Method for preparing calcium sulfide through reaction of calcium oxide and gaseous sulfur and production system thereof

Abstract

The invention provides a method for preparing calcium sulfide through reaction of calcium oxide and gaseous sulfur and a production system thereof. The method comprises the following steps: heating and gasifying solid sulfur at 500-900 DEG C to form sulfur flue gas with the S2 volume content of 80% or above; preheating the calcium oxide powder to form preheated calcium oxide powder; respectively introducing the sulfur flue gas and the preheated calcium oxide powder into a suspension reactor for gas-solid reaction to generate calcium sulfide and tail gas; and cooling the calcium sulfide. The production system comprises a sulfur gasification device for gasifying solid sulfur; the suspension preheater is used for preheating calcium oxide powder; and the suspension reactor is respectively connected with the sulfur gasification device and the suspension preheater and is used for carrying out gas-solid reaction on calcium oxide powder and gaseous sulfur to generate calcium sulfide and tail gas. According to the method, high-purity calcium sulfide can be effectively prepared, pollution emission and energy consumption are effectively reduced, green production and manufacturing are achieved, and high economic value and social benefits are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of calcium sulfide preparation, and in particular relates to a method for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur and a system thereof. Background Art

[0002] Calcium sulfide (CaS) is an inorganic compound that usually appears as a light yellow to gray powder. It has a cubic crystal system with a sodium chloride structure, which makes calcium sulfide have high hardness and stability. Pure calcium sulfide is colorless, but sometimes has a rotten egg smell because it may contain impurities. Calcium sulfide is relatively stable in dry air, but it is easily hydrolyzed in a humid environment to produce a mixture of calcium hydrosulfide, calcium hydroxide and basic calcium hydrosulfide. Calcium sulfide is an important raw material for the manufacture of chemicals such as hydrogen sulfide and thiourea. In agriculture, calcium sulfide can be used as a soil conditioner to improve soil structure and fertility. In some medical studies, it is believed that it may be beneficial for the treatment of heart and vascular problems. Pure calcium sulfide doped with rare earth elements can be used as an electroluminescent material for the production of fluorescent lamps and other light sources. With the continuous deepening of new material technology research, calcium sulfide, as an important chemical intermediate product, will have a wider range of applications.

[0003] So far, the preparation method of calcium sulfide is mainly through the oxidation-reduction method. The reducing agents mainly include coal, coke, semi-coke, charcoal, hydrogen and carbon monoxide, and the oxidizing agents mainly include calcium sulfate, phosphogypsum, desulfurized gypsum and gypsum. At the same time, some of them are also prepared by acid-base neutralization method, mainly hydrogen sulfide and calcium oxide, limestone and dolomite. According to the state of the reactants for preparing calcium sulfide, it can be roughly divided into solid-solid method and gas-solid method. Among them, the gas-solid method is that the reactants react in gas-solid two-phase to prepare calcium sulfide, that is, gas reducing agents such as hydrogen and carbon monoxide react with calcium sulfate to reduce and prepare calcium sulfide. The reaction that occurs in this process is: CaSO4+4CO=CaS+4CO2

[0004] CaSO4+4H2=CaS+4H2O Summary of the invention

[0005] In order to solve the technical problems of high reaction temperature, high energy consumption, large carbon dioxide emission and low purity in the prior art of calcium sulfide production, the present invention provides a method and system for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur.

[0006] A method for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur, comprising heating solid sulfur at 500°C to 900°C to gasify it to form sulfur flue gas with an S2 volume content of more than 80%;

[0007] Preheating the calcium oxide powder to form preheated calcium oxide powder, the preheating temperature being 400° C. to 800° C.;

[0008] The sulfur fume and the preheated calcium oxide powder are respectively introduced into a suspension reactor for gas-solid reaction to generate calcium sulfide and tail gas, the gas-solid reaction temperature is 550° C. to 850° C., and the reaction time is 2S to 45S; the calcium sulfide is cooled.

[0009] Furthermore, the step of heating and gasifying solid sulfur at 500° C. to 900° C. to form sulfur flue gas with an S2 volume content of more than 80% comprises:

[0010] Heating solid sulfur to liquefy the solid sulfur to form sulfur liquid, wherein the temperature of heating the solid sulfur is between 100° C. and 200° C.;

[0011] Filtering the sulfur liquid to form refined sulfur liquid with a purity greater than 99%;

[0012] The refined sulfur liquid is continuously heated to gasify the refined sulfur liquid to form sulfur fume with an S2 volume content of more than 80%; the temperature for continuously heating the refined sulfur liquid is between 500°C and 900°C.

[0013] Furthermore, the refined sulfur liquid is further heated by direct heating, indirect heating, combustion and gasification or one or more combinations thereof.

[0014] Furthermore, the combustion gasification is to burn part of the gaseous sulfur to provide heat, while constructing an oxygen-deficient environment to inhibit oxidation.

[0015] Further, cooling the calcium sulfide comprises the following steps:

[0016] The calcium sulfide generated by the gas-solid reaction is separated by a high-temperature cyclone separator;

[0017] The separated calcium sulfide is introduced into at least one level of suspension cooling device to exchange heat with the low-temperature medium in the heat exchange tube of the suspension cooling device to cool the calcium sulfide to room temperature.

[0018] Furthermore, the purity of the calcium sulfide is greater than 40%.

[0019] Furthermore, the purity of the calcium sulfide is greater than 80%.

[0020] The present invention also provides a production system for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur, which is applicable to the above method for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur, and the system comprises a sulfur gasification device for gasifying solid sulfur;

[0021] A suspension preheater for preheating calcium oxide powder;

[0022] A suspension reactor connected to the sulfur gasification device and the suspension preheater respectively and used for gas-solid reaction of calcium oxide powder and gaseous sulfur to generate calcium sulfide and tail gas;

[0023] A suspension cooling device connected to the suspension reactor for cooling the calcium sulfide.

[0024] Further, a production system for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur also includes an indirect heat exchanger connected to the suspension cooling device and the sulfur gasification device respectively;

[0025] The indirect heat exchanger outputs low-temperature medium to the suspension cooling device, and the low-temperature medium is converted into high-temperature medium after heat exchange in the suspension cooling device and flows back to the indirect heat exchanger;

[0026] The indirect heat exchanger outputs low-pressure steam to the sulfur gasification device to heat the solid sulfur, and the low-pressure steam after heat exchange is converted into circulating water and refluxed to the indirect heat exchanger;

[0027] In the indirect heat exchanger, the high-temperature medium output by the suspension cooling device heats the circulating water to form the low-pressure steam output to heat the solid sulfur, and at the same time, the circulating water cools the high-temperature medium to form the low-temperature medium output to the suspension cooling device to cool the calcium sulfide.

[0028] Furthermore, a production system for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur also includes a tail gas incineration device connected to the air outlet of the suspension preheater for incinerating the tail gas; a gas dust removal device for removing dust from the tail gas; and the tail gas after dust removal by the gas dust removal device is subjected to heat exchange to prepare sulfuric acid.

[0029] The present invention heats solid sulfur at 500°C to 900°C to gasify it to form sulfur flue gas with a S2 volume content of more than 80%; preheats calcium oxide powder to form preheated calcium oxide powder, and the preheating temperature is 400°C to 800°C; introduces the sulfur flue gas and the preheated calcium oxide powder into a reactor for gas-solid reaction to generate calcium sulfide and tail gas, and cools the calcium sulfide. The present invention uses gaseous sulfur to directly react with calcium oxide to produce calcium sulfide, and the temperature of the gas-solid reaction is 550°C to 850°C, the reaction temperature is low, and the energy consumption is low; the contact is sufficient, the reaction is complete, and the purity of the produced calcium sulfide is high; at the same time, there is no carbon emission and no air pollution is caused.

[0030] In addition, the present invention also provides a calcium sulfide production system, which not only effectively solves the tail gas treatment in the production process and realizes the full recycling of production resources, but also realizes the recycling of heat in the production process, greatly reducing the energy consumption in the production process; effectively realizes green production and further improves the economic and social benefits of production. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0032] Figure 1 Schematic diagram of a process for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur provided in an embodiment of the present invention Figure 1 ;

[0033] Figure 2 A detailed schematic flow chart of process S10 of a method for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur provided in an embodiment of the present invention;

[0034] Figure 3 A detailed schematic diagram of a process 40 of a method for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur provided in an embodiment of the present invention;

[0035] Figure 4 A schematic diagram of the structure of a production system for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur provided in an embodiment of the present invention;

[0036] Figure 5 A schematic diagram of a production system for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur including energy recovery and recycling provided in an embodiment of the present invention;

[0037] Figure 6 A schematic diagram of the structure of a production system for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur provided in an embodiment of the present invention, including recycling of energy and production resources. DETAILED DESCRIPTION

[0038] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0039] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0040] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the drawings, and 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, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0041] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0042] See attached Figure 1 The first embodiment of the method for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur of the present invention comprises the following steps:

[0043] Step S10: heating and gasifying solid sulfur at 500° C. to 900° C. to form sulfur flue gas with an S2 volume content of more than 80%.

[0044] Specifically, refer to the attached Figure 2 The gasification of solid sulfur to form gaseous sulfur includes the following steps.

[0045] Step S11: heating solid sulfur to liquefy the solid sulfur to form sulfur liquid, wherein the temperature of heating the solid sulfur is between 100° C. and 200° C.

[0046] Step S12: filtering the sulfur liquid to form refined sulfur liquid with a purity greater than 99%;

[0047] Step S13: continue to heat the refined sulfur liquid to gasify the refined sulfur liquid to form sulfur fume with a volume content of S2 of more than 80%; the temperature for continuing to heat the refined sulfur liquid is between 500° C. and 900° C.

[0048] See attached Figure 4 , Attachment Figure 5 , Attachment Figure 6 Solid sulfur is placed in the sulfur melting tank of the sulfur gasification device 1 to complete the liquefaction of sulfur, the temperature is controlled at 100°C to 200°C, the time is 20 to 60s, the liquefaction temperature can be preferably 100°C, 130°C, 140°C, 150°C, 160°C or 200°C, and the liquefaction time can be preferably 20s, 30s, 40s, 50s or 60s, etc., which are not limited here. It is melted to form crude sulfur liquid.

[0049] The crude sulfur liquid is then filtered to remove the solid sulfur residue to avoid clogging the pumping pipe mouth, and refined sulfur liquid is formed after filtration.

[0050] The refined sulfur liquid is heated at a temperature of 120-150°C, pumped and metered into the sulfur gasifier; the atomizing nozzle atomizes the refined sulfur liquid, and continues to overheat through combustion and gasification to produce high-temperature sulfur gas S2. The chemical reaction equation is: S8=2S 4aq =4S2↑, and then S2 is sent into the suspension reactor through a Venturi ejector. The temperature range of S2 is 500-900°C, and the flow rate range is 80-100kg / h. The temperature of S2 can preferably be 500°C, 600°C, 700°C, 800°C, 900°C, etc., which is not limited here.

[0051] The combustion gasification in the present invention generates sulfur flue gas with a S2 volume content of more than 80% by burning part of the gas sulfur to provide heat. At the same time, an oxygen-deficient environment is constructed to inhibit additional oxidation reactions, thereby reducing direct or indirect heating energy consumption, improving energy utilization efficiency, and ensuring efficient and low-consumption operation of the gas sulfur gasification process to meet the energy economy and stability requirements of the process system.

[0052] It should be noted that the gas leaving the sulfur gasification device 1 may include a small amount of SO2 in addition to sulfur gas, and the volume content of the sulfur gas S2 is above 80%, preferably 81%, 85%, 91%, 95%, 96%, 97%, 99%, etc., which is not limited here.

[0053] Step S20: preheating the calcium oxide powder to form preheated calcium oxide powder, the preheating temperature being 400° C. to 800° C.;

[0054] The calcium oxide powder meeting the predetermined particle size is introduced into the suspension preheater 2 for preheating. The suspension preheater 2 adopts a multi-stage cyclone heat exchanger. First, the calcium oxide powder is introduced into the heat exchange tube of the first-stage cyclone preheater for heat exchange, and then enters the second-stage cyclone preheating. After multi-stage cyclone heat exchange, the calcium oxide powder discharge pipe introduces the calcium oxide powder into the suspension reactor for reaction. The particle size of the preheated calcium oxide powder is below 80 μm, preferably 78 μm, 76 μm, 72 μm, 70 μm, 65 μm, 60 μm, 55 μm, 50 μm, 45 μm, 40 μm, etc., which is not limited here. The preheating temperature is 800°C, 850°C, 900°C, 950 or 1000°C, which is not limited here. In addition, the suspension preheater can be single-row or double-row.

[0055] Step S30: introducing the sulfur fume and the preheated calcium oxide powder into the suspension reactor 3 respectively for gas-solid reaction to generate calcium sulfide and tail gas, wherein the gas-solid reaction temperature is 550° C. to 850° C. and the reaction time is 2S to 45S.

[0056] The calcium sulfide powder and gaseous sulfur that meet the requirements are introduced into the suspension reactor for gas-solid reaction. The time for the gaseous sulfur and calcium oxide powder to undergo gas-solid reaction is 2S to 45S; it can be 2S, 5S, 10S, 15S, 20S, 25S, 26S, 30S, 35S, 40S, 45S, etc., which are not specifically limited here. The temperature of the gas-solid reaction is 550℃ to 850℃, which can be 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, etc., which are not specifically limited here. The produced calcium sulfide product will be introduced into the reactor for cooling to room temperature for subpackaging after cyclone separation.

[0057] The chemical reaction equation of gaseous sulfur and calcium oxide powder is 4CaO+3S2=4CaS+2SO2. The obtained calcium sulfide product has high purity and does not contain impurities such as calcium sulfate and calcium sulfite. The main component of the waste gas produced by the reaction is sulfur dioxide, which can be recycled to produce sulfuric acid, reduce environmental pollution, realize the recycling and comprehensive utilization of resources, and achieve green production.

[0058] In a specific implementation, the suspension reactor 3 can be a downstream transport bed reactor, a fluidized bed reactor or a rotary kiln reactor.

[0059] When a co-current conveying bed reactor is used, the preheated high-temperature calcium oxide powder from the preheating process is fed to the bottom of the co-current conveying bed reactor, and the high-temperature gaseous sulfur flue gas formed by the gasification of solid sulfur enters the bottom of the settling bed, and is carried by the high-temperature gaseous sulfur flue gas from bottom to top through the co-current conveying bed reactor in a dilute phase transport state, and quickly completes the gas-solid reduction reaction, and then enters the high-temperature cyclone separator for gas-solid separation. The separated high-temperature calcium sulfide powder enters the product cooling process, and the separated high-temperature tail gas enters the raw material calcium oxide preheating process.

[0060] When a fluidized bed reactor is used, the preheated high-temperature calcium oxide powder is placed in the middle of the reaction section, and a high-temperature inert gas is introduced to it to make it vigorously agitated in a fluidized state. The high-temperature gaseous sulfur formed by the gasification of solid sulfur enters from the bottom of the reactor, fully contacts with the solid calcium oxide powder in a fluidized state, and quickly completes the gas-solid mass transfer reaction. Another point is that the fluidized bed reactor has an external circulation, and a part of the reaction materials are circulated once or multiple times in the fluidized bed reactor to fully realize the gas-solid reaction.

[0061] When a rotary kiln reactor is used, the preheated high-temperature calcium oxide powder is fed into the kiln tail at a given speed. The high-temperature gaseous sulfur flue gas formed by the gasification of solid sulfur enters from the kiln head and flows in the opposite direction to the calcium oxide powder. Under the rotation of the rotary kiln, the materials are mixed, heated, and gas-solid reacted. The final product is collected from the kiln head and enters the next process.

[0062] Step S40: cooling the calcium sulfide;

[0063] Cooling calcium sulfide includes the following steps:

[0064] Step S41: gas-solid separation of the produced calcium sulfide powder

[0065] Refer to the attached Figure 4 , Attachment Figure 5 , Attachment Figure 6 The generated high temperature calcium sulfide powder suspension fluid is introduced into the cyclone separator for gas-solid separation. The cyclone separator can be installed at the tail end of the suspension reactor 3 or at the front end of the suspension cooling device 4. The present invention adopts the method of installing the cyclone separator at the tail end of the suspension reactor to constitute a component of the suspension reactor 3.

[0066] Step S42: introducing the separated calcium sulfide into at least one level of suspension cooling device 4 to exchange heat with the low-temperature medium in the heat exchange tube of the suspension cooling device to cool the calcium sulfide to room temperature.

[0067] The separated high-temperature calcium sulfide powder enters the heat exchange tube of the suspension cooling device 4 through the discharge pipe of the cyclone separator, and exchanges heat with the low-temperature medium in the heat exchange tube, thereby achieving the purpose of cooling the calcium sulfide to room temperature. The low-temperature medium can be water or an inert gas, and its temperature is lower than the temperature of the generated calcium sulfide; the low-temperature medium used in the present invention is an inert gas. For example, when the low-temperature medium is an inert gas, the generated calcium sulfide completes heat exchange with the low-temperature inert gas in the heat exchange tube. The inert gas can be nitrogen, argon, carbon dioxide and other gases that do not react with calcium sulfide. After the high-temperature calcium sulfide is cooled to room temperature, it finally enters the product transportation, storage and packaging unit through the discharge pipe of the suspension cooling device 4 for packaging, and the low-temperature inert gas is converted into a high-temperature inert gas.

[0068] Furthermore, the refined sulfur liquid is further heated by at least one direct heating, combustion gasification or / and indirect heating. In the specific implementation, resistance heating, electromagnetic induction heating, microwave heating, plasma heating or a combination thereof may be used; or an indirect heating method using one or more high-temperature flue gases such as coal, natural gas, liquefied gas, fuel oil, industrial coal gas, hydrogen, and CO as fuels may be used.

[0069] In order to further optimize the gas-solid reaction effect, improve the purity of calcium sulfide and reduce energy consumption, the temperature of the gas-solid reaction is controlled at including but not limited to 550°C, 600°C, 650°C, 700°C, 750°C, 775°C, 800°C, 825°C, and 850°C.

[0070] The purity of calcium sulfide produced by the gas-solid reaction of the present invention according to the molar ratio of gaseous sulfur and calcium oxide, reaction temperature and reaction time is >40%, further optimized to >50%, >60%, >70%, >80%, >85%, 90%; 95%; no more details are given here.

[0071] Step S50: Systematic and comprehensive utilization of energy

[0072] Furthermore, the present invention also includes an indirect heat exchanger that realizes energy recycling and further reduces energy consumption, thereby achieving green production.

[0073] Step S51: Energy recycling of the suspension cooling device and the solid sulfur gasification device

[0074] See attached Figure 5 , Attachment Figure 6 The low-temperature medium used in the present invention is a low-temperature inert gas. The high-temperature inert gas formed by the low-temperature inert gas after heat exchange in the suspension cooling device is introduced into the indirect heat exchanger to heat the circulating water to form low-pressure steam, and then the low-pressure steam is introduced to heat and gasify the solid sulfur; after the low-pressure steam completes the heat exchange, it forms circulating water and flows back to the indirect heat exchanger, absorbs the heat of the high-temperature inert gas and is converted into low-pressure steam. At the same time, the high-temperature inert gas is converted into a low-temperature inert gas and flows back to the suspension cooling device to cool the calcium sulfide produced by the gas-solid reaction. The heat absorbed by the high-temperature calcium sulfide powder during cooling is effectively fully applied to the gasification production process of solid sulfur, and the heat generated by the cooling of the high-temperature calcium sulfide is applied to the gasification process of solid sulfur to heat and liquefy the solid sulfur. At the same time, the production cost of cooling the high-temperature calcium sulfide powder is also reduced, and there is no need to increase the cost of cooling the high-temperature calcium sulfide powder, which realizes the integration and comprehensive application of energy use system, reduces the production cost, and realizes green production.

[0075] Step S52: recycling the energy of the suspension reactor and the sulfur gasification device; and recycling the SO2 in the tail gas.

[0076] Further, see Attachment Figure 6, and also includes removing dust from the tail gas after preheating the calcium oxide powder to prepare sulfuric acid. Since the gaseous S2 and the high-temperature calcium oxide powder undergo a gas-solid reaction in a suspended flow state in a high-temperature environment, the reaction environment temperature is 550°C to 850°C, and the tail gas temperature after the reaction to produce calcium sulfide is relatively high. In addition, since the temperature requirement for preheating the calcium oxide powder reaches 400°C to 800°C, the preheated tail gas also contains a large amount of heat. The present invention introduces the above-mentioned tail gas into an indirect heat exchanger for heat exchange, especially heats the circulating water in the indirect heat exchanger to form low-pressure steam and applies it to the solid sulfur liquefaction in the solid sulfur gasification process, fully absorbs and uses the heat in the tail gas, further improves the comprehensive utilization efficiency of the system energy, reduces the system energy consumption, reduces production costs, and promotes green production with significant economic value and social benefits. At the same time, since the solid sulfur gasification process will contain a small amount of SO2, and the main tail gas of the gas-solid reaction is also SO2, the production of sulfuric acid after dust removal of the above tail gas will maximize the utilization of production resources. The production process of this technical solution achieves zero solid pollutants and no polluting gas emissions, realizes systematic and comprehensive recycling of energy, low energy consumption and cost, and green and environmentally friendly production.

[0077] The following is described in detail by specific embodiments:

[0078] Example 1: Calcium oxide powder with a particle size of less than or equal to 80 μm is introduced into a suspension reactor, the molar ratio of gaseous sulfur to calcium oxide is 2:1, the gas-solid reaction time is 5S, the gas-solid reaction temperature is 550°C, and the purity of the generated calcium sulfide is 44%.

[0079] Example 2: Calcium oxide powder with a particle size of less than or equal to 80 μm is introduced into a suspension reactor, the molar ratio of gaseous sulfur to calcium oxide is 2.5:1, the gas-solid reaction time is 15 seconds, the gas-solid reaction temperature is 600° C., and the purity of the generated calcium sulfide is 62%.

[0080] Embodiment 3: calcium oxide powder with a particle size of less than or equal to 80 μm is introduced into the suspension reactor, the molar ratio of gaseous sulfur to calcium oxide is 3:1, the gas-solid reaction time is 30 seconds, the gas-solid reaction temperature is 650° C., and the purity of the generated calcium sulfide is 81%.

[0081] Example 4: Calcium oxide powder with a particle size of less than or equal to 80 μm is introduced into a suspension reactor, the molar ratio of gaseous sulfur to calcium oxide is 2.5:1, the gas-solid reaction time is 15 seconds, the gas-solid reaction temperature is 700° C., and the purity of the generated calcium sulfide is 74%.

[0082] Example 5: Calcium oxide powder with a particle size of less than or equal to 80 μm is introduced into a suspension reactor, the molar ratio of gaseous sulfur to calcium oxide is 3:1, the gas-solid reaction time is 30 seconds, the gas-solid reaction temperature is 750° C., and the purity of the generated calcium sulfide is 91%.

[0083] Example 6: Calcium oxide powder with a particle size of less than or equal to 80 μm is introduced into the suspension reactor, the molar ratio of gaseous sulfur to calcium oxide is 3:1, the gas-solid reaction time is 40 seconds, the gas-solid reaction temperature is 800° C., and the purity of the generated calcium sulfide is 94%.

[0084] Example 7: Calcium oxide powder with a particle size of less than or equal to 80 μm is introduced into the suspension reactor, the molar ratio of gaseous sulfur to calcium oxide is 2.5:1, the gas-solid reaction time is 40 seconds, the gas-solid reaction temperature is 825° C., and the purity of the generated calcium sulfide is 92%.

[0085] Embodiment 8: calcium oxide powder with a particle size of less than or equal to 80 μm is introduced into the suspension reactor, the molar ratio of gaseous sulfur to calcium oxide is 2.5:1, the gas-solid reaction time is 45 seconds, the gas-solid reaction temperature is 850° C., and the purity of the generated calcium sulfide is 95%.

[0086] The present invention also provides a production system for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur, which is applicable to the method for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur in each embodiment of the present invention. Figure 4 As shown, the system includes a sulfur gasification device 1 for gasifying solid sulfur; a suspension preheater 2 for preheating calcium oxide powder; a suspension reactor 3 connected to the sulfur gasification device 1 and the suspension preheater 2 respectively for performing a gas-solid reaction between calcium oxide powder and gaseous sulfur to generate calcium sulfide and tail gas; the final discharge pipe of the suspension preheater 2 is connected to the first feed port of the suspension reactor 3, and the sulfur gasification device 1 is connected to the second feed port of the suspension reactor 3; and a suspension cooling device 4 connected to the discharge port of the suspension reactor 3 for cooling the calcium sulfide.

[0087] During operation, the suspended fluidized calcium oxide powder with moisture and particle size meeting the predetermined values ​​is introduced into the suspension preheater 2; the calcium oxide powder is preheated by the multi-stage cyclone of the suspension preheater 2, and the temperature of the calcium oxide powder reaches the predetermined temperature, and then the calcium oxide powder enters the suspension reactor 3 from the suspension preheater 2 for gas-solid reaction. On another path, after the solid sulfur is liquefied and gasified by the sulfur gasification device 1, the gaseous sulfur reaches the predetermined temperature and enters the suspension reactor 2 from the sulfur gasification device 1 for gas-solid reaction with the calcium oxide powder. The calcium sulfide generated by the reaction is separated by a cyclone and then enters the suspension cooling device 4 to be cooled to room temperature.

[0088] In order to further reduce energy consumption, improve energy efficiency, reduce production costs and improve production economic benefits, such as the attached Figure 5As shown, the production system also includes an indirect heat exchanger 5 connected to the suspension cooling device 4 and the sulfur gasification device 1 respectively. The indirect heat exchanger 5 outputs a low-temperature cooling medium to the suspension cooling device 4, and the low-temperature cooling medium is converted into a high-temperature medium after heat exchange in the suspension cooling device 4 and flows back to the indirect heat exchanger 5. The indirect heat exchanger 5 outputs low-pressure steam to the sulfur gasification device 1 to heat the solid sulfur, and the low-pressure steam after heat exchange is converted into circulating water and flows back to the indirect heat exchanger 5; in the indirect heat exchanger 5, the high-temperature medium output by the suspension cooling device 4 heats the circulating water to form a low-pressure steam output to heat the solid sulfur, and at the same time, the circulating water cools the high-temperature medium to form a low-temperature medium output to the suspension cooling device to cool the calcium sulfide. The above-mentioned low-temperature medium can be any one of water and inert gas, and its temperature is lower than the temperature of the generated calcium sulfide; the low-temperature medium used in the present invention is an inert gas. For example, when the low-temperature medium is an inert gas, the generated calcium sulfide completes heat exchange with the low-temperature inert gas in the suspension cooling device. The inert gas can be nitrogen, argon, carbon dioxide and other gases that do not react with calcium sulfide.

[0089] As attached Figure 6 As shown, in order to further improve the resource utilization efficiency, it also includes a gas dust removal device 6 connected to the air outlet of the suspension preheater 2 for dust removal of the tail gas; the gas dust removal device 6 is used to remove dust from the tail gas after the gas-solid reaction after preheating the calcium oxide powder by the suspension preheater 2. The above tail gas may contain calcium sulfide and calcium oxide powder. After the above tail gas is dusted, the above tail gas is introduced into the indirect heat exchanger 5, and the heat of the above tail gas is further fully utilized. The circulating water in the indirect heat exchanger 5 is heated to form low-pressure steam and output to the sulfur gasification device 1 to heat the solid sulfur to liquefy it. After cooling, the tail gas containing a large amount of sulfur dioxide is collected by the sulfuric acid preparation device 7 to prepare sulfuric acid. A tail gas incineration device 8 is also arranged in the middle of the gas dust removal device 6 of the suspension preheater 2. The tail gas coming out of the suspension preheater 2 may contain part of the gaseous sulfur, which is incinerated to form sulfur dioxide.

[0090] 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 in the protection scope of the present invention.

Claims

1. A method for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur, characterized in that: Solid sulfur is heated and gasified at 500°C to 900°C to form sulfur flue gas with an S2 volume content of more than 80%; Preheating the calcium oxide powder to form preheated calcium oxide powder, the preheating temperature being 400° C. to 800° C.; The sulfur fume and the preheated calcium oxide powder are respectively introduced into a suspension reactor for gas-solid reaction to generate calcium sulfide and tail gas, the gas-solid reaction temperature is 550° C. to 850° C., and the reaction time is 2S to 45S; the calcium sulfide is cooled.

2. The method for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur as claimed in claim 1, characterized in that: The step of heating and gasifying solid sulfur at 500° C. to 900° C. to form sulfur flue gas with an S2 volume content of more than 80% comprises: Heating solid sulfur to liquefy the solid sulfur to form sulfur liquid, wherein the temperature of heating the solid sulfur is between 100° C. and 200° C.; Filtering the sulfur liquid to form refined sulfur liquid with a purity greater than 99%; The refined sulfur liquid is continuously heated to gasify the refined sulfur liquid to form sulfur fume with an S2 volume content of more than 80%; the temperature for continuously heating the refined sulfur liquid is between 500°C and 900°C.

3. The method for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur as claimed in claim 2, characterized in that: The refined sulfur liquid is further heated by direct heating, indirect heating, combustion gasification or a combination of one or more thereof.

4. The method for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur as claimed in claim 3, characterized in that: The combustion gasification is to burn part of the gaseous sulfur to provide heat and at the same time create an oxygen-deficient environment to inhibit oxidation.

5. A method for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur as claimed in any one of claims 1 to 4, characterized in that: Cooling the calcium sulfide comprises the following steps: The calcium sulfide generated by the gas-solid reaction is separated by a cyclone separator; The separated calcium sulfide is introduced into at least one level of suspension cooling device to exchange heat with the low-temperature medium in the heat exchange tube of the suspension cooling device to cool the calcium sulfide to room temperature.

6. The method for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur as claimed in claim 5, characterized in that: The purity of the calcium sulfide is >40%.

7. The method for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur as claimed in claim 6, characterized in that: The purity of the calcium sulfide is >80%.

8. A production system for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur, characterized in that: A method for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur as claimed in any one of claims 1 to 7, wherein the system comprises a sulfur gasification device for gasifying solid sulfur; A suspension preheater for preheating calcium oxide powder; A suspension reactor connected to the sulfur gasification device and the suspension preheater respectively and used for gas-solid reaction of calcium oxide powder and gaseous sulfur to generate calcium sulfide and tail gas; A suspension cooling device connected to the suspension reactor for cooling the calcium sulfide.

9. The production system for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur as claimed in claim 8, characterized in that: It also includes indirect heat exchangers connected to the suspension cooling device and the sulfur gasification device respectively; The indirect heat exchanger outputs low-temperature medium to the suspension cooling device, and the low-temperature medium is converted into high-temperature medium after heat exchange in the suspension cooling device and flows back to the indirect heat exchanger; The indirect heat exchanger outputs low-pressure steam to the sulfur gasification device to heat the solid sulfur, and the low-pressure steam after heat exchange is converted into circulating water and refluxed to the indirect heat exchanger; In the indirect heat exchanger, the high-temperature medium output by the suspension cooling device heats the circulating water to form the low-pressure steam output to heat the solid sulfur, and at the same time, the circulating water cools the high-temperature medium to form the low-temperature medium output to the suspension cooling device to cool the calcium sulfide.

10. The production system for preparing calcium sulfide by reacting calcium oxide with gaseous sulfur as claimed in claim 9, characterized in that: It also includes a tail gas incineration device connected to the air outlet of the suspension preheater for incinerating the tail gas; a gas dust removal device for removing dust from the tail gas; and the tail gas after dust removal by the gas dust removal device is subjected to heat exchange to prepare sulfuric acid.

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