Double-effect steam condensate purification unit in double-effect concentration process

Abstract

This utility model relates to the field of fine chemicals, specifically providing a purification device for the condensate from a double-effect steam in a double-effect concentration process. The device includes a first-effect concentration unit and a second-effect concentration unit. The vapor phase from the lower part of the first-effect concentration unit passes through a first-effect circulating pump and a first-effect heater before returning to the first-effect concentration unit. Similarly, the vapor phase from the lower part of the second-effect concentration unit passes through a second-effect circulating pump and a second-effect heater before returning to the second-effect concentration unit. The top vapor phase from the first-effect concentration unit passes through a first-effect demister and is connected to the lower part of a distillation unit. The top vapor phase from the distillation unit is condensed by heat exchange in the second-effect heater and then connected to a gas-liquid separator. The bottom of the gas-liquid separator is connected to the upper part of the distillation unit via pipes and pumps to form a circulation loop. The gas-liquid separator also has a condensate outlet and a vapor phase outlet. This device, by adding a distillation unit, first distills the steam from the first-effect concentration process and then condenses it, saving energy and resulting in a high yield of purified liquid at a low cost.

Description

Technical Field

[0001] This utility model belongs to the field of fine chemical technology, specifically relating to a double-effect steam condensate purification device in a double-effect concentration process. Background Technology

[0002] In traditional concentration evaporation processes, the evaporated water vapor is condensed into condensate after passing through circulating water. However, the condensate contains a large number of impurities, making it unsuitable for reuse as process water and unacceptable for direct discharge due to environmental regulations. It requires wastewater treatment before discharge. Purifying the condensate through distillation requires significant energy consumption, while other purification methods such as filtration also necessitate substantial equipment investment. Summary of the Invention

[0003] This invention provides a purification device for the condensate of a double-effect steam in a double-effect concentration process. It only adds a distillation device between the first-effect concentration device and the second-effect concentration device, and distills the steam in the concentration process of the first-effect concentration device before heat exchange and condensation, which saves energy and produces a high yield of purified liquid at a low cost.

[0004] The technical solution of this utility model is to provide a double-effect steam condensate purification device in a double-effect concentration process, including a first-effect concentration device and a second-effect concentration device. The lower part of the first-effect concentration device returns to the first-effect concentration device after passing through a first-effect circulation pump and a first-effect heater in sequence. The lower part of the second-effect concentration device returns to the second-effect concentration device after passing through a second-effect circulation pump and a second-effect heater in sequence. The gas phase at the top of the first-effect concentration device is connected to the lower part of the distillation device after passing through a first-effect demister. The gas phase at the top of the distillation device is connected to a gas-liquid separator after heat exchange in the second-effect heater. The bottom of the gas-liquid separator is connected to the upper part of the distillation device through pipes and pumps to form a circulation loop. The gas-liquid separator is also provided with a condensate purification outlet and a gas phase outlet.

[0005] Optionally, a feed pipe for the raw material to be concentrated is also connected to the pipeline between the single-effect thickener and the single-effect circulating pump.

[0006] Optionally, a single-effect heater is connected to a fresh steam pipe.

[0007] Optionally, the distillation equipment has a cavity at the bottom for containing distillation residue, and the bottom of the cavity is provided with a residue outlet, which is connected to the water treatment process through a pipeline and a residue pump.

[0008] Optionally, the upper part of the gas-liquid separator is provided with a gas phase outlet, which is either vented or connected to a gas phase post-processing step.

[0009] Optionally, the concentrate outlet of the first-effect thickener is connected via a pipeline to the pipeline between the second-effect thickener and the second-effect circulating pump; the second-effect thickener is equipped with a concentrated product outlet.

[0010] Optionally, the top gas phase of the double-effect concentrator is connected to the condenser after passing through a double-effect demister.

[0011] Optionally, both the first-effect demister and the second-effect demister are provided with a liquid phase outlet at the bottom. The liquid phase outlet of the first-effect demister is connected to the first-effect concentrator, and the liquid phase outlet of the second-effect demister is connected to the second-effect concentrator.

[0012] This utility model has the following beneficial effects: This invention adds a distillation unit between the first-effect concentration unit and the second-effect concentration unit. The gas phase from the first-effect concentration unit directly enters the distillation unit. This gas phase serves as both the raw material to be purified and the heat source for the distillation unit, avoiding the introduction of external heat, significantly reducing the cost of purified materials, and possessing extremely high economic benefits.

[0013] This device purifies the double-effect steam condensate before it is obtained, directly producing purified double-effect steam condensate that can be directly discharged from the system for reuse. At the same time, it can also use external materials of the same type to replace the reflux liquid in the gas-liquid separator, which can significantly increase the yield of double-effect steam condensate.

[0014] This device can concentrate the residual liquid in a distillation unit. Once the material in the residual liquid reaches a certain concentration, it can be recovered and used as raw material in other production processes. Alternatively, a separate treatment device can be used to treat the residual liquid. Since the amount of residual liquid after treatment by the distillation column is significantly reduced compared to the amount of condensate from conventional concentration and evaporation, the treatment cost is greatly reduced, resulting in extremely high economic benefits. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the present utility model; In the diagram: 1. First-effect concentration equipment; 2. First-effect circulating pump; 3. First-effect heater; 4. First-effect demister; 5. Distillation equipment; 6. Gas-liquid separator; 7. Distillation circulating pump; 8. Second-effect concentration equipment; 9. Second-effect circulating pump; 10. Gas-liquid separator condensate outlet; 11. Gas-liquid separator gas phase outlet; 12. Raw material feed pipe to be concentrated; 13. Fresh steam pipe; 14. Distillation equipment residual liquid discharge outlet; 15. Concentrated product outlet. Detailed Implementation

[0016] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.

[0017] like Figure 1As shown, this utility model provides a double-effect steam condensate purification device in a double-effect concentration process, including a first-effect concentration unit 1 and a second-effect concentration unit 8. The lower part of the first-effect concentration unit passes through a first-effect circulation pump 2 and a first-effect heater 3 before returning to the first-effect concentration unit. The lower part of the second-effect concentration unit passes through a second-effect circulation pump 9 and a second-effect heater 10 before returning to the second-effect concentration unit. The gas phase at the top of the first-effect concentration unit passes through a first-effect demister 4 and is connected to the lower part of a distillation unit 5. The gas phase at the top of the distillation unit is condensed by heat exchange in the second-effect heater 10 and then connected to a gas-liquid separator 6. The bottom of the gas-liquid separator is connected to the upper part of the distillation unit through a pipe and a distillation circulation pump 7 to form a circulation loop. The gas-liquid separator also has a condensate purified liquid outlet 11 and a gas phase outlet 12. The purified liquid can be recycled by other devices.

[0018] In some embodiments, a feed pipe 13 for the raw material to be concentrated is also connected to the pipeline between the first-effect concentrator and the first-effect circulating pump. The raw material to be concentrated can be a high-concentration acid aqueous solution (containing organic matter) or a high-concentration inorganic salt aqueous solution (containing ammonia or acid). The steam generated during the concentration and evaporation process may contain water and various ionic impurities, such as fluoride ions, chloride ions, ammonia, phosphoric acid, sulfuric acid, methanol, etc.; the purified liquid is generally water, organic matter, or a combination of water and organic matter.

[0019] In some embodiments, a first-effect heater is connected to a fresh steam pipe 14. The steam pipe exchanges heat with the material to be concentrated in the first-effect heater, and the steam temperature drops to produce first-effect steam condensate. This steam condensate can be directly recycled to generate steam, or it can be used as demineralized water after simple purification, which will not be elaborated here.

[0020] In some embodiments, the distillation apparatus has a cavity at the bottom for containing distillation residue, and the bottom of the cavity is provided with a residue outlet 15, which is connected to the water treatment process via a pipeline and a residue pump. In conventional processes, the distillation apparatus is generally located above the concentration apparatus, and the refluxed material from distillation returns to the concentration apparatus. In this device, the distillation apparatus is independent of the first-effect concentration apparatus, allowing only the steam from the first-effect concentration apparatus to enter the distillation apparatus. The refluxed material from distillation is directly retained at the bottom for further concentration, reducing the workload of the concentration apparatus. The residue outlet can also use a residue pump to separately transport residue with high impurity content for further treatment.

[0021] In some embodiments, the gas-liquid separator is provided with a gas phase outlet at the top, which is either vented or connected to a gas phase post-processing step. The separated and purified uncondensed vapor and non-condensable gases are discharged.

[0022] The single-effect thickener is equipped with a feed pipe and a discharge pipe, and the double-effect thickener is also equipped with a feed pipe and a discharge pipe; the discharge pipe of the single-effect thickener is connected to the double-effect thickener, or vice versa. The concentration sequence in the thickeners can be determined according to needs; for example, single-effect thickener can be used first, followed by double-effect thickener. See details... Figure 1 Alternatively, a two-effect concentration can be performed first, followed by a single-effect concentration (not shown in the figure).

[0023] The concentrate outlet of the first-effect thickener is connected via a pipeline to the pipeline between the second-effect thickener and the second-effect circulating pump; the second-effect thickener is equipped with a concentrated product outlet 16. The material to be concentrated is first concentrated in the first-effect thickener, and then enters the second-effect thickener for further concentration to obtain the target concentrated product.

[0024] In some embodiments, the top gas phase of the double-effect concentrator is connected to the condenser after passing through a double-effect demister.

[0025] In some embodiments, both the first-effect demister and the second-effect demister have a liquid phase outlet at their bottom. The liquid phase outlet of the first-effect demister is connected to the first-effect concentrator, and the liquid phase outlet of the second-effect demister is connected to the second-effect concentrator. The demisters remove liquid droplets and small amounts of solids from the top vapor phase of the first-effect and second-effect concentrators, respectively, ensuring that the vapor entering the distillation unit is free of solids.

[0026] The following uses the dual-effect concentration of monoammonium phosphate as an example to illustrate the operation scheme of this device.

[0027] A 32wt% monoammonium phosphate solution is introduced into a two-effect concentrator. Secondary steam at 0.05 MPa, evaporated in the first-effect flash chamber, is introduced into the second-effect heater for indirect heating. The solution is continuously concentrated in the second-effect concentrator until it reaches a concentration of 37%. It is then introduced into the second-effect concentrator for further concentration until it reaches a concentration of 44.6%, at which point it is withdrawn from the unit. The steam generated in the first-effect concentrator is treated by a first-effect demister and then enters a distillation unit at a temperature of 120℃ (0.1 MPa). Distillation occurs in the distillation unit, where a small amount of liquid droplets containing material and water-soluble impurities combine with water to form high-boiling-point substances (such as monoammonium phosphate) that remain in the residual liquid. During the distillation process, the liquid from the reflux of the distillation vapor phase is used for contact heat exchange to fully absorb impurities in the vapor phase, ensuring that the impurities are retained in this process. The residual liquid is specifically an aqueous solution containing ammonium and phosphate ions, which is discharged when it reaches 60% of the full liquid level in the storage area of ​​the distillation equipment. The vapor phase entering the double-effect heater has high purity and is directly condensed into high-purity distilled pure water. It then enters the gas-liquid separator for gas-liquid separation. Uncondensed vapor and non-condensable gases are discharged, and the purified water can be reused by other units (such as demineralized water production units).

[0028] The above embodiments describe preferred embodiments of the present invention, but the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including combining the various technical features in any other way. These simple modifications and combinations should also be considered as the content disclosed by the present invention and all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent should be determined by the appended claims.

Claims

1. A device for purifying double-effect steam condensate in a double-effect concentration process, characterized in that: It includes a first-effect concentrator and a second-effect concentrator. The lower part of the first-effect concentrator passes through a first-effect circulating pump and a first-effect heater before returning to the first-effect concentrator. The lower part of the second-effect concentrator passes through a second-effect circulating pump and a second-effect heater before returning to the second-effect concentrator. The gas phase at the top of the first-effect concentrator passes through a first-effect demister and is connected to the lower part of the distillation unit. The gas phase at the top of the distillation unit is condensed by heat exchange in the second-effect heater and then connected to the gas-liquid separator. The bottom of the gas-liquid separator is connected to the upper part of the distillation unit through pipes and pumps to form a circulation loop. The gas-liquid separator is also equipped with a condensate purified liquid outlet and a gas phase outlet.

2. The two-stage condensate polishing unit for a double-effect concentration process according to claim 1, characterized in that: The pipeline between the single-effect thickener and the single-effect circulating pump is also connected to the feed pipe of the raw material to be thickened.

3. The two-stage steam condensate polishing unit in a double-effect concentration process according to claim 1, characterized in that: The single-effect heater is connected to the fresh steam pipe.

4. The apparatus for purification of the second effect steam condensate in a double effect concentration process according to claim 1, characterized in that: The distillation equipment has a cavity at the bottom for containing distillation residue, and the bottom of the cavity is provided with a residue outlet, which is connected to the water treatment process through a pipeline and a residue pump.

5. The apparatus for purification of the second effect steam condensate in a double effect concentration process according to claim 1, characterized in that: The gas-liquid separator is provided with a gas phase outlet at the top, which is either vented or connected to a gas phase post-processing step.

6. The apparatus for purification of the second effect steam condensate in a double effect concentration process according to claim 1, characterized in that: The single-effect thickener is equipped with a feed pipe and a discharge pipe, and the double-effect thickener is also equipped with a feed pipe and a discharge pipe; the discharge pipe of the single-effect thickener is connected to the double-effect thickener or the discharge pipe of the double-effect thickener is connected to the single-effect thickener.

7. The apparatus for purification of the second effect condensate of a double effect concentration process according to claim 1, characterized in that: The top gas phase of the double-effect concentrator is connected to the condenser after passing through a double-effect demister.

8. The double-effect steam condensate purification device in the double-effect concentration process according to any one of claims 1 to 7, characterized in that: Both the first-effect demister and the second-effect demister have a liquid phase outlet at the bottom. The liquid phase outlet of the first-effect demister is connected to the first-effect concentration equipment, and the liquid phase outlet of the second-effect demister is connected to the second-effect concentration equipment.

Images