Three-pass steam boilers are so-called because the combustion gases that are produced inside them in the burner go round a circuit that has three parts before leaving it:
The function of the burner is to send the fuel and air into the furnace constantly, organize the air flow of pulverized coal reasonably and mix them well for rapid and stable ignition and combustion.
Fuel-to-steam efficiency is a measure of the overall efficiency of the boiler. It accounts for the effectiveness of the heat exchanger as well as the radiation and convection losses. It is an indication of the true boiler efficiency and should be the efficiency used in economic evaluations. As prescribed by the ASME Power Test Code, PTC 4.1, the fuel-to-steam efficiency of a boiler can be determined by two methods: the InputOutput Method and the Heat Loss Method.
Package boiler is a boiler that had been fabricated and available as a complete package. The entire pressure parts have been assembled in the workshop and ready to be sent to the field or site where power plant is located. On the field/site requires only connection and integration of course work in electrical connections, water pipes, steam pipes and fuel piping system to operate. Package boiler is one of classification of boiler based on erection. Design package boilers in general are the type of Fire Tube Boiler and have made up shell and tubes. This type has high heat transfer both radiation and convection.
A dryback boiler has a rear wall that is lined with refractory, a wetback boiler has a rear wall that is jacketed by water. Because of this fact, wetback boilers typically boast higher efficiency than dryback boilers as the heat from combustion goes directly into heating water instead of refractory. Wetback boilers are also more forgiving with load changes as the reversal chamber of the boiler is totally submerged in water creating an even heat transfer on the intermediate tube sheet to furnace joint.
The boiler gas consumption calculation need the following parameters: gas calorific value and boiler thermal efficiency.
Theoretically, the gas consumption of boiler = boiler thermal capacity ÷ (calorific value of gas x boiler thermal efficiency )
Take the 1 tph steam boiler as an example:
= 600,000 cal / (8500Kcal * 0.98) =72m3/h, the 1 tph boiler's gas consumption per hour is about 72 cubic meters.
A fire tube steam boiler is a boiler where the combustion gases from the burner are channeled through tubes that are surrounded by the fluid to be heated. The boiler body is the pressure vessel and contains the fluid. In most cases, this fluid is water that will circulate for heating purposes or become steam for use in processing.
Each set of tubes through which the combustion gas passes, before making a turn, is considered a "step". Consequently, a three-step boiler will have three sets of pipes with the outlet located at the rear of the boiler.
The action of starting up a fire tube boiler for the first time is already a cold start. As a result, the mechanical load in this type of boiler is much greater, as the main characteristic of cold starts is the absence of boiling water and greater stress on the connection and anchorage elements of the boiler.
To make this start a bit easier for the boiler, the boiler operator should reduce the burner load to a boiling point.
