CN215637271U

CN215637271U - Flue gas condensate water treatment device capable of resisting dew point corrosion

Info

Publication number: CN215637271U
Application number: CN202122050204.4U
Authority: CN
Inventors: 张跃
Original assignee: Broad Air Conditioning Co ltd
Current assignee: Broad Air Conditioning Co ltd
Priority date: 2021-08-30
Filing date: 2021-08-30
Publication date: 2022-01-25
Anticipated expiration: 2031-08-30

Abstract

A dew point corrosion resistant flue gas condensed water treatment device comprises a flue gas spraying unit, a flue gas heat exchange unit, a condensed water collecting tank, a dosing unit and a control unit which are connected in sequence, wherein the condensed water collecting tank is also connected with the flue gas spraying unit; a Ph detection sensor for detecting the Ph value of the condensed water is arranged in the condensed water collecting pool; the Ph detection sensor is connected with the input end of the control unit, and the output end of the control unit is connected with the dosing unit. On one hand, the pH value of the condensed water can be detected in real time, and once the condensed water is acidic, an alkaline medicament is added through the medicament adding unit to improve the alkalinity of the condensed water, so that the corrosion of equipment is prevented, and the service life of the equipment is prolonged; on the other hand, the two kinds of dew point corrosion of sulfuric acid and nitric acid that can avoid the flue gas to produce, and make full use of the heat of flue gas improves the energy utilization of flue gas.

Description

Flue gas condensate water treatment device capable of resisting dew point corrosion

Technical Field

The utility model relates to a condensed water treatment device, in particular to a flue gas condensed water treatment device capable of resisting dew point corrosion.

Background

When sulfur compounds are burned, acidic gases such as sulfur dioxide and sulfur trioxide are generated in the flue gas. In particular, sulfur trioxide is easy to combine with water vapor in flue gas to generate sulfuric acid fog drops which are condensed on the surface of a heat exchanger to generate serious corrosion, namely sulfuric acid dew point corrosion or dew point corrosion for short. The flue gases of civil or industrial gas, which contain different amounts of sulfur trioxide, undergo condensation of sulfuric acid and dew point corrosion starting in a temperature range of 102-150 ℃ and below, and the temperature range of corrosion continues up to the temperature at which a large amount of water vapor condenses (about 58 ℃ for natural gas), namely: when the flue gas is cooled to the condensation temperature, a large amount of condensed water can be generated, if more acidic gas exists in the flue gas, the formed condensed water is acidic, and the stainless steel can be seriously corroded by sulfuric acid at a certain concentration and temperature; in the area where the sulfuric acid condensation initially appears, because the sulfuric acid concentration is highest, the temperature is high, the corrosion is the most serious, perforation and failure of heat exchange equipment can be caused, and the service life is seriously shortened. Therefore, the acid must be diluted to a non-corrosive concentration (Ph greater than 4).

Even if the fuel is completely desulfurized, the corrosion of sulfuric acid dew point is avoided. However, at the high temperatures of combustion, oxygen and nitrogen can produce nitrogen oxides, some of which are nitrogen dioxide. The nitrogen dioxide can generate nitric acid when meeting water. Therefore, nitric oxide and water vapor in the flue gas can generate nitric acid condensation. The corrosion caused by nitric acid condensation is called nitric acid dew point corrosion. In flue gas of civil or industrial gas, the temperature at which nitrogen oxides cause dew point corrosion is generally around 70 ℃, and the corrosion region continues to a temperature at which a large amount of water vapor condenses (about 58 ℃ for natural gas), and thereafter the condensed water resulting from the condensation of a large amount of water vapor also tends to have a corrosive concentration. Since nitric acid can severely corrode metal materials such as copper and the like, copper ions can promote corrosion of stainless steel, nitric acid condensation severely damages a copper-brazed stainless steel plate type heat exchanger.

Although a direct contact mode of spraying the flue gas with water can be adopted, the low-temperature waste heat in the flue gas is recovered, and the heat exchanger made of corrosion-resistant materials such as stainless steel and the like is generally not corroded. However, the water absorbs smoke dust, oxysulfide and nitrogen oxide in the flue gas, so that the water quality is changed, and the water cannot be directly used as domestic hot water. And the water contains a trace amount of acidic substances, and can slowly corrode equipment utilizing the hot water, such as: heating pipelines and radiating fins, evaporator heat exchange tubes of heat pumps and the like.

SUMMERY OF THE UTILITY MODEL

The utility model aims to overcome the defects in the prior art and provide the flue gas condensed water treatment device which has long service life of equipment and high energy utilization rate and is resistant to dew point corrosion.

The technical scheme of the utility model is as follows: a dew point corrosion resistant flue gas condensed water treatment device comprises a flue gas spraying unit, a flue gas heat exchange unit, a condensed water collecting tank, a dosing unit and a control unit which are connected in sequence, wherein the condensed water collecting tank is also connected with the flue gas spraying unit; a Ph detection sensor for detecting the Ph value of the condensed water is arranged in the condensed water collecting pool; the Ph detection sensor is connected with the input end of the control unit, and the output end of the control unit is connected with the dosing unit.

Further, the dosing unit comprises a dosing pump and an alkaline liquid medicine storage container, and the alkaline liquid medicine storage container is connected with the condensate water collecting tank through a dosing pump; the output end of the control unit is connected with a dosing pump.

Further, the flue gas heat exchange unit comprises a heat exchanger body, a cold water inlet, a hot water outlet, a flue gas outlet and a condensed water outlet are formed in the heat exchanger body, and the condensed water outlet is communicated with the condensed water collecting tank.

Further, the flue gas spraying unit comprises a flue gas inlet channel, a flue gas inlet is arranged on the flue gas inlet channel, and a spraying pipe is arranged in the flue gas inlet channel.

Further, a water collecting tray is arranged below the spraying pipe.

Further, an outlet of the water collecting tray is connected with a condensed water collecting tank through a water return pipe.

Furthermore, the preset height of the condensed water collecting tank is provided with a condensed water overflow port, the bottom of the condensed water collecting tank is provided with a sewage discharge outlet, and one side end of the condensed water collecting tank is provided with a dosing port.

Furthermore, a water outlet of the condensation water collecting tank is connected with a condensation water circulating pipe, and the condensation water circulating pipe is connected with the spraying pipe through a circulating pump.

Further, the condensed water collecting tank is separately arranged; or the rear side of the flue gas heat exchange unit is provided with a flue gas output channel, and the condensed water collecting tank is arranged in the flue gas output channel.

The utility model has the beneficial effects that: on one hand, the pH value of the condensed water can be detected in real time, and once the condensed water is acidic, an alkaline medicament is added through the dosing unit to improve the alkalinity of the condensed water, so that the corrosion of equipment is prevented, and the service life of the equipment is prolonged; on the other hand, can make the flue gas of higher temperature before the heat transfer, produce partial vaporization through spraying earlier, reduce the flue gas temperature fast to remaining water smoke can absorb sulfur trioxide, sulfur dioxide and nitrogen oxide therein, becomes very thin acidizing fluid, and under the ordinary condition, its Ph is about 4, can reduce the concentration and the temperature of acid by a wide margin like this, avoids two kinds of dew point corrosion of sulphuric acid and the nitric acid that the flue gas produced, then the heat of full use of flue gas again, improves the energy utilization of flue gas.

Drawings

Fig. 1 is a schematic structural diagram of an embodiment of the present invention.

The attached drawings indicate the following:

1. a condensed water collection tank; 2. a dosing pump; 3. an alkaline liquid medicine storage tank; 4. a flue gas inlet; 5. a shower pipe; 6. a heat exchanger body; 7. a flue gas outlet; 8. a water collection tray; 9. a water return pipe; 10. a condensed water circulating pipe; 11. and a circulating pump.

Detailed Description

The utility model will be described in further detail below with reference to the drawings and specific examples.

As shown in fig. 1: a dew point corrosion resistant flue gas condensed water treatment device comprises a flue gas spraying unit, a flue gas heat exchange unit, a condensed water collecting tank 1, a dosing unit and a control unit which are connected in sequence, wherein the condensed water collecting tank 1 is also connected with the flue gas spraying unit; a Ph detection sensor for detecting the Ph value of the condensed water is arranged in the condensed water collecting pool 1; the PH detection sensor is connected with the input end of the control unit, and the output end of the control unit is connected with the dosing unit.

The scheme has the following advantages: (1) if the acidic gas that contains in the flue gas is more, lead to the condensate water acidity probably to have corrosivity, like the condition such as Ph is less than 5, through setting up Ph detection sensor, can send the Ph value of the condensate water that detects to the control unit, judge by the control unit again whether add the medicine, if add the medicine, add alkaline medicament in the control medicine unit to the condensate water collecting pit to improve the basicity of condensate water, thereby prevent that equipment from taking place the corruption. (2) By arranging the flue gas spraying unit and the flue gas heat exchange unit, the flue gas with higher temperature is firstly sprayed to generate partial vaporization before heat exchange, the temperature of the flue gas is quickly reduced, the residual water mist can absorb sulfur trioxide, sulfur dioxide and nitrogen oxide in the flue gas to form very thin acid liquid, and the Ph of the acid liquid is about 4 under normal conditions, so that the concentration and the temperature of the acid can be greatly reduced, and the corrosion of two dew points of sulfuric acid and nitric acid generated by the flue gas is avoided; the unvaporized flue gas enters the flue gas heat exchange unit to participate in heat exchange, so that the heat of the flue gas is fully utilized, and the energy utilization rate of the flue gas is improved.

In the embodiment, the dosing unit comprises a dosing pump 2 and an alkaline liquid medicine storage tank 3, and the alkaline liquid medicine storage tank 3 is connected with the condensate water collecting tank 1 through a pipeline by the dosing pump 2; the output end of the control unit is connected with the dosing pump 2. Wherein, the dosing pump 2 is a small-sized medicine pump, and can pump the medicine in the alkaline liquid medicine storage tank 3 to the condensed water collecting tank 1, so as to improve the alkalinity of the condensed water collecting tank. Generally, the pH is controlled to be 6-8.5, so that condensed water is kept in a neutral to alkalescent range, acidity can be better neutralized, and corrosion is avoided; can also absorb sulfur oxides and nitrogen oxides, is beneficial to reducing harmful components in the flue gas, and meets the allowable Ph value of the drainage standard. The alkaline chemical solution of the present embodiment includes, but is not limited to, ammonia, ammonium carbonate, sodium carbonate, and sodium hydroxide.

In this embodiment, the control unit includes the controller, and Ph detects the input that the sensor connects the control unit, and the output of controller connects dosing pump 2.

In this embodiment, the flue gas spraying unit includes flue gas inlet channel, is equipped with flue gas inlet 4 on the flue gas inlet channel, is equipped with shower 5 in the flue gas inlet channel, is equipped with a plurality of nozzles on shower 5. The flue gas heat exchange unit comprises a heat exchanger body 6, a cold water inlet, a hot water outlet, a flue gas outlet 7 and a condensed water outlet are formed in the heat exchanger body, and the condensed water outlet is communicated with the condensed water collecting tank 1. After cold water is introduced into the heat exchanger body 6, the cold water exchanges heat with high-temperature flue gas, the cold water is heated to become hot water, the hot water is output from a hot water outlet, after the high-temperature flue gas is cooled, because fuel is combusted, hydrogen elements in the hot water can generate a large amount of water vapor, for example, 16kg of methane can generate 36kg of water after being completely combusted, and when the temperature of the flue gas is reduced to be lower than 58 ℃, the flue gas can generate a large amount of condensed water. Therefore, a part of the cooled flue gas generates condensed water and enters the condensed water collecting tank 1, and the other part of the cooled flue gas forms low-temperature flue gas and is output from the flue gas outlet 7.

Wherein, the smoke outlet 7 and the condensed water outlet can share one outlet or can be respectively arranged. The flue gas outlet 7 may be a channel structure or may be a separate outlet. This embodiment is preferably a channel structure, and a condensate collection tank may also be placed in the channel.

Although the temperature of the flue gas can be reduced by spraying water mist in the hot flue gas, the preheating grade of the flue gas is equivalently reduced, the temperature difference of water in the heat exchanger body is also reduced, and the temperature of hot water discharged from the heat exchanger body can be influenced. However, the flue gas rich in saturated water vapor is rapidly condensed in the heat exchanger body when meeting cold, and the heat exchange coefficient of the water vapor condensation is far higher than that of the forced convection heat exchange of the flue gas. Therefore, the overall heat exchange capacity is rather enhanced, and the hot water temperature is not lowered. A large amount of water vapor condensate is equivalent to slightly acidic softened water, and can continuously wash the accumulated dust of the heat exchanger body, thereby ensuring the stability of heat exchange efficiency.

In this embodiment, a water collecting tray 8 is arranged below the spray pipe 5, and an outlet of the water collecting tray 8 is connected with the condensed water collecting tank 1 through a water return pipe 9. The circulation of the condensed water needs to maintain a larger flow rate so as to ensure that more water mist exists after the water is preheated and vaporized; through setting up water-collecting tray 8 and depositing water and set up 9 backwaters of wet return, can make these deposit water and play the water seal effect, avoid the flue gas to walk around the heat exchanger body.

In the embodiment, a condensed water overflow port is arranged at a preset height of the condensed water collecting tank 1, a sewage discharge port is arranged at the bottom of the condensed water collecting tank, and a chemical adding port is arranged at one side of the condensed water collecting tank; the water outlet of the condensation water collecting pool 1 is connected with a condensation water circulating pipe 10, and the condensation water circulating pipe 10 is connected with the spraying pipe 5 through a circulating pump 11. Tap water can be put into the condensed water collecting tank 1 for circulation at the beginning of system operation or after cleaning and pollution discharge, and after the system operation, the flue gas generates enough condensed water to maintain the water level. Because the flue gas can constantly produce water, through setting up the condensate overflow mouth, when the condensate in the condensate collecting tank is higher than the condensate overflow mouth, discharge in the condensate overflow mouth can be followed to unnecessary condensate to prevent that the condensate in the condensate collecting tank from storing up the overfilling. When the amount of water in the condensed water collecting tank is small and the condensed water collecting tank is not needed to be used, the residual condensed water can be discharged through the sewage draining outlet. When the water amount is small, the water can be directly discharged or collected for use (such as water replenishing of a cooling tower, flushing of a toilet and the like), and when the water amount is large, the water is discharged after the pH is adjusted by adding alkali through a dosing unit.

The working principle of the embodiment is as follows: high-temperature flue gas enters the flue gas inlet channel through the flue gas inlet 4 and is sprayed by the spraying pipe 5 in the flue gas inlet channel, so that the flue gas is partially vaporized after being sprayed, the temperature of the flue gas is reduced, the remaining water mist can absorb sulfur trioxide, sulfur dioxide and nitrogen oxide in the flue gas to form very thin acid liquid, and the pH value of the acid liquid is about 4 under normal conditions, so that the concentration and the temperature of the acid can be greatly reduced, and the corrosion of two dew points of sulfuric acid and nitric acid generated by the flue gas is avoided; the vaporized flue gas becomes condensed water and falls into the water collecting tray 8; the unvaporized flue gas enters the heat exchanger body 6 to exchange heat with cold water in the heat exchanger body 6, the cold water is heated to become hot water and is output from a hot water outlet, after the temperature of the flue gas is reduced, one part of the hot water forms condensed water and enters the condensed water collecting tank 1, and the other part of the hot water forms low-temperature flue gas and is output from a flue gas outlet 7; in the working process, a Ph detection sensor in the condensate collecting pool 1 can detect the Ph value of the condensate in real time and send an instruction to a control unit, when the Ph value is detected to be smaller than 5, the control unit controls a dosing pump 2 to act, the dosing pump 2 can pump the medicament in an alkaline liquid medicament storage tank 3 to the condensate collecting pool 1, and when the Ph detection sensor detects that Ph is larger than 5, the dosing pump 2 is controlled to stop acting, so that the condensate in the condensate collecting pool 1 is prevented from corroding devices such as a condensate circulating pipe, a circulating pump and a spraying pipe.

Claims

1. A dew point corrosion resistant flue gas condensed water treatment device is characterized by comprising a flue gas spraying unit, a flue gas heat exchange unit, a condensed water collecting pool, a dosing unit and a control unit which are sequentially connected, wherein the condensed water collecting pool is also connected with the flue gas spraying unit; a Ph detection sensor for detecting the Ph value of the condensed water is arranged in the condensed water collecting pool; the Ph detection sensor is connected with the input end of the control unit, and the output end of the control unit is connected with the dosing unit.

2. The dew point corrosion resistant flue gas condensate treatment device of claim 1, wherein the dosing unit comprises a dosing pump and an alkaline chemical liquid storage container, and the alkaline chemical liquid storage container is connected with the condensate collection tank through the dosing pump; the output end of the control unit is connected with a dosing pump.

3. The dew point corrosion resistant flue gas condensate treatment device according to claim 1 or 2, wherein the flue gas heat exchange unit comprises a heat exchanger body, a cold water inlet, a hot water outlet, a flue gas outlet and a condensate outlet are arranged on the heat exchanger body, and the condensate outlet is communicated with the condensate collecting tank.

4. The dew point corrosion resistant flue gas condensate treatment device of claim 1 or 2, wherein the flue gas spraying unit comprises a flue gas inlet channel, a flue gas inlet is arranged on the flue gas inlet channel, and a spraying pipe is arranged in the flue gas inlet channel.

5. The dew point corrosion resistant flue gas condensate treatment device of claim 4, wherein a water collection tray is provided below the shower pipe.

6. The dew point corrosion resistant flue gas condensate treatment device of claim 5, wherein the outlet of the water collection tray is connected to a condensate collection tank via a return pipe.

7. The dew point corrosion resistant flue gas condensate treatment device according to claim 1 or 2, wherein a condensate overflow port is arranged at a predetermined height of the condensate collection tank, a drain outlet is arranged at the bottom of the condensate collection tank, and a chemical adding port is arranged at one side end of the condensate collection tank.

8. The dew point corrosion resistant flue gas condensate treatment device of claim 4, wherein the water outlet of the condensate collection tank is connected with a condensate circulating pipe, and the condensate circulating pipe is connected with the spray pipe through a circulating pump.

9. The dew point corrosion resistant flue gas condensate treatment device according to claim 1 or 2, wherein the condensate collection tank is separately provided; or the rear side of the flue gas heat exchange unit is provided with a flue gas output channel, and the condensed water collecting tank is arranged in the flue gas output channel.