Roasting waste heat utilization system for aluminum oxide production

Abstract

The utility model relates to an aluminum oxide production roasting waste heat utilization system, and belongs to the technical field of industrial production waste heat utilization. The system comprises a water tank, a water replenishing valve, a circulating water pump, a fluidized bed heat exchanger, a flue gas heat exchanger, a stock solution heating heat exchanger, a stock solution pump and a circulating water pipe, circulating water sequentially passes through the fluidized bed heat exchanger, the flue gas heat exchanger and the stock solution heating heat exchanger and then returns to the circulating water pump, the circulating water takes heat at the fluidized bed heat exchanger and the flue gas heat exchanger, and the heat is transferred to the stock solution in the stock solution heating heat exchanger. According to the system, a large amount of waste heat generated in the roasting process of aluminum hydroxide is scientifically and reasonably recycled, the energy consumption of thermal equipment is reduced, meanwhile, circulating water conducts indirect heat exchange with the stock solution in the stock solution heating heat exchanger, the recycled waste heat is effectively utilized, and obvious technical advantages and economic advantages are achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of industrial production waste heat utilization, and specifically relates to an aluminum oxide production roasting waste heat utilization system. Background Art

[0002] The statements in this section are merely intended to provide background information related to the technical solution of the present application to aid understanding, and they do not necessarily constitute prior art for the technical solution of the present application.

[0003] The last step in alumina production is the roasting of aluminum hydroxide. 2 O 3 For secondary cooling, the smoke from the roasting furnace needs to be discharged. When the material comes out of the roasting furnace cyclone, the temperature is still around 220-300°C and cannot directly enter the conveying system. For the safety of equipment and personnel, cooling water in the fluidized bed cooler conducts indirect heat exchange with the material through the pipe network to reduce the material temperature to below 80°C. The exhaust temperature of the roasting furnace is 130-140°C, and it is currently directly discharged into the atmosphere. The tail exhaust gas volume is large. The exhaust heat of the roasting furnace and the alumina waste heat recovered by the fluidized bed have great recycling value. If it is not recycled, it will cause a large waste of waste heat energy.

[0004] The temperature of the evaporated raw liquid is limited by the production process system of the decomposition sand product. Only one-half of the amount can be exchanged with the fine plate. The temperature of the raw liquid is generally not higher than 75°C, and the temperature needs to be improved. Utility Model Content

[0005] In order to make full use of the above fluidized bed heat and flue gas heat, the recovered heat is used to heat the raw liquid in the evaporation process, increase the raw liquid temperature, and reduce energy waste. The utility model is designed to utilize the waste heat from the roasting of alumina production. The specific technical scheme is as follows:

[0006] A system for utilizing waste heat from roasting in the production of alumina, comprising a circulating water pump, a fluidized bed heat exchanger, a flue gas heat exchanger, a stock liquid heating heat exchanger, a stock liquid pump and a circulating water pipe, wherein the stock liquid heating heat exchanger comprises a circulating water flow path and a stock liquid flow path, and the stock liquid pump is arranged in an upstream pipeline of the stock liquid flow path; the fluidized bed heat exchanger comprises a circulating water path and a material path; the flue gas heat exchanger comprises a circulating pipeline and a flue gas path; the circulating water path of the fluidized bed heat exchanger, the circulating pipeline of the flue gas heat exchanger, the circulating water path of the stock liquid heating heat exchanger and the circulating water pump are connected in sequence via the circulating water pipe, and at the same time, the circulating water pump is connected to the circulating water path of the fluidized bed heat exchanger via the circulating water pipe, together forming a water path circulation.

[0007] Furthermore, the alumina production roasting waste heat utilization system also includes a water tank, a water supply valve and a water supply pipe. The water tank is connected to the circulating water pipe between the circulating water pump and the fluidized bed heat exchanger via the water supply pipe, and the water supply valve is arranged on the water supply pipe.

[0008] Furthermore, the raw liquid heating heat exchanger is a fine plate heat exchanger.

[0009] Compared with the prior art, the beneficial technical effects of the utility model are:

[0010] The circulating water passes through the fluidized bed heat exchanger, flue gas heat exchanger, and stock liquid heating heat exchanger in turn and then returns to the inlet of the circulating water pump. Water can be replenished according to the flow change of the circulating water pump. After the evaporation stock liquid pump is turned on, the stock liquid or the medium that needs to be heated passes through the stock liquid heating heat exchanger (fine plate heat exchanger). The circulating water takes heat at the fluidized bed heat exchanger and the flue gas heat exchanger, so that the circulating water is heated from about 80°C to 110°C. The circulating water indirectly exchanges heat with the stock liquid or the medium that needs to be heated in the stock liquid heating heat exchanger (fine plate heat exchanger), so that the stock liquid temperature rises by about 5-10°C before entering the evaporator or stock liquid tank. Heating the stock liquid can effectively utilize the recovered waste heat, and there is no need to add additional circulating water cooling equipment. The cooling process of the circulating water can be achieved through heat exchange and water replenishment of the stock liquid heating heat exchanger. This system makes full use of the heat of the fluidized bed and the flue gas. The recovered heat is used to heat the raw liquid in the evaporation process, increase the raw liquid temperature, reduce energy waste, and has a simple process with obvious technical and economic advantages. It can improve the utilization level of waste heat energy in the production process of thermal equipment of alumina production enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of the system for utilizing waste heat from roasting in the production of alumina in the embodiment.

[0012] Among them, there are water supply valve-1, circulating water pump-2, fluidized bed heat exchanger-3, flue gas heat exchanger-4, raw liquid heating heat exchanger-5, raw liquid pump-6 and circulating water pipe-7. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical solution and advantages of the utility model more clear, the following is a detailed description of the alumina production roasting waste heat utilization system of the present application in combination with the embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model, and are not used to limit the utility model.

[0014] The utility model discloses an alumina production roasting waste heat utilization system, comprising a water tank, a water supply valve 1, a circulating water pump 2, a fluidized bed heat exchanger 3, a flue gas heat exchanger 4, a stock liquid heating heat exchanger 5, a stock liquid pump 6 and a circulating water pipe 7, wherein the stock liquid heating heat exchanger 5 is a fine plate heat exchanger. The specific operation steps are as follows:

[0015] Step 1: Open the water supply valve 1 and make sure the circulating water pipe 7 is full of water

[0016] Step 2: Start the circulating water pump 2;

[0017] Step 3: The circulating water passes through the fluidized bed heat exchanger 3, then the flue gas heat exchanger 4, then the stock liquid heating heat exchanger 5, and finally returns to the circulating water pump inlet, and then repeats the above cycle process;

[0018] Step 4: Turn on the stock liquid pump 6, the stock liquid flows into the stock liquid heating heat exchanger 5, is heated by the circulating water, and then flows out of the heat exchanger and enters the evaporator or the stock liquid tank.

[0019] The heat recovery in the specific embodiment is shown in Table 1:

[0020] The heat recovery of the raw liquid is estimated according to the following formula:

[0021] QUR 2 O 3 (heat recovery of raw liquid) = average feed volume * raw liquid temperature rise * raw liquid specific gravity * specific heat;

[0022] The hourly recovery energy of the raw liquid is converted into 0.6MPa saturated steam (enthalpy value 2756kJ / kg) = (Q5gAl 2 O 3 *0.95) / (2756*1000);

[0023] The specific gravity of the stock solution is 1.28g / cm 3 , specific heat is 3.6J / g.℃.

[0024]

[0025] It can be seen from the above table that after passing through the waste heat recovery system of the utility model, the temperature of the raw liquid increases by about 5-10℃, and the heat recovery of the raw liquid can reach 6.8×10 6 kJ / h or more, and the hourly recovered energy converted into 0.6MPa saturated steam can reach more than 2t / h. The system can effectively recover the waste heat of the fluidized bed and the flue gas and realize the heating of the raw liquid, with high heat recovery efficiency.

Claims

1. A system for utilizing waste heat from roasting of alumina production, characterized in that: It comprises a circulating water pump (2), a fluidized bed heat exchanger (3), a flue gas heat exchanger (4), a raw liquid heating heat exchanger (5), a raw liquid pump (6) and a circulating water pipe (7), wherein the raw liquid heating heat exchanger (5) comprises a circulating water flow path and a raw liquid flow path, and the raw liquid pump (6) is arranged in the upstream pipeline of the raw liquid flow path; the fluidized bed heat exchanger (3) comprises a circulating water path and a material path; the flue gas heat exchanger (4) comprises a circulating pipeline and a flue gas path; the circulating water path of the fluidized bed heat exchanger (3), the circulating pipeline of the flue gas heat exchanger (4), the circulating water path of the raw liquid heating heat exchanger (5), and the circulating water pump (2) are connected in sequence via the circulating water pipe (7), and at the same time, the circulating water pump (2) is connected to the circulating water path of the fluidized bed heat exchanger (3) via the circulating water pipe (7), together forming a water path circulation.

2. The alumina production roasting waste heat utilization system according to claim 1, characterized in that: It also comprises a water tank, a water supply valve (1) and a water supply pipe, wherein the water tank is connected to the circulating water pipe (7) between the circulating water pump (2) and the fluidized bed heat exchanger (3) via the water supply pipe, and the water supply valve (1) is arranged on the water supply pipe.

3. The alumina production roasting waste heat utilization system according to claim 1, characterized in that: The raw liquid heating heat exchanger (5) is a fine plate heat exchanger.

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