Waste gas recycling system for low-heating-value gas double-hearth shaft kiln

Abstract

The waste gas recycling system comprises a left kiln chamber, a right kiln chamber, a spray gun, a left heat exchange chamber, a right heat exchange chamber, a dust removal chamber, a cooling chamber, a waste gas circulating chamber and a carbon dioxide recovery chamber, a connecting channel is arranged between the left kiln chamber and the right kiln chamber; spray guns and spray gun cooling air pipes I are arranged at the upper part of the left kiln chamber; spray guns and spray gun cooling air pipes II are arranged at the upper part of the right kiln chamber; a carbon dioxide concentration detection device is arranged in the waste gas circulation chamber; the spray gun of the left kiln chamber is connected with a fuel pipe I; the spray gun of the right kiln chamber is connected with a fuel pipe II; according to the utility model, high-temperature waste gas after cooling and dust removal is used as material cooling air and spray gun cooling air instead of cooling air, so that the concentration of carbon dioxide in the waste gas can be improved; combustion-supporting air is preheated through heat of high-temperature waste gas, and energy can be saved.

Description

Technical Field

[0001] The utility model relates to the technical field of metallurgical lime production, in particular to a low calorific value coal gas double-chamber vertical kiln waste gas recycling system. Background Art

[0002] The double-chamber vertical kiln has mature and advanced calcination principles and control technologies, and is recognized as an advanced kiln type in the lime production industry. In addition, the auxiliary equipment of the double-chamber vertical kiln is mature and reliable, and its operation control has reached a high degree of automation and intelligence.

[0003] During the calcination process of the double-bore vertical kiln, due to the combustion of fuel, the introduction of cooling air, combustion-supporting air and other gases will emit a large amount of waste gas, which contains a large amount of carbon dioxide and has a high temperature. my country's economy has shifted from a high-speed growth stage to a high-quality development stage. Energy conservation and carbon reduction play an important role in promoting the green and low-carbon development of the industry. In the context of the country's promotion of energy conservation and carbon reduction, recycling the waste gas from the double-bore vertical kiln can effectively improve the efficiency of energy resource utilization and help reduce carbon emissions from the source.

[0004] The purification and utilization of carbon dioxide gas can be applied to many fields with high added value, including metallurgy, lime, chemical industry, food, etc. Journal of Mining Engineering, 2004, Vol. 2, No. 4, pp. 60-62, the process of recovering and producing liquid carbon dioxide from lime kilns includes two processes: carbon dioxide recovery and enrichment and compression and liquefaction. Due to the sensitivity of the carbon dioxide recovery process to the carbon dioxide concentration in the exhaust gas of the double-chamber shaft kiln, increasing the carbon dioxide concentration in the exhaust gas of the double-chamber shaft kiln is an effective means to reduce the cost of carbon dioxide recovery.

[0005] Invention patent CN116477854A discloses a lime kiln equipment and control method based on carbon emission reduction, which introduces a mixture of pure oxygen and carbon dioxide as combustion-supporting air to increase the concentration of carbon dioxide in the flue gas at the end of the lime kiln. However, pure oxygen increases the cost during the kiln calcination process, and on the other hand, the principle of fuel combustion is affected by changing the composition of the combustion-supporting gas, and the chemical balance of the calcination zone will also change. In addition, the patent does not utilize the heat in the exhaust gas, resulting in energy waste. Summary of the invention

[0006] The utility model provides a low calorific value coal gas double-chamber vertical kiln waste gas recycling system and a control method thereof. The utility model can increase the concentration of carbon dioxide in the waste gas by using the waste gas after cooling and dust removal to replace cooling air as material cooling air and spray gun cooling air; and can save energy by using the heat of high-temperature waste gas to preheat combustion air.

[0007] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0008] A low calorific value coal gas double-chamber vertical kiln waste gas recycling system, comprising a left kiln chamber, a right kiln chamber, a spray gun, a left heat exchange chamber, a right heat exchange chamber, a dust removal chamber, a cooling and lowering chamber, a waste gas circulation chamber, and a carbon dioxide recovery chamber; a connecting passage is provided between the left kiln chamber and the right kiln chamber; a spray gun and a first spray gun cooling air duct are provided on the upper part of the left kiln chamber; a spray gun and a second spray gun cooling air duct are provided on the upper part of the right kiln chamber; a carbon dioxide concentration detection device is provided in the waste gas circulation chamber; the spray gun of the left kiln chamber is connected to a first fuel pipe; the spray gun of the right kiln chamber is connected to a second fuel pipe;

[0009] The bottom of the left heat exchange chamber is connected to the exhaust port at the top of the left kiln chamber through an external exhaust pipe 1, and the bottom of the left heat exchange chamber is connected to the air inlet at the top of the left kiln chamber through a combustion air branch pipe 3; the top of the left heat exchange chamber is respectively connected to a dust removal branch pipe 1 and a combustion air branch pipe 1;

[0010] The bottom of the right heat exchange chamber is connected to the exhaust port at the top of the right kiln chamber through the external exhaust pipe 2, and the bottom of the right heat exchange chamber is connected to the air inlet at the top of the right kiln chamber through the combustion air branch pipe 4; the top of the right heat exchange chamber is respectively connected to the dust removal branch pipe 2 and the combustion air branch pipe 2; the combustion air branch pipe 3 is connected to the combustion air branch pipe 4 through the combustion air branch pipe 5;

[0011] The dust removal sub-pipe 1 and the dust removal sub-pipe 2 are connected to the dust removal chamber, and the dust removal chamber is connected to the cooling chamber through a pipeline; the cooling chamber is connected to the exhaust gas circulation chamber through a cooling pipe 1; the exhaust gas circulation chamber is connected to the carbon dioxide recovery chamber through a recovery pipe;

[0012] The side of the left heat exchange chamber is connected to the air change duct 1, and the side of the right heat exchange chamber is connected to the air change duct 2. The air change duct 1 and the air change duct 2 are connected to the exhaust gas circulation chamber after being combined;

[0013] The exhaust gas circulation chamber is connected to one end of the cooling pipe 2, and the other end of the cooling pipe 2 is divided into two paths, one of which is the cooling branch pipe 1, which is respectively connected to the spray gun cooling air duct 1 and the spray gun cooling air duct 2; the other is the cooling branch pipe 2, which is respectively connected to the bottom of the left kiln chamber and the bottom of the right kiln chamber;

[0014] The combustion-supporting air branch pipe 1 is provided with a switch valve 1; the combustion-supporting air branch pipe 2 is provided with a switch valve 2; the combustion-supporting air branch pipe 3 is provided with a switch valve 3; the combustion-supporting air branch pipe 4 is provided with a switch valve 4; the switch valve 3 is located between the exhaust port at the top of the left kiln chamber and the intersection of the combustion-supporting air branch pipe 3 and the combustion-supporting air branch pipe 5; the switch valve 4 is located between the exhaust port at the top of the right kiln chamber and the intersection of the combustion-supporting air branch pipe 4 and the combustion-supporting air branch pipe 5;

[0015] The fuel pipe one is provided with an on-off valve five; the fuel pipe two is provided with an on-off valve six; the spray gun cooling air duct one is provided with an on-off valve seven; the spray gun cooling air duct two is provided with an on-off valve eight; the dust removal branch pipe one is provided with an on-off valve nine, and the dust removal branch pipe two is provided with an on-off valve ten; the air change duct one is provided with an on-off valve eleven, and the air change duct two is provided with an on-off valve twelve; the cooling pipe one is provided with an on-off valve thirteen; the recovery pipe is provided with an on-off valve fourteen; the connection between the cooling branch pipe two and the bottom of the left kiln chamber is provided with an on-off valve fifteen, and the connection between the cooling branch pipe two and the bottom of the right kiln chamber is provided with an on-off valve sixteen.

[0016] The structure of the left heat exchange chamber is the same as that of the right heat exchange chamber; a serpentine tube is provided inside the left heat exchange chamber, one end of the serpentine tube is connected to the combustion-supporting air branch pipe one, and the other end is connected to the combustion-supporting air branch pipe three; a serpentine tube is provided inside the right heat exchange chamber, one end of the serpentine tube is connected to the combustion-supporting air branch pipe two, and the other end is connected to the combustion-supporting air branch pipe four; ash discharge ports are provided at the bottom of the left heat exchange chamber and the right heat exchange chamber.

[0017] The ash discharge ports are respectively arranged on both sides of the bottom of the left heat exchange chamber and the right heat exchange chamber.

[0018] Compared with the prior art, the beneficial effects of the utility model are:

[0019] 1) In the utility model, the high-temperature exhaust gas generated by calcination in the left or right kiln chamber preheats the combustion air, which can reduce the heat absorbed by the combustion air entering the kiln chamber, thereby saving combustion energy.

[0020] 2) The utility model uses the high-temperature exhaust gas as cooling air after dust removal to replace cooling air to cool the spray gun and materials, thereby increasing the concentration of carbon dioxide in the exhaust gas and reducing the cost of carbon dioxide recovery.

[0021] 3) In the utility model, a serpentine pipe is provided in the left heat exchange chamber (right heat exchange chamber) to increase the heat exchange area and improve the heat exchange effect; in addition, the low-temperature exhaust gas is introduced into the side of the left heat exchange chamber, which can change the flow direction of the high-temperature exhaust gas and flow it to the serpentine pipe, so that the high-temperature exhaust gas and the combustion-supporting air can better exchange heat; the ash discharge port at the bottom of the left heat exchange chamber is regularly opened for cleaning, which can extend the service life of the subsequent dust collector. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the accompanying drawings:

[0023] Figure 1 It is a schematic diagram of the utility model system.

[0024] Figure 2 It is a partial schematic diagram of the system of the utility model.

[0025] Figure 3 It is a schematic diagram of the left heat exchange chamber of the utility model.

[0026] Figure 4 It is a working schematic diagram of the left heat exchange chamber of the utility model.

[0027] Description of reference numerals:

[0028] In the figure: 1-left kiln chamber 2-right kiln chamber 3-spray gun 4-left heat exchange chamber 5-right heat exchange chamber 6-dust removal chamber 7-cooling and cooling chamber 8-exhaust gas circulation chamber 9-carbon dioxide recovery chamber 10-connecting channel 11-spray gun cooling air duct 1 12-spray gun cooling air duct 2 13-fuel pipe 1 14-fuel pipe 2 15-exhaust pipe 1 16-exhaust pipe 2 17-combustion air branch pipe 1 18-combustion air branch pipe 2 19-combustion air branch pipe 3 20-combustion air branch pipe 4 21-combustion air branch pipe 5 22-dust removal branch pipe 1 23-dust removal branch pipe Tube 224-air changer 125-air changer 226-cooling tube 127-cooling tube 228-cooling branch tube 129-cooling branch tube 230-recovery tube31-on / off valve 132-on / off valve 233-on / off valve 334-on / off valve 435-on / off valve 536-on / off valve 637-on / off valve 738-on / off valve 839-on / off valve 940-on / off valve 1041-on / off valve 1142-on / off valve 1243-on / off valve 1344-on / off valve 1445-on / off valve 1546-on / off valve 1647-serpentine tube48-ash discharge port DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0030] The specific implementation of the utility model is further described below in conjunction with the accompanying drawings:

[0031] See Figures 1 to 4 As shown, the utility model relates to a low calorific value coal gas double-chamber vertical kiln waste gas recycling system, comprising a left kiln chamber 1, a right kiln chamber 2, a spray gun 3, a left heat exchange chamber 4, a right heat exchange chamber 5, a dust removal chamber 6, a cooling and lowering chamber 7, a waste gas circulation chamber 8, and a carbon dioxide recovery chamber 9. A connecting passage 10 is provided between the left kiln chamber 1 and the right kiln chamber 2, a spray gun 3 and a spray gun cooling air duct 1 11 are provided on the upper part of the left kiln chamber 1, and a spray gun 3 and a spray gun cooling air duct 2 12 are provided on the upper part of the right kiln chamber 2. A carbon dioxide concentration detection device is provided in the waste gas circulation chamber 8.

[0032] The spray gun 3 of the left kiln chamber is connected to the fuel pipe 1 13, and the spray gun 3 of the right kiln chamber is connected to the fuel pipe 2 14. The fuel pipe 1 13 and the fuel pipe 2 14 are connected to the fuel source.

[0033] The bottom of the left heat exchange chamber 4 is connected to the exhaust port at the top of the left kiln chamber 1 through an external exhaust pipe 15, and the bottom of the left heat exchange chamber 4 is connected to the air inlet at the top of the left kiln chamber 1 through a combustion air branch pipe 3 19. The top of the left heat exchange chamber 4 is connected to a dust removal branch pipe 22 and a combustion air branch pipe 17 respectively.

[0034] The bottom of the right heat exchange chamber 5 is connected to the exhaust port at the top of the right kiln chamber 2 through the second external exhaust pipe 16, and the bottom of the right heat exchange chamber 5 is connected to the air inlet at the top of the right kiln chamber 2 through the fourth combustion air branch pipe 20. The top of the right heat exchange chamber 5 is respectively connected to the second dust removal branch pipe 23 and the second combustion air branch pipe 18. The third combustion air branch pipe 19 is connected to the fourth combustion air branch pipe 20 through the fifth combustion air branch pipe 21.

[0035] The dust removal branch pipe 1 22 and the dust removal branch pipe 2 23 are connected to the dust removal chamber 6, and the dust removal chamber 6 is connected to the cooling chamber 7 through a pipeline. The cooling chamber 7 is connected to the exhaust gas circulation chamber 8 through the cooling pipe 1 26. The exhaust gas circulation chamber 8 is connected to the carbon dioxide recovery chamber 9 through the recovery pipe 30.

[0036] The side of the left heat exchange chamber 4 is connected to the air change duct 1 24 , and the side of the right heat exchange chamber 5 is connected to the air change duct 2 25 . The air change duct 1 24 and the air change duct 2 25 are connected to the exhaust gas circulation chamber 8 after being combined.

[0037] The exhaust gas circulation chamber 8 is connected to one end of the cooling pipe 27, and the other end of the cooling pipe 27 is divided into two paths. One path is a cooling branch pipe 28, which is respectively connected to the spray gun cooling air duct 11 and the spray gun cooling air duct 2 12; the other path is a cooling branch pipe 29, which is respectively connected to the bottom of the left kiln chamber 1 and the right kiln chamber 2.

[0038] A switch valve one 31 is provided on the combustion-supporting air branch pipe one 17, a switch valve two 32 is provided on the combustion-supporting air branch pipe two 18, a switch valve three 33 is provided on the combustion-supporting air branch pipe three 19, and a switch valve four 34 is provided on the combustion-supporting air branch pipe four 20. The switch valve three 33 is located between the exhaust port at the top of the left kiln chamber 1 and the intersection of the combustion-supporting air branch pipe three 19 and the combustion-supporting air branch pipe five 21, and the switch valve four 34 is located between the exhaust port at the top of the right kiln chamber 2 and the intersection of the combustion-supporting air branch pipe four 20 and the combustion-supporting air branch pipe five 21.

[0039] A switch valve 5 35 is provided on the fuel pipe 13, and a switch valve 6 36 is provided on the fuel pipe 2 14. A switch valve 7 37 is provided on the spray gun cooling air pipe 1 11, and a switch valve 8 38 is provided on the spray gun cooling air pipe 2 12. A switch valve 9 39 is provided on the dust removal branch pipe 1 22, and a switch valve 10 40 is provided on the dust removal branch pipe 2 23. A switch valve 11 41 is provided on the variable air pipe 1 24, and a switch valve 12 42 is provided on the variable air pipe 2 25. A switch valve 13 43 is provided on the cooling pipe 1 26, and a switch valve 14 44 is provided on the recovery pipe 30. A switch valve 15 45 is provided at the connection between the cooling branch pipe 2 29 and the bottom of the left kiln chamber 1, and a switch valve 16 46 is provided at the connection between the cooling branch pipe 2 29 and the bottom of the right kiln chamber 2.

[0040] The left heat exchange chamber 4 has the same structure as the right heat exchange chamber 5. A serpentine tube 47 is provided inside the left heat exchange chamber 4, one end of which is connected to the combustion air branch pipe 1 17, and the other end is connected to the combustion air branch pipe 3 19. A serpentine tube 46 is provided inside the right heat exchange chamber 5, one end of which is connected to the combustion air branch pipe 2 18, and the other end is connected to the combustion air branch pipe 4 20. Ash discharge ports 48 are provided at the bottom of the left heat exchange chamber 4 and the right heat exchange chamber 5. The ash discharge ports 48 are arranged on both sides of the bottom of the left heat exchange chamber 4 and the right heat exchange chamber 5.

[0041] The control method of the utility model comprises the following steps:

[0042] (1) Taking the calcination of the right kiln chamber 2 as an example, the switch valve 6 36 is opened, the switch valve 5 35 is in a closed state, the fuel enters the spray gun 3 of the right kiln chamber 2 through the fuel pipe 2 14, and the spray gun 3 sprays the fuel into the right kiln chamber 2. At the same time, the switch valve 1 31 and the switch valve 4 34 are opened, the switch valve 2 32 and the switch valve 3 33 are in a closed state, the combustion air enters the right kiln chamber 2 through the left heat exchange chamber 4, the fuel and the combustion air are calcined in the calcination zone of the right kiln chamber 2, the combustion smoke is mixed with the spray gun cooling air pipe 2 12 and the cooling air sprayed from the bottom of the right kiln chamber 2, and after mixing, enters the left kiln chamber 1 through the connecting channel 10, and is discharged from the exhaust port at the top of the left kiln chamber 1.

[0043] (2) After passing through the left heat exchange chamber 4, the high-temperature exhaust gas discharged enters the dust removal chamber 6 and the cooling chamber 7 in sequence. When the high-temperature exhaust gas enters the left heat exchange chamber 4, it can preheat the combustion air flowing through the left heat exchange chamber 4.

[0044] (3) After dust removal and cooling, the high-temperature exhaust gas is transformed into low-temperature exhaust gas and enters the exhaust gas circulation chamber 8. The switch valve 8 38, the switch valve 11 41, the switch valve 15 45 and the switch valve 16 46 are opened. A part of the low-temperature exhaust gas in the exhaust gas circulation chamber 8 enters the left heat exchange chamber 4 through the air change pipe 1 24, which can change the flow direction of the high-temperature exhaust gas and flow to the serpentine pipe, thereby improving the heat exchange efficiency between the high-temperature exhaust gas and the combustion air; another part of the low-temperature exhaust gas is sprayed into the right kiln chamber 2 through the spray gun cooling air pipe 2 12 to replace the cooling air to cool the spray gun 3; another part enters the left kiln chamber 1 and the right kiln chamber 2 through the bottom of the left kiln chamber 1 and the right kiln chamber 2 respectively, replacing the cooling air to cool the materials in the kiln chamber; the low-temperature exhaust gas is mixed with the combustion flue gas to form high-temperature exhaust gas again.

[0045] (4) The high-temperature exhaust gas formed in step (3) circulates in the system according to steps (1), (2) and (3). When the carbon dioxide concentration detection device in the exhaust gas circulation chamber 8 detects that the carbon dioxide concentration reaches the post-recovery standard, the switch valve 14 44 is opened, and a part of the low-temperature exhaust gas in the exhaust gas circulation chamber 8 enters the carbon dioxide recovery chamber 9; the rest is still circulated in the system.

[0046] (5) When the left kiln chamber 1 and the right kiln chamber 2 are switched for calcination, the above steps are repeated, but the opening and closing operations of the relevant valves are reversed.

[0047] In the step (4), when the carbon dioxide concentration detection device detects that the carbon dioxide concentration reaches 45% or above, the switch valve 14 44 is opened to recover the carbon dioxide.

[0048] The ash discharge port 48 at the bottom of the left heat exchange chamber 4 and the right heat exchange chamber 5 is opened regularly for dust removal. A weight detection device can be set at the ash discharge port. When the dust accumulation reaches a certain weight, an alarm is issued to remind the worker to open the ash discharge port for dust removal.

[0049] In step (1), when the right kiln chamber 2 begins the calcination stage and no high-temperature exhaust gas is generated, the combustion air is not preheated when passing through the left heat exchange chamber 4. Moreover, at this time, in the right kiln chamber, the cooling air duct 12 of the spray gun and the cooling air ejected from the bottom of the right kiln chamber 2 are both cooling air. After the high-temperature exhaust gas circulates in the system, the combustion air is preheated when passing through the left heat exchange chamber 4, and the cooling air ejected from the cooling air duct 12 of the spray gun and the bottom of the right kiln chamber 2 is replaced by the exhaust gas after dust removal and cooling.

[0050] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, and these simple modifications all belong to the protection scope of the present invention. It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations. In addition, the various different embodiments of the present invention can also be arbitrarily combined, as long as they do not violate the idea of ​​the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A low calorific value coal gas double-chamber vertical kiln waste gas recycling system, characterized in that: It includes a left kiln chamber, a right kiln chamber, a spray gun, a left heat exchange chamber, a right heat exchange chamber, a dust removal chamber, a cooling and cooling chamber, an exhaust gas circulation chamber, and a carbon dioxide recovery chamber; a connecting passage is provided between the left kiln chamber and the right kiln chamber; a spray gun and a spray gun cooling air duct 1 are provided on the upper part of the left kiln chamber; a spray gun and a spray gun cooling air duct 2 are provided on the upper part of the right kiln chamber; a carbon dioxide concentration detection device is provided in the exhaust gas circulation chamber; the spray gun of the left kiln chamber is connected to a fuel pipe 1; the spray gun of the right kiln chamber is connected to a fuel pipe 2; The bottom of the left heat exchange chamber is connected to the exhaust port at the top of the left kiln chamber through an external exhaust pipe 1, and the bottom of the left heat exchange chamber is connected to the air inlet at the top of the left kiln chamber through a combustion air branch pipe 3; the top of the left heat exchange chamber is respectively connected to a dust removal branch pipe 1 and a combustion air branch pipe 1; The bottom of the right heat exchange chamber is connected to the exhaust port at the top of the right kiln chamber through the external exhaust pipe 2, and the bottom of the right heat exchange chamber is connected to the air inlet at the top of the right kiln chamber through the combustion air branch pipe 4; the top of the right heat exchange chamber is respectively connected to the dust removal branch pipe 2 and the combustion air branch pipe 2; the combustion air branch pipe 3 is connected to the combustion air branch pipe 4 through the combustion air branch pipe 5; The dust removal sub-pipe 1 and the dust removal sub-pipe 2 are connected to the dust removal chamber, and the dust removal chamber is connected to the cooling chamber through a pipeline; the cooling chamber is connected to the exhaust gas circulation chamber through a cooling pipe 1; the exhaust gas circulation chamber is connected to the carbon dioxide recovery chamber through a recovery pipe; The side of the left heat exchange chamber is connected to the variable air duct 1, and the side of the right heat exchange chamber is connected to the variable air duct 2. The variable air duct 1 and the variable air duct 2 are connected to the exhaust gas circulation chamber after being combined; The exhaust gas circulation chamber is connected to one end of the cooling pipe 2, and the other end of the cooling pipe 2 is divided into two paths, one of which is the cooling branch pipe 1, which is respectively connected to the spray gun cooling air duct 1 and the spray gun cooling air duct 2; the other is the cooling branch pipe 2, which is respectively connected to the bottom of the left kiln chamber and the bottom of the right kiln chamber; The combustion-supporting air branch pipe 1 is provided with a switch valve 1; the combustion-supporting air branch pipe 2 is provided with a switch valve 2; the combustion-supporting air branch pipe 3 is provided with a switch valve 3; the combustion-supporting air branch pipe 4 is provided with a switch valve 4; the switch valve 3 is located between the exhaust port at the top of the left kiln chamber and the intersection of the combustion-supporting air branch pipe 3 and the combustion-supporting air branch pipe 5; the switch valve 4 is located between the exhaust port at the top of the right kiln chamber and the intersection of the combustion-supporting air branch pipe 4 and the combustion-supporting air branch pipe 5; The fuel pipe one is provided with an on-off valve five; the fuel pipe two is provided with an on-off valve six; the spray gun cooling air duct one is provided with an on-off valve seven; the spray gun cooling air duct two is provided with an on-off valve eight; the dust removal branch pipe one is provided with an on-off valve nine, and the dust removal branch pipe two is provided with an on-off valve ten; the air change duct one is provided with an on-off valve eleven, and the air change duct two is provided with an on-off valve twelve; the cooling pipe one is provided with an on-off valve thirteen; the recovery pipe is provided with an on-off valve fourteen; the connection between the cooling branch pipe two and the bottom of the left kiln chamber is provided with an on-off valve fifteen, and the connection between the cooling branch pipe two and the bottom of the right kiln chamber is provided with an on-off valve sixteen.

2. The low calorific value coal gas double-chamber vertical kiln waste gas recycling system according to claim 1 is characterized in that: The structure of the left heat exchange chamber is the same as that of the right heat exchange chamber; a serpentine tube is provided inside the left heat exchange chamber, one end of the serpentine tube is connected to the combustion-supporting air branch pipe one, and the other end is connected to the combustion-supporting air branch pipe three; a serpentine tube is provided inside the right heat exchange chamber, one end of the serpentine tube is connected to the combustion-supporting air branch pipe two, and the other end is connected to the combustion-supporting air branch pipe four; ash discharge ports are provided at the bottom of the left heat exchange chamber and the right heat exchange chamber.

3. The low calorific value coal gas double-chamber vertical kiln waste gas recycling system according to claim 2 is characterized in that: The ash discharge ports are respectively arranged on both sides of the bottom of the left heat exchange chamber and the right heat exchange chamber.

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