SCR denitration urea hydrolysis ammonia production flue gas waste heat utilization energy-saving device
During the process of hydrolysis of the ammonia in the SCR denitrification urea, heat exchange is performed using high-temperature flue gas and cold air below the outlet of the denitrification reactor, and the cold air is heated to avoid ammonia crystallization and improve ammonia conversion. The reverse reaction and high energy consumption caused by too low temperature in urea hydrolysis ammonia is solved, and energy-saving and efficient ammonia preparation is achieved.
Patent Information
- Application Number
- CN202323518256.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-22
- Publication Date
- 2025-03-11
- Estimated Expiration
- 2033-12-22
AI Technical Summary
In the prior art, in the process of urea hydrolysis and ammonia production, too low temperature can easily lead to reverse reaction and crystallization, resulting in low ammonia conversion, and high energy consumption by electric heating or steam heating, which poses safety risks.
A waste heat utilization energy-saving device for SCR denitrification urea hydrolysis ammonia flue gas is designed, and heat exchange is made using high-temperature flue gas and cold air below the outlet of the denitrification reactor, and the cold air is heated to 160-180℃, thereby providing sufficient heat to avoid ammonia crystallization and improve ammonia conversion.
By heating the cold air with waste heat of flue gas, the temperature stability during the urea hydrolysis process is achieved, reverse reaction and crystallization are avoided, ammonia conversion is improved, and energy consumption is saved.
Smart Images
Figure CN222586122U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of SCR denitration urea hydrolysis to produce ammonia for air pollution control in industrial enterprises, and relates to an energy-saving device for utilizing waste heat of flue gas from SCR denitration urea hydrolysis to produce ammonia. Background Art
[0002] In the prior art, SCR denitrification generally uses liquid ammonia, ammonia water or urea as a reducing agent to prepare ammonia gas, which is sprayed into the denitrification reactor through an ammonia spray grid. The ammonia gas NH3 reacts with nitrogen oxides NO in the flue gas. X Catalytic reduction reaction is carried out under the action of catalyst to remove nitrogen oxides NO in flue gas. X The use of liquid ammonia to produce ammonia has high efficiency, but the safety risk is high. The use of urea to produce ammonia has high energy consumption, but the safety risk is low. At present, the technical route of using urea as a reducing agent to produce ammonia is divided into urea thermal decomposition and urea hydrolysis processes.
[0003] Since urea hydrolysis is a chemical decomposition reaction, the lower the temperature of the product gas is below 120℃, the easier it is to reverse the reaction, and the intermediate product ammonium carbamate will precipitate, which is highly corrosive and easy to crystallize, causing the pipeline valve to be blocked. When it is higher than 180℃, biuret crystallization will occur, resulting in low ammonia conversion rate. Therefore, unlike liquid ammonia or urea pyrolysis to produce ammonia, the product gas pipeline of urea hydrolysis to produce ammonia must be insulated and heated. When cold air is used to mix ammonia into a mixed gas of less than 5%, the cold air must be heated to about 160-180℃ to avoid crystallization caused by too low a mixed gas temperature. The heat source for cold air heating is generally steam as a heat source steam heater, hot flue gas as a heat source flue gas heat exchanger, and auxiliary electric heating. Electric heating consumes a lot of electricity and energy, and steam heating consumes steam and energy. At the same time, there is a need for drainage, so the above factors limit its use. Utility Model Content
[0004] In view of the above problems, the utility model provides an SCR denitration urea hydrolysis ammonia flue gas waste heat utilization energy-saving device. It can fully utilize the heat exchange between the hot flue gas and the cold air in the flue duct at the outlet of the denitration reactor, and provide an SCR denitration urea hydrolysis ammonia flue gas waste heat utilization energy-saving device, thereby achieving the purpose of saving energy consumption in preparing hot ammonia mixed gas.
[0005] The technical solution of the utility model is: an SCR denitrification urea hydrolysis ammonia flue gas waste heat utilization energy-saving device, characterized in that: one end of the inlet air collecting box is connected to a fan, one end of the outlet air collecting box is connected to an ammonia mixer, a plurality of upper fin tube bundles and a plurality of lower fin tube bundles are installed between the inlet air collecting box and the outlet air collecting box, and anti-wear tiles are arranged above the upper fin tube bundles and the lower fin tube bundles. The anti-wear tiles adopt a "human"-shaped structure in cross section, and its internal angle is 135 degrees. The anti-wear tiles (5) are orifice plates with a hole diameter of 10-20mm.
[0006] The utility model adopts a longitudinal height spacing of 400-600mm and a transverse staggered spacing of 300-400mm to configure the upper fin tube bundle and the lower fin tube bundle welded on the inlet gas collecting box and the outlet gas collecting box. The device is arranged below the outlet of the denitrification reactor and utilizes the high-temperature flue gas and cold air for heat exchange to heat the cold air.
[0007] Compared with the prior art, the beneficial effects of the utility model are:
[0008] The utility model has the outstanding advantages of utilizing the flue gas waste heat for heat exchange, saving energy consumption, and being simple in device and easy in installation and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Attached Figure 1 It is a front view of the device of an embodiment of the utility model.
[0010] Attached Figure 2 It is a top view of the device of an embodiment of the utility model.
[0011] Attached Figure 3 It is a partial schematic diagram of the anti-wear tile of an embodiment of the utility model.
[0012] In the figure: 1. inlet air collecting box, 2. upper fin tube bundle, 3. outlet air collecting box, 4. lower fin tube bundle, 5. anti-wear tile, 6. hot flue gas, 7. denitrification reactor, 8. flue, 9. ammonia mixer, 10. fan. DETAILED DESCRIPTION
[0013] The following describes the embodiments in conjunction with the accompanying drawings:
[0014] The utility model discloses an energy-saving device for utilizing waste heat of flue gas from hydrolysis of urea for SCR denitration to produce ammonia. The device comprises an inlet air collecting box 1 having one end connected to a fan 10, an outlet air collecting box 3 having one end connected to an ammonia mixer 9, a plurality of upper finned tube bundles 2 and a plurality of lower finned tube bundles 4 connected between the inlet air collecting box 1 and the outlet air collecting box 3, anti-wear tiles 5 are arranged above the upper finned tube bundles 2 and the lower finned tube bundles 4, the anti-wear tiles having a "human" shaped cross section and an inner angle of 135 degrees, and the anti-wear tiles 5 are orifice plates with an aperture of 10-20 mm.
[0015] The utility model adopts a longitudinal height spacing of 400-600mm and a transverse staggered spacing of 300-400mm to configure an upper fin tube bundle 2 and a lower fin tube bundle 4, which are welded on an inlet air collecting box 1 and an outlet air collecting box 3.
[0016] The utility model is arranged at a position below the outlet of the denitration reactor 7 in the flue 8, and utilizes the high-temperature hot flue gas 6 and the cold air for heat exchange to heat the cold air.
[0017] The inlet air collecting box 1 and the outlet air collecting box 3 are made of seamless steel pipes, and the upper fin tube bundle 2 and the lower fin tube bundle 4 are welded with multiple fin tube bundles to form an air-to-air heat exchanger. The pipe diameter is designed according to the flue gas flow rate of 10-15m / s. The cold air of the fan 10 is collected by the inlet air collecting box 1, passes through the upper fin tube bundle 2 and the lower fin tube bundle 4, and is collected to the outlet air collecting box 3. During this period, the cold air and the hot flue gas 6 in the flue 8 outside the tube bundle are heat-exchanged to heat the cold air to about 160-180℃. The heated hot air enters the ammonia mixer 9 and mixes with the mother pipe ammonia to form a mixed gas with a concentration of less than 5% and enters the ammonia injection grid for denitration reaction.
[0018] The anti-wear tile 5 of the utility model is arranged above the upper fin tube bundle 2 and the lower fin tube bundle 4 to reduce the wear of the tube bundle by dust in the flue gas. Figure 3 The anti-wear tile 5 shown has a "human" shaped cross section with an internal angle of 135 degrees. The anti-wear tile 5 is a perforated plate with an aperture of 10-20 mm and an opening rate of >60%. This not only prevents the wear of the tube bundle by dust in the flue gas after the denitrification reaction, but also effectively reduces wind resistance and improves heat exchange efficiency.
Claims
1. An SCR denitrification urea hydrolysis ammonia flue gas waste heat utilization energy-saving device, characterized by: One end of the inlet air collecting box (1) is connected to a fan (10), and one end of the outlet air collecting box (3) is connected to an ammonia mixer (9). A plurality of upper finned tube bundles (2) and a plurality of lower finned tube bundles (4) are arranged between the inlet air collecting box (1) and the outlet air collecting box (3). Anti-wear tiles (5) are arranged above the upper finned tube bundles (2) and the lower finned tube bundles (4). The anti-wear tiles (5) have a "human" shaped cross section and an internal angle of 135 degrees. The anti-wear tiles (5) are orifice plates with a hole diameter of 10-20 mm.