LT6205B - Domestic boiler operating on solid fuel of variable moisture content - Google Patents

Abstract

The invention relates to the field of heating technology. The aim of the invention is to improve the operating efficiency of a boiler, and specifically the heating and power-generating characteristics thereof, and also to reduce emissions of harmful gases into the atmosphere during the operating process of the boiler. The patent describes a domestic boiler of novel design, which operates on solid fuel of variable moisture content and consists of a metallic housing, a furnace, a combustion chamber, a heat exchanger, a burner with openings for feeding in heated and cold air, the burner being mounted at the transition from the furnace to the combustion chamber, an ash bin and a smoke flue. The novelty consists in that the burner, with a length from the wall of the combustion chamber to the centre thereof, is mounted horizontally in the lower part of the combustion chamber above a furnace grate, and the ash bin is equipped with a baffle plate mounted perpendicularly to the lower surface of the ash bin for restricting the entry of air into the combustion chamber from below via the furnace grate. The baffle plate is mounted movably along the length of the ash bin in order to control the pyrolysis area above the furnace grate depending on the type of fuel, and the particle distribution and moisture content thereof. The features mentioned enable the boiler to switch rapidly to pyrolysis mode, while also improving fuel consumption efficiency and reducing emissions into the atmosphere.

Description

Installations for the efficient combustion of traditional types of solid fuels (coal, wood, peat) as well as production wastes (sawdust, straw, etc.), such as boilers with a partial or full pyrolysis scheme, are classified as heating techniques and widely used in economic activities.

Known analogue described in patent LT5938 (B), application number LT20110000081, installation for the utilization and heating of tires, rubber, plastics, automotive oil filters and wood-panel waste and its method of operation, authors and applicants Pužauskas Edvinas; Braukyla Kęstutis; Sweeps Virgil. A waste incineration plant is described which, according to the authors, has a high efficiency in the pyrolysis process of different types of waste. Specifically, a heat exchanger is provided adjacent to the flue of this installation, the pipes of which are connected to the combustion chamber water tank and the main water tank into which the condensate dryer-cooler is located; the flue heats up and transfers heat to the heat exchanger, from which water is fed through a pipe to the combustion chamber water tank, and through a pipe to a condensate dryer-cooler water tank, where the water is mixed with condensate and returned to the heat exchanger.

Although the unique feature of this installation is the original scheme of water distribution in the heat exchanger system, the obvious disadvantage of this design is the high thermal inertia and the long transition time to stationary mode.

Also known is patent LT5864 (B), application number LT20110000042, gas generating solid fuel boiler, authors and applicants Braukyla Kęstutis; Sweeps Virgil, who describes a solid fuel boiler consisting of a metal body, a firebox, a lid, a gas collection chamber, a combustion chamber, and a heat exchanger. The firebox is directly connected to the gas collection chamber. The burner and heat dissipator are vertically mounted in the combustion chamber with openings for maintaining a constant temperature in the combustion chamber and for efficient heat distribution near the heat exchanger collectors.

This design is unique in that the gas burner is mounted vertically, as well as providing additional air to the burner to increase the combustion efficiency of the gases produced during the pyrolysis process, as well as a diffuser above the burner for even heat distribution. However, the disadvantage of this design is that the pyrolysis process is not controlled, which reduces its thermal efficiency.

Other known analogs described in patent LT5919 (B), application number LT20110000043, gas generator furnace, authors and applicants Braukyla Kęstutis; Virgil flies away. This is a device for gas generation by pyrolysis. The enclosure is made of refractory brick and the outside is covered with a steel casing. Fueling is done by conveyor. The fuel passes through a sloping plane, where it is partially dried and fed to a lattice pyrolysis process to generate gas.

The disadvantage of this design is that the thermal energy released during the gas generation process is not utilized.

Also known analog, patent LT5933 (B), application number LT20110000068, Tire, rubber and plastic waste disposal facility, authors and applicants Braukyla Kęstutis; Sweeps Virgil. Describes a tire, rubber and plastic waste recycling facility. The unit consists of a solid fuel boiler, a gas collection chamber, a burner mounted between the gas collection chamber and the gas combustion chamber, a flue, a boiler with a lid, installed in the gas combustion chamber and for waste heating, a condensate collector - cooler with one end an outlet pipe connected through a sleeve to the boiler cover and the other end connected to a channel for supplying gas to the burner.

The disadvantage of this boiler design is that it is not possible to adjust its parameters when burning different types of waste.

Along with certain advantages, all of the above-mentioned inventions have a number of disadvantages when using wet fuels, namely:

1) slow transition to the main operating mode;

(2) malfunction or shutdown at a fuel humidity higher than

25%;

(3) a sufficiently high concentration of CO in the exhaust from combustion products.

These deficiencies are somewhat resolved in a boiler, a prototype described in WO2011136629 (LT5731B). Domestic solid fuel boiler with gas burner and method of gas burning, authors and applicants Braukyla Kęstutis; Sweeps Virgil. The patent describes an invention which aims to increase the formation of a combustible mixture, its burning efficiency and, at the same time, the efficiency of the boiler. The boiler furnace, through which a valve mounted in the furnace door, is supplied with a primary air volume directly connected to a metal burner installed in the combustion chamber. The burner construction consists of a double-walled housing with an internal duct. The metal burner housing has holes: one on the outer wall of the housing for secondary supply of air from the space between the burner walls; other openings are used to discharge a secondary amount of warmed air into the burner channel. A metal ring is inserted into the burner passage to reduce the hole for the passage of flammable gas into the passage. An air supply tube is fitted to the burner for additional air supply. The combustible mixture formed during the pyrolysis process is incinerated in the burner channel.

The disadvantages of the prototype include slow transition to stationary operation and inefficient regulation of boiler operation in cases where fuel types and humidity differ.

The object of the invention is to eliminate the aforementioned deficiencies of the prototype, as well as to increase the energy efficiency of the boiler, to reduce harmful emissions and to expand the functionality by adding the possibility of using a wide range of fuels with different humidity.

The aim is achieved by realizing the new design of the boiler. The object of the invention is that a new construction of a solid fuel boiler of different humidity, consisting of a metal body, a furnace, a combustion chamber, a heat exchanger, a burner with openings for supplying heated and cold air and installed in the passage from the furnace to the combustion chamber, ash collection chamber and chimney, the new one is that the burner, which is equal to the distance from the combustion chamber wall to its center, is mounted horizontally in the lower part of the combustion chamber above the grill, and the ash collection chamber has a damper perpendicular restricting access to the combustion chamber from below, through the grill.

Also new is that the damper is fitted with the ability to slide it over the entire length of the ash collection chamber; in order to adjust the pyrolysis area above the lattice depending on the type of fuel, dispersion and humidity.

The invention is further illustrated by a drawing in which FIG. 1 shows a general diagram of the boiler.

Boiler consists of: metal housing 1, furnace 2 with door 6 and cover 3, draft duct 4, grate 5, combustion chamber 8, gas burner 9 with special holes 7, heat exchanger 10, flue chamber 11, ash collecting chamber 12 with damper

13th

The principle of boiler operation. There are two operating modes: the normal combustion mode for reaching the pyrolysis temperature and preparation for the main mode; and the main one is the pyrolysis mode.

Boiler start-up is done in this way. The lid 3 is opened, the solid fuel (wood, coal, sawdust, briquettes, peat, etc.) is loaded into the combustion chamber 2 (by conveyor or manually) and the lid 3 is closed. Thereafter, the lid 6 and the draft duct 4 of the flue 11 are fully opened by means of a gas burner 9 which supplies the natural gas in this mode, the fuel being ignited. The damper 13 is located in the extreme position furthest from the cover 6 (in the drawing, the rightmost position), which allows air to enter the furnace from below, through the grate 5 over the entire cross-sectional area of the furnace. At the bottom of the furnace, the classic combustion process begins and the temperature rises to 700-800 C. When this temperature is reached, the lid 6 is partially closed, leaving a gap of about 1 cm, thus reducing air entry into the furnace. The valve 13 is moved to the position (left in the drawing), whereby the optimum pyrolysis process for the given fuel type is taken into account, considering its moisture content. The boiler enters the main mode - pyrolysis mode. The pyrolysis process is mainly localized in the lower right corner of the furnace (marked as area 14 in the drawing). The flammable gas evolved during the pyrolysis process through the draft passes through the gas burner 9 in the direction of the combustion chamber 8, through special openings 7, mixes with air in the burner passage and burns effectively in the combustion chamber 8. falls, the temperature sensor is triggered, and a signal is sent to the next operating step: or to the next cycle, ie fuel loading, etc .; or boiler shutdown.

In order to evaluate the efficiency of the product in comparison with the prototype, the emissions of combustion products were measured at an interval of 15 minutes in the opening of the combustion chamber 8:

Measurements, CO, ppm Boiler Prototype 1 190 300 2 180 270 3 160 260

The comparative table shows that the emissions of the proposed boiler are significantly lower, which indicates its greater efficiency compared to the prototype.

Claims (2)

1. Domestic boiler fired by a solid fuel of different humidity, consisting of a furnace, combustion chamber, heat exchanger, a burner with a hole in the passage from the furnace to the combustion chamber for supplying heated and cold air, an ash collection chamber and a chimney, characterized in that the burner , which starts at the combustion chamber wall and ends at its center, is mounted horizontally on the lower part of the combustion chamber above the grate, and the ash collecting chamber has a damper mounted perpendicular to its lower surface for restricting the air intake from below. 2. A domestic boiler according to claim 1, characterized in that it is possible to push the damper over the entire length of the ash collection chamber by adjusting the parameters of the pyrolysis zone above the grill depending on the fuel type, dispersion and humidity.