CN209308753U - A low-temperature flue gas cogeneration system for alumina process roasting - Google Patents

Abstract

The utility model proposes a low-temperature flue gas cogeneration system for alumina process roasting, which includes a power generation sub-system and a reheating sub-system. The smoke inlet of the primary heat exchanger is connected with the smoke exhaust port of the flue gas main pipe of the roaster, and the working fluid in the power generation subsystem is a low-boiling organic substance; the reheating subsystem includes a A secondary heat exchanger connected to the smoke outlet, the internal network water outlet of the secondary heat exchanger is connected to the hot side water inlet of the intermediate heat exchanger, and the cold side water outlet of the intermediate heat exchanger is connected to the secondary heat exchanger The inner network water inlet of the heat exchanger, the cold side water inlet of the intermediate heat exchanger is connected to the water outlet of the red mud washing water circulation system, and the hot side water outlet of the intermediate heat exchanger is connected to the water inlet of the red mud washing water circulation system . The utility model has a reasonable design and can make full use of the waste heat of the low-temperature flue gas in the alumina roasting furnace to increase the economic benefits of the enterprise.

Description

A low-temperature flue gas cogeneration system for alumina process roasting

technical field

The utility model relates to the technical field of industrial flue gas recovery and utilization, in particular to a low-temperature flue gas cogeneration system for alumina process roasting.

Background technique

Aluminum has the advantages of light weight, non-corrosion, electrical conductivity, and stretchability. It is widely used in aerospace, transportation, and construction equipment. It is the second largest metal material after steel. The alumina roasting process is widely used in the metallurgical industry. In the alumina roasting process, the smoke generated from the roaster is about 150°C, the water content is about 49%, and the dew point temperature is about 80°C. It contains a large amount of latent heat of vaporization. Although There is a large amount of energy consumption and extensive waste heat distribution, but due to the low temperature, it has not been well recycled at present. How to effectively recycle the waste heat of flue gas can not only bring economic benefits to enterprises, but also promote the development of my country's aluminum industry in terms of environmental protection and comprehensive utilization of resources.

Utility model content

The utility model aims to at least solve the technical problems existing in the prior art, and particularly innovatively proposes a low-temperature flue gas cogeneration system for alumina process roasting, so as to recycle the waste heat of low-temperature flue gas in the alumina industry.

In order to achieve the above purpose of the utility model, the utility model provides a low-temperature flue gas cogeneration system for alumina roasting, including a power generation sub-system and a reheating sub-system. A connected primary heat exchanger, the smoke inlet of the primary heat exchanger communicates with the smoke exhaust port of the flue gas main pipe of the roaster, and the primary heat exchanger is used to connect the flue gas discharged from the flue gas main pipe of the roaster with the The internal network water of the primary heat exchanger performs heat exchange, the high temperature water supply port of the primary heat exchanger is connected to the heat source water inlet of the evaporator, and the heat source water outlet of the evaporator is connected to the heat source water inlet of the preheater, so The heat source water outlet of the preheater is connected to the low-temperature return water port of the primary heat exchanger, the working fluid inlet of the preheater is connected to the working fluid outlet of the working fluid pump, and the working fluid outlet of the preheater is connected to the evaporator The working fluid inlet is connected, the working fluid outlet of the evaporator is connected to the working fluid inlet of the generator set, the working fluid outlet of the generator set is connected to the working fluid inlet of the condenser, and the working fluid outlet of the condenser is connected to the working fluid inlet The working fluid inlet of the pump;

The reheating subsystem includes a secondary heat exchanger connected to the smoke outlet of the primary heat exchanger, and the secondary heat exchanger is used to combine the flue gas discharged from the primary heat exchanger with the exhaust gas of the secondary heat exchanger. The internal network water is used for heat exchange, the internal network water outlet of the secondary heat exchanger is connected to the hot side water inlet of the intermediate heat exchanger, and the cold side water outlet of the intermediate heat exchanger is connected to the inner network of the secondary heat exchanger. Net water inlet, the cold side water inlet of the intermediate heat exchanger is connected to the water outlet of the red mud washing water circulation system, the hot side water outlet of the intermediate heat exchanger is connected to the water inlet of the red mud washing water circulation system, and the middle The heat exchanger is used to exchange heat between the internal network water of the secondary heat exchanger and the red mud washing water.

The primary heat exchanger is used to recover the sensible heat of the flue gas in the flue gas main pipe of the roaster to generate hot water, which is used as a heat source to drive the generator set to generate electricity. The working medium pump is used to provide flowing pressure for the working medium. Driven by the pressure of the working medium pump, the working medium passes through the preheater and the evaporator successively, is heated by hot water to form a gaseous working medium, enters the generator set and drives the generator set to do work Power generation, after being discharged by the generator set, it continues to enter the condenser, condenses into a liquid working medium through the condenser, and returns to the working medium pump to continue circulation, so as to complete the power generation of the sensible heat of the flue gas.

The secondary heat exchanger is used to recover the latent heat of the flue gas discharged from the primary heat exchanger to generate hot water. The intermediate heat exchanger is used to transfer the heat of the internal network water in the secondary heat exchanger to the red mud washing water, and the heated red mud washing water is used for subsequent processes, so as to complete the use of flue gas latent heat to continue heating the red mud washing water.

In the above scheme: the internal network water of the primary heat exchanger and the secondary heat exchanger are both alkaline water. Compared with pure water, alkaline water will not cause acid corrosion to equipment due to the absorption of acidic components in flue gas, prolonging the service life of equipment.

In the above solution: the intermediate heat exchanger is a plate heat exchanger. The heat transfer coefficient of the plate heat exchanger is high, and the energy loss in the process of transferring to the red mud washing water is less, so as to reduce energy loss as much as possible and improve the recycling rate.

In the above solution: the generator set is a turbo generator set. Compared with the screw expander, the maximum expansion ratio is relatively large, which can make full use of the heat source and working fluid to generate electricity and increase the power generation.

In the above scheme: the working fluid in the power generation sub-system is a low-boiling organic substance. Its boiling point is enough to be heated by the heat energy of the first-level internal network water to become a gaseous working fluid. That is to say, its boiling point is lower than the temperature of the first-level internal network water.

In summary, due to the adoption of the above technical solution, the beneficial effects of the utility model are: the waste heat of the low-temperature flue gas in the alumina roasting furnace can be fully utilized for two recycling, increasing the economic benefits of the enterprise and protecting the environment; Reasonable, the direct heat exchange method is adopted for the recovery part of the flue gas, which can absorb the latent heat of vaporization in the flue gas to the greatest extent, and the indirect heat exchange method is adopted for the heating part of the red mud washing water, and the intermediate heat exchanger can avoid The meta-aluminic acid in the red mud washing water is in contact with the acidic substances to fully recover heat and avoid scaling.

Description of drawings

Fig. 1 is the schematic diagram of the utility model.

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present utility model, but should not be construed as limiting the present utility model.

As shown in Figure 1, a low-temperature flue gas cogeneration system for alumina process roasting includes a power generation sub-system and a reheating sub-system. The smoke inlet of the primary heat exchanger 2 is connected with the smoke outlet of the flue gas main pipe 1 of the roaster, and the primary heat exchanger 2 is used to connect the flue gas discharged from the flue gas main pipe 1 of the roaster with the exhaust port of the primary heat exchanger 2 The internal network water is used for heat exchange, the high temperature water supply port of the primary heat exchanger 2 is connected to the heat source water inlet of the evaporator 4, the heat source water outlet of the evaporator 4 is connected to the heat source water inlet of the preheater 8, and the heat source outlet of the preheater 8 The water port is connected to the low-temperature return water port of the primary heat exchanger 2, the working medium inlet of the preheater 8 is connected to the working medium outlet of the working medium pump 7, the working medium outlet of the preheater 8 is connected to the working medium inlet of the evaporator 4, and the evaporation The working medium outlet of the condenser 4 is connected to the working medium inlet of the generator set 5, the working medium outlet of the generator set 5 is connected to the working medium inlet of the condenser 6, and the working medium outlet of the condenser 6 is connected to the working medium inlet of the working medium pump 7 , the working fluid in the power generation subsystem is a low-boiling organic compound;

The reheating subsystem includes a secondary heat exchanger 3 connected to the smoke outlet of the primary heat exchanger 2, the secondary heat exchanger 3 is provided with internal network water, and the internal network water outlet of the secondary heat exchanger 3 Connect the hot side water inlet of the intermediate heat exchanger 9, the intermediate heat exchanger 9 is a water-water heat exchanger, the cold side water outlet of the intermediate heat exchanger 9 is connected to the internal network water inlet of the secondary heat exchanger 3, and the middle The water inlet on the cold side of the heat exchanger 9 is connected to the water outlet of the red mud washing circulation system, the water outlet on the hot side of the intermediate heat exchanger 9 is connected to the water inlet of the red mud washing circulation system, and the intermediate heat exchanger 9 is used to convert the secondary The flue gas discharged from the heat exchanger 3 exchanges heat with the red mud washing water.

In order to prolong the service life of the equipment, the internal network water of the primary heat exchanger 2 and the secondary heat exchanger 3 is alkaline water. cause acid corrosion.

In order to improve the recycling rate, the intermediate heat exchanger 9 adopts a plate heat exchanger. The heat transfer coefficient of the plate heat exchanger is high, and the energy loss in the process of transferring to the red mud washing water is small, so as to reduce energy loss as much as possible.

In order to increase the power generation, the generator set 5 is a turbo generator set, which can make full use of heat sources and working fluids to generate electricity, and the efficiency can reach more than 80%, which is stable and efficient for a long time.

The flue gas at about 150°C discharged through the flue gas main pipe 1 of the roaster enters the primary heat exchanger 2 to recover sensible heat, heats the internal network water of the primary heat exchanger 2 to 80°C-120°C, and the working fluid pump 7 drives the working fluid Enter the preheater 8 and the evaporator 4 in turn. After entering the preheater 8, the working fluid is preheated in the preheater 8 through the internal network water of the primary heat exchanger 2, and then is exchanged by the primary heat in the evaporator 4. The water in the internal network of the device 1 is heated and forms steam, which enters the generator set 5 and drives the generator set 5 to generate power. After being discharged from the generator set 5, it enters the condenser 6 to condense to form a liquid working medium, and returns to the working medium pump 7 to continue circulation, so as to complete the power generation by utilizing the sensible heat of the flue gas.

After the flue gas absorbs heat through the primary heat exchanger 2, the temperature drops to about 100°C, and then enters the secondary heat exchanger 3 for secondary use. The secondary heat exchanger 3 absorbs the latent heat in the flue gas to heat the internal network water in the secondary heat exchanger 3 and lower the temperature of the flue gas to about 75°C before discharging. Through the intermediate heat exchanger 9, heat is exchanged between the internal network water in the secondary heat exchanger 3 and the red mud washing water, and the heated red mud washing water is used for the subsequent process, so that the red mud washing water can be completed by using the latent heat of the flue gas. Heating of mud washing water.

The economic benefits produced take the alumina process production line with an annual output of 2 million tons as an example. The generator assembly capacity is 1800kW, the annual power generation capacity is 13 million kW·h, and the washing water of 1500t/h red mud or 3000t/h total fraction mother liquor is heated to 70℃ , with an annual heat supply of 1.8 million GJ, an annual saving of 65,000 tons of standard coal, and a reduction of 162,000 tons of carbon dioxide emissions.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications, substitutions and modifications, the scope of the present invention is defined by the claims and their equivalents.

Claims (5)

1. a kind of alumina technology roasts low-temperature flue gas co-generation unit, it is characterised in that: add including power generation sub-system and again Thermal sub-system, the power generation sub-system include the first-class heat exchanger (2) being connected to baking furnace fume general pipeline (1), and the level-one is changed The smoke inlet of hot device (2) is connected to the smoke outlet of baking furnace fume general pipeline (1), and the first-class heat exchanger (2) is used for roaster The flue gas of flue gas general pipeline (1) discharge and the Intranet water of first-class heat exchanger (2) exchange heat, the high temperature of the first-class heat exchanger (2) Feed water inlet is connected to the heat source water inlet of evaporator (4), the heat source of heat source water outlet connection preheater (8) of the evaporator (4) Water inlet, the low-temperature return water mouth of heat source water outlet connection first-class heat exchanger (2) of the preheater (8), the preheater (8) The sender property outlet of working medium inlet communication working medium pump (7), the sender property outlet of the preheater (8) and the working medium import of evaporator (4) It is connected, the sender property outlet of the evaporator (4) is communicated to the working medium import of generating set (5), the working medium of the generating set (5) Outlet is connected to the working medium import of condenser (6), the sender property outlet of the condenser (6) be connected to the working medium of working medium pump (7) into Mouthful；

The reheating subsystem includes the secondary heat exchanger (3) connecting with the outlet flue of first-class heat exchanger (2), and the second level is changed Hot device (3) is for exchanging heat the Intranet water of flue gas and secondary heat exchanger (3) that first-class heat exchanger (2) are discharged, the second level The hot side water inlet of Intranet water water outlet connection Intermediate Heat Exchanger (9) of heat exchanger (3), the cold side of the Intermediate Heat Exchanger (9) Water outlet connects the Intranet water water inlet of secondary heat exchanger (3), and the cold side water inlet connection red mud of the Intermediate Heat Exchanger (9) is washed The water outlet of water circulation system, the water inlet of the hot side water outlet connection red mud wash water circulatory system of the Intermediate Heat Exchanger (9), The Intermediate Heat Exchanger (9) is for exchanging heat the Intranet water of secondary heat exchanger (3) and red mud wash water.

2. a kind of alumina technology according to claim 1 roasts low-temperature flue gas co-generation unit, it is characterised in that: institute The Intranet water for stating first-class heat exchanger (2) and secondary heat exchanger (3) is alkaline water.

3. a kind of alumina technology according to claim 2 roasts low-temperature flue gas co-generation unit, it is characterised in that: institute Stating Intermediate Heat Exchanger (9) is plate heat exchanger.

4. a kind of alumina technology according to claim 1 roasts low-temperature flue gas co-generation unit, it is characterised in that: institute Stating generating set (5) is turbine power generation unit.

5. a kind of alumina technology according to claim 1 roasts low-temperature flue gas co-generation unit, it is characterised in that: institute Stating the working medium in power generation sub-system is low-boiling-point organic compound.