Start-up temperature raising system and start-up temperature raising method for sulfuric acid production device

Abstract

The present invention relates to the technical field of contact sulfuric acid production, and specifically to a start-up temperature-raising system and a start-up temperature-raising method for a sulfuric acid production device, wherein the system comprises: an incinerator, used for incinerating fuel to obtain high-temperature flue gas, wherein the high-temperature flue gas is divided into gas a and gas b; a waste heat furnace, used for introducing gas a into the waste heat furnace for heat exchange to obtain a first low-temperature flue gas; an air heater, connected to the incinerator, used for introducing heating gas into the air heater and exchanging heat with low-temperature air to obtain a second low-temperature flue gas and high-temperature air; a conversion reactor, connected to the air heater, used for exchanging heat between the high-temperature air and the conversion reactor to obtain preheated gas. The present invention preheats the catalyst bed in the conversion reactor by preheating the high-temperature flue gas generated by the incinerator during the start-up stage of the sulfuric acid production device, thereby saving electricity and making full use of the flue gas heat, thereby saving energy and protecting the environment.

Description

Technical Field

[0001] The invention relates to the technical field of contact process sulfuric acid production, and in particular to a start-up temperature raising system and a start-up temperature raising method for a sulfuric acid production device. Background Art

[0002] In the sulfuric acid production unit of the sulfuric acid industry, the optimal reaction temperature of the catalyst used in the conversion reaction of sulfur dioxide to sulfur trioxide is above 400°C. Before the sulfuric acid unit is put into operation and charged, an external heat source is required to heat the catalyst bed to the optimal reaction temperature, which is generally not less than 380°C.

[0003] At present, the sulfuric acid industry usually uses a resistive gas heating furnace to heat the dry air, and then preheats the catalyst bed with the heated air. The electric heating elements in the resistive gas heating furnace are bare resistance wire (strip), electric heating tube, and silicon carbide rod. Among them, silicon carbide rods are eliminated due to unstable quality and high burnout rate. Electric heating tubes are also rarely used due to excessive unit surface load and short life. Bare resistance wire (strip) electric furnaces have the disadvantages of large volume (some cannot be directly installed on the main line), large resistance, large weight, low thermal efficiency, partial shielding or mutual interference of resistance wires in the furnace, and uneven spatial distribution (sometimes a small group of electric heating elements are disabled, and the temperature distribution in the furnace is seriously uneven, with one side cold and the other side hot). After long-term heating, the electric furnace is deformed, making it difficult to seal the flange surface, and the maintenance workload is large.

[0004] In addition to electric heating furnaces, some large-scale sulfuric acid production plants are directly equipped with preheating furnaces and preheaters, using coal, gas or diesel as heat sources for heating. However, this method has high start-up energy consumption and cost, making it uneconomical and impractical.

[0005] For sulfuric acid plants with incinerators and waste heat furnaces, the steam generated during the furnace drying process is usually of low quality and is vented, so the heat source generated by this part of the furnace is wasted. Summary of the invention

[0006] The purpose of the present invention is to overcome the problem in the prior art that the steam generated by a sulfuric acid production device during the start-up furnace baking stage is directly discharged, resulting in a waste of heat source, and to provide a start-up temperature increase system and a start-up temperature increase method for the sulfuric acid production device.

[0007] The inventors of the present invention have discovered that in the existing sulfuric acid production device equipped with an incinerator and a waste heat furnace, electric heating is used to heat the conversion reactor during the preheating stage of start-up. The steam generated by the incinerator is usually of low quality after heat exchange in the waste heat furnace, and is generally directly vented, resulting in waste of the heat source generated by the drying furnace. However, using the high-temperature flue gas generated by the incinerator to preheat the conversion reactor can make full use of the heat in the flue gas and improve energy utilization.

[0008] In order to achieve the above-mentioned object, the first aspect of the present invention provides a start-up temperature raising system for a sulfuric acid production device, the system comprising:

[0009] An incinerator is used to burn fuel to obtain high-temperature flue gas, wherein the high-temperature flue gas is divided into a gas and a gas;

[0010] an air duct, connected to the incinerator, for delivering oxygen to the incinerator;

[0011] A waste heat furnace, connected to the incinerator through a pipeline, for introducing the a stream of gas into the waste heat furnace for heat exchange to obtain a first low-temperature flue gas;

[0012] An air heater is connected to the incinerator through a pipeline, and the pipeline is connected to the pipeline through a pipeline, and is used to introduce heating gas into the air heater and exchange heat with the low-temperature air in the air heater to obtain a second low-temperature flue gas and high-temperature air, wherein the heating gas is the b gas or a mixture of the b gas and the first low-temperature flue gas;

[0013] The conversion reactor is connected to the air heater and is used to introduce the high-temperature air into the conversion reactor for heat exchange to obtain preheated gas.

[0014] A second aspect of the present invention provides a start-up temperature raising method for a sulfuric acid production device, which is performed in the temperature raising system described in the first aspect; the start-up temperature raising method comprises:

[0015] In the presence of oxygen-containing gas, the fuel is burned to obtain high-temperature flue gas;

[0016] The high-temperature flue gas is used to directly or indirectly heat the waste heat furnace and / or the conversion reactor, and the flow rate of the high-temperature flue gas entering the waste heat furnace and / or the conversion reactor is controlled according to the temperature of the high-temperature flue gas.

[0017] Through the above technical scheme, the present invention uses the high-temperature flue gas generated by the incinerator preheating to preheat the catalyst bed in the conversion reactor during the preheating stage of the sulfuric acid production device, thereby fully utilizing the flue gas heat and greatly saving electric energy, thereby having the advantages of energy saving and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of a start-up temperature-raising system of a sulfuric acid production device according to one embodiment of the present invention.

[0019] Description of Reference Numerals

[0020] 1. Incinerator 2. Waste heat furnace

[0021] 3. Air heater 4. Conversion reactor

[0022] 41. First catalyst bed 42. Second catalyst bed

[0023] 43. Third catalyst bed 44. Fourth catalyst bed

[0024] 45. Fifth catalyst bed 5. First regulating valve

[0025] 6. First temperature sensor 7. Second regulating valve

[0026] 8. Oxygen concentration analysis device 9. Third regulating valve

[0027] 10. Second temperature sensor 11. Third temperature sensor

[0028] 18. Fifth valve 13. Pipeline

[0029] 14. Pipeline 15. Pipeline

[0030] 16. Air pipe 17. Fourth valve DETAILED DESCRIPTION

[0031] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0032] Figure 1 : is a schematic diagram of the structure of the start-up temperature raising system of the sulfuric acid production device according to one embodiment of the present invention, such as Figure 1 As shown, the first aspect of the present invention provides a start-up temperature raising system for a sulfuric acid production device, the system comprising:

[0033] The incinerator 1 is used to burn the fuel to obtain high-temperature flue gas, and the high-temperature flue gas is divided into gas a and gas b;

[0034] an air duct 16, which is in communication with the incinerator 1 and is used to deliver oxygen to the incinerator 1;

[0035] The waste heat furnace 2 is connected to the incinerator 1 through a pipeline 13, and is used to introduce the a stream of gas into the waste heat furnace 2 for heat exchange to obtain a first low-temperature flue gas;

[0036] The air heater 3 is connected to the incinerator 1 through a pipeline 14, and the pipeline 13 and the pipeline 14 are connected through a pipeline 15, and is used to introduce the heating gas into the air heater 3 and exchange heat with the low-temperature air in the air heater 3 to obtain a second low-temperature flue gas and high-temperature air, wherein the heating gas is the b gas or a mixed gas of the b gas and the first low-temperature flue gas;

[0037] The conversion reactor 4 is connected to the air heater 3 and is used to introduce the high-temperature air into the conversion reactor 4 for heat exchange to obtain preheated air.

[0038] The operation process of the existing sulfuric acid production device includes a preheating stage and a production stage. In the preheating stage, the conversion reactor is generally heated by electric heating. For sulfuric acid production devices with incinerators, fuel needs to be burned in the incinerator to preheat the incinerator; the production stage is a process of catalytically oxidizing sulfur dioxide produced by the combustion of sulfur-containing substances to generate sulfur trioxide, and then reacting sulfur trioxide with water to generate sulfuric acid.

[0039] The startup heating system of the sulfuric acid production device provided in the present invention is a system for preheating the incinerator and the conversion reactor during the startup preheating stage. The high-temperature flue gas generated by the combustion of fuel in the incinerator 1 is directly or indirectly heat-exchanged with low-temperature air to obtain high-temperature air, and then the high-temperature air is heat-exchanged with the conversion reactor 4 to preheat the conversion reactor 4 to a specific temperature, thereby fully utilizing the heat of the high-temperature flue gas and achieving the effect of energy saving and emission reduction.

[0040] The present invention can short-circuit the high-temperature flue gas from the waste heat furnace 2 by bridging the pipeline 13 and the pipeline 14 with the pipeline 15 , so that the high-temperature flue gas directly enters the air heat exchanger 3 .

[0041] In the present invention, a third temperature sensor 11 is further provided in the incinerator for monitoring the temperature of the high-temperature flue gas and controlling the flow direction of the high-temperature flue gas according to the temperature of the high-temperature flue gas.

[0042] In some preferred embodiments of the present invention, the pipeline 14 is provided with a first temperature sensor 6 for monitoring the temperature T1 of the heating gas; the pipeline 15 is provided with a first regulating valve 5, the first regulating valve 5 is electrically connected to the first temperature sensor 6, and is used to control the flow of the a gas and the b gas according to the value of T1. When the temperature T1 of the heating gas is high, the opening of the first regulating valve 5 can be reduced to reduce the flow of the b gas entering the pipeline 15 and increase the flow of the a gas entering the waste heat furnace 2, thereby reducing the temperature T1 of the heating gas; when the temperature T1 of the heating gas is low, the opening of the first regulating valve 5 can be increased to increase the flow of the b gas entering the pipeline 15 and reduce the flow of the a gas entering the waste heat furnace 2, thereby increasing the temperature T1 of the heating gas.

[0043] In the present invention, the temperature T1 of the heating gas is in the range of 440-460°C.

[0044] In some preferred embodiments of the present invention, in order to further improve the utilization rate of energy, the conversion reactor 4 is connected to the incinerator 1 to circulate the preheated gas into the incinerator 1 .

[0045] According to the present invention, in order to ensure complete combustion of the fuel, under preferred conditions, a second regulating valve 7 is provided on the pipe connecting the incinerator 16 and the air duct 1; an oxygen concentration analysis device 8 is provided in the incinerator 1, and the oxygen concentration analysis device 8 is electrically connected to the second regulating valve 7 for monitoring the oxygen concentration in the incinerator 1 and controlling the opening of the second regulating valve 7 according to the oxygen concentration.

[0046] In the present invention, the conversion reactor 4 includes n catalyst beds, which are, from bottom to top, the first catalyst bed, the second catalyst bed...the N-1th catalyst bed, the Nth catalyst bed, wherein n≥1. Under preferred conditions, the air heater 3 is connected to at least one of the catalyst beds, and further preferably, the air heater 3 is connected to at least two of the catalyst beds.

[0047] In some preferred embodiments of the present invention, the conversion reactor 4 includes 5 catalyst beds, namely, from bottom to top, a first catalyst bed 41, a second catalyst bed 42, a third catalyst bed 43, a fourth catalyst bed 44, and a fifth catalyst bed 45, and the air heater 3 is connected to two of the catalyst beds.

[0048] When the high-temperature air enters the conversion reactor 4 from the first catalyst bed 41, the high-temperature air will cause heat loss when passing through the first catalyst bed 41, the second catalyst bed 42, and the third catalyst bed 43. In order to improve the heat utilization rate and ensure the heating requirements. Under preferred conditions, the high-temperature air is divided into c gas and d gas; the air heater 3 is connected to the first catalyst bed 41 and the fourth catalyst bed 44 through pipelines, respectively, for introducing the c gas into the first catalyst bed 41 and the d gas into the fourth catalyst bed 44; wherein the c gas enters the conversion reactor 4 from the first catalyst bed 41, and gradually moves upward from the first catalyst bed 41, and heats the second catalyst bed 42, the third catalyst bed 43, the fourth catalyst bed 44, and the fifth catalyst bed 45 in turn to obtain a first preheated gas; the d gas enters the conversion reactor 4 from the fourth catalyst bed 44, and moves upward into the fifth catalyst bed 45 to obtain a second preheated gas; after the first preheated gas and the second preheated gas merge in the fifth catalyst bed 45, they are discharged from the fifth catalyst bed 45 to the conversion reactor 4.

[0049] According to the present invention, in order to control the temperature of the conversion reactor 4 within the optimal reaction temperature range of the catalyst, under preferred conditions, a second temperature sensor 10 is provided at the inlet of the fourth catalyst bed 44 for monitoring the temperature T2 of the d gas, and a third regulating valve 9 is provided on the pipeline connecting the air heater 3 and the fourth catalyst bed 44, and the third regulating valve 9 is electrically connected to the second temperature sensor 10 for controlling the flow of the c gas and the d gas according to the value of T2. When the temperature T2 of the d gas is high, the opening of the first regulating valve 5 can be reduced to reduce the flow of the d gas entering the fourth catalyst bed 44 and increase the flow of the c gas entering the first catalyst bed 41, thereby ensuring that the temperature of the conversion reactor 4 is not too high; when the temperature T2 of the d gas is low, the opening of the first regulating valve 5 can be increased to increase the flow of the d gas entering the fourth catalyst bed 44 and reduce the flow of the c gas entering the first catalyst bed 41, thereby ensuring that the temperature of the conversion reactor 4 is not too low.

[0050] According to the present invention, the temperature of the conversion reactor 4 is adjusted accordingly according to the type of catalyst, actual working condition requirements and conversion rate. Under preferred conditions, the temperature of the conversion reactor 4 is set to 405-415°C.

[0051] In the present invention, at the initial stage of starting the furnace, since the temperature of the high-temperature flue gas generated by the incinerator 1 is relatively low, the first low-temperature flue gas obtained after heat exchange between this part of the high-temperature flue gas and the waste heat furnace 2 is directly discharged. Under preferred conditions, the waste heat furnace 2 is also provided with a pipeline connected to the atmosphere, and a fourth valve 17 is provided on the pipeline. A fifth valve 18 is provided on the pipeline 14. The flow direction of the first low-temperature flue gas is controlled by opening and closing the fourth valve 17 and the fifth valve 18.

[0052] The second aspect of the present invention provides a start-up temperature-raising method for a sulfuric acid production device, which is carried out in the temperature-raising system of the first aspect; the start-up temperature-raising method comprises: burning fuel in the presence of an oxygen-containing gas to obtain high-temperature flue gas; using the high-temperature flue gas to directly or indirectly heat the waste heat furnace and / or the conversion reactor, and controlling the flow rate of the high-temperature flue gas entering the waste heat furnace and / or the conversion reactor according to the temperature of the high-temperature flue gas.

[0053] In order to fully utilize the energy of high-temperature flue gas and fully preheat the conversion reactor to improve energy utilization, under preferred conditions, the start-up heating method includes:

[0054] (1) In the presence of oxygen-containing gas, the fuel is burned to obtain high-temperature flue gas;

[0055] (2) the high-temperature flue gas a and b, wherein the flow rates of the a and b gases are not zero at the same time;

[0056] Exchanging heat between the a gas and the waste heat furnace to obtain a first low-temperature flue gas;

[0057] exchanging heat between the heating gas and the air to obtain a second low-temperature flue gas and high-temperature air, wherein the heating gas is the b gas or a mixture of the b gas and the first low-temperature flue gas;

[0058] (3) Exchanging heat between the high-temperature air and the conversion reactor to obtain preheated gas.

[0059] In order to improve the utilization efficiency of energy, under preferred conditions, the present invention controls the flow rate of the high-temperature flue gas of the waste heat furnace and / or the conversion reactor according to the temperature of the high-temperature flue gas, and the step (2) further includes:

[0060] When the temperature of the high-temperature flue gas is T 烟 When the temperature is less than 550°C, all the high-temperature flue gas is used as a stream of gas to exchange heat with the waste heat furnace to obtain a first low-temperature flue gas, and the first low-temperature flue gas is discharged; or

[0061] When the temperature of the high-temperature flue gas is T 烟When the temperature is 550-800°C, all the high-temperature flue gas is used as gas b to exchange heat with the low-temperature air in the air heater to obtain a second low-temperature flue gas and high-temperature air; or

[0062] When the temperature of the high temperature flue gas is T 烟 When the temperature is higher than 800℃, the high-temperature flue gas is divided into gas a and gas b, wherein the flow rates of gas a and gas b are not zero, and gas a is introduced into the waste heat furnace for heat exchange to obtain a first low-temperature flue gas; gas b and the first low-temperature flue gas are mixed to obtain heating gas, and the heating gas is heat exchanged with the low-temperature air in the air heater to obtain a second low-temperature flue gas and high-temperature air.

[0063] In some preferred embodiments of the present invention, the step (3) further comprises: dividing the high temperature air into c gas and d gas, wherein the c gas is introduced into the conversion reactor from the bottom of the conversion reactor for heat exchange;

[0064] The d stream of gas is introduced into the conversion reactor from the middle and upper part of the conversion reactor for heat exchange.

[0065] According to the present invention, under preferred conditions, the temperature of the high-temperature air is 440-460°C.

[0066] According to the present invention, under preferred conditions, the method further comprises: circulating the preheated gas into the incinerator for incineration;

[0067] According to the present invention, under preferred conditions, the flow ratio of the oxygen-containing gas to the preheating gas is 1-2:1, preferably 1.5:1.

[0068] According to the present invention, under preferred conditions, the oxygen content in the incinerator is ≥12% by volume. Under this preferred condition, complete combustion of the fuel can be achieved, thereby improving the combustion efficiency of the fuel.

[0069] In the present invention, the type of the fuel may be known to those skilled in the art, for example, it may be at least one of coal, coal gas and diesel.

[0070] In a preferred embodiment of the present invention, the start-up temperature raising method comprises:

[0071] (1) Fuel is mixed with oxygen from the air duct 16 in the incinerator 1 and burned to obtain high-temperature flue gas;

[0072] (2) According to the temperature T of high temperature flue gas 烟 Adjust the flow rate of gas a and gas b:

[0073] When the temperature of the high temperature flue gas is T 烟When the temperature is less than 550°C, the flow rate of gas b is controlled to zero, and all the high-temperature flue gas is introduced into the waste heat furnace 1 as gas a to exchange heat with the waste heat furnace 1 to obtain the first low-temperature flue gas, and the first low-temperature flue gas is discharged;

[0074] When the temperature of the high temperature flue gas is T 烟 When the temperature is 550-800°C, the flow rate of gas a is controlled to zero, and all the high-temperature flue gas is used as gas b to exchange heat with the low-temperature air in the air heater to obtain a second low-temperature flue gas and high-temperature air;

[0075] When the temperature of the high temperature flue gas is T 烟 When the temperature is higher than 800°C, the high-temperature flue gas is divided into gas a and gas b, and the flow rates of gas a and gas b are not zero. Gas a is introduced into the waste heat furnace 1 to exchange heat with the waste heat furnace 1 to obtain a first low-temperature flue gas, and the first low-temperature flue gas is exhausted; gas b is mixed with the first low-temperature flue gas to obtain heating gas, and the heating gas is exchanged with the air in the air heater to obtain high-temperature air and second high-temperature flue gas, and the second high-temperature flue gas is directly exhausted;

[0076] (3) dividing the high temperature air into c gas and d gas,

[0077] The c gas is introduced into the conversion reactor from the bottom of the conversion reactor for heat exchange to obtain the first preheated gas;

[0078] The d stream of gas is introduced into the conversion reactor from the middle and upper part of the conversion reactor for heat exchange to obtain a second preheated gas;

[0079] The first preheated gas and the second preheated gas are mixed and then circulated and introduced into the incinerator 1 .

[0080] Taking a 40,000 ton / year waste acid regeneration sulfuric acid production unit as an example, it takes about 72 hours to heat up each time the sulfuric acid production unit is started up, and the power consumption per ton of acid is about 1.55-1.7kW·h. The electric energy saved by one conversion heating is 100kW-125kW, and the electricity bill saved is about 50,000 yuan.

[0081] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A startup heating system for a sulfuric acid production device, characterized in that: The system comprises: An incinerator (1) is used to incinerate fuel to obtain high-temperature flue gas, wherein the high-temperature flue gas is divided into a gas stream and a gas stream; an air duct (16), connected to the incinerator (1) and used for delivering oxygen to the incinerator (1); A waste heat furnace (2) is connected to the incinerator (1) via a pipeline (13) and is used to introduce the a stream of gas into the waste heat furnace (2) for heat exchange to obtain a first low-temperature flue gas; An air heater (3) is connected to the incinerator (1) via a pipeline (14), and the pipeline (13) and the pipeline (14) are connected via a pipeline (15), and is used to introduce heating gas into the air heater (3) and exchange heat with the low-temperature air in the air heater (3) to obtain a second low-temperature flue gas and high-temperature air, wherein the heating gas is the b gas or a mixture of the b gas and the first low-temperature flue gas; A conversion reactor (4) is connected to the air heater (3) and is used to introduce the high-temperature air into the conversion reactor (4) for heat exchange to obtain preheated gas; the conversion reactor (4) comprises five catalyst beds, which are, from bottom to top, a first catalyst bed (41), a second catalyst bed (42), a third catalyst bed (43), a fourth catalyst bed (44), and a fifth catalyst bed (45); The high temperature air is divided into c gas and d gas; The air heater (3) is connected to the first catalyst bed (41) and the fourth catalyst bed (44) through pipelines, respectively, and is used to introduce the c gas into the first catalyst bed (41) and introduce the d gas into the fourth catalyst bed (44).

2. The start-up temperature raising system according to claim 1, wherein: The pipeline (14) is provided with a first temperature sensor (6) for monitoring the temperature T1 of the heating gas; The pipeline (15) is provided with a first regulating valve (5), the first regulating valve (5) being electrically connected to the first temperature sensor (6) and being used for controlling the flow rates of the a gas and the b gas according to the value of T1.

3. The start-up heating system according to claim 1 or 2, wherein: The conversion reactor (4) is in communication with the incinerator (1) and is used to circulate the preheated gas into the incinerator (1).

4. The start-up temperature rise system according to claim 1 or 2, wherein: A second regulating valve (7) is provided on the pipeline connecting the incinerator (16) and the air pipeline (1); An oxygen concentration analysis device (8) is provided in the incinerator (1). The oxygen concentration analysis device (8) is electrically connected to the second regulating valve (7) and is used to monitor the oxygen concentration in the incinerator (1) and control the opening of the second regulating valve (7) according to the oxygen concentration.

5. The start-up heating system according to claim 1 or 2, wherein: A second temperature sensor (10) is provided at the inlet of the fourth catalyst bed (44) for monitoring the temperature T2 of the d stream gas. A third regulating valve (9) is provided on a pipeline connecting the air heater (3) and the fourth catalyst bed (44). The third regulating valve (9) is electrically connected to the second temperature sensor (10) and is used to control the flow rates of the c gas and the d gas according to the value of T2.

6. A method for heating up a sulfuric acid production plant at start-up, characterized in that: In the heating system according to any one of claims 1 to 5, the heating method comprises: (1) In the presence of oxygen-containing gas, the fuel is burned to obtain high-temperature flue gas; (2) dividing the high-temperature flue gas into gas a and gas b, wherein the flow rates of gas a and gas b are not zero at the same time; Exchanging heat between the a gas and the waste heat furnace to obtain a first low-temperature flue gas; exchanging heat between the heating gas and the air to obtain a second low-temperature flue gas and high-temperature air, wherein the heating gas is the b gas or a mixture of the b gas and the first low-temperature flue gas; (3) Exchanging heat between the high-temperature air and the conversion reactor to obtain preheated gas.

7. The start-up temperature raising method according to claim 6, wherein: The step (2) further comprises: When the temperature of the high temperature flue gas is T 烟 When the temperature is less than 550°C, all the high-temperature flue gas is used as a stream of gas to exchange heat with the waste heat furnace to obtain a first low-temperature flue gas, and the first low-temperature flue gas is discharged; or When the temperature of the high temperature flue gas is T 烟 When the temperature is 550-800°C, all the high-temperature flue gas is used as gas b to exchange heat with the low-temperature air in the air heater to obtain a second low-temperature flue gas and high-temperature air; or When the temperature of the high temperature flue gas is T 烟 When the temperature is higher than 800℃, the high-temperature flue gas is divided into gas a and gas b, wherein the flow rates of gas a and gas b are not zero, and gas a is introduced into the waste heat furnace for heat exchange to obtain a first low-temperature flue gas; gas b and the first low-temperature flue gas are mixed to obtain heating gas, and the heating gas is heat exchanged with the low-temperature air in the air heater to obtain a second low-temperature flue gas and high-temperature air.

8. The start-up temperature raising method according to claim 6 or 7, wherein: The step (3) further comprises: dividing the high temperature air into c gas and d gas, wherein the c gas is introduced into the conversion reactor from the bottom of the conversion reactor for heat exchange; The d stream of gas is introduced into the conversion reactor from the middle and upper part of the conversion reactor for heat exchange.

9. The start-up temperature raising method according to claim 6 or 7, wherein: The temperature of the high temperature air is 440-460°C.

10. The start-up temperature raising method according to claim 6 or 7, wherein: The method further comprises: circulating the preheated gas into the incinerator for incineration.

11. The start-up temperature raising method according to claim 6 or 7, wherein: The flow ratio of the oxygen-containing gas to the preheated gas is 1-2:

1.

12. The start-up temperature raising method according to claim 6 or 7, wherein: The oxygen content in the incinerator is ≥12% by volume.

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