Heat generator TGm - 1,5

Heat-generators of Kriger company, due to their design of a furnace with an inclined movable grate, allow the use of various biomass with high degree of humidity as fuel.

This advantage of heat-generators can reduce significantly the cost of production for enterprises, which use the energy of thermal units in their technological processes, taking into consideration the shortage and high price of gas fuel.

The heat-generators of our production are distinguished by high automation and control of the entire process of generating thermal energy, and are widely used as a heat source for producing steam in steam boilers and for drying of agricultural products in drying plants.

According to its design, Kriger company producers contact and non-contact heat-generators.

Contact heat-generators generate direct heat from fuel combustion.

Non-contact heat-generators generate heat, obtained from heated atmospheric air by

fuel combustion products.

Contact heat-generators TGm-ХХ.Х

Heat-generators of this model are manufactured with capacity of 5-10, 2 and 1,5 MW.

 Usually this type of heat-generators is used for thermal units, that require high temperatures from the heat source (steam and hot-water boilers), and for thermal installations of agricultural enterprises, that do not require restrictions to ecological environmental performance of the heat source.

The heat-generators are made in the form of a non-cooled thermally insulated furnace with a movable inclined grate. The product includes drafting machines, an automated fuel supply device, a device for ash and slag removing from the furnace, as well as a device for primary purification of flue gases from volatile solid particles. The heat-generator control system is based on the basis of an industrial computer.

Description of the operation of the heat-generator

 Fuel undergoes different transformations in the furnace.

• When entering the furnace, the moisture contained in the fuel evaporates due to the high temperature of the furnace (emission of white smoke).
• When all the moisture evaporates, a volatile fuel gas is formed inside of the furnace, released by pyrolysis. Wood is fuel which contains approximately 70% volatile substances.
• The solid fraction remaining after the release of gas by pyrolysis (or carbon residue) burns in the downward direction of the furnace. At the end of the grates, the combustion ends and only ash remains.
• The volatile fraction of the fuel burns in the gas phase. This combustion begins in the furnace, above the grates, then continues in the first pass (or combustion chamber).

In order to organize such combustion, the injection of air that supports combustion is organized as follows:

Primary air is pumped under the grates, into different compartments corresponding to different phases of fuel transformation, associated with the grates (drying, pyrolysis, burning of coal residues).

Secondary air is blown through holes in the heat generator, at the level of the passage to the first row of the tube heat-exchanger: this air ensures the combustion of pyrolysis gases. The holes are equipped with plugs, that can be adjusted manually outside the boiler, and their number and location can be also adjusted.

The number of fans is determined based on the maximum required flow, that is, the maximum power. For the power below the nominal air flow is reduced with the help of automatic dampers and frequency regulators of the fan speed. The flow of secondary air is also regulated depending on the desired amount of oxygen at the exit from the heat generator.

The implementation of combustion in several stages is the technique of “staged combustion”, which is used to achieve greater combustion efficiency with the least amount of pollutants. Combustion occurs not only at the level of the grates, the temperature there is lower, which allows to reduce the production of nitrogen oxide of thermal origin. Products from the first combustion zone finish burning at the level of secondary air injection, where a live flame develops, and there the transformation of CO into CO2 takes place.

The automation complex (a set) is a software and a hardware complex, designed to control the combustion process and the operation of the heat-generator in general, as well as fuel supply mechanisms. The system provides control of the heat-generator, automation of control, signaling, management, regulation, necessary protection and blocking processes. The main element of automation is the processor. It is worth noting that each drive within the boiler plant is equipped with a frequency converter, which allows, firstly, to make more flexible control of all processes in this complex and, secondly, to minimize the actual consumption of electricity.

Since the fuel supply is carried out by a plunger (or an auger according to the customer`s choice), the fuel is collected in the supply channel, then enters the furnace with movable grates. The grates are made of cast iron with a high chromium content and are arranged in rows. The special design of the grates provides for the operation of the grate “without spills”, which ensures minimal losses from “mechanical under-fire” and simplifies the maintenance of the base of the heat generator. Every second row is located on a frame that moves back and forth: movable grates, while the others are stationary. The system helps the fuel spread through the grates:

• as the movable frame moves forward, the movable grates slide motionless and push the fuel forward.
• as the frame goes back, the fuel on the moving grates falls on the fixed ones.

The frame is moved by a hydraulic cylinder. The movement of the cylinder is controlled by two sensors, located at the end of the movement. The side walls and vault of the furnace are covered with heat-insulating concrete with a high AL203 content of about 88%. The presence of such material allows maintaining the temperature, sufficient for effective combustion in the furnace.

The design of heat generator allows fuel to be burnt in a wide humidity range from 10% to 50% with maximum efficiency and low NOx content.

Multicyclone with η ≈ 97%, which is designed to clean flue gases leaving the heat generator from solid particles. The use of cast cyclone bodies made of special material allows to increase significantly the service life of this unit even in conditions of maximum abrasiveness of the particles being cleaned.

Flue gases enter the multicyclone along a spiral-looking surface, and under the action of centrifugal forces, solid particles settle in the lower hopper, from where they are moved to the general ash removal system with the help of screw transport, and the gases exit through the upper part of the cyclone.

The heat generator is made of thick sheet boiler steel, the furnace is lined with refractory concrete, insulated with basalt insulation and veneered sheet metal with a polymer coating.

All the elements of the heat generator are mounted on a common frame, which greatly facilitates the installation of this equipment and minimizes the costs, connected with the design and manufacture of foundations.

Fuel:

• wood wastes – wooden chips, bark, sawdust and shavings;
• peat in pieces, milled and granulated peat;
• granulated agricultural production wastes – cobs, corn straw, sunflower husks and buckwheat husks, grapevine, flax husks.

Fuel fraction: 55x45x15mm. Humidity from 10% to 55%.

The scope of supply of a heat generator includes:

• A heat generator (a base with movable grates, a furnace, lower and technological doors, a multicyclone);
• Fuel supply device (a plunger or a screw type, according to customer's choice);
• A set of fans within the heat generator;
• A multicyclone (as an option);
• Ash removal system from under the grates` area and a multicyclone;
• An automation system with monitoring control sensors;

The design service life of the unit is 20 years.