Skid-mounted ammonia-nitrogen wastewater treatment system and method

Abstract

The skid-mounted ammonia-nitrogen wastewater treatment system comprises a feeding pump, a preheater, a kettle liquid pump, an ammonia still, an ammonia water storage tank and an ammonia water pump, the input end of the feeding pump is connected with a feeding port, the output end of the feeding pump is connected with a cold end inlet of the preheater through a pipeline, and a cold end outlet of the preheater is connected with the middle of the ammonia still through a pipeline; a kettle outlet of the ammonia still is connected with a kettle liquid pump through a pipeline, an outlet of the kettle liquid pump is connected with a hot end inlet of a preheater, a hot end outlet of the preheater is connected with a waste liquid discharge port, a middle liquid outlet of the ammonia still is connected with a top liquid inlet of an ammonia water storage tank, and a bottom liquid outlet of the ammonia water storage tank is connected with an ammonia water pump through a pipeline. The system is arranged on the skid-mounted platform to achieve the effect of facilitating installation, is compact in structural arrangement, short in construction period, flexible to install and convenient to install, move and transport, and utilizes redundant heat of ammonia still liquid to preheat raw material liquid and improve the heat utilization efficiency, so that the efficiency of the device is improved, and the operation energy consumption of the equipment is reduced.

Description

Technical Field

[0001] The present invention relates to the field of wastewater treatment, and in particular to a skid-mounted ammonia nitrogen wastewater treatment system and method. Background Art

[0002] High-concentration ammonia nitrogen wastewater has a wide range of sources and a large amount of discharge. For example, fertilizers, coking, petrochemicals, pharmaceuticals, food, landfills, etc. all produce a large amount of high-concentration ammonia nitrogen wastewater. This type of wastewater discharged into water bodies not only causes eutrophication of water bodies and causes black and smelly water bodies, but also increases the difficulty and cost of water treatment, and even has toxic effects on humans and organisms. Therefore, research on ammonia nitrogen wastewater emission reduction and resource utilization technology is of great significance for ammonia nitrogen wastewater treatment and standard discharge.

[0003] Commonly used industrial ammonia nitrogen wastewater treatment methods include biological method, chemical precipitation method, breakpoint chlorination method, ion exchange method, membrane absorption method and stripping method. At present, there are also studies on the extraction of ammonia water from ammonia nitrogen wastewater using an ammonia evaporation tower. The ammonia evaporation tower is subordinate to the desorption tower. It is an operating equipment that releases the free ammonia dissolved in the liquid phase through the heat transfer of the heat carrier. Generally, water vapor is used as a heating agent to make the equilibrium vapor pressure of ammonia above the water surface greater than the partial pressure of ammonia in the heat carrier. The vapor and liquid phases are in countercurrent contact to transfer mass and heat, so that ammonia is released from the liquid phase. A mixture of ammonia vapor and water vapor is obtained at the top of the tower, and a liquid phase with ammonia nitrogen removed is obtained at the bottom of the tower. In the traditional ammonia evaporation system, ammonia is difficult to be completely condensed at the top of the ammonia evaporation tower, resulting in a pressure build-up at the top of the tower. Sometimes the ammonia has to be vented and discharged in excess of the standard. At the same time, the overall structure of the ammonia evaporation system is complex, the floor space is large, the installation and construction process is relatively complex, the installation work is cumbersome, and there is a problem of inconvenient installation.

[0004] To this end, the present invention proposes a skid-mounted ammonia nitrogen wastewater treatment system and method, which has the characteristics of compact structure, short construction period, flexible installation, and easy installation and mobile transportation. Summary of the invention

[0005] In view of the problems existing in the prior art, the purpose of the present invention is to provide a skid-mounted ammonia nitrogen wastewater treatment system and method to solve the problem that ammonia gas at the top of the ammonia evaporation tower cannot be completely condensed, and to improve the shortcomings of the traditional ammonia evaporation system with complex overall structure and complex installation and construction process.

[0006] To achieve the above object, the present invention provides the following technical solutions: A skid-mounted ammonia nitrogen wastewater treatment system comprises a feed pump, a preheater, a kettle liquid pump, an ammonia still, an ammonia water storage tank and an ammonia water pump, wherein the feed pump input end is connected to a feed port, the feed pump output end is connected to a cold end inlet of a preheater through a pipeline, the cold end outlet of the preheater is connected to a middle part of an ammonia still through a pipeline, the kettle outlet of the ammonia still is connected to a kettle liquid pump through a pipeline, the kettle liquid pump outlet is connected to a hot end inlet of a preheater, the hot end outlet of the preheater is connected to a waste liquid discharge port, the liquid outlet in the middle part of the ammonia still is connected to the liquid inlet at the top of an ammonia water storage tank, and the liquid outlet at the bottom of the ammonia water storage tank is connected to the ammonia water pump through a pipeline.

[0007] Furthermore, a washing section, a condensing section, a rectifying section and a stripping section are sequentially arranged in the ammonia evaporation tower from top to bottom. A washing liquid feed inlet is provided at the top of the washing section, and a washing liquid outlet is provided at the bottom of the washing section.

[0008] Furthermore, the condensation section is provided with a condenser, and the rectification section and the stripping section are of combined type, packed type or tray type.

[0009] Furthermore, the washing liquid is pure water or an acidic liquid.

[0010] Furthermore, a water vapor feed port is provided at the lower portion of the ammonia distillation tower.

[0011] Furthermore, it comprises a skid-mounted platform, and the system is installed on the skid-mounted platform.

[0012] The present invention provides a method for treating ammonia nitrogen wastewater by using the skid-mounted ammonia nitrogen wastewater treatment system, comprising the following steps: First, the ammonia nitrogen-containing wastewater generated during the production process enters the raw material preheater for preheating through the feed pump, and enters the ammonia evaporation tower after heat exchange. After the wastewater enters the ammonia evaporation tower, due to the greater volatility of ammonia than water, the ammonia in the wastewater is converted into a gas phase under the action of steam; in the ammonia evaporation tower, after multiple gas-liquid phase equilibriums, the ammonia concentration in the gas phase reaches the designed concentration requirement, and enters the internal reflux condenser for liquefaction. Part of the liquefied ammonia water is transported to the ammonia water storage tank as a product, and part of it is refluxed into the ammonia evaporation tower to participate in the gas-liquid phase equilibrium in the tower again; as the ammonia continues to evaporate, the ammonia content in the liquid in the ammonia evaporation tower gradually decreases. When the ammonia content in the liquid has reached the environmental emission requirements, the liquid discharged from the water outlet of the ammonia evaporation tower passes through the raw material preheater, exchanges heat with the wastewater before entering the ammonia evaporation tower, and the raw material preheater outlet is discharged; a washing section is set at the top of the ammonia evaporation tower to wash the gas that has not been completely condensed after passing through the condenser, and the treated tail gas is discharged in compliance with the standards.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1) The ammonia nitrogen wastewater generated in the production process of the present invention enters the raw material preheater for preheating through the feed pump, and enters the ammonia evaporation tower after heat exchange. After the wastewater enters the ammonia evaporation tower, because the volatility of ammonia is greater than that of water, under the action of steam, the ammonia in the wastewater is converted into a gas phase. In the ammonia evaporation tower, after multiple gas-liquid phase equilibriums, the ammonia concentration in the gas phase reaches the designed concentration requirement, and enters the internal reflux condenser for liquefaction. Part of the liquefied ammonia water is transported to the ammonia water storage tank as a product, and part of it is refluxed into the ammonia evaporation tower to participate in the gas-liquid phase equilibrium in the tower again; the liquid in the ammonia evaporation tower, as ammonia continues to evaporate, the ammonia content in the liquid gradually decreases. When the ammonia content in the liquid has reached the environmental emission requirements, the liquid discharged from the water outlet of the ammonia evaporation tower passes through the raw material preheater, and heat is exchanged with the wastewater before entering the ammonia evaporation tower, and the raw material preheater outlet is discharged. A washing section is set at the top of the ammonia evaporation tower to wash the gas that has not been completely condensed after passing through the condenser, and the treated tail gas is discharged in compliance with the standards; 2) The skid-mounted ammonia nitrogen wastewater treatment system of the present invention arranges the washing section, condensing section, rectifying section and stripping section in the ammonia still tower, thereby solving the problem of excessive discharge caused by pressure buildup in the top condenser of the conventional ammonia still tower, reducing the ammonia nitrogen content in the tail gas, making the overall layout of the skid compact, reducing the overall footprint of the wastewater treatment equipment, shortening the project construction period, and realizing the integrated layout of the ammonia still tower; 3) The skid-mounted ammonia nitrogen wastewater treatment system of the present invention is arranged on a skid-mounted platform to facilitate installation. The entire device can be completely skid-mounted and installed only by connecting it to the wastewater pipeline to be treated. The structure is compact, the construction period is short, the installation is flexible, and it is easy to install and move and transport. The excess heat of the ammonia still liquid is used to preheat the raw material liquid, thereby improving the heat utilization efficiency, thereby improving the efficiency of the device and reducing the energy consumption of equipment operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the overall structure of the system of the present invention.

[0015] In the figure: 1. Feed pump; 2. Preheater; 3. Kettle liquid pump; 4. Ammonia distillation tower; 5. Ammonia water storage tank; 6. Ammonia water pump; A. Wastewater containing ammonia nitrogen; B. Water vapor; C. Deammoniation wastewater; D. Circulating water; E. Washing liquid; F. Tail gas. DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to the described scope.

[0017] Please refer to Figure 1A skid-mounted ammonia nitrogen wastewater treatment system comprises a feed pump 1, a preheater 2, a kettle liquid pump 3, an ammonia still 4, an ammonia water storage tank 5 and an ammonia water pump 6, wherein the input end of the feed pump 1 is connected to the feed port, the output end of the feed pump 1 is connected to the cold end inlet of the preheater 2 through a pipeline, the cold end outlet of the preheater 2 is connected to the middle of the ammonia still 4 through a pipeline, the kettle outlet of the ammonia still 4 is connected to the kettle liquid pump 3 through a pipeline, the outlet of the kettle liquid pump 3 is connected to the hot end inlet of the preheater 2, the hot end outlet of the preheater 2 is connected to the waste liquid discharge port, the hot end outlet of the preheater 2 discharges the deammoniation wastewater C, the liquid outlet in the middle of the ammonia still 4 is connected to the liquid inlet at the top of the ammonia water storage tank 5, and the liquid outlet at the bottom of the ammonia water storage tank 5 is connected to the ammonia water pump 6 through a pipeline.

[0018] A washing section, a condensing section, a rectifying section and a stripping section are arranged in sequence from top to bottom in the ammonia distillation tower 4. A washing liquid feed inlet is provided at the upper portion of the washing section, and a washing liquid outlet is provided at the lower portion of the washing section.

[0019] The condensation section is provided with a condenser, and the condensation section is provided with circulating water D. The rectification section and the stripping section are of combined type, packed type or tray type.

[0020] In this embodiment, the washing liquid E is pure water or an acidic liquid.

[0021] A water vapor feed port is provided at the lower part of the ammonia distillation tower 4, and water vapor B provides a heat source for the ammonia distillation tower.

[0022] In this embodiment, a skid-mounted platform is included, and the system of the present invention is installed on the skid-mounted platform, so that the equipment is convenient to transport, carry and install.

[0023] The method for treating ammonia nitrogen wastewater by using a skid-mounted ammonia nitrogen wastewater treatment system of the present invention comprises the following steps: First, the ammonia nitrogen-containing wastewater A generated in the production process enters the raw material preheater 2 for preheating through the feed pump 1, and enters the ammonia evaporation tower 4 after heat exchange. After the wastewater enters the ammonia evaporation tower 4, since the volatility of ammonia is greater than that of water, under the action of water vapor B, the ammonia in the wastewater is converted into a gas phase state; in the ammonia evaporation tower 4, after multiple gas-liquid phase equilibriums, the ammonia concentration in the gas phase reaches the designed concentration requirement, and enters the internal reflux condenser for liquefaction. Part of the liquefied ammonia water is transported to the ammonia water storage tank 5 as a product, and part is transported to the ammonia water storage tank 5 as a product. It flows back to the ammonia evaporation tower 4 and participates in the gas-liquid phase equilibrium in the tower again; the ammonia content in the liquid in the ammonia evaporation tower 4 gradually decreases as the ammonia continues to evaporate. When the ammonia content in the liquid has reached the environmental emission requirements, the liquid discharged from the water outlet of the ammonia evaporation tower 4 passes through the raw material preheater 2, exchanges heat with the wastewater before entering the ammonia evaporation tower 4, and the effluent of the raw material preheater 2 is discharged; a washing section is set at the top of the ammonia evaporation tower 4 to wash the gas that has not been completely condensed after passing through the condenser, and the treated tail gas F is discharged in compliance with the standards. Example 1

[0024] The wastewater treatment system provided in Example 1 is used to treat ammonia nitrogen wastewater discharged by a certain enterprise, and the treatment method specifically includes the following steps: The ammonia nitrogen content in the ammonia nitrogen wastewater generated during the production process is 1000~2000mg / L. 3 / d of flow rate flows into feed pump 1, feed pump 1 sends wastewater into preheater 2, and the temperature is raised to 99℃, and then sent to ammonia evaporation tower 4. Steam with a pressure of 0.5MPa enters ammonia evaporation tower 4 from the steam inlet, and contacts with wastewater in countercurrent at the filler, so that the ammonia in the wastewater is converted into gas phase. After multiple gas-liquid phase equilibriums, the ammonia vapor enters the condensation section for condensation. Ammonia water with a temperature of 55℃ is partially transported to ammonia water storage tank 5 as a product, and a part of it flows back to ammonia evaporation tower 4 to participate in the gas-liquid phase equilibrium in the tower again.

[0025] The 100°C wastewater at the bottom of the ammonia distillation tower 4 is sent to the preheater 2 through the kettle liquid pump 3 to exchange heat with the feed wastewater. After the temperature drops to 35°C, the wastewater is discharged after being tested to meet the emission standards. The steam that is not completely condensed in the condensation section enters the washing section for washing treatment, and the tail gas after washing treatment meets the emission standards. After the wastewater is treated, the ammonia concentration and the ammonia nitrogen content in the treated wastewater are tested. The product ammonia concentration is 10%, the ammonia nitrogen content in the treated wastewater is 14 mg / L, and the ammonia recovery rate is 99%.

Claims

1. A skid-mounted ammonia nitrogen wastewater treatment system, characterized in that The invention comprises a feed pump (1), a preheater (2), a kettle liquid pump (3), an ammonia still (4), an ammonia water storage tank (5) and an ammonia water pump (6), wherein the input end of the feed pump (1) is connected to the feed port, the output end of the feed pump (1) is connected to the cold end inlet of the preheater (2) through a pipeline, the cold end outlet of the preheater (2) is connected to the middle of the ammonia still (4) through a pipeline, the kettle outlet of the ammonia still (4) is connected to the kettle liquid pump (3) through a pipeline, the kettle liquid pump (3) outlet is connected to the hot end inlet of the preheater (2), the hot end outlet of the preheater (2) is connected to the waste liquid discharge port, the liquid outlet in the middle of the ammonia still (4) is connected to the liquid inlet at the top of the ammonia water storage tank (5), and the liquid outlet at the bottom of the ammonia water storage tank (5) is connected to the ammonia water pump (6) through a pipeline.

2. A skid-mounted ammonia nitrogen wastewater treatment system according to claim 1, characterized in that The ammonia distillation tower (4) is provided with a washing section, a condensing section, a rectifying section and a stripping section in order from top to bottom. The upper portion of the washing section is provided with a washing liquid feed inlet, and the lower portion of the washing section is provided with a washing liquid outlet.

3. A skid-mounted ammonia nitrogen wastewater treatment system according to claim 2, characterized in that The condensation section is provided with a condenser, and the rectification section and the stripping section are of a combined type, a packed type or a tray type.

4. A skid-mounted ammonia nitrogen wastewater treatment system according to claim 2, characterized in that The washing liquid is pure water or acidic liquid.

5. The skid-mounted ammonia nitrogen wastewater treatment system according to claim 2 is characterized in that A water vapor feed inlet is provided at the lower portion of the ammonia distillation tower (4).

6. The skid-mounted ammonia nitrogen wastewater treatment system according to claim 2 is characterized in that It comprises a skid-mounted platform, on which the system is installed.

7. A method for treating ammonia nitrogen wastewater using the skid-mounted ammonia nitrogen wastewater treatment system according to any one of claims 1 to 6, characterized in that The steps include: First, the ammonia nitrogen-containing wastewater (A) generated during the production process enters the raw material preheater (2) for preheating through the feed pump (1), and then enters the ammonia evaporation tower (4) after heat exchange. After the wastewater enters the ammonia evaporation tower (4), the ammonia in the wastewater is converted into a gas phase under the action of steam because the volatility of ammonia is greater than that of water. In the ammonia evaporation tower (4), after multiple gas-liquid phase equilibriums, the ammonia concentration in the gas phase reaches the designed concentration requirement, and then enters the internal reflux condenser for liquefaction. Part of the liquefied ammonia water is transported to the ammonia water storage tank (5) as a product, and part is returned to the ammonia evaporation tower (5). The wastewater flows into the ammonia evaporation tower (4) and participates in the gas-liquid phase equilibrium in the tower again. As the ammonia evaporates continuously, the ammonia content in the liquid in the ammonia evaporation tower (4) gradually decreases. When the ammonia content in the liquid reaches the environmental emission requirements, the liquid discharged from the water outlet of the ammonia evaporation tower (4) passes through the raw material preheater (2) and exchanges heat with the wastewater before entering the ammonia evaporation tower (4). The wastewater from the raw material preheater (2) is discharged. A washing section is provided at the top of the ammonia evaporation tower (4) to wash the gas that has not been completely condensed after passing through the condenser, and the treated tail gas is discharged in compliance with the emission standards.

Images