ZG Boiler Feeding Spreader

Piping system of the boiler should be designed in a way it makes it possible to drain water easily from the lower collectors, and to deflate air from the upper ones.

Barrels of the boiler should have the appropriate diameter that enables an easy access into them because of the easy and simple repairing of the economizer pipes.

Put the isolation from the outside of the membrane walls.

A steel structure that provides the necessary strength and prevents  deformation of the walls of the boiler should be planned to be inbuilt around the boiler .
The necessary openings for entry should be provided to repair the boiler and control the fireplace and the gas tract.
Basic features of the new hot water boiler, in addition to the ones mentioned above should be:

Nominal (rated) power of                                                                                      58 [MW]
Maximum load (up to 30 minutes)                                                                        64 [MW]
Water temperature at the entrance to the boiler                                                    110 [º C]
Water temperature at the exit of the boiler                                                           145 [º C]
Concessionary pressure                                                                                          25 [bar]
Temperature of the starting water into the district heating network                     145 [° C]
Temperature of the returning water from the district heating network                   75 [º C]
The coefficient of efficiency of the boiler (at 58 MW)                                    min.81 [%]

The quality and dimensions of the inbuilt material (barrels, collectors, display tubes in the membranes, economizer pipes, air heating pipes, plating ...) are defined by the boiler manufacturer or a major mechanical project.

1.1 Fuel
Fuel is coal-lignite from the mine Stanari, located at 25km far from the plant in Doboj. The quantity that is usually kept in the stock is the one that can meet the needs for about 30 days in the winter period.  

The composition and quality of the coal according to which the further calculations will be made are the following:

Elementary composition of the ash of the accepted coal is as it follows:

- SiO2        53.52 [%]
- Fe2O3       8.00 [%]
- Al2O3     16.24 [%]
- TiO3         1.05 [%]
- MnO         0.06 [%]
- CaO          7.75 [%]
- Na2O        0.11 [%]
- SO3        0.172 [%]

1.1.1Coal storage and transport
Coal storage was designed and carried out in an earlier phase for low quality coal (calorific value about 7000 kJ / kg) and with a significantly higher ash content than coal that has been used now, and for the total installed capacity of the boiler room of 116 [MW]. All the devices for coal handling at the warehouse and its removal to the bunker on the existing boilers have also been designed and made.
The whole system for transportation of the coal to the bunkers on the existing boilers is designed for the capacity of 150 [t / h].

Coal bunker(s)
Coal bunker(s) should be provided for a new boiler.. Bunkers volume should provide work of the boiler with a full load for a period of at least 6 hours. Bunker itself  should end in its bottom with a funnel and an opening.

Oblique horizontal conveyor
The final (horizontal) part of the oblique-horizontal conveyor should be extended for about 10 m, in order to provide charging of the bunker for the new boiler ( alongside with the reconstruction of the reversible conveyor, too), as well as bunkers for the existing two boilers ( drawing no.6)

Reversible moving conveyor should be extended for approximately 7.5 m that will allow filling of the bunkers for all three boilers.
Because of the extension of the horizontal part of the vertical-oblique and reverse conveyor it is necessary to extend the rails for the reversible conveyor moving.