Urea direct injection pyrolysis system adopting novel pipeline heat tracing mode

Abstract

The invention relates to the technical field of flue gas denitration and pipeline heat tracing, and discloses a urea direct injection pyrolysis system in a novel pipeline heat tracing mode, the urea direct injection pyrolysis system comprises a mixing unit, a metering output unit and a pipeline heat tracing unit, the mixing unit comprises a urea solution supply pipeline, a demineralized water supply pipeline and a mixed liquid supply pipeline; the metering output unit comprises a plurality of metering output pipelines and a return pipeline, and each metering output pipeline is correspondingly connected with a spray gun in the spray gun system; the pipeline heat tracing unit is connected with the urea solution supply pipeline and the metering output unit; in the invention, the concentration of the urea solution is adjusted and monitored in a multi-stage manner through the mixing unit and the metering output unit, so that the concentration is kept consistent before the urea solution reaches the spray gun, and a pipeline of the flushing water unit is matched, so that the problem of pipeline blockage when a pipeline system is not used or is suspended in use is avoided; and the recovered drainage waste heat is further utilized for pipeline heat tracing, so that the operation economy of the unit is reduced while the pipeline is prevented from being blocked.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas denitration system and pipeline heating, and in particular to a urea direct injection pyrolysis system with a novel pipeline heating method. Background Art

[0002] Urea pyrolysis usually uses high-temperature flue gas from the gas turbine outlet to be drawn out through a high-temperature fan and passed into a urea pyrolysis furnace to pyrolyze the urea solution to produce ammonia; the urea hydrolysis system uses low-quality steam (0.8-1.0, 160-200 degrees) to hydrolyze the urea solution in the reactor to produce a mixed gas containing ammonia. The system is complex, and the auxiliary pipelines have high requirements for insulation and heating, which is prone to pipeline crystallization blockage and valve corrosion. Both of the above ammonia production technologies require a large amount of heat source, and the system operation and maintenance costs are high, which to a certain extent restricts the engineering application of their technologies. Urea direct injection pyrolysis technology is to spray the urea solution into the flue in an atomized form, and use the high-temperature flue gas (350-600 degrees) in the flue to pyrolyze the urea solution to produce a mixed gas containing ammonia for use in the downstream SCR reactor. The system is simple and easy to operate.

[0003] The metering and distribution module of the traditional urea direct injection pyrolysis system is skid-mounted. Each spray gun corresponds to a set of urea solution and compressed air metering and distribution modules. It is impossible to configure flushing water to flush the urea solution pipeline of each spray gun, which may easily cause blockage of the urea solution pipeline; after the urea solution is mixed with dilution water in the distribution module, the concentration of urea solution for each spray gun cannot be determined, which may easily cause the ammonia gas after the pyrolysis of the urea solution in the flue to be unable to be evenly distributed on the catalyst surface; at the same time, the nitrogen oxides at the inlet flue of the SCR gas unit are small, the amount of urea solution is small, and the urea solution distributed to each spray gun is even smaller. The currently used regulating valve cannot achieve precise adjustment.

[0004] Furthermore, in gas turbine power plants, the urea dissolution tank and storage tank of the urea station of the denitrification system are usually heated by high-temperature and high-pressure steam from the power plant. After heating, the steam drain temperature is high. In most cases, the drain is directly discharged into the drain box or ditch, resulting in a waste of drain heat. The urea solution pipeline connecting the metering distribution module to the injection device of the urea direct injection pyrolysis system is usually a small-diameter pipeline, which is inconvenient to heat. Electric heating is generally used, but the heating effect is poor and unstable, and pipeline blockage often occurs. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above problems existing in the existing urea direct injection pyrolysis system, the present invention is proposed.

[0007] Therefore, the object of the present invention is to provide a urea direct injection pyrolysis system with a novel pipeline heating method, which aims to solve the problems of urea solution blocking the delivery pipeline, poor mixing and regulation of urea solution output by the spray gun, and poor pipeline heating effect of low-concentration urea solution.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: a urea direct injection pyrolysis system with a new pipeline heating method, the system comprising a mixing unit, a metering output unit, a pipeline heating unit, a flushing water unit and a compressed air unit, wherein the mixing unit comprises a urea solution supply pipeline, a desalted water supply pipeline and a mixed liquid supply pipeline connected to the output ends of the urea solution supply pipeline and the desalted water supply pipeline; the metering output unit is connected to the mixed liquid supply pipeline, and comprises a plurality of metering output pipelines and a reflux pipeline connected thereto, and the output end of each of the metering output pipelines is connected to a corresponding spray gun in a spray gun system; and the pipeline heating unit is connected to the urea solution supply pipeline and the metering output unit, and comprises a steam drain pipeline and a gas heat exchange pipeline connected thereto.

[0009] As a preferred solution of the urea direct injection pyrolysis system with the novel pipeline heating method described in the present invention, the urea solution supply pipeline includes a urea dissolving tank and a storage tank, a urea delivery pipeline connected to the urea dissolving tank and the storage tank, and a delivery control valve, a delivery filter, a urea solution delivery pump, a urea delivery pressure gauge, a urea solution regulating valve, and an electromagnetic flowmeter sequentially connected to the urea delivery pipeline; and a steam coil is arranged in the tank body of the urea dissolving tank and the storage tank.

[0010] As a preferred solution of the urea direct injection pyrolysis system with the new pipeline heating method described in the present invention, the desalted water supply pipeline includes a desalted water storage tank, a desalted water delivery pipeline connected to the desalted water storage tank, and a desalted water control valve, a desalted water delivery pump, a desalted water delivery pressure gauge, a desalted water regulating valve, and an electromagnetic flowmeter sequentially connected to the desalted water delivery pipeline.

[0011] As a preferred solution of the urea direct injection pyrolysis system with the new pipeline heating method described in the present invention, the mixed liquid supply pipeline includes a mixed liquid main pipeline and a mixer connected to the mixed liquid main pipeline, a main pipeline control valve, a main pipeline pressure gauge, a main pipeline filter and a mixed liquid drain valve; the output ends of the urea delivery pipeline and the desalted water delivery pipeline are both connected to the input end of the mixed liquid main pipeline.

[0012] As a preferred solution of the urea direct injection pyrolysis system with the new pipeline heating method described in the present invention, the input end of the metering output pipeline is connected to the mixed liquid main pipeline after the output port of the main pipeline filter, and the output end is connected to the first input end of the spray gun; the metering output pipeline includes an output pipeline and a urea solution solenoid valve, a check valve, a gear pump, an output pipe drain valve, a first output pipe pressure gauge, a mass flow meter, a manual pressure regulating valve, a second output pipe pressure gauge, a reversing valve and an output pipe filter which are sequentially connected to the output pipeline.

[0013] As a preferred solution of the urea direct injection pyrolysis system with the new pipeline heating method described in the present invention, the return pipeline includes a return pipeline and a check valve and a return pipe solenoid valve connected to the return pipeline; the input end of the return pipeline is connected to one-way output end of the reversing valve, and its output end is connected to the input end of the output pipeline.

[0014] As a preferred solution of the urea direct injection pyrolysis system with the new pipeline heating method described in the present invention, the steam drain pipeline includes a steam input pipeline connected to the input end of the steam coil, a drain pipeline connected to the output end of the steam coil, and a thermometer, a check valve, a drain booster pump, a heater and a drain tank connected to the drain pipeline in sequence; control ball valves are installed in the steam input pipeline and the drain pipeline.

[0015] As a preferred solution of the urea direct injection pyrolysis system with the new pipeline heating method described in the present invention, the gas heat exchange pipeline includes a cold air pipeline connected to the input end of the heater, a hot air pipeline connected to the output end of the heater, and a booster fan, a temperature gauge, and a pressure gauge connected to the hot air pipeline in sequence, and the output end of the hot air pipeline is connected to the heating layer outside the output pipeline.

[0016] As a preferred solution of the urea direct injection pyrolysis system with the new pipeline heating method described in the present invention, it also includes: a compressed air unit, including an atomizing air pipeline and a cooling air pipeline, the output ends of the two pipelines are respectively connected to the second input end and the third input end of the spray gun; a flushing water unit, whose input end is connected to the desalted water supply pipeline, and the output end is connected to the metering output pipeline.

[0017] As a preferred solution of the urea direct injection pyrolysis system with the new pipeline heating method described in the present invention, the flushing water unit includes a flushing water main pipeline, a plurality of flushing water pipelines connected to the flushing water main pipeline, and a flushing water discharge valve connected to the output end of the flushing water main pipeline; a flushing water main pipeline control valve is connected to the flushing water main pipeline; the output end of the flushing water pipeline is connected to the output pipeline between the check valve and the gear pump, and a flushing water solenoid valve is installed in the flushing water pipeline.

[0018] Beneficial effects of the present invention:

[0019] In the pipeline system of the present invention, the concentration of the urea solution is adjusted and monitored at multiple stages through the mixing unit and the metering output unit, so that the concentration remains consistent before it reaches the spray gun, and the pipeline of the flushing water unit is matched to avoid the pipeline blockage problem when the pipeline system is not in use or suspended. Compared with the traditional pipeline system, the distribution module is reduced, the system pipeline is simpler and more convenient, and the coordinated cooperation of the vector pump and the mass flow meter makes the control and adjustment of the urea solution in the spray gun faster and more accurate; further, the hydrophobic in the urea dissolution tank and the urea storage tank is utilized to heat the cold air for heating the pipeline in the metering module, which can effectively reduce the use of electric heating and improve the economic efficiency of the unit operation; after the waste heat of the hydrophobic is recovered and utilized, the temperature is reduced, and the steam emission from the hydrophobic tank can be eliminated. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0021] Figure 1 The figure is a schematic diagram of the overall pipeline framework structure of the urea direct injection pyrolysis system with the novel pipeline heating method of the present invention.

[0022] Figure 2 The present invention is a schematic diagram of the urea solution supply pipeline structure of the urea direct injection pyrolysis system with a new pipeline heating method.

[0023] Figure 3 This is a schematic diagram of the desalted water supply pipeline structure of the urea direct injection pyrolysis system with the new pipeline heating method of the present invention.

[0024] Figure 4 The present invention is a schematic diagram of the mixed liquid supply pipeline structure of the urea direct injection pyrolysis system with a new pipeline heating method.

[0025] Figure 5 This is a schematic diagram of the structure of the metering output unit of the urea direct injection pyrolysis system with a new pipeline heating method of the present invention.

[0026] Figure 6 This is a schematic diagram of the structure of the pipeline heating unit of the urea direct injection pyrolysis system with the new pipeline heating method of the present invention.

[0027] Figure 7 This is a schematic diagram of the structure of the compressed air unit of the urea direct injection pyrolysis system with a new pipeline heating method of the present invention.

[0028] Figure 8 This is a schematic diagram of the structure of the flushing water unit of the urea direct injection pyrolysis system with a new pipeline heating method of the present invention.

[0029] Fig. 9 The figure is a schematic diagram of the overall pipeline connection structure of the urea direct injection pyrolysis system with the novel pipeline heating method of the present invention. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0031] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0032] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0033] Secondly, the present invention is described in detail with reference to the schematic diagram. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0034] Example 1

[0035] Reference Figure 1 and 8, which is the first embodiment of the present invention, provides a urea direct injection pyrolysis system with a novel pipeline heating method, the system includes a mixing unit 100, a metering output unit 200, a pipeline heating unit 300, a flushing water unit 400 and a compressed air unit 500, wherein the mixing unit 100 is used to mix urea solution and demineralized water to prepare a preset urea solution concentration; the metering output unit 200 is used to correspond to each spray gun system, monitor the concentration of urea solution input into the spray gun P, and facilitate the adjustment of the spray gun; the pipeline heating unit 300 is used to heat the low-concentration urea solution pipeline before the input spray gun P, thereby ensuring that the urea solution will not be blocked in the metered distribution pipeline; the compressed air unit 400 is used to cool the pipeline in the spray gun and prevent the urea solution from being evaporated in the spray gun pipeline; the flushing water unit 500 is used to clean each pipeline to avoid pipeline blockage.

[0036] The mixing unit 100 includes a urea solution supply pipeline 101, a desalted water supply pipeline 102 and a mixed liquid supply pipeline 103 connected to the output ends of the urea solution supply pipeline 101 and the desalted water supply pipeline 102; wherein the urea solution supply pipeline 101 provides an initial urea solution, and the desalted water supply pipeline 102 provides an initial desalted water, the two are mixed in the mixed liquid supply pipeline 103, and diluted to prepare a urea solution of a required concentration, and output and distributed to the metering output unit 200.

[0037] The metering output unit 200 is connected to the mixed liquid supply pipeline 103, and includes a plurality of metering output pipelines 201 and a return pipeline 202 connected thereto. The output end of each metering output pipeline 201 is connected to a corresponding spray gun P in the spray gun system; wherein each group of metering output pipelines 201 corresponds to a connected spray gun system and is also connected to a corresponding return pipeline 202. The output end of the metering output pipeline 201 is connected to the spray gun P to provide urea solution to the corresponding spray gun P. A vector pump and a mass flow meter that can cooperate with each other are installed in the pipeline, and can provide a urea solution with an accurate flow rate and concentration to the corresponding spray gun system.

[0038] The pipeline heating unit 300 is connected to the urea solution supply pipeline 101 and the metering output unit 200, and includes a steam drain pipeline 301 and a gas heat exchange pipeline 302 connected thereto; wherein the steam drain pipeline 301 is used to lead out the steam drain used for heating the urea dissolving tank and the storage tank, and the gas heat exchange pipeline 302 exchanges heat with the discharged steam drain to form hot air, which is then introduced into the metering output pipeline 201 for pipeline heating, recovering the heat in the drain, improving energy utilization, and saving energy and protecting the environment.

[0039] Example 2

[0040] Reference Figures 2 to 5 and Figures 7 to 9 , which is the second embodiment of the present invention. This embodiment is different from the first embodiment in that: a urea solution supply pipeline 101 includes a urea dissolving tank and a storage tank 101a, a urea delivery pipeline 101b connected to the urea dissolving tank and the storage tank 101a, and a delivery control valve 101c, a delivery filter 101d, a urea solution delivery pump 101e, a urea delivery pressure gauge 101f, a urea solution regulating valve 101g, and an electromagnetic flowmeter D sequentially connected to the urea delivery pipeline 101b; and a steam coil 101a-1 is provided in the tank body of the urea dissolving tank and the storage tank 101a.

[0041] Specifically, the urea dissolving tank and storage tank 101a includes a urea dissolving tank and a urea storage tank. High-concentration urea solution or urea preparation raw materials are stored in the two tanks. In this embodiment, a urea solution with a concentration of 50% is stored as an example. The urea delivery pipeline 101b connects the urea dissolution tank and storage tank 101a and the mixer 103b in the mixed liquid supply pipeline 103, and is used to deliver the urea raw material to the mixer 103b as needed. The delivery control valve 101c installed in the pipeline is used to control the on-off of the delivery pipeline; the delivery filter 101d is used to filter out impurities that may exist in the urea raw material to maintain the purity of the output urea; the urea solution delivery pump 101e provides driving force for the delivery of urea solution in the pipeline; the urea delivery pressure gauge 101f is used to monitor the pressure in the delivery pipeline; the urea solution regulating valve 101g is used to adjust the flow rate of the urea solution output from the urea delivery pipeline 101b; the electromagnetic flowmeter D monitors and displays the flow value of the output urea solution, and the urea solution regulating valve 101g can be intuitively adjusted based on this monitoring value.

[0042] Furthermore, the desalted water supply pipeline 102 includes a desalted water storage tank 102a, a desalted water delivery pipeline 102b connected to the desalted water storage tank 102a, and a desalted water control valve 102c, a desalted water delivery pump 102d, a desalted water delivery pressure gauge 102e, a desalted water regulating valve 102f, and an electromagnetic flowmeter D which are sequentially connected to the desalted water delivery pipeline 102b.

[0043] Desalted water is stored in a desalted water storage tank 102a. It should be noted that this is not limited to storage tanks, but can also be other types of storage methods. The desalted water delivery pipeline 102b connects the desalted water storage tank 102a and the mixer 103b in the mixed liquid supply pipeline 103, and is used to deliver the desalted water to the mixer 103b as needed; the desalted water control valve 102c installed in the pipeline is used to control the on-off of the desalted water delivery pipeline 102b; the desalted water delivery pump 102d is used to provide the driving force required for liquid pumping; the desalted water delivery pressure gauge 102e is used to monitor the pressure in this delivery pipeline, and the desalted water regulating valve 102f is used to adjust the flow rate of the desalted water output from the desalted water delivery pipeline 102b; the electromagnetic flowmeter D monitors and displays the flow value of the output desalted water, and the desalted water regulating valve 102f can be intuitively adjusted based on this monitoring value.

[0044] The mixed liquid supply pipeline 103 includes a mixed liquid main pipeline 103a and a mixer 103b connected to the mixed liquid main pipeline 103a, a main pipeline control valve 103c, a main pipeline pressure gauge 103d, a main pipeline filter 103e and a mixed liquid drain valve 103f; the output ends of the urea delivery pipeline 101b and the deionized water delivery pipeline 102b are both connected to the input end of the mixed liquid main pipeline 103a.

[0045] Among them, the mixed liquid main pipeline 103a is the main pipeline for supplying mixed and diluted urea solution, and is connected to each group of metering output pipelines 201; the input end of the mixed liquid main pipeline 103a is respectively connected to the output ends of the urea delivery pipeline 101b and the desalted water delivery pipeline 102b, receives two medium raw materials, and merges them into the mixer 103b for mixing. In this embodiment, a two-stage mixer is used, which is divided into a first mixer and a second mixer. The amount of desalted water is adjusted in real time according to the flow rate of the urea solution, and finally the required low-concentration urea solution is prepared in the mixer 103b and delivered to the output end side of the mixed liquid main pipeline 103a.

[0046] On the output side of the mixer 103b in the mixed liquid main pipeline 103a, the main pipeline control valve 103c is used to control the on-off of the pipeline, the main pipeline pressure gauge 103d is used to monitor the pressure in the pipeline, and the main pipeline filter 103e is used to filter and remove impurities in the pipeline; the mixed liquid drain valve 103f is used to discharge the flushing liquid or the waste mixed liquid in the main pipeline. It should be noted that the main pipeline control valve 103c and the main pipeline filter 103e may be provided in multiples according to requirements, which will not be described in detail here.

[0047] The input end of the metering output pipeline 201 is connected to the mixed liquid main pipeline 103a after the output port of the main pipeline filter 103e, and the output end is connected to the first input end of the spray gun P; the metering output pipeline 201 includes an output pipeline 201a and a urea solution solenoid valve 201b, a check valve N, a gear pump 201c, an output pipe drain valve 201d, an output pipe first pressure gauge 201e, a mass flow meter 201f, a manual pressure regulating valve 201g, an output pipe second pressure gauge 201h, a reversing valve 201j and an output pipe filter 201k which are sequentially connected to the output pipeline 201a.

[0048] Specifically, the metering output pipeline 201 connects the mixed liquid main pipeline 103a and the spray gun system, wherein the output pipeline 201a is the main connecting pipeline, the urea solution solenoid valve 201b arranged in the pipeline is used to control the on-off of the pipeline, and the check valve N is used to prevent the urea solution from flowing back; the gear pump 201c is used to accurately adjust the output amount of the spray gun P to the urea solution; the output pipe drain valve 201d is used to meter the discharge of flushing water when the output pipeline 201 is cleaned; the first pressure gauge 201e of the output pipe is used to monitor the pressure in the pipeline before it flows to the mass flow meter 201f; the manual pressure regulating valve 201g is used for further pressure regulation in the pipeline; the second pressure gauge 201h of the output pipe is used to monitor the pressure in the pipeline after two pressure adjustments, so as to ensure that the pressure and concentration of the urea solution in the input spray gun system meet the predetermined requirements; the reversing valve 201j is used to adjust the flow direction of the pipeline, whether it flows to the spray gun P through the output pipe filter 201k or flows to the return pipeline 202.

[0049] Furthermore, the return line 202 includes a return pipe 202a and a check valve N and a return pipe solenoid valve 202b connected to the return pipe 202a; the input end of the return pipe 202a is connected to one output end of the reversing valve 201h, and its output end is connected to the input end of the output pipe 201a.

[0050] The return pipe 202 is used for the circulation of urea solution when the spray gun system is temporarily stopped to prevent condensation and blockage in the pipeline system. The check valve N in the return pipe 202a is used to maintain the unidirectional flow of urea solution in the pipeline; the return pipe solenoid valve 202b is used to control the on-off of the return pipe 202a.

[0051] The flushing water unit 500 includes a flushing water main pipeline 501, a plurality of flushing water pipes 502 connected to the flushing water main pipeline 501, and a flushing water discharge valve 503 connected to the output end of the flushing water main pipeline 501; a flushing water main pipeline control valve 501a is connected to the flushing water main pipeline 501; the output end of the flushing water pipe 502 is connected to the output pipe 201a between the check valve N and the gear pump 201b, and a flushing water solenoid valve 502a is installed in the flushing water pipe 502.

[0052] Specifically, the flushing water main pipeline 501 draws water from the desalted water storage tank 102a or the desalted water delivery pipeline 102b, and controls the on-off of the pipeline through the flushing water main pipeline control valve 501a connected in the pipeline, and discharges the flushing water remaining in the pipeline through the flushing water discharge valve 503; the flushing water pipeline 502 draws water from the flushing water main pipeline 501, and is used for the flushing operation of each metering output pipeline 201; the on-off of the flushing water pipeline 502 is controlled by the flushing water solenoid valve 502a.

[0053] The atomizing air pipeline 401 includes a compressed air source 401a, an atomizing air main pipeline 401b connected to the output end of the compressed air source 401a, and a plurality of atomizing air branch pipelines 401c connected to the atomizing air main pipeline 401b.

[0054] Furthermore, the atomizing gas main pipeline 401b is connected with an atomizing gas main filter 401b-1, an atomizing gas main control valve 401b-2, a gas filtering and reducing pressure triplet 401b-3, an atomizing gas main pressure gauge 401b-4, and an atomizing gas main discharge valve 401b-5 in sequence from the input end to the output end; the atomizing gas branch pipeline 401c is connected with an atomizing gas branch control valve 401c-1, a manual pressure regulating valve 401c-2, an atomizing gas branch pressure gauge 401c-3, an atomizing gas branch float flowmeter 401c-4, and an atomizing gas branch filter 401c-5 in sequence from the input end to the output end, and the output end of the atomizing gas branch pipeline 401c is connected to the second input end of the spray gun P.

[0055] Among them, the compressed air source 401a can be in the form of a compressed air tank or supplied by a compressor, which is not limited here; the atomizing gas main pipeline 401b is connected to the compressed air source 401a to output the compressed air, and the atomizing gas branch pipeline 401c delivers the compressed air from the atomizing gas main pipeline 401b to the corresponding connected spray gun P as needed.

[0056] In the atomizing gas main pipeline 401b, the atomizing gas main pipeline filter 401b-1 is used to filter impurities in the compressed air to avoid affecting the spray gun P; the atomizing gas main pipeline control valve 401b-2 is used to control the on-off of the atomizing gas main pipeline 401b; the air filtering and decompression triplet 401b-3 is used to reduce the pressure and filter the compressed air to meet the use requirements; the atomizing gas main pipeline pressure gauge 401b-4 is used to monitor the pipeline pressure in the atomizing gas main pipeline 401b; the atomizing gas main pipeline discharge valve 401b-5 is used for the discharge and pressure relief of the atomizing gas main pipeline 401b.

[0057] Furthermore, the atomizing gas branch control valve 401c-1 in the atomizing gas branch pipeline 401c is used to control the on-off of the atomizing gas branch pipeline 401c; the manual pressure regulating valve 401c-2 is used to finely adjust the exhaust rate of the atomizing gas branch pipeline 401c to meet the usage requirements; the atomizing gas branch pressure gauge 401c-3 is used to monitor the pressure value in the atomizing gas branch pipeline 401c; the atomizing gas branch float flowmeter 401c-4 is used to monitor the flow rate of the atomizing gas in the pipeline; the atomizing gas branch filter 401c-5 is used to filter the compressed air in the atomizing gas branch pipeline 401c to minimize the impact of impurities on the spray gun P.

[0058] Furthermore, the cooling air pipeline 402 includes a cooling air main pipeline 402a and a plurality of cooling air branch pipelines 402b connected to the cooling air main pipeline 402a; the input end of the cooling air main pipeline 402a is connected to the atomizing air main pipeline 401b at the output port of the atomizing air main filter 401b-1, and a cooling air main control valve 402a-1 and a cooling air main discharge valve 402a-2 are also connected to the pipeline; the output end of the cooling air branch pipeline 402b is connected to the third input end of the spray gun P, and a cooling air branch control valve 402b-1 and a cooling air branch float flowmeter 402b-2 are connected to the pipeline in sequence; the cooling air branch pipeline 402b is also externally connected to a branch pipe 402b-3, and the output end of the branch pipe 402b-3 is connected to the fourth input end of the spray gun P, and a branch pipe control valve F is provided in the pipe.

[0059] The cooling air main pipeline 402a is also connected to a plurality of cooling air branch pipelines 402b; the cooling air main pipeline 402a extracts compressed air from the compressed air source 401a or the atomizing air main pipeline 401b and delivers it to each branch pipeline. In the cooling air main pipeline 402a, the cooling air main discharge valve 402a-1 is used to control the on-off of its pipeline; in the cooling air branch pipeline 402b, the cooling air branch control valve 402b-1 is used to control the on-off of the cooling air branch pipeline 402b; and the cooling air branch float flowmeter 402b-2 is used to monitor the flow of gas in the cooling air branch pipeline 402b.

[0060] Furthermore, the branch pipe 402b-3 is connected to the fourth input end of the spray gun P, and is used to open the branch pipe 402b-3 when the spray gun P is pulled out of the unit for online maintenance to provide sealing air for convenient maintenance.

[0061] The remaining structures are the same as those of Example 1.

[0062] In summary, the contents described in Examples 1 and 2, and with reference to the attached Figures 1 to 9 As shown in the figure, during the use of this pipeline system, the urea solution raw material and the deionized water are first mixed, and a urea solution of a predetermined concentration is prepared after mixing; for the urea solution supply pipeline 101, the delivery control valve 101c, the urea solution delivery pump 101e and the urea solution regulating valve 101g are opened, and the urea solution raw material is pumped into the mixer 103b; for the deionized water supply pipeline 102, the deionized water control valve 102c, the deionized water delivery pump 102d and the deionized water regulating valve 102f are opened, and the deionized water is also pumped into the mixer 103b for mixing, and the urea solution regulating valve 101g and the deionized water regulating valve 102f are adjusted according to the prepared concentration, so as to prepare a urea solution mixed liquid of the required concentration in the mixer 103b, and then the mixed liquid is pressed into the mixed liquid main pipeline 103a.

[0063] The main pipeline 103a of the mixed liquid is connected to several metering output units 200 and their corresponding spray gun systems; when a spray gun P needs to be opened, the urea solution solenoid valve 201b in the corresponding output pipeline 201a is opened, the gear pump 201c is turned on and adjusted to the maximum Hz, the flow rate at this time is read through the mass flow meter 201f, the manual pressure regulating valve 201g is adjusted to the maximum opening, and the reversing valve 201j is switched to the direction of the spray gun P; the mixed liquid enters the output pipeline 201a, and is sprayed into the flue through the output pipe filter 201k.

[0064] Furthermore, the required amount of urea is calculated according to the changes in the nitrogen oxide inlet and outlet of the gas waste heat boiler inlet flue, and the Hertz size of the gear pump 201c is adjusted in real time according to the measurement value of the mass flow meter 201f to achieve precise regulation.

[0065] When the spray gun P is temporarily out of service, the reversing valve 201j is switched to the direction of the return pipe 202a, and the return pipe solenoid valve 202b is opened, and the mixed liquid circulates in the output pipe 201a and the return pipe 202a; and when the spray gun P is put into use again, it is only necessary to switch the reversing valve 201j to the spray gun input direction and close the return pipe solenoid valve 202b. The advantage is that the mixed liquid always flows, and no sedimentation, blockage, or other problems will occur in the return pipe 202 and the return pipe 202.

[0066] When the spray gun system is out of use, close the urea solution solenoid valve 201b, open the flushing water main pipeline control valve 301a, and open the gear pump 201c to the maximum to flush the pipeline from the urea solution solenoid valve 201b to the spray gun. After flushing for a certain period of time, switch the reversing valve 201j to the direction of the return pipe 202a, open the return pipe solenoid valve 202b, and the output pipe drain valve 201d to flush the return pipe 202a.

[0067] Furthermore, the control valves of the metering output units 200 are closed, and the urea solution delivery pump 101e and the urea solution regulating valve 101g in the urea solution supply pipeline 101 are closed, and only the demineralized water supply pipeline 102 is allowed to pass into the mixed liquid supply pipeline 103, and the mixed liquid drain valve 103f is opened to flush the mixed liquid supply pipeline 103.

[0068] When the urea solution pipeline system is put into use and the spray gun P is turned on for use, the atomizing air pipeline 401 is opened synchronously, the atomizing gas main control valve 401b-2 and the atomizing gas branch control valve 401c-1 are opened, and the manual pressure regulating valve 401c-2 is adjusted to make the gas pressure and flow rate within the appropriate range. The compressed air enters the spray gun P through the atomizing gas branch filter 401c-5 to atomize the urea solution into the flue. In order to prevent the urea solution in the spray gun pipeline from being evaporated by the high-temperature flue gas in the flue, the cooling air pipeline 402 needs to be opened, that is, the cooling air main control valve 402a-1 and the cooling air branch control valve 402b-1 are opened to allow cooling air to enter the outer ring of the spray gun urea solution pipeline to cool and absorb the heat received by the urea solution in the flue spray gun to prevent the urea solution from being evaporated in the spray gun pipeline.

[0069] When the spray gun P is pulled out of the unit for online maintenance, the cooling air pipeline 402 can be opened to open the branch pipe control valve F to provide sealing air for easy maintenance.

[0070] Example 3

[0071] Reference Figure 6 , which is the third embodiment of the present invention. This embodiment is based on the scheme in Embodiment 2, but is different from the second embodiment in that: in the output pipe 201a and the return pipe 202a, there is a mixed low-concentration urea solution. In order to reduce the poor heating effect, instability and frequent pipe blockage of the existing electric heating method, a hot air heating method is adopted; for this purpose, a pipe heating unit 300 is set.

[0072] Specifically, the steam drain pipeline 301 includes a steam input pipeline 301a connected to the input end of the steam coil 101a-1, a drain pipeline 301b connected to the output end of the steam coil 101a-1, and a thermometer W, a check valve N, a drain booster pump 301c, a heater 301d and a drain tank 301e connected in sequence to the drain pipeline 301b; a control ball valve Q is installed in both the steam input pipeline 301a and the drain pipeline 301b.

[0073] The steam input pipeline 301a is used to introduce high-temperature and high-pressure hot steam to heat the urea dissolving tank and the urea storage tank; preferably, a thermometer W and a pressure gauge Y are also connected to the steam input pipeline 301a to monitor the temperature and pressure of the steam input in the pipeline; the steam drain after heating the urea dissolving tank and the storage tank 101a is discharged from the drain pipeline 301b, and the temperature of the steam drain is still relatively high. Under the pressure of the drain booster pump 301c, it is pumped into the heater 301d to exchange heat with the cold air introduced into the heater 301d, and the steam drain after heat exchange is discharged into the drain tank 301e; during the process, the thermometer W is used to monitor the temperature of the drain in the drain pipeline 301b; the control ball valve Q is used to control the on and off of the pipeline.

[0074] The gas heat exchange pipeline 302 includes a cold air pipe 302a connected to the input end of the heater 301d, a hot air pipe 302b connected to the output end of the heater 301d, and a booster fan 302c, a temperature gauge W, and a pressure gauge Y connected in sequence to the hot air pipe 302b. The output end of the hot air pipe 302b is connected to the heating layer outside the output pipe 201a.

[0075] Among them, the cold air is introduced into the input end of the heater 301d from the cold air duct 302a, heat is exchanged in the heater 301d to form hot air, and enters the hot air duct 302b. Under the pressure of the booster fan 302c, it is pumped into the heating layer outside the output duct 201a and the return duct 202a. Similarly, the temperature gauge W in the pipeline is used to monitor the temperature to ensure that the temperature of the hot air can reach the heating temperature requirement, and the pressure gauge Y is used to monitor the pressure value in the pipeline to ensure that it has a required pressure value range.

[0076] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A new type of pipeline heating method for urea direct injection pyrolysis system, characterized by: include, A mixing unit (100) comprising a urea solution supply pipeline (101), a desalted water supply pipeline (102), and a mixed liquid supply pipeline (103) connected to output ends of the urea solution supply pipeline (101) and the desalted water supply pipeline (102); a metering output unit (200), connected to the mixed liquid supply pipeline (103), comprising a plurality of metering output pipelines (201) and return pipelines (202) connected thereto, wherein the output end of each metering output pipeline (201) is correspondingly connected to a spray gun (P) in the spray gun system; and The pipeline heating unit (300) is connected to the urea solution supply pipeline (101) and the metering output unit (200), and comprises a steam drain pipeline (301) and a gas heat exchange pipeline (302) connected thereto.

2. The novel pipeline heating method urea direct injection pyrolysis system according to claim 1 is characterized in that: The urea solution supply pipeline (101) comprises a urea dissolving tank and a storage tank (101a), a urea delivery pipeline (101b) connected to the urea dissolving tank and the storage tank (101a), and a delivery control valve (101c), a delivery filter (101d), a urea solution delivery pump (101e), a urea delivery pressure gauge (101f), a urea solution regulating valve (101g), and an electromagnetic flowmeter (D) connected in sequence to the urea delivery pipeline (101b); A steam coil (101a-1) is arranged in the tank body of the urea dissolving tank and storage tank (101a).

3. The novel pipeline heating method urea direct injection pyrolysis system according to claim 2 is characterized by: The desalted water supply pipeline (102) comprises a desalted water storage tank (102a), a desalted water delivery pipeline (102b) connected to the desalted water storage tank (102a), and a desalted water control valve (102c), a desalted water delivery pump (102d), a desalted water delivery pressure gauge (102e), a desalted water regulating valve (102f), and an electromagnetic flowmeter (D) connected in sequence to the desalted water delivery pipeline (102b).

4. The novel pipeline heating method urea direct injection pyrolysis system according to claim 3 is characterized by: The mixed liquid supply pipeline (103) comprises a mixed liquid main pipeline (103a), a mixer (103b) connected to the mixed liquid main pipeline (103a), a main pipeline control valve (103c), a main pipeline pressure gauge (103d), a main pipeline filter (103e) and a mixed liquid drain valve (103f); The output ends of the urea delivery pipeline (101b) and the desalted water delivery pipeline (102b) are both connected to the input end of the mixed liquid main pipeline (103a).

5. The novel pipeline heating method urea direct injection pyrolysis system according to claim 4 is characterized in that: The input end of the metering output pipeline (201) is connected to the mixed liquid main pipeline (103a) after the output port of the main pipeline filter (103e), and the output end is connected to the first input end of the spray gun (P); The metering output pipeline (201) comprises an output pipeline (201a) and a urea solution solenoid valve (201b), a check valve (N), a gear pump (201c), an output pipe drain valve (201d), an output pipe first pressure gauge (201e), a mass flow meter (201f), a manual pressure regulating valve (201g), an output pipe second pressure gauge (201h), a reversing valve (201j) and an output pipe filter (201k) which are sequentially connected to the output pipeline (201a).

6. The novel pipeline heating method urea direct injection pyrolysis system according to claim 5 is characterized by: The return pipeline (202) comprises a return pipe (202a), a check valve (N) connected to the return pipe (202a), and a return pipe solenoid valve (202b); The input end of the return pipe (202a) is connected to one output end of the reversing valve (201h), and the output end thereof is connected to the input end of the output pipe (201a).

7. The novel pipeline heating method urea direct injection pyrolysis system according to claim 6 is characterized by: The steam drain pipeline (301) comprises a steam input pipeline (301a) connected to the input end of the steam coil (101a-1), a drain pipeline (301b) connected to the output end of the steam coil (101a-1), and a temperature gauge (W), a check valve (N), a drain booster pump (301c), a heater (301d) and a drain tank (301e) connected in sequence to the drain pipeline (301b); Control ball valves (Q) are installed in both the steam input pipe (301a) and the drain pipe (301b).

8. The novel pipeline heating method urea direct injection pyrolysis system according to claim 7 is characterized in that: The gas heat exchange pipeline (302) comprises a cold air pipeline (302a) connected to the input end of the heater (301d), a hot air pipeline (302b) connected to the output end of the heater (301d), and a booster fan (302c), a temperature gauge (W), and a pressure gauge (Y) connected in sequence to the hot air pipeline (302b); the output end of the hot air pipeline (302b) is connected to the heating layer outside the output pipeline (201a).

9. The novel pipeline heating method urea direct injection pyrolysis system according to claim 8 is characterized in that: Also includes, A compressed air unit (400) comprises an atomizing air pipeline (401) and a cooling air pipeline (402), wherein the output ends of the two pipelines are respectively connected to the second input end and the third input end of the spray gun (P); The flushing water unit (500) has an input end connected to the demineralized water supply pipeline (102) and an output end connected to the metering output pipeline (201).

10. The novel pipeline heating method urea direct injection pyrolysis system according to claim 9 is characterized in that: The flushing water unit (500) comprises a flushing water main pipeline (501), a plurality of flushing water pipelines (502) connected to the flushing water main pipeline (501), and a flushing water discharge valve (503) connected to the output end of the flushing water main pipeline (501); The flushing water main pipeline (501) is connected to a flushing water main pipeline control valve (501a); The output end of the flushing water pipeline (502) is connected to the output pipeline (201a) between the check valve (N) and the gear pump (201b), and a flushing water solenoid valve (502a) is installed in the flushing water pipeline (502).

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