Liquid level control device and control method for desulfurization wastewater negative pressure evaporation equipment

Abstract

The invention discloses a liquid level control device and a control method for desulfurization wastewater negative pressure evaporation equipment. An overflow port is formed in the upper part of the negative pressure evaporation equipment, the overflow port is connected with a negative pressure overflow pipe, an isolating valve and a vacuum breaking valve are arranged on the negative pressure overflow pipe, the isolating valve is close to the overflow port, the vacuum breaking valve is far away from the overflow port, and the isolating valve is kept in a normally open state; a vacuum meter is arranged on the negative pressure overflow pipe at the front end of the vacuum breaking valve; and the isolating valve, the vacuum breaking valve and the vacuum meter are all connected with a controller. The negative pressure overflow pipe and the negative pressure evaporation equipment are located in the same negative pressure environment, when the liquid level in the negative pressure evaporation equipment exceeds the overflow port, liquid overflows into the negative pressure overflow pipe, the vacuum meter detects that the pressure in the negative pressure overflow pipe exceeds a preset value, the vacuum breaking valve is opened, the overflow liquid is discharged, part of air enters the negative pressure overflow pipe, and the negative pressure state in the equipment is destroyed. The liquid level is prevented from rising; when the pressure value in the negative pressure overflow pipe is smaller than the preset value, the vacuum breaking valve is closed, the vacuum degree in the equipment is adjusted through opening and closing of the vacuum breaking valve, and the stable liquid level is recovered.

Description

Technical Field

[0001] The invention belongs to the technical field of zero-discharge treatment of industrial wastewater, and in particular relates to a liquid level control device and a control method for negative pressure evaporation equipment for desulfurization wastewater. Background Art

[0002] In the evaporation concentration and drying treatment systems for high-concentration polluted wastewater such as industrial wastewater and desulfurization wastewater, negative pressure multi-effect evaporation systems are mostly used for concentration. During the operation of the system, the liquid level of the evaporation separator in the system needs to be strictly controlled and cannot be too high, otherwise it will cause scaling in the demister on the upper part of the evaporation separator and contaminate the condensed water formed by the secondary steam.

[0003] Since the evaporation separator operates under negative pressure, it is impossible to set an overflow port under normal pressure and gravity overflow is impossible. As a result, when the liquid level suddenly rises abnormally, it will flood the demister and even overflow into the next-stage heat exchanger, causing widespread pollution and damage to the entire system. Once this phenomenon occurs, the machine can only be shut down for cleaning and maintenance, which seriously affects normal production. At present, there is no particularly good liquid level control device and liquid level control method.

[0004] In addition, due to the existence of evaporation and condensation, and the wastewater is highly concentrated and in an oversaturated state, the microwave transmitting and receiving surfaces of ultrasonic level gauges and radar level gauges are disturbed by condensed water, the static pressure level gauge cannot reflect the real liquid level under negative pressure, the visual interface of sight glasses and glass tube level gauges is easily covered by pollutants, and the price of gamma radio frequency level gauges is too expensive. Therefore, magnetic flap level gauges are generally set to measure the liquid level in the evaporation separator. However, the liquid inside the evaporation separator is the desulfurization wastewater that is being concentrated, which has the characteristics of high viscosity, crystallization, and scaling tendency. The general level measurement method causes measurement instability due to the existence of negative pressure or vacuum. Moreover, when the liquid contacts the measuring components (such as floats) and the liquid is in the cavity of the measuring equipment, the liquid is in a "dead water" state, and the flow amplitude is very small. Liquid salt crystallization, scaling, flow channel blockage, and adhesion of measuring components to the cavity will occur, so the liquid level in the evaporation separator cannot be accurately measured, resulting in consequences such as failure of the evaporation system. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a liquid level control device and a control method that can cooperate with actual application conditions, so as to achieve accurate and reliable control of the liquid level of the evaporation separator of the multi-effect evaporation system under negative pressure, reduce the labor intensity of monitoring operations by monitoring personnel, and enable the equipment to safely and timely adjust the operating status during continuous operation.

[0006] The object of the present invention is achieved in the following manner: A liquid level control device for a negative pressure evaporation device for desulfurization wastewater, wherein an overflow port is arranged on the upper part of the negative pressure evaporation device, the overflow port is connected to a negative pressure overflow pipe, an isolation valve and a rupture valve are arranged on the negative pressure overflow pipe, the isolation valve is close to the overflow port, the rupture valve is far away from the overflow port, the isolation valve is kept in a normally open state, a vacuum gauge is arranged on the negative pressure overflow pipe at the front end of the rupture valve, and the isolation valve, the rupture valve and the vacuum gauge are all connected to a controller.

[0007] The diameter of the negative pressure overflow pipe is larger than the diameter of the liquid inlet pipe of the negative pressure evaporation equipment.

[0008] A liquid level measuring device is also provided on the negative pressure evaporation equipment, and the liquid level measuring device includes a float, a pulley, a connecting rope, a float cavity, a magnetic float, an upper connecting pipe, and a lower connecting pipe. The upper connecting pipe on the upper part of the float cavity is connected to the upper interface of the negative pressure evaporation equipment, and the lower connecting pipe on the lower part is connected to the lower interface of the negative pressure evaporation equipment but is not connected. A first pulley is provided on the inner wall of the upper interface of the negative pressure evaporation equipment, and a second pulley is provided at the connection between the upper connecting pipe and the float cavity. The connecting rope passes around the first pulley and the second pulley, one end of which is connected to the magnetic float, and the other end is connected to the float. The float is located in the negative pressure evaporation equipment and floats on the liquid surface. A liquid level display panel and a signal remote transmission device are fixedly provided on the outer surface of the float cavity.

[0009] The upper and lower ends of the float cavity are provided with detachable sealing structures.

[0010] The sealing structure at the upper end of the float cavity is a flange cover or a threaded cover, and the sealing structure at the lower end of the float cavity is a flange cover or a threaded cover or a valve.

[0011] A liquid level control method for a negative pressure evaporation device for desulfurization wastewater, wherein the liquid level inside the negative pressure evaporation device fluctuates and exceeds the overflow port height of the negative pressure evaporation device, the isolation valve on the negative pressure overflow pipe is normally open, and the liquid in the negative pressure evaporation device flows from the overflow port into the negative pressure overflow pipe. As the liquid level in the negative pressure overflow pipe increases, the vacuum gauge detects the pressure in the negative pressure overflow pipe in real time and transmits the pressure signal to the controller. When the pressure exceeds the preset value, the controller controls the air-breaking valve to open, the overflow liquid is discharged, and part of the air enters the negative pressure overflow pipe, thereby destroying the negative pressure state in the equipment and preventing the liquid level from rising. When the pressure value in the negative pressure overflow pipe measured by the vacuum gauge is less than the preset value, the air-breaking valve is closed.

[0012] Compared with the prior art, the present invention adds an overflow port to the negative pressure evaporation equipment, and the overflow port is connected to the negative pressure overflow pipe, and the abnormally high liquid level overflows and discharges. The negative pressure overflow pipe and the negative pressure evaporation equipment are in the same negative pressure environment. When the vacuum of the negative pressure evaporation equipment changes suddenly, the liquid level fluctuates and exceeds the overflow port, and the liquid overflows into the negative pressure overflow pipe. As the liquid level in the negative pressure overflow pipe rises, the vacuum gauge detects the pressure in the negative pressure overflow pipe in real time. When the pressure exceeds the preset value, the air-breaking valve opens, the overflowing liquid is discharged, and part of the air enters the negative pressure overflow pipe, destroying the negative pressure state in the equipment and preventing the liquid level from rising. When the pressure value in the negative pressure overflow pipe measured by the vacuum gauge is less than the preset value, the air-breaking valve is closed, and the vacuum degree in the equipment is adjusted and the stable liquid level is restored by opening and closing the air-breaking valve, so as to avoid the liquid level being immersed in the defogger and causing damage to the equipment, and quickly restore the equipment to normal operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0014] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the present invention.

[0015] like Figure 1 As shown, a liquid level control device for a negative pressure evaporation device for desulfurization wastewater is provided, an overflow port is provided on the upper part of a negative pressure evaporation device 1 with a demister 7 on the top, the overflow port is connected to a negative pressure overflow pipe 2, an isolation valve 3 and a rupture valve 4 are provided on the negative pressure overflow pipe 2, the isolation valve 3 is close to the overflow port, the rupture valve 4 is far away from the overflow port, the isolation valve 3 is kept in a normally open state, a vacuum gauge 5 is provided on the negative pressure overflow pipe at the front end of the rupture valve 4, and the isolation valve 3, the rupture valve 4 and the vacuum gauge 5 are all connected to a controller.

[0016] A liquid level control method for a negative pressure evaporation device for desulfurization wastewater, wherein the isolation valve 3 on the negative pressure overflow pipe 2 is kept open when the device is working. When the vacuum in the negative pressure evaporation device 1 changes suddenly, the internal liquid level fluctuates and exceeds the overflow port height of the negative pressure evaporation device. The liquid in the negative pressure evaporation device 1 flows from the overflow port into the negative pressure overflow pipe 2. As the liquid level in the negative pressure overflow pipe increases, the vacuum gauge 5 detects the pressure in the negative pressure overflow pipe in real time and transmits the pressure signal to the controller. When the pressure exceeds a preset value, the controller controls the air-breaking valve 4 to open, the overflow liquid is discharged, and part of the air enters the negative pressure overflow pipe, thereby destroying the negative pressure state in the device and preventing the liquid level from rising. When the pressure value in the negative pressure overflow pipe measured by the vacuum gauge is less than the preset value, the air-breaking valve 4 is closed, thereby realizing safe liquid level control of the negative pressure evaporation device for desulfurization wastewater and effectively preventing the liquid level from being submerged in the demister 7 and causing damage to the equipment.

[0017] Furthermore, the diameter of the negative pressure overflow pipe 2 is larger than the diameter of the liquid inlet pipe of the negative pressure evaporation device 1 , ensuring that when overflow occurs, the overflow capacity of the overflow pipe is greater than the liquid inlet volume of the negative pressure evaporation device 1 .

[0018] Furthermore, a liquid level measuring device 6 is also provided on the negative pressure evaporation equipment 1, and the liquid level measuring device 6 includes a float 61, a pulley 62, a connecting rope 63, a float cavity 64, a magnetic float 65, an upper connecting pipe 66 and a lower connecting pipe 67. The upper connecting pipe 66 at the upper part of the float cavity 64 is connected to the upper part of the negative pressure evaporation equipment 1, and the lower connecting pipe 67 at the lower part is connected but not connected to the negative pressure evaporation equipment 1. A first pulley 621 is provided on the inner wall of the upper interface of the negative pressure evaporation equipment 1, and a second pulley 622 is provided at the connection between the upper connecting pipe 66 and the float cavity 64. The connecting rope 63 passes around the first pulley 621 and the second pulley 622, one end of which is connected to the magnetic float 65, and the other end is connected to the float 61. The float 61 is located in the negative pressure evaporation equipment 1 and floats on the liquid surface. A liquid level display panel 68 and a signal remote transmission device 69 are fixedly provided on the outer surface of the float cavity 64. As the liquid level rises, the float 61 and the magnetic float 65 continue to drop in the float cavity 64, and the liquid level in the negative pressure evaporation device is displayed in real time on the liquid level display panel 68. The magnetic float 65, the float cavity 64, etc. are not in contact with the liquid in the negative pressure evaporation device, and only the float 61 is in contact with the measured liquid, which effectively prevents the occurrence of phenomena such as liquid salt crystallization, scaling, flow channel blockage, and measurement component adhesion, and will not produce false signals, and can truly reflect the actual liquid level in the negative pressure evaporation device.

[0019] The liquid level display disk 6 is for local display, including a disk surface displaying a scale and a magnetic flap or magnetic flip column corresponding to the scale; the two sides of the magnetic flap or magnetic flip column are clearly distinguished by different colors, and the action of the magnetic float drives the magnetic flap or magnetic flip column on the display disk to flip, and the color flip is used to display different liquid levels on the spot and corresponds to the scale on the liquid level display disk; the magnetic float drives the magnetic flap or magnetic flip column to flip by moving up and down, and the magnetic flap or magnetic flip column flips and connects to the signal remote transmission device to convert it into an electrical signal and transmit it to a remote display, etc.

[0020] The upper and lower ends of the float cavity 65 are provided with a detachable sealing structure. In a preferred embodiment, the sealing structure at the upper end of the float cavity 65 is a flange cover or a threaded cover or other forms, and the sealing structure at the lower end of the float cavity 65 is a flange cover or a threaded cover or a valve, so that condensed water in the liquid level measuring device 6 can be discharged in time when the equipment is not in operation.

[0021] Furthermore, the liquid level measuring device 6 is connected to the controller and interlocked with the air-breaking valve 4. When the liquid level returns to the set normal value, the air-breaking valve 4 is closed.

[0022] After the air-breaking valve 4 is closed, the interlocking relationship can be temporarily released, such as closing the isolation valve 3 manually or automatically, opening the air-breaking valve 4, and flushing the inner wall of the vacuum overflow pipe below the isolation valve 4, the vacuum gauge 5, and the air-breaking valve 4 with clean water to prevent highly concentrated liquid from remaining on the inner wall of the pipeline, the inner wall of the valve, and the liquid surface of the vacuum gauge, causing salt crystallization, vacuum gauge failure, air-breaking valve switch failure, etc. After cleaning, close the air-breaking valve, open the isolation valve, and restore the interlocking function.

[0023] The liquid level measuring device 6 is assembled according to the following steps: 1) Place the float 61 on the solution to be tested and mark the position where the liquid surface is immersed; 2) Open the sealing structure at the upper end of the float cavity 64 and install and fix the second pulley 622 at the connection between the upper pipe 66 and the float cavity 64; 3) The first pulley 621 is mounted and fixed on the inner wall of the upper pipe 66 of the negative pressure evaporation device 1; 4) Fix the liquid level display plate 68 and the signal remote transmission device 69 to the outer surface of the float chamber 64, and the reading of the liquid level display plate 68 gradually increases from high to low and from zero; 5) Connect the upper pipe 66 on the upper part of the float chamber 64 to the upper interface of the negative pressure evaporation device 1, and a flange with a hole in the middle can be used to connect them; 6) Connect the lower connecting pipe 67 at the bottom of the float chamber 64 to the lower interface of the negative pressure evaporation device 1, and use a flange with no hole in the middle to make it blocked; 7) Fix one end of the connecting rope 63 to the magnetic float 65 and put it into the float cavity 64. The other end of the connecting rope 63 passes over the first pulley 621 and the second pulley 622 and is temporarily fixed to the buoy 61. 8) Adjust the length of the connecting rope 63 between the magnetic float 65 and the buoy 61 so that the reading displayed on the liquid level display plate 68 matches the height of the mark on the immersion position of the buoy liquid surface, cut the connecting rope 63 to a suitable length and fix it to the buoy 61; 9) Finally, reseal the sealing structure at the upper end of the float chamber 64.

[0024] The liquid level measuring device 6 can also be transformed from a magnetic flap (column) liquid level gauge, and the modification only needs to be carried out according to the following steps: 1) Place the float on the solution to be tested and mark the position where the liquid surface is immersed; 2) Open the sealing structure at the upper end of the float chamber of the magnetic flap (column) level gauge and take out the magnetic float; 3) Fix the first pulley and the second pulley to the inner wall of the interface on the negative pressure evaporation device and the connection between the float cavity and the upper pipe respectively; 4) Invert the liquid level display disk of the magnetic flap (column) liquid level gauge, and the reading of the liquid level display disk increases from high to low and from zero; 5) Connect the upper pipe on the upper part of the float chamber to the interface on the negative pressure evaporation equipment. If there is a valve originally, remove the valve; 6) Add an isolation plate between the lower pipe at the bottom of the float chamber and the lower interface of the negative pressure evaporation equipment and connect them well. If there is a valve originally, remove the valve; 7) Fix one end of the connecting rope to the magnetic float, put it into the float cavity, and connect the other end of the connecting rope across the first pulley and the second pulley, and temporarily fix it to the float; 8) Adjust the length of the connecting rope between the magnetic float and the buoy so that the reading displayed on the liquid level display plate matches the height of the mark on the immersion position of the buoy liquid surface. Cut the connecting rope to a suitable length and fix it to the buoy. 9) Reseal the sealing structure at the top of the float chamber.

[0025] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several changes and improvements can be made without departing from the overall concept of the present invention, which should also be regarded as the scope of protection of the present invention.

Claims

1. A liquid level control device for desulfurization wastewater negative pressure evaporation equipment, characterized in that: An overflow port is arranged at the top of the negative pressure evaporation device (1), and the overflow port is connected to a negative pressure overflow pipe (2). An isolation valve (3) and a piercing valve (4) are arranged on the negative pressure overflow pipe (2). The isolation valve (3) is close to the overflow port, and the piercing valve (4) is far from the overflow port. The isolation valve (3) is kept in a normally open state. A vacuum gauge (5) is arranged on the negative pressure overflow pipe at the front end of the piercing valve (4). The isolation valve (3), the piercing valve (4), and the vacuum gauge (5) are all connected to a controller.

2. The liquid level control device for desulfurization wastewater negative pressure evaporation equipment according to claim 1 is characterized in that: The diameter of the negative pressure overflow pipe (2) is larger than the diameter of the liquid inlet pipe of the negative pressure evaporation device (1).

3. The liquid level control device for desulfurization wastewater negative pressure evaporation equipment according to claim 1 is characterized in that: The negative pressure evaporation device (1) is also provided with a liquid level measuring device (6), the liquid level measuring device (6) comprising a float (61), a pulley (62), a connecting rope (63), a float cavity (64), a magnetic float (65), an upper connecting pipe (66), and a lower connecting pipe (67). The upper connecting pipe (66) at the upper part of the float cavity (64) is connected to the upper interface of the negative pressure evaporation device (1), and the lower connecting pipe (67) at the lower part is connected to the lower interface of the negative pressure evaporation device (1) but is not connected. The negative pressure evaporation device (1) A first pulley (621) is arranged on the inner wall of the upper interface, a second pulley (622) is arranged at the connection between the upper pipe (66) and the float cavity (64), a connecting rope (63) passes around the first pulley (621) and the second pulley (622), one end of which is connected to the magnetic float (65) and the other end of which is connected to the float (61), the float (61) is located in the negative pressure evaporation device (1) and floats on the surface of the liquid, and a liquid level display panel (68) and a signal remote transmission device (69) are fixedly arranged on the outer surface of the float cavity (64).

4. The liquid level control device for desulfurization wastewater negative pressure evaporation equipment according to claim 1 is characterized in that: The float chamber (65) is provided with detachable sealing structures at the upper and lower ends.

5. The liquid level control device for desulfurization wastewater negative pressure evaporation equipment according to claim 4 is characterized in that: The sealing structure at the upper end of the float cavity (65) is a flange cover or a threaded cover, and the sealing structure at the lower end of the float cavity (65) is a flange cover or a threaded cover or a valve.

6. The control method of the liquid level control device for desulfurization wastewater negative pressure evaporation equipment according to any one of claims 1 to 5, characterized in that: The liquid level inside the negative pressure evaporation device (1) fluctuates and exceeds the overflow port height of the negative pressure evaporation device. The isolation valve (3) on the negative pressure overflow pipe (2) is normally open, and the liquid in the negative pressure evaporation device flows from the overflow port into the negative pressure overflow pipe (2). As the liquid level in the negative pressure overflow pipe rises, the vacuum gauge (5) detects the pressure in the negative pressure overflow pipe in real time and transmits the pressure signal to the controller. When the pressure exceeds the preset value, the controller controls the air-breaking valve (4) to open, the overflow liquid is discharged, and some air enters the negative pressure overflow pipe, thereby destroying the negative pressure state in the device and preventing the liquid level from rising. When the pressure value in the negative pressure overflow pipe measured by the vacuum gauge is lower than the preset value, the air-breaking valve (4) is closed.

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