Ammonia-air mixing system
By employing two independent ammonia-air mixing units in the ammonia-air mixing system, using flue gas and steam as heat sources respectively, the problem of insufficient operational stability of the SCR catalytic unit was solved, and the system's flexibility and stability were improved.
Patent Information
- Application Number
- CN202423261454.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-27
- Publication Date
- 2025-12-12
- Estimated Expiration
- 2034-12-27
AI Technical Summary
Existing technologies have failed to effectively integrate flue gas heating and steam heating schemes, resulting in insufficient operational stability of the SCR catalytic unit and an inability to adapt to changes in ammonia injection flow rate requirements.
Two independent ammonia-air mixing units are used, one using flue gas as a heat source and the other using steam as a heat source. The flow rates of the dilution fan and heater are flexibly adjusted to adapt to the changes in the ammonia demand of the SCR catalytic unit.
This improves the system's flexibility and stability, enabling it to adapt to different ammonia injection flow requirements and ensuring the stable operation of the SCR catalytic unit.
Smart Images
Figure CN223654773U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the technical field of environmental protection equipment, specifically relates to a ammonia air mixing system. BACKGROUND
[0002] The prior application CN118384913A of the applicant, the subject of which is a supported catalyst and a preparation method thereof, and a urea ammonia denitration method, is recorded in the 59th paragraph of the specification: the dilution wind flue gas heating scheme is to use the low flow rate hot flue gas below the SCR reactor to exchange heat with the cold wind from the dilution fan. Because the pipeline wear is proportional to the 2.7 power of the flue gas flow rate, the flow rate at this place is much lower than the flow rate at the coal economizer, the wear is slight, and the wear allowance of the heat exchanger pipe wall is appropriately increased during design to ensure stable operation. At the same time, because the heat exchange area is small, the influence on the flue gas side resistance can be ignored, and the influence on the inlet flue gas temperature of the air preheater is small, and the flue gas heat exchanger 7 has small routine maintenance amount. Based on the dilution wind temperature 200 DEG C, the wind volume of a single machine 4000 Nm 3 / h (keeping the ammonia gas concentration in the ammonia mixed gas at 5%), the heat source is calculated, which is divided into three kinds of heat sources: (1) electric heating; (2) SCR outlet flue gas heating; (3) auxiliary steam heating. The energy consumption calculation results are as follows: (1) electric heating - 235 kW; (2) steam heating - 0.3 t / h (temperature 290 DEG C, pressure 1.0 MPa); (3) flue gas heating - overall temperature drop 0.3 DEG C (the total area of the heat exchanger 7 is 200 m 2 ).
[0003] The above scheme discloses the feasibility of using the dilution wind flue gas heating scheme. No new solution is proposed for the further integration of the flue gas heating and steam heating schemes. INVENTION CONTENTS
[0004] The utility model discloses a kind of ammonia air mixing systems, which fully considers the operation stability of SCR catalytic unit, while using the system stability of flue gas heating, steam heating, and its system stability is high.
[0005] To achieve the above object, the utility model provides the following technical scheme:
[0006] A kind of ammonia air mixing system, including first ammonia air mixing unit, second ammonia air mixing unit, the first ammonia air mixing unit includes first ammonia air mixer, first heater for heating dilution wind, first ammonia supply pipe;The first heater, first ammonia supply pipe are connected to the inlet of first ammonia air mixer;The second ammonia air mixing unit includes second ammonia air mixer, second heater for heating dilution wind, second ammonia supply pipe;Second heater, second ammonia supply pipe are connected to the inlet of second ammonia air mixer;
[0007] The heat source of the first heater is flue gas in the flue outlet of the external SCR catalytic unit; the heat source of the second heater is water vapor; the inlet of the first heater is connected with two first dilution air fans in parallel; the inlet of the second heater is connected with at least three second dilution air fans in parallel.
[0008] The outlet of the first ammonia-air mixer and the outlet of the second ammonia-air mixer are connected to the flue inlet of the external SCR catalytic unit.
[0009] The utility model discloses two sets of independently operated first ammonia-air mixing units and second ammonia-air mixing units, wherein the former uses flue gas as a heat source, and the latter uses water vapor as a heat source; since the temperature of the flue gas discharged by the SCR catalytic unit should not fluctuate too much, and the structure of the heat exchanger should not be excessively enlarged to affect the gas flow resistance, when the ammonia required by the SCR catalytic unit increases (fluctuation caused by sudden change of the composition of the flue gas), the amount of ammonia injection needs to be appropriately increased; at this time, the dilution air of the first ammonia-air mixing unit is kept stable, the water vapor flow of the second heater is changed, and the number of the second dilution air fans is switched or increased, so that the flexibility of the system is increased, and different ammonia injection flow requirements can be met.
[0010] In the ammonia-air mixing system, the outlet of each first ammonia-air mixer and the outlet of each second ammonia-air mixer are connected to the flue inlet of each external SCR catalytic unit and are controlled to be conducted through valves.
[0011] In the ammonia-air mixing system, the first ammonia-air mixing unit comprises two first ammonia-air mixers connected in parallel, two first heaters connected in parallel, two first ammonia supply pipes connected in parallel and two first dilution air fans connected in parallel; one first ammonia-air mixer, one first heater and one first ammonia supply pipe form a first flow path; two first flow paths are connected in parallel; the outlets of the two first dilution air fans are collected and introduced into the inlets of the two first heaters.
[0012] In the ammonia-air mixing system, the second ammonia-air mixing unit comprises two second ammonia-air mixers connected in parallel, two second heaters connected in parallel, two second ammonia supply pipes connected in parallel and three second dilution air fans connected in parallel; one second ammonia-air mixer, one second heater and one second ammonia supply pipe form a second flow path; two second flow paths are connected in parallel; the outlets of the three second dilution air fans are collected and introduced into the inlets of the two second heaters.
[0013] In the ammonia-air mixing system, the outlets of the three second dilution air fans are respectively connected with first valves; the outlets of the three second dilution air fans are communicated through a first communication pipeline; two second valves are arranged on the first communication pipeline; the two second valves and the first valve of the second dilution air fan located in the middle form a three-way structure.
[0014] In the ammonia-air mixing system, flow meters are arranged on the inlet of the first heater, the inlet of the second heater, the first ammonia supply pipe and the second ammonia supply pipe.
[0015] In the ammonia-air mixing system, a heating jacket layer is arranged on the outer periphery of the first ammonia supply pipe and the second ammonia supply pipe, and water vapor is introduced into the heating jacket layer.
[0016] Compared with the prior art, the ammonia-air mixing system has the following beneficial effects:
[0017] The first ammonia-air mixing unit and the second ammonia-air mixing unit are independently operated, the first ammonia-air mixing unit uses flue gas as a heat source, and the second ammonia-air mixing unit uses water vapor as a heat source. BRIEF DESCRIPTION OF DRAWINGS
[0018] Figure 1 is a structural schematic view of the first ammonia-air mixing unit of embodiment 1;
[0019] Figure 2 is a structural schematic view of the second ammonia-air mixing unit of embodiment 1;
[0020] Figure 3 is a structural schematic view of embodiment 1. DETAILED DESCRIPTION
[0021] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.
[0022] Embodiment 1
[0023] Reference Figure 3An ammonia-air mixing system comprises a first ammonia-air mixing unit 1 and a second ammonia-air mixing unit 2, the first ammonia-air mixing unit 1 comprises a first ammonia-air mixer 11, a first heater 12 for heating dilution air, and a first ammonia supply pipe 13; the first heater 12 and the first ammonia supply pipe 13 are connected to an inlet of the first ammonia-air mixer 11; the second ammonia-air mixing unit 2 comprises a second ammonia-air mixer 21, a second heater 22 for heating dilution air, and a second ammonia supply pipe 23; the second heater 22 and the second ammonia supply pipe 23 are connected to an inlet of the second ammonia-air mixer 21.
[0024] The first heater 12 is heated by flue gas in a flue outlet of an external SCR catalytic unit 3; the second heater 22 is heated by water vapor; the inlet of the first heater 12 is connected to two first dilution air fans 14 in parallel; the inlet of the second heater 22 is connected to at least three second dilution air fans 24 in parallel.
[0025] The outlet of the first ammonia-air mixer 11 and the outlet of the second ammonia-air mixer 21 are connected to a flue inlet of the external SCR catalytic unit 3.
[0026] The first ammonia-air mixing unit 1 and the second ammonia-air mixing unit 2 are independently operated, wherein the former uses flue gas as a heat source, and the latter uses water vapor as a heat source; since the temperature of flue gas discharged by the SCR catalytic unit 3 should not fluctuate too much, and the structure of the heat exchanger should not be excessively enlarged to affect the gas flow resistance, when the required amount of ammonia of the SCR catalytic unit 3 increases (fluctuation caused by sudden change of components of flue gas), the amount of ammonia to be sprayed needs to be appropriately increased, at this time, the dilution air of the first ammonia-air mixing unit 1 is kept stable, the water vapor flow of the second heater 22 is changed, and the number of the second dilution air fans 24 is switched or increased, so that the flexibility of the system is increased, and different ammonia spraying flow requirements can be met.
[0027] In actual production, the SCR catalytic unit 3 of the external device has 2 or 3 or 4, and generally, each SCR catalytic unit 3 is provided with a first heater 12; normally, one of the two first dilution air fans 14 of the first ammonia-air mixing unit 1 is in use, and the other is standby; one of the three second dilution air fans 24 of the second ammonia-air mixing unit 2 is in use, and the other two are standby; the outlet of the first ammonia-air mixer 11 and the outlet of the second ammonia-air mixer 21 are respectively connected to the flue inlet of each SCR catalytic unit 3, and the outlet of each first ammonia-air mixer 11 and the outlet of each second ammonia-air mixer 21 are respectively controlled by independent control valves and the conduction and opening degree of each SCR catalytic unit 3; in the case of fluctuation of production conditions, the NOx concentration of one or more SCR catalytic units 3 rises, and more ammonia gas is needed, at this time, the first ammonia-air mixing unit 1 maintains normal production, and one of the second dilution air fans 24 of the second ammonia-air mixing unit 2 is additionally started to increase the heating air volume of the second heater 22, and at the same time, the flow of the second ammonia supply pipe 23 is increased, and the excess heat ammonia generated is supplied to the corresponding fluctuating SCR catalytic unit 3.
[0028] In the above-mentioned ammonia-air mixing system, the outlet of each first ammonia-air mixer 11 and the outlet of each second ammonia-air mixer 21 are connected to the flue inlet of each external SCR catalytic unit 3 and are controlled by valves.
[0029] Preferably, referring to Figure 1 , the first ammonia-air mixing unit 1 comprises two parallel first ammonia-air mixers 11, two parallel first heaters 12, two parallel first ammonia supply pipes 13, and two parallel first dilution air fans 14; one first ammonia-air mixer 11, one first heater 12, and one first ammonia supply pipe 13 constitute a first flow path; two first flow paths are connected in parallel; the outlets of the two parallel first dilution air fans 14 are collected and introduced into the inlets of the two first heaters 12.
[0030] Referring to Figure 2 , the second ammonia-air mixing unit 2 comprises two parallel second ammonia-air mixers 21, two parallel second heaters 22, two parallel second ammonia supply pipes 23, and three parallel second dilution air fans 24; one second ammonia-air mixer 21, one second heater 22, and one second ammonia supply pipe 23 constitute a second flow path; two second flow paths are connected in parallel; the outlets of the three parallel second dilution air fans 24 are collected and introduced into the inlets of the two second heaters 22.
[0031] The parallel design of the above-mentioned first flow path and the parallel design of the second flow path are conventional redundant designs in chemical design; in the normal production process, one first flow path is in use, and one first flow path is standby or under maintenance; one second flow path is in use, and one second flow path is standby or under maintenance.
[0032] The embodiment uses three parallel second dilution air fans 24 to serve a second flow path, normally only one second dilution air fan 24 is enabled, two second dilution air fans are enabled when the SCR catalytic unit 3 fluctuates, at the same time, the flow of water vapor of the second heater 22 and the ammonia supply flow of the second ammonia supply pipe 23 are simultaneously increased.
[0033] Preferably, the outlets of the three second dilution air fans 24 are respectively connected with first valves 25; the outlets of the three second dilution air fans 24 are communicated through a first communication pipeline 26; two second valves 27 are arranged on the first communication pipeline 26; the two second valves 27 and the first valve 25 of the middle second dilution air fan 24 form a three-way structure.
[0034] The combination of the first valve 25 and the second valve 27 can better realize flexible enabling and switching of the middle second dilution air fan 24, when one second dilution air fan 24 is used, the corresponding second valve 27 is opened and the other second valve 27 is closed. In normal working conditions, the two second valves 27 are closed, and the three-way structure is kept in a non-conducting state.
[0035] Preferably, flow meters 4 are arranged on the inlet of the first heater 12, the inlet of the second heater 22, the first ammonia supply pipe 13 and the second ammonia supply pipe 23, and heating jacket layers are arranged on the outer periphery of the first ammonia supply pipe 13 and the second ammonia supply pipe 23; water vapor is introduced into the heating jacket layers.
[0036] Since the amount of ammonia used is much less than the amount of dilution air used, an additional heater is not needed, and the ammonia can be heated by the heating jacket layer on the outer wall of the pipe, so that the dilution air and the ammonia can maintain a small temperature difference in the ammonia-air mixer.
[0037] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements or modifications can be made, and these improvements or modifications should also be considered as the protection scope of the present application.
Claims
1. An ammonia-air mixing system, comprising a first ammonia-air mixing unit and a second ammonia-air mixing unit, characterized in that, The first ammonia-air mixing unit includes a first ammonia-air mixer, a first heater for heating dilution air, and a first ammonia supply pipe; the first heater and the first ammonia supply pipe are connected to the inlet of the first ammonia-air mixer; the second ammonia-air mixing unit includes a second ammonia-air mixer, a second heater for heating dilution air, and a second ammonia supply pipe; the second heater and the second ammonia supply pipe are connected to the inlet of the second ammonia-air mixer; The heat source for the first heater is the flue gas from the flue outlet of the external SCR catalytic unit; the heat source for the second heater is water vapor; the inlet of the first heater is connected to two first dilution fans in parallel; the inlet of the second heater is connected to at least three second dilution fans in parallel. The outlets of the first and second ammonia-air mixers are connected to the flue gas inlet of the external SCR catalytic unit.
2. The ammonia-air mixing system according to claim 1, characterized in that, The outlets of the first ammonia-air mixer and the second ammonia-air mixer are connected to the flue inlet of each external SCR catalytic unit and the connection is controlled by valves.
3. The ammonia-air mixing system according to claim 1, characterized in that, The first ammonia-air mixing unit includes two parallel first ammonia-air mixers, two parallel first heaters, two parallel first ammonia supply pipes, and two parallel first dilution fans; one first ammonia-air mixer, one first heater, and one first ammonia supply pipe constitute a first flow path; the two first flow paths are connected in parallel; the outlets of the two parallel first dilution fans are collected and introduced into the inlets of the two first heaters.
4. The ammonia-air mixing system according to claim 1, characterized in that, The second ammonia-air mixing unit includes two parallel second ammonia-air mixers, two parallel second heaters, two parallel second ammonia supply pipes, and three parallel second dilution fans; one second ammonia-air mixer, one second heater, and one second ammonia supply pipe constitute a second flow path; the two second flow paths are connected in parallel; the outlets of the three parallel second dilution fans are collected and introduced into the inlets of the two second heaters.
5. The ammonia-air mixing system according to claim 4, characterized in that, The outlets of the three second dilution blowers are each connected to a first valve; the outlets of the three second dilution blowers are connected through a first connecting pipe; the first connecting pipe is equipped with two second valves; the two second valves and the first valve of the second dilution blower located in the middle form a three-way structure.
6. The ammonia-air mixing system according to claim 1, characterized in that, Flow meters are installed on the inlet of the first heater, the inlet of the second heater, the first ammonia supply pipe, and the second ammonia supply pipe.
7. The ammonia-air mixing system according to claim 1, characterized in that, The outer periphery of the first ammonia supply pipe and the outer periphery of the second ammonia supply pipe are provided with heating sleeves; water vapor is introduced into the heating sleeves.