Steam recycling system for SCR (Selective Catalytic Reduction) denitration by heating flue gas with steam
By adding a steam heating device in the SCR denitrification system, the flue gas is heated to the catalyst active temperature range, the problem of strict catalyst temperature requirements is solved, the denitrification efficiency is improved, and the steam is reused, which improves the energy efficiency and environmental protection of the system. performance.
Patent Information
- Application Number
- CN202323636642.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-29
- Publication Date
- 2025-02-18
- Estimated Expiration
- 2033-12-29
AI Technical Summary
In the existing SCR denitrification process, the temperature requirements of the catalyst are strict. If the temperature is insufficient, the denitrification efficiency will be low. If the temperature is too high, the catalyst will be deactivated, resulting in the flue gas not meeting the emission standards.
Design a steam reuse system for SCR denitrification with steam-heated flue gas. By adding a heat exchanger and a high-pressure condensate flash tank between the economizer and the air preheater, the flue gas is heated to the catalyst active temperature range , thereby improving denitrification efficiency, and separating low-pressure steam through a high-pressure condensate flash tank to achieve steam reuse.
The flue gas temperature is increased to reach the range with high catalyst reaction activity, thereby improving the efficiency of SCR denitrification, realizing the reuse of steam, and improving the energy efficiency and environmental performance of the system.
Smart Images
Figure CN222503902U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of energy conservation and environmental protection, in particular to a steam recycling system for heating flue gas with steam to carry out SCR denitration. Background Art
[0002] The waste incineration boiler is a device for incinerating and treating waste. After denitration, dust removal and desulfurization, the flue gas that meets the emission standards is discharged into the atmosphere through the chimney. Among them, the SCR (selective catalytic reduction) denitration process in denitration is a widely used denitration technology. It uses a catalyst to react nitrogen oxides in the flue gas with ammonia from the reductant supply system to generate harmless nitrogen and water. In this denitration process, a catalyst is required, and the catalyst is the core of this process. If the reaction temperature does not reach the activity of the catalyst, the efficiency of denitration will also be reduced accordingly; if the reaction temperature is too high, the catalyst will lose its activity, and the flue gas produced by denitration will also not meet the emission requirements.
[0003] In view of the above problems with the catalyst, we proposed a steam recycling system that uses steam to heat the flue gas for SCR denitrification. The system mainly increases the flue gas temperature so that the flue gas temperature reaches a range with higher catalyst reaction activity, thereby improving the reaction efficiency. Utility Model Content
[0004] The utility model provides a steam recycling system for SCR denitration by heating flue gas with steam, so as to solve the problems in the background technology.
[0005] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: a steam recycling system for SCR denitrification by heating flue gas with steam, comprising an economizer, the outlet of the economizer is connected to the low-temperature flue gas inlet of a heat exchanger, the heat exchanger further comprises a high-temperature flue gas outlet, a steam inlet and a saturated water outlet, the saturated water outlet of the heat exchanger is connected to a high-pressure condensate flash tank;
[0006] The high-temperature flue gas outlet of the heat exchanger is connected to the high-temperature flue gas inlet of the SCR reactor, and the outlet of the SCR reactor is connected to an air preheater, and the air preheater discharges the flue gas after the reaction through the flue gas outlet.
[0007] Furthermore, the inlet of the economizer receives flue gas generated by the incinerator, and the economizer is used to recover heat energy in the flue gas.
[0008] Furthermore, the steam inlet of the heat exchanger is connected to the boiler pipeline of the incinerator, and the steam inlet of the heat exchanger receives the steam generated by the boiler.
[0009] Furthermore, the high-pressure condensate flash tank includes a saturated water inlet, a low-pressure steam outlet and a condensate outlet. The saturated water inlet of the high-pressure condensate flash tank is connected to the saturated water outlet of the heat exchanger, and the low-pressure steam outlet and the condensate outlet of the high-pressure condensate flash tank are separated into gas and liquid.
[0010] Furthermore, the SCR reactor is provided with an ammonia inlet, which is sprayed into the flue gas through a spray grid, and reacts with the flue gas through the SCR reactor to remove nitrogen oxides.
[0011] Furthermore, the interior of the SCR reactor is sequentially provided with an upper catalyst, a middle catalyst and a lower catalyst from top to bottom; the upper catalyst is a metal oxide composed of vanadium, tungsten or titanium, the middle catalyst is a vanadium-titanium catalyst, and the lower catalyst is an iron or iron-vanadium oxide catalyst.
[0012] Compared with the prior art, the utility model provides a steam recycling system for SCR denitrification by heating flue gas with steam, which has the following beneficial effects:
[0013] The steam recycling system for SCR denitrification by heating flue gas with steam increases the denitrification efficiency by adding a heat exchanger and a high-pressure condensate flash tank between the economizer and the air preheater, and heats the flue gas to the temperature range required for the SCR reaction. At the same time, the condensed saturated water is separated into low-pressure steam through a high-pressure condensate flash tank, thereby achieving the purpose of using steam to heat the flue gas for SCR denitrification and steam recycling at the same time. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 It is a structural schematic diagram of the utility model.
[0015] In the figure: 1. economizer; 2. heat exchanger; 3. high-pressure condensate flash tank; 4. SCR reactor; 41. upper catalyst; 42. middle catalyst; 43. lower catalyst; 5. air preheater. DETAILED DESCRIPTION
[0016] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0017] See also Figure 1The utility model discloses a steam recycling system for SCR denitrification by heating flue gas with steam, comprising an economizer 1, the outlet of the economizer 1 is connected to the low-temperature flue gas inlet a of a heat exchanger 2, the heat exchanger 2 further comprises a high-temperature flue gas outlet b, a steam inlet c and a saturated water outlet d, the saturated water outlet d of the heat exchanger 2 is connected to a high-pressure condensate flash tank 3. The high-temperature flue gas outlet of the heat exchanger 2 is connected to the high-temperature flue gas inlet h of an SCR reactor 4, the outlet of the SCR reactor 4 is connected to an air preheater 5, and the air preheater 5 discharges the flue gas after the reaction through the flue gas outlet i.
[0018] The flue gas generated by the incinerator passes through the economizer 1, and then the flue gas discharged from the economizer 1 passes through the heat exchanger 2 to exchange heat with the steam generated by the incinerator. The heated flue gas enters the SCR reactor 4 for denitrification, and the condensed saturated water passes through the high-pressure condensate flash tank 3 to separate the usable steam.
[0019] Furthermore, the inlet of the economizer 1 receives flue gas generated by the incinerator, and the economizer 1 is used to recover heat energy in the flue gas.
[0020] Furthermore, the steam inlet c of the heat exchanger 2 is connected to the boiler pipeline of the incinerator, and the steam inlet c of the heat exchanger 2 receives the steam generated by the boiler.
[0021] Furthermore, the high-pressure condensate flash tank 3 includes a saturated water inlet e, a low-pressure steam outlet f and a condensate outlet g. The saturated water inlet e of the high-pressure condensate flash tank 3 is connected to the saturated water outlet d of the heat exchanger 2. The low-pressure steam outlet f and the condensate outlet g of the high-pressure condensate flash tank 3 are gas-liquid separated, and the separated low-pressure steam and condensate can be used in other parts of the incinerator that need steam.
[0022] Among them, the high-pressure steam after heat exchange is condensed into saturated water and discharged from the saturated water outlet d, and enters through the saturated water inlet e of the high-pressure condensate flash tank 3. According to the ideal gas state equation PV=nRT, the volume increases and the pressure decreases. For saturated water at a certain pressure, after the pressure is reduced, part of the saturated water is vaporized to generate secondary steam and is discharged from the low-pressure steam outlet f. At the same time, part of the saturated water is condensed into condensed water through the high-pressure condensate flash tank 3 and is discharged through the condensed water outlet g.
[0023] Furthermore, the SCR reactor 4 is provided with an ammonia inlet j. Ammonia is a commonly used reducing agent. The ammonia inlet j is sprayed into the flue gas through a spray grid, and reacts with the flue gas through the SCR reactor 4 to remove nitrogen oxides.
[0024] Furthermore, an upper catalyst 41 , a middle catalyst 42 and a lower catalyst 43 are sequentially arranged inside the SCR reactor 4 from top to bottom.
[0025] in:
[0026] The upper catalyst 41 is a metal oxide composed of vanadium, tungsten or titanium to increase NO x adsorption capacity.
[0027] The middle layer catalyst 42 is a vanadium-titanium catalyst, which can more effectively promote the ammonia and NO x Selective catalytic reduction reaction.
[0028] The lower catalyst 43 is an iron or iron-vanadium oxide catalyst, which is used to enhance the reaction efficiency in the final stage.
[0029] By determining the reaction temperature of the above catalyst, the temperature of the flue gas out of the economizer 1, and the temperature of the steam generated by the boiler, and by reasonably designing the heat exchanger 2, the heat exchange between the high-pressure steam generated by the boiler and the boiler flue gas is achieved. That is, the high-pressure steam generated by the incinerator enters the heat exchanger through the steam inlet c of the heat exchanger and exchanges heat with the flue gas entering through the low-temperature flue gas inlet a, thereby heating the flue gas temperature to the catalyst activity temperature range.
[0030] In summary, the steam recycling system for SCR denitrification by heating flue gas with steam, by adding a heat exchanger and a high-pressure condensate flash tank between the economizer and the air preheater, heats the flue gas to the temperature range required for the SCR reaction, thereby improving the denitrification efficiency, and at the same time, the condensed saturated water is separated into low-pressure steam through the high-pressure condensate flash tank, thereby achieving the purpose of using steam to heat the flue gas for SCR denitrification and steam recycling at the same time.
[0031] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A steam recycling system for SCR denitrification by heating flue gas with steam, comprising an economizer (1), characterized in that: The outlet of the economizer (1) is connected to the low-temperature flue gas inlet of the heat exchanger (2); the heat exchanger (2) further comprises a high-temperature flue gas outlet, a steam inlet and a saturated water outlet; the saturated water outlet of the heat exchanger (2) is connected to a high-pressure condensate flash tank (3); The high-temperature flue gas outlet of the heat exchanger (2) is connected to the high-temperature flue gas inlet of the SCR reactor (4), and the outlet of the SCR reactor (4) is connected to an air preheater (5), and the air preheater (5) discharges the flue gas after the reaction through the flue gas outlet.
2. A steam recycling system for SCR denitrification using steam to heat flue gas according to claim 1, characterized in that: The inlet of the economizer (1) receives flue gas generated by an incinerator, and the economizer (1) is used to recover heat energy in the flue gas.
3. The steam recycling system for SCR denitrification using steam to heat flue gas according to claim 1, characterized in that: The steam inlet of the heat exchanger (2) is connected to the boiler pipe of the incinerator, and the steam inlet of the heat exchanger (2) receives steam generated by the boiler.
4. The steam recycling system for SCR denitrification using steam to heat flue gas according to claim 1, characterized in that: The high-pressure condensate flash tank (3) comprises a saturated water inlet, a low-pressure steam outlet and a condensate outlet; the saturated water inlet of the high-pressure condensate flash tank (3) is connected to the saturated water outlet of the heat exchanger (2); the low-pressure steam outlet and the condensate outlet of the high-pressure condensate flash tank (3) are used for gas-liquid separation.
5. The steam recycling system for SCR denitrification using steam to heat flue gas according to claim 1, characterized in that: The SCR reactor (4) is provided with an ammonia inlet, which is sprayed into the flue gas through a spray grid, and reacts with the flue gas through the SCR reactor (4) to remove nitrogen oxides.
6. The steam recycling system for SCR denitrification using steam to heat flue gas according to claim 1, characterized in that: An upper catalyst (41), a middle catalyst (42) and a lower catalyst (43) are arranged in order from top to bottom inside the SCR reactor (4); the upper catalyst (41) is a metal oxide composed of vanadium, tungsten or titanium, the middle catalyst (42) is a vanadium-titanium catalyst, and the lower catalyst (43) is an iron or iron-vanadium oxide catalyst.