Method for preventing first reaction device from being pumped dry due to negative pressure of discharge pipeline

Abstract

The invention belongs to the technical field of seawater desalination operation control, and particularly relates to a method for preventing a first-reaction device from being pumped dry due to negative pressure of a discharge pipeline. The method comprises the following steps: 1, evaluating the maximum displacement and operation condition of a discharge pipeline; 2, a hole is formed in the top of the vertical pipe section, a short pipe with the diameter phi being 80 mm is additionally arranged, the rear portion of the short pipe is divided into two branches with the diameter phi being 50 mm, the branches are each provided with an automatic exhaust valve with the diameter phi being 50 mm, and a manual valve is installed in front of the automatic exhaust valves; and step 3, observing the effect after the installation is completed. The negative pressure prevention device is additionally arranged in an area where negative pressure is easy to form in the discharge pipeline, so that the primary reverse osmosis device is prevented from being pumped dry due to the negative pressure formed in the discharge pipeline during discharge, and reliable operation of the primary reverse osmosis device is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of seawater desalination operation control, and in particular relates to a method for preventing a desalination device from being drained due to negative pressure in a discharge pipeline. Background Art

[0002] The primary reverse osmosis device is used to further desalinate the ultrafiltration water through the primary reverse osmosis membrane, and the primary reverse osmosis water enters the primary fresh water tank. The process is that part of the ultrafiltration water enters the primary reverse osmosis energy recovery device to be pressurized (low pressure in), and the other part of the ultrafiltration water enters the high-pressure pump and passes through the primary reverse osmosis energy recovery device (high pressure out). The ultrafiltration water pressurized by the booster pump is mixed and enters the primary reverse osmosis device. The water inlet pressure is higher than the osmotic pressure. About 45% of the primary fresh water enters the primary fresh water tank, and 55% of the concentrated drainage pressure is high. In order to recover the concentrated drainage pressure energy, the concentrated drainage enters the primary reverse osmosis energy recovery device (high pressure in) to transfer the pressure energy to the ultrafiltration water entering at low pressure. After the concentrated drainage pressure energy is transferred, it is discharged to the sea (low pressure out). The concentrated brine discharge pipeline is connected to the seawater discharge main pipe. The pipelines connected to the seawater discharge main pipe include the low-pressure discharge pipeline of each reverse PX device, the neutralization tank discharge pipeline, the backwash drainage tank discharge pipeline, the outdoor trench drainage, etc.

[0003] Due to the complex working conditions of the discharge pipeline, the uncertainty of the discharge time and flow of each drainage pipeline, the superposition of multiple discharge pipelines, and the sudden increase in the flow rate through the vertical pipeline during discharge, negative pressure will be formed. The negative pressure formed in the drainage main pipe will cause negative pressure in the first-level reverse osmosis membrane and the first-level reverse osmosis PX energy recovery device, and the water in the system will be drained, which may cause damage to the membrane and dryness and non-rotation of the first-level reverse osmosis PX energy recovery device, thus making the first-level reverse osmosis system unusable.

[0004] The present invention studies how to prevent a primary reverse osmosis device from being drained due to negative pressure in a discharge pipeline, and proposes to add a negative pressure prevention device in a negative pressure area of ​​the discharge pipeline, so as to avoid the primary reverse osmosis device being drained due to negative pressure formed in the discharge pipeline during discharge, thereby ensuring the reliable operation of the primary reverse osmosis device. Summary of the invention

[0005] The low-pressure discharge pipeline of the first-stage reverse osmosis concentrated seawater is connected to the main discharge pipeline. The discharge pipeline forms a negative pressure during discharge, thereby draining the first-stage reverse osmosis device, causing the first-stage reverse osmosis membrane to lose water, affecting the safe operation of the membrane, and the first-stage reverse osmosis PX device to dry out and the rotor to stop rotating, making the first-stage reverse osmosis system unusable.

[0006] The purpose of the present invention is to provide a method for preventing a reverse osmosis device from being drained due to negative pressure in a discharge pipeline. A negative pressure prevention device is added to a negative pressure area of ​​the discharge pipeline that is prone to form negative pressure, so as to avoid the formation of negative pressure in the discharge pipeline during discharge, which may cause the first-stage reverse osmosis device to be drained, thereby ensuring the reliable operation of the first-stage reverse osmosis device.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for preventing a device from being drained due to negative pressure in a discharge pipeline.

[0009] Step 1: Evaluate the maximum discharge capacity and operating conditions of the discharge pipeline;

[0010] Step 2: Drill a hole at the top of the vertical pipe section and add a short pipe of φ80mm. The short pipe is divided into two branches of φ50mm. A φ50mm automatic exhaust valve is installed on each branch, and a manual valve is installed in front of the automatic exhaust valve.

[0011] Step 3: Observe the effect after installation.

[0012] The drainage of the discharge pipeline comes from: low-pressure discharge water of the first-level reverse osmosis energy recovery device; discharge water from the wastewater neutralization tank; discharge water from the backwash drainage tank; and discharge water from the outdoor trench.

[0013] The low-pressure discharge water of the primary reverse osmosis energy recovery device can be put into 4 trains at most, each with 470m 3 / h.

[0014] The rated discharge flow rate of the wastewater neutralization tank is 250m 3 / h.

[0015] Backwash drainage pool discharge water: two pumps in parallel discharge flow rate of 800m 3 / h.

[0016] The maximum discharge flow of the discharge pipeline is 470*4+250+800=2930m 3 / h.

[0017] The φ80mm short tube is made of fiberglass.

[0018] The φ50mm branch is made of PVC.

[0019] The automatic exhaust valve is made of PVC.

[0020] Whether the requirements are met can be determined by observing whether there is any suction sound from the automatic exhaust valve of the first-stage reverse osmosis safety filter when the system is in standby state.

[0021] The beneficial effects achieved by the present invention are:

[0022] The present invention adds a negative pressure prevention device to the discharge main pipe, reduces the pressure fluctuation of the discharge main pipe, makes the discharge condition of the discharge main pipe more stable, reduces vibration, and makes the pipeline safer and more reliable;

[0023] The present invention adds a negative pressure prevention device to the discharge main pipe to prevent the primary reverse osmosis membrane from being drained and losing water, thereby ensuring that the primary reverse osmosis membrane will not be damaged;

[0024] The present invention adds a negative pressure prevention device to the discharge main pipe to prevent the primary reverse osmosis membrane PX energy recovery device from being drained and causing the rotor to dry out and stop rotating, thereby reducing the unavailable time of the primary reverse osmosis PX energy recovery device system;

[0025] The present invention adds a negative pressure prevention device to the discharge main pipe, which can reduce the time of filling and exhausting the first-stage reverse osmosis, reduce the air intake of the system in the standby state, and reduce the corrosion of the first-stage reverse device due to air in the standby state;

[0026] The present invention adds a negative pressure prevention device to the discharge main pipe, which can reduce the fluctuation of low-pressure discharge volume caused by the pressure fluctuation of the discharge main pipe after the first reaction device is put into operation, thereby reducing the frequency of system flow regulation;

[0027] The negative pressure prevention device of the present invention adopts an automatic exhaust valve, which can realize automatic air suction, and the discharged water will not flow out. It has a simple structure and does not require human operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the negative pressure prevention process of the first-stage reverse osmosis device and the discharge main pipe. DETAILED DESCRIPTION

[0029] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] A method for preventing a device from being drained due to negative pressure in a discharge pipeline comprises the following steps:

[0031] Step 1: Evaluate the maximum discharge volume and operating conditions of the discharge pipeline; the discharge of the main discharge pipe of the Tianwan desalination project mainly comes from four aspects: low-pressure discharge water of the primary reverse osmosis energy recovery device; discharge water from the wastewater neutralization tank; discharge water from the backwash drainage tank; and discharge water from the outdoor pipe trench. The outdoor pipe trench discharge water is negligible, and the maximum flow rates of the other three drainage items are: concentrated discharge water of the primary reverse osmosis device: a maximum of 4 columns, each column is 470m 3 / h; Wastewater neutralization tank discharge water: rated discharge flow is 250m 3 / h; Backwash drainage pool discharge water: two pumps in parallel discharge flow rate is 800m 3 / h. The maximum discharge flow rate of the discharge main is 470*4+250+800=2930m 3 / h.

[0032] Step 2, design the size and installation position of the negative pressure prevention device; according to the on-site pipeline layout, the negative pressure of the discharge pipeline is mainly due to the sudden increase in flow velocity in the vertical section of the pipeline, forming a falling negative pressure, so a hole is opened at the top of this vertical pipe section, and a short pipe of φ80mm is added. The short pipe is divided into two branches of φ50mm, and a φ50mm automatic exhaust valve is installed on each branch, and a manual valve is installed in front of the exhaust valve (manual valve 1 and manual valve 2 in the figure); the φ80mm short pipe is made of fiberglass, and the φ50mm branch pipe and valve are made of PVC.

[0033] Step 3: Observe the effect after the negative pressure prevention device is installed; judge whether the negative pressure prevention device meets the requirements by observing whether there is any suction sound when the automatic exhaust valve of the first-level reverse osmosis safety filter is in standby mode.

[0034] The present invention discloses a method for preventing a primary reverse osmosis device from being drained due to negative pressure in a discharge pipeline. An automatic exhaust valve is added to a resin pipe section of a discharge main pipe as a negative pressure prevention device, the method has a simple structure and requires less operation personnel. The method reduces pressure fluctuations in a discharge main pipe, so that a discharge condition of the discharge main pipe is more stable, vibration is reduced, and the pipeline is safer and more reliable. The method prevents a primary reverse osmosis membrane from being drained and losing water, prevents a primary reverse osmosis membrane PX energy recovery device from being drained and causing a rotor to dry out and not rotate, reduces rusting of air entering the primary reverse osmosis equipment, reduces unavailable time of a primary reverse osmosis system, and avoids damage to the primary reverse osmosis system. The method can reduce fluctuations in low-pressure discharge volume caused by pressure fluctuations in the discharge main pipe after a reverse device is put into operation, and makes the system operation more stable.

Claims

1. A method for preventing a reaction device from being drained due to negative pressure in a discharge pipeline, characterized in that: Step 1: Evaluate the maximum discharge capacity and operating conditions of the discharge pipeline; Step 2: Drill a hole at the top of the vertical pipe section and add a short pipe of φ80mm. The short pipe is divided into two branches of φ50mm. A φ50mm automatic exhaust valve is installed on each branch, and a manual valve is installed in front of the automatic exhaust valve. Step 3: Observe the effect after installation.

2. The method for preventing a reaction device from being drained due to negative pressure in a discharge pipeline according to claim 1, characterized in that: The drainage of the discharge pipeline comes from: low-pressure discharge water of the first-level reverse osmosis energy recovery device; discharge water from the wastewater neutralization tank; discharge water from the backwash drainage tank; and discharge water from the outdoor trench.

3. The method for preventing a reaction device from being drained due to negative pressure in a discharge pipeline according to claim 2, characterized in that: The low-pressure discharge water of the primary reverse osmosis energy recovery device can be put into 4 trains at most, each with 470m 3 / h.

4. The method for preventing a reaction device from being drained due to negative pressure in a discharge pipeline according to claim 2, characterized in that: The rated discharge flow rate of wastewater neutralization tank discharge water is 250m 3 / h.

5. The method for preventing a reaction device from being drained due to negative pressure in a discharge pipeline according to claim 2, characterized in that: Backwash drainage pool discharge water: two pumps in parallel discharge flow rate of 800m 3 / h.

6. The method for preventing a reaction device from being drained due to negative pressure in a discharge pipeline according to claim 1, characterized in that: The maximum discharge flow of the discharge pipeline is 470*4+250+800=2930m 3 / h.

7. The method for preventing a reaction device from being drained due to negative pressure in a discharge pipeline according to claim 1, characterized in that: The φ80mm short tube is made of fiberglass.

8. The method for preventing a reaction device from being drained due to negative pressure in a discharge pipeline according to claim 1, characterized in that: The φ50mm branch is made of PVC.

9. The method for preventing a reaction device from being drained due to negative pressure in a discharge pipeline according to claim 1, characterized in that: The automatic exhaust valve is made of PVC.

10. The method for preventing a reaction device from being drained due to negative pressure in a discharge pipeline according to claim 1, characterized in that: Whether the requirements are met can be determined by observing whether there is any suction sound from the automatic exhaust valve of the first-stage reverse osmosis safety filter when the system is in standby state.

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