Electric heating device and method for steam overheating

Abstract

The invention relates to the technical field of industrial waste heat recycling, in particular to an electric heating device and method for superheating saturated steam generated in the evaporative cooling process of a converter, an electric furnace and a steel rolling heating furnace in the iron and steel industry. Clean energy electricity serves as a heat source, saturated steam is heated into superheated steam through the steam superheater, the quality of the saturated steam can be effectively improved, damage of steam condensation water is prevented, and meanwhile steam conveying loss can be reduced; and compared with a traditional fuel gas type overheating device, other emissions are not added, and the problem of environmental pollution cannot be generated. The method is particularly suitable for the superheating process of high-temperature flue gas of a converter and an electric furnace in steel production and saturated steam generated by evaporative cooling steam drums such as a supporting beam in a heating furnace, the quality of (saturated) steam can be greatly improved by adopting the method, meanwhile, the harm caused by condensation of steam into water due to temperature reduction can be prevented, energy waste is effectively reduced, and the production cost is reduced. And the method has high economic benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial waste heat recovery and utilization, and in particular to an electric heating device and method for superheating saturated steam generated during the vaporization cooling process of a converter, an electric furnace and a steel rolling heating furnace in the steel industry. Background Art

[0002] Steel companies have a lot of waste heat and energy resources in the smelting process. In recent years, all steel companies have gradually paid attention to the recycling of waste heat resources in steel plants and have achieved certain results.

[0003] In the prior art, the cooling of high-temperature flue gas from converters and electric furnaces and the supporting beams in heating furnaces in steel production is usually done by taking the heat out of the steam drum with undersaturated water, cooling it through flash evaporation, and then pressurizing it and sending it back to the smoke hood and the supporting beams in the furnace to absorb heat, so as to protect the safe use of the equipment. At the same time, a large amount of saturated steam is recovered, and most of this saturated steam is transported to other users through the pipeline network or enters the steam turbine generator for power generation.

[0004] However, since the saturated steam transported by the existing technology has low quality, it is easy to condense into water due to temperature loss during the transportation process, which not only causes serious steam loss, but also endangers the operation of the pipeline network and the turbine. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an electric heating device and method for superheating steam, which uses clean energy electricity as a heat source, heats saturated steam into superheated steam through a steam superheater, and can effectively improve the quality of saturated steam and prevent the harm of steam condensation water. At the same time, it can reduce steam transportation losses and reduce energy waste.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] 1. An electric heating device for steam superheating

[0008] The present invention provides an electric heating device for steam superheating, comprising a steam drum 1, wherein the steam drum 1 is connected to the steam inlet of a steam superheater 4 through a steam pipeline 1, and the steam outlet of the steam superheater 4 is connected to the user's steam network through a steam pipeline 2. A steam regulating valve group 2 is installed on the steam pipeline 1, a cooling device is connected to the middle part of the steam pipeline 2 through a cooling pipeline, and a steam pressure reducing valve 5 and a temperature measuring sensor 7 are installed on the steam pipeline 2, and a steam temperature reducing valve 6 is installed on the cooling pipeline.

[0009] Furthermore, the steam superheater 4 adopts an organic heat carrier steam superheater, which heats the steam input from the steam pipeline 1 through the organic heat carrier, and transports the heated superheated steam to the user's steam network through the steam pipeline 2.

[0010] Furthermore, the medium outlet of the steam superheater 4 is connected to one end of the steam-water separator 3 through a medium pipeline 1, and the other end of the steam-water separator 3 is connected to the input end of the working fluid circulation pump 11. The output end of the working fluid circulation pump 11 is connected to the medium inlet of the steam superheater 4 after passing through the electric heating boiler 12.

[0011] Furthermore, the electric heating boiler 12 is provided with a plurality of electric heating rods. After the organic heat carrier exchanges heat with the steam in the steam superheater 4 and cools down, it is pressurized by the working fluid circulation pump 11 and sent to the electric heating boiler 12 for heating. The heated organic heat carrier enters the steam superheater 4 again for recycling.

[0012] Furthermore, the top of the steam-water separator 3 is connected to the high-level expansion tank 9, and the high-level expansion tank 9 is connected to the low-level storage tank 10 through a connecting pipe 1. The low-level storage tank 10 is connected to a heat carrier supplement pipeline, and the heat carrier supplement pipeline and the low-level storage tank 10 are connected to the input end of the working medium circulation pump 11 through a connecting pipe 2; the connecting pipe 1, the connecting pipe 2 and the heat carrier supplement pipeline are all provided with corresponding regulating valves.

[0013] Furthermore, a medium regulating valve group 8 is provided between the medium outlet and the medium inlet of the steam superheater 4 , for regulating the flow of the heat carrier entering the steam superheater 4 .

[0014] Furthermore, the steam regulating valve group 2 is used to adjust the steam flow entering the steam superheater 4. When the steam pressure reducing valve 5 is opened, the delivery pressure of the superheated steam in the steam pipeline 2 can be reduced. When the steam temperature reducing valve 6 is opened, the temperature of the superheated steam in the steam pipeline 2 can be reduced through a cooling device.

[0015] Furthermore, the temperature measurement sensor 7, the steam pressure reducing valve 5, the steam temperature reducing valve 6, the steam regulating valve group 2, the medium regulating valve group 8 and the electric heating boiler 12 are all electrically connected to the control system and are interlockedly controlled by the control system.

[0016] 2. A method for electric heating of steam superheating

[0017] Based on the same inventive concept, the present invention also provides a steam superheating electric heating method, based on the steam superheating electric heating device as described above, specifically comprising the following steps:

[0018] S1, by controlling the opening of the steam regulating valve group, the saturated steam pressure delivered by the drum is adjusted, and the initial pressure of the saturated steam pressure is 1.2-2.4 MPa and the initial temperature is 188-220°C;

[0019] S2, start the working medium circulation pump to make the organic heat carrier flow into the steam superheater to heat the saturated steam into superheated steam, the expected pressure of the superheated steam is 1.05-1.3 MPa, and the expected temperature is 250-280° C.;

[0020] S3, after the organic heat carrier exchanges heat with steam in the steam superheater and cools down, it is pressurized by the working fluid circulation pump and sent to the electric heating boiler for heating. The heated organic heat carrier enters the steam superheater again for recycling;

[0021] The power of the single heating rod in the electric heating boiler is 57kW, and the heating time is 1 to 2s;

[0022] S4, by controlling the power of the electric heating rod in the electric heating boiler and the opening of the medium regulating valve group, the temperature and flow rate of the organic heat carrier flowing into the steam superheater are respectively adjusted;

[0023] S5, execute superheated steam temperature interlocking control according to the real-time temperature value of the temperature measuring sensor.

[0024] Wherein, the superheated steam temperature interlocking control includes:

[0025] 1) If the pressure of the superheated steam meets 1.05-1.3 MPa and the temperature value is higher than the maximum temperature threshold (280° C.), the power of the electric heating rod is first reduced by 10% to reduce the heat exchange temperature of the organic heat carrier;

[0026] 2) If the temperature of the superheated steam is still higher than the maximum temperature threshold (280° C.) after the power of the electric heating rod is reduced by 10%, the opening of the steam temperature reduction valve is increased to reduce the temperature of the superheated steam;

[0027] 3) If the pressure of the superheated steam meets 1.05-1.3 MPa and the temperature value is lower than the minimum temperature threshold (250° C.), the steam temperature reduction valve is first closed to stop cooling the superheated steam;

[0028] 4) If the temperature of the superheated steam is still lower than the minimum temperature threshold (250°C) after the steam temperature reducing valve is closed, the power of the electric heating rod is increased until the temperature of the superheated steam is within a preset temperature range (250°C to 280°C).

[0029] Compared with the prior art, the present invention has the following main advantages:

[0030] 1. The present invention uses clean energy electricity as the heat source, converts electrical energy into thermal energy through electric thermal resistors (rods), and uses a steam superheater to heat saturated steam into superheated steam, which can effectively improve the quality of saturated steam and prevent the harm of steam condensation water. At the same time, it can reduce steam transportation losses and energy waste, and has huge economic value. Compared with traditional gas-fired superheating devices, the present invention does not add other emissions and will not cause environmental pollution problems, which meets the requirements of "energy saving and carbon reduction, green development" for enterprise development.

[0031] 2. The present invention adopts a green and environmentally friendly steam superheating method, which is particularly suitable for the saturated steam superheating process generated by the high-temperature flue gas of the converter and electric furnace in steel production and the support beam in the heating furnace and other vaporization cooling steam drums. The use of the present invention can greatly improve the quality of (saturated) steam, and at the same time prevent the harm caused by the condensation of steam into water due to temperature reduction, effectively reduce energy waste, and have higher economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the structure of the electric heating device for steam superheating in the first embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the structure of the electric heating device for steam superheating in the second embodiment of the present invention;

[0034] Figure 3 This is an overall flow chart of the electric heating method for superheating steam in Example 3 of the present invention.

[0035] In the figure: 1-steam drum; 2-steam regulating valve group; 3-steam-water separator; 4-steam superheater; 5-steam pressure reducing valve; 6-steam temperature reducing valve; 7-temperature measuring sensor; 8-medium regulating valve group; 9-high-level expansion tank; 10-low-level storage tank; 11-working fluid circulation pump; 12-electric heating boiler. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0037] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, and two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0038] Embodiment 1: This embodiment provides an electric heating device for steam superheating, such as Figure 1 As shown, it mainly includes: a steam drum 1, a steam regulating valve group 2, a steam superheater 4, a steam pressure reducing valve 5, a steam temperature reducing valve 6 and a temperature measuring sensor 7;

[0039] Among them, the steam drum 1 is connected to the steam inlet of the steam superheater 4 through the steam pipeline 1, the steam outlet of the steam superheater 4 is connected to the user steam network through the steam pipeline 2, a steam regulating valve group 2 is installed on the steam pipeline 1, a cooling device is connected to the middle part of the steam pipeline 2 through the cooling pipeline, and a steam pressure reducing valve 5 and a temperature measuring sensor 7 are installed on the steam pipeline 2, and a steam temperature reducing valve 6 is installed on the cooling pipeline.

[0040] Furthermore, the steam superheater 4 adopts an organic heat carrier steam superheater, which heats the steam input from the steam pipeline 1 through the organic heat carrier, and transports the heated superheated steam to the user's steam network through the steam pipeline 2.

[0041] Furthermore, the medium outlet of the steam superheater 4 is connected to one end of the steam-water separator 3 through a medium pipeline 1, and the other end of the steam-water separator 3 is connected to the input end of the working fluid circulation pump 11. The output end of the working fluid circulation pump 11 is connected to the medium inlet of the steam superheater 4 after passing through the electric heating boiler 12.

[0042] Furthermore, the electric heating boiler 12 is provided with a plurality of electric heating rods. After the organic heat carrier exchanges heat with the steam in the steam superheater 4 and cools down, it is pressurized by the working fluid circulation pump 11 and sent to the electric heating boiler 12 for heating. The heated organic heat carrier enters the steam superheater 4 again for recycling.

[0043] Specifically: the saturated steam coming out of the steam drum enters the organic heat carrier steam superheater through the regulating valve group to be heated and then enters the steam network after the temperature is adjusted by the temperature reducing valve; at the same time, the organic heat carrier in the organic heat carrier steam superheater exchanges heat with the saturated steam and cools down, and then is pressurized by the working fluid circulation pump and sent to the electric heating boiler to be heated by multiple groups of electric thermal resistors (rods). The heated organic heat carrier enters the organic heat carrier steam superheater again to continue heating the saturated steam, thus realizing recycling.

[0044] Furthermore, the top of the steam-water separator 3 is connected to the high-level expansion tank 9, and the high-level expansion tank 9 is connected to the low-level storage tank 10 through a connecting pipe 1. The low-level storage tank 10 is connected to a heat carrier supplement pipeline, and the heat carrier supplement pipeline and the low-level storage tank 10 are connected to the input end of the working medium circulation pump 11 through a connecting pipe 2; the connecting pipe 1, the connecting pipe 2 and the heat carrier supplement pipeline are all provided with corresponding regulating valves.

[0045] Furthermore, a medium regulating valve group 8 is provided between the medium outlet and the medium inlet of the steam superheater 4 , for regulating the flow of the heat carrier entering the steam superheater 4 .

[0046] Furthermore, the steam regulating valve group 2 is used to adjust the steam flow entering the steam superheater 4. When the steam pressure reducing valve 5 is opened, the delivery pressure of the superheated steam in the steam pipeline 2 can be reduced. When the steam temperature reducing valve 6 is opened, the temperature of the superheated steam in the steam pipeline 2 can be reduced through a cooling device.

[0047] Furthermore, the temperature measurement sensor 7, the steam pressure reducing valve 5, the steam temperature reducing valve 6, the steam regulating valve group 2, the medium regulating valve group 8 and the electric heating boiler 12 are all electrically connected to the control system and are interlockedly controlled by the control system.

[0048] Furthermore, the user can select different organic heat carriers according to the temperature requirements to be achieved by the superheated steam; the steam superheater can be a shell and tube heat exchanger.

[0049] Embodiment 2: This embodiment provides an electric heating device for steam superheating, such as Figure 2 As shown, the steam superheater can directly adopt an electrically heated steam superheater;

[0050] The saturated steam from the drum 1 enters the electric heating steam superheater 4 through the regulating valve group 2 and is heated to a superheated state by multiple groups of electric thermal resistors (rods), and then enters the user's steam network after being regulated by the temperature reduction and pressure reducing valve group;

[0051] Furthermore, the temperature detection device arranged on the outlet pipe of the steam superheater is interlocked with the multiple groups of electric thermal resistors (rods), and when the dryness of the saturated steam coming out of the steam drum is low, a steam-water separator 3 needs to be arranged in front of the steam superheater. After the saturated steam enters the steam-water separator 3, the condensed water is discharged through the bottom for secondary utilization, and the saturated steam is sent out.

[0052] The electric heating method for steam superheating proposed in the present application solves the environmental pollution problem caused by gas-fired superheating devices. Users can choose to directly use electric heaters to heat saturated steam according to usage conditions, or choose different organic carriers to heat (saturated) steam according to steam temperature requirements to achieve steam superheating, thereby meeting the requirements of downstream users for steam quality. It can effectively prevent the harm caused by (saturated) steam condensing into water due to pipeline heat dissipation losses, and can greatly reduce steam transmission losses. It is an energy-saving and environmentally friendly steam superheating method.

[0053] Embodiment 3, based on the same inventive concept, this embodiment also provides a steam superheating electric heating method, based on the steam superheating electric heating device as described above, such as Figure 3 As shown, the specific steps include:

[0054] S1, by controlling the opening of the steam regulating valve group, the saturated steam pressure delivered by the drum is adjusted, and the initial pressure of the saturated steam pressure is 1.2-2.4 MPa and the initial temperature is 188-220°C;

[0055] S2, start the working medium circulation pump to make the organic heat carrier flow into the steam superheater to heat the saturated steam into superheated steam, the expected pressure of the superheated steam is 1.05-1.3 MPa, and the expected temperature is 250-280° C.;

[0056] S3, after the organic heat carrier exchanges heat with steam in the steam superheater and cools down, it is pressurized by the working fluid circulation pump and sent to the electric heating boiler for heating. The heated organic heat carrier enters the steam superheater again for recycling;

[0057] The power of the single heating rod in the electric heating boiler is 57kW, and the heating time is 1 to 2s;

[0058] S4, by controlling the power of the electric heating rod in the electric heating boiler and the opening of the medium regulating valve group, the temperature and flow rate of the organic heat carrier flowing into the steam superheater are respectively adjusted;

[0059] S5, execute superheated steam temperature interlocking control according to the real-time temperature value of the temperature measuring sensor.

[0060] Wherein, the superheated steam temperature interlocking control includes:

[0061] 1) If the pressure of the superheated steam meets 1.05-1.3 MPa and the temperature value is higher than the maximum temperature threshold (280° C.), the power of the electric heating rod is first reduced by 10% to reduce the heat exchange temperature of the organic heat carrier;

[0062] 2) If the temperature of the superheated steam is still higher than the maximum temperature threshold (280° C.) after the power of the electric heating rod is reduced by 10%, the opening of the steam temperature reduction valve is increased to reduce the temperature of the superheated steam;

[0063] 3) If the pressure of the superheated steam meets 1.05-1.3 MPa and the temperature value is lower than the minimum temperature threshold (250° C.), the steam temperature reduction valve is first closed to stop cooling the superheated steam;

[0064] 4) If the temperature of the superheated steam is still lower than the minimum temperature threshold (250°C) after the steam temperature reducing valve is closed, the power of the electric heating rod is increased until the temperature of the superheated steam is within a preset temperature range (250°C to 280°C).

[0065] Furthermore, all parts involved in this application that are not described in detail are the same as the prior art or are implemented using the prior art.

[0066] In summary:

[0067] 1. The present invention uses clean energy electricity as the heat source, converts electrical energy into thermal energy through electric thermal resistors (rods), and uses a steam superheater to heat saturated steam into superheated steam, which can effectively improve the quality of saturated steam and prevent the harm of steam condensation water. At the same time, it can reduce steam transportation losses and energy waste, and has huge economic value. Compared with traditional gas-fired superheating devices, the present invention does not add other emissions and will not cause environmental pollution problems, which meets the requirements of "energy saving and carbon reduction, green development" for enterprise development.

[0068] 2. The present invention adopts a green and environmentally friendly steam superheating method, which is particularly suitable for the saturated steam superheating process generated by the high-temperature flue gas of the converter and electric furnace in steel production and the support beam in the heating furnace and other vaporization cooling steam drums. The use of the present invention can greatly improve the quality of (saturated) steam, and at the same time prevent the harm caused by the condensation of steam into water due to temperature reduction, effectively reduce energy waste, and have higher economic benefits.

[0069] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An electric heating device for steam superheating, characterized in that: The invention comprises a steam drum (1), wherein the steam drum (1) is connected to the steam inlet of a steam superheater (4) through a steam pipeline 1, and the steam outlet of the steam superheater (4) is connected to the user's steam network through a steam pipeline 2, a steam regulating valve group (2) is installed on the steam pipeline 1, a cooling device is connected to the middle of the steam pipeline 2 through a cooling pipeline, a steam pressure reducing valve (5) and a temperature measuring sensor (7) are installed on the steam pipeline 2, and a steam temperature reducing valve (6) is installed on the cooling pipeline.

2. The electric heating device for steam superheating according to claim 1, characterized in that: The steam superheater (4) adopts an organic heat carrier type steam superheater, which heats the steam input from the steam pipeline one through the organic heat carrier, and transports the heated superheated steam to the user's steam network through the steam pipeline two.

3. The electric heating device for steam superheating according to claim 2, characterized in that: The medium outlet of the steam superheater (4) is connected to one end of the steam-water separator (3) through a medium pipeline 1, and the other end of the steam-water separator (3) is connected to the input end of a working medium circulation pump (11), and the output end of the working medium circulation pump (11) is connected to the medium inlet of the steam superheater (4) after passing through an electric heating boiler (12).

4. The electric heating device for steam superheating according to claim 3, characterized in that: The electric heating boiler (12) is provided with a plurality of groups of electric heating rods. After the organic heat carrier exchanges heat with the steam in the steam superheater (4) to reduce its temperature, it is pressurized by the working fluid circulation pump (11) and then sent to the electric heating boiler (12) for heating. The heated organic heat carrier enters the steam superheater (4) again for recycling.

5. The electric heating device for steam superheating according to claim 3, characterized in that: The top of the steam-water separator (3) is connected to a high-position expansion tank (9), and the high-position expansion tank (9) is connected to a low-position storage tank (10) via a connecting pipe 1. The low-position storage tank (10) is connected to a heat carrier supplement pipeline, and the heat carrier supplement pipeline and the low-position storage tank (10) are connected to the input end of the working medium circulation pump (11) via a connecting pipe 2; the connecting pipe 1, the connecting pipe 2 and the heat carrier supplement pipeline are all provided with corresponding regulating valves.

6. The electric heating device for steam superheating according to claim 3, characterized in that: A medium regulating valve group (8) is provided between the medium outlet and the medium inlet of the steam superheater (4) for regulating the flow rate of the heat carrier entering the steam superheater (4).

7. The electric heating device for steam superheating according to claim 1, characterized in that: The steam regulating valve group (2) is used to regulate the steam flow entering the steam superheater (4); the steam pressure reducing valve (5) can reduce the delivery pressure of the superheated steam in the steam pipeline 2 after it is opened; and the steam temperature reducing valve (6) can reduce the temperature of the superheated steam in the steam pipeline 2 through a cooling device after it is opened.

8. The electric heating device for steam superheating according to claim 6, characterized in that: The temperature measurement sensor (7), the steam pressure reducing valve (5), the steam temperature reducing valve (6), the steam regulating valve group (2), the medium regulating valve group (8) and the electric heating boiler (12) are all electrically connected to the control system and are interlockedly controlled by the control system.

9. A steam superheating electric heating method, based on the steam superheating electric heating device according to any one of claims 1 to 8, characterized in that: The steps include: S1, adjusts the saturated steam pressure delivered by the drum by controlling the opening of the steam regulating valve group; S2, start the working medium circulation pump to make the organic heat carrier flow into the steam superheater to heat the saturated steam into superheated steam; S3, after the organic heat carrier exchanges heat with steam in the steam superheater and cools down, it is pressurized by the working fluid circulation pump and sent to the electric heating boiler for heating. The heated organic heat carrier enters the steam superheater again for recycling; S4, by controlling the power of the electric heating rod in the electric heating boiler and the opening of the medium regulating valve group, the temperature and flow rate of the organic heat carrier flowing into the steam superheater are respectively adjusted; S5, execute superheated steam temperature interlocking control according to the real-time temperature value of the temperature measuring sensor.

10. The electric heating method for steam superheating according to claim 9, characterized in that: The superheated steam temperature interlocking control comprises: 1) If the temperature value of the superheated steam is higher than the maximum temperature threshold, firstly, the power of the electric heating rod is reduced by 10% to reduce the heat exchange temperature of the organic heat carrier; 2) If the temperature of the superheated steam is still higher than the maximum temperature threshold after the power of the electric heating rod is reduced by 10%, the opening of the steam temperature reducing valve is increased to reduce the temperature of the superheated steam; 3) If the temperature of the superheated steam is lower than the minimum temperature threshold, the steam temperature reduction valve is first closed to stop cooling the superheated steam; 4) If the temperature of the superheated steam is still lower than the minimum temperature threshold after the steam temperature reducing valve is closed, the power of the electric heating rod is increased until the temperature of the superheated steam is within a preset temperature range.

Images