Energy balance is to analyze the balance relationship between input energy, effective utilization of energy and loss energy of a system (equipment, workshop, enterprise). Through energy balance, improve the level of energy utilization, analyze the influencing factors of each link in the process of energy utilization, find out the causes of energy loss and the potential and ways of energy saving, so as to formulate feasible technical transformation measures and improve the energy utilization rate of the system.

1. energy balance model

Energy balance refers to the balance of energy when the equipment is in a stable energy state. Energy balance can be divided into thermal balance, electric balance, steam balance, water balance and so on. According to production objects, it can be divided into equipment energy balance and enterprise energy balance.

Take thermal balance as an example to establish an enterprise energy balance model (Figure 3.2):

Figure 3.2 Energy Balance Model

2. Calculation of energy efficiency

Energy efficiency refers to the extent to which the energy contained in energy is effectively utilized, and the energy efficiency model can be expressed as:

Where eta is the energy utilization efficiency.

Use different objects and methods to calculate energy efficiency. Generally, there are three methods.

1) calculated according to product energy consumption.

Using the main energy-consuming products of the enterprise, the total energy utilization efficiency of the enterprise can be obtained by the weighted average of the effective energy utilization per unit product and the total energy consumption:

Where q refers to the output of the product;

E 1- Effective utilization of product energy;

E2- the total energy consumption of the product.

2) According to the purpose of energy use.

Energy has two uses: one is direct combustion; The other is converted into secondary energy for reuse. Therefore, it can be divided into: power generation, boiler, kiln, steam power, internal combustion power and so on. First, get the effective utilization energy of a certain purpose, then add up the effective utilization energy of various purposes, and finally compare the total energy consumption of various purposes (W use +W loss):

Where w represents the effective utilization of energy;

W loss-energy loss.

3) According to the energy from processing to utilization.

Divide energy from processing, conversion, transportation to final use into four processes, calculate the efficiency of each process respectively, and then multiply to get the total energy utilization efficiency:

ηtotal =ηplusηturnηtransportηuse× 100%