The Environmental Protection and Energy saving Effect of Integrated Smoke Tower

By utilizing the enormous heat generated by natural ventilation cooling towers, the net flue gas after desulfurization is lifted and discharged, which is called the integration of smoke towers. In most cases, the lifting of mixed flue gas at the outlet of the smoke tower can promote the diffusion of pollutants. Due to the absence of leaks, it ensures desulfurization efficiency and has good environmental protection effects; After adopting the flue gas tower integration, the reheating part of the clean flue gas can be eliminated, the resistance of the flue gas system is reduced, and the energy consumption of the booster fan is also reduced, which can lower the power consumption rate of the plant. At the same time, the waste heat of the flue gas entering the desulfurization system is recovered, which to some extent saves coal consumption and thus has a good energy-saving effect.
[Keywords] Integrated smoke tower, environmental protection, energy conservation
Existing engineering practice of integrating smoke towers into one

The research on the integration of smoke towers began around the 1970s, and engineering practice began in Germany in the 1980s. It developed rapidly in the 1990s and is currently being applied in more than 20 power plants in Poland, Turkey, Italy, Hungary, Greece and other countries besides Germany. The single unit capacity has developed from the initial Volklingen power plant with a capacity of 200000 kilowatts to the currently under construction Neurath power plant with a capacity of 1 million kilowatts. The total installed capacity in the world has reached 30 million kilowatts.
The principle of integrating two smoke towers to discharge wet flue gas after desulfurization

The use of natural ventilation cooling towers to discharge desulfurized flue gas has its obvious characteristics. Compared with the smoke emitted from chimneys, the smoke clusters have a significant heat content. The dynamic lifting effect caused by heat is many times that of chimney emissions, resulting in a significant lifting of smoke clusters emitted by the cooling tower under weak wind conditions.

The environmental and energy-saving effects of integrating three smoke towers

3.1 Environmental Protection Effect of Integrated Smoke Tower
Observations indicate that under unstable atmospheric conditions, smoke plumes are easily lifted to higher heights (as shown in Figure 1). The research calculation results show that under unstable atmospheric weather conditions, the flue gas emissions from a 120m high cooling tower after desulfurization are not higher than the ground concentration emissions from a 240m high chimney. This is mainly caused by the slightly better lifting of the cooling tower compared to the chimney under calm or light wind weather conditions. After reaching the maximum ground concentration, the final ground sulfur dioxide concentration caused by the two methods was almost identical and rapidly decreased (as shown in Figure 2).

After adopting the integration of smoke tower, the raw flue gas is directly purified by the absorption tower and enters the FRP flue, where it is discharged through the smoke tower. Therefore, the raw flue gas that has not been desulfurized and purified will not leak into the purified flue gas. Compared with the FGD with GGH leakage rate of about 3% or more, it can improve the desulfurization efficiency by about 2% or more, thus ensuring the desulfurization efficiency.
3.2 Energy saving effect of integrated smoke tower
The energy-saving effect of adopting the integrated smoke tower emission method is reflected in the following aspects (estimated based on a total capacity of 1000MW and 6000h utilization hours of 4 units):
(1) The cancellation of rotary GGH has reduced the electricity consumption of the reheating system for clean flue gas to a certain extent, saving about 3.6 million kW. h of electricity annually.
(2) Due to the lack of a clean flue gas reheating device, compared with conventional desulfurization systems with GGH, the resistance of the flue gas system is reduced by about 1/4, the motor power of the booster fan is reduced by about 1/3, and an annual energy saving of 16 million kW. h can be achieved; Overall (1) and (2), compared to conventional power plants with GGH desulfurization systems, the plant power consumption rate has been reduced by approximately 0.4%.
(3) The use of a tubular flue gas cooler to recover the heat entering the FGD absorption tower improves the utilization rate of heat, and each unit recovers

The amount of waste heat collected by 2 units is about 25GJ/h, and about 600000 GJ of waste heat can be recovered by 4 units throughout the year, which is equivalent to saving 50000 to 60000 tons of coal consumption throughout the year.

Engineering design of integrating 4 smoke towers

In the design of the integrated smoke tower project, the desulfurized flue gas enters the center of the natural ventilation cooling tower through a fiberglass flue (FRP) and is discharged. The typical process of the integrated smoke tower power plant is shown in Figure 3.
Figure 3 Schematic diagram of desulfurization tower integrated power plant process
The key to the design of the integrated smoke tower project is not only the FRP flue inlet on the smoke tower wall, but also the FRP flue and anti-corrosion treatment.
(1) FRP flue
Before designing the flue, it is necessary to confirm the composition, temperature, pressure, and flow rate of various pollutants in the flue gas at the outlet of the FGD, and then pass them through
Calculate the composition of the gas emitted from the fiberglass flue, as this affects the amount and thickness of corrosion-resistant resin (see Figure 4).
The internal anti-corrosion layer, structural layer, and external protective layer of the FRP flue are all made of DOW resin, with different thicknesses, and the laying design of each layer
Different, the types of glass fibers are different.
3
Figure 4 Typical FRP flue layout
The design of the layer is the key to producing a qualified FRP flue, and different parts have different designs. Years of Engineering Practice Table
Ming, the FRP flue has minimal maintenance work and strong corrosion resistance, which enables the transportation of wet flue gas to the flue tower after desulfurization, as well as full capacity
The corrosive environment of flue gas after desulfurization has played a positive role.
(2) Corrosion prevention of smoke tower
The anti-corrosion of smoke towers is another key technology in smoke tower integrated power plants, and the effectiveness of anti-corrosion directly affects the safe operation of smoke towers.
Anti corrosion uses vinyl ester resin, with an outer layer of 2 layers and a thickness of about 80 μ m, and an inner layer of 3 layers, consisting of 1 base layer and 2 layers. The throat
Approximately 200 μ m below and 300 μ m above the throat.
5 Summary

The desulfurization flue gas tower integration project is a mature and advanced technology that integrates energy conservation and environmental protection. Its main characteristics are as follows:
(1) The lifting of the mixed flue gas at the outlet of the smoke tower can promote the diffusion of pollutants. Since there is no leakage, it ensures the desulfurization efficiency, which is beneficial
environment protection
(2) After adopting the integration of the smoke tower, the reheating part of the clean flue gas can be eliminated, the resistance of the flue gas system can be reduced, and the energy consumption of the booster fan can be reduced
It also reduces the power consumption rate of the plant, thus having a great energy-saving effect. At the same time, it recovers the waste heat from the flue gas entering the desulfurization system, which to some extent saves coal consumption.
Therefore, promoting this technology appropriately while meeting the environmental conditions for tower lifting can promote the development of clean production technology that emphasizes both energy conservation and environmental protection in China.