Maintenance of a boiler

Maintenance of a boiler consists of these operations: its putting into operation and stopping, operation control and regulation, selection of the optimum operation repair, maintenance checkup of the damages and so on. Requirements for these operations are given in the above mentioned regulations. Additional requirements for the steam boilers of the power stations are pointed out in the corresponding regulations. Concrete directions which service staff must strictly execute are drawn up on the basis of these requirements taking into consideration existing local conditions.

Regulation of the boiler operation, putting into operation and stopping are especially significant operations. Procedure of their fulfilment is indicated in the special directions.

The state of the boiler itself and auxiliary equipment are controlled before putting it into operation. Having engaged a suction fan, smoke ducts must be ventilated well, so that gas accumulated inside would not explode. A boiler is filled with warm water to its lowest level in the drum. A boiler is heated gradually due to get even warming of all its elements.

During the heating of the boiler a superheater and an economizer are cooled. A superheater is chilled by the steam, blown through it, an economizer – by water provided by recirculation pipe installed between the boiler drum and the supply header of the economizer.

Staff on duty is watching the state of the operating boiler and exactly keep the established conditions of the running boiler.

Stopping the boiler for a longer time should be protected from the internal corrosion, e.g. measures are to be taken, that oxygen should not get into it. The method of excess pressure is rather good when the whole boiler is filled with deaerated water and attached to the feeding watermain, maintaining the pressure in the boiler system. A certain amount of hydrazin, reacting with the remainders of the water, is mixed into it. A boiler is filled with deaerated and more alkaline water, if alkaline method of preservation is used. Oxide film formed on the steel surface protects metal from further corrosion. Other methods of the boiler preservation are also applied.

A boiler can be repaired only when internal pressure in it is nor bigger than the atmospheric one. Approximately major overhaul of the boiler is carried out every 1…3 years, routine repairs – 1…2 times a year according to the circumstances. Precise terms are presented in the documents of a manufacturer of concrete boiler. The repair of a boiler must last as shortly as possible, so maintenance operation is to be arranged best and, if possible, mechanized.

The mentioned above organizations control technical condition of the boiler. It is examinated from inside every 4 years and not rarely as 8 years it is tested hydraulically to check-up its mechanical resistance. During a hydraulic test the pressure is 25 percent more than the pressure in running boiler, but not less than pi + 0,3 MPa. Exact periods of examination and a pressure during a test are presented in the main documents of a boiler. The results of examinations and functional tests are inscribed in the main document of the boiler-a card of technical and operation data. Boiler description in details, its drawings and other documents are added to this card.