RU2196933C2 - Hot-water boiler - Google Patents

Abstract

FIELD: power engineering; regeneration of thermal energy by means of catalytic heating elements working on principle of flameless oxidation of natural gas; autonomous water heating systems and continuous hot water supply for domestic and industrial buildings. SUBSTANCE: hot-water boiler includes furnace unit provided with tubular cylindrical or oval heating catalytic element provided with two sleeves which are extension of tubular structure with layer of catalyst located on surface of tubular structure and sleeves; it is made in form of gas permeable flat and corrugated reinforced tapes wound and sintered with tubular structure and sleeves at spaced relation between turns forming gas-and-air passages between tapes. Used as catalyst is reinforced porous material containing the following active components: Co₃O₄, CuO, Cr₂O₃, Fe₂O₃, Al₂O₃, metals of group VIII secured on metal carriers by means of Ti-Al, Ni-Al, Ni-Cr and Ti-Si alloys. Proposed hot-water boiler may be used for employing catalytic oxidation principle, thus ensuring ecologically pure oxidation of hydrocarbon gases. EFFECT: enhanced efficiency. 8 cl, 3 dwg

Description

 The invention relates to energy, to a technique for generating thermal energy using catalytic heating elements operating on the principle of flameless oxidation of natural gas, and can be used for autonomous water heating and year-round hot water supply for domestic and industrial premises.

It is known that for local heating of rooms using water heating, gas-fired boilers with traditional flame burners are used [MB. Ravich, "Gas and the efficiency of its use in the national economy." Publishing house "Nedra", 1987, p.238]. AKGV-23.2-1 gas household heating apparatus with forced circulation (combined household gas apparatus with a water circuit, JSC Zhukovsky Machine-Building Plant) have a water circuit for heating a room 140-1200 m ² , a shunt circuit for hot water supply, a system maintain the set temperature in the room, equipped with an electronic control unit that ensures the safety of operation and control of the boiler, are located in an isolated part of the house. No emission data.

Sibiryak family of boilers (ГЦО-29-06 / Е "Sibiryak", thermal power - 29 kW, ГЦО-19.8-4 / Е "Sibiryak-M. 19.8 kW, ГЦО-10-15 / Е Sibiryak-N, 10 kW. ГЦО-29-08 / Е Sibiryak-2, 29 kW, Sibgazpribor CJSC) with forced circulation of hot water heat rooms from 100 to 300 m ² , have traditional electronic control units and allow wall or floor location with exhaust gas off-site. The heating center in the firing unit is a standard injection burner equipped with thermal automation. Exhaust gases contain: СО 119 mg / m ³ , NO _X 144 mg / m ³ . The disadvantage of these boilers is the high concentration of harmful emissions and only a low price relative to foreign companies ensures their sales.

The company "Vaillant" (Germany) produces all types of boilers based on one- or two-stage atmospheric burners with heat-removing ceramic rods in three types: international, for Germany, for Eastern Europe [Price list 2000. Part 1, part 2 ]. The condensing wall-mounted gas boiler VU 506 E (109% efficiency, rated power range 13.8-46.0 kW) has NOx ≤20 mg / kW • h (41 mg / m ³ ). Gas heating boilers VK INT KLASSIK 15 / Kl EH ... 45 / K-1 ЕН (20.9-47.3 kW, weight 120-195 kg) have Nox≤70 mg / kW • h in the exhaust gases (59, 5 mg / m ³ ). Boilers with a two-stage atmospheric burner VK 60 / 7-2EH ... 156 / 7-2EN (20.9-47.3 kW, 93% efficiency), boilers VKO 22 / 3-70 / 3 (17 , 0-70.0 kW, efficiency 94%) and gas cylinder water heaters VGH 130 / 5X2 also have NOx≤80 mg / kW • h (165 mg / m ³ ) in the exhaust gases. As can be seen from the above data, Vaillant boilers have the same emission disadvantages as the boilers discussed above.

 Mounted automatic boilers from Buderus (Czech Republic), Lamborgini (Italy) with a capacity of up to 25 kW (94-95% efficiency) have close emissions values, like the boilers of the German companies considered. For environmental reasons, the Protherm company (Czech Republic), which produces relatively light (70 kg) boilers (50 kW), equips mini-boilers in basements or on the roofs of houses, using a cascade of several devices. Cascading boiler houses allow you to disconnect from district heating, reducing gas consumption by 20-50%, however, they do not solve the problem of suppressing NOx and CO emissions.

 The main drawback of all the boilers discussed above is the use of one of six types of burners in them: 1) a traditional atmospheric burner (CO emissions ≤35 ppm, NOx≤320 ppm), 2) a simple distributed burner (СО≤25 ppm, NOx≤250 ppm) , 3) a supercharged burner (СО≤20 ppm, NOx≤185 ppm), 4) an optimized distributed burner (СО≤18 ppm, NOx≤170 ppm), 5) a fully pre-mixed burner (СО≤15 ppm, NOx ≤110 ppm), 6) a burner with ventilation pressurization and a cylindrical (spherical) combustion surface (СО≤10 ppm, NOx≤60 ppm) [TB Jannemann. The Development of Atmospheric Burners with Respect to the Increasing Emissions Restrictions. In: Proceedings of the First European Conference on Small Burner Technology and Heating Equipment. Zurich, September 25-26, 1996, v. 1, p. 23-34].

The company "Viessman" (Germany) produces a wide range of gas boilers for liquid and gaseous fuels with both traditional atmospheric burners and radiative Matrix compact [Vitotec Price List 2000 GUS Viessman]. Low-temperature boilers "Vitogas-100" with ranges of rated thermal power 11-60, 72-144 kW, have an economical mode of weather-dependent heat transfer of the coolant, efficiency up to 92%, equipped with an atmospheric pre-mixing burner and give emissions: NOx≤50 mg / kW • h (103 mg / m ³ ), СО≤10 mg / kW • h (4.8 mg / m ³ ). Gas-fired boilers Vitola 100. ..200 (15-63 kW), Vitorond 200 (15-33 kW), Vitopend 100 (10.5-24 kW), gas condensate modules Vitodens 100 ( 8-18 kW) have water-cooled modulated burners with regulation of mixture formation or infrared burners (stainless steel emitter) with a level of emission of harmful emissions below the environmental standard "Blue Angel". Due to the utilization of the latent heat of condensation, the normative efficiency boiler increases to 106%. Eurola wall-mounted boilers use modulated matrix radiation-catalytic burners that provide nitrogen and carbon oxides with NOx ≤9 mg / kW • h (18.5 mg / m ³ ), CO ≤17 mg / kW • h (8.2 mg / m ³ ) [Ein echter Heizkessel fur die Wand extrem schadstoffarm durch Matrix-Strahlungsbrenner. Viessman company ad for Eurola boiler]. The maximum power control range is 1: 2.25, the mass of the boiler per kilowatt of generated power is about 3-5 kg / kW.

 The Eurola-kat boiler, selected as a prototype, with a catalytic coated layer of a matrix burner and a spherical heating surface made of stainless steel, has an efficiency of 108% due to the condensation stage. The volume of the water circuit of 30 l allows you to compensate for fluctuations when heating the coolant. It is equipped with an electronic control unit with an integrating diagnostic system. Only 8-11 kW is used for space heating, 24 kW for drinking water heating. Overall dimensions 415 • 560 • 900 mm. Despite the high level of automation and high efficiency Viessman boilers, the presence of unrecoverable emissions of nitrogen oxides inherent in atmospheric burners, imposes environmental restrictions on their use indoors.

 The invention solves the problem of creating a hot water boiler with a capacity of 25 kW, in the exhaust gases of which the CO content is not more than 10 ppm, methane not more than 30 ppm, nitrogen oxides are absent.

 The problem is solved by creating the design of the KGK-25 hot water boiler (gas catalytic boiler with a power of 25 kW), containing a frame in which all the node assemblies of the boiler are located: furnace block, consisting of a catalytic burner, heat exchanger, ignition unit; control unit and control system of boiler operation modes. As a burner, it contains a catalytic heating element containing a tubular structure of a cylindrical or oval shape, and two glasses serving as a continuation of the tubular structure, with a catalyst layer located on the surface of the tubular structure and glasses, a gas distribution device with a gas-air mixture supply unit, an inlet and outlet point cooling water.

 The catalyst in the catalytic heating element is made in the form of gas-permeable flat and corrugated reinforced tapes, wound and sintered with a tubular structure and glasses, with gaps between the turns with the formation of gas-air channels between the tapes, the outer catalyst layer has a corrugation size larger than the critical size of the channels for the flame to enter the layer of the catalyst, the width of the catalyst layer in the catalytic heating element exceeds the width of the tubular structure by the width of the glasses, untied thermal contact with the catalyst bed.

The gas distribution device in the catalytic heating element comprises one or more perforated gas distribution pipes with perforation holes smaller than the critical diameter for the flame to enter the gas distribution pipe, and a jets flowing out of the perforation holes. The tubular structure in the catalytic heating element is made in the form of a water-cooled tubular heat exchanger. A reinforced porous material containing Co ₃ O ₄ , CuO, Cr ₂ O ₃ , Fe ₂ O ₃ , Al ₂ O ₃ , Group VIII metals fixed on metal supports with alloys as the active components is used as a catalyst in the catalytic heating element Ti-Al, Ni-Al. Ni-Cr, Ti-Si.

 The fuel used is natural gas, a propane-butane mixture, refinery off-gas, flare gas, etc.

The boiler KGK-25 (figure 1) is made in the form of a frame 1, to which all the node assemblies of the boiler are attached:
- furnace block 2, which consists of a catalytic heating element with a rated power of 25 kW (Fig.2), a heat exchanger, an ignition and flame control unit, a ventilation unit;
- control panel 3;
- expansion tank;
- manostat;
- air boost unit 4;
- electromagnetic valve 5;
- automatic three-way valve 6;
- pointer "Pressure"7;
- pointer "Temperature"8;
- automatic purge valve,
- gas valve 9;
- limit pressure sensor;
- overheating sensor for heating water;
- temperature sensor;
- temperature sensor;
- inlet crane;
- safety valve;
- heat exchanger technical water 10;
- circulation pump 11;
- pipelines 12;
- walls left, right and front 13;
- front wall 14;
- viewing window 15.

 In FIG. 2. A catalytic heating element is presented, which is a tubular cylindrical or oval construction, consisting of a tubular ring-type heat exchanger 1, inside of which there is a gas distribution device, which is one or more perforated pipes 2, into which a gas-air mixture is supplied. Around the gas distribution pipe for better gas distribution and suppressing the speed of the jets flowing from the hole, a divider 3 is located. The catalyst 4 in the form of flat 5 and corrugated 6 ribbons is wound onto the tubes of the heat exchanger 1 and sintered with them. The catalyst layer exceeds the width of the tubular heat exchanger by the size of the glasses, decoupled by heat from the collectors 8 of the heat exchanger. To supply cold water and drain the heated device is equipped with fittings 9 and 10, respectively. To improve the dynamic characteristics of the heating element, the outer catalyst layer 11 has a corrugation size larger than the critical size of the channels for flame penetration into the porous structure.

 It is envisaged that the boiler should work in two modes: "Winter" and "Summer". In the "Summer" mode, the boiler provides the consumer only with technical warm water, and in the "Winter" mode - heating water. The operating circuit of the boiler is shown in FIG. 3. After connecting the exhaust pipe, connecting the heating batteries and filling the heating circuit with water (pH≤7, soft), attaching the gas and technical water lines, and supplying electric energy, the KGK-25 boiler is ready for operation.

 When the boiler is turned on by setting the switch "1" - "0" to the "1" position on the automatic control unit, the unit self-tests and checks the state of the boiler, after which, in case of a positive test result, the inscription on the device displays: "Everything is OK, you can turn it on" .

After pressing the "Start" button, the automatic control unit turns on the exhaust fan 2 and the boost system fan 8, the electric spark ignition system 15 of the ignition burner 7, the circulation pump 10 and the solenoid valve of the ignition burner 14 opens. flame on the ignition burner after 5 with the control unit, the main gas valve and the modulator in the gas valve 9. opens. Gas is supplied to the mixing chamber of the charge unit VA and ignites on the surface of KNE-25 4. At the same time, high voltage is removed from the ignition electrodes. 15 seconds after the mixture is fed to the KNE-25, the electromagnetic valve is turned off, the gas supply to the ignition burner stops. The surface temperature of KNE-25 rises to a temperature of 500 ^o C for up to 300 s, after which the catalytic process of gas oxidation begins. KNE is heated to an operating temperature of 750-850 ^o C and begins the nominal mode of operation of the boiler. When the boiler KGK-25 enters the operating mode, a message about the temperature on the surface of KNE-25 appears on the information board.

After turning on the circulation pump 10, water from the heating system, filled under pressure of 1.5-2.0 kg / cm ² , is supplied to the internal water-cooled KNE heat exchanger, then to the pre-heating heat exchanger 27, then to the boiler heat exchanger 3 and through a three-way valve 16 and pipe 21 to the heating system and returns through pipe 25 again to the KNE-25 internal water-cooled heat exchanger. The resulting exhaust gases are sucked off by the fan 2 and are removed from the room through the axial pipe 28.

 Air supply to the mixing chamber is carried out by the fan of the mixing and discharge unit 8 through an axial pipeline from the environment. Possible residual air in the boiler is pushed out by the pump through the purge valve 6. The boiler has a built-in expansion vessel with a membrane 5 with a nominal volume of 10 l. To obtain hot technical water, the water supply from the main is opened through the pipe 22, while using the valve 16 the water supply to the heating system is turned off and it is supplied to the technical water heater 18. The technical water passing through the coil is heated and supplied to the consumer through the pipe 23. The operation of the boiler and safety is controlled by a digital system, which is built on the basis of a microcontroller and provides connection and processing of sensors: manostat 1 (exhaust presence sensor), water pressure in the heating system, water flow, the presence of a flame on the ignition burner, KNE temperature, temperature heating water. The digital system provides connection and control of executive devices: the solenoid valve of the ignition burner, electric spark ignition of the ignition burner, gas valve, modulator of gas flow of the gas valve, the fan of the discharge unit into the mixing chamber.

 The boiler KGK-25 is switched off by pressing the "Off" button on the boiler control panel. At the same time, the gas valve is turned off, which shuts off the gas supply to the mixer, KNE-25 starts to cool. For 5 minutes, the pressurization unit, the ventilation unit and the centrifugal pump continue to work, which ensures protection of the KNE-25 from destruction. The message "The gas boiler is shutting down" appears on the information panel of the control panel and, if all the nodes meet their requirements, the message "Everything is OK, you can turn it off" appears. According to this message, the KGK-25 boiler is de-energized by setting the switch "1" - "0" to the "0" position.

In all operating modes, in case of exceeding critical values of the boiler parameters: KNE-25 temperatures above 880 ^o C or below 550 ^o C, heating water pressure below normal, failure of ventilation units, pressurization by the control system, the gas supply is shut off, the "Alarm" indicator turns on and the LCD displays a message about the cause of the emergency shutdown.

 The KGK-25 boiler is made in the wall version.

Example 1. The gas catalytic boiler KGK-25 has the overall dimensions, mm:
- height - 1290;
- width - 567;
- length - 730.

 Mass of a copper, kg, no more than 70.

Natural gas of the composition, (% vol.) Is supplied to the KGK-25 boiler: methane 97.46, ethane 1.11, propane 0.37, disobutane 0.06, butane 0.06, pentane 0.02. Nominal expense, (nm ³ / hour): gas 2,46; air 27.06, gas-air mixture 29.52; heating water 0.48, Pressure: gas-air mixture at the inlet to the boiler 1000-2000 Pa; water in the heating system 1.8 kg / cm ² . The volume of water in the heating system is 130 ± 10 l.

As a result of the operation of the boiler:
- time to reach the nominal mode, sec - 290;
- rated heat output, kW - 25 ± 2.5;
- surface heating temperature KNE-25, ^o С - 750-830;
- temperature of heating water, ^o С - 90-95;
- productivity of heating industrial water, l / min, not less
- when heated to 25, ^o C - 12;
- when heated to 35, ^o C - 9;
- content in exhaust gases, ppm
- carbon monoxide - 2.51;
- methane - 11.12;
- nitrogen oxides - no.

 The present invention allows to create a hot water boiler with a capacity of 10-100 kW, using the principle of catalytic oxidation of natural gas, as well as other hydrocarbon gases, to produce heat. The hot water boiler provides environmentally friendly oxidation of hydrocarbon gases so that the CO content in the exhaust gases corresponds to a concentration of not more than 10 ppm, methane - not more than 30 ppm in the absence of nitrogen oxides.

 The invention can be used for autonomous water heating and year-round hot water supply for domestic and industrial premises.

Claims (8)

 1. A boiler containing a frame in which a furnace block is located, consisting of a catalytic burner, a heat exchanger, an ignition unit, a control unit and a boiler operating mode control system, characterized in that it contains a catalytic heating element containing a tubular cylindrical structure as a burner or oval and two glasses serving as a continuation of the tubular structure, with a catalyst layer located on the surface of the tubular structure and glasses, gas distribution devices о with a unit for supplying a gas-air mixture, a place for entering and leaving cooling water.  2. A water boiler according to claim 1, characterized in that the catalyst in the catalytic heating element is made in the form of gas-permeable flat and corrugated reinforced tapes, wound and sintered with a tubular structure and glasses, with gaps between the turns with the formation of gas channels between the tapes.  3. Water boiler according to paragraphs. 1 and 2, characterized in that the outer catalyst layer has a corrugation larger than the critical size of the channels for penetration of the flame into the catalyst layer.  4. The hot water boiler according to claim 1, characterized in that the width of the catalyst layer in the catalytic heating element exceeds the width of the tubular structure by the width of the glasses, separated by thermal contact with the catalyst layer.  5. A water boiler according to claim 1, characterized in that the gas distribution device in the catalytic heating element contains one or more perforated gas distribution pipes with a diameter of perforation holes smaller than the critical diameter for the flame to penetrate into the gas distribution tube and the jet divider flowing from the perforation holes.  6. The hot water boiler according to claim 1, characterized in that the tubular structure in the catalytic heating element is made in the form of a water-cooled tubular heat exchanger. 7. The hot water boiler according to claim 1, characterized in that a reinforced porous material containing Co ₃ O ₄ , CuO, Cr ₂ O ₃ , Fe ₂ O ₃ , Al ₂ O as active components is used as a catalyst in the catalytic heating element ₃ , Group VIII metals fixed on metal supports using Ti-Al, Ni-Al, Ni-Cr, Ti-Si alloys.  8. The hot water boiler according to claim 1, characterized in that natural gas, a propane-butane mixture, refinery exhaust gases, flare gases, and others are used as fuel.

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