CN209922985U - Circulating water corrosion control system of indirect air cooling unit of thermal power factory - Google Patents
Circulating water corrosion control system of indirect air cooling unit of thermal power factory Download PDFInfo
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- CN209922985U CN209922985U CN201920564202.7U CN201920564202U CN209922985U CN 209922985 U CN209922985 U CN 209922985U CN 201920564202 U CN201920564202 U CN 201920564202U CN 209922985 U CN209922985 U CN 209922985U
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Abstract
The utility model discloses a circulating water corrosion control system of an indirect air cooling unit in a thermal power plant, which comprises an indirect cooling tower, a condenser, a circulating water pump, a carbon dioxide storage tank, a water delivery pipeline, a detector and a controller; the outlet of the indirect cooling tower is communicated with the inlet of the condenser, the outlet of the condenser is communicated with the inlet of the circulating water pump, the outlet of the circulating water pump and the outlet of the carbon dioxide storage tank are communicated with the inlet of the indirect cooling tower through a water conveying pipeline after being connected in parallel through a pipeline, a sampling port on the pipeline between the outlet of the condenser and the inlet of the circulating water pump is communicated with the inlet of the detector, the output end of the detector is connected with the input end of the controller, and the output end of the controller is connected with the control end of the carbon dioxide storage tank.
Description
Technical Field
The utility model belongs to the technical field of chemistry and chemical engineering technique and new forms of energy and energy-conserving, a indirect air cooling unit circulating water corrosion control system of thermal power factory is related to.
Background
At present, the enterprise standard mainly refers to the execution provided by manufacturers, and combines the circulating water quality requirements of a surface indirect air cooling system in DL/T1717-2017 'chemical supervision technical guide rule of a gas-steam combined cycle power plant', and provides basic requirements for indexes such as pH value, conductivity and oxygen content of normal working circulating water of a thermal power unit: pH 6.5-8.5 (no more than 9 is allowed at any time); the conductivity (25 ℃) is less than 10 mu S/cm; circulating water O230-300 mu g/L, and the content of silicon dioxide is less than or equal to 20 mu g/L.
According to the feedback of the practical operation experience of the indirect air cooling unit of the thermal power plant, the electrochemical state of a ternary corrosion system of carbon steel, stainless steel and 1050A pure aluminum exists in a circulating water system, although high-quality desalted water is used in the circulating water system adopting pure aluminum as the air cooling radiator construction material, water quality deterioration occurs in the construction stage and operation, the pH suddenly rises (the aluminum material starts to corrode when the pH is 8.5, and the aluminum material starts to corrode when the pH is 9), the production accident that the 1050A pure aluminum air cooling radiator is seriously corroded and leaked to cause the unit shutdown is caused, and great threat is caused to the safe operation of the indirect air cooling unit. The indirect air cooling circulating water system has large water storage capacity, and the method for controlling the pH value of the circulating water only by changing water is not ideal and runs counter to the water-saving design idea; the adoption of the circulating water cation bed treatment process effectively reduces the pH value of the circulating water of the unit, and has good effect, larger one-time investment and large workload of later-period operation and maintenance; a small amount of phosphoric acid or ammonia water is added into the circulating water to adjust the pH value, although the pH value can be controlled within a certain range, the corrosion risk of the pipe is reduced, the salt content in the desalted water is increased, and the conductivity is also increased.
The three methods adjust the circulating water quality of the indirect cooling circulating system from different angles and control the pH value of the water quality, but the application in the indirect cooling circulating water system is still imperfect at present, basic type compound research needs to be strengthened, the investment is controlled, the later-stage operation cost is saved, a cross experiment is developed, and the application is convenient to expand.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to overcome above-mentioned prior art's shortcoming, provide a indirect air cooling unit circulating water corrosion control system of thermal power factory, this system can effectively solve and cause water waste, circulating water by-pass flow to handle the problem that investment is big fortune dimension with high costs and circulating water adds medicine and handles quality of water index and be difficult to control the electric conductance and rise among the prior art through replacing partial circulating water that exists.
In order to achieve the purpose, the system for controlling the circulating water corrosion of the indirect air cooling unit of the thermal power plant comprises an indirect cooling tower, a condenser, a circulating water pump, a carbon dioxide storage tank, a water conveying pipeline, a detector and a controller;
the outlet of the indirect cooling tower is communicated with the inlet of the condenser, the outlet of the condenser is communicated with the inlet of the circulating water pump, the outlet of the circulating water pump and the outlet of the carbon dioxide storage tank are communicated with the inlet of the indirect cooling tower through a water conveying pipeline after being connected in parallel through a pipeline, a sampling port on the pipeline between the outlet of the condenser and the inlet of the circulating water pump is communicated with the inlet of the detector, the output end of the detector is connected with the input end of the controller, and the output end of the controller is connected with the control end of the carbon dioxide storage tank.
The inlet of the detector is communicated with the sampling port through a first control valve.
And a second control valve is arranged at an outlet of the carbon dioxide storage tank, and the output end of the controller is connected with the control end of the second control valve.
The outlet of the carbon dioxide storage tank is communicated with the water pipeline through a third control valve.
The controller is a PLC controller.
The detector is a pH value detector, a carbon dioxide concentration detector or a carbonate concentration detector.
The utility model discloses following beneficial effect has:
indirect air cooling unit circulating water corrosion control system of thermal power factory when concrete operation to carbon dioxide gas is the medicament, through adding carbon dioxide gas to the circulating water of intercooling unit in, thereby ionize out H in circulating water+Ions to lower the pH of the circulating water and thereby inhibit the chemistry of the system materialsThe corrosion reaction can not produce new corrosion products simultaneously, and then reduce the risk of system corrosion, reduces the hidden danger of unit safe operation, compares safe and reliable more with other medicament and processing method, can practice thrift a large amount of demineralized water, simple structure, convenient operation, once investment and maintenance cost are extremely low, economic benefits and environmental protection benefit are showing.
Drawings
Fig. 1 is a schematic structural diagram of the present invention.
Wherein, 1 is a condenser, 2 is an indirect cooling tower, 3 is a circulating water pump, 4 is a third control valve, 5 is a carbon dioxide storage tank, 6 is a controller, 7 is a detector, and 8 is a first control valve.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings:
free carbon dioxide in water is very unstable and is easily affected by factors such as temperature, pressure, time, etc. The circulating water of the indirect cooling system is in closed circulation, the pressure is generated by the static pressure of the cooling tower and the circulating water pump 3, the dissolution of the carbon dioxide gas in the desalted water is increased along with the increase of the pressure, and the dissolution of the carbon dioxide gas in the desalted water is reduced along with the increase of the water temperature. Free carbon dioxide gas is easily escaped from the water body. Under normal working condition, the water temperature of the circulating water of the indirect cooling unit is generally lower than 60 ℃, and in the area of lower than 60 ℃, a protective corrosion product protective film can be formed after the chromium-containing steel is corroded, so that the corrosion rate is slowed down; after carbon dioxide is added into circulating water of the indirect cooling unit, the partial pressure of the carbon dioxide is extremely low, and when the partial pressure of the carbon dioxide is lower than 0.02MPa, the corrosion can be ignored.
It should be noted that the indirect cooling unit carbon dioxide technology adjusts the pH value based on the property of carbon dioxide, which is called carbonic anhydride, is one of carbon oxides, is an inorganic substance, and is non-toxic at low concentrations. Carbon dioxide can be dissolved in water and reacts with water to generate carbonic acid, while unstable carbonic acid is easily decomposed into water and carbon dioxide, and free carbon dioxide escapes, wherein the chemical reaction equation in water is as follows:
H2O+CO2＝H2CO3
H2CO3＝H2O+CO2↑
the hydrogen ions react with the hydroxyl ions in the water to generate water, other impurity ions cannot be additionally added, the pH value of the circulating water is effectively reduced, the alkaline corrosion of the tube bundle of the indirect cooling radiator and the chemical corrosion of a system are effectively controlled, and the water quality index of the circulating water is controlled within a reasonable range.
Based on the above principle, referring to fig. 1, the system for controlling the corrosion of the circulating water of the indirect air cooling unit in the thermal power plant of the present invention comprises an indirect cooling tower 2, a condenser 1, a circulating water pump 3, a carbon dioxide storage tank 5, a water pipeline, a detector 7 and a controller 6; the outlet of the indirect cooling tower 2 is communicated with the inlet of the condenser 1, the outlet of the condenser 1 is communicated with the inlet of the circulating water pump 3, the outlet of the circulating water pump 3 and the outlet of the carbon dioxide storage tank 5 are communicated with the inlet of the indirect cooling tower 2 through a pipeline after being connected in parallel, a sampling port on the pipeline between the outlet of the condenser 1 and the inlet of the circulating water pump 3 is communicated with the inlet of the detector 7, the output end of the detector 7 is connected with the input end of the controller 6, and the output end of the controller 6 is connected with the control end of the carbon dioxide storage tank 5.
The inlet of the detector 7 is communicated with the sampling port through a first control valve 8; a second control valve is arranged at the outlet of the carbon dioxide storage tank 5, and the output end of the controller 6 is connected with the control end of the second control valve; the outlet of the carbon dioxide storage tank 5 is communicated with a water pipeline through a third control valve 4; the controller 6 is a PLC controller; the detector 7 is a pH value detector, a carbon dioxide concentration detector or a carbonate concentration detector.
The utility model discloses a concrete working process does:
when the detector 7 is a pH value detector, detecting the pH value of circulating water in a pipeline between the outlet of the condenser 1 and the inlet of the circulating water pump 3 in real time through the detector 7, and when the pH value of the circulating water in the pipeline between the outlet of the condenser 1 and the inlet of the circulating water pump 3 exceeds a preset pH value, controlling a second control valve, and intermittently filling carbon dioxide gas into the circulating water in the water pipeline through a carbon dioxide storage tank 5 so as to enable the pH value of the circulating water in the pipeline between the outlet of the condenser 1 and the inlet of the circulating water pump 3 to be within a preset pH value range;
when the detector 7 is a carbonate concentration detector, detecting the carbonate concentration of the circulating water in the pipeline between the outlet of the condenser 1 and the inlet of the circulating water pump 3 in real time through the detector 7, and when the carbonate concentration of the circulating water in the pipeline between the outlet of the condenser 1 and the inlet of the circulating water pump 3 is less than or equal to a preset carbonate concentration value, controlling a second control valve, and intermittently filling carbon dioxide gas into the circulating water in the water pipeline through a carbon dioxide storage tank 5 to enable the carbonate concentration of the circulating water in the pipeline between the outlet of the condenser 1 and the inlet of the circulating water pump 3 to be within a preset carbonate concentration range;
when the detector 7 is a carbon dioxide concentration detector, the carbon dioxide concentration of the circulating water in the pipeline between the outlet of the condenser 1 and the inlet of the circulating water pump 3 is detected in real time through the detector 7, when the carbon dioxide concentration of the circulating water in the pipeline between the outlet of the condenser 1 and the inlet of the circulating water pump 3 is smaller than or equal to a preset carbon dioxide concentration value, the second control valve is controlled, carbon dioxide gas is intermittently filled into the circulating water in the water pipeline through the carbon dioxide storage tank 5, and the carbon dioxide concentration of the circulating water in the pipeline between the outlet of the condenser 1 and the inlet of the circulating water pump 3 is enabled to be within a preset carbon dioxide.
Example one
The pH value of the circulating water is controlled by adopting a mode of directly adding carbon dioxide gas into an indirect cooling circulating water system, good effect is obtained in engineering example application, indexes such as the pH value, the conductivity and the like can be controlled within a reasonable range, and a table 1 shows that CO is added into a certain power plant2Adjusting a water quality table, wherein carbon dioxide gas is added from October, and the data shows that the pH value, the conductance and the Al content of the water are gradually reduced after the carbon dioxide gas is added.
TABLE 1
| Date | pH | Conductivity/(μ S/cm) | Aluminum/(μ g/L) | Iron/(μ g/L) |
| 10 months and 26 days | 9.23 | 31.88 | 1594 | 2940 |
| 10 month and 28 days | 9.03 | 19.32 | 1328 | 2798 |
| 10 months and 31 days | 8.94 | 19.20 | 1137 | 2735 |
| 11 month and 1 day | 8.89 | 17.80 | 1034 | 2615 |
| 11 month and 2 days | 8.84 | 16.06 | 799.3 | 2450 |
| 11 month and 3 days | 8.78 | 15.40 | 694.2 | 2379 |
| 11 month and 4 days | 8.69 | 15.02 | 657.2 | 2070 |
| 11 month and 5 days | 8.68 | 14.82 | 654.5 | 2032 |
| 11 month and 6 days | 8.45 | 13.78 | 647.5 | 2756 |
| 11 month and 7 days | 8.42 | 10.76 | 549.0 | 1586 |
| 11 month and 8 days | 8.10 | 10.21 | 462.4 | 1287 |
| 11 month and 10 days | 7.97 | 10.03 | 429.2 | 715.8 |
| 11 month and 12 days | 7.71 | 9.510 | 382.5 | 654.4 |
| 11 months and 14 days | 7.52 | 9.350 | 351.9 | 497.1 |
| 11 month and 18 days | 7.51 | 7.220 | 124.7 | 271.3 |
| 11 month and 20 days | 7.49 | 6.640 | 91.40 | 205.2 |
| 11 month and 22 days | 8.19 | 4.630 | 66.40 | 92.10 |
In the embodiment, carbon dioxide is added into the circulating water to effectively control the pH value, so that the pH value is controlled within a reasonable range for a long time, and other water quality indexes can be controlled and maintained at a good level.
At the debugging stage, because equipment manufacturing defect in earlier stage, the anticorrosive impaired or washing stage of installation stage are because newly-built the unit demineralized water yield is limited originally, lead to washing nonconformity, take place the pH value and rise, for preventing that the equipment body from further corroding, adopt to add the aqueous ammonia to adjust pH usually, the reaction of the carbon dioxide of aqueous ammonia and demineralized water divides two steps to go on:
NH3H2O+CO2＝NH4HCO3
NH4HCO3+NH4OH＝(NH4)2CO3+H2O
as can be seen from the above reaction equation, the reaction between ammonia water and carbon dioxide in desalted water is weak acid and weak base, and the final result is weak base with less free H+And OH-Chemical equilibrium is achieved, the ammonia adding treatment can slow down the corrosion of the pipe by controlling the pH value of the circulating water within a certain range, but certain difficulty exists in the aspect of ammonia adding control, and the conductivity can also rise, so the effect of the ammonia adding mode is not ideal, and the ammonia adding mode is not recommended to use.
Starting from the system debugging operation and the carbon dioxide addition, through long-time water quality testing analysis and examination under different operation conditions at different stages, the circulating water quality is good, indexes such as pH value, iron and aluminum are always kept in a reasonable range, the influence of corrosion of system materials is obviously reduced, the service life of indirect cooling equipment is prolonged, and the long-term safe and reliable operation of a unit is ensured.
And starting a circulating water pump 3 to carry out circulating flushing, detecting the pH value, the conductivity, the iron content, the aluminum content and suspended matters of the circulating water, draining when the conductivity of the circulating water exceeds 50 mu S/cm, and replacing with desalted water. When the conductivity is less than 10 mu S/cm and the pH value is 6.5-8.2, the water is qualified by washing, then the water is sequentially washed by desalted water on the cooling triangles, each cooling triangle is washed by the brine for 3-4 h, the quality of the circulating water is continuously detected, the quality mainly comprises the pH value, the conductivity and the aluminum content, the change conditions of the pH value and the aluminum content of the circulating water are closely noticed, and the water quality is ensured to reach the standard. And after the operation is started, when the pH value of the circulating water is more than or equal to 8.5, adding carbon dioxide gas into the circulating water, so that the pH value of the circulating water is adjusted to 7.2-8.3.
What need to explain, the utility model discloses regard as gaseous medicament with carbon dioxide, the low price is convenient to purchase, easily accurate control and interpolation, the weak acid environment that forms after dissolving improves softly to intercooling system water quality, more do benefit to control, and very limited to circulating water conductance's influence, do not introduce other ions simultaneously, effectively restrain the chemical corrosion reaction of influence system material, combine the addition of automatic dosing system accurate control (the pressure of decompression adjustment gas, the flow) carbon dioxide, effectively reduce the corruption of the erosive carbon dioxide in the circulating water to system metal, make pH value control at reasonable within range, guarantee circulation water quality safety.
Claims (6)
1. A circulating water corrosion control system of an indirect air cooling unit of a thermal power plant is characterized by comprising an indirect cooling tower (2), a condenser (1), a circulating water pump (3), a carbon dioxide storage tank (5), a water conveying pipeline, a detector (7) and a controller (6);
the outlet of the indirect cooling tower (2) is communicated with the inlet of the condenser (1), the outlet of the condenser (1) is communicated with the inlet of the circulating water pump (3), the outlet of the circulating water pump (3) and the outlet of the carbon dioxide storage tank (5) are communicated with the inlet of the indirect cooling tower (2) through a water pipeline after being communicated through a pipeline, a sampling port on the pipeline between the outlet of the condenser (1) and the inlet of the circulating water pump (3) is communicated with the inlet of the detector (7), the output end of the detector (7) is connected with the input end of the controller (6), and the output end of the controller (6) is connected with the control end of the carbon dioxide storage tank (5).
2. The indirect air cooling unit circulating water corrosion control system of the thermal power plant according to claim 1, wherein an inlet of the detector (7) is communicated with the sampling port through a first control valve (8).
3. The indirect air cooling unit circulating water corrosion control system of the thermal power plant according to claim 2, wherein a second control valve is arranged at an outlet of the carbon dioxide storage tank (5), and an output end of the controller (6) is connected with a control end of the second control valve.
4. The indirect air cooling unit circulating water corrosion control system of the thermal power plant according to claim 3, wherein an outlet of the carbon dioxide storage tank (5) is communicated with the water pipeline through a third control valve (4).
5. The indirect air cooling unit circulating water corrosion control system of the thermal power plant according to claim 1, wherein the controller (6) is a PLC controller.
6. The indirect air cooling unit circulating water corrosion control system of thermal power plant according to claim 1, wherein the detector (7) is a pH detector, a carbon dioxide concentration detector or a carbonate concentration detector.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110028145A (en) * | 2019-04-23 | 2019-07-19 | 李卫 | A kind of thermal power plant indirect air cooling unit Circulating Water Corrosion control system and method |
| CN111807495A (en) * | 2020-08-05 | 2020-10-23 | 西安热工研究院有限公司 | Water quality control device and method for preventing corrosion of indirect air-cooling circulating water system |
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- 2019-04-23 CN CN201920564202.7U patent/CN209922985U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110028145A (en) * | 2019-04-23 | 2019-07-19 | 李卫 | A kind of thermal power plant indirect air cooling unit Circulating Water Corrosion control system and method |
| CN111807495A (en) * | 2020-08-05 | 2020-10-23 | 西安热工研究院有限公司 | Water quality control device and method for preventing corrosion of indirect air-cooling circulating water system |
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