Practical operations, routine inspections, fault‑checking and certificate‑related studies for water‑treatment jobs all rely on basic knowledge. This article sorts out 200 well‑polished practical guidelines for water‑treatment work. It covers seven key sections: resin systems, boiler maintenance, chemical dosing, membrane processes, water quality testing, equipment operation and maintenance, plus safety standards. Every point delivers solid know‑how. The material suits new‑comers for entry‑level learning and on‑the‑job staff reviewing contents for certification exams.
Part 1 Core Knowledge of Ion‑Exchange Resin (Points 1‑30)
1.Model 001×7 resin is a strong‑acid cation‑exchange resin and the widely‑used cation resin in power plants.
2.Ion‑exchange resin consists of a high‑polymer framework and functional groups.
3.For resin type 201×7, the first digit “2” stands for strong‑base anion‑exchange resin.
4.The standard filling ratio for power‑plant mixed‑bed is anion resin: cation resin = 2:1.
5.Back‑wash separation of anionic and cationic resin in mixed‑beds relies on their difference in true wet density.
6.Poor‑quality treated‑water after mixed‑bed regeneration is mainly caused by incomplete separation during back‑washing.
7.When separation results are unsatisfactory, dilute NaOH solution of 1%‑2% can be injected for auxiliary separation.
8.Anion‑resin contaminants mainly include oil, organic matter and oxidants, so inflow water needs pre‑treatment.
9.Aging of cation resin is mainly triggered by oxidation and contamination of heavy‑metal ions like iron and aluminum.
10.Lower cross‑linking degree leads to higher water‑holding capacity, better anti‑fouling property yet poorer mechanical strength.
11.Iron‑aluminum pollution darkens resin color and sharply reduces its exchange capacity.
12.New dry resin should be soaked with saturated salt solution to avoid rupture from excessive swelling.
13.Dehydrated and cracked resin can be revived by soaking in 10% salt‑water solution.
14.Density rule: the true wet density of cation resin is higher than that of anion resin.
15.Water‑making via ion‑exchange is essentially the gradual downward movement of the working layer.
16.Resin regeneration is the reverse reaction of ion‑exchange water‑production.
17.Combined weak‑base and strong‑base system: weak‑base resin removes strong‑acid radicals while strong‑base resin gets rid of weak‑acid radicals and reactive silica.
18.A running resin layer is divided into exhausted layer, working layer and protective layer.
19.Chloride ions leak out first when the weak‑base anion bed reaches exhaustion.
20.Hydrogen silicate ions escape first upon strong‑base anion‑bed failure, resulting in excessive silica in outlet water.
21.Only strong‑base anion resin can effectively remove reactive silica present in raw water.
22.Excessively‑concentrated concentrated sulfuric‑acid during cation‑bed regeneration forms calcium‑sulfate precipitates and blocks resin pores.
23.For strong‑acid H‑form cation beds, high sodium‑ion content marks the exhaustion point.
24.After qualified rinsing following mixed‑bed regeneration, effluent conductivity drops rapidly with excellent water quality.
25.Counter‑current regeneration delivers better‑quality effluent with lower chemical consumption; the compacted layer prevents layer disorder during regeneration.
26.Higher regeneration temperature speeds up ion diffusion; the recommended temperature range for anion‑resin regeneration is 30‑45℃.
27.Weight of filled resin = filling volume × bulk wet density.
28.Excessive chloride ions compete for adsorption sites on cation resin and weaken exchange performance.
29.Mixed‑up resin can be separated by back‑washing based on density differences.
30.Anion resin is less stable and more vulnerable to aging and contamination compared with cation resin.
Part 2 Boiler Water‑Steam and Blow‑down Process (Items 31‑60)
31.Boiler blow‑down falls into two types: continuous blow‑down and intermittent blow‑down.
32.Intermittent blow‑down mainly discharges sludge and precipitates inside the boiler to avoid scaling and corrosion.
33.The inlet of continuous blow‑down is placed 200‑300 mm below the drum water level to drain boiler water with high salt content.
34.The continuous blow‑down rate of the boiler shall not be less than 0.30%.
35.Blow‑down rate = Blow‑down water flow ÷ Boiler evaporation capacity ×100%.
36.Phosphate treatment for boiler‑water serves both scale inhibition and anti‑corrosion purposes.
37.Low‑phosphorus treatment is applied for units with hardness‑free feed‑water and eliminates the phosphate hide‑out phenomenon.
38.Control standards for low‑phosphorus mode: phosphate radical 0.5‑3 mg/L, pH 9.0‑9.8, conductivity ≤60 μS/cm.
39.Phosphate dosing and continuous blow‑down start when boiler pressure rises to 1.0 MPa.
40.If feed‑water contains hardness, phosphate radicals shall be kept at the upper limit for enhanced scale prevention.
41.Boiler‑water absorbs heat inside water‑wall tubes and turns into saturated steam.
42.Steam contamination arises from two factors: mechanical carry‑over and dissolved carry‑over.
43.Higher boiler pressure improves the capacity of steam to dissolve impurities.
44.Key indexes for steam quality are silica content and sodium content.
45.When boiler load rises sharply, temporary hide‑out of salts occurs: PO₄³⁻ decreases while alkalinity goes up.
46.Poor‑quality water leads to three major troubles: scaling, salt deposition and metal corrosion.
47.The feed‑water system suffers the most severe oxygen‑corrosion among thermal‑power equipment.
48.Increase the frequency of intermittent blow‑down if boiler‑water becomes turbid.
49.Boiler operators perform intermittent blow‑down under supervision from chemistry staff.
50.Conductivity drops temporarily in the early‑stage exhaustion of the cation bed.
51.Excessive ammonia addition causes ammonia‑corrosion of copper tubes in boilers; accurate dosage control is required.
52.Condensate drain is condensed water generated by steam pipelines and steam‑using equipment.
53.Superheated steam means steam whose temperature exceeds the saturation temperature under its corresponding pressure.
54.Principle of thermal power generation: heat energy is converted into mechanical energy to drive power‑generation.
55.Internals inside the steam‑water drum separate steam and water and cut down mechanical carry‑over rate.
56.Water quality fluctuates heavily during boiler startup and shutdown. Boost blow‑down and strengthen monitoring.
57.Excessively high boiler‑water alkalinity results in foaming and priming, which worsens steam quality.
58.Salt deposits on steam turbine blades block passages and reduce unit efficiency.
59.Intermittent blow‑down needs short‑time full‑valve opening at high flow‑rate for thorough sludge removal.
60.Continuous blow‑down steadily reduces salt content of boiler‑water and maintains reliable steam quality.
Part 3 Feed‑Water Deaeration and Chemical‑Dosing Operation & Maintenance (Items 61‑85)
61.Feed‑water deaeration includes thermal deaeration and chemical deaeration.
62.Ammonia is dosed into feed‑water to keep pH between 8.8‑9.3 and prevent acid‑induced corrosion from carbon dioxide.
63.Hydrazine is added to remove residual dissolved oxygen and restrain oxygen‑corrosion inside pipelines.
64.Ammonia solution is injected at the down‑comer of the deaerator.
65.The ammonia‑dosing pump runs with continuous tiny flow adjustment during normal unit operation.
66.If pH remains high even with the minimum pump stroke, dilute the ammonia solution.
67.Unqualified dissolved‑oxygen content in feed‑water is mostly caused by abnormal working conditions of the deaerator.
68.Startup procedure for metering pump: open the outlet valve first, then start the pump.
69.Shutdown procedure for metering pump: shut down the pump before closing the outlet valve to prevent back‑siphonage.
70.Standard oil level for metering pumps ranges from 1/3 to 2/3 of the sight glass.
71.Change lubricating oil two weeks after commissioning for new or overhauled pumps, then replace oil once every three months afterwards.
72.Stop the pump right away when bearing temperature exceeds 75℃ and switch to the standby pump.
73.Vibration standard for centrifugal pumps: ≤0.7 mm for rotating speed below 1800 r/min; ≤0.06 mm for 1800‑4500 r/min.
74.The vibration value of metering‑pumps at 200‑400 r/min shall be less than 0.15 mm.
75.If pump pressure rises yet no water is delivered and valves work properly, the outlet pipeline is clogged.
76.Test insulation resistance for motors kept idle for over 15‑days before startup.
77.A pneumatic diaphragm valve consists of a valve body and a pneumatic actuator.
78.Fully drain and flush sampling pipelines given poor‑quality water during unit startup.
79.Constant‑temperature units for online instruments maintain temperature at 25±2℃ to guarantee precise readings.
80.A cooler must be installed for every water‑steam sampling assembly.
81.Water samples for conductivity and sodium‑content tests need pretreatment via a hydrogen‑ion exchange column.
82.Metal corrosion rate serves as the core evaluation index for chemical‑cleaning outcomes.
83.Make‑up water pretreatment in power plants covers chemical treatment and heating treatment.
84.Water‑stabilizing treatment is the mainstream process for scale inhibition of cooling‑water.
85.Calibrate dosing accuracy of the chemical‑adding system regularly to avoid incorrect dosage.
Part 4 Filtration, Ultra‑filtration and Reverse Osmosis Processes (Items 86‑115)
86.Impurities in raw natural water fall into three categories: suspended solids, colloids and dissolved contaminants.
87.Filtration works through mechanical interception and surface adsorption.
88.Filtration is classified into mechanical filtration and adsorptive filtration.
89.Filter performance is affected by filtration velocity, backwash intensity, duration and flow‑water uniformity.
90.Coagulation efficiency depends on water temperature, pH value, chemical dosage, water quality and reaction time.
91.Coagulation can reduce turbidity and slightly lower water hardness.
92.Activated‑carbon filters remove residual chlorine and organic matter so as to protect membrane elements.
93.Iron‑removal filters trap contaminants via porous filter cartridges with combined air‑water backwashing.
94.Self‑cleaning filters perform automatic backwash according to fixed time or pressure‑difference, while backwash pumps keep running continuously.
95.Ultrafiltration and reverse‑osmosis systems share one cleaning system including acid washing and alkaline washing.
96.Reverse‑osmosis membranes only allow water molecules to pass through while intercepting salts and macromolecular pollutants.
97.When water temperature rises, RO salt rejection decreases and recovery rate increases; lower temperature reduces recovery rate.
98.RO permeate flow is proportional to water temperature, and pH of product water is around 6.0.
99.A resin trap is installed at mixed‑bed outlet to avoid resin loss and subsequent equipment blockage.
100.The floating‑bed adopts top‑to‑bottom counter‑current regeneration without the risk of layer disorder.
101.White spheres inside floating‑beds protect resins and prevent blockage of water‑collecting devices.
102.Shut down the floating‑bed and clean resins when pressure difference reaches or exceeds 0.2 MPa.
103.Floating‑bed resins are cleaned externally, with demineralized‑water as the resin‑transport medium.
104.In decarbonators, water flows downwards and air moves upwards in counter‑current mode to strip off CO₂.
105.Higher water permeability of RO membranes brings larger permeate output and lower salt‑rejection rate.
106.Resins with better particle uniformity deliver more stable operating performance.
107.Conductivity and silica content are the key monitoring indexes for anion beds.
108.Higher inlet‑water acidity improves the utilization rate of anion‑exchange resin.
109.Condensate with unqualified TOC must drain directly to the wastewater tank and is prohibited from entering downstream systems.
110.Coagulation tests help confirm the optimum chemical dosage and pH value.
111.Contaminated resins feature reduced exchange capacity, increased pressure difference and poor‑quality outlet water.
112.Resins in the compacted‑layer during counter‑current‑regeneration avoid layer‑disorder.
113.Mixed‑bed startup steps: open vent and feed‑water valves → open drain valve until the water turns qualified → open product‑water valve.
114.Bicarbonate ions mainly contribute to alkalinity of natural raw water.
115.Reverse‑osmosis systems need regular flushing to prevent scaling and fouling on membrane surfaces.
Part 5 Water‑Quality Indexes and Basic Chemical Knowledge (Items 116‑150)
116.COD stands for Chemical Oxygen Demand, which shows the pollution level of organic substances in water.
117.The unit of water conductivity is μS/cm.
118.Qualified standards for demineralized water: hardness nearly zero, SiO₂ ≤20 μg/L, conductivity ≤0.2 μS/cm.
119.The normal pH range of demineralized‑water is 6.5‑7.5.
120.Calcium ions and magnesium ions are the main ions contributing to water hardness.
121.Alkaline water refers to water whose alkalinity is higher than its hardness value.
122.pH is the negative logarithm of hydrogen‑ion concentration. Lower pH means stronger acidity.
123.pH =7 is neutral; below 7 is acidic; above 7 is alkaline. Free CO₂ no longer exists when pH≥8.3.
124.Law of mass conservation: total mass remains unchanged before and after chemical reactions.
125.Neutralization reaction means acids react with bases to produce salt and water.
126.A solution consists of solvent and solute.
127.Buffer solutions resist impacts from acids or alkalis and stabilize pH values.
128.Oxidation‑reduction rule: substances losing electrons act as reducing agents while electron‑gaining materials are oxidizing agents.
129.Matters exist in solid, liquid and gas states, and phase conversion happens with changed working conditions.
130.An element is a general term for atoms with the same nuclear charge number (proton number).
131.The solubility of air in water drops with rising water temperature and pressure.
132.Conductivity is positively related to water temperature. Higher temperature increases water‑conductivity.
133.Chemical reaction speed is affected by temperature, reactant concentration and catalysts.
134.Molecular formula of sulfuric acid: H₂SO₄; trisodium phosphate: Na₃PO₄.
135.Industrial sodium‑hydroxide solution usually contains a small amount of sodium carbonate impurities.
136.Strong‑alkaline solutions shall never be stored in glass containers, for they corrode glass and release silicon impurities.
137.If the solution turns blue after scale samples dissolve in sulfuric acid, copper scale can be confirmed.
138.The static sodium‑ion test adopts calomel electrode with 0.1mol/L KCl solution.
139.A hanging drop left on the tip of burette will produce higher test readings.
140.Gauge‑pressure conversion formula: Gauge pressure = Absolute pressure minus local atmospheric pressure.
141.Raw water is untreated natural‑source water. Softened water is water with calcium‑magnesium hardness removed.
142.Free carbon‑dioxide is almost completely eliminated when water pH is above or equal to 8.3.
143.Aged or contaminated resin brings lower exchange capacity, poor‑quality outlet water and increased pressure difference.
144.Three major systems of thermal‑power plants are the water‑steam system, electric system and coal‑handling system.
145.Sulfur dioxide is the main air pollutant from power‑plant flue‑gas.
146.Molecules move faster with higher water‑temperature, which speeds up overall reaction rates during water‑treatment.
147.Salt from strong‑acid and strong‑base shows neutral property and will not change the basic pH of water.
148.Dissolved impurities have extremely tiny particle size and cannot be removed via filtration or sedimentation.
149.Colloidal particles stay stable due to surface electric charges; regular sedimentation does not work, so coagulation is required for destabilization.
150.Standard sampling is required for water‑quality analysis to avoid inaccurate readings caused by pollution and volatile loss.
Part 6 Safety Specifications and Post‑work Rules (Items 151‑180)
151.The core guideline for safe production: safety comes first, prevention is prioritized.
152.Safety refers to a stable state free from hazards, accidents and injuries during production.
153.Working at height is defined as operations 2 meters or higher above ground. Safety belts are compulsory.
154.Two key permits for power‑safety management are work permit and operation permit. All tasks shall be carried out by certified staff.
155.Three unsafe behaviors include illegal command, rule‑breaking operation and violation of labor disciplines.
156.The first‑aid step for electric shock is to cut off power supply right away. Rescue while equipment is live is strictly forbidden.
157.Perform external chest compression immediately if the victim suffers cardiac arrest from electric shock.
158.Acid‑resistant gloves and face shields must be worn while handling acids and alkalis.
159.Emergency treatment for acid burns: flush with plenty of clean water, then neutralize with 5% sodium‑bicarbonate solution.
160.An acid‑mist absorber removes acid‑mist waste gas to protect workers and avoid environmental pollution.
161.Pencils are prohibited for operation logs and data records to guarantee permanent traceability.
162.Emergency wash‑water and protective gears shall be equipped around chemical tanks and dosing zones.
163.The supervision‑system and operation‑permit system must be followed strictly for startup, shutdown and switch‑over of equipment.
164.Single‑person operation is banned during resin loading‑unloading as well as acid‑alkali preparation.
165.Power‑off, power‑checking, tag‑hanging and lock‑out are required before maintenance of electrical devices.
166.Insulation tests shall be strengthened for tasks in damp surroundings to prevent electric‑shock incidents.
167.Waste‑water and waste‑liquid must be collected and treated in compliance with rules. Direct discharge is forbidden.
168.Chemical agents are stored by categories. Acids and alkalis are separated; flammable and explosive goods are kept independently.
169.Focus points of routine inspection: water‑quality indexes, equipment pressure, temperature, vibration and liquid level.
170.Personal safety is given top priority under abnormal conditions before dealing with equipment and water‑quality troubles.
171.Wear protective equipment and prepare chemical reagents in strict accordance with proportion requirements.
172.Do not take samples directly under high‑temperature or high‑pressure conditions. Cooling and pressure reduction are required beforehand.
173.Shut down equipment for troubleshooting promptly if over‑temperature, over‑pressure or excessive vibration occurs.
174.Keep monitoring liquid level, chemical concentration and duration throughout resin regeneration and cleaning.
175.Since the reverse‑osmosis system runs under high‑pressure conditions, pipe fittings and membrane housings cannot be disassembled under pressure.
176.Once leakage occurs in the dosing system, stop pumps, isolate the area and improve ventilation.
177.Follow operating procedures closely during titration and instrument‑testing to ensure accurate test results.
178.Hand‑over staff should share information about water‑quality, equipment status, running conditions and abnormal issues.
179.Regularly inspect old‑style equipment to find hidden risks and avoid leakage, corrosion and breakdowns.
180.Core values of water‑treatment: ensuring equipment safety, stabilizing water quality and saving energy with low‑emission.
Part 7 Supplementary Frequently‑Used Practical Knowledge (Items 181‑200)
181.When cation resin gets contaminated by heavy‑metal ions, its exchange capacity drops sharply and outlet‑water quality deteriorates.
182.Higher salt content in water brings up conductivity values and strengthens electrical conductivity.
183.Properly increased temperature of regenerant solution greatly improves the regeneration completeness of resin.
184.Severe load fluctuation of boilers easily causes short‑term excess limits of steam‑water quality.
185.The low‑phosphate treatment delivers the best scale‑inhibition and anti‑corrosion effect for feed‑water with low‑hardness.
186.Dissolved carry‑over of steam serves as the main cause of excessive silica in high‑pressure units.
187.Steadily rising pressure difference of filters indicates filter media is blocked with excessive trapped impurities.
188.Ultrafiltration mainly removes colloids, suspended solids and macromolecular organic substances from raw water.
189.Reverse osmosis can eliminate most salts, heavy metals, bacteria and colloids in water.
190.For long‑term shutdown of resin, regular flushing and moisturizing are required to avoid cracking and contamination.
191.Excessive mixing of cation and anion‑resin directly degrades mixed‑bed effluent and shortens its service cycle.
192.Low‑pH feed‑water will aggravate acid‑corrosion inside pipelines and equipment.
193.Low alkalinity of boiler‑water weakens buffer capacity and results in localized corrosion.
194.Chemical cleaning effectively gets rid of scaling, salt deposits and biological slime on equipment.
195.Intensify blow‑down and index monitoring because water quality fluctuates greatly during unit startup and shutdown.
196.Accurate chemical dosing and stable water‑quality are critical to extend the service life of thermal‑power equipment.
197.Ion‑exchange desalination applies to raw water with medium‑to‑low salinity, while reverse osmosis works for pretreatment of high‑salinity raw‑water.
198.Stable water quality and reliable equipment provide fundamental support for safe and economical operation of power‑generating units.
199.Standardized operation, routine maintenance and precise monitoring greatly reduce failure rates of water‑treatment systems.
200.Basic knowledge of water‑treatment is the foundation for on‑site operation, fault analysis and process optimization.
