collector 4. According to pressure drop signals in the first-stage semi-dry desulfurization tower 2 and the second-stage semi-dry desulfurization tower 3, desulfurization ash in the first-stage ash hopper and the second-stage ash hopper falls to a first-stage inflator pump and a second-stage inflator pump below the ash hoppers, most of the desulfurization ash enters a material return air chute of a first-stage desulfurization ash circulating system and a second-stage desulfurization ash circulating system, and the desulfurization ash entering a first-stage external circulating material return air chute 5 and a second-stage external circulating material return air chute 6 returns to the first-stage absorption tower and the second-stage absorption tower to participate in further chemical reaction under the action of first-stage fluidized air and second-stage fluidized air, so that the retention time of a desulfurizing agent in the absorption tower is prolonged, and the operation cost is reduced;
2) the process water spraying process comprises the following steps:
the process water system is connected with the upper conical section of the venturi of the first-stage semi-dry desulfurization tower 2 through a high-pressure backflow spray gun, sprayed atomized water is used for reducing the temperature of flue gas in the first-stage absorption tower, and SO in the flue gas is enabled to be generated due to reduction of the temperature of the flue gas and increase of the humidity2When the acid gas molecules are easier to condense, adsorb and ionize on the surface of the absorbent, the improvement of the desulfurization efficiency is very beneficial, and the amount of atomized water is determined by setting the temperature of the desulfurization tower.
3) The slaked lime storage and supply process comprises the following steps:
the slaked lime is connected with a venturi lower cylinder of the first-stage semi-dry desulfurization tower 2 through a slaked lime bin 1 feeding conveying chute and is used for providing fresh absorbent into the first-stage semi-dry desulfurization tower 2, and the second-stage semi-dry desulfurization tower 3 only uses the unreacted escaped slaked lime in the first-stage semi-dry desulfurization tower 2; thus, through the double circulation of the two stages of desulfurization towers, the absorbent concentration in the two desulfurization towers is higher, and the severe friction among circulating ash particles causes the unreacted absorbent covered by the calcium salt hard shell to be exposed again to continue to participate in the reaction (surface updating effect). Meanwhile, the continuous supplement of the fresh absorbent and the circulation of a large amount of desulfurized ash are mixed by humidification, so that the absorbent can always maintain higher effective concentration in the desulfurizing tower, and higher absorption efficiency is ensured. The desulfurization efficiency of the two-stage desulfurization tower can reach 99.75 percent;
the steps 1), 2) and 3) are carried out alternately or simultaneously.
Example 2
This example provides a double-tower double-circulation semidry desulfurization process, which is different from example 1 in that in step 1), circulation is not performed, i.e., the incompletely reacted desulfurization ash is not fed into the desulfurization tower again for reaction.
As a result, it was found that: if the unreacted and complete desulfurized fly ash separated by the bag-type dust collector at the rear is not returned to the desulfurizing tower through the return chute, the working condition firstly leads to extremely low desulfurizing efficiency of the desulfurizing tower, namely the desulfurizing tower only keeps internal circulation, slaked lime can only return along the inner wall of the tower in flue gas flow through a reflux device at the upper part of the absorption tower, and the unreacted and complete or escaping slaked lime does not enter the desulfurizing tower again through external circulation to participate in reaction; the bed thickness in the absorption tower is mainly established by a large amount of desulfurized ash captured and separated by a dust remover, and if most of solid particles do not return to the desulfurization tower through the external circulation return chute, the bed in the tower is too weak, the solid-gas ratio is too low, and the high desulfurization efficiency cannot be ensured; secondly, the utilization rate of the slaked lime is extremely low, the calcium-sulfur ratio can be greatly increased, and the later-period operation cost is increased. The internal circulation rate of the desulfurization tower is only 30-50, and the external circulation rate is as high as 150-200, so if the unreacted desulfurization ash is not introduced into the desulfurization tower again for reaction, the consumption of fresh slaked lime is increased sharply only by internal circulation, which is uneconomical. The external circulation is mainly used for establishing compact bed thickness in the desulfurizing tower, enhancing gas-solid contact, leading the absorbent to collide violently in the desulfurizing tower, continuously updating the reaction surface, improving the efficiency and reducing the consumption, thereby achieving two purposes.
Example 3
This example provides a double-tower double-circulation semidry desulfurization process, which is different from example 1 in that in step 1), slaked lime is introduced into both dry desulfurization towers.
As a result, it was found that: if slaked lime is introduced into the two-stage desulfurizing tower, the investment cost is increased, and two sets of slaked lime powder bins, powder bin accessory equipment and two sets of slaked lime chute feeding devices are needed; the method is characterized in that fresh slaked lime is introduced into the first-stage desulfurizing tower only, slaked lime is introduced into the two-stage desulfurizing tower only, the desulfurizing effect is the same, the concentration of original sulfur dioxide is determined, the consumption of slaked lime is a fixed value (fluctuation in a small range is normal), and the first-stage desulfurizing tower and the second-stage desulfurizing tower are connected in series, so that the slaked lime is added twice respectively and added at one time with the slaked lime, the desulfurizing effect and the consumption are not changed, and therefore, in order to save investment cost and the workload of later-stage operation and maintenance, only the slaked lime needs to be introduced into the first-stage desulfurizing tower.
In one or more embodiments of the invention, the double-tower double-circulation semidry desulfurization device or the double-tower double-circulation semidry desulfurization process is applied to desulfurization under high working conditions;
the high-working-condition desulfurization, namely the original sulfur dioxide concentration exceeds 2000mg/Nm3。
The disclosure of the present invention is not limited to the specific embodiments, but rather to the specific embodiments, the disclosure is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. The double-tower double-circulation semi-dry desulfurization device is characterized by comprising a first-stage semi-dry desulfurization tower (2) and a second-stage semi-dry desulfurization tower (3), wherein the first-stage semi-dry desulfurization tower (2) and the second-stage semi-dry desulfurization tower are connected through a connecting flue (13), and the first-stage semi-dry desulfurization tower (2) comprises a flue gas inlet which is used for being communicated with a process flue gas pipeline;
the flue gas outlets of the first-stage semi-dry desulfurization tower (2) and the second-stage semi-dry desulfurization tower (3) are connected with a rotary blowing bag-type dust remover (4), and the bottom of the rotary blowing bag-type dust remover (4) conveys desulfurization ash to the first-stage semi-dry desulfurization tower (2) and the second-stage semi-dry desulfurization tower (3).
2. The double-tower double-circulation semidry desulfurization apparatus according to claim 1, further comprising a slaked lime silo (1), wherein the slaked lime silo (1) is a first-stage semidry desulfurization tower (2) to transfer slaked lime into the first-stage semidry desulfurization tower (2);
preferably, the slaked lime bin (1) conveys slaked lime from the bottom to the first-stage semi-dry desulfurization tower (2).
3. The double-tower double-circulation semidry desulfurization apparatus according to claim 1, wherein there are two rotary blowing bag-type dust collectors (4), the second semidry desulfurization tower (3) is sequentially connected to a first rotary blowing bag-type dust collector and a second rotary blowing bag-type dust collector, the first rotary blowing bag-type dust collector delivers desulfurization ash to the first semidry desulfurization tower (2), and the second rotary blowing bag-type dust collector delivers desulfurization ash to the second semidry desulfurization tower (3);
preferably, a circulating return air chute is arranged below the rotary blowing bag-type dust collector (4) and faces to the direction of the semi-dry desulfurization tower;
preferably, a fluidization self-balancing ash bucket is arranged below the rotary blowing bag-type dust collector (4);
preferably, one end of the fluidization self-balancing ash hopper is connected with the circulating return air chute, and the other end of the fluidization self-balancing ash hopper is connected with the ash storehouse;
further preferably, the fluidization self-balancing ash bucket is connected with the circulating return air chute and the ash warehouse through an inflator pump.
4. The double-tower double-circulation semidry desulfurization apparatus according to claim 1, further comprising a process water system for spraying water into the first-stage semidry desulfurization tower (2);
preferably, the bottom of the first-stage semi-dry desulfurization tower (2) is provided with a high-pressure reflux spray gun, and process water enters the first-stage semi-dry desulfurization tower (2) from the high-pressure reflux spray gun;
preferably, the flue gas inlet of the first-stage semi-dry desulfurization tower (2) is positioned at the bottom of the tower, a Venturi turbulence structure is arranged at the flue gas inlet, a conical section is arranged above the Venturi turbulence structure, and the high-pressure backflow spray gun is arranged at the conical section.
5. The double-tower double-circulation semidry desulfurization apparatus according to claim 1, further comprising a chimney, wherein a fan is provided above the rotary blowing bag-type dust remover (4) to draw the purified gas into the chimney.
6. The double-tower double-circulation semidry desulfurization apparatus according to claim 2, wherein the slaked lime bin (1) body is provided with a pulse bag dust collector and a safety balance valve to maintain the stability of the pressure in the powder bin;
furthermore, the slaked lime bin (1) is also provided with a radar level indicator and a high level and a low level to detect the level of the powder bin.
7. A double-tower double-circulation semi-dry desulfurization process, which is performed in the double-tower double-circulation semi-dry desulfurization apparatus of any one of claims 1 to 6, comprising the steps of:
introducing flue gas of the first-stage semi-dry desulfurization tower (2) and the second-stage semi-dry desulfurization tower (3) into a rotary blowing bag-type dust remover (4), and returning the unreacted desulfurization ash in the rotary blowing bag-type dust remover (4) to the first-stage semi-dry desulfurization tower (2) and the second-stage semi-dry desulfurization tower (3) again for further reaction under the action of first-stage and second-stage fluidized air;
preferably, the completely reacted desulfurized ash enters the ash storehouse through a fluidization self-balancing ash bucket.
8. The double-tower double-circulation semidry desulfurization process of claim 6, further comprising a water spray step:
the process water system sprays atomized water into the venturi of the primary absorption tower through the high-pressure reflux spray gun, and is used for reducing the temperature of flue gas in the primary absorption tower;
preferably, the amount of atomized water injected is determined by setting the temperature of the desulfurization tower.
9. The double-tower double-circulation semidry desulfurization process according to claim 6, further comprising a slaked lime feeding step of: conveying slaked lime from a slaked lime bin (1) to a first-stage semi-dry desulfurization tower (2), and utilizing escaped slaked lime unreacted in the first-stage desulfurization tower by a second-stage semi-dry desulfurization tower (3); through the double circulation of the two stages of desulfurizing towers, the absorbent concentration inside the first-stage semi-dry desulfurizing tower (2) and the second-stage semi-dry desulfurizing tower (3) is higher, and the severe friction among circulating ash particles enables the unreacted absorbent covered by the calcium salt hard shell to be exposed again to continue to participate in the reaction.
10. Use of the double column, double circulation semi-dry desulfurization apparatus of any one of claims 1 to 6 or the double column, double circulation semi-dry desulfurization process of any one of claims 7 to 9 for high-service desulfurization;
the high-working-condition desulfurization, namely the original sulfur dioxide concentration exceeds 2000mg/Nm3。
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| CN114870611A (en) * | 2022-05-26 | 2022-08-09 | 广东佳德环保科技有限公司 | Half-dry desulfurization method for flue gas of lithium salt plant |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114870611A (en) * | 2022-05-26 | 2022-08-09 | 广东佳德环保科技有限公司 | Half-dry desulfurization method for flue gas of lithium salt plant |
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