A system for efficiently utilizing waste heat and waste pressure of top gas in gas-based vertical furnace process

Abstract

The utility model discloses a system for efficiently utilizing waste heat and waste pressure of top gas of a gas-based vertical furnace process, comprising a gas-based vertical furnace, a top gas heat exchanger and a top gas scrubber which are connected in sequence, wherein the gas outlet of the top gas scrubber is respectively connected to the gas inlet of a process gas compressor through a first pipeline, to the gas inlet of a turbine expander through a second pipeline, and to the fuel gas inlet of a process gas heater through a third pipeline; the process gas outlet of the process gas compressor is connected to the reducing gas inlet of the gas-based vertical furnace; the process gas outlet of the turbine expander is connected to the fuel inlet of a combustion boiler; and is connected to the combustion oxygen supplement and combustion-supporting gas inlet of a process gas heater through a third pipeline. After being purified, part of the top gas is directly used to drive the process gas compressor, and part is used for turbine expansion to do work; part of the process gas heater is used as fuel gas for the process gas heater; and the high-temperature steam can also enter a steam turbine generator set to generate electricity, so that the high-temperature and high-pressure top gas generated by the gas-based vertical furnace is fully utilized.

Description

Technical Field

[0001] The utility model belongs to the technical field of waste heat recovery, and in particular relates to a system for efficiently utilizing waste heat and waste pressure of furnace top gas in a gas-based vertical furnace process. Background Art

[0002] The direct reduction iron process for large-scale production has a large carbon reduction range and is increasingly favored by steel producers. Among them, the gas-based vertical furnace direct reduction technology has low energy consumption, stable products, and less pollution, and has been widely recognized in the industry. At present, the commonly used gas-based vertical furnace direct reduction iron mainly includes MIDREX and HLY process routes. The metallization rates of the products of these two processes are equivalent. The difference lies in the raw material hydrogen-carbon ratio and the production pressure level of the vertical furnace device. Among them, the HYL process route has a large hydrogen-carbon ratio and a stronger carbon reduction ability. The first part of the vertical furnace top gas generated by the existing HYL process enters the main process and mixes with the raw material gas to become a raw material mixed gas. After pressure replenishment, purification, reforming, heating and oxygen supplementation, it enters the vertical furnace again as a reducing agent for reduction reaction; the second part passes through the vertical furnace top scrubber and then undergoes temperature reduction and pressure reduction or turbine expansion to generate electricity. The third part is used as a heating furnace fuel to provide heating fuel for the raw material mixed gas heating furnace. Its defect is that the temperature reduction and pressure reduction treatment of the second part of the top gas is high-quality and low-use, and the cascade utilization of the top gas is not achieved, resulting in high energy consumption in the vertical furnace production process and waste of heat carried in the top gas. Summary of the invention

[0003] In view of the shortcomings of the prior art, the purpose of the utility model is to provide a system for efficiently utilizing the waste heat and waste pressure of the top gas of a gas-based vertical furnace process, which solves the technical problems of low waste heat recovery efficiency and high heat utilization cost in the prior art.

[0004] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0005] A system for efficiently utilizing waste heat and waste pressure of top gas of a gas-based vertical furnace process, comprising a gas-based vertical furnace, a top gas heat exchanger and a top gas scrubber which are sequentially connected and arranged, wherein the gas outlet of the top gas scrubber is respectively connected to the gas inlet of a process gas compressor via a first pipeline, connected to the gas inlet of a turbine expander via a second pipeline, and connected to the fuel gas inlet of a process gas heater via a third pipeline;

[0006] The process gas outlet of the process gas compressor is connected to the reducing gas inlet of the gas-based vertical furnace;

[0007] The process gas outlet of the turbine expander is connected to the fuel inlet of the combustion boiler;

[0008] It is connected to the combustion oxygen supplement and combustion-supporting air inlet of the process gas heater through the third pipeline.

[0009] The utility model also has the following technical features:

[0010] Specifically, the steam outlet of the top gas heat exchanger is connected to the steam inlet of the steam turbine generator set through a fourth pipeline, and the process gas outlet of the top gas heat exchanger is connected to the air inlet of the top gas scrubber; the water inlet of the top gas heat exchanger is connected to the softened water pipeline, and the air inlet of the top gas heat exchanger is connected to the air outlet of the gas-based vertical furnace through a pipeline;

[0011] The softened water pipeline is also communicated with the water inlet of the combustion boiler, and the steam outlet of the combustion boiler is connected to the steam inlet of the steam turbine generator set through a fifth pipeline.

[0012] Furthermore, a mixed gas reformer is also arranged on the pipeline between the process gas compressor and the gas-based vertical furnace.

[0013] Furthermore, a clutch is provided between the process gas compressor and the turbine expander.

[0014] Furthermore, the process gas compressor is also connected to an electric motor.

[0015] Furthermore, the process gas heater is connected to the chimney via a first smoke exhaust pipe, and the combustion boiler is connected to the chimney via a second smoke exhaust pipe.

[0016] Furthermore, the process gas heater is also connected to a first oxygenation pipeline; and the combustion boiler is also connected to a second oxygenation pipeline.

[0017] Furthermore, the first pipeline is also connected to an air supply pipeline.

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

[0019] (1) In the utility model, part of the high-temperature and high-pressure top gas generated by the gas-based vertical furnace is directly used to drive the process gas compressor after purification, and part of it is used for turbine expansion to do work, and the process gas compressor and the turbine expander are connected by a clutch, which reduces the secondary energy conversion process of connecting to the power grid and taking electricity from the power grid; part of the process gas heater is used as the fuel gas of the process gas heater, so that the high-temperature and high-pressure top gas generated by the gas-based vertical furnace is fully utilized.

[0020] (2) The high-temperature steam generated by the furnace top gas heat exchanger in the utility model can enter the steam turbine generator set to generate electricity. Compared with the traditional waste heat boiler, the furnace top gas is more reasonably utilized, the pressure energy and thermal energy are also utilized in a cascade manner, and the energy structure is effectively optimized.

[0021] Other features and advantages of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1It is a schematic diagram of the overall structure of the utility model, in which the arrows indicate the direction of smoke flow;

[0023] The symbols in the figure represent:

[0024] 1-gas-based vertical furnace, 2-top gas heat exchanger, 3-top gas scrubber, 4-first pipeline, 5-process gas compressor, 6-second pipeline, 7-turbine expander, 8-third pipeline, 9-process gas heater, 10-combustion boiler, 11-softened water pipeline, 12-steam turbine generator set, 13A-fourth pipeline, 13B-fifth pipeline, 14-mixed gas reformer, 15-clutch, 16-motor, 17-chimney, 18-second smoke exhaust pipeline, 19-first smoke exhaust pipeline. 20-air supply pipeline.

[0025] The specific contents of the utility model are further explained in detail below in conjunction with the drawings and specific implementation methods. DETAILED DESCRIPTION

[0026] It should be noted that, unless otherwise specified, all components in the present invention are components known in the art.

[0027] The terms "upper", "lower", "front", "back", "top", "bottom", etc. used in the present invention to indicate directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. "Inside" and "outside" refer to the inside and outside of the contour of the corresponding components, and the above terms should not be understood as limitations on the present invention.

[0028] In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include one or more of the features.

[0029] In the present invention, unless otherwise specified, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, or a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of the present application fall within the protection scope of the present invention.

[0031] Example

[0032] The present embodiment discloses a system for efficiently utilizing waste heat and waste pressure of top gas in a gas-based vertical furnace process, comprising a gas-based vertical furnace 1, a top gas heat exchanger 2 and a top gas scrubber 3 which are sequentially connected and arranged, the top gas heat exchanger 2 is used to generate steam and also has a dust removal function, the top gas scrubber 3 is used to perform dust removal and dehydration treatment on the top gas after heat exchange to obtain clean top gas; the gas outlet of the top gas scrubber 3 is respectively connected to the gas inlet of a process gas compressor 5 through a first pipeline 4, connected to the gas inlet of a turbine expander 7 through a second pipeline 6, and connected to the fuel gas inlet of a process gas heater 9 through a third pipeline 8;

[0033] The process gas outlet of the process gas compressor 5 is connected to the reducing gas inlet of the gas-based vertical furnace 1;

[0034] The process gas outlet of the turbo expander 7 is connected to the fuel inlet of the combustion boiler 10.

[0035] As a preferred solution of this embodiment, the steam outlet of the top gas heat exchanger 2 is connected to the steam inlet of the steam turbine generator set 12 through the fourth pipeline 13A, and the process gas outlet of the top gas heat exchanger 2 is connected to the air inlet of the top gas scrubber 3; the water inlet of the top gas heat exchanger 2 is connected to the softened water pipeline 11, and the air inlet of the top gas heat exchanger 2 is connected to the air outlet of the gas-based vertical furnace 1 through a pipeline.

[0036] The clean top gas discharged from the top gas scrubber 3 is divided into three sections: the top gas of section I enters the process gas compressor 5; the top gas of section II enters the turbo expander 7; the top gas of section III enters the process gas heater 9 as the fuel gas of the heater 9. The process compressor 5 is used to compress the mixed gas input by the raw gas supplemented by the gas supply pipeline 20 and the top gas of section I, and provide high-pressure reducing gas for the gas-based vertical furnace 1; the turbo expander 7 is used to expand the high top pressure of the top gas of section II to do work, and the clutch 15 is connected to the shaft system of the process gas compressor 5, and the mechanical energy generated by the expansion work reduces the power of the motor of the process gas compressor 5.

[0037] As a preferred solution of this embodiment, a clutch 15 is provided between the process gas compressor 5 and the turbine expander 7 .

[0038] As a preferred solution of this embodiment, the process gas compressor 5 is also connected to an electric motor 16 .

[0039] In the early stage of unit startup, the clutch 15 is disconnected, and the process gas compressor 5 is driven by the motor 16; after the process system is fully loaded, the clutch 15 is closed, and the process gas compressor 5 is driven by the motor 16 and the turbo expander 7. The top gas of the III stage enters the process gas heater 9, and as the fuel gas of the heater 9, it is mixed with the external supplementary oxygen and burned to provide energy for heating the main reducing gas entering the gas-based vertical furnace 1.

[0040] As a preferred solution of this embodiment, the steam outlet of the top gas heat exchanger 2 is connected to the steam inlet of the steam turbine generator set 12 through the fourth pipeline 13A, and the process gas outlet of the top gas heat exchanger 2 is connected to the air inlet of the top gas scrubber 3; the water inlet of the top gas heat exchanger 2 is connected to the softened water pipeline 11, and the air inlet of the top gas heat exchanger 2 is connected to the air outlet of the gas-based vertical furnace 1 through a pipeline; the softened water pipeline 11 is also connected to the water inlet of the combustion boiler 10.

[0041] As a preferred solution of this embodiment, a mixed gas reformer 14 is also provided on the pipeline between the process gas compressor 5 and the gas-based vertical furnace 1. The gas is reformed into reducing gas and then enters the gas-based vertical furnace 1. The iron oxide reacts with the reducing gas in the gas-based vertical furnace 1 and is directly reduced to iron.

[0042] As a preferred solution of this embodiment, the process gas heater 9 is connected to the chimney 17 via the first smoke exhaust pipe 19 , and the combustion boiler 10 is connected to the chimney 17 via the second smoke exhaust pipe 18 .

[0043] As a preferred solution of this embodiment, the process gas heater 9 is further connected to a first oxygenation pipeline; and the combustion boiler 10 is further connected to a second oxygenation pipeline.

[0044] As a preferred solution of this embodiment, the first pipeline 4 is also connected to an air supply pipeline 20 .

[0045] The usage process of this embodiment includes:

[0046] The softened water introduced into the system through the soft water pipe 11 is supplied to the top gas heat exchanger 2 and the combustion boiler 10 respectively; the high-temperature and high-pressure top gas discharged from the top of the gas-based vertical furnace 1 becomes saturated steam after passing through the top gas heat exchanger 2, and enters the steam turbine generator set 12 through the fourth pipe 13A; among them, the partially purified top gas after passing through the top gas heat exchanger 2 and the top scrubber 3 enters the turbine expander through the second pipe 6, and uses the residual pressure expansion to do work without consuming the top gas. After passing through the turbine expander 7, it becomes low-pressure top gas and enters the combustion boiler 10 with oxygen provided from the outside to generate saturated steam; the saturated steam enters the steam turbine generator set 12 through the fifth pipe 13B, and the saturated steam entering the steam turbine generator set generates electricity through the steam turbine, which can reduce the amount of electricity purchased by the enterprise.

[0047] Part of the high-temperature and high-pressure top gas discharged from the top of the gas-based vertical furnace 1 enters the top gas scrubber 3 after passing through the top gas heat exchanger 2 to obtain clean top gas; the clean top gas discharged from the top gas scrubber 3 is divided into three sections: the first section of the top gas enters the process gas compressor 5, the process compressor 5 compresses the mixed gas of the supplementary gas and the first section of the top gas, and provides high-pressure reducing gas for the vertical furnace; the second section of the top gas enters the turbine expander 7; the mechanical energy generated by the expansion work of the turbine expander 7 reduces the power of the motor of the process gas compressor 5; the third section of the top gas enters the process gas heater 9 as the fuel gas of the process heater 9. It is burned together with the oxygen fed into the heater to provide energy for heating the main reducing gas entering the gas-based vertical furnace 1.

[0048] The flue gas generated by combustion in the process gas heater 9 is discharged through the chimney 17. The high-pressure furnace top gas of stage II is expanded by the turbine expander 7 to become low-pressure coal gas and enter the combustion boiler 10. The flue gas generated after combustion in the combustion boiler 10 is discharged through the chimney 17.

[0049] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction, and as long as they do not violate the concept of the present utility model, they should also be regarded as the contents disclosed by the present utility model.

Claims

1. A system for efficiently utilizing waste heat and waste pressure of top gas in a gas-based vertical furnace process, comprising a gas-based vertical furnace (1), a top gas heat exchanger (2) and a top gas scrubber (3) which are connected in sequence, characterized in that: The gas outlet of the furnace top gas scrubber (3) is connected to the gas inlet of the process gas compressor (5) via a first pipeline (4), connected to the gas inlet of the turbine expander (7) via a second pipeline (6), and connected to the combustion gas inlet of the process gas heater (9) via a third pipeline (8); The process gas outlet of the process gas compressor (5) is connected to the reducing gas inlet of the gas-based vertical furnace (1); The process gas outlet of the turbine expander (7) is connected to the fuel inlet of the combustion boiler (10).

2. The system for efficiently utilizing waste heat and waste pressure of top gas in a gas-based vertical furnace process according to claim 1, characterized in that: The steam outlet of the top gas heat exchanger (2) is connected to the steam inlet of the steam turbine generator set (12) via a fourth pipeline (13A), and the process gas outlet of the top gas heat exchanger (2) is connected to the air inlet of the top gas scrubber (3); the water inlet of the top gas heat exchanger (2) is connected to the softened water pipeline (11), and the air inlet of the top gas heat exchanger (2) is connected to the air outlet of the gas-based vertical furnace (1) via a pipeline; The softened water pipeline (11) is also connected to the water inlet of the combustion boiler (10), and the steam outlet of the combustion boiler (10) is connected to the steam inlet of the steam turbine generator set (12) via a fifth pipeline (13B).

3. The system for efficiently utilizing waste heat and waste pressure of top gas in a gas-based vertical furnace process according to claim 1, characterized in that: A mixed gas reformer (14) is also provided on the pipeline between the process gas compressor (5) and the gas-based vertical furnace (1).

4. The system for efficiently utilizing waste heat and waste pressure of top gas in a gas-based vertical furnace process according to claim 1, characterized in that: A clutch (15) is provided between the process gas compressor (5) and the turbine expander (7).

5. The system for efficiently utilizing waste heat and waste pressure of top gas in a gas-based vertical furnace process according to claim 1, characterized in that: The process gas compressor (5) is also connected to an electric motor (16).

6. The system for efficiently utilizing waste heat and waste pressure of top gas in a gas-based vertical furnace process according to claim 1, characterized in that: The process gas heater (9) is connected to the chimney (17) via a first smoke exhaust pipe (19), and the combustion boiler (10) is connected to the chimney (17) via a second smoke exhaust pipe (18).

7. The system for efficiently utilizing waste heat and waste pressure of top gas in a gas-based vertical furnace process according to claim 1, characterized in that: The process gas heater (9) is also connected to a first oxygenation pipeline; and the combustion boiler (10) is also connected to a second oxygenation pipeline.

8. The system for efficiently utilizing waste heat and waste pressure of top gas in a gas-based vertical furnace process according to claim 1, characterized in that: The first pipeline (4) is also connected to an air supply pipeline (20).

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