Apparatus and method for separating hydrofluoric acid and sulfuric acid in mixed acid by forced circulation evaporation

Abstract

The application discloses a device for separating hydrofluoric acid and sulfuric acid in mixed acid by forced circulation evaporation, which comprises a liquid inlet pump, a preheater, a steam condensate storage tank, a one-effect evaporation system, a two-effect evaporation system, a single-effect evaporation system and a condenser. The one-effect evaporation system comprises a one-effect evaporator, a one-effect evaporation tank and a one-effect forced circulation pump. The two-effect evaporation system comprises a two-effect evaporator, a two-effect evaporation tank and a two-effect forced circulation pump. The single-effect evaporation system comprises a single-effect evaporator, a single-effect evaporation tank and a single-effect forced circulation pump. The condenser is connected with a vacuum jet pump through a pipeline, and the liquid outlet of the condenser is connected with the liquid inlet of a hydrofluoric acid storage tank through a material pipeline. The application further discloses a method for separating hydrofluoric acid and sulfuric acid in mixed acid by forced circulation evaporation. The two-effect and single-effect evaporation process of forced circulation is adopted, so that the steam consumption is reduced, the controllability of the system is improved, and the problems of easy crystallization of the evaporator and high equipment damage rate are solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of tail gas treatment of rare earth concentrate high-temperature roasting, and particularly relates to a device and method for forcibly circulating evaporation separation of hydrogen fluoride and sulfuric acid in mixed acid. BACKGROUND

[0002] The tail gas of rare earth concentrate high-temperature roasting with concentrated sulfuric acid contains a large amount of hydrogen fluoride, sulfur dioxide, silicon tetrafluoride and other gases. Direct discharge of the tail gas will pollute the environment and cause waste of resources. At present, the tail gas is discharged after being treated by spraying and desulfurization to reduce the content of sulfur and fluorine in the tail gas. The concentration of sulfuric acid in the waste water after spraying is about 28%, which is relatively low and contains a certain amount of hydrogen fluoride acid, that is, the mixed acid of sulfuric acid and hydrogen fluoride acid, which cannot be directly recycled to the roasting section of the rare earth concentrate. In order to meet the requirements of the roasting process of the rare earth concentrate on the concentration and purity of sulfuric acid, it is necessary to separate the sulfuric acid and hydrogen fluoride acid in the mixed acid, reduce the content of hydrogen fluoride acid in the sulfuric acid, and increase the concentration of sulfuric acid.

[0003] At present, the separation and treatment method of sulfuric acid and hydrogen fluoride acid adopts evaporation treatment process. One is the traditional single-effect evaporation process, which has the disadvantages of high energy consumption, easy crystallization in the internal evaporator and high equipment damage rate, because all the evaporators of each effect use saturated steam. The other is a three-effect evaporation process, which has the disadvantages of high evaporation temperature of the evaporator of the first effect to ensure that the secondary steam can be used twice, easy damage of the equipment due to high temperature of the automatic valve, pipeline and circulating pump, and the problem of easy crystallization in the internal evaporator. Moreover, the flow of the mixed acid is controlled by the opening degree of the delivery pump and the automatic valve to control the flow of the mixed acid into the next evaporator. Since the mixed acid contains sulfuric acid and hydrogen fluoride acid, the automatic valve has high requirements. The automatic valve is often damaged or not sensitive in the field, which leads to a large difference between the actual flow and the required flow into the next evaporator, causes the liquid level in the evaporation tank to be high or low, is difficult to control, and finally leads to low qualified rate of separated hydrogen fluoride acid and sulfuric acid. SUMMARY

[0004] In view of the disadvantages of the single-effect evaporation process and the three-effect evaporation process, the application provides a device and method for forcibly circulating evaporation separation of hydrogen fluoride acid and sulfuric acid in mixed acid, which adopts a forced circulation two-effect plus single-effect evaporation process, can reduce the consumption of steam, improve the controllability of the system, and solve the problems of easy crystallization of the evaporator and high equipment damage rate.

[0005] To achieve the above purpose, the technical solution used by the application is as follows:

[0006] The device for separating hydrofluoric acid and sulfuric acid in mixed acid by forced circulation evaporation includes: liquid inlet pump, preheater, steam condensate tank, one-effect evaporation system, two-effect evaporation system, single-effect evaporation system, condenser, the inlet of the liquid inlet pump is used for introducing mixed acid, the outlet is connected with the liquid inlet of the preheater through material pipeline, the liquid outlet of the preheater is connected with the liquid inlet of the one-effect forced circulation pump through material pipeline; the outlet of the steam condensate tank is connected with the circulation port of the preheater through circulation pipeline, the inlet of the steam condensate tank is connected with the condensate outlet of the one-effect evaporator and the single-effect evaporator through circulation pipeline; the one-effect evaporation system includes: one-effect evaporator, one-effect evaporation tank, one-effect forced circulation pump, the liquid outlet and the liquid inlet of the one-effect evaporator are connected with the liquid inlet of the one-effect evaporation tank and the liquid outlet of the one-effect forced circulation pump through material pipeline respectively, the steam inlet of the one-effect evaporator inputs saturated steam; the liquid outlet and the circulation port of the one-effect evaporation tank are connected with the liquid inlet of the two-effect forced circulation pump and the liquid inlet of the one-effect forced circulation pump through material pipeline respectively, the gas phase outlet of the one-effect evaporation tank is connected with the gas phase inlet of the two-effect evaporator through material pipeline; the two-effect evaporation system includes: two-effect evaporator, two-effect evaporation tank, two-effect forced circulation pump, the liquid outlet and the liquid inlet of the two-effect evaporator are connected with the liquid inlet of the two-effect evaporation tank and the liquid outlet of the two-effect forced circulation pump through material pipeline respectively; the liquid outlet and the circulation port of the two-effect evaporation tank are connected with the liquid inlet of the single-effect forced circulation pump and the liquid inlet of the two-effect forced circulation pump through material pipeline respectively, the gas phase outlet of the two-effect evaporation tank is connected with the gas phase inlet of the condenser through material pipeline; the single-effect evaporation system includes: single-effect evaporator, single-effect evaporation tank, single-effect forced circulation pump, the liquid outlet and the liquid inlet of the single-effect evaporator are connected with the liquid inlet of the single-effect evaporation tank and the liquid outlet of the single-effect forced circulation pump through material pipeline respectively, the steam inlet of the single-effect evaporator inputs saturated steam; the liquid outlet of the single-effect evaporation tank is connected with the liquid inlet of the sulfuric acid tank through material pipeline, the circulation port is connected with the liquid inlet of the single-effect forced circulation pump through material pipeline, and the gas phase outlet is connected with the gas phase inlet of the condenser through material pipeline; the condenser is connected with the vacuum jet pump through pipeline, and the liquid outlet of the condenser is connected with the liquid inlet of the hydrofluoric acid tank through material pipeline.

[0007] Further, the preheater includes: first preheater, second preheater, the outlet of the liquid inlet pump is connected with the inlet of the filter through material pipeline, the outlet of the filter is connected with the liquid inlet of the first preheater through material pipeline, the liquid outlet of the first preheater is connected with the liquid inlet of the second preheater through material pipeline, the liquid outlet of the second preheater is connected with the liquid inlet of the one-effect forced circulation pump through material pipeline, and the circulation ports of the second preheater and the first preheater are connected with the steam condensate tank through circulation pipeline.

[0008] Further, the liquid outlet of the single-effect evaporation tank is connected with the liquid inlet of the sulfuric acid heat exchanger through material pipeline, the liquid outlet of the sulfuric acid heat exchanger is connected with the liquid inlet of the sulfuric acid tank through material pipeline, and the circulation water inlet and the circulation water outlet of the sulfuric acid heat exchanger are used for connecting circulating feed water and circulating return water.

[0009] Further, the liquid outlet of the condenser is connected to the liquid return port of the two-effect evaporator, the liquid inlet of the hydrofluoric acid heat exchanger through the material pipeline, and the liquid outlet of the hydrofluoric acid heat exchanger is connected to the liquid inlet of the hydrofluoric acid storage tank through the material pipeline; the circulating water inlet and outlet of the hydrofluoric acid heat exchanger are used to connect the circulating feed water and circulating return water.

[0010] The method for separating hydrofluoric acid and sulfuric acid in mixed acid by forced circulation evaporation includes:

[0011] The mixed acid is pumped into the filter through the liquid inlet pump, filtered through the filter, and then preheated in the first preheater and the second preheater in sequence, and the temperature of the mixed acid after two preheats is 80-90℃.

[0012] The preheated mixed acid is sent to the one-effect evaporation system for separation of hydrofluoric acid and sulfuric acid, and the heat source of the one-effect evaporation system is saturated steam; the mixed acid after the first separation is sent to the two-effect evaporation system for the second separation of hydrofluoric acid and sulfuric acid, and the heat source of the two-effect evaporation system is the hydrofluoric acid steam of the one-effect evaporation system.

[0013] The mixed acid after the second separation is sent to the single-effect evaporation system for the third separation of hydrofluoric acid and sulfuric acid, and the heat source is saturated steam, and the separated sulfuric acid is injected into the sulfuric acid storage tank, and the separated hydrofluoric acid is injected into the hydrofluoric acid storage tank.

[0014] Preferably, the separated sulfuric acid is cooled in the sulfuric acid heat exchanger before being injected into the sulfuric acid storage tank, and the separated hydrofluoric acid is cooled in the hydrofluoric acid heat exchanger before being injected into the hydrofluoric acid storage tank.

[0015] Preferably, the mixed acid is preheated for the first time in the first preheater, and then preheated for the second time in the second preheater; the heat sources for the two preheats of the mixed acid come from the one-effect evaporator and the single-effect evaporator, respectively.

[0016] Preferably, the preheated mixed acid flows to the liquid inlet of the one-effect forced circulation pump, is heated in the one-effect evaporator under the push of the one-effect forced circulation pump, and is separated by evaporation in the one-effect evaporation tank, the gas phase temperature in the one-effect evaporation tank is 100-110℃, the liquid phase temperature is 85-95℃, and the evaporation tank liquid level is 1000-1100mm.

[0017] Preferably, the mixed acid after the first separation flows to the liquid inlet of the two-effect forced circulation pump, is heated and mixed in the two-effect evaporator, and is separated by evaporation in the two-effect evaporation tank, the gas phase temperature in the two-effect evaporation tank is 80-85℃, the liquid phase temperature is 85-90℃, and the evaporation tank liquid level is 1100-1200mm.

[0018] The preferred single-effect evaporating tank gas phase temperature is 100-105 DEG C, the liquid phase temperature is 110-115 DEG C, and the evaporating tank liquid level is 1000-1100 mm.

[0019] The technical effects of the present application include:

[0020] 1. The present application adopts forced circulation two-effect plus single-effect evaporation process, which is more suitable for separating hydrogen fluoride and sulfuric acid in mixed acid.

[0021] In view of the shortcomings of the current single-effect evaporation and three-effect evaporation process, the two-effect plus single-effect evaporation process is adopted, hydrogen fluoride vapor is reused, energy consumption is reduced, and the amount of saturated steam is reduced.

[0022] In the current three-effect evaporation process, the secondary steam is used twice, and the temperature difference loss is large. In order to make up for the problem of large temperature difference loss, the evaporation temperature of one of the effects in the three-effect evaporation process must be high. High temperature reduces the service life of the circulating pump, pipeline and valve in the system, and brings more unstable factors to the operation of the system. In the present application, hydrogen fluoride vapor is only used once, which can effectively avoid a series of problems caused by the use of secondary steam twice in the three-effect evaporation process.

[0023] Therefore, the two-effect plus single-effect evaporation process of the present application is more suitable for separating hydrogen fluoride and sulfuric acid in mixed acid.

[0024] 2. The evaporator structure of the one-effect evaporator, two-effect evaporator and single-effect evaporator adopts a forced circulation evaporator (a forced circulation pump is provided for the climbing film evaporator). The flow of the mixed acid in each evaporator is from the bottom to the top of the evaporator, and the flow speed of the mixed acid in the evaporator is accelerated by the forced circulation pump, which greatly reduces the crystallization of the inner wall of the evaporator and prolongs the service life of the evaporator.

[0025] 3. The flow mode of the mixed acid is overflow between each evaporator.

[0026] In the current evaporation process, the mixed acid flows into the circulating pump from the bottom outlet of the evaporating tank, part of the outlet of the circulating pump returns to the evaporator for further heating and evaporation, and the other part goes to the next evaporating tank. The flow into the next evaporating tank is controlled by controlling the opening of the automatic valve in the pipeline. Since the mixed acid contains both sulfuric acid and hydrogen fluoride acid, the automatic valve has high requirements. The automatic valve on site is often damaged or not sensitive to control, resulting in inaccurate flow and poor controllability.

[0027] In the present application, the flow of mixed acid between each evaporator is overflowed from the side of the evaporation tank to the inlet of the forced circulation pump of the next effect, by controlling the liquid level of the evaporation tank, the liquid can be uniformly flowed to the pipeline inlet of the forced circulation pump of the next effect without any valve in between, reducing the control points, saving investment, and improving the operability of the system.

[0028] 4. The energy utilization rate can be improved.

[0029] In the process of the present application, the heat source of the single-effect evaporator and the single-effect evaporator is saturated steam, and the heat value of the liquid and gas in the steam condensate water is relatively high. The steam condensate water is collected, the liquid and gas are preheated mixed acid respectively, the initial temperature of the mixed acid is improved, the heat is reused, and the energy consumption is reduced.

[0030] 5. In the present application, the forced circulation process is adopted, so that the crystalline material in the evaporator is greatly reduced, and the service life of the evaporator is prolonged.

[0031] In the current evaporation process, the crystalline material continuously accumulates in the evaporator, so that the evaporator is used for at most 5 months, and the cost of replacing the evaporator every year is: 0.75 million yuan x 4 units x 2.4 = 7.2 million yuan.

[0032] In the present application, the forced circulation pump is introduced to speed up the flow speed of waste acid in the evaporator, and the service life of the evaporator is doubled, which is replaced once a year, and the cost of replacing the evaporator every year is: 1 million yuan x 3 units x 1 = 3 million yuan. Therefore, the annual cost of the evaporator is saved: 7.2 million yuan-3 million yuan = 4.2 million yuan. On the other hand, in the two-effect and single-effect production process, the temperature of the system is low, and the consumption of steam is reduced.

[0033] Compared with the current evaporation process, in the case of the same treatment capacity, the present application saves one fourth of the steam compared with the current evaporation process, saves 1.5 t / h of steam per hour on average, saves 1.5 t / h x 24 h x 300 days x 265 yuan / t = 28.62 million yuan per year, and reduces the production cost by 4.2 million yuan + 28.62 million yuan = 706.2 million yuan per year. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is a structural principle diagram of the device for separating hydrofluoric acid and sulfuric acid in mixed acid by forced circulation evaporation in the present application. DETAILED DESCRIPTION

[0035] The following description fully illustrates specific embodiments of the present application to enable those skilled in the art to practice and reproduce the same.

[0036] As shown in Figure 1 It is a structural principle diagram of the device for separating hydrofluoric acid and sulfuric acid in mixed acid by forced circulation evaporation in the present application.

[0037] The device for separating hydrofluoric acid and sulfuric acid in mixed acid by forced circulation evaporation includes a liquid inlet pump P01, a first preheater E01, a second preheater E02, a steam condensate storage tank V06, a single-effect evaporation system, a double-effect evaporation system, and a single-effect evaporation system.

[0038] The method for separating hydrofluoric acid and sulfuric acid in mixed acid by forced circulation evaporation includes the following steps:

[0039] Step 1: The mixed acid is sent to a filter F01ab through a liquid inlet pump P01, filtered by the filter F01ab, and then preheated by a first preheater E01 and a second preheater E02 in sequence. The temperature of the mixed acid after the two preheating processes is 80-90℃.

[0040] The inlet of the liquid inlet pump P01 is connected to the mixed acid pipeline through a material pipeline, and the outlet is connected to the inlet of the filter F01ab through a material pipeline. The outlet of the filter F01ab is connected to the liquid inlet of the first preheater E01 through a material pipeline, the liquid outlet of the first preheater E01 is connected to the liquid inlet of the second preheater E02 through a material pipeline, and the liquid outlet of the second preheater E02 is connected to the liquid inlet of the single-effect forced circulation pump P03 through a material pipeline. The steam condensate storage tank V06 is connected to the second preheater E02 and the first preheater E01 through a circulation pipeline in sequence, and the second preheater E02 is located above the first preheater E01. The inlet of the steam condensate storage tank V06 is connected to the condensate outlets of the single-effect evaporator F03 and the single-effect evaporator F03 through a circulation pipeline.

[0041] The mixed acid is preheated for the first time in the first preheater E01, and then preheated for the second time in the second preheater E02. The heat sources for the two preheating processes come from the single-effect evaporator F01 of the single-effect evaporation system and the single-effect evaporator F03 of the single-effect evaporation system, respectively.

[0042] Step 2: The preheated mixed acid is sent to the single-effect evaporation system for separation of hydrofluoric acid and sulfuric acid. The heat source for the single-effect evaporation system is saturated steam. The mixed acid after the first separation is sent to the double-effect evaporation system for the second separation of hydrofluoric acid and sulfuric acid. The heat source for the double-effect evaporation system is the hydrofluoric acid steam from the single-effect evaporation system.

[0043] The first evaporation system comprises a first evaporator F01, a first evaporation tank V01, a first forced circulation pump P03, the liquid outlet of the first evaporator F01 is connected to the liquid inlet of the first evaporation tank V01 through a material pipeline, and the liquid inlet is connected to the liquid outlet of the first forced circulation pump P03 through a material pipeline; the steam inlet of the first evaporator F01 inputs saturated steam, and the condensate outlet of the first evaporator F01 is connected to the inlet of a steam condensate storage tank V06 through a circulation pipeline; the liquid outlet of the first evaporation tank V01 is connected to the liquid inlet of a second forced circulation pump P04 through a material pipeline, the circulation port is connected to the liquid inlet of the first forced circulation pump P03 through a material pipeline, and the gas phase outlet is connected to the gas phase inlet of a second evaporator F02 through a material pipeline. The preheated mixed acid flows to the liquid inlet of the first forced circulation pump P03, is heated in the first evaporator F01 under the pushing of the first forced circulation pump P03, is evaporated and separated in the first evaporation tank V01, and the heat source of the first evaporation system is saturated steam. The gas phase temperature in the first evaporation tank V01 is 100-110 DEG C, the liquid phase temperature is 85-95 DEG C, and the evaporation tank liquid level is 1000-1100 mm.

[0044] The mixed acid is heated to a boiling state in the first evaporator F01, the boiling state mixed acid enters the first evaporation tank V01, and separation of hydrofluoric acid and sulfuric acid is realized in the first evaporation tank V01. Since the boiling point of hydrofluoric acid is low and the boiling point of sulfuric acid is high, hydrofluoric acid is first gasified and exists in the gas phase, the gas is condensed into hydrofluoric acid liquid, and the liquid phase is the remaining sulfuric acid. The mixed acid in the second evaporation system and the single-effect evaporation system is the same.

[0045] The second evaporation system comprises a second evaporator F02, a second evaporation tank V02, a second forced circulation pump P04, the liquid outlet of the second evaporator F02 is connected to the liquid inlet of the second evaporation tank V02 through a material pipeline, the liquid inlet of the second evaporator F02 is connected to the liquid outlet of the second forced circulation pump P04 through a material pipeline, the gas phase inlet of the second evaporator F02 is connected to the gas phase outlet of the first evaporation tank V01 through a material pipeline, and the liquid return port of the second evaporator F02 is connected to the liquid outlet of a condenser F05 through a material pipeline; the liquid outlet of the second evaporation tank V02 is connected to the liquid inlet of a single-effect forced circulation pump P05 through a material pipeline, the circulation port is connected to the liquid inlet of the second forced circulation pump P04 through a material pipeline, and the gas phase outlet is connected to the gas phase inlet of the condenser F05 through a material pipeline. The mixed acid separated for the first time flows to the liquid inlet of the second forced circulation pump P04, is heated and mixed in the second evaporator F02, is evaporated and separated in the second evaporation tank V02, and the heat source is the hydrofluoric acid steam of the first evaporation system. The gas phase temperature in the second evaporation tank V02 is 80-85 DEG C, the liquid phase temperature is 85-90 DEG C, and the evaporation tank liquid level is 1100-1200 mm.

[0046] Step 3: The mixed acid after the second separation is sent to a single-effect evaporation system for the third separation of hydrofluoric acid and sulfuric acid. The heat source is saturated steam. The separated sulfuric acid is cooled in the sulfuric acid heat exchanger F04 and then injected into the sulfuric acid storage tank V04. The separated hydrofluoric acid is cooled in the hydrofluoric acid heat exchanger F06 and then injected into the hydrofluoric acid storage tank V05.

[0047] The single-effect evaporation system includes a single-effect evaporator F03, a single-effect evaporation tank V03, and a single-effect forced circulation pump P05. The liquid outlet of the single-effect evaporator F03 is connected to the liquid inlet of the single-effect evaporation tank V03 through a material pipeline. The liquid inlet of the single-effect evaporator F03 is connected to the liquid outlet of the single-effect forced circulation pump P05 through a material pipeline. The steam inlet of the single-effect evaporator F03 is connected to the saturated steam. The condensate outlet is connected to the inlet of the steam condensate storage tank V06 through a circulation pipeline. The liquid outlet of the single-effect evaporation tank V03 is connected to the liquid inlet of the sulfuric acid heat exchanger F04 through a material pipeline. The circulation port is connected to the liquid inlet of the single-effect forced circulation pump P05 through a material pipeline. The gas phase outlet is connected to the gas phase inlet of the condenser F05 through a material pipeline. The liquid outlet of the sulfuric acid heat exchanger F04 is connected to the liquid inlet of the sulfuric acid storage tank V04 through a material pipeline. The circulating water inlet and outlet of the sulfuric acid heat exchanger F04 are connected to the circulating feed water and circulating return water, respectively.

[0048] The vacuum system uses a combination of a condenser F05 and a vacuum jet pump to maintain negative pressure in the system. The liquid outlet of the condenser F05 is connected to the return liquid port of the double-effect evaporator F02 (further separation of hydrofluoric acid, sulfuric acid, and recovery of heat from the hydrofluoric acid vapor carried out by the single-effect evaporation system) and the liquid inlet of the hydrofluoric acid heat exchanger F06 through a material pipeline. The liquid outlet of the hydrofluoric acid heat exchanger F06 is connected to the liquid inlet of the hydrofluoric acid storage tank V05 through a material pipeline. The circulating water inlet and outlet of the hydrofluoric acid heat exchanger F06 are connected to the circulating feed water and circulating return water, respectively. The separated hydrofluoric acid is cooled in the hydrofluoric acid heat exchanger F06 and then injected into the hydrofluoric acid storage tank V05.

[0049] The mixed acid after the second separation flows to the liquid inlet of the single-effect forced circulation pump P04, is heated in the single-effect evaporator F03, and is evaporated in the single-effect evaporation tank V03. The heat source is saturated steam. The separated sulfuric acid is cooled in the sulfuric acid heat exchanger F04 and then injected into the sulfuric acid storage tank V04.

[0050] The gas phase temperature in the single-effect evaporation tank V03 is 100-105°C, the liquid phase temperature is 110-115°C, and the evaporation tank liquid level is 1000-1100mm.

[0051] The terms used in the present application are illustrative and exemplary, rather than limiting terms. Since the present application can be implemented in various forms without departing from the spirit or essential characteristic thereof, it should also be understood that the above-described embodiments are not limited by any of the foregoing disclosure, but are widely interpreted, falling within the spirit and scope of the appended claims, whereby all changes and modifications thereto belong to the scope of the following claims.

Claims

1. A device for separating hydrofluoric acid and sulfuric acid in a mixed acid by forced circulation evaporation, characterized by, The application relates to a sulfuric acid production system, which comprises an inlet pump, a preheater, a steam condensate tank, a one-effect evaporation system, a two-effect evaporation system, a single-effect evaporation system and a condenser, wherein the inlet of the inlet pump is used for introducing mixed acid, the outlet of the inlet pump is connected with the inlet of the preheater through a material pipeline, the outlet of the preheater is connected with the inlet of a one-effect forced circulation pump through a material pipeline, the outlet of the steam condensate tank is connected with the circulation port of the preheater through a circulation pipeline, and the inlet of the steam condensate tank is connected with the condensate outlets of the one-effect evaporator and the single-effect evaporator through circulation pipelines; the one-effect evaporation system comprises a one-effect evaporator, a one-effect evaporation tank and a one-effect forced circulation pump, the liquid outlet and the liquid inlet of the one-effect evaporator are connected with the liquid inlet of the one-effect evaporation tank and the liquid outlet of the one-effect forced circulation pump through material pipelines respectively, and the steam inlet of the one-effect evaporator is used for inputting saturated steam; the liquid outlet and the circulation port of the one-effect evaporation tank are connected with the liquid inlet of the two-effect forced circulation pump and the liquid inlet of the one-effect forced circulation pump through material pipelines respectively, and the gas phase outlet of the one-effect evaporation tank is connected with the gas phase inlet of the two-effect evaporator through a material pipeline; the two-effect evaporation system comprises a two-effect evaporator, a two-effect evaporation tank and a two-effect forced circulation pump, the liquid outlet and the liquid inlet of the two-effect evaporator are connected with the liquid inlet of the two-effect evaporation tank and the liquid outlet of the two-effect forced circulation pump through material pipelines respectively; the liquid outlet and the circulation port of the two-effect evaporation tank are connected with the liquid inlet of the single-effect forced circulation pump and the liquid inlet of the two-effect forced circulation pump through material pipelines respectively, and the gas phase outlet of the two-effect evaporation tank is connected with the gas phase inlet of the condenser through a material pipeline; the single-effect evaporation system comprises a single-effect evaporator, a single-effect evaporation tank and a single-effect forced circulation pump, the liquid outlet and the liquid inlet of the single-effect evaporator are connected with the liquid inlet of the single-effect evaporation tank and the liquid outlet of the single-effect forced circulation pump through material pipelines respectively, the steam inlet of the single-effect evaporator is used for inputting saturated steam, the liquid outlet of the single-effect evaporation tank is connected with the liquid inlet of a sulfuric acid tank through a material pipeline, the circulation port of the single-effect evaporation tank is connected with the liquid inlet of the single-effect forced circulation pump through a material pipeline, and the gas phase outlet of the single-effect evaporation tank is connected with the gas phase inlet of the condenser through a material pipeline; and the condenser is connected with a vacuum jet pump through a pipeline, and the liquid outlet of the condenser is connected with the liquid inlet of a hydrofluoric acid tank through a material pipeline. The preheater comprises a first preheater and a second preheater, the outlet of the inlet pump is connected with the inlet of a filter through a material pipeline, the outlet of the filter is connected with the liquid inlet of the first preheater through a material pipeline, the liquid outlet of the first preheater is connected with the liquid inlet of the second preheater through a material pipeline, the liquid outlet of the second preheater is connected with the liquid inlet of the one-effect forced circulation pump through a material pipeline, and the circulation ports of the second preheater and the first preheater are connected with the steam condensate tank through circulation pipelines.

2. The apparatus for separating hydrofluoric acid and sulfuric acid from a mixed acid by forced circulation evaporation as claimed in claim 1, wherein The liquid outlet of the single-effect evaporation tank is connected with the liquid inlet of a sulfuric acid heat exchanger through a material pipeline, the liquid outlet of the sulfuric acid heat exchanger is connected with the liquid inlet of a sulfuric acid tank through a material pipeline, and the circulation water inlet and the circulation water outlet of the sulfuric acid heat exchanger are used for connecting circulating feed water and circulating return water.

3. The apparatus for separating hydrofluoric acid and sulfuric acid from a mixed acid by forced circulation evaporation as claimed in claim 1, wherein ​ 4. The apparatus for separating hydrofluoric acid and sulfuric acid from a mixed acid by forced circulation evaporation as claimed in claim 1, wherein The liquid outlet of the condenser is connected with the liquid return port of the two-effect evaporator, the liquid inlet of the hydrofluoric acid heat exchanger through the material pipeline, and the liquid inlet of the hydrofluoric acid storage tank through the material pipeline connected with the liquid outlet of the hydrofluoric acid heat exchanger; the circulating water inlet and outlet of the hydrofluoric acid heat exchanger are used for connecting the circulating feed water and circulating return water.

5. A method for the forced circulation evaporation separation of hydrofluoric acid and sulfuric acid from a mixed acid using the apparatus according to any one of claims 1 to 4, characterized in that, Comprise: The mixed acid is pumped into the filter through the liquid inlet pump, filtered through the filter, and then preheated in the first preheater and the second preheater in turn, and the temperature of the mixed acid after two preheats is 80-90℃; The preheated mixed acid is sent to the one-effect evaporation system for separation of hydrofluoric acid and sulfuric acid, and the heat source of the one-effect evaporation system is saturated steam; the mixed acid after the first separation is sent to the two-effect evaporation system for the second separation of hydrofluoric acid and sulfuric acid, and the heat source of the two-effect evaporation system is the hydrofluoric acid steam of the one-effect evaporation system; The mixed acid after the second separation is sent to the single-effect evaporation system for the third separation of hydrofluoric acid and sulfuric acid, and the heat source is saturated steam, and the separated sulfuric acid is injected into the sulfuric acid storage tank, and the separated hydrofluoric acid is injected into the hydrofluoric acid storage tank.

6. The method of claim 5 wherein the forced circulation evaporation separates the hydrofluoric acid and the sulfuric acid in the mixed acid. The separated sulfuric acid is cooled in the sulfuric acid heat exchanger and then injected into the sulfuric acid storage tank, and the separated hydrofluoric acid is cooled in the hydrofluoric acid heat exchanger and then injected into the hydrofluoric acid storage tank.

7. The method of claim 5 wherein the forced circulation evaporation separates the hydrofluoric acid and the sulfuric acid in the mixed acid. The mixed acid is preheated in the first preheater for the first time, and then sent to the second preheater for the second time; the heat sources for the two preheats of the mixed acid come from the one-effect evaporator and the single-effect evaporator respectively.

8. The method of claim 5 wherein the forced circulation evaporation separates the hydrofluoric acid and the sulfuric acid in the mixed acid. The preheated mixed acid flows to the liquid inlet of the one-effect forced circulation pump, is heated in the one-effect evaporator under the push of the one-effect forced circulation pump, and is separated by evaporation in the one-effect evaporation tank, the gas phase temperature in the one-effect evaporation tank is 100-110℃, the liquid phase temperature is 85-95℃, and the evaporation tank liquid level is 1000-1100mm.

9. The method of claim 5 wherein the forced circulation evaporation separates the hydrofluoric acid and the sulfuric acid in the mixed acid. The mixed acid after the first separation flows to the liquid inlet of the two-effect forced circulation pump, is heated in the two-effect evaporator, and is separated by evaporation in the two-effect evaporation tank, the gas phase temperature in the two-effect evaporation tank is 80-85℃, the liquid phase temperature is 85-90℃, and the evaporation tank liquid level is 1100-1200mm.

10. The method of claim 5 wherein the forced circulation evaporation separates the hydrofluoric acid and the sulfuric acid in the mixed acid. The gas phase temperature in the single-effect evaporation tank is 100-105℃, the liquid phase temperature is 110-115℃, and the evaporation tank liquid level is 1000-1100mm.

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