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THERMAL DEVICES, DEVICES FOR HEATING LIQUID MEDIA AND THEIR APPLICATION
INVENTION
Patent of the Russian Federation RU2232942

CATALYTIC HEAT GENERATOR AND METHOD FOR REGULATING ITS POWER

The name of the inventor: Simonov AD (RU); Languages ​​N.A. (RU); Vedyakin P.I. (RU); Aflyatunov A.S. (RU); Smolin S.V. (RU); Parmon V.N. (RU)
The name of the patent holder: G.K. Boreskov SB RAS (RU)
Address for correspondence: 630090, Novosibirsk, Acad. Lavrentyeva, 5, Institute of Catalysis named after. G.K. Boreskov, Patent Department, Т.D. Yudina
Date of commencement of the patent: 2003.05.15

The invention can be used in heat supply systems and in the combustion of fuels for heating working bodies, where the combustion of various fuels takes place in a fluidized bed. A catalytic heat source with thermal power adjustment by changing the heat exchange surface in contact with the fluidized bed of the catalyst consists of a vertical casing with air and fuel feeds at the bottom, flue gas fumes and catalyst charge at the top, inside the casing between the air supply and A non-isothermal packing and a heat exchanger are placed in series above the grate, a catalyst discharge pipe and a catalyst charge pipe located above the non-isothermal nozzle are disposed on the housing under the non-isothermal packing, and a gas distribution grid is arranged on which the layer of the granular oxidation catalyst is located; On the case above the non-isothermal nozzle, two or more nozzles for the dispatch of the catalyst may be disposed. A volumetric organizing nozzle with a live cross section of 50-90% with an opening size of 2-15 diameters of catalyst particles and a fraction of free volume in a pack of 85-95% nozzles is placed above the gas distribution grid in front of the non-isothermal nozzle. At the exit of the flue gases, a device is placed against the entrainment of the catalyst particles. To drain water from the heat exchanger, it contains a siphon. The fluid-exchange contacting heat exchange surfaces are located above the non-isothermal lattice. The method for controlling the power of the catalytic heat generator is that the heat output of the heat generator is controlled by changing the amount of catalyst present in the heat generator. The invention makes it possible to develop a catalytic heat generator that efficiently uses heat in the combustion of fuel, ensuring the ecological purity of the exhaust gases and allowing it to regulate its heat output.

DESCRIPTION OF THE INVENTION

The invention relates to heat power engineering and can be used in heat supply systems and in the combustion of fuels for heating working bodies, where the combustion of various fuels occurs in a fluidized bed.

A catalytic heat generator is described in Sect. Scientific works "Technological processes based on catalytic heat generators", Siberian Branch of USSR Academy of Sciences, Catalysis Institute, Novosibirsk, 1985, Fig. 2, p.22, Vedyakin P.I. "Application of catalytic heat generators for water heating and adsorption-contact drying of materials". The known heat generator consists of a casing with nozzles for supplying fuel, air, cold water and hot water and flue gas, and in the lower part of the casing there is a catalyst layer on the gas distribution grid, an intermediate solid heat carrier above which the non-isothermal nozzle Economizer, there is an air cooling jacket on the outer surface of the housing, in addition, a heater in the form of 20 vertical Fild tubes is placed inside the housing in the combustion zone of the fuel. In the heat generator there is a flameless combustion of fuel on the surface of the catalyst pellets that are in a fluidized state.

The design of the heat generator does not allow to achieve environmentally friendly combustion of fuel when operating in the design mode, because Fuel consumption, the amount of liquefied air, the flow rate and the temperature of the heated water are strictly interrelated for this process.

Under real conditions, the water discharge may differ from the calculated one, and the water temperature varies within wide limits. Adjustment of the generator's heat output by changing the water flow rate is impossible, because in heat supply systems, as a rule, the heat output is quantitatively regulated, at which the water flow is kept constant. In addition, a decrease in the flow rate of the heat carrier leads to a simultaneous increase in the temperature of the heated water, which may exceed the boiling point, and the temperature in the combustion zone, which, if the critical value of the catalyst reaches 1000 ° C, will cause its destruction. With an increase in water consumption, the temperature in the combustion zone drops to 700 ° C and lower, which affects the stability of the combustion process and the completeness of combustion.

Adjusting the temperature by changing the air flow rate is unacceptable. The fluidization conditions and the stoichiometric ratio of air and fuel are violated, which causes the formation of harmful emissions.

The Filth tubes immersed in the fluidized bed and removing the major part of the heat can lead to a decrease in the temperature in the combustion zone and, as a result, an increase in CO and NO x emissions.

The closest to the claimed device is the catalytic heat generator described in RF patent No. 2122467, F 23 C 11/02, 10.01.99. The known catalytic heat generator consists of a vertical housing with air and fuel supply nozzles in the lower part, between which a gas distribution grid with a layer of granular oxidation catalyst is placed in the housing, a heat exchanger of U-shaped tubes is placed in the middle of the generator, under which an isothermal nozzle is located, The jacket has a cooling jacket, the jacket is made of water and consists of independent sections operating in parallel and connected in series to the heat exchanger.

The presence of a water sectional jacket on the body above and below the level of the non-isothermal nozzle allows to regulate the amount of heat withdrawn from the combustion zone by turning off or switching on the sections of the water jacket.

The disadvantages of the known catalytic heat generator are:

1. The presence of a water jacket on the body leads to a strong cooling of the catalyst bed in the combustion zone of the fuel and, as a result, an increase in CO and NO x emissions.

2. When a separate section of the shirt is disconnected, its temperature quickly reaches a catalyst bed temperature of 700-800 ° C. If necessary, to increase the power of the heat generator again, the supply of water to this section becomes impossible due to evaporation of water and increase of pressure in the section up to the pressures that cause its destruction.

3. The presence on the body of a water jacket in the combustion zone of fuel makes it difficult or impossible to start the heat generator into operation, because During start-up, the catalyst bed in the combustion zone needs to be heated to a catalytic ignition temperature of 200-400 ° C (the ignition temperature depends on the activity of the catalyst). Due to the jacket, the catalyst bed will be strongly cooled.

The problem solved by the present invention consists in the development of a catalytic heat generator that efficiently uses heat in the combustion of fuel and ensures the ecological purity of the exhaust gases and allows to regulate its heat output.

The problem is solved by the design of the catalytic heat generator with the adjustment of the heat output by changing the heat exchange surface in contact with the fluidized bed of the catalyst. It consists of a vertical hull with air and fuel feeds at the bottom, flue gas discharge pipes and catalyst charge in the upper part, a gas distribution grid is located inside the hull between the air and fuel pipes, on which a layer of granular oxidation catalyst is located, A non-isothermal nozzle and a heat exchanger, a catalyst outlet and a catalyst charge pipe located above the non-isothermal nozzle are disposed on the body under the non-isothermal packing.

On the body above the non-isothermal nozzle, two or more nozzles for the discharge of the catalyst may be disposed.

A volumetric organizing nozzle with a live cross section of 50-90% with an opening size of 2-15 diameters of catalyst particles and a fraction of free volume in a pack of 85-95% nozzles is placed above the gas distribution grid in front of the non-isothermal nozzle.

At the exit of the flue gases there is an anti-entrainment device for the catalyst particles.

To drain water from the heat exchanger, the heat generator contains a siphon.

The heat exchange surfaces contacting the fluidized bed are located above the non-isothermal lattice.

The presence of nozzles for unloading and loading the catalyst makes it possible to change the level of the catalyst in the heat generator during its operation, which makes it possible to change the surface area of ​​the heat exchanger in contact with the catalyst and, consequently, to change the heat output of the heat generator without changing the air flow rate, water to the heat exchanger and maintaining the optimum Temperature in the combustion zone of fuel 700-800 ° C.

The task is also solved by a method for controlling the power of the above-described catalytic heat generator, which is carried out by changing the amount of catalyst in the heat generator.

The figure shows a diagram of a catalytic heat generator.

CATALYTIC HEAT GENERATOR AND METHOD FOR REGULATING ITS POWER

The heat generator consists of a vertical casing (1), in which air supply sections (a), combustion (b), heat sink (c) and separation zone (d) are located. The air supply section (a) consists of a chamber with an inlet (6) for air injection and is designed to distribute air evenly over the cross-section of the gas distribution grid (4), and in the case of lateral air intake, in addition to changing the direction of the air flow by 90 °.

The combustion section (b) is separated from the air supply section by a gas distribution grate (4) and has nozzles for supplying a gaseous (24) or liquid (8) or solid fuel (7), a branch pipe with a valve or a catalyst discharge gate (14). In addition, in the combustion section above the gas distribution grid, a volumetric organizing nozzle (9) is placed in front of the non-isothermal packing (10), for example, from wire gratings, with a live cross section of 50-90%, with apertures of 2-15 diameters of catalyst particles and a free volume fraction in the lattice packet 85-95%.

The heat sink section (c) consists of a heat exchanger (3) and a volumetric non-isothermic nozzle (10) placed under the heat exchanger above the organizing nozzle. The design parameters of the nozzle (10) exceed the parameters of the organizing nozzle by 1.5-2 times. The nozzle (10) can be made of wire gratings. In the heat sink section there is a cold water inlet (11), a hot water outlet (12), a siphon (18) with a valve for draining water from the heat exchanger during a heat generator stop at outdoor temperatures below 0 ° C. It is also possible to install one or more nozzles (15), (16), (17) with valves or shutters to unload the catalyst.

The separation zone (d) is located at the top of the heat generator and has a branch pipe (5) for flue gas outlet, a branch pipe with a valve or shutter (13) for catalyst overload, a catalyst filler pipe (2), a safety diaphragm (21).

The catalytic heat generator works as follows. In the heat generator through the pipe (2), the catalyst is loaded, the amount of which corresponds to the maximum power of the heat generator. The air along the branch pipe (6) is fed into the air supply section (a), passes the gas distribution grid (4) to the combustion section (b), where fuel (gas or liquid or solid fuel is supplied through the nozzles (24) or (8) or (7) ).

The catalyst particles (22) are fluidized by the upward flow of air and flue gases. In the combustion section, heat is generated by the combustion of fuel on the catalyst. The large gas bubbles containing air and fuel, formed due to the fusion of small bubbles, are again broken into small ones on the organizing nozzle (9), which intensifies the burning of fuel and the completeness of its combustion.

The hot flue gases and catalyst pass through the non-isothermal nozzle (10) to the heat sink section, where heat is transferred to the heat exchanger and cooled. The cold catalyst returns to the combustion zone. The main amount of heat released during the combustion of fuel in the combustion section is transferred to the heat removal section by the catalyst particles. The non-isothermal nozzle brakes the rate of rise of the catalyst particles to the heat-sink section, which allows maintaining the optimum combustion temperature in the combustion section at 700-800 ° C, and in the heat-sink section, a temperature of 300-600 ° C, optimal for ensuring maximum heat transfer coefficients from the fluidized bed to the heat exchange surfaces. Further, the flue gases pass through the separation zone and the anti-entrainment device of the catalyst (23), which is a grid with a cell smaller than the particle size of the catalyst. Heat removal takes place through the surface of the heat exchanger (3) immersed in the fluidized bed. The removal of heat from flue gases occurs through a surface located in the superlayer space of the separation zone or on an additional heat exchanger installed outside the heat generator. The water enters the heat exchanger through a branch pipe (11) with a temperature of 40-60 ° C and exits the heat exchanger (3) at a temperature of 80-100 ° C.

Automatic control of the temperature in the combustion zone of the fuel (b) and the temperature of the hot water at the outlet (12) from the heat generator is carried out by switching off and switching on the fuel supply. When the maximum temperature of hot water, for example, 95 ° C and the temperature in the combustion zone of the fuel, for example 800 ° C, is reached, the fuel supply is cut off. When the temperature in the combustion zone drops below 800 ° C and the water temperature drops below 90 ° C, the fuel supply switches on. The decrease in the temperature of the layer occurs fairly quickly. The decrease in the temperature of the hot water (12) occurs more slowly and, therefore, the regulation of the operation modes of the heat generator is usually carried out depending on the temperature of the hot water, i.e. Fuel supply is only turned on after the water temperature drops to 90 ° C. In this case, the temperature of the layer in the combustion section may drop below 700 ° C.

At the maximum power consumption of heat in the heating system corresponding to the maximum power of the heat generator, usually the temperature in the combustion section is kept within 700-800 ° C when the temperature of hot water varies within 5-10 ° C. However, as the heat sink is reduced in the heating system, for example, due to the increase in the outside air temperature, the temperature of the return water (11) is higher than the regulated temperature of 40-60 ° C. This leads to an increase in the time interval between switching off and on the fuel supply to the combustion section and, as a consequence, to lower the temperature in the combustion section is substantially below 700 ° C. In turn, a decrease in the temperature in the combustion section below 700 ° C leads to a decrease in the completeness of fuel combustion and an increase in CO and NO x emissions with flue gases.

In the claimed catalytic heat generator, when the return water temperature (11) rises above the limit temperature, a valve or valve opens on the branch pipe (14), and a part of the catalyst is discharged from the heat generator, for example, into a hopper (19). This leads to a decrease in the surface of the heat exchanger (3) immersed in the fluidized bed and a decrease in the power of the heat generator. As a consequence, the time interval between switching on and switching off the fuel supply to the combustion section is reduced and the temperature in the combustion section is kept within 700-800 ° C. In the presence of an automatic level gauge on the hopper (19), the amount of catalyst shipped strictly corresponds to the value of the return water temperature (11). In the absence of a level gauge, the catalyst is shipped from the heat generator stepwise by gravity through the pipes (15) or (16) or (17), etc. By opening the valves or dampers in accordance with the value of the return water temperature (11). In this case, the calibration of the heat generator power corresponding to the return water temperature (11) is carried out beforehand at commissioning.

The reverse increase in the power of the heat generator with increasing heat dissipation in the heating system and a decrease in the return water temperature (11) at the inlet to the heat exchanger (3) is carried out in the following order: air is fed to the ejector (20) and the valve on the branch pipe (13) opens. If there is an automatic level gauge on the hopper (19), the required quantity of catalyst corresponding to the return water temperature (11) is loaded in the heat generator. In the absence of a level gauge, the loading is carried out to the level of the closed nozzle (17), (16), (15).

The task is also solved by a method for controlling the power of the catalytic heat generator, characterized in that the adjustment of the heat output of the heat generator of the above-described structure is carried out by changing the amount of catalyst present in the heat generator.

The table shows the change in the heat output of an industrial heat generator running on liquid fuel, depending on the amount of the catalyst shipped. The total amount of loaded catalyst is 150 kg.

Thus, the claimed heat generator provides a stable temperature in the combustion zone of the fuel with a change in its power and ensures environmentally friendly combustion of various fuels at the maximum efficiency of 0.93-0.96.

CLAIM

1. A catalytic heat source with thermal power adjustment by changing the heat exchange surface in contact with the fluidized bed of the catalyst, consisting of a vertical housing with air and fuel feeds at the bottom, flue gas discharge pipes and catalyst charge in the upper part, inside the housing between supply pipes Air and fuel there is a gas distribution grid on which a layer of granular oxidation catalyst is located, a non-isothermal packing and a heat exchanger are arranged in series above the grate, characterized in that a catalyst discharge pipe and a catalyst charge pipe located above the non-isothermal packing are disposed on the housing under the non-isothermal packing.

2. The catalytic heat generator according to claim 1, characterized in that two or more catalyst discharge ports are arranged on the body above the non-isothermal nozzle.

3. A catalytic heat generator according to any one of claims 1 and 2, characterized in that a volumetric organizing nozzle with a live cross section of 50-90% is placed above the gas distribution grid in front of the non-isothermal nozzle with apertures of 2-15 diameters of catalyst particles and a fraction of the free volume in the nozzle pack 85-95%.

4. A catalytic heat generator according to any of the preceding claims. 1-3, characterized in that at the outlet of the flue gases there is placed an anti-entrainment device for the catalyst particles.

5. A catalytic heat generator according to any of the preceding claims. 1-4, characterized in that for draining the water from the heat exchanger, it contains a siphon.

6. A catalytic heat generator according to any of the preceding claims. 1-5, characterized in that the heat exchange surfaces contacting the fluidized bed are located above the non-isothermal lattice.

7. A method for controlling the power of a catalytic heat generator, characterized in that the control of the heat output of the heat generator according to any one of 1-6 is carried out by changing the amount of catalyst present in the heat generator.

print version
Date of publication 31.12.2006гг