CN104803465A - Device and method for reducing pH value of alkaline ammonia-containing sewage by use of flue gases - Google Patents

Abstract

The invention provides a device and method for reducing the pH value of alkaline ammonia-containing sewage by using flue gas. The device includes a reaction chamber, the two sides of the reaction chamber are respectively provided with gas and water inlets and outlets, the bottom is provided with a tailings outlet valve, and an ultrasonic atomizing sheet and a demister are installed in the reaction chamber. Its working process includes that the sewage entering the reaction chamber is submerged in the ultrasonic atomizing sheet, and is atomized by the ultrasonic atomizing sheet. The mist reacts with the flue gas, absorbs carbon dioxide in the flue gas and interacts with the ammonia component in the sewage. Reaction, the tailings outlet valve discharges the deposited solid impurities. The feature of the present invention is that the natural flow of the gas phase and the liquid phase is adopted, and the absorption and reaction between the gas and the liquid can be strengthened simply by using the atomizing sheet, which makes the device structure simple, easy to clean and maintain, and can be operated under normal pressure, and the gas The liquid flow is easy to regulate, easy to control and use; the scale of the device is flexible, and the gas-liquid processing capacity can be expanded by connecting in series or in parallel.

Description

Device and method for reducing pH value of alkaline ammonia-containing sewage by using flue gas

technical field

The invention relates to waste gas and waste water treatment technology, in particular to a device and method for reducing the pH value of alkaline ammonia-containing sewage by using flue gas.

Background technique

According to the comprehensive sewage discharge standard (GB8978-1996), the pH value of sewage discharge is required to be controlled at 6-9. However, many ammonia-containing wastewaters, including some ammonia-nitrogen wastewaters, often have a pH value higher than this value. Ammonia nitrogen wastewater is one of the wastes with large discharge in industrial production. Generally, the main source of ammonia nitrogen in wastewater with a pH value above 7 is the joint action of inorganic ammonia and ammonia water. The ammonia nitrogen in wastewater with a pH value below 7 is mainly derived from inorganic ammonia. . At present, reducing the pH value of alkaline ammonia-containing sewage mainly depends on the consumption of sulfuric acid and hydrochloric acid, and the cost of the treatment process is relatively high. It has been reported that carbon dioxide can be used to lower the pH of alkaline wastewater without introducing new refractory ions into the wastewater. A typical carbon dioxide treatment system is to vaporize liquid carbon dioxide through a vaporizer and spray it into wastewater under a suitable pressure. Since carbon dioxide needs to be liquefied by cooling and pressurizing, the operation is relatively cumbersome. At the same time, flue gas and alkaline ammonia nitrogen sewage are wastes that are difficult to treat, and the flue gas after desulfurization and cooling can be considered to reduce the pH value of sewage. Flue gas contains a large amount of carbon dioxide gas, which can be absorbed by aqueous solution, such as alcohol amine and other solutions, and spraying method is used to enhance the gas-liquid absorption rate, but the required equipment structure is often complicated.

In short, most of the waste gas or wastewater treatment devices based on gas-liquid contact absorption are vertical or tower structures, some of which need to pressurize the intake air, and the structure and operation of the devices are relatively complicated. According to these technical conditions, it is possible to consider designing a gas-liquid contact absorption device with a simple structure, so as to speed up the gas-liquid absorption and reaction rate.

Contents of the invention

The object of the present invention is to provide a kind of device and method that utilizes flue gas to reduce the pH value of alkaline ammoniacal sewage, can utilize the carbon dioxide contained in the flue gas after a certain degree of cooling and the alkaline ammoniacal sewage The ammonia components react with each other to lower the pH of the sewage.

The present invention is realized through the following technical solutions.

A kind of device that utilizes flue gas to reduce the pH value of alkaline ammonia-containing sewage provided by the present invention, this device comprises a reaction chamber 1, and one side of reaction chamber 1 is provided with gas inlet 8 and water outlet 7 from top to bottom, The other side of the reaction chamber 1 is provided with a gas outlet 3 and a water inlet 4 from top to bottom, and the bottom of the reaction chamber 1 is provided with a tailings outlet valve 6; A demister 2 is installed in the chamber 1 close to the gas outlet 3 .

The above-mentioned device for reducing the pH value of alkaline ammonia-containing sewage by using flue gas, its demister 2 is a wire mesh demister.

The above-mentioned device for reducing the pH value of alkaline ammonia-containing sewage by using flue gas can expand the gas-liquid treatment capacity by connecting multiple devices in parallel or in series.

A kind of method that utilizes flue gas to reduce the pH value of alkaline ammonia-containing sewage provided by the invention, adopts above-mentioned device, comprises the steps:

a) Ammonia-containing sewage enters the reaction chamber 1 from the water inlet 4, so that the ultrasonic atomizing sheet 5 is immersed in the sewage;

b) Turn on the ultrasonic atomizing sheet 5 to atomize the sewage, and the mist droplets fill the space above the liquid level of the sewage in the inner cavity of the reaction chamber 1;

c) The flue gas enters the reaction chamber 1 from the gas inlet 8, flows through the inner cavity of the reaction chamber 1 and passes through the demister 2, and then is discharged from the gas outlet 3;

d) After the sewage flows through the inner cavity of the reaction chamber 1, it is discharged from the water outlet 7;

e) The tailings formed by the deposition of impurities in the sewage are discharged through the tailings outlet valve 6 .

The initial pH value of the sewage entering the reaction chamber 1 in the above step a) should be greater than 7.

The initial temperature of the flue gas entering the reaction chamber 1 in step c) above should be lower than 95°C.

The device of the present invention has a simple structure, utilizes the interaction between the flue gas and the ammonia-containing sewage to make the carbon dioxide in the flue gas react with the ammonia in the sewage, thereby reducing the content of the ammonia component in the ammonia-containing sewage, thereby reducing The pH value of the sewage is improved; at the same time, the carbon dioxide in the flue gas is absorbed to achieve the goal of low-carbon emission reduction. The use of ultrasonic atomization sheets also strengthens the efficiency of gas-liquid contact and reaction absorption. The feature of the present invention is that the device adopts the natural flow of gas phase and liquid phase, and the absorption and reaction of gas and liquid can be strengthened simply by using an atomized sheet at the bottom of the device, which makes the device simple in structure, can be operated under normal pressure, and is convenient for cleaning and maintenance , and the gas-liquid flow is easy to regulate, easy to control and use; the scale of the device is flexible, and the gas-liquid processing capacity can be expanded through series or parallel connection. In summary, the present invention is simple and efficient, has obvious advantages in emission reduction, and has broad application prospects.

Description of drawings

Fig. 1 is a schematic diagram of the device of the present invention.

In the figure: 1 - reaction chamber; 2 - demister; 3 - gas outlet; 4 - water inlet; 5 - ultrasonic atomization sheet; 6 - tailings outlet valve; 7 - water outlet; 8 - gas inlet. the

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and through specific embodiments.

Example 1:

The device that adopts is as shown in Figure 1, and this device comprises a reaction chamber 1, is provided with gas inlet 8 and water outlet 7 from top to bottom on one side of reaction chamber 1, on the other side of reaction chamber 1 from top to bottom A gas outlet 3 and a water inlet 4 are provided, and a tailings outlet valve 6 is provided at the bottom of the reaction chamber 1; an ultrasonic atomization sheet 5 is installed below the chamber 1, and a valve is installed near the gas outlet 3 in the chamber 1 Demister 2.

Adopt above-mentioned device, utilize flue gas to reduce the method for alkaline ammoniacal sewage pH value, comprise the steps:

a) Ammonia-containing sewage enters the reaction chamber 1 from the water inlet 4, so that the ultrasonic atomizing sheet 5 is immersed in the sewage;

b) Turn on the ultrasonic atomizing sheet 5 to atomize the sewage, and the mist droplets fill the space above the liquid level of the sewage in the inner cavity of the reaction chamber 1;

c) The flue gas enters the reaction chamber 1 from the gas inlet 8, flows through the inner cavity of the reaction chamber 1 and passes through the demister 2, and then is discharged from the gas outlet 3;

d) After the sewage flows through the inner cavity of the reaction chamber 1, it is discharged from the water outlet 7;

e) The tailings formed by the deposition of impurities in the sewage can be discharged through the tailings outlet valve 6 irregularly.

The size of the reaction chamber 1 described in this embodiment is 0.1 meters wide, 1 meter long, and 0.5 meters high, and the demister 2 is a wire mesh demister; the temperature of the feed flue gas is 50 ° C, and the flow rate is 40 L /min, the volume content of carbon dioxide is 3.88%; the temperature of the feed alkaline ammonia-containing sewage is 25°C, the pH value is 10.5, the flow rate is 2L/min, and the mass content of ammonia is 0.03%; in the inner cavity of reaction chamber 1 Among them, the height of the liquid level line of the sewage is 0.2 meters; the ultrasonic atomizing sheets 5 installed under the inner cavity of the reaction chamber 1 are arranged along the central axis of the inner cavity, and a total of 9 pieces are installed, and the distance between the centers of each other is 10cm. The diameter of piece 5 is 25mm, the resonant frequency is 1.7MHz, and the power is 25W; the sewage is atomized by the ultrasonic atomizing piece in the reaction chamber 1, and the carbon dioxide in the flue gas is absorbed by the sewage droplets and combined with the ammonia component in the water Reaction with each other, after the sewage flows out from the water outlet 7, its pH value drops to 6.90, and the effect of reducing the pH value is obvious.

Example 2

The device and work flow are the same as in Example 1, except that the feed alkaline ammonia-containing sewage is ammonia-nitrogen sewage containing organic matter such as phenol, cyanide, and sulfide, the pH value is 9.90, and the mass content of free ammonia is 0.03%; After the sewage flows out from the water outlet 7, its pH value drops to 8.50, the free ammonia component in the sewage can no longer be detected, and the treatment effect is obvious.

Example 3

The working process is the same as in Example 1, except that the two devices are connected in series, so as to expand the gas-liquid treatment capacity, the flow rate of the feed flue gas is 80L/min, and the flow rate of the feed alkaline ammoniacal sewage is 4L/min. min; after the sewage flows out from the water outlet 7 of the second device connected in series, its pH value drops to 7.20, and the effect of reducing the pH value is obvious.

Example 4

The working process is the same as in Example 1, except that the two devices are connected in parallel to facilitate the expansion of the gas-liquid treatment capacity; the feed flue gas flow rate is 80L/min, and the feed alkaline ammonia-containing sewage flow rate is 4L/min. min; after the sewage flows out from the two parallel devices and is mixed, its pH value drops to 7.30, and the pH value reduction effect is obvious.

Claims (6)

1. a device that utilizes flue gas to reduce the pH value of alkaline ammonia-containing sewage, is characterized in that, comprises a reaction chamber (1), is provided with gas inlet (8) from top to bottom at the side of reaction chamber (1) ) and water outlet (7), the other side of the reaction chamber (1) is provided with a gas outlet (3) and a water inlet (4) from top to bottom, and the bottom of the reaction chamber (1) is provided with a tailings outlet valve (6) ; An ultrasonic atomizing sheet (5) is installed below the reaction chamber (1), and a demister (2) is installed near the gas outlet (3) in the reaction chamber (1). 2. The device for reducing the pH value of alkaline ammonia-containing sewage by utilizing flue gas as claimed in claim 1, wherein said demister (2) is a wire mesh demister. 3. The device for reducing the pH value of alkaline ammonia-containing sewage by utilizing flue gas as claimed in claim 1, wherein the device is a device composed of multiple devices connected in parallel or in series. 4. A method utilizing flue gas to reduce the pH value of alkaline ammonia-containing sewage, characterized in that, adopting the device described in claim 1 or 3, comprising the steps of: a) Ammonia-containing sewage enters the reaction chamber (1) from the water inlet (4), so that the ultrasonic atomizing sheet (5) is immersed in the sewage; b) Turn on the ultrasonic atomizing sheet (5) to atomize the sewage, and the mist droplets fill the space above the liquid level of the sewage in the inner cavity of the reaction chamber (1); c) The flue gas enters the reaction chamber (1) from the gas inlet (8), flows through the inner cavity of the reaction chamber (1) and passes through the demister (2), and then is discharged from the gas outlet (3); d) After the sewage flows through the inner cavity of the reaction chamber (1), it is discharged from the water outlet (7); e) The tailings formed by the deposition of impurities in the sewage are discharged through the tailings outlet valve (6). 5. A method for reducing the pH value of alkaline ammonia-containing sewage by utilizing flue gas as claimed in claim 4, wherein the initial pH value of the sewage entering the reaction chamber (1) in step a) is greater than 7. 6. a kind of method utilizing flue gas to reduce the pH value of alkaline ammonia-containing sewage as claimed in claim 4, is characterized in that, step c) the initial temperature of the flue gas that enters reaction chamber (1) is lower than 95 ℃ .