Slag waste heat recovery system and method capable of flexibly adjusting steam parameters

Abstract

The invention discloses a slag waste heat recovery system and method capable of flexibly adjusting steam parameters, relates to the technical field of slag waste heat recovery, and aims to solve the problems of low efficiency, single steam parameters, difficulty in control and the like in the current slag waste heat recovery link. According to the scheme, the slag is subjected to air blowing cooling, so that the cooled slag and hot air are obtained; the cooled slag is subjected to water preheating of a first branch in a conduction heat exchange mode, water vapor is prepared from the preheated water, and superheated saturated steam is prepared from the water vapor; hot air is used for preheating water of the second branch in a heat convection manner, and the preheated water is used for preparing water vapor; when high-temperature steam is needed, the blowing flow is reduced, the flow of the first branch is increased, and the flow of the second branch is reduced; and when low-temperature steam is needed, the blowing flow is increased, the flow of the first branch is reduced, and the flow of the second branch is increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of slag waste heat recovery, and in particular relates to a slag waste heat recovery system and method for flexibly adjusting steam parameters. Background Art

[0002] In the process of steelmaking and ferroalloy in converters and electric furnaces, a large amount of high-temperature slag or slag is produced. Slag or slag is the solid waste left after the metal ore undergoes a reduction reaction at high temperature and the metal and other valuable components are removed. The temperature of these slag or slag is usually between 1400℃ and 1600℃, containing a large amount of sensible heat, so this part of energy has a huge room for utilization.

[0003] The heat in the recovered slag can be used for preheating raw materials, producing steam and hot water, and even generating electricity, thereby reducing external energy consumption, reducing heat emissions, and reducing environmental pollution. The granulated slag can be used as building materials or other purposes to realize the resource utilization of waste. Through waste heat recovery and resource utilization, it can bring economic benefits to enterprises.

[0004] However, the existing technology only uses heat exchangers to extract heat from slag, so the waste heat recovery efficiency is still low in the existing technology, and the parameters of the produced steam are single and difficult to control, which cannot meet the complex steam usage needs of metallurgical enterprises, so the utilization rate of the produced steam is not high. This is a problem that needs to be solved urgently.

[0005] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0006] The purpose of the present invention is to solve the problems of low efficiency and single and difficult to control steam parameters in the current waste heat recovery link of slag, and to provide a slag waste heat recovery system and method with flexible adjustment of steam parameters.

[0007] A first aspect of the present invention provides a slag waste heat recovery system with flexible adjustment of steam parameters, comprising a slag melter, a conduction heat exchanger and a convection heat exchanger, a steam drum, a water supply system, and a fan;

[0008] The top of the conduction heat exchanger is provided with a filling port for adding slag particles, and the convection heat exchanger is provided with a superheater, a first evaporator and a first economizer arranged in sequence from top to bottom;

[0009] A second economizer is provided in the countercurrent heat exchanger;

[0010] The inlets of the first economizer and the second economizer are connected to the water supply system through pipelines, and the connected pipelines are respectively provided with a first flow valve and a second flow valve; the outlets of the first economizer and the second economizer are connected to the steam drum through pipelines;

[0011] The inlet and outlet of the first evaporator are both connected to the steam drum through pipelines; the inlet of the superheater is connected to the steam drum through pipelines;

[0012] Among the pipes connected to the steam drum, the pipe connected to the inlet of the superheater is connected to the steam drum at the highest position; the pipe connected to the inlet of the first evaporator is connected to the steam drum at the lowest position;

[0013] The slag melter, the convection heat exchanger and the fan are connected in sequence through pipelines.

[0014] In one embodiment of the present invention, a second evaporator is provided in the convection heat exchanger, and the inlet and outlet of the second evaporator are connected to the steam drum through pipes; the connection position of the pipe connecting the inlet of the second evaporator and the steam drum is also the lowest.

[0015] In one embodiment of the present invention, a dust collector is provided on the pipeline connecting the countercurrent heat exchanger and the fan.

[0016] In one embodiment of the present invention, the outlet of the blower is connected back to the slag melter through a pipeline to form a circulating blowing loop.

[0017] In one embodiment of the present invention, the discharge port of the slag container is located above the filling port and opposite to the filling port.

[0018] In one embodiment of the present invention, the slag melter is a rotor granulator.

[0019] The second aspect of the present invention provides a slag waste heat recovery method with flexible adjustment of steam parameters, wherein the slag is cooled by blowing air to obtain cooled slag and hot air; the cooled slag is used to preheat water in a first branch by conductive heat exchange, and water vapor is prepared from the preheated water, and superheated saturated steam is prepared from the water vapor; the hot air is used to preheat water in a second branch by convection heat exchange, and water vapor is prepared from the preheated water; when high-temperature steam is needed, the flow rate of the blowing air is reduced, while the flow rate of the first branch is increased and the flow rate of the second branch is reduced; when low-temperature steam is needed, the flow rate of the blowing air is increased, while the flow rate of the first branch is reduced and the flow rate of the second branch is increased.

[0020] Compared with the prior art, the technical effects achieved by the present invention are as follows:

[0021] 1. Extracting heat through both convection heat transfer and conduction heat transfer can improve the overall heat transfer efficiency and increase the amount of heat extracted.

[0022] 2. By changing the fan load, the working conditions of the first flow valve and the second flow valve, superheated saturated steam of different temperatures can be prepared, and the steam parameters can be flexibly adjusted to meet different steam usage requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of a slag waste heat recovery system with flexible adjustment of steam parameters according to an embodiment of the present invention.

[0024] Description of main reference numerals:

[0025] 1. Slag vessel; 2. Conduction heat exchanger; 3. Superheater; 4. First evaporator; 5. First economizer; 6. Steam drum; 7. Convection heat exchanger; 8. Second evaporator; 9. Second economizer; 10. Dust collector; 11. Fan; 12. First flow valve; 13. Second flow valve; 14. Water supply system. DETAILED DESCRIPTION

[0026] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0027] The technical solution of the present invention is described below by specific embodiments. It should be understood that one or more steps mentioned in the present invention do not exclude the existence of other methods and steps before and after the combination step, or other methods and steps can be inserted between these explicitly mentioned steps. It should also be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Unless otherwise specified, the numbering of each method step is only for the purpose of identifying each method step, and does not limit the order of arrangement of each method or limit the scope of implementation of the present invention. The change or adjustment of the relative relationship thereof can also be regarded as the scope of implementation of the present invention without substantial changes in the technical content.

[0028] The sources of the raw materials and instruments used in the examples are not particularly limited and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0029] According to a preferred embodiment of the present invention, a slag waste heat recovery method with flexible adjustment of steam parameters is used, the slag is cooled by blowing air to obtain cooled slag and hot air; the cooled slag is used to preheat water in a first branch by conduction heat exchange, and water vapor is prepared from the preheated water, and superheated saturated steam is prepared from the water vapor; the hot air is used to preheat water in a second branch by convection heat exchange, and water vapor is prepared from the preheated water; when high-temperature steam is needed, the flow rate of the blowing air is reduced, and the flow rate of the first branch is increased and the flow rate of the second branch is reduced; when low-temperature steam is needed, the flow rate of the blowing air is increased, and the flow rate of the first branch is reduced and the flow rate of the second branch is increased.

[0030] For the system or device used to implement the above method, reference may be made to one of the following implementations.

[0031] like Figure 1 As shown, a slag waste heat recovery system with flexible adjustment of steam parameters according to a preferred embodiment of the present invention includes a slag vessel 1, a conduction heat exchanger 2, a convection heat exchanger 7, a steam drum 6, a water supply system 14, and a fan 11.

[0032] The slag vessel 1 is a device for solidifying and granulating slag, which is specifically a rotor granulator. The rotor granulator is only a preferred choice of prior art equipment, and other technical types of equipment, such as rolling crushing and wind quenching, can also be implemented. The structure of the rotor granulator generally includes a granulator shell, a rotor is arranged inside the granulator shell, and a power system for driving the rotor to rotate is arranged outside the granulator shell. When working, the molten slag is poured onto the rotor, and the power system drives the rotor to rotate, and the slag is thrown onto the inner wall of the granulator shell with the help of centrifugal force. The slag is cooled and crushed during the collision, thereby forming a large number of solidified slag particles the size of soybeans, and then the slag particles will fall from the discharge port of the granulator shell.

[0033] The conduction heat exchanger 2 is a high tower structure container in which the conduction heat exchange process occurs, with a filling port for adding slag particles arranged at the top and a discharge port arranged at the bottom. The slag container 1 is fixed above the conduction heat exchanger 2 so that the outlet at the bottom of the slag container 1 is located above and opposite to the filling port, so that the slag particles in the slag container 1 can directly fall into the conduction heat exchanger 2. The superheater 3, the first evaporator 4 and the first economizer 5 are arranged in sequence from top to bottom inside the conduction heat exchanger 2. The slag particles entering the conduction heat exchanger 2 will fall due to gravity, and gradually contact the superheater 3, the first evaporator 4 and the first economizer 5 during the process.

[0034] The convection heat exchanger 7 is a high tower structure container in which the convection heat exchange process occurs, and the second evaporator 8 and the second economizer 9 are arranged in sequence from top to bottom. The slag tank 1, the convection heat exchanger 7 and the fan 11 are connected in sequence through pipelines, and the outlet of the fan 11 is connected back to the slag tank 1 through a pipeline, thereby forming a circulating air blowing loop. A dust collector 10 is also provided on the pipeline between the convection heat exchanger 7 and the fan 11. When the fan 11 is working, wind is first blown into the slag tank 1. The slag particles are cooled by air in the slag tank 1, thereby improving the solidification effect of the slag particles and extracting heat at the same time. Subsequently, the hot air enters the convection heat exchanger 7 under the action of wind pressure, and the hot air contacts the second evaporator 8 and the second economizer 9 in sequence.

[0035] The inlet of the first economizer 5 and the second economizer 9 are connected to the water supply system 14 through a pipeline, and the connected pipelines are respectively provided with a first flow valve 12 and a second flow valve 13. The outlet of the first economizer 5 and the outlet of the second economizer 9 are both connected to the steam drum 6 through a pipeline.

[0036] The inlet of the superheater 3 is connected to the steam drum 6 through a pipeline. The outlet of the superheater 3 extends out of the conduction heat exchanger 2 for connecting to a device or system using steam. The inlet and outlet of the first evaporator 4 are both connected to the steam drum 6 through a pipeline. The inlet and outlet of the second evaporator 8 are both connected to the steam drum 6 through a pipeline.

[0037] Among the pipes connected to the steam drum 6, the pipe connected to the inlet of the superheater 3 is connected to the steam drum 6 at the highest position; the pipe connecting the inlet of the first evaporator 4 and the inlet of the second evaporator 8 is connected to the steam drum 6 at the lowest position.

[0038] After the water supply system 14 starts supplying water, the water enters the first economizer 5 and the second economizer 9 through two branches. The water is heated in the first economizer 5 and the second economizer 9 to reach a preheated state. The preheated water will enter the steam drum 6, and under the action of gravity, the water enters the first evaporator 4 and the second evaporator 8. In the first evaporator 4 and the second evaporator 8, the water is heated to water vapor. The water vapor can rise spontaneously due to buoyancy and return to the steam drum 6. It further enters the superheater 3 from the steam drum 6. In the superheater 3, the water vapor is heated to superheated saturated steam, and then discharged and used.

[0039] When the steam temperature needs to be increased, the load of the fan 11 is reduced, so the air volume will decrease, and the heat exchange with the slag particles in the slag container 1 will decrease, which will lead to an increase in the temperature of the slag particles entering the conductive heat exchanger 2. Since the heat exchange efficiency is positively correlated with the temperature difference, the temperature of the superheated saturated steam will increase. And since the temperature of the slag particles entering the conductive heat exchanger 2 is high, in order to ensure that the solid particles discharged from the bottom of the conductive heat exchanger 2 are within a reasonable temperature range, it is necessary to increase the opening of the first flow valve 12. Correspondingly, the heat entering the conductive heat exchanger 2 is less, and the opening of the second flow valve 13 needs to be reduced.

[0040] When the steam temperature needs to be lowered, the load of the fan 11 is increased, so the air volume will increase, and the heat exchange with the slag particles in the slag container 1 will increase, which will cause the temperature of the slag particles entering the conductive heat exchanger 2 to drop, so the temperature of the superheated saturated steam will drop. Correspondingly, the opening of the first flow valve 12 needs to be lowered and the opening of the second flow valve 13 needs to be increased.

[0041] In summary, by changing the load of the fan 11 and the openings of the first flow valve 12 and the second flow valve 13, the temperature of the superheated saturated steam can be changed, so that steam with different parameters can be obtained to meet different steam usage requirements.

[0042] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A slag waste heat recovery system with flexible steam parameter adjustment, characterized in that: Includes slag furnace, conduction heat exchanger and convection heat exchanger, steam drum, water supply system, and fan; The top of the conduction heat exchanger is provided with a filling port for adding slag particles, and the convection heat exchanger is provided with a superheater, a first evaporator and a first economizer arranged in sequence from top to bottom; A second economizer is provided in the countercurrent heat exchanger; The inlets of the first economizer and the second economizer are connected to the water supply system through pipelines, and the connected pipelines are respectively provided with a first flow valve and a second flow valve; the outlets of the first economizer and the second economizer are connected to the steam drum through pipelines; The inlet and outlet of the first evaporator are both connected to the steam drum through pipelines; the inlet of the superheater is connected to the steam drum through pipelines; Among the pipes connected to the steam drum, the pipe connected to the inlet of the superheater is connected to the steam drum at the highest position; The connection position of the pipe connected to the inlet of the first evaporator and the steam drum is the lowest; The slag melter, the convection heat exchanger and the fan are connected in sequence through pipelines.

2. The slag waste heat recovery system with flexible steam parameter adjustment according to claim 1 is characterized in that: The countercurrent heat exchanger is provided with a second evaporator, and the inlet and outlet of the second evaporator are both connected to the steam drum through pipelines; the connection position of the pipeline connecting the inlet of the second evaporator and the steam drum is also the lowest.

3. The slag waste heat recovery system with flexible steam parameter adjustment according to claim 1 is characterized in that: A dust collector is provided on the pipeline connecting the countercurrent heat exchanger and the fan.

4. The slag waste heat recovery system with flexible steam parameter adjustment according to claim 1 is characterized in that: The outlet of the blower is connected back to the slag melter through a pipeline to form a circulating blowing loop.

5. The slag waste heat recovery system with flexible steam parameter adjustment according to claim 1 is characterized in that: The discharge port of the slag maker is located above the filling port and opposite to the filling port.

6. The slag waste heat recovery system with flexible steam parameter adjustment according to claim 1 is characterized in that: The slag smelter is a rotor granulator.

7. A slag waste heat recovery method with flexible adjustment of steam parameters, characterized in that: The slag is cooled by blowing air, thereby obtaining cooled slag and hot air; the cooled slag is used to preheat water in the first branch by means of conduction heat exchange, and water vapor is prepared from the preheated water, and superheated saturated steam is prepared from the water vapor; the hot air is used to preheat water in the second branch by means of convection heat exchange, and water vapor is prepared from the preheated water; when high-temperature steam is needed, the flow rate of the blowing air is reduced, while the flow rate of the first branch is increased and the flow rate of the second branch is reduced; When low-temperature steam is needed, the flow rate of the blowing air is increased, while the flow rate of the first branch is reduced and the flow rate of the second branch is increased.

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