Method and system for co-producing hydrogen and white carbon black by using silicon wafer cutting sewage

Abstract

The invention provides a method and a system for co-producing hydrogen and white carbon black by using silicon wafer cutting sewage, and relates to the technical field of industrial sewage recycling. The system provided by the invention comprises a sewage sedimentation unit arranged at a silicon wafer cutting unit, wherein the sewage sedimentation unit is used for accommodating silicon wafer cutting sewage and carrying out standing sedimentation; the sewage separation unit is used for conveying subnatant after standing and settling to the hydrolysis hydrogen production unit; the hydrolysis hydrogen production unit is used for performing hydrolysis hydrogen production on the subnatant input by the sewage separation unit; the purification hydrogen storage unit is used for washing, purifying and storing the hydrogen generated by the hydrolysis hydrogen production unit; and the white carbon black preparation unit is used for collecting the hydrogen production wastewater generated by the hydrolysis hydrogen production unit and carrying out filter pressing and drying after reaction to obtain the white carbon black. According to the method, the silicon wafer cutting sewage can be used for joint production of green hydrogen, the generated secondary wastewater is recycled to generate white carbon black, the economic benefit of silicon wafer cutting production is effectively improved, and meanwhile, the environmental load is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial wastewater recycling and utilization, and in particular to a method and system for co-producing hydrogen and white carbon black by utilizing silicon wafer cutting wastewater. Background Art

[0002] The modern photovoltaic industry produces a large amount of silicon wafer wire sawing during production. This wastewater is washed down by the cutting cooling water into a wastewater pool, where it collects as silicon wafer sawing wastewater. Currently, the most common treatment method is to filter the wastewater to form silicon powder filter blocks and filter tailwater, which are then treated or recycled separately. However, this process carries significant additional costs, such as energy consumption. Furthermore, recycling the silicon powder filter blocks requires secondary crushing and water addition, further wasting energy and water resources. Therefore, a solution is urgently needed to address this issue. Summary of the Invention

[0003] The purpose of the present invention is to provide a method and system for co-producing hydrogen and white carbon black using silicon wafer cutting wastewater, which can utilize silicon wafer cutting wastewater to co-produce green hydrogen and recycle the generated secondary wastewater to produce white carbon black, effectively improving the economic benefits of silicon wafer cutting production and reducing its environmental load.

[0004] The present invention provides a system for co-producing hydrogen and white carbon black using silicon wafer cutting wastewater, comprising: a wastewater sedimentation unit arranged at a silicon wafer cutting unit, the wastewater sedimentation unit being used to accommodate silicon wafer cutting wastewater and perform static sedimentation; a wastewater separation unit being used to transport the upper layer liquid of the silicon wafer cutting wastewater after static sedimentation to a water recovery tank, and to transport the lower layer liquid to a hydrolysis hydrogen production unit; a hydrolysis hydrogen production unit being used to hydrolyze the lower layer liquid input from the wastewater separation unit to produce hydrogen; a purified hydrogen storage unit being used to wash, purify and store the hydrogen produced by the hydrolysis hydrogen production unit; and a white carbon black preparation unit being used to collect the hydrogen production wastewater produced by the hydrolysis hydrogen production unit and, after reaction, filter press and dry the wastewater to obtain white carbon black.

[0005] The system provided by the present invention requires continuous cooling water to flush and cool the cutting wire saw and silicon wafers during the operation of the silicon wafer cutting unit, and then a large amount of wire saw silicon chips and powder are flushed down with the cooling water and collected in the sewage sedimentation unit. After the sewage mixed with silicon powder naturally settles in the sewage sedimentation unit, the upper layer liquid with less silicon powder content is transported to the water recovery tank for recycling and treatment through the sewage separation unit, and the lower layer liquid with more silicon powder content is transported to the hydrolysis hydrogen production unit, and the silicon powder is hydrolyzed to produce hydrogen by the hydrolysis hydrogen production unit, and the generated hydrogen is washed, purified and stored by the purification hydrogen storage unit. In addition, the white carbon black preparation unit collects the secondary hydrogen production wastewater generated by the hydrolysis hydrogen production unit, and produces white carbon black through reaction and post-treatment.

[0006] Optionally, the sewage sedimentation unit includes a plurality of connected sewage sedimentation tanks each for accommodating and sedimenting the silicon wafer cutting sewage, and the sewage separation unit performs circulation treatment on the plurality of sewage sedimentation tanks.

[0007] Optionally, the silicon wafer cutting wastewater is allowed to settle in the wastewater sedimentation tank for 30 minutes to 180 minutes.

[0008] Optionally, the hydrolysis hydrogen production unit includes: a reaction hydrogen production module, used to accommodate the hydrolyzed liquid and the lower layer liquid for hydrolysis hydrogen production reaction; a solution adding module, used to add the hydrolyzed liquid into the reaction hydrogen production module; and a waste liquid discharge module, used to transport the hydrogen production wastewater after the hydrolysis hydrogen production reaction in the reaction hydrogen production module to the white carbon black preparation unit.

[0009] Optionally, the hydrolysis solution includes a comprehensive catalyst with a mass concentration of 0.5%-10%, the comprehensive catalyst includes a silicon powder detergent with a mass fraction of 5%-15%, and a hydrolysis catalyst of 85%-95%, the silicon powder detergent includes citric acid, hexadecyltrimethoxysilane, and one of EO / PO block polyether modified siloxane, and the hydrolysis catalyst includes one of calcium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, calcium oxide and sodium ethoxide.

[0010] Optionally, the purified hydrogen storage unit includes: a washing and purification module for washing and purifying the hydrogen produced by the hydrolysis hydrogen production unit; a hydrogen storage module for storing the washed and purified hydrogen; preferably, the hydrogen storage module includes a high-pressure hydrogen storage container.

[0011] Optionally, the washing and purification module includes: a labyrinth condensation column for condensing and recovering water vapor in the gas generated by the hydrolysis hydrogen production unit; a circulating cooling water supplier for heat exchange of the labyrinth condensation column; and a direct washing and purification column for purifying and washing the gas output by the labyrinth condensation column.

[0012] Optionally, the silica preparation unit includes: a plurality of reaction precipitation modules connected together and each used to accommodate the reaction of hydrogen production wastewater and an auxiliary agent; an auxiliary agent replenishing module, used to add an auxiliary agent to the reaction precipitation module, the auxiliary agent including a gas containing 0.01%-100% carbon dioxide; a filter pressing and drying module, which filters and dries the precipitate produced in the reaction precipitation module to obtain silica, preferably, after filtration, the precipitate is crushed and dried to a water content of 25%-40% and then dried.

[0013] In a second aspect, the present invention also provides a method for co-producing hydrogen and white carbon black using silicon wafer cutting wastewater, comprising: collecting silicon wafer cutting wastewater during silicon wafer cutting production and allowing it to settle, separating the upper layer of liquid for water recovery treatment and separating the lower layer of liquid for hydrolysis to produce hydrogen, washing and purifying the gas produced by hydrolysis to produce hydrogen and storing high-purity hydrogen, reacting the hydrogen production wastewater produced by hydrolysis to produce hydrogen and filtering and drying it to obtain white carbon black. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the system structure for co-producing hydrogen and white carbon black using silicon wafer cutting wastewater provided by the present invention.

[0015] Explanation of the accompanying symbols: 1. Sewage sedimentation unit; 2. Sewage separation unit; 3. Water recovery tank; 4. Hydrolysis hydrogen production unit; 5. Purification hydrogen storage unit; 6. Silica preparation unit. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with ordinary skills in the field to which the present invention belongs.

[0017] See also Figure 1 The present invention provides a system for co-producing hydrogen and white carbon black using silicon wafer cutting wastewater, comprising: a wastewater sedimentation unit arranged at a silicon wafer cutting unit, the wastewater sedimentation unit being used to accommodate silicon wafer cutting wastewater and perform static sedimentation; a wastewater separation unit being used to transport the upper layer liquid of the silicon wafer cutting wastewater after static sedimentation to a water recovery tank, and to transport the lower layer liquid to a hydrolysis hydrogen production unit; a hydrolysis hydrogen production unit being used to hydrolyze the lower layer liquid input from the wastewater separation unit to produce hydrogen; a purified hydrogen storage unit being used to wash, purify and store the hydrogen produced by the hydrolysis hydrogen production unit; and a white carbon black preparation unit being used to collect the hydrogen production wastewater produced by the hydrolysis hydrogen production unit and to obtain white carbon black by filter pressing and drying after reaction.

[0018] In fact, during the operation of the silicon wafer cutting unit, cooling water is continuously used to flush and cool the wire saw and silicon wafers, and a large amount of wire saw silicon powder is flushed into the wastewater sedimentation unit along with the cooling water. Specifically, the silicon wafer cutting unit can be formed by one or more cutting machines in a group, and the wastewater sedimentation unit can simultaneously face all the cutting machines in the silicon wafer cutting unit to collect silicon-containing wastewater. In some embodiments,

[0019] In practice, the wastewater settling unit comprises multiple connected wastewater settling tanks, each used to receive and settle silicon wafer cutting wastewater. Specifically, during operation, the wastewater separation unit circulates treatment throughout the multiple settling tanks, enabling the continuous co-production of hydrogen and silica. Furthermore, the capacity of each settling tank must be sufficient to continuously inject silicon wafer cutting wastewater for 4-6 hours.

[0020] In some embodiments, when the silicon wafer cutting wastewater is settled in the wastewater sedimentation tank, the static sedimentation time is controlled to be 30 minutes to 180 minutes, so that the silicon powder in the silicon wafer cutting wastewater can be fully settled, which is beneficial for the wastewater separation unit to separately treat the upper layer liquid and the lower layer liquid.

[0021] In fact, the hydrolysis hydrogen production unit includes a reaction hydrogen production module, which is used to accommodate the hydrolyzed liquid and the lower layer liquid for hydrolysis hydrogen production reaction; a solution adding module, which is used to add the hydrolyzed liquid into the reaction hydrogen production module; and a waste liquid discharge module, which is used to transport the hydrogen production wastewater after the hydrolysis hydrogen production reaction in the reaction hydrogen production module to the white carbon black preparation unit.

[0022] In some embodiments, the hydrolysis solution includes a comprehensive catalyst with a mass concentration of 0.5%-10%, the comprehensive catalyst includes a silicon powder detergent with a mass fraction of 5%-15%, and a hydrolysis catalyst of 85%-95%. The silicon powder detergent includes citric acid, hexadecyltrimethoxysilane, and one of EO / PO block polyether modified siloxane. The hydrolysis catalyst includes one of calcium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, calcium oxide, and sodium ethoxide.

[0023] In fact, the purified hydrogen storage unit includes: a washing and purification module for washing and purifying the hydrogen produced by the hydrolysis hydrogen production unit; a hydrogen storage module for storing the washed and purified hydrogen; preferably, the hydrogen storage module includes a high-pressure hydrogen storage container.

[0024] In some embodiments, the washing and purification module includes: a labyrinth condensation column for condensing and recovering water vapor in the gas generated by the hydrolysis hydrogen production unit; a circulating cooling water supplier for heat exchange of the labyrinth condensation column; and a direct washing and purification column for purifying and washing the gas output by the labyrinth condensation column.

[0025] In fact, the silica preparation unit includes: a plurality of reaction precipitation modules connected together and each used to accommodate the reaction of hydrogen production wastewater and auxiliary agents; an auxiliary agent replenishing module, used to add auxiliary agents to the reaction precipitation module, and the auxiliary agents include a gas containing 0.01%-100% carbon dioxide; a filter pressing and drying module, which filters and dries the precipitate produced in the reaction precipitation module to obtain silica. Preferably, after the filtration, the precipitate is crushed and dried to a water content of 25%-40% and then dried.

[0026] The present invention also provides a method for co-producing hydrogen and white carbon black using silicon wafer cutting wastewater, comprising: collecting silicon wafer cutting wastewater during silicon wafer cutting production and allowing it to settle, separating the upper layer liquid for water recovery treatment and separating the lower layer liquid for hydrolysis to produce hydrogen, washing and purifying the gas produced by the hydrolysis to produce hydrogen and storing high-purity hydrogen, reacting the hydrogen production wastewater produced by the hydrolysis to produce hydrogen and filtering and drying it to obtain white carbon black.

[0027] Example 1

[0028] This embodiment 1 provides a method for co-producing hydrogen and white carbon black using silicon wafer cutting wastewater, comprising: stirring 20 kg of a wastewater sample evenly and then allowing it to settle for 50 minutes, extracting approximately 3 kg of relatively clear water from the top of a sedimentation tank with a micro water pump, and then injecting the remaining wastewater into a reactor. 170 g of a comprehensive catalyst for hydrogen production from hydrolysis of silicon wafer cutting wastewater is then added to the reactor, allowing the hydrolysis hydrogen production reaction to proceed spontaneously, and the generated hydrogen is discharged and measured through a mass flow meter; after the gas production flow rate gradually decreases to a negligible level (after about 1.5 hours), the reactor is opened, the hydrogen production waste liquid is poured into a plastic tank, carbon dioxide is introduced into the bottom of the tank at a flow rate of 0.5 L / min while stirring, and unreacted carbon dioxide is naturally discharged by bubbling. After 50 minutes, all the tank liquid is injected into a gravity filter press for filtration. After removing the water, the filter cake is removed, crushed and spread out, air-dried in air for about ten hours, and then dried in an oven at about 100°C.

[0029] Example 2

[0030] This embodiment 2 provides a method for co-producing hydrogen and white carbon black using silicon wafer cutting wastewater, comprising: stirring 20 kg of a wastewater sample evenly and then allowing it to settle for 50 minutes, extracting 3 kg of relatively clear water from the top of a sedimentation tank with a micro water pump, and then injecting the remaining wastewater into a reactor. Then, 170 g of a comprehensive catalyst for hydrolyzing and producing hydrogen from silicon wafer cutting wastewater is added to the reactor, allowing the hydrolysis and hydrogen production reaction to proceed spontaneously, and the generated hydrogen is discharged and measured through a mass flow meter; after the gas production flow rate gradually decreases to a negligible level (after about 1 hour), the reactor is opened, the hydrogen production waste liquid is poured into a plastic tank, and compressed air is introduced into the bottom of the tank through six evenly distributed air vents at a total flow rate of 20 L / min, and unreacted air is naturally discharged by bubbling. After 100 minutes, all the tank liquid is injected into a gravity filter press for filtration. After removing the water, the filter cake is removed, crushed and spread out, air-dried in air for about ten hours, and then dried in an oven at about 100°C.

[0031] Example 3

[0032] This embodiment 3 provides a method for co-producing hydrogen and white carbon black using silicon wafer cutting wastewater, comprising: stirring 20 kg of a wastewater sample evenly and then allowing it to settle for 50 minutes, extracting 3 kg of relatively clear water from the top of a sedimentation tank with a micro water pump, and then injecting the remaining wastewater into a reactor. Then, 170 g of a comprehensive catalyst for hydrogen production by hydrolysis of silicon wafer cutting wastewater is added to the reactor, allowing the hydrolysis hydrogen production reaction to proceed spontaneously, and the generated hydrogen is discharged and measured through a mass flow meter; after the gas production flow rate gradually decreases to a negligible level (after about 40 minutes), the reactor is opened, the hydrogen production waste liquid is poured into a plastic tank, and compressed air is introduced into the bottom of the tank through six evenly distributed air vents at a total flow rate of 20 L / min, and unreacted air is naturally discharged by bubbling. After 100 minutes, all the tank liquid is injected into a gravity filter press for filtration. After removing the water, the filter cake is removed, crushed and spread out, air-dried in air for about ten hours, and then dried in an oven at about 100°C.

[0033] The green hydrogen production, white carbon black production and particle size in Examples 1 to 3 are shown in Table 1 below.

[0034] Table 1

[0035]

[0036]

[0037] While the embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations of these embodiments are possible. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as set forth in the claims. Furthermore, the invention described herein is susceptible to other embodiments and may be practiced or implemented in a variety of ways.

Claims

1. A system for co-producing hydrogen and white carbon black using silicon wafer cutting wastewater, characterized in that: include: A sewage sedimentation unit is provided at the silicon wafer cutting unit, and is used to accommodate silicon wafer cutting sewage and perform static sedimentation; The sewage separation unit is used to transport the upper layer of silicon wafer cutting sewage after static sedimentation to the water recovery tank, and transport the lower layer of sewage to the hydrolysis hydrogen production unit; the hydrolysis hydrogen production unit is used to hydrolyze the lower layer of sewage input from the sewage separation unit to produce hydrogen; The purification and storage hydrogen unit is used to wash, purify and store the hydrogen produced by the hydrolysis hydrogen production unit; the white carbon black preparation unit is used to collect the hydrogen production wastewater produced by the hydrolysis hydrogen production unit and filter and dry it after reaction to obtain white carbon black.

2. The system according to claim 1, wherein: The sewage sedimentation unit includes a plurality of connected sewage sedimentation tanks each for accommodating and sedimenting the silicon wafer cutting sewage. The sewage separation unit performs circulation treatment on the plurality of sewage sedimentation tanks. Preferably, the silicon wafer cutting sewage is allowed to settle in the sewage sedimentation tank for 30 minutes to 180 minutes.

3. The system according to claim 1, wherein: The hydrolysis hydrogen production unit includes: a reaction hydrogen production module, which is used to accommodate hydrolyzed liquid and lower layer liquid for hydrolysis hydrogen production reaction; a solution adding module, which is used to add hydrolyzed liquid into the reaction hydrogen production module; and a waste liquid discharge module, which is used to transport the hydrogen production wastewater after the hydrolysis hydrogen production reaction in the reaction hydrogen production module to the white carbon black preparation unit.

4. The system according to claim 3, characterized in that The hydrolysis solution includes a comprehensive catalyst with a mass concentration of 0.5%-10%, the comprehensive catalyst includes a silicon powder detergent with a mass fraction of 5%-15% and a hydrolysis catalyst with a mass fraction of 85%-95%, the silicon powder detergent includes one of citric acid, hexadecyltrimethoxysilane, and EO / PO block polyether modified siloxane, and the hydrolysis catalyst includes one of calcium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, calcium oxide, and sodium ethoxide.

5. The system according to claim 1, wherein: The purified hydrogen storage unit includes: a washing and purification module for washing and purifying the hydrogen produced by the hydrolysis hydrogen production unit; a hydrogen storage module for storing the washed and purified hydrogen; preferably, the hydrogen storage module includes a high-pressure hydrogen storage container.

6. The system according to claim 5, characterized in that The washing and purification module includes: a labyrinth condensation column for condensing and recovering water vapor in the gas generated by the hydrolysis hydrogen production unit; a circulating cooling water supplier for exchanging heat for the labyrinth condensation column; and a direct washing and purification column for purifying and washing the gas output by the labyrinth condensation column.

7. The system according to claim 1, wherein: The white carbon black preparation unit includes: a plurality of reaction precipitation modules connected together and each used to accommodate the reaction of hydrogen production wastewater and an auxiliary agent; an auxiliary agent replenishing module, used to add an auxiliary agent to the reaction precipitation module, wherein the auxiliary agent includes a gas containing 0.01%-100% carbon dioxide; a filter pressing and drying module, which filters and dries the precipitate generated in the reaction precipitation module to obtain white carbon black, preferably, after the filter pressing, the precipitate is crushed and dried to a water content of 25%-40% and then dried.

8. A method for co-producing hydrogen and white carbon black by using silicon wafer cutting wastewater, characterized in that: include: During silicon wafer cutting production, silicon wafer cutting wastewater is collected and allowed to settle, the upper liquid is separated for water recovery treatment, and the lower liquid is separated for hydrolysis to produce hydrogen. The gas produced by hydrolysis is washed and purified, and high-purity hydrogen is stored. The hydrogen production wastewater produced by hydrolysis is reacted and filtered and dried to obtain white carbon black.

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