A new ammonia evaporation energy-saving process system

Abstract

The present application relates to the field of coking, synthetic ammonia and the like containing ammonia wastewater treatment, and discloses a novel ammonia evaporation energy-saving process system, a primary ammonia evaporation tower, an intermediate pressurizing pump set, a water flow regulating device, a secondary ammonia evaporation device, a flash tank, a steam ejector, a pressurizing pump set and a control unit. After the ammonia-containing wastewater is preliminarily treated by the primary ammonia evaporation tower, it is delivered to the secondary ammonia evaporation device by the pressurizing pump, and introduced into new steam for secondary ammonia evaporation. After the secondary ammonia evaporation, the wastewater flows into the flash tank to produce flash steam by cooling and pressure reduction, and the flash steam is pressurized by mixing with the new steam through the steam ejector, and then returns to the primary ammonia evaporation tower or the secondary ammonia evaporation device, so that the steam is recycled multiple times. The system can effectively reduce the new steam consumption by 35-45% under the premise of ensuring the stability of the ammonia nitrogen index of the effluent, improve the energy utilization rate, reduce carbon emissions, and is suitable for direct ammonia evaporation and indirect ammonia evaporation systems.

Description

A novel ammonia stripping energy-saving process system Technical Field

[0001] This invention relates to the field of ammonia-containing wastewater treatment in coking, ammonia synthesis, and other industries, and specifically to a novel energy-saving ammonia stripping process system. Background Technology

[0002] The ammonia stripping tower in a coking plant is a key environmental protection and resource recovery device. It is mainly used to remove ammonia nitrogen (NH3-N) from wastewater generated during the coking process, significantly reducing the ammonia nitrogen pollution load in the wastewater, creating conditions for subsequent biochemical treatment, and realizing the recovery and utilization of ammonia resources, thus possessing significant environmental and economic benefits. Its core step is steam stripping to volatilize ammonia.

[0003] Steam stripping mainly consumes water vapor. The current common consumption index of "steam (kg) / ammonia-containing wastewater (ton)" is 160-220 kg / t. Moreover, most of the consumed steam is carried away by the circulating cooling water, resulting in a great deal of energy waste.

[0004] However, most of the consumed steam is carried away by the cooling water system, resulting in serious energy waste, high operating costs, and large carbon emissions, which is inconsistent with the industry trend of energy conservation and carbon reduction. Therefore, an energy-saving process is needed to reduce steam consumption and improve energy utilization without large-scale modification of existing systems. To this end, we propose a new ammonia stripping energy-saving process system for new ammonia stripping systems or the renovation of existing ammonia stripping systems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a novel energy-saving ammonia stripping process system to solve the technical problems existing in the prior art.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0007] A novel ammonia stripping energy-saving system includes:

[0008] The original ammonia stripping tower was used to receive ammonia-containing wastewater and remove ammonia nitrogen through steam stripping.

[0009] An intermediate pressurization pump set is connected to the outlet of the original ammonia stripping tower and is used to pressurize and transport the ammonia stripping wastewater discharged from the original ammonia stripping tower.

[0010] A water flow regulating device is installed after the intermediate booster pump set to regulate the flow rate of ammonia wastewater entering the secondary ammonia stripping equipment. The water flow regulating device is a regulating valve or a frequency converter.

[0011] The secondary ammonia stripping equipment receives the regulated ammonia stripping wastewater and simultaneously introduces a fresh stream of steam to exchange heat with the ammonia stripping wastewater, allowing the residual ammonia nitrogen in the wastewater to be further stripped and precipitated. The steam and ammonia gas mixture discharged from the secondary ammonia stripping equipment is guided to subsequent use.

[0012] The flash tank is connected to the wastewater outlet of the secondary ammonia stripping equipment. It is used to receive the wastewater after the secondary ammonia stripping and to make it flash evaporate under cooling and depressurization conditions, so that the flash vapor is separated from the remaining wastewater.

[0013] A steam ejector has a flash steam inlet, a power steam inlet, and a mixed steam outlet. The flash steam inlet of the flash tank is connected to the flash tank, the power steam inlet is connected to the new steam supply pipeline, and the mixed steam outlet is connected to the original ammonia stripping tower or secondary ammonia stripping equipment. It is used to mix the flash steam with the new steam and then pressurize and deliver it to the system.

[0014] The booster pump set is used to transport the wastewater discharged from the flash tank to the original ammonia stripping tower or subsequent treatment unit;

[0015] The control unit is connected to the secondary ammonia stripping equipment, steam ejector, and water flow regulating device. It is used to regulate the operating pressure of the secondary ammonia stripping equipment, the operating temperature of the flash tank, the power steam pressure of the steam ejector, and the mixing ratio.

[0016] Preferably, the operating pressure of the secondary ammonia stripping equipment is 20-200 kPa, and the corresponding operating temperature is 104-133℃.

[0017] Preferably, the operating pressure of the secondary ammonia stripping equipment is higher than that of the original ammonia stripping tower, and the discharged mixed gas flow can directly enter the original ammonia stripping tower without pressurization or enter the original ammonia stripping tower after pressure reduction and adjustment.

[0018] Preferably, the secondary ammonia stripping equipment is a vertical tower-type equipment or a horizontal cylindrical equipment.

[0019] Preferably, the operating temperature of the flash tank is lower than the operating temperature of the secondary ammonia stripping equipment, with a temperature difference of 2°C to 30°C.

[0020] Preferably, the steam ejector is an adjustable ejector that can automatically adjust the injection ratio and injection intensity based on the flash steam pressure, the motive steam pressure and the system back pressure; the motive steam pressure of the steam ejector is not less than 0.2 MPa to ensure that the mixed steam has sufficient pressure to enter the original ammonia stripping tower or the secondary ammonia stripping equipment.

[0021] Preferably, the system further includes a compressor for pressurizing the flash steam generated by the flash tank to the pressure required by the system, in the case of an alternative or auxiliary steam ejector.

[0022] Preferably, the system is suitable for direct or indirect ammonia stripping processes. For indirect ammonia stripping systems, a steam generator with external steam as a heat source can be added to directly generate new steam from the ammonia stripping wastewater, thereby converting it into a direct ammonia stripping system.

[0023] The control unit regulates the steam flow and pressure in real time through regulating valves installed on the steam inlet pipeline, the ejector power steam inlet, and the water flow regulating device, so as to minimize steam consumption while ensuring that the ammonia nitrogen index of the effluent meets the requirements.

[0024] A novel energy-saving ammonia stripping system includes the following steps:

[0025] S1: The ammonia stripping wastewater discharged from the original ammonia stripping tower first enters the secondary ammonia stripping equipment;

[0026] S2: Simultaneously, a stream of steam is introduced into the secondary ammonia stripping equipment, where the ammonia-containing wastewater undergoes further ammonia stripping.

[0027] S3: The ammonia-containing wastewater discharged from the secondary ammonia stripping equipment enters the flash tank again, where the ammonia-stripping wastewater is cooled and depressurized to flash vapor.

[0028] S4: The flash vapor discharged from the flash tank is pressurized by the ejector or compressor and then enters the original ammonia stripping tower or secondary ammonia stripping equipment;

[0029] S5: The steam discharged from the secondary ammonia stripping equipment is then reintroduced into the original ammonia stripping tower, achieving secondary steam utilization.

[0030] In summary, the present invention has the following main beneficial effects:

[0031] By installing a secondary ammonia stripping unit in series after the original ammonia stripping tower, a fresh steam source is introduced to perform secondary ammonia stripping treatment on the wastewater. A flash tank is used to recover residual heat from the wastewater to generate flash steam, which is then mixed with the fresh steam and pressurized before being returned to the system using a steam ejector. This achieves multiple cycles of steam utilization. The overall process can reduce fresh steam consumption by approximately 35% to 45% while maintaining the same ammonia nitrogen levels in the effluent, significantly improving steam utilization and reducing energy consumption per unit of wastewater treatment.

[0032] The system described does not require large-scale replacement or modification of the existing ammonia stripping tower and supporting equipment. It only requires adding modules such as a secondary ammonia stripping unit, flash tank, and steam ejector to the existing process flow, and optimizing process parameters through the control unit to achieve energy-saving upgrades. This solution is applicable to direct ammonia stripping systems and can also be used to convert indirect ammonia stripping systems to direct ammonia stripping systems, demonstrating strong engineering adaptability and promotional value.

[0033] By recovering flash steam generated in flash tanks to replace part of the new steam, the demand for purchased steam and boiler load are reduced, thereby lowering overall energy consumption and carbon emissions and helping the company achieve its low-carbon production goals. The efficient recovery of wastewater heat not only reduces the burden on the cooling system but also optimizes the overall plant energy balance, balancing economic benefits with environmental protection.

[0034] The steam ejector used in this invention can be flexibly adjusted according to the flash steam pressure, flow rate, and system back pressure to ensure that the mixed steam meets the operating requirements of the original ammonia stripping tower or secondary ammonia stripping equipment. By adjusting the operating pressure, flow rate, and temperature of each component through the control unit, the system can adapt to different loads and operating conditions, achieving automated operation and improving process stability and ease of operation.

[0035] This system not only achieves significant energy conservation and consumption reduction goals, but also reduces steam purchase costs, wastewater treatment operating costs, and equipment maintenance costs caused by boiler load. At the same time, it reduces emission trading costs associated with carbon emission quotas, bringing significant direct and indirect economic benefits to enterprises. It has a short investment payback period and broad prospects for commercial application. Attached Figure Description

[0036] Figure 1 is a flowchart of the method of the present invention. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Example 1

[0039] Referring to Figure 1, a novel ammonia stripping energy-saving system includes:

[0040] The original ammonia stripping tower was used to receive ammonia-containing wastewater and remove ammonia nitrogen through steam stripping.

[0041] An intermediate pressurization pump set is connected to the outlet of the original ammonia stripping tower and is used to pressurize and transport the ammonia stripping wastewater discharged from the original ammonia stripping tower.

[0042] A water flow regulating device is installed after the intermediate booster pump set to regulate the flow rate of ammonia wastewater entering the secondary ammonia stripping equipment. The water flow regulating device is a regulating valve or a frequency converter.

[0043] The secondary ammonia stripping equipment receives ammonia stripping wastewater from the outlet of the regulating device, and simultaneously introduces a fresh stream of steam to exchange heat with the ammonia stripping wastewater, allowing residual ammonia nitrogen in the wastewater to be further stripped and precipitated. The steam and ammonia gas mixture discharged from the secondary ammonia stripping equipment is guided to subsequent use.

[0044] The flash tank is connected to the wastewater outlet of the secondary ammonia stripping equipment. It is used to receive the wastewater after the secondary ammonia stripping and to make it flash evaporate under cooling and depressurization conditions, so that the flash vapor is separated from the remaining wastewater.

[0045] A steam ejector has a flash steam inlet, a power steam inlet, and a mixed steam outlet. The flash steam inlet of the flash tank is connected to the flash tank, the power steam inlet is connected to the new steam supply pipeline, and the mixed steam outlet is connected to the original ammonia stripping tower or secondary ammonia stripping equipment. It is used to mix the flash steam with the new steam and then pressurize and deliver it to the system.

[0046] The booster pump set is used to transport the wastewater discharged from the flash tank to the original ammonia stripping tower or subsequent treatment unit;

[0047] The control unit is connected to the secondary ammonia stripping equipment, steam ejector, and water flow regulating device. It is used to regulate the operating pressure of the secondary ammonia stripping equipment, the operating temperature of the flash tank, the power steam pressure of the steam ejector, and the mixing ratio.

[0048] The operating pressure of the secondary ammonia stripping equipment is 20–200 kPa, corresponding to an operating temperature of 104–133℃. The operating pressure of the secondary ammonia stripping equipment is higher than that of the original ammonia stripping tower. The discharged mixed gas stream can directly enter the original ammonia stripping tower without pressurization or after pressure reduction and regulation. The secondary ammonia stripping equipment is a vertical tower-type or horizontal cylindrical equipment. The operating temperature of the flash tank is lower than that of the secondary ammonia stripping equipment, with a temperature difference of 2℃ to 30℃. The steam ejector is an adjustable ejector capable of automatically adjusting the injection ratio and injection intensity based on the flash steam pressure, the motive steam pressure, and the system back pressure. The motive steam pressure of the steam ejector is not lower than 0.2 kPa. The system is configured to pressurize the flash steam generated in the flash tank to the required system pressure, ensuring that the mixed steam has sufficient pressure to enter the original ammonia stripping tower or secondary ammonia stripping equipment. The system further includes a compressor for pressurizing the flash steam generated in the flash tank to the required system pressure when replacing or assisting the steam ejector. The system is suitable for direct or indirect ammonia stripping processes, and for indirect ammonia stripping systems, it can be converted to direct ammonia stripping or a steam generator can be added to directly generate new steam from ammonia stripping wastewater. The control unit controls the steam flow, pressure and system operating conditions in real time through regulating valves installed on the steam inlet pipeline, the ejector power steam inlet and the water flow regulating device.

[0049] Example 2

[0050] Referring to Figure 1, a process for a novel ammonia stripping energy-saving system includes the following steps:

[0051] S1: The ammonia stripping wastewater discharged from the original ammonia stripping tower first enters the secondary ammonia stripping equipment;

[0052] S2: Simultaneously, a stream of steam is introduced into the secondary ammonia stripping equipment, where the ammonia-containing wastewater undergoes further ammonia stripping.

[0053] S3: The ammonia-containing wastewater discharged from the secondary ammonia stripping equipment enters the flash tank again, where the ammonia-stripping wastewater is cooled and depressurized to flash vapor.

[0054] S4: The flash vapor discharged from the flash tank is pressurized by the ejector or compressor and then enters the original ammonia stripping tower or secondary ammonia stripping equipment;

[0055] S5: The steam discharged from the secondary ammonia stripping equipment is then reintroduced into the original ammonia stripping tower, achieving secondary steam utilization.

[0056] For indirect ammonia stripping systems, the added foaming and shaking ammonia stripping energy-saving system is combined with a steam generator. The steam generator uses fresh steam to heat the ammonia stripping wastewater to produce steam. A portion of the steam generated by the steam generator is used as power source steam and enters the ejector to ignite the flash steam generated in the flash tank. The other portion of the steam enters the secondary ammonia stripping equipment and is used as a stripping steam source, thereby realizing the energy-saving upgrade from indirect ammonia stripping system to direct ammonia stripping system. The energy-saving effect can also reach 35-45%.

[0057] Example 3

[0058] In a coking plant, wastewater treated by the original ammonia stripping tower is pumped to a secondary ammonia stripping unit via an intermediate booster pump. Fresh steam is introduced for secondary ammonia stripping, with the operating pressure set at 50 kPa and temperature at 111℃. The wastewater after secondary ammonia stripping enters a flash tank, where it is cooled to 95℃ and -15 kPa. The resulting flash steam is mixed with 0.5 MPa fresh steam via a steam ejector and then pressurized before being returned to the original ammonia stripping tower. Wastewater discharged from the flash tank is pumped to the biological treatment system. In actual operation, the system's steam consumption decreased from 160 kg / t to 90 kg / t, achieving an energy saving rate of approximately 44% and a significant reduction in carbon emissions.

[0059] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An ammonia stripping energy-saving system, characterized in that, include: The original ammonia stripping tower was used to receive ammonia-containing wastewater and remove ammonia nitrogen through steam stripping. An intermediate pressurization pump set, connected to the outlet of the original ammonia stripping tower, is used to pressurize and transport the ammonia stripping wastewater discharged from the original ammonia stripping tower to the secondary ammonia stripping equipment. A water flow regulating device, installed after the intermediate pressurization pump set, is used to regulate the flow rate of the ammonia stripping wastewater entering the secondary ammonia stripping equipment. The water flow regulating device is a regulating valve or a frequency converter. The secondary ammonia stripping equipment receives the ammonia stripping wastewater from the outlet of the regulating device and simultaneously introduces a stream of fresh steam to conduct contact heat exchange with the ammonia stripping wastewater, allowing the residual ammonia nitrogen in the wastewater to be further stripped and precipitated. The steam and ammonia gas mixture discharged from the secondary ammonia stripping equipment is guided to the original ammonia stripping tower for use. A flash tank, connected to the wastewater outlet of the secondary ammonia stripping equipment, is used to receive the wastewater after secondary ammonia stripping and to cause flash evaporation under cooling and depressurization conditions. The system involves several steps: First, a flash steam is generated and separated from the remaining wastewater. A steam ejector has a flash steam inlet, a power steam inlet, and a mixed steam outlet. The flash steam inlet connects to the flash tank, the power steam inlet connects to a fresh steam supply line, and the mixed steam outlet connects to the original ammonia stripping tower or secondary ammonia stripping equipment. The fresh steam is used to pressurize the flash steam, and the mixed steam is then sent to the system. A pressurization pump unit is used to transport the wastewater discharged from the flash tank to subsequent treatment units. A control unit, connected to the secondary ammonia stripping equipment, the steam ejector, and a water flow regulating device, is used to regulate the operating pressure of the secondary ammonia stripping equipment, the operating pressure and temperature of the flash tank, the power steam pressure of the steam ejector, and the injection coefficient. The operating pressure of the secondary ammonia stripping equipment is 20–200 °C. The pressure is kPa, corresponding to an operating temperature of 104–133℃; the operating pressure of the secondary ammonia stripping equipment is higher than that of the original ammonia stripping tower, and the discharged mixed gas flow can directly enter the original ammonia stripping tower without pressurization or after pressure reduction and regulation; the operating temperature of the flash tank is lower than that of the secondary ammonia stripping equipment, with a temperature difference of 2℃ to 30℃; the steam ejector is an adjustable ejector, which can automatically adjust the injection ratio and injection intensity based on the flash steam pressure, the power steam pressure, and the system back pressure conditions; the steam ejector can also be a non-adjustable ejector; the power steam pressure of the steam ejector is not less than 0.2 MPa to ensure that the ejector has a sufficiently large injection coefficient, and at the same time ensure that the mixed steam has sufficient pressure to enter the original ammonia stripping tower or the secondary ammonia stripping equipment; It is applicable to both direct and indirect ammonia stripping processes. For indirect ammonia stripping systems, a steam generator with external steam as a heat source can be added to directly generate new steam from the ammonia stripping wastewater, thereby converting it into a direct ammonia stripping system. The control unit controls the steam flow and pressure in real time through regulating valves installed on the steam inlet pipeline, the ejector power steam inlet, and the water flow regulating device, minimizing steam consumption while ensuring that the ammonia nitrogen index of the effluent meets the requirements.

2. The ammonia stripping energy-saving system according to claim 1, characterized in that, The secondary ammonia stripping equipment is either a vertical tower-type equipment or a horizontal cylindrical equipment.

3. The ammonia stripping energy-saving system according to claim 1, characterized in that, The system further includes a steam compressor for pressurizing the flash steam generated by the flash tank to the required system pressure when replacing or assisting the steam ejector.

4. The process of an ammonia stripping energy-saving system according to any one of claims 1-3, characterized in that, Includes the following steps: S1: The ammonia-containing wastewater discharged from the original ammonia stripping tower first enters the secondary ammonia stripping equipment; S2: At the same time, a stream of steam is introduced into the secondary ammonia stripping equipment, where the ammonia-containing wastewater undergoes further ammonia stripping; S3: The ammonia-containing wastewater discharged from the secondary ammonia stripping equipment then enters the flash tank, where the ammonia-containing wastewater is cooled and depressurized to flash steam; S4: The flash steam discharged from the flash tank is pressurized by an ejector or compressor and then enters the original ammonia stripping tower or the secondary ammonia stripping equipment; S5: The steam discharged from the secondary ammonia stripping equipment then enters the original ammonia stripping tower, achieving secondary steam utilization.

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