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, in dachas and in private houses. Modern fire-tube boilers differ significantly from their ancestors - they allow, without changing their overall dimensions, to significantly increase the level of productivity.
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-bar models are equipped with two reservoir tanks. In this case, one tank is inside another. These two segments are connected through flanges and steam collectors.
A furnace is located in the front of the unit, and a system for exhausting combustion products is installed in the rear . In order for the steam boiler to work, it is necessary to provide it with air supply. The latter is submitted forcibly. 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 the combustion products are discharged. The boilers are equipped with heat exchangers - the best of them is a steel product. Steel is not exposed to corrosion and is not deformed due to constant temperature changes.
Operating principle
These boilers are one of the subspecies of gas pipe units, the surface of which consists of flame tubes. Liquid or gaseous fuel circulates inside them .
The principle of operation of the fire tube boiler is very simple. On the front of the flame tubes there is a forced-charge burner. It can burn gas or liquid fuels. A heat pipe is nothing more than a combustion chamber. Inside it effectively burns all the fuel that is supplied to the device.
During the operation of this heating equipment , steam is generated. Steam temperature is not higher than 115 degrees. The pressure inside is not more than 0.07 MPa. Such steam is suitable for the heating system of private houses or for use in production processes.
Types of boilers
There are steam and fire tube hot water boilers for rooms. The first heat the coolant with steam. Inside for this there are special tanks. The second is distinguished by the fact 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 combustion products are thrown out into the pipe, they make three passes through the pipes washed by water. The first move is the combustion chamber. There is the highest temperature. Then the gases change their direction and are fed into the pipes of the second stroke, and then into the pipes of the third stroke. This movement pattern is completely carried out by the fan and the natural draft of the chimney.
The first pipe, as already indicated, is the combustion chamber. The second serves to divert the heated water into the hot water supply system. The third provides the heating system.
The water level in the tank of the steam tube boiler is unstable. During operation, water can boil away and in the form of steam enter inside, where droplets are separated by a separator. This is a required process. Otherwise, water hammer will occur, which will not affect the operation of the equipment in the best way. 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 housing and covers - front and rear. 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. Inside there is a convection zone. Additionally, the boiler is covered with special materials for thermal insulation.
Gases here change direction and return to the front. After they give away heat to water or another heat carrier, they will be removed to the chimney.
Electric Steam Boilers
We examined the principle of operation of fire-tube boilers running on gas or liquid fuel. But there are also electrical units. Unlike analogues requiring 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.
Waste heat boilers
For production processes, special fire-tube boilers are used, in which there is no familiar combustion chamber. For the preparation of steam, these models use heat that is generated as a result of various processes. For small loads, gas pipe solutions are used.
For industry, emissions of hazardous products into the open air are reduced, gas cleaning costs are significantly reduced, and the opportunity to use inexpensive fuel for heating is provided.
Water pipe and direct-flow steam unit
The fire tube boiler and the 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 pipes.
The steam drum boiler has pipes connected to the drums of the middle diameter in the design of the furnace screen. Water or other coolant circulates several times through unheated pipes, improving thermal conductivity. Drums are reservoirs within 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 but a coil located inside the firebox. The coolant in the coil is pumped by a pump. Water in the boiler tube flows through the tubes of the evaporator and turns into steam. In the transition zone, the steam formation process ends, and then it is fed to the superheater.
These boilers are an open hydraulic system and can operate at a pressure greater or less than the set pressure.
Among the main advantages, one can single out a high heating rate, excellent circulation, efficiency is higher than that of fire tube boilers, protection against overheating, the ability to use various types of fuel, compact sizes.
Operational Features
The principle of a fire tube boiler is based on the preparation of steam. Therefore, the unit requires proper treatment. You need to regularly monitor the stability of the work. The manufacturer indicates safety requirements.
The main points are scale and deposits. They are often the cause of equipment failure. Due to the design features of the pipeline, deposits accumulate unevenly inside, which can cause overheating.
Due to the fact that the steel fire tube boiler uses a larger amount of water for operation, in contrast to the water tube analog, there is a risk of explosion. The structure of the pipes reduces the rate of circulation of the coolant - so-called stagnant zones are formed.
Boiler service is a timely replacement of heat exchangers, regular cleaning, and operation monitoring. If you follow the instructions, the boiler will work longer than the manufacturer's declared time.
Pros and cons
The main advantage of these solutions is autonomy. Using the available units, you can assemble an excellent, easy-to-use heating system. If necessary, three-way fire tube boilers can heat water for hot water supply. A lot depends on the choice of fuel - before buying, you should focus on models that run on gas, diesel and electricity.
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. If necessary, you can carry out repairs. 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 constant monitoring and maintenance. After some time, the boiler requires a new fueling. 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 are fire tube boilers. These units are an excellent replacement for traditional gas. But during operation there are certain inconveniences. The main plus of these units is autonomy and versatility. The design is also repairable and relatively uncomplicated. The equipment is suitable for preparing hot water. And even though such systems are not very relevant for an apartment building, for country houses and cottages this is affordable heating.