CN212712774U

CN212712774U - Energy-saving urea pyrolysis system

Info

Publication number: CN212712774U
Application number: CN202020554926.6U
Authority: CN
Inventors: 蔡小峰; 徐力海
Original assignee: Beijing Huadian Hengxin Technology Development Co ltd
Current assignee: Beijing Huadian Hengxin Technology Development Co ltd
Priority date: 2020-04-15
Filing date: 2020-04-15
Publication date: 2021-03-16
Anticipated expiration: 2030-04-15

Abstract

The utility model relates to a flue gas denitration technical field especially relates to urea pyrolysis system. An energy efficient urea pyrolysis system comprising: a gas input device; the boiler is provided with a front smoke well region; the heat exchanger group is arranged close to the front smoke well area and is provided with a first air inlet and a first exhaust port; a pyrolysis furnace comprising a second inlet; the gas input device is respectively connected with the first gas inlet and the second gas inlet, and the first exhaust port is connected with the second gas inlet; and a urea solution atomization input device is arranged on the pyrolysis furnace. The technical scheme provided by the embodiment of the disclosure can have the following beneficial effects: the air is heated by the heat of the flue gas of the boiler and mixed with the urea solution, and the urea solution is pyrolyzed to generate ammonia and water, so that the preparation of the ammonia is effectively realized, the resources are saved, and the preparation cost of the ammonia is reduced.

Description

Energy-saving urea pyrolysis system

Technical Field

The disclosure relates to the technical field of flue gas denitration, in particular to an energy-saving urea pyrolysis system.

Background

Nitrogen oxides emitted from the tail gas of coal-fired boilers are the most main atmospheric pollutants. Because of higher pitot efficiency, the Selective Catalytic Reduction (SCR) flue gas denitration technology is generally adopted in the prior flue gas denitration. The urea is adopted in a power plant to prepare a reducing agent ammonia gas for denitration. The urea pyrolysis is one of the most main ammonia preparation, and the currently adopted general urea pyrolysis process has the main route that cold (hot) primary air is heated to about 650 ℃ through an electric heater or diesel oil and natural gas to be used as a urea pyrolysis and heat source, so that the energy consumption and the operation cost are high. The excessive energy consumption has certain influence on the economical efficiency of the operation of the unit. Or the energy consumption of the electric heater is reduced by additionally installing the gas-gas heat exchanger, but for the urea pyrolysis system engineering, the electric heating is required to be additionally installed, and the system investment is increased.

SUMMERY OF THE UTILITY MODEL

To overcome the problems in the related art, the present disclosure provides an energy efficient urea pyrolysis system.

According to an aspect of an embodiment of the present disclosure, there is provided an energy-saving urea pyrolysis system, including: a gas input device; the boiler is provided with a front smoke well region; the heat exchanger group is arranged close to the front smoke well area and is provided with a first air inlet and a first exhaust port; a pyrolysis furnace comprising a second inlet; the gas input device is respectively connected with the first gas inlet and the second gas inlet, and the first exhaust port is connected with the second gas inlet; and a urea solution atomization input device is arranged on the pyrolysis furnace.

In one embodiment, the heat exchanger group comprises a plurality of heat exchangers, an air inlet pipeline and an exhaust pipeline, the heat exchangers are connected with the air inlet pipeline and the exhaust pipeline, a first air inlet is formed in the air inlet pipeline, and a first exhaust port is formed in the first exhaust pipeline.

In one embodiment, the gas input device comprises: the air passage and the hot gas passage are connected with a first port of an input pipeline, and a second port of the input pipeline is respectively connected with a first air inlet and a second air inlet; the hot gas path is in communication with the boiler.

In one embodiment, a first regulating device and a filtering device are sequentially arranged on the hot gas passage in a direction from the boiler to the first port, the amount of hot gas input from the boiler is regulated by the first regulating device, and the hot gas is input to the gas input device after being filtered by the filtering device.

In one embodiment, a centrifugal fan or a boiler primary fan is provided on the air passage, and air is pressurized by the centrifugal fan or the boiler primary fan.

In one embodiment, a second regulating device is arranged between the input pipeline and the pyrolysis furnace, and the air volume of the air output from the input pipeline to the pyrolysis furnace is regulated through the second regulating device.

In one embodiment, the first and second regulating means each comprise a gate valve and a regulating valve.

In one embodiment, a regulating valve and a testing device are sequentially arranged on the input pipeline along the direction from the first port to the second port, and the testing device is used for testing the flow rate, the temperature and the pressure of the gas passing through the input pipeline.

In one embodiment, the urea solution atomization input device comprises an atomization nozzle arranged inside the pyrolysis furnace, and the atomization nozzle is connected with an external urea solution container through a pipeline.

In one embodiment, the pyrolysis furnace further comprises a second exhaust port, the urea solution is mixed with the gas input through the second gas inlet to generate ammonia gas, and the ammonia gas is output through the second exhaust port; and a temperature sensor is arranged at the second exhaust port.

The technical scheme provided by the embodiment of the disclosure can have the following beneficial effects:

the air is heated by the heat of the flue gas of the boiler and mixed with the urea solution, and the urea solution is pyrolyzed to generate ammonia and water, so that the preparation of the ammonia is effectively realized, the resources are saved, and the preparation cost of the ammonia is reduced.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.

FIG. 1 is a schematic diagram illustrating an energy efficient urea pyrolysis system according to an exemplary embodiment of the present disclosure.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the invention, as detailed in the appended claims.

According to an aspect of an embodiment of the present disclosure, as shown in fig. 1, there is provided an energy-saving urea pyrolysis system, including: a gas input device 3; the boiler 1 is used for generating high-temperature smoke dust through combustion, a front smoke well region 11 is arranged on the boiler 1, and the high-temperature smoke dust is discharged through the front smoke well region 11; the heat exchanger group 2 is arranged close to the front smoke well region 11, and the heat exchanger group 2 is provided with a first air inlet and a first air outlet; a pyrolysis furnace 4 including a second air inlet; the gas input device 3 is respectively connected with the first gas inlet and the second gas inlet, and the first exhaust port is connected with the second gas inlet; and a urea solution atomization input device 5 is arranged on the pyrolysis furnace 4.

Introduce a part of ambient gas through gas input device 3 and set up in boiler 1's preceding cigarette wellsite 11, the high temperature smoke and dust that boiler 1 produced is discharged through preceding cigarette wellsite 11, and heat exchanger group 2 is close to preceding cigarette wellsite 11 and sets up, and when the high temperature flue gas was discharged through preceding cigarette wellsite 11, heat ambient gas through high temperature flue gas, input pyrolysis oven 4 with the gas after heating. Another part of the environmental gas is directly input into the pyrolysis furnace 4 through the gas input device 3, and the low-temperature gas and the high-temperature gasThe gases are mixed in the pyrolysis furnace 4, and the temperature of the high-temperature gas is adjusted by the low-temperature gas, so that the temperature is controlled within a preset range. The urea solution is atomized by the urea solution atomization input device 5 and then injected into the pyrolysis furnace 4, so that the atomized urea solution is fully mixed with gas, and ammonia (NH) containing SCR reducing agent for denitration is generated after pyrolysis₃). And denitration is carried out on the flue gas generated by the boiler through the prepared ammonia gas. Urea solution sprays into pyrolysis oven 4 after atomizing, compares with the method of directly inputing the urea solution into pyrolysis oven 4 for urea solution can with gaseous intensive mixing, has solved urea solution effectively because the velocity of flow problem leads to the problem that urea pyrolysis conversion reduces, simultaneously, has solved urea solution and has directly sprayed into the stove, has the urea liquid drop to come not too late the reaction and the problem of piling up in the flue.

In the process, the ammonia gas is prepared by utilizing the principle that the urea solution is unstable at high temperature and can be decomposed into NH3 and HNCO, and the HNCO reacts with water to generate NH3 and CO2, so that the danger caused by directly inputting the ammonia gas is effectively solved. The smoke heated in the boiler 1 is used for heating the gas, no additional heating equipment is needed, the cost for preparing ammonia gas is effectively reduced, and meanwhile, resources are saved.

The reaction of the ammonia pyrolysis process is as follows:

the process for denitrating the smoke dust by ammonia gas comprises the step of reacting a reactant NH3 with nitrogen oxides (NOx) x in smoke gas in a boiler to generate nitrogen (N2) and water (H20) which are harmless to the environment.

The main reaction is described below:

in the urea pyrolysis system of this disclosure, introduce gas through gas input device 3, with gas input setting heat exchanger group 2 in boiler 1, heat exchanger group 2 is close to the preceding cigarette well area 11 setting of boiler 1, at the vertical setting in the top of boiler 1. The high-temperature flue gas in the boiler 1 is discharged to the outside of the boiler 1 through the front flue gas trap zone 11, and heats the gas in the heat exchanger group 2 provided in the front flue gas trap zone 11.

The temperature of urea pyrolysis needs to be controlled within a preset range, generally between 350 ℃ and 650 ℃, if the lowest temperature cannot be reached, the urea solution cannot be fully decomposed, waste is caused, the preparation amount of ammonia gas is reduced, and particularly, the temperature is more difficult to rise to the lowest required temperature in a short time by introducing ambient air into a high-temperature area and heating the ambient air by using high-temperature flue gas in the boiler 1. Therefore, when the ambient air is input, high temperature gas needs to be introduced at the same time. In view of the above, two gas input channels, namely an air channel 31 and a hot gas channel 32, are included in the gas input device 3 of the present disclosure, wherein the hot gas channel 32 is connected to the boiler 1 and introduces the gas heated in the boiler 1. A centrifugal fan or a boiler primary fan is provided on the air passage 31, and the air is pressurized by the centrifugal fan or the boiler primary fan. Air and hot gas are fed into the heat exchanger package 2 through the feed line 33, the heated gas being used to regulate the temperature of the air.

In some fields, for example, increasing the energy of gas heated in a power plant after the gas passes through the rotation of a turbine is effective in increasing the amount of electricity generated. Therefore, the input amount of hot gas needs to be controlled in the urea pyrolysis system, the hot gas required by normal production is not influenced, and energy is saved. The direction from the boiler to the first port is sequentially provided with a first adjusting device 321 and a filtering device 322 in the hot gas channel 32, the input amount of hot gas is adjusted by the first adjusting device 321, the first adjusting device 321 comprises a gate valve 3211 and an adjusting valve 3212, and in this embodiment, the gate valve 3211 and the adjusting valve 3212 adopt an electric gate valve and an electric adjusting valve. When the temperature of air introduced into the air passage 31 meets the requirement of final temperature, the gate valve 3211 is closed, when the temperature is required to be raised, the gate valve 3211 is opened to introduce hot air, and the amount of the introduced hot air is adjusted by the adjusting valve 3212. The final desired temperature is the temperature of the ammonia gas discharged from the pyrolysis furnace. The hot gas introduced from the boiler is mixed with a small amount of soot, affects the pyrolysis of the urea solution, and is deposited in the urea pyrolysis system, and thus the soot is filtered by the filtering device 322 after the hot gas passes through the first adjusting device 321. In this embodiment, the filter device 322 is a centrifugal filter device.

The introduced gas is input through a first port of the input pipeline 33, a part of the gas is input into the heat exchanger group 2 through a second port of the input pipeline 33 through a first gas inlet of the heat exchanger group 2, the gas is heated to a temperature higher than a preset temperature to form high-temperature gas, and the high temperature gas is input into the pyrolysis furnace 4 through a first exhaust port of the heat exchanger group 2 and a second gas inlet of the pyrolysis furnace 4. A regulating valve 34 is provided on the inlet line 33 for regulating the amount of gas introduced to ensure a concentration of < 5% ammonia at the second outlet of the pyrolysis furnace 4. The flow, temperature and pressure of the gas are detected by the testing device 35 after the gas has been adjusted in flow by the regulating valve 34, and therefore the testing device 35 comprises flow, temperature and pressure detectors. In the present embodiment, the regulating valve 34 is an electric regulating valve.

In order to improve the heating efficiency of the introduced gas, the heat exchanger group 2 consists of a plurality of heat exchangers, each heat exchanger is provided with an air inlet and an air outlet, all the air inlets are connected with an air inlet pipeline, and a first air inlet is arranged on the air inlet pipeline. All the exhaust ports are connected with an exhaust pipeline, and a first exhaust port is arranged on the exhaust pipeline. After the gas passes through the plurality of heat exchangers, the heat exchange area is increased, and the gas heating efficiency is improved.

Another part of the introduced gas is directly inputted to the pyrolysis furnace 4 through the second gas inlet as a low temperature gas, and the low temperature gas is used to adjust the temperature of the high temperature gas inputted to the pyrolysis furnace 4. And adjusting the temperature of the high-temperature gas according to the temperature of the discharged ammonia gas, and inputting the low-temperature gas for adjustment when the temperature of the discharged ammonia gas is higher than the preset temperature. And stopping inputting the low-temperature gas when the temperature of the discharged ammonia gas is lower than the preset temperature. A second regulating device 36 is therefore provided between the second port of the inlet duct 33 and the second inlet of the pyrolysis furnace 4. As with the first adjusting device 321, the second adjusting device 36 includes a gate valve 361 and a regulating valve 362, and in the present embodiment, the gate valve 361 and the regulating valve 362 adopt an electric gate valve and an electric regulating valve. When the high-temperature gas does not exceed the maximum preset temperature, the gate valve 361 is in a closed state, when the high-temperature gas exceeds the maximum preset temperature, the gate valve 361 is opened to introduce the low-temperature gas, and the amount of the introduced low-temperature gas is adjusted by the adjusting valve 362. In the present embodiment, the maximum preset temperature is 650 ℃.

The high temperature gas is mixed with a urea solution in the pyrolysis furnace 4, and the urea solution is pyrolyzed in the pyrolysis furnace 4 to form ammonia and carbon dioxide. In order to sufficiently pyrolyze the urea solution, an atomizing nozzle 51 is provided inside the pyrolysis furnace 4, and the atomizing nozzle 51 is connected to an external urea solution container through a pipe. Become the urea solution spraying through atomizing nozzle 51 with urea solution, be convenient for with the gaseous intensive mixing of high temperature, abundant pyrolysis urea solution effectively improves the output of ammonia, has reduced piling up of urea solution in pyrolysis oven 4.

The pyrolysis furnace 4 further comprises a second exhaust port, the urea solution is mixed with the gas input through the second air inlet to generate ammonia gas, and the ammonia gas is output through the second exhaust port. A temperature sensor 6 is provided at the second exhaust port. The temperature sensor 6 is used for testing the temperature of the ammonia gas discharged from the pyrolysis furnace 4, and when the temperature of the discharged ammonia gas is lower than a design value, the temperature of the air fed into the system is increased by adjusting the adjusting valve 3212, so that the temperature of the discharged ammonia gas is kept constant. When the temperature of the discharged ammonia gas is higher than the designed value, the flow of the low-temperature gas is adjusted by the adjusting valve 362, the temperature of the mixed air entering the second air inlet of the pyrolysis furnace 4 is reduced, and the stability of the system is guaranteed.

Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

It will be understood that the invention is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. An energy-efficient urea pyrolysis system, comprising:

a gas input device;

the boiler is provided with a front smoke well region;

the heat exchanger group is arranged close to the front smoke well area and is provided with a first air inlet and a first exhaust port;

a pyrolysis furnace comprising a second inlet;

the gas input device is respectively connected with the first gas inlet and the second gas inlet, and the first exhaust port is connected with the second gas inlet;

and a urea solution atomization input device is arranged on the pyrolysis furnace.

2. The energy efficient urea pyrolysis system of claim 1,

the heat exchanger group comprises a plurality of heat exchangers, an air inlet pipeline and an exhaust pipeline, the heat exchangers are connected with the air inlet pipeline and the exhaust pipeline, a first air inlet is formed in the air inlet pipeline, and a first exhaust port is formed in the exhaust pipeline.

3. The energy efficient urea pyrolysis system of claim 2, wherein the gas input device comprises:

the air passage and the hot gas passage are connected with a first port of an input pipeline, and a second port of the input pipeline is respectively connected with a first air inlet and a second air inlet;

the hot gas path is in communication with the boiler.

4. The energy efficient urea pyrolysis system of claim 3,

the hot gas channel is sequentially provided with a first adjusting device and a filtering device in the direction from the boiler to the first port, the amount of hot gas input from the boiler is adjusted through the first adjusting device, and the hot gas is input into the gas input device after being filtered through the filtering device.

5. The energy efficient urea pyrolysis system of claim 3,

and a centrifugal fan or a primary boiler fan is arranged on the air channel, and air is pressurized through the centrifugal fan or the primary boiler fan.

6. The energy efficient urea pyrolysis system of claim 4,

and a second adjusting device is arranged between the input pipeline and the pyrolysis furnace, and the air quantity of the air output from the input pipeline to the pyrolysis furnace is adjusted through the second adjusting device.

7. The energy efficient urea pyrolysis system of claim 6,

the first adjusting device and the second adjusting device both comprise gate valves and adjusting valves.

8. The energy efficient urea pyrolysis system of claim 6,

and the input pipeline is sequentially provided with a regulating valve and a testing device along the direction from the first port to the second port, and the testing device is used for testing the flow, the temperature and the pressure of the gas passing through the input pipeline.

9. The energy efficient urea pyrolysis system of claim 1,

urea solution atomizing input device including set up in inside atomizing nozzle of pyrolysis oven, atomizing nozzle passes through the pipeline and is connected with outside urea solution container.

10. The energy efficient urea pyrolysis system of claim 9,

the pyrolysis furnace also comprises a second exhaust port, the urea solution is mixed with the gas input through the second air inlet to generate ammonia gas, and the ammonia gas is output through the second exhaust port;

and a temperature sensor is arranged at the second exhaust port.