Drainage system and method for zero-emission recovery of condensate water of air compressor

Abstract

The invention belongs to the field of electrical control, and relates to a drainage system and method for zero-discharge recovery of condensate water of an air compressor, condensate water generated by a cooler of the air compressor is discharged through liquid level control of a steam trap and enters a water collecting tank through a three-way valve; gas and liquid are separated by the cyclone separator, the gas is subjected to pressure regulation by the check valve and the Venturi mixer and then returns to the air inlet filter of the air compressor for recycling, and the liquid is conveyed to a circulating water station by triggering the booster pump group through the liquid level switch. The system dynamically balances the air pressure through the pressure sensor and the venturi mixer, and realizes gas-liquid double-phase efficient recovery by combining with the logic of preventing frequent start and stop of the double-floating-ball liquid level switch. The system has the functions that the gas-liquid separation rate is larger than 98%, the energy consumption of a pump set is reduced by 40% or above, and one-key switching of an emergency pipeline is achieved, the problems that traditional condensate water is directly discharged, pollution is caused, energy is wasted, and the system reliability is poor are thoroughly solved, and the requirement for energy-saving transformation of air compressors in the industrial field is met.

Description

Technical Field

[0001] The invention belongs to the field of electrical control and relates to a drain system and method for zero-discharge recovery of condensed water from an air compressor. Background Art

[0002] As an important power source equipment in the industrial field, the problem of condensate treatment caused by temperature changes during the air compression process has always been a technical pain point in the industry. Traditional air compressor systems discharge condensate directly into the sewer pipe through a simple steam trap. This extensive treatment method not only wastes water resources, but also causes environmental problems such as soil pollution and pipeline corrosion due to the lubricating oil particles, metal oxides and other pollutants contained in the condensate. In recent years, with the strengthening of environmental protection regulations and the popularization of the concept of circular economy, zero-emission condensate recovery technology has become a core demand for the upgrading and transformation of air compressor systems.

[0003] Current status of technology development:

[0004] 1. Mechanical steam trap solution

[0005] In the early days, float-type and thermodynamic steam traps were commonly used to control drainage by sensing liquid level or temperature changes through mechanical structures. Although such devices are low-cost, they have the following inherent defects:

[0006] 1) The trap opening threshold is fixed and cannot adapt to the changes in condensate production caused by air compressor load fluctuations, resulting in drainage delays or malfunctions;

[0007] 2) The moving parts in the valve body are easily adhered by oil and dirt, and the risk of seizure failure after long-term operation is as high as more than 40%;

[0008] 3) No gas-liquid separation device is configured, and compressed air leaks during drainage, resulting in additional energy loss;

[0009] 2. Electronically controlled steam trap solution

[0010] The electronically controlled drain system based on liquid level sensor controls the opening and closing of the solenoid valve through PLC, which has improved the accuracy compared with the mechanical solution. However, it is found in actual application that:

[0011] 1) The life of the sensor probe is shortened to 6-8 months under high temperature (>80℃) and high humidity (PH value of condensed water <5) conditions;

[0012] 2) Single-point liquid level detection is easily disturbed by equipment vibration, with a false trigger rate of 15%-20%;

[0013] 3) The linkage control with the back-end recovery system was not established, and the drainage pump was frequently started and stopped, resulting in water hammer effect that damaged the pipeline;

[0014] 3. Simple recovery device solution

[0015] Some manufacturers use a physical recycling method that uses a water collection tank and a float switch, but this method has systemic defects:

[0016] 1) The open water tank design causes the compressed air and condensed water to be discharged together, and the gas-liquid separation efficiency is less than 60%;

[0017] 2) No water quality monitoring module is configured, and the oil and acidic substances in the recycled water directly enter the circulating water system, causing scaling of the heat exchanger and microbial growth;

[0018] 3) Emergency handling function is missing, and equipment failure requires shutdown for maintenance, affecting the continuity of the production line.

[0019] In summary, the existing technologies have the following problems: when the drainage device adopts redundant design to reduce the failure rate, the system energy consumption increases by more than 30%; the pursuit of efficient drainage leads to accelerated wear of components; the mixed gas-liquid discharge causes a loss of 0.3-0.5kW·h energy per cubic meter of compressed air; more than 75% of the existing devices do not integrate a pressure balance module, and the negative pressure state of the water collection tank causes cavitation damage to the drainage pump; the piping system does not consider temperature deformation compensation, and metal pipes above DN25 are prone to weld cracking due to thermal stress; more than 90% of the systems lack real-time data collection functions and cannot be traced The trend of water quality changes is correlated with the degradation of equipment performance; no fault prediction model has been established, and emergencies such as steam trap blockage and pump group abnormality still need to be discovered through manual inspections; the COD index of directly discharged condensate generally exceeds the standard by 2-5 times, facing the potential risk of environmental protection penalties; the direct discharge of untreated oil-water mixture into the sewage network violates the management regulations of the "National Hazardous Waste List"; traditional mechanical steam traps need to be disassembled and cleaned every quarter, and a single maintenance takes 4-6 hours; the failure rate of electronic components in a humid environment is 3.2 times that of a conventional industrial environment, and the cost of replacing spare parts accounts for more than 60% of the total maintenance cost.

[0020] Therefore, there is an urgent need for a new type of hydrophobic system that integrates intelligent control, efficient gas-liquid separation, online water quality monitoring, and system self-protection. Summary of the invention

[0021] In view of this, the object of the present invention is to provide a drainage system and method for zero-discharge recovery of air compressor condensate to solve the existing problems.

[0022] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a drain system for zero-discharge recovery of condensate from an air compressor, comprising an electronic liquid level controlled automatic drain trap, a condensate collecting device, an air circuit recovery pipeline and a remote monitoring unit; wherein the electronic liquid level controlled automatic drain trap is installed at the drain outlet of the air compressor cooler, and its power input end is connected to a newly added distribution box, and the drain trap body is provided with an operation indicator light, a fault alarm indicator light and a switch signal output interface; the condensate collecting device comprises a water collecting tank, a booster pump group and a liquid level switch, the water collecting tank is connected to the original drain pipe through a three-way pipeline, and manual valves are respectively arranged upstream and downstream of the three-way pipeline; one end of the air circuit recovery pipeline is connected to the exhaust port of the drain trap, and the other end is connected to the air intake filter of the air compressor, and a pressure sensor, a check valve and a venturi mixer are arranged on the pipeline in sequence; the remote monitoring unit is connected to the air compressor centralized control system through an RS485 communication interface to receive the drain trap fault signal and the liquid level switch status in real time.

[0023] Optionally, the fault signal output interface of the electronic liquid level controlled automatic steam trap is hard-wired to an alarm relay of a distribution box, which lights up a red light and sends a passive dry contact signal to a centralized control system when triggered.

[0024] Optionally, the branch pipe section of the three-way pipeline adopts a DN25 pipe, which is welded to the original drainage pipe at a 45° angle, and a leakage detection ring is provided at the weld.

[0025] Optionally, a cyclone separator is provided on the top of the water collecting tank, the inlet of which is connected to a three-way pipeline, and the outlet of which is connected to the suction pipe of the booster pump group through a flange;

[0026] The liquid level switch is a double float structure. The high-position float triggers the booster pump to start, and the low-position float delays 5 seconds to stop the pump. The signals of both are connected to the centralized control system through a shielded cable.

[0027] Optionally, a temperature-compensated flow meter is installed at the outlet end of the Venturi mixer of the gas recovery pipeline, and the data is connected to the centralized control system via a 4-20mA signal.

[0028] Optionally, the check valve is a spring-assisted structure, and the opening pressure is set to 0.05 MPa to prevent gas backflow when the air compressor is shut down.

[0029] Optionally, it also includes a water quality monitoring unit, which includes a pH probe and a turbidity sensor installed in the water collection tank, and the data is sent to the centralized control system through a wireless transmission module;

[0030] An accumulative water meter is arranged on the outlet pipe of the booster pump group, and the pulse signal of the water meter is connected to the control box through an optical coupler isolator.

[0031] A method for draining air compressor condensate with zero discharge recovery, using the draining system for zero discharge recovery of air compressor condensate as described above, comprises the following steps:

[0032] S1, the condensate level in the cooler is monitored in real time by the electronic level control automatic steam trap. When the level reaches the set height, the steam trap is opened and the discharged medium enters the water collecting tank through the three-way pipeline;

[0033] S2, the cyclone separator performs primary separation on the gas-liquid mixture, the gas returns to the air compressor intake end through the gas recovery pipeline, and the liquid remains in the water collection tank;

[0034] S3. The liquid level switch detects the liquid level in the water collecting tank. When the liquid level is high, the booster pump is started to transport the condensed water to the circulating water station. When the liquid level is low, the pump is stopped and the emergency discharge is switched to the original drain pipe.

[0035] S4. The water quality monitoring unit detects pH value and turbidity in real time. When the pH value and turbidity are exceeded, an audible and visual alarm is triggered and the booster pump operation is locked.

[0036] Optionally, in step S1, the number of operations of the steam trap is recorded each time it is turned on, and a maintenance warning is sent to the centralized control system when the frequency exceeds 50 times within 24 hours.

[0037] Optionally, in step S3, when the booster pump switches to operation, the control box first closes the outlet electric valve, and then starts and stops the pump after a delay of 10 seconds to prevent water hammer impact.

[0038] The beneficial effects of the present invention are:

[0039] 1) The cyclone separator and the Venturi mixer work together to achieve efficient separation and directional recovery of gas (compressed air) and liquid in condensed water. The gas is returned to the air intake of the air compressor after pressure regulation, and the liquid enters the circulating water system after purification. The comprehensive recovery rate is increased to more than 99.2%, completely eliminating direct discharge pollution.

[0040] 2) Integrated pH / turbidity sensor monitors water quality in real time. When excessive oil content (>15ppm) or acid corrosion (pH <6.5) is detected, it automatically switches to the emergency discharge pipeline and triggers the cleaning program to avoid the spread of pollution.

[0041] 3) Through the PID dynamic pressure regulation function of the Venturi mixer, the negative pressure effect caused by gas-liquid separation in the water collecting tank is eliminated, the power consumption of the booster pump is reduced by 40%-60%, and the risk of cavitation damage is avoided.

[0042] 4) The recovered compressed air carries waste heat (usually 50-70°C) and is fed back to the air compressor inlet through the mixer, which can reduce the intake air heating energy consumption by about 12%-18%.

[0043] The present invention not only solves the problems of high energy consumption, frequent failures, and serious secondary pollution in traditional drainage systems, but also realizes a technological leap from "passive drainage" to "resource recovery" through intelligent control and modular architecture. Compared with existing technologies, the comprehensive operation and maintenance costs are reduced by more than 45%, while meeting the requirements of energy saving and consumption reduction and green production. It is particularly suitable for industries such as metallurgy, automobile manufacturing, and food processing that are sensitive to environmental protection and energy efficiency.

[0044] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0046] Figure 1 It is a schematic diagram of the overall system of the present invention.

[0047] Figure numerals: steam trap 1, distribution box 2, water collecting tank 3, booster pump group 4, liquid level switch 5, valve 6, air compressor air intake filter 7, check valve 8, pressure sensor 9, Venturi mixer 10, cyclone separator 11, cumulative water meter 12, circulating water station 13, air compressor cooler 14. DETAILED DESCRIPTION

[0048] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0049] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0050] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "back" and the like indicate directions or positional relationships, they are based on the directions or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0051] See also Figure 1 The zero-discharge recovery and drainage system for condensate from air compressors in this embodiment is composed of the following components (connected in sequence):

[0052] 1. Condensate collection subsystem:

[0053] Air compressor cooler 14: condensate source, bottom drain port is connected to steam trap 1 through flange;

[0054] Steam trap 1: electronic liquid level control type, built-in double-electrode liquid level sensor, with fault alarm indicator light on the top;

[0055] Three-way valve 6: DN25 stainless steel ball valve, the main outlet is connected to the water collecting tank 3, and the bypass outlet is connected to the original drainage pipe;

[0056] Cyclone separator 11: installed at the air inlet of the water collecting tank 3 to achieve primary separation of gas and liquid;

[0057] 2. Gas recovery subsystem:

[0058] Check valve 8: DN20 stainless steel, to prevent gas from flowing back to the water collecting tank 3;

[0059] Pressure sensor 9: 4-20mA output, monitoring gas line pressure fluctuations;

[0060] Venturi mixer 10: throat diameter adjustable structure, outlet end connected to air compressor air intake filter 7;

[0061] 3. Water recovery subsystem:

[0062] Water collecting tank 3: Made of 304 stainless steel, with double float liquid level switch 5 installed on the top;

[0063] Booster pump group 4: one for use and one for standby, with Y-type filters and anti-water hammer buffer tanks installed at the inlet and outlet;

[0064] Accumulative water meter 12: mechanical digital type, connected in series on the pipeline from the pump group outlet to the circulating water station 13;

[0065] 4. Control unit:

[0066] Distribution box 2: integrated PLC controller, receiving the signal of liquid level switch 5 and pressure sensor 9, controlling the start and stop of steam trap 1 and booster pump group 4.

[0067] The steps for implementing the hydrophobic method include:

[0068] Step 1: Condensate generation and discharge control:

[0069] The condensed water generated when the air compressor cooler 14 is running enters the steam trap 1;

[0070] When the liquid level reaches the preset high position of steam trap 1 (electrode sensor is triggered), the drain valve is opened, and the water flows through the main path of valve 6 into the water collection tank 3;

[0071] If the steam trap 1 fails (continuous drainage for more than 5 minutes), the distribution box 2 triggers an alarm and automatically switches the valve 6 to the bypass, and the condensate is directly discharged to the emergency pipeline;

[0072] Step 2: Gas-liquid separation and gas recovery:

[0073] The gas-containing condensed water is centrifugally separated in the cyclone separator 11:

[0074] Liquid: settles to the bottom of the water collecting tank 3;

[0075] Gas: carries a trace amount of water mist and enters the Venturi mixer 10 through the check valve 8;

[0076] The pressure sensor 9 monitors the gas line pressure in real time and adjusts the throat diameter of the Venturi mixer 10 through the PID algorithm to make the gas pressure match the requirements of the air compressor intake filter 7;

[0077] The purified gas is finally returned to the air compressor intake system for recycling;

[0078] Step 3: Liquid storage and pressurized delivery:

[0079] The liquid level in the water collecting tank 3 is controlled by the double float liquid level switch 5:

[0080] High-level trigger (float lifts): start booster pump group 4 and close the drain valve of steam trap 1 to prevent backflow;

[0081] Low level trigger (float drops): delay 30 seconds to stop the pump to avoid frequent start and stop;

[0082] After the condensed water is pressurized by the booster pump group 4, the flow rate is measured by the cumulative water meter 12 and transported to the circulating water station 13 as cooling tower water replenishment;

[0083] Step 4: System protection and data feedback:

[0084] Anti-cavitation protection: When the pressure sensor 9 detects that the negative pressure of the gas circuit is greater than 0.05MPa, the pump is stopped immediately and the air supply valve of the steam trap 1 is opened;

[0085] Abnormal water quality treatment: If the turbidity sensor (built-in water collection tank 3) detects values ​​that exceed the standard, the valve 6 main route is automatically closed and switched to bypass discharge;

[0086] Data recording: The cumulative water meter 12 readings and fault codes are uploaded to the central control system via RS485.

[0087] In this embodiment, steam trap 1 is interlocked with valve 6; normal mode: drain valve of steam trap 1 is open → main circuit of valve 6 is open; maintenance mode: valve 6 is manually operated to switch to bypass, and steam trap 1 enters self-cleaning program.

[0088] In this embodiment, the liquid level switch 5 is linked to the booster pump group 4; the starting condition of the pump group 4: the high-level signal of the liquid level switch 5 + the normal pressure of the Venturi mixer 10 (0.2-0.4MPa); the forced pump stop condition: the low-level signal of the liquid level switch 5 lasts for 10 seconds, or the pump body temperature is greater than 85°C.

[0089] In this embodiment, the check valve 8 cooperates with the pressure sensor 9; the check valve 8 prevents gas backflow, and the pressure sensor 9 calibrates the opening of the Venturi mixer 10 in real time to ensure air pressure balance.

[0090] Specific embodiment 1,

[0091] In this embodiment, when the air compressor runs continuously for 8 hours, the steam trap 1 drains water once every 15 minutes, and the drainage volume is about 2L each time. After separation by the cyclone separator 11: the gas (accounting for 30% by volume) enters the gas recovery subsystem; the liquid (70%) is temporarily stored in the water collection tank 3;

[0092] Specific embodiment 2,

[0093] In this embodiment, when the liquid level of the water collecting tank 3 reaches 60% of the volume, the liquid level switch 5 triggers the booster pump group 4 to start at 8m 3 / h flow rate to the circulating water station 13;

[0094] Specific embodiment 3,

[0095] In this embodiment, the cumulative water meter 12 records the total water delivery, and the Venturi mixer 10 dynamically adjusts the air pressure to match the load change of the air compressor.

[0096] This embodiment builds a complete condensate water zero discharge closed loop by precisely controlling the drainage timing of the steam trap 1, coordinating the gas recovery of the cyclone separator 11 and the venturi mixer 10, and coordinating the water delivery of the double float liquid level switch 5 and the booster pump group 4. All components are connected with industrial standard interfaces, and can be adapted to mainstream brand air compressors without customized modification, which has significant engineering implementation convenience.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A drain system for zero-discharge recovery of condensate from air compressors, characterized by: It includes an electronic level-controlled automatic steam trap, a condensate collection device, a gas recovery line, and a remote monitoring unit; Among them, the electronic liquid level control automatic steam trap is installed at the drain outlet of the air compressor cooler, and its power input end is connected to the newly added distribution box. The steam trap body is equipped with an operation indicator light, a fault alarm indicator light and a switch signal output interface; The condensate collection device includes a water collecting tank, a booster pump group and a liquid level switch. The water collecting tank is connected to the original drainage pipe through a three-way pipeline, and manual valves are respectively provided upstream and downstream of the three-way pipeline; One end of the gas recovery pipeline is connected to the exhaust port of the steam trap, and the other end is connected to the air intake filter of the air compressor. The pressure sensor, check valve and Venturi mixer are arranged on the pipeline in sequence; The remote monitoring unit is connected to the air compressor centralized control system via the RS485 communication interface to receive the steam trap fault signal and liquid level switch status in real time.

2. The drainage system for zero-discharge recovery of air compressor condensate according to claim 1 is characterized in that: The fault signal output interface of the electronic liquid level control automatic steam trap is connected to the alarm relay of the distribution box through hard wiring. When triggered, the red light is turned on and a passive dry contact signal is sent to the centralized control system.

3. The drainage system for zero-discharge recovery of air compressor condensate according to claim 1 is characterized in that: The branch pipe section of the three-way pipeline adopts a DN25 pipe, which is welded to the original drainage pipe at a 45° angle, and a leakage detection ring is set at the weld.

4. The drainage system for zero-discharge recovery of air compressor condensate according to claim 1, characterized in that: A cyclone separator is arranged on the top of the water collecting tank, the inlet of which is connected to a three-way pipeline, and the outlet of which is connected to the suction pipe of the booster pump group through a flange; The liquid level switch is a double float structure. The high-position float triggers the booster pump to start, and the low-position float delays 5 seconds to stop the pump. The signals of both are connected to the centralized control system through a shielded cable.

5. The drain system for zero-discharge recovery of air compressor condensate according to claim 1, characterized in that: A temperature compensation flow meter is installed at the outlet end of the Venturi mixer of the gas recovery pipeline, and the data is connected to the centralized control system through a 4-20mA signal.

6. The drainage system for zero-discharge recovery of air compressor condensate according to claim 1, characterized in that: The check valve is a spring-assisted structure with an opening pressure set at 0.05 MPa to prevent gas backflow when the air compressor is shut down.

7. The drainage system for zero-discharge recovery of air compressor condensate according to claim 1, characterized in that: It also includes a water quality monitoring unit, which includes a pH probe and a turbidity sensor installed in the water collection tank, and the data is sent to the centralized control system through a wireless transmission module; An accumulative water meter is arranged on the outlet pipe of the booster pump group, and the pulse signal of the water meter is connected to the control box through an optical coupler isolator.

8. A method for draining air compressor condensate with zero discharge recovery, using a draining system for draining air compressor condensate with zero discharge recovery as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: S1, the condensate level in the cooler is monitored in real time by the electronic level control automatic steam trap. When the level reaches the set height, the steam trap is opened and the discharged medium enters the water collecting tank through the three-way pipeline; S2, the cyclone separator performs primary separation on the gas-liquid mixture, the gas returns to the air compressor intake end through the gas recovery pipeline, and the liquid remains in the water collection tank; S3. The liquid level switch detects the liquid level in the water collecting tank. When the liquid level is high, the booster pump is started to transport the condensed water to the circulating water station. When the liquid level is low, the pump is stopped and the emergency discharge is switched to the original drain pipe. S4. The water quality monitoring unit detects pH value and turbidity in real time. When the pH value and turbidity are exceeded, an audible and visual alarm is triggered and the booster pump operation is locked.

9. The method for draining air compressor condensate with zero discharge recovery according to claim 8, characterized in that: In step S1, the number of operations of the steam trap is recorded each time it is turned on, and a maintenance warning is sent to the centralized control system when the frequency exceeds 50 times within 24 hours.

10. The method for draining air compressor condensate with zero discharge recovery according to claim 8, characterized in that: In step S3, when the booster pump switches to operation, the control box first closes the outlet electric valve, and then starts and stops the pump after a delay of 10 seconds to prevent water hammer impact.

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