For more than two hundred years, mankind has been using fire-tube equipment. Such units are used in heating systems at livestock enterprises, in various industries, in construction companies, in military units. Compact solutions have found application in private heating - in cottages, summer cottages and private homes. Modern fire-tube boilers are significantly different from their ancestors - they allow you to significantly increase the level of productivity without changing their overall dimensions.
What are the features?
The shape and appearance of these units can be very different. However, in most cases, cylindrical products are found on sale. Single-heat models are equipped with two reservoirs. In this case, one tank is inside the other. These two segments are connected via flanges and steam collectors.
In front of the machinea firebox is located, and a system for removing combustion products is installed in the back. In order for the steam boiler to work, it is necessary to provide it with air supply. The latter is forced. Air is supplied under the grate using a fan. It is fixed on the front platform.
Fire tube boilers running on gas or diesel fuel are equipped with a burner and a pipe through which combustion products are discharged. Boilers are equipped with heat exchangers - the best of them is a steel product. Steel does not corrode or deform due to constant temperature fluctuations.
Operation principle
These boilers are one of the subspecies of gas-tube units, the surface of which consists of flame tubes. Liquid or gaseous fuel circulates inside them.
The operating principle of a fire tube boiler is very simple. There is a forced draft burner on the front of the flame tubes. It can burn gas or liquid fuels. The flame tube is nothing more than a combustion chamber. Inside it effectively burns all the fuel that is supplied to the device.
During the operation of such heating equipment, steam is generated. The steam temperature is not higher than 115 degrees. The pressure inside is no more than 0.07 MPa. Such steam is suitable for the heating system of private houses or for use in industrial processes.
Types of boilers
Distinguish between steam and fire tube boilers for indoor use. The first heat the coolant withpair. Inside there are special tanks for this. The latter differ in that the case is heated using water.
Features of steam boilers
These models are in most cases equipped with a three-way heat exchanger. Before the products of combustion are thrown out into the pipe, they make three passes through the pipes, which are washed by water. The first move is the combustion chamber. There is the highest temperature. Further, the gases change their direction and are fed into the pipes of the second pass, and then into the pipes of the third pass. This movement scheme is completely carried out by the fan and the natural draft of the chimney.
The first pipe, as already mentioned, is the combustion chamber. The second serves to divert heated water to the hot water supply system. The third ensures the operation of the heating system.
The water level in the tank of the fire tube steam boiler is unstable. During operation, water can boil away and enter in the form of steam inside, where drops are separated using a separator. This is a required process. Otherwise, water hammer will occur, which will not have the best effect on the operation of the equipment. Owners must constantly monitor how much water is in the boiler.
Most of these units are used in industrial and technological processes when maximum energy efficiency is needed. Boilers of this type create a huge amount of heat for heating fuel tanks, deaerators, turbines.
Water heating units
The design is a body and covers - front and back. There are also pipes for the removal of gases, supports. The housing has a combustion chamber in the form of a flame tube with a rounded bottom. There is a convection zone inside. Additionally, the boiler is covered with special materials for thermal insulation.
The gases here change direction and return to the frontal part. After they give off heat to water or other coolant, they will be led out into the chimney.
Electric steam boilers
We examined the principle of operation of fire-tube boilers operating on gas or liquid fuel. But there are also electrical units. Unlike analogues that require gas or liquid fuel, electrical devices do not burn oxygen in the air and do not need fuel reserves. Many models are equipped with automation and remote control systems. Such models are much more profitable than their gas or diesel counterparts.
HRSG
For production processes, special fire-tube boilers are used, in which there is no usual combustion chamber. For the preparation of steam in these models, heat is used, which is generated as a result of various processes. For light loads, gas-pipe solutions are used.
For the industry, the emission of hazardous products into the open air is reduced, the cost of gas purification is significantly reduced, and it is possible to use inexpensive fuel for heating.
Water-tube and once-through steamunit
Fire tube boiler and water tube boiler are different from each other. Water-tube - the exact opposite of a fire-tube unit. By the way these solutions work, they distinguish water-tube and direct-flow.
The steam drum boiler has pipes in the design of the combustion screen connected to drums of medium diameter. Water or other coolant circulates several times through unheated pipes, improving thermal conductivity. Drums are tanks inside which water and steam are separated. The circulation in the drums can be either forced or natural.
There is no drum in the once-through boiler. This is nothing more than a coil located inside the firebox. The coolant is pumped into the coil using a pump. The water in the water tube boiler flows through the evaporator tubes and turns into steam. In the transition zone, the steam formation process ends and then it is fed to the superheater.
These boilers are open-loop hydraulic systems and can operate at pressures greater than or less than the specified pressure.
Among the main advantages are high heating speed, excellent circulation, higher efficiency than fire tube boilers, overheating protection, the ability to use various types of fuel, compact size.
Features of operation
The principle of a fire-tube boiler is based on the preparation of steam. Therefore, the unit requires proper attitude. You need to regularly monitor the stability of the work. The manufacturer specifies the requirements forsecurity.
The main points are scale and deposits. They are often the cause of equipment failure. Due to the design of the pipeline, deposits accumulate unevenly inside, which can cause overheating.
Due to the fact that a steel fire-tube boiler uses more water to operate, unlike a water-tube counterpart, there is a risk of an explosion. The structure of the pipes reduces the circulation rate of the coolant - the so-called stagnant zones are formed.
Boiler maintenance is the timely replacement of heat exchangers, regular cleaning, monitoring of work. If you follow the instructions, the boiler will work longer than the period declared by the manufacturer.
Pros and cons
The main advantage of these solutions is autonomy. With the help of affordable units, you can assemble an excellent, easy-to-use heating system. If necessary, three-pass fire-tube boilers can heat water for hot water supply. Much depends on the choice of fuel - before buying, you should focus on models that run on gas, diesel and electricity.
The fuel and materials from which the boiler is made significantly affect the service life. On average, the service life is from 20 to 50 years. Repairs can be made if necessary. Automation and electronics make it possible to adjust the temperature and keep it at a constant level.
Among the shortcomings, reviews highlight the need for constantcontrol and maintenance. After some time, the boiler requires a new bookmark of fuel. This is especially true for solid fuel models. Sometimes you have to clean the combustion chamber from soot and slag, clean the chimney.
Conclusion
So, we found out what fire-tube boilers are. These units are an excellent replacement for traditional gas units. But during operation there are certain inconveniences. The main advantage of these units is autonomy and versatility. Also, the design is repairable and relatively simple. The equipment is suitable for preparing hot water. And although such systems are not very relevant for an apartment building, this is affordable heating for country houses and cottages.
