A high-temperature steam condensate water deoxygenation recycling system and method thereof

Abstract

This invention discloses a high-temperature steam condensate deoxygenation and reuse system and method, belonging to the field of high-temperature steam condensate recovery. It includes a deoxygenation device, a first online detection device, a first collection device, a deoxygenation reflux device, a second online detection device, a second collection device, and a third collection device. The lower outlet of the deoxygenation device is connected to the first online detection device, which is connected to the first collection device and the deoxygenation reflux device. The top outlet of the deoxygenation reflux device is connected to the second online detection device, which is connected to the second and third collection devices. The bottom outlet of the deoxygenation reflux device is connected to the top of the deoxygenation device. The first online detection device is used to detect the oxygen content, oil content, and conductivity of the condensate, while the second online detection device is used to detect the oil content and conductivity of the condensate. Using this system, this invention can reduce the dissolved oxygen content in water and reuse high-temperature condensate.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature steam condensate recovery, and is particularly applicable to the high-temperature steam condensate recovery process in the coking or petrochemical industries. Background Technology

[0002] Currently, there are two common types of steam condensate recovery systems: open-loop and closed-loop. Open-loop systems collect condensate in a tank open to the atmosphere and then pump it out. This leads to several problems: 50-70% of the heat released by the steam traps is lost; 5-20% of the total condensate is dissipated as softened water; it causes severe thermal pollution; deoxygenated water is secondary polluted by oxygen, and dissolved oxygen causes oxygen corrosion of the tanks and water-using equipment, altering the condensate quality and requiring retreatment. Closed-loop systems, on the other hand, centrally recover condensate at one or more pressure levels from a pressurized container. While avoiding the drawbacks of open-loop systems, the pressure difference between steam and condensate, as well as the pressure difference between condensate at different pressures, results in issues such as low back pressure condensate leakage, incomplete recovery, and even severe steam leakage from individual steam traps, which can increase the overall system back pressure and affect the normal operation of other traps. Therefore, complete condensate recovery is not always possible. Furthermore, it was found in practice that pump impellers are prone to cavitation when conveying high-temperature water, which affects the normal operation of the equipment.

[0003] For example, Chinese patent application No. 201020249591.3, with a publication date of February 16, 2011, discloses a closed-loop steam condensate recovery system. The system includes high-pressure and low-pressure condensate recovery pipelines. The high-pressure condensate recovery pipeline includes a condensate riser, a closed-loop condensate recovery unit, and a condensate transfer pump. High-pressure condensate is collected from the drain pipe to the main pipe by a heat-generating device, and then transported to the condensate recovery unit via the condensate riser. When the high-pressure condensate collected in the condensate recovery unit reaches a preset level, the level sensor inside transmits a signal to the condensate transfer pump, which starts and transports the high-pressure condensate to the deaerator. The low-pressure condensate recovery pipeline includes another condensate riser, another closed-loop condensate recovery unit, and another condensate transfer pump. Low-pressure condensate is collected from the drain pipe to another main pipe, and then passes through another condensate riser, another closed-loop condensate recovery unit, and another condensate transfer pump in sequence, before also sending low-pressure steam condensate to the deaerator. The output pipelines of the two condensate transfer pumps are connected. However, the patent application failed to describe and address the potential for condensate contamination in chemical plants. Furthermore, the use of demineralized water for cooling in closed-loop condensate return systems typically increases the oxygen content of the condensate, and direct entry of the condensate into the deaerator without deoxygenation would consume the heat of the condensate.

[0004] Chinese patent application No. 201410362085.8, published on February 10, 2016, discloses a steam condensate waste heat recovery system. The system includes a plate heat exchanger with a condensate outlet, a demineralized water outlet, a demineralized water cold water inlet, and a condensate hot water inlet. The condensate outlet is connected to a raw water tank, and the demineralized water outlet is connected to a deaerator via a main cold water pipe. The deaerator is connected to a boiler. The condensate hot water inlet is connected to a sulfur melting condensate return pipe and a phosphate fertilizer condensate return pipe. The condensate outlet and the condensate hot water inlet are connected via a hot water pipe; the demineralized water cold water inlet and the demineralized water outlet are connected via a cold water pipe. This invention, a steam condensate waste heat recovery system, reduces the amount of low-pressure steam required for deaerator heating and deoxygenation, saving steam; it also reduces raw water consumption and saves a significant amount of water resources. However, this method, through indirect heat exchange, can only indirectly recover the heat and water volume of the condensate. The clean condensate, after cooling, still needs to go through various processes in the demineralized water station for desalination again before it can enter the deaerator, wasting the capacity of the demineralized water station equipment and being detrimental to energy conservation and consumption reduction.

[0005] Chinese patent application No. 201110077178.2, published on October 10, 2012, discloses a closed-loop condensate recovery system. This system includes a boiler and a condensate tank. The upper end of the boiler is connected to a deaerator via a pipe. The deaerator is connected to one end of a soft water tank via a pipe. The other end of the soft water tank is connected to a soft water treatment exchanger. The soft water treatment exchanger is connected to a tap water inlet pipe, which is connected to the condensate tank via a condensate pipe. The top of the condensate tank is connected to low-pressure, medium-pressure, and high-pressure steam-using equipment via pipes. The tops of the low-pressure, medium-pressure, and high-pressure steam-using equipment are all connected to a desuperheater and pressure reducer via pipes. The desuperheater and pressure reducer are connected to the top of the boiler via valves. However, this patent application still treats clean condensate as if it were tap water with poor quality, requiring further cooling and softening via a soft water treatment exchanger. This wastes the equipment's capacity and is not conducive to energy conservation and consumption reduction.

[0006] Chinese patent application No. 202110972920.X, published on November 12, 2021, discloses a vertical high-temperature condensate deoxygenation device. This device includes a tank, a condensate distributor, a steam spraying device, and an exhaust treatment device. The tank is placed vertically, with the condensate distributor positioned at the center of the upper end cap. An exhaust pipe on the upper end cap is connected to the exhaust treatment device. The steam spraying device is located inside the tank and includes a steam pipe, a submerged steam plate connected to the steam pipe, and a rotating steam arm. The submerged steam plate is located at the bottom, and the rotating steam arm is positioned above the ideal liquid level. However, this device still relies on precious steam resources for deoxygenation, failing to effectively utilize the heat of the high-temperature condensate itself for effective deoxygenation, which is detrimental to energy conservation and consumption reduction.

[0007] Therefore, there is an urgent need to develop a high-temperature steam condensate deoxygenation and reuse system and method to effectively utilize the heat of the high-temperature condensate itself for effective deoxygenation. Summary of the Invention

[0008] 1. The problem to be solved

[0009] To address the problems existing in the prior art, the present invention provides a high-temperature steam condensate deoxygenation and reuse system and method thereof.

[0010] 2. Technical Solution

[0011] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0012] The system of this invention, based on conventional steam condensate recovery, reduces the dissolved oxygen content in the water and allows for the reuse of high-temperature condensate. Specifically:

[0013] A high-temperature steam condensate deoxygenation and reuse system includes a deoxygenation device, a first online detection device, a first collection device, a deoxygenation reflux device, a second online detection device, a second collection device, and a third collection device.

[0014] The upper inlet of the deoxygenation device is connected to a high-temperature condensate pipe, and the lower outlet of the deoxygenation device is connected to a first online detection device. The first online detection device is connected to a first collection device and a deoxygenation reflux device.

[0015] The top outlet of the deoxygenation reflux device is connected to the second online detection device, which is connected to the second and third collection devices; the bottom outlet of the deoxygenation reflux device is connected to the top of the deoxygenation device.

[0016] The first online detection device is used to detect the oxygen content, oil content and conductivity of the condensate, and the second online detection device is used to detect the oil content and conductivity of the condensate. The first online detection device and the second online detection device are used to control the flow direction of the condensate.

[0017] Furthermore, a spray head is installed above the upper water inlet in the deoxygenation device, and the bottom water outlet of the deoxygenation return device is connected to the spray head. The spray liquid flow rate at the outlet of the spray head is 3-10 m / s.

[0018] Furthermore, the deaerator contains several first screen plates arranged along its height, with adjacent first screen plates staggered. Each first screen plate is a circular screen plate with notches, divided into an effective screen plate area and a downcomer area. The effective screen plate area has several screen holes with a diameter of 6-10 mm. The downcomer area is a solid plate, with a downcomer plate located at the end of the effective screen plate area, connecting to the end of the effective screen plate area and facing downwards. An overflow weir plate is also located at the end of the effective screen plate area, facing upwards. Since the first screen plates are downcomer type, condensate flows horizontally through the screen plates and then vertically down to the next screen plate after passing through the downcomer. A small amount of gas passes vertically upwards through each screen plate, undergoing mass and heat transfer with the condensate on the screen plates before finally being discharged from the top of the deaerator.

[0019] Furthermore, the number of layers of the first sieve plate inside the deoxygenation device is 7 to 12.

[0020] Furthermore, the inlet of the deoxygenation reflux device is located in the middle of the side. Inside the device, several second screen plates are arranged along the height direction. Both the top and bottom outlets pass through these second screen plates for deoxygenation, gradually reducing the oxygen content in the condensate. Adjacent second screen plates are staggered. The number of second screen plate layers inside the device is 9-15. Each second screen plate is a circular screen plate with notches, and it has screen holes with a diameter of 6-12 mm. The second screen plates are submerged, meaning the deoxygenation reflux device is completely filled. Because of the deoxygenation process, the condensate contains only a small amount of oxygen. The oxygen rises and falls due to the screen holes and the gap between the screen plate and the inner wall of the device. The disturbance caused by the screen holes and the gap between the screen plate and the inner wall further precipitates out the oxygen, which rises and is eventually discharged. The lower oxygen content water at the bottom is pumped back to the deoxygenation device via a reflux condensate pump, while the higher oxygen content water at the top is pumped to subsequent processes via an external condensate pump.

[0021] Furthermore, the pressure inside the deoxygenation reflux device is 0 to -50 Pa. If it is positive pressure, the oxygen in the condensate will not easily escape. If the negative pressure is set too high, the net positive suction head (NPSH) of pumps such as the reflux pump will be insufficient.

[0022] Furthermore, the first online detection device includes an oxygen analyzer, a first oil analyzer, and a first conductivity meter; the second online detection device includes a second oil analyzer and a second conductivity meter.

[0023] Furthermore, a first heat exchanger is installed on the pipeline connecting the first online detection device to the deoxygenation reflux device; a second heat exchanger is installed on the pipeline connecting the deoxygenation reflux device to the second online detection device.

[0024] Furthermore, the lower outlet of the deaerator is supplied to the first online detection device via a hot water pump; the top outlet of the deaerator reflux device is supplied to the second online detection device via an external condensate pump; and the bottom outlet of the deaerator reflux device is supplied to the top of the deaerator via a reflux condensate pump. Both the external condensate pump and the reflux condensate pump are equipped with frequency conversion regulation.

[0025] Furthermore, the deaerator has a non-condensable gas outlet at the top and is connected to a third collection device. A pressure reducing valve and a third heat exchanger are sequentially installed on the connecting pipe. An vent is opened at the top of the third collection device.

[0026] Furthermore, a regulating valve is installed on the connecting pipe between the non-condensable gas outlet at the top of the deaerator and the third collection device, and the regulating valve is interlocked with the first online detection device.

[0027] All the pipes and devices mentioned above are made of 304 stainless steel to prevent secondary pollution of the water.

[0028] This invention proposes a method for recovering and utilizing steam condensate in the coking industry, which features low equipment cost, high thermal efficiency, production safety, and good deoxygenation effect. Details are as follows:

[0029] A method for deoxygenating and reusing high-temperature steam condensate employs the aforementioned system. A deoxygenation device cools and deoxygenates the high-temperature condensate (120℃~165℃) from the steam-using unit, thereby pre-reducing the oxygen content in the high-temperature condensate. The condensate at the outlet below the deoxygenation device is then monitored by a first online detection device.

[0030] When the oxygen content, oil content and conductivity detected by the first online detection device are lower than the set values, the condensate is transported to the first collection device, and the condensate of the first collection device is used as the feed water source for the medium-temperature and medium-pressure boiler.

[0031] When the oxygen content, oil content, or conductivity detected by the first online monitoring device is higher than the set value, the condensate is sent to the deoxygenation reflux device for deoxygenation treatment.

[0032] The oxygen content of the water effluent at the bottom of the deaeration reflux device is low, and it is transported to the top of the deaeration device as a cooling liquid for high-temperature condensate.

[0033] The oxygen content of the water effluent from the top of the deoxygenation reflux device is relatively high. After being detected by the second online detection device, when the oil content detected by the second online detection device is lower than the set value, the condensate is sent to the second collection device for delivery to the ultrafiltration water tank or RO permeate tank; when the oil content detected by the second online detection device is higher than the set value, the condensate is sent to the third collection device, and the condensate in the third collection device is used as the raw water for the demineralized water station.

[0034] The condensate in the first collection device is of better quality than that in the second collection device, and the condensate in the second collection device is of better quality than that in the third collection device, as shown in the following ways:

[0035] Condensate in the first collection device: water temperature 104~120℃, water pressure 0.11~0.25MPa, oil content less than 0.5mg / l, oxygen content less than 15μg / l, conductivity less than 6μs / cm;

[0036] The condensate in the second collection device should be at a temperature of 20–35°C, at atmospheric pressure, with an oil content of less than 1 mg / L and a conductivity of less than 30 μS / cm.

[0037] The condensate in the third collection device is maintained at a temperature of 20–35°C and atmospheric pressure, with an oil content greater than 1 mg / L and a conductivity greater than 30 μS / cm.

[0038] Furthermore, when the oil content detected by the second online detection device is lower than the set value and the conductivity value is higher than the set value, it is used to transport the water to the ultrafiltration tank; when the oil content detected by the second online detection device is lower than the set value and the conductivity value is lower than the set value, it is used to transport the water to the RO product tank.

[0039] Furthermore, the oxygen content setting of the first online detection device is 1-15 μg / l, the oil content setting is 0.1-0.5 mg / l, and the conductivity setting is 0.1-6 μs / cm.

[0040] Furthermore, the oil content setting value of the second online detection device is 0.3 to 1 mg / L, and the conductivity setting value is 4 to 30 μS / cm.

[0041] Furthermore, the condensate is transported to the pipeline of the deaeration reflux device and cooled to 65°C by the first heat exchanger; the water effluent from the top of the deaeration reflux device is cooled by the second heat exchanger and then transported to the second online detection device.

[0042] Furthermore, a condensate pump delivers condensate (60-65°C) from the bottom of the deaeration return unit to the deaeration unit for top spraying, cooling the high-temperature condensate within the deaeration unit to ensure the water temperature does not exceed 120°C. The condensate pump is interlocked with the pressure or temperature within the deaeration unit to ensure the temperature inside is below 120°C. An external condensate pump delivers the top effluent from the deaeration return unit to the second online monitoring device. This external condensate pump is interlocked with the upstream pressure to ensure the upstream pressure is 0 to -50 Pa.

[0043] Furthermore, the deaerator is also provided with a non-condensable gas outlet at the top, which is connected to a third collection device. A pressure reducing valve and a third heat exchanger are installed on the connecting pipe. After pressure reduction and cooling to room temperature, condensate is collected in the third collection device, and non-condensable gas is released from the vent at the top of the third collection device.

[0044] Furthermore, a regulating valve is installed on the connecting pipe between the non-condensable gas outlet at the top of the deaerator and the third collection device to regulate the oxygen content and interlock with the oxygen content data of the first online detection device.

[0045] 3. Beneficial effects

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] The high-temperature steam condensate deoxygenation and reuse system of the present invention has the following advantages in recovering steam condensate from the plant area:

[0048] (1) Considering that the temperature of the steam condensate collected in the plant area is high, if the closed condensate recovery device is used directly for recovery, the one-time investment cost is too large. Therefore, spraying at the top of the deoxygenation device can be used to reduce the temperature. In order to reduce heat loss, the spray liquid used in this invention comes from the condensate at the bottom outlet after deoxygenation by the deoxygenation return device and is recycled multiple times, which can further reduce the oxygen content in the water.

[0049] Determining the reflux ratio of the spray liquid based on the deoxygenation effect can effectively recover the heat of the high-temperature steam condensate while minimizing the oxygen content in the water. If the deoxygenation effect is poor, the deoxygenation reflux ratio can be increased to better utilize the deoxygenation capacity of the deoxygenation reflux device. However, the boundary condition for adjusting the reflux ratio is to ensure that the condensate temperature in the deoxygenation device is within the range of 104–120℃.

[0050] The spray volume is adjusted in real time based on the flow rate and temperature of the high-temperature condensate to ensure the overall stability of the system. This early warning is based on the readings of the flow meters and thermometers of the incoming high-temperature condensate, which is equivalent to feedforward control.

[0051] The flow rate of the spray liquid is interlocked with the pressure detection value inside the deaerator. If the pressure is high, the spray volume of the spray liquid increases. Spray liquid volume = total amount of high-temperature condensate before entering the deaerator × (temperature of high-temperature condensate after mixing before entering the deaerator - set temperature) / (set temperature - temperature of deaerator return condensate). In the above formula, the set temperature is generally 104~120℃, while the temperature of deaerator return condensate is generally 60~65℃.

[0052] The spray liquid used in this invention comes from the condensate at the bottom outlet of the deoxygenation reflux device; if it is necessary to recover steam condensate with a temperature below 120°C, such as refrigeration steam condensate, the spray liquid can be omitted for spray cooling, which simplifies the process.

[0053] (2) In this invention, a gas outlet is opened at the top of the deoxygenation device, and the temperature of 120°C in the deoxygenation device is used for pre-deoxygenation. A pressure reducing valve is installed on the pipeline after the gas outlet to maintain the pressure in the deoxygenation device and continuously discharge the non-condensable gas accumulated at the top of the deoxygenation device. The exhaust pipeline is then cooled by a heat exchanger, and the cooled gas-water mixture is sent to the demineralized water raw water tank as the raw water for the demineralized water station. The oxygen and other non-condensable gases in it are released from the vent at the top of the third collection device.

[0054] (3) In this invention, a first online detection device is set between the deoxygenation device and the deoxygenation reflux device and before the first heat exchanger to detect the oxygen content, oil content and conductivity. If the first online detection device detects that the dissolved oxygen content in the water is less than 15 μg / l and the oil content and conductivity are qualified, it can be directly sent to the first collection device, and the high-quality condensate can be directly used for boiler water in medium temperature and medium pressure, which saves energy well. If it is higher than the set value, it is sent to the deoxygenation reflux device for processing, and selectively transported to the second collection device, the third collection device or returned to the top of the deoxygenation device as spray liquid.

[0055] (4) The condensate recovery device of this application has low initial investment cost and good heat exchange effect: high temperature condensate has high requirements for the materials it comes into contact with. By spraying warm water on the top of the deoxygenation device, the system temperature can be effectively reduced to 120°C and below, which reduces the initial investment cost of materials such as hot water pumps in the system of this invention, and at the same time reduces the working pressure and temperature in the system.

[0056] (5) The present invention combines pre-deoxygenation and micro-negative pressure deoxygenation:

[0057] Traditional closed-loop condensate recovery devices are only used for condensate recovery. This invention combines the condensate recovery device with the deoxygenation device. By utilizing the high temperature of 120°C inside the device and the dispersing effect of the first screen plate, the condensate is pre-deoxygenated, and non-condensable gases are discharged in time through the pressure reducing pipeline.

[0058] Traditional deaerators use atmospheric pressure for deaeration, which requires heating. By using a slightly negative pressure deaeration reflux device, the temperature requirement can be reduced, saving resources. Moreover, the slightly negative pressure itself is conducive to the removal of oxygen from the condensate.

[0059] (6) The present invention provides both the reflux condensate pump and the external condensate pump with frequency conversion regulation interlocked with the relevant pressure, which can effectively maintain the stable operation of the system and ensure that the deoxygenation effect meets the standard.

[0060] (7) The oxygen content of the present invention is controlled by the regulating valve on the non-condensable gas discharge pipe at the top of the deoxygenation device. While controlling the oxygen content, unnecessary top gas discharge can also be reduced, thus saving energy. Attached Figure Description

[0061] Figure 1 This is a schematic diagram of the high-temperature steam condensate deoxygenation and reuse system of the present invention;

[0062] Figure 2 This is a schematic diagram of the structure of the first sieve plate of the present invention;

[0063] Figure 3 This is a schematic diagram of the structure of the second sieve plate of the present invention;

[0064] Figure 4 This is a schematic diagram of the internal structure of the deoxygenation device of the present invention;

[0065] In the picture:

[0066] 1. Deoxygenation device; 11. Spray head; 12. First sieve plate; 121. Effective sieve plate area; 122. Downcomer zone; 123. Downcomer tube sheet; 124. Overflow weir plate; 13. Hot water pump; 2. First collection device; 21. First online detection device; 211. Oxygen analyzer; 212. First oil analyzer; 213. First conductivity meter; 3. Deoxygenation reflux device; 31. First heat exchanger; 32. Second sieve plate; 4. Reflux condensate pump; 5. Second collection device; 51. External condensate pump; 52. Second heat exchanger; 53. Second online detection device; 531. Second oil analyzer; 532. Second conductivity meter; 6. Third collection device; 61. Drain port; 71. Pressure reducing valve; 72. Regulating valve; 73. Third heat exchanger. Detailed Implementation

[0067] The present invention will be further described below with reference to specific embodiments.

[0068] Example

[0069] This embodiment of a high-temperature steam condensate deoxygenation and reuse system includes a deoxygenation device 1, a first online detection device 21, a first collection device 2, a deoxygenation reflux device 3, a second online detection device 53, a second collection device 5, and a third collection device 6; wherein, the oxygen analyzer and conductivity meter in the first online detection device 21 and the second online detection device 53 can be products of Mettler Toledo, and the oil analyzer can be products of Medex or Xi'an Yingrun Environmental Protection Co., Ltd. For example... Figure 1 As shown, specifically:

[0070] The deaerator 1 contains several first sieve plates 12 arranged along its height, with adjacent first sieve plates 12 staggered. Each first sieve plate 12 is a circular sieve plate with notches. Figure 2 As shown, it is divided into an effective sieve plate area 121 and a descending zone 122. The effective sieve plate area 121 has several sieve holes with a diameter of 6-10 mm. The descending zone 122 is a solid plate. Figure 4 As shown, the downcomer plate 123 is located at the end of the effective sieve plate area 121. The downcomer plate 123 is connected to the end of the effective sieve plate area 121 and is set downwards. At the same time, an overflow weir plate 124 is set at the end of the effective sieve plate area 121 and is set upwards. The first sieve plate 12 is a downcomer type sieve plate. After the condensate flows horizontally through the sieve plate, it flows vertically down to the next layer of sieve plate after passing through the downcomer. A small amount of gas passes vertically through each layer of sieve plate from bottom to top. After mass and heat transfer with the condensate on the sieve plate, it is finally discharged from the top of the deaerator 1. The number of layers of the first sieve plate 12 inside the deaerator 1 is 7 to 12. The inlet of the deaerator 1 is located at a high position in the vertical direction, and the outlet of the deaerator 1 is located at a lower position on its side. The outlet is connected to the first online detection device 21. A hot water pump 13 is installed on the pipe between the outlet and the first online detection device 21. The first online detection device 21 includes an oxygen analyzer 211, a first oil analyzer 212, and a first conductivity meter 213. The first online detection device 21 is connected to the first collection device 2 and the deaerator return device 3. Condensate that passes the set value of the first online detection device 21 is transported to the first collection device 2, and condensate that does not pass the set value of the first online detection device 21 is transported to the deaerator return device 3. In order to reduce the damage to the pipe caused by high temperature, a first heat exchanger 31 is installed on the pipe connecting the first online detection device 21 and the deaerator return device 3 to cool the condensate in the pipe to about 65°C.

[0071] The inlet of the deoxygenation reflux device 3 is located in the middle of the side. Inside the device, several second screen plates 32 are arranged along the height direction. Both the top and bottom outlets pass through these second screen plates 32 for deoxygenation, gradually reducing the oxygen content in the condensate. Adjacent second screen plates 32 are staggered. The number of layers of second screen plates 32 inside the deoxygenation reflux device 3 is 9 to 15. Figure 3As shown, the second sieve plate 32 is a circular sieve plate with notches, and sieve holes with a diameter of 6-12 mm are distributed on it. The second sieve plate is a submersible sieve plate, that is, it is filled in the deoxygenation reflux device 3. Because it has been deoxygenated by the deoxygenation device 1, the condensate contains only a small amount of oxygen. It rises and falls by relying on the sieve holes on the sieve plate and the gap between the sieve plate and the inner wall of the device. Through the disturbance effect of the sieve holes and the gap between the sieve plate and the inner wall of the device, the oxygen in the liquid is further released, rises and is finally discharged. The water with lower oxygen content at the bottom is sent to the deoxygenation device by the reflux condensate pump 4, and the water with higher oxygen content at the top is sent to the subsequent process by the external condensate pump 51. The deoxygenation reflux device 3 has outlets at both its top and bottom. The top outlet of the deoxygenation reflux device 3 is connected to the second online detection device 53. An external condensate pump 51 and a second heat exchanger 52 are installed on the connecting pipe between the top outlet of the deoxygenation reflux device 3 and the second online detection device 53. The external condensate pump 51 is frequency-controlled and interlocked with the pressure in front of the pump to control the top of the deoxygenation device 1 to be at a slight negative pressure of 0 to -50 Pa, which is conducive to the removal of oxygen from the condensate. The second heat exchanger 52 cools the condensate to room temperature.

[0072] The second online detection device 53 is connected to the second collection device 5 and the third collection device 6, and the second online detection device 53 includes a second oil analyzer 531 and a second conductivity meter 532.

[0073] A. Condensate with the set value of the second oil meter 531 is connected to the second collection device 5. At the same time, condensate with a value higher than the set value of the second conductivity meter 532 is introduced into the ultrafiltration water tank as ultrafiltration water; condensate with a value lower than the set value of the second conductivity meter 532 is introduced into the RO product water tank.

[0074] B. Condensate that fails to pass the set value of the second oil meter 531 is connected to the third collection device 6 and used as the raw water tank of the demineralized water station.

[0075] It should be noted that the bottom outlet of the deaerator reflux device 3 is connected to the top of the deaerator 1, and the condensate temperature at its outlet is about 65°C, which is used to spray the high-temperature condensate to cool it down to below 120°C.

[0076] Specifically, the deaerator 1 is equipped with a non-condensable gas outlet at the top, which is connected to the third collection device 6. At the same time, a pressure reducing valve 71, a regulating valve 72, and a third heat exchanger 73 are installed sequentially on its connecting pipe. The pressure reducing valve 71 controls the reduction of pressure, the regulating valve 72 is interlocked with the oxygen analyzer 211 of the first online detection device 21 to control the oxygen content, and the third heat exchanger 73 cools the condensate to room temperature and delivers it to the third collection device 6. The third collection device 6 has an vent 61 at the top for discharging non-condensable gases such as oxygen. The condensate collected in the third collection device 6 is used as raw water for the demineralized water station.

[0077] This embodiment provides a method for deoxygenating and reusing high-temperature steam condensate, using the system described in this embodiment. Specifically:

[0078] Step 1: High-temperature condensate at 130℃ and 0.2MPa is supplied to the inlet of deoxygenation device 1 at a flow rate of 15t / h. After cooling by the spray liquid at approximately 65℃ at the top of deoxygenation device 1 and the distillation and deoxygenation effect of the multi-layer first sieve plate, the condensate temperature at the bottom outlet of deoxygenation device 1 is 104~120℃. It is then pumped by hot water pump 13 to the first online detection device 21 for detection. The oxygen analyzer 211 is set to 15μg / l, the first oil analyzer 212 is set to 0.5mg / l, and the first conductivity meter 213 is set to 6μs / cm. When the oxygen content of the condensate is less than 15 μg / l, the oil content is less than 0.5 mg / l, and the conductivity meter reading is less than 6 μs / cm, the condensate is fed into the first collection device 2. The collected condensate has an oxygen content of less than 12 μg / l, an oil content of 0.25 mg / l, and a conductivity of 5 μs / cm, and is used as the feedwater source for medium-temperature and medium-pressure boilers. When the oxygen content of the condensate is higher than 15 μg / l, the oil content is higher than 0.5 mg / l, or the conductivity meter reading is higher than 6 μs / cm, the condensate is fed into the deaeration reflux device 21 for treatment.

[0079] It is worth noting that the non-condensable gases in the deaerator 1 are discharged through the top outlet, and after being cooled to room temperature by the pressure reducing valve 71, regulating valve 72, and third heat exchanger 73, the condensate is collected inside the third collection device 6, and oxygen and other non-condensable gases are discharged through the vent 61 at the top of the third collection device 6.

[0080] Step 2: When the condensate from Step 1 needs to be treated in the deoxygenation reflux device 21, the condensate first passes through the first heat exchanger 31 to cool down to 65°C. After entering the deoxygenation reflux device 21, under the action of a slight negative pressure of about 0Pa (gauge pressure) to -50Pa (gauge pressure), oxygen can be effectively removed. The deoxygenation reflux device 21 is equipped with a second sieve plate 32 arranged in a spiral pattern above and below the inlet.

[0081] Condensate with low oxygen content in the deoxygenation reflux device 21 is pumped out from the lower outlet by the reflux condensate pump 4 and returned to the top of the deoxygenation device 1 for use as a spray liquid. Condensate with high oxygen content in the deoxygenation reflux device 21 is pumped out from the top outlet by the external condensate pump 51, and simultaneously cooled to room temperature by the second heat exchanger 52 before being sent to the second online detection device 53 for testing. The set value of the second oil analyzer 531 is 1 mg / L, and the set value of the second conductivity meter 532 is 30 μS / cm.

[0082] When the oil content of the condensate is greater than 1 mg / L, it flows into the third collection device 6. The collected condensate has an oil content of 1.2 mg / L and a conductivity of 100 μS / cm, and is used as raw water for the demineralized water station.

[0083] When the oil content of the condensate is less than 1 mg / L, it flows into the second collection device 5. At the same time, when the conductivity of the condensate is greater than 30 μs / cm, it can be passed into the ultrafiltration water tank for use as ultrafiltration water. At this time, the collected condensate has an oil content of 0.8 mg / L and a conductivity of 25 μs / cm. When the conductivity of the condensate is less than 30 μs / cm, it can be passed into the RO product water tank for use. At this time, the collected condensate has an oil content of 0.6 mg / L and a conductivity of 15 μs / cm.

[0084] The examples described herein are merely preferred embodiments of the invention and are not intended to limit the concept and scope of the invention. Any modifications and improvements made by those skilled in the art to the technical solutions of the invention without departing from the design concept of the invention should fall within the protection scope of the invention.

Claims

1. A method for deoxygenating and reusing high-temperature steam condensate, characterized in that: The high-temperature condensate is cooled and deoxygenated by the deoxygenation device (1), and the condensate at the outlet below the deoxygenation device (1) is detected by the first online detection device (21): When the oxygen content, oil content and conductivity detected by the first online detection device (21) are lower than the set values, the condensate is transported to the first collection device (2), and the condensate of the first collection device (2) is used as the feed water source for the medium temperature and medium pressure boiler. When the oxygen content, oil content, or conductivity detected by the first online detection device (21) is higher than the set value, the condensate is sent to the deoxygenation reflux device (3) for deoxygenation treatment: The water effluent from the bottom of the deoxygenation reflux device (3) is transported to the top of the deoxygenation device (1) via the reflux condensate pump (4) as a coolant for the high-temperature condensate; wherein the reflux condensate pump (4) is set to be interlocked with the pressure or temperature inside the deoxygenation device (1); the water effluent from the top of the deoxygenation reflux device (3) is transported to the second online detection device (53) via the external condensate pump (51), wherein the external condensate pump (51) is set to be interlocked with the pressure before the pump; The water effluent from the top of the deoxygenation reflux device (3) is then passed through the second online detection device (53). When the oil content detected by the second online detection device (53) is lower than the set value, the condensate is transported to the second collection device (5) for transport to the ultrafiltration water tank or RO product water tank. When the oil content detected by the second online detection device (53) is higher than the set value, the condensate is transported to the third collection device (6). The deoxygenation device (1) also has a non-condensable gas outlet at the top, which is connected to the third collection device (6). A pressure reducing valve (71) and a third heat exchanger (73) are installed on the connecting pipe. After pressure reduction and cooling, condensate is collected in the third collection device (6), and non-condensable gas is released from the vent (61) at the top of the third collection device (6). A regulating valve (72) is also installed on the non-condensable gas outlet at the top of the deoxygenation device (1) and the connecting pipe to the third collection device (6) to regulate the oxygen content and interlock with the oxygen content data of the first online detection device (21).

2. The method for deoxygenating and reusing high-temperature steam condensate according to claim 1, characterized in that: The upper inlet of the deoxygenation device (1) is connected to a high-temperature condensate pipe, and the lower outlet of the deoxygenation device (1) is connected to a first online detection device (21). The first online detection device (21) is connected to a first collection device (2) and a deoxygenation reflux device (3). The top outlet of the deoxygenation reflux device (3) is connected to the second online detection device (53), and the second online detection device (53) is connected to the second collection device (5) and the third collection device (6); the bottom outlet of the deoxygenation reflux device (3) is connected to the top of the deoxygenation device (1); The first online detection device (21) is used to detect the oxygen content, oil content and conductivity of the condensate, and the second online detection device (53) is used to detect the oil content and conductivity of the condensate. The first online detection device (21) and the second online detection device (53) are used to control the flow direction of the condensate.

3. A method for deoxygenating and reusing high-temperature steam condensate according to claim 1, characterized in that: The deoxygenation device (1) is equipped with a spray head (11) above the upper water inlet. The bottom outlet of the deoxygenation return device (3) is connected to the spray head (11). The pressure inside the deoxygenation return device (3) is 0~-50 Pa.

4. A method for deoxygenating and reusing high-temperature steam condensate according to claim 1, characterized in that: The deoxygenation device (1) has several first sieve plates (12) arranged along the height direction inside. The first sieve plate (12) is a circular sieve plate with a notch. It is divided into an effective sieve plate area (121) and a downcomer area (122). The effective sieve plate area (121) is distributed with several sieve holes with a diameter of 6~10 mm. The downcomer area (122) is a solid plate. The downcomer plate (123) is set at the end of the effective sieve plate area (121) and is set downward. The two adjacent first sieve plates (12) are staggered. The number of layers of the first sieve plates (12) inside the deoxygenation device (1) is 7~12.

5. A method for deoxygenating and reusing high-temperature steam condensate according to claim 1, characterized in that: The inlet of the deoxygenation reflux device (3) is located in the middle of the side. The deoxygenation reflux device (3) is provided with several second screen plates (32) arranged along the height direction. The two adjacent second screen plates (32) are staggered. The number of layers of the second screen plates (32) inside the deoxygenation reflux device (3) is 9 to 15. The second screen plate (32) is a circular screen plate with notches, and screen holes with a diameter of 6 to 12 mm are distributed on it.

6. The method for deoxygenating and reusing high-temperature steam condensate according to claim 1, characterized in that: The first online detection device (21) includes an oxygen analyzer (211), a first oil analyzer (212), and a first conductivity meter (213); the second online detection device (53) includes a second oil analyzer (531) and a second conductivity meter (532); a first heat exchanger (31) is installed on the pipeline connecting the first online detection device (21) to the deoxygenation reflux device (3); a second heat exchanger (52) is installed on the pipeline connecting the deoxygenation reflux device (3) to the second online detection device (53).

7. The method for deoxygenating and reusing high-temperature steam condensate according to claim 1, characterized in that: The lower outlet of the deoxygenation device (1) is supplied to the first online detection device (21) by a hot water pump (13); the top outlet of the deoxygenation reflux device (3) is supplied to the second online detection device (53) by an external condensate pump (51); the bottom outlet of the deoxygenation reflux device (3) is supplied to the top of the deoxygenation device (1) by a reflux condensate pump (4), wherein both the external condensate pump (51) and the reflux condensate pump (4) are configured with frequency conversion regulation.

8. A method for deoxygenating and reusing high-temperature steam condensate according to claim 7, characterized in that: When the oil content detected by the second online detection device (53) is lower than the set value and the conductivity value is higher than the set value, it is used to transport the water to the ultrafiltration tank; when the oil content detected by the second online detection device (53) is lower than the set value and the conductivity value is lower than the set value, it is used to transport the water to the RO product tank. The oxygen content setting of the first online detection device (21) is 1~15 μg / l, the oil content setting is 0.1~0.5mg / l, and the conductivity setting is 0.1~6μs / cm; The second online detection device (53) has an oil content setting of 0.3~1 mg / l and an electrical conductivity setting of 4~30 μs / cm.

9. A method for deoxygenating and reusing high-temperature steam condensate according to claim 7, characterized in that: The condensate is transported to the pipeline of the deoxygenation reflux device (3) and cooled by the first heat exchanger (31); the water from the top of the deoxygenation reflux device (3) is cooled by the second heat exchanger (52) and then transported to the second online detection device (53).

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