RU2794290C1 - Device for burning suspension fuels - Google Patents

Abstract

FIELD: energy.

SUBSTANCE: device for burning suspension fuels contains a combustion chamber, which has the shape of a parallelepiped with a square horizontal section, on the front wall of which fuel pneumatic nozzles are mounted, and blow nozzles are installed on the side and rear walls, an ash catcher made in the form of a funnel is installed in the lower part of the chamber, an ash and slag removal chamber in the form of a cylinder with a diameter greater than the diameter of the ash catcher funnel neck by 2 times or more is installed below ash collector, with an open lower end immersed in water, filling a bath with one inclined wall installed below, above the bottom and inclined wall of which an ash and slag removal scraper conveyor is mounted, while the ash and slag removal chamber is connected to the combustion chamber by a pipeline with a built-in fan, and a chamber for afterburning fuel and cooling flue gases, made in the form of two or more sections with shielded walls located in series one after the other. An additional combustion chamber is installed between the combustion chamber and the chamber for afterburning the fuel and cooling the flue gases.

EFFECT: increased efficiency of CWF combustion by ensuring the stability of the ash melting temperature in the furnace, low underburning coefficient and controllability of the boiler performance.

3 cl, 1 dwg

Description

The invention relates to devices for burning liquid, including water-coal fuel (VUT) in various boiler plants for industrial heat power, housing and communal services and other heat generating systems.

The technology of coal combustion in the form of CWF opens up the possibility of using low-grade coal and coal waste in thermal power engineering. However, the calorie content of such suspensions is low and, as experience shows [Alekseenko S.V., Maltsev L.I. et al. Results of experimental and operational combustion of water-coal fuel in a low-capacity water-heating boiler. Bulletin of the Tomsk Polytechnic University. Engineering of georesources. - 2017. - T. 328. No. 12. - S. 16-28], the most successful results are obtained only in cases where the combustion of CWF is carried out in combustion chambers at sufficiently high temperatures.

Known combustion device for the combustion of coal-water fuel [RU 2518754, 29.08.2012, IPC F23C 3/00, F23J 1/02], including a lined combustion chamber with fuel injectors, blow nozzles with a tangential supply of an oxidizer and a central refractory insert and a chamber shielded by boiler pipes cooling with a convective tube bundle, interconnected by means of gas bypass windows. In the lower part of the combustion device, in the center of the combustion chamber, an ash catcher is installed, made in the form of a funnel, and an ash removal chamber in the form of a cylinder with a diameter greater than the diameter of the neck of the ash catcher funnel by 2 times or more with an open lower end immersed in water, filling the bath installed below with one an inclined wall, above the bottom and inclined wall of which a scraper conveyor for ash and slag removal is mounted, while the ash and slag removal chamber is connected to the combustion chamber by a pipeline with a built-in fan, and a heat exchanger is additionally installed in front of the fan.

The closest solution is a boiler for burning slurry fuels [RU 2766244, 06/15/2021, F23C 3/00], containing a combustion chamber and an afterburning chamber for fuel and flue gas cooling. The combustion chamber is made in the form of a parallelepiped with a domed upper boundary, fuel pneumatic injectors and blow nozzles are mounted on opposite side walls, an ash catcher in the form of a funnel is installed in the lower part of the combustion chamber, an ash removal chamber is installed below the ash catcher, connected to the combustion chamber by a pipeline with a built-in fan. The chamber for afterburning fuel and cooling flue gases is made in the form of two or more sections with shielded walls, located in series one after the other.

Thus, in boilers operating on CWF, it is advisable to maintain the temperature at the level of the ash melting point. But VUT is a fuel with a reduced calorific value, and in order to ensure reliable complete fuel burnout, in practice, the excess air coefficient is usually set close to 1.2, due to which some part of the thermal energy in the muffle furnace is spent on heating excess air. As a result, in the analogue and the prototype, firstly, it is not always possible to provide the desired temperature in the furnace, and secondly, the boiler almost always has to operate at limiting modes and does not allow its performance to be controlled.

The objective of the claimed invention is to increase the efficiency of CWF combustion by ensuring the stability of the ash melting temperature in the furnace, low underburning coefficient and controllability of the performance of the device for burning slurry fuels.

A device for burning slurry fuels is proposed, which includes three chambers:

1. combustion chamber equipped with injectors and blast nozzles;

2. afterburning chamber for fuel and flue gas cooling;

3. an additional combustion chamber with a nozzle and a blast nozzle installed between the combustion chamber and the chamber for afterburning fuel and cooling flue gases.

The combustion chamber has the shape of a parallelepiped with a square horizontal section, on the front wall of which fuel pneumatic injectors are mounted, and on the side and rear walls there are blow nozzles,

The chamber for afterburning fuel and cooling flue gases is made in the form of two or more sections with shielded walls, located in series one after the other.

According to the invention, between the combustion chamber and the chamber for afterburning fuel and cooling flue gases, an additional combustion chamber is installed, which is equipped with a nozzle and a blower nozzle that provide the necessary calculated values of fuel and oxidizer consumption, an ash catcher made in the form of a funnel is installed in the lower part of the chamber, below the ash catcher an ash and slag removal chamber is installed in the form of a cylinder with a diameter greater than the diameter of the mouth of the ash catcher funnel by 2 times or more with an open lower end immersed in water filling a bath installed below with one inclined wall, above the bottom and inclined wall of which a scraper conveyor for removing ash and slag is mounted, at the same time, the ash and slag removal chamber is connected to the combustion chamber by a pipeline with a built-in fan.

According to the invention, the nozzle of the additional combustion chamber is installed on the front wall of the chamber along the normal to the wall along the height in the middle of the passage window between the combustion chamber and the additional combustion chamber,

According to the invention, the blast nozzle of the additional combustion chamber is mounted on the rear wall of the chamber along the diagonal of its section with a horizontal plane at the level of the nozzle.

The device for burning slurry fuels, equipped with an additional combustion chamber, has a low coefficient of underburning of coal, and also provides regulation of its productivity within the limits of up to 40% of the maximum value.

The drawing shows a diagram of a device for burning slurry fuels, where: 1 - muffle combustion chamber; 2 - chamber for afterburning fuel and cooling flue gases; 3 - nozzles on the front wall of the combustion chamber; 4 - blow nozzles on the walls of the combustion chamber; 5 - additional combustion chamber; 6 - additional nozzle; 7 - additional blow nozzle; 8 - a window for the flow of gases from the combustion chamber 1 to the additional combustion chamber 5, 9 - a window for the flow of hot gases from the afterburning chamber and the cooling of flue gases into the convective part of the boiler.

Thus, the device for burning slurry fuels consists of three chambers:

1. muffle combustion chamber 1, equipped with nozzles 3 and blow nozzles 4,

2. additional combustion chamber 5 equipped with nozzle 6 and blow nozzle 7,

3. a chamber for afterburning fuel and cooling flue gases 2, including two or more sections with walls covered with screen pipes.

When starting the boiler into the combustion chamber 1 in its upper part with pneumatic nozzles 3 [Pneumatic nozzle (Options): US Pat. Ros. Federation №2523816; dec. 01/22/2013; publ. 07/27/2014, Bull. No. 21. - 10 sec.] introduce highly reactive (for example, diesel or furnace) fuel.

A helical wall jet of blast air is fed into the combustion chamber through blow nozzles 4 intended for blowing the oxidizer, which provides a vortex flow of the fuel-oxidizer mixture and allows intensifying the heat-mass transfer combustion processes.

Due to the heat released during the combustion of the fuel, the walls of the combustion chamber are heated. After heating the walls of the combustion chamber to a temperature of 500-600°C, a small proportion of water-coal fuel is added to the diesel fuel. As the temperature inside the combustion chamber further increases, the proportion of diesel fuel in the supplied mixture decreases, and the proportion of CWF increases until the boiler reaches the design mode of operation only on water-coal fuel.

In the operating modes of the boiler, by selecting the fuel flow supplied to the combustion chamber, and the coefficient of excess oxidizer, not exceeding the value of α=1, in the chamber 1 the temperature is maintained above the ash melting temperature. The resulting molten slag flows down to the neck of the ash removal chamber, and hot gases flow into the additional combustion chamber 5. An additional portion of CWF is introduced into the additional chamber through the nozzle 6, and the corresponding amount of air is introduced through the blower nozzle 7. The CWF gas-droplet jet formed by nozzle 6 enters the hot gas stream flowing out of window 8, quickly warms up and ignites. Due to the short residence time of the fuel inside the chamber 1 and the small value of α, the underburning coefficient of the fuel in the combustion chamber 1 can take on significant values. However, the presence of an additional combustion chamber makes it possible to reduce the total underburning of coal to almost zero.

Numerical calculations have shown that in a single-chamber furnace, a decrease in the flow rate of blast air in the vicinity of the value α=1 makes it possible to significantly increase the temperature inside the combustion chamber, but this may also increase the underburning of coal. The use of an additional combustion chamber allows maintaining a higher temperature in the furnace and increasing the residence time of the fuel in the high temperature zone, which leads to minimization of underburning and makes it possible to control the boiler performance.

Claims (3)

1. A device for burning slurry fuels, containing a combustion chamber, which has the shape of a parallelepiped with a square horizontal section, on the front wall of which fuel pneumatic nozzles are mounted, and blow nozzles are installed on the side and rear walls, an ash catcher is installed in the lower part of the chamber, made in the form funnels, below the ash catcher, an ash and slag removal chamber is installed in the form of a cylinder with a diameter greater than the diameter of the neck of the ash catcher funnel by 2 times or more, with an open lower end immersed in water, filling the bath installed below with one inclined wall, above the bottom and inclined wall of which a scraper conveyor is mounted removal of ash and slag, while the ash and slag removal chamber is connected to the combustion chamber by a pipeline with a built-in fan, and a chamber for afterburning fuel and cooling flue gases, made in the form of two or more sections with shielded walls located in series one after the other, characterized in that between the chamber combustion chamber and an afterburning chamber for fuel and cooling of flue gases, an additional combustion chamber is installed, equipped with a nozzle and a blast nozzle, providing the necessary calculated values of fuel and oxidizer consumption. 2. The device according to claim. 1, characterized in that the nozzle of the additional combustion chamber is installed on the front wall of the chamber along the normal to the wall in height in the middle of the passage window between the combustion chamber and the additional combustion chamber. 3. The device according to claim 1, characterized in that the blast nozzle of the additional combustion chamber is mounted on the rear wall of the chamber along the diagonal of its section by a horizontal plane at the level of the nozzle.

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