CN106731890B

CN106731890B - Inorganic film for capturing water vapor in flue gas of thermal power plant and preparation method

Info

Publication number: CN106731890B
Application number: CN201611214188.5A
Authority: CN
Inventors: 陈海平; 宋涛; 叶超
Original assignee: North China Electric Power University
Current assignee: North China Electric Power University
Priority date: 2016-12-26
Filing date: 2016-12-26
Publication date: 2023-08-18
Anticipated expiration: 2036-12-26
Also published as: CN106731890A

Abstract

The invention discloses an inorganic ceramic membrane for capturing water vapor in flue gas of a thermal power plant and a preparation method thereof, wherein the method comprises the following steps: 1. preparing aluminum-based sol, preparing water and aluminum in proper proportion, adding nitric acid as a catalyst, and ensuring the pH of the solution to be about 4.3. 2. The pretreatment of the alumina ceramic matrix membrane comprises respectively carrying out ultrasonic cleaning on distilled water, deionized water, anhydrous acetone, isopropanol and ethanol for 10min, and drying in a constant temperature drying oven at 100 ℃. 3. And (3) depositing the aluminum-based sol diluted by 10 times on one side of the alumina ceramic pores by adopting a suction filtration method, and drying at room temperature. 4. And (3) performing a dip coating method, coating the ceramic membrane for 10s, drying in a constant-temperature drying oven at room temperature and 60 ℃ respectively, and sintering at 530 ℃ to obtain the final ceramic separation membrane. 5. The surface morphology is observed under a scanning electron microscope by testing parameters such as average pore diameter, pore volume, porosity and the like on a full-automatic specific surface and pore diameter analyzer. The conclusion that the ceramic membrane has good pore diameter gradient distribution and good mechanical property can completely meet the moisture trapping in the smoke exhaust of the thermal power plant, the water recovery rate can reach more than 20 percent, and a new water-saving direction and an emission reduction thought are provided for the passing-through-fire electricity industry.

Description

Inorganic film for capturing water vapor in flue gas of thermal power plant and preparation method

Technical Field

The invention belongs to the technical field of water and energy conservation in the thermal power generation industry, and relates to an asymmetric inorganic ceramic membrane for flue gas dehydration of a thermal power plant and a related preparation method.

Background

The water resource content of 27266.9 hundred million cubic meters in China accounts for 6% of the global water resource, but the water resource of people accounts for one fourth of the water resource of people in the world, and the unbalanced distribution of the water resource makes the electric power development of the China-western rich coal water-deficient area very challenging. The total amount of power generation from 2005 to 2014 is doubled, wherein the thermal power ratio is slightly reduced in recent years but stabilized above 73%. Therefore, in the electric power industry of China, thermal power generation mainly using consumed coal is still performed for a long time in the future. Researches show that the water consumption of the thermal power is 40% of the water consumption of the national industry, and the water consumption rate of the national installation is 40% -50% higher than the international advanced level. So water resources are a major contradiction in thermal power generation.

At present, in the smoke components generated when different coal types are used for combustion of thermal power generating units with different capacities in China, the water vapor accounts for 5-15%. The annual smoke displacement of the 1000MW thermal power generating unit adopting lignite can reach 121 ten thousand tons. If 20% of the flue gas water quantity can be recovered, the water supplementing self-sufficiency of the unit can be realized. If the water can be recovered from the flue gas by adopting effective measures, the boiler water supply can be ensured, and the thermal power water consumption can be greatly reduced to become an important part of the thermal power energy-saving field.

The existing method for flue gas water capture research of the thermal power plant mainly comprises a composite membrane and an inorganic membrane, and has the characteristics of simple device, easy control of operation, environmental friendliness and the like, so that the method is widely applied. However, the organic ceramic membrane has poor mechanical properties, short service life and small volume, and certain application is limited. Compared with the inorganic membrane of the composite membrane, the inorganic membrane has excellent chemical, thermodynamic and mechanical stability, can continuously work under extreme conditions, has larger volume, and is suitable for industrial production and application, thereby attracting attention. In 2000, the american gas technology institute was under the grant of the united states department of energy to study the water capturing technology through the nanoporous ceramic membrane and succeeded, and then the preamble of the research of the inorganic ceramic membrane in terms of flue gas dehydration was opened. Many scholars and institutions abroad have also conducted research. The method has the advantages that the method is relatively late in the aspect of researching the dehydration of the flue gas by utilizing the inorganic ceramic membrane in China, the related technology is not very mature, and only scattered researches and reviews are reported. Especially in the process of preparing inorganic films.

The alumina ceramic is the ceramic material which is used for commercial production at the earliest, and the alumina ceramic matrix film has good mechanical property, low cost, excellent chemical stability, mature preparation process, capability of being manufactured into various shapes and convenient application. Therefore, the present subject uses an alumina-based film. Compared with alumina coating such as zirconia, titania and the like, the preparation method is easier, the cost is low, the process is mature, and the method is suitable for mass industrialized production. Thus, aluminum-based sols are used herein for coating.

Disclosure of Invention

In order to recover the moisture in the flue gas of the thermal power plant and save the water of the power plant, the invention provides a preparation method of an inorganic ceramic membrane for capturing the water vapor in the flue gas. The ceramic membrane has simple preparation process and excellent separation performance.

The technical scheme adopted by the invention is as follows: the method of suction filtration coating is adopted, namely, an aluminum-based coating is coated on the surface of the alumina ceramic. The preparation method comprises the following process flows: preparing aluminum-based sol: 1. 75g of analytically pure Al (NO 3) 3.9H2O solid was dissolved in 200mL deionized water. 2. Stirring thoroughly, and standing for 24 hr. 3. Taking analytically pure ammonia water, and preparing 1mol/L ammonia water for standby. 4. Dropwise adding the aluminum nitrate solution into ammonia water to obtain flocculent boehmite. 5. And (3) washing three times by filtering and deionized water, and drying in a constant-temperature incubator to obtain boehmite. 6. 750mL of deionized water was heated to 85℃and 30g of boehmite was added thereto and the mixture was hydrolyzed with stirring for 5 hours. 7. 65mL of 1mol/L nitric acid was added. 8. And (3) carrying out heat preservation for 15 hours in a water bath kettle at 87 ℃ to obtain boehmite sol. 9. Taking 50mL of boehmite sol, adding 500mL of deionized water, and stirring in a water bath kettle at 85 ℃ for 1h to obtain sol diluent; 2. pretreatment of an alumina-based film: 1. a100 mm sample was taken of the alumina ceramic matrix membrane (inner diameter 8mm, outer diameter 12 mm) and left for use. 2. Ultrasonic cleaning with distilled water for 10min. 3. Ultrasonic cleaning with deionized water for 10min. 4. Ultrasonic cleaning with anhydrous acetone for 10min. 5. Ultrasonic cleaning with isopropanol for 10min. 6. Ultrasonic cleaning with ethanol for 10min. 7. Drying in a constant temperature drying oven at 100 ℃ for 1h to obtain an alumina-based film for standby; 3. and (3) preparing a ceramic membrane by a suction filtration method: the invention prepares the asymmetric ceramic membrane by coating the inner surface of the alumina-based membrane. 1. Taking a clean alumina ceramic membrane, adding sol dilute solution into one end of the clean alumina ceramic membrane in a blocking way, connecting the other end of the clean alumina ceramic membrane with a pump 2, and pressurizing the dilute solution by the pump to enable the dilute solution to pass through the ceramic base membrane. 3. The above operation was repeated three times. 4. Drying at room temperature for 48h. 4. Preparation of ceramic membranes by dip coating: 1. and injecting boehmite sol into the dried alumina ceramic by adopting a dip coating method, standing for 10 seconds, and drying at room temperature for 48 hours. 2. Drying in a constant temperature drying oven at 80 ℃ for 4 hours. 3. Heating to 530 ℃ at a heating rate of 1 ℃/min, preserving heat for 3 hours, and cooling along with a furnace to obtain an asymmetric ceramic membrane; 5. and (3) carrying out full-automatic specific surface and aperture analysis and scanning electron microscope analysis on the ceramic membrane obtained by the method. The analysis experiment result shows that the ceramic membrane has excellent separation performance and is very suitable for flue gas dehydration of a thermal power plant.

The beneficial effects of the invention are as follows: the alumina asymmetric ceramic membrane has good mechanical and mechanical properties, good structural stability, acid resistance, alkali resistance and thermal shock resistance. The method is suitable for various flue gas working conditions at the tail part of the boiler furnace of the coal-fired power plant, and has obvious separation effect and longer service life. The pore diameter change gradient of the separation membrane prepared by the pressure suction filtration is gentle, kong Ronggeng is small, the defect rate of the macropores is lower, and the separation performance is better. The average pore diameter is about 9nm through a full-automatic specific surface pore diameter testing instrument, the adsorption quantity of nitrogen is low, and the adsorption quantity of water vapor is high due to surface diffusion and capillary condensation. When the ceramic membrane is applied to a simulated flue gas experiment, water with higher quality can be recovered by changing the temperature and pressure conditions of the gas collecting side, and under certain conditions, the water recovery rate can reach 0.5 Kg/(m) ² H), the water recovery rate reaches 20-30%. The asymmetric porous ceramic membrane for capturing water in flue gas of a thermal power plant can effectively capture water in the flue gas, and provides a new water-saving direction and an emission reduction thought for the passing-through-fire electricity industry.

Claims

1. The preparation method of the inorganic ceramic membrane for capturing water vapor in the flue gas of the thermal power plant is characterized by comprising the following steps of: 1. preparing aluminum-based sol: 1. analytically pure Al (NO) ₃ ) ₃ •9H ₂ 75g of O solid, dissolved in 200mL of deionized water; 2. fully stirring, and standing for 24 hours for use; 3. preparing 1mol/L ammonia water from analytically pure ammonia water for standby; 4. dropwise adding an aluminum nitrate solution into ammonia water to obtain flocculent boehmite; 5. filtering the flocculent boehmite, washing the flocculent boehmite with deionized water for three times, and drying the flocculent boehmite in a constant-temperature incubator to obtain boehmite; 6. heating 750mL of deionized water to 85 ℃, adding 30g of boehmite, and stirring for hydrolysis for 5h; 7. 65mL of nitric acid with the concentration of 1mol/L is added; 8. heat-insulating for 15h in a water bath kettle at 87 ℃ to obtain boehmite sol; 9. taking 50mL of boehmite sol, adding 500mL of deionized water, and stirring in a water bath kettle at 85 ℃ for 1h to obtain sol diluent; 2. pretreatment of an alumina ceramic base film: 1. taking an alumina ceramic matrix membrane with an inner diameter of 8mm and an outer diameter of 12mmIntercepting a 100mm sample for standby; 2. ultrasonically cleaning with distilled water for 10min; 3. ultrasonically cleaning with deionized water for 10min; 4. ultrasonically cleaning with anhydrous acetone for 10min; 5. ultrasonically cleaning with isopropanol for 10min; 6. ultrasonic cleaning with ethanol for 10min; 7. drying in a constant-temperature drying oven at 100 ℃ for 1h to obtain an alumina ceramic matrix membrane for standby; 3. preparing an alumina ceramic membrane by a suction filtration method: 1. taking a clean alumina ceramic base membrane, wherein one end of the alumina ceramic base membrane is blocked, and the other end of the alumina ceramic base membrane is connected with a pump; 2. pumping the sol dilute solution into the alumina ceramic base membrane by a pump and pressurizing to enable the dilute solution to pass through the ceramic base membrane; 3. repeating operation 2 three times; 4. drying at room temperature for 48 hours; 4. preparation of ceramic membranes by dip coating: 1. injecting boehmite sol into the dried alumina ceramic membrane by adopting a dip coating method, standing for 10 seconds, and drying at room temperature for 48 hours; 2. drying in a constant temperature drying oven at 80 ℃ for 4 hours; 3. heating to 530 ℃ at a heating rate of 1 ℃/min, preserving heat for 3 hours, and cooling along with the furnace to obtain the asymmetric ceramic membrane.

2. The method for preparing the inorganic ceramic membrane for capturing water vapor in flue gas of a thermal power plant according to claim 1 is characterized in that sol diluted 10 times is subjected to suction filtration and deposited in gaps of the ceramic membrane to obtain uniformly gradient-distributed pore diameters, and then a coating film is formed by dipping the coating film to obtain the separation membrane.