Condensation and purification system and method for steam generated in concentration and evaporation process and application

Abstract

The invention relates to the technical field of fine chemical engineering, and discloses a condensation and purification system and method for steam generated in the concentration and evaporation process and application, the system comprises a concentration and evaporation device, and a bottom discharge port of the concentration and evaporation device passes through a pipeline, a concentration circulating pump and a steam heater and then returns to the concentration and evaporation device; the top of the concentration and evaporation device is provided with a gas phase outlet descaling device and then connected to the lower portion of the rectification device, a gas phase outlet in the top of the rectification device passes through a condenser and then is connected to the gas-liquid separation device, the bottom of the gas-liquid separation device is connected to a return port in the upper portion of the rectification device through a reflux pump, and the lower portion of the gas-liquid separation device is connected with a purified liquid outlet pipe. And a gas-phase discharge pipe is arranged at the upper part. By adopting the system and the method, the steam generated in the concentration and evaporation process can be effectively treated, the purified condensate is obtained, the cost is lower, and the economic benefit is high.

Description

Technical Field

[0001] The present invention belongs to the technical field of fine chemicals, and in particular relates to a condensation and purification system, method and application of steam generated during a concentration and evaporation process. Background Art

[0002] In traditional concentration and evaporation processes, evaporated water vapor is condensed by circulating water to form condensate. This condensate contains a large amount of impurities, making direct discharge and recycling unsuitable for environmental and process requirements. Purifying this condensate using a distillation unit requires reheating, which consumes significant energy. Purifying this condensate using other methods also incurs additional costs and may introduce new impurities, resulting in lower condensate recovery rates.

[0003] When the concentrated feedstock is an inorganic salt, especially at a high concentration, solid crystals form during the concentration process to remove low-boiling-point materials such as water. Materials containing solid crystals cannot be processed using traditional distillation equipment. For example, when the concentrated feedstock is an acidic composite liquid, directly distilling the acidic liquid to separate low-boiling-point materials such as water requires a larger distillation unit and requires high acid resistance, significantly increasing the cost of the equipment. Summary of the Invention

[0004] The present invention provides a condensation purification system, method and application for steam generated during the concentration and evaporation process, which can effectively treat the steam generated during the concentration and evaporation process to obtain purified condensate with low cost and high economic benefit.

[0005] The technical solution of the present invention is to provide a condensation and purification system for steam generated during a concentration and evaporation process, comprising a concentration and evaporation device, wherein a bottom discharge port thereof returns to the concentration and evaporation device through a pipeline, a concentration circulation pump, and a steam heater; a gas phase outlet descaling device is provided at the top of the concentration and evaporation device and is connected to the lower part of a distillation device; a gas phase outlet at the top of the distillation device is connected to a gas-liquid separation device after passing through a condenser; the bottom of the gas-liquid separation device is connected to a return port at the upper part of the distillation device through a reflux pump; the lower part of the gas-liquid separation device is connected to a purified liquid outlet pipe, and a gas phase discharge pipe is provided at the top.

[0006] Optionally, the system includes multiple groups of distillation devices, heat exchangers, gas-liquid separation devices and reflux pumps, the gas phase pipeline of each group of distillation devices is connected to the upper reflux port of the distillation device through the heat exchanger, gas-liquid separation device and reflux pump, and the gas phase discharge pipe of the previous group of gas-liquid separation devices is connected to the lower air inlet of the next group of distillation devices.

[0007] Optionally, the steam heater is connected to a fresh steam pipeline; an inlet for the material to be concentrated is provided on the pipeline between the concentration evaporation device and the concentration circulation pump, and a concentrated product discharge port is also provided at the bottom of the concentration evaporation device.

[0008] Optionally, the descaling device is a cyclone demister or a washing tower.

[0009] Optionally, the bottom of the distillation device is provided with a residual liquid accommodating space, which is connected to a residual liquid output pump and a pipeline; the middle section or the lower section of the distillation device is provided with a foreign material feeding port.

[0010] Optionally, a post-processing device is further connected to the gas phase discharge pipe of the gas-liquid separation device; such as an optional vacuum condensation system, a tail washing system, an organic matter recovery system, etc.

[0011] The present invention also relates to a method for condensing and purifying steam generated during a concentration and evaporation process, comprising the following steps: S1, the material to be concentrated enters the concentration evaporation device for evaporation and concentration, and the concentrated product is drawn out; S2. The gas phase generated during the production process of the concentration and evaporation device is drawn out from the top and enters the distillation device, where it is purified both as a raw material to be purified and as a heat source. The temperature and reflux ratio in the distillation device are controlled at a certain level according to the boiling point of the impurities to be removed. The gas phase entering the distillation device contacts the reflux material in a reverse direction. Finally, the gas phase at the top is condensed into a liquid phase through heat exchange, part of which is refluxed into the distillation device, and part is withdrawn as a purified liquid, or enters a subsequent distillation device for purification and then drawn out.

[0012] Optionally, the steam evaporated by the concentration evaporation device contains water; and further contains one or more of phosphate ions, fluoride ions, chloride ions, ammonium ions, ammonia water and organic matter.

[0013] The present invention also relates to the application of the above system or method in material concentration.

[0014] Alternatively, the material to be concentrated may be a material introduced into the evaporation process due to foaming, or may contain volatile and easily evaporable components. Such materials may include highly concentrated aqueous acid solutions (containing organic matter) and highly concentrated aqueous inorganic salt solutions (containing ammonia and acid). Examples include monoammonium phosphate solutions, acidic solutions containing volatile acidic vapors of hydrogen chloride and fluoride, and the like.

[0015] The present invention has the following beneficial effects: The present invention sets a semi-distillation device directly after the concentration evaporation device, and directly distills the steam produced by the concentration evaporation. The steam serves as both a raw material and a heat source, avoiding the need to introduce a large amount of external heat for distillation after condensing it, thereby greatly reducing the cost of purifying the material.

[0016] The condensate obtained by the traditional concentration, evaporation and condensation device has a high impurity content and cannot be used directly. The purified condensate obtained by the present invention can be used directly. At the same time, the output of purified condensate can be increased by introducing foreign similar materials to replace part of the reflux liquid in the distillation reflux stage.

[0017] The distillation device of the present invention concentrates the residual liquid. After the residual liquid reaches a certain concentration, it can be recycled and reused as a raw material in other production processes, or the residual liquid can be drawn out and further processed by other devices. Compared with the traditional direct treatment of condensate, its processing volume is greatly reduced, and the processing cost can also be reduced.

[0018] The device and method provided by the present invention are applicable to various material concentration scenarios. They can also realize the separation and purification recovery of low-boiling-point materials and high-boiling-point materials in the concentrated steam by connecting multiple sets of distillation devices in series. The concentration can be carried out under normal pressure, positive pressure or negative pressure conditions, which facilitates their recycling.

[0019] This device can implement a production unit for material concentration and a production unit for gas-phase steam separation and purification, solving the difficulties and pain points of the distillation device. At the same time, the device can operate normally and stably because the amount of water vapor of multiple components in the previous production unit is always basically consistent, and the feed amount of the distillation device is consistent. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention provides a structural block diagram of the device.

[0021] Figure 2 The present invention provides a partial structural schematic diagram of the device, in which 1 is a first-effect flash chamber, 2 is a first-effect circulating pump, 3 is a first-effect heater, 4 is a condensate tank, 5 is a demister, 6 is a first-effect washing tower, 7 is a washing circulating pump, 8 is a first-effect steam condensing tower, 9 is a filter, 10 is a heat exchange circulating pump, 11 is a heat exchanger, 12 is a reboiler, and 13 is a compressor. DETAILED DESCRIPTION

[0022] The experimental methods in the following examples are conventional methods unless otherwise specified. The materials used in the following examples are commercially available products unless otherwise specified.

[0023] Example 1 A condensation and purification system for steam generated during the evaporation process, such as Figure 1As shown, it includes a concentration and evaporation device 1, the bottom discharge port of which returns to the concentration and evaporation device 1 through a pipeline and a concentration circulation pump 2 and a steam heater 3. The top of the concentration and evaporation device 1 is provided with a gas phase outlet descaling device 4 and is connected to the lower part of the distillation device 5. The gas phase outlet at the top of the distillation device is connected to the gas-liquid separation device 7 after passing through a condenser 6. The bottom of the gas-liquid separation device is connected to the return port of the upper part of the distillation device through a reflux pump 8. The lower part of the gas-liquid separation device is connected to the purified liquid lead-out pipe 9, and the upper part is provided with a gas phase discharge pipe 10.

[0024] In some embodiments, the steam heater 3 is connected to the fresh steam pipe 11; the pipe between the concentration evaporation device and the concentration circulation pump is also connected to the feed pipe 12 of the material to be concentrated, and the lower part of the concentration evaporation device is also provided with a concentrated product discharge pipe 13.

[0025] In some embodiments, the descaling device 4 is a cyclone demister, a washing tower, or a settling chamber. In Example 1, a cyclone demister is used. If solid impurities are present, a washing tower or a settling chamber can be selected as the descaling device to ensure that the material entering the distillation column does not contain solids.

[0026] In some embodiments, the bottom of the distillation device is provided with a residual liquid accommodating space, which is connected to the residual liquid output pump 14 and the pipeline; the middle section or the lower section of the distillation device is provided with a foreign material feeding port.

[0027] In some embodiments, the gas phase discharge pipe of the gas-liquid separation device 7 is further connected to a post-processing device, such as a vacuum condensation system, a tail washing system, an organic matter recovery system, etc.

[0028] Example 2 A condensation and purification system for steam generated during the evaporation process, such as Figure 2 As shown, the main structure is the same as that of Example 1, except that it includes two groups of distillation devices, heat exchangers, gas-liquid separation devices and reflux pumps. The gas phase pipeline of each group of distillation devices is connected to the upper reflux port of the distillation device through the heat exchanger, gas-liquid separation device and reflux pump, and the gas phase discharge pipe of the previous group of gas-liquid separation devices is connected to the lower air inlet of the next group of distillation devices.

[0029] The number of distillation units can be adjusted as needed. Using multiple groups of distillation units in conjunction with post-processing units is suitable for concentrating materials with complex components and can achieve separate purification and recovery.

[0030] For example, in the process of concentrating phosphoric acid containing organic matter, the first-stage distillation device removes phosphoric acid, fluorine, chlorine and most of the water in the original acid steam, and the second-stage distillation device distills and separates a small amount of water and organic matter.

[0031] Example 3 The system of Example 1 is used to concentrate the monoammonium phosphate solution, which includes the following steps: (The following data are data of continuous stable operation state) Step (1): The concentration of monoammonium phosphate slurry is 32%, and the material feed rate is 75.2t / h. It is indirectly heated and concentrated by steam at 0.05MPa. After the steam produced by evaporation is defoamed, the mixed steam containing a small amount of monoammonium phosphate material and a large amount of water vapor enters the distillation device. The ammonia nitrogen content in the steam is 500g, the steam volume is 10t / h, the steam temperature is 81℃, the steam absolute pressure is 47Kpa, and the discharge rate of the concentrated product at the bottom of the concentration evaporation device is 65.2t / h, with a concentration of 36.9%.

[0032] Step (2): After the steam from step (1) enters the distillation unit, it comes into countercurrent contact with the reflux water input by the reflux pump in step (4), and sufficient heat and mass transfer occurs in the distillation unit. The reflux flow rate is 2 t / h, and the temperature is 76°C. The residual liquid flow rate at the bottom of the distillation unit is 2.1 t / h, the temperature is 80°C, and the ammonia nitrogen content is 237.0 mg / L.

[0033] Step (3): The steam (flow rate 9.9t / h, temperature 76°C, pressure 43kPa) coming out of the top of the distillation device in step (2) is cooled in the condenser and condensed. 9.8t / h of the steam is condensed into water, which is separated from the 0.1t / h steam in the gas-liquid separator (5). The steam is sent to the post-processing device (6) and condensed into condensate after absorbing heat in the circulating water cooler. The non-condensable gas is discharged and the 0.1t / h condensate is returned to the gas-liquid separator (5).

[0034] Step (4): The condensate from the gas-liquid separation tank in step (3) is pumped out by a reflux pump at 2 t / h and fed into step (2). 7.9 t / h of purified condensate is pumped out by a purified liquid pump, and its ammonia nitrogen content is 0.3 mg / L.

[0035] Step (5): The residual liquid output pump in step (2) delivers 2.1t / h of wastewater with high ammonia nitrogen concentration to an external unit that separately treats ammonia nitrogen in wastewater. The ammonia nitrogen content in the purified liquid in step (4) is 0.3mg / L, which is low in ammonia nitrogen content. After cooling, it can be used as a raw material for producing desalted water.

[0036] Example 4 The system of Example 1 is used to concentrate a phosphoric acid solution containing chloride ions and organic matter, and the process includes the following steps: (The following data are for continuous and stable operation) The main components of the material to be concentrated in step (1) are 36% phosphoric acid, 1% chlorine, and 0.05% organic matter. The feed rate of the concentration evaporator is 100 t / h, and 0.5 MPa steam is used for indirect heating and concentration. After defoaming, the steam produced by evaporation contains a mixture of 3000 g / h chlorine and 0.04 t / h organic matter water vapor, which enters the distillation unit. The concentrated product output at the bottom of the concentration evaporator is 90 t / h, and the phosphoric acid concentration is 40%.

[0037] The other operating steps are the same as those in Example 3, and the specific parameters are shown in Table 1.

[0038] Example 5 The system of Example 1 is used to concentrate a phosphoric acid solution containing chloride ions and organic matter, and the process includes the following steps: (The following data are for continuous and stable operation) Step (1): The main components of the material to be concentrated are 36% phosphoric acid, 1% chlorine, and 0.13% organic matter. The feed rate of the concentration evaporator is 100t / h, and 0.5MPa steam is used for indirect heating and concentration. After defoaming, the steam produced by evaporation contains a mixture of 3000g / h chlorine and 0.1t / h organic matter water vapor, which enters the distillation unit. The discharge rate of the concentrated product at the bottom of the concentration evaporator is 90t / h, with a concentration of 40%.

[0039] The other operating steps are the same as those in Example 3, and the specific parameters are shown in Table 1.

[0040] Table 1

[0041] Example 6 The system of Example 2 is used to concentrate a phosphoric acid solution containing chloride ions and organic matter, and the process includes the following steps: (The following data are for continuous and stable operation) Step (1): The composition of the material to be concentrated is: 36% phosphoric acid, 1% chlorine, and 0.05% organic matter. The feed rate of the concentration evaporation device is 100t / h. 0.5MPa steam is used for indirect heating and concentration. After defoaming, the steam produced by evaporation contains 3000g / h chlorine and 0.04t / h organic matter. The steam mixture with a steam pressure of 103kPa (absolute pressure) and a steam temperature of 105℃ enters the distillation device. The discharge rate of the concentrated product at the bottom of the concentration evaporation device is 90t / h, and the concentration is 40%.

[0042] Step (2): After the steam from step (1) enters the first-stage distillation unit, it comes into countercurrent contact with the reflux water input by the reflux pump in step (4), and sufficient heat and mass transfer occurs in the distillation unit. The reflux flow rate is 1.5 t / h, and the temperature is 100°C. The bottom residual liquid flow rate of the first-stage distillation unit is 1.6 t / h, the temperature is 103°C, the chlorine content is 1875 mg / L, and the COD content is 500 mg / L.

[0043] Step (3): The steam (flow rate 9.9 t / h, temperature 102°C, pressure 102 kPa) coming out of the top of the distillation unit in step (2) is cooled in a condenser and condensed. 9 t / h of the steam is condensed into water, which is then separated into gas and liquid by the 0.9 t / h water vapor and organic vapor in the gas-liquid separator (5). The vapor is then sent to step (5).

[0044] Step (4): The condensate from the gas-liquid separation tank in step (3) is pumped through a reflux pump to extract 1.5 t / h of material into step (2), and 7.5 t / h of condensate is pumped out through a pump, and its organic matter content is 0.0045 t / h.

[0045] Step (5): 0.9 t / h of water vapor and organic vapor from step (3) are sent to the second-stage distillation unit and contacted with 0.76 t / h of reflux liquid in reverse heat and mass transfer. The organic vapor and a small amount of water vapor (totaling 0.8 t / h) enter the condenser for condensation and then enter the gas-liquid separation tank for separation. The material in the gas-liquid separation tank is refluxed as reflux liquid, with a withdrawal rate of 0.04 t / h (organic component 0.031 t / h). The purified high-concentration organic matter has low water content and is recycled in the original device production system. 0.86 t / h of the residual liquid at the bottom of the second-stage distillation unit (organic component 0.0045 t / h) is discharged.

[0046] The percentages in the above embodiments are all by mass.

[0047] The above embodiments describe preferred embodiments of the present invention, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent of the present invention shall be based on the appended claims.

Claims

1. A condensation and purification system for steam generated during the concentration and evaporation process, characterized in that: The invention comprises a concentration evaporation device (1), wherein a bottom discharge port of the concentration evaporation device returns to the concentration evaporation device (1) through a pipeline, a concentration circulation pump (2), and a steam heater (3); a gas phase outlet descaling device (4) is provided on the top of the concentration evaporation device (1) and is connected to the lower part of a distillation device (5); a gas phase outlet at the top of the distillation device passes through a condenser (6) and is connected to a gas-liquid separation device (7); the bottom of the gas-liquid separation device is connected to a return port on the upper part of the distillation device through a reflux pump (8); the lower part of the gas-liquid separation device is connected to a purified liquid outlet pipe, and the upper part is provided with a gas phase discharge pipe.

2. The system according to claim 1, wherein: The system includes multiple groups of distillation devices, heat exchangers, gas-liquid separation devices and reflux pumps. The gas phase pipeline of each group of distillation devices is connected to the upper reflux port of the distillation device through the heat exchanger, gas-liquid separation device and reflux pump, and the gas phase discharge pipe of the previous group of gas-liquid separation devices is connected to the lower air inlet of the next group of distillation devices.

3. The system according to claim 1, wherein: The steam heater (3) is connected to the fresh steam pipeline; an inlet for the material to be concentrated is provided on the pipeline between the concentration evaporation device (1) and the concentration circulation pump (2); and a concentrated product discharge port is also provided at the bottom of the concentration evaporation device.

4. The system according to claim 1, wherein: The descaling device (4) is a cyclone demister, a settling chamber, or a washing tower.

5. The system according to claim 1, wherein: The bottom of the distillation device is provided with a residual liquid accommodating space, which is connected to the residual liquid output pump and pipeline; the middle section or the lower section of the distillation device is provided with a foreign material feeding port.

6. The system according to any one of claims 1 to 5, characterized in that: A post-processing device is further connected to the gas phase discharge pipe of the gas-liquid separation device (7).

7. A method for condensing and purifying steam generated during a concentration and evaporation process, characterized in that: The following steps are involved: S1, the material to be concentrated enters the concentration evaporation device for evaporation and concentration, and the concentrated product is drawn out; S2. The gas phase generated during the production process of the concentration and evaporation device is drawn out from the top and enters the distillation device, where it is purified both as a raw material to be purified and as a heat source. The temperature and reflux ratio in the distillation device are controlled at a certain level according to the boiling point of the impurities to be removed. The gas phase entering the distillation device contacts the reflux material in a reverse direction. Finally, the gas phase at the top is condensed into a liquid phase through heat exchange, part of which is refluxed into the distillation device, and part is withdrawn as a purified liquid, or enters a subsequent distillation device for purification and then drawn out.

8. The method according to claim 7, wherein: The steam evaporated by the concentration evaporation device contains water; it also contains one or more of phosphate ions, fluoride ions, chloride ions, ammonium ions, ammonia water and organic matter.

9. Use of the condensation and purification system for steam generated during the concentration and evaporation process according to any one of claims 1 to 6 or the condensation and purification method for steam generated during the concentration and evaporation process according to any one of claims 7 to 8 in material concentration.

10. The use according to claim 9, characterized in that: The material to be concentrated is the material that is brought into the material itself due to foam during evaporation, or the material itself contains volatile and easily evaporated components.

Images