Steam Boiler System Selection (Part2)

August 04, 2020

Steam Boiler System Selection (Part2)

This article will analyze the auxiliary machinery parts of the steam boiler system for you.

1.Fuel Supply System

There are two types: belt coal feeder and lifting coal feeder. The price of the belt coal feeder is slightly higher than that of the lift coal feeder.

2. Air supply system

Mainly used in solid fuel boilers. Because this type of boiler requires slight negative pressure combustion in the furnace. Therefore, in general, the induced draft fan is slightly larger than the blower, the induced draft fan is connected to the flue, and the blower is connected to the air duct. These two devices are mandatory for solid fuel boilers.

3. Electronic control system

The ordinary electric control system,

the most basic control system, only the alarm function can start and stop the boiler, and the related auxiliary equipment can be turned on and off. The boiler cannot be controlled digitally, and the boiler cannot be observed more intuitively. Of course, the price is also the cheapest.

The PLC control system,

the semi-digital programmable electric control system can monitor the temperature, pressure, and other data of the boiler, perform automatic boiler water replenishment, and boiler safety automatic shutdown. More precise control of the boiler. Basically, the entire control of the boiler can be realized. The price is medium. All boilers under 10 T/h are applicable.

DCS control system:

digital fully automatic electronic control system. It can monitor various data of the boiler in real-time, including comprehensive feedback such as boiler combustion, boiler pressure, steam temperature, water level, etc. It can program the operation of the boiler and automatically adjust various states of the boiler. The price is higher. A DCS electronic control system is recommended for boilers over 10 T/h.

4. Water treatment system

Water treatment equipment.

At present, resin exchange water treatment equipment is widely used, and the water quality of this equipment is relatively high. The PH value can be controlled at around 9. If it is only fire tube boilers and water-fire tube boilers under 10 T/h, dosing devices are not required. Generally, equipped with 2 water treatment equipment, one is used and one is prepared. When replacing water treatment equipment, there is no need to stop the boiler.

Deaerator:

remove oxygen in the water to avoid boiler oxidation and corrosion. This equipment is generally equipped with boilers of more than 10 T/h.

Dosing device.

Steam boilers over 10 T/h need to be equipped with chemical dosing devices, and the PH value is controlled at 9-11. Prevent boiler fouling.

5. Water supply system.

The steam boiler, as the steam continues to evaporate, requires a continuous supply of water to the boiler. Therefore, we need to use higher quality water pumps. Once the water pump has a problem, the boiler water level will be too low and the boiler will be forced to shut down. It can even cause the boiler to explode when it is dangerous. At present, the most used EPCB boilers are the American Greif pumps and the Nan-fang pumps. The pump quality is very good. There are generally equipped with two water pumps, which are the same as water treatment.

6. Energy-saving system

The boiler exhaust temperature is generally about 50°C higher than the steam temperature. That is, the temperature of the smoke is generally around 250°C. If the temperature of the exhaust gas can be reduced to about 150℃. According to the size of the boiler, at least $20,000/year of fuel can be saved. The lower the flue gas temperature, the more savings, the bigger the boiler, the more savings. However, it is not recommended that the flue gas temperature drop too low. The exhaust gas below 100 degrees Celsius will generate sulfuric acid, nitric acid, and carbonic acid, all corrosive liquids. Corrodes the chimney.

Economizer,

finned tube economizer is currently the most used in the market. According to different suppliers, the boiler size, structure, and size will vary. Generally, the temperature of the smoke will be reduced to about 150°C. The price is more appropriate. You can save the economizer cost in half a year.

Condenser:

The function of the condenser is similar to that of the economizer, but the structure is different and the energy-saving effect is better. The price is relatively higher. The smoke temperature can be reduced to about 100°C. You can save the condenser cost in 1 year.

Air pre-controller.

Use high-temperature flue gas to heat the air and blow the air back into the furnace. This equipment uses more solid fuel boilers. The energy-saving effect is poor and the price is cheaper. The cost can be recovered in 2 years.

Condensate recovery device. Recover the latent heat in the steam. The condensate and heat are recycled twice. Relatively high prices, countries, and regions with higher fuel prices can be equipped. The cost can be recovered in 1~2 years.

7. Water Blowdown System

Continuous blowdown expansion tank and regular blowdown expansion tank can play a role in energy saving, the price is medium, but the energy-saving effect is poor. It is only recommended to equip boilers above 10 Ton/h.

8. Dust removal system

The multi-tube dust collector

has high dust removal efficiency and can capture particles of about 5 microns. It is more suitable for countries and regions with less stringent emission requirements. The price is also much cheaper. Often used with wet dust collectors.

The wet dust collector

has medium dust removal efficiency and can absorb NOx and SOx in the flue gas. The price is relatively low. It is often used with multi-tube dust collectors.

The bag type dust collector

has the highest dust removal efficiency, up to 98%. But the price is higher than the sum of multi-tube dust collectors and wet dust collectors. Moreover, the bag is flammable, and if the boiler is not operated properly, the bag will be burned out. It is best to equip a flame arrestor.

9. Slag removal system

The scribe type slag remover and the spiral type slag remover have the same slag removal efficiency and similar prices. You can choose according to personal preference.

10. Security control system.

Safety valve, pressure gauge, water level gauge, steam flow meter, interlock protection device. According to the specific conditions of the boiler, different valves are equipped. 2 water level gauges and 2 water level sensors. 1 pressure gauge, 1 electric contact pressure gauge, 1 steam flow meter, 2 safety valves, 1 interlocking protection device. This is the minimum configuration.