Energy-saving waste acid evaporator and operation method

Abstract

The invention provides an energy-saving waste acid evaporator and an operation method.The evaporator comprises a heating medium circulating system, the heating medium circulating system comprises a circulating tank, a steam compressor, a heater and a condenser which are connected through pipelines, and an air suction port of the steam compressor is connected with a steam outlet of the circulating tank; superheated steam of 120-130 DEG C is output from an exhaust port of the steam compressor to a shell pass of the heater, waste acid materials are introduced into a tube pass of the heater, and the shell pass of the heater and the steam compressor form a closed steam loop. The steam compressor and the heater form a closed loop, superheated steam at the temperature of 120-130 DEG C is completely recycled, energy is saved compared with a traditional graphite evaporator, and energy consumption per ton treatment is reduced to 180-200 kWh.

Description

Technical Field

[0001] This invention belongs to the field of waste acid treatment, specifically relating to an energy-saving waste acid evaporator and its operation method. Background Technology

[0002] In industrial production, waste acid evaporators are widely used to evaporate waste acid, thereby achieving the purpose of reducing waste and recovering pure acid, thus realizing the resource utilization of waste acid.

[0003] Common types of waste acid evaporators include: Graphite evaporators: These use graphite heat exchangers and separators, and then use electric heating or steam to heat the waste acid to boiling. The evaporated steam is cooled by circulating cooling water and becomes condensate. The energy consumption is as high as 350-400 yuan / ton. Enameled reactor evaporators: These use a steam compressor to pressurize and heat the secondary steam generated by evaporation, and then reuse it to evaporate the material. The material also serves as a cooling medium for the steam. The evaporation temperature is 85~90℃. Although it uses steam recompression technology, it is limited by the material and cannot handle hydrofluoric acid / nitric acid. LTAPE low-temperature atmospheric pressure evaporators: These low-temperature evaporators use a heat pump to heat the material and make it boil at 40℃ under high vacuum. At the same time, the cooling capacity generated by the heat pump is used to condense the steam. Although it has strong applicability, the operating cost is as high as 240 yuan / ton and it occupies a large area.

[0004] Therefore, the aforementioned waste acid evaporators generally suffer from problems such as high energy consumption, material limitations, or complex operation, and in particular, they cannot simultaneously handle multiple types of waste acid treatment and operate at low cost.

[0005] Therefore, designing a high-efficiency, energy-saving, and long-life waste acid evaporator is of great practical significance. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an energy-saving waste acid evaporator.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an energy-saving waste acid evaporator, including a heat medium circulation system, wherein the heat medium circulation system includes a circulation tank, a steam compressor, a heater and a condenser connected by pipelines, the suction port of the steam compressor is connected to the steam outlet of the circulation tank, the exhaust port of the steam compressor outputs superheated steam at 120~130°C to the shell side of the heater, the tube side of the heater is fed with waste acid material, and the shell side of the heater and the steam compressor form a closed steam circuit.

[0008] In some embodiments, the shell side of the condenser is connected to the circulation tank via a circulation pump, and the tube side of the condenser receives acid vapor generated from the evaporation of waste acid.

[0009] In some embodiments, a material flow system is also included, which includes a preheater and a separator connected by pipes. The inlet of the preheater is connected to a waste acid source, and the outlet is connected through the heater tube of the separator. The top outlet of the separator is connected to the tube of a condenser, and the bottom outlet forms a concentrated waste acid discharge channel.

[0010] In some embodiments, a control module is also included, including a PLC controller, for real-time monitoring and adjustment of the speed of the steam compressor, the flow rate of the circulating pump, and the system pressure. The exhaust port of the steam compressor is equipped with a temperature sensor and a pressure sensor, and the temperature sensor and the pressure sensor are communicatively connected to the PLC controller.

[0011] In some embodiments, the steam compressor is a high-temperature screw compressor with a compression ratio of 1:3.5~4.2, a temperature rise of ≥40℃, and the outlet steam temperature of the steam compressor is stable at 125±5℃.

[0012] In some embodiments, the heater and the condenser are made of graphite shells lined with a PTFE film with a thickness of 50~100μm, and a spiral turbulence generator is provided in the tube side of the heater to make the waste acid flow rate ≥2m / s.

[0013] In some embodiments, the circulation tank is equipped with a level gauge and an electric heating rod, and automatically replenishes the liquid when the liquid level is below 30%. The water replenishment pipeline of the circulation tank is equipped with a solenoid valve, which is linked to the level gauge for control.

[0014] In some embodiments, the material flow system further includes a secondary heat exchanger located between the preheater and the separator, which uses the 85-90°C waste acid solution output from the tube side of the condenser to preheat the waste acid to 80-85°C. The condenser is equipped with an air-cooled unit in parallel. When the temperature sensor detects that the acid vapor temperature exceeds 90°C, the PLC controller automatically switches to air-cooled mode.

[0015] The technical problem to be solved by the present invention is to provide an operating method for an energy-saving waste acid evaporator.

[0016] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an operation method of an energy-saving waste acid evaporator according to any of the above embodiments, comprising the following steps: starting a circulation pump to pump 85°C clean water from the circulation tank into the shell side of the condenser; starting a steam compressor to compress the clean water steam to 120~130°C and deliver it to the shell side of the heater; the waste acid is preheated to 70~80°C by the preheater and then enters the separator, where it is heated to boiling by the heater; the acid vapor is condensed into 85~90°C waste acid liquid in the tube side of the condenser, which is then returned to the preheater to preheat the new material before being discharged.

[0017] In some implementations, the speed of the steam compressor is dynamically adjusted by a PLC controller to maintain the steam temperature in the shell side of the heater at 120~130°C.

[0018] The scope of this invention is not limited to technical solutions formed by specific combinations of the above-described technical features, but also includes other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in this application.

[0019] Due to the application of the above technical solutions, the present invention has the following advantages compared with the prior art: The present invention provides an energy-saving waste acid evaporator and its operation method, which forms a closed loop between the steam compressor and the heater, so that the superheated steam at 120-130℃ can be completely recycled, which is more energy-efficient than the traditional graphite evaporator, and the energy consumption per ton of processing is reduced to 180-200kWh. Attached Figure Description

[0020] Appendix Figure 1 This is a schematic diagram of an energy-saving waste acid evaporator. Detailed Implementation

[0021] As attached Figure 1 The energy-saving waste acid evaporator shown includes a heat medium circulation system, a material flow system, and a control module.

[0022] The heat transfer medium circulation system includes a circulation tank TK-1, a steam compressor M101, a heater EX301, and a condenser EX302 connected by pipelines. The suction port of the steam compressor M101 is connected to the steam outlet of the circulation tank TK-1. The exhaust port of the steam compressor M101 outputs superheated steam at 120~130℃ to the shell side of the heater EX301. Waste acid material is introduced into the tube side of the heater EX301. The shell side of the heater EX301 and the steam compressor M101 form a closed steam circuit. The shell side of the condenser EX302 is connected to the circulation tank TK-1 through the circulation pump P101. The tube side of the condenser EX302 receives acid vapor generated by the evaporation of waste acid.

[0023] The steam compressor is a high-temperature screw compressor with a compression ratio of 1:3.5~4.2, a temperature rise of ≥40℃, and a stable outlet steam temperature of 125±5℃.

[0024] The circulating tank TK-1 is equipped with a level gauge and an electric heating rod, and automatically replenishes the liquid when the level is below 30%.

[0025] The material flow system includes a preheater EX303 and a separator SP301 connected by pipes. The inlet of the preheater EX303 is connected to the waste acid source, and the outlet is connected to the heater EX301 through the separator SP301. The top outlet of the separator SP301 is connected to the condenser EX302, and the bottom outlet forms a concentrated waste acid discharge channel.

[0026] The control module includes a PLC controller, which is used to monitor and adjust the speed of steam compressor M101, the flow rate of circulating pump P101 and the system pressure in real time. The exhaust port of steam compressor M101 is equipped with a temperature sensor and a pressure sensor. The temperature sensor and the pressure sensor are connected to the PLC controller in communication, and the data from the temperature sensor and the pressure sensor are fed back to the PLC controller in real time.

[0027] In this embodiment, the heater and condenser are made of graphite shell and lined with a PTFE film with a thickness of 50~100μm.

[0028] In this embodiment, the preheater is a plate heat exchanger, with waste acid flowing through the tube side and condensed waste acid liquid flowing through the shell side, thus realizing the cascade utilization of heat.

[0029] Working principle: The heat medium circulation process is realized through clean water as the medium. A certain amount of clean water is stored in the circulation tank TK-1 and the pipeline. After being preheated to 85°C, the steam compressor M101 is started. Under the negative pressure state of the steam compressor, 85°C steam is formed. This low-temperature steam is compressed and heated to 120~130°C under the action of the steam compressor M101, forming superheated steam. Then it is sent to the shell side of the heater EX301 in the waste acid evaporator TK-3. After exchanging heat with the material in the tube side of the heater EX301, it is cooled into clean water and returned to the circulation tank. This cycle continues.

[0030] Meanwhile, 85°C clean water is pumped into the shell side of condenser EX302 by circulating pump P101. After exchanging heat with acid vapor, the temperature rises and the water returns to the circulating tank, providing the energy required for the evaporation of clean water in the circulating tank, thus realizing energy circulation.

[0031] Material flow: At room temperature, the material is pumped into the tube side of the preheater EX303. After heat exchange with the condensate generated in the tube side of EX302, the temperature rises to 70~80℃ and enters the separator SP301. Due to the natural circulation pump of the heater EX301, the material is heated to boiling by the steam pressurized by the steam compressor M101 through the heat exchange effect of the heater EX301, and acid vapor is generated. The acid vapor enters the tube side of the condenser EX302 through the pipeline. After heat exchange with the clean water in the shell side, it is condensed to 85~90℃ to form waste acid condensate, which then enters the preheater EX303 to heat the material before flowing into the condensate tank.

[0032] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An energy-saving waste acid evaporator, characterized in that, The system includes a heat transfer medium circulation system, which comprises a circulation tank, a steam compressor, a heater, and a condenser connected by pipes. The suction port of the steam compressor is connected to the steam outlet of the circulation tank, and the exhaust port of the steam compressor outputs superheated steam at 120~130°C to the shell side of the heater. Waste acid material is introduced into the tube side of the heater, and the shell side of the heater and the steam compressor form a closed steam circuit.

2. The energy-saving waste acid evaporator according to claim 1, characterized in that: The shell side of the condenser is connected to the circulation tank via a circulation pump, and the tube side of the condenser receives acid vapor generated by the evaporation of waste acid.

3. The energy-saving waste acid evaporator according to claim 1, characterized in that: It also includes a material flow system, which includes a preheater and a separator connected by pipelines. The inlet of the preheater is connected to the waste acid source, and the outlet is connected to the heater of the separator. The top outlet of the separator is connected to the tubes of the condenser, and the bottom outlet forms a concentrated waste acid discharge channel.

4. The energy-saving waste acid evaporator according to claim 3, characterized in that: It also includes a control module, including a PLC controller, for real-time monitoring and adjustment of the speed of the steam compressor, the flow rate of the circulating pump and the system pressure. The exhaust port of the steam compressor is equipped with a temperature sensor and a pressure sensor, and the temperature sensor and the pressure sensor are communicatively connected to the PLC controller.

5. The energy-saving waste acid evaporator according to claim 1, characterized in that: The steam compressor is a high-temperature screw compressor with a compression ratio of 1:3.5~4.2 and a temperature rise of ≥40℃. The outlet steam temperature of the steam compressor is 125±5℃.

6. The energy-saving waste acid evaporator according to claim 1, characterized in that: The heater and the condenser are made of graphite shell and lined with a PTFE film with a thickness of 50~100μm. The heater tube is equipped with a spiral turbulence generator that can make the waste acid flow rate ≥2m / s.

7. The energy-saving waste acid evaporator according to claim 1, characterized in that: The circulation tank is equipped with a level gauge and an electric heating rod. When the liquid level is below 30%, the liquid is automatically replenished. The water replenishment pipeline of the circulation tank is equipped with a solenoid valve, which is linked to the level gauge for control.

8. The energy-saving waste acid evaporator according to claim 4, characterized in that: The material flow system also includes a secondary heat exchanger located between the preheater and the separator, which uses the 85-90°C waste acid solution output from the tube side of the condenser to preheat the waste acid to 80-85°C. The condenser is equipped with an air-cooled unit in parallel. When the temperature sensor detects that the acid vapor temperature exceeds 90°C, the PLC controller automatically switches to air-cooled mode.

9. A method for operating an energy-saving waste acid evaporator as described in any one of claims 1 to 8, characterized in that, Includes the following steps: Start the circulation pump to pump 85℃ clean water from the circulation tank into the condenser shell side; The steam compressor is started to compress the clean water steam to 120~130℃ and deliver it to the shell side of the heater; the waste acid is preheated to 70~80℃ by the preheater and then enters the separator, where it is heated to boiling by the heater; the acid vapor is condensed into waste acid liquid at 85~90℃ in the tube side of the condenser and then returned to the preheater to preheat the new material before being discharged.

10. The operating method according to claim 9, characterized in that: The steam compressor speed is dynamically adjusted by the PLC controller to maintain the steam temperature in the heater shell side at 120~130℃.

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