【 Weak current College 】 heating ventilating and air conditioning cooling water treatment status, problems and solutions

1, heating and air conditioning cooling water treatment status

1.1 hot water heating system, air conditioning (cooling) cold water or hot water (hereinafter referred to as hot and cold water system) of water treatment, previously used sodium ion exchanger for tap water (or deep water) softening treatment methods, now also has adopted this method. Refrigeration (or air pressure, air separation) cooling water (hereinafter referred to as the cooling water system), have not taken any water treatment methods, and today still has not done any treatment of water.

1.2 hot and cold water system uses the sodium ion exchanger for tap water (or deep water) softening treatment and cooling water systems use electronic water treatment, magnetic water etc physical methods of water treatment.

1.3 hot and cold water system although equipped with a dosing tank, but does not insist on the use in the operation of the cooling water system in the use of electronic water treatment, magnetic water etc physical methods of water treatment.

1.4 hot and cold water and cooling water system uses electronic water treatment, magnetic water etc physical methods of water treatment.

1.5 hot and cold water system with manual or automatic dosing device on the system for dosing of chemical water treatment and water cooling system using electronic water treatment, magnetic water etc physical methods of water treatment.

1.6 hot and cold water system and two sets of water cooling system, the system uses manual or automatic dosing equipment for chemical water treatment system.

2, heating and air conditioning cooling water circulation system features

2.1 hot and cold water system normally closed loop water system, but there are open-water circulating system (such as the cotton mills of the spray-type air treatment room and other components of the system, etc.). Its running, debugging before the first water filling and running supplementary watertap water for the city in General (but also useful for deep water). The duration of the supplementary volume, open-water circulating system is a closed loop water system to a much larger, and on the water quality requirements are also quite high. If the water content of bacteria, water is toxic, water conforms to national health standards, etc.

2.2 hot and cold water system, the temperature of the circulating water in summer 7-12 ° c; 65-50 degrees centigrade in winter and central air conditioner terminal equipment water temperature in winter is generally more at 60 ° c and below.

2.3 except steam boiler outside the system, hot water heating system circulating water temperatures more than 100 ℃ below, but also have hot water heating systems, such as 70 ℃, 110-130-70 ° c, 150-90 ℃, etc.

2.4 closed loop water system of water from the surrounding environment, and there is no concentration of water in various ion, concentration remains unchanged; and open-loop water system water is influenced by the surrounding environment effects, such as the workshop production equipment distributed by dust, new trend collection and processing of dirt can cause pollution of the water circulating.

2.5 coolers and air conditioners or spray spraying of conditioner (e) of the tank is very easy to breed in large numbers of bacteria, there is a large water tank bottom mud, poor health conditions. Has attracted attention of colleagues.

2.6 cooling water system is generally open-loop water system, but also has a closed loop water system. Its first water filling and supplementary water during operation also City tap water or deep water. Cooling water temperature is 37 ° c 32-, or lower than the temperature. Cooling water environment, such as dust (air suspensions), bacteria, oxygen, sulphur dioxide, nitrogen oxides, acid rain, etc. These substances once inside the cooling water system, you will seriously polluted cooling water, and because of the evaporativecooling water continuously, water Ca2 +, Mg2 +, Cl-, SO42-and dissolved solids, total suspended matter concentration increases, the cooling water system of the equipment and pipeline of corrosion, dirt and bacteria and algae in propagation, serious will produce clay and blocked pipeline or equipment.

3, heating and air conditioning cooling water circulation system of basic problem

Closed cycle cooling water system of the main problems is the corrosion, and open cooling water system of the main problems is the scaling and corrosion.

3.1 closed loop water system of the main problems is the prevailing corrosion phenomena, not what people think of scaling. As Tianjin Hexi District a road reconstruction in the cross-road of down overhead heating pipe, pipe inner wall and no scaling but rather the whole surface corrosion and corrosion phenomena associated with a little; recently in Tianjin University in demolition, when heating pipes are also the corrosion problems, through research, that their system does not use chemicals for water treatment. So closed loop water system, in engineering design, you should first consider how to prevent corrosion, at the same time, of course have to consider how to prevent system scaling issues. In view of the above problems you should change the ideas and concepts, how to prevent corrosion of the system in the first place, the second is to prevent fouling. The reason is: HVAC and refrigeration and air conditioning of closed loop water system water temperature circulating water, low, and the device heat transfer surface temperature are low; hence not like steam boilers of boiler water, makes water ions concentration in various phenomena. Coupled with HVAC and refrigeration and air conditioning water recycling system for supplementary water although relatively small, but with a certain amount of dissolved oxygen, and salinity, and corrosion problems has become a priority issue.

3.2 cooling water system is one ofthe most disadvantaged of the system, should do well in water treatment. We have on an organization's cooling tower for cleaning work found that the cooling water system is equipped with a desk 500T/h of cross flow cooling tower, and is equipped with multiple electronic water treatment. After a summer of runs, cooling tower packing a lot of carbonate on the scale, the thickness of about 20-50 μ m; and out of the water pipe inner wall had a significant scale. Will clean out the scale and scale your pack up foot six small sacks. If you do not timely cleaning, the scale, iron oxide belt into the device, it is easy to plug the condenser, caused the accident. Later the units accept the suggested, miningAuto chemicalized equipment, chemical water treatment system, with scaling problem has been resolved.

4, heating and air conditioning cooling water treatment in the design specification

4.1 should strictly implement water treatment of three technical regulations

State technical supervision Bureau published 2001 Edition People's Republic of China national standard "industrial boiler water quality" (GB1576-2001), the 1995 edition of the national standard "industrial People's Republic of China circulating cooling water treatment design specifications" (GB50050-95) and "industrial circulating water cooling design standard" (GB/T50102-2003), is the industry water treatment of technical regulations, should be carefully implemented.

The new standard for relaxed 4.2 water hardness indicators

New standard "industrial boiler water quality" (GB1576-2001), hot water boiler feed water treatment with chemical water treatment relaxes the hardness of the water supply. The original standard GB1576-1991 provides water hardness ≤ 4mmol/L, the new standard in 2001 GB1576-water hardness ≤ 6mmol/L-while most of the water hardness is around 6mmol/L (Tianjin Luan water hardness about 3.4mmol/L, pH = 7, dissolved oxygen 10mg/L). This water as a carrier of heating, air conditioning, cooling water circulation system, to use chemical water treatment method has very favorable conditions. In other words, most of China's hot water heating system, air conditioning, hot and cold water system can use chemical treatments of water. Because this can reduce the hardness of the water as the primary purpose of sodium ion exchange method, which creates a significant amount of each year, hundreds of tons of waste salt contamination of groundwater.

5 air conditioning and refrigeration, HVAC and water treatment design

Collect water quality data 5.1

Design for water treatment, you should first collection system water quality information, such as hardness, pH, dissolved oxygen, chlorine ions, dissolved solids (or salt content), suspended solids, etc. In order to provide engineering design to address the water circulation system prevalence of corrosion or scaling phenomena provide the underlying data.

5.2 understanding system equipment and materials, material

Should identify or understanding system equipment, piping, valves, pumps, and other materials used to meet the design requirements on water quality and water treatment, and prevention of corrosion and fouling system.

5.3 hot and cold water system water treatment process

Hot water heating system, air conditioning, hot and cold water system water treatment programme, first use of advanced technology and proven method of water treatment automatic dosing device on the system of automatic dosing of chemical water treatment methods. Single use sodium ion exchanger production of demineralized water only prevent system scaling, not corrosion prevention system, air-conditioning, hot water corrosive than tap water. This is because the tap water contains calcium carbonate, natural, it is a cathode resistance of corrosion inhibitors. When water softening, while increasing the pH of the water, but as hardness constituents of removal, the water's originalnatural inhibitor calcium carbonate-has also been removed; coupled with the sodium ion exchanger for softening water salinity than raw water has increased, its calculation formula is:

ΔG=2.95HCa+10.84HMg

G-Δ-softened water salinity increase, mg/L; HCa-raw water hardness Ca, mmol/L; HMg-raw water hardness Mg, mmol/L.

Therefore, single use sodium ion exchanger manufacture of softened water, dosing chemicals to prevent the system from corrosion. This approach will make the sodium ion exchanger produces large amounts of recycled waste and contaminated groundwater saline solution, and will make the device a total investment of more than a chemical compound of pharmaceutical methods of water treatment equipment. Moreover, the use and circulation of cold and hot water system that corresponds to the characteristics of chemicals for water treatment, its running cost is lower. It is also a pollution-free, green environmental protection product should be vigorously promoted.

To physical methods of water treatment, such as a magnetic water, electronic water treatment device, to a certain quality of a scale effect, but does not have the effect of preventing corrosion, thus making the system experienced a severe corrosion. A commercial installation 2 Hitachi brand screw chillers, and run a few years after the discovery of serious corrosion of the equipment and pipeline, the physical water treatment facilities. In early 2002, the original of the "electronic water treatment" and all the corroded pipe complete demolition, removal process discovery pipeline has a large number of rust and iron oxide. So screw chillers also made chemical cleaning. After the switch to the "chemical methods of water treatment programme", the use of automatic dosing equipment, air-conditioning and hot water systems and cooling water systems, implementation of the chemical water treatment, for the second year running to receive good results.

5.4 cooling water system watertreatment process

To prevent cooling (or air pressure, air separation) water systems, environmental impact, so that the cooling water mixed with a lot of dust, bacteria, oxygen, sulphur dioxide, nitrogen oxides, acid rain, pollution, and because of the evaporative cooling water continuously, the original water Ca2 + in, Mg2 +, Cl-, SO42-and dissolved solids, total suspended matter concentration continues to increase, resulting in the cooling water system of corrosion, dirt and bacteria and algae reproduction that produce clay and blocked pipeline or equipment. It is designed to be the preferred method of "chemicals" water treatment programme. From currently available technology, adopt and cooling water system features correspond to conduct water treatment chemicals, more than any other method is more effective, in line with existing State Bureau of technical supervision and construction Ministry published national standards. The method from the GB (GB50050-95) — "industrial cooling water treatment design specifications" and "industrial circulating water cooling design standard" (GB/T50102-2003), better than any other.

5.5 should strictly control system and sufficient water for the first time and run time for water quality

If the first filled with water or tonic water does not comply with the requirements, system equipment, pipeline causing corrosion. Even stainless steel equipment (e.g., SUS304, SUS316, material), such as the Cl-ions concentration is too large, it will give rise to corrosion even causing perforation equipment.

6, HVAC and refrigeration and air conditioning water treatment technology prospect

6.1 break tradition, the use of new technologies for water treatment, everyone from a Green perspective in the design, construction, management, quality homes.

6.2 calls for the relevant departments to develop policies and regulations, development, production more affordable green chemical water treatment chemicals, toadapt the protection of the environment. No phosphorus (p), non-toxic green chemical water treatment chemicals, in hot water heating system, air conditioning, hot and cold water and cooling water systems using proven, has on the environment, pollution-free, non-destructive of good results, its running cost and containing organic phosphonic acid salt scale, corrosion inhibition reagents. Of particular note is the operation of the sewage will not cause environmental pollution.

6.3 water treatment automatic dosing device is achievable on the circulating water system automatically or timing of dosing, to reduce the labor intensity of workers. The device according to the number of water supply, Proportioning of automatic dosing or timing of dosing, according to the water's pH and water supply on-line control of quantitative dosing. We want to continue to develop advanced technology, easy operation, price/performance advantages of automatic water treatment dosing equipment, to promote the HVAC and refrigeration and air conditioning industry for the development of chemical water treatment.