热能与动力工程专业毕业论文外文资料及译文.doc

Water Treatment System1, the automatic water softener works: The hardness of the water main by one of the cations: calcium (Ca2 +), magnesium (Mg2 +) ion composition.Ion exchange method is the use of on exchange resins in the exchangeable cations (eg Na, H), the water contains Ca, Mg exchange out of the water decreased Ca, Mg content, a process known as water softening, the use ofdevice called ion exchange, also known as water softeners.As with the hardness of raw water through the exchanger resin layer, the water of calcium and magnesium ions adsorbed by the resin, while the release of sodium ions, so that the water comes out of the switch is softened to remove hardness ions, when the resin adsorption of calciumand magnesium ions up to a certain degree of saturation, the water hardness increases, then water softener will be automatically carried out according to a predetermined failure of regeneration of the resin, the use of higher concentrations of sodium chloride solution (salt water) through the resin, the failurerestore the resin to the sodium resin.2, the main features of automatic softener: 1) The high degree of automation, water conditions, long service life.Full automatic, just on a regular basis with salt, without human intervention. 2) high efficiency, low energy consumption, low operating costs.The overall design of the water softener is reasonable, the exchange capacity of the resin given full play, the energy consumption of the device itself was significantly lower than the general index softened water equipment, automatic control devices do not need full-time operators, which gave the user withto many of the facilities, and produce good economic returns. 3) equipment, compact structure, small footprint, no special equipment foundation, placed on the flat concrete floor can be. 4) easy to use, installation, commissioning, operation is simple, stable performance control unit, able to remove the users worries. 5) corrosion resistance, anti-pollution, lead-free brass control valve, lined with the exchange of non-toxic PE plastic cans, PE plastic material of the salt boxes, which are sufficient to ensure that the equipment corrosion, anti-pollution, non-toxic, tasteless, excellent sound performance.3, automatic softener range of applications: Industrial boilers, central air conditioning, heat exchangers, hotels, food and chemical industry, printing and dyeing laundry, health and other needs soften water to prevent scale class produces a variety of industries.4, automatic softener product structure:Fully automatic water softener consists of three parts: 1) U.S. original controller (including computer control and multi-valve system to the set); 2 U.S. imports or domestically produced tank parts (including exchange tanks and salt tank, optional glass fiber reinforced materials, carbon steel rubber lined, stainless steel); 3) equipment accessories parts (including upper and lower water distributor, central tube, salt valves, Salt, salt tubes, sewage pipes, filters, solenoid valves, etc.);5, automatic softener technical indicators: 1) water pressure :0.25-0 .45 MPa, the best to 0.3MPa; 2) water hardness: 6.5mmol / L (if the raw water hardness exceeds this index, need to re-design); 3) the water hardness: 0.03mmol / L; 4) The water temperature :2-50 ; 5) Power: AC22DV 50Hz, power 10-50W; 6) Resin Type: 00lx7 strong acid cation resin (optional imported and domestic brands); 7) Body material: high strength plastic or brass; 8) Tank Material: FRP winding (available on request allocation of carbon steel rubber lined, stainless steel tank);9) Water consumption: 2% of water production; salt consumption: 100 g / g-equivalent power consumption :3-40WAutomatic softener is softening and regeneration of run automatically control each step, and use of time, flow or other sensors, etc. to start regeneration.The basic form automatic softener is: FLECK or Autotrol multi-control valve, resin tank (with 001 * 7 resin), salt boxes and piping systems.6, automatic softener features: Water softening process automation: process control devices via the device, to achieve ion exchange and resin regeneration process automation. High: water softener designed, effective work of the resin exchange capacity into full play. Provincial workers: no hand operation, easy installation. Non-toxic: lead-free brass or plastic valve body. Provincial Water: more than 98% of water. Power: As the use of siphon principle, renewable without salt pump.Easy to adjust: the regeneration cycle can be adjusted as needed and time.Tank corrosion: stainless steel tank, glass steel, steel lined with plastic material, to avoid resin contamination.Wide applicability: for industrial boilers, heat exchangers, air conditioning, laundry, bathing facilities and food, pharmaceutical, electronics and other industries.7, the maintenance of sodium ion exchange: ion exchanger is used to reduce the hardness of the water, raw water from the top down through the switch to soften the water contains magnesium, calcium, cation exchange resin with water, sodium ion exchange; raw water to be softened a littlecalcium, magnesium and salt water (known as soft water), so that the water is not easy to form carbonate and sulfate scale scale, can be used for boiler feed water and some industrial uses.Because sodium is very soluble in water.Will not form a hard scale in the boiler house, and easy to exclude, enter the sodium ion exchange water, shall be subject to clarification and filtration treatment, generally does not contain suspended solids.After softening by the switch, the residual hardness of not more than 0.03 mg / liter.Before emptying into the salt can not, so there will be air-resin, regeneration is not complete, not only will not increase water production good, but also may reduce the water yield and quality of water production. ion exchanger in the salt water is called regeneration, is cation exchange column for the purposes.High concentration of sodium ions to replace the branch of heavy metal ions.After half an hour rinse out the excess salt is to maintain the resin in a renewable good working condition.8, scale scale that is water base, that is, the state of water changes (especially when heated), dissolved calcium (Ca2 +) and magnesium ions (Mg2 +), and some of the radical ion formation of insoluble incompound or mixture of water, the main ingredient is calcium carbonate.Poor thermal conductivity of the scale, only metal 1 / 200.Scale tend to form crystalline, hard, once formed, it is difficult to remove. How does the formation of scale?Scale formation is a complex physical and chemical processes of reasons both internal and external.First, the water has calcium and magnesium ions and other heavy metal ions, is the root cause of the formation of scale is also called internal; the second is from the supersaturated solid matter precipitated in boiler water and adhere to the metal heating surface is the formation of the external scale.When containing calcium and magnesium salts into the boiler water impurities, the absorption of high temperature flue gas heat to pass, calcium, magnesium impurities will be a chemical reaction to produce precipitation of insoluble material.With the continuous evaporation of water heaters gradually concentrated, when a certain concentration, precipitation will become a solid precipitated, attached to the drum, water wall tubes on the heating surface of the wall, forming a layer of film, impede heat transferThis layer of film called the scale.As used in daily life, tap water, are a large number of dissolved calcium (Ca2 +) and magnesium ions (Mg2 +), Beijing is often called hard water, is the truth.Such water in the heating, the calcium carbonate and magnesium ions (calcium carbonate and magnesium carbonate) solubility in water significantly reduced, most of which insoluble (calcium carbonate and magnesium carbonate) which would precipitate from the waterthe formation of precipitation, and then form a scale. What is the scale of the damage?Scale is a poor thermal conductivity of the material, only one-tenth of the boiler to the number of steel per cent (the thermal conductivity of steel is 46.5 58.2w/m.k), is the source of detrimental.In a variety of scale, the most hard silicate scale, thermal conductivity is very small, easily attached to the boiler heating surface evaporation surface of the strongest, is the most harmful kind of scale.Heating boilers, water heaters and hot water systems: Poor thermal conductivity of the scale, the waste of energy (natural gas or electricity), the financial burden of the family; Lead to overheating of heat exchanger to reduce the service life, and even accidents; Scale can clog water pipes, causing poor water flow, or even forced to replace water pipes, causing damage to the decoration and other consequences.9, the scale of the boiler safety, economic operation of the hazard reduce the thermal efficiency, waste a lot of fuel.Boiler Health scale, the heating surface deterioration of the heat transfer performance, fuel combustion heat released can not be quickly passed to the boiler water, so a lot of heat was taken away by smoke, resulting in increased exhaust gas temperature, increased heat lossesthe boiler thermal efficiency.In this case, in order to keep the boiler ratings, to be adding more fuel to the furnace and to increase the blast and the wind to strengthen combustion.The result is a large number of incomplete combustion of substances from the chimney, potentially increasing the fuel consumption.As we all know, the boiler furnace volume and grate area is certain, no matter how much adding fuel, fuel combustion is limited, so it is impossible for the thermal efficiency of the boiler increase.The more students boiler scale Results thick, the lower the thermal efficiency, fuel consumption will be.Experimental data show that when the end of Health 1.5 mm scale, we should consume 6% of the fuel; to 5 mm, the fuel consumption will reach 15%; to 8 mm, the fuel consumption increased to 34%.To more than 40 million units of the current boiler, if the only part of the Boiler different levels of scale, then wasted fuel is also very striking. cause metal overheat, lower intensity, affect safety.Use of steel boiler heating surface, generally are carbon steel, in use, allowing the metal wall temperature below 450 .In the normal operation of the boiler, the metal wall temperature generally at 280 or less.Paradise when the boiler heating surface, the metal heat transfer the heat quickly after the water supply, then the temperature difference between the two is about 30 .However, if the heating surface junction of Health scale, the situation is not much different.For example, when the working pressure of the boiler heating surface 1.25Mpa Results scale of 1 mm thick (the mixture of scale), metal wall and the boiler water temperature will reach about 200 .That the metal wall temperature at this time to allow the temperature within the steel.But when the scale is 3 mm, the metal wall temperature rises to 580 , far more than the allowable temperature of steel.Thus, when the tensile strength of steel will fall from the 3.92Mpa to 0.98Mpa, boiler pressure parts will overheat under internal pressure drum blisters, deformation, leakage, or explosion.In addition, the metal wall temperature increases will stretch the metal, such as 1-meter-long tube, is increased by 100 , elongation of 1.2 mm, the margin expansion for the heating surface does not, it will cause the furnacecracking.Measured data show that the metal wall temperature is increased with the increase in scale thickness, the thicker the scale, the higher the metal wall temperature, and thus the greater the probability of the accident. destruction of the water cycle.Boiler water cycle of natural water cycle and forced water circulation in two forms.The former is decreased by the increase in tube and pipe the proportion of different soft drinks produced by the pressure difference and the water cycle.The latter mainly depends on the role of mechanical power pump forced circulation.No matter what kind of circular form, is calculated by design, that is sufficient to ensure the flow of cross-sectional area.When the furnace wall Results of Health scale, it will make the cross-sectional area reduction tube flow, flow resistance increases, damage to the normal water cycle, making the surface of the metal attached to thermal wall temperature rise.Pipeline security is blocked when the scale, the water cycle is completely stopped, the metal wall temperature is higher, long-term effect on the over-burning occurs easily due to tube rupture.Water wall tube is even arranged in the furnace, the absorption of the radiant heat.400 mm away from the header surface temperature of about Xianghuo area, if the junction of Health scale, the drum on the most vulnerable to blisters, leaks, bending and blasting accidents. increase the amount of maintenance, waste a lot of money.Once the boiler fouling, it must be removed, so as to ensure safe and economic operation boiler.Therefore, the scale must be removed by chemical agents, such as acid and alkali.The more thick knot of Health scale, the more consumption of Pharmacy, the more money invested.For example, 1T / H boiler if the average scale of 3 mm, in addition to a pharmacy would need 0.5 tons of dirt, plus labor costs to be about 2,500 yuan of funds.In accordance with the tonnage of the different boiler, tonnage increased to increase the required one-third of Pharmacy, funds also increased.Within the general scaling drum to eliminate a little easy, but if the tube scale, elimination is quite difficult.Moreover, the event of tube rupture and put a new pipe, the welding is very convenient.Drum drum blister Wabu, require high for a long time, the construction more difficult.A big drum scarf patch repair blisters, we should spend about 1 to 20,000 yuan of funds.In short, both the chemical cleaning or repair of the purchase of materials, must spend a lot of manpower, material and financial resources. reduce boiler life.General boiler service life under normal use conditions, be able to run for 20 consecutive years.But why are most of the boiler using the unit does not achieve this life?The reasons are manifold, one of which there are scale effects.Drum drum blister occurs, Wabu restored, blood pressure should be on its proper use to ensure safety.As a result, a higher vapor pressure for the required units for the new boiler had to be replaced.Some units will also be affected by steam pressure is too low quality or even defective, a direct impact on economic efficiency.Some of the boiler drum blister area is too large for deformed and had to be discarded; some boiler though can be repaired, but repair costs are too high, no value, had to be scrapped.When inappropriate or acid pickling methods frequently also affect the life of the boiler.In addition, because the scale contains halogen ions, at a high temperature corrosive effect of iron will lead to brittle metal wall and metal wall to keep the depths of development, resulting in metal corrosion, reduce boiler life.10, scale preventionTo ensure the boiler does not scale or thin scale operation, we must strengthen the boiler feed water treatment, which is to ensure safe and economic operation of the boiler an important part.Prevent scale formation, usually used the following methods to prevent: pot outside the water.This method is applicable to all kinds of boilers.Effects of current and reliable water pot outside the lime + soda ash softening, the water is to have clarified by adding the right amount of lime and soda ash to soften the purpose.Lime - soda ash softening of cold and hot French.Cooling method is carried out at room temperature, so that the residual water hardness equivalent to 1.5 to 2 mg / liter.Thermal water is heated to 20 80 , so the water residual hardness equivalent to 0.3 to 0.4 mg / liter.Therefore, the thermal method should be used to enhance the softening effect.Ion exchange softening mainly by sodium ion exchange resin in exchange softening.Exchange resin as strong, can free in the water of calcium and magnesium ion adsorption, so that the boiler feed water hardness reached the required standard.Ion-exchange agent has two types of inorganic and organic.Only the surface of inorganic exchange resin, softening effect is bad, use less.And organic exchange resin core structure is characterized by loose particles, the particle surface and the exchange reaction can be within the same time, softening effect, so use more. pot treatment.This method is mainly water, add chemicals to the furnace, and boiler water to form scale of calcium and magnesium to form loose sediment, and then use the method to sediment discharge of sewage released, but serve to prevent (or reduce) the effect of boiler fouling.Add syrup processing furnace generally used for small low-pressure boilers.Pot drugs commonly used water treatment are: trisodium phosphate, sodium carbonate (soda ash), sodium hydroxide (caustic soda, also known as caustic soda) and organic colloids (tannin) and so on.Dosing should be first made into all kinds of drugs solution, and then join the boiler.Trisodium phosphate solution concentration is usually 5 to 8%, sodium carbonate concentration less than 5%, the concentration of sodium hydroxide is less than 1 2%.Dosing method has both a regular and continuous dosing.Dosing depends mainly on a regular basis to add additional bottles of medicine, medicine; continuous dosing device in the w