Ammonia gas generating system for atomizing and hydrolyzing urea aqueous solution for low-temperature denitration

Abstract

The utility model relates to a urea aqueous solution atomizing and hydrolyzing ammonia gas generating system for low-temperature denitration, which comprises a saturated urea aqueous solution temporary storage device, an atomizing and hydrolyzing device, a denitration reaction device, a smoke inlet pipeline and a smoke exhaust pipeline, and the atomizing and hydrolyzing device comprises an atomizing chamber and an atomizing component arranged in the atomizing chamber. The atomization chamber is provided with a smoke inlet and a smoke outlet, the saturated urea water solution buffer device is connected with the atomization assembly through a conveying pipe, the smoke inlet pipeline is connected with the smoke inlet, and the smoke outlet pipeline is connected with the smoke outlet and the denitration reaction device. The system has the advantages that the system is reasonable in design, the urea aqueous solution is used for forming spray and is in direct contact with flue gas, so that the spray obtains enough heat and is instantly hydrolyzed to generate ammonia gas, the flue gas can be flexibly matched with the spray amount, the ammonia gas conversion rate is relatively high, the whole production and preparation process is relatively 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 atomization hydrolysis ammonia generation system for low-temperature denitration. Background Art

[0002] The molecular formula of ammonia is NH 3 , nitrogen-containing inorganic salts and organic intermediates, sulfonamide drugs, polyurethane, polyamide fiber and nitrile rubber all require ammonia as raw materials, and are 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 safer, more economical and applicable 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 atomizing and hydrolyzing 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 atomizing and hydrolyzing ammonia generation system for low-temperature denitration includes a saturated urea aqueous solution buffer device, an atomizing and hydrolyzing device, a denitration reaction device, a smoke inlet pipeline and a smoke exhaust pipeline. The atomizing and hydrolyzing device includes an atomizing chamber, an atomizing assembly arranged in the atomizing chamber, and the atomizing chamber has a smoke inlet and a smoke exhaust outlet. The saturated urea aqueous solution buffer device is connected to the atomizing assembly through a conveying pipe, the smoke inlet pipeline is connected to the smoke inlet, and the smoke exhaust pipeline is respectively connected to the smoke exhaust outlet 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, a liquid pump is provided on the delivery pipe.

[0012] Furthermore, the smoke exhaust pipeline is provided with a gas pressurizing and conveying device and a flow regulating valve.

[0013] Furthermore, the gas pressurizing and conveying device is a fan.

[0014] Furthermore, a smoke conveying device is provided on the above-mentioned smoke inlet pipeline.

[0015] Furthermore, the above-mentioned smoke conveying device is a fan.

[0016] Furthermore, the saturated urea aqueous solution cache device includes a cache tank and a heating unit. The cache tank is provided with a liquid inlet and a liquid outlet. The liquid outlet is connected to the delivery pipe. The heating unit is arranged on the side wall and / or bottom wall of the cache tank.

[0017] Furthermore, a horizontal partition is provided at the lower inner portion of the atomizing chamber, the smoke inlet is provided at a portion of a side wall of one side of the atomizing chamber close to one end of the partition, a through hole for upward flow of smoke is provided at the other end of the partition, the smoke exhaust port is provided at the upper portion of the side wall of one side of the atomizing chamber, and the atomizing assembly is provided below the partition.

[0018] Furthermore, the atomizing assembly includes an atomizer and a plurality of atomizing nozzles connected to the atomizer. The plurality of atomizing nozzles are installed at the lower end of the partition and are distributed at intervals between the two ends of the partition.

[0019] Furthermore, the smoke exhaust port is also connected to the smoke inlet via a branch pipe, a heating device is provided on the branch pipe, an ammonia concentration detector is provided at the smoke exhaust port, and a control valve is provided on the branch pipe.

[0020] The beneficial effects of the utility model are as follows: the system is reasonably designed, urea aqueous solution is used to form a spray, and the spray is in direct contact with the flue gas, so that the spray obtains sufficient heat to instantly hydrolyze and produce ammonia, the flue gas and the spray amount can be flexibly adapted, the ammonia conversion rate is high, the entire production and preparation process is relatively safe, and no high-quality thermal energy is required, so it 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 buffer device; 2. Atomizing hydrolysis device; 3. Denitrification reaction device; 4. Smoke inlet pipeline; 5. Smoke exhaust pipeline; 6. Gas booster delivery device; 7. Flow regulating valve; 8. Smoke delivery device; 9. Branch pipeline; 11. Delivery pipe; 12. Liquid pump; 13. Buffer tank; 14. Heating unit; 21. Atomizing chamber; 22. Atomizing assembly; 91. Heating device; 211. Partition; 221. Atomizing nozzle. 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 ammonia generation system of urea aqueous solution atomization hydrolysis for low-temperature denitrification of this embodiment includes a saturated urea aqueous solution buffer device 1, an atomization hydrolysis device 2, a denitrification reaction device 3, a smoke inlet pipeline 4 and a smoke exhaust pipeline 5. The atomization hydrolysis device 2 includes an atomization chamber 21, an atomization component 22 arranged in the atomization chamber 21, and the atomization chamber 21 has a smoke inlet and a smoke exhaust port. The saturated urea aqueous solution buffer device 1 is connected to the atomization component 22 through a conveying pipe 11, the smoke inlet pipeline 4 is connected to the smoke inlet, and the smoke exhaust pipeline 5 is respectively connected to the smoke exhaust port and the denitrification reaction device 3.

[0027] This embodiment utilizes the characteristics that urea is easily soluble in water and can be rapidly hydrolyzed at 140°C. It is a very safe and convenient ammonia generating device. The reaction principle is as follows:

[0028] CO(NH 2 ) 2 +H2 O=2NH 3 ↑+CO 2 ↑

[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 the hydrolysis of urea aqueous solution can be the flue gas of boilers / kilns, and the 170°C flue gas is pressed into the atomizing chamber 21 by a high-pressure fan, and then the prefabricated saturated urea aqueous solution stored in the saturated urea aqueous solution buffer device 1 is formed into a spray through the atomizing component 22, and the spray is fully contacted with the flue gas entering the atomizing chamber 21, and the heat of the flue gas is used to make the urea aqueous solution spray obtain enough heat to instantly hydrolyze to produce ammonia, and the generated ammonia is discharged through the exhaust port, and then transported to the denitration reaction device 3 through the exhaust pipeline 5 for denitration treatment, and finally the required ammonia is generated. The system is reasonably designed, and the urea aqueous solution is used to form a spray, and directly contact with the flue gas, so that the spray obtains enough heat to instantly hydrolyze to produce ammonia, which can make the flue gas and the spray amount flexibly adapted, the ammonia conversion rate is high, the entire production and preparation process is relatively safe, and does not require the participation of high-quality thermal energy, which is economical and applicable. It is a relatively safe, economical and practical ammonia acquisition method as a whole.

[0030] In this embodiment, a liquid pump 12 is provided on the delivery pipe 11. The liquid pump 12 promotes the flow of fluid in the delivery pipe 11, so that the urea aqueous solution in the saturated urea aqueous solution buffer device 1 is smoothly delivered to the atomizing assembly 22 and forms a spray.

[0031] As a preferred embodiment, the smoke exhaust pipeline 5 is provided with a gas pressurizing and conveying device 6 and a flow regulating valve 7 .

[0032] In the above embodiment, the amount of ammonia is accurately controlled by the gas pressurizing and conveying device 6 and the flow regulating valve 7. The design pressure of the whole device can be controlled within the safe pressure, and there is no potential safety hazard.

[0033] In this embodiment, the gas pressurizing and conveying device 6 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.

[0034] In this embodiment, a smoke conveying device 8 is provided on the smoke inlet pipeline 4. The smoke conveying device 8 can ensure that the smoke can smoothly enter the atomization chamber 21.

[0035] In this embodiment, the smoke conveying device 8 is a fan. Specifically, the smoke conveying device 8 can be a high temperature resistant fan currently available on the market, and the specific model is flexibly adapted according to actual needs, which will not be described in detail here.

[0036] As a preferred embodiment, the saturated urea aqueous solution cache device 1 includes a cache tank 13 and a heating unit 14. The cache tank 13 is provided with a liquid inlet and a liquid outlet. The liquid outlet is connected to the delivery pipe 11. The heating unit 14 is arranged on the side wall and / or bottom wall of the cache tank 13.

[0037] In the above embodiment, the prefabricated saturated urea aqueous solution is stored in the buffer tank 13, and the solution in the tank can be heated by the heating unit 14, so that the saturated urea aqueous solution is preheated to 90°C, and then a spray with a relatively high initial temperature is formed, which then contacts the flue gas. The temperatures of the two are as close as possible, which can promote the hydrolysis effect to a certain extent.

[0038] In this embodiment, the heating unit 14 is an electric heating tube or a heating wire, which is embedded in the side wall and / or bottom wall of the cache tank 13.

[0039] As a preferred embodiment, a horizontal partition 211 is provided in the lower part of the atomization chamber 21, the smoke inlet is provided at a portion of the side wall of one side of the atomization chamber 21 close to one end of the partition 211, a through hole for upward flow of smoke is provided at the other end of the partition 211, the smoke exhaust port is provided at the upper portion of the side wall of one side of the atomization chamber 21, and the atomization assembly 22 is provided below the partition 211.

[0040] In the above embodiment, the design of the partition 211 forms a flue gas flow passage at the lower part of the atomizing chamber 21. The flue gas enters through one end and then flows upward into the upper chamber through the through hole on the partition 211 at the other end, thereby preventing the flue gas from flowing directly upward after entering, thereby increasing the horizontal flow distance of the flue gas, and an atomizing assembly 22 is arranged in the horizontal flow area, so that the urea aqueous solution spray is fully in contact with the flue gas, thereby improving the hydrolysis rate.

[0041] As a preferred embodiment, the atomizing assembly 22 includes an atomizer and a plurality of atomizing nozzles 221 connected to the atomizer. The plurality of atomizing nozzles 221 are mounted on the lower end of the partition 211 and are spaced apart and distributed between the two ends of the partition 211 .

[0042] In the above embodiment, the urea aqueous solution enters the atomizer, forms a spray, and is sprayed out through multiple atomizing nozzles 221. Since the multiple atomizing nozzles 221 are arranged between the two ends of the lower end of the partition 211, they are just adapted to the flow trajectory of the incoming flue gas, thereby further allowing the flue gas to fully contact with the spray, further improving the conversion rate (or conversion effect) of the ammonia produced by hydrolysis.

[0043] As a preferred embodiment, Figure 2As shown, the smoke exhaust port is also connected to the smoke inlet via a branch pipe 9 , a heating device 91 is provided on the branch pipe 9 , an ammonia concentration detector is provided at the smoke exhaust port, and a control valve is provided on the branch pipe 9 .

[0044] In the above embodiment, after ammonia is generated in the atomizing chamber 21, it is discharged through the smoke exhaust port. When passing through the smoke exhaust port, the ammonia concentration is detected by the ammonia concentration detector (the existing sensor can be used, and the adaptation model can be flexibly selected according to actual needs, which will not be described here). If the concentration is lower than the set value, the control valve on the branch line 9 is opened, the smoke exhaust line 5 is closed, and the airflow is heated by the heating device 91 on the branch line 9 and sent to the atomizing chamber 21 to fully contact and hydrolyze with the spray again. This cycle is repeated. After the concentration reaches the standard, the branch line 9 is closed, and the smoke exhaust line 5 is opened to transport it to the subsequent denitration reaction device 3 for denitration treatment. This technical design improves the final ammonia concentration.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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 atomizing and hydrolyzing urea aqueous solution for low-temperature denitration, characterized in that: The invention comprises a saturated urea aqueous solution buffer device (1), an atomizing hydrolysis device (2), a denitration reaction device (3), a smoke inlet pipeline (4) and a smoke exhaust pipeline (5), wherein the atomizing hydrolysis device (2) comprises an atomizing chamber (21) and an atomizing component (22) arranged in the atomizing chamber (21), the atomizing chamber (21) having a smoke inlet and a smoke exhaust outlet, the saturated urea aqueous solution buffer device (1) is connected to the atomizing component (22) via a conveying pipe (11), the smoke inlet pipeline (4) is connected to the smoke inlet, and the smoke exhaust pipeline (5) is respectively connected to the smoke exhaust outlet and the denitration reaction device (3).

2. The system for generating ammonia by atomizing and hydrolyzing urea aqueous solution for low-temperature denitration according to claim 1, characterized in that: The delivery pipe (11) is provided with a liquid pump (12).

3. The system for generating ammonia by atomizing and hydrolyzing urea aqueous solution for low-temperature denitration according to claim 1, characterized in that: The smoke exhaust pipeline (5) is provided with a gas pressurizing and conveying device (6) and a flow regulating valve (7).

4. The system for generating ammonia by atomizing and hydrolyzing urea aqueous solution for low-temperature denitration according to claim 3, characterized in that: The gas pressurizing and conveying device (6) is a fan.

5. The system for generating ammonia by atomizing and hydrolyzing urea aqueous solution for low-temperature denitration according to claim 1, characterized in that: The smoke inlet pipeline (4) is provided with a smoke conveying device (8).

6. A system for generating ammonia by atomizing and hydrolyzing urea aqueous solution for low-temperature denitration according to claim 5, characterized in that: The smoke conveying device (8) is a fan.

7. The system for generating ammonia by atomizing and hydrolyzing urea aqueous solution for low-temperature denitration according to claim 1, characterized in that: The saturated urea aqueous solution cache device (1) comprises a cache tank (13) and a heating unit (14), the cache tank (13) being provided with a liquid inlet and a liquid outlet, the liquid outlet being connected to the delivery pipe (11), and the heating unit (14) being arranged on the side wall and / or the bottom wall of the cache tank (13).

8. A system for generating ammonia by atomizing and hydrolyzing urea aqueous solution for low-temperature denitration according to any one of claims 1 to 7, characterized in that: A horizontal partition (211) is provided at the lower part of the atomizing chamber (21); a smoke inlet is provided at a portion of a side wall of one side of the atomizing chamber (21) close to one end of the partition (211); a through hole for upward flow of smoke is provided at the other end of the partition (211); a smoke exhaust port is provided at the upper part of the side wall of one side of the atomizing chamber (21); and the atomizing assembly (22) is provided below the partition (211).

9. The system for generating ammonia by atomizing and hydrolyzing urea aqueous solution for low-temperature denitration according to claim 8, characterized in that: The atomizing assembly (22) comprises an atomizer and a plurality of atomizing nozzles (221) connected to the atomizer. The plurality of atomizing nozzles (221) are mounted on the lower end of the partition (211) and are distributed at intervals between the two ends of the partition (211).

10. A system for generating ammonia by atomizing and hydrolyzing urea aqueous solution for low-temperature denitration according to any one of claims 1 to 7, characterized in that: The smoke exhaust port is also connected to the smoke inlet via a branch pipe (9), a heating device (91) is provided on the branch pipe (9), an ammonia concentration detector is provided at the smoke exhaust port, and a control valve is provided on the branch pipe (9).

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