What Is a Recovery Boiler?

The structure is different from ordinary steam boilers, and condensing heat exchangers and air preheaters are added.

Condensing waste heat recovery boiler

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The condensing waste heat recovery boiler is a structure different from ordinary steam boilers, and a condensing heat exchanger and an air preheater are added. The burner uses a split burner and heats the combustion air with an air preheater. With automatic adjustment of steam temperature and pressure, automatic ignition, and protection against water shortage, overpressure and flameout. The use of stainless steel finned tubes for condensing heat exchangers enhances heat transfer. Vacuum heat pipe air preheater, etc. Optional high-quality imported low-NOX burner, full combustion, belongs to environmental protection products.

The structure is different from ordinary steam boilers, and condensing heat exchangers and air preheaters are added.

The burner uses a split burner, and the air for combustion is heated by an air preheater.

Stainless steel finned tubes for condensing heat exchangers enhance heat transfer.

Vacuum heat pipe air preheater.

Optional high-quality imported low-NOX burner, full combustion, belongs to environmental protection products.

The boiler adopts advanced touch screen computer controller and digital computer controller for full automatic control.

With automatic adjustment of steam temperature and pressure, automatic ignition, and protection against water shortage, overpressure and flameout.

Boiler manufacturing specifications are manufactured strictly in accordance with relevant national standards.

The overall quick-installation is delivered from the factory with beautiful appearance and bright color.

Fuel contains a large amount of hydrogen, and combustion produces a large amount of water vapor. Every 1NM3 of natural gas can generate 1.55KG of water vapor after combustion, which has considerable latent heat of vaporization, which is about 3700KJ, which accounts for about 10% of the low-level calorific value of natural gas. When the exhaust temperature is high, the water vapor cannot condense and release heat, and the heat is wasted with the exhaust of the flue gas. At the same time, high-temperature flue gas also takes away a large amount of sensible heat, which together forms a large smoke loss.

The flue gas condensation waste heat recovery device cools the flue gas by using lower temperature water or air to reduce the flue gas temperature. Near the heat exchange surface area, the water vapor in the flue gas condenses, and the sensible heat release of the flue gas and the latent heat of water vapor condensation are realized It is released, and the water or air in the heat exchanger absorbs heat and is heated to realize heat energy recovery and improve the thermal efficiency of the boiler.

Increased boiler thermal efficiency: The theoretical flue gas volume for 1NM3 natural gas combustion production is about 10.3 NM3 (about 12.5KG). Taking the excess air coefficient of 1.3 as an example, 14 NM3 (about 16.6KG) of flue gas is generated. The flue gas temperature is reduced from 200 ° C to 70 ° C, the physical sensible heat is about 1600KJ, the water vapor condensation rate is taken as 50%, the latent heat of vaporization is about 1850 KJ, and the total heat release is 3450 KJ, which is about 10% of the natural gas low-level heat generation. If 80% of the flue gas is taken into the thermal energy recovery device, the thermal energy utilization rate can be increased by more than 8%, and natural gas fuel can be saved by nearly 10%.

In traditional boilers, the exhaust temperature is generally 160-250 ° C. The water vapor in the flue gas is still in a superheated state, and it is impossible to condense into liquid water and give off latent heat of vaporization. As we all know, the boiler thermal efficiency is calculated by the low-level heating value of the fuel, without considering the heat loss of the latent heat of vaporization in the high-level heating value of the fuel. Therefore, the traditional boiler's thermal efficiency can only reach 87% ~ 91%. The condensing waste heat recovery boiler reduces the exhaust temperature to 50-70 ° C and fully recovers the sensible heat in the flue gas and the latent heat of condensation of water vapor.

The natural gas as a fuel is used to condense the volume of water vapor in the flue gas of the condensing waste heat recovery boiler, and the water vapor content in the flue gas of the oil-fired boiler is 10% to 12%, which is much higher than the flue gas produced by the coal-fired boiler. Water vapor content below 6%. At present, the thermal efficiency of boilers is calculated based on the low calorific value. Although the nominal thermal efficiency is high, the actual energy utilization rate needs to be improved due to the difference between the high and low calorific values of natural gas. In order to make full use of energy, reduce the exhaust temperature, and recover the physical thermal energy of the flue gas, when the wall temperature of the heat exchanger is lower than the dew point temperature of the flue gas, the water vapor in the flue gas will be condensed to release latent heat, a high and low level of 10% The difference in heating value can be effectively used.

The exhaust temperature is one of the basic design parameters of the boiler. When designing the boiler, this parameter must be selected first.

Boiler exhaust temperature directly affects the economics of the boiler unit and the safety of the tail heating surface. Selecting a lower exhaust temperature can reduce the exhaust heat loss of the boiler, which is beneficial to improving the thermal efficiency of the boiler, saving energy and reducing the operating cost of the boiler. Therefore, how to effectively reduce the exhaust temperature of the boiler and make reasonable use of it is a major technical issue. The condensing waste heat recovery boiler introduced by South Korea's technology and research and development, and the reduction of the exhaust temperature is achieved by the following methods:

(1) Reduce the exhaust temperature by increasing the heat transfer area of the convective heating surface of the boiler body or by increasing the convective heat transfer coefficient;

(2) Add high-efficiency fin-type condensing heat exchanger and heat pipe air preheater in the tail flue.

The above method effectively recovers the sensible heat and the latent heat of vaporization in the practical application.

(1) Heat pipe air preheater and fin condensing heat exchanger are used, which effectively reduces the exhaust temperature.

(2) A split-type burner is used to preheat the air required for fuel combustion to fully burn the fuel and increase the furnace temperature.

(3) Condensation energy-saving device In order to prevent the acidic corrosion of the exhaust condensate, the imported stainless steel threaded pipe is used. Compared with the straight pipe, the heat conduction performance is more than 2 times higher than the straight pipe.

(4) The harmful gas of the flue gas is effectively controlled, and flows into the neutralization tank with the condensate.

In summary, the condensing boiler is the crystallization of sciences such as heat transfer, physics, combustion, and materials. It esteems traditional boilers with absolute economics. The promotion of condensing boilers is a shining light of thinking and a change in concepts. At the same time, it will certainly promote the development of the thermal industry.

1. The heat conduction performance of heat pipes is 500-1000 times higher than that of copper and aluminum pipes. Air preheaters made of heat pipes are 2/3 smaller in size and weight than traditional shell and tube air preheaters, which can be located on the front of the boiler. Assemble settings, occupying very little space.

2. Radial aluminum sheet with excellent thermal conductivity is attached to the surface of the tube to obtain a large heat transfer area in a small volume.

3. The temperature of the evaporation part and the condensation part of the heat pipe is uniform, and the amount of thermal expansion and contraction is small. It can be said that it is a long-life device.

1. This energy-saving device is made of stainless steel spiral finned tube in order to prevent the acidic corrosion of smoke and dew condensation and supply rust-free clean hot water.

2. Compared with the straight tube, a spiral fin tube with a heat transfer performance that is more than 2 times is used, and the size and weight are reduced to 1/2. Corrosion-resistant stainless steel extends its service life.

3. The device can be assembled in the upper part of the boiler to reduce the occupied space, and the condensed water generated on the heat transfer surface can also be naturally discharged.

In the exhaust path, a condensing waste heat recovery heat exchanger is set up. The flue gas passes through the heat transfer surface in the path, and the temperature drops below the dew point temperature. The latent heat of condensation of the steam contained in the exhaust fume heats cold or warm water. Waste heat recovery energy saving device (also known as condensing heat exchanger).

The condensing energy-saving devices seen in the process are arranged in series in the tail flue (front and rear) to condense the water vapor in the flue gas. After condensation, it absorbs part of the CO2 and NOX in the flue gas, cleans the flue gas, Environmental protection.

The condensed water is discharged into the neutralization tank through the guide pipe, and is neutralized with the alkaline lime water in the neutralization tank.