Titanium dioxide production waste acid concentration system

Abstract

The utility model relates to a waste acid concentration system for titanium dioxide production, which is characterized in that a first-effect evaporator, a second-effect evaporator and a flash evaporator are designed for three-step gradual evaporation, so that the system is less in required equipment, easy to control, flexible and convenient to operate, low in energy consumption and capable of efficiently concentrating waste acid, further recycling the waste acid, reducing the use amount of fresh sulfuric acid and reducing the production cost. Meanwhile, the use amount of limestone and quicklime during waste acid neutralization is reduced, resources are saved, the solid stacking space is reduced, and pollution to the environment is reduced.

Description

Technical Field

[0001] The utility model belongs to the field of sulfuric acid process titanium dioxide production technology equipment, and specifically relates to a titanium dioxide production waste acid concentration system. Background Art

[0002] In the production of titanium dioxide by sulfuric acid method, a large amount of concentrated sulfuric acid is required, and a large amount of waste acid is generated in the process. There are usually two ways to deal with the waste acid. One is neutralization treatment, which requires a large amount of limestone and quicklime. Limestone and quicklime are expensive and need to be further crushed before they can be fully utilized. The processing cost is high, and a large amount of solid calcium mud will be generated after neutralization treatment, which takes up a lot of space when stacked and pollutes the environment. The second is recycling. The waste acid produced by titanium dioxide by sulfuric acid method has a large output and low concentration, and its direct utilization value is low. The utilization value can be increased after concentration. The ordinary concentration process has high energy consumption, and the material temperature in the concentration process is high. The strong acid is easy to corrode and block the equipment, making the production unstable. Summary of the invention

[0003] The utility model aims to avoid the shortcomings of the prior art and provide a waste acid concentration system for titanium dioxide production.

[0004] To achieve the above purpose, the technical solution adopted by the utility model is: a titanium dioxide production waste acid concentration system, characterized in that: the outlet of the primary preheater is connected to the inlet of the first-effect circulation pump, the outlet of the first-effect circulation pump is connected to the first-effect heater, the outlet of the first-effect heater is connected to the first-effect evaporator, and the bottom outlet of the first-effect evaporator is returned to the inlet of the first-effect circulation pump;

[0005] The outlet of the first-effect circulation pump is also connected to the secondary preheater through an acid pouring pipe, the outlet of the secondary preheater is connected to the inlet of the second-effect circulation pump, the outlet of the second-effect circulation pump is connected to the second-effect heater, the outlet of the second-effect heater is connected to the second-effect evaporator, the bottom outlet of the second-effect evaporator is returned and connected to the inlet of the second-effect circulation pump, the middle acid pipe of the second-effect evaporator is connected to the inlet of the flash circulation pump, the outlet of the flash circulation pump is connected to the flash evaporator, the bottom outlet of the flash evaporator is returned and connected to the inlet of the flash circulation pump, and the concentrated acid outlet of the flash evaporator is connected to the liquid seal tank;

[0006] The upper outlet of the first-effect evaporator is connected to the corresponding atomizing condenser through a vacuum pipe; the upper outlet of the flash evaporator is connected to another atomizing condenser through another vacuum pipe, and the water outlets of the two atomizing condensers are both connected to a circulating water pool, and the outlets at the bottom of the circulating water pool are respectively connected to the corresponding atomizing condensers through a circulating water pump.

[0007] The liquid seal tank is connected with an overflow pipe, which is connected to the concentrated acid tank, so as to stabilize the vacuum degree of the system and make the production stable and reliable.

[0008] The steam pipe at the top of the second-effect evaporator is connected to the first-effect heater, and the secondary steam generated by the second-effect evaporator is used as the heat source of the first-effect heater. The condensate pipe of the first-effect heater is connected to the first-stage preheater and used as the heat source of the first-stage preheater. The condensate discharge pipe of the first-stage preheater is connected to the condensate tank.

[0009] The second-effect heater is connected to the fresh steam pipe, the condensate pipe of the second-effect heater is connected to the secondary preheater and is used as the heat source of the secondary preheater, and the condensate discharge pipe of the secondary preheater is connected to the condensate tank.

[0010] The outlet of the flash circulation pump is also connected to a return pipe, and the return pipe is connected to the inlet of the second-effect circulation pump.

[0011] The beneficial effects of the utility model are as follows: the system is designed with a first-effect evaporator, a second-effect evaporator and a flash evaporator to perform three-step gradual evaporation, less equipment is required, easy to control, flexible and convenient to operate, low energy consumption, and waste acid can be efficiently concentrated and then recycled, thereby reducing the amount of fresh sulfuric acid used and reducing production costs; at the same time, the amount of limestone and quicklime used in neutralizing waste acid is reduced, resources are saved, solid stacking space is reduced, and pollution to the environment is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the utility model;

[0013] In the figure: 1-primary preheater, 2-primary circulation pump, 3-primary heater, 4-primary evaporator, 5-primary and secondary preheaters, 6-secondary circulation pump, 7-secondary heater, 8-secondary evaporator, 9-condensate tank, 10-flash circulation pump, 11-flash evaporator, 12-liquid seal tank, 13-concentrated acid tank, 14-atomizing condenser, 15-circulating water tank, 16-circulating water pump;

[0014] A-waste acid pipe, B-fresh steam pipe, C-acid pouring pipe, D-return pipe, E-intermediate acid pipe, F-steam pipe. DETAILED DESCRIPTION

[0015] See Figure 1 A waste acid concentration system for titanium dioxide production, characterized in that: the outlet of the primary preheater 1 is connected to the inlet of the first-effect circulation pump 2, the outlet of the first-effect circulation pump 2 is connected to the first-effect heater 3, the outlet of the first-effect heater 3 is connected to the first-effect evaporator 4, and the bottom outlet of the first-effect evaporator 4 is returned to the inlet of the first-effect circulation pump 2;

[0016] The outlet of the first-effect circulation pump 2 is also connected to the secondary preheater 5 through the acid pouring pipe C, the outlet of the secondary preheater 5 is connected to the inlet of the second-effect circulation pump 6, the outlet of the second-effect circulation pump 6 is connected to the second-effect heater 7, the outlet of the second-effect heater 7 is connected to the second-effect evaporator 8, the bottom outlet of the second-effect evaporator 8 is returned to connect the inlet of the second-effect circulation pump 6, the intermediate acid pipe E of the second-effect evaporator 8 is connected to the inlet of the flash circulation pump 10, the outlet of the flash circulation pump 10 is connected to the flash evaporator 11, the bottom outlet of the flash evaporator 11 is returned to connect the inlet of the flash circulation pump 10, and the concentrated acid outlet of the flash evaporator 11 is connected to the liquid seal tank 12; the liquid seal tank 12 is connected to an overflow pipe, and the overflow pipe is connected to the concentrated acid tank 13. The outlet of the flash circulation pump 10 is also connected to the return pipe D, and the return pipe D is connected to the inlet of the second-effect circulation pump 6.

[0017] The upper outlet of the first-effect evaporator 4 is connected to the corresponding atomizing condenser 14 through a vacuum pipe; the upper outlet of the flash evaporator 11 is connected to another atomizing condenser 14 through another vacuum pipe, and the water outlets of the two atomizing condensers 14 are both connected to a circulating water pool 15, and the outlets at the bottom of the circulating water pool 15 are respectively connected to the corresponding atomizing condensers 14 through a circulating water pump 16.

[0018] The steam pipe F at the top of the second-effect evaporator 8 is connected to the first-effect heater 3. The secondary steam generated by the second-effect evaporator 8 is used as the heat source of the first-effect heater 3. The condensate pipe of the first-effect heater 3 is connected to the first-stage preheater 1 and is used as the heat source of the first-stage preheater 1. The condensate discharge pipe of the first-stage preheater 1 is connected to the condensate tank 9.

[0019] The second-effect heater 7 is connected to the fresh steam pipe B, and the condensate pipe of the second-effect heater 7 is connected to the secondary preheater 5 and is used as the heat source of the secondary preheater 5 . The condensate discharge pipe of the secondary preheater 5 is connected to the condensate tank 9 .

[0020] Working process: low-concentration original waste acid is sent to the primary preheater 1 through the waste acid pipe A for preheating. Before entering the first-effect circulation pump 2, it enters the first-effect heater 3 for further heating through the first-effect circulation pump 2, and then enters the first-effect evaporator 4. It continues to circulate through the first-effect circulation pump 2 and the first-effect heater 3. After the waste acid in the first-effect evaporator 4 reaches a certain liquid level and temperature, it enters the secondary preheater 5 through the acid pouring pipe C for further heating, and then is sent to the inlet of the second-effect circulation pump 6, and is heated by the second-effect circulation pump 6 through the second-effect heater 7 before entering After entering the second-effect evaporator 8, the second-effect circulating pump 6 continues to work and the second-effect heater 7 heats the waste acid. When the waste acid in the second-effect evaporator 8 reaches a certain temperature and liquid level, the waste acid will enter the inlet of the flash circulation pump 10 along the intermediate acid pipe E, and the flash circulation pump 10 will work, and the waste acid will enter the flash evaporator 11 for further evaporation. After reaching the specified concentration, it will flow into the liquid seal tank 12 by gravity, and then enter the concentrated acid tank 13 through the overflow pipe, and be reused in other places; the unqualified waste acid is sent to the front of the second-effect circulating pump 6 by the return pipe D, and continues to be concentrated until it is qualified.

[0021] The circulating water in the circulating water pool 15 is sent to the atomizing condenser 14 through the circulating water pump 16. At this time, under the action of the large-flow water jet and the condensation of the water vapor evaporated in the first-effect evaporator 4 and the flash evaporator 11, a vacuum is formed in the first-effect evaporator 4 and the flash evaporator 11, which can save the traditional condenser and vacuum pump, reduce energy consumption, and reduce maintenance costs; the water vapor generated in the second-effect evaporator 8 enters the first-effect heater 3 through the steam pipe F for condensation, and a negative pressure is formed in the second-effect evaporator 8, the boiling point of the waste acid is reduced, and it evaporates at a lower temperature; the fresh steam enters the second-effect heater 7 from the fresh steam pipe B for heating and condensation, and the condensed water enters the secondary preheater 5 to heat the material and then enters the condensate tank 9; the temperature in the second-effect evaporator 8 is high, and the secondary steam formed by evaporation heats the first-effect heater 3 through the steam pipe F. The condensed water after heating passes into the primary preheater 1, heats the original waste acid and then enters the condensate tank 9.

Claims

1. A waste acid concentration system for titanium dioxide production, Features: The outlet of the primary preheater (1) is connected to the inlet of a first-effect circulation pump (2), the outlet of the first-effect circulation pump (2) is connected to a first-effect heater (3), the outlet of the first-effect heater (3) is connected to a first-effect evaporator (4), and the bottom outlet of the first-effect evaporator (4) is returned and connected to the inlet of the first-effect circulation pump (2); The outlet of the first-effect circulation pump (2) is also connected to the second-effect preheater (5) through an acid pouring pipe (C), the outlet of the second-effect preheater (5) is connected to the inlet of the second-effect circulation pump (6), the outlet of the second-effect circulation pump (6) is connected to the second-effect heater (7), the outlet of the second-effect heater (7) is connected to the second-effect evaporator (8), the bottom outlet of the second-effect evaporator (8) is returned and connected to the inlet of the second-effect circulation pump (6), the intermediate acid pipe (E) of the second-effect evaporator (8) is connected to the inlet of the flash circulation pump (10), the outlet of the flash circulation pump (10) is connected to the flash evaporator (11), the bottom outlet of the flash evaporator (11) is returned and connected to the inlet of the flash circulation pump (10), and the concentrated acid outlet of the flash evaporator (11) is connected to the liquid sealing tank (12); The upper outlet of the first-effect evaporator (4) is connected to a corresponding atomizing condenser (14) via a vacuum pipe; the upper outlet of the flash evaporator (11) is connected to another atomizing condenser (14) via another vacuum pipe; the water outlets of the two atomizing condensers (14) are both connected to a circulating water pool (15); and the outlets at the bottom of the circulating water pool (15) are respectively connected to the corresponding atomizing condensers (14) via a circulating water pump (16).

2. A titanium dioxide production waste acid concentration system as claimed in claim 1, Features: The liquid seal tank (12) is connected to an overflow pipe, and the overflow pipe is connected to the concentrated acid tank (13).

3. A titanium dioxide production waste acid concentration system as claimed in claim 1, Features: The steam pipe (F) at the top of the second-effect evaporator (8) is connected to the first-effect heater (3), and the secondary steam generated by the second-effect evaporator (8) is used as the heat source of the first-effect heater (3). The condensate pipe of the first-effect heater (3) is connected to the first-stage preheater (1) and used as the heat source of the first-stage preheater (1). The condensate discharge pipe of the first-stage preheater (1) is connected to the condensate tank (9).

4. A titanium dioxide production waste acid concentration system as claimed in claim 1, Features: The second-effect heater (7) is connected to the fresh steam pipe (B), the condensate pipe of the second-effect heater (7) is connected to the secondary preheater (5) and is used as the heat source of the secondary preheater (5), and the condensate discharge pipe of the secondary preheater (5) is connected to the condensate tank (9).

5. A titanium dioxide production waste acid concentration system as claimed in claim 1, Features: The outlet of the flash circulation pump (10) is also connected to a return pipe (D), and the return pipe (D) is connected to the inlet of the secondary effect circulation pump (6).

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