“Waste heat boiler” is usually no burner, if high pressure and high temperature steam is necessary, an additional burner can be installed in the “waste heat boiler”. Depending on the ignition of the fuel, the temperature of all the flue gas is raised, which can result in steam with high basic parameters.

For example, when a waste heat boiler is not installed with a burner, the flue gas temperature in the safe passage is 500 ° C, and after the additional burner is installed, the flue gas temperature in the passage can be ensured at 756 ° C. The pressure of the steam can be raised from 4MPa to 10MPa, the temperature of the steam can be raised from 450 ° C to 510 ° C, and the steam can be used for high pressure and high temperature turbogenerators, thereby enhancing the higher power export.

Waste heat boilers mainly use industrial waste gas as a pyrogen, so there is no need for an ignition operating system (unless there is a secondary combustion requirement).

The waste heat boiler is composed of a boiler drum, a movable smoke hood, a furnace section flue, an inclined 1 section flue, an inclined 2 section flue, a last 1 section flue, a last 2 section flue, a feeding tube (feeding pass) groove, an oxygen gun muzzle, a nitrogen sealing device and a nitrogen sealing plug, an inlet hole, a differential pressure taking device, a support and a hanger of the flue, etc. Waste heat boiler is divided into six circulation loops, each circulation loop is composed of down pipe and up pipe, each section of flue water from the boiler drum through the down pipe into the lower header of each flue into the heating surface, water through the heating surface after the generation of steam into the inlet header, and then into the boiler drum by the rising pipe. Each flue is connected with a flange.

Working principle of waste heat boiler

The combustion of fuel, gas and coal produces high temperature flue gas to release heat. The high temperature flue gas first enters the furnace, then enters the waste heat recovery device of the front smoke box, then enters the fireworks tube, and finally enters the waste heat recovery device in the flue of the rear smoke box. The high temperature flue gas becomes low temperature flue gas and is discharged into the atmosphere through the chimney. Because the waste heat boiler greatly improves the utilization rate of the heat released by the fuel combustion, it is very energy efficient.

Waste heat boiler product characteristics

The high temperature flue gas released by coal burning is transported to the inlet of the waste heat boiler through the flue, then flows through the superheater, evaporator and economizer, and finally discharged into the atmosphere through the chimney, the exhaust temperature is generally 150 ~ 180℃, and the heat released by the flue gas temperature from high temperature to the exhaust temperature is used to make water into steam. The boiler feed water first enters the economizer, and the water absorbs heat in the economizer and heats up to a saturation temperature slightly lower than the drum pressure into the boiler drum. After the water entering the cylinder is mixed with the saturated water in the cylinder, it enters the evaporator along the down tube below the cylinder to absorb heat and begin to produce steam, usually only a part of the water becomes steam, so the flow in the evaporator is a mixture of soda water. The steam mixture leaves the evaporator and enters the upper cylinder through the steam separation equipment, and the water falls into the water space inside the cylinder and enters the downcomer to continue absorbing heat and producing steam, while the steam enters the superheater from the upper part of the cylinder, absorbing heat and turning the saturated steam into superheated steam. According to the three stages of the steam production process corresponding to three heating surfaces, that is, economizer, evaporator and superheater, if you do not need superheated steam, only need saturated steam, you can not install superheater. When there is reheated steam, a reheater can be added.

Core components of waste heat boiler

Drum introduction

The cylinder is provided with pipe seats for pickling, thermal measurement, water level gauge, water supply, dosing, continuous blowdown, emergency water discharge, safety valve, air valve, and manhole devices. The drum is provided with two spring safety valves; Two water level meter, quartz tube type two-color water level meter, safe and reliable, easy to observe, correct indication. The tube holder is used in the tube inlet pipe hole and other pipe holes that may have a large temperature difference to prevent cracks near the pipe hole due to thermal fatigue. The inner device of the drum is provided with a separation device for water and water separation, and a connecting pipe for boiler water supply and dosing. The drum is equipped with two supports, one is a fixed support and one is a movable support.

Movable hood

The water distribution header is composed of a water distribution header and a connecting pipe. The boiler feed water is led from the boiler drum to the water header by the downcomer. In order to ensure that the temperature of each part of the header does not deviate, the water intake of the water distribution header and the lower header is introduced by multiple dispersive downcomer.
The collecting header is composed of an outlet header and a connecting pipe. In order to ensure that the temperature of each part of the header does not deviate, the soft water mixture is introduced into the outlet header by a number of connecting pipes, and then into the drum by the rising pipe.
The pipe group of the movable smoke hood is composed of the upper header, the lower header and the pipe group. 180 φ45×5 seamless steel pipes are connected between the upper and lower header, and the lower smoke hood is formed by flat steel welding between the pipes.
Due to technological reasons, the active smoke hood often needs to move up and down, and there is a gap between the active smoke hood and the furnace section. In order to prevent the high-temperature smoke from leaking out, a water seal tank is made on the upper part of the active smoke hood, and the water seal is sealed in the form of a water seal. In order to prevent molten slag from splashing into the sealing tank, a slag baffle is arranged at the end of the sealing tank to facilitate the cleaning of debris in the water tank. A cleaning hand hole is also provided on the water seal groove.

flue

It consists of distribution header, lower header, pipe group and upper header. The boiler feed water is led from the boiler drum into the distribution header. In order to ensure that the temperature of each part of the header does not deviate, the water into the distribution header and the lower header is introduced by dispersing down pipe. After entering the lower header, the water is dispersed into 132 φ42×4 seamless steel pipes and a circular flue heating surface composed of 6mm thick flat steel with a pitch circle of φ2400mm, and then the soft water mixture is produced into the upper header. The riser leads into the drum.

Oxygen muzzle

There is an oxygen muzzle on the flue of the furnace section, the oxygen muzzle is composed of tube bundle and upper and lower collecting box, because the temperature is high here, in order to prevent the deformation of the entrance structure, a removable water-cooled jacket structure is used, and the oxygen gun inlet is set up to prevent the smoke from spraying outside, and the oxygen muzzle nitrogen sealing device (containing nitrogen sealing plug) is also set.

Blanking pipe

A cutting pipe is provided on the flue of the furnace opening section, which is composed of a tube bundle, an upper and lower collecting box and an anti-wear plate. ZG series needle tube waste heat recovery device is specially designed for flue gas waste heat recovery of special high-efficiency energy-saving products. When the needle tube is used to strengthen the heat element to expand the heating surface, the heating surface on the smoke side of the pipe can be greatly increased. At the same time, strong turbulent flow is formed when the smoke flows through the needle tube surface, which can improve the heat transfer efficiency and reduce the accumulation of soot. The waste heat recovery device has the advantages of brief structure, high thermal efficiency, long operating life, safety and reliability, long operating life, safety and reliability, convenient maintenance and so on.

Waste heat boiler body composition:

Generally, the waste heat boiler is composed of economizer, evaporator, superheater, and heat exchange tube groups and containers such as header and drum, etc., in the steam cycle with reheater, reheater can be added.

★ Economizer – boiler feed water to complete the task of preheating, so that the feed water temperature to close to the saturation temperature level;

★ Evaporator – feed water phase change into saturated steam;

★ Superheater – saturated steam is heated to become superheated steam;

★ Reheater – reheat steam is heated to the set reheat temperature;

★ Steam drum – collects the economizer feed water and collects the steam and water mixture from the economizer to provide qualified saturated steam into the superheater or supply to the user.