A boiler feed water deoxygenation system and method

Abstract

The present invention discloses a boiler feed water deoxygenation system and method. The system includes a deaerator and a desalted water tank. The upper part of the deaerator is a deaerator tower, the lower part of the deaerator is a deaerator water tank and a deaerator water jet tank, the deaerator tower and the deaerator water tank are connected, the top of the deaerator tower is provided with an exhaust port I, the top of the deaerator water jet tank is provided with a deaerator water jet inlet, the bottom of the deaerator water jet tank is provided with a deaerator water jet outlet, the middle of the deaerator water jet tank is provided with an overflow port, and the top of the deaerator water jet tank is provided with a water ejector, the exhaust port I is connected to the air inlet of the water ejector; the desalted water tank is provided with a desalted water inlet and a desalted water outlet, the desalted water inlet is connected to the overflow port on the deaerator water jet tank through a pipeline, and the desalted water outlet is connected to the deaerator water jet inlet through a pipeline. The present invention eliminates the chemical assisted deoxygenation system, adds a circulating water tank of the desalted water tank, avoids the corrosion of the equipment by the chemical assisted deoxygenation additive, and is conducive to the maintenance of the equipment.

Description

Technical Field

[0001] The invention belongs to the field of boiler feed water treatment, and in particular relates to a boiler feed water deoxygenation system and method. Background Art

[0002] In the boiler feed water treatment process, deoxygenation is a very critical link. Oxygen is the main corrosive substance in the feed water system and boiler. The oxygen in the feed water should be removed quickly, otherwise it will corrode the boiler's feed water system and components. The corrosion product, iron oxide, will enter the boiler and deposit or adhere to the boiler tube wall and heating surface, forming iron scale that is difficult to dissolve and has poor heat transfer. In addition, corrosion will cause pits on the inner wall of the pipeline and increase the resistance coefficient. When the pipeline is severely corroded, it may even explode. The state stipulates that steam boilers with an evaporation capacity of more than 2 tons per hour and hot water boilers with a water temperature of more than 95°C must be deoxygenated. For many years, many boiler feed water treatment workers have been exploring efficient and economical deoxygenation methods, and vacuum deoxygenation is one of the best.

[0003] The working principle of vacuum deoxygenation is to apply Henry's law and Dalton's law. According to Henry's law, in a closed container, if any gas exists on the water surface at the same time, the solubility of the gas is proportional to its own partial pressure, and the solubility of the gas is only related to its own partial pressure. Under a certain pressure, as the water temperature rises, the partial pressure of water vapor increases, while the partial pressures of air and oxygen become smaller and smaller. At 100°C, the partial pressure of oxygen drops to zero, and the dissolved oxygen in the water also drops to zero. When the pressure on the water surface is less than the atmospheric pressure, the solubility of oxygen can also reach zero at a lower water temperature. In this way, the oxygen molecules in the space above the water surface are discharged or converted into other gases, so that the partial pressure of oxygen is zero, and the oxygen in the water continuously escapes, achieving the effect of deoxygenation. The vacuum deaerator is a deaerator based on the above principle. It is a device that makes water boil at low temperature under vacuum and removes oxygen, nitrogen, carbon dioxide and other gases contained in the water.

[0004] However, it has been found in practice that the effect of a single deaerator is poor. During production operation, our factory adopts a vacuum deaerator plus chemical assisted deaerator mode due to the poor deaerator effect. Although the deaerator effect meets the operating requirements, the chemical assisted deaerator added with residual agents has certain hazards to the turbine, boiler and steam pipe, and the effect is unstable. Summary of the invention

[0005] In order to solve the problems in the above-mentioned prior art that the deoxygenation effect of using a deaerator alone is poor, and the chemical assisted deoxygenation residues added in vacuum deoxygenation plus chemical assisted deoxygenation have certain harm to turbines, boilers and steam pipes, and the effect is unstable, the present invention provides a boiler feed water deoxygenation system and method.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A boiler feed water deoxygenation system, comprising a deaerator and a desalting water tank, wherein the deaerator is in an inverted "T" shape, the upper part of the deaerator is a deaerator tower, the lower part of the deaerator is a deaerator water tank and a deaerator jet water tank, the deaerator water tank and the deaerator jet water tank are separated by a partition, the deaerator tower and the deaerator water tank are connected, and a deaerator water outlet is provided at the lower part of the deaerator water tank; an exhaust port I is provided at the top of the deaerator tower, a water inlet to be deaerated is provided on the tower body of the deaerator tower, a return water port and a deaerator jet water inlet are provided at the top of the deaerator jet water tank, a deaerator jet water outlet is provided at the bottom of the deaerator jet water tank, an overflow port is provided in the middle of the deaerator jet water tank, and a deaerator jet water outlet is provided at the bottom of the deaerator jet water tank. A water ejector is provided above the water tank, and the water inlet of the water ejector is connected to the deoxygenation water jet outlet through a pipeline, and a water pump I is provided on the pipeline, and the mixed liquid outlet of the water ejector is connected to the return water outlet of the deoxygenation water jet tank, and the exhaust port I is connected to the air inlet of the water ejector; a desalted water inlet and a desalted water outlet are provided on the desalted water tank, and the desalted water inlet is connected to the overflow outlet on the deoxygenation water jet tank through a pipeline, and the desalted water outlet is connected to the deoxygenation water jet inlet through a pipeline, and a water pump II is provided on the pipeline, and the water pump II pumps the desalted water in the desalted water tank into the deoxygenation water jet tank.

[0008] Furthermore, an exhaust port II is provided on the top of the deoxygenated water tank, and the exhaust port II is connected to the air inlet of the water ejector through a pipeline, and a valve is provided on the pipeline.

[0009] Furthermore, a heating jacket is provided outside the deoxygenated water tank, and a circulating water inlet and a circulating water outlet are provided on the heating jacket, so that hot water forms a water circulation in the heating jacket.

[0010] Furthermore, two parallel pipelines are provided between the water inlet of the water ejector and the deoxygenated water ejection outlet, and each pipeline is provided with a water pump.

[0011] Furthermore, a stirring paddle is provided in the deaeration water tank, a stirring rod of the stirring paddle passes through the deaeration water tank shell, and the stirring rod is fixed to the deaeration water tank shell through a sealed bearing.

[0012] Furthermore, the stirring paddle is arranged on the top of the deaeration water tank; or the stirring paddle is arranged on the side end of the deaeration water tank, and the other end of the stirring rod is fixed on the partition through a bearing.

[0013] A method for deoxygenating boiler feed water based on the above deoxygenation system comprises the following steps:

[0014] (1) Heat the temperature of the deaerator tank to 40-45°C;

[0015] (2) Turn on water pump I and water ejector to evacuate the deaeration water tank and set the vacuum degree to -80Pa;

[0016] (3) Turn on water pump II. Water pump II pumps the desalted water in the desalted water tank into the deoxygenated water tank, mixes it with the high-temperature water in the deoxygenated water tank, and reduces the water temperature of the deoxygenated water tank. The deoxygenated water tank drains water into the desalted water tank and adjusts the water level to balance, which is circulated continuously.

[0017] Furthermore, the water temperature in the deaeration water injection tank is controlled at 45°C.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The system of the present invention eliminates the need for a chemically assisted deoxygenation system and adds a circulating water tank for a desalted water tank. The desalted water tank is provided with a desalted water inlet and a desalted water outlet. The desalted water inlet is connected to the overflow port on the deoxygenated water jet tank through a pipeline, and the desalted water outlet is connected to the deoxygenated water jet inlet through a pipeline. The pipeline is provided with a water pump II. The water pump II pumps the desalted water in the desalted water tank into the deoxygenated water jet tank. The excess water in the deoxygenated water jet tank flows back to the desalted water tank through the overflow port. The desalted water tank and the deoxygenated water jet tank form a cycle. During the operation of the water ejector, the water temperature in the deoxygenated water jet tank continues to rise, and the water pump II pumps the low-temperature desalted water in the desalted water tank into the deoxygenated water jet tank. The high-temperature desalted water in the deoxygenated water jet tank flows out from the overflow port and flows back to the desalted water tank to adjust to a water level balance. This cycle reduces the water temperature in the deoxygenated water jet tank and improves the vacuuming efficiency. The present invention achieves dissolved oxygen in deoxygenated water below 5 ug / L, the deoxygenation effect reaches the operation requirement, and there is no chemical auxiliary deoxygenation, which ensures the safe operation of the steam turbine, boiler and steam pipeline, avoids the corrosion of the equipment by the chemical auxiliary deoxygenation additive, and is beneficial to the maintenance of the equipment.

[0020] (2) The water temperature of the deaeration water jet tank is high. During normal operation, the water needs to be changed 1-2 times per shift and discharged into the circulating water pool. However, the present invention returns the high-temperature water circulated in the deaeration water jet tank to the desalted water tank for recycling, thus saving water costs. In addition, the high-temperature water circulated in the deaeration water jet tank is returned to the desalted water tank, the temperature of the desalted water increases, the boiler feed water temperature increases, the boiler efficiency increases, the power generation increases, and the revenue increases.

[0021] (3) The method of the present invention eliminates chemical assisted deoxygenation and decides to reduce the water temperature of the deoxygenation water jet tank according to the working principle of the vacuum deaerator. That is, a water pump is added to replenish the deionized water in the deionized water tank to the deoxygenation water jet tank, and the deoxygenation water jet tank is drained to the deionized water tank, and the water level is adjusted to be balanced. The cycle is continuous to achieve the purpose of reducing the water temperature in the deoxygenation water jet tank, improving the working efficiency of the vacuum deaerator, and ensuring the safety of the unit equipment. After operation practice, the water temperature of the deoxygenation water tank dropped to 45°C, the vacuum of the deaerator increased to -80Pa, the dissolved oxygen was below 5ug / L, and the deoxygenation effect met the operation requirements.

[0022] (4) The present invention eliminates chemical-assisted deoxygenation, and thus also eliminates the chemical-assisted deoxygenation system, thereby reducing the equipment maintenance cost of the chemical-assisted deoxygenation system and saving the cost of chemical agents.

[0023] (5) In the prior art, due to the high water temperature in the deaeration water jetting tank, the water needs to be changed 1 to 2 times per shift during normal operation and discharged into the circulating water pool. The present invention returns the high-temperature water circulated in the deaeration water jetting tank to the desalted water tank for recycling, thus saving water costs. The high-temperature water circulated in the deaeration water jetting tank of the present invention is returned to the desalted water tank, the temperature of the desalted water is increased, the boiler feed water temperature is increased, the boiler efficiency is improved, the power generation is increased, and the profit is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of the present invention;

[0025] Figure 2 It is a cross-sectional view of the deaeration water tank and the deaeration water injection tank;

[0026] Figure 3 This is a schematic diagram of the structure after adding exhaust port II;

[0027] Figure 4 This is a schematic diagram of the structure after adding a heating jacket;

[0028] Figure 5 The cross-sectional view of the deaeration water tank and deaeration water injection tank after adding the heating jacket;

[0029] Figure 6 A schematic diagram of the structure for adding parallel pipes between the water injector and the deaerator water injection tank;

[0030] Figure 7 A schematic diagram of adding a vertical stirring paddle;

[0031] Figure 8 This is a schematic diagram of adding a horizontal stirring paddle.

[0032] In the figure, 1-deaerator tower, 101-exhaust port Ⅰ, 102-water inlet to be deoxygenated; 2-deaerator water tank, 201-deaerator water outlet, 202-circulating water inlet, 203-circulating water outlet, 204-exhaust port Ⅱ, 3-deaerator water jet tank, 301-return water outlet, 302-deaerator water jet inlet, 303-deaerator water jet outlet, 304-overflow, 305-water pump Ⅰ, 4-partition, 5-water ejector, 6-deionized water tank, 601-deionized water inlet, 602-deionized water outlet, 603-water pump Ⅱ, 7-agitation paddle, 701-agitation rod, 702-sealed bearing. DETAILED DESCRIPTION

[0033] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific implementation methods of the present invention are now described with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0034] The present invention is further described below in conjunction with the embodiments, which are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the protection scope of the present invention. Example

[0035] like Figure 1 and 2 As shown, a boiler feed water deoxygenation system includes a deaerator and a desalting water tank 6, wherein the deaerator is in an inverted "T" shape, the upper part of the deaerator is a deaerator tower 1, the internal structure of the deaerator tower 1 is the prior art, the lower part of the deaerator is a deaerator water tank 2 and a deaerator water jet tank 3, the deaerator water tank 2 and the deaerator water jet tank 2 are separated by a partition 4, the deaerator tower 1 and the deaerator water tank 2 are connected, and a deaerator water outlet 201 is provided at the lower part of the deaerator water tank; an exhaust port Ⅰ101 is provided at the top of the deaerator tower 1, a water inlet 102 to be deoxygenated is provided on the tower body of the deaerator tower 1, a return water port 301 and a deaerator water jet inlet 302 are provided at the top of the deaerator water jet tank 3, a deaerator water jet outlet 303 is provided at the bottom of the deaerator water jet tank, an overflow port 304 is provided in the middle of the deaerator water jet tank 3, a water ejector 5 is provided above the deaerator water jet tank 3, and a water inlet 102 between the water ejector 5 and the deaerator water jet outlet 303 is provided. They are connected by a pipeline, on which a water pump Ⅰ305 is provided, the mixed liquid outlet of the water injector 5 is connected to the return water port 301 of the deoxygenation water jetting tank, and the exhaust port Ⅰ101 is connected to the air inlet of the water injector 5; the desalted water tank 6 is provided with a desalted water inlet 601 and a desalted water outlet 602, the desalted water inlet 601 is located at a height lower than the height of the overflow port 304 on the deoxygenation water jetting tank 3, the desalted water inlet 601 is connected to the overflow port 304 on the deoxygenation water jetting tank 3 through a pipeline, the desalted water outlet 602 is connected to the deoxygenation water jetting inlet 302 through a pipeline, and a water pump Ⅱ603 is provided on the pipeline, the water pump Ⅱ603 pumps the desalted water in the desalted water tank 6 into the deoxygenation water jetting tank 3, and the excess water in the deoxygenation water jetting tank 3 flows back to the desalted water tank through the overflow port 304, and the desalted water tank and the deoxygenation water jetting tank form a cycle.

[0036] The working process of a boiler feed water deoxygenation system of the present invention is as follows:

[0037] The water inlet 102 to be deoxygenated is connected to the outlet of the desalted water in the water treatment workshop, and the water to be deoxygenated enters the deoxygenation tower 1 from the water inlet 102 to be deoxygenated, and then falls into the deoxygenation water tank 2; the water pump Ⅰ305 and the water ejector 5 are started, and the water pump Ⅰ305, the water ejector 5 and the deoxygenation water ejector tank 3 form a vacuum pumping device to vacuum the deoxygenation water tank 2; the air pressure in the deoxygenation water tank 2 is reduced, and the gas in the water escapes and is discharged from the exhaust port Ⅰ101, and is mixed with the deoxygenation water ejector pumped out by the water pump Ⅰ305 in the water ejector 5, and the mixed liquid is discharged through the return water port 301 Flow back to the deoxygenated water jet tank 3; as the water ejector 5 continues to work, the temperature of the deoxygenated water jet in the deoxygenated water jet tank 3 continues to rise, the vacuuming efficiency decreases, and the water pump II 603 is turned on. The water pump II 603 pumps the low-temperature deoxygenated water in the deoxygenated water jet tank 6 into the deoxygenated water jet tank 3, and mixes with the high-temperature deoxygenated water jet in the deoxygenated water jet tank 3, thereby reducing the temperature of the deoxygenated water jet, and the excess water overflows through the overflow port 304 and flows back to the deoxygenated water jet tank 6, and is adjusted to the water level balance, and the cycle is repeated, thereby reducing the temperature of the deoxygenated water jet and maintaining the vacuum in the deoxygenated water tank 2. The system of the present invention eliminates the need for chemical auxiliary deoxygenation, which is beneficial to equipment maintenance, and also avoids frequent water changes due to excessively high water temperature in the deoxygenated water jet tank.

[0038] Further, such as Figure 3 As shown, the top of the deaerator water tank 2 is provided with an exhaust port II 204, which is connected to the air inlet of the water ejector 5 through a pipeline, and a valve is provided on the pipeline. The exhaust port II 204 is provided on the top of the deaerator water tank 2, which is conducive to the gas being discharged directly from the exhaust port II 204 and entering the water ejector 5.

[0039] Further, such as Figure 4 and 5 As shown, the deoxygenated water tank 2 is provided with a heating jacket, on which a circulating water inlet 202 and a circulating water outlet 203 are provided. Hot water forms a water circulation in the heating jacket to heat the water in the deoxygenated water tank.

[0040] Further, such as Figure 6 As shown, two parallel pipelines are provided between the water inlet of the water ejector 5 and the deoxygenated water jet outlet 303, and each pipeline is provided with a water pump. The parallel pipeline arrangement can increase the circulation speed of the deoxygenated water jet and improve the work efficiency.

[0041] Further, such as Figure 7As shown, the deoxygenated water tank 2 is provided with a stirring paddle 7, which is arranged on the top of the deoxygenated water tank 2. A stirring rod 701 of the stirring paddle 7 passes through the outer shell of the deoxygenated water tank 2, and the stirring rod 701 is fixed on the outer shell of the deoxygenated water tank 1 through a sealed bearing 702. The stirring paddle 7 is arranged on the deoxygenated water tank 1, and during the vacuum deoxygenation process, the deoxygenated water is stirred, the escape speed of the gas in the water is increased, the deoxygenation time is shortened, and the deoxygenation is more thorough. At the same time, the heating efficiency is improved during heating.

[0042] Further, such as Figure 8 As shown, a stirring paddle 7 is provided in the deoxygenated water tank 2, and the stirring paddle 7 is arranged at the side end of the deoxygenated water tank 2. A stirring rod 701 of the stirring paddle 7 passes through the outer shell of the deoxygenated water tank 2, and the stirring rod 701 is fixed to the outer shell of the deoxygenated water tank 1 through a sealed bearing 702, and the other end of the stirring rod 701 is fixed to the partition 4 through a bearing. The stirring paddle 7 is arranged horizontally, and when stirring, the water in the deoxygenated water tank 2 has a larger range of action, thereby improving the stirring efficiency.

[0043] Experimental Example 1

[0044] A method for deoxygenating boiler feed water based on the above deoxygenation system comprises the following steps:

[0045] (1) Heat the deaeration water tank to 40°C;

[0046] (2) Turn on water pump I and water ejector to evacuate the deaeration water tank and set the vacuum degree to -80Pa;

[0047] (3) Turn on water pump II. Water pump II pumps the desalted water in the desalted water tank into the deoxygenated water tank, mixes it with the high-temperature water in the deoxygenated water tank, and reduces the water temperature of the deoxygenated water tank. The deoxygenated water tank drains water into the desalted water tank and adjusts the water level to balance, which is circulated continuously.

[0048] Experimental Example 2

[0049] A method for deoxygenating boiler feed water based on the above deoxygenation system comprises the following steps:

[0050] (1) Heat the temperature of the deaerator water tank to 45°C;

[0051] (2) Turn on water pump I and water ejector to evacuate the deaeration water tank and set the vacuum degree to -80Pa;

[0052] (3) Turn on water pump II. Water pump II pumps the desalted water in the desalted water tank into the deoxygenated water tank, mixes it with the high-temperature water in the deoxygenated water tank, and reduces the water temperature of the deoxygenated water tank. The deoxygenated water tank drains water into the desalted water tank and adjusts the water level to balance, which is circulated continuously.

[0053] Experimental Example 3

[0054] A method for deoxygenating boiler feed water based on the above deoxygenation system comprises the following steps:

[0055] (1) Heat the temperature of the deaerator water tank to 42°C;

[0056] (2) Turn on water pump I and water ejector to evacuate the deaeration water tank and set the vacuum degree to -80Pa;

[0057] (3) Turn on water pump II. Water pump II pumps the desalted water in the desalted water tank into the deoxygenated water tank, mixes it with the high-temperature water in the deoxygenated water tank, and reduces the water temperature of the deoxygenated water tank. The deoxygenated water tank drains water into the desalted water tank and adjusts the water level to balance, which is circulated continuously.

[0058] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A boiler feed water deoxygenation system, characterized in that: It includes a deaerator and a desalted water tank, the deaerator is in an inverted "T" shape, the upper part of the deaerator is a deaerator tower, the lower part of the deaerator is a deaerator water tank and a deaerator jet water tank, the deaerator water tank and the deaerator jet water tank are separated by a partition, the deaerator tower and the deaerator water tank are connected, and a deaerator water outlet is provided at the lower part of the deaerator water tank; an exhaust port I is provided at the top of the deaerator tower, a water inlet to be deaerated is provided on the tower body of the deaerator tower, a return water port and a deaerator jet water inlet are provided at the top of the deaerator jet water tank, a deaerator jet water outlet is provided at the bottom of the deaerator jet water tank, an overflow port is provided in the middle of the deaerator jet water tank, and a There is a water ejector, the water inlet of the water ejector is connected to the deoxygenation water ejection outlet through a pipeline, a water pump I is arranged on the pipeline, the mixed liquid outlet of the water ejector is connected to the water return port of the deoxygenation water ejection tank, the exhaust port I is connected to the air inlet of the water ejector; the desalted water tank is provided with a desalted water inlet and a desalted water outlet, the desalted water inlet is connected to the overflow port on the deoxygenation water ejection tank through a pipeline, the desalted water outlet is connected to the deoxygenation water ejection inlet through a pipeline, a water pump II is arranged on the pipeline, and the water pump II pumps the desalted water in the desalted water tank into the deoxygenation water ejection tank; A heating jacket is provided outside the deoxygenated water tank, and a circulating water inlet and a circulating water outlet are provided on the heating jacket, and hot water forms a water circulation in the heating jacket; A stirring paddle is arranged in the deaeration water tank, a stirring rod of the stirring paddle passes through the deaeration water tank shell, and the stirring rod is fixed on the deaeration water tank shell through a sealed bearing.

2. A boiler feed water deoxygenation system according to claim 1, characterized in that: An exhaust port II is arranged on the top of the deaeration water tank, and the exhaust port II is connected to the air inlet of the water ejector through a pipeline, and a valve is arranged on the pipeline.

3. A boiler feed water deoxygenation system according to claim 1, characterized in that: Two parallel pipelines are arranged between the water inlet of the water ejector and the deoxygenation water ejection outlet, and each pipeline is provided with a water pump.

4. A boiler feed water deoxygenation system according to claim 1, characterized in that: The stirring paddle is arranged on the top of the deaeration water tank; or the stirring paddle is arranged on the side end of the deaeration water tank, and the other end of the stirring rod is fixed on the partition through a bearing.

5. A method for deoxygenating boiler feed water in a deoxygenation system, characterized in that: Deoxygenation using the boiler feed water deoxygenation system according to any one of claims 1 to 4 comprises the following steps: (1) Heat the temperature of the deaerator tank to 40-45°C; (2) Turn on water pump I and water ejector to evacuate the deaeration water tank and set the vacuum degree to -80Pa; (3) Turn on water pump II. Water pump II pumps the desalted water in the desalted water tank into the deoxygenated water tank, mixes it with the high-temperature water in the deoxygenated water tank, and reduces the water temperature of the deoxygenated water tank. The deoxygenated water tank drains water into the desalted water tank and adjusts the water level to balance, which is circulated continuously.

6. The method for deoxygenating boiler feed water of a deoxygenation system according to claim 5, characterized in that: The water temperature in the deaeration water injection tank is controlled at 45℃.

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