Integrated system and method for cascade recycling of waste heat of calcium carbide

Abstract

The invention discloses an integrated system and method for cascade recycling of calcium carbide waste heat, and belongs to the technical field of calcium carbide production waste heat utilization. The integrated system comprises a waste heat recycling unit, a waste heat storage unit and a cyclic utilization unit which are communicated in sequence; small and solid calcium carbide blocks can be directly obtained through production of the integrated system, the technological process can be greatly shortened, the production efficiency can be improved, the occupied area can be reduced, meanwhile, stepped recycling of calcium carbide waste heat can be achieved, and the production cost is reduced. The water to be electrolyzed is subjected to gradient heating through oxygen cooling, nitrogen and calcium carbide contact heat transfer and calcium carbide radiant heat absorbed by carbon dioxide, a cooling gas path and the calcium carbide are subjected to contact heat exchange, loss caused by contact of water vapor and the calcium carbide in the technological process is greatly reduced, and the quality and productivity of the calcium carbide are effectively guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of waste heat utilization in calcium carbide production, and in particular to an integrated system and method for cascade recovery and utilization of waste heat from calcium carbide. Background Art

[0002] The production of calcium carbide generates significant carbon emissions. These emissions come from two main sources: direct carbon emissions, generated during the reaction between quicklime and carbon-containing raw materials (coke, lignite, anthracite, etc.); and indirect carbon emissions, generated through electricity consumption during calcium carbide production. According to the "Energy Consumption per Unit of Calcium Carbide Product" (GB21343-2015), each ton of calcium carbide consumes 3,300-3,500 kWh of electricity, equivalent to approximately 805-940 kg of standard coal. By 2025, the calcium carbide industry is required to achieve a benchmark production capacity of over 30% through energy-saving and carbon-reduction initiatives. Therefore, energy conservation, emission reduction, and carbon-reduction adjustments will be a top priority for future development of the calcium carbide industry. After calcium carbide leaves the furnace, a significant amount of heat is released as it solidifies from liquid to gas. Currently, there are no mature waste heat recovery processes to recycle this heat, resulting in significant heat dissipation. According to calculations, the total waste heat carried by 1 ton of calcium carbide is about 2.789GJ. If fully utilized, it can reduce carbon dioxide emissions (carbon emission coefficient is 0.67 tC / tce) by about 0.234 tons.

[0003] In recent years, a large amount of research and results have been produced in the field of calcium carbide waste heat recovery and utilization, including technologies related to calcium carbide waste heat recovery and direct utilization. Traditional recovery methods can extract heat, but the amount of heat is huge, and calcium carbide production is intermittent. Direct connection to the existing system will cause great system fluctuations and have strict requirements on the load adjustment capacity of the equipment. The connection of energy storage devices can effectively overcome the above problems. However, in the coupling technology of energy storage devices and calcium carbide production devices, the energy density is relatively low, about 30-60Wh / L. When it comes to large-scale, large-volume and long-cycle heat storage processes, the energy storage density is insufficient. At the same time, the energy release process needs to rely on specific equipment (such as expanders) and the flexibility is still insufficient.

[0004] Based on the above problems, an integrated system and method for cascade recovery and utilization of calcium carbide waste heat are proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide an integrated system and method for cascade recovery and utilization of calcium carbide waste heat to solve the problems in the background technology.

[0006] To achieve the above-mentioned purpose, the present invention provides an integrated system for the cascade recovery and utilization of calcium carbide waste heat, comprising a waste heat recovery unit, a waste heat storage unit, and a recycling unit connected in sequence, wherein the waste heat recovery unit comprises a feeding device and a granulating device, the waste heat storage unit comprises a low-temperature heat exchanger, a high-temperature dust collector, a medium-temperature heat exchanger, a high-temperature heat exchanger, a supplementary heat electric heater, a solid oxide electrolyzer, a preheating evaporator, a condenser, a hydrogen liquefaction storage device, an oxygen liquefaction storage device, a water supply pump, and a water supply treatment device; the recycling unit comprises a hydrogen utilization module and an oxygen utilization module; In the waste heat recovery unit, the feeding device receives the molten calcium carbide in the calcium carbide furnace, and the molten calcium carbide in the feeding device enters the granulating device.

[0007] Preferably, the low-temperature heat exchanger is connected to the calcium carbide outlet of the granulating device, the inlet of the high-temperature dust collector is connected to the cooling gas phase outlet of the granulating device, and the high-temperature side inlet of the medium-temperature heat exchanger is connected to the outlet of the high-temperature dust collector; the high-temperature side outlet of the medium-temperature heat exchanger is connected to the gas phase inlet of the low-temperature heat exchanger through a circulating fan; the tube-side inlet of the high-temperature heat exchanger is connected to the granulating device, and the tube-side outlet of the high-temperature heat exchanger is connected to the granulating device through a compressor.

[0008] Preferably, the low-temperature side inlet of the medium-temperature heat exchanger is connected to the water side outlet of the preheating evaporator, and the water side inlet of the preheating evaporator is connected to the water treatment device through a water supply pump; the inlet of the water treatment device is connected to the liquid phase outlet of the condenser, the liquid phase inlet of the condenser is connected to the cathode outlet of the solid oxide electrolyzer, and the gas phase outlet of the condenser is connected to the hydrogen liquefaction storage device; The high-temperature side inlet of the preheating evaporator is connected to the anode outlet of the solid oxide electrolysis cell, and the high-temperature side outlet of the preheating evaporator is connected to the oxygen liquefaction storage device.

[0009] Preferably, the low temperature side outlet of the medium temperature heat exchanger is connected to the shell side inlet of the high temperature heat exchanger, and the shell side outlet of the high temperature heat exchanger is connected to the supplementary heat electric heater; the other end of the supplementary heat electric heater is connected to the solid oxide electrolytic cell.

[0010] The present invention also provides a method for cascade recovery and utilization of calcium carbide waste heat, which is achieved through an integrated system for cascade recovery and utilization of calcium carbide waste heat. The specific cascade recovery and utilization method of calcium carbide waste heat is as follows: 1) The molten calcium carbide in the feeding device enters the granulating device through the lower discharge port. In the granulating device, it is centrifuged by the high-speed rotating cup-shaped liquid receiving plate and blown toward the inner wall of the granulating device shell by the cooling gas phase working medium. At this time, the cooling gas phase working medium and the granulated calcium carbide liquid undergo contact heat exchange; 2) After the contact heat exchange is completed, the cooling gas phase working medium enters the high-temperature dust collector from the cooling gas phase outlet of the granulation device for dust removal. The cooling gas phase working medium then enters the medium-temperature heat exchanger and performs non-contact heat exchange with the water vapor to be electrolyzed that has been preheated in the preheating evaporator. After the cooling gas phase working medium releases heat, it is pressurized by the circulating fan and pumped to the low-temperature heat exchanger; 3) The granulated calcium carbide particles enter the low-temperature heat exchanger from the granulation device, where they undergo direct contact heat exchange with the cooling gas phase. The heated cooling gas phase enters the cooling gas path of the granulation device. After deep cooling, the calcium carbide particles are transported to subsequent process flows by a calcium carbide transfer vehicle. 4) The circulating working fluid CO2 absorbs the radiant heat of the calcium carbide liquid in the radiant heat exchanger of the granulation device, and the temperature of CO2 rises. Then, CO2 enters the high-temperature heat exchanger and indirectly exchanges heat with the water vapor to be electrolyzed, transferring the heat to the water vapor to be electrolyzed. After releasing heat, CO2 is pressurized by the compressor and returned to the radiant heat exchanger to complete the cycle. 5) The feed water treatment device desalinates the feed water to be electrolyzed and then pressurizes it into the preheating evaporator via the feed water pump. It undergoes preliminary non-contact heat exchange with the high-temperature O2 generated at the anode of the solid oxide electrolytic cell. After the electrolysis feed water absorbs heat and evaporates, it enters the medium-temperature heat exchanger and undergoes non-contact heat exchange with the cooled gas phase working medium after dust removal. It then enters the high-temperature heat exchanger and undergoes non-contact heat exchange with the circulating working medium CO2. After the temperature of the electrolysis water vapor is further increased, it is supplemented by the supplementary heating electric heater according to the temperature control adjustment. 6) After the heat supplement is completed, the water vapor to be electrolyzed enters the cathode of the solid oxide electrolysis cell for electrolysis. The H2 produced at the cathode and the unreacted water vapor enter the condenser for cooling. The unreacted water vapor is condensed into liquid and removed for hydrogen purification. The condensed water is discharged from the liquid phase outlet and returned to the water treatment device for reuse, and the H2 enters the hydrogen liquefaction storage device.

[0011] Preferably, the cooling gas phase working medium is nitrogen or dehydrated air.

[0012] Preferably, in the high-temperature heat exchanger, the circulating working fluid CO2 enters the tube side, and the electrolyzed water vapor enters the shell side for indirect heat exchange.

[0013] Preferably, in the solid oxide electrolyzer, the hydrogen generated by electrolysis is utilized through a hydrogen utilization module, and the hydrogen and acetylene produced by calcium carbide are introduced into an ethylene tower together for hydrogenation reaction to produce ethylene.

[0014] Preferably, the oxygen after heat exchange in the preheating evaporator enters the oxygen liquefaction storage device, or enters the factory's own boiler unit through the oxygen utilization module for pure oxygen combustion.

[0015] Therefore, the integrated system and method for cascade recovery and utilization of calcium carbide waste heat of the present invention has the following beneficial effects: (1) The present invention organically combines the three links of waste heat recovery, storage and utilization to achieve integrated operation, reduce the equipment footprint, and reduce the system complexity and investment cost; small, solid calcium carbide blocks can be directly obtained in one production, which can greatly shorten the process flow, improve production efficiency, and reduce the footprint. The calcium carbide blocks can be reduced to below 300°C, effectively recovering about 85% of the waste heat of calcium carbide and reducing the cooling time by about 90%.

[0016] (2) In the present invention, the calcium carbide liquid is first dispersed into small droplets by rotating centrifugation and high-speed gas blowing, and the cooling gas phase medium and the calcium carbide liquid droplets are contacted for heat exchange. The heat exchange specific surface area is greatly improved compared with the natural cooling form of the traditional calcium carbide pot, ensuring the stable and continuous operation of the integrated system under high temperature conditions; the cooling gas circuit uses nitrogen or dehydrated air as the circulating cooling medium to perform contact heat exchange with the calcium carbide, which greatly reduces the loss caused by the contact between water vapor and calcium carbide in this process, and effectively ensures the quality and production capacity of the calcium carbide; and the method uses oxygen cooling, nitrogen contact heat transfer with calcium carbide, and calcium carbide radiation heat absorbed by carbon dioxide to perform step-by-step heating on the water to be electrolyzed, which can realize the step-by-step recovery and utilization of calcium carbide waste heat.

[0017] (3) The present invention reduces direct heat emissions and thermal pollution to the environment by recycling the waste heat of calcium carbide. Water is electrolyzed to generate hydrogen and oxygen. Hydrogen can be used for subsequent production as a clean energy source, and oxygen is used for pure oxygen combustion to improve energy utilization efficiency and reduce pollutant emissions. The condenser condenses the unreacted water vapor into liquid form and removes it, which is then returned to the water treatment device for reuse, thus realizing the recycling of water resources, reducing the waste of water resources, and having good environmental benefits.

[0018] (4) The existing acetylene hydrogenation reaction to produce ethylene is not economical because the generation of hydrogen requires a large amount of electricity. In the present invention, hydrogen is produced by cooling the waste heat of calcium carbide, which can effectively utilize waste heat. The temperature range of waste heat is cascaded to meet the needs of solid oxide electrolysis for hydrogen production, and it provides a new process route and system solution for the acetylene-ethylene industry chain.

[0019] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the granulation process according to an embodiment of the present invention; Figure 2 This is a schematic structural diagram of a granulation device according to an embodiment of the present invention; Reference numerals: 1. Feeding device; 2. High-temperature dust collector; 3. Medium-temperature heat exchanger; 4. High-temperature heat exchanger; 5. Supplementary heat electric heater; 6. Oxygen liquefaction storage device; 7. Preheating evaporator; 8. Solid oxide electrolyzer; 9. Water supply pump; 10. Water supply treatment device; 11. Ethylene tower; 12. Hydrogen liquefaction storage device; 13. Condenser; 14. Circulating fan; 15. Compressor; 16. Low-temperature heat exchanger; 17. Granulation device; 1701. Cup-shaped liquid receiving tray; 1702. Molten calcium carbide inlet; 1703. Cooling gas phase outlet; 1704. Radiant heat exchanger; 1705. Casing; 1706. Cooling gas path; 1707. Granulated calcium carbide outlet; 1708. Motor; 1709. Cooling gas phase inlet; 1710. Rotating shaft; 1711. Rotating scraper. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0023] Example like Figure 1 As shown, the present invention provides an integrated system for the cascade recovery and utilization of calcium carbide waste heat, including a waste heat recovery unit, a waste heat storage unit, and a recycling unit connected in sequence. The waste heat recovery unit includes a feeding device 1 and a granulating device 17. The feeding device 1 is used to receive the molten calcium carbide in the calcium carbide furnace and is made of a material with excellent high temperature resistance and thermal shock resistance. A certain slope is set at the bottom of the feeding device 1, and a discharge port is set on the lower side of the bottom. At the same time, the feeding device 1 is vertically arranged with an agitator to slow down the solidification rate of calcium carbide; the slope and the agitator are set at the bottom, which can effectively slow down the solidification rate of calcium carbide and facilitate subsequent processing. The granulating device 17 adopts a centrifugal dispersed molding cooling method, and the cooling gas phase working medium and the granulated calcium carbide liquid are fully in contact with each other for heat exchange, thereby improving the heat recovery efficiency.

[0024] The molten calcium carbide in the feeding device 1 enters the granulating device 17. Figure 2As shown, the granulation device 17 adopts a centrifugal dispersion molding method. The granulation device 17 consists of a rotating distributor, a shell 1705, a cooling air path 1706, a radiation heat exchanger 1704, and a rotating scraper 1711. The shell 1705 is located directly below the feeding device 1, and the center line opening at the top of the shell 1705 is connected to the outlet of the feeding device 1; the shell 1705 adopts a double-conical design, and a cooling gas phase inlet 1709, a cooling gas phase outlet 1703, a molten calcium carbide inlet 1702 and a granulated calcium carbide outlet 1707 are respectively arranged on the upper and lower parts of the shell 1705. The radiation heat exchanger 1704 is attached to the conical geometric topological configuration presented by the outer wall of the double-conical shell 1705. The radiation heat exchanger 1704 is spiral-shaped. Since the lower part of the shell 1705 receives the granulated calcium carbide particles, the heat exchanger pipeline arranged at the lower part is denser than that at the upper part, which can better absorb the radiation heat of the calcium carbide particles.

[0025] Cooling air path 1706 extends directly from the centerline of the bottom of housing 1705 into the interior of granulating device 17. A rotating distributor is provided within cooling air path 1706. The rotating distributor comprises a cup-shaped liquid receiving tray 1701, a rotating shaft 1710, and a drive motor. Rotating shaft 1710 is driven by motor 1708 to rotate at high speed, and the top of rotating shaft 1710 is connected to cup-shaped liquid receiving tray 1701. The top opening of cooling air path 1706 adopts a gradually diverging structure, allowing the cooling gaseous medium to enter the interior of granulating device 17 through the channel between the liquid receiving tray and the gradually diverging structure. Cooling air path 1706 uses nitrogen or dehydrated air as the circulating cooling medium. Rotating scraper 1711, located on the inner wall of housing 1705, is biconical in shape, matching the inner wall of housing 1705. Driven by an additional motor 1708, it is used to remove calcium carbide blocks adhering to the inner wall of housing 1705.

[0026] A supercritical CO2 circulation module is formed between the radiation heat exchanger 1704 and the high-temperature heat exchanger 4. A compressor 15 is connected to the outlet of the high-temperature heat exchanger 4 to maintain the pressure state of the circulation loop, thereby realizing CO2 circulation and further improving the efficiency of waste heat recovery.

[0027] The waste heat storage unit includes a low-temperature heat exchanger 16, a high-temperature dust collector 2, a medium-temperature heat exchanger 3, a high-temperature heat exchanger 4, a supplementary heat electric heater 5, a solid oxide electrolytic cell 8, a preheating evaporator 7, a condenser 13, a hydrogen liquefaction storage device 12, an oxygen liquefaction storage device 6, a water supply pump 9, and a water supply treatment device 10. The waste heat is reasonably stored and transferred through the above-mentioned equipment to provide a stable heat source for the subsequent electrolysis process. The low-temperature heat exchanger 16 is connected to the calcium carbide outlet of the granulation device 17. The granulated calcium carbide particles enter the low-temperature heat exchanger 16. The cooling gas phase working medium and the calcium carbide particles are in direct contact for heat exchange. The heated cooling gas phase working medium enters the cooling gas path 1706 to complete the rotary centrifugal granulation. The inlet of the high-temperature dust collector 2 is connected to the cooling gas phase outlet 1703 of the granulation device 17. A ceramic fiber dust collector is selected according to the temperature resistance.

[0028] The medium-temperature heat exchanger 3 adopts a shell and tube heat exchanger with the tube side being the high-temperature side. The high-temperature side inlet is connected to the outlet of the high-temperature dust collector 2; the high-temperature side outlet of the medium-temperature heat exchanger 3 is connected to the gas phase inlet of the low-temperature heat exchanger 16 through the circulating fan 14. The medium-temperature heat exchanger 3 is used for further heating of the water vapor to be electrolyzed.

[0029] The tube-side inlet of high-temperature heat exchanger 4 is connected to granulation unit 17, while the tube-side outlet of high-temperature heat exchanger 4 is connected to granulation unit 17 via compressor 15. High-temperature heat exchanger 4 utilizes a tubular silicon carbide ceramic heat exchanger, with high-temperature CO2 flowing through the tube side and water vapor to be electrolyzed flowing through the shell side. After absorbing radiant heat in radiant heat exchanger 1704 in granulation unit 17, the CO2 transfers this heat to the water vapor to be electrolyzed in high-temperature heat exchanger 4. After releasing the heat, the CO2 is connected to radiant heat exchanger 1704 in granulation unit 17 via compressor 15, completing the CO2 cycle.

[0030] The shell side of the medium-temperature heat exchanger 3 is the low-temperature side, the low-temperature side inlet is connected to the water side outlet of the preheating evaporator 7, the low-temperature side outlet is connected to the shell side inlet of the high-temperature heat exchanger 4, and the shell side outlet of the high-temperature heat exchanger 4 is connected to the supplementary heating electric heater 5. The supplementary heating electric heater 5 is used to perform supplementary heating when the outlet of the electrolyzed water vapor of the high-temperature heat exchanger 4 cannot reach the set optimal electrolysis temperature range. The set temperature is adjusted according to parameters such as the electrolysis current density of the solid oxide electrolysis cell 8; the other end of the supplementary heating electric heater 5 is connected to the solid oxide electrolysis cell 8, which ensures the stable progress of the electrolysis process and improves the adaptability of the system to different working conditions.

[0031] The water side inlet of the preheating evaporator 7 is connected to the water treatment device 10 through the water pump 9. The water treatment device 10 desalinates and removes impurities from the water before it enters the preheating evaporator 7 for heating and evaporation. The inlet of the water treatment device 10 is connected to the liquid phase outlet of the condenser 13. The liquid phase inlet of the condenser 13 is connected to the cathode outlet of the solid oxide electrolysis cell 8. The solid oxide electrolysis cell 8 can adopt a (BSCF-SDC|YSZ-SDC|Ni-YSZ) electrolysis cell. After the electrolyzed water vapor is heated by the high-temperature heat exchanger 4, it is adjusted to the set temperature of the electrolysis in the supplementary heating electric heater 5 and then enters the cathode. During operation, the high-temperature water vapor to be electrolyzed is input from the cathode. Under the action of the current, a reduction reaction is carried out at the cathode to generate hydrogen and oxygen ions. The relevant reaction formula is: 2 H 2 O +4 e − =2 H 2 +2 O 2 − ; Oxygen ions are transported from the electrolyte to the anode, where they undergo an oxidation reaction to generate oxygen. The reaction formula is: 2 O 2 − = O 2 +4 e − ; Unreacted water vapor and hydrogen both enter the condenser 13, where the unreacted water vapor is condensed into a liquid state and removed to achieve hydrogen purification. The condenser 13 is provided with a gas phase outlet and a liquid phase outlet, respectively. The condensed water is discharged from the liquid phase outlet and refluxed to the water treatment device 10 for reuse. The gas phase outlet of the condenser 13 is connected to the hydrogen liquefaction storage device 12 to achieve the storage of high-purity hydrogen and realize the effective storage and conversion of energy.

[0032] The high-temperature side inlet of the preheating evaporator 7 is connected to the anode outlet of the solid oxide electrolysis cell 8, and the oxygen generated by electrolysis enters the preheating evaporator 7. The high-temperature side outlet of the preheating evaporator 7 is connected to the oxygen liquefaction storage device 6, and the oxygen after heat exchange is completed is stored.

[0033] The recycling unit includes a hydrogen utilization module and an oxygen utilization module. The hydrogen utilization module utilizes hydrogen generated by electrolysis. Acetylene produced from calcium carbide and hydrogen enter the ethylene tower 11 for a hydrogenation reaction to produce ethylene. The oxygen utilization module allows oxygen to enter the plant's own boiler unit for pure oxygen combustion, effectively improving boiler efficiency and, in turn, overall plant efficiency.

[0034] The specific method of cascade recovery and utilization of calcium carbide waste heat is as follows: 1) The molten calcium carbide in the feeding device 1 enters the molten calcium carbide inlet 1702 of the granulating device 17 through the lower discharge port. Inside the granulating device 17, the molten calcium carbide is centrifuged by the high-speed rotating cup-shaped liquid receiving plate 1701 and blown toward the inner wall of the granulating device 17 housing by the cooling gaseous working medium, which is nitrogen or dehydrated air. At this time, the cooling gaseous working medium and the granulated calcium carbide liquid undergo contact heat exchange; 2) After the contact heat exchange is completed, the cooled gas phase working medium enters the high-temperature dust collector 2 through the cooled gas phase outlet 1703 of the granulating device 17 for dust removal. The cooled gas phase working medium then enters the medium-temperature heat exchanger 3 and performs non-contact heat exchange with the water vapor to be electrolyzed that has been preheated in the preheating evaporator 7. After releasing heat, the cooled gas phase working medium is pressurized by the circulating fan 14 and pumped to the low-temperature heat exchanger 16. 3) The granulated calcium carbide particles enter the low-temperature heat exchanger 16 through the granulated calcium carbide outlet 1707 of the granulating device 17. The calcium carbide particles and the cooling gas phase work medium perform direct contact heat exchange. The heated cooling gas phase work medium enters the cooling gas path 1706 of the granulating device 17. After deep cooling, the calcium carbide particles are transported to the subsequent process by the calcium carbide transfer vehicle; 4) The circulating working fluid CO2 absorbs the radiant heat of the calcium carbide liquid in the radiant heat exchanger 1704 of the granulation device 17, causing the CO2 temperature to rise. The CO2 then enters the high-temperature heat exchanger 4, where it indirectly exchanges heat with the water vapor to be electrolyzed, transferring the heat to the water vapor to be electrolyzed. After releasing heat, the CO2 is pressurized by the compressor 15 and then returned to the radiant heat exchanger 1704 to complete the circulation. 5) The feed water treatment device 10 desalinates the feed water to be electrolyzed and then pressurizes it through the feed water pump 9 and transports it to the preheating evaporator 7, where it undergoes preliminary non-contact heat exchange with the high-temperature O2 generated at the anode of the solid oxide electrolysis cell 8. After the heat exchange is completed, the oxygen enters the oxygen liquefaction storage device 6, or enters the plant's own boiler unit through the oxygen utilization module for pure oxygen combustion.

[0035] After the heat exchange is completed, the electrolytic feed water absorbs heat and evaporates, then enters the medium-temperature heat exchanger 3, and performs non-contact heat exchange with the cooled gas phase working medium after dust removal, and then enters the high-temperature heat exchanger 4. The circulating working medium CO2 enters the tube side, and the electrolytic water vapor enters the shell side. The electrolytic water vapor and the circulating working medium CO2 perform non-contact heat exchange. After the temperature of the electrolytic water vapor is further increased, it is heated in the heating electric heater 5 according to the temperature control adjustment; 6) After the heat supplement is completed, the water vapor to be electrolyzed enters the cathode of the solid oxide electrolysis cell 8 for electrolysis, and the H2 produced at the cathode and the unreacted water vapor enter the condenser 13 for cooling. The unreacted water vapor is condensed into liquid and removed for hydrogen purification. The condensed water is discharged from the liquid phase outlet and returned to the water treatment device 10 for reuse. The H2 is utilized through the hydrogen utilization module, and the hydrogen and acetylene produced by calcium carbide are jointly introduced into the ethylene tower 11 for hydrogenation reaction to prepare ethylene. Therefore, the present invention provides an integrated system and method for the cascade recovery and utilization of calcium carbide waste heat. Small, solid calcium carbide blocks can be directly obtained through production through the integrated system, which can greatly shorten the process flow, improve production efficiency, and reduce floor space. At the same time, the cascade recovery and utilization of calcium carbide waste heat can be achieved. Oxygen cooling, nitrogen contact heat transfer with calcium carbide, and calcium carbide radiation heat absorbed by carbon dioxide can respectively heat the water to be electrolyzed in a cascade manner. The cooling gas path and calcium carbide perform contact heat exchange, which greatly reduces the loss caused by the contact between water vapor and calcium carbide during the process, and effectively ensures the quality and production capacity of calcium carbide.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An integrated system for cascade recovery of calcium carbide waste heat, characterized by: It includes a waste heat recovery unit, a waste heat storage unit, and a recycling unit that are connected in sequence. The waste heat recovery unit includes a feeding device and a granulation device. The waste heat storage unit includes a low-temperature heat exchanger, a high-temperature dust collector, a medium-temperature heat exchanger, a high-temperature heat exchanger, a supplementary heat electric heater, a solid oxide electrolyzer, a preheating evaporator, a condenser, a hydrogen liquefaction storage device, an oxygen liquefaction storage device, a water supply pump, and a water supply treatment device; the recycling unit includes a hydrogen utilization module and an oxygen utilization module.

2. The integrated system for cascade recovery of calcium carbide waste heat according to claim 1 is characterized in that: The low-temperature heat exchanger is connected to the calcium carbide outlet of the granulation device, the inlet of the high-temperature dust collector is connected to the cooling gas phase outlet of the granulation device, and the high-temperature side inlet of the medium-temperature heat exchanger is connected to the outlet of the high-temperature dust collector; the high-temperature side outlet of the medium-temperature heat exchanger is connected to the gas phase inlet of the low-temperature heat exchanger through a circulating fan; the tube side inlet of the high-temperature heat exchanger is connected to the granulation device, and the tube side outlet of the high-temperature heat exchanger is connected to the granulation device through a compressor.

3. The integrated system for cascade recovery of calcium carbide waste heat according to claim 2 is characterized in that: The low-temperature side inlet of the medium-temperature heat exchanger is connected to the water side outlet of the preheating evaporator, and the water side inlet of the preheating evaporator is connected to the water treatment device through a water pump; the inlet of the water treatment device is connected to the liquid phase outlet of the condenser, the liquid phase inlet of the condenser is connected to the cathode outlet of the solid oxide electrolyzer, and the gas phase outlet of the condenser is connected to the hydrogen liquefaction storage device; The high-temperature side inlet of the preheating evaporator is connected to the anode outlet of the solid oxide electrolysis cell, and the high-temperature side outlet of the preheating evaporator is connected to the oxygen liquefaction storage device.

4. The integrated system for cascade recovery of calcium carbide waste heat according to claim 3 is characterized in that: The low temperature side outlet of the medium temperature heat exchanger is connected to the shell side inlet of the high temperature heat exchanger, and the shell side outlet of the high temperature heat exchanger is connected to the supplementary heat electric heater; the other end of the supplementary heat electric heater is connected to the solid oxide electrolytic cell.

5. A method for cascade recovery of calcium carbide waste heat, characterized in that: The integrated system for cascade recovery and utilization of calcium carbide waste heat as described in any one of claims 1 to 4 is implemented, and the specific cascade recovery and utilization method of calcium carbide waste heat is as follows: 1) The molten calcium carbide in the feeding device enters the granulating device through the lower discharge port. In the granulating device, it is centrifuged by the high-speed rotating cup-shaped liquid receiving plate and blown toward the inner wall of the granulating device shell by the cooling gas phase working medium. At this time, the cooling gas phase working medium and the granulated calcium carbide liquid undergo contact heat exchange; 2) After the contact heat exchange is completed, the cooling gas phase working medium enters the high-temperature dust collector from the cooling gas phase outlet of the granulation device for dust removal. The cooling gas phase working medium then enters the medium-temperature heat exchanger and performs non-contact heat exchange with the water vapor to be electrolyzed that has been preheated in the preheating evaporator. After the cooling gas phase working medium releases heat, it is pressurized by the circulating fan and pumped to the low-temperature heat exchanger; 3) The granulated calcium carbide particles enter the low-temperature heat exchanger from the granulation device, where they undergo direct contact heat exchange with the cooling gas phase. The heated cooling gas phase enters the cooling gas path of the granulation device. After deep cooling, the calcium carbide particles are transported to subsequent process flows by a calcium carbide transfer vehicle. 4) The circulating working fluid CO2 absorbs the radiant heat of the calcium carbide liquid in the radiant heat exchanger of the granulation device, and the temperature of CO2 rises. Then, CO2 enters the high-temperature heat exchanger and indirectly exchanges heat with the water vapor to be electrolyzed, transferring the heat to the water vapor to be electrolyzed. After releasing heat, CO2 is pressurized by the compressor and returned to the radiant heat exchanger to complete the cycle. 5) The feed water treatment device desalinates the feed water to be electrolyzed and then pressurizes it into the preheating evaporator via the feed water pump. It undergoes preliminary non-contact heat exchange with the high-temperature O2 generated at the anode of the solid oxide electrolytic cell. After the electrolysis feed water absorbs heat and evaporates, it enters the medium-temperature heat exchanger and undergoes non-contact heat exchange with the cooled gas phase working medium after dust removal. It then enters the high-temperature heat exchanger and undergoes non-contact heat exchange with the circulating working medium CO2. After the temperature of the electrolysis water vapor is further increased, it is supplemented by the supplementary heating electric heater according to the temperature control adjustment. 6) After the heat supplement is completed, the water vapor to be electrolyzed enters the cathode of the solid oxide electrolysis cell for electrolysis. The H2 produced at the cathode and the unreacted water vapor enter the condenser for cooling. The unreacted water vapor is condensed into liquid and removed for hydrogen purification. The condensed water is discharged from the liquid phase outlet and returned to the water treatment device for reuse, and the H2 enters the hydrogen liquefaction storage device.

6. The method for cascade recovery of calcium carbide waste heat according to claim 5, characterized in that: The cooling gas phase working medium is nitrogen or dehydrated air.

7. The method for cascade recovery of calcium carbide waste heat according to claim 5, characterized in that: In the high-temperature heat exchanger, the circulating working medium CO2 enters the tube side, and the electrolyzed water vapor enters the shell side for indirect heat exchange.

8. The method for cascade recovery of calcium carbide waste heat according to claim 5, characterized in that: In the solid oxide electrolyzer, the hydrogen generated by electrolysis is utilized through a hydrogen utilization module and transported to the hydrogen-requiring process in the plant, or the hydrogen and acetylene produced by calcium carbide are introduced into an ethylene tower together for hydrogenation reaction to produce ethylene.

9. The method for cascade recovery of calcium carbide waste heat according to claim 5, characterized in that: The oxygen after heat exchange in the preheating evaporator enters the oxygen liquefaction storage device, or is transported to the oxygen-demanding process in the plant, or enters the plant's own boiler unit through the oxygen utilization module for pure oxygen combustion.

Images