Online construction method of urea prilling tower overhead bag type dust recovery device

Abstract

The application discloses an online construction method of a bag-type dust recovery device at the top of a urea prilling tower, and comprises the following steps: ground prefabrication, civil construction, truss and cleaning chamber hoisting and installation, recovery system pipeline laying, removal of louvers and water receiving disc manufacturing, ammonia removal atomization pipeline laying, power line laying, fan installation and debugging, filter bag installation and finishing work, according to the drawing requirements, the truss is spliced on the ground, after the truss is assembled, the assembly of the cleaning chamber is completed, and the cleaning chamber is assembled according to the drawing requirements and the component number at the bottom of the urea prilling tower. The application realizes the online construction of the bag-type dust recovery device at the top of the urea prilling tower, in the construction process, in most cases, the urea prilling tower does not need to stop working to install the bag-type dust recovery device under the condition of ensuring construction safety, so that the production efficiency of the urea prilling tower for urea can be greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of online construction of a dust recovery device, in particular to an online construction method of a bag-type dust recovery device at the top of a urea prilling tower. BACKGROUND

[0002] China is the world's largest urea producer and user, with an annual urea production capacity of 770 million tons, accounting for 40% of the world's total production capacity, and an annual urea output of about 620 million tons, accounting for 1 / 3 of the world's total output. The urea prilling tower is one of the most important equipment for producing urea, and is the key equipment for producing granular products from molten urea. The urea prilling tower using natural ventilation is generally a high and large concrete structure in cylindrical or rectangular shape, which has the advantages of stable operation, convenient management and low operation cost, but has the disadvantage of being greatly affected by environmental conditions.

[0003] A large amount of dust is generated during the production of urea in the urea prilling tower, which will cause serious environmental pollution if not treated in time. Therefore, a dust recovery device needs to be installed at the top of the urea prilling tower. However, in most cases, the installation of the existing dust recovery device needs to be carried out under the premise that the urea prilling tower stops working, which will affect the production of urea in the urea prilling tower and thus affect the production efficiency of urea. Therefore, an online construction method of a bag-type dust recovery device at the top of a urea prilling tower is needed to solve the above technical problems. SUMMARY

[0004] The present application aims to provide an online construction method of a bag-type dust recovery device at the top of a urea prilling tower to solve the problems raised in the background.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] An online construction method of a bag-type dust recovery device at the top of a urea prilling tower, comprising the following steps:

[0007] S1: Ground preparation

[0008] According to the drawing requirements, the truss is spliced on the ground, and after the truss is assembled, the assembly of the cleaning chamber is completed. The cleaning chamber is assembled according to the drawing requirements and the component number at the bottom of the urea prilling tower, and the welding at the joint needs to meet the technical requirements and adjust the flatness of the components according to the requirements;

[0009] S2: Civil engineering construction

[0010] Cutting the top of the urea prilling tower to ensure the ventilation and filtration area, cutting the parapet opening of the top of the urea prilling tower, drilling the truss anchor bolt hole at the corresponding position of the opening, ground water washing recovery tank and water washing circulating pump infrastructure, cutting the surface and equipment foundation for corrosion prevention treatment;

[0011] S3: truss and cleaning room hoisting and installation

[0012] Before hoisting, the prilling needs to be stopped, the water pan splicing is hoisted into the specified position with prefabricated steel plates, and the other time is normal production prilling, and welding personnel are organized to reinforce the hoisted components and complete the welding work of each connection part. At the same time, the box plate attached to the steel structure is hoisted and welded and reinforced. After the truss is in place, it is fixed with the urea prilling tower bearing wall by chemical bolts. After the truss is installed and fixed, the four zone cleaning rooms are hoisted. The hoisting and welding of the truss and the cleaning room are carried out under the normal production of the urea prilling tower. The bottom end of the box plate is temporarily not welded to ensure that the urea prilling tower has sufficient air flow during the installation of the filter bag;

[0013] S4: Recovery system pipeline laying

[0014] The installation of the recovery system, pipeline laying, valve installation and S3 are carried out at the same time, and the preformed port work of the related pipeline connection is completed;

[0015] S5: Remove the louver and make the water pan

[0016] After the louver is removed, the scaffolding is completely removed, and then the water pan is spliced and made. This process needs to be carried out under the condition of stopping prilling;

[0017] S6: Ammonia abatement atomization pipeline laying

[0018] The installation of the ammonia abatement pipeline needs to stop prilling, which is completed in 3-4 times. While the ammonia abatement pipeline is under construction, the monitoring personnel color the water pan for leakage test;

[0019] S7: Electric power line laying

[0020] The cable bridge welding and cable laying work are carried out at the same time as S6 construction content, and the wiring work of PLC control cabinet and electromagnetic valve can be carried out after the cleaning room hoisting and fixing are completed in S3;

[0021] S8: Fan installation and debugging

[0022] After the louver is removed, the water pan is made, and the ammonia abatement pipeline is laid, the fan is hoisted and installed. After the fan is installed in place, the wiring is completed, and the fan debugging can be carried out;

[0023] S9: Filter bag installation

[0024] After the completion of the fan debugging, the filter bag, keel and spray pipe are installed, the whole filter bag installation process needs to stop the granulation, which can be divided into three times:

[0025] ①First, install the filter bag and keel of the first and second areas, after the installation of the filter bags of the two areas, start the two area fans to ensure the normal ventilation of the urea prilling tower, and start to resume the prilling. Because the urea solution tank liquid level is high after stopping prilling, it needs time to lower the liquid level, and the installation of the first and second area spray pipes and the clean room manhole sealing strip is carried out during this period;

[0026] ②After the urea solution tank is lowered to the low liquid level, stop the prilling and install the third area filter bag, keel and spray pipe, after the installation of all parts, start the third area fan;

[0027] ③After the first two times of filter bag, keel and spray pipe construction, 3 / 4 of the whole air outlet area has been installed with filter components, and reaches the normal operation state, the fourth area filter components can be installed under normal prilling conditions, after the installation of the filter bag, start all the fans and put into use the dust removal system, which can enter the trial operation stage;

[0028] S10: finishing work

[0029] The finishing work is the welding of the bottom box plate, the debugging of the dust removal system and the debugging of the recovery system, which can be carried out in the trial operation stage. The welding of the box needs to stop the prilling and stop the fan to prevent the formation of negative pressure in the clean gas chamber, which can suck the welding slag into the interior and ignite the filter bag.

[0030] As a further scheme of the present application: in S1, according to the load of the crane, the clean room accessories are assembled, including: gas collector, flow collector and guardrail.

[0031] As a further scheme of the present application: in S2, before the civil construction, a scaffold is erected in the inner circle of the urea prilling tower air outlet to support the falling concrete during the construction process. The scaffold erection stops the prilling until the scaffold erection is completed, and the remaining time is normal production prilling.

[0032] As a further scheme of the present application: in S5, the splicing of the water receiving disc is completed in 7-8 times, and each time interval ensures the normal production prilling of the urea prilling machine, ensures the stable operation of the urea prilling machine, and the construction party can interleave with other construction contents, but it is necessary to avoid simultaneous operation with the clean room or steel structure welding work to prevent cross operation causing personnel injury.

[0033] As a further scheme of the present application: in S9, the filter bag must be installed in the whole area each time, and the granulation cannot be started if the installation is not completed in the whole area, otherwise the inner surface of the filter bag in the area will be contaminated by dust, resulting in that the exhaust analysis after the trial operation is not up to standard.

[0034] Compared with the prior art, the present application has the following beneficial effects:

[0035] The present application realizes the online construction of the urea prilling tower top bag type dust recovery device by ground prefabrication, civil construction, truss and cleaning room hoisting installation, pipeline laying of the recovery system, removal of the louver and water pan manufacturing, ammonia removal atomization pipeline laying, power line laying, fan installation and debugging, filter bag installation and finishing work, so that in most cases during the construction process, the urea prilling tower does not need to stop working to install the bag type dust recovery device under the condition of ensuring construction safety, which greatly improves the production efficiency of the urea prilling tower for urea, and is beneficial to the production and prilling of urea. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 Flow chart of the online construction method of the urea prilling tower top bag type dust recovery device. DETAILED DESCRIPTION

[0037] Various exemplary embodiments, features, and aspects of the present application will be described in detail below with reference to the accompanying drawings. The same reference numerals in the drawings denote elements having the same or similar functions. Although various aspects of the embodiments are illustrated in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

[0038] The word "exemplary" is used herein in the sense of being an example, rather than a preference or requirement. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0039] In addition, in order to better illustrate the present application, numerous specific details are given in the specific embodiments below. Those skilled in the art should understand that the present application can also be implemented without some specific details. In some examples, methods, means, elements well known to those skilled in the art are not described in detail, in order to highlight the main idea of the present application.

[0040] Embodiment one

[0041] Please refer to Figure 1 An online construction method of a urea prilling tower top bag type dust recovery device, comprising the following steps:

[0042] S1: ground prefabrication

[0043] According to the drawing requirements, the truss is spliced on the ground, and after the truss is assembled, the assembly of the cleaning chamber is completed. The cleaning chamber is assembled according to the drawing requirements and the component number at the bottom of the urea prilling tower. The welding of the spliced joint needs to meet the technical requirements, and the flatness of the components needs to be adjusted according to the requirements;

[0044] S2: civil construction

[0045] Cut the expanded urea prilling tower top air outlet to ensure the ventilation and filtration area. Cut the parapet opening at the top of the urea prilling tower and drill truss anchor bolt holes at the corresponding position. The ground water recovery tank and water washing circulating pump foundation are constructed. The cutting surface and equipment foundation are leveled and anticorrosion treated;

[0046] S3: truss and cleaning chamber hoisting and installation

[0047] Before hoisting, the prilling needs to be stopped, the precast steel plate for splicing the water receiving tray is hoisted into the specified position, and the normal production prilling is carried out at other times. Welding personnel are organized to reinforce the hoisted components and complete the welding work of each connection part. At the same time, the box plate attached to the steel structure is hoisted and welded and reinforced. After the truss is in place, it is fixed to the urea prilling tower bearing wall with chemical bolts. After the truss is installed and fixed, the four zone cleaning chambers are hoisted. The hoisting and welding of the truss and the cleaning chamber are carried out under the normal production condition of the urea prilling tower. The bottom end of the box plate is temporarily not welded to ensure sufficient air flow in the urea prilling tower during the installation of the filter bag;

[0048] S4: recovery system pipeline laying

[0049] The installation of the recovery system, pipeline laying, valve installation and S3 are carried out at the same time. The reserved port work of related pipeline connection is completed;

[0050] S5: remove the louver and make the water receiving tray

[0051] After the louver is removed, the scaffolding is completely removed, and then the water receiving tray is spliced and made. This process needs to be carried out under the condition of stopping prilling;

[0052] S6: ammonia abatement atomization pipeline laying

[0053] The installation of the ammonia abatement pipeline needs to stop prilling and is completed in 3-4 times. While the ammonia abatement pipeline is constructed, the monitoring personnel color the water receiving tray for leakage test;

[0054] S7: power line laying

[0055] The cable bridge welding and cable laying work are carried out at the same time as S6 construction content. The wiring work of PLC control cabinet and electromagnetic valve can be carried out after the cleaning chamber is hoisted and fixed;

[0056] S8: Fan installation and commissioning

[0057] After the baffle is removed, the water pan is made, and the ammonia removal pipeline is laid, the fan is hoisted and installed. After the fan is installed in place, the wiring is completed, and the fan commissioning can be performed;

[0058] S9: Filter bag installation

[0059] After the fan commissioning is completed, the filter bag, keel, and injection pipe are installed. The entire filter bag installation process needs to be stopped under the condition of granulation, which can be divided into three times of construction:

[0060] ①First, install the filter bag and keel in the first and second zones. After the installation of the filter bags in the two zones is completed, start the fans in the two zones to ensure normal ventilation of the urea prilling tower. Start to resume granulation. Since the urea solution tank liquid level is high after stopping granulation, it needs time to lower the liquid level. During this period, install the injection pipe and clean room manhole sealing strip in the first and second zones;

[0061] ②After the urea solution tank is lowered to a low liquid level, stop granulation and install the filter bag, keel, and injection pipe in the third zone. After all the components are installed, start the fan in the third zone;

[0062] ③After the first two times of construction of the filter bag, keel, and injection pipe, 3 / 4 of the entire air outlet area has been installed with filter components, reaching the normal operating state. The fourth zone filter components can be installed under normal granulation conditions. After the filter bag installation is completed, start all the fans and put the dust removal system into operation. Then, enter the trial operation stage;

[0063] S10: Finishing work

[0064] The finishing work is the welding of the bottom box plate, the commissioning of the dust removal system, and the commissioning of the recovery system, which can be performed during the trial operation stage. The welding of the box requires stopping granulation and stopping the fan to prevent the formation of negative pressure in the clean gas chamber, which can suck the welding slag into the interior and ignite the filter bag.

[0065] Preferably, in the present embodiment, in S1, according to the load of the crane, the clean room accessories are assembled, including: gas collection tank, flow collector, and guardrail.

[0066] It should be specifically noted that the online construction of the urea prilling tower top bag-type dust recovery device can be realized through the above steps.

[0067] Example Two

[0068] Please refer to Figure 1 An online construction method of a urea prilling tower top bag-type dust recovery device, comprising the following steps:

[0069] S1: Ground preparation

[0070] According to the drawing requirements, the truss is spliced on the ground, and after the truss is assembled, the assembly of the cleaning chamber is completed. The cleaning chamber is assembled according to the drawing requirements and the component number at the bottom of the urea prilling tower. The welding of the spliced joint needs to meet the technical requirements, and the flatness of the components needs to be adjusted according to the requirements;

[0071] S2: civil construction

[0072] Cut the expanded urea prilling tower top air outlet to ensure the ventilation and filtration area. Cut the parapet opening at the top of the urea prilling tower and drill truss anchor bolt holes at the corresponding position. Wash the ground water recovery tank and water washing circulating pump foundation. Level and anticorrosive treatment is carried out on the cutting surface and equipment foundation;

[0073] S3: truss and cleaning chamber hoisting and installation

[0074] Before hoisting, the prilling needs to be stopped, the precast steel plate for splicing the water receiving tray is hoisted into the specified position, and the normal production prilling is carried out at other times. Welding personnel are organized to reinforce the hoisted components and complete the welding work of each connection part. At the same time, the box plate attached to the steel structure is hoisted and welded and reinforced. After the truss is in place, it is fixed to the urea prilling tower bearing wall with chemical bolts. After the truss is installed and fixed, the four zone cleaning chambers are hoisted. The hoisting and welding of the truss and the cleaning chamber are carried out under the normal production condition of the urea prilling tower. The bottom end of the box plate is temporarily not welded to ensure sufficient air flow in the urea prilling tower during the installation of the filter bag;

[0075] S4: laying of recovery system pipeline

[0076] The installation of the recovery system, pipeline laying, valve installation and S3 are carried out at the same time. The reserved port work of related pipeline connection is completed;

[0077] S5: remove the louver and make the water receiving tray

[0078] After the louver is removed, the scaffolding is completely removed, and then the water receiving tray is spliced and made. This process needs to be carried out under the condition of stopping prilling;

[0079] S6: laying of ammonia abatement atomization pipeline

[0080] The installation of the ammonia abatement pipeline needs to stop prilling and is completed in 3-4 times. While the ammonia abatement pipeline is constructed, the monitoring personnel color the water receiving tray for leakage test;

[0081] S7: laying of power line

[0082] The welding of cable bridge and cable laying work is carried out at the same time as S6 construction content. The wiring work of PLC control cabinet and solenoid valve can be carried out after the cleaning chamber is hoisted and fixed.

[0083] S8: Fan installation and commissioning

[0084] After the blinds are removed, the water pan is made, and the ammonia removal pipeline is laid, the fan is hoisted and installed. After the fan is installed in place, the wiring is completed, and the fan can be commissioned.

[0085] S9: Filter bag installation

[0086] After the fan commissioning is completed, the filter bag, keel, and injection pipe are installed. The entire filter bag installation process needs to be stopped under the condition of granulation, which can be divided into three times of construction:

[0087] ① First, install the filter bags and keels in areas one and two. After the installation of the filter bags in these two areas is completed, start the fans in these two areas to ensure normal ventilation of the urea prilling tower and start to resume granulation. Since the urea solution tank liquid level is high after stopping granulation, it needs time to lower the liquid level. During this period, the installation of the injection pipes and clean room manhole sealing strips in areas one and two is carried out.

[0088] ② After the urea solution tank is lowered to a low liquid level, stop granulation and install the filter bags, keels, and injection pipes in area three. After all the components are installed, start the fan in area three.

[0089] ③ After the first two times of construction of the filter bags, keels, and injection pipes, 3 / 4 of the entire air outlet area has been installed with filter components, reaching a normal operating state. The filter components in area four can be installed under normal granulation conditions. After the installation of the filter bags is completed, start all the fans and put the dust removal system into operation, which can enter the trial operation stage.

[0090] S10: Finishing work

[0091] The finishing work is the welding of the bottommost box body plate, the commissioning of the dust removal system, and the commissioning of the recovery system, which can be carried out during the trial operation stage. The welding of the box body needs to stop granulation and shut down the fan to prevent the formation of negative pressure in the clean gas chamber, which can suck welding slag into the interior and ignite the filter bags.

[0092] Preferably, in this embodiment, in S1, according to the load of the crane, the clean room accessories are assembled, including the gas collection tank, the flow collector, and the guardrail.

[0093] Preferably, in this embodiment, in S2, before the civil construction, a scaffold is erected inside the urea prilling tower air outlet to support the falling concrete during the construction process. The scaffold erection stops granulation until the scaffold erection is completed, and the remaining time is for normal production granulation.

[0094] Preferably, in the embodiment, in S5, the splicing of the water pan is completed in 7-8 times, and the intermittent time ensures the normal production of the urea prilling machine, ensures the stable operation of the urea prilling machine, and the construction party can interleave with other construction contents, but it is necessary to avoid simultaneous work with the cleaning room or steel structure welding work to prevent cross operation from causing personal injury.

[0095] Preferably, in the embodiment, in S9, the filter bag must be installed in the whole area each time, and it is not allowed to start prilling under the condition that the installation in a certain area is not completed, otherwise the inner surface of the filter bag in the area will be contaminated by dust, resulting in that the exhaust analysis after trial operation does not meet the standard.

[0096] It needs to be specifically pointed out that: by further limiting, in S2, before the civil construction, a scaffold is erected in the inner circle of the urea prilling tower outlet to support the falling concrete during the construction process, the scaffold stops prilling until the scaffold erection is completed, the remaining time is normal production prilling, in S5, the splicing of the water pan is completed in 7-8 times, and the intermittent time ensures the normal production of the urea prilling machine, ensures the stable operation of the urea prilling machine, and the construction party can interleave with other construction contents, but it is necessary to avoid simultaneous work with the cleaning room or steel structure welding work to prevent cross operation from causing personal injury, in S9, the filter bag must be installed in the whole area each time, and it is not allowed to start prilling under the condition that the installation in a certain area is not completed, otherwise the inner surface of the filter bag in the area will be contaminated by dust, resulting in that the exhaust analysis after trial operation does not meet the standard, so as to better realize the online construction of the bag type dust recovery device at the top of the urea prilling tower.

[0097] It needs to be specifically pointed out that: by further limiting, in S2, before the civil construction, a scaffold is erected in the inner circle of the urea prilling tower outlet to support the falling concrete during the construction process, the scaffold stops prilling until the scaffold erection is completed, the remaining time is normal production prilling, in S5, the splicing of the water pan is completed in 7-8 times, and the intermittent time ensures the normal production of the urea prilling machine, ensures the stable operation of the urea prilling machine, and the construction party can interleave with other construction contents, but it is necessary to avoid simultaneous work with the cleaning room or steel structure welding work to prevent cross operation from causing personal injury, in S9, the filter bag must be installed in the whole area each time, and it is not allowed to start prilling under the condition that the installation in a certain area is not completed, otherwise the inner surface of the filter bag in the area will be contaminated by dust, resulting in that the exhaust analysis after trial operation does not meet the standard, so as to better realize the online construction of the bag type dust recovery device at the top of the urea prilling tower.

[0098] For those skilled in the art, it is obvious that the present application is not limited to the details of the above exemplary embodiments, and the present application can be realized in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application.

[0099] Furthermore, it should be understood that although the specification is described in terms of embodiments, not every embodiment includes only one independent technical solution, and the specification is described in this way only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. An online construction method of a urea prilling tower overhead baghouse dust recovery device, characterized by, The method comprises the following steps: S1: ground prefabrication According to the drawing requirements, the truss is spliced on the ground, and after the truss is assembled, the assembly of the cleaning chamber is completed. The cleaning chamber is assembled according to the drawing requirements and the component number at the bottom of the urea prilling tower. The welding of the joint needs to meet the technical requirements, and the flatness of the components needs to be adjusted according to the requirements. S2: civil construction Cut the expanded urea prilling tower top air outlet to ensure the ventilation and filtration area. Cut the parapet wall opening at the top of the urea prilling tower, drill truss anchor bolt holes at the corresponding position of the opening, and cut the surface and equipment foundation for flatness and corrosion prevention treatment. S3: truss and cleaning chamber hoisting and installation Before hoisting, the prilling needs to be stopped, the water receiving plate spliced with the prefabricated steel plate is hoisted into the specified position, and the other time is normal production and prilling. Welding personnel are organized to reinforce the hoisted components, complete the welding work of each connecting part, and hoist and weld the steel structure attached box plate. After the truss is in place, it is fixed to the urea prilling tower bearing wall with chemical bolts. After the truss is installed and fixed, the four-zone cleaning chamber is hoisted. The hoisting and welding of the truss and the cleaning chamber are carried out under the condition of normal production of the urea prilling tower. The bottom end of the box plate is temporarily not welded to ensure sufficient air flow in the urea prilling tower during the installation of the filter bag. S4: recovery system pipeline laying The installation, pipeline laying, valve installation of the recovery system are carried out at the same time as S3, and the reserved port work of the related pipeline connection is completed. S5: remove the louver and make the water receiving plate After the louver is removed, the scaffolding is completely removed, and then the water receiving plate is spliced and made. This process needs to be carried out under the condition of stopping prilling. S6: ammonia abatement atomization pipeline laying The installation of the ammonia abatement pipeline needs to stop prilling and is completed in 3-4 times. While the ammonia abatement pipeline is being constructed, the monitoring personnel color the water receiving plate and test the leakage. S7: power line laying The cable bridge welding and cable laying work are carried out at the same time as S6. The PLC control cabinet and electromagnetic valve wiring work can be carried out after the cleaning chamber hoisting and fixing are completed. S8: fan installation and debugging After the louver is removed, the water receiving plate is made, and the ammonia abatement pipeline is laid, the fan is hoisted and installed. After the fan is installed in place, the wiring is completed, and the fan debugging can be carried out. S9: filter bag installation After the fan debugging is completed, the filter bag, keel, and injection pipe are installed. The entire filter bag installation process needs to be carried out under the condition of stopping prilling and can be divided into three times: ①First, install the filter bag and keel in the first and second zones. After the installation of the filter bags in the two zones is completed, start the fans in the two zones to ensure normal ventilation of the urea prilling tower and start to resume prilling. Since the urea solution tank liquid level is high after stopping prilling, the liquid level needs to be lowered. During this period, the installation of the injection pipe and the cleaning chamber manhole sealing rubber strip in the first and second zones is carried out. ②After the urea solution tank is lowered to a low liquid level, stop prilling to install the filter bag, keel, and injection pipe in the third zone. After all the components are installed, start the fan in the third zone. ③ After the first two times to filter bag, keel, spray pipe construction, at this time the entire outlet 3 / 4 area has been installed filter components, to achieve normal operating state, four area filter components can be installed under normal granulation, filter bag installation is complete, start all the fan, put into use dust removal system, can enter the commissioning phase; S10: finishing work Finishing work is the bottom box plate welding, dust removal system debugging, recycling system debugging, can be carried out in the commissioning stage, which weld the box need to stop granulation, the fan stop, prevent the clean air chamber to form a negative pressure, the welding slag into the internal, ignition filter bag.

2. The urea prilling tower overhead baghouse dust recovery device online construction method of claim 1, wherein, In S1, according to the load of crane, the cleaning chamber accessories are assembled, including: gas collection tank, flow collector and guardrail.

3. The urea prilling tower overhead baghouse dust recovery device online construction method of claim 1, wherein, In S2, before the civil construction, the scaffold is erected in the inner circle of the urea prilling tower outlet, which is used to support the falling concrete during the construction process. The scaffold erection stops granulation until the scaffold erection is completed. The remaining time is normal production granulation.

4. The urea prilling tower overhead baghouse dust recovery device online construction method of claim 1, wherein, In S5, the assembly of the water receiving tray is completed in 7-8 times. Each time interval ensures the normal production of the urea prilling machine, ensures the stable operation of the urea prilling machine, and enables the construction party to interleave with other construction contents, but avoids simultaneous operation with the cleaning chamber or steel structure welding work to prevent cross operation causing personal injury.

5. The urea prilling tower overhead baghouse dust recovery device online construction method of claim 1, wherein, In S9, each time the filter bag must be installed in the whole area. It is not allowed to start granulation before the installation of all filter bags in a certain area. Otherwise, the inner surface of the filter bag in the area will be contaminated by dust, resulting in off-specification exhaust analysis after commissioning.

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