Energy-saving system and energy-saving method of multi-stage coupling of flash steam and MVR system

Abstract

The energy-saving system of dry crystallization steam and MVR system multi-energy level coupling comprises an MVR system and a steam ejector pump; the steam ejector pump is arranged on a tank top outlet pipeline of a flash crystallization tank, and an outlet end of the steam ejector pump is connected to a heat medium inlet of any one or more of an MVR third-stage preheater, an MVR second-stage preheater, a forced circulation evaporator and a steam dryer, for secondary utilization of the steam ejector pump after pressure boosting of flash steam of the flash crystallization tank when the temperature of the flash steam is greater than or equal to 60 DEG C; the energy-saving system further comprises a heat exchange pipeline which is arranged in parallel with the steam ejector pump, for secondary utilization of the flash steam when the temperature of the flash steam is less than 60 DEG C. An energy-saving method is also provided, which is performed by using the foregoing energy-saving system. The energy-saving system and the energy-saving method can effectively solve the situation of insufficient steam in a park, and control different energy secondary utilization paths according to different temperatures of flash steam output from a tank top of a flash crystallization tank.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of energy saving of chemical devices, and particularly relates to an energy saving system and method for coupling multiple energy levels of flash steam and MVR systems. BACKGROUND

[0002] The MVR system is an energy saving technology that uses secondary steam generated by the evaporation system itself, which is compressed by a steam compressor to improve the enthalpy of the secondary steam, thereby reducing the demand for external energy.

[0003] With the rapid development of the battery industry, nickel sulfate, manganese sulfate, and cobalt sulfate, as key components of batteries, have high energy density, long service life, and stable charging and discharging characteristics, and are applied to emergency power supplies, electric vehicles, backup power supplies, and energy storage systems. At the same time, through recycling and reuse, it helps to reduce resource waste and environmental pollution.

[0004] Taking a hydrometallurgical device in a certain chemical park as an example, the main metal elements such as nickel, cobalt, and manganese in metal minerals are refined by a wet method. The MHP wet base, sulfuric acid, sodium sulfite, and water are used as reaction raw materials to replace the metals in the MHP wet base by acid leaching, and the interface liquid obtained by the reaction is sent to the extraction process. Different sulfate solutions are refined according to the extraction capacity of the extractant for different metal ions, and finally, the product workshop obtains battery-grade sulfate products through evaporation crystallization and drying.

[0005] The hydrometallurgical process involves four processes of reaction, extraction, product, and water treatment in production. In the reaction process, the high-acid leaching rapidly rises from 70-80℃ to 120-130℃ and generates a large amount of acid mist due to heat release. The industry currently uses circulating water to remove heat.

[0006] The flash drying crystallization process produces 10t / h of water vapor, and the industry also uses circulating water to remove heat, resulting in a large amount of waste heat. At the same time, the low-temperature heat sink in the device is heated by high-temperature steam, and the heat is not fully matched and utilized, resulting in high energy consumption of the device.

[0007] CN 215939039 U discloses a deamination and evaporation concentration coupling energy saving device, which utilizes the characteristics of ammonia gas being easy to vaporize at low pressure and low temperature to realize material deamination, and uses the secondary steam generated by the fourth effect of the deamination device as a heat source, thereby saving the amount of steam in the device and reducing the energy consumption of deamination. Although this process achieves energy saving to some extent, the heat utilization rate is not high, and the temperature of the secondary steam is controlled according to the parameters of deamination, the heat source is unstable, the equipment requirements are high, and the modification is difficult.

[0008] CN 117168213 A discloses an oxygen pressure leaching waste steam preheating and recovery system. This system utilizes a waste steam treatment component to perform cascade heat exchange on the waste steam at the top of the absorption tower. Finally, the water vapor discharged from the evaporation component and the water discharged from the condensate component are combined and recycled, improving energy efficiency. However, this invention depends on the temperature of the waste steam and the user, and any new components require custom customization, resulting in significant modifications to the tower system.

[0009] As can be seen from the above, there is currently no way to completely recover the energy wasted by flash steam and MVR systems. Summary of the Invention

[0010] The first objective of this invention is to provide an energy-saving system that couples flash steam with an MVR system at multiple energy levels. This energy-saving system has a simple structure and is easy to operate. It can recover all the heat generated by flash drying and avoid energy waste.

[0011] The second objective of this invention is to provide an energy-saving method employing the aforementioned energy-saving system.

[0012] To achieve the first objective of this invention, the following technical solution is adopted:

[0013] The energy-saving system includes an MVR system and a steam ejector pump;

[0014] The steam ejector pump is installed on the top outlet pipeline of the flash crystallizer in the MVR system, and its outlet end is connected to the heat medium inlet of any one or more of the MVR third-stage preheater, MVR second-stage preheater, forced circulation evaporator and steam dryer in the MVR system. It is used to pressurize the flash vapor in the flash crystallizer when the flash vapor temperature is ≥60℃ and send it to any one or more of the MVR third-stage preheater, MVR second-stage preheater, forced circulation evaporator and steam dryer for secondary use as a heat medium.

[0015] The energy-saving system also includes a heat exchange pipeline, which is connected in parallel with the steam ejector pump. When the flash steam temperature in the flash crystallizer of the MVR system is <60°C, it is sent to the second-stage preheater of the MVR system as a heat medium for secondary utilization.

[0016] The energy-saving system of the application, preferably, the energy-saving system further comprises a fifth condensate tank, and a non-condensed gas outlet is arranged at the top of the tank, a condensate outlet is arranged at the bottom of the tank, and the inlet end of the tank is connected to the heat medium outlet of any one or more of the MVR third-stage preheater, the MVR second-stage preheater, the forced-circulation evaporator and the steam dryer in the MVR system, the non-condensed gas outlet of the tank is connected to the heat medium inlet of the MVR second-stage preheater, and the condensate outlet of the tank is connected to the heat medium inlet of the MVR first-stage preheater, so as to receive the heat medium condensate from any one or more of the MVR third-stage preheater, the MVR second-stage preheater, the forced-circulation evaporator and the steam dryer when the flash gas temperature of the flash crystallization tank is greater than or equal to 60 DEG C, perform pressure-reducing gas-liquid separation on the heat medium condensate, output the fifth-stage non-condensed gas from the non-condensed gas outlet of the tank to the MVR second-stage preheater as heat medium for secondary utilization, and output the fifth-stage condensate from the condensate outlet of the tank to the MVR first-stage preheater as heat medium for secondary utilization.

[0017] The energy-saving system of the application, preferably, a third circulating pump is further arranged on the pipeline from the condensate outlet of the fifth condensate tank to the heat medium inlet of the MVR first-stage preheater, and a second valve is arranged at the outlet end of the third circulating pump; and / or,

[0018] The heat medium inlet of the forced-circulation evaporator is provided with a valve, including a third valve arranged on the steam heat source pipeline and a fourth valve arranged on the secondary utilization heat source pipeline; and / or,

[0019] A fifth valve is arranged on the heat medium inlet pipeline of the MVR second-stage preheater; and / or,

[0020] A sixth valve is arranged on the pipeline from the heat medium outlet of the MVR second-stage preheater to the inlet of the fifth condensate tank, and the sixth valve is arranged at a position between the heat medium outlet of the MVR second-stage preheater and the heat medium outlet of the MVR third-stage preheater; and / or,

[0021] A seventh valve is arranged on the pipeline from the fifth condensate tank to the outlet end of the fifth valve.

[0022] The energy-saving system of the application, preferably, the energy-saving system further comprises a first controller, and the first controller is electrically connected to any one or more of the second valve, the third valve, the fourth valve, the fifth valve, the sixth valve and the seventh valve.

[0023] The energy-saving system of the application, preferably, an eighth valve is arranged on the heat exchange pipeline; and / or,

[0024] A first valve is arranged at the condensate outlet end of the fifth condensate tank; and / or,

[0025] The heat medium inlet of the steam dryer is provided with valves, including an eleventh valve located on the steam heat source pipeline and a ninth valve located on the secondary heat source pipeline; and / or,

[0026] The energy-saving system further comprises a second pipeline, and the inlet end of the second pipeline is connected to the heat medium outlet of any one or more of the MVR third-stage preheater, the forced circulation evaporator and the MVR second-stage preheater, and the outlet end is connected to the inlet end of the fifth condensate tank, so as to converge the heat medium outlet materials of any one or more of the MVR third-stage preheater, the forced circulation evaporator and the MVR second-stage preheater into the fifth condensate tank through the second pipeline, and the second pipeline is provided with a tenth valve.

[0027] Preferably, the energy-saving system further comprises a second controller, which is electrically connected to any one or more of the eighth valve, the ninth valve, the tenth valve, the steam ejector pump, the first valve and the eleventh valve.

[0028] Preferably, the MVR system comprises an MVR first-stage preheater, an MVR second-stage preheater and an MVR third-stage preheater connected in sequence through pipelines, for sequentially preheating the sulfate salt solution by heat exchange and outputting the preheated sulfate salt solution.

[0029] The MVR system further comprises an MVR crystallization separator, and the bottom of the MVR crystallization separator is provided with a storage bin, one side of the bottom of the MVR crystallization separator is provided with a discharge port, the lower sidewall of the MVR crystallization separator is respectively provided with a feed inlet, a forced circulation inlet and a self-circulation inlet, and the top of the MVR crystallization separator is provided with a flash gas outlet, and the bottom of the storage bin is provided with a first bin outlet and a second bin outlet, and the feed inlet of the storage bin is connected to the material outlet of the MVR third-stage preheater, so as to perform flash crystallization on the preheated sulfate salt solution from the MVR third-stage preheater, output the flash gas from the top flash gas outlet of the MVR crystallization separator, discharge the concentrated liquid containing sulfate salt crystals from the discharge port of the MVR crystallization separator, store part of the concentrated liquid containing sulfate salt crystals in the storage bin, discharge part of the concentrated liquid containing sulfate salt crystals from the second bin outlet of the MVR crystallization separator and return the part of the concentrated liquid containing sulfate salt crystals to the MVR crystallization separator through the self-circulation inlet, and discharge part of the concentrated liquid containing sulfate salt crystals from the first bin outlet of the MVR crystallization separator.

[0030] A first circulation pump is arranged on the pipeline from the second bin outlet to the self-circulation inlet, for pumping the material discharged from the second bin outlet to the MVR crystallization separator.

[0031] The MVR system further comprises a discharge pipeline, a material humidity instrument, an axial flow pump, a forced circulation evaporator, and a flash crystallization tank; a first end of the discharge pipeline is connected to the first bin outlet and the discharge port, respectively; a second end of the discharge pipeline is connected to the bottom inlet of the forced circulation evaporator and the feed inlet of the flash crystallization tank, respectively; the material humidity instrument is connected in parallel to the discharge pipeline; the axial flow pump is arranged on the bottom inlet pipeline of the forced circulation evaporator, and is used to detect the material from the first bin outlet and the discharge port by using the material humidity instrument, and when the detection result is unqualified, the material is sent to the forced circulation evaporator by the axial flow pump for treatment, and then is circulated to the MVR crystallization separator from the forced circulation inlet for further treatment, and when the detection result is qualified, the material is output to the flash crystallization tank for cooling flash crystallization, and the flash gas is output from the tank top, and the sulfate salt crystal is output from the tank bottom;

[0032] The MVR system further comprises a compressor arranged on the flash gas outlet pipeline of the MVR crystallization separator, and used to compress the flash gas from the MVR crystallization separator and then return it to the forced circulation evaporator as part of the steam source thereof;

[0033] The MVR system further comprises a first centrifugal pump and a steam dryer connected in sequence by pipelines, and the inlet of the first centrifugal pump is connected to the tank bottom outlet of the flash crystallization tank, and used to sequentially centrifugally dewater and steam dry the sulfate salt crystal output from the tank bottom of the flash crystallization tank, and output the sulfate salt product;

[0034] The MVR system further comprises a first-stage condensate storage tank, a third-stage condensate storage tank, a non-condensable gas condenser, a second-stage condensate storage tank, and a second centrifugal pump connected by pipelines; wherein,

[0035] The feed inlet of the first-stage condensate storage tank is connected to the hot medium outlets of the MVR second-stage preheater and the MVR third-stage preheater, and used to perform pressure reduction gas-liquid separation on the hot medium condensate from the MVR second-stage preheater and the MVR third-stage preheater, and output the first-stage non-condensable gas from the top and the first-stage condensate from the bottom;

[0036] The first-stage condensate storage tank, the non-condensable gas condenser, and the second-stage condensate storage tank are connected in sequence, and used to output the first-stage non-condensable gas from the first-stage condensate storage tank, send it to the non-condensable gas condenser for cooling, then send it to the second-stage condensate storage tank for further pressure reduction gas-liquid separation, and output the second-stage non-condensable gas from the top and the second-stage condensate from the bottom;

[0037] The feed inlet of the third-stage condensate storage tank is connected to the bottom outlets of the first-stage condensate storage tank and the second-stage condensate storage tank, respectively, and the discharge port is connected to the hot medium inlet of the MVR first-stage preheater, and used to receive the first-stage condensate from the first-stage condensate storage tank and the second-stage condensate from the second-stage condensate storage tank, and send them to the MVR first-stage preheater as the hot medium thereof to preheat the sulfate salt solution of the feed.

[0038] To achieve the second object of the present application, an energy-saving method of coupling a drying crystallization vapor with a multi-energy-level MVR system is also provided, which is performed by using the aforementioned energy-saving system.

[0039] The energy-saving method of the present application preferably comprises:

[0040] The energy-saving method comprises:

[0041] (1) When the sulfate solution is treated by the MVR system, flash steam is output from the top of the flash crystallization tank, and sulfate crystals are output from the bottom of the tank.

[0042] (2) When the temperature of the flash steam output from the top of the flash crystallization tank in step (1) is ≥ 60℃, the flash steam is sent to the steam ejector pump for pressure boosting, and then to any one or more of the MVR third-stage preheater, the MVR second-stage preheater, the forced circulation evaporator, and the steam dryer as a heat medium for secondary utilization.

[0043] When the temperature of the flash steam output from the top of the flash crystallization tank in step (1) is < 60℃, the flash steam is sent to the MVR second-stage preheater as a heat medium for secondary utilization.

[0044] The energy-saving method of the present application preferably further comprises step (3), wherein the heat medium condensate of any one or more of the MVR third-stage preheater, the MVR second-stage preheater, the forced circulation evaporator, and the steam dryer is sent to the fifth condensate tank for pressure reduction gas-liquid separation, and the fifth-stage non-condensable gas is output from the non-condensable gas outlet to the MVR second-stage preheater as a heat medium for secondary utilization, and the fifth-stage condensate is output from the condensate outlet to the MVR first-stage preheater as a heat medium for secondary utilization.

[0045] The energy-saving method of the present application preferably utilizes a first controller to control any one or more of the second valve, the third valve, the fourth valve, the fifth valve, the sixth valve, and the seventh valve, so as to control the secondary utilization path of energy.

[0046] The energy-saving method of the present application preferably utilizes a second controller to control any one or more of the eighth valve, the ninth valve, the tenth valve, the steam ejector pump, the first valve, and the eleventh valve, so as to control the secondary utilization path of energy.

[0047] The energy-saving method of the present application has the following advantages:

[0048] The energy-saving system and method of the dry crystallization steam and MVR system multi-energy level coupling of the present application can effectively solve the situation of insufficient steam in the park. In order to make full use of the flash steam output from the flash crystallization tank, the flash steam at different temperatures needs to be controlled: when the temperature is relatively low (<60℃), the flash steam is sent to the MVR second-stage preheater as a heat medium for secondary utilization; when the temperature is relatively high (≥60℃), the steam ejector pump is started to perform secondary treatment (pressure increasing treatment) on the flash steam, and then the flash steam is sent to the MVR third-stage preheater, the MVR second-stage preheater, the forced circulation evaporator and the steam dryer as a heat medium for secondary utilization; finally, the fifth-stage non-condensable gas and the fifth-stage condensate output from the fifth condensate tank are utilized in stages, the fifth-stage non-condensable gas is sent to the MVR second-stage preheater as a heat medium for secondary utilization, and the fifth-stage condensate is sent to the MVR first-stage preheater as a heat medium for secondary utilization; thereby realizing the coupled utilization of energy, recovering the low-temperature waste heat in the device, and reducing the steam energy consumption of the device. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 is a structural schematic diagram of the energy-saving system of the dry crystallization steam and MVR system multi-energy level coupling of the present application in an embodiment.

[0050] Figure 2 is a structural schematic diagram of a traditional MVR system. DETAILED DESCRIPTION

[0051] The technical solutions of the present application and their effects will be further described below in combination with specific embodiments / examples and drawings. The following embodiments / examples are only used to illustrate the content of the present application, and the present application is not limited to the following embodiments or examples. Simple changes to the present application using the concept of the present application are within the scope of the present application.

[0052] The present application provides an energy-saving system of dry crystallization steam and MVR system multi-energy level coupling, as shown in Figure 1 The energy-saving system includes an MVR system and a steam ejector pump 201.

[0053] The steam ejector pump 201 is arranged on the tank top outlet pipeline of the flash crystallization tank 116 in the MVR system, and the outlet end thereof is connected to the heat medium inlet of any one or more of the MVR third-stage preheater 103, the MVR second-stage preheater 102, the forced circulation evaporator 112 and the steam dryer 118 in the MVR system, for sending the flash gas of the flash crystallization tank 116 to any one or more of the MVR third-stage preheater 103, the MVR second-stage preheater 102, the forced circulation evaporator 112 and the steam dryer 118 as a heat medium for secondary utilization after being pressurized (such as pressurized to 150-200 kPa) when the flash gas temperature of the flash crystallization tank 116 is ≥60℃.

[0054] The energy-saving system further comprises a heat exchange pipeline 215 arranged in parallel with the steam ejector pump 201, for sending the flash gas of the flash crystallization tank 116 to the MVR second-stage preheater 102 as a heat medium for secondary utilization when the flash gas temperature of the flash crystallization tank 116 in the MVR system is <60℃.

[0055] The energy-saving system of the dry crystallization steam and MVR system multi-energy level coupling of the present application can effectively solve the situation of insufficient steam in the park. In order to fully utilize the flash gas output from the tank top of the flash crystallization tank, the flash gas at different temperatures needs to be controlled: when the temperature is low (<60℃), the flash gas is sent to the MVR second-stage preheater as a heat medium for secondary utilization; when the temperature is high (≥60℃), the steam ejector pump is started to perform secondary treatment (pressure increasing treatment) on the flash gas, and then the flash gas is sent to any one or more of the MVR third-stage preheater 103, the MVR second-stage preheater 102, the forced circulation evaporator 112 and the steam dryer 118 as a heat medium for secondary utilization, so as to realize the coupled utilization of energy, recover the low-temperature waste heat in the device, and reduce the steam energy consumption of the device.

[0056] In an embodiment, as Figure 1As shown, the energy-saving system further comprises a fifth condensate tank 202, and the top of the tank is provided with a non-condensable gas outlet, the bottom is provided with a condensate outlet, and the inlet end is connected to the heat medium outlet of any one or more of the MVR third-stage preheater 103, the MVR second-stage preheater 102, the forced circulation evaporator 112 and the steam dryer 118 in the MVR system, the non-condensable gas outlet is connected to the heat medium inlet of the MVR second-stage preheater 102, and the condensate outlet is connected to the heat medium inlet of the MVR first-stage preheater 101, so as to accept the heat medium condensate from any one or more of the MVR third-stage preheater 103, the MVR second-stage preheater 102, the forced circulation evaporator 112 and the steam dryer 118 when the flash gas temperature of the flash crystallization tank 116 is greater than or equal to 60°C, perform pressure reduction gas-liquid separation on the heat medium condensate, output the fifth-stage non-condensable gas from the non-condensable gas outlet to the MVR second-stage preheater 102 as heat medium for secondary utilization, and output the fifth-stage condensate from the condensate outlet to the MVR first-stage preheater 101 as heat medium for secondary utilization.

[0057] The energy-saving system of the dry crystallization steam and MVR system multi-energy level coupling of the application can perform cascade utilization on the fifth-stage non-condensable gas and the fifth-stage condensate output by the fifth condensate tank 202, send the fifth-stage non-condensable gas to the MVR second-stage preheater 102 as heat medium for secondary utilization, send the fifth-stage condensate to the MVR first-stage preheater 101 as heat medium for secondary utilization, thereby realizing coupled utilization of energy, recovering low-temperature waste heat in the device, and reducing steam energy consumption of the device.

[0058] In an embodiment, as shown in Figure 1 A third circulating pump 203 is further arranged on the pipeline from the condensate outlet of the fifth condensate tank 202 to the heat medium inlet of the MVR first-stage preheater 101, and the outlet end of the third circulating pump 203 is provided with a second valve 205; and / or,

[0059] The heat medium inlet of the forced circulation evaporator 112 is provided with a valve, including a third valve 206 located on the steam heat source pipeline and a fourth valve 207 located on the secondary utilization heat source pipeline; and / or,

[0060] A fifth valve 208 is arranged on the heat medium inlet pipeline of the MVR second-stage preheater 102; and / or,

[0061] A sixth valve 209 is arranged on the pipeline from the heat medium outlet of the MVR second-stage preheater 102 to the inlet of the fifth condensate tank 202, and the sixth valve 209 is located between the heat medium outlet of the MVR second-stage preheater 102 and the heat medium outlet of the MVR third-stage preheater 103; and / or,

[0062] A seventh valve 210 is arranged on the pipeline from the fifth condensate tank 202 to the outlet end of the fifth valve 208.

[0063] In an embodiment, as shown in Figure 1 The energy-saving system further comprises a first controller 211 electrically connected to any one or more of the second valve 205, the third valve 206, the fourth valve 207, the fifth valve 208, the sixth valve 209 and the seventh valve 210, so as to control the opening and closing and the opening degree of the valves, to control the secondary utilization path of energy, to control the flow of materials in the pipelines where the valves are arranged, to realize the coupled utilization of energy therein, and to realize energy saving.

[0064] In an embodiment, as shown in Figure 1 An eighth valve 212 is arranged on the heat exchange pipeline 215; and / or,

[0065] The condensate outlet end of the fifth condensate tank 202 is provided with a first valve 204; and / or,

[0066] The heat medium inlet of the steam dryer 118 is provided with valves, including an eleventh valve 216 arranged on the steam heat source pipeline thereof and a ninth valve 213 arranged on the secondary utilization heat source pipeline thereof; and / or,

[0067] The energy-saving system further comprises a second pipeline 217, the inlet end of which is connected to the heat medium outlet of any one or more of the MVR third-stage preheater 103, the forced circulation evaporator 112 and the MVR second-stage preheater 102, and the outlet end of which is connected to the inlet end of the fifth condensate tank 202, so as to converge the materials from the heat medium outlets of any one or more of the MVR third-stage preheater 103, the forced circulation evaporator 112 and the MVR second-stage preheater 102, and then send the materials to the fifth condensate tank 202 through the second pipeline 217, and a tenth valve 214 is arranged on the second pipeline 217.

[0068] In an embodiment, as shown in Figure 1 The energy-saving system further comprises a second controller 218 electrically connected to any one or more of the eighth valve 212, the ninth valve 213, the tenth valve 214, the steam ejector pump 201, the first valve 204 and the eleventh valve 216, so as to control the opening and closing and the opening degree of the valves, to control the secondary utilization path of energy, to control the flow of materials in the pipelines where the valves are arranged, to realize the coupled utilization of energy therein, and to realize energy saving.

[0069] In an embodiment, as shown in Figure 1As shown, the MVR system includes an MVR first-stage preheater 101, an MVR second-stage preheater 102, and an MVR third-stage preheater 103 connected in sequence by pipelines, which are used to sequentially preheat the fed sulfate solution by heat exchange and output the preheated sulfate solution.

[0070] The MVR system also includes an MVR crystallizer 104, which is connected to the material outlet of the MVR third-stage preheater 103 through its inlet. It is used to flash crystallize the preheated sulfate solution from the MVR third-stage preheater 103 and output flash vapor and concentrated liquid containing sulfate crystals.

[0071] The MVR system also includes a compressor 115 and a forced circulation evaporator 112 connected in sequence; the inlet end of the compressor 115 is connected to the flash vapor outlet of the MVR crystallizer 104, which is used to compress the flash vapor from the MVR crystallizer 104 and send it back to the forced circulation evaporator 112 as part of its steam source (i.e., as its heat medium for secondary use), and output the heat medium condensate.

[0072] The MVR system also includes a flash crystallizer 116, whose inlet is connected to the concentrate outlet of the MVR crystallizer 104. It is used to cool and flash crystallize the qualified concentrate containing sulfate crystals from the MVR crystallizer 104, and output flash vapor from the top of the tank and sulfate crystals from the bottom of the tank.

[0073] The MVR system also includes a first centrifugal pump 117 and a steam dryer 118 connected in sequence by pipelines. The inlet of the first centrifugal pump 117 is connected to the bottom outlet of the flash crystallizer 116, which is used to centrifuge and steam dry the sulfate crystals output from the bottom of the flash crystallizer 116 in sequence, and output sulfate products.

[0074] In one implementation, such as Figure 1 As shown, the MVR system includes an MVR first-stage preheater 101, an MVR second-stage preheater 102, and an MVR third-stage preheater 103 connected in sequence by pipelines, which are used to sequentially preheat the fed sulfate solution by heat exchange and output the preheated sulfate solution.

[0075] The MVR system further comprises an MVR crystallization separator 104, which is provided with a storage bin 105 at the bottom, a discharge port 106 at one side of the bottom, a feed inlet, a forced circulation inlet 107 and a self-circulation inlet 114 on the lower sidewall respectively, and a flash gas outlet at the top, and the bottom of the storage bin 105 is provided with a first bin outlet 108 and a second bin outlet 109, and the feed inlet is connected to the material outlet of the MVR third-stage preheater 103, for flash evaporation crystallization of the preheated sulfate solution from the MVR third-stage preheater 103, and output of flash gas from the flash gas outlet at the top, discharge of the concentrated liquid containing sulfate crystals from the discharge port 106, storage of part of the concentrated liquid in the storage bin 105, discharge of part of the concentrated liquid from the second bin outlet 109 and return of the concentrated liquid to the MVR crystallization separator 104 through the self-circulation inlet 114, and discharge of part of the concentrated liquid from the first bin outlet 108;

[0076] A first circulation pump 113 is arranged on the pipeline from the second bin outlet 109 to the self-circulation inlet 114, for pumping the material discharged from the second bin outlet 109 to the MVR crystallization separator 104;

[0077] The MVR system further comprises a discharge pipeline, a material humidity instrument 110, an axial flow pump 111, a forced circulation evaporator 112, and a flash evaporation crystallization tank 116. The first end of the discharge pipeline is connected to the first bin outlet 108 and the discharge port 106 respectively, and the second end of the discharge pipeline is connected to the bottom inlet of the forced circulation evaporator 112 and the feed inlet of the flash evaporation crystallization tank 116 respectively. The material humidity instrument 110 is arranged in parallel on the discharge pipeline. The axial flow pump 111 is arranged on the bottom inlet pipeline of the forced circulation evaporator 112, for detecting the material from the first bin outlet 108 and the discharge port 106 by using the material humidity instrument 110, and when the detection result is unqualified, sending the material to the forced circulation evaporator 112 for treatment, and then circulating the material to the MVR crystallization separator 104 through the forced circulation inlet 107 for further treatment, and when the detection result is qualified, outputting the material to the flash evaporation crystallization tank 116 for cooling flash evaporation crystallization, and outputting flash gas from the top of the tank and sulfate crystals from the bottom of the tank;

[0078] The MVR system further comprises a compressor 115 arranged on the flash gas outlet pipeline of the MVR crystallization separator 104, for compressing the flash gas from the MVR crystallization separator 104 and returning the flash gas to the forced circulation evaporator 112 as part of the steam source of the forced circulation evaporator 112;

[0079] The MVR system further comprises a first centrifugal pump 117 and a steam dryer 118 connected in sequence by pipelines, and the inlet of the first centrifugal pump 117 is connected to the tank bottom outlet of the flash evaporation crystallization tank 116, for sequentially centrifugal dewatering and steam drying of the sulfate crystals output from the tank bottom of the flash evaporation crystallization tank 116, and output of sulfate products.

[0080] The MVR system further comprises a first-stage condensate storage tank 122, a third-stage condensate storage tank 123, a non-condensable gas condenser 124, a second-stage condensate storage tank 125 and a second centrifugal pump 126 connected by pipelines; wherein,

[0081] The feed inlet of the first-stage condensate storage tank 122 is connected to the hot medium outlets of the MVR second-stage preheater 102 and the MVR third-stage preheater 103, for performing pressure-reducing gas-liquid separation on the hot medium condensate from the MVR second-stage preheater 102 and the MVR third-stage preheater 103, and outputting first-stage non-condensable gas from the top and first-stage condensate from the bottom;

[0082] The first-stage condensate storage tank 122, the non-condensable gas condenser 124 and the second-stage condensate storage tank 125 are connected in sequence, for outputting the first-stage non-condensable gas from the first-stage condensate storage tank 122 to the non-condensable gas condenser 124 for cooling and then to the second-stage condensate storage tank 125 for further pressure-reducing gas-liquid separation, and outputting second-stage non-condensable gas from the top and second-stage condensate from the bottom;

[0083] The feed inlet of the third-stage condensate storage tank 123 is connected to the bottom outlets of the first-stage condensate storage tank 122 and the second-stage condensate storage tank 125, and the discharge outlet is connected to the hot medium inlet of the MVR first-stage preheater 101, for receiving the first-stage condensate from the first-stage condensate storage tank 122 and the second-stage condensate from the second-stage condensate storage tank 125 and sending them to the MVR first-stage preheater 101 as its hot medium to preheat the sulfate solution of the feed.

[0084] The skilled person understands that in the energy-saving system of the present application, dry crystallization vapor and MVR system multi-energy level coupling, valves are arranged on the relevant pipelines, and the valves are respectively controlled by the relevant controllers to control the opening and closing and the opening degree, so as to control the flow of the material on the relevant pipelines, and then control the secondary utilization path of energy, so that the energy in the flash vapor output from the flash crystallization tank 116 is fully recovered and utilized under different conditions.

[0085] The present application also provides an energy-saving method of dry crystallization vapor and MVR system multi-energy level coupling, which is carried out by using the above-mentioned energy-saving system.

[0086] In an embodiment, as shown in Figure 1 the energy-saving method comprises:

[0087] (1) After the sulfate solution is treated by the MVR system, flash vapor is output from the top of the flash crystallization tank 116 thereof, and sulfate crystals are output from the bottom;

[0088] (2) when the flash gas temperature output from the flash crystallization tank 116 in step (1) is ≥ 60℃, the flash gas is sent to the steam ejector pump 201 for pressure boosting (such as to 150-200 kPa) and then to any one or more of the MVR third-stage preheater 103, the MVR second-stage preheater 102, the forced circulation evaporator 112 and the steam dryer 118 as a heat medium for secondary utilization;

[0089] (2) when the flash gas temperature output from the flash crystallization tank 116 in step (1) is < 60℃, the flash gas is sent to the MVR second-stage preheater 102 as a heat medium for secondary utilization.

[0090] The energy-saving method of the dry crystallization steam and MVR system multi-energy level coupling of the application can effectively solve the situation of insufficient steam in the park. In order to make full use of the flash gas output from the flash crystallization tank, the flash gas at different temperatures can be controlled: when the temperature is low (< 60℃), the flash gas is sent to the MVR second-stage preheater as a heat medium for secondary utilization; when the temperature is high (≥ 60℃), the steam ejector pump is started to perform secondary treatment (pressure boosting) on the flash gas, and then the flash gas is sent to any one or more of the MVR third-stage preheater 103, the MVR second-stage preheater 102, the forced circulation evaporator 112 and the steam dryer 118 as a heat medium for secondary utilization.

[0091] In one embodiment, the energy-saving method further comprises step (3): sending the heat medium condensate of any one or more of the MVR third-stage preheater 103, the MVR second-stage preheater 102, the forced circulation evaporator 112 and the steam dryer 118 to the fifth condensate tank 202 for pressure reduction gas-liquid separation, and outputting the fifth-stage non-condensable gas from the non-condensable gas outlet of the fifth condensate tank 202 to the MVR second-stage preheater 102 as a heat medium for secondary utilization, and outputting the fifth-stage condensate from the condensate outlet of the fifth condensate tank 202 to the MVR first-stage preheater 101 as a heat medium for secondary utilization.

[0092] The energy-saving method of the application realizes the coupled utilization of energy by using the fifth-stage non-condensable gas and the fifth-stage condensate output from the fifth condensate tank 202 in a cascade manner, sending the fifth-stage non-condensable gas to the MVR second-stage preheater 102 as a heat medium for secondary utilization, and sending the fifth-stage condensate to the MVR first-stage preheater 101 as a heat medium for secondary utilization, thereby realizing the coupled utilization of energy, recovering low-temperature waste heat in the device, and reducing the steam energy consumption of the device.

[0093] In one embodiment, the energy-saving method further includes using a first controller 211 to control any one or more of the second valve 205, the third valve 206, the fourth valve 207, the fifth valve 208, the sixth valve 209, and the seventh valve 210, thereby controlling the opening and closing of these valves, and thus controlling the secondary utilization path of energy, controlling the material flow in the pipelines where these valves are located, realizing the coupled utilization of energy within them, and thus achieving energy saving.

[0094] In one embodiment, the second controller 218 controls one or more of the eighth valve 212, the ninth valve 213, the tenth valve 214, the steam ejector pump 201, the first valve 204, and the eleventh valve 216, thereby controlling the opening and closing of these valves, and thus controlling the secondary utilization path of energy, controlling the material flow in the pipelines where these valves are located, realizing the coupled utilization of energy within them, and thus achieving energy saving.

[0095] The energy-saving system and method of the present invention, which couples drying and crystallizing steam with MVR system at multiple energy levels, can effectively solve the problem of insufficient steam in industrial parks.

[0096] The present invention will be further illustrated below through examples and comparative examples.

[0097] Example 1 (S1)

[0098] like Figure 1 As shown, an energy-saving system A1, which couples drying crystallization steam with a multi-level MVR system, includes an MVR system and a steam ejector pump 201; wherein,

[0099] The MVR system includes an MVR first-stage preheater 101, an MVR second-stage preheater 102, and an MVR third-stage preheater 103 connected in sequence by pipelines, which are used to sequentially preheat the feed salt solution and then output the preheated salt solution.

[0100] The MVR system further comprises an MVR crystallization separator 104, which is provided with a storage bin 105 at the bottom, a discharge port 106 at one side of the bottom, an inlet for material, a forced circulation inlet 107 and a self-circulation inlet 114 on the lower sidewall respectively, and a flash gas outlet at the top, and the bottom of the storage bin 105 is provided with a first bin outlet 108 and a second bin outlet 109, and the inlet of the storage bin 105 is connected to the material outlet of the MVR third-stage preheater 103, so as to perform flash crystallization on the preheated salt solution from the MVR third-stage preheater 103, and output the flash gas from the flash gas outlet at the top, discharge the concentrated liquid containing sulfate crystals from the discharge port 106, store part of the concentrated liquid in the storage bin 105, and discharge part of the concentrated liquid from the second bin outlet 109 and return it to the MVR crystallization separator 104 through the self-circulation inlet 114, and discharge part of the concentrated liquid from the first bin outlet 108;

[0101] A first circulation pump 113 is arranged on the pipeline from the second bin outlet 109 to the self-circulation inlet 114, so as to pump the material discharged from the second bin outlet 109 to the MVR crystallization separator 104;

[0102] The MVR system further comprises a discharge pipeline, a material humidity instrument 110, an axial flow pump 111, a forced circulation evaporator 112, and a flash crystallization tank 116. The first end of the discharge pipeline is connected to the first bin outlet 108 and the discharge port 106 respectively, the second end of the discharge pipeline is connected to the bottom inlet of the forced circulation evaporator 112 and the inlet of the flash crystallization tank 116 respectively, the material humidity instrument 110 is arranged in parallel on the discharge pipeline, and the axial flow pump 111 is arranged on the bottom inlet pipeline of the forced circulation evaporator 112. The axial flow pump 111 is used to detect the material from the first bin outlet 108 and the discharge port 106 by using the material humidity instrument 110, and when the detection result is unqualified, the material is sent to the forced circulation evaporator 112 through the axial flow pump 111 for treatment, and then circulated to the MVR crystallization separator 104 through the forced circulation inlet 107 for continuous treatment, and when the detection result is qualified, the material is output to the flash crystallization tank 116 for cooling and flash crystallization, and the flash gas is output from the top of the tank, and the sulfate crystals are output from the bottom of the tank;

[0103] The MVR system further comprises a compressor 115 arranged on the flash gas outlet pipeline of the MVR crystallization separator 104, which is used to compress the flash gas from the MVR crystallization separator 104 and return it to the forced circulation evaporator 112 as part of the steam source;

[0104] The MVR system further comprises a first centrifugal pump 117 and a steam dryer 118 connected in sequence by pipelines, and the inlet of the first centrifugal pump 117 is connected to the tank bottom outlet of the flash crystallization tank 116, which is used to sequentially perform centrifugal dewatering and steam drying on the sulfate crystals output from the bottom of the flash crystallization tank 116, and output the sulfate product.

[0105] The MVR system further comprises a first-stage condensate storage tank 122, a third-stage condensate storage tank 123, a non-condensable gas condenser 124, a second-stage condensate storage tank 125, and a second centrifugal pump 126 connected in series through pipelines, wherein,

[0106] The feed inlet of the first-stage condensate storage tank 122 is connected to the hot medium outlets of the MVR second-stage preheater 102 and the MVR third-stage preheater 103, for performing pressure-reducing gas-liquid separation on the hot medium condensate from the MVR second-stage preheater 102 and the MVR third-stage preheater 103, and outputting first-stage non-condensable gas from the top and first-stage condensate from the bottom;

[0107] The first-stage condensate storage tank 122, the non-condensable gas condenser 124, and the second-stage condensate storage tank 125 are connected in series, for outputting the first-stage non-condensable gas from the first-stage condensate storage tank 122, sending it to the non-condensable gas condenser 124 for cooling, then sending it to the second-stage condensate storage tank 125 for further pressure-reducing gas-liquid separation, and outputting second-stage non-condensable gas from the top and second-stage condensate from the bottom;

[0108] The feed inlet of the third-stage condensate storage tank 123 is connected to the bottom outlets of the first-stage condensate storage tank 122 and the second-stage condensate storage tank 125, and the discharge outlet is connected to the hot medium inlet of the MVR first-stage preheater 101, for receiving the first-stage condensate from the first-stage condensate storage tank 122 and the second-stage condensate from the second-stage condensate storage tank 125 and sending them to the MVR first-stage preheater 101 as its hot medium to preheat the feed of the sulphate solution;

[0109] The steam ejector pump 201 is arranged on the tank top outlet pipeline of the flash crystallization tank 116 in the MVR system, and the outlet end thereof is connected to the hot medium inlet of any one or more of the MVR third-stage preheater 103, the MVR second-stage preheater 102, the forced circulation evaporator 112, and the steam dryer 118 in the MVR system, for pressurizing (such as pressurizing to 150-200 kPa) the flash gas of the flash crystallization tank 116 when the temperature thereof is ≥60℃, and then sending it to any one or more of the MVR third-stage preheater 103, the MVR second-stage preheater 102, the forced circulation evaporator 112, and the steam dryer 118 as a hot medium for secondary utilization;

[0110] The energy-saving system further comprises a heat exchange pipeline 215 arranged in parallel with the steam ejector pump 201, for sending the flash gas of the flash crystallization tank 116 to the MVR second-stage preheater 102 as a hot medium for secondary utilization when the temperature of the flash gas is <60℃.

[0111] An energy-saving method for coupling a dry crystallization steam with an MVR system with multiple energy levels, which adopts the MVR system as shown inFigure 1 The energy-saving system A1 is used for treating sulfate solution. The energy-saving method comprises the following steps:

[0112] (1) When the sulfate solution is treated by the MVR system, flash steam is output from the top of the flash crystallization tank 116, and sulfate crystals are output from the bottom of the tank.

[0113] (2) The temperature of the flash steam output from the top of the flash crystallization tank 116 in step (1) is 65°C. The first controller 211 and the second controller 218 are used to control the related valves on the related material pipelines, so that the flash steam is sent to the MVR third-stage preheater 103, the MVR second-stage preheater 102, the forced circulation evaporator 112 and the steam dryer 118 for pressure boosting to 200 kPa and then sent to the MVR third-stage preheater 103, the MVR second-stage preheater 102, the forced circulation evaporator 112 and the steam dryer 118 as heat medium for secondary utilization.

[0114] (3) The first controller 211 and the second controller 218 are used to control the related valves on the related material pipelines, so that the heat medium condensate in the MVR third-stage preheater 103, the MVR second-stage preheater 102, the forced circulation evaporator 112 and the steam dryer 118 is sent to the fifth condensate tank 202 for pressure reduction gas-liquid separation, and the fifth-stage non-condensed gas is output from the non-condensed gas outlet of the fifth condensate tank 202 to the MVR second-stage preheater 102 as heat medium for secondary utilization, and the fifth-stage condensate is output from the condensate outlet of the fifth condensate tank 202 to the MVR first-stage preheater 101 as heat medium for secondary utilization.

[0115] Results:

[0116] In Example 1, the flash steam output from the top of the flash crystallization tank 116 is sent to the MVR third-stage preheater 103, the MVR second-stage preheater 102, the forced circulation evaporator 112 and the steam dryer 118 as heat medium for energy secondary utilization, thereby reducing the steam consumption of the MVR third-stage preheater 103, the MVR second-stage preheater 102, the forced circulation evaporator 112 and the steam dryer 118.

[0117] In Example 1, the heat medium condensate output from the MVR third-stage preheater 103, the MVR second-stage preheater 102, the forced circulation evaporator 112 and the steam dryer 118 is sent to the fifth condensate tank 202 for pressure reduction gas-liquid separation, and the fifth-stage non-condensed gas is output from the non-condensed gas outlet of the fifth condensate tank 202 to the MVR second-stage preheater 102 as heat medium for energy secondary utilization, and the fifth-stage condensate is output from the condensate outlet of the fifth condensate tank 202 to the MVR first-stage preheater 101 as heat medium for energy secondary utilization, thereby reducing the steam consumption of the MVR second-stage preheater 102 and the MVR first-stage preheater 101.

[0118] In Example 1, the total amount of steam required to be introduced from the outside (such as a park) is only 10 t / h.

[0119] Example 2 (S2)

[0120] An energy-saving method for coupling a dry crystallization steam with an MVR system multi-energy level, using an energy-saving system A1 as shown for processing a sulfate solution; wherein the energy-saving method comprises: Figure 1

[0121] (1) When the sulfate solution is processed by the MVR system, flash steam is output from the top of the flash crystallization tank 116, and sulfate crystals are output from the bottom;

[0122] (2) The flash steam temperature output from the top of the flash crystallization tank 116 in step (1) is 50℃, which is sent to the MVR second-stage preheater 102 as a heat medium for secondary utilization.

[0123] Results:

[0124] In Example 2, the total amount of steam required to be introduced from the outside (such as a park) is only 15 t / h.

[0125] Comparative Example 1 (D1)

[0126] As shown in Figure 2 , the traditional MVR system A1' includes an MVR first-stage preheater 101, an MVR second-stage preheater 102, and an MVR third-stage preheater 103 connected in sequence by pipelines, for sequentially heating and preheating the incoming sulfate solution to output a preheated sulfate solution;

[0127] The MVR system further includes an MVR crystallization separator 104, and its bottom is provided with a storage bin 105, one side of the bottom is provided with a discharge port 106, the lower side wall is respectively provided with a forced circulation inlet 107 and a self-circulation inlet 114, and the top is provided with a flash steam outlet. The bottom of the storage bin 105 is provided with a first bin outlet 108 and a second bin outlet 109, which is used for flash crystallization of the preheated sulfate solution from the MVR third-stage preheater 103, and outputs flash steam from the flash steam outlet, and part of the concentrated liquid containing sulfate crystals is discharged from the discharge port 106, part of which is stored in the storage bin 105, and part of which is discharged from the second bin outlet 109 and returned to the MVR crystallization separator 104 through the self-circulation inlet 114, and part of which is discharged from the first bin outlet 108;

[0128] A first circulation pump 113 is provided on the pipeline from the second bin outlet 109 to the self-circulation inlet 114, which is used to pump the material discharged from the second bin outlet 109 to the MVR crystallization separator 104;

[0129] ​The MVR system further comprises a discharge pipeline, a material humidity instrument 110, an axial flow pump 111, a forced circulation evaporator 112, and a flash crystallization tank 116; a first end of the discharge pipeline is connected to the first bin outlet 108 and the discharge port 106 respectively, a second end of the discharge pipeline is connected to a bottom inlet of the forced circulation evaporator 112 and a feed inlet of the flash crystallization tank 116 respectively, the material humidity instrument 110 is arranged in parallel on the discharge pipeline, and the axial flow pump 111 is arranged on a bottom inlet pipeline of the forced circulation evaporator 112, for detecting the material from the first bin outlet 108 and the discharge port 106 by using the material humidity instrument 110, and when the detection result is unqualified, the material is sent to the forced circulation evaporator 112 by the axial flow pump 111 for processing, and then recycled to the MVR crystallization separator 104 from the forced circulation inlet 107 for continuous processing, and when the detection result is qualified, the material is output to the flash crystallization tank 116 for cooling flash crystallization, and flash gas is output from the tank top and sulfate salt crystals are output from the tank bottom;

[0130] The MVR system further comprises a compressor 115, for compressing the flash gas from the MVR crystallization separator 104 and returning it to the forced circulation evaporator 112 as a part of steam source;

[0131] The MVR system further comprises a first centrifugal pump 117 and a steam dryer 118 connected in sequence by pipelines, and an inlet of the first centrifugal pump 117 is connected to a tank bottom outlet of the flash crystallization tank 116, for sequentially centrifuging and dehydrating and steam drying the sulfate salt crystals output from the tank bottom of the flash crystallization tank 116, and outputting sulfate salt products;

[0132] The MVR system further comprises a flash condenser 119, a fourth-stage condensate storage tank 120, and a second circulating pump 121 connected in sequence by pipelines, and an inlet of the flash condenser 119 is connected to a tank top outlet of the flash crystallization tank 116, for condensing the flash gas from the tank top of the flash crystallization tank 116, collecting condensate by using the fourth-stage condensate storage tank 120 and outputting, and pumping and outputting non-condensable gas by using the second circulating pump 121;

[0133] The MVR system further comprises a first-stage condensate storage tank 122, a third-stage condensate storage tank 123, a non-condensable gas condenser 124, a second-stage condensate storage tank 125, and a second centrifugal pump 126 connected by pipelines;

[0134] A feed inlet of the first-stage condensate storage tank 122 is connected to heat medium outlets of the MVR second-stage preheater 102 and the MVR third-stage preheater 103, for performing pressure reduction gas-liquid separation on the heat medium condensate from the MVR second-stage preheater 102 and the MVR third-stage preheater 103, and outputting first-stage non-condensable gas from the top and first-stage condensate from the bottom;

[0135] The first-stage condensate storage tank 122, the non-condensable gas condenser 124 and the second-stage condensate storage tank 125 are sequentially connected, for outputting the first-stage non-condensable gas from the first-stage condensate storage tank 122 to the non-condensable gas condenser 124 for cooling and then to the second-stage condensate storage tank 125 for further pressure reduction and gas-liquid separation, and outputting the second-stage non-condensable gas from the top and the second-stage condensate from the bottom;

[0136] The feed inlet of the third-stage condensate storage tank 123 is connected to the bottom outlet of the first-stage condensate storage tank 122 and the second-stage condensate storage tank 125 respectively, and the discharge outlet is connected to the heat medium inlet of the MVR first-stage preheater 101, for receiving the first-stage condensate from the first-stage condensate storage tank 122 and the second-stage condensate from the second-stage condensate storage tank 125 and sending them to the MVR first-stage preheater 101 as the heat medium thereof to preheat the sulfate salt solution of the feed in the first stage.

[0137] The sulfate salt solution is treated by using the foregoing conventional MVR system A1', in the following manner:

[0138] (1) When the sulfate salt solution is treated by the MVR system A1', the flash gas is output from the top of the flash crystallization tank 116 thereof, and the sulfate salt crystals are output from the bottom of the tank;

[0139] (2) The flash gas from the top of the flash crystallization tank 116 in step (1) is condensed by using the flash condenser 119, the condensate obtained is collected by using the fourth-stage condensate storage tank 120, and the non-condensable gas obtained is pumped out by using the second circulating pump 121;

[0140] The sulfate salt crystals output from the bottom of the flash crystallization tank 116 in step (1) are centrifugally dewatered and steam-dried by using the first centrifugal pump 117 and the steam dryer 118, and the sulfate salt product is output.

[0141] In the comparative example 1, the total amount of steam required to be introduced from the outside (such as a park) is 18.7 t / h.

[0142] According to the comparison of the examples 1-2 and the comparative example 1, it can be seen that the energy-saving system and the energy-saving method of the application can adopt different energy secondary utilization paths according to the temperature of the flash gas from the top of the flash crystallization tank 116, so as to fully recycle the energy in the flash gas from the top of the flash crystallization tank 116, realize the coupling of the flash gas and the MVR system in multiple energy levels, reduce the steam consumption of the device requiring steam preheating or heating, i.e. reduce the steam demand, reduce the production pressure of the steam in the park, and reduce the processing cost of the sulfate salt.

[0143] While the present application has been described in detail with respect to the preferred embodiments thereof, it will be apparent to those skilled in the art that various modifications and alterations can be made without departing from the spirit and scope of the present application.

Claims

1. An energy-saving system that couples drying crystallization steam with a multi-level MVR system, characterized in that, The energy-saving system includes an MVR system and a steam ejector pump (201). The steam ejector pump (201) is installed on the top outlet pipeline of the flash crystallizer (116) in the MVR system, and its outlet end is connected to the heat medium inlet of any one or more of the MVR third-stage preheater (103), MVR second-stage preheater (102), forced circulation evaporator (112) and steam dryer (118) in the MVR system. It is used to pressurize the flash vapor in the flash crystallizer (116) when the flash vapor temperature is ≥60 ℃ and send it to any one or more of the MVR third-stage preheater (103), MVR second-stage preheater (102), forced circulation evaporator (112) and steam dryer (118) for secondary use as a heat medium when the flash vapor temperature is ≥60 ℃. The energy-saving system also includes a heat exchange pipeline (215), which is connected in parallel with the steam ejector pump (201) and is used to send the flash steam of the flash crystallizer (116) in the MVR system to the second-stage preheater (102) of the MVR for secondary use as a heat medium when the flash steam temperature is <60 ℃.

2. The energy-saving system according to claim 1, characterized in that, The energy-saving system also includes a fifth condensate tank (202), which has a non-condensable gas outlet at the top and a condensate outlet at the bottom. Its inlet is connected to the heat medium outlet of any one or more of the following in the MVR system: the MVR third-stage preheater (103), the MVR second-stage preheater (102), the forced circulation evaporator (112), and the steam dryer (118). Its non-condensable gas outlet is connected to the heat medium inlet of the MVR second-stage preheater (102), and its condensate outlet is connected to the heat medium inlet of the MVR first-stage preheater (101). This is used to ensure that the flash vapor temperature in the flash crystallizer (116) is ≥60°C. At ℃, the heat medium condensate is received from any one or more of the MVR third-stage preheater (103), MVR second-stage preheater (102), forced circulation evaporator (112) and steam dryer (118), and depressurized gas-liquid separation is performed on it. The fifth-stage non-condensable gas is output from its non-condensable gas outlet to the MVR second-stage preheater (102) for secondary use as a heat medium, and the fifth-stage condensate is output from its condensate outlet to the MVR first-stage preheater (101) for secondary use as a heat medium.

3. The energy-saving system according to claim 2, characterized in that, A third circulation pump (203) is also installed on the pipeline from the condensate outlet of the fifth condensate tank (202) to the heat medium inlet of the first-stage preheater (101) of the MVR, and a second valve (205) is installed at the outlet end of the third circulation pump (203); and / or, The forced circulation evaporator (112) is equipped with valves at its heat medium inlet, including a third valve (206) located on its steam heat source line and a fourth valve (207) located on its secondary heat source line; and / or, A fifth valve (208) is installed on the heat medium inlet pipeline of the MVR second-stage preheater (102); and / or, A sixth valve (209) is installed on the pipeline from the heat medium outlet of the MVR second-stage preheater (102) to the inlet of the fifth condensate tank (202). The sixth valve (209) is located between the heat medium outlet of the MVR second-stage preheater (102) and the heat medium outlet of the MVR third-stage preheater (103); and / or, A seventh valve (210) is installed on the pipeline from the fifth condensate tank (202) to the outlet of the fifth valve (208).

4. The energy-saving system according to claim 3, characterized in that, The energy-saving system also includes a first controller (211), which is connected to one or more of the electrical signals of the second valve (205), the third valve (206), the fourth valve (207), the fifth valve (208), the sixth valve (209), and the seventh valve (210).

5. The energy-saving system according to any one of claims 1-4, characterized in that, An eighth valve (212) is installed on the heat exchange pipeline (215); and / or, The fifth condensate tank (202) is equipped with a first valve (204) at its condensate outlet; and / or, The heat medium inlet of the steam dryer (118) is equipped with valves, including an eleventh valve (216) located on its steam heat source line and a ninth valve (213) located on its secondary heat source line; and / or, The energy-saving system also includes a second pipeline (217), and the inlet end of the second pipeline (217) is connected to the outlet of any one or more of the heat medium in the MVR third-stage preheater (103), the forced circulation evaporator (112), and the MVR second-stage preheater (102), respectively. The outlet end is connected to the inlet end of the fifth condensate tank (202), which is used to collect the heat medium outlet material of any one or more of the MVR third-stage preheater (103), the forced circulation evaporator (112), and the MVR second-stage preheater (102) and send it to the fifth condensate tank (202) after it is collected through the second pipeline (217). A tenth valve (214) is provided on the second pipeline (217).

6. The energy-saving system according to claim 5, characterized in that, The energy-saving system also includes a second controller (218), which is connected to one or more of the eighth valve (212), the ninth valve (213), the tenth valve (214), the steam ejector pump (201), the first valve (204), and the eleventh valve (216) via electrical signals.

7. The energy-saving system according to any one of claims 1-4 and 6, characterized in that, The MVR system includes an MVR first-stage preheater (101), an MVR second-stage preheater (102), and an MVR third-stage preheater (103) connected in sequence by pipelines, which are used to sequentially preheat the fed sulfate solution by heat exchange and output the preheated sulfate solution. The MVR system also includes an MVR crystallizer (104), which has a storage silo (105) at the bottom, a discharge port (106) on one side of the bottom, a feed inlet, a forced circulation inlet (107) and a self-circulation inlet (114) on the lower side wall, and a flash steam outlet at the top. The storage silo (105) has a first silo outlet (108) and a second silo outlet (109) at the bottom, and is connected to the third stage preheater (104) of the MVR through its feed inlet. 3) The material outlet is used to flash crystallize the preheated sulfate solution from the third stage preheater (103) of the MVR, and output flash vapor from its top flash vapor outlet. The concentrated liquid containing sulfate crystals is partially discharged from its outlet (106), partially stored in its storage silo (105), partially discharged from its second silo outlet (109) and returned to the MVR crystallizer (104) through its circulation inlet (114), and partially discharged from its first silo outlet (108). A first circulation pump (113) is installed on the pipeline from the outlet (109) of the second silo to the circulation inlet (114) to pump the material discharged from the outlet (109) of the second silo to the MVR crystallizer (104). The MVR system also includes a discharge pipeline, a material humidity meter (110), an axial flow pump (111), a forced circulation evaporator (112), and a flash crystallizer (116). The first end of the discharge pipeline is connected to the outlet (108) of the first silo and the discharge port (106), respectively. The second end of the discharge pipeline is connected to the bottom inlet of the forced circulation evaporator (112) and the inlet of the flash crystallizer (116), respectively. The material humidity meter (110) is connected in parallel on the discharge pipeline, and the axial flow pump (111) is located on the forced circulation evaporator. The bottom inlet pipeline of the device (112) is used to detect the material from the outlet (108) and discharge port (106) of the first silo using a material humidity meter (110). If the detection result is unqualified, the material is sent to the forced circulation evaporator (112) by the axial flow pump (111) for processing and then circulated from the forced circulation inlet (107) to the MVR crystallizer (104) for further processing. If the detection result is qualified, the material is output to the flash crystallizer (116) for cooling flash crystallization and flash vapor is output from the top of the tank and sulfate crystals are output from the bottom of the tank. The MVR system also includes a compressor (115) located on the flash outlet line of the MVR crystallizer (104) for compressing the flash vapor from the MVR crystallizer (104) and sending it back to the forced circulation evaporator (112) as part of its steam source; The MVR system also includes a first centrifugal pump (117) and a steam dryer (118) connected in sequence by pipelines. The inlet of the first centrifugal pump (117) is connected to the bottom outlet of the flash crystallizer (116) for centrifugal dehydration and steam drying of the sulfate crystals output from the bottom of the flash crystallizer (116) in sequence, and output sulfate products. The MVR system also includes a first-stage condensate storage tank (122), a third-stage condensate storage tank (123), a non-condensable gas condenser (124), a second-stage condensate storage tank (125), and a second centrifugal pump (126) connected by pipelines; wherein, The inlet of the first-stage condensate storage tank (122) is connected to the heat medium outlet of the second-stage preheater (102) and the third-stage preheater (103) of the MVR, for depressurization gas-liquid separation of the heat medium condensate from the second-stage preheater (102) and the third-stage preheater (103) of the MVR, and outputs the first-stage non-condensable gas from the top and the first-stage condensate from the bottom; The first-stage condensate storage tank (122), the non-condensable gas condenser (124), and the second-stage condensate storage tank (125) are connected in sequence to output the first-stage non-condensable gas from the first-stage condensate storage tank (122) and send it to the non-condensable gas condenser (124) for cooling before sending it to the second-stage condensate storage tank (125) for further depressurization and gas-liquid separation. The second-stage non-condensable gas is output from the top and the second-stage condensate is output from the bottom. The inlet of the third-stage condensate storage tank (123) is connected to the bottom outlets of the first-stage condensate storage tank (122) and the second-stage condensate storage tank (125), respectively. The outlet is connected to the heat medium inlet of the first-stage preheater (101) of the MVR, which is used to receive the first-stage condensate from the first-stage condensate storage tank (122) and the second-stage condensate from the second-stage condensate storage tank (125) and send them to the first-stage preheater (101) of the MVR as its heat medium to preheat the fed sulfate solution in the first stage.

8. An energy-saving method for coupling dry crystallization steam with a multi-level MVR system, characterized in that, The energy-saving system described in any one of claims 1-7 is used.

9. The energy-saving method according to claim 8, characterized in that, The energy-saving method includes: (1) When the sulfate solution is processed by the MVR system, flash vapor is output from the top of the flash crystallizer (116) and sulfate crystals are output from the bottom of the tank; (2) When the flash vapor temperature output from the top of the flash crystallizer (116) in step (1) is ≥60 ℃, it is sent to the steam ejector pump (201) for pressurization and then sent to any one or more of the MVR third-stage preheater (103), MVR second-stage preheater (102), forced circulation evaporator (112) and steam dryer (118) as a heat medium for secondary use; When the temperature of the flash vapor output from the top of the flash crystallizer (116) in step (1) is <60 ℃, it is sent to the second stage preheater (102) of the MVR for secondary use as a heat medium.

10. The energy-saving method according to claim 9, characterized in that, The energy-saving method further includes step (3), which involves sending the condensate of any one or more of the heat medium from the MVR third-stage preheater (103), the MVR second-stage preheater (102), the forced circulation evaporator (112), and the steam dryer (118) to the fifth condensate tank (202) for depressurization gas-liquid separation, and outputting the fifth-stage non-condensable gas from its non-condensable gas outlet to the MVR second-stage preheater (102) for secondary use as a heat medium, and outputting the fifth-stage condensate from its condensate outlet to the MVR first-stage preheater (101) for secondary use as a heat medium.

11. The energy-saving method according to claim 9, characterized in that, The first controller (211) controls one or more of the second valve (205), the third valve (206), the fourth valve (207), the fifth valve (208), the sixth valve (209), and the seventh valve (210) respectively, thereby controlling the secondary utilization path of energy.

12. The energy-saving method according to any one of claims 9-11, characterized in that, The second controller (218) controls one or more of the eighth valve (212), the ninth valve (213), the tenth valve (214), the steam ejector pump (201), the first valve (204), and the eleventh valve (216) respectively, thereby controlling the secondary utilization path of energy.

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