industrial boiler water quality

- Nov 20, 2019-

I. Common problems in industrial boiler water quality and analysis of the impact on boilers

        1. The effect of colloidal impurities on the boiler

        The use of surface water directly as boiler water, a large amount of colloidal impurities contained in surface water will have many adverse effects on the boiler. If there is more colloid in the water in the boiler feed water, in the process of generating steam, the unstable heat of the colloid will generate a large amount of foam attached to the evaporation surface, which directly pollutes the steam, which causes the steam quality to decline, which in turn affects the energy efficiency of the boiler operation. At the same time, the attachment of the colloidal foam will cause deviations in the display of the boiler water level gauge, affecting the normal operation of the boiler. During the operation of the boiler, the colloid in the water will enter the boiler or the ion exchanger. For some thermally unstable colloidal materials, if it adheres to the heating surface of the boiler, it may form scale that is difficult to remove. Some colloidal substances entering the ion exchanger will be attached to the resin on the surface, which in turn affects the exchange capacity of the resin on the surface of the ion exchanger, greatly reducing the working cycle of the resin and affecting the quality of the effluent.

        2. Effect of dissolved impurities on the boiler

        Natural water contains a large amount of dissolved impurities, such as calcium ions, magnesium ions, acid ions, etc. These dissolved impurities will react during the use of the boiler, affecting the operation of the boiler. For example, calcium and magnesium ions increase the hardness of the water, and it is easy to react with the boiler surface during the operation of the boiler to promote boiler fouling. The effect of acid ions on the boiler is also extremely significant. For example, the content of bicarbonate ions and carbonate ions will directly affect the alkalinity of the water. The alkalinity substance can react with calcium and magnesium ions to form slag, which is removed by sewage discharge and plays a certain anti-scaling effect. Therefore, the low-pressure boiler requires a certain alkalinity in the pot water. However, the alkalinity of the pot water is too high, and the phenomenon of steam and water rushing is easy to cause the steam quality to decrease, and the boiler with high pressure is also likely to cause alkaline corrosion. Therefore, for natural water with a high content of bicarbonate, as a boiler feed water, it is necessary to reduce the alkali.

        Second, the significance of industrial boiler water quality testing

        Industrial boilers are one of the main equipments in the modern industrial field. Because of their special requirements in application, such as the high temperature and high pressure, the operation has a greater threat, so the relevant departments of China for industrial boilers Use and testing to set clear requirements to ensure that industrial boilers meet industrial production efficiency while reducing the likelihood of safety incidents. It can be seen that the development of boiler testing is extremely important. In the actual testing, the key link lies in the water quality testing. It is required to find problems in the industrial boiler during the inspection, and effectively deal with the scaling problems that may occur on the heating surface to ensure that the boiler heat transfer efficiency and overall working efficiency will not be affected. Related studies have pointed out that in the case of 1mm scale on the heated surface, the fuel consumption will increase by 8%, and the boiler operating efficiency will decrease by 5%. And in the trend of scaling problems, water-cooled wall tube explosion, corrosion and other issues may occur. Therefore, doing a good job in water quality testing is the key to controlling the scaling problem and is the main process to improve the overall efficiency of boiler operation.

 

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        Third, industrial boiler water quality treatment methods

        1. Method for controlling the pH of the pot water

        The control of the pH of the pot water is firstly the choice of the water source for the industrial boiler. It is generally recommended that the industrial enterprise choose tap water. If the water source has less selectivity, it is generally controlled by adding a chemical. However, before the reference, it is necessary to test the water supply source and understand the relevant characteristics of the water source to formulate corresponding control measures. In order to prevent corrosion of the water supply system, the national standard requires that the pH of the feed water should be controlled within the range of 7.0 to 10.0. In the process of dosing, it is necessary to pay attention to the following points: the empty pot of water or the supplement is based on the total volume of the pot water. The running dosing is based on the daily replenishment or the amount of water per hour; The dosage of the respective manufacturer's pharmaceutical formula should be combined with the water quality calculation and adjusted according to the pot water test results to the normal dosage; the dosing interval is usually once per shift or once a day. The pH of the pot water should be controlled between 10.0 and 12.0.

        2. Control method of hardness material in raw water

        The boiler user should conduct detailed inspection of the raw water quality. In actual operation, the boiler water quality should be monitored, and the water treatment method should be adjusted in time according to the fouling situation found in the boiler internal inspection. If the original boiler water does not use a sodium ion exchanger, the fouling of the boiler after adjusting the medicament still does not reach the expected level, and the raw water should be softened. The original boiler water is already softened water. The water quality of the sodium ion exchanger should be regularly monitored to prevent the resin from failing and the boiler feed water hardness is high. For the raw water is negative hardness water, the raw water should be combined with the quality of the boiler water and steam to reduce the alkalinity of the raw water, resulting in a large amount of waste heat.

        Fourth, strategies to improve the effectiveness of boiler water quality testing

        For boiler water quality testing, it is required to take corresponding measures. Taking the boiler scaling problem as an example, it is an important factor affecting the heat transfer efficiency of the boiler. It is required to continuously strengthen the inspection and supervision during the treatment process to ensure that the water quality testing in the boiler operation is in place, and propose a scheme to optimize the boiler operation in combination with the detected parameters, so that the scaling problem can be controlled from the source. Taking the boiler corrosion problem as an example, the cause is related to the boiler water quality, pressure, temperature and related corrosive media. For this problem, it is necessary to pay attention to the stage of shutdown protection, combined with specific operating procedures, to clarify the relevant indicators of corrosion detection, and to control the factors that may cause corrosion problems. At the same time, for the problem of water treatment equipment, it is required to do a good quality inspection before use to determine whether it is consistent with the boiler operation requirements. In addition, the intensity of water quality testing should also be increased, mainly to improve the overall quality of personnel, and to do a good job of technical disclosure before the operation, to achieve timely detection and timely processing, so as to improve the efficiency of boiler operation.

        Conclusion

        Boiler water quality testing is the main work in industrial boiler testing. In the actual inspection work, the importance of water quality testing should be correctly recognized, based on the problems existing in the current testing work such as water scaling, water treatment equipment, furnace maintenance and corrosion problems, etc., based on this, adopt corresponding solutions. In this way, the water quality testing target can be realized, and the operation level of the industrial boiler can be further improved.