Urea pyrolysis furnace

Abstract

The present invention discloses a urea pyrolysis furnace, comprising a furnace body, a furnace top cover, an inlet flue and an atomizer. The furnace body is arranged vertically, the cavity inside the furnace body forms a vertical main flue, and the top end surface of the furnace body is provided with a flue gas inlet, and the bottom end surface of the furnace body is provided with a flue gas outlet; the furnace top cover is installed on the top of the furnace body and blocks the flue gas inlet, and a cyclone air cavity is formed between the furnace top cover and the top end surface of the furnace body; the inlet flue is connected with the cyclone air cavity along the tangential direction, the atomizer is installed on the side wall of the furnace body, and the ammonia solution is sprayed into the main flue of the furnace body through the atomizer. It solves the technical problem of material wall adhesion or deposition caused by flue gas fluctuations in the pyrolysis furnace.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas denitration, and in particular to a urea pyrolysis furnace. Background Art

[0002] With the completion of ultra-low emission of flue gas in thermal power plants, ultra-low emission projects using SCR denitration technology have been launched in various industries such as steel sintering, glass, coking and industrial furnaces. In the denitration process, the pyrolysis furnace for urea decomposition needs to rely on a stable heat source for pyrolysis, which leads to fluctuations in the flow direction, temperature, load and other aspects of the flue gas, which will have a serious impact on the decomposition effect of urea. Summary of the invention

[0003] To this end, the present invention provides a urea pyrolysis furnace, in order to at least partially solve the technical problem of material wall adhesion or deposition caused by flue gas fluctuations in the pyrolysis furnace.

[0004] In order to achieve the above purpose, the embodiment of the present invention provides the following technical solutions:

[0005] A urea pyrolysis furnace, comprising:

[0006] A furnace body, wherein the furnace body is vertically arranged and its cavity forms a vertical main flue, and a smoke inlet is provided on the top surface of the furnace body and a smoke outlet is provided on the bottom surface of the furnace body;

[0007] A furnace top cover, which is installed on the top of the furnace body and blocks the smoke inlet, and a cyclone air cavity is formed between the furnace top cover and the top surface of the furnace body;

[0008] An inlet flue, the inlet flue being in tangential communication with the cyclone air cavity;

[0009] An atomizer is installed on the side wall of the furnace body, and ammonia solution is sprayed into the main flue of the furnace body through the atomizer.

[0010] Furthermore, it also includes:

[0011] A swirl generator is installed on the top surface of the furnace body and is located in the swirl air cavity. The air inlet end of the swirl generator is connected to the swirl air cavity, and the air outlet end is connected to the smoke inlet.

[0012] Furthermore, there are multiple smoke inlets, each of which is opened in a circular form on the top surface of the furnace body; there are multiple swirl generators, and the gas outlet end of each swirl generator is connected to each smoke inlet in a one-to-one correspondence.

[0013] Furthermore, the swirl generator comprises a drainage flue and a swirl generating chamber, and the drainage flue is tangent to the swirl generating chamber.

[0014] Furthermore, the ratio of the entrance height to the entrance width of the drainage duct is 1:2, the ratio of the diameter of the swirl generating chamber to the entrance width of the drainage duct is (2-0.4):1, and the ratio of the height of the swirl generating chamber to the entrance height of the drainage duct is (3-5):1.

[0015] Furthermore, there are a plurality of atomizers, and each of the atomizers is evenly distributed on the side wall of the furnace body in a circumferential direction.

[0016] Furthermore, it also includes a furnace bottom flue, and the smoke inlet end of the furnace bottom flue is connected to the smoke outlet of the furnace body.

[0017] Furthermore, it also includes an outlet flue, and the smoke inlet end of the outlet flue is connected to the smoke outlet end of the furnace bottom flue.

[0018] Furthermore, the furnace bottom flue is a conical flue, the large end of the conical flue forms the smoke inlet end of the furnace bottom flue, and the small end of the conical flue forms the smoke outlet end of the furnace bottom flue.

[0019] Furthermore, the furnace body is a cylindrical tower body, and the ratio of the diameter to the height of the cylindrical tower body is 1:(4-5).

[0020] The urea pyrolysis furnace provided by the present invention comprises a furnace body, a furnace top cover, an inlet flue and an atomizer. The furnace body is arranged vertically, the cavity inside the furnace body forms a vertical main flue, the top surface of the furnace body is provided with a flue gas inlet, and the bottom surface of the furnace body is provided with a flue gas outlet; the furnace top cover is installed on the top of the furnace body and blocks the flue gas inlet, and a cyclone air cavity is formed between the furnace top cover and the top surface of the furnace body; the inlet flue is connected to the cyclone air cavity along the tangential direction, the atomizer is installed on the side wall of the furnace body, and the ammonia solution is sprayed into the main flue of the furnace body through the atomizer. In this way, through the tangentially arranged inlet flue and the swirl air cavity connected to the inlet flue, the flue gas enters the furnace body after the swirl. When the inlet flue gas flow rate and the flue gas temperature fluctuate, the flue gas can still flow along the wall to form thermal protection for the furnace wall. The material leaves the furnace wall and swirls inward under the action of the airflow, ensuring that the material does not adhere to the wall. At the same time, the urea solution is atomized into fine droplets by the atomizer and then sprayed into the swirling airflow. The solution is pyrolyzed in the process of continuous evaporation of the hot flue gas, thereby strengthening the heat exchange between the solution and the flue gas and fully utilizing the heat, ensuring that the material is completely decomposed and not deposited, thereby solving the technical problem of material adhesion or deposition caused by flue gas fluctuations in the pyrolysis furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0022] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0023] Figure 1 A schematic structural diagram of a specific implementation mode of the pyrolysis furnace provided by the present invention;

[0024] Figure 2 for Figure 1 The schematic diagram of the structure of the pyrolysis furnace after removing the furnace top cover;

[0025] Figure 3 for Figure 1 Schematic diagram of the structure of the swirl generator in the pyrolysis furnace shown.

[0026] Description of reference numerals:

[0027] 101-furnace body 102-furnace top cover 103-furnace bottom flue 104-swirl generator 105-atomizer

[0028] 106-export flue 107-import flue DETAILED DESCRIPTION

[0029] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Please refer to Figure 1-Figure 2 , Figure 1 A schematic structural diagram of a specific implementation mode of the pyrolysis furnace provided by the present invention; Figure 2 for Figure 1 The schematic diagram of the structure of the pyrolysis furnace after removing the furnace top cover is shown.

[0031] In a specific embodiment, the urea pyrolysis furnace provided by the present invention includes a furnace body 101, a furnace top cover 102, an inlet flue 107 and an atomizer 105. The furnace top cover 102 and the inlet flue 107 can be an integrally formed structure, that is, the two are integrated into the same part. The furnace body 101 is vertically arranged and forms a vertical main flue with its cavity, and a flue gas inlet is provided on the top surface of the furnace body 101, and a flue gas outlet is provided on the bottom surface of the furnace body 101; the furnace body 101 is the main structure of the pyrolysis furnace, and the cavity surrounded by the barrel-shaped side wall, the top surface and the bottom surface is the place where the reaction occurs. During the reaction, the flue gas and urea material enter the cavity and are evenly mixed in the cavity. The furnace top cover 102 is installed on the top of the furnace body 101 and blocks the flue gas inlet. A cyclone air cavity is formed between the furnace top cover 102 and the top surface of the furnace body 101. The inlet flue duct 107 is connected to the cyclone air cavity along the tangent direction. Before the flue gas enters the furnace body 101, it enters the cyclone air cavity tangentially and first forms a cyclone in the cyclone air cavity, and enters the furnace body 101 in the form of a gas cyclone to avoid wall adhesion or precipitation. The atomizer 105 is installed on the side wall of the furnace body 101. The ammonia solution is sprayed into the main flue of the furnace body 101 through the atomizer 105. The ammonia solution is atomized into fine particles by the atomizer 105 and then enters the furnace body 101 so as to be fully mixed with the flue gas in the cyclone form.

[0032] Specifically, the furnace body 101 is a cylindrical tower body, and the ratio of the diameter to the height of the cylindrical tower body is 1:(4-5). The pyrolysis furnace with this diameter-to-height ratio is a tall and thin type, which can significantly save floor space while ensuring the reaction effect.

[0033] In order to improve the smoke extraction effect, the pyrolysis furnace further includes a furnace bottom flue 103 and an outlet flue 106, wherein the smoke inlet end of the furnace bottom flue 103 is connected to the smoke outlet of the furnace body 101, and the smoke inlet end of the outlet flue 106 is connected to the smoke outlet end of the furnace bottom flue 103. The furnace bottom flue 103 is a conical flue, wherein the large end of the conical flue forms the smoke inlet end of the furnace bottom flue 103, and the small end of the conical flue forms the smoke outlet end of the furnace bottom flue 103, and the taper of the furnace bottom flue 103 is between 45 and 55 degrees.

[0034] In this way, through the tangentially arranged inlet flue 107 and the cyclone air cavity connected to the inlet flue 107, the flue gas enters the furnace body 101 after the cyclone. When the inlet flue gas flow rate and the flue gas temperature fluctuate, the flue gas can still flow along the wall to form thermal protection for the furnace wall. The material leaves the furnace wall and swirls inward under the action of the airflow, ensuring that the material does not adhere to the wall. At the same time, the urea solution is atomized into fine droplets by the atomizer 105 and then sprayed into the rotating airflow. The solution is pyrolyzed in the process of continuous evaporation of the hot flue gas, thereby strengthening the heat exchange between the solution and the flue gas and fully utilizing the heat, ensuring that the material is completely decomposed and not deposited, thereby solving the technical problem of material adhesion or deposition caused by flue gas fluctuations in the pyrolysis furnace.

[0035] In the above specific embodiment, in order to improve the cyclone effect of the flue gas and further prevent the material from adhering to the wall or depositing, the pyrolysis furnace further includes a cyclone generator 104, such as Figure 3 As shown, the swirl generator 104 is installed on the top surface of the furnace body 101 and is located in the swirl air cavity. The air inlet end of the swirl generator 104 is connected to the swirl air cavity, and the air outlet end is connected to the smoke inlet.

[0036] Specifically, the swirl generator 104 includes a drainage flue and a swirl generating chamber, the drainage flue is tangent to the swirl generating chamber, and the swirl flue gas formed after the primary swirl treatment of the flue gas in the swirl air chamber of the inlet flue 107 enters the swirl generator 104 for secondary swirl, and then enters the furnace body 101 after the secondary swirl, thereby improving the swirl effect.

[0037] The ratio of the entrance height to the entrance width of the drainage flue is 1:2, the ratio of the diameter of the swirl chamber to the entrance width of the drainage flue is (2-0.4):1, and the ratio of the height of the swirl chamber to the entrance height of the drainage flue is (3-5):1. That is to say, Figure 3 As shown, the inlet of the flue gas uniform distribution swirl generator 104 is horizontally flat, the inlet flue gas flow rate is 15-20m / s, the ratio of the inlet height CH to the inlet width CW is 1:2, the ratio of the diameter CF to the inlet width CW is (2-0.4):1, and the ratio of the generator height CB to the inlet height CH is: (3-5):1.

[0038] In actual use, in order to further improve the swirl effect, there are multiple smoke inlets, each of which is opened in a circular form on the top surface of the furnace body 101; there are multiple swirl generators 104, and the gas outlet end of each swirl generator 104 is connected to each smoke inlet one by one. Specifically, each swirl generator 104 is arranged in a circular ring, and the number of arrangements is 3-5. During operation, the high-temperature smoke enters the swirl air cavity tangentially through the inlet flue 107, and after generating a rotating airflow in the swirl air cavity, it is evenly distributed by multiple groups of swirl generators 104. The smoke enters the swirl generator 104 tangentially again, generating multiple small swirl smokes, which flow downward into the furnace body 101. The small swirl smoke generated by multiple groups of swirl generators 104 converges into a larger swirl airflow according to the principle of gas swirl convergence. In such an airflow, the main airflow rotates in the center of the furnace body 101, and a small part of the airflow rotates on the wall of the furnace body 101.

[0039] There are multiple atomizers 105, each of which is evenly distributed on the side wall of the furnace body 101. The atomizer 105 is specifically a dual-fluid atomizer 105, each of which is installed within a range of 0.8-1.2m below the upper end surface of the furnace body 101, and the atomized particle size of the droplets is controlled to be 15-30um.

[0040] During operation, the high-temperature flue gas enters the cyclone cavity tangentially through the inlet flue 107, and after generating a rotating airflow in the cyclone cavity, it is evenly distributed by multiple groups of cyclone generators 104. The flue gas enters the cyclone generator 104 tangentially again, generating multiple small cyclone flue gases, which flow downward into the furnace body 101. The small cyclone flue gases generated by multiple groups of cyclone generators 104 converge into a larger rotating airflow according to the gas cyclone convergence principle. In such an airflow, the main airflow rotates in the center of the furnace body 101, and a small part of the airflow rotates on the wall of the furnace body 101. The atomizer 105 atomizes the urea solution into fine droplets and sprays them into the rotating airflow. The urea is pyrolyzed in the process of the solution being continuously evaporated by the hot flue gas. The generated ammonia and water vapor flow downward with the rotating airflow in the furnace body 101, and are finally tightened by the conical structure of the flue 103 at the bottom of the furnace, and flow out of the pyrolysis furnace under the guidance of the outlet flue 106. In addition, the flue gas flow field in the furnace body 101 is not affected by the direction of the flue gas at the inlet of the pyrolysis furnace. The flue gas flow field in the furnace body 101 is in a turbulent state, the heat exchange between the droplets and the flue gas is sufficient and the residence time can be as long as more than 30 seconds. The flue gas in the pyrolysis furnace is a strong rotating airflow, and no ash accumulates at the bottom and the walls are not wet.

[0041] Taking a 30MW subcritical power generation unit SCR denitrification urea pyrolysis furnace as an example, the process parameters of the pyrolysis furnace provided by the present invention are briefly described below to illustrate the above technical effects.

[0042] When the above pyrolysis furnace is applied to a 30MW subcritical power generation unit SCR denitrification urea pyrolysis furnace, a single boiler requires 150kg / hr of ammonia, and uses 4060Nm3 / hr of primary air (328℃ / 10kPa) to heat up to 600℃ through an electric heater and enter the urea pyrolysis furnace. A single boiler consumes 265kg / hr of urea solution with a mass concentration of 40-50%, which is sprayed into the urea pyrolysis furnace through 8 double-fluid atomizers. The furnace body is φ1.8×13m, and 5 groups of flue gas uniformly distributed swirl generators are arranged. The generator inlet height is 140mm, the inlet width is 300mm, the generator barrel diameter is 220mm, and the barrel height is 500mm. The system can operate stably, with an actual pyrolysis ammonia production capacity of 50-150kg / h, which is not affected by the flue gas flow rate entering the furnace, and there is no bottom wet wall, deposition and other phenomena, and the operation effect is good.

[0043] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprises a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0044] Finally, 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A urea pyrolysis furnace, characterized in that: include: A furnace body (101), the furnace body (101) being arranged vertically and forming a vertical main flue with its cavity, and a smoke inlet being provided on the top end surface of the furnace body (101), and a smoke outlet being provided on the bottom end surface of the furnace body (101); A furnace top cover (102), the furnace top cover (102) being installed on the top of the furnace body (101) and shielding the smoke inlet, a cyclone air cavity being formed between the furnace top cover (102) and the top end surface of the furnace body (101); An inlet flue (107), the inlet flue (107) being in tangential communication with the cyclone air cavity; an atomizer (105), the atomizer (105) being installed on a side wall of the furnace body (101), and the urea solution being sprayed into a main flue of the furnace body (101) through the atomizer (105); Wherein: a swirl generator (104), the swirl generator (104) is installed on the top surface of the furnace body (101) and is located in the swirl air cavity, the air inlet end of the swirl generator (104) is connected to the swirl air cavity, and the air outlet end is connected to the smoke inlet; there are multiple smoke inlets, each of which is opened in a circular form on the top surface of the furnace body (101); there are multiple swirl generators (104), and the air outlet end of each swirl generator (104) is connected to each smoke inlet in a one-to-one correspondence; the swirl generator (104) comprises a drainage flue and a swirl generating cavity, and the drainage flue is tangent to the swirl generating cavity; The high-temperature flue gas enters the cyclone air cavity tangentially through the inlet flue (107) and generates a rotating airflow in the cyclone air cavity. The high-temperature flue gas is then evenly distributed by the multiple groups of cyclone generators (104). The flue gas enters the cyclone generators (104) tangentially again to generate multiple small cyclone flue gases, which flow downward into the furnace body (101). The small cyclone flue gases generated by the multiple groups of cyclone generators (104) converge into a larger rotating airflow based on the gas cyclone convergence principle. In such an airflow, the main airflow rotates in the center of the furnace body (101), and a small part of the airflow rotates along the wall of the furnace body (101).

2. The urea pyrolysis furnace according to claim 1, characterized in that: The ratio of the entrance height to the entrance width of the drainage flue is 1:2, the ratio of the diameter of the swirl generating chamber to the entrance width of the drainage flue is (2-0.4):1, and the ratio of the height of the swirl generating chamber to the entrance height of the drainage flue is (3-5):

1.

3. The urea pyrolysis furnace according to claim 1, characterized in that: There are a plurality of atomizers (105), and each of the atomizers (105) is evenly distributed on the side wall of the furnace body (101) in the circumferential direction.

4. The urea pyrolysis furnace according to claim 1, characterized in that: It also comprises a furnace bottom flue (103), wherein a smoke inlet end of the furnace bottom flue (103) is connected to a smoke outlet of the furnace body (101).

5. The urea pyrolysis furnace according to claim 4, characterized in that: It also comprises an outlet flue (106), wherein a smoke inlet end of the outlet flue (106) is connected to a smoke outlet end of the furnace bottom flue (103).

6. The urea pyrolysis furnace according to claim 5, characterized in that: The furnace bottom flue (103) is a conical flue, the large end of the conical flue forms a smoke inlet end of the furnace bottom flue (103), and the small end of the conical flue forms a smoke outlet end of the furnace bottom flue (103).

7. The urea pyrolysis furnace according to any one of claims 1 to 6, characterized in that: The furnace body (101) is a cylindrical tower body, and the ratio of the diameter to the height of the cylindrical tower body is 1:(4-5).

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