Urea aqueous solution aeration hydrolysis ammonia gas generation system for low-temperature denitration

Abstract

The utility model relates to the technical field of ammonia gas preparation, in particular to a urea aqueous solution aeration hydrolysis ammonia gas generation system for low-temperature denitration. The urea aqueous solution aeration hydrolysis ammonia gas generation system for low-temperature denitration comprises a saturated urea aqueous solution preparation device, an aeration hydrolysis chamber, a denitration reaction device, a smoke inlet pipeline and a smoke exhaust pipeline, and a liquid outlet of the saturated urea aqueous solution preparation device is connected with the aeration hydrolysis chamber through a conveying pipe. An aeration assembly is arranged on the inner bottom wall of the aeration hydrolysis chamber, the smoke inlet pipeline is connected with the aeration assembly, a smoke outlet is formed in the upper part of the aeration hydrolysis chamber, and the smoke outlet pipeline is respectively connected with the smoke outlet and the denitration reaction device. The system has the advantages that the system is reasonable in design, the flue gas is detonated in the urea aqueous solution in an aeration mode, so that the urea aqueous solution obtains enough heat and is instantly hydrolyzed to generate ammonia gas, the whole production and preparation process is safe, high-quality heat energy is not needed, and the system is economical and applicable.

Description

Technical Field

[0001] The utility model relates to the technical field of ammonia preparation, in particular to a urea aqueous solution aeration hydrolysis ammonia generation system for low-temperature denitration. Background Art

[0002] The molecular formula of ammonia is NH3. Nitrogen-containing inorganic salts and organic intermediates, sulfonamide drugs, polyurethane, polyamide fiber and nitrile rubber all require ammonia as raw materials. It is widely used in chemical industry, light industry, fertilizer, pharmaceutical, synthetic fiber and other fields. Ammonia is also a reducing agent in the denitrification process.

[0003] Ammonia is a colorless gas with a strong pungent odor. Its density is less than that of air under standard conditions. It is easy to liquefy. When cooled to -33.5℃ at normal pressure or pressurized to 700-800kPa at room temperature, gaseous ammonia liquefies into a colorless liquid. It is an alkaline substance that is easily soluble in water. Ammonia is flammable in the air, but it is generally difficult to ignite. It can burn if it is in continuous contact with a fire source and can burn above 651℃. When the concentration of ammonia and air mixture is 16%-25%, it will burn and explode when it encounters an open flame. If there is grease or other flammable substances, it is more likely to ignite. Ammonia has a strong corrosive effect on human physiological tissues and is highly irritating and corrosive to the skin and respiratory organs. High concentrations of ammonia splashed into the eyes can cause visual impairment and disability. The human body's limit of ammonia tolerance is 50ppm. When a person inhales air containing an ammonia concentration of more than 0.5% (5000ppm), it will cause pulmonary edema within a few minutes, and even respiratory arrest and suffocation. According to the National Occupational Health Standard (GBZ2-2002), the permissible concentration of ammonia for short-term contact in the workplace is 30 mg / Nm 3 , the time-weighted average permissible concentration is 20 mg / Nm 3 .

[0004] Ammonia is an indispensable reducing agent in the tail gas denitrification process of various thermal power plants, steel mills, various kilns, etc.

[0005] Currently, most thermal power plants, steel mills and kilns use high-temperature denitrification technology, and the source of ammonia is mainly liquid ammonia, ammonia solution or urea solution directly sprayed into the boiler. There are certain safety hazards in obtaining ammonia using liquid ammonia or ammonia solution, and spraying urea solution into the furnace will waste a lot of high-quality heat energy, and there will be certain residues when urea is thermally decomposed, which will have a certain impact on the internal structure of the boiler.

[0006] Based on this, it is necessary to develop a safe and economical ammonia preparation technology. Utility Model Content

[0007] The technical problem to be solved by the utility model is to provide a system for generating ammonia by aeration and hydrolysis of urea aqueous solution for low-temperature denitration, which effectively overcomes the defects of the prior art.

[0008] The technical solution of the utility model to solve the above technical problems is as follows:

[0009] A urea aqueous solution aeration and hydrolysis ammonia generation system for low-temperature denitration comprises a saturated urea aqueous solution preparation device, an aeration and hydrolysis chamber, a denitration reaction device, a smoke inlet pipeline and a smoke exhaust pipeline. The liquid outlet of the saturated urea aqueous solution preparation device is connected to the aeration and hydrolysis chamber through a conveying pipe. An aeration component is provided on the bottom wall of the aeration and hydrolysis chamber. The smoke inlet pipeline is connected to the aeration component. A smoke exhaust port is provided on the upper part of the aeration and hydrolysis chamber. The smoke exhaust pipeline is respectively connected to the smoke exhaust port and the denitration reaction device.

[0010] On the basis of the above technical solution, the present invention can also be improved as follows.

[0011] Furthermore, the saturated urea aqueous solution preparation device includes a tank body, a stirring mechanism and a heating unit. The top of the tank body is provided with a feeding port that can be opened or closed, the lower part of the side wall of the tank body is provided with a drain port, the drain port is connected to the delivery pipe, the inside of the tank body is provided with a stirring mechanism connected to the top thereof, and the bottom wall of the tank body is provided with the heating unit.

[0012] Furthermore, the stirring mechanism includes a stirring shaft and stirring blades arranged on the stirring shaft. The stirring shaft is arranged vertically, and its upper end passes through the top middle area of ​​the tank body and is rotatably connected to the top of the tank body. A rotation drive device is provided on the top of the tank body, and the rotation drive device is connected to the upper end of the stirring shaft.

[0013] Furthermore, a heat-insulating layer is provided outside the tank body.

[0014] Furthermore, a liquid pump is provided on the delivery pipe.

[0015] Furthermore, the smoke exhaust pipeline is provided with a gas pressurizing and conveying device and a flow regulating valve.

[0016] Furthermore, the gas pressurizing and conveying device is a fan.

[0017] Furthermore, a smoke conveying device is provided on the above-mentioned smoke inlet pipeline.

[0018] Furthermore, the above-mentioned smoke conveying device is a fan.

[0019] Furthermore, the smoke exhaust port is connected to an ammonia drying device.

[0020] The beneficial effects of the utility model are: the system is reasonably designed, and the flue gas is detonated in the urea aqueous solution by aeration, so that the urea aqueous solution obtains sufficient heat to instantly hydrolyze and produce ammonia. The entire production and preparation process is relatively safe, does not require the participation of high-quality thermal energy, and is economical and applicable. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the urea aqueous solution atomization hydrolysis ammonia generation system for low-temperature denitration of the utility model;

[0022] Figure 2 It is a structural schematic diagram of another embodiment of the urea aqueous solution atomization hydrolysis ammonia generation system for low-temperature denitrification of the utility model.

[0023] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0024] 1. Saturated urea aqueous solution preparation device; 2. Aeration and hydrolysis chamber; 3. Denitrification reaction device; 4. Smoke inlet pipeline; 5. Smoke exhaust pipeline; 6. Delivery pipe; 7. Aeration component; 8. Gas booster delivery device; 9. Flow regulating valve; 10. Smoke delivery device; 11. Tank body; 12. Stirring mechanism; 13. Heating unit; 61. Liquid pump; 121. Stirring shaft; 122. Stirring blades; 123. Rotary drive device; 201. Ammonia drying device. DETAILED DESCRIPTION

[0025] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0026] Example: Figure 1 As shown, the aeration and hydrolysis ammonia generation system of urea aqueous solution for low-temperature denitration of this embodiment includes a saturated urea aqueous solution preparation device 1, an aeration and hydrolysis chamber 2, a denitration reaction device 3, a smoke inlet pipeline 4 and a smoke exhaust pipeline 5. The liquid outlet of the saturated urea aqueous solution preparation device 1 is connected to the aeration and hydrolysis chamber 2 through a delivery pipe 6, an aeration component 7 is provided on the inner bottom wall of the aeration and hydrolysis chamber 2, the smoke inlet pipeline 4 is connected to the aeration component 7, a smoke exhaust port is provided on the upper part of the aeration and hydrolysis chamber 2, and the smoke exhaust pipeline 5 is respectively connected to the smoke exhaust port and the denitration reaction device 3.

[0027] This embodiment utilizes the characteristics that urea is easily soluble in water and can be rapidly hydrolyzed at 120°C. It is a very safe and convenient ammonia generating device. The reaction principle is as follows:

[0028] CO(NH2)2+H2O=2NH3↑+CO2↑

[0029] Specifically, the waste heat of flue gas (about 170°C) discharged from equipment such as boilers / kilns is used to maintain the temperature as a whole, that is, the heat for hydrolysis of urea aqueous solution can be the flue gas of boilers / kilns, and the 170°C flue gas is pressed into the aeration hydrolysis chamber 2 by a high-pressure fan, and the flue gas is detonated and transported into the urea aqueous solution through the aeration component 7 (the aeration component 7 is located below the liquid level of the urea aqueous solution in the aeration hydrolysis chamber 2), so that the flue gas and the urea aqueous solution are fully mixed to obtain sufficient heat to instantly hydrolyze and produce ammonia. The generated ammonia is discharged through the exhaust port, and then transported to the denitration reaction device 3 through the exhaust pipeline 5 for weakening, and finally the required ammonia is produced. The system is reasonably designed, and the flue gas is detonated in the urea aqueous solution by aeration, so that the urea aqueous solution obtains sufficient heat to instantly hydrolyze and produce ammonia. The entire production and preparation process does not require the participation of high-quality thermal energy, and it is a relatively safe, economical and practical way to obtain ammonia.

[0030] In this embodiment, the front-end urea aqueous solution is prepared in the saturated urea aqueous solution preparation device 1, and is introduced into the aeration hydrolysis chamber 2 after preparation.

[0031] In this embodiment, an ammonia storage tank may be connected to the end of the smoke exhaust pipeline 5 , that is, the ammonia enters the ammonia storage tank for buffering after passing through the denitration reaction device 3 .

[0032] As a preferred embodiment, the saturated urea aqueous solution preparation device 1 includes a tank body 11, a stirring mechanism 12 and a heating unit 13. The top of the tank body 11 is provided with a feeding port that can be opened or closed, the lower part of the side wall of the tank body 11 is provided with a drain port, and the drain port is connected to the delivery pipe 6. The inside of the tank body 11 is provided with a stirring mechanism 12 connected to the top thereof, and the bottom wall of the tank body 11 is provided with the heating unit 13.

[0033] In the above embodiment, raw materials such as urea are put into the feeding port on the top of the tank body 11, and a proper amount of water is added, and then the heating unit 13 is started to heat the aqueous solution in the tank body 11. At the same time, the aqueous solution is stirred by the stirring mechanism 12 so that the urea is fully dissolved in the water. Finally, a saturated urea aqueous solution at about 90° C. is generated in the tank body 11, and then sent to the aeration hydrolysis chamber 2 through the delivery pipe 6. The detonation of the flue gas in the urea aqueous solution creates the hydrolysis conditions of the urea aqueous solution, thereby hydrolyzing and producing a large amount of ammonia. The overall structural design is simple and reasonable, and the operation is relatively convenient.

[0034] In this embodiment, the heating unit 13 can be an electric heating wire (tube) embedded in the bottom wall of the tank body 11 , or an electric heating tube directly disposed in the tank body 11 .

[0035] In this embodiment, the aeration assembly 7 can be an existing conventional aeration pipeline, one end of which passes through the lower part of the side wall of the tank body 11 and is connected to the smoke inlet pipeline 4 .

[0036] As a preferred embodiment, the stirring mechanism 12 includes a stirring shaft 121 and a stirring blade 122 arranged on the stirring shaft 121. The stirring shaft 121 is vertically arranged, and its upper end passes through the top middle area of ​​the tank body 11 and is rotatably connected to the top of the tank body 11. A rotating drive device 123 is provided on the top of the tank body 11, and the rotating drive device 123 is connected to the upper end of the stirring shaft 121.

[0037] In the above embodiment, the rotary drive device 123 drives the stirring shaft 121 to rotate, and drives the stirring blades 122 to rotate, so that the water in the tank body 11 can be stirred and flowed, so that urea can be more easily and fully dissolved in the water body.

[0038] In this embodiment, a heat preservation layer is provided outside the tank body 11, and heat loss is reduced by designing the heat preservation layer. The heat preservation layer can be made of conventional heat preservation cotton.

[0039] As a preferred embodiment, a liquid pump 61 is provided on the delivery pipe 6 .

[0040] In the above embodiment, the liquid pump 61 is used to promote the flow of fluid in the delivery pipe 6 , so that the urea aqueous solution prepared by the saturated urea aqueous solution preparation device 1 is smoothly delivered into the aeration and hydrolysis chamber 2 .

[0041] As a preferred embodiment, the smoke exhaust pipeline 5 is provided with a gas pressurizing and conveying device 8 and a flow regulating valve 9 .

[0042] In the above embodiment, the amount of ammonia is accurately controlled by the gas booster delivery device 8 and the flow control valve 9. The design pressure of the whole device can be controlled within 0.2 MPa, and there is no safety hazard.

[0043] In this embodiment, the gas pressurizing and conveying device 8 can be a fan of an existing compatible model on the market. The specific selection is based on actual needs and will not be elaborated here.

[0044] As a preferred embodiment, a smoke conveying device 10 is provided on the smoke inlet pipeline 4 .

[0045] In the above embodiment, the smoke conveying device 10 can ensure that the smoke can smoothly enter the aeration and hydrolysis chamber 2 .

[0046] In this embodiment, the above-mentioned smoke conveying device 10 can adopt the existing high-temperature resistant fan on the market. The specific model is flexibly adapted according to actual needs and will not be described in detail here.

[0047] As a preferred embodiment, Figure 2 As shown, the smoke exhaust port is connected to an ammonia drying device 201.

[0048] In the above embodiment, the moisture content in the ammonia is reduced by installing an ammonia drying device 201 at the smoke exhaust port.

[0049] In this embodiment, the ammonia drying device 201 can be a box filled with a desiccant, and the ammonia gas can pass through the box. The desiccant should be an alkaline desiccant such as soda lime.

[0050] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0051] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0052] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0053] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0054] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0055] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A system for generating ammonia by aeration and hydrolysis of urea aqueous solution for low-temperature denitration, characterized in that: The invention comprises a saturated urea aqueous solution preparation device (1), an aeration and hydrolysis chamber (2), a denitration reaction device (3), a smoke inlet pipeline (4) and a smoke exhaust pipeline (5); the liquid outlet of the saturated urea aqueous solution preparation device (1) is connected to the aeration and hydrolysis chamber (2) via a delivery pipe (6); an aeration component (7) is provided on the inner bottom wall of the aeration and hydrolysis chamber (2); the smoke inlet pipeline (4) is connected to the aeration component (7); a smoke exhaust port is provided at the top of the aeration and hydrolysis chamber (2); and the smoke exhaust pipeline (5) is respectively connected to the smoke exhaust port and the denitration reaction device (3).

2. The low-temperature denitrification urea aqueous solution aeration hydrolysis ammonia generation system according to claim 1, characterized in that: The saturated urea aqueous solution preparation device (1) comprises a tank body (11), a stirring mechanism (12) and a heating unit (13); the top of the tank body (11) is provided with a feeding port which can be opened or closed; the lower part of the side wall of the tank body (11) is provided with a liquid discharge port, the liquid discharge port is connected to the delivery pipe (6); the inside of the tank body (11) is provided with the stirring mechanism (12) connected to the top thereof; the bottom wall of the tank body (11) is provided with the heating unit (13).

3. A low-temperature denitrification urea aqueous solution aeration hydrolysis ammonia generation system according to claim 2, characterized in that: The stirring mechanism (12) comprises a stirring shaft (121) and a stirring blade (122) arranged on the stirring shaft (121); the stirring shaft (121) is arranged vertically, and its upper end passes through the middle area of ​​the top of the tank body (11) and is rotatably connected to the top of the tank body (11); a rotating drive device (123) is provided on the top of the tank body (11), and the rotating drive device (123) is connected to the upper end of the stirring shaft (121).

4. The low-temperature denitrification urea aqueous solution aeration hydrolysis ammonia generation system according to claim 2, characterized in that: The tank body (11) is provided with a heat-insulating layer outside.

5. The low-temperature denitrification urea aqueous solution aeration hydrolysis ammonia generation system according to claim 1, characterized in that: The delivery pipe (6) is provided with a liquid pump (61).

6. The low-temperature denitrification urea aqueous solution aeration hydrolysis ammonia generation system according to claim 1, characterized in that: The smoke exhaust pipeline (5) is provided with a gas pressurizing and conveying device (8) and a flow regulating valve (9).

7. A system for generating ammonia by aeration and hydrolysis of urea aqueous solution for low-temperature denitration according to claim 6, characterized in that: The gas pressurizing and conveying device (8) is a fan.

8. The low-temperature denitrification urea aqueous solution aeration hydrolysis ammonia generation system according to claim 1, characterized in that: The smoke inlet pipeline (4) is provided with a smoke conveying device (10).

9. The low-temperature denitrification urea aqueous solution aeration hydrolysis ammonia generation system according to claim 8, characterized in that: The smoke conveying device (10) is a fan.

10. A system for generating ammonia by aeration and hydrolysis of urea aqueous solution for low-temperature denitrification according to any one of claims 1 to 9, characterized in that: The smoke exhaust port is connected to an ammonia drying device (201).

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