A device system and method for sulfuric acid concentration online desalination coupling energy saving

Abstract

The present invention provides a device system and method for sulfuric acid concentration online desalination coupled energy saving, belonging to the technical field of waste sulfuric acid recovery and sulfuric acid concentration. By opening a part of sulfuric acid from a concentrated sulfuric acid storage device, after mixing, diluting and cooling the concentrated sulfuric acid, using resin to adsorb the salt in the sulfuric acid, the desalted sulfuric acid obtained replaces water as the capture water of gaseous sulfuric acid in the sulfuric acid concentration process to return to the system, which can not only reduce the overall salt content in the sulfuric acid concentration system, but also reduce the loss of gaseous sulfuric acid in the sulfuric acid concentration system and the amount of water directly introduced. The device system is simple in device, simple in method, and has a small sulfuric acid processing volume. It can quickly, effectively, and online remove the salt in sulfuric acid, avoid the accumulation and scaling of salt in sulfuric acid in the system, and at the same time reduce the energy consumption of the sulfuric acid concentration system, with good economic and environmental benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of waste sulfuric acid recovery and sulfuric acid concentration, and relates to a sulfuric acid concentration online desalination coupled energy-saving device system and method. Background Art

[0002] Concentrated sulfuric acid is an important industrial raw material, widely used in chemical, petroleum, metallurgy, electric power, papermaking and other industries. Sulfuric acid is usually prepared by contact method using pyrite slag or sulfur as raw materials. The concentration of concentrated sulfuric acid decreases after use and impurities are introduced during use. Generally, sulfuric acid is concentrated by a sulfuric acid concentration device to gradient concentrate sulfuric acid and reuse waste sulfuric acid. Waste sulfuric acid generally needs to be concentrated to more than 90% before it has reuse value. However, due to the introduction of the preparation process and the contact corrosion of equipment and concentrated sulfuric acid during use, there are a large number of metal impurities in sulfuric acid. During the sulfuric acid concentration process, as sulfuric acid is gradually concentrated, the solubility of metal impurities in sulfuric acid decreases, exceeding the saturated solubility of sulfuric acid to form metal salts that precipitate and deposit in the sulfuric acid concentration device. At the same time, sulfuric acid needs to be cooled after concentration, which further reduces the solubility of metal impurities, leading to equipment scaling, pipeline blockage and reduced equipment heat transfer efficiency. The normal operation of the device is affected while increasing energy consumption.

[0003] CN105152229A discloses a waste sulfuric acid purification and recovery system and recovery process containing high-concentration ferrous sulfate. The recovery system includes a waste acid storage tank, a cooling crystallizer, a centrifuge and a membrane separation device. The recovery process includes: (1) transporting the waste acid into the waste acid storage tank for storage; (2) the waste acid storage tank transports the waste acid into the cooling crystallizer through a centrifugal pump, and the cooling crystallizer transports the crystallized waste acid into the centrifuge; (3) the centrifuge separates the crystallized waste acid into ferrous sulfate heptahydrate crystals and other liquid phases, and transports the separated liquid phase into the membrane separation device; (4) the membrane separation device separates the sulfuric acid in the liquid phase from the Fe 2+ The concentrated solution is separated and transported to the waste acid storage tank to continue to repeat the above steps until the ferrous sulfate heptahydrate crystals and sulfuric acid are completely recovered. The above method uses cooling crystallization + membrane separation to purify saline sulfuric acid, but the separation membrane can only tolerate sulfuric acid with a concentration of less than 40%, and cannot be used under high-concentration sulfuric acid conditions. In addition, the membrane separation device is expensive and has low industrial feasibility.

[0004] In addition, the most commonly used sulfuric acid desalination method is to stop the machine and wash the salt. Although it is simple to operate, the high-temperature equipment needs to be stopped and cooled down continuously for salt washing, and then heated up again after the salt washing is completed. This not only affects the normal operation of the device, but also causes a certain degree of damage to the equipment, affecting the operating life of the device.

[0005] In summary, it is an urgent problem to be solved by those skilled in the art to provide a device and method for concentrating and desalting sulfuric acid with a simple and efficient process, low cost and no need to stop the process. Summary of the invention

[0006] The object of the present invention is to provide a device system and method for sulfuric acid concentration and online desalination coupled energy saving, which opens a part of sulfuric acid from a concentrated sulfuric acid storage device, uses resin to adsorb salt in the sulfuric acid after treatment, and then uses desalted sulfuric acid instead of spray water to capture gas phase sulfuric acid, and finally returns to the sulfuric acid concentration system, which can not only reduce the overall salt content in the sulfuric acid concentration system, but also reduce sulfuric acid loss and energy consumption in the sulfuric acid concentration process; the device system and process are simple, the sulfuric acid treatment volume is small, the investment is small and the industrial feasibility is high.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a sulfuric acid concentration online desalination coupled energy-saving device system, the device system comprising a sulfuric acid concentration device, a concentrated sulfuric acid storage device, a desalination unit and a gas phase sulfuric acid capture device connected in sequence;

[0009] The sulfuric acid concentration device is provided with a dilute sulfuric acid liquid inlet pipeline;

[0010] The sulfuric acid concentration device is bidirectionally connected to the gas phase sulfuric acid capture device;

[0011] The desalination unit comprises a mixing device, a cooling device and a resin adsorption device connected in sequence;

[0012] The outlet of the concentrated sulfuric acid storage device is connected to two pipelines, one pipeline is connected to the mixing device, and the other pipeline is connected to a downstream user of concentrated sulfuric acid;

[0013] The resin adsorption device is connected to the gas phase sulfuric acid capture device.

[0014] The device system provided by the present invention performs desalination by adding a desalination unit of a specific resin adsorption device, and then connects with a gas-phase sulfuric acid capture device through the resin adsorption device, and returns the desalted sulfuric acid to the sulfuric acid concentration system as the capture water of the gas-phase sulfuric acid in the sulfuric acid concentration process instead of water, which can not only reduce the overall salt content in the sulfuric acid concentration system to maintain it below the saturated solubility, thereby avoiding salt precipitation, but also avoid the loss of sulfuric acid caused by the loss of gas-phase sulfuric acid in the sulfuric acid concentration process and the excessive acid content of waste water, reduce the amount of water directly introduced, and thus reduce the energy consumption waste in the sulfuric acid concentration process.

[0015] It is worth noting that the mixing device in the desalination unit is connected to an outlet pipeline of the concentrated sulfuric acid storage device, which can desalinate online without stopping the machine and does not affect the use of downstream users, thereby improving production efficiency and having high industrial feasibility.

[0016] As a preferred technical solution of the present invention, the resin adsorption device is filled with ion exchange resin.

[0017] The type of the ion exchange resin includes any one of LSC-957, XDA-1G or ZXC-9-S.

[0018] It is worth noting that the ion exchange resin selected in the present invention is a resin that can adsorb metal acid salts but hardly adsorb sulfuric acid.

[0019] As a preferred technical solution of the present invention, a condensing device is connected to the top of the gas phase sulfuric acid capture device.

[0020] The outlet of the condensing device is connected to two pipelines, one pipeline is connected to the mixing device, and the other pipeline is discharged externally.

[0021] In the present invention, the condensed acid water in the gas phase sulfuric acid capture device can be used as the sulfuric acid dilution acid water required in the mixing device, which further reduces the cost.

[0022] In a second aspect, the present invention provides a method for energy saving coupled with online desalination of sulfuric acid concentration, the method being carried out using the device described in the first aspect, comprising the following steps:

[0023] (1) Acidic water and concentrated sulfuric acid discharged from a concentrated sulfuric acid storage device are mixed in a mixing device, and then cooled in a cooling device and subjected to resin adsorption in a resin adsorption device to obtain deionized sulfuric acid;

[0024] (2) The desalinated sulfuric acid obtained in step (1) is transported to a gas phase sulfuric acid capture device, and then reused in a sulfuric acid concentration device.

[0025] The method provided by the present invention has a small amount of sulfuric acid to be processed in the concentrated sulfuric acid desalination process, and only needs to open a small amount of sulfuric acid from a concentrated sulfuric acid storage device. After the concentrated sulfuric acid is mixed, diluted and cooled, a resin is used to adsorb salt in the sulfuric acid to obtain desalted sulfuric acid. At the same time, desalted sulfuric acid is used instead of water as a gas phase capture liquid in the sulfuric acid concentration process, which has a better capture effect than aqueous sulfuric acid, reduces the amount of water directly introduced into the sulfuric acid concentration system, not only realizes the recycling of desalted sulfuric acid, avoids sulfuric acid loss and excessive acid content in wastewater, but also can reduce the overall salt content in the sulfuric acid concentration system.

[0026] It is worth noting that although the proportion of concentrated sulfuric acid subjected to adsorption desalination is small, it is fully capable of solving the problem of re-salting in the sulfuric acid concentration system without affecting the downstream users of concentrated sulfuric acid. In addition, the use of desalted sulfuric acid instead of water as the gas phase capture liquid in the sulfuric acid concentration process can increase the gas phase sulfuric acid capture efficiency by 40-65%.

[0027] As a preferred technical solution of the present invention, the mass concentration of the concentrated sulfuric acid in step (1) is 70-98%, for example, it can be 72%, 75%, 78%, 80%, 82%, 85%, 88%, 90%, 92%, 95% or 96%, etc., but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0028] The metal ions contained in the concentrated sulfuric acid in step (1) include Fe 3+ , Fe 2+ Cr 3+ 、Ni 2+ 、Mo 2+ , Mn 2+ Mg 2+ , Cu 2+ or Zn 2+ Any one or a combination of at least two of the following, wherein the combination is typically but not limited to: Fe 3+ and Fe 2+ Combination of Fe 3+ and Cr 3+ Combination of Fe 3+ 、Mo 2+ and Mn 2+ Combination or Fe 3+ , Fe 2+ , Mn 2+ and Zn 2+ Combinations of Fe 3+ Cr 3+ 、Ni 2+ Or Mo 2+ Any one or a combination of at least two of the following.

[0029] The total amount of metal ions contained in the concentrated sulfuric acid in step (1) is 200-500 ppm, for example, it can be 220 ppm, 250 ppm, 280 ppm, 300 ppm, 320 ppm, 350 ppm, 380 ppm, 400 ppm, 420 ppm, 450 ppm or 480 ppm, but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0030] In the present invention, the total amount of metal ions refers to the total mass concentration of metal ions.

[0031] The concentrated sulfuric acid discharged from the open circuit in step (1) is 0.01-0.1% of the total amount of concentrated sulfuric acid in the concentrated sulfuric acid storage device, for example, it can be 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08% or 0.09%, etc., but is not limited to the listed values. Other values ​​within the numerical range are also applicable, preferably 0.01-0.05%.

[0032] It is worth noting that the salt formation problem in the sulfuric acid concentration system can be solved by opening a small portion of sulfuric acid in the concentrated sulfuric acid storage device for adsorption and desalination.

[0033] As a preferred technical solution of the present invention, the acidic water in step (1) is acidic water condensed by a condensation device.

[0034] The pH value of the acidic water in step (1) is 0.5-3, for example, it can be 0.6, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.6 or 2.8, but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0035] The acidic water in step (1) contains nitric acid and / or sulfuric acid.

[0036] The mass ratio of the acidic water to the concentrated sulfuric acid produced in step (1) is 1:(0.25-4), for example, it can be 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, 1:2.2, 1:2.5, 1:2.8, 1:3, 1:3.2, 1:3.5 or 1:3.8, but is not limited to the values ​​listed above. Other values ​​within the numerical range are also applicable, preferably (0.5-2):1.

[0037] It is worth noting that the present invention uses acidic water to dilute concentrated sulfuric acid instead of pure water, because the sulfuric acid concentration process will produce a stream of acidic water. On the one hand, this stream of acidic water has no effect on the resin adsorption process after being used to dilute sulfuric acid. On the other hand, the use of acidic water can reduce the use of pure water and the discharge of pickling wastewater, reduce the loss of sulfuric acid discharged with the wastewater, and reduce costs.

[0038] It is worth noting that when the amount of acidic water is too much, the concentrated sulfuric acid will be diluted too thin. Although it has no effect on sulfuric acid desalination, if the same concentrated sulfuric acid processing capacity is to be achieved, the amount of dilute sulfuric acid will be greater than the required amount of water for gaseous sulfuric acid capture, resulting in excessive water evaporation for sulfuric acid concentration, increasing the energy consumption for sulfuric acid concentration; if the amount of acidic water is too little, the concentration of sulfuric acid after dilution is still high, which will damage the resin skeleton and affect the resin desalination effect.

[0039] As a preferred technical solution of the present invention, after the cooling in step (1), the temperature of the sulfuric acid is 20-80°C, for example, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C or 75°C, etc., but is not limited to the listed values, and other values ​​within the numerical range are also applicable, preferably 40-80°C.

[0040] In the present invention, after the concentrated sulfuric acid is diluted, the heat of sulfuric acid dilution needs to be removed in time to prevent the high-temperature sulfuric acid from damaging the resin.

[0041] As a preferred technical solution of the present invention, the adsorption space velocity of the resin adsorption in step (1) is 0.2-4BV / h, for example, it can be 0.5BV / h, 0.8BV / h, 1BV / h, 1.5BV / h, 2BV / h, 2.5BV / h, 3BV / h or 3.5BV / h, but is not limited to the listed values. Other values ​​within the numerical range are also applicable, preferably 0.2-2BV / h.

[0042] In the present invention, the pressure of the resin adsorption is normal pressure.

[0043] As a preferred technical solution of the present invention, the total amount of metal ions contained in the desalted sulfuric acid in step (1) is less than 50 ppm, for example, it can be 45 ppm, 40 ppm, 35 ppm, 30 ppm, 25 ppm, 20 ppm or 10 ppm, but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0044] As a preferred technical solution of the present invention, the method comprises the following steps:

[0045] (1) Acidic water with a pH value of 0.5-3 and concentrated sulfuric acid discharged from a concentrated sulfuric acid storage device are mixed in a mixing device at a mass ratio of 1:(0.25-4), cooled to a temperature of 20-80° C. by a cooling device, and then subjected to resin adsorption in a resin adsorption device at an adsorption space velocity of 0.2-4 BV / h to obtain desalted sulfuric acid containing a total amount of metal ions less than 50 ppm;

[0046] The mass concentration of the concentrated sulfuric acid is 70-98%; the metal ions contained in the concentrated sulfuric acid include Fe 3+ , Fe 2+ Cr 3+ 、Ni 2+ 、Mo 2+ , Mn 2+ Mg 2+ , Cu 2+ or Zn 2+ Any one or a combination of at least two of the following; the total amount of metal ions contained in the concentrated sulfuric acid is 200-500ppm; the concentrated sulfuric acid discharged from the open circuit is 0.01-0.1% of the total amount of concentrated sulfuric acid in the concentrated sulfuric acid storage device;

[0047] (2) The desalinated sulfuric acid obtained in step (1) is transported to a gas phase sulfuric acid capture device, and then reused in a sulfuric acid concentration device.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] (1) The device system and method provided by the present invention open a circuit to discharge part of the concentrated sulfuric acid in the concentrated sulfuric acid storage device, mix and dilute the concentrated sulfuric acid and cool it, then use resin to adsorb the salt in the sulfuric acid, and the obtained desalted sulfuric acid is reused as spray water in the gas phase sulfuric acid capture device, and then returned to the sulfuric acid concentration device. This can not only solve the salt formation problem in the sulfuric acid concentration system, avoid material loss caused by the discharge of desalted sulfuric acid, improve the utilization rate of sulfuric acid, and reduce resource waste, but also avoid sulfuric acid loss caused by the loss of gas phase sulfuric acid during the sulfuric acid concentration process and excessive acid content in waste water, reduce the amount of water directly introduced, and thus reduce energy consumption waste in the sulfuric acid concentration process;

[0050] (2) The device system and method provided by the present invention can not only reduce the salt content in sulfuric acid and maintain it below the saturated solubility, thereby avoiding salt precipitation, but also effectively solve the salt formation problem of the sulfuric acid concentration unit, avoid equipment scaling, pipeline blockage, reduced heat exchanger efficiency and other problems, and improve production efficiency; in addition, the spray capture effect of using desalted sulfuric acid is better than that of water spray capture, thereby reducing the loss of gaseous sulfuric acid and reducing the acid content in sulfuric acid concentration wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 The sulfuric acid concentration online desalination coupled energy-saving device system provided in Example 1;

[0052] Among them, 1-sulfuric acid concentration device, 2-concentrated sulfuric acid storage device, 3-mixing device, 4-cooling device, 5-resin adsorption device, 6-gas phase sulfuric acid capture device, 7-condensation device. DETAILED DESCRIPTION

[0053] It should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0054] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0055] In the following specific embodiments of the present invention, the waste dilute sulfuric acid comes from the sulfuric acid (nitrated waste sulfuric acid) recovered from the nitration reaction unit of the DNT process of the TDI device of Wanhua Chemical, which is stored in a concentrated sulfuric acid storage device after concentration. The resins are all purchased through commercial channels. The test method for the metal ion content includes: using any one of AAS atomic absorption spectrometer, ICP-OES inductively coupled plasma emission spectrometer or ICP-MS inductively coupled plasma mass spectrometer for testing.

[0056] Example 1

[0057] This embodiment provides a sulfuric acid concentration online desalination coupled energy saving device system (such as Figure 1 As shown), the device system includes a sulfuric acid concentration device 1, a concentrated sulfuric acid storage device 2, a desalination unit and a gas phase sulfuric acid capture device 6 connected in sequence;

[0058] The sulfuric acid concentration device 1 is provided with a waste dilute sulfuric acid inlet pipeline;

[0059] The sulfuric acid concentration device 1 is bidirectionally connected to the gas phase sulfuric acid capture device 6;

[0060] The desalination unit comprises a mixing device 3, a cooling device 4 and a resin adsorption device 5 which are connected in sequence; the resin adsorption device 5 is filled with an ion exchange resin of model ZXC-9-S;

[0061] The outlet of the concentrated sulfuric acid storage device 2 is connected to two pipelines, one pipeline is connected to the mixing device 3, and the other pipeline is connected to the concentrated sulfuric acid downstream user;

[0062] The resin adsorption device 5 is connected to the gas phase sulfuric acid capture device 6;

[0063] The top of the gas phase sulfuric acid capture device 6 is connected to a condensing device 7; the outlet of the condensing device 7 is connected to two pipelines, one pipeline is connected to the mixing device 3, and the other pipeline is discharged to the outside.

[0064] Example 2

[0065] This embodiment provides a sulfuric acid concentration online desalination coupled energy-saving device system. Except that the resin adsorption device is filled with ion exchange resin of model LSC-957, other conditions are the same as those of Example 1.

[0066] Example 3

[0067] This embodiment provides a sulfuric acid concentration online desalination coupled energy-saving device system. Except that the resin adsorption device is filled with an ion exchange resin of model XDA-1G, other conditions are the same as those of Example 1.

[0068] Comparative Example 1

[0069] This comparative example provides a concentrated sulfuric acid desalination device system, except that the resin adsorption device is not connected to the gas phase sulfuric acid capture device, other conditions are the same as those in Example 1.

[0070] Application Example 1

[0071] This application example provides a method for energy saving coupled with online desalination of sulfuric acid concentration, using the device system provided in Example 1, including the following steps:

[0072] (1) Acidic water and concentrated sulfuric acid discharged from the concentrated sulfuric acid storage device 2 are mixed in a mixing device 3 at a mass ratio of 1:3, cooled to a temperature of 50° C. by a cooling device 4, and then subjected to resin adsorption in a resin adsorption device 5 at normal pressure and an adsorption space velocity of 0.5 BV / h to obtain deionized sulfuric acid;

[0073] The concentrated sulfuric acid discharged from the open circuit is 0.02% of the total amount of concentrated sulfuric acid in the concentrated sulfuric acid storage device 2; the acidic water is the acidic water condensed by the condensation device 7; the pH value of the acidic water is about 0.54; the acidic water contains 14483 ppm of sulfuric acid and 41 ppm of nitric acid;

[0074] (2) The desalinated sulfuric acid obtained in step (1) is transported to the gas phase sulfuric acid capture device 6, and then reused in the sulfuric acid concentration device 1.

[0075] In this application example, the compositions of concentrated sulfuric acid in step (1) and sulfuric acid before and after resin adsorption are shown in Table 1.

[0076] Table 1

[0077]

[0078] Application Example 2

[0079] This application example provides a method for energy saving coupled with online desalination of sulfuric acid concentration, using the device system provided in Example 2, including the following steps:

[0080] (1) Acidic water and concentrated sulfuric acid discharged from a concentrated sulfuric acid storage device are mixed in a mixing device at a mass ratio of 1:1, cooled to a temperature of 60° C. in a cooling device, and then subjected to resin adsorption in a resin adsorption device at normal pressure and an adsorption space velocity of 1.5 BV / h to obtain deionized sulfuric acid;

[0081] The concentrated sulfuric acid discharged from the open circuit is 0.05% of the total amount of concentrated sulfuric acid in the concentrated sulfuric acid storage device; the acidic water is the acidic water condensed by the condensing device; the pH value of the acidic water is about 0.58; the acidic water contains 12949 ppm of sulfuric acid and 34 ppm of nitric acid;

[0082] (2) The desalinated sulfuric acid obtained in step (1) is transported to a gas phase sulfuric acid capture device, and then reused in a sulfuric acid concentration device.

[0083] In this application example, the compositions of concentrated sulfuric acid in step (1) and sulfuric acid before and after resin adsorption are shown in Table 2.

[0084] Table 2

[0085]

[0086] Application Example 3

[0087] This application example provides a method for energy saving coupled with online desalination of sulfuric acid concentration, using the device system provided in Example 3, including the following steps:

[0088] (1) Acidic water and concentrated sulfuric acid discharged from a concentrated sulfuric acid storage device are mixed in a mixing device at a mass ratio of 1:2, cooled to a temperature of 40° C. in a cooling device, and then subjected to resin adsorption in a resin adsorption device at normal pressure and an adsorption space velocity of 0.3 BV / h to obtain desalted sulfuric acid;

[0089] The concentrated sulfuric acid discharged from the open circuit is 0.01% of the total amount of concentrated sulfuric acid in the concentrated sulfuric acid storage device; the acidic water is the acidic water condensed by the condensing device; the pH value of the acidic water is about 0.69; the acidic water contains 10421 ppm of sulfuric acid;

[0090] (2) The desalinated sulfuric acid obtained in step (1) is transported to a gas phase sulfuric acid capture device, and then reused in a sulfuric acid concentration device.

[0091] In this application example, the compositions of concentrated sulfuric acid in step (1) and sulfuric acid before and after resin adsorption are shown in Table 3.

[0092] Table 3

[0093]

[0094] It can be seen from Table 1-3 that the device system and method used in this application example 1-3 can remove most of the metal impurities in concentrated sulfuric acid, avoid the precipitation of metal impurities during the sulfuric acid concentration and cooling process, and then return the desalted sulfuric acid to the sulfuric acid concentration system instead of water as the spray capture liquid, which can not only solve the salt formation problem of the sulfuric acid concentration system, but also reduce the amount of water directly introduced, and the energy consumption is reduced by 540KW / h, 1350KW / h, and 360KW / h respectively. At the same time, this method can also improve the utilization rate of sulfuric acid, reduce the excessive loss of sulfuric acid from the gas phase caused by the use of water spray capture, reduce resource waste, and be beneficial to environmental protection.

[0095] Application Example 4

[0096] This application example provides a method for energy saving by coupling online desalination of sulfuric acid concentration. Except that the mass ratio of acidic water to concentrated sulfuric acid discharged from the open circuit in step (1) is 1:4, the rest is the same as that in application example 1.

[0097] In this application example, the compositions of concentrated sulfuric acid in step (1) and sulfuric acid before and after resin adsorption are shown in Table 4.

[0098] Table 4

[0099]

[0100] It can be seen from Table 4 that when the amount of acidic water is large, although it has no effect on sulfuric acid desalination, if the same concentrated sulfuric acid treatment capacity is to be achieved, the amount of dilute sulfuric acid will be greater than the required amount of water to be captured by gaseous sulfuric acid, resulting in excessive amount of water to be evaporated for sulfuric acid concentration, increasing the energy consumption for sulfuric acid concentration.

[0101] Application Example 5

[0102] This application example provides a method for energy saving coupled with online desalination of sulfuric acid concentration. Except that the adsorption space velocity in step (1) is 5 BV / h (the space velocity is too fast, the resin and sulfuric acid do not complete ion exchange, and the sulfuric acid flows out of the resin column, reducing the desalination efficiency), the rest is the same as application example 1.

[0103] In this application example, the compositions of concentrated sulfuric acid in step (1), sulfuric acid before resin adsorption, and desalted sulfuric acid at the initial stage of adsorption are shown in Table 5.

[0104] Table 5

[0105]

[0106] It can be seen from Table 5 that: when the space velocity of resin adsorption is too fast, the metal ion concentration in the desalted sulfuric acid obtained in the initial stage of adsorption can meet the requirements, but in the later stage of adsorption, because the resin is partially saturated with adsorption, when the adsorption space velocity is too fast, the resin and sulfuric acid cannot effectively complete ion exchange, and the sulfuric acid flows out of the resin column, reducing the desalination effect.

[0107] Comparative application example 1

[0108] This comparative application example provides a method for online desalination of sulfuric acid concentration, using the device system provided in comparative example 1, except that step (2) is not performed, other conditions are the same as those in application example 1.

[0109] Although the device system and method adopted in this comparative application example can remove most of the metal impurities in the concentrated sulfuric acid discharged from the open circuit, the total amount of sulfuric acid in the system is reduced because the desalted sulfuric acid is not returned to the sulfuric acid concentration system, which cannot meet the sulfuric acid usage needs of downstream users. Not only can it not solve the salt formation problem of the sulfuric acid concentration system, it can also not reduce the energy consumption of the sulfuric acid concentration system, and it causes the acid content in the discharged wastewater to be too high, which in turn makes the wastewater treatment cost too high.

[0110] Comparative Application Example 2

[0111] This comparative application example provides a conventional method for sulfuric acid concentration and desalination. During the sulfuric acid concentration and cooling process, as the solubility of metal impurities decreases, metal salts gradually precipitate, causing equipment scaling, pipeline blockage, and reduced heat exchanger efficiency. At this time, waste sulfuric acid is regularly discharged and fresh sulfuric acid is added to reduce the content of metal impurities in sulfuric acid, or the system is stopped regularly (about once a month) for flushing.

[0112] The method provided in this comparative application example causes material waste and affects the stable operation of the device. In addition, water is used to capture sulfuric acid in the gas phase. After the water captures the sulfuric acid, it enters the sulfuric acid concentration boiler and is evaporated again, causing energy waste. The sulfuric acid content in the wastewater is about 26054 ppm, and the amount of sulfuric acid lost from the gas phase is higher than the amount captured by using sulfuric acid, which will also increase material waste and wastewater treatment costs.

[0113] From the comparison of the above application examples and comparative application examples, it can be seen that, firstly, the device system and method provided by the present invention can effectively solve the salt formation problem of the sulfuric acid concentration unit, improve the quality of sulfuric acid, reduce process abnormalities caused by reduced sulfuric acid quality due to equipment corrosion, and improve production efficiency, which is of great significance to the sulfuric acid preparation industry; secondly, the present invention uses sulfuric acid dilution, cooling, and resin adsorption to return the desalted sulfuric acid to the sulfuric acid concentration system as spray water, which can also effectively reduce energy consumption and has important value in the fields of energy conservation, emission reduction, environmental protection, etc.; finally, the present invention can also avoid the increase in energy consumption caused by the direct return of dilute acid to the system, which has important economic and social benefits for industries that use a large amount of sulfuric acid, such as chemical, petroleum, metallurgy, electric power, and papermaking.

[0114] The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed structural features, that is, it does not mean that the present invention must rely on the above-mentioned detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A sulfuric acid concentration online desalination coupled energy saving device system, characterized in that: The device system comprises a sulfuric acid concentration device, a concentrated sulfuric acid storage device, a desalination unit and a gas phase sulfuric acid capture device which are connected in sequence; The sulfuric acid concentration device is provided with a dilute sulfuric acid liquid inlet pipeline; The sulfuric acid concentration device is bidirectionally connected to the gas phase sulfuric acid capture device; The desalination unit comprises a mixing device, a cooling device and a resin adsorption device connected in sequence; The outlet of the concentrated sulfuric acid storage device is connected to two pipelines, one pipeline is connected to the mixing device, and the other pipeline is connected to a downstream user of concentrated sulfuric acid; The resin adsorption device is connected to the gas phase sulfuric acid capture device; The top of the gas phase sulfuric acid capture device is connected to a condensing device; the outlet of the condensing device is connected to two pipelines, one pipeline is connected to the mixing device, and the other pipeline is discharged externally; The concentrated sulfuric acid discharged from the open circuit is 0.01-0.1% of the total amount of concentrated sulfuric acid in the concentrated sulfuric acid storage device.

2. The device system according to claim 1, characterized in that: The resin adsorption device is filled with ion exchange resin; The type of the ion exchange resin includes any one of LSC-957, XDA-1G or ZXC-9-S; The ion exchange resin is a resin that can adsorb metal acid salts but hardly adsorbs sulfuric acid.

3. A method for energy saving coupled with online desalination of sulfuric acid concentration, characterized in that: The method is carried out using the device system according to claim 1 or 2, and comprises the following steps: (1) Acidic water and concentrated sulfuric acid discharged from a concentrated sulfuric acid storage device are mixed in a mixing device, and then cooled in a cooling device and subjected to resin adsorption in a resin adsorption device to obtain deionized sulfuric acid; The concentrated sulfuric acid discharged from the open circuit is 0.01-0.1% of the total amount of concentrated sulfuric acid in the concentrated sulfuric acid storage device; The adsorption space velocity of the resin adsorption is 0.2-4BV / h; (2) The desalinated sulfuric acid obtained in step (1) is transported to a gas phase sulfuric acid capture device, and then reused in a sulfuric acid concentration device.

4. The method according to claim 3, characterized in that The mass concentration of the concentrated sulfuric acid in step (1) is 70-98%; The metal ions contained in the concentrated sulfuric acid in step (1) include Fe 3+ , Fe 2+ Cr 3+ 、Ni 2+ 、Mo 2+ , Mn 2+ Mg 2+ , Cu 2+ or Zn 2+ Any one or a combination of at least two of the following: The total amount of metal ions contained in the concentrated sulfuric acid in step (1) is 200-500 ppm.

5. The method according to claim 3, characterized in that: The acidic water in step (1) is acidic water condensed by a condensation device; The pH value of the acidic water in step (1) is 0.5-3; The acidic water in step (1) contains nitric acid and / or sulfuric acid; The mass ratio of the acidic water in step (1) to the concentrated sulfuric acid discharged from the open circuit is 1:(0.25-4).

6. The method according to claim 3, characterized in that After cooling in step (1), the temperature of the sulfuric acid is 20-80°C.

7. The method according to claim 3, characterized in that The total amount of metal ions contained in the desalted sulfuric acid in step (1) is less than 50 ppm.

8. The method according to claim 3, characterized in that The method comprises the following steps: (1) Acidic water with a pH value of 0.5-3 and concentrated sulfuric acid discharged from a concentrated sulfuric acid storage device are mixed in a mixing device at a mass ratio of 1:(0.25-4), cooled to a temperature of 20-80° C. by a cooling device, and then subjected to resin adsorption in a resin adsorption device at an adsorption space velocity of 0.2-4 BV / h to obtain desalted sulfuric acid containing a total amount of metal ions less than 50 ppm; The mass concentration of the concentrated sulfuric acid is 70-98%; the metal ions contained in the concentrated sulfuric acid include Fe 3+ , Fe 2+ Cr 3+ 、Ni 2+ 、Mo 2+ , Mn 2+ Mg 2+ , Cu 2+ or Zn 2+ Any one or a combination of at least two of the following; the total amount of metal ions contained in the concentrated sulfuric acid is 200-500ppm; the concentrated sulfuric acid discharged from the open circuit is 0.01-0.1% of the total amount of concentrated sulfuric acid in the concentrated sulfuric acid storage device; (2) The desalinated sulfuric acid obtained in step (1) is transported to a gas phase sulfuric acid capture device, and then reused in a sulfuric acid concentration device.

Images