A steam-water series isothermal conversion device for producing superheated steam

Abstract

The present invention discloses a steam-water series isothermal conversion device for producing superheated steam, belonging to the field of CO conversion technology. The device comprises an adiabatic conversion furnace, a first detoxification tank, a second detoxification tank, two isothermal conversion furnaces, a steam drum, a heat exchanger, and related piping and valves. The crude synthesis gas is connected to the first and second detoxification tanks via the heat exchanger. One detoxification tank outlet is connected to the adiabatic conversion furnace inlet and another to the second isothermal conversion furnace inlet. The combined conversion gas outlets are then connected to the heat exchanger, which is then connected to the third isothermal conversion furnace. The heat exchanger outlet is connected to the heat exchange tube bundle outlet of the second isothermal conversion furnace, and the drum circulating hot water outlet is connected to the heat exchange tube bundle inlet of the second isothermal conversion furnace. The drum steam outlet is connected to the external saturated steam to be heated and then connected to the adiabatic conversion furnace. Boiler feed water, heated by the third isothermal conversion furnace, is connected to the drum water inlet. The present invention significantly improves the quality of recovered waste heat and reduces the probability of external pressure instability and leakage failure of the isothermal conversion furnace heat exchange tubes.

Description

Technical Field

[0001] The present invention relates to the field of CO conversion technology, in particular to a steam-water series isothermal conversion device for producing superheated steam. Background Art

[0002] Currently, the conversion of crude syngas produced by pressurized coal gasification is primarily accomplished through adiabatic and isothermal conversion processes. The adiabatic conversion process involves installing one or more adiabatic conversion furnaces, followed by a steam superheater or waste heat recovery unit. This produces saturated steam, which can be used to heat other process media and recover waste heat. The isothermal conversion process involves installing water pipes within the conversion reactor, evaporating the water within the pipes to absorb the waste heat of the conversion reaction and produce saturated steam.

[0003] Generally, the reaction and heat load of the first isothermal or adiabatic converter are high, while the reaction and heat load of the second isothermal or adiabatic converter are low. The reaction bed temperature of the second isothermal or adiabatic converter is also relatively low. To meet the reaction conditions of the second isothermal converter, the steam pressure generated by the heat exchange tube bundle is low, resulting in low waste heat recovery quality and value. Furthermore, the pressure inside the heat exchange tubes in the heat exchange tube bundle is much lower than the gas pressure outside the bundle. The heat exchange tubes in the bundle are subject to external pressure, making them susceptible to leakage and instability. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a steam-water series isothermal conversion device for producing superheated steam, which solves the technical problems existing in the prior art, achieves high quality and value of waste heat recovery, effectively ensures the internal and external pressure balance of the heat exchange tube bundle, and reduces the probability of external pressure instability and leakage failure of the heat exchange tube of the isothermal conversion furnace.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A steam-water series isothermal conversion device for producing superheated steam, comprising a first conversion furnace, a first detoxification tank, a second detoxification tank, a second isothermal conversion furnace, a steam drum, a third isothermal conversion furnace, a heat exchanger, and related pipelines and valves; the first conversion furnace is an adiabatic conversion furnace;

[0007] After passing through the heat exchanger, the crude synthesis gas is connected to the gas inlet of the first detoxification tank and the second detoxification tank respectively. The outlets of the first detoxification tank and the second detoxification tank are merged and then divided into two paths, one of which is connected to the gas inlet of the first shift converter and the other is connected to the gas inlet of the second isothermal shift converter. The converted gas outlet of the first shift converter and the converted gas outlet of the second isothermal shift converter are merged and then connected to the heat exchanger. The outlet of the heat exchanger is connected to the gas inlet of the third isothermal shift converter. The gas outlet at the bottom of the third isothermal shift converter is connected to the heat recovery system.

[0008] The outlet of the second heat exchange tube bundle of the second isothermal shift furnace is connected to the steam-liquid mixture inlet of the drum, the circulating hot water outlet of the drum is connected to the second heat exchange tube bundle inlet of the second isothermal shift furnace, the steam outlet of the drum is combined with the external saturated steam to be heated and then connected to the steam inlet of the first shift furnace, and the steam outlet of the first shift furnace is connected to the superheated steam pipe network;

[0009] One line of boiler feed water merges with one outlet of the third heat exchange tube bundle at the top of the third isothermal conversion furnace and then connects to the drum water inlet. Another line of boiler feed water merges with another outlet of the third heat exchange tube bundle at the top of the third isothermal conversion furnace and then connects to the inlet of the third heat exchange tube bundle at the bottom of the third isothermal conversion furnace. The gas outlet at the bottom of the third isothermal conversion furnace is connected to the heat recovery system.

[0010] A further improvement of the technical solution of the present invention is that: the adiabatic conversion furnace adopts a first adiabatic conversion furnace with a built-in steam superheater or a second adiabatic conversion furnace with an upper steam superheater and a lower steam superheater provided between multiple adiabatic sections; when the second adiabatic conversion furnace is adopted, the device also includes a water heater; the steam outlet of the boiler drum is merged with the saturated steam to be heated from the outside and then connected to the superheated steam inlet of the upper steam superheater through the lower steam superheater, and the superheated steam outlet of the upper steam superheater is connected to the superheated steam pipeline network; the boiler feed water line is merged with the outlet of the third heat exchange tube bundle at the top of the third isothermal conversion furnace and then connected to the water inlet of the boiler drum and the heat exchange inlet of the water heater respectively, and the hot water outlet of the water heater is connected to the water inlet of the boiler drum.

[0011] A further improvement of the technical solution of the present invention is that the inlet and outlet of the first detoxification tank and the second detoxification tank are both equipped with shut-off valves for maintenance of the detoxification tank and replacement of detoxification agents.

[0012] A further improvement of the technical solution of the present invention is that the air inlet of the first conversion furnace and the air inlet of the second isothermal conversion furnace are both equipped with regulating valves for adjusting the gas inlet volume.

[0013] A further improvement of the technical solution of the present invention is that a flow regulating valve is installed on the drum water inlet pipeline.

[0014] Due to the adoption of the above technical solution, the technical advancements achieved by the present invention are:

[0015] 1. In the present invention, the reaction heat of the first converter having steam superheaters between multiple insulation sections is used to produce superheated steam through steam superheaters arranged between the catalyst bed sections in the furnace. The second isothermal converter connected in parallel with the first converter produces saturated steam through the second heat exchange tube bundle arranged on the catalyst bed in the furnace for recovery. The converted gas is cooled by the heat exchanger and enters the gas inlet of the third isothermal converter to continue the conversion reaction. The third isothermal converter is used to preheat boiler feed water. The pressure of the hot water is equivalent to the pressure of the steam produced as a by-product of the second isothermal converter. The hot water is used as make-up water for the steam drum. The third isothermal converter heats the boiler feed water instead of producing low-pressure steam, thereby increasing the amount of by-product steam of the second isothermal converter, and significantly improving the quality of the by-product waste heat of the third isothermal converter system.

[0016] 2. The present invention can control the steam-side pressure of the steam superheater tube sheet and the water-side pressure of the isothermal shift furnace tube bundle to be slightly greater than the synthesis gas-side pressure by adjusting the steam drum pressure. At the same time, the steam superheater and the isothermal shift furnace heat exchange tube bundle are subjected to internal pressure, and can achieve a slight pressure difference operation between the water side and the process gas side of the tube bundle. The stress situation is significantly improved, and the probability of external pressure instability and leakage failure of the isothermal shift furnace heat exchange tube can be reduced.

[0017] 3. The present invention arranges the detoxification tank after the heat exchanger, which is beneficial for removing SOx and impurities such as entrained dust from the crude synthesis gas, and can protect the catalyst from damage by poisons, thereby extending its service life.

[0018] 4. The first conversion furnace in the present invention is configured as an adiabatic conversion furnace, which can not only superheat the saturated steam provided by the steam drum within the system, but also superheat the saturated steam provided outside the system.

[0019] 5. In the present invention, since the first conversion furnace is connected in parallel with the second isothermal conversion furnace and in series with the third isothermal conversion furnace, the third isothermal conversion furnace can provide the steam drum with supplementary hot water equivalent to the steam pressure, and can also provide heat for the reaction gas at the inlet of the third isothermal conversion furnace, effectively maintaining the normal operation of the third isothermal conversion furnace. It can be used not only in the conversion section, but also in the low-pressure methanol synthesis and ammonia synthesis sections. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural diagram of Example 1 of the present invention;

[0021] Figure 2 It is a structural diagram of Example 2 of the present invention;

[0022] Among them, 1. the first adiabatic conversion furnace, 1a. the steam superheater, 2. the first detoxification tank, 3. the second detoxification tank, 4. the second isothermal conversion furnace 4, 5. the steam drum, 6. the third isothermal conversion furnace, 7. the heat exchanger, 8. the first pipeline, 9. the second pipeline, 10. the third pipeline, 11. the fourth pipeline, 11a. the boiler feed water pipeline, 12. the water heater, 13. the fifth pipeline, 14. the sixth pipeline, 15. the third flow regulating valve, 16. the second adiabatic conversion furnace, 16a. the upper steam superheater, 16b. the lower steam superheater. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0024] It should be noted that, in the description of the present invention, the technical terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing and understanding the technical solutions of the present invention. The above description does not limit the present invention, and the present invention is not limited to the examples described above. Any changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention should be regarded as the scope of protection of the present invention.

[0025] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "several" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0027] Example 1

[0028] like Figure 1As shown, a steam-water series isothermal conversion device for producing superheated steam includes a first adiabatic conversion furnace 1, a first detoxification tank 2, a second detoxification tank 3, a second isothermal conversion furnace 4, a steam drum 5, a third isothermal conversion furnace 6, a heat exchanger 7, and related pipelines and valves; the first adiabatic conversion furnace 1 is equipped with a steam superheater 1a;

[0029] The crude synthesis gas is preheated by the heat exchanger 7 and then enters the first detoxification tank 2 and the second detoxification tank 3 respectively. SO x After merging with the entrained dust and other impurities, it is divided into two paths, one entering the gas inlet of the first adiabatic conversion furnace 1, and the other entering the gas inlet of the second isothermal conversion furnace 4. When the first detoxification tank 2 is in the parked state, part of the gas at the outlet of the second detoxification tank 3 enters the first adiabatic conversion furnace 1, and part enters the second isothermal conversion furnace 4; when the second detoxification tank 3 is in the parked state, part of the gas at the outlet of the first detoxification tank 2 enters the first adiabatic conversion furnace 1, and part enters the second isothermal conversion furnace 4. Shut-off valves are provided at the air inlet and outlet of the first detoxification tank 2 and the second detoxification tank 3 for maintenance of the detoxification tanks and replacement of the detoxifying agent. The shut-off valve provided at the outlet of the first detoxification tank 2 can adjust the air intake into the first adiabatic conversion furnace 1 according to the amount of saturated steam to be superheated, ensuring a reasonable heat distribution of the first adiabatic conversion furnace 1 and the entire system.

[0030] Regulating valves are respectively installed at the air inlets of the first adiabatic conversion furnace 1 and the second isothermal conversion furnace 4 to adjust the gas inlet volume of the first adiabatic conversion furnace 1 and the second isothermal conversion furnace 4. The conversion gas outlet of the first adiabatic conversion furnace 1 merges with the conversion gas outlet of the second isothermal conversion furnace 4 and enters the gas inlet of the third isothermal conversion furnace 6 after being cooled by the heat exchanger 7. The converted gas after the reaction exits the bottom gas outlet of the third isothermal conversion furnace 6 and goes to the heat recovery system.

[0031] The outlet of the second heat exchange tube bundle of the second isothermal shift furnace 4 is connected to the vapor-liquid mixture inlet of the drum 5, the circulating hot water outlet of the drum 5 is connected to the second heat exchange tube bundle inlet of the second isothermal shift furnace 4, the steam outlet of the drum 5 merges with the inlet of the external saturated steam to be heated, and then connected to the steam inlet of the steam superheater 1a provided in the first adiabatic shift furnace 1, the superheated steam outlet of the steam superheater 1a is connected to the top outlet of the first adiabatic shift furnace 1, one path of boiler feed water passes through the first pipeline 8 and merges with one path of outlet of the third heat exchange tube bundle at the top of the third isothermal shift furnace 6 through the second pipeline 9, and then connected to the water inlet of the drum 5. Another path of boiler feed water passes through the fourth pipeline 11 and with one path of outlet of the third heat exchange tube bundle at the top of the third isothermal shift furnace 6 through the third pipeline 10 and merges at the pump inlet, and then connected to the inlet of the third heat exchange tube bundle at the bottom of the third isothermal shift furnace 6. The gas outlet at the bottom of the third isothermal shift furnace 6 is connected to the heat recovery system.

[0032] A first flow control valve is installed on the first pipeline 8 according to the load of the third isothermal shift furnace 6. By adjusting the water flow in the first pipeline 8, the inlet water temperature at the inlet of the third heat exchange tube bundle of the third isothermal shift furnace 6 is controlled to ensure thermal balance and normal operation of the third isothermal shift furnace 6. A second flow control valve is installed on the boiler feed water pipeline 11a to control the liquid level of the steam drum 5. The first adiabatic shift furnace 1 is an adiabatic shift furnace equipped with a steam superheater 1a. The second isothermal shift furnace 4 and the third isothermal shift furnace 6 are both isothermal shift furnaces. By adjusting the steam pressure of the steam drum 5, the steam-side pressure of the steam superheater 1a and the water-side pressure of the second heat exchange tube bundle of the second isothermal shift furnace 4 and the third isothermal shift furnace 6 can be controlled to be slightly greater than the syngas-side pressure.

[0033] Example 2

[0034] like Figure 2 As shown, a steam-water series isothermal conversion device for producing superheated steam includes a second adiabatic conversion furnace 16, a first detoxification tank 2, a second detoxification tank 3, a second isothermal conversion furnace 4, a steam drum 5, a third isothermal conversion furnace 6, a heat exchanger 7, a water heater 12, and related pipelines and valves; the second adiabatic conversion furnace 16 is a multi-stage adiabatic section with an upper steam superheater 16a and a lower steam superheater 16b provided between the sections;

[0035] The crude synthesis gas is preheated by the heat exchanger 7 and then enters the first detoxification tank 2 and the second detoxification tank 3 respectively, where SO is removed. x , entrained dust and other impurities are merged and then divided into two paths, one path entering the gas inlet of the second adiabatic conversion furnace 16, and the other path entering the gas inlet of the second isothermal conversion furnace 4. When the first detoxification tank 2 is in the parking state, part of the gas at the outlet of the second detoxification tank 3 enters the second adiabatic conversion furnace 16, and part enters the second isothermal conversion furnace 4; when the second detoxification tank 3 is in the parking state, part of the gas at the outlet of the first detoxification tank 2 enters the first adiabatic conversion furnace 16, and part enters the second isothermal conversion furnace 4. Shut-off valves are provided at the air inlet and outlet of the first detoxification tank 2 and the second detoxification tank 3 for the maintenance of the two detoxification tanks and the replacement of detoxification agents. The shut-off valve provided at the outlet of the first detoxification tank 2 can adjust the air intake entering the second adiabatic conversion furnace 16 according to the amount of saturated steam to be superheated, ensuring a reasonable heat distribution of the second adiabatic conversion furnace 16 and the entire system.

[0036] Regulating valves are installed at the air inlets of the second adiabatic shift furnace 16 and the second isothermal shift furnace 4 to regulate the gas inlet volume into the second adiabatic shift furnace 16 and the second isothermal shift furnace 4. The shifted gas after the upper reaction in the second adiabatic shift furnace 16 is cooled in the upper steam superheater 16a before entering the lower catalyst stage. The reacted gas is cooled in the lower steam superheater 16b, where it undergoes heat exchange with saturated steam from the outside and steam from the steam drum 5 before exiting the bottom outlet of the second adiabatic shift furnace 16. A shift reaction occurs within the second isothermal shift furnace 4, producing saturated steam as a by-product. The shifted gas at the bottom outlet of the second adiabatic shift furnace 16 is combined with the shifted gas at the bottom outlet of the second isothermal shift furnace 4 and then enters the heat exchanger 7. The shifted gas, cooled by the heat exchanger 7, is further heated by the water heater 12 before entering the gas inlet of the third isothermal shift furnace 6. The shift reaction then proceeds within the third isothermal shift furnace 6. The shifted gas exiting the bottom outlet of the third isothermal shift furnace 6 is then connected to a heat recovery system.

[0037] The outlet of the second heat exchange tube bundle of the second isothermal conversion furnace 4 is connected to the steam-liquid mixture inlet of the steam drum 5, and the circulating hot water outlet of the steam drum 5 is connected to the second heat exchange tube bundle inlet of the second isothermal conversion furnace 4. The steam outlet of the steam drum 5 is merged with the saturated steam to be heated from the outside and then passes through the lower steam superheater 16b and the upper steam superheater 16a arranged in the lower section of the second adiabatic conversion furnace 16 in sequence, that is, the superheated steam outlet of the lower steam superheater 16b of the second adiabatic conversion furnace 16 is connected to the steam inlet of the upper steam superheater 16a of the adiabatic conversion furnace 16 through a pipeline, and the superheated steam at the superheated steam outlet of the upper steam superheater 16a of the second adiabatic conversion furnace 16 is connected to the superheated steam pipeline network.

[0038] One route of boiler feed water passes through the first pipeline 8 and is joined with one outlet of the third heat exchange tube bundle at the top of the third isothermal shift furnace 6 via the second pipeline 9. The water is then connected to the water inlet of the steam drum 5 and the hot water inlet of the water heater 12 via the fifth pipeline 13 and the sixth pipeline 14 respectively. The hot water outlet of the water heater 12 is connected to the water inlet of the steam drum 5. The other route of boiler feed water passes through the fourth pipeline 11 and is joined with the other outlet of the third heat exchange tube bundle at the top of the third isothermal shift furnace 6 via the third pipeline 10 at the pump inlet. The water is then connected to the inlet of the third heat exchange tube bundle at the bottom of the third isothermal shift furnace 6. A first flow regulating valve is provided on the first pipeline 8 according to the load condition of the third isothermal shift furnace 6. The water flow rate of the first pipeline 8 is adjusted to control the water inlet temperature at the inlet of the third heat exchange tube bundle of the third isothermal shift furnace 6 to ensure the thermal balance and normal operation of the third isothermal shift furnace 6. The converted gas outlet at the bottom of the third isothermal shift furnace 6 is connected to the heat recovery system.

[0039] A third flow control valve 15 is installed on the fifth water inlet pipe 13 of the drum 5 to control the temperature of the gas inlet to the third isothermal shift furnace 6 to maintain normal operation of the third isothermal shift furnace 6. A second flow control valve is installed on the boiler feed water pipe 11a to control the liquid level of the drum 5.

[0040] A steam superheater, namely an upper steam superheater 16a and a lower steam superheater 16b, is provided under each bed layer of the second adiabatic conversion furnace 16, constituting an adiabatic conversion furnace with two or more steam superheaters arranged between two or more adiabatic sections.

[0041] In summary, in the present invention, since the first conversion furnace is connected in parallel with the second isothermal conversion furnace and in series with the third isothermal conversion furnace, the third isothermal conversion furnace can not only provide supplementary hot water with a steam pressure equivalent to that of the steam drum, but also provide heat for the reaction gas at the inlet of the third isothermal conversion furnace, thereby effectively maintaining the normal operation of the third isothermal conversion furnace. The present invention is not only used in the conversion section, but also in the low-pressure methanol synthesis and ammonia synthesis sections.

Claims

1. A steam-water series isothermal conversion device for producing superheated steam, characterized by: The invention comprises a first conversion furnace, a first detoxification tank (2), a second detoxification tank (3), a second isothermal conversion furnace (4), a steam drum (5), a third isothermal conversion furnace (6), a heat exchanger (7), and related pipelines and valves; the first conversion furnace is an adiabatic conversion furnace; After passing through the heat exchanger (7), the crude synthesis gas is connected to the gas inlets of the first detoxification tank (2) and the second detoxification tank (3) respectively. After the outlets of the first detoxification tank (2) and the second detoxification tank (3) are merged, the gas is divided into two paths, one path is connected to the gas inlet of the first conversion furnace, and the other path is connected to the gas inlet of the second isothermal conversion furnace (4). The conversion gas outlet of the first conversion furnace and the conversion gas outlet of the second isothermal conversion furnace (4) are merged and then connected to the heat exchanger (7). The outlet of the heat exchanger (7) is connected to the gas inlet of the third isothermal conversion furnace (6). The gas outlet at the bottom of the third isothermal conversion furnace (6) is connected to the heat recovery system. The outlet of the second heat exchange tube bundle of the second isothermal conversion furnace (4) is connected to the steam-liquid mixture inlet of the drum (5), the circulating hot water outlet of the drum (5) is connected to the second heat exchange tube bundle inlet of the second isothermal conversion furnace (4), the steam outlet of the drum (5) is combined with the external saturated steam to be heated and then connected to the steam inlet of the first conversion furnace, and the steam outlet of the first conversion furnace is connected to the superheated steam pipe network; One boiler water supply line is connected to one outlet of the third heat exchange tube bundle at the top of the third isothermal conversion furnace (6) and then connected to the water inlet of the drum (5); another boiler water supply line is connected to another outlet of the third heat exchange tube bundle at the top of the third isothermal conversion furnace (6) and then connected to the inlet of the third heat exchange tube bundle at the bottom of the third isothermal conversion furnace (6); the gas outlet at the bottom of the third isothermal conversion furnace (6) is connected to the heat recovery system; According to the load condition of the third isothermal conversion furnace (6), a first flow regulating valve is provided on the first pipeline (8), and the water flow of the first pipeline (8) is adjusted to control the water inlet temperature at the inlet of the third heat exchange tube bundle of the third isothermal conversion furnace (6) to meet the thermal balance and normal operation of the third isothermal conversion furnace (6); a second flow regulating valve is provided on the boiler water supply pipeline (11a) to control the liquid level of the steam drum (5); and the steam side pressure of the steam superheater (1a) is controlled by adjusting the steam pressure of the steam drum (5) so that the water side pressure of the second heat exchange tube bundle of the second isothermal conversion furnace (4) and the water side pressure of the third heat exchange tube bundle of the third isothermal conversion furnace (6) are both greater than the synthesis gas side pressure.

2. The steam-water series isothermal conversion device for producing superheated steam according to claim 1, characterized in that: The adiabatic conversion furnace adopts a first adiabatic conversion furnace (1) with a steam superheater (1a) built in, or a second adiabatic conversion furnace (16) with multiple adiabatic sections and an upper steam superheater (16a) and a lower steam superheater (16b). When the second adiabatic conversion furnace (16) is adopted, the device further comprises a water heater (12). The steam outlet of the drum (5) is combined with the saturated steam to be heated externally and then connected to the superheated steam inlet of the upper steam superheater (16a) through the lower steam superheater (16b). The superheated steam outlet of the upper steam superheater (16a) is connected to the superheated steam pipe network. The boiler feed water line is combined with the outlet of the third heat exchange tube bundle at the top of the third isothermal conversion furnace (6). After that, they are respectively connected to the water inlet of the drum (5) and the heat exchange inlet of the water heater (12). The hot water outlet of the water heater (12) is connected to the water inlet of the drum (5).

3. A steam-water series isothermal conversion device for producing superheated steam according to any one of claims 1-2, characterized in that: The inlet and outlet of the first detoxification tank (2) and the second detoxification tank (3) are both equipped with cut-off valves for maintenance of the detoxification tanks and replacement of detoxification agents.

4. A steam-water series isothermal conversion device for producing superheated steam according to any one of claims 1-2, characterized in that: The air inlet of the first conversion furnace and the air inlet of the second isothermal conversion furnace (4) are both equipped with regulating valves for regulating the gas inlet volume.

5. A steam-water series isothermal conversion device for producing superheated steam according to any one of claims 1-2, characterized in that: A flow regulating valve is installed on the water inlet pipeline of the steam drum (5).

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