Method of heating heat carriers in boiler-smoke stack and boiler-smoke stack device

Abstract

FIELD: power engineering.SUBSTANCE: design of boilers for heating liquid heat carriers, combining the functions of a boiler and a chimney in a single design, which can be used in industrial and municipal boiler installations. In a smoke stack boiler comprising a boiler with a furnace, a smoke stack located above the boiler, the smoke stack is made of at least two shells inserted into each other to form a coaxial gap, wherein the walls of the inner shell have high thermal conductivity and are a vertical gas exhaust shaft, and the walls of the outer shell have low thermal conductivity. The boiler furnace is made with a heat-insulating shell that forms a gap with the walls of the furnace, while the gap between the heat-insulating outer shells of the chimney and the furnace, as well as between the inner shell of the chimney and the walls of the furnace, forms a recuperative air duct. Heat exchangers for liquid coolant are located with the possibility of heating the coolant in the furnace during fuel combustion and in the inner lining of the chimney from hot flue gases. The invention also relates to a method for heating heat carriers in a boiler-smoke stack, including supplying air into the furnace through a recuperative air duct with its heating first in the coaxial gap of the smoke stack, and then in the gap between the furnace and the outer heat-insulating shell. The liquid coolant is heated first in the furnace during fuel combustion, and then in the inner lining of the chimney from hot flue gases.EFFECT: simplified design and operation by combining the functions of the boiler and chimney, increased efficiency, and a reduction in the weight and dimensions of the device.3 cl

Description

[0001] I. Scope of use

[0002] The invention relates to thermal power engineering and can be used in the creation of explosion-proof boiler houses, including high-power ones with higher efficiency and without the use of buildings.

[0003] II. Technique level.

[0004] In all boilers that use fuel combustion, a gas flow path runs through the entire boiler, which:

[0005] - starts from the air intake point;

[0006] - passes through the firebox;

[0007] - further - through chimneys or gas ducts;

[0008] - ends at the exit of the chimney.

[0009] Terminology:

[0010] The section of the gas flow path from the boiler to the outlet of the chimney is called the gas exhaust path.

[0011] The section from the boiler to the chimney is called:

[0012] chimney - for small boilers;

[0013] gas duct - for large boilers.

[0014] The boiler liquid heat carrier heating system consists of radiation and convective heating surfaces - heat exchangers.

[0015] The main initial parameter for boiler calculations is the "particle dwell time" in the heat transfer zone from the particle to the heating surfaces or other heated medium in a specific section of the gas flow path. The higher the "particle dwell time," the higher the boiler efficiency.

[0016] To increase the “dwell time of particles,” the gas removal path in the boiler itself is made with turns.

[0017] The higher the resistance of the gas flow path, the lower the efficiency of the boiler.

[0018] Analysis of known technical solutions

[0019] 1. Outdoor condensing boiler (Application: 2012137842 / 06, 04.09.2012)

[0020] Design:

[0021] - a housing with the main heat exchanger located inside;

[0022] - blast burner;

[0023] - forward and reverse lines;

[0024] - chimney pipe;

[0025] - coaxial chimney, in the cylindrical part of which the main heat exchanger is installed;

[0026] - additional heat exchanger installed in a coaxial chimney and connected in parallel with the main one.

[0027] Disadvantages:

[0028] - the presence of direct and return lines leads to the need for turns and reversals of the flow in the boiler, which increases the aerodynamic resistance of the tract;

[0029] - the flue gas duct from the firebox to the chimney contains many turns;

[0030] - Flow turns increase the aerodynamic resistance of the gas exhaust tract, which leads to increased energy consumption for the operation of fans and smoke exhausters;

[0031] - bends in the tract act as blast wave reflectors: in the event of an explosion in the furnace, the blast wave is reflected back into the furnace, and does not go directly into the chimney;

[0032] - due to the risk of blast wave reflection, the furnace body has to be made more durable, which increases manufacturing and installation costs.

[0033] 2. Tower boiler PTVM-50 of the Barnaul power equipment plant (the closest analogue)

[0034] Design Features:

[0035] - the flue pipe is installed directly on the boiler (there are no chimneys / gas ducts);

[0036] - total height of the structure - 55 m (boiler height - 15 m, chimney height - 40 m);

[0037] - presence of heat-insulating lining. Disadvantages:

[0038] - the lining significantly increases the weight of the boiler;

[0039] - an increase in the mass of the lining leads to the need to increase the strength of the supporting frame;

[0040] - the overall increase in the boiler weight requires an increase in the foundation support area;

[0041] - the increase in the mass of the entire structure increases the cost of manufacturing and installation of the boiler;

[0042] - from the total height (55 m) only 15 m remains for heat transfer, which significantly reduces the “particle hovering time” parameter;

[0043] - as a result, the efficiency of the PTVM-50 boiler is below 90%.

[0044] State of the art conclusion

[0045] Analysis of known solutions shows that existing boiler designs have the following disadvantages:

[0046] - turns in the gas flow path (including in a condensing boiler):

[0047] - create aerodynamic drag;

[0048] - increase energy consumption for the operation of fans and smoke exhausters;

[0049] - serve as reflectors of the blast wave, which requires strengthening the strength of the furnace body.

[0050] - solid lining (in the PTVM-50 boiler):

[0051] - increases the mass of the structure;

[0052] - requires strengthening the supporting frame and expanding the foundation;

[0053] - leads to an increase in the cost of manufacturing and installation.

[0054] Low heat transfer efficiency (in PTVM-50):

[0055] - low height of the heat transfer zone relative to the overall height of the structure;

[0056] - reduced parameter “particle hovering time”;

[0057] - Efficiency below 90%.

[0058] These shortcomings necessitate the development of a new technical solution to eliminate them.

[0059] III. The Problem of the Invention

[0060] The objective of the invention is to eliminate the shortcomings of known solutions and to create a method for heating heat carriers and a boiler-smoke stack design that ensure:

[0061] - increasing efficiency by increasing the time particles spend in the heat transfer zone;

[0062] - reducing the aerodynamic resistance of the gas removal tract;

[0063] - ensuring explosion safety due to direct-flow vertical discharge of the blast wave without turns;

[0064] - simplification of design and reduction of manufacturing and operating costs;

[0065] - reducing energy costs for the operation of fans and smoke exhausters.

[0066] The set objective is achieved by combining the functions of the boiler and chimney in a single design with a straight-through gas flow path and recuperative air heating.

[0067] IV. DISCLOSURE OF THE INVENTION

[0068] The essence of the invention is that the chimney performs the functions of a boiler, and the gas flow path is straight-through and vertical, without turns.

[0069] This allows you to:

[0070] 1. Increase the particle hover time by using the entire height of the structure for heat transfer (unlike the PTVM-50, where only 15 m of the 55 m are left for heat transfer).

[0071] 2. Reduce aerodynamic resistance due to the absence of turns in the gas flow (unlike a condensing boiler with many turns in the chimney).

[0072] 3. Ensure explosion safety by vertically diverting the blast wave upward without reflections from bends (unlike boilers with multi-pass flues).

[0073] 4. Implement recuperative air heating due to the coaxial gap between the chimney shells and the gap between the firebox and its heat-insulating shell.

[0074] 5. Reduce the weight and cost of the structure by eliminating the massive lining (unlike PTVM-50) and using shells with different thermal conductivities.

[0075] The technical result is achieved by the following features:

[0076] - combining the functions of a boiler and a chimney;

[0077] - straight-through vertical gas flow path without turns;

[0078] - a recuperative air duct formed by a coaxial gap between the shells of the chimney and the gap between the firebox and its shell;

[0079] - using the inner shell of the chimney as a gas exhaust shaft with high thermal conductivity;

[0080] - using an outer shell with low thermal conductivity to reduce heat loss;

[0081] - building explosion valves into the walls of the chimney to improve safety.

[0082] VI. Static state (device)

[0083] The chimney boiler structure is a single vertical structure in which the chimney acts as a boiler.

[0084] Main elements of the device:

[0085] 1. Firebox with a burner device for burning fuel;

[0086] 2. Inner lining of the chimney:

[0087] - made of material with high thermal conductivity;

[0088] - functions as a vertical gas outlet barrel;

[0089] - serves as a heat transfer surface for heating the liquid coolant in the second stage of the process.

[0090] 3. The outer shell of the chimney is made of low thermal conductivity material, which reduces heat loss to the environment.

[0091] Coaxial gap between shells:

[0092] - forms part of the recuperative air duct;

[0093] - provides preheating of air due to heat transfer from flue gases through the wall of the inner shell.

[0094] Heat-insulating shell of the firebox:

[0095] - surrounds the firebox, creating a gap;

[0096] - prevents heat loss from the firebox to the environment;

[0097] - participates in the formation of the recuperative air duct.

[0098] Gap between the walls of the firebox and its heat-insulating shell:

[0099] - is a part of the recuperative air duct;

[0100] - provides additional air heating before entering the furnace. Heat exchangers for liquid coolant:

[0101] - located in two zones: in the firebox and in the inner lining of the chimney;

[0102] - provide two-stage heating of the coolant.

[0103] Explosion valves:

[0104] - built into the walls of the inner casing of the chimney;

[0105] - placed evenly along the height of the pipe;

[0106] - designed to relieve excess pressure in emergency situations.

[0107] Fan:

[0108] - installed in the lower or upper part of the gas outlet barrel;

[0109] - provides forced draft when needed.

[0110] Design features:

[0111] - absence of chimneys / gas ducts between the boiler and the chimney;

[0112] - straight-through vertical gas flow path without turns;

[0113] - Coaxial flue structure with gap for heat recovery;

[0114] - integration of boiler and chimney functions in a single design.

[0115] VII. Dynamic state

[0116] The process of heating the coolant is carried out as follows:

[0117] Step 1. Air supply and heating:

[0118] 1. Air enters the recuperative air duct formed by:

[0119] - coaxial gap between the inner and outer shells of the chimney;

[0120] - the gap between the firebox and its heat-insulating shell.

[0121] 2. The air is heated sequentially:

[0122] - first in the coaxial gap due to heat transfer from hot flue gases through the wall of the inner shell of the chimney;

[0123] - then in the gap between the firebox and its shell.

[0124] 3. Preheated air is supplied directly to the firebox, which improves the combustion process and reduces fuel consumption for heating the supplied air.

[0125] Stage 2. Combustion and heating of the coolant:

[0126] 1. Fuel combustion occurs in the firebox, releasing thermal energy.

[0127] 2. The liquid coolant is heated through heat exchangers in the furnace - this is the first stage of heating.

[0128] 3. Flue gases generated during combustion enter the inner lining of the chimney.

[0129] Stage 3. Heating of the coolant and gas removal:

[0130] 1. In the inner lining of the chimney the following occurs:

[0131] - heat transfer from flue gases to the wall of the inner shell;

[0132] - heating of the liquid coolant through heat exchangers located in the inner shell - the second stage of heating.

[0133] 2. Flue gases are removed in a straight-through manner into a vertical gas exhaust shaft (inner shell).

[0134] 3. The movement of gases in the barrel is ensured by:

[0135] - natural draft (due to the difference in temperature and pressure);

[0136] - and / or forced by a fan.

[0137] Step 4. Ensuring security:

[0138] 1. In case of an emergency (e.g. explosion in the furnace):

[0139] - the blast wave is directed vertically upward along a straight-through path without reflections;

[0140] - when the permissible pressure is exceeded, the explosion valves are automatically triggered, releasing excess pressure into a safe area.

[0141] Technical results achieved:

[0142] - Increasing efficiency to 95% or more is achieved due to:

[0143] - increasing the time of particles hovering in the heat transfer zone;

[0144] - two-stage heating of the coolant;

[0145] - flue gas heat recovery for air heating.

[0146] - The reduction of energy consumption for traction by 20-30% is ensured by the absence of aerodynamic resistance from turns.

[0147] - Explosion safety is ensured by direct-flow blast wave removal and the presence of explosion valves.

[0148] - Simplification of the design and reduction of manufacturing and operating costs is achieved by combining the functions of the boiler and chimney.

Claims

1. A method for heating heat carriers in a boiler-smoke stack, including: - combustion of fuel in the firebox; - heating of the liquid coolant through the surface of heat exchangers; - removal of flue gases into a vertical gas exhaust shaft, characterized in that: - air is supplied into the furnace through a recuperative air duct formed by a coaxial gap between at least two shells of the chimney, wherein the walls of the inner shell have high thermal conductivity and perform the function of a vertical gas exhaust shaft, and the walls of the outer shell have low thermal conductivity, and a gap between the walls of the furnace and its heat-insulating shells; - the supplied air is heated first in the coaxial gap of the chimney due to the transfer of heat from the hot flue gases through the walls of the inner shell, then in the gap between the firebox and the outer heat-insulating shell; - preheated air is supplied directly to the firebox; - the liquid coolant is heated first in the firebox during fuel combustion, and then in the inner lining of the chimney from hot flue gases; - the movement of gases in the gas exhaust shaft is carried out by natural draft and / or forced by a fan.

2. A boiler-smoke stack containing: - boiler with firebox; - a chimney located above the boiler, characterized in that: - the chimney is made of at least two shells inserted into each other to form a coaxial gap, wherein the walls of the inner shell have high thermal conductivity and are a vertical gas exhaust shaft, and the walls of the outer shell have low thermal conductivity; - the boiler firebox is made with a heat-insulating shell that forms a gap with the walls of the firebox; - the gap between the heat-insulating outer shells of the chimney and the firebox, as well as between the inner shell of the chimney and the walls of the firebox forms a recuperative air duct; - heat exchangers for liquid coolant are located with the possibility of heating the coolant in the firebox during fuel combustion and in the inner lining of the chimney from hot flue gases.

3. A boiler-smoke stack according to paragraph 2, characterized in that explosion valves are built into the walls of the smoke stack.