CN111102596A - System for preventing ammonium bisulfate of boiler air preheater from blocking ash - Google Patents

Abstract

The invention discloses a system for preventing ammonium bisulfate from blocking ash in a boiler air preheater, which adopts the technical scheme that a plurality of isolation plates are arranged in two primary air preheaters and two secondary air preheaters respectively, the heat exchange cavity is divided into a plurality of sub heat exchange cavities arranged side by the isolation plates, the number of first vent pipes is the same as that of the sub heat exchange cavities in the primary air preheaters, the number of second vent pipes is the same as that of the sub heat exchange cavities in the secondary air preheaters, isolation components for blocking gas flow are arranged in the first vent pipes and the second vent pipes respectively, and the isolation components are electrically connected to a control system.

Description

System for preventing ammonium bisulfate of boiler air preheater from blocking ash

Technical Field

The invention relates to a boiler system, in particular to a system for preventing ammonium bisulfate of an air preheater of a boiler from blocking ash.

Background

Along with the stricter and stricter national control on the emission standard of atmospheric pollutants of coal-fired boilers, garbage boilers or biomass boilers, the coal-fired boilers are provided with flue gas denitration devices, the denitration process generally adopts an SNCR selective non-catalytic reduction method or an SCR selective catalytic reduction method, and the denitration agent is generally ammonia water or urea solution. After the boiler operates for a period of time, ash blockage phenomena of different degrees appear at the air preheater, the reason of the ash blockage is that ammonia water or urea solution which is not completely reacted reacts with sulfur trioxide in smoke to generate ammonium bisulfate, the melting point of the ammonium bisulfate is 147 ℃, namely when the smoke temperature is lower than 147 ℃, the ammonium bisulfate can crystallize, and the ammonium bisulfate can also be bonded with fly ash in the crystallization process to cause blockage. The ammonium bisulfate ash blockage can cause the reduction of boiler efficiency, the rise of power consumption of a fan plant, the corrosion of an air preheater, the increase of boiler resistance, the reduction of boiler output and other consequences, so that the loss of economic benefits is realized, and the safety risk is also brought.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a system which has small boiler resistance and is corrosion-resistant and can prevent ammonium bisulfate from blocking ash in an air preheater of a boiler.

In order to achieve the purpose, the invention provides the following technical scheme: a system for preventing ammonium bisulfate of boiler air preheaters from blocking ash comprises a flue gas pipeline, wherein two primary air preheaters and two secondary air preheaters are arranged in the flue gas pipeline, the two primary air preheaters and the two secondary air preheaters are arranged along the length direction of the flue gas pipeline and respectively comprise a heat exchange cavity communicated with the flue gas pipeline, the two secondary air preheaters are positioned between the two primary air preheaters, the two primary air preheaters and the two secondary air preheaters respectively comprise a plurality of mutually independent air channels arranged in an array manner, two ends of the plurality of air channels respectively extend to the pipe wall of the flue gas pipeline and are communicated with the outside, a first vent pipe for communicating the air channels in the two primary air preheaters and a second vent pipe for communicating the air channels in the two secondary air preheaters are arranged on the outer wall of the flue gas pipeline, first breather pipe and second breather pipe all are located flue gas pipeline's homonymy, two all be provided with a plurality of division board, a plurality of in air preheater and two overgrate air preheater the division board divide into the sub heat transfer chamber that a plurality of set up side by side with the heat transfer chamber, the quantity of first breather pipe is the same with the quantity in the sub heat transfer chamber in the air preheater of overgrate air, the quantity in second breather pipe is the same with the quantity in the sub heat transfer chamber in the air preheater of overgrate air, all be provided with in first breather pipe and the second breather pipe and be used for blocking the isolation subassembly of gas flow, the isolation subassembly electricity is connected to control system.

As a further improvement of the invention, an initial temperature measuring part which is in one-to-one correspondence with the sub heat exchange cavities and is used for monitoring the temperature of the flue gas before entering the sub heat exchange cavities is arranged on the primary air preheater close to the inlet of the flue gas pipeline, a final temperature measuring part which is in one-to-one correspondence with the sub heat exchange cavities and is used for monitoring the temperature of the flue gas after entering the sub heat exchange cavities is arranged on the primary air preheater close to the outlet of the flue gas pipeline, and a temperature measuring part for monitoring the temperature of the air after heat exchange is arranged at the port of the air channels for gas outflow.

As a further improvement of the present invention, the number of the sub heat exchange cavities in the primary air preheater and the secondary air preheater is the same, the first vent pipes and the second vent pipes are in one-to-one correspondence and are located in the same plane, the first vent pipes located in the same plane surround the second vent pipes, the isolation assemblies in the first vent pipes and the isolation assemblies in the second vent pipes located in the same plane are both connected to the output shaft of the same driving motor, and the driving motor is externally connected to a control system.

As a further improvement of the invention, the first vent pipe and the second vent pipe which are positioned in the same plane are integrally formed, and the cavities of the first vent pipe and the second vent pipe are not communicated.

The invention has the beneficial effects that: the interior of the existing air preheater is divided into a plurality of independent sub heat exchange cavities through partition plates, the plurality of sub heat exchange cavities are not interfered with each other, a plurality of air channels are divided into different sub heat exchange cavities, the partition components are controlled one by one through a boiler DCS system to enable air in corresponding first vent pipes and second vent pipes to be incapable of circulating, no air flows in corresponding air channels, smoke in the sub heat exchange cavities where the air channels are located cannot be cooled to rise in temperature, the air channels are in a dry combustion state, ammonium bisulfate crystals are sublimated and discharged along with the flow of the smoke, the temperature of the smoke flowing through the primary air preheater and the secondary air preheater is small in overall change, the temperature of the discharged smoke is within an allowable value range, and the safety is high; such design is compared and needs regularly to unpack apart boiler system among the current and carry out the maintenance work of detaching ammonium bisulfate and can be simplified and maintain the operation, and maintains the work in boiler system work, and is easy and simple to handle, and maintenance work is automatic and intelligent, has not only solved the problem that ammonium bisulfate blockked up, has improved boiler system's availability factor moreover.

Drawings

FIG. 1 is a front cross-sectional view of the present invention as installed in a boiler system;

FIG. 2 is an enlarged view at B in FIG. 1;

figure 3 is a perspective view of the present invention shown removed from the flue gas duct.

Reference numerals: 1. a flue gas duct; 2. a heat exchange cavity; 3. a primary air preheater; 4. a secondary air preheater; 5. a first vent pipe; 6. a second vent pipe; 7. an air duct; 8. an isolation component; 9. an initial temperature measurement part; 10. a final temperature measurement part; 11. considering a temperature measuring part; 12. a drive motor; 13. a separator plate; 14. and the sub heat exchange cavity.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. In which like parts are designated by like reference numerals.

Referring to fig. 1 to 3, the system for preventing ammonium bisulfate from blocking ash in a boiler air preheater of the present embodiment includes a flue gas duct 1, two primary air preheaters 3 and two secondary air preheaters 4 are disposed in the flue gas duct 1, the two primary air preheaters 3 and the two secondary air preheaters 4 are both disposed along the length direction of the flue gas duct 1 and both include heat exchange cavities 2 communicated with the flue gas duct 1, the two secondary air preheaters 4 are both located between the two primary air preheaters 3, the two primary air preheaters 3 and the two secondary air preheaters 4 both include a plurality of air channels 7 which are independent from each other and arranged in an array, the air channels 7 are ducts for flowing outside air, both ends of the plurality of air channels 7 extend to the wall of the flue gas duct 1 and communicate with the outside, that is, both ends of the plurality of air channels 7 extend to the wall of the sub heat exchange cavities 14, the pipe wall of the flue gas pipeline 1 is provided with a through hole, the shell wall of the primary air preheater 3 or the secondary air preheater 4 is attached to the inner wall of the flue gas pipeline 1, the through hole is communicated with the air duct 7, or the shell wall of the primary air preheater 3 or the secondary air preheater 4 is externally connected with a pipeline communicated with the air duct 7, and the pipeline can penetrate through the through hole and extend out of the flue gas pipeline 1; the outer wall of the flue gas pipeline 1 is provided with a first vent pipe 5 for communicating air channels 7 in two primary air preheaters 3 and a second vent pipe 6 for communicating air channels 7 in two secondary air preheaters 4, the first vent pipe 5 and the second vent pipe 6 are both positioned at the same side of the flue gas pipeline 1, the first vent pipe 5 and the second vent pipe 6 are independent, the first vent pipe 5 and the second vent pipe 6 can be connected on the outer wall of the flue gas pipeline 1 in a welding way, the two primary air preheaters 3 and the two secondary air preheaters 4 are divided into two groups, each group comprises one primary air preheater 3 and one secondary air preheater 4, the primary air preheater 3 and the secondary air preheater 4 are connected together, and a plurality of air channels 7 are spaced at a certain distance so that flue gas can flow through the air preheaters, because the air flows into the other group of the primary air preheater 3 and the secondary air preheater 4 from the group of the primary air preheater 3 and the secondary air preheater 4, the air temperature rises and is higher, namely the first vent pipe 5 and the second vent pipe 6 are made of iron pipe materials instead of rubber pipes or plastic pipes, which is the structure of the existing middle boiler system;

the improvement is carried out on the basis of the prior art, a plurality of partition boards 13 are arranged in the two primary air preheaters 3 and the two secondary air preheaters 4, the partition boards 13 are required to meet the properties of corrosion resistance and high temperature resistance, namely, the partition boards 13 can be made of steel plates and the like, the heat exchange cavity 2 is divided into a plurality of sub heat exchange cavities 14 which are arranged side by the plurality of partition boards 13, a plurality of air channels 7 in the two primary air preheaters 3 and the two secondary air preheaters 4 are divided into a plurality of sub heat exchange cavities 14, in order to ensure that the effect generated by each sub heat exchange cavity 14 in the subsequent operation is consistent, the plurality of air channels 7 are equally divided, the number of the first vent pipes 5 is the same as that of the sub heat exchange cavities 14 in the primary air preheaters 3, the number of the second vent pipes 6 is the same as that of the sub heat exchange cavities 14 in the secondary air preheaters 3, and the number of the air channels 7, if the number of the air channels 7 in each sub-heat exchange cavity 14 is one, the first vent pipe 5 and the second vent pipe 6 are correspondingly communicated with the air channels 7, if the number of the air channels 7 in each sub-heat exchange cavity 14 is more than one, the inner diameters of the pipe orifices of the first vent pipe 5 and the second vent pipe 6 are made large so as to ensure that the ports of the air channels 7 can be enclosed when the pipe orifices of the first vent pipe 5 and the second vent pipe 6 are connected to the side wall of the flue gas pipeline 1, namely, one first vent pipe 5 or one second vent pipe 6 can be simultaneously communicated with the air channels 7, the first vent pipe 5 and the second vent pipe 6 are internally provided with an isolation assembly 8 for blocking gas flow, the isolation assembly 8 is electrically connected to a control system, the control system is the existing technology for controlling the whole system of the boiler, namely, the boiler DCS control system, the isolation assembly 8 can be an electromagnetic valve, cutting off a section of the first vent pipe 5 from the middle, placing the electromagnetic valve at the position where the first vent pipe 5 is cut off, connecting two cut ends to the electromagnetic valve and sealing, driving the electromagnetic valve through a control system to realize whether the first vent pipe 5 cut into two sections is communicated or not, and arranging an isolation component 8 on the second vent pipe 6 like the first vent pipe 5; the isolation component 8 can also be a ring body hinged with a baffle, the first vent pipe 5 or the second vent pipe 6 is cut into two sections, the two sections of cuts are respectively connected to two surfaces of the ring body, and sealing treatment is carried out;

further optimization, specifically referring to fig. 3, in order to avoid the phenomenon that the circuits between the first vent pipe 5 and the second vent pipe 6 are staggered and complicated, the number of the isolation plates 13 in the primary air preheater 3 and the secondary air preheater 4 is the same, i.e. the number of the sub heat exchange cavities 14 in the primary air preheater 3 and the secondary air preheater 4 is the same, and the sub heat exchange cavities are communicated one by one, the number of the first vent pipe 5 is the same as the number of the second vent pipe 6, the plurality of first vent pipes 5 and the plurality of second vent pipes 6 are arranged in one-to-one correspondence and are positioned in the same plane, the first vent pipes 5 positioned in the same plane surround the second vent pipes 6, the first vent pipes 5 and the second vent pipes 6 are positioned in the same vertical plane, and the design can make the lengths of the second vent pipes 6 and the first vent pipes 5 shortest, the occupied space is small, the baffle in the first vent pipe 5 and the baffle in the second vent pipe 6 which are positioned in the same vertical plane are both connected to the output shaft of the same driving motor 12, the driving motor 12 can drive the output shaft to rotate, so that one driving motor 12 can simultaneously control the rotation of the baffles in the first vent pipe 5 and the second vent pipe 6, and the driving motor 12 is externally connected with a control system;

further optimization, specifically referring to fig. 2, an initial temperature measuring part 9 corresponding to a plurality of sub heat exchange cavities 14 one by one and used for monitoring the temperature of the flue gas before entering the sub heat exchange cavities 14 is arranged on the primary air preheater 3 close to the inlet of the flue gas pipeline 1, a final temperature measuring part 10 corresponding to the plurality of sub heat exchange cavities 14 one by one and used for monitoring the temperature of the flue gas after entering the sub heat exchange cavities 14 is arranged on the primary air preheater 3 close to the outlet of the flue gas pipeline 1, a consideration temperature measuring part 11 used for monitoring the temperature of the air after heat exchange is arranged at the port of a plurality of air channels 7 for gas outflow, if only one air channel 7 is arranged in each sub heat exchange cavity 14, each air channel 7 is provided with the consideration temperature measuring part 11, if a plurality of air channels 7 are arranged in each sub heat exchange cavity 14, a plurality of through pipes corresponding to the sub heat exchange cavities 14 one by one are arranged on the outer wall, the through pipe can be communicated with a plurality of air channels 7 at the same time, a temperature measuring part 11 is arranged on the through pipe, the temperature measuring part 11 can measure the temperature of mixed gas discharged by the air channels 7, under the normal operation of a boiler system, the initial temperature measuring part 9, the final temperature measuring part 10 and the temperature measuring part 11 are respectively provided with a design value for reference and an allowable value for ensuring the normal operation, in order to control the production cost, the initial temperature measuring part 9, the final temperature measuring part 10 and the temperature measuring part 11 can be thermometers, the thermometers can be positioned on the outer wall of the flue gas pipeline 1, and one ends of the thermometers for measuring the temperature extend into the corresponding pipes so as to be in contact with the gas; if the initial temperature measuring part 9, the final temperature measuring part 10 and the temperature measuring part 11 to be considered can adopt the existing temperature sensors for convenient installation and production, the probes for measuring the temperature of the temperature sensors are arranged at the corresponding positions and can be fully contacted with the gas, and the processing system connected with the probes is electrically connected with the control system, namely the temperature information measured by the temperature sensors can be fed back to the control system, so that a user can observe and monitor the temperature information;

for convenience of description, specifically referring to fig. 3, the primary air preheater 3 and the secondary air preheater 4 are designed to be the same, and the air duct 7 in the sub heat exchange cavity 14 is one, during the use of the boiler system, the flue gas duct 1 is disposed perpendicular to the bottom surface, the flow direction of the flue gas in the flue gas duct 1 is from top to bottom, the upper port of the flue gas duct 1 is a flue gas inlet, the initial temperature measuring member 9 is disposed near the flue gas inlet, the lower port is a flue gas outlet, the final temperature measuring member 10 is disposed near the flue gas outlet, the primary air preheater 3 and the secondary air preheater 4 near the flue gas outlet are both externally connected with blowers, at this time, the control system controls all driving motors 12 to operate, so that the isolation assembly 8 rotates to a state where all the first vent pipes 5 and the second vent pipes 6 can allow the gas to circulate, and blows the externally connected gas into the primary air preheater 3 and the secondary air preheater 4, the gas flows into the primary air preheater 3 and the secondary air preheater 4 close to the smoke inlet from bottom to top along the first vent pipe 5 and the second vent pipe 6 relative to the ground, the air flows from bottom to top and is convenient for cooling the smoke for a plurality of times compared with the air flows from top to bottom, the cooling effect is good, the public common knowledge of the existing boiler system shows that ammonium bisulfate is in a solid state below 147 ℃, ammonium bisulfate is in a liquid state at 147-207 ℃, ammonium bisulfate is in a gaseous state above 207 ℃, the temperature of the smoke is lower than 147 ℃ after the smoke is cooled, the ammonium bisulfate in the smoke starts to crystallize and adheres to the pipe wall of the air channel 7, the cavity wall of the sub heat exchange cavity 14 and the isolation plate 13, the gap between the air channel 7 and the isolation plate 13 is reduced along with the accumulation of ammonium bisulfate crystals, the flow of the smoke is unsmooth, and even the air channel 7 and the isolation plate 13 are in a closed state, therefore, the flue gas can not flow through the primary air preheater 3 and the secondary air preheater 4, the flue gas in the flue gas pipeline 1 can not circulate, in order to avoid the precipitation of ammonium bisulfate crystals, according to a certain sequence, an instruction is input to the control system, the control system controls one of the driving motors 12 to operate, the driving motor 12 drives the isolation component 8 to rotate, the interiors of the first vent pipe 5 and the second vent pipe 6 corresponding to the driving motor 12 are blocked, the air can not circulate, the rest of the isolation components 8 are kept still, the air in the four air channels 7 corresponding to the first vent pipe 5 and the second vent pipe 6 stops flowing, the four air channels 7 without air flowing are not regarded as a group, the flue gas flowing through the air channels 7 can not be cooled, the temperature in the corresponding sub heat exchange cavity 14 rises, when the readings of the initial temperature measuring component 9 and the final temperature measuring component 10 are basically consistent, the air duct 7 is in a dry-burning state, the flue gas is kept at a temperature above 207 ℃, the smoke ventilation time is kept for 20 to 30 minutes, ammonium bisulfate crystals on the outer wall of the air duct 7, the cavity wall of the corresponding sub heat exchange cavity 14 and the partition plate 13 are sublimated, the sublimated ammonium bisulfate is discharged to the outside from a smoke outlet together with the flue gas, the adjacent sub heat exchange cavities 14 cannot be influenced by the temperature in the sub heat exchange cavities 14 under the action of the partition plate 13, the smoke ventilation time can be adjusted according to the actual temperature of the flue gas, until the air duct 7 is dried and sintered, the driving motor 12 corresponding to the air duct 7 is controlled to reset by inputting an instruction to a control system, the driving motor 12 drives the partition component 8 connected with the driving motor to reset, the first ventilation pipe 5 and the second ventilation pipe 6 corresponding to the air duct 7 are in a smooth state, the air blower can blow air into the air duct 7 and keep the air circulation, after the temperature is stabilized for 10 minutes, observing the reading of the final temperature measuring piece 10, if the reading of the final temperature measuring piece 10 reaches or approaches the design value and the reading of the temperature measuring piece 11 is increased or approaches the design value, the dry burning is considered to be finished, otherwise, the isolation component 8 needs to be controlled again to prevent the air in the group of air channels 7 from flowing again, and the dry burning time is prolonged; after a group of air ducts 7 are dried, other driving motors 12 are controlled one by one to drive corresponding isolation components 8 by repeating the steps, the interiors of corresponding first vent pipes 5 and corresponding second vent pipes 6 are blocked, so that the corresponding air ducts 7 are dried, only one group of air ducts 7 can be dried in each drying process, and meanwhile, the readings of an initial temperature measuring part 9, a final temperature measuring part 10 and a temperature measuring part 11 to be considered cannot exceed corresponding allowable values;

such design is compared and is needed regularly to unpack apart boiler system among the current and carry out the maintenance work of detaching ammonium bisulfate and can simplify the maintenance operation, and maintain the work in the work of boiler system, and easy and simple to handle, it is automatic and intelligent to maintain the work, the problem of ammonium bisulfate jam has been solved, and boiler system's availability factor has been improved, and the flue gas temperature after primary air heater 3 and overgrate air heater 4 of flowing through generally changes for a short time, the exhaust flue gas temperature is in the within range of permissible value, the security is high.

Further optimize, can be with the first breather pipe 5 and the second breather pipe 6 integrated into one piece that lie in the coplanar, have two sections through-holes in a pipe promptly, and two sections through-holes do not communicate with each other, compare like this design with the design that first breather pipe 5 and second breather pipe 6 both independent settings respectively on the installation tend to simplify, more stable on structural strength, not fragile.

The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.

Claims (4)

1. A system for preventing ammonium bisulfate of a boiler air preheater from blocking ash comprises a flue gas pipeline (1), wherein two primary air preheaters (3) and two secondary air preheaters (4) are arranged in the flue gas pipeline (1), the primary air preheaters (3) and the two secondary air preheaters (4) are arranged along the length direction of the flue gas pipeline (1) and respectively comprise a heat exchange cavity (2) communicated with the flue gas pipeline (1), the two secondary air preheaters (4) are positioned between the two primary air preheaters (3), the two primary air preheaters (3) and the two secondary air preheaters (4) respectively comprise a plurality of air channels (7) which are mutually independent and are arranged in an array manner, two ends of the plurality of air channels (7) extend to the pipe wall of the flue gas pipeline (1) and are communicated with the outside, be provided with on the outer wall of flue gas pipeline (1) and be used for first breather pipe (5) that are linked together wind channel (7) in two air preheater (3) and be used for second breather pipe (6) that are linked together wind channel (7) in two overgrate air preheater (4), first breather pipe (5) and second breather pipe (6) all are located the homonymy of flue gas pipeline (1), its characterized in that: two all be provided with a plurality of division board (13), a plurality of in air preheater (3) and two overgrate air preheater (4) division board (13) divide into sub heat transfer chamber (14) that a plurality of set up side by side with heat transfer chamber (2), the quantity of first breather pipe (5) is the same with the quantity of sub heat transfer chamber (14) in air preheater (3), the quantity of second breather pipe (6) is the same with the quantity of sub heat transfer chamber (14) in overgrate air preheater (3), all be provided with in first breather pipe (5) and second breather pipe (6) and be used for blocking the isolation subassembly (8) that gaseous flow, isolation subassembly (8) electricity is connected to control system.

2. The system for preventing ammonium bisulfate from blocking ash in an air preheater of a boiler as set forth in claim 1, wherein: be close to flue gas pipeline (1) entry be provided with on air preheater (3) with a plurality of sub heat transfer chamber (14) one-to-one and be used for monitoring the initial temperature measurement spare (9) of the temperature before the flue gas gets into sub heat transfer chamber (14), be close to flue gas pipeline (1) export be provided with on air preheater (3) with a plurality of sub heat transfer chamber (14) one-to-one and be used for monitoring terminal temperature measurement spare (10) of the temperature after the flue gas gets into sub heat transfer chamber (14), be provided with in a plurality of wind channel (7) port department that is used for gaseous outflow and be used for monitoring the temperature of air after the heat transfer consider temperature measurement spare (11).

3. The system for preventing ammonium bisulfate from blocking ash in an air preheater of a boiler as set forth in claim 1 or 2, wherein: the quantity of division board (13) in primary air heater (3) and overgrate air heater (4) these two is the same and the one-to-one sets up, a plurality of first breather pipe (5) and a plurality of second breather pipe (6) one-to-one and be in the coplanar, and first breather pipe (5) that are located the coplanar enclose outside second breather pipe (6), are located the coplanar on isolation subassembly (8) in first breather pipe (5) and isolation subassembly (8) in second breather pipe (6) all are connected to the output shaft of same driving motor (12), driving motor (12) external control system.

4. The system for preventing ammonium bisulfate from blocking ash in an air preheater of a boiler as set forth in claim 3, wherein: the first vent pipe (5) and the second vent pipe (6) which are positioned in the same plane are integrally formed, and cavities of the first vent pipe and the second vent pipe are not communicated.

Images