Automatic liquid replenishment system for the mechanical seal of the oxidation kettle

Abstract

The present application discloses an automatic liquid replenishing system for the mechanical seal of an oxidation kettle, which has a liquid storage tank, Pump A, the liquid chamber of a balance cylinder, and the liquid seal chamber of a mechanical seal arranged in sequence along the liquid flow path; there is also a compressed air tank B, a pneumatic pump B, and the gas chamber of the balance cylinder arranged in sequence along the gas flow path. Between the gas chamber and the liquid chamber is a cylinder piston, and the reciprocating motion of the piston can change the relative volume sizes of the two chambers. There is also a controller. A liquid level signaler is connected to the liquid chamber, and the controller controls the start and stop of Pump A and the pneumatic pump B respectively, so as to maintain the liquid level within a suitable range between two liquid level sensors. Through the automatic control of the controller, the present invention can effectively avoid the damage of the mechanical seal due to water shortage and improve the service life of the mechanical seal parts.

Description

Technical Field

[0001] The present invention relates to a liquid replenishment technology for mechanical seals. Background Art

[0002] Mechanical seal is a shaft sealing device for rotating machinery, such as centrifugal pumps, centrifuges, reactors, compressors and other equipment. Since the drive shaft runs through the inside and outside of the equipment, there is a circumferential gap between the shaft and the equipment. The medium in the equipment leaks out through this gap. If the pressure inside the equipment is lower than the atmospheric pressure, air leaks into the equipment. Therefore, a shaft sealing device to prevent leakage is necessary.

[0003] The key to the success of mechanical seal is to form and maintain a liquid film with a certain thickness, and a reasonable unit area pressure must be controlled between the end faces to maintain this liquid film, so as to obtain a high level of mechanical seal technology and effectively extend the service life of the mechanical seal.

[0004] Glyphosate is a systemic, highly effective, broad-spectrum, pollution-free and safe herbicide, which occupies a large proportion in the global pesticide market. The common synthesis routes of glyphosate are divided into glycine route and iminodiacetic acid (IDA) route. The IDA method uses iminodiacetic acid as the main raw material, synthesizes glyphosate via glyphosate-methylphosphonic acid and then oxidizes it. During the preparation process, the oxidation reaction needs to be carried out in an oxidation kettle through the stirring action of the paddle. During the use of the oxidation kettle stirring, the seal of the stirrer is prone to overheat and burn out due to lack of water, which will affect the production. The by-product formaldehyde in this reaction is a highly hazardous chemical, which is highly irritating to mucous membranes, the upper respiratory tract, eyes and skin.

[0005] Therefore, the sealing performance of its mechanical seal needs to be well guaranteed. The replenishment of the liquid (water or oil) in the traditional oxidation kettle mechanical seal is manually controlled, and it is impossible to replenish water in a timely, accurate and effective manner. The mechanical seal is often damaged, and the maintenance rate is high, which seriously affects the use and production progress of the oxidation kettle. The leakage of the mechanical seal poses a hazard to human beings and the environment. Summary of the Invention

[0006] Object of the Invention:

[0007] To provide an automatic liquid replenishment system for the mechanical seal of an oxidation kettle that can automatically replenish the liquid in the mechanical seal, ensure proper metering and high safety.

[0008] Technical Solution:

[0009] The present invention provides an automatic liquid replenishing system for the mechanical seal of an oxidation kettle, which has a liquid storage tank, a pump A (preferably a pneumatic pump, equipped with a compressed air tank A, avoiding the use of an electric pump, which does not generate electric sparks and has high safety for oxidizing materials. Compressed air is on the left side, pneumatically driving the liquid, without electricity, safe and explosion-proof), a liquid chamber of a balance cylinder (having a liquid chamber, a piston, and a gas chamber from top to bottom), and a liquid seal chamber of a mechanical seal arranged in sequence according to the liquid flow path; there are also a compressed air tank B (compressed air on the right side, entering the lower chamber of the balance cylinder, driving the piston to move upward, the liquid enters the upper chamber of the balance cylinder, and enters or returns to the mechanical seal to play a sealing role), a pneumatic pump B, and a gas chamber of the balance cylinder arranged in sequence according to the gas flow path.

[0010] There are a liquid transfer channel and a liquid return channel between the liquid chamber of the balance cylinder and the liquid seal chamber of the mechanical seal, so that the liquid volume in the liquid seal chamber can change in a timely manner following the movement of the piston in the balance cylinder.

[0011] Between the gas chamber and the liquid chamber is a cylinder piston. The reciprocating movement of the piston can change the relative volume sizes of the two chambers, thereby adjusting the amount of liquid entering or returning to the liquid seal chamber of the mechanical seal, so that the sealing performance of the liquid seal chamber changes accordingly, and it can effectively prevent the mechanical seal from being damaged due to lack of liquid in the liquid seal chamber of the mechanical seal.

[0012] The balance cylinder housing has a cooling water coil, which is convenient for cooling the balance cylinder body, reducing the liquid temperature, preventing overheating and overpressure, and preventing liquid gasification from affecting the lubrication and sealing effects of the mechanical seal parts.

[0013] There may be an accumulator between the pneumatic pump A and the balance cylinder (when combined with the following soft water medium, the accumulator can be used for pressure accumulation. A simple oil seal cannot generate pressure and the accumulator has no pressure accumulation function). When the upper piston plate is between the two sensors, the pneumatic pump A can be turned on for a while longer, and the surplus liquid and its potential energy are temporarily stored in the accumulator, which is convenient for timely compensating the liquid in the balance cylinder without the need to start and stop the pneumatic pump A too frequently.

[0014] There may be a pressure relief valve between the pneumatic pump A and the accumulator. Another branch of the pressure relief valve is connected to the liquid storage tank, which is convenient for discharging the excessive liquid (or the air pressure of the pump A) in the pipeline and returning it to the liquid storage tank.

[0015] The combined application of the accumulator and the pressure relief valve enables the amount of liquid in the balance cylinder and the pressure in the pneumatic pump B to maintain a good Dongtai balance, with stronger self-adjusting ability. A small amount of energy surplus in the pipeline can be collected and utilized, but there will be no excessive pressure, and it will not affect the sealing effect of the system too much.

[0016] The preferred liquid is soft water (good water quality to avoid precipitation and scaling of inorganic substances), rather than an oil agent. The mechanical seal uses soft water as the liquid seal; preferably, there is a water-resistant sealing ring around the contact area between the mechanical seal and the soft water (preferably an ethylene propylene diene monomer (EPDM) rubber sealing ring, which has good weather resistance, ozone resistance, water resistance, and chemical resistance). This mechanical seal is used for the seal of the oxidation kettle to prevent oil from coming into contact with oxides, which is prone to combustion and explosion. At the same time, the surface tension of water is greater than that of general oil agents, and it is less likely to leak at the seal. Even if there is leakage, water is easy to volatilize (especially when the mechanical seal generates heat due to friction after use, causing the water to vaporize and volatilize), while oil is likely to contaminate the mechanical surface.

[0017] Preferably, there is a filter and pressure reducing two-piece between the compressed air tank A and the pneumatic pump A. Gas purification reduces the wear of the gas chamber of the balance cylinder and the balance cylinder piston, extending the service life; pressure reduction ensures that the pressure of the pneumatic pump A is not too high, the liquid flow is gentle, and the pressure regulation of the balance cylinder is gentle.

[0018] There is also a controller, which is respectively connected to control the start and stop of the pneumatic pump A and the pneumatic pump B; or is connected to control the pressure relief valve.

[0019] In addition, a liquid level signaler is connected to the liquid chamber. The liquid level signaler can respectively connect to collect the liquid level signals of the upper and lower two liquid level sensors.

[0020] There is a signal connection line between the liquid level signaler and the controller. When the upper and lower two liquid level sensors are respectively touched or not touched by the upper piston plate, the controller respectively controls the start or stop of the pneumatic pump A and the pneumatic pump B, so as to maintain the liquid level within a suitable range between the upper and lower two liquid level sensors.

[0021] That is, when the upper piston plate is lower than the lower liquid level sensor, it indicates that the liquid chamber is too large and the liquid is too much. The controller controls the pneumatic pump B to start or accelerate the flow, so that more compressed air enters the gas chamber, pushing the piston upward. At this time, the pressure relief valve can be opened to let the liquid flow back to the liquid storage tank. When the upper piston plate is higher than the upper liquid level sensor, it indicates that the liquid chamber is too small and the liquid is too little. The controller controls the pneumatic pump A to start or accelerate the flow, and the liquid compensates and enters the liquid chamber.

[0022] Preferably, the air pressure generated by the pneumatic pump A is greater than the air pressure generated by the pneumatic pump B, and the pressure difference between the two is between 0.2 MPa and 0.6 MPa. This enables the pressure difference to maintain a suitable liquid height and pressure in the liquid chamber, without being too high, avoiding leakage and increasing the load on the balance rod, thus ensuring a suitable liquid volume and liquid pressure required for maintaining the seal in the mechanical seal.

[0023] After the pneumatic pump or the accumulator, there can be multiple units composed of a balance cylinder, a mechanical seal, and compressed air B connected in parallel, enabling the liquid storage tank to be shared for replenishing liquid for multiple mechanical seals.

[0024] Beneficial effects:

[0025] The mechanical seal automatic water replenishing system has high stability. Through the automatic control of the controller, it can effectively prevent the mechanical seal from being damaged due to water shortage, timely replenish the lacking liquid or return the excess liquid, improve the service life of the mechanical seal, reduce the failure rate of the equipment, and reduce the impact of mechanical seal maintenance on production. At the same time, the combined use of the accumulator and the pressure relief valve effectively ensures the stable operation of production, saves energy, reduces consumption, and increases efficiency and reduces costs. Description of the drawings

[0026] Figure 1 It is a schematic diagram of the connection structure of the sealing liquid system components of the water replenishing system of the present invention;

[0027] In the figure, 1 - liquid storage tank; 2 - filter; 3 - liquid valve; 4 - filter and pressure reducing two - piece; 5 - pneumatic pump; 6 - pressure relief valve; 7 - accumulator; 8 - controller; 9 - gas valve; 10 - mechanical seal; 11 - liquid level signaler (including two liquid level sensors); 12 - liquid chamber; 13 - balance cylinder; 14 - gas chamber. Specific embodiments

[0028] As Figure 1 shown in the oxidation kettle mechanical seal automatic liquid replenishing system, there is a liquid storage tank, pump A, the liquid chamber of the balance cylinder, and the liquid seal chamber of the mechanical seal arranged in sequence according to the liquid flow path; there is also a compressed air tank B, pneumatic pump B, and the gas chamber of the balance cylinder arranged in sequence according to the gas flow path. Between the gas chamber and the liquid chamber is a cylinder piston, and the reciprocating movement of the piston adjusts the amount of liquid entering or flowing back into the liquid seal chamber of the mechanical seal. There is an accumulator between the pneumatic pump A and the balance cylinder, and the surplus liquid and its potential energy are temporarily stored in the accumulator. There is a pressure relief valve between the pneumatic pump A and the accumulator.

[0029] There is also a controller, which is respectively connected to control the start and stop of the pneumatic pump A and the pneumatic pump B; in addition, a liquid level signaler is connected to the liquid chamber, and there is a signal connection line between the liquid level signaler and the controller. The liquid level signaler can respectively connect to collect the liquid level signals of the upper and lower two liquid level sensors; the controller respectively controls the start or stop of the pneumatic pump A and the pneumatic pump B to maintain the liquid level between the upper and lower two liquid level sensors.

[0030] The above - mentioned mechanical seal automatic water replenishing system may include the following operation steps:

[0031] Startup step:

[0032] (1) Turn on the right compressed air source and stabilize the compressed air pressure at 0.7 MPaG. (2) Confirm that the remote pressure, i.e., the pressure of the liquid replenishment system, is stable at 1.05 MPaG. (3) Open the valve at the pressurizing port of the balance tank (balance cylinder) and increase the pressure in the gas chamber of the balance tank to the operating pressure of 0.6 MPaG. (5) Monitor the pressure in the system pipeline and whether the liquid levels in the liquid storage tank and the balance tank are normal.

[0033] Shutdown steps:

[0034] (1) Close the valve at the air filling port of the balance cylinder, open the vent hole of the instrument valve, and release the pressure in the gas chamber of the balance tank. (2) Open the valve at the liquid injection port, fill the sealing liquid within the piston limit range, and then close the valve at the liquid injection port. (3) Turn off the compressed air source and open the pressure relief valve to release the pressure in the liquid replenishment section.

Claims

1. An automatic liquid replenishing system for the mechanical seal of an oxidation kettle, characterized in that: There is a liquid storage tank, a pneumatic pump A, the liquid chamber of a balance cylinder, and the liquid seal chamber of a mechanical seal arranged in sequence along the liquid flow path; there is also a compressed air tank B, a pneumatic pump B, and the gas chamber of the balance cylinder arranged in sequence along the gas flow path. The balance cylinder is composed of the liquid chamber, a cylinder piston, and the gas chamber. There is an upper piston plate in the liquid chamber, and the cylinder piston is between the gas chamber and the liquid chamber; the reciprocating motion of the cylinder piston can adjust the amount of liquid entering the liquid chamber or flowing to the liquid seal chamber. There is also a controller that is respectively connected to control the start and stop of the pneumatic pump A and the pneumatic pump B. In addition, the liquid chamber is connected with a liquid level signaler. The liquid level signaler includes upper and lower liquid level sensors, and there is a signal connection line between the liquid level signaler and the controller. There is an accumulator between the pneumatic pump A and the balance cylinder. Excess liquid and its potential energy are temporarily stored in the accumulator, and there is a pressure relief valve between the pneumatic pump A and the accumulator. There are a liquid transfer channel and a channel for liquid reflux between the liquid chamber of the balance cylinder and the liquid seal chamber of the mechanical seal, so that the liquid volume in the liquid seal chamber changes in a timely manner following the movement of the piston in the balance cylinder. The liquid is soft water, and the mechanical seal uses soft water as the liquid seal. This mechanical seal is used as the machine seal of the oxidation kettle. The liquid level signaler can respectively connect to collect the liquid level signals of the upper and lower liquid level sensors; the controller respectively controls the start or stop of the pneumatic pump A and the pneumatic pump B to maintain the liquid level between the upper and lower liquid level sensors; when the upper piston plate is lower than the lower liquid level sensor, it indicates that the liquid chamber is too large and there is too much liquid. The controller controls the pneumatic pump B to start or accelerate the flow, so that more compressed air enters the gas chamber, pushing the cylinder piston upward. At this time, the pressure relief valve opens to allow the liquid to flow back to the liquid storage tank; when the upper piston plate is higher than the upper liquid level sensor, it indicates that the liquid chamber is too small and there is too little liquid. The controller controls the pneumatic pump A to start or accelerate the flow, and the liquid compensates and enters the liquid chamber. After the accumulator, there are multiple units composed of balance cylinders, mechanical seals, and compressed air connected in parallel, so that the liquid storage tank is shared for the liquid replenishment of multiple mechanical seals. The air pressure generated by the pneumatic pump A is greater than the air pressure generated by the pneumatic pump B, and the pressure difference between the two is between 0.2 MPa and 0.6 MPa. There is a circle of ethylene propylene diene monomer rubber seals at the place where the mechanical seal contacts the soft water.

Images