Urea direct injection pyrolysis system of pipeline heat tracing mode

Abstract

The present application relates to flue gas denitration and pipeline heat tracing technical field, disclose a kind of pipeline heat tracing mode's urea direct injection pyrolysis system, including mixing unit, metering output unit and pipeline heat tracing unit, wherein, mixing unit, including urea solution supply line, desalted water supply line and mixed liquor supply line;Metering output unit, including several metering output pipelines and reflux pipeline, each metering output pipeline is connected with corresponding spray gun in spray gun system;Pipeline heat tracing unit, connected with urea solution supply line and metering output unit;In the present application, the concentration of urea solution is adjusted and monitored by mixing unit and metering output unit multistage, so that it reaches spray gun, the concentration remains consistent, and the pipeline of flush water unit is matched, to avoid the problem of pipeline blockage existing in pipeline system when not using or temporarily stopping using;Further, the pipeline is heated by using the recovered steam waste heat, which reduces the economic efficiency of the unit while preventing pipeline blockage.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flue gas denitration system and pipeline heat tracing, and particularly relates to a urea direct injection pyrolysis system of a pipeline heat tracing mode. BACKGROUND

[0002] Urea pyrolysis usually adopts high-temperature flue gas at the outlet of a gas turbine to be introduced into a urea pyrolysis furnace by a high-temperature fan to pyrolyze urea solution to produce ammonia; a urea hydrolysis system uses low-quality steam (0.8-1.0, 160-200 degrees) to make urea solution in the reactor hydrolyze to produce a mixed gas containing ammonia, the system is complex, and the accompanying pipeline requires high heat preservation and heat tracing, and is prone to pipeline crystallization blockage and valve corrosion. Both of the above-mentioned ammonia production technologies require a large amount of heat source, and the system operation and maintenance cost is high, which to some extent restricts the engineering application of the technology. The urea direct injection pyrolysis technology is to atomize and spray urea solution into a flue, and use high-temperature flue gas (350-600 degrees) in the flue to pyrolyze urea solution to produce a mixed gas containing ammonia for use in a downstream SCR reactor, and the system is simple and easy to operate.

[0003] The traditional urea direct injection pyrolysis system metering and distribution module adopts a skid-mounted mode, each spray gun corresponds to a set of urea solution and compressed air metering and distribution module, and it is impossible to configure flushing water to flush the urea solution pipeline of each spray gun, which is prone to urea solution pipeline blockage; after urea solution is mixed with dilution water in the distribution module, the concentration of urea solution of each spray gun cannot be determined, which is prone to uneven distribution of ammonia gas after urea solution pyrolysis in the flue on the surface of the catalyst; at the same time, the nitrogen oxide at the SCR inlet flue of the gas turbine unit is small, the urea solution consumption is small, and the urea solution distributed to each spray gun is smaller, and the currently used regulating valve cannot achieve precise regulation.

[0004] Further, in a gas turbine power plant, the urea solution tank and storage tank of the denitration system urea station usually use high-temperature and high-pressure steam of the power plant for heating, and the steam drainage temperature after heating is high, and in most cases, the drainage is directly discharged into a drainage tank or a ditch, causing waste of heat. The urea solution pipeline connected between the metering and distribution module and the injection device of the urea direct injection pyrolysis system is usually a small-diameter pipeline, and the heat tracing construction is inconvenient, and generally adopts electric heat tracing, but the heat tracing effect is poor, unstable and prone to pipeline blockage. SUMMARY

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

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

[0007] Therefore, the present application aims to provide a urea direct injection pyrolysis system in a pipeline heating mode, which aims to solve the problems of urea solution blocking the delivery pipeline, poor mixing of urea solution output by the spray gun, poor adjustment, and poor pipeline heating effect of low-concentration urea solution.

[0008] To solve the above technical problems, the present application provides the following technical solution: a urea direct injection pyrolysis system in a pipeline heating mode, which comprises 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 solution 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 solution supply pipeline and comprises a plurality of metering output pipelines and a return pipeline connected thereto, and the output end of each metering output pipeline is connected to a corresponding spray gun in the 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 scheme of the urea direct injection pyrolysis system in a pipeline heating mode, the urea solution supply pipeline comprises 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 connected in sequence 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 scheme of the urea direct injection pyrolysis system in a pipeline heating mode, the desalted water supply pipeline comprises 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 connected in sequence to the desalted water delivery pipeline.

[0011] As a preferred scheme of the urea direct injection pyrolysis system in a pipeline heating mode, the mixed solution supply pipeline comprises a mixed solution main pipeline and a mixer, a main pipeline control valve, a main pipeline pressure gauge, a main pipeline filter, and a mixed solution blowdown valve connected in sequence to the mixed solution main pipeline; and the output ends of the urea delivery pipeline and the desalted water delivery pipeline are connected to the input end of the mixed solution main pipeline.

[0012] As a preferred scheme of the urea direct injection pyrolysis system of the pipeline heat tracing mode, the input end of the metering output pipeline is connected to the mixed solution 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 comprises an output pipeline and, in sequence, a urea solution electromagnetic valve, a check valve, a gear pump, an output pipe blowdown valve, an output pipe first pressure gauge, a mass flowmeter, a manual pressure regulating valve, an output pipe second pressure gauge, a reversing valve and an output pipe filter.

[0013] As a preferred scheme of the urea direct injection pyrolysis system of the pipeline heat tracing mode, the reflux pipeline comprises a reflux pipeline and, connected to the reflux pipeline, a check valve and a reflux pipe electromagnetic valve; the input end of the reflux pipeline is connected to the output end of the reversing valve, and the output end is connected to the input end of the output pipeline.

[0014] As a preferred scheme of the urea direct injection pyrolysis system of the pipeline heat tracing mode, the steam drain pipeline comprises 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, in sequence, a temperature gauge, a check valve, a drain booster pump, a hair drier and a drain tank connected to the drain pipeline; a control ball valve is installed in each of the steam input pipeline and the drain pipeline.

[0015] As a preferred scheme of the urea direct injection pyrolysis system of the pipeline heat tracing mode, the gas heat exchange pipeline comprises a cold air pipeline connected to the input end of the hair drier, a hot air pipeline connected to the output end of the hair drier, and, in sequence, a booster fan, a temperature gauge and a pressure gauge connected to the hot air pipeline; the output end of the hot air pipeline is connected to the heat tracing layer outside the output pipeline.

[0016] As a preferred scheme of the urea direct injection pyrolysis system of the pipeline heat tracing mode, further comprising a compressed air unit comprising 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, the input end of which is connected to a demineralized water supply pipeline, and the output end of which is connected to the metering output pipeline.

[0017] As a preferred scheme of the urea direct injection pyrolysis system of the pipeline heat tracing mode, the flushing water unit comprises a flushing water main pipeline, a plurality of flushing water branch pipelines connected to the flushing water main pipeline, and a flushing water blowdown valve connected to the output end of the flushing water main pipeline; a flushing water main pipeline control valve is connected in the flushing water main pipeline; the output end of the flushing water branch pipeline is connected to the output pipeline between the check valve and the gear pump, and a flushing water electromagnetic valve is installed in the flushing water branch pipeline.

[0018] Advantages of the present application:

[0019] In the pipeline system of the present application, the concentration of urea solution is adjusted and monitored by the mixing unit and the metering output unit in multiple stages, so that it remains consistent before reaching the lance, and the pipeline of the flushing water unit is matched, thereby avoiding the problem of pipeline blockage when the pipeline system is not used or temporarily suspended. Compared with the traditional pipeline system, the distribution module is reduced, the system pipeline is simpler and more convenient, and the cooperation of the vector pump and the mass flow meter makes the control and adjustment of urea solution in the lance more rapid and accurate. Furthermore, the drain in the urea dissolving tank and the urea storage tank is utilized to heat the cold air, which is used to heat the pipeline in the metering module, thereby effectively reducing the use of electric heat tracing and improving the economic efficiency of the unit operation. After the heat recovery and utilization of the drain, the temperature is reduced, and the steam emission phenomenon of the drain tank can be eliminated. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor. Among them:

[0021] Figure 1 It is a schematic diagram of the overall pipeline frame structure of the urea direct injection pyrolysis system with pipeline heat tracing mode of the present application.

[0022] Figure 2 It is a schematic diagram of the urea solution supply pipeline structure of the urea direct injection pyrolysis system with pipeline heat tracing mode of the present application.

[0023] Figure 3 It is a schematic diagram of the desalted water supply pipeline structure of the urea direct injection pyrolysis system with pipeline heat tracing mode of the present application.

[0024] Figure 4 It is a schematic diagram of the mixed solution supply pipeline structure of the urea direct injection pyrolysis system with pipeline heat tracing mode of the present application.

[0025] Figure 5 It is a schematic diagram of the metering output unit structure of the urea direct injection pyrolysis system with pipeline heat tracing mode of the present application.

[0026] Figure 6 It is a schematic diagram of the pipeline heat tracing unit structure of the urea direct injection pyrolysis system with pipeline heat tracing mode of the present application.

[0027] Figure 7 It is a schematic diagram of the compressed air unit structure of the urea direct injection pyrolysis system with pipeline heat tracing mode of the present application.

[0028] Figure 8 The flushing water unit structure diagram of the urea direct injection pyrolysis system in the pipeline heat tracing mode of the present application.

[0029] Figure 9 The overall pipeline connection structure diagram of the urea direct injection pyrolysis system in the pipeline heat tracing mode of the present application. DETAILED DESCRIPTION

[0030] In order to make the above objectives, features and advantages of the present application more apparent, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0031] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details given herein, that the present application can be practiced with other different systems, and therefore the scope of the present application is not limited to the details given herein.

[0032] Secondly, the "one embodiment" or "embodiment" referred to herein means that the specific features, structures or characteristics can be included in at least one implementation of the present application. The "in one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an independent or selective embodiment excluding other embodiments.

[0033] Thirdly, the present application is described in detail in combination with the schematic diagram. In the detailed description of the embodiments of the present application, the cross-sectional view of the device structure is partially enlarged without the general proportion for the convenience of description, and the schematic diagram is only an example, which should not limit the scope of protection of the present application herein. In addition, the three-dimensional spatial dimensions of length, width and depth should be included in the actual manufacture.

[0034] Embodiment 1

[0035] Reference Figure 1 and 8 For the first embodiment of the present application, a urea direct injection pyrolysis system in the pipeline heat tracing mode is provided, which comprises a mixing unit 100, a metering output unit 200, a pipeline heat tracing unit 300, a flushing water unit 400 and a compressed air unit 500. The mixing unit 100 is used for mixing urea solution and desalted water to prepare a preset urea solution concentration. The metering output unit 200 is used for monitoring the urea solution concentration in the input spray gun P corresponding to each spray gun system, so as to facilitate the adjustment of the spray gun. The pipeline heat tracing unit 300 is used for heat tracing the low-concentration urea solution pipeline before the input spray gun P, so as to ensure that the urea solution will not be blocked in the metering and distribution pipeline. The compressed air unit 400 is used for cooling the spray gun pipeline and preventing the urea solution from being evaporated in the spray gun pipeline. The flushing water unit 500 is used for cleaning 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 solution supply pipeline 103 connected to the output ends of the urea solution supply pipeline 101 and the desalted water supply pipeline 102; the urea solution supply pipeline 101 provides initial urea solution, the desalted water supply pipeline 102 provides initial desalted water, and the two are mixed in the mixed solution supply pipeline 103 to dilute and prepare urea solution of a required concentration, which is output to the metering output unit 200.

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

[0038] The pipeline heat tracing 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; the steam drain pipeline 301 is used to lead out steam drain used for heating the urea dissolving tank and the storage tank, and the gas heat exchange pipeline 302 exchanges heat between cold air and the discharged steam drain to form hot air, which is introduced into the metering output pipeline 201 for pipeline heat tracing, recovers heat in the steam drain, improves energy utilization rate, and saves energy and protects the environment.

[0039] Embodiment 2

[0040] Reference Figures 2~5 and Figures 7~9 The second embodiment of the present application is different from the first embodiment in that the urea solution supply pipeline 101 includes a urea dissolving tank and a storage tank 101a, a urea conveying pipeline 101b connected to the urea dissolving tank and the storage tank 101a, and a conveying control valve 101c, a conveying filter 101d, a urea solution conveying pump 101e, a urea conveying pressure gauge 101f, a urea solution regulating valve 101g, and an electromagnetic flowmeter D connected in sequence in the urea conveying pipeline 101b; and a steam coil 101a-1 is arranged 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, and high-concentration urea solution or urea raw material is stored in the two tanks. In this embodiment, a 50% concentration urea solution is taken as an example for illustration. The urea delivery pipeline 101b is connected to the urea dissolving tank and storage tank 101a and the mixer 103b in the mixed solution supply pipeline 103, and is used to deliver 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, so as to keep the output urea pure. 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 regulate the flow of the urea solution output by 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 according to the monitoring value.

[0042] Further, 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 connected to the desalted water delivery pipeline 102b in sequence.

[0043] The desalted water is stored in the desalted water storage tank 102a. It should be noted that the storage tank is not limited to this, but can also be other types of storage methods. The desalted water delivery pipeline 102b is connected to the desalted water storage tank 102a and the mixer 103b in the mixed solution supply pipeline 103, and is used to deliver 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 driving force required for liquid pumping. The desalted water delivery pressure gauge 102e is used to monitor the pressure in the delivery pipeline. The desalted water regulating valve 102f is used to regulate the flow of the desalted water output by 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 according to the monitoring value.

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

[0045] The mixed solution main pipeline 103a is a main pipeline for supplying the mixed and diluted urea solution and is connected with each group of metering output pipelines 201. The input end of the mixed solution main pipeline 103a is connected with the output end of the urea conveying pipeline 101b and the desalted water conveying pipeline 102b respectively to receive the two kinds of medium raw materials and is merged into the mixer 103b to be mixed. In this embodiment, a two-stage mixer is adopted, 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 of the urea solution. Finally, the low-concentration urea solution required is prepared in the mixer 103b and is conveyed to the output end of the mixed solution main pipeline 103a.

[0046] The output side of the mixer 103b in the mixed solution main pipeline 103a is provided with a main pipeline control valve 103c for controlling the opening and closing of the pipeline, a main pipeline pressure gauge 103d for monitoring the pressure in the pipeline, a main pipeline filter 103e for filtering and removing impurities existing in the pipeline and a mixed solution blowdown valve 103f for discharging flushing liquid or waste mixed solution in the main pipeline. It should be noted that the main pipeline control valve 103c and the main pipeline filter 103e can be provided with multiple valves 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 solution main pipeline 103a after the output end 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 electromagnetic valve 201b, a check valve N, a gear pump 201c, an output pipeline blowdown valve 201d, an output pipeline first pressure gauge 201e, a mass flowmeter 201f, a first manual pressure regulating valve 201g, an output pipeline second pressure gauge 201h, a reversing valve 201j and an output pipeline filter 201k connected in sequence in the output pipeline 201a.

[0048] Specifically, the metering output pipeline 201 is connected with the mixed solution main pipeline 103a and the spray gun system. The output pipeline 201a is the main connecting pipeline. The urea solution electromagnetic valve 201b provided in the pipeline is used to control the opening and closing of the pipeline, and the check valve N is used to prevent the backflow of the urea solution. The gear pump 201c is used to accurately adjust the output amount of the urea solution to the spray gun P. The output pipeline blowdown valve 201d is used to discharge flushing water when the metering output pipeline 201 is cleaned. The output pipeline first pressure gauge 201e is used to monitor the pressure in the pipeline before the flow to the mass flowmeter 201f. The first manual pressure regulating valve 201g is used for further pressure regulation in the pipeline. The output pipeline second pressure gauge 201h is used to monitor the pressure in the pipeline after the pressure is regulated twice. The purpose is 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, that is, whether the flow is to the spray gun P through the output pipeline filter 201k or to the return pipeline 202.

[0049] Further, the return pipeline 202 includes a return pipeline 202a, a check valve N and a return pipeline electromagnetic valve 202b connected to the return pipeline 202a; the input end of the return pipeline 202a is connected to the output end of the switching valve 201j, and the output end is connected to the input end of the output pipeline 201a.

[0050] The return pipeline 202 is used for the circulation of the 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 pipeline 202a is used to maintain one-way flow of the urea solution in the pipeline; the return pipeline electromagnetic valve 202b is used to control the opening and closing of the return pipeline 202a.

[0051] The flushing water unit 500 includes a flushing water main pipeline 501, a plurality of flushing water branch 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; a flushing water main pipeline control valve 501a is connected in the flushing water main pipeline 501; the output end of the flushing water branch pipeline 502 is connected to the output pipeline 201a between the check valve N and the urea solution electromagnetic valve 201b, and a flushing water electromagnetic valve 502a is installed in the flushing water branch pipeline 502.

[0052] Specifically, the flushing water main pipeline 501 takes water from the desalted water storage tank 102a or the desalted water delivery pipeline 102b, controls the opening and closing 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 branch pipeline 502 takes water from the flushing water main pipeline 501 and is used for flushing operation of each metering output pipeline 201; the opening and closing of the flushing water branch pipeline 502 is controlled by the flushing water electromagnetic 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] Further, the atomizing air main pipeline 401b is sequentially connected in the direction from the input end to the output end with an atomizing air main pipeline filter 401b-1, an atomizing air main pipeline control valve 401b-2, a filter pressure reducing three-way joint for air 401b-3, an atomizing air main pipeline pressure gauge 401b-4, and an atomizing air main pipeline discharge valve 401b-5; the atomizing air branch pipeline 401c is sequentially connected in the direction from the input end to the output end with an atomizing air branch pipeline control valve 401c-1, a second manual pressure regulating valve 401c-2, an atomizing air branch pipeline pressure gauge 401c-3, an atomizing air branch pipeline float flowmeter 401c-4, an atomizing air branch pipeline filter 401c-5, and the output end of the atomizing air branch pipeline 401c is connected to the second input end of the spray gun P.

[0055] The compressed air source 401a can be in the form of a compressed air tank or supplied by a compressor, which is not limited herein; the atomizing air main pipeline 401b is connected with the compressed air source 401a to output compressed air, and the atomizing air branch pipeline 401c is connected with the atomizing air main pipeline 401b to supply compressed air to the corresponding connected spray gun P according to the requirement.

[0056] In the atomizing air main pipeline 401b, the atomizing air main pipeline filter 401b-1 is used to filter impurities in the compressed air to avoid affecting the spray gun P; the atomizing air main pipeline control valve 401b-2 is used to control the on-off of the atomizing air main pipeline 401b; the filter pressure reducing three-way joint 401b-3 is used to reduce and filter the compressed air to meet the use requirement; the atomizing air main pipeline pressure gauge 401b-4 is used to monitor the pipeline pressure in the atomizing air main pipeline 401b; and the atomizing air main pipeline exhaust valve 401b-5 is used for the exhaust pressure relief of the atomizing air main pipeline 401b.

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

[0058] Further, 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 pipeline filter 401b-1, and the pipeline is further connected with a cooling air main pipeline control valve 402a-1 and a cooling air main pipeline exhaust valve 402a-2; the output end of the cooling air branch pipeline 402b is connected to the third input end of the spray gun P, and the pipeline is sequentially connected with a cooling air branch pipeline control valve 402b-1 and a cooling air branch pipeline float flowmeter 402b-2; the cooling air branch pipeline 402b is further connected with a branch pipeline 402b-3, and the output end of the branch pipeline 402b-3 is connected to the fourth input end of the spray gun P, and the pipeline is provided with a branch pipeline control valve F.

[0059] The main cooling air duct 402a is connected to multiple branch cooling air ducts 402b. The main cooling air duct 402a draws compressed air from the compressed air source 401a or the atomizing air main duct 401b and delivers it to each branch duct. In the main cooling air duct 402a, a main cooling air exhaust valve 402a-1 controls the opening and closing of the duct. In the branch cooling air ducts 402b, a branch cooling air control valve 402b-1 controls the opening and closing of the branch cooling air ducts 402b. A branch cooling air float flow meter 402b-2 monitors the flow rate of gas in the branch cooling air ducts 402b.

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

[0061] The remaining structure is the same as that in Example 1.

[0062] In summary, the contents of Examples 1 and 2 above, and with reference to the appendix, Figures 1~9 As shown, during the operation of this pipeline system, the urea solution raw material and demineralized water are first mixed to prepare a urea solution of a predetermined concentration. 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 to pump the urea solution raw material into the mixer 103b. For the demineralized water supply pipeline 102, the demineralized water control valve 102c, the demineralized water delivery pump 102d, and the demineralized water regulating valve 102f are opened, and the demineralized water is also pumped into the mixer 103b for mixing. According to the prepared concentration, the urea solution regulating valve 101g and the demineralized water regulating valve 102f are adjusted respectively to prepare the urea solution mixture of the required concentration in the mixer 103b, and then the mixture is pumped into the 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 certain 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 Hertz, the flow rate is read by the mass flow meter 201f, the first 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 based on the changes in nitrogen oxide inlet and outlet of the flue gas inlet of the gas-fired waste heat boiler, and the Hertz value of the gear pump 201c is adjusted in real time based on the measurement value of the mass flow meter 201f to achieve precise adjustment.

[0065] When the lance P is temporarily stopped, the switching valve 201j is switched to the backflow pipe 202a direction, the backflow pipe electromagnetic valve 202b is opened, and the mixed solution circulates in the output pipe 201a and the backflow pipe 202a; when the lance P is used again, the switching valve 201j is switched to the lance input direction, and the backflow pipe electromagnetic valve 202b is closed, so that the mixed solution always flows, and problems such as deposition and blockage in the backflow pipe 202 and the backflow pipe 202a are avoided.

[0066] When the lance system is withdrawn, the urea solution electromagnetic valve 201b is closed, the flushing water main pipe control valve 301a is opened, the gear pump 201c is started to the maximum, the urea solution electromagnetic valve 201b between the pipe and the lance can be flushed, after a certain time, the switching valve 201j is switched to the backflow pipe 202a direction, the backflow pipe electromagnetic valve 202b is opened, and the output pipe blowdown valve 201d can flush the backflow pipe 202a.

[0067] Further, the control valve of each metering output unit 200 is closed, the urea solution delivery pump 101e and the urea solution regulating valve 101g in the urea solution supply pipe 101 are closed, only the desalted water supply pipe 102 is connected to the mixed solution supply pipe 103, the mixed solution blowdown valve 103f is opened, and the mixed solution supply pipe 103 can be flushed.

[0068] When the urea solution pipe system is put into use, and the lance P is started, the atomizing air pipe 401 is started at the same time, the atomizing gas main pipe control valve 401b-2 and the atomizing gas branch pipe control valve 401c-1 are opened, the manual pressure regulating valve 401c-2 is adjusted to make the gas pressure and flow within a suitable range, the compressed air enters the lance P through the atomizing gas branch pipe filter 401c-5 to atomize the urea solution into the flue; in order to prevent the urea solution in the lance pipe from being evaporated by the high-temperature flue gas in the flue, the cooling gas pipe 402 needs to be started, that is, the cooling air main pipe control valve 402a-1 and the cooling air branch pipe control valve 402b-1 are opened, so that the cooling air enters the outer ring of the urea solution pipe of the lance to cool and absorb the heat received by the urea solution in the lance, preventing the urea solution from being evaporated in the lance pipe.

[0069] When the lance P is withdrawn for maintenance, the cooling gas pipe 402 is started, and the branch pipe control valve F is opened to provide sealing air for convenient maintenance.

[0070] Example 3

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

[0072] Specifically, the steam and 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 temperature gauge W, a non-return valve N, a drain booster pump 301c, an air heater 301d and a drain tank 301e connected in sequence in the drain pipeline 301b; control ball valves Q are installed in 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 temperature gauge W and a pressure gauge Y are connected to the steam input pipeline 301a to monitor the temperature and pressure values of the steam introduced into the pipeline; the steam and drain after heating the urea dissolving tank and the storage tank 101a is led out by the drain pipeline 301b, and the temperature of the steam and drain is still high, which is pumped into the air heater 301d under the boosting action of the drain booster pump 301c to heat the cold air introduced into the air heater 301d, and the steam and drain after heat exchange is discharged into the drain tank 301e; during the process, the temperature gauge W is used to monitor the temperature of the steam and drain in the drain pipeline 301b; the control ball valves Q are used to control the on-off of the pipeline.

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

[0075] The cold air is introduced into the input end of the air heater 301d by the cold air pipeline 302a, heated in the air heater 301d to form hot air, and enters the hot air pipeline 302b, which is pumped into the heating layer outside the output pipeline 201a and the return pipeline 202a under the boosting action of the booster fan 302c. Similarly, the temperature gauge W in the pipeline is used to monitor the temperature to ensure that the temperature of the hot air can meet the requirement of the heating temperature, and the pressure gauge Y is used to monitor the pressure value in the pipeline to have the required pressure value range.

[0076] It should be noted that the above examples are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced, without departing from the spirit and scope of the technical solutions of the present application, which should be covered in the scope of the claims of the present application.

Claims

1. A urea direct injection pyrolysis system with pipeline heating, characterized in that: include, The mixing unit (100) includes a urea solution supply line (101), a demineralized water supply line (102), and a mixed liquid supply line (103) connected to the output ends of the urea solution supply line (101) and the demineralized water supply line (102). A metering output unit (200), connected to the mixed liquid supply pipeline (103), 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; and, The pipeline heat tracing unit (300) is connected to the urea solution supply pipeline (101) and the metering output unit (200), and includes a steam condensate pipeline (301) and a gas heat exchange pipeline (302) connected thereto. The metering output pipeline (201) includes an output pipeline (201a) and, in sequence, a urea solution solenoid valve (201b), a check valve (N), a gear pump (201c), an output pipeline drain valve (201d), an output pipeline first pressure gauge (201e), a mass flow meter (201f), a first manual pressure regulating valve (201g), an output pipeline second pressure gauge (201h), a reversing valve (201j), and an output pipeline filter (201k). The return pipeline (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 (201j), and its output end is connected to the input end of the output pipe (201a).

2. The urea direct injection pyrolysis system with pipeline heating method according to claim 1, characterized in that: The 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 flow meter (D) connected in sequence to the urea delivery pipeline (101b). The urea dissolving tank and storage tank (101a) are equipped with a steam coil (101a-1).

3. The urea direct injection pyrolysis system with pipeline heating method according to claim 2, characterized in that: The demineralized water supply pipeline (102) includes a demineralized water storage tank (102a), a demineralized water delivery pipeline (102b) connected to the demineralized water storage tank (102a), and a demineralized water control valve (102c), a demineralized water delivery pump (102d), a demineralized water delivery pressure gauge (102e), a demineralized water regulating valve (102f), and an electromagnetic flow meter (D) connected in sequence to the demineralized water delivery pipeline (102b).

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

5. The urea direct injection pyrolysis system with pipeline heating method according to claim 4, characterized in that: The input end of the metering output pipeline (201) is connected to the main pipeline (103a) of the mixed liquid 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).

6. The urea direct injection pyrolysis system with pipeline heating method according to claim 5, characterized in that: The steam condensate line (301) includes a steam input pipe (301a) connected to the input end of the steam coil (101a-1), a condensate line (301b) connected to the output end of the steam coil (101a-1), and a thermometer (W), a check valve (N), a condensate booster pump (301c), a heater (301d), and a condensate tank (301e) connected in sequence in the condensate line (301b). Control ball valves (Q) are installed in both the steam input pipe (301a) and the drain pipe (301b).

7. The urea direct injection pyrolysis system with pipeline heating method according to claim 6, characterized in that: The gas heat exchange pipeline (302) includes 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 thermometer (W), and a pressure gauge (Y) connected in sequence in the hot air pipeline (302b). The output end of the hot air pipeline (302b) is connected to the heat tracing layer outside the output pipeline (201a).

8. The urea direct injection pyrolysis system with pipeline heating method according to claim 7, characterized in that: It also includes, The compressed air unit (400) includes an atomizing air pipeline (401) and a cooling air pipeline (402), the output ends of which are respectively connected to the second input end and the third input end of the spray gun (P); The flushing water unit (500) has its input end connected to the demineralized water supply pipeline (102) and its output end connected to the metering output pipeline (201).

9. The urea direct injection pyrolysis system with pipeline heating according to claim 8, characterized in that: The flushing water unit (500) includes a main flushing water pipe (501), a plurality of flushing water pipes (502) connected to the main flushing water pipe (501), and a flushing water discharge valve (503) connected to the output end of the main flushing water pipe (501). The main flushing water pipe (501) is connected to a main flushing water pipe control valve (501a); The output end of the flushing water pipe (502) is connected to the output pipe (201a) between the check valve (N) and the urea solution solenoid valve (201b), and the flushing water pipe (502) is equipped with a flushing water solenoid valve (502a).

Images