CN213651871U

CN213651871U - Urea pyrolysis system

Info

Publication number: CN213651871U
Application number: CN202022764356.6U
Authority: CN
Inventors: 王审昌; 岳乃利
Original assignee: Shandong Lifeng Environmental Protection Technology Co ltd
Current assignee: Shandong Lifeng Environmental Protection Technology Co ltd
Priority date: 2020-11-25
Filing date: 2020-11-25
Publication date: 2021-07-09
Anticipated expiration: 2030-11-25

Abstract

The invention discloses a urea pyrolysis system, which relates to the technical field of boiler flue gas treatment and comprises a feeding mechanism, a heating furnace mechanism, a preheating mechanism, a compressed air pipeline, an ammonia pipeline and a damp and hot air pipeline; the feeding mechanism pipeline is connected with the compressed air pipeline; the preheating mechanism pipeline is connected with the wet hot air pipeline; the heating furnace mechanism comprises a rotatable furnace body and a heater; the feeding mechanism, the compressed air pipeline, the ammonia pipeline and the wet and hot air pipeline are all communicated with the inner cavity of the furnace body through pipelines; the compressed air pipeline can blow compressed air for urea conveyed by the feeding mechanism into the inner cavity of the furnace body, the ammonia gas pipeline can output ammonia gas generated in the inner cavity of the furnace body, the damp and hot air pipeline can heat damp air and input the damp air into the inner cavity of the furnace body, and the heater can heat the furnace body. The system has reasonable structure, energy conservation, convenient operation, difficult blockage and small occupied area.

Description

Urea pyrolysis system

Technical Field

The invention relates to the technical field of boiler flue gas treatment, in particular to a urea pyrolysis system.

Background

Along with the economic development in China, the pollution of flue gas discharged by boilers of coal-fired power plants, industrial kilns and the like to the atmospheric environment is increasingly serious, and the urban haze weather is also increased rapidly, so that the smoke-exhausting device is widely concerned by the whole society. Therefore, the state sets stricter smoke emission standards of the coal-fired power plant boiler and the industrial kiln in succession, and aims to reduce the influence of the smoke emission of enterprises on the atmospheric environment.

In order to maintain the normal production of enterprises and ensure that nitrogen oxides in flue gas discharged by boilers of coal-fired power plants, industrial kilns and the like stably reach the standard, boiler flue gas denitration technologies SCR and SNCR are comprehensively popularized in national coal-fired power plants and industrial kilns. The wide application of the technologies greatly reduces the emission of nitrogen oxides in the flue gas, improves the surrounding atmospheric environment and makes great contribution to avoiding haze.

In SCR and SNCR systems, liquid ammonia, ammonia and urea are commonly used as reducing agents. Wherein, the liquid ammonia is flammable and explosive, is limited by regions, has strict requirements on safe application conditions, and limits the large-scale application of the liquid ammonia in industry; in recent years, in order to avoid production accidents, ammonia water with the concentration of more than 10% is listed in dangerous chemicals, and the safe application conditions are increasingly strict. Although ammonia water with a concentration of less than 10% is a common chemical, in practical application, the problems of large usage amount and inconvenient transportation still exist. Thus, urea is necessarily the first choice for manufacturers when a reductant is selected for use in SCR and SNCR systems.

Whether liquid ammonia, ammonia water or urea, is converted into ammonia gas to be utilized by the SCR and SNCR systems.

At present, the technologies for preparing ammonia from urea mainly comprise urea solution spray pyrolysis and urea solution stripping. The stripping process requires high operating pressure, the system is heavy and complex, and the stripping process is generally rarely applied. At present, the urea solution spray pyrolysis process is commonly used for preparing ammonia from urea.

The urea solution is mainly dissolved into solution in the process of spray pyrolysis, and then the solution enters a pyrolysis furnace for spray pyrolysis. The equipment related to the pyrolysis process mainly comprises a urea solution preparation system, a urea solution conveying system, a spraying system, a hot air heating system, a pyrolysis system and the like. The pyrolysis chamber requires high temperature (the hot air temperature is more than 600 ℃), large air quantity, harsh technological conditions, improper design or operation and easy blockage of system crystallization. In view of this, this patent equipment adopts the direct pyrolysis technology of urea granule, has abandoned traditional preparation to become the solution and has carried out the process route of pyrolysis earlier for the system constitutes simpler, energy saving, convenient operation, system can not block up, area significantly reduces.

Disclosure of Invention

In order to achieve the purpose, the invention adopts the following technical scheme:

a urea pyrolysis system comprises a feeding mechanism, a heating furnace mechanism, a preheating mechanism, a compressed air pipeline, an ammonia pipeline and a damp and hot air pipeline; the feeding mechanism pipeline is connected with the compressed air pipeline; the preheating mechanism pipeline is connected with the wet hot air pipeline; the heating furnace mechanism comprises a rotatable furnace body and a heater; the feeding mechanism, the compressed air pipeline, the ammonia pipeline and the wet and hot air pipeline are all communicated with the inner cavity of the furnace body through pipelines; the compressed air pipeline can blow compressed air for urea conveyed by the feeding mechanism into the inner cavity of the furnace body, the ammonia gas pipeline can output ammonia gas generated in the inner cavity of the furnace body, the damp and hot air pipeline can heat damp air and input the damp air into the inner cavity of the furnace body, and the heater can heat the furnace body.

Preferably, the feeding mechanism comprises a feeding bin and a screw conveyor, an outlet of the feeding bin is connected with a feeding hole of the screw conveyor, and a compressed air feeding valve is arranged between a discharging hole of the screw conveyor and the compressed air pipeline.

Preferably, a compressed air storage tank is arranged on the compressed air pipeline.

Preferably, the preheating mechanism comprises a flue gas preheater and an electric heater.

Preferably, the ammonia pipeline is provided with a first branch and a second branch which are connected in parallel, the first branch is provided with a first fan, and the second branch is provided with a second fan.

Preferably, the device further comprises an atomizer, and the atomizer is connected with the preheating mechanism.

Preferably, the heater is an electromagnetic heater and is arranged below the furnace body.

Preferably, a heat radiation fan is arranged below the heater.

The system provided by the invention is reasonable in structure arrangement, adopts a direct urea particle pyrolysis process, and abandons the traditional process route of preparing a solution and then pyrolyzing the solution, so that the system is simpler in structure, energy-saving, convenient to operate, not easy to block and small in occupied area.

Drawings

FIG. 1 is a schematic diagram of the system of the present invention;

fig. 2 is a left side view of the heating furnace mechanism.

Detailed Description

The invention is further described with reference to the following figures and examples.

As shown in fig. 1, a urea pyrolysis system is composed of a feeding mechanism 1, a heating furnace mechanism 2, a preheating mechanism 3, a compressed air pipeline 4, an ammonia pipeline 5 and a wet hot air pipeline 6.

Wherein the pipeline of the feeding mechanism 1 is connected with a compressed air pipeline 4; the pipeline of the preheating mechanism 3 is connected with a wet hot air pipeline 6; the heating furnace mechanism 2 includes a rotatable furnace body 21 and a heater 22; the feeding mechanism 1, the compressed air pipeline 4, the ammonia pipeline 5 and the damp and hot air pipeline 6 are all communicated with the inner cavity of the furnace body 21 through pipelines; the compressed air pipeline 4 can blow the compressed air for urea conveyed by the feeding mechanism 1 into the inner cavity of the furnace body 21, the ammonia gas pipeline 5 can output ammonia gas generated in the inner cavity of the furnace body 21, the damp and hot air pipeline 6 can heat the damp air and input the damp air into the inner cavity of the furnace body 21, and the heater 22 can heat the furnace body 21. The heater 22 is an electromagnetic heater and is disposed below the furnace body 21. A heat radiation fan 29 is provided below the heater 22.

The feeding mechanism 1 comprises a feeding bin 11 and a metering type screw conveyor 12, an outlet of the feeding bin 11 is connected with a feeding port of the screw conveyor 12, a compressed air feeding valve 13 is arranged between a discharging port of the screw conveyor 12 and the compressed air pipeline 4, an air inlet and an air outlet are respectively arranged at two ends of the compressed air feeding valve 13, an obliquely arranged urea feeding pipe is arranged in the middle of the compressed air feeding valve, and urea enters from the urea feeding pipe from the discharging port of the screw conveyor 12 and then is blown into the furnace body 21 by compressed air. A compressed air storage tank 7 is provided in the compressed air line 4.

The preheating mechanism includes a flue gas preheater 31 and an electric heater 32. By utilizing the flue gas of a high-temperature kiln of a factory, the flue gas preheater 31 exchanges heat and heats the humid air generated by the atomizer 9, and the electric heater 32 performs auxiliary heating to control the humid and hot air in a stable temperature range.

The ammonia pipeline 5 is provided with a first branch 6a and a second branch 6b which are connected in parallel, the first branch is provided with a first fan 61, and the second branch is provided with a second fan 62. The ammonia gas can be diluted and adjusted according to the yield. And after being regulated, the ammonia gas is sprayed out to treat and purify the flue gas of the kiln after being catalyzed by the catalyst 8, and an ammonia gas concentration detector 81 is arranged at the gas outlet end.

As shown in fig. 2, the furnace body 21 of the heating furnace mechanism 2 is rotatable, furnace necks 23 are arranged at two ends, wherein the furnace neck 23 at one end is provided with an opening, and the other end is blocked. The furnace neck 23 is provided with a gear ring, a gear set 28 meshed with the gear ring is arranged below the gear ring, the gear set 28 comprises at least one driving wheel and a plurality of driven wheels, and the driving wheel is driven by a motor to rotate so as to drive the furnace body 21 to rotate. A choke plug 24 is arranged on the furnace neck 23 at one end provided with the opening, a compressed air inlet 25 and an ammonia outlet 26 are arranged on the choke plug 24, and a damp and hot air inlet 27 is connected with the compressed air pipeline 4, the ammonia pipeline 5 and the damp and hot air pipeline 6 respectively. The plug 24 and the furnace neck 23 can rotate relatively, namely, when the furnace body 21 rotates, the plug 24 does not rotate along with the furnace neck.

The system has the following advantages:

1. the system is simple in configuration and easy to manage and operate.

2. Energy conservation and consumption reduction. Compared with the urea solution spray pyrolysis, a large amount of water is not required to be vaporized at the same time, so that the energy consumption can be greatly reduced.

3. The system is highly integrated and occupies small area. Compared with the urea solution spray pyrolysis, a urea solution preparation system, a urea solution storage system and a urea solution conveying system are omitted, and the occupied area is greatly reduced.

4. There is no clogging of the system. The conveying of the solid materials in the system adopts spiral conveying and pneumatic conveying, so that no blockage exists.

5. The system operating temperature is 280 ℃ and is lower than that of a urea solution spray pyrolysis system (the operating temperature is more than 600 ℃); the operating pressure of the system is-1 to 6KPa, while the operating pressure of the current urea solution hydrolysis system is 2.2 MPa; therefore, the system operation difficulty is greatly reduced, and the system is safer and more reliable.

Although the specific embodiments of the present invention have been described with reference to the accompanying drawings, the scope of the present invention is not limited thereto, and some technical contents known to those skilled in the art will be omitted herein for brevity.

Claims

1. A urea pyrolysis system is characterized by comprising a feeding mechanism, a heating furnace mechanism, a preheating mechanism, a compressed air pipeline, an ammonia pipeline and a damp and hot air pipeline, wherein the feeding mechanism is arranged on the heating furnace mechanism; the feeding mechanism pipeline is connected with the compressed air pipeline; the preheating mechanism pipeline is connected with the wet hot air pipeline; the heating furnace mechanism comprises a rotatable furnace body and a heater; the feeding mechanism, the compressed air pipeline, the ammonia pipeline and the wet and hot air pipeline are all communicated with the inner cavity of the furnace body through pipelines; the compressed air pipeline can blow compressed air for urea conveyed by the feeding mechanism into the inner cavity of the furnace body, the ammonia gas pipeline can output ammonia gas generated in the inner cavity of the furnace body, the damp and hot air pipeline can heat damp air and input the damp air into the inner cavity of the furnace body, and the heater can heat the furnace body.

2. The urea pyrolysis system of claim 1, wherein the feeding mechanism comprises a feeding bin and a screw conveyor, an outlet of the feeding bin is connected with a feeding hole of the screw conveyor, and a compressed air feeding valve is arranged between a discharging hole of the screw conveyor and the compressed air pipeline.

3. The urea pyrolysis system of claim 1, wherein the compressed air line is provided with a compressed air storage tank.

4. The urea pyrolysis system of claim 1, wherein the preheating mechanism comprises a flue gas preheater and an electric heater.

5. The urea pyrolysis system of claim 1, wherein the ammonia line is provided with a first branch and a second branch which are connected in parallel, the first branch is provided with a first fan, and the second branch is provided with a second fan.

6. The urea pyrolysis system of claim 1, further comprising an atomizer coupled to the preheating mechanism.

7. The urea pyrolysis system of claim 1, wherein the heater is an electromagnetic heater disposed below the furnace body.

8. A urea pyrolysis system according to any one of claims 1 to 7 wherein a heat sink fan is provided below the heater.