Wastewater treatment method and apparatus based on hydrate-based water vapor adsorption

Patent metadata

Field	Value
Publication number	US-11926538-B2
Application number	US-202318315484-A
Country	US
Kind code	B2
Filing date	May 10, 2023
Priority date	May 13, 2022
Publication date	Mar 12, 2024
Grant date	Mar 12, 2024

Abstract

The present disclosure relates to the technical field of wastewater treatment, and provides a wastewater treatment method and apparatus based on hydrate-based water vapor adsorption. The apparatus includes a wastewater evaporation zone, a hydrate formation zone, a hydrate decomposition zone, and a data acquisition and control system. Rising water vapor and condensed water formed during evaporation of wastewater at normal temperature react with a hydrate former on a cooling wall surface to form a hydrate, continuous evaporation of the wastewater is promoted, the hydrate is scraped off to a collecting zone below by a scraper after being formed, and the hydrate is decomposed into fresh water, thereby realizing wastewater treatment. The present disclosure provides a method for treating complex wastewater containing a plurality of pollutants, where water vapor is consumed to form the hydrate to promote wastewater evaporation, and water obtained from the decomposition does not contain pollutants theoretically.

First claim

What is claimed is:

1. A wastewater treatment apparatus based on hydrate-based water vapor adsorption, comprising: a wastewater evaporation zone, a hydrate formation zone, a hydrate decomposition zone, and a data acquisition and control system, wherein
the wastewater evaporation zone comprises a reactor, a magnetic stirrer, a waste liquid tank, and a wastewater storage tank; the reactor is divided into a wastewater evaporation chamber and a hydrate formation and decomposition chamber; an upper part of the wastewater evaporation chamber is communicated with an upper part of the hydrate formation and decomposition chamber; the wastewater storage tank is connected to the wastewater evaporation chamber of the reactor; the magnetic stirrer is arranged in the wastewater evaporation chamber; a bottom of the wastewater evaporation chamber is connected to the waste liquid tank;
the hydrate formation zone comprises a wall scraping device, a cooling wall surface, a gas cylinder, a pressure sensor, and a temperature sensor; the gas cylinder is connected to the reactor; the pressure sensor and the temperature sensor are arranged in the reactor to monitor a reaction environment in the hydrate formation and decomposition chamber; the wall scraping device is arranged in the reactor to act on the cooling wall surface and is configured to scrape off a hydrate crystal formed by water vapor and condensed water of the water vapor with a gaseous hydrate former on the cooling wall surface;
the hydrate decomposition zone comprises the hydrate formation and decomposition chamber of the reactor, a fresh water tank, and a gas recovery device; the hydrate crystal scraped off by the wall scraping device falls to a bottom of the hydrate formation and decomposition chamber of the reactor; the gas recovery device is connected to the hydrate formation and decomposition chamber and is configured to collect the gaseous hydrate former after decomposition of the hydrate crystal to achieve recycling of the gaseous hydrate former; the fresh water tank is connected to the bottom of the hydrate formation and decomposition chamber and is configured to collect fresh water after the decomposition of the hydrate crystal; and
the data acquisition and control system comprises a data acquisition device and a computer control system; the pressure sensor and the temperature sensor in the reactor are connected to the data acquisition device to detect pressure and temperature changes in a wastewater treatment process inside the reactor; and the computer control system controls a wall scraping motion of the wall scraping device and a temperature adjustment of the cooling wall surface.

2. The wastewater treatment apparatus based on the hydrate-based water vapor adsorption according to claim 1 , wherein the wall scraping device comprises a motor, a telescopic rod, and a scraper; the motor is mounted in the reactor and is connected to the telescopic rod to control the scraper to move on an inner wall of the reactor; and a length of the telescopic rod is adjustable according to a position change, so that the scraper vertically moves along the cooling wall surface and scrapes off the hydrate crystal formed by the water vapor and the condensed water of the water vapor with the gaseous hydrate former on the cooling wall surface.

3. The wastewater treatment apparatus based on the hydrate-based water vapor adsorption according to claim 1 , wherein the cooling wall surface is cooled by a cooling coil pipe to form a wall surface environment suitable for hydrate formation.

4. The wastewater treatment apparatus based on the hydrate-based water vapor adsorption according to claim 1 , wherein a main body part of the reactor is made of stainless steel and is configured for bearing a pressure of 10 MPa.

5. The wastewater treatment apparatus based on the hydrate-based water vapor adsorption according to claim 3 , wherein an outer sidewall of the reactor corresponding to the cooling coil pipe is made of a high-pressure-resistant thermal insulation material having a thermal conductivity of less than 0.25 W/(m·K) to connect to other outer sidewall surfaces, to reduce a loss of cold energy.

6. A method of using the wastewater treatment apparatus based on the hydrate-based water vapor adsorption according to claim 1 , comprising the following steps:
step 1: wastewater intake: conveying wastewater in the wastewater storage tank into the reactor until a volume of the wastewater conveyed reaches a volume of wastewater to be treated in one batch;
step 2: gas introduction: introducing the gaseous hydrate former at a high pressure in the gas cylinder into the reactor until a pressure in the reactor reaches a pressure required for wastewater treatment;
step 3: reaction: reducing a temperature of the cooling wall surface to a temperature required for the reaction, and turning on the magnetic stirrer to accelerate an evaporation of the wastewater; rising the water vapor and the condensed water formed during the evaporation reacting with the gaseous hydrate former to form a hydrate crystal as a solid on the cooling wall surface, and promoting a continuous evaporation of the wastewater by consuming the water vapor through the reaction;
step 4: separation: as the hydrate crystal formed on the cooling wall surface continuously accumulates and thickens, turning on the wall scraping device to scrape off the hydrate crystal formed on the cooling wall surface; periodically turning on and off the wall scraping device by the computer control system to periodically scrape off the hydrate crystal formed on the cooling wall surface until one batch of the wastewater treatment is completed;
step 5: decomposition: the hydrate crystal which is scraped off falling to the bottom of the hydrate formation and decomposition chamber of the reactor, and the hydrate crystal being rapidly decomposed into a gas and fresh water at normal temperature; collecting the gas released from the decomposition of the hydrate crystal to the gas recovery device, and recycling the gas after purification; the fresh water obtained through the decomposition of the hydrate crystal flowing to the fresh water tank; conveying remaining concentrated wastewater at the bottom of the wastewater evaporation chamber of the reactor to the waste liquid tank; and
step 6: cycling: after the hydrate crystal is completely decomposed, the one batch of the wastewater treatment is completed, closing all valves, and repeating the steps 1 to 5 to realize continuous wastewater treatment.

7. The method according to claim 6 , wherein the gaseous hydrate former is a gas molecule that generates a hydrate phase equilibrium pressure of 0.1 MPa to 10 MPa at a reaction temperature of 2° C. to 8° C.

8. The method according to claim 6 , wherein the gaseous hydrate former is one or both of carbon dioxide and propane.

9. The method according to claim 6 , wherein the wastewater conveyed into the reactor for the wastewater treatment is complex wastewater containing a plurality of pollutants, a temperature of the wastewater is 20° C. to 25° C., a flow rate of the wastewater is controlled at 1.0 m/s to 3.0 m/s, and the volume of the wastewater conveyed is 70% to 80% of a volume of the wastewater evaporation zone of the reactor.

10. The method according to claim 6 , wherein a stirring speed of the magnetic stirrer is controlled at 400 rpm to 800 rpm to increase a speed of the evaporation of the wastewater; the temperature of the cooling wall surface is adjusted according to a concentration of the wastewater treated, and the temperature is controlled at 2° C. to 8° C., the temperature and the pressure are controlled to be above a hydrate phase equilibrium curve; and the gaseous hydrate former

Assignees

• Univ Dalian Tech

Inventors

• Song Yongchen
• Zhang Lunxiang
• Sun Huilian
• Ling Zheng
• Zhao Jiafei
• Sun Lingjie
• Yang Lei
• Yang Mingjun
• Liu Yu
• Liu Weiguo
• Li Yanghui
• Sun Xiang
• Jiang Lanlan

Classifications

• C02F1/048 Primary

  Purification of waste water by evaporation · CPC title

• B01D1/30

  Accessories for evaporators {; Constructional details thereof} · CPC title

• B01D5/0006

  Coils or serpentines · CPC title

• B01D5/0051

  Regulation processes; Control systems, e.g. valves · CPC title

• B01D5/006

  with evaporation or distillation · CPC title