Chemical-biological coupling fixing system for carbon dioxide in flue gas

Abstract

The utility model discloses a technology for immobilizing carbon dioxide by microorganisms, and particularly relates to a technology for treating and purifying carbon dioxide in hazardous waste incineration waste gas by utilizing a photobioreactor, and the concentration of finally discharged carbon dioxide is close to that of carbon dioxide in the atmosphere. The flue gas treatment amount of the process system is 100m < 3 > / h, and the main process flow of the treatment is as follows: flue gas passes through a condensing heat exchanger, a spray tower, a chemical regulating tank, a photobioreactor and discharge (gas) / recovery (biomass); wherein a spraying agent in the spraying tower is potassium carbonate which reacts with carbon dioxide in the flue gas to generate a potassium bicarbonate solution, and the potassium bicarbonate solution is collected into the chemical adjusting tank and finally flows into the photobioreactor to serve as a supplementary carbon source; algae liquid discharged by the photobioreactor is collected and then subjected to filter pressing treatment, filtrate is circulated to a spray tower water collecting tank and used for preparing spray liquid, and water circulation of the whole system is achieved.

Description

Technical Field

[0001] The utility model relates to the field of microbial fixation of carbon dioxide, specifically a chemical-biological coupling fixation system for carbon dioxide in flue gas. The system is based on microbial fixation of carbon dioxide technology and utilizes a photobioreactor to treat and purify carbon dioxide in hazardous waste incineration waste gas, ultimately discharging carbon dioxide at a concentration close to that in the atmosphere. Background Art

[0002] Microalgae are tiny yet extremely important organisms, commonly found in aquatic and wetland environments, and are an integral part of ecosystems. Microalgae are diverse in morphology, classification, growth conditions, and bioactive substances. Microalgae have a short growth cycle, with some completing a cycle in just a few hours. Furthermore, microalgae are rich in nutrients such as protein, fat, and carbohydrates, as well as bioactive substances such as antioxidants and polysaccharides, offering a wide range of applications. Microalgae can also fix carbon dioxide and convert it into organic matter while releasing oxygen, making them a key carbon dioxide fixer in ecosystems.

[0003] Currently, microalgae cultivation systems for carbon dioxide fixation can be divided into two types: outdoor open-raceway systems and closed photobioreactor systems, depending on whether the system is airtight or not. The open-raceway system is the simplest microalgae cultivation system, offering advantages such as low energy demand, low construction costs, and ease of large-scale production. However, outdoor open-race systems are difficult to control in terms of environmental factors such as light intensity, pH, and temperature, have high water evaporation rates, and pose a risk of contamination. To address these limitations of outdoor open-raceway systems, closed photobioreactor systems have been developed. Due to their effective temperature control and sterile environment, closed photobioreactor systems can achieve high carbon dioxide fixation effects, microalgae biomass productivity, and photosynthesis efficiency, while reducing the probability of cross-contamination, making them the preferred system.

[0004] Tubular photobioreactors consist of transparent glass or plastic tubes, through which microalgae culture circulates, completing their own growth and metabolism while also achieving carbon fixation and product accumulation. However, these systems are difficult to scale up, and expansion can only be achieved by multiplying the number of tubular PBRs. Flat-plate photobioreactors, by adjusting the orientation and tilt of the flat-plate PBRs to meet the growth needs of algae cells, offer high light energy utilization and a larger specific surface area than tubular systems. However, they suffer from high energy consumption and require high-quality materials for the flat-plate reactors. Utility Model Content

[0005] This system, based on microalgae carbon dioxide fixation technology and utilizing a photobioreactor, is designed to treat and purify carbon dioxide from industrial boiler flue gases. The final exhaust concentration of carbon dioxide approaches atmospheric carbon dioxide concentration (0.04%). The flue gas entering this process is considered to have undergone dust removal, dehumidification, desulfurization, and denitrification. This process only treats the carbon dioxide in the flue gas.

[0006] In order to achieve the above objectives, this system adopts the following technical solutions:

[0007] The flue gas processing volume of this process system is 100m 3 / h, and the main process flow of the treatment is: flue gas → condensation heat exchanger → spray tower → chemical regulating tank → photobioreactor → emission (gas) / recovery (biomass); the spray agent in the spray tower is potassium carbonate, which reacts with carbon dioxide in the flue gas to generate potassium bicarbonate solution, which is collected in the chemical regulating tank and finally flows into the photobioreactor as a supplementary carbon source; the algae liquid discharged from the photobioreactor is collected and filtered, and the filtrate is circulated to the spray tower collection tank for the preparation of spray liquid, thus realizing the water circulation of the entire system.

[0008] The chemical-biological coupling system for carbon dioxide capture in flue gas includes a clean gas outlet valve, a circulating water outlet valve, a filtrate recovery valve, an algae liquid recovery valve, a carbon dioxide waste gas inlet valve, an aeration plate, a circulating water inlet valve, a nutrient solution inlet valve, a spray tower, a chemical regulating tank, a nutrient solution storage tank, an algae liquid collection tank, a filter press, and a lighting assembly. The clean gas outlet valve is located above the photobioreactor; the filtrate recovery valve is located above the algae liquid recovery valve; the nutrient solution inlet valve is located above the circulating water inlet valve; the carbon dioxide waste gas inlet valve is located at the bottom of the photobioreactor, 680 mm above the ground, and is connected to the spray tower outlet; the algae liquid recovery valve is connected to the algae liquid collection tank; and the nutrient solution inlet valve is connected to the nutrient solution storage tank. The spraying agent in the above-mentioned spray tower is potassium carbonate, which reacts with carbon dioxide in the flue gas to generate potassium bicarbonate solution, which is collected in the chemical regulating tank and eventually flows into the photobioreactor as a supplementary carbon source; the algae liquid discharged from the photobioreactor is collected and then subjected to filter pressure treatment; the carbon dioxide and circulating water of the photobioreactor are both in the bottom-in and top-out method.

[0009] The above chemical-biological coupling fixation system for carbon dioxide in flue gas, the aperture of the aeration plate of the photobioreactor is 0.2mm

[0010] The chemical-biological coupling fixation system for carbon dioxide in flue gas has three support columns at the bottom of the photobioreactor.

[0011] In the chemical-biological coupling fixation system for carbon dioxide in flue gas, the carbon dioxide waste gas inlet valve at the bottom of the photobioreactor is a spherical valve with a diameter of 300 mm.

[0012] In the chemical-biological coupling fixation system for carbon dioxide in flue gas, the clean gas outlet valve of the photobioreactor is a spherical valve with a diameter of 100 mm.

[0013] In the chemical-biological coupling fixation system for carbon dioxide in flue gas, the outflow valve of the circulating water of the photobioreactor is a spherical valve with a diameter of 50 mm.

[0014] In the chemical-biological coupling fixation system for carbon dioxide in flue gas, the nutrient solution inlet valve of the photobioreactor is a spherical valve with a diameter of 50 mm.

[0015] In the chemical-biological coupling fixation system for carbon dioxide in flue gas, the water inlet valve for circulating water in the photobioreactor is a spherical valve with a diameter of 50 mm.

[0016] In the chemical-biological coupling fixation system for carbon dioxide in flue gas, the photobioreactor filtrate recovery valve is a spherical valve with a diameter of 50 mm.

[0017] In the above-mentioned chemical-biological coupling fixation system for carbon dioxide in flue gas, the algae liquid recovery valve of the photobioreactor is a spherical valve with a diameter of 100 mm.

[0018] In the above-mentioned chemical-biological coupling fixation system for carbon dioxide in flue gas, the inner diameter of the photobioreactor body is 2610 mm and the outer diameter is 3000 mm.

[0019] In the above-mentioned chemical-biological coupling fixation system for carbon dioxide in flue gas, the main body of the photobioreactor has a height of 6100 mm.

[0020] In the above-mentioned chemical-biological coupling fixation system for carbon dioxide in flue gas, the top cover plate of the photobioreactor has a diameter of 3300 mm and a thickness of 100 mm.

[0021] In the above-mentioned microalgae carbon dioxide fixation process, the spray tower has a height of 1800 mm, a diameter of 300 mm, and a flue gas outlet diameter of 65 mm at the top of the tower.

[0022] The above-mentioned chemical-biological coupling fixation system for carbon dioxide in flue gas has three observation windows on the spray tower body, each of which has a diameter of 200 mm.

[0023] The above-mentioned chemical-biological coupling fixation system for carbon dioxide in flue gas is provided with a spray tower provided with a spray pump, which delivers nutrient solution to the top of the spray tower through a spray pipe, and the diameter of the spray pipe is 50 mm.

[0024] The chemical-biological coupling fixation system for carbon dioxide in flue gas has a flue gas inlet pipe at the bottom of the spray tower body. The flue gas inlet pipe is 50 mm long and 50 mm in diameter.

[0025] The above-mentioned chemical-biological coupling fixation system for carbon dioxide in flue gas has a waste liquid outlet at the bottom of the spray tower body, which is connected to the chemical regulating tank. The outlet pipe is 40 mm long and 40 mm in diameter.

[0026] The above-mentioned chemical-biological coupling fixation system for carbon dioxide in flue gas has a size of the chemical adjustment tank of length×width×height: 2100×2100×2000 mm.

[0027] The chemical-biological coupling fixation system for carbon dioxide in flue gas has an agitator at the center of the chemical regulating tank, which is perpendicular to the horizontal plane above the regulating tank and extends vertically downward, with a length of 600 mm.

[0028] In the chemical-biological coupling fixation system for carbon dioxide in flue gas, the diameter of the stirring paddle of the stirrer is 200 mm.

[0029] In the chemical-biological coupling fixation system for carbon dioxide in flue gas, a lifting pump is provided at the bottom of the chemical regulating tank and is connected to the water outlet by a lifting pipe, and the length of the lifting pipe is 1750 mm.

[0030] The chemical-biological coupling fixation system for carbon dioxide in flue gas, wherein the chemical regulating tank stirring system is composed of a steering bracket, a steering rod, a support frame, and a stirrer, so that the liquid in the regulating tank is evenly mixed and fully reacted to provide nutrient solution for the photobioreactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Attachment Figure 1 is a three-dimensional schematic diagram of the photobioreactor;

[0032] Attachment Figure 2 Front view of the photobioreactor;

[0033] Attachment Figure 3 Top view of the photobioreactor;

[0034] Attachment Figure 4 1-1 cross-sectional view of the photobioreactor;

[0035] Attachment Figure 5 Chemical regulating tank plan;

[0036] Attachment Figure 6 Chemical regulating tank 1-1 cross-section;

[0037] Attachment Figure 7 Cross-section of chemical regulating tank 2-2;

[0038] Attachment Figure 8 Front view of the spray tower;

[0039] Attachment Figure 9 Cross-sectional view of spray tower;

[0040] Attachment Figure 10 Top view of the spray tower;

[0041] Attachment Figure 11 Flowchart of microbial carbon dioxide fixation. DETAILED DESCRIPTION

[0042] The following is a further description of this process with reference to the accompanying drawings:

[0043] As attached Figure 11 As shown in the flow chart, this process assumes that the flue gas entering the carbon fixation treatment system has already undergone dust removal, dehumidification, desulfurization, and denitrification, and only processes the carbon dioxide in the flue gas. To create a temperature environment suitable for algae growth, the flue gas must first be condensed and cooled. It then passes into a spray tower, where excess carbon dioxide reacts with potassium carbonate to produce a saturated potassium bicarbonate solution. This solution is stored in a chemical regulating tank and used as a supplementary carbon source for the microalgae carbon fixation process within the photobioreactor. The flue gas at the spray tower outlet then passes into the photobioreactor treatment unit, where carbon dioxide serves as a nutrient source for algae photosynthesis, ultimately achieving carbon dioxide fixation and microalgae biomass production. The resulting microalgae is collected in a microalgae collection pool, filtered, and then transported to the subsequent biomass resource utilization unit.

[0044] As attached Figure 1 The photobioreactor is shown, with the inner radius of the reaction column r = 150 mm, the outer jacket radius R = 200 mm, the height h = 600 mm, the effective liquid level depth at 2 / 3 of the height of the reaction column, the light intensity 1500 Lux, and the CO2 ventilation volume q = 20 ml / min.

[0045] Attachment Figure 2 The figure shows the front view of the photobioreactor. Carbon dioxide waste gas enters through the carbon dioxide waste gas inlet at the bottom of the photobioreactor and flows out from the clean gas outlet at the top. A carbon dioxide sensor is provided at the top to measure the carbon dioxide concentration at the outlet.

[0046] Attachment Figure 3 The photobioreactor is shown from above. The waterproof lamp is installed vertically downward in the lamp slot in the center of the reactor, providing light for the algae solution. The lamp slot is 4720mm long and 100mm in diameter; the wall thickness is 10mm. The waterproof lamp is 50mm in diameter and 4620mm long. The circulating water layer is cylindrical in shape, with an inner diameter of 2610mm and an outer diameter of 3000mm. The inner wall thickness is 10mm, and the outer wall thickness is 20mm.

[0047] Attachment Figure 4 The photobioreactor is shown in cross-section 1-1. An aeration plate is provided at the bottom of the reactor to allow carbon dioxide to be stably and evenly introduced into the algae liquid. The aeration plate is arranged in a ring shape in the reactor, with an aperture of 0.2 mm and a porosity of 36%.

[0048] Attachment Figure 5 This is the plan of a chemical regulating tank with a designed residence time (HRT) of 12 hours, a reinforced concrete structure, and a fully buried layout. The designed effective water depth is h = 2m, the side length is L = 2.1m, and the depth-to-diameter ratio is h / L 0.95.

[0049] Attachment Figure 6 This is a cross-sectional view of the chemical regulating tank 1-1. An agitator and a lifting pump are provided in the regulating tank, and a waterproof casing is provided on the outside of the lifting pipe.

[0050] Attachment Figure 7 This is the cross-section of the chemical regulating tank 2-2. According to the calculations involved, the WQ25-8-22 type lift pump is selected, with a diameter of 25mm and a flow rate of 8m 3 / h, power 1.2kw, select QJB0.37 / 6-220 / 3-960 / S model agitator, stirring solution initial velocity 0.2m / s, unit flow power consumption 0.37W / (m 3 ·s), impeller diameter 220mm, impeller area 0.038m 2 , wherein, the stirring system consists of a steering bracket, a steering rod, a support frame and a stirrer.

[0051] Attachment Figure 8 This is the front view of the spray tower. The diameter of the spray tower is 300mm and the cross-sectional area of ​​the tower is 0.07m. 2 The spray tower is 1800mm high. The designed filling height of the spray tower is 1200mm, and the lower part is supported by corrugated support plates.

[0052] Attachment Figure 9 This is a cross-sectional view of the spray tower. Potassium carbonate is pumped into the top of the spray tower along the spray pipe by a spray pump. A water baffle is provided on the top of the spray tower. The tower body is provided with two layers of filler and a layer of filter cotton. Carbon dioxide waste gas enters from the bottom air inlet and conducts mass transfer with the potassium carbonate liquid in the spray tower to achieve the purpose of fully absorbing carbon dioxide.

[0053] Attachment Figure 10 This is a top view of the spray tower. Carbon dioxide exhaust gas is introduced into the spray tower by a high-pressure induced draft fan. The flue gas inlet pipe is 50mm long and has a pipe diameter of 50mm; the outlet pipe has a diameter of 65m, and the material is SS304, with a pressure level of PN6.

Claims

1. A chemical-biological coupling fixation system for carbon dioxide in flue gas, comprising a clean gas outlet valve (1), a circulating water outlet valve (2), a filtrate recovery valve (3), an algae liquid recovery valve (4), a carbon dioxide waste gas inlet valve (5), an aeration plate (6), a circulating water inlet valve (7), a nutrient solution input valve (8), a spray tower, a chemical regulating tank, a nutrient solution storage tank, an algae liquid collection tank, and a filter press lighting assembly. The system is characterized by: The clean gas outlet valve (1) is above the photobioreactor; the filtrate recovery valve (3) is above the algae liquid recovery valve (4); the nutrient solution input valve (8) is above the circulating water inlet valve (7); the carbon dioxide waste gas inlet valve (5) is at the bottom of the photobioreactor, 680 mm from the ground, and is connected to the spray tower outlet; the algae liquid recovery valve (4) is connected to the algae liquid collection pool; and the nutrient solution input valve (8) is connected to the nutrient solution storage pool.

2. The chemical-biological coupling fixation system for carbon dioxide in flue gas according to claim 1, characterized in that The photobioreactor is provided with a circulating water layer surrounding the outer layer of the nutrient solution; the lighting assembly described in claim 1 consists of a waterproof lamp tube and a vertical downward light trough, the light trough is 4720mm long and 100mm in diameter; the wall thickness of the light trough is 10mm; the waterproof lamp tube has a diameter of 50mm and a length of 4620mm; the circulating water layer is characterized in that some components of the circulating water layer are cylindrical, with an inner diameter of 2610mm and an outer diameter of 3000mm; the inner wall thickness of the circulating water layer is 10mm, and the outer wall thickness is 20mm.

3. The chemical-biological coupling fixation system for carbon dioxide in flue gas according to claim 1, characterized in that The spray tower has a diameter of 300mm, a height of 1800mm, and a cross-sectional area of ​​0.07m 2 The height of the packing in the tower is 1200mm.

4. The chemical-biological coupling fixation system for carbon dioxide in flue gas according to claim 1, characterized in that The dimensions of the chemical regulating tank are length × width × height: 2100 × 2100 × 2000 mm.

5. The chemical-biological coupling fixation system for carbon dioxide in flue gas according to claim 1, characterized in that The clean gas outlet valve (1), the circulating water outlet valve (2), the filtrate recovery valve (3), the algae liquid recovery valve (4), the carbon dioxide waste gas inlet valve (5), the circulating water inlet valve (7), and the nutrient solution input valve (8) all use ball valves.

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