Cement production process based on zero fossil energy outsourcing and zero carbon emission of existing cement production line

Abstract

The present application relates to a kind of zero fossil energy and zero carbon emission cement production process based on existing cement production line, it is realized by the following equipment, including preheater system, decomposer, rotary kiln, separation module, flow control module, heat exchange equipment, electric / photolysis water hydrogen production device, catalytic conversion module, ammonia catalytic decomposition device, heater and carbonization device;The cement production process of the present application passes through the above series of equipment, makes full use of the gas and heat generated in each step, saves energy to the greatest extent, almost no gas is discharged, no CO2 is emitted in the whole process of cement production, realizes the circulation or zero carbon emission;All heat consumption in the process of cement production comes from the methane and liquid fuel generated by catalytic conversion, and the part of carbon can realize internal circulation;Since full-oxygen combustion is used in preheater system one for pre-decomposition process, and N2 heating is used in preheater system two for pre-decomposition process, therefore, almost no nitrogen oxides are generated.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of environmental engineering, and particularly relates to a cement production process based on an existing cement production line and free of purchased fossil energy and carbon emissions. BACKGROUND

[0002] 2Since the cement industry uses calcium carbonate as raw material, the carbon source is emitted from fuel combustion and limestone decomposition, which will emit more carbon dioxide than the steel and thermal power industries; at the same time, the cement industry has large flue gas volume and low CO2 concentration, which brings greater difficulties to carbon capture.

[0003] For the enrichment, capture and utilization technology of CO2, Chinese Patent Publication No. CN114739163A discloses a cement industry carbon dioxide enrichment system and its process principle, which not only realizes the enrichment of part of the kiln tail flue gas carbon dioxide to greatly reduce the capture and utilization cost of carbon dioxide, but also effectively reduces the negative impact on the kiln system, but does not solve the problems of CO2 purification and utilization; Chinese Patent Publication No. CN114290504A discloses a production process and device for mineralizing and strengthening building waste and mineralized curing concrete products by using cement kiln tail gas, which performs pressure swing adsorption on the cement kiln tail gas to improve the CO2 concentration and then uses it for building waste strengthening or concrete mineralized curing, but due to the low CO2 concentration, the cost of pressure swing adsorption purification is relatively high.

[0004] In summary, the existing cement industry still has the following problems in CO2 emission reduction:

[0005] (1) Large CO2 emission and high concentration in the cement industry;

[0006] (2) High cost of CO2 capture and utilization;

[0007] (3) Air separation oxygen technology is used in oxy-combustion, and a large amount of N2 is wasted and discharged;

[0008] Therefore, it is urgent to find a technical route suitable for CO2 emission reduction in the cement industry. SUMMARY

[0009] In view of the problems in the prior art, the present application provides a cement production process based on an existing cement production line and free of purchased fossil energy and carbon emissions, which can be used for cement production by using the existing cement production equipment for modification, without purchasing fossil energy in the production process, without generating CO2 emissions, and maximizing the recycling of system gas and heat.

[0010] The application is achieved by a cement production process based on an existing cement production line, which is zero fossil energy and zero carbon emission, and is achieved by the following equipment, including a preheater system, a decomposition furnace, a rotary kiln, and further including a separation module, a flow control module, a heat exchange device, an electrolysis / photochemical water hydrogen production device, a catalytic conversion module, an ammonia catalytic decomposition device, a heater, and a carbonization device.

[0011] The specific steps are as follows:

[0012] The main fuel of the decomposition furnace and the kiln head burner is CH4 gas synthesized by CO2 and hydrogen; after the CH4 and O2 produced by electrolysis / photochemical water are burned at the kiln head burner, the generated CO2 and H2O pass through the kiln tail flue chamber and enter the decomposition furnace; the CH4 and O2 combustion in the decomposition furnace provides heat and generates CO2 and H2O, the raw material decomposition in the preheater system one and the decomposition furnace generates CO2, and the gas burned at the kiln head burner, the gas burned in the decomposition furnace, and the gas decomposed by the raw material in the preheater system one are mixed and enter the separation module one;

[0013] After passing through the separation module one, the CO2 and H2O are separated; the water vapor enters the heat exchange device one, is condensed into liquid water, and then enters the electrolysis / photochemical water hydrogen production device; the CO2 gas passes through the flow control module two and is divided into two paths, which respectively enter the catalytic conversion module one and the catalytic conversion module two;

[0014] The liquid water passes through the electrolysis / photochemical water hydrogen production device to generate H2 and O2; the H2 enters the catalytic conversion module one; the O2 acts as a combustion-supporting gas, passes through the flow control module one, and is divided into three paths, which respectively enter the kiln head burner, the decomposition furnace, and the ammonia catalytic decomposition device;

[0015] The CO2 and H2 entering the catalytic conversion module one react to generate H2O and CH4, and then enter the separation module two to separate the water vapor and CH4; the water vapor enters the heat exchange device two, is condensed into liquid water, and then enters the electrolysis / photochemical water hydrogen production device; the CH4 gas passes through the flow control module three and is divided into two paths, which respectively enter the kiln head burner and the decomposition furnace;

[0016] The NH3 enters the heat exchange device one, is preheated by the heat exchange device one, and then enters the heat exchange device two for preheating, and then enters the ammonia catalytic decomposition device heated to a fixed temperature, decomposes to generate N2 and H2, and then enters the separation module three to separate the N2 and H2; the H2 enters the catalytic conversion module two and catalytically reacts with the CO2 to generate liquid fuel; the N2 enters the heater;

[0017] The liquid fuel is divided into two paths, one of which enters the ammonia catalytic decomposition device, and is used for combustion reaction with O2 to heat the catalytic reaction bed layer in the ammonia catalytic decomposition device, and the combustion gas CO2+H2O is not contacted with NH3 in the catalytic reaction bed layer, and is heated by using independent pipelines, and the CO2+H2O enters the heater; the other path enters the kiln head burner, and is used as a supplement of CH4 fuel;

[0018] The N2+CO2+H2O in the heater enters the preheater system two, and is used for raw material decomposition; the CO2 generated by the raw material decomposition in the preheater system two is mixed with the gas entering the preheater system two, and then enters the carbonization device.

[0019] Preferably, the catalyst filled in the catalytic conversion module one is a Ni-based or Ru-based catalyst, and the reaction temperature is 280-350 DEG C; the catalyst filled in the catalytic conversion module two is a bifunctional catalyst, and the bifunctional is hydrogenation function and carbon chain growth function, and the reaction temperature is 200-450 DEG C.

[0020] Preferably, the catalyst filled in the ammonia catalytic decomposition device is a Ni-based or Co-based catalyst, and the reaction temperature is 600-850 DEG C.

[0021] Preferably, the separation module one and the separation module two select ceramic membrane separation components, and the separation module three selects a Pd separation membrane.

[0022] Preferably, the ammonia is heated to 150-200 DEG C after passing through the heat exchange equipment one, and is heated to 250-300 DEG C after passing through the heat exchange equipment two, and then enters the ammonia catalytic decomposition device.

[0023] Preferably, the raw material preheated and decomposed in the preheater system two directly enters the rotary kiln, the raw material preheated in the preheater system one enters the decomposition furnace, and then enters the rotary kiln, and a gas valve is arranged between the preheater system one and the preheater system two, so that the gases do not flow into each other.

[0024] Preferably, the N2 after passing through the separation module three is heated to 850-900 DEG C after passing through the heater.

[0025] Preferably, the liquid fuel is an alkane, an alkene and an alcohol compound.

[0026] Preferably, the carbonization device can be filled with low calcium clinker independently produced by a cement plant, so that high-performance auxiliary cementitious materials can be prepared after carbonization.

[0027] Preferably, the carbonization device can be filled with concrete block precursors prepared from building waste micro-powder and other additives, so that carbonized blocks can be prepared after carbonization curing.

[0028] The application has the advantages and positive effects that:

[0029] (1) The cement production process of the present application does not emit CO2 throughout the whole process, realizing cyclic or zero carbon emission, and all heat consumption in the cement production process comes from the catalytic conversion of generated methane and liquid fuel, and this part of carbon can realize internal circulation;

[0030] (2) The present application makes full use of the gas and heat generated in each step to save energy to the maximum extent, and almost no gas is discharged;

[0031] (3) The cement produced by the present application almost does not produce nitrogen oxides because full-oxygen combustion is used in the pre-decomposition process in the first preheater system and N2 heating is used in the pre-decomposition process in the second preheater system. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a flow chart of the cement production process provided by the embodiment of the present application, which is a zero-fossil energy purchase and zero-carbon emission cement production process. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0034] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0035] EMBODIMENT

[0036] As shown in Figure 1 , the present application provides a zero-fossil energy purchase and zero-carbon emission cement production process based on an existing cement production line, which is realized by the following devices, including a preheater system, a decomposition furnace, a rotary kiln, and further including a separation module, a flow control module, a heat exchange device, an electric / hydrogen production device by water splitting, a catalytic conversion module, an ammonia catalytic decomposition device, a heater, and a carbonization device.

[0037] The specific steps are as follows:

[0038] The main fuel of the decomposition furnace and the kiln head burner of the rotary kiln is CH4 gas synthesized by CO2 and hydrogen; after the combustion of CH4 and O2 generated by electrolysis and photolysis of water at the kiln head burner, the generated CO2 and H2O enter the decomposition furnace after passing through the kiln tail flue; CH4 and O2 are combusted in the decomposition furnace to provide heat, and CO2 and H2O are generated by the decomposition of raw materials in the preheater system and the decomposition furnace; after the combustion of the gas at the kiln head burner, the combustion gas in the decomposition furnace, and the gas generated by the decomposition of raw materials in the preheater system, the mixed gas enters the separation module one, and the temperature of the mixed gas is about 260-350℃.

[0039] The separation module one uses a ceramic membrane separation assembly to separate CO2 and H2O; the water vapor enters the heat exchange equipment one, is condensed into liquid water, and then enters the electrolysis and photolysis water hydrogen production device; the CO2 gas enters the flow control module two and is divided into two paths, which respectively enter the catalytic conversion module one and the catalytic conversion module two.

[0040] The electrolysis and photolysis water hydrogen production device needs to introduce a part of light energy or electric energy to supplement; liquid water generates H2 and O2 after passing through the electrolysis and photolysis water hydrogen production device; H2 enters the catalytic conversion module one; O2 enters the kiln head burner, the decomposition furnace, and the ammonia catalytic decomposition device as a combustion-supporting gas after being divided into three paths by the flow control module one.

[0041] The catalyst filled in the catalytic conversion module one is a Ni-based or Ru-based catalyst, and the reaction temperature is 280-350℃; CO2 and H2 entering the catalytic conversion module one react to generate H2O and CH4, and then enter the separation module two; the separation module two uses a ceramic membrane separation assembly to separate water vapor and CH4; the water vapor enters the heat exchange equipment two, is condensed into liquid water, and then enters the electrolysis and photolysis water hydrogen production device; the CH4 gas enters the kiln head burner and the decomposition furnace after being divided into two paths by the flow control module three.

[0042] NH3 is heated to 150-200℃ after entering the heat exchange equipment one, is preheated by the heat exchange equipment one, is preheated again after entering the heat exchange equipment two, and is heated to 250-300℃, and then enters the ammonia catalytic decomposition device which is heated to a fixed temperature, and decomposes to generate N2 and H2; N2 and H2 are separated by the separation module three which uses a Pd separation membrane; the catalyst filled in the catalytic conversion module two is a bifunctional catalyst, and the two functions are hydrogenation function and carbon chain growth function; the reaction temperature is 200-450℃; H2 enters the catalytic conversion module two, and catalytically reacts with CO2 to generate liquid fuel which is alkane, alkene, and alcohol compound; N2 enters the heater and is heated to 850-900℃.

[0043] The liquid fuel is divided into two paths, one of which enters the ammonia catalytic decomposition device, and is used for combustion reaction with O2 to heat the catalytic reaction bed layer in the ammonia catalytic decomposition device, the catalyst filled in the ammonia catalytic decomposition device is a Ni-based or Co-based catalyst, the reaction temperature is 600-850 DEG C, the gas CO2+H2O after combustion does not contact NH3 in the catalytic reaction bed layer, and is heated by using independent pipelines, CO2+H2O enters the heater; the other path of the liquid fuel enters the kiln head burner, and is used as a supplement of CH4 fuel.

[0044] The N2+CO2+H2O in the heater enters the preheater system two for raw material decomposition; the CO2 generated by raw material decomposition in the preheater system two is mixed with the gas entering the preheater two, and then enters the carbonization device for use. The carbonization device can be filled with low-calcium clinker independently produced by a cement plant, so that high-performance auxiliary cementitious materials can be prepared after carbonization. Or, the carbonization device can be filled with concrete block precursors prepared from building waste micro-powder and other additives, so that carbonized blocks can be prepared after carbonization curing.

[0045] The raw material preheated and decomposed in the preheater system two directly enters the rotary kiln, the raw material preheated in the preheater system one enters the decomposition furnace, and then enters the rotary kiln, and a gas valve is arranged between the outlets of the preheater system one and the preheater system two, so that the gases do not flow into each other.

[0046] The specific working process of the application is described in detail below:

[0047] First, start the electrolysis / photochemical water hydrogen production device, and introduce a certain amount of starting H2O(l) into the device, and introduce a part of light energy or electric energy into the electrolysis / photochemical water hydrogen production device, and the electrolysis / photochemical water hydrogen production device generates O2 and H2; the generated H2 and a part of starting CO2 are introduced into the catalytic conversion module one, under the action of the catalyst, CO2 and H2 react to generate CH4 and H2O(g), and then enter the separation module two, the separated H2O(g) passes through the heat exchange equipment two, and is condensed into H2O(l) and then enters the electrolysis / photochemical water hydrogen production device to enter the cycle, and the separated CH4 enters the flow control module three and is divided into two paths, and enters the kiln head burner and the decomposition furnace respectively.

[0048] The O2 generated by the electrolysis / photochemical decomposition water hydrogen production device enters the flow control module one and is divided into three paths, one of which enters the kiln head burner, mixes with CH4 and burns to provide heat for the kiln, and the CO2 and H2O(g) generated after burning enter the decomposition furnace after passing through the kiln tail flue; at the same time, the other path of O2 in the flow control module one mixes with CH4 and burns in the decomposition furnace to generate CO2 and H2O(g) to provide heat for raw material decomposition. The gas in the decomposition furnace enters the separation module one through the preheater system one, and the gas temperature is about 260-350℃, and CO2 is separated and enters the flow control module two, and H2O(g) is separated and enters the heat exchange equipment one, and H2O(l) is obtained after condensation through the heat exchange equipment one and enters the electrolysis / photochemical decomposition water hydrogen production device. The other path of O2 in the flow control module one enters the ammonia catalytic decomposition device.

[0049] The CO2 enters the flow control module two and is divided into two paths, one of which is introduced into the catalytic conversion module one to replace the starting CO2, and the other of which is introduced into the catalytic conversion module two.

[0050] In another circulating system, NH3 passes through the heat exchange equipment one and the heat exchange equipment two in turn, and the preheated NH3 enters the ammonia catalytic decomposition device after being heated to a fixed temperature by the catalytic reaction bed layer, to generate N2 and H2, which enter the separation module three for separation, wherein N2 enters the heater, and H2 enters the catalytic conversion module two and mixes with CO2 therein to synthesize liquid fuel; part of the liquid fuel enters the kiln head burner to supplement the heat for the kiln combustion, and the other part of the liquid fuel enters the ammonia catalytic decomposition device to provide heat for ammonia catalytic decomposition, and the liquid fuel and O2 are combusted to heat the catalytic reaction bed layer in the ammonia catalytic decomposition device, and the CO2+H2O after combustion does not contact NH3 in the catalytic reaction bed layer and is heated by an independent pipeline, and the CO2+H2O enters the heater after being heated with N2 entering the heater, and enters the preheater system two for raw material decomposition, and the N2 at the outlet of the preheater system two and the CO2 generated by the raw material decomposition are mixed and enter the carbonization device for carbonization of concrete products or steel slag. When used for carbonizing concrete products or steel slag, a part of pure oxygen is needed to assist combustion, and the pure oxygen can come from the air separation oxygen production system.

[0051] In summary, the cement production process of the present application does not emit CO2 throughout the process, realizes recycling or zero carbon emission, fully utilizes the gas and heat generated in each step, maximizes energy saving, and almost no gas is discharged; all heat consumption in the cement production process comes from the catalytic conversion generated methane and liquid fuel, and this part of carbon can realize internal circulation.

[0052] The present application produces cement, and since full-oxygen combustion is used in the preheater system one for the pre-decomposition process and N2 heating is used in the preheater system two for the pre-decomposition process, almost no nitrogen oxides are generated.

[0053] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, those ordinarily skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or equivalently replace some or all of the technical features thereof, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A cement production process based on existing cement production lines that achieves zero external fossil energy purchases and zero carbon emissions, the process being implemented through equipment including a preheater system, a decomposition furnace, and a rotary kiln, characterized in that: It also includes a separation module, a flow control module, a heat exchanger, an electrolysis / photocatalytic water splitting hydrogen production unit, a catalytic conversion module, an ammonia catalytic decomposition unit, a heater, and a carbonization unit; The specific steps of the cement production process are as follows: The main fuel for the decomposition furnace and the rotary kiln head burner is CH4 gas synthesized from CO2 hydrogenation. After the CH4 and O2 produced by electrolysis / photolysis of water are burned at the kiln head burner, the resulting CO2 and H2O enter the decomposition furnace after passing through the kiln tail smoke chamber. In the decomposition furnace, the combustion of CH4 and O2 provides heat and generates CO2 and H2O. CO2 is generated from the decomposition of raw materials in the preheater system and the decomposition furnace. The gas after combustion at the kiln head burner, the gas after combustion in the decomposition furnace, and the gas from the decomposition of raw materials in the preheater system are mixed and then enter the separation module one. After passing through separation module one, CO2 and H2O are separated; water vapor enters heat exchange device one, condenses into liquid water and then enters the electrolysis / photocatalytic water splitting hydrogen production device; CO2 gas passes through flow control module two and is divided into two paths, which enter catalytic conversion module one and catalytic conversion module two respectively; Liquid water is processed by an electrolysis / photocatalytic water splitting hydrogen production unit to produce H2 and O2; H2 enters the catalytic conversion module one; O2, as a combustion-supporting gas, is divided into three paths by the flow control module one, and enters the kiln head burner, the decomposition furnace, and the ammonia catalytic decomposition unit respectively. CO2 and H2 react in the first catalytic conversion module to produce H2O and CH4. Then, they enter the second separation module to separate water vapor and CH4. The water vapor enters the second heat exchanger, condenses into liquid water, and then enters the electrolysis / photocatalytic water splitting hydrogen production unit. The CH4 gas is divided into two streams by the third flow control module, which enter the kiln head burner and the decomposition furnace respectively. NH3 enters heat exchanger one, is preheated in heat exchanger one, and then enters heat exchanger two for preheating. After that, it enters the ammonia catalytic decomposition device where the catalytic reaction bed is heated to a fixed temperature, where it decomposes into N2 and H2. Then it enters separation module three to separate N2 and H2. H2 enters catalytic conversion module two and reacts with CO2 to produce liquid fuel. N2 enters the heater. The liquid fuel is divided into two paths. One path enters the ammonia catalytic decomposition unit, where it reacts with O2 to heat the catalytic reaction bed within the unit. After combustion, the gases CO2 + H2O and NH3 do not come into contact within the catalytic reaction bed and are heated by an independent pipeline. CO2 + H2O then enters the heater. The other path enters the kiln head burner as a supplement to the CH4 fuel. The N2+CO2+H2O in the heater enters the second preheater system for raw material decomposition. The CO2 produced by the decomposition of raw materials in the second preheater system is mixed with the gas entering the second preheater system and then enters the carbonization unit for use.

2. The cement production process based on existing cement production lines with zero external fossil energy purchases and zero carbon emissions, as described in claim 1, is characterized in that: The catalyst packed in the first catalytic conversion module is a Ni-based or Ru-based catalyst, and the reaction temperature is 280~350℃; the catalyst packed in the second catalytic conversion module is a bifunctional catalyst, with the bifunctional functions being hydrogenation and carbon chain growth, and the reaction temperature is 200~450℃.

3. The cement production process based on existing cement production lines with zero external fossil energy purchases and zero carbon emissions, as described in claim 1, is characterized in that: The catalyst packed in the ammonia catalytic decomposition device is a Ni-based or Co-based catalyst, and the reaction temperature is 600~850℃.

4. The cement production process based on existing cement production lines with zero external fossil energy purchases and zero carbon emissions, as described in claim 1, is characterized in that: The separation module one and separation module two are ceramic membrane separation components, and the separation module three is a Pd separation membrane.

5. The cement production process based on existing cement production lines with zero external fossil energy purchases and zero carbon emissions, as described in claim 1, is characterized in that: After passing through heat exchanger one, the ammonia gas is heated to 150~200℃, and after passing through heat exchanger two, it is heated to 250~300℃, and then enters the ammonia catalytic decomposition device.

6. The cement production process based on existing cement production lines with zero external fossil energy purchases and zero carbon emissions, as described in claim 1, is characterized in that: In Preheater System 2, the raw materials are preheated and decomposed before being directly fed into the rotary kiln. In Preheater System 1, the raw materials are preheated before being fed into the decomposition furnace and then into the rotary kiln. A gas valve is installed between the outlets of Preheater System 1 and Preheater System 2 to prevent gas from flowing between the two systems.

7. The cement production process based on existing cement production lines with zero external fossil energy purchases and zero carbon emissions, as described in claim 1, is characterized in that: After passing through the third separation module, the N2 is heated to 850~900℃ by the heater.

8. The cement production process based on existing cement production lines with zero external fossil energy purchases and zero carbon emissions, as described in claim 1, is characterized in that: Liquid fuels are alkanes, alkenes, and alcohols.

9. The cement production process based on existing cement production lines with zero external fossil energy purchases and zero carbon emissions, as described in claim 1, is characterized in that: The carbonization device contains low-calcium clinker produced by the cement plant, which is then carbonized to prepare high-performance auxiliary cementitious materials.

10. The cement production process based on existing cement production lines with zero external fossil energy purchases and zero carbon emissions, as described in claim 1, is characterized in that: The carbonization device contains a concrete block precursor prepared from construction waste powder and other additives, which is then carbonized and cured to produce carbonized blocks.

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