System for synergistically preparing ammonium bicarbonate based on alkalized biogas slurry and aerobic digested CO2 and operation method thereof

Abstract

The invention provides a system for synergistically preparing ammonium bicarbonate based on alkalized biogas slurry and aerobic digestion CO2 and an operation method thereof, and relates to the technical field of resource recovery, the system comprises a CO2 gas supply and pretreatment unit, a biogas slurry pretreatment and alkalization unit, an ammonium bicarbonate synthesis reactor, an ammonium bicarbonate post-treatment unit and a control and monitoring unit, cO2-rich gas generated by aerobic digestion of kitchen waste is treated by a CO2 gas supply and pretreatment unit, and then is introduced into an ammonium bicarbonate synthesis reactor to react with alkalized biogas slurry from a biogas slurry pretreatment and alkalization unit to obtain ammonium bicarbonate crystal slurry; and conveying the ammonium bicarbonate crystal slurry to an ammonium bicarbonate post-treatment unit for separation, washing and drying to obtain an ammonium bicarbonate product. The technical problems of high cost, complex process and high energy consumption in the prior art are solved, and the technical effect of integrally preparing ammonium bicarbonate based on direct absorption and aerobic digestion of CO2 by the alkalized biogas slurry is achieved.

Description

Technical Field

[0001] This invention relates to the field of resource recycling technology, and in particular to a system and its operation method for the synergistic preparation of ammonium bicarbonate based on alkalized biogas slurry and aerobic digestion of CO2. Background Technology

[0002] During the aerobic digestion (composting) process of food waste, high concentrations of CO2 are generated in the exhaust gas. Current technologies for treating this CO2 are relatively limited, mainly focusing on the following: direct emission, with most small and medium-sized aerobic composting plants releasing the exhaust gas directly into the atmosphere after simple treatment such as deodorization, resulting in greenhouse gas emissions; use as greenhouse fertilizer, with some research or practical attempts to introduce this CO2 into agricultural greenhouses as gaseous fertilizer, but this is limited by location, season, and transportation conditions; and conventional carbon capture, such as chemical absorption (amine washing), physical adsorption (pressure swing adsorption PSA), and membrane separation, which are mature CO2 capture technologies that can capture this CO2, but face problems such as high cost, complex processes, and high energy consumption when dealing with relatively dispersed and small-scale emission sources like aerobic digestion of food waste.

[0003] Biogas slurry is a byproduct of anaerobic digestion and is rich in ammonia nitrogen (mainly NH4). + (In the form of NH4). Existing technologies for the recovery and utilization of ammonia nitrogen in biogas slurry mainly focus on the following aspects: ammonia stripping / stripping-acid absorption method, which increases the pH value by adding alkaline agents (such as lime, sodium hydroxide) to the biogas slurry, thereby reducing NH4. + The process involves converting NH3 into free NH3, then introducing air (ammonia stripping) or steam (ammonia vapor stripping) to separate NH3 from the biogas slurry. This NH3 is then absorbed by acidic solutions such as sulfuric acid or nitric acid to produce ammonium salt fertilizers or chemical products such as ammonium sulfate and ammonium nitrate. However, this method suffers from high energy consumption (especially steam stripping), large equipment investment, secondary pollution (such as ammonia escape), and strong acid consumption. The struvite (MAP) precipitation method, on the other hand, involves adding magnesium salts and phosphates (or utilizing the biogas slurry's own phosphates) to the biogas slurry, allowing ammonia nitrogen to react with phosphates under suitable pH conditions. Roots react with magnesium ions to form magnesium ammonium phosphate (struvite) precipitate, thereby recovering ammonia and phosphorus. However, this method is limited by the phosphorus content in the biogas slurry, and the product is a specific type of slow-release fertilizer. Ion exchange, adsorption, and membrane separation methods are also used for ammonia nitrogen recovery from biogas slurry, but they are usually costly or have limited processing capacity, which limits their large-scale application. For direct agricultural use, after appropriate treatment (such as solid-liquid separation and dilution), biogas slurry can be directly applied to farmland as liquid fertilizer, but there are problems such as inconvenient transportation, unstable nutrient concentration, and risks of heavy metals and pathogens.

[0004] Traditional methods for preparing ammonium bicarbonate mainly focus on the following aspects: Industrial synthesis method, where ammonium bicarbonate (NH4HCO3) is traditionally produced by reacting liquid ammonia produced in ammonia synthesis plants with CO2 under certain conditions (carbonization method). This method relies on large-scale ammonia synthesis industry and has low correlation with waste resource utilization; Ammonium bicarbonate is prepared by using recovered ammonia. Ammonia recovered from sewage or waste (e.g., ammonia gas or ammonia water obtained by stripping) is reacted with CO2 (e.g., CO2 in boiler flue gas or biogas) to prepare ammonium bicarbonate or ammonium carbonate. The core of this method is to pre-separate and purify ammonia from the original mother liquor before reacting it with CO2. For example, ammonia gas is obtained by stripping biogas slurry with ammonia and then passed into a carbonization tower to react with CO2. Although this method achieves the combination of nitrogen and carbon in waste, it still includes a separate ammonia separation and purification step. The process is relatively long, and the energy consumption and cost of the ammonia separation step still exist.

[0005] In summary, existing technologies for the separate treatment or recovery of CO2 and ammonia nitrogen from aerobic digestion, as well as processes for preparing ammonium bicarbonate from relatively pure recovered ammonia and CO2, require complex CO2 capture and purification steps, or energy-intensive pre-separation steps such as ammonia stripping / stripping.

[0006] Currently, there is an urgent need for an integrated and efficient method to synthesize ammonium bicarbonate by directly reacting CO2 produced from the aerobic digestion of kitchen waste with biogas slurry that has undergone simple alkalization pretreatment.

[0007] In view of this, the present invention is hereby proposed. Summary of the Invention

[0008] One of the objectives of this invention is to provide a system for the synergistic preparation of ammonium bicarbonate based on alkalized biogas slurry and aerobic digestion of CO2. This system can directly react CO2 generated from the aerobic digestion of kitchen waste with biogas slurry that has undergone simple alkalization pretreatment to achieve the goal of integrated and efficient synthesis of ammonium bicarbonate.

[0009] The second objective of this invention is to provide an operating method for a system that synergistically prepares ammonium bicarbonate from alkalized biogas slurry and aerobic digestion of CO2. This method solves the technical problems of high cost, complex process, and high energy consumption in the prior art, and achieves the technical effect of integrated preparation of ammonium bicarbonate based on direct absorption of CO2 from alkalized biogas slurry and aerobic digestion.

[0010] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In the first aspect, a system for the synergistic preparation of ammonium bicarbonate based on alkalized biogas slurry and aerobic digestion of CO2 includes a CO2 gas supply and pretreatment unit, a biogas slurry pretreatment and alkalization unit, an ammonium bicarbonate synthesis reactor, an ammonium bicarbonate posttreatment unit, and a control and monitoring unit. The CO2 gas supply and pretreatment unit is used to supply CO2 from aerobic digestion and pretreat CO2 from aerobic digestion to obtain pretreated CO2 gas, which is then transported to the ammonium bicarbonate synthesis reactor. The biogas slurry pretreatment and alkalization unit is used to pretreat the raw biogas slurry to form clarified biogas slurry and alkalize the clarified biogas slurry to obtain alkalized biogas slurry, which is then transported to the ammonium bicarbonate synthesis reactor. The ammonium bicarbonate synthesis reactor is used to perform gas-liquid mass transfer of the pretreated CO2 gas to achieve CO2 absorption, react with the alkaline biogas slurry to synthesize ammonium bicarbonate, and crystallize ammonium bicarbonate to obtain ammonium bicarbonate slurry, which is then transported to the ammonium bicarbonate post-processing unit. The ammonium bicarbonate post-processing unit is used to perform solid-liquid separation and product washing on the ammonium bicarbonate slurry to obtain the ammonium bicarbonate product. The control and monitoring unit uses DCS or PLC to integrate and control each unit in the system. Based on material balance feedforward and online feedback of pH, tail gas NH3 / CO2, and temperature, it dynamically adjusts the supply of CO2 and alkaline biogas slurry and their molar ratio, thereby optimizing CO2 absorption and NH3 conversion efficiency.

[0011] Furthermore, the CO2 gas supply and pretreatment unit includes, in sequence according to the gas flow path, an aerobic digestion reactor, a gas dust collector, a gas condenser dehumidifier, a gas desulfurization tower, and a gas conveying pipeline.

[0012] Furthermore, the biogas slurry pretreatment and alkalization unit includes, in sequence, a biogas slurry storage tank, a biogas slurry solid-liquid separation device, an alkalization reaction vessel, and an alkalization biogas slurry delivery pump, according to the biogas slurry passage order. Preferably, the biogas slurry pretreatment and alkalization unit is equipped with an alkali agent adding device for adding alkali agent to the alkalization reactor; Preferably, the biogas slurry pretreatment and alkalization unit separates the original biogas slurry into solid and liquid components until the suspended solids (SS) are <1-5 g / L and alkalizes it to a pH of 9.5-10.5 before transporting it to the ammonium bicarbonate synthesis reactor.

[0013] Furthermore, the ammonium bicarbonate synthesis reactor is equipped with a gas distributor to uniformly introduce CO2 gas into the liquid phase in the form of bubbles; Preferably, the gas distributor includes at least one of a microporous aeration plate, a porous tube, and a high-efficiency gas nozzle.

[0014] Furthermore, the ammonium bicarbonate synthesis reactor is equipped with a stirring device to enhance gas-liquid mass transfer and solid-liquid suspension, and to prevent crystal sedimentation and caking. Preferably, the stirring device employs a multi-layer turbine-type or propeller-type stirring impeller; Preferably, the ammonium bicarbonate synthesis reactor is equipped with a cooling device to remove the heat of reaction and control the reaction temperature; Preferably, the ammonium bicarbonate synthesis reactor is equipped with a temperature sensor, a pH sensor, and a liquid level sensor for real-time monitoring and control of reaction conditions.

[0015] Furthermore, the ammonium bicarbonate post-treatment unit includes, in sequence according to the order in which the ammonium bicarbonate crystal slurry passes, an ammonium bicarbonate crystal slurry conveying pump, a solid-liquid separator, a crystal washing assembly, and a low-temperature dryer. Preferably, the solid-liquid separator is equipped with a washing liquid spraying device to wash the ammonium bicarbonate crystals with a low-temperature 0-10℃ saturated ammonium bicarbonate aqueous solution or cold water spray. Preferably, the drying temperature of the low-temperature dryer is not higher than 35℃-40℃, thereby preventing the thermal decomposition of ammonium bicarbonate; Preferably, the ammonium bicarbonate post-treatment unit is equipped with a mother liquor collection tank for collecting the mother liquor and washing waste liquid discharged from the solid-liquid separator; Preferably, the mother liquor is collected and reused for dilution or alkalization adjustment in biogas slurry pretreatment, and / or for nitrogen and phosphorus recovery or biochemical treatment.

[0016] Furthermore, the system is equipped with a mother liquor and tail gas treatment unit for treating the collected liquid in the mother liquor collection tank and for treating the tail gas discharged from the ammonium bicarbonate synthesis reactor. Preferably, the exhaust gas treatment method includes acid washing; Preferably, the acid washing uses dilute sulfuric acid as the absorbent, and the resulting product is ammonium sulfate.

[0017] Secondly, a method for operating the system described in any of the above claims includes the following steps: S1: The CO2-rich gas produced by the aerobic digestion of kitchen waste is sequentially treated by dust removal, condensation and dehumidification and desulfurization in the CO2 gas supply and pretreatment unit, and then introduced into the ammonium bicarbonate synthesis reactor. S2: The original biogas slurry is stored and separated from solids to achieve SS < 1-5 g / L. Alkali is added to the alkalization reactor to make the pH of the biogas slurry reach 9.5-10.5, and the alkalized biogas slurry is obtained and sent to the reactor. S3: Pretreated CO2 is introduced into the reactor through a gas distributor and CO2 absorption, reaction and crystallization are carried out at 10℃-30℃ under stirring and cooling conditions to obtain ammonium bicarbonate slurry. S4: The ammonium bicarbonate slurry is subjected to solid-liquid separation and washed with a saturated ammonium bicarbonate aqueous solution or cold water at 0-10℃. Then, it is dried at a low temperature not higher than 35℃-40℃ to obtain the ammonium bicarbonate product. S5: Acid wash the tail gas generated by the reactor to recover NH3, and return part of the treated CO2-containing gas to the CO2 pretreatment inlet as needed; Collect and reuse the mother liquor or treat it in a way that allows it to be recycled or meet standards.

[0018] Furthermore, the operating method also includes the following steps: During operation, a material balance calculation model oriented towards the target output is established, and feedforward control is achieved through parameters such as ammonia nitrogen concentration and CO2 concentration to pre-adjust the amount of reactants added. Meanwhile, real-time feedback of parameters such as pH in the reactor, NH3 / CO2 concentration in the tail gas, and reaction temperature is used to dynamically correct the molar ratio of CO2 to alkalized biogas slurry, ensuring accurate ratio of reactants and optimized absorption and conversion efficiency.

[0019] Furthermore, the ammonium bicarbonate synthesis reactor is a bubble column or stirred tank with mechanical stirring, the main body is made of corrosion-resistant material and is equipped with online monitoring of temperature, pH and liquid level.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects: The system provided by this invention, which is based on the synergistic preparation of ammonium bicarbonate from alkalized biogas slurry and aerobic digestion of CO2, can use two major wastes (waste gas and waste liquid) as the main reaction raw materials. Through a "waste-to-treasure" approach, it can be synergistically processed in an integrated system, realizing the integration of CO2 capture and nitrogen recovery. It can directly synthesize ammonium bicarbonate products as commercial nitrogen fertilizer. In summary, the system of this invention not only simplifies operation, reduces costs, and saves energy, but also realizes the efficient synergistic resource utilization of carbon and nitrogen elements in the process of treating kitchen waste and biogas slurry, which is conducive to the synergistic value-added utilization of waste.

[0021] The operating method of the system for preparing ammonium bicarbonate based on the synergistic preparation of alkalized biogas slurry and aerobic digestion of CO2 provided by the present invention solves the technical problems of high cost, complex process and high energy consumption in the prior art, and achieves the technical effect of integrated preparation of ammonium bicarbonate based on the direct absorption of alkalized biogas slurry and aerobic digestion of CO2. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1A process flow diagram for the synergistic preparation of ammonium bicarbonate based on alkalized biogas slurry and aerobic digestion of CO2, provided for one embodiment of the present invention. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] According to a first aspect of the present invention, a system for the synergistic preparation of ammonium bicarbonate based on alkalized biogas slurry and aerobic digestion of CO2 is provided, comprising a CO2 gas supply and pretreatment unit, a biogas slurry pretreatment and alkalization unit, an ammonium bicarbonate synthesis reactor, an ammonium bicarbonate posttreatment unit, and a control and monitoring unit. The CO2 gas supply and pretreatment unit is used to supply CO2 from aerobic digestion and pretreat CO2 from aerobic digestion to obtain pretreated CO2 gas, which is then transported to the ammonium bicarbonate synthesis reactor. The biogas slurry pretreatment and alkalization unit is used to pretreat the raw biogas slurry to form clarified biogas slurry and alkalize the clarified biogas slurry to obtain alkalized biogas slurry, which is then transported to the ammonium bicarbonate synthesis reactor. The ammonium bicarbonate synthesis reactor is used to achieve CO2 absorption through gas-liquid mass transfer of pretreated CO2 gas, react with alkaline biogas slurry to synthesize ammonium bicarbonate, and crystallize ammonium bicarbonate to obtain ammonium bicarbonate slurry, which is then transported to the ammonium bicarbonate post-treatment unit. The ammonium bicarbonate post-processing unit is used to perform solid-liquid separation and product washing of ammonium bicarbonate slurry to obtain ammonium bicarbonate product. The control and monitoring unit uses DCS or PLC to integrate and control each unit in the system. Based on material balance feedforward and online feedback of pH, tail gas NH3 / CO2, and temperature, it dynamically adjusts the supply of CO2 and alkaline biogas slurry and their molar ratio, thereby optimizing CO2 absorption and NH3 conversion efficiency.

[0026] This invention uses two major wastes (waste gas and waste liquid) as the main reaction raw materials. Through the "turning waste into treasure" approach, they are processed synergistically in an integrated system, realizing the integration of CO2 capture and nitrogen recovery. Ammonium bicarbonate products can be directly synthesized as commercial nitrogen fertilizer. This not only simplifies operation, reduces costs, and saves energy, but also achieves efficient synergistic resource utilization of carbon and nitrogen elements in the process of treating kitchen waste and biogas slurry, which is conducive to the synergistic value-added utilization of waste.

[0027] It should be noted that using inexpensive, even negatively valuable, biogas slurry as a CO2 absorbent replaces expensive chemical absorbents (such as amine solutions). The biogas slurry itself does not require additional preparation, and the amount of alkali required for its alkalization is relatively controllable. Because CO2 reacts directly, the desorption step after traditional capture is eliminated, avoiding huge regeneration energy consumption, thus significantly reducing the operating cost of CO2 capture and transforming it from an environmental burden into a low-cost reaction feedstock. Furthermore, with biogas slurry entering the system as a reactant, most of the ammonia nitrogen is recovered, reducing reliance on subsequent expensive advanced biogas slurry treatment (such as membrane treatment, advanced oxidation, and biological denitrification). More importantly, the nitrogen in the biogas slurry is converted into high-value ammonium bicarbonate, which can be sold directly or used as agricultural fertilizer. The "cost center" of biogas slurry treatment is transformed into a "profit center," bringing new economic growth points to food waste treatment or the livestock industry.

[0028] On the one hand, the system of this invention can directly utilize carbon (CO2) and nitrogen (NH3) in waste to synthesize nitrogen fertilizer, which is different from the Haber-Bosch ammonia synthesis process that requires high temperature and high pressure. The process in this invention is a room temperature (15°C - 25°C) reaction, and it utilizes existing waste resources. The carbon footprint and energy consumption of producing ammonium bicarbonate are far lower than those of traditional nitrogen fertilizer production, which is in line with the trend of green manufacturing and energy transition, and has long-term economic and environmental competitiveness.

[0029] On the other hand, the system of the present invention can integrate CO2 capture, ammonia nitrogen recovery and nitrogen fertilizer production, reducing the number and complexity of independent equipment units. For example, CO2 absorption and its reaction with NH3 are completed in the ammonium bicarbonate synthesis reactor, replacing the CO2 absorption tower, desorption tower and independent ammonia nitrogen recovery unit, which significantly reduces the initial investment (CAPEX) and plant floor space, and is conducive to improving the economy and scalability of the overall system.

[0030] In a preferred embodiment, the CO2 gas supply and pretreatment unit includes, but is not limited to, an aerobic digestion reactor, a gas dust collector, a gas condenser dehumidifier, a gas desulfurization tower, and a gas conveying pipeline, in the order in which the gas passes through.

[0031] Pre-treatment of CO2 gas before the reaction, including dust removal, condensation and dehumidification, and desulfurization (to prevent impurities from corroding equipment and contaminating products), helps ensure the smooth progress of subsequent reactions, improves conversion efficiency, and guarantees the quality of the final product.

[0032] In a preferred embodiment, the biogas slurry pretreatment and alkalization unit includes, but is not limited to, a biogas slurry storage tank, a biogas slurry solid-liquid separation device, an alkalization reactor, and an alkalization biogas slurry delivery pump, in the order in which the biogas slurry passes through; at the same time, the biogas slurry pretreatment and alkalization unit may be equipped with an alkali addition device for adding alkali to the alkalization reactor.

[0033] It should be noted that the biogas slurry pretreatment and alkalization unit can separate the original biogas slurry into solid and liquid components until the suspended solids (SS) are less than 1-5 g / L and alkalize it to a pH of 9.5-10.5 before transporting it to the ammonium bicarbonate synthesis reactor.

[0034] Pretreatment of the biogas slurry by solid-liquid separation (to reduce the impact of suspended solids on equipment blockage and product purity) and alkalization before the reaction is beneficial to ensure the smooth progress of subsequent reactions, improve conversion efficiency and ensure the quality of the final product.

[0035] In this invention, the specific pretreatment steps are key to ensuring efficient and stable operation of the reaction and ultimately obtaining high-purity ammonium bicarbonate products. This avoids the interference problems that may be caused by waste materials as raw materials and extends the life of the equipment.

[0036] In a preferred embodiment, the ammonium bicarbonate synthesis reactor may be equipped with a gas distributor for uniformly introducing CO2 gas into the liquid phase in the form of bubbles; the gas distributor includes, but is not limited to, at least one of microporous aeration plates, porous pipes, and high-efficiency gas nozzles.

[0037] In a preferred embodiment, the ammonium bicarbonate synthesis reactor may be equipped with a stirring device to enhance gas-liquid mass transfer and solid-liquid suspension, and to prevent crystal sedimentation and caking; the stirring device may be a multi-layer turbine type or a propeller-type stirring paddle.

[0038] In a preferred embodiment, the ammonium bicarbonate synthesis reactor may be equipped with a cooling device to remove the heat of reaction and control the reaction temperature.

[0039] In a preferred embodiment, the ammonium bicarbonate synthesis reactor may be equipped with a temperature sensor, a pH sensor, and a liquid level sensor for real-time monitoring and control of reaction conditions.

[0040] Under ambient temperature (10-30°C) conditions, the ammonium bicarbonate synthesis reactor achieves an integrated process of CO2 absorption, NH3 reaction, and ammonium bicarbonate crystallization. This integrates three complex chemical unit operations—gas-liquid mass transfer (CO2 absorption), chemical reaction (NH3 and CO2 to synthesize NH4HCO3), and product crystallization (NH4HCO3 precipitation)—into a single reactor (such as a bubble column or stirred tank), greatly simplifying the process flow and reducing equipment investment and floor space. At the same time, ambient temperature operation avoids the energy-intensive absorbent regeneration step in traditional CO2 capture technologies, significantly reducing operating energy consumption and carbon footprint, and improving economic feasibility.

[0041] In a preferred embodiment, the ammonium bicarbonate post-treatment unit includes, but is not limited to, an ammonium bicarbonate crystal slurry transfer pump, a solid-liquid separator, a crystal washing assembly, and a low-temperature dryer, in the order in which the ammonium bicarbonate crystal slurry passes through.

[0042] In this invention, the solid-liquid separator may be equipped with a washing liquid spraying device to wash the ammonium bicarbonate crystals with a low-temperature saturated ammonium bicarbonate aqueous solution or cold water at 0-10℃; at the same time, the drying temperature of the low-temperature dryer is not higher than 35℃-40℃, thereby preventing the thermal decomposition of ammonium bicarbonate.

[0043] In a preferred embodiment, the ammonium bicarbonate post-treatment unit may be equipped with a mother liquor collection tank for collecting the mother liquor and washing waste liquid discharged from the solid-liquid separator; the collected mother liquor is then reused for dilution or alkalization adjustment in the biogas slurry pretreatment, and / or for nitrogen and phosphorus recovery or biochemical treatment.

[0044] In a preferred embodiment, the system may include a mother liquor and tail gas treatment unit for treating the collected liquid in the mother liquor collection tank and for treating the tail gas discharged from the ammonium bicarbonate synthesis reactor.

[0045] It should be noted that the treatment methods for exhaust gas include, but are not limited to, acid washing. The absorbent used in acid washing can be dilute sulfuric acid, and the resulting product is ammonium sulfate.

[0046] In this invention, the overall control architecture and safety interlock of the system can adopt a distributed control system (DCS) or a high-performance programmable logic controller (PLC) as the central control platform to achieve integrated control of all units.

[0047] The control architecture is as follows: Sensor layer: Various transmitters (temperature, pressure, flow, level, pH, gas analyzer, etc.) transmit real-time data to the controller; Control layer: DCS / PLC receives data, executes PID, proportional, sequential, and other control algorithms, and sends control commands to actuators (pumps, valves, motors, etc.); Operation layer: Human-machine interface (HMI) provides intuitive process flow diagrams, real-time data, historical trends, alarm information, and parameter setting functions, facilitating operator monitoring and management.

[0048] Safety interlocks are as follows: Reactor over-temperature protection: When the reactor temperature exceeds the set upper limit (e.g., 30℃), the CO2 and biogas slurry feed will be automatically shut off, and an alarm will be triggered, while maximizing the cooling water flow rate; Dryer over-temperature protection: When the temperature inside the dryer or the hot air temperature exceeds the set upper limit (e.g., 38℃), the heating source will be automatically shut off, the feed will be stopped, and an alarm will be triggered; Reactor high / low liquid level protection: When the reactor liquid level exceeds the upper limit or falls below the lower limit, the relevant feed pump or discharge pump will be automatically stopped, and an alarm will be triggered; H2S / NH3 concentration exceeding the standard: When the H2S / NH3 gas concentration at critical points exceeds the standard, an alarm will be triggered and the reactor can be shut down or a bypass can be switched for treatment; pH runaway: If the reactor pH deviates significantly from the target range for a long period of time, or if the pH of the alkalization vessel is abnormal, an alarm will be triggered and the reactor can be shut down; Equipment failure interlock: When critical pumps, fans, agitators, and other equipment (monitored by current, pressure, or flow) fail, the reactor will automatically shut down and an alarm will be triggered, and downstream equipment will be stopped in conjunction with the equipment.

[0049] According to a second aspect of the present invention, a method for operating the system described in any of the preceding claims is provided, comprising the following steps: S1: The CO2-rich gas produced by the aerobic digestion of kitchen waste is sequentially treated by dust removal, condensation and dehumidification and desulfurization in the CO2 gas supply and pretreatment unit, and then introduced into the ammonium bicarbonate synthesis reactor. S2: The original biogas slurry is stored and separated from solids to achieve SS < 1-5 g / L. Alkali is added to the alkalization reactor to make the pH of the biogas slurry reach 9.5-10.5, and the alkalized biogas slurry is obtained and sent to the reactor. S3: Pretreated CO2 is introduced into the reactor through a gas distributor and CO2 absorption, reaction and crystallization are carried out at 10℃-30℃ under stirring and cooling conditions to obtain ammonium bicarbonate slurry. S4: The ammonium bicarbonate slurry is subjected to solid-liquid separation and washed with a saturated ammonium bicarbonate aqueous solution or cold water at 0-10℃. Then, it is dried at a low temperature not higher than 35℃-40℃ to obtain the ammonium bicarbonate product. S5: Acid wash the tail gas generated by the reactor to recover NH3, and return part of the treated CO2-containing gas to the CO2 pretreatment inlet as needed; Collect and reuse the mother liquor or treat it in a way that allows it to be recycled or meet standards.

[0050] In this invention, the pH of the alkalized biogas slurry can be 9.0-11.0, and more preferably 9.5-10.5, which can promote the alkalization of most of the ammonium nitrogen (NH4+) in the biogas slurry. + The efficient conversion of CO2 into free ammonia (NH3(aq)) not only provides a highly efficient absorbent (NH3) for subsequent CO2 absorption, but also utilizes the rapid reaction between NH3 and CO2 to keep the CO2 concentration in the liquid phase at an extremely low level, thereby maintaining a strong gas-liquid mass transfer driving force and ensuring efficient CO2 absorption.

[0051] The operating method of the system of the present invention solves the technical problems of high cost, complex process and high energy consumption in the prior art, and achieves the technical effect of integrated preparation of ammonium bicarbonate based on direct absorption of CO2 from alkalized biogas slurry and aerobic digestion.

[0052] It should be noted that the ammonium bicarbonate synthesis reactor can be a bubble column or a stirred tank with mechanical stirring. The main body can be made of corrosion-resistant materials and can be equipped with online monitoring of temperature, pH and liquid level.

[0053] In a preferred embodiment, the control strategy of the present invention includes the following steps: During operation, a material balance calculation model oriented towards the target output is established, and feedforward control is achieved through parameters such as ammonia nitrogen concentration and CO2 concentration to pre-adjust the amount of reactants added. Meanwhile, real-time feedback of parameters such as pH in the reactor, NH3 / CO2 concentration in the tail gas, and reaction temperature is used to dynamically correct the molar ratio of CO2 to alkalized biogas slurry, ensuring accurate ratio of reactants and optimized absorption and conversion efficiency.

[0054] Control strategies are key to achieving stable, efficient, and economical system operation. They can cope with fluctuations in raw materials and changes in reaction conditions, maximize product yield, and minimize energy consumption and ammonia escape, thereby improving the overall reliability and automation level of the process and greatly reducing operating costs.

[0055] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0056] Example 1 A system for the synergistic preparation of ammonium bicarbonate based on alkalized biogas slurry and aerobic digestion of CO2 includes a CO2 gas supply and pretreatment unit, a biogas slurry pretreatment and alkalization unit, an ammonium bicarbonate synthesis reactor, an ammonium bicarbonate post-treatment unit, and a control and monitoring unit. The CO2 gas supply and pretreatment unit is used to supply CO2 from aerobic digestion and pretreat CO2 from aerobic digestion to obtain pretreated CO2 gas, which is then transported to the ammonium bicarbonate synthesis reactor. Specifically, the CO2 gas supply and pretreatment unit includes, in sequence, an aerobic digestion reactor, a gas dust collector, a gas condenser and dehumidifier, a gas desulfurization tower, and a gas transmission pipeline, according to the gas flow order. The biogas slurry pretreatment and alkalization unit is used to pretreat the raw biogas slurry to form clarified biogas slurry and alkalize the clarified biogas slurry to obtain alkalized biogas slurry, which is then transported to the ammonium bicarbonate synthesis reactor. Specifically, the biogas slurry pretreatment and alkalization unit includes, in sequence, a biogas slurry storage tank, a biogas slurry solid-liquid separation device, an alkalization reactor, and an alkalization biogas slurry delivery pump; at the same time, the biogas slurry pretreatment and alkalization unit is equipped with an alkali agent addition device for adding alkali agent to the alkalization reactor. The ammonium bicarbonate synthesis reactor is used to achieve CO2 absorption through gas-liquid mass transfer of pretreated CO2 gas, react with alkaline biogas slurry to synthesize ammonium bicarbonate, and crystallize ammonium bicarbonate to obtain ammonium bicarbonate slurry, which is then transported to the ammonium bicarbonate post-treatment unit. Specifically, the ammonium bicarbonate synthesis reactor adopts a bubble tower or stirred tank reactor design with mechanical stirring. The main body is made of corrosion-resistant materials (304 / 316L stainless steel or anti-corrosion lining). A gas distributor (such as microporous aeration plate, porous pipe or high-efficiency gas nozzle) is provided at the bottom or lower part to uniformly introduce the pretreated CO2 gas into the liquid phase in the form of fine bubbles, thereby increasing the contact area. The ammonium bicarbonate synthesis reactor is equipped with a stirring device (such as a multi-layer turbine or propeller-type stirring paddle) to enhance gas-liquid mass transfer and solid-liquid suspension, prevent crystal precipitation and caking, and is also equipped with a cooling jacket / coil to introduce cooling water to remove the heat of reaction and control the reaction temperature. In addition, temperature sensors, pH sensors and liquid level sensors are installed to monitor and control the reaction conditions in real time. The ammonium bicarbonate synthesis reactor has a crystal slurry outlet at the bottom or lower side to discharge the slurry containing ammonium bicarbonate crystals, and a tail gas outlet at the top to discharge unreacted CO2, inert gas and a small amount of NH3 that may escape. The ammonium bicarbonate post-processing unit is used to perform solid-liquid separation and product washing of ammonium bicarbonate slurry to obtain ammonium bicarbonate product. Specifically, the ammonium bicarbonate post-treatment unit includes, in sequence, an ammonium bicarbonate crystal slurry transfer pump, a solid-liquid separator, a crystal washing assembly, and a low-temperature dryer, according to the order in which the ammonium bicarbonate crystal slurry passes through. The solid-liquid separator is equipped with a washing liquid spraying device to wash the ammonium bicarbonate crystals with a low-temperature (0-10℃) saturated ammonium bicarbonate aqueous solution or cold water. Furthermore, the ammonium bicarbonate post-treatment unit is equipped with a mother liquor collection tank to collect the mother liquor and washing waste liquid discharged from the solid-liquid separator. The control and monitoring unit uses DCS or PLC to integrate and control each unit in the system. Based on material balance feedforward and online feedback of pH, tail gas NH3 / CO2, and temperature, it dynamically adjusts the supply of CO2 and alkaline biogas slurry and their molar ratio, thereby optimizing CO2 absorption and NH3 conversion efficiency.

[0057] Example 2 The only difference between this embodiment and Embodiment 1 is that the system is further provided with a mother liquor and tail gas treatment unit, which is used to treat the collected liquid in the mother liquor collection tank and to treat the tail gas discharged from the ammonium bicarbonate synthesis reactor. The collected liquid in the mother liquor collection tank contains unreacted ammonia, residual ammonium bicarbonate, organic matter and inorganic salts from the biogas slurry. It can be partially reused for dilution or alkalization adjustment in biogas slurry pretreatment (the risk of impurity accumulation needs to be assessed), or for nitrogen and phosphorus recovery (such as the recovery of residual phosphorus and ammonia by struvite precipitation), or for biochemical treatment (such as anaerobic + aerobic) to meet discharge standards or for farmland irrigation (the salt and heavy metal content needs to be assessed), or concentrated and used as raw material for liquid organic-inorganic compound fertilizer. The main components of the exhaust gas from the ammonium bicarbonate synthesis reactor are unreacted CO2, N2, O2, and a small amount of NH3 that may be entrained. It can be discharged externally or fed into the exhaust gas recirculation device. NH3 can be absorbed and recovered by an acid washing tower (such as dilute sulfuric acid washing) to generate ammonium sulfate. If the CO2 concentration in the exhaust gas is high, part of the exhaust gas can be returned to the CO2 pretreatment unit. Everything else is the same as in Example 1.

[0058] Example 3 This embodiment describes the system operation method of Embodiment 2, including the following steps: S1: The CO2-rich gas produced by the aerobic digestion of kitchen waste is sequentially treated by dust removal, condensation and dehumidification and desulfurization in the CO2 gas supply and pretreatment unit, and then introduced into the ammonium bicarbonate synthesis reactor. S2: The original biogas slurry is stored and separated from solids to achieve SS < 1-5 g / L. Alkali is added to the alkalization reactor to make the pH of the biogas slurry reach 9.5-10.5, and the alkalized biogas slurry is obtained and sent to the reactor. S3: Pretreated CO2 is introduced into the reactor through a gas distributor and CO2 absorption, reaction and crystallization are carried out at 10℃-30℃ under stirring and cooling conditions to obtain ammonium bicarbonate slurry. S4: The ammonium bicarbonate slurry is subjected to solid-liquid separation and washed with a saturated ammonium bicarbonate aqueous solution or cold water at 0-10℃. Then, it is dried at a low temperature not higher than 35℃-40℃ to obtain the ammonium bicarbonate product. S5: Acid wash the tail gas generated by the reactor to recover NH3, and return part of the treated CO2-containing gas to the CO2 pretreatment inlet as needed; Collect and reuse or treat the mother liquor in accordance with standards; Specifically, the process flow is as follows: Figure 1 As shown: CO2 gas sources and collection: Food waste undergoes aerobic fermentation in a closed aerobic digester, producing a mixed gas containing high concentrations of CO2 (10%-40% vol), O2, N2, water vapor, and small amounts of volatile organic compounds (VOCs), hydrogen sulfide (H2S), and other impurities. CO2 gas pretreatment: Dust removal: The collected high-temperature and high-humidity gas first enters a gas dust collector such as a cyclone separator or a bag filter. The cyclone separator uses the centrifugal force generated by the rotation of the airflow to separate solid particles, while the bag filter intercepts dust in the gas through filter bags, thereby removing solid particles from the gas and preventing blockage of subsequent equipment and contamination of products. Condensation and dehumidification: After dust removal, the gas enters a gas condensation dehumidifier, such as a shell-and-tube condenser or a plate heat exchanger, and cooling water is introduced. The gas exchanges heat with the low-temperature cooling medium, and the temperature decreases, causing most of the water vapor in the gas to condense into liquid water and be discharged, thus reducing the gas humidity. At the same time, the gas temperature is lowered to close to the temperature required for subsequent reactions (such as 20-40℃), which helps to improve the efficiency of subsequent CO2 absorption and reduce side reactions. Desulfurization: After condensation and cooling, the gas enters the gas desulfurization tower and is desulfurized by dry method (such as iron oxide desulfurizing agent) or wet method (such as alkaline washing tower). Taking dry iron oxide desulfurization as an example, the tower is filled with iron oxide desulfurizing agent. H2S reacts with iron oxide to form iron sulfide and is removed. This can prevent sulfide impurities from being mixed into the subsequent ammonium carbonate products and protect the equipment from corrosion. CO2 gas transportation: The CO2 gas (pure CO2 gas) after pretreatment (dust removal, dehumidification, desulfurization) is transported to the subsequent ammonium bicarbonate synthesis reactor through the pretreated CO2 gas transportation pipeline (powered by a fan or compressor); Biogas slurry sources and storage: The biogas slurry produced by anaerobic digestion (such as anaerobic fermentation of organic wastes such as kitchen waste and livestock and poultry manure) is first pumped into a biogas slurry storage tank for temporary storage and buffering. Biogas slurry solid-liquid separation: The raw biogas slurry is pumped out of the storage tank and enters the biogas slurry solid-liquid separation device. It adopts multi-stage treatment, such as first passing it through a grid or screen (pore size 5-10mm) to remove large suspended solids, and then entering a sedimentation tank or air flotation device to remove most of the fine suspended solids (SS). The goal is to obtain relatively clear biogas slurry with low SS content (e.g., <1-5 g / L) to reduce the adverse effects on subsequent reactions, crystallization and product purity. Alkalization of biogas slurry: The pretreated biogas slurry enters an alkalization reactor equipped with a stirring device. The reactor is equipped with an alkali inlet, a pH sensor (for online monitoring), a temperature sensor, and a discharge outlet. Alkali is precisely added to the alkalization reactor through an alkali addition device (such as an alkali storage tank and a metering pump). The amount of alkali added is controlled based on the reading of the online pH sensor. The biogas slurry contains NH4+. + Most of the ammonia nitrogen in its original form is converted into free NH3(aq), and free ammonia reacts more readily with CO2; CO2 absorption and ammonium bicarbonate synthesis: Alkaline biogas slurry (rich in free NH3) is continuously or intermittently added from the top or middle of the ammonium bicarbonate synthesis reactor. Pretreated CO2 gas is introduced from the bottom of the reactor through a gas distributor. Under stirring conditions, the CO2 gas is fully dispersed and absorbed in the alkaline biogas slurry, and reacts with dissolved free ammonia and water. When the concentration of NH4HCO3 in the solution reaches supersaturation, crystals will precipitate out, resulting in a slurry containing ammonium bicarbonate crystals. Ammonium bicarbonate solid-liquid separation and product washing: The slurry containing ammonium bicarbonate crystals is pumped to a solid-liquid separator by an ammonium bicarbonate crystal slurry transfer pump. The solid-liquid separator can be a scraper discharge centrifuge, a piston pusher centrifuge, or a vacuum belt filter. The solid-liquid separator is equipped with a washing liquid spraying device to wash the crystals. The separated mother liquor enters a mother liquor collection tank. The washed wet ammonium bicarbonate crystals are sent to a low-temperature dryer through a wet ammonium bicarbonate conveying device (such as a screw conveyor or scraper conveyor). The low-temperature dryer can be an airflow dryer (hot air temperature controlled at 35-40℃ and below), a vacuum rake dryer, or a low-temperature belt dryer. The dried product is collected from the dried ammonium bicarbonate product outlet. During or after separation, a small amount of low-temperature (e.g., 0-10°C) saturated ammonium bicarbonate aqueous solution or a small amount of pure cold water is sprayed onto the crystal surface through a washing liquid spraying device. The purpose is to remove mother liquor impurities adhering to the crystal surface and improve product purity. Under conditions below the significant decomposition temperature of ammonium bicarbonate (<35°C), free water and some attached water in the crystals are removed by hot air convection, vacuum dehumidification or a combination thereof, so that the moisture content of the product is reduced to 1-2% to improve its storage stability. Mother liquor treatment: The mother liquor discharged from the solid-liquid separator is collected in a mother liquor collection tank and then sent to the mother liquor treatment unit. The mother liquor contains unreacted ammonia, residual ammonium bicarbonate, organic matter and inorganic salts from the biogas slurry. It can be partially reused for dilution or alkalization adjustment in biogas slurry pretreatment (the risk of impurity accumulation needs to be assessed), nitrogen and phosphorus can be recovered (such as the recovery of residual phosphorus and ammonia by struvite precipitation), and it can be biochemically treated (such as anaerobic + aerobic) to meet discharge standards or for farmland irrigation (the salt and heavy metal content needs to be assessed). It can also be concentrated and used as a raw material for liquid organic-inorganic compound fertilizer. Tail gas treatment: The main components of the tail gas discharged from the ammonium bicarbonate synthesis reactor are unreacted CO2, N2, O2 and a small amount of NH3 that may be entrained. After evaluation, it is considered to discharge it externally or to introduce it into the tail gas recirculation device. NH3 is absorbed and recovered using an acid washing tower (such as dilute sulfuric acid washing) to generate ammonium sulfate; the treated gas is mainly CO2, N2 and O2, and depending on the CO2 concentration, a portion can be recycled back to the inlet of the CO2 pretreatment unit (the issue of inert gas accumulation needs to be assessed) or discharged in compliance with standards. In addition, during operation, a material balance calculation model oriented towards the target output is established, and feedforward control is achieved through parameters such as ammonia nitrogen concentration and CO2 concentration to pre-adjust the amount of reactants added; supplemented by real-time feedback of parameters such as pH in the reactor, NH3 / CO2 concentration in the tail gas, and reaction temperature, the molar ratio of CO2 to alkalized biogas slurry is dynamically corrected to ensure accurate ratio of reactants and optimized absorption and conversion efficiency.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for the production of ammonium bicarbonate based on the cooperation of alkalized biogas slurry and aerobic digestion of CO2, characterized by, The system comprises a CO2 gas supply and pretreatment unit, a biogas slurry pretreatment and alkalization unit, an ammonium bicarbonate synthesis reactor, an ammonium bicarbonate post-treatment unit, and a control and monitoring unit. The CO2 gas supply and pretreatment unit is configured to supply aerobic digestion CO2 and pretreat the aerobic digestion CO2 to obtain pretreated CO2 gas and deliver the pretreated CO2 gas to the ammonium bicarbonate synthesis reactor. The biogas slurry pretreatment and alkalization unit is configured to pretreat raw biogas slurry to form clarified biogas slurry and alkalize the clarified biogas slurry to obtain alkalized biogas slurry and deliver the alkalized biogas slurry to the ammonium bicarbonate synthesis reactor. The ammonium bicarbonate synthesis reactor is configured to cause the pretreated CO2 gas to perform gas-liquid mass transfer to realize CO2 absorption, react with the alkalized biogas slurry to synthesize ammonium bicarbonate, and cause the ammonium bicarbonate to crystallize and precipitate to obtain ammonium bicarbonate crystal slurry and deliver the ammonium bicarbonate crystal slurry to the ammonium bicarbonate post-treatment unit. The ammonium bicarbonate post-treatment unit is configured to cause the ammonium bicarbonate crystal slurry to perform solid-liquid separation and product washing to obtain ammonium bicarbonate product. The control and monitoring unit is configured to perform integrated control on each unit in the system by using DCS or PLC, and dynamically adjust the supply amounts of CO2 and alkalized biogas slurry and their molar ratio based on material balance feedforward and online feedback of pH, tail gas NH3 / CO2, and temperature, so as to optimize CO2 absorption and NH3 conversion efficiency.

2. The system of claim 1, wherein, The CO2 gas supply and pretreatment unit comprises, in sequence according to gas passing order, an aerobic digestion reactor, a gas dust remover, a gas condensation dehumidifier, a gas desulfurization tower, and a gas delivery pipeline.

3. The system of claim 1, wherein, The biogas slurry pretreatment and alkalization unit comprises, in sequence according to biogas slurry passing order, a biogas slurry storage tank, a biogas slurry solid-liquid separation device, an alkalization reactor, and an alkalized biogas slurry delivery pump. Preferably, the biogas slurry pretreatment and alkalization unit is provided with an alkali agent adding device configured to add alkali agent to the alkalization reactor. Preferably, the biogas slurry pretreatment and alkalization unit causes raw biogas slurry to be solid-liquid separated to suspended solids SS < 1-5 g / L and alkalized to pH 9.5-10.5, and then delivered to the ammonium bicarbonate synthesis reactor.

4. The system according to any one of claims 1-3, characterized in that, The ammonium bicarbonate synthesis reactor is provided with a gas distributor configured to uniformly introduce CO2 gas in the form of bubbles into liquid phase. Preferably, the gas distributor comprises at least one of a microporous aeration plate, a porous pipe, and a high-efficiency gas nozzle.

5. The system of claim 4, wherein, The ammonium bicarbonate synthesis reactor is provided with a stirring device configured to strengthen gas-liquid mass transfer and solid-liquid suspension, and prevent crystal settlement and caking. Preferably, the stirring device adopts a multi-layer turbine type or propelling type stirring paddle. Preferably, the ammonium bicarbonate synthesis reactor is provided with a cooling device configured to remove reaction heat and control reaction temperature. Preferably, the ammonium bicarbonate synthesis reactor is provided with a temperature sensor, a pH sensor, and a liquid level sensor configured to monitor and control reaction conditions in real time.

6. The system of any one of claims 1-3, wherein, The ammonium bicarbonate post-treatment unit comprises, in sequence according to ammonium bicarbonate crystal slurry passing order, an ammonium bicarbonate crystal slurry delivery pump, a solid-liquid separator, a crystal washing assembly, and a low-temperature dryer. Preferably, the solid-liquid separator is provided with a washing liquid spraying device configured to spray 0-10℃ saturated ammonium bicarbonate aqueous solution or cold water on ammonium bicarbonate crystals for low-temperature washing. Preferably, the drying temperature of the low-temperature dryer is not higher than 35-40℃, so as to prevent the thermal decomposition of ammonium bicarbonate; Preferably, the ammonium bicarbonate post-processing unit is provided with a mother liquor collecting tank for collecting the mother liquor and the washing waste liquid discharged from the solid-liquid separator; Preferably, the collected mother liquor is reused for dilution or alkalization adjustment of the biogas slurry pretreatment, and / or is subjected to nitrogen and phosphorus recovery or biochemical treatment.

7. The system of claim 6, wherein, The system is provided with a mother liquor and tail gas treatment unit for treating the collected liquid in the mother liquor collecting tank and for treating the tail gas discharged from the ammonium bicarbonate synthesis reactor. Preferably, the tail gas is treated by acid washing. Preferably, the acid washing uses dilute sulfuric acid, and the product obtained is ammonium sulfate.

8. A method of operating a system as claimed in any one of claims 1 to 7, characterised in that, The method comprises the following steps: S1: The CO2-rich gas generated by aerobic digestion of kitchen waste is subjected to dust removal, condensation and dehumidification, and desulfurization treatment in sequence through a CO2 gas supply and pretreatment unit, and is introduced into an ammonium bicarbonate synthesis reactor; S2: The raw biogas slurry is stored and subjected to solid-liquid separation to obtain a slurry with SS of less than 1-5g / L, an alkaline agent is added into an alkalization reactor to make the pH of the biogas slurry reach 9.5-10.5, and an alkalized biogas slurry is obtained and is sent into the reactor; S3: The pretreated CO2 is introduced into the ammonium bicarbonate synthesis reactor through a gas distributor, and CO2 absorption, reaction and crystallization are carried out under stirring and cooling conditions at 10-30℃, so as to obtain ammonium bicarbonate crystal slurry; S4: The ammonium bicarbonate crystal slurry is subjected to solid-liquid separation, and the crystals are washed using 0-10℃ saturated ammonium bicarbonate aqueous solution or cold water, and then low-temperature drying is carried out at a temperature of not higher than 35-40℃, so as to obtain ammonium bicarbonate product; S5: The tail gas generated by the reactor is subjected to acid washing to recover NH3, and part of the treated CO2-containing gas is refluxed to the CO2 pretreatment inlet as needed; The mother liquor is collected and reused or is subjected to resourceization / standard treatment.

9. The method of operating of claim 8, wherein, The operation method further comprises the following steps: During operation, a material balance calculation model oriented to target output is established, and feedforward control is realized through parameters of ammonia nitrogen concentration and CO2 concentration, so as to pre-adjust the reactant addition amount; At the same time, real-time feedback of parameters of pH in the reactor, NH3 / CO2 concentration in the tail gas and reaction temperature is supplemented, so as to dynamically correct the molar ratio of CO2 to alkalized biogas slurry, so as to ensure accurate proportioning of reactants and optimize absorption conversion efficiency.

10. The method of operating of claim 8, wherein, The ammonium bicarbonate synthesis reactor is a bubbling tower or an agitated tank with mechanical stirring, the main body is made of corrosion-resistant material, and online monitoring of temperature, pH and liquid level is provided.

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