Residual ammonia water distillation system without adding liquid caustic soda

Abstract

The utility model discloses a residual ammonia water distillation system without adding liquid caustic soda, and belongs to the technical field of coking and semi-coke. The residual ammonia water distillation system comprises a raw material ammonia water tank, a raw material ammonia water pump, an ammonia water-wastewater heat exchanger, an ammonia still, a wastewater intermediate tank, a reverse osmosis module, a blending tank, a hydrochloric acid rectifying tower and an acid-base neutralization tank. According to the technical scheme, by utilizing the system, a residual ammonia water distillation process without adding liquid caustic soda is realized, the production cost can be reduced, and the pollution can be reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of coking and blue charcoal, in particular to a residual ammonia distillation system without adding liquid alkali. Background Art

[0002] The residual ammonia water in the coking and semi-coke industries contains high concentrations of fixed ammonium salts such as ammonium chloride and ammonium sulfate. Sodium hydroxide needs to be added to decompose the fixed ammonium salts. The acid-base neutralization principle is used to decompose the fixed ammonium salts and release ammonia gas, thereby reducing the ammonia nitrogen concentration in the discharged wastewater and preventing it from having an adverse effect on the subsequent biochemical system. Liquid caustic soda reacts with ammonium sulfate to produce ammonia and ammonium sulfate, and reacts with ammonium chloride to produce ammonia and sodium chloride, as follows:

[0003] (NH4)2SO4+NaOH→Na2SO4+NH3↑

[0004] NH4Cl+NaOH→NaCl+NH3↑

[0005] Large-scale coking and lignite enterprises need to spend tens of millions of yuan every year to purchase liquid alkali, which increases the cost of the entire process.

[0006] In the process of using sodium hydroxide to decompose fixed ammonium salts, a large amount of secondary pollutants such as sodium sulfate and sodium chloride are formed at the bottom of the ammonia evaporation tower, which makes the treatment of ammonia evaporation wastewater more difficult and increases the cost of the entire process.

[0007] However, the existing patents for distilling ammonia from residual ammonia water are all based on energy conservation, and no research is conducted on saving liquid caustic soda.

[0008] Therefore, it is necessary to design a residual ammonia distillation system without adding liquid alkali. Utility Model Content

[0009] The purpose of the utility model is to provide a residual ammonia distillation system without adding liquid alkali, so as to solve the problems raised in the above background technology.

[0010] To achieve the above objectives, the present invention provides the following technical solutions:

[0011] A residual ammonia distillation system without adding liquid alkali comprises a raw ammonia water tank, an ammonia removal device, a pH value regulating device and a concentrated brine treatment device which are connected in sequence.

[0012] As a further solution of the present invention: the ammonia removal device includes an ammonia water-wastewater heat exchanger and an ammonia evaporation tower, the upper and lower ends of the ammonia evaporation tower are both connected to the ammonia water-wastewater heat exchanger, the ammonia water-wastewater heat exchanger is connected to the raw ammonia water tank, and the ammonia water-wastewater heat exchanger is connected to the pH value regulating device.

[0013] As a further solution of the present invention: the pH value regulating device includes a wastewater intermediate tank, a reverse osmosis module and a mixing tank connected in sequence, the wastewater intermediate tank is connected to the ammonia-wastewater heat exchanger, and the mixing tank is connected to the concentrated brine treatment device.

[0014] As a further solution of the present invention: the concentrated brine treatment device includes a hydrochloric acid distillation tower and an acid-base neutralization tank connected in sequence, and the hydrochloric acid distillation tower is connected to the preparation tank.

[0015] As a further solution of the present invention: a raw ammonia water pump is provided between the ammonia water-wastewater heat exchanger and the raw ammonia water tank, and a raw ammonia water pump is provided between the wastewater intermediate tank and the reverse osmosis module.

[0016] In summary, the beneficial effects of this utility model are as follows: it improves the traditional ammonia distillation process, eliminates the addition of liquid caustic soda, and reduces production costs. Furthermore, the calcium carbonate and magnesium hydroxide produced do not cause environmental pollution. By providing a pH adjustment device and a concentrated brine treatment device, ammonium sulfate and calcium chloride can be generated without secondary pollution, eliminating the need for subsequent pollution reduction equipment, thereby reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The figure is a flow chart of a residual ammonia distillation system without adding liquid alkali.

[0018] In the figure: 1. Raw ammonia water tank; 2. Raw ammonia water pump; 3. Ammonia water-wastewater heat exchanger; 4. Ammonia distillation tower; 5. Wastewater intermediate tank; 6. Reverse osmosis module; 7. Mixing tank; 8. Hydrochloric acid distillation tower; 9. Acid-base neutralization tank. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0020] Example

[0021] See also Figure 1 ,like Figure 1 As shown, a residual ammonia distillation system without adding liquid caustic soda comprises a raw ammonia water tank 1, a deammonification device, a pH value regulating device and a concentrated brine treatment device which are connected in sequence.

[0022] The ammonia removal device includes an ammonia water-wastewater heat exchanger 3 and an ammonia evaporation tower 4. The upper and lower ends of the ammonia evaporation tower 4 are both connected to the ammonia water-wastewater heat exchanger 3, the ammonia water-wastewater heat exchanger 3 is connected to the raw ammonia water tank 1, and the ammonia water-wastewater heat exchanger 3 is connected to the pH value regulating device.

[0023] The pH value regulating device includes a wastewater intermediate tank 5, a reverse osmosis module 6 and a blending tank 7 which are connected in sequence. The wastewater intermediate tank 5 is connected to the ammonia-wastewater heat exchanger 3, and the blending tank 7 is connected to the concentrated brine treatment device.

[0024] The concentrated brine treatment device includes a hydrochloric acid distillation tower 8 and an acid-base neutralization tank 9 which are connected in sequence, and the hydrochloric acid distillation tower 8 is connected to the mixing tank 7.

[0025] A raw ammonia water pump 2 is provided between the ammonia water-wastewater heat exchanger 3 and the raw ammonia water tank 1 , and a raw ammonia water pump 2 is provided between the wastewater intermediate tank 5 and the reverse osmosis module 6 .

[0026] A process for distilling excess ammonia water without adding liquid caustic soda comprises the following steps:

[0027] S1, the remaining ammonia water enters the raw ammonia water tank 1, and a certain amount of concentrated ammonia water is added to soften it. The pH value of the softened ammonia water is 11. The calcium and magnesium ions in the ammonia water are converted into precipitates and discharged from the bottom of the raw ammonia water tank. Under the alkaline condition of pH value reaching 11, the following chemical reactions occur in the raw ammonia water tank:

[0028] (1) Ammonium bicarbonate in the raw ammonia water reacts with calcium ions under alkaline conditions to produce calcium carbonate precipitation:

[0029] HCO 3- +OH - +Ca 2+ →CaCO3↓+H2O

[0030] (2) The magnesium ions in the raw ammonia water are completely precipitated when the pH value reaches 11:

[0031] Mg 2+ +OH - →Mg(OH)2↓

[0032] The precipitate converted from calcium and magnesium ions is discharged from the bottom of the raw ammonia water tank;

[0033] S2. The softened ammonia water is fed into the ammonia water-wastewater heat exchanger 3 through the raw ammonia water pump 2, and heat exchanged with the wastewater at the bottom of the ammonia still 4. The raw ammonia water is preheated to 95° C.-105° C. and enters the upper part of the ammonia still 4 for distillation. Preferably, the preheating temperature is stabilized at 100° C. The distilled ammonia gas is discharged from the top of the ammonia still 4, and the remaining wastewater enters the bottom of the ammonia still 4.

[0034] S3, the wastewater at the bottom of the ammonia still 4 enters the wastewater intermediate tank 5 after heat exchange and cooling, and at the same time, an appropriate amount of dilute sulfuric acid is added to the wastewater intermediate tank 5 to adjust the pH value of the wastewater to 1-2;

[0035] S4, the wastewater from the wastewater intermediate tank 5 is transported to the reverse osmosis device 6 for filtration to filter out the intermediate water and concentrated brine, the intermediate water accounts for 80-90% of the total wastewater, the intermediate water can be recycled and reused, and the concentrated brine accounts for 10-20% of the total wastewater;

[0036] S5, the concentrated brine produced after filtration enters the deployment tank 7 where sulfuric acid is added to stabilize the pH value of the concentrated brine;

[0037] S6, the prepared acidic concentrated brine enters the hydrochloric acid distillation tower 8 for distillation to distill out hydrogen chloride gas. The bottom of the hydrochloric acid distillation tower 8 is a high-concentration ammonium sulfate solution, which can be further processed to obtain ammonium sulfate particles;

[0038] S7. The hydrogen chloride gas enters the acid-base neutralization tank, and lime is added to the acid-base neutralization tank to obtain a calcium chloride solution, which can be further processed to obtain anhydrous calcium chloride product.

[0039] It should be noted that the above embodiments are only specific and clear descriptions of the technical solutions and technical features of the present application. For those skilled in the art, solutions or features that belong to the prior art or common knowledge will not be described in detail in the above embodiments.

[0040] In addition, the technical solutions of the present application are not limited to the above-mentioned embodiments. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A system for distilling excess ammonia water without adding liquid caustic soda, characterized in that: It comprises a raw ammonia water tank (1), a deammonification device, a pH value regulating device and a concentrated brine treatment device which are connected in sequence.

2. The system for distilling excess ammonia water without adding liquid caustic soda according to claim 1, characterized in that: The ammonia removal device comprises an ammonia water-wastewater heat exchanger (3) and an ammonia evaporation tower (4), wherein the upper end and the lower end of the ammonia evaporation tower (4) are both connected to the ammonia water-wastewater heat exchanger (3), the ammonia water-wastewater heat exchanger (3) is connected to the raw ammonia water tank (1), and the ammonia water-wastewater heat exchanger (3) is connected to the pH value regulating device.

3. The system for distilling excess ammonia water without adding liquid caustic soda according to claim 2, characterized in that: The pH value regulating device comprises a wastewater intermediate tank (5), a reverse osmosis module (6) and a blending tank (7) which are connected in sequence, the wastewater intermediate tank (5) is connected to the ammonia-wastewater heat exchanger (3), and the blending tank (7) is connected to the concentrated brine treatment device.

4. The system for distilling excess ammonia water without adding liquid caustic soda according to claim 3, characterized in that: The concentrated brine treatment device comprises a hydrochloric acid distillation tower (8) and an acid-base neutralization tank (9) which are connected in sequence, and the hydrochloric acid distillation tower (8) is connected to the mixing tank (7).

5. The system for distilling excess ammonia water without adding liquid caustic soda according to claim 4, characterized in that: A raw ammonia water pump (2) is provided between the ammonia water-wastewater heat exchanger (3) and the raw ammonia water tank (1), and a raw ammonia water pump (2) is provided between the wastewater intermediate tank (5) and the reverse osmosis module (6).

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