ORC waste heat generator set for electrolytic aluminum industry

Abstract

The utility model discloses an ORC waste heat generator set for the electrolytic aluminum industry. The ORC waste heat generator set comprises an expansion machine, a generator, a working medium pump, an evaporator and a condenser. Low-temperature flue gas of an aluminum electrolysis cell is conveyed into the evaporator through a pipeline, the evaporator is connected with the expansion machine through a first working medium pipeline, the expansion machine is connected with the condenser through a second working medium pipeline, the expansion machine is connected with the power generator, the condenser is connected with the evaporator through a third working medium pipeline, and the power generator is connected with the evaporator. The working medium pump is arranged on the third working medium pipeline; an evaporator liquid level meter and a condenser liquid level meter are arranged in the evaporator and the condenser respectively; the first working medium pipeline, the second working medium pipeline and the third working medium pipeline are provided with an expansion machine inlet valve, an expansion machine outlet valve and an evaporator inlet valve respectively. The device has the advantages that the device can stably operate in a strong magnetic environment, and efficient utilization of low-temperature waste heat energy in the electrolytic aluminum industry is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of low-temperature waste heat power generation, in particular to an ORC waste heat power generation unit used in the electrolytic aluminum industry. Background Art

[0002] ORC (Organic Rankine Cycle) low-temperature waste heat power generation technology converts low-grade thermal energy, such as flue gas, low-temperature hot water, and low-temperature steam, into high-grade electricity. Due to its high thermoelectric conversion efficiency and low-carbon, environmentally friendly advantages, it has been widely adopted in industries such as steel, chemical, power, and petrochemicals, achieving efficient energy utilization and gaining widespread recognition within the industry.

[0003] In the aluminum electrolytic industry, flue gas from aluminum reduction cells can be recovered and utilized. A centripetal low-temperature waste heat power generation system uses hot water as a medium for transferring heat from the flue gas, converting this heat into electricity.

[0004] During the electrolytic aluminum production process, the electrolyte in the electrolytic cell contains aluminum ions and aluminum oxide ions. The aluminum ions are reduced to aluminum metal through an electrolytic reaction. During this process, the current flowing through the electrolyte generates a magnetic field, resulting in a high magnetic field surrounding the electrolytic cell. This magnetization can also occur in surrounding equipment and piping.

[0005] In strong magnetic environments, the control systems of conventional ORC waste heat generator sets are affected by the magnetic field, resulting in electromagnetic interference and magnetization of control components, making it impossible to meet control requirements. Welding in strong magnetic environments is also affected by the magnetic field, causing magnetic arc blow and welding failure. The strong magnetic field affects the iron core of generators and motors, causing changes in magnetic flux, resulting in increased vibration, torque fluctuations, and reduced efficiency. This makes conventional ORC waste heat generator sets unable to operate stably in strong magnetic environments. The waste heat generated in this production process cannot be fully utilized, resulting in low energy efficiency and serious energy consumption. Utility Model Content

[0006] The purpose of the utility model is to provide an ORC waste heat power generation unit for the electrolytic aluminum industry, thereby solving the above-mentioned problems existing in the prior art.

[0007] In order to achieve the above purpose, the technical solution adopted by the present utility model is as follows:

[0008] An ORC waste heat power generation unit for the electrolytic aluminum industry includes an expander, a generator, a working fluid pump, an evaporator, and a condenser. Low-temperature flue gas from an aluminum electrolytic cell is transported to the evaporator via a pipeline. The evaporator is connected to the expander via a first working fluid pipeline. The expander is connected to the condenser via a second working fluid pipeline. The expander is connected to the generator. The condenser is connected to the evaporator via a third working fluid pipeline. The working fluid pump is provided on the third working fluid pipeline. The evaporator and condenser are provided with an evaporator liquid level gauge and a condenser liquid level gauge, respectively.

[0009] The first working fluid pipeline, the second working fluid pipeline and the third working fluid pipeline are respectively provided with an expander inlet valve, an expander outlet valve and an evaporator inlet valve; in the direction of working fluid movement in the third working fluid pipeline, the evaporator inlet valve is located downstream of the working fluid pump.

[0010] Preferably, the flow element of the working fluid pump is made of austenitic stainless steel.

[0011] Preferably, the motor of the working fluid pump is equipped with an anti-magnetic cover.

[0012] Preferably, the evaporator inlet valve is an electric valve, and the valve head of the electric valve is equipped with an anti-magnetic cover.

[0013] Preferably, the evaporator liquid level gauge and the condenser liquid level gauge are differential pressure liquid level gauges.

[0014] Preferably, the expander inlet valve is a pneumatic valve; the positioner of the pneumatic valve is an intrinsically safe type.

[0015] Preferably, the expander outlet valve is an electric valve, and the valve head of the electric valve is equipped with an anti-magnetic cover.

[0016] Preferably, the generator is equipped with an anti-magnetic shield.

[0017] Preferably, the pipelines and skid of the ORC waste heat generator set are prefabricated off-site and connected on-site via flanges and high-strength bolts.

[0018] Preferably, the ORC waste heat power generation unit further comprises a control system, wherein the control cables and the power cables of the control system are laid separately in the bridge, sealed with a cover plate, and the bridge spacing between the control cables and the power cables is increased;

[0019] The control cable adopts a twisted-pair cable with a shielded layer, and the outer layer of the twisted-pair cable is wrapped with a shielding layer.

[0020] The beneficial effects of the present invention are as follows: 1. The ORC waste heat generator set can operate stably in a strong magnetic environment, achieving efficient utilization of low-temperature waste heat energy in the electrolytic aluminum industry. 2. It solves the problems of reduced efficiency and heat generation caused by the magnetization of generators, motors, and working fluid pumps, and solves the problem of conventional ORC units being unable to achieve automatic control in a strong magnetic environment due to magnetization of valves and liquid level gauge components and signal feedback errors. 3. The structure and pipelines of the ORC waste heat generator set are prefabricated off-site and assembled on-site, which can meet the strength requirements of the structure and the welding requirements of the pipelines, ensuring the safety and stability of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural diagram of the ORC low-temperature waste heat generator set in an embodiment of the present utility model.

[0022] In the figure: 1. Working fluid pump; 2. Evaporator inlet valve; 3. Evaporator; 4. Evaporator liquid level gauge; 5. Expander inlet valve; 6. Expander; 7. Generator; 8. Expander outlet valve; 9. Condenser; 10. Condenser liquid level gauge. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] like Figure 1 As shown, in this embodiment, in order to solve the problem that the ORC waste heat power generation unit cannot operate stably in a strong magnetic environment, the utility model improves the process, structure, control, etc. of the traditional ORC waste heat power generation unit, so that the ORC waste heat power generation unit can operate stably in a strong magnetic environment and achieve efficient energy utilization. Specifically, an ORC waste heat power generation unit for the electrolytic aluminum industry is provided, including an expander 6, a generator 7, a working fluid pump 1, an evaporator 3 and a condenser 9; the low-temperature flue gas of the aluminum electrolytic cell is transported to the evaporator 3 through a pipeline, the evaporator 3 is connected to the expander 6 through a first working fluid pipeline, the expander 6 is connected to the condenser 9 through a second working fluid pipeline, the expander 6 is connected to the generator 7, and the condenser 9 is connected to the evaporator 3 through a third working fluid pipeline, and the working fluid pump 1 is arranged on the third working fluid pipeline.

[0025] The first working fluid pipeline, the second working fluid pipeline and the third working fluid pipeline are respectively provided with an expander inlet valve 5, an expander outlet valve 8 and an evaporator inlet valve 2; in the direction of working fluid movement in the third working fluid pipeline, the evaporator inlet valve 2 is located downstream of the working fluid pump 1.

[0026] The outlet of working fluid pump 1 is connected to evaporator 3 via a pipeline. The working fluid flow rate is controlled by evaporator inlet valve 2. The heat source exchanges heat with the working fluid through the heat exchanger. The working fluid absorbs heat from the heat source in evaporator 3, transforming from liquid to gaseous state. This is then transported through a pipeline to expander 6. The gaseous working fluid drives the impeller of expander 6, driving generator 7 to generate electricity. The working fluid flow rate is regulated by expander inlet valve 5. After expansion, the working fluid is transported through a pipeline to condenser 9, where it condenses into a liquid state and flows back to working fluid pump 1, completing the cycle.

[0027] The evaporator 3 and the condenser 9 are provided with an evaporator liquid level gauge 4 and a condenser liquid level gauge 10 respectively; the evaporator liquid level gauge 4 and the condenser liquid level gauge 10 are used to detect the liquid levels of the evaporator 3 and the condenser 9 respectively.

[0028] In this embodiment, the flow element of the fluid pump 1 is made of austenitic stainless steel to prevent magnetization. If this element becomes magnetized, it can reduce the efficiency of the fluid pump 1, resulting in reduced flow and head. A magnetized impeller can also cause noise and temperature rise during operation. However, the use of austenitic stainless steel as the flow element is impervious to magnetization in magnetic fields, ensuring the long-term stable operation of the fluid pump 1 in strong magnetic environments.

[0029] In this embodiment, the motor of the working fluid pump 1 is equipped with an anti-magnetic shield. In a strong magnetic environment, the stress on the motor's core can change, causing increased motor vibration. Strong magnetism can also alter the motor's magnetic flux, affecting its output torque and power, and reducing its performance. By adding the anti-magnetic shield, the majority of the magnetic field is concentrated within it, forming a magnetic shield. This effectively reduces the magnitude and direction of the magnetic field at the motor.

[0030] In this embodiment, the evaporator inlet valve 2 is an electric valve, and the valve head of the electric valve is equipped with an anti-magnetic cover. The manual automatic switching of the electric valve is of electromagnetic induction type. When it is in a strong magnetic environment, it will affect the electromagnetic induction of the electric valve itself, and remote switching cannot be achieved. The opening and closing of the electric valve is driven by an electric motor. In a strong magnetic environment, the stress on the iron core of the motor will change, resulting in increased vibration of the motor. Strong magnetism will also cause the magnetic flux of the motor to change, thereby affecting the output torque and power of the motor and reducing the performance of the motor. By adding an anti-magnetic cover, most of the magnetic field is concentrated in the anti-magnetic cover to form a magnetic shield. The size and direction of the magnetic field at the motor and the manual automatic switching knob are effectively reduced, thereby realizing remote control of the electric valve.

[0031] In this embodiment, the evaporator level gauge 4 and the condenser level gauge 10 are differential pressure level gauges. Since the ORC unit has very high requirements for liquid level control, it is necessary to meet the full range measurement of the liquid level and real-time feedback. The magnetic flap level gauge selected by the conventional unit contains magnetic components. In a strong magnetic environment, the liquid level display is inaccurate and the error is too large, making it impossible to control the liquid level during the operation of the ORC unit. The differential pressure level gauge uses the pressure generated by the liquid column to measure the liquid level. The pressure change caused by the liquid level change is used to calculate the liquid level height. It is not affected by the magnetic field and can operate stably in a magnetic field environment. The liquid level control requirements of the ORC waste heat generator set can be met. Through the feedback of the liquid level signal, the frequency conversion of the working fluid pump 1 and the evaporator inlet valve 2 are controlled to adjust the container liquid level.

[0032] In this embodiment, the expander inlet valve 5 is a pneumatic valve that enables rapid valve adjustment. An intrinsically safe positioner is selected. In the ORC low-temperature waste heat generator set, the flow rate of the expander 6 in the intake pipe needs to be precisely controlled. Precise adjustment is achieved by adjusting the position of the pneumatic valve on the intake pipe. The valve positioner plays a vital role in this process. To achieve precise valve control, the valve positioner needs to be re-adjusted on site to improve control accuracy, response speed, and stability. Conventional positioners are self-tuning electromagnetic induction type and are subject to magnetic field interference in a strong magnetic environment, making self-tuning impossible. Intrinsically safe positioners, on the other hand, are self-tuning mechanically and are not affected by the magnetic field environment, thus meeting the pneumatic valve adjustment requirements.

[0033] In this embodiment, the expander outlet valve 8 is an electric valve, and the valve head of the electric valve is equipped with an anti-magnetic cover. The manual automatic switching of the electric valve is of electromagnetic induction type. When it is in a strong magnetic environment, it will affect the electromagnetic induction of the electric valve itself, and remote switching cannot be achieved. The opening and closing of the electric valve are driven by an electric motor. In a strong magnetic environment, the stress on the iron core of the motor will change, resulting in increased vibration of the motor. Strong magnetism will also cause the magnetic flux of the motor to change, thereby affecting the output torque and power of the motor and reducing the performance of the motor. By adding an anti-magnetic cover, most of the magnetic field is concentrated in the anti-magnetic cover to form a magnetic shield. The size and direction of the magnetic field at the motor and the manual automatic switching knob are effectively reduced, thereby realizing remote control of the electric valve. The control cables of the ORC waste heat generator set are laid separately from the power cables, and the distance between the control cables and the power cable tray is increased to avoid additional magnetic field interference with the power cables.

[0034] In this embodiment, the generator 7 is equipped with an anti-magnetic cover to prevent the generator 7 from being magnetized.

[0035] In this embodiment, the pipelines and skid body of the ORC waste heat generator set are prefabricated off-site and connected on-site by flanges and high-strength bolts. In a strong magnetic environment, arc magnetic blow will occur during welding, the arc will swing violently or even go out, the state of the welding molten pool will change, the molten pool will be asymmetric, the weld width will increase, the weld depth will decrease, and other welding problems will result in the failure to meet the welding process requirements. Generally, welding in a strong magnetic environment adopts methods such as adding a shielding body and adding a demagnetization device. The welding is difficult, the construction time is long, and the requirements for welders are high. The use of off-site prefabrication and on-site assembly can avoid the influence of the magnetic field. Both structural and pipeline welding can meet the welding process requirements. By strictly controlling the blanking and welding tolerances, the entire field can be assembled on-site.

[0036] In this embodiment, the ORC waste heat generator set also includes a control system. Strong magnetic fields can affect the control quality of the control system and even damage components within the PLC. This is achieved by laying the control cables and power cables separately in cable trays, enclosing them with covers, and increasing the spacing between the cable trays. All control cables use shielded twisted-pair cables, with the shield wrapped around the outer layer of the twisted pair. Ensure that all grounding wires are reliably grounded.

[0037] By adopting the above technical solution disclosed in the utility model, the following beneficial effects are obtained:

[0038] The utility model provides an ORC waste heat generator set for the electrolytic aluminum industry. The ORC waste heat generator set can operate stably in a strong magnetic environment, achieving efficient utilization of low-temperature waste heat energy in the electrolytic aluminum industry. It solves problems such as reduced efficiency and heat generation caused by the magnetization of generators, motors, and working fluid pumps, and solves the problem of conventional ORC units being unable to achieve automatic control in a strong magnetic environment due to magnetization of valves and liquid level gauge components and signal feedback errors. The structure and pipelines of the ORC waste heat generator set are prefabricated off-site and assembled on-site, which can meet the strength requirements of the structure and the welding requirements of the pipelines, ensuring the safety and stability of the unit.

[0039] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An ORC waste heat power generation unit for the electrolytic aluminum industry, characterized by: The system comprises an expander, a generator, a working fluid pump, an evaporator and a condenser; the low-temperature flue gas of the aluminum electrolysis cell is transported to the evaporator through a pipeline; the evaporator is connected to the expander through a first working fluid pipeline; the expander is connected to the condenser through a second working fluid pipeline; the expander is connected to the generator; the condenser is connected to the evaporator through a third working fluid pipeline; the working fluid pump is arranged on the third working fluid pipeline; the evaporator and the condenser are respectively provided with an evaporator liquid level gauge and a condenser liquid level gauge; The first working fluid pipeline, the second working fluid pipeline and the third working fluid pipeline are respectively provided with an expander inlet valve, an expander outlet valve and an evaporator inlet valve; in the direction of working fluid movement in the third working fluid pipeline, the evaporator inlet valve is located downstream of the working fluid pump.

2. The ORC waste heat power generation unit for the electrolytic aluminum industry according to claim 1 is characterized in that: The flow element of the working fluid pump is made of austenitic stainless steel.

3. The ORC waste heat power generation unit for the electrolytic aluminum industry according to claim 1 is characterized in that: The motor of the working fluid pump is additionally equipped with an anti-magnetic cover.

4. The ORC waste heat power generation unit for the electrolytic aluminum industry according to claim 1 is characterized in that: The evaporator inlet valve is an electric valve, and a valve head of the electric valve is additionally provided with an anti-magnetic cover.

5. The ORC waste heat power generation unit for the electrolytic aluminum industry according to claim 1 is characterized in that: The evaporator liquid level gauge and the condenser liquid level gauge are differential pressure liquid level gauges.

6. The ORC waste heat power generation unit for the electrolytic aluminum industry according to claim 1, characterized in that: The expander inlet valve is a pneumatic valve; the positioner of the pneumatic valve is an intrinsically safe type.

7. The ORC waste heat power generation unit for the electrolytic aluminum industry according to claim 1, characterized in that: The expander outlet valve is an electric valve, and a valve head of the electric valve is additionally provided with an anti-magnetic cover.

8. The ORC waste heat power generation unit for the electrolytic aluminum industry according to claim 1, characterized in that: The generator is additionally equipped with an anti-magnetic cover.

9. The ORC waste heat power generation unit for the electrolytic aluminum industry according to claim 1, characterized in that: The pipelines and skid of the ORC waste heat generator set are prefabricated off-site and connected on-site through flanges and high-strength bolts.

10. The ORC waste heat power generation unit for the electrolytic aluminum industry according to claim 1, characterized in that: The ORC waste heat power generation unit also includes a control system, wherein the control cables and power cables of the control system are laid separately in the bridge, closed with a cover plate, and the bridge spacing between the control cables and the power cables is increased; The control cable adopts a twisted-pair cable with a shielded layer, and the outer layer of the twisted-pair cable is wrapped with a shielding layer.

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