Method for eliminating use of fresh steam in aluminum oxide production hot water tank

Abstract

The invention discloses a method for eliminating fresh steam used by a hot water tank in aluminum oxide production, which comprises the following steps of: introducing high-temperature condensed water of a last-effect forced evaporator into a position at least 3 meters below the liquid level of the hot water tank by adopting a pipeline system so as to mix and raise the temperature, the last-effect forced evaporator is a last-effect forced evaporator of two groups of multi-effect evaporators, the hot water tank is a washing water heating tank for a filter cake filtered by aluminum hydroxide; according to the method, the temperature of high-temperature condensate water of a last-effect forced evaporator is 116 DEG C, after the high-temperature condensate water is introduced into a hot water tank through a pipeline system, water in the hot water tank can be heated to 92.3 DEG C, the flow is still 190 m < 3 > / h, the washing water requirement and other requirements for aluminum hydroxide filtering filter cakes are met, new steam does not need to be introduced into the hot water tank for heating, and 3 t of new steam is saved per hour.

Description

Technical Field

[0001] The invention relates to the field of alumina production, and in particular to a method for eliminating new steam used in a hot water tank in alumina production. Background Art

[0002] In the process of alumina production, the filter cake after aluminum hydroxide filtration needs to be washed with hot water to reduce the alkali content of the filter cake. The washing effect of low-temperature hot water is poor, resulting in increased alkali content, which affects product quality and alkali loss. However, the amount of hot water for alumina production is limited and cannot fully meet the process requirements of each part, resulting in low temperature in the hot water tank and high alkali content in the filter cake after aluminum hydroxide filtration. The commonly used method for heating the washing water is to add a heat exchanger for heating, but the process is complicated and the cleaning and maintenance of the heat exchanger is difficult and expensive. The most direct method is to use new steam for heating, which results in waste of new steam consumption. Evaporation system (such as Figure 2 As shown in the figure, I, II, Ш, IV: evaporator; 1, 2, 3, 4, 5: condensed water self-evaporation tank; ①, ②, ③: preheater; a, b, c, d: flash evaporator;) In order to save energy, the new steam heating is carried out in effect I or extended to effect II, and the exhaust steam generated after heating and the exhaust steam generated by the self-evaporation of high-temperature condensed water are recovered to heat the next stage. Due to the relatively low condensed water temperature (116℃) after multi-stage exhaust steam recovery heating, and the self-evaporation capacity of the condensed water self-evaporation tank is limited, the high-temperature condensed water of the last effect forced evaporator enters the mixing, and then evaporates through the 5-effect condensed water self-evaporation tank, and the exhaust steam generated is relatively small, resulting in the failure to maximize the utilization of the high-temperature condensed water waste heat generated by the last effect forced evaporator heating. In order to improve the operation effect of the deaerator, the exhaust is emptied. During the exhaust process, some exhaust steam generated by the self-evaporation of hot water is attached, which causes waste and also brings noise pollution. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a method for eliminating the use of new steam in the hot water tank for alumina production, so as to at least solve the technical problem that the waste heat of high-temperature condensed water generated by heating the last-effect forced evaporator cannot be maximized.

[0004] The objective of the present invention is achieved through the following technical solutions:

[0005] A method for eliminating the use of fresh steam in a hot water tank for aluminum oxide production comprises the following steps:

[0006] A pipeline system is used to introduce high-temperature condensed water from the last-effect forced evaporator into a hot water tank at least 3 meters below the liquid surface for mixing and temperature raising. The last-effect forced evaporator is the last-effect forced evaporator of two groups of multiple-effect evaporators, and the hot water tank is a washing water heating tank for filter cakes filtered by aluminum hydroxide.

[0007] Furthermore, it also includes the following steps: using a second pipeline to introduce the exhaust gas discharged from the thermoelectric deaerator into the hot water tank at least 3.5 meters below the liquid surface to mix and increase the temperature.

[0008] Furthermore, the pipeline system is vertically inserted into the hot water tank below the liquid surface in a multi-point manner and is staggered in height below the liquid surface.

[0009] The beneficial effects of the present invention are:

[0010] The present invention provides a method for eliminating the use of new steam in a hot water tank for aluminum oxide production. The temperature of high-temperature condensed water from a final-effect forced evaporator is 116°C. After being introduced into a hot water tank through a pipeline system, the water in the hot water tank can be heated to 92.3°C. The flow rate is still 190m3 / h, which can meet the washing water demand and other demands for filter cakes filtered by aluminum hydroxide. There is no need to introduce new steam into the hot water tank for heating, thereby saving 3t of new steam per hour.

[0011] Compared with the traditional method of introducing the high-temperature condensed water of the last-effect forced evaporator into the V-effect condensed water self-evaporation tank to mix with its low-temperature condensed water, and utilizing the condensed water self-evaporation tank for self-evaporation to generate exhaust steam for recycling, according to the self-evaporation efficiency of the condensed water self-evaporation tank, the exhaust steam generated by the high-temperature condensed water part of the last-effect forced evaporator can be ignored for offsetting the new steam of the evaporation system, which is far less than the new steam amount of 3t / h saved by introducing the hot water tank. Through the present invention, the waste heat of the high-temperature condensed water of the last-effect forced evaporator is maximized, achieving a significant energy-saving and consumption-reducing effect.

[0012] The high-temperature condensed water from the last-effect forced evaporator no longer enters the V-effect condensed water self-evaporation tank for self-evaporation, which has no obvious impact on the operation and energy saving of the evaporation system.

[0013] The exhaust gas discharged from the thermoelectric deaerator 3 is accompanied by exhaust steam. Introducing the exhaust gas discharged from the thermoelectric deaerator 3 into the hot water tank can further increase the temperature of the water in the hot water tank and eliminate the noise pollution caused by emptying.

[0014] The pipe system is inserted under the liquid surface of the hot water tank at multiple points to increase the mixing efficiency of the high-temperature condensed water and the water in the hot water tank.

[0015] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings, in which:

[0017] Figure 1 It is a schematic diagram of the structure of the present invention.

[0018] Figure 2 It is a schematic diagram of utilizing high-temperature condensed water of an existing last-effect forced evaporator.

[0019] In the figure: final effect forced evaporator 1, hot water tank 2, thermoelectric deaerator 3, first pipeline 4. DETAILED DESCRIPTION

[0020] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the preferred embodiments are only for illustrating the present invention, rather than for limiting the protection scope of the present invention.

[0021] Embodiment 1

[0022] like Figure 1 As shown, a method for eliminating the use of new steam in a hot water tank for alumina production comprises the following steps:

[0023] Two first pipes 4 are used to introduce high-temperature condensed water from the two last-effect forced evaporators 1 into a hot water tank 2 at least 3 meters below the liquid surface for mixing and temperature raising (the depth of the hot water tank 2 is 10 meters). The temperature of the high-temperature condensed water from the last-effect forced evaporator 1 is 116°C. The two last-effect forced evaporators 1 are the last-effect forced evaporators of two groups of four-effect evaporators. The hot water tank 2 is a washing water heating tank for filter cake filtered by aluminum hydroxide. The outlets of the two first pipes are arranged at intervals in the hot water tank.

[0024] The relevant data before and after the application of this embodiment are compared, as shown in Table 1:

[0025] Table 1

[0026]

[0027] It can be seen from the above table that the high-temperature condensed water from the last-effect forced evaporator 1 of the two groups of four-effect evaporators is introduced into the hot water tank 2 for mixing and temperature increase, which has no obvious effect on the operation and energy saving of the evaporation system. The temperature of the water in the hot water tank 2 is increased by 7.8℃, eliminating the waste of 3t new steam used in the hot water tank 2 per hour.

[0028] Embodiment 2

[0029] like Figure 1 As shown, the difference from the first embodiment is that it also includes the following steps:

[0030] The exhaust gas discharged from the thermoelectric deaerator 3 is introduced into the hot water tank 2 at least 3.5 meters below the liquid level through a second pipeline for mixing and temperature raising.

[0031] The exhaust gas discharged from the thermoelectric deaerator 3 is accompanied by exhaust steam. Introducing the exhaust gas discharged from the thermoelectric deaerator 3 into the hot water tank can further increase the temperature of the water in the hot water tank and eliminate the noise pollution caused by emptying.

[0032] Embodiment 3

[0033] The difference from Example 1 is that a pipeline system is used to introduce the high-temperature condensed water of the two last-effect forced evaporators 1 into the hot water tank 2 at least 3 meters below the liquid surface for mixing and temperature increase. The specific pipeline system includes two main pipes, a coil and multiple branch pipes. The two main pipes are respectively connected to the two ends of the coil. The coil is located above the liquid surface of the hot water tank and is horizontal. Multiple branch pipes are evenly spaced under the coil. The multiple branch pipes are of different lengths. The multiple branch pipes are vertically inserted below the liquid surface of the hot water tank and are staggered in height. The shortest branch pipe extends at least 3 meters below the liquid surface of the hot water tank.

[0034] The pipe system is inserted under the liquid surface of the hot water tank at multiple points to increase the mixing efficiency of the high-temperature condensed water and the water in the hot water tank.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for eliminating the use of fresh steam in a hot water tank for alumina production, characterized in that: The steps include: A pipeline system (4) is used to introduce high-temperature condensed water from the last-effect forced evaporator (1) into a hot water tank (2) at least 3 meters below the liquid surface for mixing and temperature raising. The last-effect forced evaporator (1) is a last-effect forced evaporator of two groups of multiple-effect evaporators, and the hot water tank (2) is a washing water heating tank for filter cakes filtered by aluminum hydroxide.

2. The method for eliminating the use of fresh steam in a hot water tank for alumina production according to claim 1, characterized in that: The method further comprises the following steps: using a second pipeline to introduce the exhaust gas discharged from the thermoelectric deaerator (3) into the hot water tank (2) at least 3.5 meters below the liquid surface for mixing and temperature raising.

3. The method for eliminating the use of fresh steam in a hot water tank for aluminum oxide production according to claim 1, characterized in that: The pipe system is vertically inserted into the hot water tank below the liquid surface in a multi-point manner and is arranged at different heights below the liquid surface.

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