System and method for converting synthesis ammonia byproduct redundant gaseous carbon dioxide

Abstract

The invention discloses a system and a method for converting synthesis ammonia byproduct redundant gaseous carbon dioxide, and relates to the technical field of chemical raw material treatment, the system comprises the following components: a gaseous carbon dioxide collection and pretreatment module, a compression and deep purification module, a cold box purification and liquefaction module and a storage and sale module; by means of the gaseous carbon dioxide collection and pretreatment module, the compression and deep purification module and the cold box purification and liquefaction module, efficient conversion of redundant gaseous carbon dioxide of a synthesis ammonia byproduct is achieved, cooperative work of the pre-cooling heat exchanger, the buffer tank, the compressor and the desulfurization tower equipment is achieved, temperature and pressure fluctuation of the carbon dioxide is reduced, and energy consumption is reduced. According to the method, the carbon dioxide is recycled, sulfide impurities in the carbon dioxide are effectively removed, the purity of the carbon dioxide is improved, high-quality raw materials are provided for subsequent carbon dioxide liquefaction and sale through the efficient conversion and purification process, meanwhile, environmental pollution is reduced, and cyclic utilization of resources is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of chemical raw material processing, and in particular to a system and method for converting excess gaseous carbon dioxide produced as a by-product of synthetic ammonia. Background Art

[0002] In the chemical production process, synthetic ammonia units often produce a large amount of gaseous carbon dioxide as a by-product. If this carbon dioxide is not utilized, it will not only cause a waste of resources but may also have a negative impact on the environment.

[0003] Traditional technologies often have many shortcomings when dealing with excess gaseous carbon dioxide produced as a by-product of synthetic ammonia. On the one hand, the traditional technology is relatively simple in terms of the collection and pretreatment process of carbon dioxide, and lacks efficient pre-cooling and buffering devices, resulting in large fluctuations in the temperature and pressure of carbon dioxide, affecting the subsequent conversion effect. On the other hand, the purification process of traditional technologies is usually not thorough enough, and it is difficult to effectively remove sulfide impurities in carbon dioxide, resulting in low quality of the converted products that cannot meet market demand.

[0004] In summary, conventional technologies have many deficiencies in treating excess gaseous carbon dioxide produced as a byproduct of synthetic ammonia. Therefore, it is particularly important to develop a system and method for converting excess gaseous carbon dioxide produced as a byproduct of synthetic ammonia. Summary of the invention

[0005] The purpose of the present invention is to make up for the shortcomings of the prior art and to provide a system and method for converting excess gaseous carbon dioxide produced as a by-product of synthetic ammonia. The system can achieve efficient conversion and purification of carbon dioxide through the coordinated work of multiple modules, which not only improves the quality and purity of the product, but also ensures the stable operation of downstream production, and has important application value.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a system and method for converting excess gaseous carbon dioxide produced as a byproduct of synthetic ammonia, the system comprising the following components: a gaseous carbon dioxide collection and pretreatment module, a compression and deep purification module, a cold box purification and liquefaction module, and a storage and external sales module;

[0007] The gaseous carbon dioxide collection and pretreatment module is composed of an intake pipe, a precooling heat exchanger and a buffer tank connected in sequence. The intake pipe receives the excess gaseous carbon dioxide produced as a byproduct of synthetic ammonia. The precooling heat exchanger adopts a heat exchange algorithm, and the formula is Q = K × A × ΔT × f (P, T in ,T out ), where Q is the heat transfer, K is the comprehensive heat transfer coefficient, A is the heat transfer area, ΔT is the logarithmic mean temperature difference, and the inlet temperature T in and target precooling temperature T out It is calculated that f(P,T in ,Tout ) is a correction function for pressure and temperature effects, and the gaseous carbon dioxide is pre-cooled. The internal buffer structure of the buffer tank adopts a multi-layer elastic diaphragm structure, and the buffer space is adaptively adjusted according to the gas pressure fluctuation. The filtering device adopts a nanofiber composite filter;

[0008] The compression and deep purification module includes a compressor, a desulfurization tower, a cooler and a recooler. The compressor adopts an intelligent adaptive compression algorithm, and the formula is P out =P in ×(1+α×ln(V in / V out )+β×(T in -T ref )), where P out is the output pressure, P in is the input pressure, α and β are coefficients related to compressor performance, V in is the intake air flow rate, V out is the exhaust flow rate, T in is the intake air temperature, T ref The gas is pressurized to 2.5MPa as the reference temperature. The desulfurizer in the desulfurization tower adopts a composite metal oxide desulfurizer, and its active ingredient ratio is determined according to the sulfur content distribution in the synthetic ammonia process. Through a large number of experimental optimizations, the cooler and the recooler adopt a multi-stage cooling structure in series. The cooling temperature of each stage is determined by heat balance calculation according to the gas composition and subsequent process requirements. Circulating water and chilled brine are used for cooling to reduce the gas temperature to about 10°C.

[0009] The cold box purification and liquefaction module is composed of a cold box, a primary distillation tower, a primary condenser and a secondary condenser. A low-temperature distillation algorithm is used inside the cold box. The formula is: where y i is the mole fraction of component i in the gas phase, x i is the mole fraction of component i in the liquid phase, γ i is the activity coefficient of component i, ΔH vap,i is the enthalpy of evaporation of component i, R is the universal gas constant, T is the temperature, g(P sys ,x i ) is the system pressure and composition influencing function, the heavy components are discharged in the primary distillation tower, the primary condenser and the secondary condenser adopt a graded condensation strategy, the condensation temperature is determined according to the carbon dioxide liquefaction curve and the impurity separation requirements, and the carbon dioxide is liquefied by indirect heat exchange with the refrigerant;

[0010] The storage and sales module includes a secondary distillation tower, a recooler and a storage tank. The secondary distillation tower operates under specific temperature and pressure conditions. Its operating parameters are determined by phase equilibrium calculation based on the purity requirements of liquid carbon dioxide and the impurity composition. The residual light component impurities are further removed. The recooler adopts an optimized refrigeration cycle algorithm. The formula is: Where COP is the coefficient of refrigeration, Q e is the cooling capacity, W is the power consumption of the compressor, T e is the evaporation temperature, T c is the condensation temperature, P e is the evaporation pressure, P c is the condensation pressure, h(T e ,T c ,P e ,P c ) is a correction function that takes into account the coupling effect of pressure and temperature. Liquid carbon dioxide is recooled and sent to a storage tank for storage. When production needs are met, some food-grade carbon dioxide can be sold.

[0011] The emergency gasification and supply module includes a vaporizer, a pressure reducing device, a steam flow regulating valve and a one-button start control system. The vaporizer adopts a high-efficiency thermal conductivity gasification algorithm, and the formula is: Where m g is the mass flow rate of gaseous carbon dioxide produced by gasification, Q h For heating, the heat is provided by steam, L v is the latent heat of vaporization of carbon dioxide, k(P g ,T g ) is the pressure and temperature influence coefficient. Liquid carbon dioxide is gasified into gaseous carbon dioxide. The pressure reducing device adopts a two-stage pressure reducing structure. The first-stage pressure reducing ratio is determined by fluid mechanics calculation according to the vaporizer outlet pressure and the target supply pressure. The second-stage pressure reducing adopts a high-precision pressure regulating valve to set the pressure to 0.4MPa. The steam flow regulating valve is set according to the preset outlet flow range of 15000-20000m 3 / hour, the steam flow rate is automatically adjusted through the feedback control algorithm. The algorithm is dynamically adjusted based on flow deviation and temperature changes. The formula is where F v is the steam flow control valve opening F set is the opening corresponding to the preset flow rate, k p , k i , k d is the proportional, integral, and differential coefficient, k tis the temperature influence coefficient, ΔF is the deviation between the actual flow and the preset flow, ΔT is the temperature change, and the one-button start control system is hard-wired with the shutdown signal of the synthetic ammonia unit to achieve seamless start-up of the emergency gasification and supply process to ensure the joint alkali production. At the same time, an externally purchased liquid carbon dioxide tank truck unloading and filling device is set up, including an unloading pipeline, a filling pump and a safety interlock system. The unloading pipeline is made of low-temperature and high-pressure resistant materials. The filling pump flow is determined according to the storage tank capacity and replenishment needs. The safety interlock system ensures the safety and reliability of the unloading and filling process according to the pressure and liquid level parameters.

[0012] Furthermore, the low-temperature medium in the precooling heat exchanger is a low-temperature ethylene glycol aqueous solution from the refrigeration system, and its initial temperature is determined by heat exchange calculation according to the gaseous carbon dioxide inlet temperature and the precooling target temperature, ranging from -15°C to -5°C, and the refrigeration system adopts variable frequency control technology to automatically adjust the refrigeration power according to the heat load demand of the precooling heat exchanger. Its control algorithm is based on heat load feedback, and the formula is: Where P r is the actual power of the refrigeration system, P max is the maximum power of the refrigeration system, Q l is the real-time heat load of the precooling heat exchanger, Q max is the maximum design heat load of the precooling heat exchanger, f c (T e g,T set ) is the influence function of ethylene glycol aqueous solution temperature and set temperature, which is obtained by fitting experimental data and is used to optimize the power regulation of the refrigeration system.

[0013] Furthermore, the impellers of each stage of the compressor adopt a three-dimensional flow field optimization design. According to the principles of gas dynamics and actual operating conditions, the blade shape, inlet and outlet angles and flow channel structure of the impeller are determined through computational fluid dynamics simulation analysis to improve compression efficiency and reduce energy consumption. The compressor is equipped with an online monitoring system to monitor vibration, temperature and pressure parameters in real time. The monitoring data is transmitted to the central control system. When the parameters exceed the preset threshold, the central control system automatically adjusts the compressor operating parameters or issues a warning signal. The preset threshold is determined according to the safe operation specifications and performance characteristics of the compressor.

[0014] Furthermore, the composite metal oxide desulfurizer in the desulfurization tower is composed of copper oxide, zinc oxide and manganese oxide in a specific molar ratio ranging from 3:2:1 to 5:3:2. The ratio is determined by long-term monitoring and analysis of the sulfur content and form in the gaseous carbon dioxide produced as a by-product of synthetic ammonia, combined with the adsorption and reaction characteristics of different metal oxides to various sulfides. The desulfurizer is loaded in layers, and the height of each layer is determined by fluid mechanics calculation based on the tower diameter and gas flow rate to ensure uniform distribution and sufficient contact of the gas in the desulfurizer bed, thereby improving the desulfurization efficiency.

[0015] Furthermore, the primary distillation tower inside the cold box uses high-efficiency structured packing, the packing material is stainless steel wire mesh corrugated packing, and its specific surface area is determined by mass transfer calculation according to the separation requirements of carbon dioxide and impurity components, and the range is 500-1000m 2 / m 3 The number of plates of the distillation tower is determined by distillation calculation according to the feed composition, product purity requirements and operating pressure, and the range is 20-50. At the same time, the cold box is equipped with a low-temperature refrigeration cycle system, which uses a mixed refrigerant. Its composition is determined by refrigeration cycle simulation optimization according to the required refrigeration temperature and refrigeration capacity of the cold box to ensure the stability of the low-temperature environment in the cold box and meet the requirements of distillation and liquefaction processes.

[0016] Furthermore, the storage tank adopts a double-layer vacuum insulation structure. The inner layer is made of stainless steel with a thickness determined according to the storage tank capacity and pressure requirements, ranging from 8-15mm. The outer layer is made of carbon steel with a thickness of 6-10mm. The vacuum degree of the vacuum layer is maintained within the range of 0.1-1Pa by a vacuum pump, and the storage tank is equipped with liquid level, pressure and temperature monitoring devices. The monitoring data is transmitted to the central control system in real time. The central control system automatically controls the feeding, discharging and refrigeration system operation of the storage tank according to the data to ensure the storage safety and stable quality of liquid carbon dioxide in the storage tank.

[0017] Furthermore, the burner of the vaporizer adopts premixed combustion technology. The mixing ratio of fuel and air is determined by combustion experiments according to the combustion efficiency and flue gas temperature requirements, ranging from 1:10 to 1:15. The flame temperature of the burner is controlled by adjusting the fuel flow rate and air flow rate. The control algorithm is based on temperature feedback, and the formula is F f =F f0 +k fb ×(T set -T act ), where F f is the fuel flow rate, F f0 is the initial fuel flow rate, k fb is the temperature feedback coefficient, T set To set the flame temperature, T act The actual flame temperature ensures efficient gasification of liquid carbon dioxide while reducing harmful gas emissions.

[0018] Furthermore, the filling pump in the purchased liquid carbon dioxide tank truck unloading and filling device adopts a multi-stage centrifugal pump, and its head is determined by fluid mechanics calculation according to the storage tank height and the filling pipeline resistance, and the range is 30-50m. The safety interlock system includes a pressure sensor, a liquid level switch and an emergency shut-off valve. When the pressure in the storage tank exceeds the set upper limit or the liquid level exceeds the set upper limit, the emergency shut-off valve automatically closes and stops the filling operation to ensure the safety and reliability of the unloading and filling process. At the same time, the unloading and filling device is also equipped with a grounding protection device with a grounding resistance of less than 10Ω to prevent static electricity accumulation from causing safety accidents.

[0019] Furthermore, the one-button start control system adopts a redundant design, including a main controller and a backup controller. When the main controller fails, the backup controller automatically switches to operation to ensure the reliable start-up of the emergency gasification and supply process, and the control system interacts with the control system of the joint alkali production device to obtain the operating status and carbon dioxide demand information of the joint alkali production device in real time, and automatically adjusts the supply parameters of gaseous carbon dioxide according to demand to ensure the stable operation of the joint alkali production.

[0020] On the other hand, a method for converting excess gaseous carbon dioxide produced as a byproduct of synthetic ammonia is provided, characterized in that the method comprises the following specific steps:

[0021] S1. Collection and pretreatment of gaseous carbon dioxide: The excess gaseous carbon dioxide produced as a byproduct of synthetic ammonia enters the precooling heat exchanger through the air intake pipe. According to the heat exchange algorithm of the precooling heat exchanger, Q = K × A × ΔT × f (P, T in ,T out ) for pre-cooling, and then enters the buffer tank, where the multi-layer elastic diaphragm structure in the buffer tank buffers pressure fluctuations, and the nanofiber composite filter is used to initially separate impurities;

[0022] S2, Compression and deep purification: The gas flowing out of the buffer tank enters the compressor according to the intelligent adaptive compression algorithm P out =P in ×(1+α×ln(V in / V out )+β×(T in -T ref )) The gas is pressurized to 2.5MPa and then enters the desulfurization tower to fully react with the new composite metal oxide desulfurizer to remove sulfides. It then passes through the cooler and recooler in sequence, and uses a series of multi-stage cooling structures, circulating water, and frozen brine to reduce the gas temperature to about 10°C;

[0023] S3, cold box purification and liquefaction: The gas with a temperature of about 10°C enters the cold box, and is distilled in the cold box according to the cryogenic distillation algorithm. The heavy components are discharged in the primary distillation tower, and then the carbon dioxide is liquefied by indirect heat exchange with the refrigerant through a staged condensation strategy in the primary condenser and the secondary condenser;

[0024] S4. Storage and external sales: Liquid carbon dioxide enters the secondary distillation tower from the secondary condenser, further removes residual light component impurities under specific temperature and pressure conditions, and then enters the recooler according to the refrigeration cycle algorithm. After recooling, it is sent to the storage tank for storage. During the continuous and stable production period, part of the food-grade carbon dioxide is sold out according to the storage tank liquid level and market demand;

[0025] S5. Emergency gasification and supply: When the failure of the synthetic ammonia unit causes the interruption of the production of raw carbon dioxide in the alkali industry, the liquid carbon dioxide in the storage tank enters the vaporizer and is gasified according to the efficient heat conduction algorithm. Gasification into gaseous carbon dioxide, the pressure is set to 0.4MPa through a two-stage pressure reducing device, and the steam flow regulating valve is controlled according to the feedback control algorithm. Automatically adjust steam flow to control outlet flow at 15000-20000m 3 / hour, the one-button start control system starts the emergency gasification and supply process to ensure the joint alkali production. When the liquid carbon dioxide reserves in the storage tank are insufficient, it is replenished through the purchased liquid carbon dioxide tank truck unloading and filling device, and the filling pump is used to transport the liquid carbon dioxide in the tank truck to the storage tank. At the same time, the safety interlock system ensures the safety of the unloading and filling process.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The system achieves efficient conversion of excess gaseous carbon dioxide produced as a by-product of synthetic ammonia through multiple modules, including gaseous carbon dioxide collection and pretreatment, compression and deep purification, cold box purification and liquefaction. The coordinated work of the precooling heat exchanger, buffer tank, compressor and desulfurization tower equipment not only reduces the temperature and pressure fluctuations of carbon dioxide, but also effectively removes sulfide impurities and improves the purity of carbon dioxide. This efficient conversion and purification process provides high-quality raw materials for the subsequent liquefaction and sale of carbon dioxide, while also reducing environmental pollution and achieving resource recycling.

[0028] (2) The system is specially equipped with an emergency gasification and supply module, which includes a vaporizer, a pressure reducing device, a steam flow regulating valve and a one-button start control system. When a failure in the synthetic ammonia unit causes the interruption of the supply of raw carbon dioxide for the combined alkali production, the module can be quickly started to gasify the liquid carbon dioxide in the storage tank into gaseous carbon dioxide, and adjust its pressure and flow to meet the needs of combined alkali production. This emergency gasification and supply function not only ensures the stable operation of combined alkali production, but also avoids production stagnation and economic losses caused by raw material interruption. At the same time, the system is also equipped with an external liquid carbon dioxide tank truck unloading and filling device. When the liquid carbon dioxide reserve in the storage tank is insufficient, the raw material can be replenished in time to ensure the continuous operation of the system.

[0029] Other advantages, objectives and features of the present invention will be set forth in part in the following description and, in part, will be apparent to those skilled in the art based on an examination of the following or may be taught from the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 This is a process operation diagram of a system for converting excess gaseous carbon dioxide produced as a by-product of synthetic ammonia;

[0032] Figure 2 The present invention is a process operation diagram of a method for converting excess gaseous carbon dioxide produced as a by-product of synthetic ammonia. DETAILED DESCRIPTION

[0033] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation mode, structure, characteristics and effects of the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0034] Embodiment 1 :

[0035] This embodiment describes that a synthetic ammonia plant produces a large amount of by-product gaseous carbon dioxide during the production process. In order to achieve effective utilization of resources and reduce greenhouse gas emissions, the plant installed a synthetic ammonia by-product gaseous carbon dioxide conversion system.

[0036] The excess gaseous carbon dioxide produced as a byproduct of the synthetic ammonia unit enters the precooling heat exchanger through the air intake pipe. The low-temperature medium in the precooling heat exchanger is a low-temperature ethylene glycol aqueous solution from the refrigeration system. Its initial temperature is determined by heat exchange calculation based on the gaseous carbon dioxide inlet temperature and the precooling target temperature, ranging from -15°C to -5°C. The refrigeration system adopts variable frequency control technology to automatically adjust the refrigeration power according to the heat load demand of the precooling heat exchanger. The control algorithm is based on heat load feedback. The gaseous carbon dioxide in the precooling heat exchanger is based on the heat exchange algorithm Q=K×A×ΔT×f(P,T in ,T out ) for pre-cooling and then enters the buffer tank. The multi-layer elastic diaphragm structure inside the buffer tank adaptively adjusts the buffer space according to the gas pressure fluctuation, and its nanofiber composite filter preliminarily separates impurities.

[0037] The gas flowing out of the buffer tank enters the compressor. The impellers at all levels of the compressor adopt a three-dimensional flow field optimization design and are equipped with an online monitoring system to monitor vibration, temperature, and pressure parameters in real time. The gas is compressed according to the intelligent adaptive compression algorithm P out =P in ×(1+α×ln(V in / V out )+β×(T in -T ref )) is pressurized to 2.5MPa and then enters the desulfurization tower. The composite metal oxide desulfurizer in the desulfurization tower is composed of copper oxide, zinc oxide and manganese oxide in a molar ratio of 4:3:2. It is loaded in layers, and the height of each layer is determined by fluid mechanics calculation based on the tower diameter and gas flow rate. After the gas fully reacts with the desulfurizer to remove sulfides, it passes through the cooler and recooler in turn, and the gas temperature is reduced to about 10°C using a series of multi-stage cooling structures, circulating water and chilled brine.

[0038] The gas with a temperature of about 10°C enters the cold box. The primary distillation tower inside the cold box uses stainless steel wire mesh corrugated packing with a specific surface area of ​​800m 2 / m 3 The number of plates is 35. According to the low temperature distillation algorithm in the cold box The heavy components are discharged in the primary distillation tower, and then the carbon dioxide is liquefied by indirect heat exchange with the refrigerant through a staged condensation strategy in the primary condenser and the secondary condenser.

[0039] Liquid carbon dioxide enters the secondary distillation tower from the secondary condenser to further remove residual light component impurities under specific temperature and pressure conditions, and then enters the recooler. After re-cooling, it is sent to the storage tank for storage. The storage tank adopts a double-layer vacuum insulation structure. The inner layer of stainless steel is 12mm thick and the outer layer of carbon steel is 8mm thick. The vacuum degree of the vacuum layer is maintained at 0.1-1Pa. It is equipped with liquid level, pressure and temperature monitoring devices. The monitoring data is transmitted to the central control system in real time. The central control system automatically controls the feeding, discharging and refrigeration system operation of the storage tank according to the data. During the continuous and stable production period, some food-grade carbon dioxide is sold according to the storage tank liquid level and market demand.

[0040] When the failure of the synthetic ammonia unit causes the interruption of the production of raw carbon dioxide in the alkali process, the liquid carbon dioxide in the storage tank enters the vaporizer. The burner of the vaporizer adopts premixed combustion technology, and the fuel-air mixing ratio is 1:12. The burner flame temperature is controlled by adjusting the fuel flow and air flow. The control algorithm is based on temperature feedback. The liquid carbon dioxide is removed in the vaporizer according to the efficient heat conduction gasification algorithm. Gasification into gaseous carbon dioxide, the pressure is set to 0.4MPa through a two-stage pressure reducing device, and the steam flow regulating valve is controlled according to the feedback control algorithm. Automatically adjust steam flow to control outlet flow at 15000-20000m 3 / hour, the one-button start control system starts the emergency gasification and supply process to ensure the joint alkali production. When the liquid carbon dioxide reserves in the storage tank are insufficient, it is supplemented by purchasing a liquid carbon dioxide tank truck unloading and filling device. The filling pump adopts a multi-stage centrifugal pump with a head of 40m to transport the liquid carbon dioxide in the tank truck to the storage tank. The safety interlock system ensures the safety of the unloading and filling process.

[0041] Embodiment 2 :

[0042] This embodiment describes that in a large-scale synthetic ammonia plant, the daily production process will produce excess gaseous carbon dioxide as a by-product. The plant is equipped with a complete carbon dioxide conversion system to achieve effective treatment and utilization of this part of carbon dioxide.

[0043] The excess gaseous carbon dioxide produced as a byproduct of the synthetic ammonia unit enters the precooling heat exchanger through the air intake pipe. The air intake temperature is 30°C, the target precooling temperature is set to 5°C, and the low-temperature medium in the precooling heat exchanger is a low-temperature ethylene glycol aqueous solution at -10°C (determined by heat exchange calculation). According to the heat exchange algorithm, the formula is Q = K × A × ΔT × f (P, T in ,T out ), where Q is the heat transfer, K is the comprehensive heat transfer coefficient, A is the heat transfer area, ΔT is the logarithmic mean temperature difference, and the inlet temperature T in and target precooling temperature T out It is calculated that f(P,T in ,T out) is the correction function for pressure and temperature effects. The heat exchange capacity is calculated and pre-cooling is performed. The pre-cooled carbon dioxide enters the buffer tank. The multi-layer elastic diaphragm structure in the buffer tank effectively buffers the gas pressure fluctuations, and the nanofiber composite filter preliminarily separates some impurities.

[0044] The gas flowing out of the buffer tank enters the compressor. The intake pressure of the compressor is 0.1MPa and the intake flow rate is 5000m 3 / h, the intake temperature is 5℃, the reference temperature is 25℃, and the intelligent adaptive compression algorithm is used. The formula is P out =P in ×(1+α×ln(V in / V out )+β×(T in -T ref )), where P out is the output pressure, P in is the input pressure, α and β are coefficients related to compressor performance, V in is the intake air flow rate, V out is the exhaust flow rate, T in is the intake air temperature, T ref For reference temperature, the compressor pressurizes the gas to 2.5MPa, and the pressurized gas enters the desulfurization tower. The composite metal oxide desulfurizer (copper oxide, zinc oxide and manganese oxide in a molar ratio of 4:3:2) loaded in the desulfurization tower fully reacts with the gas to remove sulfides. The gas then passes through the cooler and recooler in sequence, using a multi-stage cooling structure in series. The cooling temperature of each stage is set according to the gas composition and subsequent process requirements, and the gas temperature is reduced to about 10°C through circulating water and chilled brine.

[0045] The gas with a temperature of about 10°C enters the cold box. The primary distillation tower in the cold box uses high-efficiency structured packing (stainless steel wire mesh corrugated packing with a specific surface area of ​​800m 2 / m 3 , the number of plates is 30), according to the cryogenic distillation algorithm, the formula is where y i is the mole fraction of component i in the gas phase, x i is the mole fraction of component i in the liquid phase, γ i is the activity coefficient of component i, ΔH vap,i is the enthalpy of evaporation of component i, R is the universal gas constant, T is the temperature, g(P sys ,x i ) is the system pressure and composition influencing function. The heavy components are discharged in the primary distillation tower, and then in the primary condenser and the secondary condenser, the condensation temperature is set according to the carbon dioxide liquefaction curve and impurity separation requirements according to the graded condensation strategy, and the carbon dioxide is liquefied by indirect heat exchange with the refrigerant.

[0046] Liquid carbon dioxide enters the secondary distillation tower from the secondary condenser, further removes residual light component impurities under specific temperature and pressure conditions (determined by phase equilibrium calculation), and then enters the recooler. The recooler is based on the refrigeration cycle algorithm, and the formula is Where COP is the coefficient of refrigeration, Q e is the cooling capacity, W is the power consumption of the compressor, T e is the evaporation temperature, T c is the condensation temperature, P e is the evaporation pressure, P c is the condensation pressure, h(T e ,T c ,P e ,P c ) is a correction function that takes into account the coupling effects of pressure and temperature. The liquid carbon dioxide is cooled again and then sent to the storage tank for storage. The storage tank adopts a double-layer vacuum insulation structure (the inner layer of stainless steel is 10mm thick, the outer layer of carbon steel is 8mm thick, and the vacuum degree is maintained at 0.5Pa) and is equipped with liquid level, pressure and temperature monitoring devices. The data is transmitted to the central control system in real time. During continuous and stable production, some food-grade carbon dioxide is sold according to the storage tank liquid level and market demand.

[0047] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A system for converting excess gaseous carbon dioxide produced as a byproduct of synthetic ammonia, characterized in that: The system includes a gaseous carbon dioxide collection and pretreatment module, a compression and deep purification module, a cold box purification and liquefaction module, and a storage and sales module: The gaseous carbon dioxide collection and pretreatment module is composed of an intake pipe, a precooling heat exchanger and a buffer tank connected in sequence. The intake pipe receives the excess gaseous carbon dioxide produced as a byproduct of synthetic ammonia. The precooling heat exchanger adopts a heat exchange algorithm, and the formula is Q = K × A × ΔT × f (P, T in ,T out ), where Q is the heat transfer, K is the comprehensive heat transfer coefficient, A is the heat transfer area, ΔT is the logarithmic mean temperature difference, and the inlet temperature T in and target precooling temperature T out It is calculated that f(P,T in ,T out ) is a correction function for pressure and temperature effects, and the gaseous carbon dioxide is pre-cooled. The internal buffer structure of the buffer tank adopts a multi-layer elastic diaphragm structure, and the buffer space is adaptively adjusted according to the gas pressure fluctuation. The filtering device adopts a nanofiber composite filter; The compression and deep purification module includes a compressor, a desulfurization tower, a cooler and a recooler. The compressor adopts an intelligent adaptive compression algorithm, and the formula is P out =P in ×(1+α×ln(V in / V out )+β×(T in -T ref )), where P out is the output pressure, P in is the input pressure, α and β are coefficients related to compressor performance, V in is the intake air flow rate, V out is the exhaust flow rate, T in is the intake air temperature, T ref The gas is pressurized to 2.5MPa as the reference temperature. The desulfurizer in the desulfurization tower adopts a composite metal oxide desulfurizer, and its active ingredient ratio is determined according to the sulfur content distribution in the synthetic ammonia process. Through a large number of experimental optimizations, the cooler and the recooler adopt a multi-stage cooling structure in series. The cooling temperature of each stage is determined by heat balance calculation according to the gas composition and subsequent process requirements. Circulating water and chilled brine are used for cooling to reduce the gas temperature to about 10°C. The cold box purification and liquefaction module is composed of a cold box, a primary distillation tower, a primary condenser and a secondary condenser. A low-temperature distillation algorithm is used inside the cold box. The formula is: where y i is the mole fraction of component i in the gas phase, x i is the mole fraction of component i in the liquid phase, γ i is the activity coefficient of component i, ΔH vap,i is the enthalpy of evaporation of component i, R is the universal gas constant, T is the temperature, g(P sys ,x i ) is the system pressure and composition influencing function, the heavy components are discharged in the primary distillation tower, the primary condenser and the secondary condenser adopt a graded condensation strategy, the condensation temperature is determined according to the carbon dioxide liquefaction curve and the impurity separation requirements, and the carbon dioxide is liquefied by indirect heat exchange with the refrigerant; The storage and sales module includes a secondary distillation tower, a recooler and a storage tank. The secondary distillation tower operates under specific temperature and pressure conditions. Its operating parameters are determined by phase equilibrium calculation based on the purity requirements of liquid carbon dioxide and the impurity composition. The residual light component impurities are further removed. The recooler adopts an optimized refrigeration cycle algorithm. The formula is: Where COP is the coefficient of refrigeration, Q e is the cooling capacity, W is the power consumption of the compressor, T e is the evaporation temperature, T c is the condensation temperature, P e is the evaporation pressure, P c is the condensation pressure, h(T e ,T c ,P e ,P c ) is a correction function that takes into account the coupling effect of pressure and temperature. Liquid carbon dioxide is recooled and sent to a storage tank for storage. When production needs are met, some food-grade carbon dioxide can be sold. The emergency gasification and supply module includes a vaporizer, a pressure reducing device, a steam flow regulating valve and a one-button start control system. The vaporizer adopts a high-efficiency thermal conductivity gasification algorithm, and the formula is: Where m g is the mass flow rate of gaseous carbon dioxide produced by gasification, Q h For heating, the heat is provided by steam, L v is the latent heat of vaporization of carbon dioxide, k(P g ,T g ) is the pressure and temperature influence coefficient. Liquid carbon dioxide is gasified into gaseous carbon dioxide. The pressure reducing device adopts a two-stage pressure reducing structure. The first-stage pressure reducing ratio is determined by fluid mechanics calculation according to the vaporizer outlet pressure and the target supply pressure. The second-stage pressure reducing adopts a high-precision pressure regulating valve to set the pressure to 0.4MPa. The steam flow regulating valve is set according to the preset outlet flow range of 15000-20000m 3 / hour, the steam flow rate is automatically adjusted through the feedback control algorithm. The algorithm is dynamically adjusted based on flow deviation and temperature changes. The formula is where F v is the steam flow control valve opening F set is the opening corresponding to the preset flow rate, k p , k i , k d is the proportional, integral, and differential coefficient, k t is the temperature influence coefficient, ΔF is the deviation between the actual flow and the preset flow, ΔT is the temperature change, and the one-button start control system is hard-wired with the shutdown signal of the synthetic ammonia unit to achieve seamless start-up of the emergency gasification and supply process to ensure the joint alkali production. At the same time, an externally purchased liquid carbon dioxide tank truck unloading and filling device is set up, including an unloading pipeline, a filling pump and a safety interlock system. The unloading pipeline is made of low-temperature and high-pressure resistant materials. The filling pump flow is determined according to the storage tank capacity and replenishment needs. The safety interlock system ensures the safety and reliability of the unloading and filling process according to the pressure and liquid level parameters.

2. A system for converting excess gaseous carbon dioxide produced as a byproduct of synthetic ammonia according to claim 1, characterized in that: The low-temperature medium in the precooling heat exchanger is a low-temperature ethylene glycol aqueous solution from the refrigeration system, and its initial temperature is determined by heat exchange calculation according to the gaseous carbon dioxide inlet temperature and the precooling target temperature, ranging from -15°C to -5°C. The refrigeration system adopts frequency conversion control technology to automatically adjust the refrigeration power according to the heat load demand of the precooling heat exchanger. Its control algorithm is based on heat load feedback, and the formula is: Where P r is the actual power of the refrigeration system, P max is the maximum power of the refrigeration system, Q l is the real-time heat load of the precooling heat exchanger, Q max is the maximum design heat load of the precooling heat exchanger, f c (T e g,T set ) is the influence function of ethylene glycol aqueous solution temperature and set temperature.

3. A system for converting excess gaseous carbon dioxide produced as a byproduct of synthetic ammonia according to claim 1, characterized in that: The impellers of each stage of the compressor are designed with a three-dimensional flow field optimization. The blade shape, inlet and outlet angles and flow channel structure of the impeller are determined through computational fluid dynamics simulation analysis based on the principles of gas dynamics and actual operating conditions. The compressor is equipped with an online monitoring system to monitor vibration, temperature and pressure parameters in real time. The monitoring data is transmitted to the central control system. When the parameters exceed the preset threshold, the central control system automatically adjusts the compressor operating parameters or issues a warning signal. The preset threshold is determined based on the safe operating specifications and performance characteristics of the compressor.

4. A system for converting excess gaseous carbon dioxide produced as a byproduct of synthetic ammonia according to claim 1, characterized in that: The composite metal oxide desulfurizer in the desulfurization tower is composed of copper oxide, zinc oxide and manganese oxide in a specific molar ratio, and the molar ratio ranges from 3:2:1 to 5:3:

2. The ratio is determined by long-term monitoring and analysis of the sulfur content and form in the gaseous carbon dioxide by-product of synthetic ammonia, combined with the adsorption and reaction characteristics of different metal oxides to various sulfides. The desulfurizer is loaded in layers, and the loading height of each layer is determined by fluid mechanics calculation based on the tower diameter and the gas flow rate.

5. The system for converting excess gaseous carbon dioxide produced as a byproduct of synthetic ammonia according to claim 1, characterized in that: The primary distillation tower inside the cold box uses high-efficiency structured packing, and the packing material is stainless steel wire mesh corrugated packing. The specific surface area is determined by mass transfer calculation according to the separation requirements of carbon dioxide and impurity components, and the range is 500-1000m 2 / m 3 The number of plates of the distillation tower is determined by distillation calculation according to the feed composition, product purity requirements and operating pressure, and the range is 20-50. At the same time, the cold box is equipped with a low-temperature refrigeration cycle system, which uses a mixed refrigerant. Its composition is determined by refrigeration cycle simulation optimization according to the required refrigeration temperature and refrigeration capacity of the cold box.

6. The system for converting excess gaseous carbon dioxide produced as a byproduct of synthetic ammonia according to claim 1, characterized in that: The storage tank adopts a double-layer vacuum insulation structure. The inner layer is made of stainless steel. The thickness is determined according to the storage tank capacity and pressure requirements, ranging from 8-15mm. The outer layer is made of carbon steel with a thickness of 6-10mm. The vacuum degree of the vacuum layer is maintained in the range of 0.1-1Pa by a vacuum pump, and the storage tank is equipped with liquid level, pressure and temperature monitoring devices. The monitoring data is transmitted to the central control system in real time. The central control system automatically controls the feeding, discharging and refrigeration system operation of the storage tank according to the data.

7. The system for converting excess gaseous carbon dioxide produced as a byproduct of synthetic ammonia according to claim 1, characterized in that: The burner of the vaporizer adopts premixed combustion technology. The mixing ratio of fuel and air is determined by combustion experiments according to the combustion efficiency and flue gas temperature requirements, ranging from 1:10 to 1:

15. The flame temperature of the burner is controlled by adjusting the fuel flow rate and air flow rate. The control algorithm is based on temperature feedback, and the formula is F f =F f0 +k fb ×(T set -T act ), where F f is the fuel flow rate, F f0 is the initial fuel flow rate, k fb is the temperature feedback coefficient, T set To set the flame temperature, T act is the actual flame temperature.

8. The system for converting excess gaseous carbon dioxide produced as a byproduct of synthetic ammonia according to claim 1, characterized in that: The filling pump in the purchased liquid carbon dioxide tank truck unloading and filling device adopts a multi-stage centrifugal pump, and its head is determined by fluid mechanics calculation according to the storage tank height and the filling pipeline resistance, and the range is 30-50m. The safety interlock system includes a pressure sensor, a liquid level switch and an emergency shut-off valve. When the pressure in the storage tank exceeds the set upper limit or the liquid level exceeds the set upper limit, the emergency shut-off valve automatically closes and stops the filling operation to ensure the safety and reliability of the unloading and filling process. At the same time, the unloading and filling device is also equipped with a grounding protection device with a grounding resistance of less than 10Ω to prevent static electricity accumulation from causing safety accidents.

9. The system for converting excess gaseous carbon dioxide produced as a byproduct of synthetic ammonia according to claim 1, characterized in that: The one-button start control system adopts a redundant design, including a main controller and a backup controller. When the main controller fails, the backup controller automatically switches to operation to ensure the reliable start of the emergency gasification and supply process. The control system interacts with the control system of the joint alkali production device to obtain the operating status and carbon dioxide demand information of the joint alkali production device in real time, and automatically adjusts the supply parameters of gaseous carbon dioxide according to demand to ensure the stable operation of the joint alkali production.

10. A method for converting excess gaseous carbon dioxide produced as a by-product of synthetic ammonia, characterized in that: The specific steps of this method are: S1. Collection and pretreatment of gaseous carbon dioxide: The excess gaseous carbon dioxide produced as a byproduct of synthetic ammonia enters the precooling heat exchanger through the air intake pipe. According to the heat exchange algorithm of the precooling heat exchanger, Q = K × A × ΔT × f (P, T in ,T out ) for pre-cooling, and then enters the buffer tank, where the multi-layer elastic diaphragm structure in the buffer tank buffers pressure fluctuations, and the nanofiber composite filter is used to initially separate impurities; S2, Compression and deep purification: The gas flowing out of the buffer tank enters the compressor according to the intelligent adaptive compression algorithm P out =P in ×(1+α×ln(V in / V out )+β×(T in -T ref )) The gas is pressurized to 2.5MPa and then enters the desulfurization tower to fully react with the new composite metal oxide desulfurizer to remove sulfides. It then passes through the cooler and recooler in sequence, and uses a series of multi-stage cooling structures, circulating water, and frozen brine to reduce the gas temperature to about 10°C; S3, cold box purification and liquefaction: The gas with a temperature of about 10°C enters the cold box, and is distilled in the cold box according to the cryogenic distillation algorithm. The heavy components are discharged in the primary distillation tower, and then the carbon dioxide is liquefied by indirect heat exchange with the refrigerant through a staged condensation strategy in the primary condenser and the secondary condenser; S4. Storage and external sales: Liquid carbon dioxide enters the secondary distillation tower from the secondary condenser, further removes residual light component impurities under specific temperature and pressure conditions, and then enters the recooler according to the refrigeration cycle algorithm. After recooling, it is sent to the storage tank for storage. During the continuous and stable production period, part of the food-grade carbon dioxide is sold out according to the storage tank liquid level and market demand; S5. Emergency gasification and supply: When the failure of the synthetic ammonia unit causes the interruption of the production of raw carbon dioxide in the alkali process, the liquid carbon dioxide in the storage tank enters the vaporizer and is gasified according to the efficient heat conduction algorithm. Gasification into gaseous carbon dioxide, the pressure is set to 0.4MPa through a two-stage pressure reducing device, and the steam flow regulating valve is controlled according to the feedback control algorithm. Automatically adjust steam flow to control outlet flow at 15000-20000m 3 / hour, the one-button start control system starts the emergency gasification and supply process to ensure the joint alkali production. When the liquid carbon dioxide reserves in the storage tank are insufficient, it is replenished through the purchased liquid carbon dioxide tank truck unloading and filling device, and the filling pump is used to transport the liquid carbon dioxide in the tank truck to the storage tank. At the same time, the safety interlock system ensures the safety of the unloading and filling process.

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