High-temperature material waste heat recovery system

Abstract

The invention discloses a high-temperature material waste heat recovery system which comprises a cooling device used for cooling materials; the low-temperature water circulation unit is communicated with the cooling device and is used for carrying out indirect heat exchange on the materials in the cooling device; the high-temperature steam-water circulation unit is respectively communicated with the cooling device and the low-temperature water circulation unit to form circulation and is used for carrying out indirect heat exchange on the materials in the cooling device; and finally, double forced circulation is formed on the cooling device. According to the waste heat recovery device, the dual functions of high-temperature material cooling and waste heat recovery are achieved, waste heat in the high-temperature material cooling process is recovered and effectively utilized, and the waste heat recovery efficiency and the economic value are improved.

Description

Technical Field

[0001] The present invention relates to the fields of metallurgy, solid waste treatment and resource utilization, and more specifically, to a high-temperature material waste heat recovery system. Background Art

[0002] The rotary hearth furnace is a high-temperature furnace. Currently, there are many studies on the waste heat recovery of its high-temperature flue gas, but there are fewer studies on the waste heat recovery of high-temperature materials discharged from the rotary hearth furnace.

[0003] The temperature of the high-temperature material after reduction in the rotary hearth furnace is about 1000-1100℃. The metallization rate of the material is generally 50%-90%. In addition, it also contains a certain proportion of silicon, silicon, aluminum, magnesium and other oxides and other substances. The material can be directly used in the blast furnace or steelmaking furnace through the hot delivery system, but due to the high technical requirements and cost of hot charging equipment, and the problems of matching with the user system, most of the relevant production lines in the industry cool the high-temperature material before transporting it to the user or taking it out.

[0004] The cooling medium is usually water, and there are two main types of cooling devices: external spray cooling cylinder and internal cooling cooling cylinder. In the external cooling cylinder, part of the cooling water evaporates, and part is collected through the pool at the bottom of the cooler and recycled. The internal cooling cylinder usually adopts a closed water cooling system, and the high-temperature circulating water is cooled by the cooling tower and then recycled.

[0005] It can be seen that no matter whether it is external cooling or internal cooling equipment, the sensible heat of high-temperature materials is not recovered and utilized.

[0006] In existing patent applications, such as patent publication number CN 102183154 A, a waste heat recovery device and method for the cooling process of red-hot pellets in a rotary hearth furnace are disclosed. 1) The material tank is arranged on the upper pipe of the countercurrent cooler and connected to the first-level pre-dust collector. The first-level pre-dust collector pipe is connected to the upper part of the boiler. The bottom of the boiler is connected to the second-level bag dust collector. The second-level bag dust collector is connected to the lower part of the vertical countercurrent cooler through a circulating fan. 2) The waste heat recovery method includes the following steps: low-temperature nitrogen and red-hot pellets are contacted and heat exchanged to 800°C; high-temperature nitrogen dust removal; high-temperature nitrogen is cooled to 200°C and steam is generated; the cooled nitrogen is dusted again; and low-temperature nitrogen is recycled. The invention is used to realize nitrogen closed-loop circulation, thereby realizing the recycling of energy media, and realizing rapid cooling through contact countercurrent heat exchange. However, the patent uses nitrogen to directly contact the high-temperature pellets, and does not consider how to maintain a reasonable flow of nitrogen in the cooler to ensure cooling effect and heat exchange efficiency.

[0007] For example, patent publication number CN 116772593 A discloses a device and method for cooling and recovering waste heat of high-temperature pellets in a rotary hearth furnace. 1) The equipment includes a primary cooling device, a secondary cooling device, a waste heat boiler system, a soft water supply system, a detection and regulation system, and a control system; 2) The invention adopts a two-stage cooling and two-stage heat recovery method to recover the heat energy released by the high-temperature pellets, and at the same time, the cooling water used in the heat recovery process can be recycled, thereby solving the problems of heat loss and resource waste in the cooling process of the high-temperature pellets. However, the patent uses two cooling devices, which were previously connected by a chute, and the equipment configuration is cumbersome and the investment is large; the secondary cooling device in the patent needs to heat the water supply to above 100°C to achieve the deoxygenation requirement, resulting in a mismatch in the cooling medium flow in the two-stage cooling device, and it needs to be used in conjunction with other heat sources to achieve system steam-water balance. Summary of the invention

[0008] In view of the defects existing in the prior art, the purpose of the present invention is to provide a high-temperature material waste heat recovery system, which realizes the dual functions of high-temperature material cooling and waste heat recovery, which not only recovers the waste heat in the high-temperature material cooling process and makes effective use of it, but also improves the waste heat recovery efficiency and economic value.

[0009] To achieve the above object, the present invention adopts the following technical solution:

[0010] A high-temperature material waste heat recovery system, comprising:

[0011] A cooling device for cooling the material;

[0012] A low-temperature water circulation unit is connected to the cooling device and is used to indirectly exchange heat with the material in the cooling device;

[0013] A high-temperature steam-water circulation unit is respectively connected with the cooling device and the low-temperature water circulation unit to form a circulation, so as to indirectly exchange heat with the material in the cooling device;

[0014] Finally, a double forced circulation is formed on the cooling device.

[0015] Preferably, the cooling device adopts a horizontal rotary membrane wall water cooling structure.

[0016] Preferably, the low-temperature water circulation unit comprises a water storage tank and a deaerator;

[0017] The water storage tank is connected to the deaerator through a first water inlet pipeline;

[0018] The deaerator is connected to the low-temperature circulating water inlet pipeline of the cooling device through a second water inlet pipeline.

[0019] Preferably, the high-temperature steam-water circulation unit comprises a steam drum;

[0020] The steam drum is connected to the high-temperature circulating water inlet pipeline of the cooling device through a third water inlet pipeline.

[0021] Preferably, the first water inlet pipeline, the second water inlet pipeline, and the third water inlet pipeline are all provided with a water pump, a valve, and a bypass;

[0022] The bypass is also provided with a water pump and a valve.

[0023] Preferably, the cooling device, the deaerator and the steam drum are all connected with a sewage pipeline and a dosing device.

[0024] Preferably, the deaerator, the steam drum, the first water inlet pipeline, the second water inlet pipeline, and the third water inlet pipeline are all provided with a flow meter, a pressure gauge, and a temperature gauge.

[0025] The high-temperature material waste heat recovery system provided by the present invention has the following beneficial effects:

[0026] 1) The high-temperature material waste heat recovery system of the present invention is used to cool the high-temperature material to below 150° C., thereby meeting the cooling requirements of the high-temperature material;

[0027] 2) The high-temperature material waste heat recovery system of the present invention is used to separate the steam-water mixture and generate high-temperature steam, which can be incorporated into the plant network or used for other purposes, thus realizing waste heat recovery;

[0028] 3) The high-temperature material waste heat recovery system of the present invention cooperates with the high-temperature steam-water circulation unit to solve the problems of low pressure and low temperature of recovered steam and limited energy reuse;

[0029] 4) The high-temperature material waste heat recovery system of the present invention adopts a double-circulation waste heat recovery system to recover waste heat in stages, thereby improving waste heat recovery efficiency; at the same time, the material temperature is reduced, which is more conducive to subsequent transportation of the material and reduces the risk of reoxidation;

[0030] 5) The high-temperature material waste heat recovery system of the present invention adopts a vacuum deaerator, which reduces the low-temperature water inlet temperature of the cooling device on the basis of ensuring water quality, and improves the waste heat recovery level; in addition, the use of this deaerator gets rid of the limitation of the low-temperature circulating water temperature, which is more conducive to flexible configuration of the system;

[0031] 6) The high-temperature material waste heat recovery system of the present invention can be set up independently or considered together with other waste heat recovery systems, so the configuration is more flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the structural framework of the high-temperature material waste heat recovery system of the present invention;

[0033] Figure 2 Schematic diagram of a cooling device in the high-temperature material waste heat recovery system of the present invention;

[0034] Figure 3 yes Figure 2 Schematic side view of . DETAILED DESCRIPTION

[0035] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0036] Combination Figures 1 to 3 As shown, the present invention provides a high-temperature material waste heat recovery system, comprising:

[0037] Cooling device 1, the material enters the cooling device 1 through the material conveying channel 2 (chute), and under the joint action of the cylinder rotation of the cooling device 1 and the spiral material guide trough, the material gradually moves to the discharge end 101 of the cooling device 1. The cooling device 1 adopts a horizontal rotary membrane wall water cooling structure. During the movement of the material, the material is constantly in contact with the cylinder wall of the cooling device 1, and the heat is transferred to the heat conducting medium 3 flowing in the membrane wall. After the material passes through the cooling device 1, the temperature can drop to below 150°C, achieving the purpose of cooling the material.

[0038] The cooling device 1 is connected with double forced circulation, namely, a low-temperature water circulation unit and a high-temperature steam-water circulation unit. Two circulations are adopted on the same cooling device 1 to realize segmented recovery of waste heat of high-temperature materials respectively. The waste heat recovery efficiency is high and the cooling effect of high-temperature materials is better.

[0039] The low-temperature water circulation unit includes a water storage tank 4 and a deaerator 5.

[0040] The cooling water from the water tank 4 (the water quality should meet the requirements for boiler water) enters the deaerator 5 through the water pump on the first water inlet pipeline 6, and then enters the low-temperature circulation water inlet pipe of the cooling device 1 through the water pump of the second water inlet pipeline 7 after decompression and deoxygenation. The cooling water is distributed to the membrane wall of the low-temperature section through the rotary joint and the water distributor. The cooling water flows in the membrane wall of the low-temperature section and indirectly exchanges heat with the high-temperature material in the cylinder of the cooling device 1. Each waterway in the low-temperature water circulation unit is connected to the return device. The cooling water after heat exchange enters the steam drum 8 under pressure through the return device, the rotary joint and the external pipeline, and serves as the supplementary water of the steam drum 8.

[0041] The high-temperature steam-water circulation unit comprises a steam drum 8.

[0042] The cooling water in the drum 8 is forcibly sent to the high-temperature circulating water inlet pipe of the cooling device 1 through the water pump on the third water inlet pipeline 9. The high-temperature circulating water inlet pipe is connected to the rotary joint and high-temperature water distributor of the water cooling device 1. The cooling water flows in the membrane wall of the water cooling device 1 and indirectly exchanges heat with the high-temperature material inside the water cooling device 1. Part of the water is vaporized during the heat exchange process, and the flowing medium in the pipeline of the membrane wall is actually a steam-water mixture. Each waterway in the high-temperature steam-water circulation unit is connected to the return device. Under the action of pressure, the steam-water mixture passes through the return device, the rotary joint and the external pipeline and then returns to the drum 8. Steam and water separation is achieved in the drum 8, wherein the separated saturated steam is transported to the outside through the steam pipeline 10 at the top of the drum 8, and the separated high-temperature water is used as the water inlet of the high-temperature circulation system.

[0043] The first water inlet pipeline 6, the second water inlet pipeline 7 and the third water inlet pipeline 9 are all provided with bypasses, and the bypasses are also provided with water pumps and valves as backup pipelines.

[0044] The cooling device 1, the deaerator 5 and the steam drum 8 are also connected with a sewage pipeline and a dosing device 11 to ensure the water quality of the system.

[0045] The deaerator 5, the steam drum 8 and the steam pipe 10 are provided with safety valves and emptying devices for emergency release.

[0046] The deaerator 5, the steam drum 8, the first water inlet pipeline 6, the second water inlet pipeline 7 and the third water inlet pipeline 9 are all provided with various flow meters, pressure gauges and temperature gauges for system control and feedback.

[0047] In order to ensure the safety of the high-temperature material waste heat recovery system of the present invention and the utilization value of saturated steam, a reasonable system pressure is selected, and the saturated steam pressure is ≥0.8MPa.

[0048] All water pumps are variable frequency pumps.

[0049] Example

[0050] In the 250,000-ton rotary hearth furnace production line, various zinc-iron dusts, reducing agents (here C-containing raw materials such as coal powder or coke powder are used), and binders are batched, mixed, and pelletized according to the process requirements. After the raw balls are dried, they enter the rotary hearth furnace. The materials are calcined and reduced at a high temperature of 1000-1300°C in the rotary hearth furnace. The temperature of the reduced pellets and powder is about 1100°C, and they are discharged out of the furnace by a spiral discharging machine. The discharge rate is about 25t / h. The high-temperature materials enter the cooling device 1 of the high-temperature material waste heat recovery system of this embodiment through the chute.

[0051] The high temperature section of the cooling device 1 has a diameter of 2.5m and a length of about 15m. After cooling in the high temperature section, the material temperature is about 240°C. Then it enters the low temperature section for cooling. The low temperature section has a diameter of 2.5m and a length of about 6m. After cooling in the low temperature section, the material temperature is about 140-150°C.

[0052] Parameters of high-temperature steam-water circulation unit: inlet medium temperature is about 184°C, outlet medium temperature is 184°C;

[0053] Parameters of the low-temperature water circulation unit: inlet medium temperature is about 40℃, outlet medium temperature is 100℃.

[0054] The deaerator 5 in the low-temperature water circulation unit uses a vacuum deaerator with an internal pressure of 0.06-0.09MPa. It boils the low-temperature water by maintaining a certain vacuum degree. Less heating steam is required and the outlet water temperature of the vacuum deaerator is low, so the waste heat utilization effect is good.

[0055] The high-temperature material waste heat recovery system of this embodiment generates about 6 t / h of 1.0 MPa saturated steam through waste heat recovery.

[0056] The pressure, temperature, gas production and other parameters of the high-temperature material waste heat recovery system of this embodiment can be adjusted according to the actual project.

[0057] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A high-temperature material waste heat recovery system, characterized in that: include: A cooling device for cooling the material; A low-temperature water circulation unit is connected to the cooling device and is used to indirectly exchange heat with the material in the cooling device; A high-temperature steam-water circulation unit is respectively connected with the cooling device and the low-temperature water circulation unit to form a circulation, so as to indirectly exchange heat with the material in the cooling device; Finally, a double forced circulation is formed on the cooling device.

2. The high temperature material waste heat recovery system according to claim 1 is characterized in that: The cooling device adopts a horizontal rotary membrane wall water cooling structure.

3. The high temperature material waste heat recovery system according to claim 2 is characterized in that: The low-temperature water circulation unit includes a water storage tank and a deaerator; The water storage tank is connected to the deaerator through a first water inlet pipeline; The deaerator is connected to the low-temperature circulating water inlet pipeline of the cooling device through a second water inlet pipeline.

4. The high temperature material waste heat recovery system according to claim 3 is characterized in that: The high-temperature steam-water circulation unit includes a steam drum; The steam drum is connected to the high-temperature circulating water inlet pipeline of the cooling device through a third water inlet pipeline.

5. The high temperature material waste heat recovery system according to claim 4 is characterized in that: The first water inlet pipeline, the second water inlet pipeline and the third water inlet pipeline are all provided with a water pump, a valve and a bypass; The bypass is also provided with a water pump and a valve.

6. The high temperature material waste heat recovery system according to claim 5, characterized in that: The cooling device, the deaerator and the steam drum are all connected with a sewage discharge pipeline and a dosing device.

7. The high temperature material waste heat recovery system according to claim 5, characterized in that: The deaerator, the steam drum, the first water inlet pipeline, the second water inlet pipeline, and the third water inlet pipeline are all provided with a flow meter, a pressure gauge, and a temperature gauge.

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