CN109059012B - Ground torch closed combustor exhaust gas denitration system and method - Google Patents

Abstract

The present disclosure provides a ground flare closed burner evacuation gas denitration system and method, wherein the evacuation gas denitration system includes: the device comprises SCR denitration equipment, a first branch pipe, a first pneumatic valve, a gas pipe, a second pneumatic valve, a second branch pipe and a third pneumatic valve; the air inlet of the SCR denitration device is connected with the second end of the burner exhaust pipeline, and the air outlet of the SCR denitration device is connected with the emptying gas pipeline; the first branch pipe is connected with a burner air inlet pipeline and a burner exhaust pipeline; the first pneumatic valve is arranged on the first branch pipe; the gas pipe is connected with the first branch pipe; the second pneumatic valve is arranged on the gas pipe; the second branch pipe is connected with the emptying gas pipeline and the burner; the third pneumatic valve is disposed on the second branch pipe. The present disclosure is effective in reducing NO _x And the discharge amount and the production cost of the waste gas can be effectively utilized.

Description

Ground torch closed burner exhaust gas denitrification system and method

Technical field

The present disclosure relates to the field of burner exhaust gas treatment, and in particular to a ground torch closed burner exhaust gas denitration system and method.

Background technique

With the deterioration of the global environment and the gradual strengthening of people's environmental awareness, the pollution caused to the atmospheric environment by NO _x and PM in exhaust gases emitted by chemical plants has attracted widespread attention from the international community. Today, with the rapid development of the petrochemical industry, petroleum refining, chemicals, plastics and other petrochemical and subsequent production units, due to the scale and mutual connection of these production units, there will be a large number of emissions during startup and shutdown, normal production and accidental emissions. Flare gas is vented. Flare gas is waste gas generated during the production process of the petrochemical industry. It is a flammable, explosive, toxic and harmful gas, such as CH ₄ , CH ₃ OH, NH ₃ , O ₂ , H ₂ S, H ₂ , etc. Because it is extremely harmful, in order to ensure the system stability and safety of the production device, direct venting cannot be used. A torch system should be set up to burn it in a timely and safe manner. The commonly used treatment methods are elevated torch systems or ground Torch system.

With the development of greenhouse gas emission reduction and international trading of carbon dioxide, China has begun to use ground torches to burn combustible waste gas to meet the goals of efficient combustion and monitoring of combustion status. Compared with elevated torches, ground torches have the characteristics of small footprint, high burnout rate, easy maintenance, no light pollution, low noise, and low heat radiation. The exhaust gas emissions have complex components, including high-pressure and ultra-low-pressure flare gases, conventional hydrocarbon gases and corrosive gases. The processing capacity of a single-cylinder ground torch is generally less than or equal to 100t/h. The torch gas is burned staged in the burner, using high-energy spark ignition. The body of the ground closed burner is cylindrical, which can achieve a completely closed combustion process, thereby avoiding the flame leakage during combustion, and there is no fire outside, so its Avoid light pollution and reduce heat radiation. The ground burner is cylindrical, not affected by temperature and rain, and has good noise reduction and sound absorption performance. Therefore, the torch gas is burned in a closed space, and it has rainproof, heat insulation, noise reduction and other effects to minimize the impact of the combustion process on the environment. In a ground torch enclosed burner, the combustion center temperature of the burner can reach a maximum temperature of over 1850°C.

Due to the large amount of waste gas treatment and the diversity of combustion gases, other toxic and harmful gases, including soot, NO _x, etc., will be secondary produced after combustion in the current ground flare burner. Under high temperature and oxygen-rich conditions, N ₂ in the burner will react with O ₂ in the combustion chamber to generate NO, and NO will be rapidly oxidized to NO ₂ . NO _x is an acid-causing gas and an important precursor for the occurrence of photochemical smog. The fine particulate matter (PM10/PM2.5) formed by it will cause the occurrence of haze weather, so the emission of NO _x must be strictly controlled. In addition, domestic chemical plants are currently using ground flare burners to treat ammonia emissions. The flare gas only contains ammonia, and the ammonia is burned directly in the burner. At present, there are very few domestic technologies related to the treatment of ground flare exhaust gas. Therefore, more in-depth research is needed on the denitrification treatment of exhaust gas after burner combustion.

Contents of the invention

(1) Technical problems to be solved

The present disclosure provides a ground torch closed burner exhaust gas denitration system and method to at least partially solve the above technical problems.

(2) Technical solutions

According to one aspect of the present disclosure, a ground flare closed burner exhaust gas denitration system is provided. The ground flare closed burner is provided with a burner air inlet and a burner exhaust port, and the flare gas is introduced through the burner. The burner air inlet is connected to the burner air inlet pipe, and the burner exhaust port is connected to the burner exhaust pipe; among them, the ground torch closed burner exhaust gas denitrification system includes : The first branch pipe, the first end of the first branch pipe is connected to the burner air inlet pipe, and the second end of the first branch pipe is connected to the burner exhaust pipe; SCR denitrification equipment is provided with an SCR denitrification equipment air inlet and an SCR denitrification equipment. Exhaust port; the air inlet of the SCR denitrification equipment is connected to the second end of the burner exhaust pipeline, and the exhaust port of the SCR denitrification equipment is connected to the exhaust gas pipeline; the first pneumatic valve is set on the first branch pipe to control the first The input SCR denitrification equipment for the flare gas in the branch pipe; the gas transmission pipe is connected to the first branch pipe; the second pneumatic valve is set on the gas transmission pipe to control the input of NH3 to the first branch pipe through the gas transmission pipe; the second branch pipe, the second branch pipe One end is connected to the vent gas pipeline, the second end of the second branch pipe is connected to the burner; the third pneumatic valve is arranged on the second branch pipe.

In some embodiments of the present disclosure, the SCR denitration equipment includes: a rectifying grid, a first-stage catalytic layer, and a second-stage catalytic layer; the rectifying grid, the first-stage catalytic layer, and the second-stage catalytic layer are provided in the SCR denitration equipment. within, and are set up sequentially from the air inlet of the SCR denitrification equipment to the exhaust port of the SCR denitrification equipment.

In some embodiments of the present disclosure, the SCR denitration equipment further includes: a backup catalytic layer disposed between the second-stage catalytic layer and the exhaust port of the SCR denitration equipment.

In some embodiments of the present disclosure, the method further includes: a baffle plate disposed on the exhaust pipe of the burner.

In some embodiments of the present disclosure, the first, second and third pneumatic valves are pneumatic butterfly valves.

According to another aspect of the present disclosure, a method for denitrification of exhaust gas from a ground torch closed burner is provided, which includes: passing the torch gas into the burner for combustion; the first pneumatic valve is closed, the second pneumatic valve is opened, and the gas is passed through the output The NH3 introduced into the air pipe merges with the flue gas discharged through the burner exhaust pipe through the first branch pipe to form a mixed gas; the mixed gas enters the SCR denitrification equipment for denitration and is emptied through the vent gas pipeline.

According to another aspect of the present disclosure, a method for denitrification of exhaust gas from a ground-level torch closed burner is provided, which includes: passing the torch gas into the burner for combustion, opening the first pneumatic valve, and entering the first branch pipe; The second pneumatic valve opens, and the torch gas entering the first branch pipe merges with the NH3 flowing in the gas pipe; then it mixes with the flue gas discharged through the burner exhaust pipe through the first branch pipe to form a mixed gas; the mixed gas enters the SCR denitrification equipment To carry out denitration, the third pneumatic valve is opened, and the mixed gas flows back to the burner through the second branch for combustion.

(3) Beneficial effects

It can be seen from the above technical solutions that the ground torch closed burner exhaust gas denitration system and method of the present disclosure has at least one or part of the following beneficial effects:

(1) The present disclosure can effectively treat _NOx emissions from flare combustion, thereby improving the chemical plant and surrounding air environment.

(2) SCR denitrification equipment is easy to modify, has low reaction temperature, the catalyst does not contain precious metals, has a long service life, and can be applied to a variety of working conditions and various types of exhaust gas emissions.

(3) The ground-level torch closed burner can effectively utilize NH ₃ in the exhaust gas. It uses NH ₃ produced in chemical plants as the reducing agent. The raw materials are sufficient, convenient and easy to obtain, and the cost is low. It can reduce the amount of flare gas processing and improve efficiency. At the same time, denitrification and emission reduction are achieved.

(4) Use pneumatic butterfly valve for control, which has quick response, good reliability and is not easy to leak.

(5) The baffle can make the distribution of smoke more uniform in the longitudinal direction, and can also guide the movement of smoke by changing the size and shape of the baffle.

Description of the drawings

Figure 1 is a schematic structural diagram of the exhaust gas denitration system of a ground torch closed burner according to an embodiment of the present disclosure.

Figure 2 is a schematic flow chart of a denitration method for exhaust gas from a closed burner with a ground torch according to the first embodiment of the present disclosure.

FIG. 3 is a schematic flow chart of a method for denitrifying exhaust gas from a ground torch closed burner according to the second embodiment of the present disclosure.

[Explanation of main component symbols in the embodiments of the present disclosure in the drawings]

10-burner;

11-Burner air inlet;

12-Burner exhaust port;

20-burner air inlet pipe;

30-burner exhaust pipe;

31-Deflector;

40-first branch pipe;

41-First pneumatic valve;

50-gas pipe;

51-Second pneumatic valve

60-SCR denitration equipment;

61-rectifier grille

64-First level catalytic layer;

62-Second stage catalytic layer;

63- spare catalytic layer;

70-Second branch pipe;

71-Third pneumatic valve;

80-Bleed gas lines.

Detailed ways

The present disclosure provides a ground torch closed burner exhaust gas denitration system and method, wherein the ground torch closed burner exhaust gas denitration system includes: a burner, a burner air inlet pipeline, and a burner exhaust pipeline , first branch pipe, SCR denitration equipment, first pneumatic valve, gas transmission pipe, second pneumatic valve, second branch pipe and third pneumatic valve; the burner is equipped with a burner air inlet and a burner exhaust port; the torch gas passes through The burner air inlet enters the burner; the burner air inlet pipeline is connected to the burner air inlet; the first end of the burner exhaust pipeline is connected to the burner exhaust port; the first end of the first branch pipe is connected to the burner air inlet pipe The second end of the first branch pipe is connected to the burner exhaust pipeline; the SCR denitrification equipment is provided with an SCR denitrification equipment air inlet and an SCR denitrification equipment exhaust port; the SCR denitrification equipment air inlet is connected to the burner exhaust pipe The second end is connected, and the exhaust port of the SCR denitration equipment is connected to the vent gas pipeline; the first pneumatic valve is set on the first branch pipe to control the input of the torch gas in the first branch pipe to the SCR denitration equipment; the gas transmission pipe is connected to the first branch pipe; The second pneumatic valve is arranged on the gas pipeline to control the input of NH3 to the first branch pipe through the gas pipeline; the first end of the second branch pipe is connected to the exhaust gas pipeline, and the second end of the second branch pipe is connected to the burner; the third pneumatic valve Set on the second branch pipe.

In order to make the purpose, technical solutions and advantages of the present disclosure more clear, the present disclosure will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

Certain embodiments of the present disclosure are described more fully below with reference to the accompanying drawings, some, but not all, of which are shown. Indeed, various embodiments of the disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth in this number; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements.

In an exemplary embodiment of the present disclosure, a ground flare closed burner exhaust gas denitration system is provided. Figure 1 is a schematic structural diagram of the exhaust gas denitration system of a ground torch closed burner according to an embodiment of the present disclosure. As shown in Figure 1, the ground torch closed burner exhaust gas denitration system includes: burner 10, burner air inlet pipe 20, burner exhaust pipe 30, first branch pipe 40, SCR denitrification equipment 60, A pneumatic valve 41, a gas pipe 50, a second pneumatic valve 51, a second branch pipe 70 and a third pneumatic valve 71; the burner 10 is provided with a burner air inlet 11 and a burner exhaust port 12; the torch gas passes through the burner The air inlet 11 enters the burner 10; the burner air inlet pipeline 20 is connected to the burner air inlet 11; the first end of the burner exhaust pipeline 30 is connected to the burner exhaust port 12; the first end of the first branch pipe 40 It is connected to the burner air inlet pipeline 20, and the second end of the first branch pipe 40 is connected to the burner exhaust pipeline 30; the SCR denitrification equipment 60 is provided with an SCR denitrification equipment air inlet and an SCR denitrification equipment exhaust port; the SCR denitrification equipment inlet The gas port is connected to the second end of the burner exhaust pipeline 30, and the SCR denitration equipment exhaust port is connected to the vent gas pipeline 80; the first pneumatic valve 41 is set on the first branch pipe 40 to control the torch gas in the first branch pipe 40 input; the gas pipeline 50 is connected to the first branch pipe 40, and the second pneumatic valve 51 is provided on the gas pipeline 50 to control the input of NH ₃ to the first branch pipe 40 through the gas pipeline 50. The first end of the second branch pipe 70 is connected to the vent gas pipeline 80 , and the second end of the second branch pipe 70 is connected to the burner 10 ; the third pneumatic valve 71 is provided on the second branch pipe 70 .

The SCR denitrification equipment 60 used in this disclosure includes: a rectifying grid 61, a first-level catalytic layer 64, a second-level catalytic layer 62, and a backup catalytic layer 63; The first-stage catalytic layer 62 and the backup catalytic layer 63 are arranged in the SCR denitration equipment 60 and are arranged in sequence from the air inlet of the SCR denitration equipment to the exhaust port of the SCR denitration equipment. Selective catalytic reduction post-processor (SCR), a selective catalytic reduction technology using urea aqueous solution as the reducing agent, can effectively reduce _NOx emissions in an oxygen-rich reaction environment with variable flow, temperature and components. The current efficiency is as high as 95%. Widely used in denitrification of automobiles, ships, coal-fired boilers, and garbage incinerators. Commonly used SCR catalysts include vanadium-based catalysts and zeolite-type catalysts, and generally use 32.5% urea aqueous solution as the reducing agent, which is injected into the exhaust gas through air-assisted injection. Since the actual reducing agent that reacts with _NOx in the catalyst is ammonia (NH ₃ ) generated by hydrolysis of urea, NH ₃ is directly introduced into the first branch pipe 40 as the reducing agent here. Two catalyst layers and a backup catalyst layer are provided in the SCR denitrification equipment 60 to ensure sufficient catalysis, and the catalyst is a vanadium-based catalyst. Generally, the _NOx distribution upstream of the rectification grid 61, the ammonia injection flow distribution, the mixing distance and other parameters will affect the distribution uniformity of _NOx and _NH3 on the surface of the first catalyst layer.

Among them, the burner exhaust pipe 30 is also provided with a guide plate 31 to make the distribution of the flue gas more uniform in the longitudinal direction. In a specific implementation, the size and shape of the guide plate 31 can also be changed to guide the flue gas. sports. The burner 10 is a surface torch closed burner. The combustion of the torch gas is completely completed in a cylindrical combustion chamber. The flame is completely closed and the fire light cannot be seen from the outside. There is no light pollution, which reduces thermal radiation and heat conduction and reduces combustion noise. In the general embodiment, the diameter of the combustion chamber barrel is 6000mm, and the wall thickness is 8mm.

The pneumatic butterfly valve selected for the first pneumatic valve 41 , the second pneumatic valve 51 and the third pneumatic valve 71 in this disclosure has the characteristics of fast action, good reliability, less leakage and low cost.

In a first embodiment of the present disclosure, a method for denitrification of exhaust gas from a ground torch closed burner is provided. Figure 2 is a schematic flow chart of a denitration method for exhaust gas from a closed burner with a ground torch according to the first embodiment of the present disclosure. As shown in Figure 2, it includes: the torch gas is introduced into the burner for combustion; the first pneumatic valve is closed, the second pneumatic valve is opened, and the NH ₃ introduced through the gas pipe passes through the first branch pipe and the burner exhaust pipe The discharged flue gases merge to form a mixed gas; the mixed gas enters the SCR denitrification equipment for denitrification and is emptied through the vent gas pipeline. This embodiment is mainly applicable when the flare gas contains hydrocarbons and other emissions.

In a second embodiment of the present disclosure, a ground torch closed burner exhaust gas denitration method is provided. FIG. 3 is a schematic flow chart of a method for denitrifying exhaust gas from a ground torch closed burner according to the second embodiment of the present disclosure. As shown in Figure 3, it includes: the torch gas is introduced into the burner for combustion, the first pneumatic valve is opened, and the torch gas enters the first branch pipe; the second pneumatic valve is opened, and the torch gas entering the first branch pipe is connected with the gas pipe. NH ₃ is combined; then mixed with the flue gas discharged through the burner exhaust pipe through the first branch pipe to form a mixed gas; the mixed gas enters the SCR denitrification equipment for denitration, the third pneumatic valve opens, and the mixed gas returns through the second branch until burned out in the burner. In this embodiment, ammonia in the flare gas itself is used as the reducing agent to complete denitration and utilize waste gas at the same time to achieve the effect of reducing costs.

So far, the embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. It should be noted that implementation methods not shown or described in the drawings or the text of the specification are all forms known to those of ordinary skill in the technical field and have not been described in detail. In addition, the above definitions of each element and method are not limited to the various specific structures, shapes or methods mentioned in the embodiments, which can be simply modified or replaced by those of ordinary skill in the art.

Based on the above description, those skilled in the art should have a clear understanding of the ground flare closed burner exhaust gas denitration system of the present disclosure.

To sum up, the present disclosure provides a system and method for exhaust gas denitration of a ground torch closed burner that greatly reduces _NOx emissions and can also reduce costs and realize waste gas utilization.

It should also be noted that the directional terms mentioned in the embodiments, such as "up", "down", "front", "back", "left", "right", etc., are only for reference to the directions of the drawings, not used to limit the scope of the present disclosure. Throughout the drawings, the same elements are designated by the same or similar reference numerals. Conventional structures or constructions will be omitted where they may obscure the understanding of the present disclosure.

Moreover, the shapes and sizes of the components in the figures do not reflect the actual sizes and proportions, but only illustrate the contents of the embodiments of the present disclosure. Furthermore, in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

Unless expressly stated to the contrary, the numerical parameters in this specification and the appended claims are approximations that may vary depending on the desired characteristics derived from the teachings of this disclosure. Specifically, all numbers used in the specification and claims to express compositional contents, reaction conditions, etc. should be understood to be modified by the word "about" in all cases. In general, the meaning of the expression is to include a variation of ±10% in some embodiments, ±5% in some embodiments, ±1% in some embodiments, and ±1% in some embodiments. ±0.5% variation in the example.

Furthermore, the word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

The ordinal numbers used in the description and claims, such as "first", "second", "third", etc., are used to modify the corresponding elements. They themselves do not mean that the element has any ordinal number, nor do they mean that the element has any ordinal number. Represents the order of a certain component with another component, or the order in the manufacturing method. The use of these serial numbers is only used to clearly distinguish one component with a certain name from another component with the same name.

In addition, unless the steps are specifically described or must occur in sequence, the order of the above steps is not limited to those listed above and may be changed or rearranged according to the required design. Moreover, the above-mentioned embodiments can be mixed and matched with each other or with other embodiments based on design and reliability considerations, that is, the technical features in different embodiments can be freely combined to form more embodiments.

Similarly, it should be understood that in the above description of exemplary embodiments of the disclosure, various features of the disclosure are sometimes grouped together into a single embodiment in order to streamline the disclosure and assist in understanding one or more of the various disclosed aspects. figure, or its description. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed disclosure requires more features than are expressly recited in each claim. Rather, as the following claims reflect, disclosed aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this disclosure.

The above-mentioned specific embodiments further describe the purpose, technical solutions and beneficial effects of the present disclosure in detail. It should be understood that the above-mentioned are only specific embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this disclosure shall be included in the protection scope of this disclosure.

Claims (6)

1. The ground torch closed burner is provided with a burner air inlet and a burner air outlet, and torch gas enters the ground torch closed burner through the burner air inlet to complete combustion, flame is completely closed so that the outside cannot see fire light, the burner air inlet is connected with a burner air inlet pipeline, and the burner air outlet is connected with a burner air exhaust pipeline; wherein, ground torch closed combustor evacuation gas denitration system includes:

the first end of the first branch pipe is connected with the burner air inlet pipeline, and the second end of the first branch pipe is connected with the burner air outlet pipeline;

the SCR denitration device is provided with a rectification grating, an air inlet of the SCR denitration device and an air outlet of the SCR denitration device; the air inlet of the SCR denitration device is connected with the second end of the burner exhaust pipeline, the air outlet of the SCR denitration device is connected with the emptying gas pipeline, and the rectification grating is arranged in the SCR denitration device;

the first pneumatic valve is arranged on the first branch pipe and used for controlling the input of flare gas in the first branch pipe to SCR denitration equipment;

the gas transmission pipe is connected with the first branch pipe;

the second pneumatic valve is arranged on the gas pipe and used for controlling the input of NH3 to the first branch pipe through the gas pipe;

the first end of the second branch pipe is connected with the emptying gas pipeline, and the second end of the second branch pipe is connected with the burner;

the third pneumatic valve is arranged on the second branch pipe;

the guide plate is arranged on the exhaust pipeline of the burner.

2. The ground flare closed combustor evacuation gas denitration system of claim 1, the SCR denitration device further comprising: a first stage catalytic layer and a second stage catalytic layer;

the first-stage catalytic layer and the second-stage catalytic layer are arranged in the SCR denitration device, and the rectification grating, the first-stage catalytic layer and the second-stage catalytic layer are sequentially arranged from the air inlet of the SCR denitration device to the air outlet of the SCR denitration device.

3. The ground flare closed combustor evacuation gas denitration system of claim 2, the SCR denitration device further comprising: and the standby catalytic layer is arranged between the second-stage catalytic layer and the exhaust port of the SCR denitration device.

4. The ground flare closed combustor evacuation gas denitration system of claim 1, the first pneumatic valve, the second pneumatic valve, and the third pneumatic valve being pneumatic butterfly valves.

5. A ground flare closed burner exhaust gas denitration method based on the ground flare closed burner exhaust gas denitration system of any one of claims 1 to 4, comprising:

the flare gas is introduced into a burner for combustion;

the first pneumatic valve is closed, the second pneumatic valve is opened, and NH3 introduced through the gas transmission pipe is converged with the flue gas exhausted through the burner exhaust pipeline through the first branch pipe to form mixed gas;

the mixed gas enters SCR denitration equipment to be subjected to denitration, and is emptied through an emptying gas pipeline.

6. A ground flare closed burner exhaust gas denitration method based on the ground flare closed burner exhaust gas denitration system of any one of claims 1 to 4, comprising:

the flare gas is introduced into the burner for burning, the first pneumatic valve is opened, and the flare gas enters the first branch pipe;

the second pneumatic valve is opened, and the flare gas entering the first branch pipe is converged with NH3 introduced by the gas transmission pipe;

then the mixed gas is formed by mixing the first branch pipe with the flue gas exhausted by the burner exhaust pipe;

the mixed gas enters SCR denitration equipment to be subjected to denitration, a third pneumatic valve is opened, and the mixed gas flows back to the combustor through a second branch to burn out.