PTFE double-membrane coupling hardness and ammonia removal system applied to gasification ash water treatment

Abstract

The utility model discloses a PTFE double-membrane coupling hardness and ammonia removal system applied to gasification ash water treatment, and belongs to the field of membrane method water treatment. Comprising a high-density pool, a buffer tank, a Y-shaped filter, an ultrafiltration water inlet pump, a coarse filter, a PTFE ultrafiltration membrane, an intermediate tank, an intermediate water pump, a heat exchanger and a PTFE deamination membrane contactor which are connected in sequence, ammonia sulfate recovered by the device can be used as a byproduct, and the problems of high ammonia nitrogen content and high hardness in coal gasification grey water are solved. The treatment system provided by the utility model is convenient to operate, relatively low in cost, stable in system, good in hardness and ammonia removal effect, good in effluent quality and low in energy consumption, by-products are recycled, and the effluent can meet a back-end membrane recycling process.

Description

Technical Field

[0001] This utility model relates to a PTFE dual-membrane coupled hardening and ammonia removal system for gasification ash water treatment, which is particularly suitable for gasification ash water reuse systems and belongs to the field of membrane water treatment. Background Art

[0002] Coal gasification is a key technology in my country's coal chemical production and an important means of achieving clean utilization of coal resources. However, the gasification process generates a large amount of wastewater with high suspended solids, high COD, high ammonia nitrogen, and high hardness. Currently, the problems that need to be addressed with coal gasification ash water are: 1. Scaling in the ash water system; 2. High ammonia nitrogen content. Some manufacturers have temporarily alleviated ash water scaling by adding a certain proportion of scale inhibitors to severely scaled areas, but a serious scaling tendency still exists. Severe scaling in the ash water system will affect the continuous operation of the unit, shorten the operating cycle, and in severe cases, cause unnecessary shutdowns. Only by solving the scaling problem can the safe and stable operation of the gasification unit be guaranteed.

[0003] Chinese patent CN 110171857 A discloses a method for treating ash water from coal slurry gasification containing ammonia. This process involves pressurizing all the ash water from coal slurry gasification and sending it to an evaporation tower, and then treating it with ammonia removal through a stripping tower. This process has disadvantages such as complex flow, large number of equipment, lack of hardness removal, easy system structure, and high hardness of the treated ash water. Utility Model Content

[0004] This invention addresses the problems existing in the treatment of ash water from coal-water slurry gasification by providing a PTFE dual-membrane coupled hardness removal and ammonia removal system for gasification ash water treatment. This system effectively reduces suspended solids, hardness, and ammonia nitrogen in ash water, has a high wastewater recycling rate, low production cost, low energy consumption, and low difficulty in wastewater treatment.

[0005] To solve the problem of this utility model, the technical solution adopted is as follows: A PTFE dual-membrane coupled hardening and ammonia removal system applied to gasification ash water treatment includes: a high-density tank (1), a buffer tank (2), a pretreatment system (3), a PTFE ultrafiltration membrane (4), an intermediate tank (5), an intermediate water pump (6), a heat exchanger (7), and a PTFE ammonia removal membrane contactor (8). The high-density tank (1) is composed of a reaction zone (1-1), a pre-coagulation zone (1-2), a flocculation zone (1-3), and a sedimentation zone (1-4). A first agitator (1-7), a second agitator (1-8), and a third agitator (1-9) are respectively installed in the reaction zone (1-1), the pre-coagulation zone (1-2), and the flocculation zone (1-3). A sludge return pump (1-6) and a sludge discharge pump (1-5) are installed at the sludge pipe at the bottom of the sedimentation zone (1-4).

[0006] The outlet of the high-density tank (1) is connected to the buffer tank (2); the buffer tank (2) is connected to the PTFE ultrafiltration membrane equipment (4) via a pretreatment system (3), which consists of a Y-type filter (3-1), an ultrafiltration feed pump (3-2), and a coarse filter (3-3); the outlet of the pretreatment system (3) is connected to the PTFE ultrafiltration membrane (4) and the intermediate tank (5), and the outlet of the intermediate tank (5) is connected to the inlet of the heat exchanger (7) via an intermediate water pump (6), and the outlet of the heat exchanger (7) is connected to the PTFE deammoniation membrane contactor (8).

[0007] Preferably, the Y-type filter (3-1) of the pretreatment system (3) has a filtration accuracy of 1.2 mm, and the coarse filter (3-2) has a filtration accuracy of 1 mm.

[0008] Preferably, an online pH meter is installed in the reaction zone (1-1), and an over-alkali monitoring instrument is installed in the outlet pipe of the high-density tank (1) to accurately control the dosage of chemicals.

[0009] Preferably, the buffer tank (2) has a conical bottom, a baffle (2-1) is installed at the water inlet to avoid disturbing the lower sediment, an overflow weir (2-2) is installed at the water outlet to allow the clear liquid above to overflow, and a drain valve (2-3) is installed at the bottom to discharge sludge regularly and prevent sediment from accumulating at the bottom of the tank.

[0010] Preferably, a portion of the concentrate from the PTFE ultrafiltration membrane (4) is returned to the high-density tank (1).

[0011] Beneficial effects:

[0012] 1. The PTFE dual-membrane coupled hardening and ammonia removal system described in this utility model, applied to the treatment of gasified ash water, effectively removes suspended solids, colloids, solid particles and heavy metal ions from the ash water, reduces the ammonia nitrogen content, and can reduce the hardness of the ash water to below 100 mg / L, greatly reducing the difficulty of wastewater treatment.

[0013] 2. The Y-type filter (3-1) is 1.2mm thick, and the coarse filter (3-2) is 1mm thick, forming two-stage interception and distributed filtration. Multiple coarse filters (3-2) can be operated in parallel and automatically backwashed, effectively reducing the subsequent membrane fouling load and reducing the membrane cleaning frequency.

[0014] 3. The PTFE dual-membrane coupled hardening and ammonia removal system described in this utility model, applied to the treatment of gasified ash water, has an effluent pH of 10.5~11.5 in the high-density tank. It can directly enter the PTFE ultrafiltration membrane (4) for treatment without pH adjustment, while conventional organic ultrafiltration membranes require pH adjustment to below 11. After treatment by the PTFE ultrafiltration membrane (4), the effluent enters the PTFE ammonia removal membrane contactor (8). Since the optimal pH value of the PTFE ammonia removal membrane contactor (8) is 10.5~11.5, no additional alkali solution needs to be added when entering the PTFE ammonia removal membrane contactor (8), reducing the amount of chemicals added and the pH adjustment process.

[0015] 4. The application of this utility model is in the PTFE dual-membrane coupled hardening and ammonia removal system for gasification ash water treatment. It treats gasification ash water with high hardness and high ammonia nitrogen, with good hardening and ammonia removal effect, good effluent quality, low energy consumption, by-product recovery, and effluent that can meet the requirements of downstream membrane reuse processes. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings.

[0017] Figure 1 This invention is applied to a PTFE dual-membrane coupled hardening and ammonia removal system for gasification ash water treatment.

[0018] Among them: 1-High-density tank, 1-1 Reaction zone, 1-2 Pre-coagulation zone, 1-3 Flocculation zone, 1-4 Sedimentation zone, 1-5 Sludge discharge pump, 1-6 Sludge return pump, 2-Buffer tank, 2-1 Inlet baffle, 2-2 Overflow weir, 2-3 Sewage valve, 3-Pretreatment system, 3-1 Y-type filter, 3-2 Ultrafiltration inlet pump, 3-3 Coarse filter, 4-PTFE ultrafiltration membrane, 5-Intermediate tank, 6-Intermediate water pump, 7-Heat exchanger, 8-PTFE deammoniation membrane contactor. DETAILED DESCRIPTION

[0019] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solution of this utility model will be clearly and completely described below in conjunction with the accompanying drawings and a preferred embodiment.

[0020] Example 1

[0021] The system includes: a high-density tank 1, a buffer tank 2, a pretreatment system 3, a PTFE ultrafiltration membrane 4, an intermediate tank 5, an intermediate water pump 6, a heat exchanger 7, and a PTFE ammonia removal membrane contactor 8. The high-density tank 1 consists of a reaction zone 1-1, a pre-coagulation zone 1-2, a flocculation zone 1-3, and a sedimentation zone 1-4. Agitators 1-7, 1-8, and 1-9 are installed in the reaction zone 1-1, the pre-coagulation zone 1-2, and the flocculation zone 1-3. Sludge is collected at the bottom sludge pipe of the sedimentation zone 1-4. Return pump 1-6, sludge discharge pump 1-5; the outlet of high-density tank 1 is connected to buffer tank 2; buffer tank 2 is connected to PTFE ultrafiltration membrane equipment 4 via pretreatment system 3, which consists of Y-type filter 3-1, ultrafiltration inlet pump 3-2, and coarse filter 3-3; the outlet of pretreatment system 3 is connected to PTFE ultrafiltration membrane 4 and intermediate tank 5, and the outlet of intermediate tank 5 is connected to the inlet of heat exchanger 7 via intermediate water pump 6, and the outlet of heat exchanger 7 is connected to PTFE deammoniation membrane contactor 8.

[0022] The pretreatment system has a 3Y type filter with a thickness of 1.2mm and a coarse filter with a thickness of 1mm, forming two stages of interception and distributed filtration. Multiple coarse filters can be operated in parallel and automatically backwashed.

[0023] An online pH meter is installed in reaction zone 1-1, and an over-alkali monitoring device is installed in the outlet pipe of high-density tank 1 to accurately control the dosage of chemicals.

[0024] The buffer tank 2 has a conical bottom, with a baffle 2-1 at the water inlet to avoid disturbing the lower sediments, an overflow weir 2-2 at the water outlet to allow the clear liquid above to overflow, and a drain valve 2-3 at the bottom to discharge sludge regularly and prevent sediment from accumulating at the bottom of the tank.

[0025] The concentrated water from the PTFE ultrafiltration membrane 4 is returned to the high-density tank 1.

[0026] The process of using this system is as follows:

[0027] A PTFE dual-membrane coupled hardening and ammonia removal system for gasification ash water treatment: Ash water enters a high-density tank, effluent enters a buffer tank, a Y-type filter is connected between the buffer tank and the ultrafiltration feed pump, a coarse filter is connected to the outlet of the ultrafiltration membrane feed pump, effluent enters a PTFE ultrafiltration membrane, PTFE ultrafiltration membrane permeate enters an intermediate tank, effluent is pumped by an intermediate water pump to a heat exchanger and a PTFE ammonia removal membrane contactor, and ammonia-removed permeate enters a permeate tank. The above constitutes the gasification ash water hardening and ammonia removal system.

[0028] The influent ammonia nitrogen concentration in a coal gasification ash wastewater treatment plant is 300-500 mg / L, and the hardness is 400-500 mg / L. The effluent requirements are ammonia nitrogen <50 mg / L and hardness <100 mg / L. The treatment capacity is 100 m³ / h. 3 / h.

[0029] ① The pH value of the gasified ash water is adjusted to 10.5~11.5 in reaction zone 1-1. Coagulant and flocculant are added in pre-coagulation zone 1-1 and flocculation zone 1-3. An online excess alkali analyzer is installed at the effluent outlet. The sodium hydroxide concentration in the control tank is controlled at 0.05g / l~0.4g / l, and the sodium carbonate concentration is 0.3~0.6g / L.

[0030] ② The effluent from the high-density tank enters the buffer tank. The hydraulic retention time of the buffer tank is 1 hour. The buffer tank has a conical bottom and a baffle is installed at the inlet to avoid disturbing the lower sediment. An overflow weir is installed at the outlet to allow the clear liquid to overflow. Two or three drain valves are installed at the bottom to discharge sludge regularly and prevent sediment from accumulating at the bottom of the tank.

[0031] ③ A Y-type filter 3-1 with a filtration accuracy of 1.2mm is connected to the outlet of the buffer tank. A coarse filter 3-3 is connected to the outlet of the ultrafiltration inlet pump 3-2. The coarse filter 3-3 can be operated in parallel and automatically backwashed. The coarse filter 3-3 has a filtration accuracy of 1mm. The distribution filtration method combining the Y-type filter 3-2 and the coarse filter 3-3 forms two interceptions to reduce the subsequent pollution load. If there is a blockage, the debris can be manually disassembled and cleaned.

[0032] ④ The outlet of the coarse filter 3-3 is connected to the PTFE ultrafiltration membrane 4. Part of the concentrate from the PTFE ultrafiltration membrane 4 is returned to the high-density tank 1.

[0033] ⑤ The effluent from the PTFE ultrafiltration membrane 4 enters the intermediate water tank 5, and after being connected to the intermediate water pump 6, it is lifted to the heat exchanger 7, where it is heated by steam, and then enters the PTFE deammoniation membrane contactor 8.

[0034] ⑥The PTFE deammoniation membrane contactor 8 absorbs sulfuric acid with a concentration of 2-5%, and the sulfuric acid circulation volume is 1.5-2 times the treated water volume. The concentration of the by-product ammonium sulfate can reach 15%, with high purity and recycling value.

[0035] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A PTFE dual-membrane coupled hardening and ammonia removal system for use in gasification ash water treatment, characterized in that: include: The high-density tank (1), buffer tank (2), pretreatment system (3), PTFE ultrafiltration membrane (4), intermediate tank (5), intermediate water pump (6), heat exchanger (7), and PTFE deammoniation membrane contactor (8) are provided. The high-density tank (1) consists of a reaction zone (1-1), a pre-coagulation zone (1-2), a flocculation zone (1-3), and a sedimentation zone (1-4). The reaction zone (1-1), the pre-coagulation zone (1-2), and the flocculation zone (1-3) are respectively equipped with a first agitator (1-7), a second agitator (1-8), and a third agitator (1-9). The sedimentation zone (1-4) is equipped with a sludge return pump (1-6) and a sludge discharge pump (1-5) at the bottom sludge pipe. The outlet of the high-density tank (1) is connected to the buffer tank (2); the buffer tank (2) is connected to the PTFE ultrafiltration membrane (4) via a pretreatment system (3), which consists of a Y-type filter (3-1), an ultrafiltration feed pump (3-2), and a coarse filter (3-3); the outlet of the pretreatment system (3) is connected to the PTFE ultrafiltration membrane (4) and the intermediate tank (5), and the outlet of the intermediate tank (5) is connected to the inlet of the heat exchanger (7) via an intermediate water pump (6), and the outlet of the heat exchanger (7) is connected to the PTFE deammoniation membrane contactor (8).

2. The PTFE dual-membrane coupled hardening and ammonia removal system for gasification ash water treatment according to claim 1, characterized in that: The Y-type filter (3-1) of the pretreatment system (3) has a filtration accuracy of 1.2 mm, and the coarse filter (3-3) has a filtration accuracy of 1 mm.

3. The PTFE dual-membrane coupled hardening and ammonia removal system for gasification ash water treatment according to claim 1, characterized in that: An online pH meter is installed in the reaction zone (1-1), and an over-alkali monitoring instrument is installed in the outlet pipe of the high-density tank (1).

4. The PTFE dual-membrane coupled hardening and ammonia removal system for gasification ash water treatment according to claim 1, characterized in that: The buffer tank (2) has a conical bottom, a baffle (2-1) is installed at the water inlet, an overflow weir (2-2) is installed at the water outlet to allow the clear liquid to overflow, and a drain valve (2-3) is installed at the bottom.

5. The PTFE dual-membrane coupled hardening and ammonia removal system for gasification ash water treatment according to claim 1, characterized in that: Part of the concentrate from the PTFE ultrafiltration membrane (4) is returned to the high-density tank (1).

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