Section 3 Coal burning equipment

3.1.1 The design and arrangements for coal burning equipment are to be such that it can be manually controlled from a suitable position Iocal to the boiler fronts.

3.1.2 Burning arrangements for solid fuel firing:

1. The arrangements should permit a sufficient level of control of coal feed to the grates or bed to avoid uneven firing conditions likely to cause damage to the grate or bed, due to excessive heat or coal build-up, under all operating conditions.

2. In addition to the adequate supplies of air for efficient combustion, sufficient capacity and means of control of the combustion air supply below the grates or beds are to be provided to ensure cooling of the grate or bed under all conditions of coal or alternative means of firing.

3. When the coal bed is not fully incandescent, i.e. during low steaming conditions when coal-fired beds are banked or reduced in output, sufficient purging sequences to sweep the furnace volumes are to be provided before any alternative means of firing is attempted.

3.1.3 Where it is proposed to provide means of firing the boiler simultaneously on coal and oil, details of the arrangements for furnace purging and ignition of oil burners are to be submitted and will be the subject of special consideration.

3.2.1 In boilers fitted with forced and induced draught fans, suitable bias is to be maintained to avoid gas leakage into the boiler room.

3.2.2 In the event of induced draught fan failure, the forced draught fan should be arranged to stop automatically. Alternative arrangements which will permit the forced draught fan to be controlled to reduce the supply of air may be considered.

3.3.1 In general, the coal burning equipment is to be designed to utilise the various grades of coal likely to be encountered.

3.4.1 Where it is proposed to use an alternative means of firing, such as oil or coal/oil slurry mixtures, the arrangements are to be in accordance with the requirements for oil burning, see Pt 5, Ch 14 Machinery Piping Systems.

3.4.2 Particular attention is drawn to the requirements concerning arrangements for securely locking up-take dampers in the fully open position when burning fuel oil.

3.4.3 Where it is proposed to use fuel oil burners for lighting up coal fires, details are to be submitted of the pre-purging sequences of the boiler before lighting-up burners are introduced into the furnace.

3.4.4 Where it is proposed to employ lighting-up burners using diesel oil or similar marine distillate fuels, they are to be provided with their own combustion air supply.

3.4.5 Where it is proposed to use steam purging or steam atomising oil burners with coal fired boilers, particular attention is to be given to furnace purging arrangements. Details of the purging sequences are to be submitted.

3.4.6 The arrangements for purging the oil burners are to be such that the minimum practicable volume of oil will be introduced into the boiler furnace.