Biomass / coal-fired hot water boiler technical discussion on 5.6mw biomass hot water boiler

Coal fired boiler:

The new DZL series boiler is a single drum longitudinal water fire tube shell boiler, and the combustion equipment is a chain grate.

Boiler water circulation is natural circulation plus injection. The water walls on the left and right sides of the furnace are radiant heating surfaces, the two wings of the furnace are convective heating surfaces, the boiler drum is equipped with spiral flue pipe convective heating surfaces, the front and rear arches are made of heat-resistant concrete by a new process of integral casting, and the outer side of the boiler main machine is a three-dimensional guard plate shell.

1. This series of boilers adopt arch tube sheet, threaded smoke tube, hot water boiler backwater injection technology, etc., which solve the problems of shell boiler tube sheet crack, drum at the lower part of the drum, water-cooled wall tube explosion, low thermal efficiency, insufficient output, poor adaptability of coal quality, etc.

2. Combustion process:

The fuel falls at the front of the grate from the coal hopper. With the operation of the grate, the coal is preheated, carbonized, ignited and burned out. The slag falls into the slag hopper and is discharged from the furnace at any time by the slag remover. The flue gas can form a vortex at the throat between the front and rear arches to fully mix with the air, and heat the front arch. It enters the two wing convection tube bundles through the smoke window at the upper part of the arch, enters the threaded smoke pipe through the front smoke box, and is led to the chimney by the induced draft fan after passing through the economizer and dust collector.

3. Technical features:

(1) The boiler drum is composed of arched tube plate and threaded smoke pipe, which makes the boiler drum change from quasi rigid body to quasi elastic body structure, cancels the tension brace in the tube plate area, and reduces the stress. The flue gas pipe is changed from two return to single return, which solves the problem of tube sheet crack.

(2) Due to the arrangement of rising pipe row at the lower part of the drum, the dead water area at the bottom of the drum is eliminated, so that the sludge is not easy to deposit. The high-temperature area of the drum can be well cooled, and the bulge at the lower part of the boiler shell is prevented.

(3) By using high-efficiency heat transfer screw smoke pipe, the heat transfer enhancement effect is obtained, the characteristics of fast boiler temperature rise and pressure rise are achieved, and the thermal efficiency of the boiler is improved.

(4) Compact structure, small overall dimension compared with the same type of boiler, saving the capital construction investment of boiler room.

(5) Stable operation, convenient adjustment and sufficient output.

(6) The hot water boiler has been greatly improved in water circulation. The jet technology is successfully adopted, and the return water is injected into the downcomer with jet water, so as to improve the circulating velocity of the riser.

(7) The threaded smoke pipe is used to enhance heat transfer, which improves the heat transfer coefficient and thermal efficiency. Due to the disturbance of flue gas in the pipe, it is not easy to accumulate dust in the smoke pipe, which plays the role of self cleaning.

(8) High efficiency and energy-saving furnace arch with integral pouring of heat-resistant concrete and independent air chamber are used in the furnace to achieve reasonable air distribution, so as to form an aerodynamic field conducive to combustion in the furnace, thus expanding the adaptability of coal.

(9) The furnace arch and outlet smoke window of the boiler have the function of dust removal. The original dust concentration of the boiler is controlled below the standard to ensure that the smoke and dust emission of the boiler reaches the indicators specified by the national environmental protection regulations.

4. Intelligent control cabinet

The control cabinet is designed according to the operating procedures and control requirements of the steam boiler and the characteristics of the combustion system of the coal-fired boiler. It has the functions of semi-automatic control and fault protection for the coal-fired boiler. The main control objects are blower, induced draft fan, make-up water pump, coal feeder, grate and slag extractor. The system takes PLM as the data processing and control core, and professional instruments as the operation and display. With multi-level protection function, the safety interlock is simple, convenient and reliable, making the system safer during operation.

The industrial control software carefully designed by Fenglan company and the process structure of the control periphery are embedded in the control system. The system software not only realizes the general monitoring requirements such as manual / automatic control, working condition monitoring and real-time trend of the boiler, but also adds the results of careful analysis and Research on boiler accidents in recent years by Fenglan company. It has rich functions such as fault detection, fault alarm and fault handling, and ensures the safe and reliable operation of the boiler.