Experimental Study On Scaling Law Of Mine Water In Circulating Cooling System And Selection Of Scale Inhibitor

China is the most populous country and the largest developing country in the world.Water resources are the basic natural resources.According to data,there are about 400 water-deficient cities in china,and about 110 severely water-deficient cities.Water resources shortage and surface water pollution It is a serious problem that china is currently facing.Among them,the reuse rate of industrial water in china is only 45%,and the water consumption is much higher than that of countries with relatively developed industries.Therefore,how to reduce industrial water consumption is of great significance for saving water resources.Theoretically,the circulating cooling water system of coal-fired power plants is the system with the largest water consumption in thermal power plants,generally accounting for 60%to 75%of industrial water consumption.In addition to the usual use of air-cooled systems to reduce water consumption,it is an effective way to save water in thermal power systems by reusing mine water for circulating chilled water systems in power plants.However,the quality of mine water is complex and has significant characteristics of the coal industry,in which the content of total dissolved solids,especially calcium and magnesium ions that are easy to scale,is high.During the operation of the circulating cooling water system,the calcium ions and carbonate ions in it are easy to form calcium carbonate when heated,and deposit on the surface of the heat exchanger,which will significantly reduce the heat exchange efficiency,increase the operating cost,and even cause calcium carbonate.security incident.Therefore,this paper discusses the scaling law of mine water in the circulating cooling system by simulating the scaling experiments of mine water under different influence conditions in the circulating cooling water system,which can provide a basis for further research on scaling prevention.At the same time,based on the water quality of common mine water,the scale inhibition efficiency of common scale inhibitors in the market was analyzed,and the best scale inhibitor suitable for mine water reuse in circulating cooling water system was screened out,and the scale inhibitor was optimized for thermal power plants.The best dosing conditions in the environment.The main conclusions of the paper are as follows:（1）Ca²⁺,Mg²⁺,HCO₃^-,SO₄^2-ions are the main scaling ions in mine water.The main scaling products are calcium carbonate and calcium sulfate,and there are less magnesium carbonate and magnesium sulfate scaling.Among them,the main factors affecting scaling are temperature,contact time,p H and so on.With the increase of Ca²⁺,Mg²⁺,HCO₃^-,SO₄^2-ion mass concentration,temperature,p H,and contact time,the fouling amount also increases.（2）The increase of SO₄^2-concentration will lead to an increase in the amount of hard scale in mine water scaling substances,mainly calcium sulfate.SO₄^2-content is the main factor for the formation of hard scale,and the removal of hard scale has a significant impact on the efficiency of mine water reuse.Therefore,when the mine water is used for the treatment of circulating cooling water,not only the use of calcium and magnesium type scale inhibitors,but also the addition of sulfuric acid type scale inhibitors should be considered.（3）In the experiment,when the calcium ion mass concentration is 300 mg/L,the magnesium ion mass concentration is 240 mg/L,the sulfate mass concentration is 1000 mg/L,the bicarbonate mass concentration is 1000 mg/L,p H=8,and the temperature is 80°C,Scale inhibitor sodium polyacrylate（PAAS）,hydroxyethylidene diphosphonic acid（HEDP）,ethylenediaminetetramethylene phosphate（EDTMPS）have good scale inhibition efficiency for mine water in daily dosage,all reached more than 80%.Among them,EDTMPS has the best scale inhibition efficiency.When the dosage is 6mg/L,the scale inhibition efficiency reaches91.91%.The main reason is that EDTMPS has better removal efficiency for calcium carbonate,and its scale inhibition effect on calcium sulfate is also very good.Well,the side shows that the removal of hard scale in mine water has a significant impact on the scale inhibition work of the entire mine water reuse.（4）When the scale inhibitor EDTMPS was applied to the experiment,when the ion mass concentration of the solution remained unchanged,the theoretical scale inhibition efficiency reached the highest when the temperature was 70.408°C,the contact time was 6.136h,and the dosage was 5.981mg/L,which was 96.713%.Among them,the dosage of the scale inhibitor EDTMPS has the most significant effect on the scale inhibition effect.Due to the strong stability and adaptability of EDTMPS,the influence of solution temperature and contact time on the scale inhibition effect is mainly due to their influence on the scale of the solution system itself.Under the conditions of the above solution temperature and contact time,the amount of scaling in the water sample itself is relatively low,so under the condition of adding enough scale inhibitor,the scale inhibition effect can be guaranteed to the greatest extent.