Aluminum oxide clinker kiln denitration urea pyrolysis system

Abstract

The invention belongs to the technical field of metallurgical environmental protection, and relates to an alumina clinker kiln denitration urea pyrolysis system, which comprises: a dissolving assembly for dissolving deionized hot water and urea particles; the mixing assembly is used for mixing the urea solution and the qualified slurry; the mixing assembly is connected with the dissolving assembly; the reaction assembly is used for providing a reaction place; the reaction assembly is connected with the mixing assembly; the denitration assembly is used for denitration; the denitration assembly is connected with the reaction assembly. According to the denitration urea pyrolysis system for the alumina clinker kiln, ammonia escape can be effectively reduced, the denitration efficiency is improved, the system is easy to maintain, the crystallization problem of an SCR denitration pyrolysis furnace is avoided, and meanwhile pyrolysis energy consumption can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgical environmental protection, and in particular to a denitrification urea pyrolysis system for an alumina clinker kiln. Background Art

[0002] The alumina clinker rotary kiln adopts a wet process, where the circulating mother liquor, aluminum ore, soda ash, limestone ore (or lime) and white coal are mixed and ground into raw material slurry, and after multiple index adjustments, the raw material slurry is atomized into a rotary kiln using a high-pressure pump spray gun. The dried material is sequentially fired into clinker in the preheating zone, decomposition zone, burning zone and cooling zone at the end of the kiln, and then cooled and recovered by a single-drum cooler or a grate cooler to obtain qualified clinker. The rotary kiln uses pulverized coal as fuel. The hot air from the combustion of pulverized coal at the head of the kiln is discharged after the cyclone dust collection, electric dust collection and SCR denitrification (a denitrification process) at the end of the kiln under the suction of the exhaust fan at the end of the kiln. The temperature of the exhaust gas is about 170-200 degrees, and the concentration of nitrogen oxides is below 100mg / Nm3.

[0003] The reducing agents used in SCR denitrification are usually liquid ammonia, urea and ammonia water. The advantage of using liquid ammonia as a reducing agent is that the amount of reducing agent is small. The disadvantage is that liquid ammonia is a hazardous chemical, flammable and explosive, with poor safety, strict requirements on storage sites, and is restricted by many factors; the advantage of using ammonia water as a reducing agent is high safety, low cost, simple control, etc. The disadvantage is that the concentration of ammonia solution is usually only 15-25%. Compared with liquid ammonia, the transportation volume is large and the storage tank is large, which is more suitable for small and medium-sized boilers and kilns; the biggest advantage of using urea as a reducing agent is high safety and convenient storage. The disadvantage is high operating cost, because urea needs to be pyrolyzed or hydrolyzed into ammonia gas, and the preparation of urea solution is cumbersome. The urea solution pipeline needs to be heated, which consumes a lot of energy, and urea is very easy to crystallize, often blocking the pipeline, and operation and maintenance are relatively troublesome.

[0004] In the industry, the SCR denitrification of alumina clinker kilns all adopts the urea pyrolysis process. Urea particles are dissolved in deionized hot water to form a urea solution of about 40%, which is pumped into the pyrolysis furnace by a high-pressure pump and pyrolyzed into NH3 and CO2 under the action of hot air at about 500 degrees. The resulting mixed gas enters the flue through the ammonia injection grid, and after mixing with the flue gas, enters the SCR reactor for denitrification reaction. After heat exchange with the flue gas, the air temperature can be increased to 170-200 degrees, and then heated to 500-600 degrees by electric heating. According to statistics, for a clinker kiln with a daily output of 1,150 tons, the monthly power consumption of denitrification electric heating is about 210,000 degrees, which is a large power consumption, so it needs to be improved. Summary of the invention

[0005] In view of this, the present invention provides an alumina clinker kiln denitrification urea pyrolysis system.

[0006] Specifically, the present invention is achieved through the following technical solutions:

[0007] According to a first aspect of the present invention, there is provided an alumina clinker kiln denitrification urea pyrolysis system, comprising:

[0008] Dissolution component, used for dissolution of deionized hot water and urea granules;

[0009] A mixing component, used for mixing urea solution and qualified slurry; the mixing component is connected to the dissolving component;

[0010] A reaction component, used to provide a reaction site; the reaction component is connected to the mixing component;

[0011] A denitration component is used for denitration; the denitration component is connected to the reaction component.

[0012] Optionally, the dissolution component includes: a dissolution tank, and the dissolution tank is connected to deionized hot water and steam.

[0013] Optionally, the dissolution component further includes: a hoist connected to the dissolution tank.

[0014] Optionally, the dissolution component further comprises: a solution storage tank, the solution storage tank is connected to the dissolution tank, and the solution storage tank is connected to steam.

[0015] Optionally, the dissolution component further comprises: a vertical pump, wherein the vertical pump is respectively connected to the solution storage tank and the mixing component.

[0016] Optionally, the mixing component includes: a slurry tank, which is connected to a vertical pump in the dissolving component.

[0017] Optionally, the mixing assembly further comprises: a Warman pump, wherein the Warman pump is respectively connected to the slurry tank and the reaction assembly.

[0018] Optionally, the reaction component comprises: a rotary kiln and an exhaust fan, wherein the rotary kiln is connected to the Warman pump in the mixing component and the exhaust fan respectively.

[0019] Optionally, the reaction component further includes: an electrical dust collecting chamber, and the electrical dust collecting chamber is connected to the exhaust fan and the denitration component respectively.

[0020] Optionally, the denitration component includes: a denitration reactor, and the denitration reactor is connected to the electrical dust collector in the reaction component.

[0021] The technical solution provided by the present invention brings at least the following beneficial effects:

[0022] The alumina clinker kiln denitrification urea pyrolysis system provided in the present application can effectively reduce ammonia escape, improve denitrification efficiency, and the system maintenance is simple, there is no SCR denitrification pyrolysis furnace crystallization problem, and at the same time it can reduce pyrolysis energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0025] Figure 1 A schematic structural diagram of a denitrification urea pyrolysis system for an alumina clinker kiln provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. 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.

[0027] Figure 1 A denitrification urea pyrolysis system for an alumina clinker kiln applicable to an embodiment of the present invention is schematically shown.

[0028] Reference Figure 1 As shown, the present application provides an alumina clinker kiln denitrification urea pyrolysis system, comprising:

[0029] Dissolution component, used for dissolution of deionized hot water and urea granules;

[0030] A mixing component, used for mixing urea solution and qualified slurry; the mixing component is connected to the dissolving component;

[0031] A reaction component, used to provide a reaction site; the reaction component is connected to the mixing component;

[0032] A denitration component is used for denitration; the denitration component is connected to the reaction component.

[0033] In an embodiment of the present application, deionized hot water and urea particles are dissolved in a dissolving component to obtain a urea solution, the urea solution and qualified slurry are mixed in a mixing component, and then the mixed solution enters a reaction component for reaction, and then enters a denitrification component for denitrification operation.

[0034] Exemplarily, the dissolution component includes: a dissolution tank, which is connected to deionized hot water and steam.

[0035] In the embodiment of the present application, deionized hot water is connected to the dissolution tank to dissolve the urea granules, and the steam can increase the temperature to accelerate the dissolution of the urea granules by the deionized hot water.

[0036] Exemplarily, the dissolution component further includes: a hoist connected to the dissolution tank.

[0037] In the embodiment of the present application, the elevator is used to transport urea granules to the dissolution tank.

[0038] Exemplarily, the dissolution component further includes: a solution storage tank, which is connected to the dissolution tank and is connected to steam.

[0039] In the embodiment of the present application, the solution storage tank is used to receive the urea solution obtained from the dissolution tank, and the steam is used to keep the urea solution warm to prevent urea from precipitating out of the urea solution.

[0040] Exemplarily, the dissolution component further includes: a vertical pump, which is connected to the solution storage tank and the mixing component respectively.

[0041] In the embodiment of the present application, the vertical pump is used to transport the urea solution in the solution storage tank to the mixing assembly.

[0042] Exemplarily, the mixing component includes: a slurry tank connected to a vertical pump in the dissolving component.

[0043] In the embodiment of the present application, the slurry tank is used to receive qualified slurry delivered from the outside and urea solution delivered by the vertical pump, and mix the qualified slurry and the urea solution.

[0044] Exemplarily, the mixing assembly further comprises: a Warman pump, wherein the Warman pump is respectively connected to the slurry tank and the reaction assembly.

[0045] In an embodiment of the present application, a Warman pump is used to transport the mixed solution in the slurry tank to the reaction component.

[0046] Exemplarily, the reaction component comprises: a rotary kiln and an exhaust fan, wherein the rotary kiln is connected to the Warman pump in the mixing component and the exhaust fan respectively.

[0047] In the embodiment of the present application, the rotary kiln is used to receive the mixed solution delivered by the Warman pump and react, and to deliver the clinker obtained after the reaction, and the exhaust fan is used to discharge the gas generated by the reaction.

[0048] Exemplarily, the reaction component further includes: an electrical dust collecting chamber, and the electrical dust collecting chamber is connected to the exhaust fan and the denitration component respectively.

[0049] In the embodiment of the present application, the electrical dust collecting chamber is used to detect dust in the gas exhausted by the exhaust fan using electrical technology and transport it to the denitrification component.

[0050] Exemplarily, the denitration component includes: a denitration reactor, and the denitration reactor is connected to the electrical dust collector in the reaction component.

[0051] In the embodiment of the present application, the denitration component is used to receive the dust transported from the electric dust collecting chamber and perform denitration operations.

[0052] In this application, urea granules are transported to the dissolution tank by an elevator and dissolved with deionized hot water, then stored in the solution storage tank, and then sent to the slurry tank by a vertical pump to mix with qualified slurry, and then sent to the rotary kiln by a Warman pump for reaction. After the urea solution is pyrolyzed in the rotary kiln, it is mixed with the flue gas in the kiln and scattered by the exhaust fan, and then enters the denitrification reactor through the electrical dust collection chamber for denitrification, and finally the flue gas is discharged after meeting the standards.

[0053] In this application, the specification of the slurry tank is θ6*8m, with a built-in stirring device; the outlet pressure of the Warman pump is 1.6MPa~2.0MPa; the kiln tail of the rotary kiln is 10~15m away from the slurry entry position to the kiln head, and the flue gas temperature is 230~600 degrees.

[0054] In this application, the urea solution is pumped into the slurry tank by a vertical pump, mixed evenly with the qualified slurry in the tank, and then pumped into the rotary kiln by a Warman pump. Under the action of 800-1000 degrees hot air from the kiln head, the slurry mixture mixed with urea solution is dried, and the flue gas temperature is reduced to about 230 degrees. Most of the urea is pyrolyzed and converted into NH3 and CO2. Some unpyrolyzed urea is wrapped by the slurry and falls to the bottom of the kiln. It moves to the kiln head side with the material. As the temperature rises, it continues to be pyrolyzed into NH3 and CO2, accompanied by SNCR reaction (selective non-catalytic reduction), reducing NOX to N2 in the kiln. Most of the pyrolyzed NH3 enters the denitrification reactor with the flue gas to undergo SCR denitrification reaction, reducing NOX in the flue gas to N2 and meeting environmental emission standards. The NH3 gas produced by pyrolysis in the kiln is mixed with the NOX produced by combustion at the kiln head at the kiln tail, and is scattered and stirred by the impeller of the exhaust fan at the kiln tail. Then, it is distributed at the inlet of the electrical dust collector and the mixed flue gas is fully homogenized after entering the denitrification reactor through the action of the homogenization plate, which is beneficial to improve the denitrification efficiency and reduce ammonia escape. At the same time, the heat of the flue gas of the large kiln itself is fully utilized to pyrolyze the urea solution. There is no need to set up electric heating and dilution fans, which can greatly reduce costs.

[0055] The alumina clinker kiln denitrification urea pyrolysis system provided in the present application can effectively reduce ammonia escape, improve denitrification efficiency, and the system maintenance is simple, there is no SCR denitrification pyrolysis furnace crystallization problem, and at the same time it can reduce pyrolysis energy consumption.

[0056] It should be noted that, in the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0057] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0058] In addition, the terms "installed", "set", "provided with", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0059] In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise specified, "plurality" means two or more.

[0060] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. An alumina clinker kiln denitrification urea pyrolysis system, characterized in that: include: Dissolution component, used for dissolution of deionized hot water and urea granules; A mixing assembly, used to mix urea solution and qualified slurry; The mixing component is connected to the dissolving component; A reaction component, used to provide a reaction site; the reaction component is connected to the mixing component; A denitration component is used for denitration; the denitration component is connected to the reaction component.

2. The alumina clinker kiln denitrification urea pyrolysis system according to claim 1, characterized in that: The dissolution component comprises a dissolution tank, and the dissolution tank is connected to deionized hot water and steam.

3. The alumina clinker kiln denitrification urea pyrolysis system according to claim 2, characterized in that: The dissolving component further comprises: a hoist connected to the dissolving tank.

4. The alumina clinker kiln denitrification urea pyrolysis system according to claim 2, characterized in that: The dissolving component further comprises: a solution storage tank, which is connected to the dissolving tank and is connected to steam.

5. The alumina clinker kiln denitrification urea pyrolysis system according to claim 4, characterized in that: The dissolving component further comprises: a vertical pump, and the vertical pump is connected to the solution storage tank and the mixing component respectively.

6. The alumina clinker kiln denitrification urea pyrolysis system according to claim 1, characterized in that: The mixing component comprises: a slurry tank, and the slurry tank is connected to the vertical pump in the dissolving component.

7. The alumina clinker kiln denitrification urea pyrolysis system according to claim 6, characterized in that: The mixing component further comprises: a Warman pump, wherein the Warman pump is respectively connected to the slurry tank and the reaction component.

8. The alumina clinker kiln denitrification urea pyrolysis system according to claim 1, characterized in that: The reaction assembly comprises: a rotary kiln and an exhaust fan, wherein the rotary kiln is connected to the Warman pump in the mixing assembly and the exhaust fan respectively.

9. The alumina clinker kiln denitrification urea pyrolysis system according to claim 8, characterized in that: The reaction component further includes: an electrical dust collecting chamber, and the electrical dust collecting chamber is connected to the exhaust fan and the denitration component respectively.

10. The alumina clinker kiln denitrification urea pyrolysis system according to claim 1, characterized in that: The denitration component comprises: a denitration reactor, and the denitration reactor is connected to the electrical dust collecting chamber in the reaction component.

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