Industrial boilers will produce wastes that needs to be treated during the use process, which is what we mentioned of boiler blowdown. What are the methods for boiler blowdown?
1. Regular blowdown
1) The time interval and quantity of discharge depend on the test results of boiler water. It usually do not exceed 5% of the water supply.
2) When the regular blowdown is being made under high load of the boiler, the blowdown of the water-cooled wall header is generally not required to avoid affecting the normal water circulation of the water-cooled wall and forming a tube explosion incident.
2. Continuous blowdown
The amount of blowdown shall be determined according to the test results of the boiler water, and shall be completed by adjusting the needle-shaped angle of the blowdown tube.
Here load means, amount of steam drawn from the boiler. So when the load increases, the specific volume of the steam in the boiler increases reducing the pressure. This inturn demands for more feed water and more amount of fuel to be burnt. So, for any boiler there will be a feed water level control system put in place to measure the water level in drum. As and when the level of water in the drum reduces, the controller sends a signal to the feed water pump to start and stops when the desired water level is reached. This way the steam generation continues to maintain the desired pressure.
A water level sensor fail on a steam boiler is extremely dangerous. The low water cut of should be tested daily. If the sensor fails the boiler could turn all the water into steam, leaving the boiler dry. Without water in the boiler the flame from the burner would heat up the heating surface to extreme temperatures and would crack and damage the inside of the boiler. But that’s not the dangerous part. If water added to boiler while it is extremely hot. Once water touches the extremely hot heating service, water would immediately start to evaporate into steam. When water evaporates it expands 18x it’s original size. The boiler would explode from the sudden increase in pressure from the inside. Some in some cases, boilers that have exploded out of a building and have landed 100s of feet away.
It could also say, how much heat is required to rais the water temperature from 60 ℃ to 90 ℃.
To calculate heat required follow below steps
Q= mCp dt
Where
m - water flow rate (kg/hr)
Cp- specific heat of water
dt- temperature differences ( 90–60)
You will get heat required in kcal/ hr.
dividing to Q by fuel GCV and system efficiency you will come to know how much fuel (either it is coal or oil) required to raise the temperature of water from 60 ℃ to 90℃.
In the work of transforming a coal-fired boiler into a gas-fired boiler, the principle of changing the original boiler should be reduced without changing the pressure component of the boiler body. The transformation process should focus on the choice of gas burners, the determination of the number of burners, the layout of the burners, the matching design of the furnace layout, and the selection of explosion-proof measures. Step by step, both economic benefits and practicality should be considered.
1. Sufficient furnace temperature: Sufficient fuel combustion of biomass-fired boilers firstly requires high furnace temperature. The temperature should meet the requirements of sufficient fuel combustion. Besides, the combustion speed is required to be proportional to the temperature. Moreover, the furnace temperature should be raised as much as possible on the premise that slag is not formed in the furnace.
Firstly, the combustion of biomass fuel is easy to control. The fuel is easy to ignite. Besides, the combustion speed is faster than that of coal.
Secondly, the biomass-fired boiler can be ignited and extinguished at any time while the coal-fired boiler cannot. The biomass-fired boiler can also be ignited automatically.
Thirdly, the biomass-fired boiler can achieve zero emission of sulfur dioxide, which belongs to environment-friendly boilers.
System load is measured in either BTUs or tons of steam (at a specific pressure and temperature). It would be nearly impossible to size and select a boiler(s) without knowing the system load requirements. Knowing the requirements leads to the following information:
The boiler(s) capacity, taken from the maximum system load requirement.
The boiler(s) turndown, taken from the minimum system load requirement.
Conditions for maximum efficiency, taken from the average system load requirement.
Determining the total system load requires an understanding of the type(s) of load in the system. There are three types of loads: heating, process, and combination.
