Boiler Selection Guide | Study on Selection of District Central Heating Boilers

October 10, 2022

Winter is coming. For cold areas, district central heating is an indispensable heating facility, which also marks the heating capacity and economic development level of a city.

 

At present, in response to the question of how to choose a boiler type in district central heating, some people think that economic input factors should be mainly considered when choosing a boiler, and some people think that when choosing a boiler, they should mainly focus on energy saving and environmental protection effect, and there are other Some people think that the selection of boilers should pay attention to social benefits in an all-round way, so how should the type of district central heating boilers be selected?

 

Based on more than ten years of experience in boiler equipment production and research and development, EPCB systematically elaborates on boiler types, boiler equipment selection principles, and boiler selection evaluation indicators to help you find a clear direction when selecting central heating boilers.

 

Boiler Type

At present, the boilers suitable for district central heating can be divided into the following three categories according to the combustion method: namely, floor-burning furnaces, chamber-burning furnaces and boiling furnaces.

These three types of boilers, as well as several of the newer types of boilers or combustion technologies, are described below.

 

1. Layer burner. 


The boiler in which the fuel is layered on the grate for combustion is called a layer-burning furnace, also called a fire-bed furnace. It is currently the most widely used furnace type for small boilers. Vibrating grate furnace, etc.

 

2. Chamber burner. 


A furnace in which the fuel flows into the furnace with air in a suspended state, also known as a suspended combustion furnace, such as a pulverized coal furnace, an oil-fired furnace using liquid fuel, and a gas-fired furnace.

 

3. Boiling furnace. 


The solid fuel is held up by the air from the bottom to the top in the furnace, and the boiler is rolled up and down for combustion. It is a relatively effective boiler for burning inferior fuel and desulfurizing and reducing nitrogen oxides. Fluidized bed furnaces include ordinary fluidized bed furnaces and circulating fluidized bed furnaces.

 

4. Several other newer boilers or combustion technologies

 

  • Waste heat boilers for gas-steam combined cycle systems


The waste heat boiler is a heat exchange equipment that recovers the exhaust heat of the gas turbine to generate steam for the steam turbine to generate electricity. Generally, the exhaust temperature of the gas turbine is 400~600℃. When the gas turbine burns natural gas, the sulfur content of the fuel is very low, and the waste heat The exhaust gas temperature of the boiler can be reduced to 80~90℃ (generally, the exhaust gas temperature of the waste heat boiler should be higher than the dew point of the flue gas by more than 10℃).


  • Condensing boiler


Condensing boilers use high-efficiency flue gas condensation waste heat recovery devices to absorb the sensible heat in the exhaust flue gas at the tail of the boiler and the latent heat released by the condensation of water vapor, so as to achieve the purpose of improving the thermal efficiency of the boiler.


  • Rubbish


Incineration technology General waste can be divided into several categories of waste, such as domestic waste, industrial waste, medical waste and hazardous waste. Commonly used waste incineration methods include fixed bed incineration, moving bed incineration, fluidized bed incineration, gasification incineration and rotary kiln incineration. At present, the most commonly used are moving bed incinerators, namely grate incinerators and fluidized bed incinerators.

 

Boiler Equipment Selection Principles

 

  • Selection principle

 

When the heat load, fuel type and analysis data, heat medium and its parameters are determined, the following principles should be followed when selecting a boiler:


1. The rated evaporation capacity of the boiler is selected according to the design heat load. When the heat load fluctuates greatly or the heat is intermittently supplied, the heater can also be considered to adjust the high and low loads.


2. The main technical indicators of the boiler should be able to meet the design requirements under any circumstances.


3. It can effectively burn the fuel used and has high thermal efficiency.


4. Comply with the relevant requirements of the national environmental protection, fire protection and labor departments, which is conducive to environmental protection.


5. Boilers with the same capacity and combustion equipment should be selected. When different types of boilers must be selected, their capacities and types should not exceed two.


6. On the premise of ensuring the safety of operation, the capital construction investment and operation cost should be minimized.

 

  • Number of boilers

 

The method for determining the number of boilers is as follows:


1. The number of boilers should be determined according to the dispatch of heat load, the possibility of rotating maintenance and expansion of boilers, and generally no less than 2 and no more than 5 in a new boiler room. The total number of units during expansion and reconstruction shall not exceed 7 units.

 

2. A spare boiler can be installed in the boiler room that is mainly based on production load or provides heat all year round. For the boiler room mainly based on heating, ventilation and domestic heat load, two boilers should be set up, when the largest one is overhauled, can still meet the minimum heat load, generally do not use boilers.


3. The boiler configuration of the heating unit should be determined according to the balance calculation of heating and power supply, and generally no boiler is used for equipment.

 

Boiler selection evaluation index

 

Boiler selection evaluation indicators mainly include four aspects:


1. Economic input indicators.

 

It mainly includes two parts of investment: a. The initial investment in equipment; b. The investment in fuel, water and electricity costs and the maintenance of the boiler during the operation of the whole year, and there are some necessary investments.

 

2. Energy saving indicators.

 

Energy is a non-renewable resource. In order to save energy, the selection of boiler type should consider the design stage of the product and the energy-saving effect of the boiler during normal operation, and then select a boiler with excellent performance. The former is mainly based on the metal consumption efficiency. To illustrate the level of energy consumption, the latter is mainly based on the thermal efficiency of the boiler to judge its energy-saving effect.

 

3. Environmental protection indicators.

 

The raw material basis of the district central heating system is generally coal, and the pollution products (smoke, sulfur dioxide and nitrogen oxides, etc.) produced by its combustion will cause huge damage to the human body and buildings. Therefore, the environmental protection factor is also one of the important indicators for choosing a boiler. one.

 

4. Social impact indicators.

 

The selection of boiler type requires the following criteria:

 

a. Its usage and situation are in line with my country's basic national conditions, national policies and development direction.


b. Can improve the civilized level of the working environment.


c. Promote social production and industrial development.


d. It will not have a negative impact on the living environment of the surrounding residents.


e. The area is reasonable and the land resources are saved.


f. The maintenance and repair process is timely, simple and fast, reducing potential safety hazards.

 

Taking these factors into consideration can ensure that a suitable boiler type is selected.

 

Conclusion

 

In summary, EPCB details several commonly used boilers as well as waste heat boilers, condensing boilers and waste incinerators. Therefore, when boiler users choose regional central heating boilers, they should comprehensively consider economic input factors, energy conservation and environmental protection factors, and social influence factors, and select the boiler type suitable for the region according to the boiler selection principles and methods. In this way, the safety, economy and practicality of boiler production can be ensured.

 

If you have any questions about boiler selection, please contact EPCB, we will provide you with free technical support. 


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