System and method for direct liquid-phase carbonation of calcium carbide slag in a bubbling bed

Abstract

The present application belongs to the technical field of direct liquid-phase carbonation of alkaline solid waste, and discloses a system for direct liquid-phase carbonation of carbide slag in a bubbling bed, which comprises a bubbling bed reaction system, a collection and analysis system and a liquid-phase circulation system. The present application also discloses a method for realizing carbon fixation of carbide slag at normal temperature and pressure and recycling of liquid phase by using the system, and the flow pattern in the bubbling bed reactor is monitored and controlled. On the one hand, CO2 fixation at normal temperature and pressure and treatment of alkaline solid waste can be implemented, and environmental pollution can be reduced; on the other hand, recycling of liquid phase can be realized, water resources can be saved, and comprehensive treatment and disposal of alkaline solid waste and CO2 at low energy consumption can be realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solid waste resource utilization and liquid phase carbonation, and relates to a liquid phase carbonation technology of carbide slag at normal temperature and pressure. BACKGROUND

[0002] At present, more than 70% of the carbide in China is used to produce polyvinyl chloride resin (PVC), and 1.5-1.6 tons of carbide are consumed to produce 1 ton of PVC, and 1.8-1.9 tons of dry-based carbide slag are generated at the same time. The annual output of carbide slag in China is about 43 million tons, and the cumulative stockpiling amount of carbide slag has exceeded 100 million tons. Carbide slag is generally stockpiled in an open-air manner or buried in sand, which not only occupies land resources and causes environmental pollution, but also seriously endangers the health of residents living around the region where carbide slag is stockpiled. Improving the utilization rate of carbide slag and reducing the open-air stockpiling of carbide slag can not only obtain economic benefits, but also have good environmental and social benefits.

[0003] Under the increasingly severe climate problem, carbon emission reduction has become the consensus of many countries in the world. In order to achieve the "double carbon" goal, it is very important to implement a reasonable and reliable CO2 emission reduction technology. Accelerating carbonation technology is one of the carbon sequestration technologies, which uses alkaline minerals or alkaline solid waste to react with CO2 to form stable carbonated minerals. This technology can be divided into two categories: mineral carbonation technology and alkaline solid waste carbonation technology. This technology can be divided into direct and indirect paths, and the direct carbonation path can be further divided into direct gas-solid path and direct liquid phase path. The liquid phase path is a very effective carbonation path, which has good reaction efficiency, reaction kinetics and good by-products. The direct liquid phase carbonation reaction using minerals generally has the following disadvantages: high process processing cost, need for chemical additives, very slow reaction kinetics and very high energy consumption. Alkaline solid waste is generally close to industrial reaction equipment, has higher reaction activity, and has better environmental stability after treatment, so more researchers turn to the research of alkaline solid waste direct liquid phase carbonation technology. The overall technology in this direction is not mature enough and cannot be well converted into commercial scale application. Alkaline solid waste carbide slag is less used for direct liquid phase carbonation technology. Alkaline solid waste liquid phase carbonation technology still has the disadvantages of high energy consumption, therefore, reducing energy consumption and controlling cost is an important development direction of the technology. SUMMARY

[0004] (I) Technical problems to be solved

[0005] The present application is directed to the problem of the direct liquid-phase carbonation technology device of carbide slag in the reasonable utilization technology of solid waste at present. A system and method for direct liquid-phase carbonation of carbide slag in a bubbling bed are proposed, aiming to realize the purpose of rational utilization of solid waste by using industrial alkaline solid waste such as carbide slag for carbonation reaction in the simplest environment. Further, the environmental pollution caused by leaching of heavy metals in solid waste such as carbide slag is reduced, and important technical reference is provided for the research of carbonation. Moreover, the product of the reaction can also be used for recycling in the construction industry.

[0006] (ii) Technical solution

[0007] In order to achieve the above-mentioned purpose, the technical solution adopted by the present application is: a system and method for direct liquid-phase carbonation of carbide slag in a bubbling bed, which comprises a bubbling bed reaction system, a collection and analysis system and a liquid-phase circulation system, wherein: the bubbling bed reaction system is used for direct liquid-phase carbonation reaction of carbide slag; the collection and analysis system is used for collecting pressure pulsation signals, pH value, conductivity and CO2 concentration at the outlet of the reactor and tail gas components in the bubbling bed reactor; the liquid-phase circulation system is used for liquid-solid separation of the slurry after reaction, and recycling of the clear liquid.

[0008] As a further preferred embodiment of the present application, the bubbling bed reaction system comprises a bubbling bed reactor, one side of the upper part of the bubbling bed reactor is connected with a solid material storage chamber, and a solid feeding port is arranged on the upper part of the solid material storage chamber; the other side of the upper part of the bubbling bed reactor is provided with a supplementary liquid phase inlet, and a mass flow meter one is arranged at the supplementary liquid phase inlet; a gas inlet is arranged at the bottom of the bubbling bed reactor, and a mass flow meter two is arranged at the gas inlet; a slurry phase outlet is arranged at one side of the lower part of the bubbling bed reactor, and a slurry pump one is arranged at the slurry phase outlet.

[0009] As a further preferred embodiment of the present application, the liquid-phase circulation system comprises a solid-liquid separation device connected with the slurry phase outlet of the bubbling bed reactor, a solid waste outlet is arranged at the bottom of the solid-liquid separation device, a recovered liquid phase outlet is arranged at the upper part of the solid-liquid separation device, a mass flow meter three is arranged at the recovered liquid phase outlet, the recovered liquid phase outlet is connected with a recovered liquid phase device through a slurry pump two, the recovered liquid phase device is connected with the bubbling bed reactor through a slurry pump three, and a mass flow meter four is arranged on the connecting pipeline between the recovered liquid phase device and the bubbling bed reactor.

[0010] As a further preferred embodiment of the present application, the collection and analysis system comprises a sampling port arranged on one side of the bubble column reactor, a pH meter I arranged at the sampling port, pressure sensor I and pressure sensor II arranged at two different positions on the bubble column reactor, CO2 sensor and flue gas analyzer arranged at the upper part of the bubble column reactor, and pH meter II arranged on the recovered liquid phase device.

[0011] A method for performing direct liquid-phase carbonation and carbon sequestration of calcium carbide slag in a bubble column reactor using the system described above, the method comprising the following steps:

[0012] (1) A specified amount of gas phase, liquid phase and solid phase are respectively introduced into the bubble column reactor through the gas-liquid-solid material feeding device, the gas phase is metered by mass flow meter II before entering the bubble column reactor, the liquid phase is metered by mass flow meter I before entering the bubble column reactor, and the calcium carbide slag solid phase material is weighed and then introduced into the bubble column reactor through the solid phase feeding port;

[0013] (2) Gas-liquid-solid bubble column is used for gas-liquid-solid three-phase mixing and reaction, and the collection and analysis system is used for real-time monitoring of the pressure pulsation signal, pH value, conductivity, CO2 concentration value and gas component of the slurry. All data are collected in the computer storage after passing through the data acquisition card, and the slurry in the reaction process is sampled and analyzed at a certain time interval;

[0014] (3) The pressure pulsation data are analyzed by the pressure sensor I and the pressure sensor II in the collection and analysis system in time and frequency domain to obtain flow pattern characterization data, and then the flow pattern of the bubble column reactor is determined. When the pH value monitored by the pH meter I is lower than 6, it is preliminarily determined that the reaction endpoint is reached. The slurry samples in the reaction process and after the reaction are dried and then subjected to thermogravimetric analysis;

[0015] (4) While the gas phase is introduced, the slurry after reaction is introduced into the liquid-solid separation device through the slurry pump I, and the liquid-solid separation is performed by natural sedimentation. The upper clear liquid is introduced into the recovered liquid phase device through the slurry pump and mass flow meter III for controlling the flow rate. The recovered clear liquid is introduced into the bubble column reactor through the slurry pump III and mass flow meter IV for participating in the liquid phase feeding, so as to control the ratio of the circulating liquid phase feeding amount and the fresh liquid phase feeding amount. At the same time, the pH value of the liquid phase in the pH meter II 23 monitoring device 24 is monitored to understand the system operation state;

[0016] (5) The calcium carbide slag liquid-phase carbonation efficiency is calculated through the slurry thermogravimetric analysis, the CO2 concentration of the gas outlet is monitored, the CO2 absorption amount is calculated synchronously, and the gas component is analyzed. If the gas is hydrogen sulfide or sulfur dioxide, the outlet gas needs to be treated.

[0017] As a further preferred embodiment of the present application, the expression for calculating the relationship between the calcium carbide slag carbonation efficiency and the CO2 absorption amount is:

[0018]

[0019]

[0020] In formula (1), η is the carbonation efficiency of carbide slag, the original mass of the carbide slag is m1, the percentage of mass reduction of Ca(OH)2 in the unreacted carbide slag at 300-500℃ in the TG analysis is A1, the mass of the carbide slag after the carbonation reaction is m2, and the percentage of mass reduction of Ca(OH)2 in the carbide slag after the reaction is defined as A2.

[0021] In formula (2), C CO2total is the total amount of CO2 introduced, and C CO2remain is the total amount of CO2 in the tail gas after the reaction.

[0022] (III) Beneficial effects

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] The present application provides a system and a method for direct liquid-phase carbonation of carbide slag in a bubbling bed. The system mainly comprises a bubbling bed reaction system, a collection and analysis system, and a liquid-phase circulation system. The method can realize direct liquid-phase carbonation of carbide slag in the system, and the environmental stability of the carbide slag after the reaction is improved. By adjusting the operating conditions, the carbide slag can achieve a high carbon fixation amount. The slurry after the reaction can be separated from the solid through the slurry circulation system, promoting the reuse of the clear liquid and saving water. The gas-liquid-solid feed amount can be precisely controlled. At the same time, the real-time collection and analysis of the slurry pressure pulsation signal in the bubbling bed reactor can monitor and control the flow pattern in the reactor, mainly including homogeneous flow and heterogeneous flow.

[0025] The carbon fixation amount of the technology depends on the optimization of the operating conditions, and also depends on the content of Ca(OH)2 in the carbide slag. Through the operation of the system, the CO2 fixation amount can be 214.05-401 g CO2 / kg of carbide slag. Compared with the carbon fixation amount of other alkaline solid waste liquid-phase carbonation technologies, the present application has a high carbon fixation amount and technical development potential. BRIEF DESCRIPTION OF DRAWINGS

[0026] The present application will be further described below in combination with the drawings and examples.

[0027] Figure 1 The system structure diagram of the present application is shown in FIG. 1.

[0028] Figure 1 The reference signs in the drawings are explained as follows:

[0029] 1, solid feed inlet, 2, material storage chamber, 3, sampling port, 4, pH meter 1, 23, pH meter 2, 5, bubble bed reactor, 6, gas inlet, 7, mass flow meter 2, 10, mass flow meter 4, 12, mass flow meter 1, 22, mass flow meter 3, 8, CO2 sensor, 9, flue gas analyzer, 11, slurry pump 3, 16, slurry pump 1, 21, slurry pump 2, 13, make-up liquid phase inlet, 14, pressure sensor 1, 15, pressure sensor 2, 17, slurry phase outlet, 18, solid-liquid separation device, 19, solid waste outlet, 20, recovered liquid phase outlet, 24, recovered liquid phase device.

[0030] Figure 2 Thermogravimetric curve diagram for the embodiment of the present application;

[0031] Figure 3 Carbonation efficiency diagram for the embodiment of the present application;

[0032] Figure 4 Flow pattern identification diagram for the embodiment of the present application, Figure 4 (a), (b), (c), (d), (e), (f), (g), (h), (i) respectively show the U g The flow pattern has a value of 0.041 m / s, 0.061 m / s, 0.082 m / s, 0.102 m / s, 0.123 m, 0.14 m / s, 0.16 m / s, 0.18 m / s, 0.205 m / s. DETAILED DESCRIPTION

[0033] The following will be described in detail in combination with specific embodiments, and it is worth mentioning that the following description is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art within the technical scope disclosed by the present application, according to the technical solution and inventive concept of the present application, equivalent replacement or change, should be covered within the protection scope of the present application.

[0034] A system and method for direct liquid-phase carbonation of carbide slag in a bubble bed are provided herein, such as Figure 1As shown, the device includes a reverse bubble bed reaction system, a collection and analysis system, and a liquid phase circulation system. The bubble bed reaction system includes a bubble bed reactor 5, a solid feed inlet 1, a material storage chamber 2, a gas inlet 6, a mass flow meter 2 7 and a mass flow meter 1 12, a supplementary liquid phase inlet 13, a slurry pump 1 16 and a slurry phase outlet 17; the collection and analysis system includes a sampling port 3, a pH meter 1 4, a CO2 sensor 8, a flue gas analyzer 9, a pressure sensor 1 14, a pressure sensor 2 15, a pH meter 2 23; the liquid phase circulation system includes a mass flow meter 4 10 and a mass flow meter 3 22, a slurry pump 3 11 and a slurry pump 2 21, a solid-liquid separation device 18, a solid waste outlet 19, a recovered liquid phase outlet 20, and a recovered liquid phase device 24. Among them: the bubble bed reaction system is used for direct liquid phase carbonation reaction of carbide slag; the collection and analysis system is used for collecting pressure pulsation signals, pH value, conductivity and CO2 concentration at the outlet of the reactor and tail gas components in the bubble bed reactor; the liquid phase circulation system is used for liquid-solid separation of the slurry after reaction, and recycling of the clear liquid.

[0035] The amounts that need to be controlled are the gas velocity (gas flow meter) and the liquid-solid ratio (solid weighing, liquid passing through the mass flow meter). By controlling the gas velocity and the liquid-solid ratio, different reaction conditions and flow conditions can be obtained, and related experimental phenomena can be obtained.

[0036] Example 1. Carbonation efficiency. The device can be used as experimental equipment to obtain the thermogravimetric curve related data of the change of the solid before and after the reaction. The carbonation efficiency is calculated by the following formula:

[0037]

[0038] In formula (1), η is the carbonation efficiency of carbide slag, the mass of the original carbide slag is m1, in TG analysis, the mass percentage of Ca(OH)2 in the unreacted carbide slag completely decomposed at 300-500°C is A1, the mass of the carbide slag after carbonation reaction is m2, and the mass reduction percentage of Ca(OH)2 in the reacted carbide slag after decomposition is defined as A2.

[0039] The thermogravimetric curve is shown in Figure 2 The carbonation efficiency is shown in 3. When the liquid-solid ratio is 5 ml / g, the carbonation efficiency under different gas velocities is shown in 3. The optimal carbonation efficiency is at the position of 0.012 m / s. Through the operation of the system, the CO2 fixation amount can be 214.05-401 g CO2 / kg carbide slag. This is one of the functions of the device, and it can be used for any research involving three-phase reaction.

[0040] Example 2. Flow pattern identification. As shown in Figure 4As shown, the liquid-solid ratio is 5 ml / g, and the uniform flow state can be maintained in a wide range of Ug(0.041 m / s~0.102 m / s), wherein Ug represents the superficial gas velocity into the reactor. Due to the low bed expansion height, at a small gas velocity, the opportunity for large-sized bubbles to form in the bed is less, and only some fine foam can be seen, and when the flow rate is 0.123 m / s, a non-uniform flow pattern can be observed. When the surface gas velocity is above 0.123 m / s, larger irregular bubbles are observed to be generated, belonging to a strong turbulent flow.

[0041] So far, the above example of the system and method for direct liquid-phase carbonation of carbide slag in a bubbling bed can be applied to any research involving a three-phase reaction for CO2 fixation.

[0042] The above-described specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A system for direct liquid-phase carbonation of calcium carbide slag in a bubbling bed for carbon capture, characterized in that, The system comprises a bubbling bed reaction system, a collection and analysis system and a liquid phase circulation system, wherein: the bubbling bed reaction system is used for carrying out a carbide slag direct liquid phase carbonation reaction; the collection and analysis system is used for collecting pressure pulsation signals, pH value, conductivity and CO2 concentration at the reactor outlet and tail gas components in the bubbling bed reactor; and the liquid phase circulation system is used for carrying out liquid-solid gravity sedimentation separation on the slurry after reaction, and recycling the clear liquid; The bubbling bed reaction system comprises a bubbling bed reactor (5), one side of the upper portion of the bubbling bed reactor (5) is connected with a solid material storage chamber (2), and a solid feeding port (1) is arranged on the upper portion of the solid material storage chamber (2); the other side of the upper portion of the bubbling bed reactor (5) is provided with a supplementary liquid phase inlet (13), and a mass flowmeter one (12) is arranged at the supplementary liquid phase inlet (13); a gas inlet (6) is arranged at the bottom of the bubbling bed reactor (5), and a mass flowmeter two (7) is arranged at the gas inlet (6); a slurry phase outlet (17) is arranged at one side of the lower portion of the bubbling bed reactor (5), and a slurry pump one (16) is arranged at the slurry phase outlet (17); The liquid phase circulation system comprises a solid-liquid separation device (18) connected with the slurry phase outlet (17) of the bubbling bed reactor (5), a solid waste outlet (19) is arranged at the bottom of the solid-liquid separation device (18), a recovered liquid phase outlet (20) is arranged at the upper portion of the solid-liquid separation device (18), a mass flowmeter three (22) is arranged at the recovered liquid phase outlet (20), the recovered liquid phase outlet (20) is connected with a recovered liquid phase device (24) through a slurry pump two (21), the recovered liquid phase device (24) is connected with the bubbling bed reactor (5) through a slurry pump three (11), and a mass flowmeter four (10) is arranged on the connecting pipeline between the recovered liquid phase device (24) and the bubbling bed reactor (5); The collection and analysis system comprises a sampling port (3) arranged on one side of the bubbling bed reactor (5), a pH meter one (4) is arranged at the sampling port (3), further comprises a pressure sensor one (14) and a pressure sensor two (15) arranged at two different positions on the bubbling bed reactor (5), further comprises a CO2 sensor (8) and a flue gas analyzer (9) arranged on the upper portion of the bubbling bed reactor (5), and further comprises a pH meter two (23) arranged on the recovered liquid phase device (24).

2. The method for direct liquid phase carbonation of carbide slag in a bubble column reactor using the system of claim 1, characterized in that, The method comprises the following steps: (1) a specified amount of gas phase, liquid phase and solid phase are respectively introduced into the bubbling bed reactor (5) through a gas-liquid-solid material feeding device, the gas phase is introduced into the bubbling bed reactor (5) after metering through the mass flowmeter two (7), the liquid phase is introduced into the bubbling bed reactor (5) after metering through the mass flowmeter one (12), and the carbide slag solid phase material is introduced into the bubbling bed reactor (5) after weighing through the solid feeding port; (2) In the bubble column reactor (5), gas-liquid-solid three-phase mixing and reaction were carried out, and the pressure fluctuation signal, pH value, conductivity, CO2 concentration value and gas component of the slurry were monitored in real time by the collection and analysis system. All data were collected in the computer storage after the data acquisition card, and the slurry in the reaction process was sampled and analyzed at a certain time interval; (3) The pressure sensor one (14) and the pressure sensor two (15) in the collection and analysis system were used to analyze the pressure fluctuation data in time and frequency domain, to obtain flow pattern characterization data, and to determine the flow pattern of the bubble column reactor (5). When the pH value monitored by the pH meter one (4) was lower than 6, it was preliminarily determined that the reaction endpoint was reached. The slurry samples in the reaction process and after the reaction were dried and analyzed by thermogravimetric analysis; (4) While the gas phase was introduced, the slurry after the reaction was introduced into the solid-liquid separation device (18) through the slurry pump one (16) for natural sedimentation and liquid-solid separation. The upper clear liquid was introduced into the recovered liquid phase device (24) through the slurry pump two (21) and the mass flow meter three (22) to control the flow rate. The recovered clear liquid was introduced into the bubble column reactor (5) through the slurry pump three (11) and the mass flow meter four (10) to participate in the liquid phase feeding, to control the ratio of the circulating liquid phase feeding amount and the fresh liquid phase feeding amount. At the same time, the pH meter two (23) was used to monitor the pH value of the liquid phase in the recovered liquid phase device (24) to understand the system operation state; (5) The calcium carbide slag liquid carbonation efficiency was calculated by thermogravimetric analysis of the slurry, and the CO2 concentration at the gas outlet was monitored to calculate the CO2 absorption amount and analyze the gas component. If there was hydrogen sulfide or sulfur dioxide gas, the outlet gas needed to be treated; The expression for calculating the relationship between the calcium carbide slag carbonation efficiency and the CO2 absorption amount is: （1） （2） In formula (1), is the carbamation efficiency of carbide slag; C in formula (2) CO2total is the total amount of CO2 admitted, C CO2remain is the total amount of CO2 in the exhaust gas after the reaction.

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