Rotary calcination carbonate coupled with catalytic reduction for syngas production system and method

Abstract

This invention discloses a rotary kiln system and method for co-producing syngas by coupled catalytic reduction of carbonates, belonging to the field of carbonate calcination technology. The system includes a rotary kiln assembly, comprising a rotary kiln and a drive unit. A heating device is installed outside the rotary kiln, and a heat exchange tube is installed outside the heating device. A kiln head mechanical seal and a kiln tail mechanical seal are respectively installed at both ends of the rotary kiln, with a feed pipe installed on the kiln head mechanical seal. A first heat recovery unit has a first material inlet and a first gas inlet; the first material inlet is connected to the feed pipe, and the first gas inlet is connected to the outlet of the heat exchange tube. A second heat recovery unit has a second material outlet and a second gas outlet; the second material outlet is connected to the kiln tail mechanical seal. A water removal unit is connected to the second gas outlet. An electrolysis water device is connected to the inlet of the heat exchange tube. This invention solves the problem of catalyst and solid product separation, ensures the quality of the solid product, and allows for catalyst recycling.

Description

Technical Field

[0001] This invention belongs to the field of carbonate calcination technology, and particularly relates to a rotary calcination carbonate coupled with catalytic reduction to produce syngas system and method. Background Technology

[0002] Carbonates are essential raw materials for heavy-emission industries such as steel, cement, and refractory materials. The large-scale use of carbonates in these industries releases massive amounts of CO2 through thermal decomposition, putting enormous pressure on achieving global carbon neutrality goals.

[0003] Existing research has shown that heating alkaline earth metal carbonates and transition metal carbonates in a hydrogen atmosphere can lower their thermal decomposition temperature by approximately 150°C compared to inert or oxidizing atmospheres. However, existing systems or methods for carbonate processing based on this principle still have various problems. For example, CN118491466A discloses an in-situ hydrogenation refining apparatus for carbonates, which does not consider the impact of waste heat utilization and conversion rate. CN118831526A discloses a low-carbon production system and method for hydrogen-assisted carbonate production of metal oxides and methanol, but the carbonate decomposition section uses a high hydrogen ratio, resulting in excessive gas volume and difficulties in reactor design and operation.

[0004] In summary, there is an urgent need for a low-carbon, green carbonate calcination process that achieves high conversion rates and effective utilization of waste heat. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a rotary calcination carbonate coupled with catalytic reduction for the co-production of syngas, which can effectively solve the problem of catalyst and solid product separation, ensure the quality of the solid product, recycle the catalyst, effectively accelerate the reaction, and ensure complete reaction.

[0006] This invention is achieved by providing a rotary calcination carbonate coupled with catalytic reduction for the co-production of syngas, comprising:

[0007] A rotary kiln assembly includes a rotary kiln and a drive device that provides rotational power to the rotary kiln. A heating device for heating the rotary kiln is provided outside the rotary kiln. A heat exchange tube is provided outside the heating device. A kiln head mechanical seal and a kiln tail mechanical seal are respectively provided at both ends of the rotary kiln. A feed pipe is provided on the kiln head mechanical seal. The first heat recovery unit has a first material inlet, a first material outlet, a first gas inlet, and a first gas outlet. The first material inlet is connected to a feed pipe, and the first gas inlet is connected to the outlet of a heat exchange tube. The second heat recovery unit has a second material inlet, a second material outlet, a second gas inlet, and a second gas outlet. The second material outlet is connected to the kiln tail mechanical seal. A water removal unit is connected to the second gas outlet; An electrolysis water device, wherein the hydrogen production outlet of the electrolysis water device is connected to the inlet of a heat exchange tube.

[0008] Furthermore, the first material outlet is equipped with a separator for separating the cooled solid material into solid finished product and catalyst, and the catalyst separated from the cooled solid material is transported to the second material outlet.

[0009] Furthermore, the heating device is an electric heating jacket fitted outside the rotary kiln, and the electric heating jacket controls the reaction temperature of the rotary kiln to be 300~900℃.

[0010] Furthermore, the molar ratio of hydrogen production to carbonate raw material in the water electrolysis device is (1~5):1.

[0011] Furthermore, the rotary kiln has an inclination angle of 1 to 4° and a rotation speed of 0.5 to 6 rpm.

[0012] Furthermore, the rotary kiln is equipped with lifting plates, which are arranged in one or multiple sections along the axial direction of the rotary kiln.

[0013] Furthermore, the solid region of the second heat recovery unit is provided with a drain pipe for draining the heated and evaporated water from the carbonate raw material.

[0014] Furthermore, an airlock valve is installed on the feeding pipe.

[0015] On the other hand, a preparation method using any of the above-described systems is provided, comprising the following steps: Preheating raw meal: Carbonate raw meal enters the second heat recovery unit, where it exchanges heat with the high-temperature syngas from the rotary kiln to 260~500℃ before entering the rotary kiln; Preheated hydrogen: The room-temperature hydrogen produced by the water electrolysis unit is heated once through the heat exchange tube and then enters the first heat recovery unit to exchange heat with the high-temperature material. After being heated a second time, it enters the rotary kiln. Coupled reduction reaction: Carbonate raw materials and hydrogen undergo a coupled reduction reaction in a rotary kiln under the action of a catalyst to produce syngas and metal oxides; Product processing: The high-temperature synthesis gas after the reaction is cooled by heat exchange in the second heat recovery unit and then dehydrated by the dehydration unit before being output; the high-temperature metal oxide is cooled by heat exchange in the first heat recovery unit and then discharged after the catalyst is separated by the separator. The separated catalyst is returned to the second material outlet.

[0016] Furthermore, the catalyst particle size is 1~3mm; the carbonate raw material particle size is 5~200μm.

[0017] The advantages and technical effects of this invention are as follows: By adopting the above-mentioned technical solution, the catalyst separation method is considered, the conversion rate is improved, waste heat is effectively utilized, and the process operation is simple. The co-production of syngas from carbonates using a zero-carbon emission method can be converted into high-value-added chemicals, reducing carbon dioxide emissions and contributing to the carbon neutrality goals of heavily emitting industries.

[0018] This method effectively solves the problem of catalyst and solid product separation. On the one hand, it ensures the quality of the solid product, eliminating the presence of harmful substances; on the other hand, it allows for catalyst recycling, effectively accelerating the reaction and ensuring complete reaction. Simultaneously, lifting plates can be installed inside the rotary kiln to alter the material's packing state, increasing the contact area between the material and gas, and accelerating the reaction. Adjusting the rotary kiln's rotation speed allows for control of the material's packing state and reaction time within the kiln, ensuring complete reaction.

[0019] It can eliminate carbon emissions caused by the use of carbonates in heavy-emission industries. Carbonates can react with H2 in the presence of a catalyst to generate syngas and metal oxides. The water electrolysis device, drive device, and electric heating jacket are powered by green electricity, achieving zero carbon emissions.

[0020] The waste heat generated on the surface of the rotary kiln is recovered by the first heat recovery unit, the second heat recovery unit, and the heat exchange tubes. While ensuring the temperature required by the downstream process, the waste heat is effectively utilized, reducing energy consumption and the use of green electricity.

[0021] The generated syngas can be used as a raw material for high-value chemicals. The ratio of H2 to CO in the syngas can be flexibly adjusted as needed to supply the process flow for producing different high-value chemicals. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the system structure provided in an embodiment of the present invention.

[0023] In the diagram: 10. Rotary kiln assembly; 11. Rotary kiln; 12. Kiln head mechanical seal; 13. Drive unit; 14. Electric heating jacket; 15. Heat exchange tube; 16. Kiln tail mechanical seal; 17. Feed pipe; 2. First heat recovery unit; 3. Separator; 4. Water electrolysis device; 5. Second heat recovery unit; 6. Water removal unit. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] It should be noted that the terms "upper", "lower", "left", "right", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0026] like Figure 1 As shown, this application provides a rotary calcination carbonate coupled with catalytic reduction for the co-production of syngas, comprising: The rotary kiln assembly 10 includes a rotary kiln 11 and a drive device 13 that provides rotational power to the rotary kiln 11. A heating device for heating the rotary kiln 11 is provided outside the rotary kiln 11. A heat exchange tube 15 is provided outside the heating device. Preferably, the heat exchange tube is spirally sleeved outside the heating device. A kiln head mechanical seal 12 and a kiln tail mechanical seal 16 are respectively provided at both ends of the rotary kiln 11. A feed pipe 17 is provided on the kiln head mechanical seal 12. The first heat recovery unit 2 has a first material inlet, a first material outlet, a first gas inlet and a first gas outlet. The first material inlet is connected to the feed pipe 17 and the first gas inlet is connected to the outlet of the heat exchange pipe 15. The second heat recovery unit 5 has a second material inlet, a second material outlet, a second gas inlet, and a second gas outlet. The second material outlet is connected to the kiln tail mechanical seal 16. The water removal unit 6 is connected to the second gas outlet; The water electrolysis device 4 has its hydrogen production outlet connected to the inlet of the heat exchange tube 15.

[0027] It should be noted that the first material outlet of the first heat recovery unit 2 is the solid finished product discharge outlet; the second material inlet of the second heat recovery unit 5 is the carbonate raw material inlet. The dewatering unit 6 is a membrane dewatering device or an absorption dewatering device.

[0028] The driving device 13 and the heating device use green electricity. The driving device 13 is driven by a motor and has an outer gear ring installed outside the rotary kiln 11. The motor output end is equipped with a drive gear that meshes with the outer gear ring to drive the rotary kiln 11 to rotate.

[0029] During operation, the rotary kiln 11 rotates. Both the kiln head mechanical seal 12 and the kiln tail mechanical seal 16 include rotating and stationary components. The rotating components rotate with the rotary kiln 11, while the stationary components remain relatively stationary. Gas and material conveying pipelines are connected to the stationary components. The kiln head mechanical seal 12 and the kiln tail mechanical seal 16 are interconnected with the rotary kiln. This ensures effective connection between the gas and material and the rotating kiln body during conveying. The kiln head mechanical seal 12 and the kiln tail mechanical seal 16 can be the DNF125ZT-BXG model mechanical seal manufactured by Shandong Haixuan Machinery Technology Co., Ltd.

[0030] As a preferred embodiment, the first material outlet is equipped with a separator 3 for separating the cooled solid material into a solid finished product and a catalyst. The catalyst separated from the cooled solid material is then conveyed to the second material outlet. Specifically, the separator 3 can be one of a vibrating screen, a centrifugal separator 3, or an electrostatic separator 3.

[0031] As a preferred embodiment, when the material and hydrogen can be coupled and reacted in a countercurrent manner within the rotary kiln 11: the first gas outlet is connected to the kiln head mechanical seal 12, and the second gas inlet is connected to the kiln tail mechanical seal 16; As a preferred embodiment, when the material and hydrogen can react in a co-current manner within the rotary kiln 11: the first gas outlet is connected to the kiln tail mechanical seal 16, and the second gas inlet is connected to the kiln head mechanical seal 12.

[0032] As a preferred embodiment, the heating device is an electric heating jacket 14 fitted around the outside of the rotary kiln 11, and the electric heating jacket 14 controls the reaction temperature of the rotary kiln 11 to be 300~900℃. The electric heating jacket 14 is configured to allow for multi-stage programmable setting of the temperature along the rotary kiln 11.

[0033] As a preferred embodiment, the molar ratio of hydrogen produced by the water electrolysis device 4 to the carbonate raw material is (1~5):1.

[0034] The molar ratio of hydrogen to carbonate in the reduction reaction is 1. Experiments have shown that the reduction conversion rate is insufficient when the hydrogen is introduced according to the stoichiometric ratio. Increasing the ratio is intended to improve the conversion rate and to regulate the ratio of CO and H2 in the syngas so that high-value chemicals can be synthesized downstream.

[0035] As a preferred embodiment, the rotary kiln 11 has an inclination angle of 1 to 4° and a rotation speed of 0.5 to 6 rpm.

[0036] The rotational speed is determined by the effective inner diameter of the rotary kiln 11 and the amount of carbonate processed, with the aim of controlling the distribution of material on its surface within the rotary kiln 11. Because this patent uses external heating, unlike conventional calcination methods, the material thickness needs to be reduced to facilitate heat transfer and decomposition. Specifically, when the carbonate processing volume is large and the effective inner diameter of the rotary kiln 11 is small, a faster rotational speed is required; conversely, when the carbonate processing volume is small and the effective inner diameter of the rotary kiln 11 is large, a slower rotational speed is required.

[0037] As a preferred embodiment, in order to change the material accumulation state and increase the contact area with gas, the rotary kiln 11 is provided with lifting plates, which are arranged in one or multiple sections along the axial direction of the rotary kiln 11.

[0038] As a preferred embodiment, in order to drain the moisture evaporated during the heating process in the carbonate raw material, the solid area of ​​the second heat recovery unit 5 is provided with a drain pipe for draining the moisture evaporated during the heating process in the carbonate raw material.

[0039] As a preferred embodiment, the feed pipe 17 is equipped with an airlock valve.

[0040] On the other hand, a preparation method using any of the above-described systems is provided, comprising the following steps: Preheating raw meal: Carbonate raw meal enters the second heat recovery unit 5, where it exchanges heat with the high-temperature synthesis gas from the rotary kiln 11 to 260~500℃ before entering the rotary kiln 11. Carbonate raw meal at 30~80℃ enters the second heat recovery unit 5 through the second material inlet, where it exchanges heat with the 600~900℃ high-temperature synthesis gas generated by the rotary kiln 11, and its temperature can reach 260~500℃.

[0041] Preheating hydrogen: The ambient temperature hydrogen produced by the water electrolysis unit 4 is first heated by heat exchange tube 15 and then enters the first heat recovery unit 2 to exchange heat with the high-temperature material. After a second heating, it enters the rotary kiln 11. The ambient temperature hydrogen produced by the water electrolysis unit 4 is heated to 80~150℃ by heat exchange tube 15 using waste heat and then enters the first heat recovery unit 2 to exchange heat with the high-temperature material. After the temperature rises to 300~500℃, it enters the rotary kiln 11.

[0042] Coupled reduction reaction: Carbonate raw materials and hydrogen undergo a coupled reduction reaction in the rotary kiln 11 under the action of a catalyst to produce syngas and metal oxides. The required heat is supplied by the electric heating jacket 14 through the rotary kiln 11.

[0043] Product processing: The high-temperature syngas after the reaction is cooled by heat exchange in the second heat recovery unit 5 and then dehydrated by the dehydration unit 6 before being output. The high-temperature metal oxides are cooled by heat exchange in the first heat recovery unit 2 and then separated from the catalyst by the separator 3 before being discharged. The separated catalyst is returned to the second material outlet. Specifically, the decomposed metal oxides, with a temperature of 600~900℃, enter the first heat recovery unit 2 and exchange heat with hydrogen from the heat exchange tube 15 to reduce the temperature to 300~500℃. Then, after separating the catalyst by the separator 3, the solid product is reserved for use. The syngas at 600~900℃ is cooled by heat exchange in the second heat recovery unit 5 to 260~500℃, and then enters the dehydration unit 6 to remove water before being output as syngas product to downstream production of high-value products.

[0044] Furthermore, the catalyst particle size is 1~3mm; the carbonate raw material particle size is 5~200μm.

[0045] Example 1 The system and process were applied to the carbonate decomposition process in the cement industry. The temperature of rotary kiln 11 was controlled at 800℃, the molar ratio of hydrogen produced by water electrolysis device 4 to carbonate raw material was 3:1, the rotation speed was controlled at 3 rpm, the catalyst particle size was selected as 2 mm, the carbonate raw material size was 40 μm, the water removal unit 6 adopted the membrane method, and the separator 3 was a vibrating screen. After calcination by this system, the carbonate was completely calcined, and the proportion of H2 in the synthesis gas was 66.67% and the proportion of CO was 33.33%, which can be used as a raw material for Fischer-Tropsch synthesis of α-olefins.

[0046] Example 2 The difference between this embodiment and embodiment 1 is that the electric heating jacket 14 is divided into 3 sections, and the controlled temperatures from the kiln head to the kiln tail are 850℃, 750℃ and 650℃ respectively. The catalyst particle size is 3mm, the separator 3 is an electric separator 3, and the generated synthesis gas can be used as a raw material for Fischer-Tropsch synthesis of ethanol.

[0047] Example 3 The system and process methods were applied to the lime-burning process. The temperature of rotary kiln 11 was controlled at 850℃, the molar ratio of hydrogen produced by water electrolysis device 4 to carbonate raw material was 4:1, the rotation speed was controlled at 3 rpm, the catalyst particle size was selected as 5 mm, the carbonate raw material particle size was 100 μm, the water removal unit 6 adopted the absorption method, and the separator 3 was a vibrating screen. After calcination by this system, the carbonate was completely calcined, and the H in the synthesis gas was reduced. 22 With a ratio of 75% and a CO ratio of 25%, it can be used as a raw material for the Fischer-Tropsch synthesis of α-olefins.

[0048] The above-mentioned technical solution, which considers catalyst separation methods, improves conversion rate, effectively utilizes waste heat, and simplifies process operation, allows for the co-production of syngas from carbonate calcination in a zero-carbon emission manner. This can be converted into high-value-added chemicals, reducing carbon dioxide emissions and contributing to the carbon neutrality goals of heavy-emission industries.

[0049] This effectively solves the problem of catalyst and solid product separation. On the one hand, it ensures the quality of the solid product, eliminating the presence of harmful substances; on the other hand, it allows for catalyst recycling, effectively accelerating the reaction and ensuring complete reaction. Simultaneously, lifting plates can be installed inside the rotary kiln 11 to change the material's packing state, increasing the contact area between the material and gas, and accelerating the reaction. Adjusting the rotational speed of the rotary kiln 11 allows for adjustment of the material's packing state and control of the reaction time within the kiln, ensuring complete reaction.

[0050] It can eliminate carbon emissions caused by the use of carbonates in heavy-emission industries. Carbonates can react with H2 in the presence of a catalyst to generate syngas and metal oxides. The water electrolysis device 4, drive device 13, and electric heating jacket 14 are powered by green electricity, which can achieve zero carbon emissions.

[0051] The waste heat generated on the surface of the rotary kiln 11 is recovered by the first heat recovery unit 2, the second heat recovery unit 5, and the heat exchange tube 15. While ensuring the temperature required by the downstream process, the waste heat is effectively utilized, reducing energy consumption and the use of green electricity.

[0052] The generated syngas can be used as a raw material for high-value chemicals. The ratio of H2 to CO in the syngas can be flexibly adjusted as needed to supply the process flow for producing different high-value chemicals.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A rotary calcination carbonate coupled with catalytic reduction for the co-production of syngas, characterized in that, include: A rotary kiln assembly includes a rotary kiln and a drive device that provides rotational power to the rotary kiln. A heating device for heating the rotary kiln is provided outside the rotary kiln. A heat exchange tube is provided outside the heating device. A kiln head mechanical seal and a kiln tail mechanical seal are respectively provided at both ends of the rotary kiln. A feed pipe is provided on the kiln head mechanical seal. The first heat recovery unit has a first material inlet, a first material outlet, a first gas inlet, and a first gas outlet. The first material inlet is connected to a feed pipe, and the first gas inlet is connected to the outlet of a heat exchange tube. The second heat recovery unit has a second material inlet, a second material outlet, a second gas inlet, and a second gas outlet. The second material outlet is connected to the kiln tail mechanical seal. A water removal unit is connected to the second gas outlet; An electrolysis water device, wherein the hydrogen production outlet of the electrolysis water device is connected to the inlet of a heat exchange tube.

2. The rotary calcination carbonate coupled with catalytic reduction and co-production of syngas system according to claim 1, characterized in that, The first material outlet is equipped with a separator to separate the cooled solid material into solid finished product and catalyst. The catalyst separated from the cooled solid material is then transported to the second material outlet.

3. The rotary calcination carbonate coupled with catalytic reduction and co-production of syngas system according to claim 1, characterized in that, The heating device is an electric heating jacket fitted outside the rotary kiln, and the electric heating jacket controls the reaction temperature of the rotary kiln to be 300~900℃.

4. The rotary calcination carbonate coupled with catalytic reduction and co-production of syngas system according to claim 1, characterized in that, The molar ratio of hydrogen production to carbonate raw material in the water electrolysis device is (1~5):

1.

5. The rotary calcination carbonate coupled with catalytic reduction and co-production of syngas system according to claim 1, characterized in that, The rotary kiln has an inclination angle of 1 to 4° and a rotation speed of 0.5 to 6 rpm.

6. The rotary calcination carbonate coupled with catalytic reduction and co-production of syngas system according to claim 1, characterized in that, The rotary kiln is equipped with lifting plates, which are arranged in one or multiple sections along the axial direction of the rotary kiln.

7. The rotary calcination carbonate coupled with catalytic reduction and co-production of syngas system according to claim 1, characterized in that, The solid region of the second heat recovery unit is equipped with a drain pipe for draining the heated and evaporated water from the carbonate raw material.

8. The rotary calcination carbonate coupled with catalytic reduction and co-production of syngas system according to claim 1, characterized in that, An airlock valve is installed on the feeding pipe.

9. A method for preparing the system according to any one of claims 1 to 8, characterized in that, Includes the following steps: Preheating raw meal: Carbonate raw meal enters the second heat recovery unit, where it exchanges heat with the high-temperature syngas from the rotary kiln to 260~500℃ before entering the rotary kiln; Preheated hydrogen: The room-temperature hydrogen produced by the water electrolysis unit is heated once through the heat exchange tube and then enters the first heat recovery unit to exchange heat with the high-temperature material. After being heated a second time, it enters the rotary kiln. Coupled reduction reaction: Carbonate raw materials and hydrogen undergo a coupled reduction reaction in a rotary kiln under the action of a catalyst to produce syngas and metal oxides; Product processing: The high-temperature synthesis gas after the reaction is cooled by heat exchange in the second heat recovery unit and then dehydrated by the dehydration unit before being output; the high-temperature metal oxide is cooled by heat exchange in the first heat recovery unit and then discharged after the catalyst is separated by the separator. The separated catalyst is returned to the second material outlet.

10. The preparation method according to claim 9, characterized in that, The catalyst particles have a size of 1-3 mm; the carbonate raw material particles have a size of 5-200 μm.

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