Calcium sulfide preparation method and production system thereof

Abstract

The invention provides a calcium sulfide preparation method and production system, and the method comprises the following steps: gypsum powder is preheated and dehydrated, and the preheating temperature is 800-900 DEG C; heating the solid sulfur to 500-900 DEG C to generate sulfur gas; the sulfur gas and the preheated gypsum powder are introduced into a suspension reactor for a reduction reaction, calcium sulfide and tail gas are generated, the reaction temperature is controlled to range from 800 DEG C to 1200 DEG C, and the tail gas comprises SO2; and the calcium sulfide is cooled. According to the calcium sulfide preparation method provided by the invention, the solid sulfur is used as a reaction raw material to produce calcium sulfide, so that the problems of long reaction time, low efficiency, low calcium sulfide quality and the like in production of calcium sulfide by reducing gypsum with sulfur in the prior art are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of calcium sulfide preparation, and in particular relates to a calcium sulfide preparation method and a production system thereof. Background Art

[0002] Calcium sulfide is an inorganic compound widely used in the rubber industry and leather industry as an additive in the rubber vulcanization process; it can also be used as an additive in the mineral processing process; in the preparation of other chemical substances, calcium sulfide can be used as a reducing agent or vulcanizing agent. With the continuous deepening of new material technology research, calcium sulfide, as an important chemical intermediate product, will have a wider range of applications. my country's industrial by-product gypsum production and existing reserves are huge. Reduction reaction of gypsum to generate calcium sulfide is an effective way to fully utilize the sulfur and calcium resources in gypsum.

[0003] Although patent CN 101708825 A discloses a method for preparing calcium sulfide by reducing and decomposing gypsum with sulfur, it uses gaseous sulfur as a reducing gas to prepare calcium sulfide. However, its raw material uses finished sulfur gas, which has a high procurement cost and transportation difficulty; secondly, the reduction reaction time of sulfur gas and gypsum is 0.5-2h, the reaction time is long and the efficiency is low; the experiment was only verified in a quartz tube suspension reactor, and no device and production process suitable for this method were designed. Therefore, it is of great social environmental and economic value to develop a method and system with simple process, low cost, stable system, high production efficiency, short reaction time and low energy consumption to produce high-purity calcium sulfide. Summary of the invention

[0004] The main purpose of the present invention is to provide a calcium sulfide preparation method and a calcium sulfide production system, aiming to solve the technical problems of the existing production of calcium sulfide using sulfur-reduced gypsum, such as long reaction time, low efficiency, and low quality of calcium sulfide.

[0005] To achieve the above object, the present invention provides a method for preparing calcium sulfide, which comprises the following steps:

[0006] Preheating and dehydrating the gypsum powder, wherein the preheating temperature is 800° C. to 900° C.;

[0007] Heat solid sulfur to 500℃~900℃ to generate sulfur gas;

[0008] The sulfur gas and the preheated gypsum powder are introduced into a suspension reactor for reduction reaction to generate calcium sulfide and tail gas, the reaction temperature is controlled at 800° C. to 1200° C., and the tail gas includes SO2;

[0009] The calcium sulfide is cooled.

[0010] Optionally, the step of heating solid sulfur to 500° C. to 900° C. to generate sulfur gas comprises:

[0011] The solid sulfur is heated and liquefied to generate liquid sulfur, and the temperature is controlled at 120℃~150℃;

[0012] The sulfur liquid is heated and gasified to generate sulfur gas. The temperature of the sulfur gas is controlled at 500° C. to 900° C., and the volume content of S2 in the sulfur gas is 10 to 100%.

[0013] Optionally, the method of heating and gasifying the sulfur liquid is one of indirect heating gasification and oxygen-deficient combustion gasification, or a combination of both.

[0014] Optionally, the step of cooling the calcium sulfide comprises:

[0015] A low-temperature inert gas is used to exchange heat with the generated calcium sulfide to cool the generated calcium sulfide to room temperature, and the low-temperature inert gas is converted into a high-temperature inert gas, wherein the temperature of the generated calcium sulfide is greater than that of the low-temperature inert gas, and the temperature of the low-temperature inert gas is lower than that of the high-temperature inert gas.

[0016] Optionally, it also includes:

[0017] Exchanging heat between the high-temperature inert gas and low-temperature air and circulating cold water, the high-temperature inert gas is converted into the low-temperature inert gas, the low-temperature air is converted into high-temperature air, and the circulating cold water is converted into low-pressure steam, wherein the temperature of the high-temperature air is greater than the temperature of the low-temperature air, the temperature of the low-temperature air and the temperature of the circulating cold water are both lower than the temperature of the high-temperature inert gas, and the temperature of the low-pressure steam is greater than the temperature of the circulating cold water;

[0018] The high-temperature air is used to heat the sulfur liquid, and the high-temperature air is converted into the low-temperature air;

[0019] The low-pressure steam is used to heat the sulfur solid, and the low-pressure steam is converted into the circulating cold water.

[0020] Optionally, the method further includes: using tail gas to preheat the gypsum powder.

[0021] Optionally, the method further comprises: preparing sulfuric acid by using the tail gas obtained by preheating the gypsum powder and performing gas dust removal.

[0022] In addition, to achieve the above-mentioned purpose, the present invention provides a calcium sulfide production system, which is applied to the aforementioned calcium sulfide preparation method, and the calcium sulfide production system comprises: a suspension preheater, a suspension reactor, a suspension cooler and a sulfur gasification unit;

[0023] The discharge pipe of the final cyclone preheater of the suspension preheater is connected to the first feed port of the suspension reactor;

[0024] The discharge pipe of the gas-solid separator of the suspension reactor is connected to the feed port of the first-stage cyclone cooler of the suspension cooler, and the air outlet pipe of the gas-solid separator of the suspension reactor is connected to the heat exchange pipe of the final-stage cyclone preheater of the suspension preheater;

[0025] The discharge pipe of the sulfur gasification unit is communicated with the second feed port of the suspension reactor.

[0026] Optionally, the calcium sulfide production system further comprises: an indirect heat exchanger and a sulfur liquefaction unit connected to the sulfur gasification unit;

[0027] The air outlet pipe of the first-stage cyclone cooler of the suspension cooler is connected to the heat exchange pipe of the indirect heat exchanger;

[0028] The air outlet pipe of the indirect heat exchanger is connected to the heat exchange pipe of the sulfur liquefaction unit and the heat exchange pipe of the sulfur gasification unit, or the air outlet pipe of the indirect heat exchanger is connected to the heat exchange pipe of the sulfur liquefaction unit;

[0029] The discharge pipe of the sulfur gasification unit is communicated with the second feed port of the suspension reactor.

[0030] Optionally, the calcium sulfide production system further comprises: a gas dust removal unit and a sulfuric acid preparation unit;

[0031] The air outlet of the first-stage cyclone preheater of the suspension preheater is connected to the air inlet of the gas dust removal unit;

[0032] The exhaust port of the gas dust removal unit is communicated with the sulfuric acid preparation unit.

[0033] The present invention proposes a method for preparing calcium sulfide and a production system thereof, wherein gypsum powder is preheated and dehydrated, the preheating temperature is 800°C to 900°C; solid sulfur is heated to 500°C to 900°C to generate sulfur gas; the sulfur gas and the preheated gypsum powder are introduced into a suspension reactor for reduction reaction to generate calcium sulfide and tail gas, the reaction temperature is controlled at 700°C to 1000°C; and the calcium sulfide is cooled. Solid sulfur is used as a raw material, solid sulfur is heated to generate gaseous sulfur, and the sulfur reacts with gypsum to generate calcium sulfide. Since the sulfur is in a gaseous state, the contact area between sulfur and gypsum is increased, the reaction is more complete, and the reaction efficiency of sulfur and gypsum is improved, thereby reducing the reaction time of sulfur reducing gypsum to generate calcium sulfide, and the generated product has a higher content of calcium sulfide and less content of unreacted gypsum or sulfur, that is, the quality of the generated calcium sulfide is improved. Thus, the problems of long reaction time, low efficiency and low quality of calcium sulfide produced by reducing gypsum with sulfur in the prior art are solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] 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.

[0035] Figure 1 A schematic flow chart of a first embodiment of a method for preparing calcium sulfide provided by an embodiment of the present invention;

[0036] Figure 2 A detailed schematic diagram of the process of step S20 in the method for preparing calcium sulfide provided in an embodiment of the present invention;

[0037] Figure 3 A schematic diagram of the structure of a calcium sulfide production system provided in an embodiment of the present invention Figure 1 ;

[0038] Figure 4 A schematic diagram of the structure of a calcium sulfide production system provided in an embodiment of the present invention Figure 2 ;

[0039] Figure 5 A schematic diagram of the structure of a calcium sulfide production system provided in an embodiment of the present invention Figure 3 .

[0040] Figure Number:

[0041] 1. Suspension preheater; 2. Suspension reactor; 3. Sulfur gasification unit; 4. Suspension cooler; 5. Indirect heat exchanger; 6. Gas dust removal unit; 7. Sulfuric acid preparation unit; 8. Sulfur liquefaction unit.

[0042] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] Reference Figure 1-Figure 5 In the first embodiment of the method for preparing calcium sulfide of the present invention, the method for preparing calcium sulfide comprises the steps of:

[0048] Step S10, preheating and dehydrating the gypsum powder, wherein the preheating temperature is 150° C. to 250° C.;

[0049] The gypsum raw material is metered into the suspension preheater 1 for preheating so as to remove the moisture in the gypsum, which includes free water and combined water.

[0050] Specifically, the gypsum raw material is fed into the heat exchange tube of the first stage cyclone preheater of the suspension preheater 1 by metering, where free water is removed, and the chemical reaction equation is: CaSO4·2H2O=CaSO4·1 / 2H2O+3 / 2H2O, and the temperature range is 150-180°C, and 150°C, 160°C, 170°C or 180°C, etc., can be preferably used, and are not limited here. After gas-solid separation in the cylinder of the first stage cyclone preheater, it enters the heat exchange tube of the second stage cyclone preheater through the discharge pipe, and the combined water is removed in the last three stages of preheaters, and the chemical reaction equation is: CaSO4·1 / 2H2O=CaSO4+1 / 2H2O, and the temperature range is 200-250°C, and 200°C, 210°C, 220°C, 230°C, 240°C or 250°C, etc., can be preferably used, and are not limited here. After gas-solid separation in the final cyclone preheater, the gypsum enters the suspension reactor 2 through the discharge pipe. The gypsum particle size entering the suspension reactor 2 is in the range of 10 to 80 μm, the temperature is in the range of 200 to 250° C., and the flow rate is in the range of 500 to 600 kg / h.

[0051] It should be noted that the particle size of the gypsum entering the suspension reactor 2 may preferably be 10 μm, 20 μm, 40 μm, 60 μm, 80 μm, etc., which is not limited here, and the temperature may preferably be 800° C., 820° C., 830° C., 840° C., 860° C. or 900° C., etc., which is not limited here. The flow rate range may preferably be 500 kg / h, 520 kg / h, 540 kg / h, 560 kg / h, 580 kg / h or 600 kg / h, etc., which is not limited here.

[0052] Step S20, heating solid sulfur to 500° C. to 900° C. to generate sulfur gas;

[0053] Solid sulfur is heated to 500° C. to 900° C., so that the sulfur changes from a solid state to sulfur gas, and the sulfur gas is introduced into the suspension reactor 2 .

[0054] Specifically, refer to Figure 2 , step S20 comprises:

[0055] Step S21, heating and liquefying solid sulfur to generate liquid sulfur, with the temperature controlled at 120° C. to 150° C.;

[0056] Step S22, heating and gasifying the sulfur liquid to generate sulfur gas, wherein the temperature of the sulfur gas is controlled at 500° C. to 900° C., and the volume content of S2 in the sulfur gas is 10 to 100%.

[0057] Solid sulfur is placed in the sulfur melting tank of the sulfur liquefaction unit 8 to complete the liquefaction of sulfur, the temperature is controlled at 120-150°C, the time is 20-60s, the liquefaction temperature can be preferably 120°C, 130°C, 140°C or 150°C, etc., the liquefaction time can be preferably 20s, 30s, 40s, 50s or 60s, etc., which are not limited here. The crude sulfur liquid is melted to form a crude sulfur liquid, and then the crude sulfur liquid is filtered to filter out the residue of solid sulfur to avoid clogging the pumping pipe mouth, and refined sulfur liquid is formed after filtration.

[0058] The refined sulfur liquid is heated at a temperature of 120-150°C, and is pumped and metered into the sulfur gasification unit 3; the atomizing nozzle in the sulfur gasification unit 3 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 2 through the 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 be preferably 500°C, 600°C, 700°C, 800°C, 900°C, etc., which are not limited here. The flow rate of S2 can be preferably 80kg / h, 85kg / h, 90kg / h, 95kg / h or 100kg / h, etc., which are not limited here.

[0059] It should be noted that the gas leaving the sulfur gasification unit 3 may include a small amount of SO2 in addition to sulfur gas, and the volume content of sulfur gas S2 is 10-100%, preferably 20%, 30%, 50%, 70%, 80%, 90% or 100%.

[0060] Step S30, introducing the sulfur gas and the preheated gypsum powder into the suspension reactor 2 for reduction reaction to generate calcium sulfide and tail gas, and the reaction temperature is controlled at 800° C. to 1000° C.;

[0061] The preheated and dehydrated gypsum and sulfur gas are added to the suspension reactor 2 in a mass ratio of (6-6.5):1, the preheated gypsum powder from the preheating process enters the bottom of the suspension reactor 2, and the high-temperature sulfur gas from the raw sulfur combustion and gasification process enters the bottom of the settling bed of the suspension reactor 2, and passes through the suspension reactor 2 from bottom to top in a dilute phase transport state under the carry-over of the high-temperature sulfur gas, and quickly completes the gas-solid reduction reaction to generate products of calcium sulfide and sulfur dioxide, wherein the reaction temperature of the gas-solid reaction is 800°C to 1200°C, which can be 800°C, 850°C, 900°C, 950°C, 1000°C, 1100°C, 1200°C, etc., which is not limited here, and the average reaction time is 1 to 15s, which can be 1s, 2s, 4s, 6s, 8s, 10s, 12s or 15s, etc., which is not limited here.

[0062] It should be noted that the external heating of the suspension reactor 2 is a direct heating method of one or more combinations of resistance heating, electromagnetic induction heating, microwave heating, and plasma heating; or an indirect heating method of high-temperature flue gas from burning fuel, and the fuel is one or more combinations of coal, natural gas, liquefied gas, fuel oil, industrial coal gas, hydrogen, and CO.

[0063] Step S40, cooling the calcium sulfide.

[0064] The generated product then enters the high-temperature cyclone separator of the suspension reactor 2 for gas-solid separation. The separated high-temperature calcium sulfide powder enters the heat exchange tube of the cyclone cooler of the suspension cooler 4 through the discharge pipe of the high-temperature 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, air, or an inert gas, and its temperature is lower than the temperature of the generated calcium sulfide. For example, when the low-temperature medium is inert air, the generated calcium sulfide completes temperature exchange with the low-temperature inert gas in the heat exchange tube. The inert gas can be nitrogen, argon, carbon dioxide, or 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 cooler 4 for packaging, and the low-temperature inert gas is converted into a high-temperature inert gas.

[0065] Furthermore, the suspension cooler 4 is composed of 2 to 5 stages of cyclone heat exchangers. High-temperature calcium sulfide enters from the heat exchange tube of the first stage cyclone heat exchanger and exchanges heat with the low-temperature inert gas. After the exchange, it passes through each stage of heat exchangers in turn and is finally cooled to room temperature.

[0066] Furthermore, the discharge port of the final cyclone heat exchanger of the suspension cooler 4 can be further connected to an indirect heat exchanger 5, and the calcium sulfide discharged from the suspension cooler is further cooled by the indirect heat exchanger 5. The cooling medium in the indirect heat exchanger 5 can circulate cold water, low-temperature inert gas, low-temperature air, etc.

[0067] It should be noted that the suspension reactor 2 has an external circulation, and a part of the reaction materials circulates in the suspension reactor 2 once or multiple times.

[0068] In this embodiment, gypsum powder is preheated and dehydrated, and the preheating temperature is 150℃~250℃; solid sulfur is heated to 500℃~900℃ to generate sulfur gas; sulfur gas and preheated gypsum powder are introduced into suspension reactor 2 for reduction reaction to generate calcium sulfide and tail gas, and the reaction temperature is controlled at 800℃~1200℃, and the tail gas includes SO2; calcium sulfide is cooled. Solid sulfur is used as raw material, and gas sulfur is generated by heating solid sulfur to react with gypsum to generate calcium sulfide. Since sulfur is in gaseous state, the contact area between sulfur and gypsum is increased, the reaction is more sufficient, and the reaction efficiency of sulfur and gypsum is improved, thereby reducing the reaction time of sulfur reducing gypsum to generate calcium sulfide, and the calcium sulfide content in the generated product is higher, and the content of unreacted gypsum or sulfur is less, that is, the quality of the generated calcium sulfide is improved. Thus, the problems of long reaction time, low efficiency, and low quality of calcium sulfide produced by reducing gypsum with sulfur in the prior art are solved.

[0069] Further, refer to Figure 3-Figure 5 According to the first embodiment of the method for preparing calcium sulfide of the present application, a second embodiment of the method for preparing calcium sulfide of the present application is proposed. The method for preparing calcium sulfide of the present application further includes:

[0070] Step S50, exchanging heat between the high-temperature inert gas and the low-temperature air and the circulating cold water, the high-temperature inert gas is converted into the low-temperature inert gas, the low-temperature air is converted into the high-temperature air, and the circulating cold water is converted into the low-pressure steam, wherein the temperature of the high-temperature air is greater than the temperature of the low-temperature air, the temperature of the low-temperature air and the temperature of the circulating cold water are both lower than the temperature of the high-temperature inert gas, and the temperature of the low-pressure steam is greater than the temperature of the circulating cold water;

[0071] Step S60, heating the sulfur liquid with high-temperature air, and converting the high-temperature air into low-temperature air;

[0072] Step S70, heating the sulfur solid with low-pressure steam, and converting the low-pressure steam into circulating cold water.

[0073] The high-temperature calcium sulfide enters the heat exchange tube of the first-stage cyclone heat exchanger of the suspension cooler 4, and after heat exchange with the low-temperature inert gas, the high-temperature inert gas exiting the first-stage suspension cooler, i.e., the inert gas after heat exchange with the calcium sulfide, enters the indirect heat exchanger 5, and completes the temperature exchange with the low-temperature air and circulating cold water in the indirect heat exchanger 5. At this time, the high-temperature inert gas changes from a high-temperature state to a low-temperature inert gas in a low-temperature state, and the low-temperature inert gas is circulated back to the first-stage cyclone heat exchanger to exchange heat with the high-temperature calcium sulfide in the heat exchange tube entering the first-stage cyclone heat exchanger, and the reciprocating cycle is repeated to reuse the inert gas, and the temperature of the high-temperature inert gas is greater than that of the low-temperature inert gas.

[0074] After heat exchange with the high-temperature inert gas, the low-temperature air and circulating cold water are heated into high-temperature air and low-pressure steam. The temperature of the high-temperature air is higher than that of the low-temperature air. The temperature of the low-temperature air and the temperature of the circulating cold water are lower than that of the high-temperature inert gas. The temperature of the low-pressure steam is higher than that of the circulating cold water. The heated high-temperature air enters the sulfur gasification unit 3 and heats the sulfur liquid together with the external heating source. After the high-temperature air heats the sulfur liquid, it becomes low-temperature air again. The low-temperature air comes out of the sulfur gasification unit 3 and returns to the indirect heat exchanger 5 to repeat the heat exchange process with the high-temperature inert gas.

[0075] The low-pressure steam generated by the circulating cold water absorbing heat in the indirect heat exchanger 5 enters the sulfur liquefaction unit 8 and heats the solid sulfur together with the external heat source. After heating, the low-pressure steam turns into circulating cold water again, and the circulating cold water returns to the indirect heat exchanger 5 through the circulation pipeline to cool the high-temperature inert gas and is reused.

[0076] It should be noted that the external heat source can be resistance heating, electromagnetic induction heating, microwave heating, plasma heating, and indirect heating of high-temperature flue gas from burning fuel. The fuel is one or a combination of more than one of coal, natural gas, liquefied gas, fuel oil, industrial gas, hydrogen, and CO. In addition to the above-mentioned indirect heating methods, the method for heating and gasifying the sulfur liquid can also be oxygen-depleted combustion gasification, or a combination of oxygen-depleted combustion gasification and the above-mentioned indirect heating methods.

[0077] This embodiment utilizes inert gas, water and air through cyclic heat exchange to fully utilize the waste heat of high-temperature calcium sulfide to heat liquid sulfur and solid sulfur, thereby reducing the consumption of external heat sources during sulfur gasification and liquefaction and reducing the energy consumption of the entire process.

[0078] Further, refer to Figure 3-Figure 5 According to the first embodiment of the method for preparing calcium sulfide of the present application, a third embodiment of the method for preparing calcium sulfide of the present application is proposed. The method for preparing calcium sulfide of the present application further includes:

[0079] Step S80, using tail gas to preheat the gypsum powder.

[0080] The tail gas generated in step S30 is in a high temperature state, and the tail gas including sulfur dioxide is introduced into the suspension preheater 1 to perform heat exchange with the gypsum powder, thereby heating the gypsum powder. The flow direction of the sulfur dioxide is opposite to the flow direction of the gypsum powder.

[0081] In this embodiment, the heat of the exhaust gas is used to preheat the gypsum powder, thereby reducing the demand for external energy consumption during the gypsum powder preheating process, thereby saving energy consumption.

[0082] Further, refer to Figure 3-Figure 5According to the first embodiment of the method for preparing calcium sulfide of the present application, a fourth embodiment of the method for preparing calcium sulfide of the present application is proposed. The method for preparing calcium sulfide of the present application further includes:

[0083] Step S90, preparing sulfuric acid using the tail gas obtained by preheating the gypsum powder and performing gas dust removal.

[0084] The tail gas from the suspension preheater 1 passes through the gas dust removal unit 6 and then enters the sulfuric acid preparation unit 7, where the SO2 gas in the tail gas is prepared into sulfuric acid product. This embodiment increases the added value of calcium sulfide production by using SO2, a byproduct in the calcium sulfide production process, to generate sulfuric acid.

[0085] The following describes it in detail through specific embodiments.

[0086] Embodiment 1

[0087] The particle size of the gypsum powder entering the suspension reactor 2 is 20 microns, the mass ratio of the gypsum powder to the sulfur gas is 6:1, the average reaction time is 2s, the gypsum flow rate in the suspension reactor 2 is 500kg / h, the sulfur gas flow rate is 80kg / h, the reaction temperature is 800°C, and the final product calcium sulfide content is 83.8%.

[0088] Embodiment 2

[0089] The particle size of the gypsum powder entering the suspension reactor 2 is 40 microns, and the mass ratio of the gypsum powder to the sulfur gas is 6.1:1. The average reaction time is 4 seconds. The gypsum flow rate in the suspension reactor 2 is 520 kg / h, the sulfur gas flow rate is 85 kg / h, the reaction temperature is 850°C, and the final product calcium sulfide content is 85.6%.

[0090] Embodiment 3

[0091] The particle size of the gypsum powder entering the suspension reactor 2 is 60 microns, the mass ratio of the gypsum powder to the sulfur gas is 6.2:1, the average reaction time is 6s, the gypsum flow rate in the suspension reactor 2 is 540kg / h, the sulfur gas flow rate is 90kg / h, the reaction temperature is 900°C, and the final product calcium sulfide content is 95.5%.

[0092] Embodiment 4:

[0093] The particle size of the gypsum powder entering the suspension reactor 2 is 80 microns, and the mass ratio of the gypsum powder to the sulfur gas is 6.3:1. The average reaction time is 8s. The gypsum flow rate in the suspension reactor 2 is 560kg / h, the sulfur gas flow rate is 95kg / h, the reaction temperature is 950°C, and the final product calcium sulfide content is 96.2%.

[0094] Embodiment 5

[0095] The particle size of the gypsum powder entering the suspension reactor 2 is 80 microns, and the mass ratio of the gypsum powder to the sulfur gas is 6.5:1. The average reaction time is 10s. The gypsum flow rate in the suspension reactor 2 is 600kg / h, the sulfur gas flow rate is 100kg / h, the reaction temperature is 100°C, and the final product calcium sulfide content is 97.6%.

[0096] The present invention also provides a calcium sulfide production system, referring to Figure 3 The system is applied to the calcium sulfide preparation method of each embodiment of the present invention. The calcium sulfide production system includes: a suspension preheater 1, a suspension reactor 2, a suspension cooler 4 and a sulfur gasification unit 3; the discharge pipe of the final cyclone preheater of the suspension preheater 1 is connected to the first feed port of the suspension reactor 2; the discharge pipe of the gas-solid separator of the suspension reactor 2 is connected to the feed port of the first cyclone cooler of the suspension cooler 4, and the air outlet pipe of the gas-solid separator of the suspension reactor 2 is connected to the heat exchange pipe of the final cyclone preheater of the suspension preheater 1; the discharge pipe of the sulfur gasification unit 3 is connected to the second feed port of the suspension reactor 2.

[0097] The suspension preheater 1 is composed of 1 to 4 stages of cyclone heat exchangers. The raw gypsum enters from the heat exchange pipe of the first stage cyclone preheater of the suspension preheater 1, passes through the subsequent multi-stage cyclone preheaters, and is dehydrated and preheated in the suspension preheater 1. After the dehydrated and preheated gypsum powder is separated from the gas and solid in the final stage cyclone preheater, it passes through the discharge pipe of the final stage cyclone preheater of the suspension preheater 1 and the first feed port of the suspension reactor 2 in sequence, and enters the suspension reactor 2.

[0098] Solid sulfur is added to the sulfur gasification unit 3 for gasification to generate high-temperature sulfur gas, and the high-temperature sulfur gas enters the suspension reactor 2 through the discharge pipe of the sulfur gasification unit 3 and the second feed port of the suspension reactor 2 in sequence.

[0099] In the suspension reactor 2, the gypsum powder reacts with the sulfur gas to generate high-temperature calcium sulfide and high-temperature tail gas including SO2. The generated calcium sulfide and SO2 are separated into gas and solid in the high-temperature cyclone separator of the suspension reactor 2.

[0100] The separated high-temperature calcium sulfide powder enters the suspension cooler 4 through the discharge pipe of the high-temperature cyclone separator. The suspension cooler 4 is composed of 2 to 5 stages of cyclone coolers. The discharge pipe of the first stage cyclone cooler is connected to the heat exchange pipe of the second stage cyclone cooler, the air outlet pipe of the second stage cyclone cooler is connected to the heat exchange pipe of the first stage cyclone cooler, the discharge pipe of the second stage cyclone cooler is connected to the heat exchange pipe of the last stage cyclone cooler, and the air outlet pipe of the last stage cyclone cooler is connected to the heat exchange pipe of the second stage cyclone cooler. The high-temperature calcium sulfide powder passes through the multi-stage cyclone cooler in sequence, and finally cools to room temperature, and enters the product transportation, storage and packaging unit through the discharge pipe of the suspension cooler 4 for packaging.

[0101] The high-temperature exhaust gas including SO2 enters the heat exchange tube of the final cyclone preheater of the suspension preheater 1 through the outlet pipe of the gas-solid separator of the suspension reactor 2, and passes through the cyclone preheaters of each stage in the suspension preheater 1 in turn, and is finally discharged through the outlet of the first-stage cyclone preheater of the suspension preheater 1. In the process of the high-temperature exhaust gas including SO2 passing through the suspension preheater 1, heat exchange is performed with the gypsum powder, thereby preheating the gypsum powder.

[0102] Further, refer to Figure 4 , the calcium sulfide production system also includes:

[0103] an indirect heat exchanger 5 and a sulfur liquefaction unit 8 connected to the sulfur gasification unit 3;

[0104] The number of indirect heat exchangers 5 can be one, two or more. When the number of indirect heat exchangers 5 is one, the air outlet pipe of the first-stage cyclone cooler of the suspension cooler 4 is connected to the heat exchange pipe of the indirect heat exchanger 5. The air outlet pipe of the indirect heat exchanger 5 connected to the suspension cooler 4 is connected to at least the heat exchange pipe of the sulfur liquefaction unit 8, and can also be connected to the heat exchange pipe of the sulfur gasification unit 3.

[0105] Solid sulfur is placed in the sulfur melting tank of the sulfur liquefaction unit 8 to complete the liquefaction of sulfur, and melted to form a crude sulfur liquid. The crude sulfur liquid is then filtered to filter out the solid sulfur residue to avoid clogging the pumping pipe mouth. After filtering, refined sulfur liquid is formed. The refined sulfur liquid is pumped and metered into the sulfur gasification unit 3 in the sulfur liquefaction unit 8; the atomizing nozzle in the sulfur gasification unit 3 atomizes the refined sulfur liquid, and continues to overheat through combustion gasification to produce high-temperature sulfur gas S2, and then S2 is sent into the suspension reactor 2 through the Venturi ejector of the sulfur gasification unit 3.

[0106] The low-temperature inert gas in the heat exchange tube of the first-stage cyclone cooler of the suspension cooler 4 completes heat exchange with calcium sulfide, and the low-temperature inert gas is converted into high-temperature inert gas. The high-temperature inert gas enters the heat exchange tube of the indirect heat exchanger 5 through the outlet pipe of the first-stage cyclone cooler of the suspension cooler 4, and exchanges heat with the circulating cold water and low-temperature air in the indirect heat exchanger 5. After the heat exchange, the high-temperature inert gas is converted into low-temperature inert gas again and returns to the first-stage cyclone cooler of the suspension cooler 4. The circulating cold water forms low-pressure steam after heat exchange in the indirect heat exchanger 5, and the low-temperature air forms high-temperature air after heat exchange in the indirect heat exchanger 5. The low-pressure steam and high-temperature air come out of the indirect heat exchanger 5 and enter the sulfur liquefaction unit 8 and the sulfur gasification unit 3 respectively. The low-pressure steam enters the sulfur liquefaction unit 8 and exchanges heat with solid sulfur and then becomes circulating cold water again. It comes out of the sulfur liquefaction unit 8 through the circulation pipeline and re-enters the indirect heat exchanger 5. Similarly, the high-temperature air enters the sulfur gasification unit 3 and exchanges heat with the sulfur liquid, and then becomes low-temperature air again, and finally returns to the indirect heat exchanger 5.

[0107] When there are two indirect heat exchangers 5, in addition to one indirect heat exchanger 5 connected to the air outlet pipe of the first-stage cyclone cooler of the suspension cooler 4, another indirect heat exchanger 5 can be connected to the final-stage cyclone cooler of the suspension cooler 4 to further circulate cold water to cool the calcium sulfide coming out of the suspension cooler 4, and the circulating cold water is converted into hot water.

[0108] Further, refer to Figure 5 The calcium sulfide production system also includes: a gas dust removal unit 6 and a sulfuric acid preparation unit 7; the air outlet of the first-stage cyclone preheater of the suspension preheater 1 is connected to the air inlet of the gas dust removal unit 6; the exhaust port of the gas dust removal unit 6 is connected to the sulfuric acid preparation unit 7.

[0109] The tail gas including SO2 passing through the suspension preheater 1 passes through the air outlet of the first-stage cyclone preheater and the air inlet of the gas dust removal unit 6 in sequence, enters the gas dust removal unit 6, and after the dust in the tail gas is removed, enters the sulfuric acid preparation unit 7 through the exhaust port of the gas dust removal unit 6 to produce a sulfuric acid product.

[0110] 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, characterized in that: The steps include: Preheating and dehydrating the gypsum powder, wherein the preheating temperature is 800° C. to 900° C.; Heat solid sulfur to 500℃~900℃ to generate sulfur gas; The sulfur gas and the preheated gypsum powder are introduced into a suspension reactor for reduction reaction to generate calcium sulfide and tail gas, the reaction temperature is controlled at 800° C. to 1200° C., and the tail gas includes SO2; The calcium sulfide is cooled.

2. The method for preparing calcium sulfide according to claim 1, characterized in that: The step of heating solid sulfur to 500° C. to 900° C. to generate sulfur gas comprises: The solid sulfur is heated and liquefied to generate liquid sulfur, and the temperature is controlled at 120℃~150℃; The sulfur liquid is heated and gasified to generate sulfur gas. The temperature of the sulfur gas is controlled at 500° C. to 900° C., and the volume content of S2 in the sulfur gas is 10 to 100%.

3. The method for preparing calcium sulfide according to claim 2, characterized in that: The method of heating and gasifying the sulfur liquid is one of indirect heating gasification and oxygen-deficient combustion gasification or a combination of the two.

4. The method for preparing calcium sulfide according to claim 1, characterized in that: The step of cooling the calcium sulfide comprises: A low-temperature inert gas is used to exchange heat with the generated calcium sulfide to cool the generated calcium sulfide to room temperature, and the low-temperature inert gas is converted into a high-temperature inert gas, wherein the temperature of the generated calcium sulfide is greater than that of the low-temperature inert gas, and the temperature of the low-temperature inert gas is lower than that of the high-temperature inert gas.

5. The method for preparing calcium sulfide according to claim 4, characterized in that: Also includes: Exchanging heat between the high-temperature inert gas and low-temperature air and circulating cold water, the high-temperature inert gas is converted into the low-temperature inert gas, the low-temperature air is converted into high-temperature air, and the circulating cold water is converted into low-pressure steam, wherein the temperature of the high-temperature air is greater than the temperature of the low-temperature air, the temperature of the low-temperature air and the temperature of the circulating cold water are both lower than the temperature of the high-temperature inert gas, and the temperature of the low-pressure steam is greater than the temperature of the circulating cold water; The high-temperature air is used to heat the sulfur liquid, and the high-temperature air is converted into the low-temperature air; The low-pressure steam is used to heat the sulfur solid, and the low-pressure steam is converted into the circulating cold water.

6. The method for preparing calcium sulfide according to any one of claims 1 to 5, characterized in that: Also includes: The gypsum powder is preheated using tail gas.

7. The method for preparing calcium sulfide according to claim 6, characterized in that: Also includes: The tail gas obtained by preheating the gypsum powder is used to prepare sulfuric acid after gas dust removal.

8. A calcium sulfide production system, characterized in that: Applied to the method for preparing calcium sulfide according to any one of claims 1 to 7, the system comprises: a suspension preheater, a suspension reactor, a suspension cooler and a sulfur gasification unit; The discharge pipe of the final cyclone preheater of the suspension preheater is connected to the first feed port of the suspension reactor; The discharge pipe of the gas-solid separator of the suspension reactor is connected to the feed port of the first-stage cyclone cooler of the suspension cooler, and the air outlet pipe of the gas-solid separator of the suspension reactor is connected to the heat exchange pipe of the final-stage cyclone preheater of the suspension preheater; The discharge pipe of the sulfur gasification unit is communicated with the second feed port of the suspension reactor.

9. The calcium sulfide production system according to claim 8, characterized in that: The calcium sulfide production system further includes: an indirect heat exchanger and a sulfur liquefaction unit connected to the sulfur gasification unit; The air outlet pipe of the first-stage cyclone cooler of the suspension cooler is connected to the heat exchange pipe of the indirect heat exchanger; The air outlet pipe of the indirect heat exchanger is connected to the heat exchange pipe of the sulfur liquefaction unit and the heat exchange pipe of the sulfur gasification unit, or the air outlet pipe of the indirect heat exchanger is connected to the heat exchange pipe of the sulfur liquefaction unit; The discharge pipe of the sulfur gasification unit is communicated with the second feed port of the suspension reactor.

10. The calcium sulfide production system according to claim 9, characterized in that: The calcium sulfide production system also includes: a gas dust removal unit and a sulfuric acid preparation unit; The air outlet of the first-stage cyclone preheater of the suspension preheater is connected to the air inlet of the gas dust removal unit; The exhaust port of the gas dust removal unit is communicated with the sulfuric acid preparation unit.

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