Hot water solid-fuel boiler
The boiler addresses efficiency and wear issues by employing tray burners with horizontal fuel movement and a combined heat exchanger system, achieving high efficiency and extended component life with reduced fuel consumption and ash emission.
Patent Information
- Authority / Receiving Office
- RU · RU
- Patent Type
- Patents
- Current Assignee / Owner
- OOO PROMTEPLO
- Filing Date
- 2025-07-04
- Publication Date
- 2026-07-09
AI Technical Summary
Existing solid fuel boilers suffer from low efficiency, limited power, uneven combustion, high maintenance needs, and increased wear due to vertical fuel feed and L-shaped burners, leading to reduced operational life and increased coal consumption.
A hot water solid fuel boiler design featuring tray burners with horizontal fuel movement, a U-shaped water jacket, and a combined heat exchanger system with plate compensators, ensuring efficient combustion and increased flame temperature, along with a horizontal and vertical flue gas path for improved heat transfer and reduced ash emission.
The boiler achieves efficiency up to 92-94%, extended component life, reduced fuel consumption, and enhanced environmental friendliness by minimizing ash emission and wear on mechanical components.
Smart Images
Figure 00000001_ABST
Abstract
Description
[0001] The invention relates to the field of industrial and municipal heat power engineering, namely to industrial hot water boilers of medium power, and can be used for heat supply of residential buildings, buildings and structures for municipal and domestic purposes, industrial premises equipped with hot water heating and hot water supply systems.
[0002] Industrial heating boilers are hot water heating devices with a capacity of over 100 kW. Solid fuel boilers operate by converting the energy released during combustion into heat, which is used to heat water. Fuels used include coal, including brown coal, wood, peat briquettes, and various types of wood waste.
[0003] The prior art includes known classic solid fuel boilers of small and medium power, containing in the central part of the boiler a combustion chamber (furnace) with a burner installed in it, which is a device for burning fuel, as well as a water heat exchanger with inlet and outlet pipes, and the heat exchanger can be located on top, can encircle the combustion chamber on all sides in the form of a “jacket”. At the bottom of the boiler there is an ash pan for waste raw materials and an air blower (RU Patent No. 2376525 C1, priority date 07 / 28 / 2008, publication date 12 / 20 / 2009, authors: Polikarpov A.N. et al., RU; Russian Federation Patent No. 2575591 C1, priority date 07 / 29 / 2014, publication date 02 / 20 / 2016, authors: Zakharov G.A. et al., RU; Russian Federation Patent No. 137989 U1, priority date 11 / 07 / 2013, publication date 02 / 27 / 2014, author Kostenko D.P., RU; Russian Federation Patent No. 205295 U1, priority date 12 / 24 / 2020, publication date 07.07.2021, authors: Polikarpova M.G. et al., RU).
[0004] The main disadvantage of classic solid fuel boilers is the low efficiency factor (COP), due to the low efficiency of the combustion and heat exchange devices, as well as their limited use mainly in low-power boilers.
[0005] In addition to classic boiler models, improved devices such as long-burning or pyrolysis boilers are also available. These utilize an algorithm for the efficient combustion of all fuel components (primarily high-calorific pyrolysis gas), require minimal human intervention for boiler maintenance during operation, and have increased efficiency. However, like classic boilers operating on solid fuels, they have the following disadvantages:
[0006] - wave-like thermal mode of operation of most models;
[0007] - waste formation - ash and soot;
[0008] - the need for manual adjustment due to the low level of automation;
[0009] - the need for a warehouse for storing fuel supplies (coal, firewood, etc.).
[0010] (https: / / tmf.ru / info / articles / vidy_otopitelnykh_vodogreynykh_kotlov / , access date 05 / 20 / 2025).
[0011] Long burning boilers include shaft-type boilers with upper combustion, which allow for complete combustion of fuel due to improved mixing of secondary blast air with fuel gasification products (RU Patent No. 182455 U1, priority date 08 / 09 / 2017, publication date 08 / 17 / 2018, authors: Panin I.S. et al., RU; RU Patent No. 183159 U1, priority date 08 / 09 / 2017, publication date 09 / 12 / 2018, authors: Panin I.S. et al., RU; RU Patent No. 183190 U1, priority date 08 / 09 / 2017, publication date 09 / 13 / 2018, authors: Panin I.S. et al., RU).
[0012] Also known is a long-burning solid fuel boiler containing a heat exchanger with an ash pan located underneath it, to which an air intake is connected, the heat exchanger is made in the form of a vertically installed tank, inside which in the upper part there is a fuel bunker with a door for loading fuel and at least one flue gas duct, the outlet of which is brought out to the upper part of the fuel bunker, where a chimney is connected to it, and inside the lower part of the heat exchanger tank there is a firebox with a grate and additional air ducts, while in the firebox along the inner wall of the heat exchanger there is an afterburning chamber for combustion products, and combustion catalysts are located in it, and the inlet of the afterburning chamber is located above the grate, and its outlet is connected to the inlet of the flue gas duct, and the outlets of the additional air ducts are introduced into the afterburning chamber (RU Patent No. 132530 U1, priority date 02.04.2013, publication date 09.20.2013, authors: Bashkirtsev O.G. et al., RU).
[0013] A common disadvantage of these long-burning solid fuel boilers is their low power, caused by the small volume of the combustion chamber to ensure complete and uniform combustion of the loaded fuel.
[0014] Also known is a hot water boiler with automatic fuel and air supply, comprising a housing made of two coaxial shells, in the annular space between which are located smoke tubes of a convective bundle and a heating circuit of the coolant, a combustion chamber formed by the cavity of the inner shell, a working thermostat, a fuel bunker and a burner with a conical tip, located in the combustion chamber and connected by an automatic fuel supply system with the fuel bunker and an automatic supply of combustion air with a supercharging fan, wherein the automatic fuel supply system is made in the form of a screw conveyor driven by a gear motor, and the working thermostat through a programmable controller controls the supply of electric current to the fan and the gear motor, in addition, on the rear surface of the housing are located water inlet and outlet pipes, pipes for connecting underfloor heating and pipes for connecting a boiler,The boiler also contains a firebox door in the front part, the frame of which connects the shells, there are ash pan doors in the front and rear lower parts, a flue gas outlet box is located on the rear surface of the body, and on the outer surface of the body there is thermal insulation made of mineral wool, closed on top with a decorative removable lining (RU patent No. 2296920 C1, priority date 08.08.2005, publication date 10.04.2007, author Andris Lubinsh, LV).
[0015] The disadvantage of this analogue is the increased load on the gear motor and the fuel feed auger due to the need to push the fuel vertically onto the burner bowl and overcome the resistance due to the L-shaped burner with a conical tip.
[0016] On the official website of the East Siberian Boiler Plant (VSKZ), an enterprise producing heating equipment, the following models of low- and medium-power automatic boilers are manufactured: VSKZ-ECO 14-270 kW; VSKZ-LIGHT 15-28 kW; VSKZ-ECO PLUS 15-210 kW; VSKZ-LUX 20-60 kW; VSKZ-COMPACT 20-85 kW, having a side-mounted hopper and equipped with a retort burner (https: / / vskz.ru / , accessed on 05 / 25 / 2025).
[0017] Also known are the VSKZ-DUO series of medium-power automatic boilers with multiple retort cast iron burners, specifically with two burners in 400-500 kW models or three burners in 600-800 kW models. These boilers are designed with a rear-mounted hopper. (https: / / vskz.ru / %D0%B0%D0%B2%D1%82%D0%BE%D0%BC%D0%B0%D1%82%D0%B8%D1%87%D0%B5%D1%81%D0%BA%D0%B8%D0%B5-%D0%BA%D0%BE%D1%82%D0%BB%D1%8B-%D0%B2%D1%81%D0%BA%D0%B7-%D0%B4%D1%83%D0%BE-%D1%8D%D0%BA%D0%BE%D0%BB%D0%BE%D0%B3%D0%B8%D1%87%D0%B5%D1%81%D0%BA%D0%B8%D0%B5, view date (25.05.2025).
[0018] The prototype is the VSKZ-DUO 500 automatic industrial hot water solid fuel boiler, designed with two retort cast iron burners in the firebox and a heating capacity of 500 kW. The boiler body is made of 6 mm thick steel with double walls forming the water jacket of the heat exchanger. A water-filled shelf is located above the burners in the firebox, and a fire-tube heat exchanger is located above the firebox. In the front part of the boiler there are two doors for the heat exchanger, firebox and ash pan, and in the rear part there is a fuel supply unit, including a hopper and screw conveyors with a gear motor, connecting the hopper with the burners, there are also blower fans, supplying air through special channels to the burner bowls, and pipes for the inlet and outlet of the coolant, in addition, at the top of the boiler there is a pipe for the outlet of the flue gases from the heat exchanger, and the control of the screw conveyors and fans is carried out by a microcontroller.
[0019] %D0%BB%D1%8B-%D0%B2%D1%81%D0%BA%D0%B7-%D0%B4%D1%83%D0%BE-%D1%8D %D0%BA%D0%BE%D0%BB%D0%BE%D0%B3%D0%B8%D1%87%D0%B5%D1%81%D0%BA%D0 %B8%D0%B5 / %D0%B0%D0%B2%D1%82%D0%BE%D0%BC%D0%B0%D1%82%D0%B8%D1%8 7%D0%B5%D1%81%D0%BA%D0%B8%D0%B9-%D0%BA%D0%BE%D1%82%D1%91%D0%BB- %D0%B2%D1%81%D0%BA%D0%B7-%D0%B4%D1%83%D0%BE-500-%D1%8D%D0%BA%D0 %BE%D0%BB%D0%BE%D0%B3%D0%B8%D1%87%D0%B5%D1%81%D0%BA%D0%B8%D0%B9, viewing date 05 / 25 / 2025, prototype).
[0020] The disadvantages of the prototype include a boiler efficiency limited to 90%, as well as insufficient wear resistance as its thermal output increases, and the need for more burners, which complicates the boiler design. These shortcomings are primarily due to the use of L-shaped retort burners in the boiler design, characterized by vertical fuel feed and increased load on the gearmotor and fuel feed auger due to the need to push the fuel vertically onto the burner bowl. As a result, the gearmotor and the auger itself cannot operate for more than two heating seasons. Uneven combustion of fuel around the burner bowl can cause unburned fuel to fall into the ash pan, thereby reducing boiler efficiency. Furthermore, the combustion flame temperature, which ranges from 650-880°C, also reduces efficiency.Furthermore, manufacturing a retort burner requires turning, milling, and drilling, which increases labor costs. The fuel supply unit typically uses a 102 mm diameter pipe, with reinforced versions using a 127 mm diameter pipe. At high power settings, to ensure the required fuel volume for thermal energy generation, the gearmotor operates at a duty cycle of 60-90%, which places increased strain on the gearmotor and contributes to accelerated equipment failure. Secondly, the heat exchanger is unreasonably thick at 6 mm and has an insufficient heat exchanger area, which is designed for higher-quality coal. This also leads to reduced boiler efficiency and increased coal consumption.
[0021] The technical problem solved by the invention is the need to increase the efficiency and wear resistance when creating a solid fuel hot water boiler with a long burning capacity of (300-1600) kW with two burners by using tray burners of an improved design, characterized by horizontal movement of fuel on a cast iron tray-grate and ensuring more efficient combustion of fuel with an increase in the temperature of the combustion flame of the fuel in the range of 860-980 °C.
[0022] To solve the technical problem and achieve the technical result, a hot water solid fuel boiler is proposed, comprising a steel casing with double walls forming a water jacket, a firebox with two burners installed in it, a water-filled shelf with compensators located above the burners, a horizontal fire-tube heat exchanger designed to pass flue gases from the firebox chamber through the heat exchanger pipes into the chimney, in the front part of the boiler contains two doors of the heat exchanger, firebox and ash pan, and in the rear part there is a fuel supply unit including a hopper and fuel supply augers with a gear motor connecting the receiving necks of the hopper with the burners, and a supercharger fan is connected to the body of each burner, and the inlet and outlet pipes of the coolant are located at the edges, respectively, in the lower and upper corners of the boiler. What is new is that two tray burners are installed in the firebox chamber,each of which contains a cast iron grate tray in the form of a plate with openings and with inclined longitudinal walls connected to the plate by welded joints, and under the grate tray a steel burner body is installed, forming a channel with the grate for blowing air, wherein the tray burners are inclined relative to the horizontal at an angle equal to 6°, in addition, the said burners are equipped with a flat former and a diffuser in the form of a triangular prism for uniform distribution of fuel over the entire plane of the grate tray with the possibility of effective combustion; the water jacket is made U-shaped, consisting of side and top walls equipped with plate compensators made of steel and fixed between the walls of the jacket by means of welded joints vertically in the side walls and horizontally in the top wall, wherein openings are made in the compensators, and a shaft is made at the bottom of the boiler under the vertical compensators,communicating with the coolant inlet pipe for its uniform passage into the jacket; the boiler also contains a gas path for the movement and afterburning of flue gases, wherein for the first pass of flue gases a horizontal shaft is made, located above the water-filled shelf and intended to increase heat removal and the deposition of suspended matter and ash, the second pass of flue gases is made in the lower part of the horizontal fire-tube heat exchanger, the pipes of which are communicated with the said shaft, for the third pass of flue gases a vertical shaft is made, communicating with the pipes of the horizontal fire-tube heat exchanger, intended for the turn of flue gases into the fourth pass through the upper part of the horizontal fire-tube heat exchanger into the chimney.
[0023] Fig. 1 shows a schematic diagram of a solid fuel hot water boiler, a general front view with the doors conditionally removed; Fig. 2 - the same, left view; Fig. 3 - the same, right view, with a local longitudinal section; Fig. 4 is a general view of the boiler in 3D, with a longitudinal section; Fig. 5 shows a tray burner assembled with a fuel supply unit, general view.
[0024] The design of an industrial hot water solid fuel boiler with a thermal capacity of 1600 kW, related to automatic boilers PT (300-1600 kW) is given as an example. The claimed boiler is a combined heat exchanger, united in a steel casing 1 with a firebox 2. Casing 1 is made with double walls of 09G2S steel, 5 mm thick, forming a U-shaped water jacket 3, consisting of side and top walls equipped with plate compensators 4, made of 5 mm thick steel and fixed between the jacket walls at a pitch of 200 mm vertically in the side walls and horizontally in the top wall. These compensators are designed to reduce the deformation of the sheet material of the walls when operating under pressure. In the lower part of the boiler there is a combustion chamber (furnace) 2 surrounded by a water jacket 3, in which two tray burners 5 are installed.Each burner comprises a cast-iron grate 6 in the form of a perforated plate with inclined longitudinal walls connected to the plate by welded joints. A steel burner body 7 is mounted beneath the grate 6, forming a channel 8 for air injection with the grate. The diameter and number of openings in the grate 6 were determined experimentally to ensure more efficient combustion and increase the thermal output of the burners 5. The trough burners 5 are inclined relative to the horizontal at an angle of 6° to facilitate the removal of caked-on pieces (cakes). Furthermore, the trough burners are equipped with a flat former 9 and a triangular prism-shaped diffuser 10 to evenly distribute the fuel across the entire surface of the grate trough, enabling efficient fuel combustion with an increased flame temperature within the range of 860-980°C.Ash pans (not shown) are installed in the combustion chamber 2 beneath the trough burners 5, and a water-filled shelf 11 is located above the trough burners 5. This shelf is a plate heat exchanger made of 6 mm thick sheet steel, which bears the main heat load from the burners 5 during boiler operation and serves as a baffle for uniform flame distribution throughout the heat exchanger. The water-filled shelf 11 is equipped with horizontal plate compensators 12, which serve to reduce sheet metal deformation when operating under pressure. Furthermore, the shelf 11 is inclined at a 1° angle to remove air bubbles, and the compensators 12 of the shelf 11 are perforated to improve coolant (water) circulation and reduce the formation of air bubbles during coolant boiling.Above the combustion chamber 2, there is a horizontal fire-tube heat exchanger 13, designed for the passage of flue gases from the combustion chamber 2 along the first pass through the shaft 14, communicating with the lower pipes of the heat exchanger 13, along the second pass through the lower pipes of the heat exchanger 13, along the third pass through the vertical shaft 15, communicating with the pipes of the heat exchanger 13, and also designed for the turn of flue gases into the fourth pass through the upper pipes of the heat exchanger 13 into the chimney 16, wherein the diameter of the pipes of the heat exchanger 13 is 89 mm. On the front wall, the boiler contains two doors for the heat exchanger 17, the combustion chamber 18 and the ash pan 19, which are provided with thermal insulation and a seal that ensures a tight fit to the hatch body using a locking mechanism.An inspection hatch 20 is provided in the rear wall of the boiler, intended for inspection and repair of the boiler heat exchanger during its operation, and at the edges in the lower and upper corners of the boiler, respectively, there are inlet 21 and supply 22 pipes for the coolant. In the rear part of the boiler, there is a fuel supply unit, including a hopper 23 and fuel supply augers 24 with a gear motor 25, connecting the receiving necks of the hopper with the burners 5, wherein a blower fan 26 is connected to the body of each burner. Transport loops 27 are fixed on the top of the boiler. The surface of the boiler is covered with decorative metal covers with thermal insulation made of mineral wool (not shown).
[0025] The technology for obtaining thermal energy is as follows: the cooled coolant is supplied to the boiler through the inlet pipes 21, which communicate with the shaft (50×100 mm) of the water jacket 3 and are made along the edges of the boiler in the lower corners for uniform distribution of the coolant throughout the boiler and to ensure proper circulation, where the coolant, in contact with the water-filled heat-exchange surfaces of the combustion chamber 2 and with the pipes of the convective heating surfaces of the heat exchanger 13, is heated and through the supply pipe 22 enters the consumer.
[0026] The main types of fuel for the boiler are: fractionated brown coal (seeds, peas, nuts), sawdust granules (fuel pellets and agropellets). The recommended calorific value of coal is 4920-5600 kcal / kg. This fuel is loaded into a hopper 23, which is hermetically sealed with a lid. Augers 24, rotating with the help of a worm gear motor 25, take fuel from the hopper and feed it to the grate troughs 6 of burners 5, equipped with flat formers 9 and spreaders 10 for uniform fuel combustion, and also equipped with special channels 8, through which blower fans 26 supply air under the grate troughs of the burners.
[0027] The operation of each auger and fan is controlled by a microprocessor controller, which determines the duration of the auger rotation, as well as the rotation speed of the fan to maintain the set temperature of the coolant supplied from the boiler (not shown).
[0028] During fuel combustion in tray burners, the combustion flame temperature increases to 860-980°C, indicating an increase in the temperature shoulder and increased heat transfer from fuel combustion to the coolant. Therefore, to ensure intensive heat transfer, the boiler contains a combined heat exchanger (water-filled plate heat exchanger 3, 11 and fire-tube heat exchanger 13) with a sufficient coolant capacity of 5540 liters.
[0029] The blower fan 26 of each burner creates excess pressure in the combustion chamber 2, due to which gases from the combustion chamber enter the fire-tube heat exchanger 13 through the gas path. At the same time, the flame is distributed over the entire plane due to the first water-filled fire-beater shelf 11. Next, bending around the water-filled shelf, the air-flame mixture flow enters the first wide horizontal shaft 14, where the flow calms down, resulting in up to 70% of the entrained ash settling on shelf 11. The flow of hot gas-air mixture then enters the second pass of the fire-tube heat exchanger 13 and, being distributed through the tubes, it calms down and up to 20% of the ash settles. After passing the third pass through the vertical shaft 15, the flue gases turn into the fourth pass through the upper pipes of the heat exchanger 13, where the mixture of flue gases gives off residual heat to the coolant, and up to 4% of the carried away ash falls out.Then the flue gases enter the chimney box 16, where the remaining ash calms down and settles to 3%.
[0030] Thus, the emission of entrained ash from the chimney into the environment is reduced by 97%, demonstrating the boiler's environmental friendliness. Furthermore, the interval between complete heat exchanger cleanings is extended and can reach an entire heating season. Ash produced during fuel combustion is displaced by a fresh batch of fuel and falls from the 5 chute burners into ash boxes with a sufficient capacity of 750 liters.
[0031] The improved design of the boiler heat exchanger and the use of improved tray burners in the combustion chamber have made it possible to obtain the following technical and economic advantages in the manufacture and operation of the claimed industrial hot water solid fuel boiler:
[0032] Thanks to the use of plate compensators in the heat exchanger, the metal thickness is reduced to 5 mm, and the load from the internal pressure is uniformly distributed, which is 3.5 kg / cm 2 .
[0033] The increased heat exchanger area, designed for brown coal with a lower calorific value compared to coal, contributes to a higher boiler efficiency of up to 92-94% and leads to a reduction in fuel consumption.
[0034] The simplicity of the design of the tray burner ensures a reduction in labor costs for its manufacture due to the exclusion of milling work.
[0035] Since there's no need to push coal upward, and the resistance is reduced when pushing coal horizontally directly onto the grate, the load and wear on the gearmotor and auger are reduced. This extends the service life of the loaded components and ensures trouble-free operation of the boiler as a whole. The auger and gearmotor have a service life of 3 years.
[0036] The overall dimensions of the boiler (w / h / d) are 2210×2450×4320 (mm), which allows the declared boiler to be used not only in stationary boiler houses, but also for use inside modular and block-modular boiler houses, fitting within the transport dimensions.
[0037] The technical result achieved by the invention consists in improving the operational characteristics of a hot water solid fuel boiler by increasing the boiler efficiency to 92-94%, increasing wear resistance and improving environmental friendliness.
Claims
A hot water solid fuel boiler comprising a steel body with double walls forming a water jacket, a firebox with two burners installed therein, a water-filled shelf with compensators located above the burners, a horizontal fire-tube heat exchanger designed for the passage of flue gases from the firebox chamber through the heat exchanger pipes into the chimney, in the front part of the boiler there are two doors of the heat exchanger, firebox and ash pan, and in the rear part there is a fuel supply unit including a hopper and fuel supply augers with a gear motor connecting the receiving necks of the hopper with the burners, wherein a supercharging fan is connected to the body of each burner, and the inlet and outlet pipes of the coolant are located at the edges in the lower and upper corners of the boiler respectively, characterized in that two tray burners are installed in the firebox chamber, each of which contains a cast iron tray-grate in the form of a plate with openings and with inclined longitudinal walls,connected to the stove by welded joints, and a steel burner body is installed under the grate tray, forming a channel with the grate for blowing air, wherein the tray burners are inclined relative to the horizontal at an angle equal to 6°, in addition, the said burners are equipped with a flat former and a diffuser in the form of a triangular prism for uniform distribution of fuel over the entire plane of the grate tray with the possibility of effective combustion; the water jacket is made U-shaped, consisting of side and top walls equipped with plate compensators made of steel and secured between the walls of the jacket by means of welded joints vertically in the side walls and horizontally in the top wall, and openings are made in the compensators, and at the bottom of the boiler under the vertical compensators there is a shaft communicating with the coolant inlet pipe for its uniform passage into the jacket; the boiler also contains a gas tract for the movement and afterburning of flue gases,wherein for the first passage of flue gases a horizontal shaft is made, located above the water-filled shelf and intended to increase heat removal and sedimentation of suspended matter and ash, the second passage of flue gases is made in the lower part of the horizontal fire-tube heat exchanger, the pipes of which are connected with the said shaft, for the third passage of flue gases a vertical shaft is made, communicating with the pipes of the horizontal fire-tube heat exchanger, intended to turn the flue gases into the fourth passage through the upper part of the horizontal fire-tube heat exchanger into the chimney.