Analyzed gas heating system for reducing nitrogen oxide content

Abstract

The utility model relates to the technical field of desorbed gas treatment, in particular to a desorbed gas heating system for reducing nitrogen oxide content, which comprises a first pipeline, the first pipeline surrounds the outer side surface of a heating furnace, a plurality of branch pipelines are connected onto the first pipeline, and the tail ends of the branch pipelines extend into a hearth of the heating furnace and are connected with a burner I; the combustors I are uniformly distributed in an equal-radius manner by taking the midpoint of the inner bottom surface of the hearth of the heating furnace as a circle center; the center of the bottom of the heating furnace is connected with a second pipeline, and the outlet end of the second pipeline extends out of the bottom face of the hearth and is provided with a second combustor. A connecting pipeline is connected between the second pipeline and the first pipeline, and a third valve is arranged on the connecting pipeline. Two heating modes of the heating furnace are achieved by additionally arranging the connecting pipeline, when desorption gas is sufficient, the desorption gas directly enters the first combustor through the first pipeline and the branch pipeline, distributed combustion in the hearth is achieved, the content of nitric oxide is reduced, and cost reduction and efficiency improvement are achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of analytical gas treatment, and particularly relates to an analytical gas heating system for reducing the content of nitrogen oxides. Background Art

[0002] The hydrocracking workshop is an important production department in the petrochemical industry, mainly responsible for the hydrocracking process in the petroleum refining process. The heating furnace is one of the production equipment in the hydrocracking workshop. The gas fuel in the heating furnace is usually a mixed gas of fuel gas and analytical gas. The main component of the fuel gas is methane, and the methane content can account for more than 90%. Usually, it needs to be purchased, and its components are stable. The analytical gas is a by-product generated in the production process of the petrochemical industry. The main components are carbon monoxide, carbon dioxide and hydrogen. The hydrogen content can account for more than 50%. Its characteristics are explosive, large pressure fluctuation and low calorific value. It is collected according to the actual production situation and cannot be taken at any time as needed. When the fuel gas and the analytical gas are co-fired and heated in the heating furnace, the flow ratio of the two is usually 1:1. The fuel gas is distributed and burned through its supporting burner at the bottom of the furnace chamber, and the analytical gas is centrally burned by its supporting burner. The co-firing of the fuel gas and the analytical gas usually has the following problems:

[0003] When the fuel gas and the analytical gas are co-fired, the heating temperature inside the furnace chamber is too high, about above 900 °C. High-temperature heating will generate a high content of nitrogen oxides, which cannot meet the increasingly strict nitrogen oxide emission standards. Theoretically, by reducing the oxygen content of the oxygen-containing gas (usually including air) introduced into the heating furnace, the temperature during combustion can be reduced, thereby reducing the generation amount of nitrogen oxides. However, if the oxygen content is too low, incomplete combustion will occur, which is prone to safety hazards. At present, the common treatment method in enterprises is to replace the conventional burner with a low-nitrogen burner, but the low-nitrogen burner is expensive, and the replacement will increase the production cost. Content of the Utility Model

[0004] Aiming at the technical problem that the co-firing of fuel gas and analytical gas in the heating furnace often causes the nitrogen oxide content to exceed the standard and alarm, and the existing transformation cost is relatively high, the utility model provides an analytical gas heating system for reducing the nitrogen oxide content. By adding a connecting pipeline, two heating methods of the heating furnace are realized. When the analytical gas is sufficient, the analytical gas directly enters the burner 1 through the first pipeline and the branch pipeline to realize its distributed combustion in the furnace chamber, which not only significantly reduces the nitrogen oxide content, but also realizes cost reduction and efficiency increase.

[0005] The technical solution of the utility model is as follows:

[0006] An analytical gas heating system for reducing the nitrogen oxide content, comprising a first pipeline which surrounds the outer side of a heating furnace. A number of branch pipelines are connected to the first pipeline, and the ends of the branch pipelines extend into the furnace chamber of the heating furnace and are connected with a burner I, and the burner I is uniformly distributed at an equal radius with the midpoint of the inner bottom surface of the heating furnace chamber as the center;

[0007] The center of the bottom of the heating furnace is connected with a second pipeline, and the outlet end of the second pipeline extends out of the bottom surface of the furnace chamber. A burner II is arranged at the outlet end of the second pipeline;

[0008] A connecting pipeline is connected between the second pipeline and the first pipeline. A valve III is arranged on the connecting pipeline. A valve I is arranged upstream of the intersection point of the first pipeline and the connecting pipeline. A valve II is arranged on the second pipeline between the intersection point of the second pipeline and the connecting pipeline and the heating furnace.

[0009] Further, the number of the branch pipelines is the same as the number of the burner I, and the number of the burner I is not less than three.

[0010] Further, the number of the burner I is eight.

[0011] Further, an air inlet pipeline is also connected to the bottom of the heating furnace.

[0012] Oxygen-containing gas is introduced into the bottom of the heating furnace chamber through the air inlet pipeline.

[0013] Further, an air outlet pipeline is connected to the top of the heating furnace.

[0014] Further, an alarm device is arranged on the air outlet pipeline.

[0015] The beneficial effects of the utility model are as follows:

[0016] The utility model provides an analytical gas heating system for reducing the nitrogen oxide content, and realizes two heating modes of the heating furnace by adding a connecting pipeline.

[0017] When the analytical gas is sufficient, there is no need to burn additional fuel gas. The analytical gas directly enters the burner I through the first pipeline and the branch pipelines, reducing the combustion temperature from about 900 °C before to below 800 °C. Without reducing the oxygen content in the furnace chamber or installing a low-nitrogen burner, the nitrogen oxide content after combustion can be significantly reduced, solving the long-term alarm problem caused by the excessive nitrogen oxide content, and eliminating potential safety hazards such as flash explosion that may be brought about by significantly reducing the oxygen content of the oxygen-containing gas in the heating furnace. Moreover, compared with installing a low-nitrogen burner, the transformation cost is reduced by about 60,000 yuan. By adopting this heating mode, the full utilization of the analytical gas is realized, and there is no situation where the unutilized analytical gas needs to enter the compressor of the flare system for re-pressurization and then be injected into the fuel system during use, wasting material and energy resources, which is more environmentally friendly and economical.

[0018] When the analytical gas is insufficient, the pipeline is switched through the valve setting, so that the fuel gas and all the analytical gas can be temporarily co-fired and heated in the heating furnace. Usually, due to the insufficient amount of analytical gas, without adjusting the amount of oxygen-containing gas introduced, the combustion temperature of the heating furnace will not exceed 900 °C, and the situation of excessive nitrogen oxides will be correspondingly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 It is a schematic diagram of the analytical gas heating system of the present invention.

[0021] Figure 2 It is a top view of the inside of the furnace chamber of the heating furnace of the analytical gas heating system of the present invention.

[0022] In the figure, 1 - heating furnace, 2 - first pipeline, 3 - second pipeline, 4 - connecting pipeline, 5 - valve one, 6 - valve two, 7 - valve three, 8 - branch pipeline, 9 - air inlet pipeline, 10 - outlet pipeline, 11 - alarm device, 12 - burner one, 13 - burner two. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] Embodiment 1

[0025] Refer to Figure 1 - Figure 2 , an analytical gas heating system for reducing the content of nitrogen oxides, including a first pipeline 2, the first pipeline 2 surrounds the outer side of the heating furnace 1, several branch pipelines 8 are connected to the first pipeline 2, the end of each branch pipeline 8 extends into the furnace chamber of the heating furnace 1 and is respectively connected to a burner one 12, the number of burners one 12 is eight, and the burners one 12 are evenly distributed at equal radii with the midpoint of the inner bottom surface of the furnace chamber of the heating furnace 1 as the center;

[0026] The center of the bottom of the heating furnace 1 is connected to a second pipeline 3. The outlet end of the second pipeline 3 extends out of the bottom surface of the furnace chamber, and a burner two 13 is provided at the outlet end of the second pipeline 3;

[0027] A connecting pipeline 4 is connected between the second pipeline 3 and the first pipeline 2. A valve three 7 is arranged on the connecting pipeline 4. A valve one 5 is arranged upstream of the confluence point of the first pipeline 2 and the connecting pipeline 4. A valve two 6 is arranged on the second pipeline 3 between the confluence point of the second pipeline 3 and the connecting pipeline 4 and the heating furnace 1. The bottom of the heating furnace 1 is also connected to an air inlet pipeline 9. The top of the heating furnace is connected to an air outlet pipeline 10. An alarm device 11 is arranged on the air outlet pipeline 10.

[0028] According to the actual production situation, when the output of the analysis gas is sufficient, there is no need to use fuel gas, and the first heating method is adopted:

[0029] The valve one 5 and the valve two 6 are closed, and the valve three 7 is opened. The analysis gas enters the burner one 12 of the heating furnace 1 through the first pipeline 2 and the branch pipeline 8. The oxygen-containing gas (the oxygen content of which is 3%-5% stipulated in the national standard) enters the furnace chamber from the air inlet pipeline 9, and the distributed combustion of the analysis gas is realized. The combustion gas is discharged through the air outlet pipeline 10. The alarm device 11 arranged on the air outlet pipeline 10 monitors the nitrogen oxide content in the discharged gas.

[0030] At this time, when the oxygen-containing gas with an oxygen content of 3%-5% is introduced into the air inlet pipeline 9, the temperature in the heating furnace drops below 800 °C, and the generated nitrogen oxide content is 25-45 mg / m 3 , which is significantly lower than the set value of the DSC alarm system (the set value is lower than the current nitrogen oxide emission standard, for example, the set value is 80 mg / m 3 ), and will not trigger the alarm of the alarm device 11. This heating method does not need to use the purchased fuel gas, and also omits the step of treating the remaining analysis gas entering the flare system, reducing the cost and realizing the full utilization of the waste gas of the by-product analysis gas.

[0031] According to the actual production situation, when the output of the analysis gas is insufficient, the purchased fuel gas is used, and the second heating method is adopted:

[0032] The oxygen-containing gas enters the furnace chamber from the air inlet pipeline 9. The valve three 7 on the connecting pipeline 4 is closed, and the valve one 5 and the valve two 6 are opened, so that the fuel gas is decompressed and enters the burner one 12 in the furnace chamber through the first pipeline 2 and the branch pipeline 8 for distributed combustion. The analysis gas enters the furnace chamber directly through the second pipeline 3 and is centrally combusted through the burner two 13 arranged at the outlet end of the second pipeline 3.

[0033] At this time, due to the small amount of by-product gas released by analysis, the temperature of the heating furnace during co-firing usually does not exceed 900 °C, and the situation of excessive nitrogen oxides will be correspondingly reduced. The alarm device monitors at any time. If there is a tendency of exceeding the standard, the heating of the heating furnace will be suspended in time to prevent non-compliance of gas emissions caused by excessive nitrogen oxides. According to the actual production situation, when the gas volume released by analysis is sufficient again, the first heating method will be switched back.

[0034] Although the present invention has been described in detail by referring to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, those of ordinary skill in the art can make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions should all be within the scope covered by the present invention / Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention.

Claims

1. A desorption gas heating system for reducing nitrogen oxide content, comprising a first pipeline (2), characterized in that: The first pipe (2) surrounds the outer side of the heating furnace (1), and a plurality of branch pipes (8) are connected to the first pipe (2). The ends of the branch pipes (8) extend into the furnace of the heating furnace and are connected to burner 1 (12). The burner 1 (12) is evenly distributed with equal radii with the midpoint of the bottom surface of the furnace of the heating furnace (1) as the center of the circle; A second pipe (3) is connected to the center of the bottom of the heating furnace (1), the outlet end of the second pipe (3) extends out of the bottom surface of the furnace, and a second burner (13) is provided at the outlet end of the second pipe (3); A connecting pipe (4) is connected between the second pipe (3) and the first pipe (2), a valve three (7) is arranged on the connecting pipe (4), a valve one (5) is arranged upstream of the intersection of the first pipe (2) and the connecting pipe (4), and a valve two (6) is arranged on the second pipe (3) between the intersection of the second pipe (3) and the connecting pipe (4) and the heating furnace (1).

2. A desorption gas heating system for reducing nitrogen oxide content as claimed in claim 1, characterized in that: The number of branch pipes (8) is the same as the number of burner one (12), and the number of burner one (12) is not less than three.

3. A desorption gas heating system for reducing nitrogen oxide content as claimed in claim 2, characterized in that: The number of burners one (12) is eight.

4. The desorption gas heating system for reducing nitrogen oxide content according to claim 1, characterized in that: The bottom of the heating furnace (1) is also connected to an air inlet duct (9).

5. The analytical gas heating system for reducing nitrogen oxide content according to claim 1, characterized in that: The top of the heating furnace is connected to a gas outlet pipe (10).

6. A desorption gas heating system for reducing nitrogen oxide content as claimed in claim 5, characterized in that: An alarm device (11) is provided on the air outlet pipe (10).

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