Instrument air on-line water removal system

Abstract

The invention discloses an instrument air online water removal system which comprises an air compressor, and an outlet of the air compressor is sequentially communicated with a buffer tank, a cold dryer, an adsorption device and an air storage tank through air pipelines. The adsorption device comprises a first adsorption tower and a second adsorption tower which are connected in parallel. The system effectively removes moisture in compressed air, reduces the dew-point temperature and ensures that the dew-point temperature of the compressed air is less than or equal to-40 DEG C by utilizing the principle of freeze dehydration and adsorption dehydration, so that the dryness of air used by pneumatic equipment is improved, and the conditions of corrosion, blockage and freezing in pipelines, valves or equipment caused by the fact that water vapor is condensed into water at low temperature are avoided; the service life of equipment is prolonged, the whole system is interlocked through the PLC, and automatic operation is achieved.

Description

Technical Field

[0001] The invention relates to the field of chemical production equipment, and in particular to an instrument air online water removal system. Background Art

[0002] Instrument air is an important resource in industrial production and a key factor in ensuring the stable and efficient operation of industrial automation control systems. It is mainly used for the drive and control of pneumatic equipment, and as an auxiliary gas in certain process steps. For example, it is the main power source for pneumatic actuators such as cylinders and pneumatic valves. By controlling the pressure and flow of the gas, precise control and movement of the equipment can be achieved.

[0003] Instrument air is usually produced by an air compressor that draws air from the atmosphere and undergoes a series of treatment processes such as compression. During the compression process, moisture, oil mist and impurities in the air are gradually removed, and the produced instrument air can meet the strict requirements of instrumentation and control systems. However, during the preparation of instrument air, the water content of compressed air is high and difficult to handle, resulting in a high water content in the produced instrument air, which will have the following impacts on equipment and facilities: (1) Moisture in instrument air can cause corrosion inside pneumatic equipment and pipelines, especially for moisture-sensitive components such as pneumatic valves, cylinders, instruments and control system electronic components. Long-term exposure to high humidity environments will accelerate the wear and failure of these components, reduce the overall reliability and efficiency of the system, and accelerate equipment damage. (2) Pneumatic control systems rely on precise pressure and flow control, and the presence of moisture will change the volume and compressibility of the gas, affecting the accurate transmission of pneumatic signals, resulting in inaccurate feedback from the control system, affecting the control accuracy and product quality of the production process. (3) In low temperature environments, moisture in the instrument air may condense into ice inside the pipeline or equipment, blocking the air path, restricting airflow, and even causing equipment damage. In extreme cases, freezing may also cause pipeline ruptures, especially in hazardous chemicals and major hazard source devices, which can easily cause safety accidents. (4) Excessive moisture will increase the maintenance frequency and cost of equipment, including replacing corroded and damaged parts, cleaning or replacing filters, desiccants, etc., as well as production losses caused by downtime due to faults, which are costly. (5) In some industries with strict requirements on the production environment, such as the air delivery device for polyvinyl chloride resin, the moisture in the instrument air will directly cause quality problems such as resin rehumidification and agglomeration, which does not meet the use requirements. Summary of the invention

[0004] The present invention provides an instrument air online dehumidification system, which aims to solve the problem that high water content in the instrument air preparation process causes internal corrosion of pneumatic equipment and pipelines, affects control accuracy, and accelerates equipment damage.

[0005] To achieve its purpose, the present invention adopts the following technical solution: An instrument air online dehumidification system comprises an air compressor, wherein the outlet of the air compressor is sequentially connected with a buffer tank, a cold dryer, an adsorption device and an air storage tank through an air pipeline.

[0006] Furthermore, the adsorption device includes two parallel first adsorption towers and second adsorption towers, and the air ducts connecting the cold dryer and the first adsorption tower and the second adsorption tower are respectively provided with cut-off valves, and the air ducts at the tops of the first adsorption tower and the second adsorption tower are respectively provided with check valves, and the air ducts at the tops are also respectively provided with cut-off valves; the first adsorption tower and the second adsorption tower are both provided with time relays.

[0007] Furthermore, the bottoms of the buffer tank, the cold dryer and the air storage tank are all connected to a first drainage pipe, and the first drainage pipe is provided with an automatic drainage valve.

[0008] Furthermore, the bottoms of the first adsorption tower and the second adsorption tower are connected with a second drainage pipe, and the second drainage pipes are respectively provided with a cut-off valve.

[0009] Furthermore, the air duct between the first adsorption tower and the second adsorption tower is connected with a first branch duct, and the first branch duct is provided with an electric heater.

[0010] Furthermore, the air duct at the outlet of the cold dryer is connected to a second branch duct, and a first valve is provided on the second branch duct.

[0011] Furthermore, a second valve is provided on the air pipeline between the adsorption device and the air storage tank.

[0012] Furthermore, a muffler is provided on the second drainage pipe.

[0013] Furthermore, a thermometer is provided on the air duct at the outlet of the cold dryer.

[0014] Furthermore, the time relay is electrically connected to the signal input end of the PLC programmable controller, and the signal output end of the PLC programmable controller is electrically connected to all the cut-off valves, the first valve, the second valve, the electric heater, the automatic drain valve, the thermometer, the muffler and the check valve respectively.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The online water removal system provided by the present invention sequentially connects a buffer tank, a cold dryer, an adsorption device and an air storage tank on the air pipe at the outlet of the air compressor, and utilizes the principle of freezing dehydration + adsorption dehydration to effectively remove moisture from the compressed air, reduce the dew point temperature, and ensure that the dew point temperature of the compressed air is ≤-40°C, thereby improving the dryness of the air used by the pneumatic equipment, avoiding the condensation of water vapor into water at low temperature, which causes corrosion, blockage and freezing inside the pipeline, valve or equipment, and extending the service life of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the online water removal system of the present invention; In the figure: 1: air compressor; 2: buffer tank; 3: cold dryer; 4: adsorption device; 5: air storage tank; 6: PLC programmable controller; A: first adsorption tower; B: second adsorption tower; G1: air duct; G2: first drainage pipe; G3: second drainage pipe; G4: first branch pipe; G5: second branch pipe; Q1, Q2, Q3, Q4, Q5, Q6: cut-off valve; P1: first valve; P2: second valve; J: electric heater; H: automatic drain valve; T: thermometer; X: muffler; Z: check valve. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the accompanying drawings: like Figure 1 As shown, the present invention is an instrument air online dehydration system, including an air compressor 1 arranged at the front end of the system, and the outlet of the air compressor 1 is connected to the buffer tank 2, the cold dryer 3, the adsorption device 4 and the air storage tank 5 in sequence through the air pipe G1. Specifically, the air compressor 1 uses a screw air compressor, and a pair of mutually meshing spiral rotors rotate in the shell. As the rotor rotates, the volume of the cavity between the threads gradually decreases, and the gas is continuously compressed. The compressed oil-gas mixture enters the oil-gas separation tank, and most of the oil is separated by collision, interception, gravity separation and other methods to obtain cleaner compressed air. The whole machine has air cooling and oil separation functions. The buffer tank 2 provides a space for temporary storage of compressed air in the compressed air system, and plays a role in smoothing pressure fluctuations and ensuring the pressure stability of downstream gas-using equipment. The cold dryer 3 mainly functions to reduce the moisture content in the compressed air, ensure the normal operation of the pneumatic equipment and extend the life of the equipment, and avoid corrosion, freezing, equipment failure and product contamination caused by moisture. The adsorption device 4 removes moisture, oil mist and impurities to achieve the air quality standards required for different applications. The function of the air storage tank 5 is to store compressed air, and the air storage tank 5 can effectively mitigate air pressure fluctuations, provide stable pressure for downstream gas-using equipment, and improve the stability of the production process and product quality.

[0018] The adsorption device 4 includes two parallel-connected first adsorption towers A and second adsorption towers B. The first adsorption tower A and the second adsorption tower B both have a ventilation volume of 600 Nm 3 / min existing adsorption tower, which adopts carbon steel shell, uses grid plate at the bottom of the interior, adds adsorbent in the middle, and fixes the top of the adsorbent with grid plate; the adsorbent uses activated alumina, which has extremely high specific surface area and can effectively adsorb moisture in the air. When the humid compressed air passes through the first adsorption tower A and the second adsorption tower B, the moisture is captured by the micropores on the surface of the adsorbent, thereby achieving the effect of drying the air. During the operation of the system, the replacement condition of the adsorbent can be judged according to the pressure difference between the inlet and outlet of the adsorption tower, and the pressure difference needs to be replaced when it is greater than 0.1Mpa. The air pipeline G1 connecting the cold dryer 3 and the first adsorption tower A and the second adsorption tower B is respectively provided with a shut-off valve Q2 and a shut-off valve Q5, and the air pipeline G1 at the top inlet position of the first adsorption tower A and the second adsorption tower B is provided with a check valve Z to prevent the two towers from cross-gasing during adsorption and regeneration, and the top air pipeline G1 is also provided with a shut-off valve Q1 and a shut-off valve Q4. The bottom of the first adsorption tower A and the second adsorption tower B is connected to the second drainage pipeline G3, and the second drainage pipeline G3 is respectively provided with a shut-off valve Q3 and a shut-off valve Q6. In order to avoid noise pollution in the factory and the environment, a silencer X is also provided on the second drainage pipe G3. The first adsorption tower A and the second adsorption tower B are both provided with a time relay. The air pipe G1 between the first adsorption tower A and the second adsorption tower B is connected to the first branch pipe G4 through a tee. The first branch pipe G4 is provided with an electric heater J, which is heated by a 380V AC power supply. According to the principle of high-pressure and low-temperature dehydration of compressed air and low-pressure and high-temperature regeneration, the moisture in the adsorption device 4 is discharged from the bottom of the adsorption device 4 through hot water, ensuring that the temperature of the regeneration and drainage process of the adsorption device 4 meets the standard.

[0019] The bottom of the buffer tank 2, the cold dryer 3 and the air storage tank 5 are all connected to the first drainage pipe G2, and the first drainage pipe G2 is provided with an automatic drainage valve H. Among them, the automatic drainage valve H of the cold dryer 3 is an electrically controlled timed drainage valve, which automatically opens and closes the drainage port according to the preset time interval to drain water regularly; the automatic drainage valve H at the bottom of the air storage tank 5 is a float type automatic drainage valve, and there is a float inside the float type automatic drainage valve. As the condensed water accumulates in the drainage cavity, the float also rises. When the water level reaches a predetermined height, the float drives the connecting rod or magnetic coupling device to open the drainage valve to allow the condensed water to drain. As the water level drops, the float falls back, and the drainage valve is automatically closed under the action of the spring or gravity to prevent compressed air leakage. A thermometer T is provided on the air pipe G1 at the outlet of the cold dryer 3, and the air pipe G1 is also connected to the second branch pipe G5, and the second branch pipe G5 is provided with a first valve P1. A second valve P2 is provided on the air pipe G1 between the adsorption device 4 and the air storage tank 5 near the air storage tank 5. The first valve P1 and the second valve P2 are used to deliver compressed air to the air storage tank 5 through the second branch pipeline G5 in the event of a failure of the adsorption tower or normal maintenance, to ensure continuous air supply and production continuity.

[0020] The time relay is electrically connected to the signal input end of the PLC programmable controller 6, and the signal output end of the PLC programmable controller 6 is electrically connected to the cut-off valve Q1, the cut-off valve Q2, the cut-off valve Q3, the cut-off valve Q4, the cut-off valve Q5, the cut-off valve Q6, the first valve P1, the second valve P2, the electric heater J, the automatic drain valve H, the thermometer T, the muffler X and the check valve Z. When working, the time relay records the running time of the first adsorption tower A and the second adsorption tower B. When the time reaches the set time, the time relay feeds back the signal to the PLC programmable controller 6, and the PLC programmable controller 6 receives the signal to control the first adsorption tower A and the second adsorption tower B to switch operation. Specifically, the PLC programmable controller 6 switches the standby adsorption tower by controlling the cut-off valves Q1, Q2, Q6, or the cut-off valves Q3, Q4, Q5, ensuring that one tower performs adsorption drying while the other tower performs regeneration drainage treatment, thereby ensuring the continuous supply of compressed air. During operation, when the adsorption tower fails or is under normal maintenance, the PLC programmable controller 6 controls the second valve P2 to close, and uses the first valve P1 to send the compressed air to the air storage tank 5 through the second branch pipe G5 to ensure continuous air supply and production continuity. At the same time, the PLC programmable controller 6 also controls the operation of the electric heater J, the automatic drain valve H, the thermometer T, the muffler X and the check valve Z, wherein the electric heater J is used to ensure that the temperature of the regeneration and drainage process of the adsorption device 4 meets the standard, the automatic drain valve H is used for regular drainage, the thermometer T is used to observe the temperature index of the compressed air after cold drying, the muffler X is used to avoid noise pollution in the factory and the environment, and the check valve Z is used to prevent the two towers from cross-gasing during the adsorption and regeneration process. In this way, signal interlocking and automatic operation are achieved.

[0021] When working, the air pipe G1 at the outlet of the air compressor 1 is inserted into the bottom of the buffer tank 2, and the compressed air enters from the top of the buffer tank 2 to the bottom. The air pipe G1 at the top of the buffer tank 2 is connected to the inlet of the cold dryer 3 to achieve automatic drainage of the compressed air. The cold dryer 3 uses an air-cooled Freon refrigeration unit. The compressed air at the outlet of the buffer tank 2 is introduced into the evaporator of the cold dryer 3 to exchange heat with the low-temperature refrigerant. In this process, the temperature of the compressed air is significantly reduced, close to its dew point temperature, so that the moisture in the air condenses into liquid water and precipitates. A thermometer T is provided on the air pipe G1 at the outlet of the cold dryer 3 to facilitate the observation of the temperature index of the compressed air after cold drying. The index range is required to be 10-15°C. By referring to the thermometer T, the operating load of the cold dryer 3 can be adjusted in time to ensure the normal operation of the drainage system. The cold dryer 3 is connected to the two parallel first adsorption towers A and second adsorption towers B, one for standby and the other for switching operation, ensuring that one tower is performing adsorption drying while the other tower is performing regeneration and drainage treatment, so as to ensure the continuous supply of compressed air and meet production needs. The compressed air at the outlet of the cold dryer 3 enters from the bottom of the first adsorption tower A or the second adsorption tower B, and the dried compressed air is transported to the air storage tank 5 through the air pipe G1 at the top outlet of the first adsorption tower A or the second adsorption tower B, enters from the bottom of the air storage tank 5, and is transported to the user from the top of the air storage tank 5 through the air pipe G1.

[0022] The adsorption operation time of the first adsorption tower A is set to 1h, and the regeneration time of the second adsorption tower B is set to 1h, and the synchronous switching operation is realized through the PLC programmable controller. The switching logic is as follows: when the first adsorption tower A is adsorbing and the second adsorption tower B is regenerating, the PLC programmable controller synchronously controls the closing of the cut-off valve Q3, opens the cut-off valves Q1 and Q2, closes the cut-off valves Q4 and Q5, and opens the cut-off valve Q6. After running for 1h, the time relay transmits the signal to the PLC programmable controller, and the PLC programmable controller receives the signal to switch the second adsorption tower B to adsorb and the first adsorption tower A to regenerate. At this time, the PLC programmable controller synchronously controls the closing of the cut-off valves Q1, Q2, and Q6, and opens Q3, Q4, and Q5. The above control program can set the cycle operation mode through the PLC programmable controller.

[0023] The dew point temperature of compressed air required by the instrument equipment is ≤-40℃, so during the operation of the system, the dew point temperature of the compressed air is measured to confirm whether the water content of the compressed air meets the standard. The dew point temperature measured this time is -52℃, indicating that the dew point temperature of the compressed air meets the requirements and its water content meets the standards, and can be used for instrument air. Therefore, the water content of the instrument air prepared by this system meets the requirements, which solves the problem of high water content in the preparation process of instrument air, prolongs the service life of the equipment, and improves the test accuracy.

Claims

1. An instrument air online dehumidification system, comprising an air compressor (1), Features: The outlet of the air compressor (1) is sequentially connected to the buffer tank (2), the cold dryer (3), the adsorption device (4) and the air storage tank (5) through an air pipeline (G1).

2. An instrument air online dehumidification system as claimed in claim 1, Features: The adsorption device (4) comprises two first adsorption towers (A) and second adsorption towers (B) connected in parallel; a shut-off valve Q2 and a shut-off valve Q5 are provided on the air pipe (G1) connecting the cold dryer (3) with the first adsorption tower (A) and the second adsorption tower (B); a check valve (Z) is provided on the air pipe (G1) at the top of the first adsorption tower (A) and the second adsorption tower (B); and a shut-off valve Q1 and a shut-off valve Q4 are provided on the air pipe (G1) at the top; and a time relay is provided on the first adsorption tower (A) and the second adsorption tower (B).

3. An instrument air online dehumidification system as claimed in claim 2, Features: The bottoms of the buffer tank (2), the cold dryer (3) and the air storage tank (5) are all connected to a first drainage pipe (G2), and the first drainage pipe (G2) is provided with an automatic drainage valve (H).

4. An instrument air online dehumidification system as claimed in claim 3, Features: The bottoms of the first adsorption tower (A) and the second adsorption tower (B) are connected to a second drainage pipe (G3), and a shut-off valve Q3 and a shut-off valve Q6 are respectively provided on the second drainage pipe (G3).

5. An instrument air online moisture removal system as claimed in claim 4, Features: The first adsorption tower (A) and the second adsorption tower (B) are connected via an air pipeline (G1), and the air pipeline (G1) is connected to a first branch pipeline (G4), and the first branch pipeline (G4) is provided with an electric heater (J).

6. An instrument air online moisture removal system as claimed in claim 5, Features: The air pipeline (G1) at the outlet of the cold dryer (3) is connected to a second branch pipeline (G5), and a first valve (P1) is provided on the second branch pipeline (G5).

7. An instrument air online moisture removal system as claimed in claim 6, Features: A second valve (P2) is provided on the air pipeline (G1) between the adsorption device (4) and the air storage tank (5).

8. An instrument air online moisture removal system as claimed in claim 7, Features: The second drainage pipe (G3) is provided with a muffler (X).

9. An instrument air online moisture removal system as claimed in claim 8, Features: A thermometer (T) is provided on the air duct (G1) at the outlet of the cold dryer (3).

10. An instrument air online moisture removal system as claimed in claim 9, Features: The time relay is electrically connected to a signal input end of a PLC programmable controller (6), and the signal output end of the PLC programmable controller (6) is electrically connected to the cut-off valve Q1, the cut-off valve Q2, the cut-off valve Q3, the cut-off valve Q4, the cut-off valve Q5, the cut-off valve Q6, the first valve (P1), the second valve (P2), the electric heater (J), the automatic drain valve (H), the thermometer (T), the muffler (X) and the check valve (Z), respectively.

Images