(1) Acid cleaning agent for chemical cleaning of boiler

柠檬酸酸洗是在锅炉大型化，盐酸酸洗引起奥氏体(不锈)钢应力腐蚀破裂的情况下发展起来的二种酸洗剂。由于柠檬酸不含氯离子，不会引起奥氏体的应力腐蚀破裂。所以适用于结构复杂和系统很复杂的高参数、大容量锅炉，特别适用于奥氏体钢和蛇形管的清洗。清洗时，清洗液浓度一般应控制在3％～4％之间，温度为90～98％，pH值在3．5～4．0之间，清洗流速为O．3～2．Om／s，清洗时问控制在3～5h。柠檬酸清洗存在的问题为柠檬酸废液处理较复杂，它无溶解硅酸盐垢的能力，机组启动时还应有洗硅措施，药品昂贵，操作不当时还会产生柠檬酸铁沉淀.使用柠檬酸做        清洗剂时应注意：

Citric acid pickling is a kind of pickling agent developed under the condition that the boiler is large-scale and hydrochloric acid pickling causes stress corrosion cracking of austenitic (stainless) steel. Because citric acid does not contain chloride ions, it will not cause stress corrosion cracking of austenite. Therefore, it is applicable to high-parameter and large-capacity boilers with complex structures and systems, especially to the cleaning of austenitic steel and coils. During cleaning, the concentration of cleaning solution should be controlled between 3% and 4%, the temperature should be 90~98%, the pH value should be 3.5~4.0, the cleaning flow rate should be 0.3~2. Om/s, and the cleaning time should be controlled between 3~5h. The problem of citric acid cleaning is that the treatment of citric acid waste liquor is complex, and it has no ability to dissolve silicate scale. When the unit is started, silicon cleaning measures should also be taken. Drugs are expensive, and iron citrate precipitation will occur when the operation is improper. When using citric acid as cleaning agent, attention should be paid to:

①在专用的溶液箱中将缓蚀剂搅拌溶解,用除盐水溶解柠檬酸,并加氨水调整清洗液pH为3.5～4.0.用蒸汽将配制好的清洗液加热90℃以上。

① Stir and dissolve the corrosion inhibitor in a special solution tank, dissolve the citric acid with demineralized water, and add ammonia to adjust the pH of the cleaning solution to 3.5~4.0. Heat the prepared cleaning solution to above 90 ℃ with steam.

②确认清洗系统无漏泄时，用清洗泵将柠檬酸送被清洗的锅炉中。

② When confirming that there is no leakage in the cleaning system, use the cleaning pump to send the citric acid to the cleaned boiler.

③在清洗过程中，每30min采样化验一次清洗液中柠檬酸浓度、Fe2+浓度及pH值。在整个清洗过程中应保持清洗液pH始终在3．5～4．0之间(用氨水调节)。

③ During the cleaning process, the citric acid concentration, Fe2+concentration and pH value in the cleaning solution shall be sampled and tested every 30min. During the whole cleaning process, the pH of the cleaning solution should be kept between 3.5 and 4.0 (adjusted with ammonia water).

④当酸洗既定时间后或清洗液中Fe2+含量基本稳定后，结束酸洗。 ⑤酸洗结束后，用热的除盐水(90℃以上)排挤柠檬酸液并进行冲洗。为提高冲洗效果，尽量提高冲洗流速，直到排出水pH为5～6，含铁量小于20～30mg／L时为止。

④ When the pickling reaches the set time or the content of Fe2+in the cleaning solution is basically stable, the pickling is finished. ⑤ After pickling, use hot demineralized water (above 90 ℃) to squeeze out the citric acid solution and wash it. To improve the flushing effect, try to increase the flushing flow rate until the pH of the discharged water is 5~6 and the iron content is less than 20~30mg/L.

(2)锅炉化学清洗漂洗剂

(2) Chemical cleaning and rinsing agent for boiler

当用盐酸或柠檬酸作酸洗剂时，在酸洗结束并用除盐水(或软化水)冲洗后，一般要再用稀柠檬酸溶液进行一次冲洗，通常称为漂洗，是利用柠檬酸有络合铁离子的能力，除去酸洗和水冲洗后残留在清洗系统内的铁离子，以及水冲洗时可能在金属表面产生的铁锈。采用0.2％～0.4％的稀柠檬酸溶液(含有0．05％的缓蚀剂)，pH值为3．5～4．0，温度60～90℃，时间2～3h。在漂洗中应注意以下问题：

When hydrochloric acid or citric acid is used as pickling agent, after pickling and rinsing with demineralized water (or softened water), dilute citric acid solution is generally used for rinsing, which is usually called rinsing. It is to use the ability of citric acid to complexe iron ions to remove the iron ions left in the cleaning system after pickling and water washing, as well as the rust that may occur on the metal surface during water washing. Use 0.2%~0.4% dilute citric acid solution (containing 0.05% corrosion inhibitor), pH value 3.5~4.0, temperature 60~90 ℃, time 2~3h. Pay attention to the following problems during rinsing:

①漂洗液应用除盐水(或软化水)配制。

① The rinse solution shall be prepared with demineralized water (or softened water).

②配制方法采用边循环边加药的方法进行，即先用清洗泵使漂洗水在清洗系统中进行循环，并在循环的同时将水加热60～90℃，然后连续地向漂洗水中加入已事先配制好的浓药品，加药顺序为漂洗剂、缓蚀剂，并用氨水调解pH为3．5～4．0。

② The preparation method adopts the method of adding chemicals while circulating, that is, first use the washing pump to circulate the rinsing water in the washing system, and then heat the water to 60~90 ℃ while circulating, and then continuously add the prepared concentrated drugs to the rinsing water. The dosing sequence is bleaching agent, corrosion inhibitor, and adjust the pH to 3.5~4.0 with ammonia.

③在漂洗过程中应经常测定漂洗液温度及pH值。

③ In the process of rinsing, the temperature and pH value of rinsing solution should be measured frequently.

④漂洗结束后，用除盐水(或软化水)冲洗干净系统后转入下道工序。

④ After rinsing, rinse the system with demineralized water (or softened water) and then proceed to the next process.