Energy saving effect, cost and benefit of condensate recovery technology transformation

Condensate recovery is an important link in the cycle of steam thermal system. From the point of view of system energy saving, the quality of condensate recovery directly affects the total energy utilization efficiency of steam thermal system. This is mainly reflected in the following aspects:

1) Thermal energy value: Condensed water has about 20% steam thermal energy (enthalpy). Compared with the system without condensate recovery, the energy-saving potential of condensate recovery and transformation is greater than other links in the thermal system.

2) Process balance: The perfect design of condensate recovery system can make up for the steam leakage of steam equipment caused by improper selection of steam traps by about 3%, and reduce the flash loss of high-temperature saturated water by 5- 10%.

3) thermal balance: the waste heat recovery of condensate is used for thermal oxygen removal, which reduces the consumption of new steam and high-grade steam; Recovering condensed water to boiler drum can save boiler fuel. Generally speaking, fuel 1% can be saved for every 6℃ increase in feed water temperature. The recovery of condensed water is beneficial to reduce boiler blowdown, reduce heat loss of blowdown and improve boiler thermal efficiency.

4) Water balance: Condensed water as boiler feed water can reduce the amount of softened water treatment and save the treatment cost of softened water. project investment

The investment of new condensate recovery project consists of recovery pipe network, recovery pump station, automatic control and civil installation costs.

The investment of condensate recovery and reconstruction project includes steam trap selection, reconstruction of recovery pipe network, reconstruction of recovery pump station, automatic control system and some civil works reconstruction. The total investment of the project is determined by the radius of the factory building, the number of steam equipment, the diameter and number of recycling pipe networks, the pressure level and flow rate of condensate, and the utilization and control mode of condensate.

Payback period of investment

The value of condensed water is directly reflected in three parts: thermal energy value, pure quality value of condensed water and pollution reduction value. Although the engineering investment of new projects and renovation projects is different, the value of condensed water is different due to different power equipment, steam cost and even the value of condensed water. Take the coal-fired boiler as an example (the steam cost of fuel oil and natural gas is relatively high), the steam cost is generally 60-90 yuan/ton, and the annual value of condensed water per ton: when the equipment runs continuously, the annual value of condensed water saved is about 654.38 million yuan; When the equipment runs intermittently, the value of condensed water is saved by about 50,000 yuan every year. Due to the different condensate recovery schemes, the operating cost varies greatly, but the power consumption required for condensate recovery is far less than the value of the recovered heat energy and softened water. Condensed water is directly used as the recovery system of boiler drum feed water, and the operating electricity fee of the recovery device can partially offset the operating electricity fee of the original boiler feed water pump. The operating cost of the recovery system with condensate as deaerator water supply is the electricity fee of the condensate pump of the recovery device. When the condensed water is used for heating or other purposes, the specific thermal energy analysis is carried out according to the specific application. Through the technical transformation of condensed water energy saving, it can not only bring good energy saving effect and objective economic benefit, but also produce good environmental and social benefits.

(1) Reduce environmental thermal pollution

At the moment when the condensed water is discharged into the atmosphere from the steam equipment, due to the sudden drop of pressure, a large number of secondary flash steam is generated, and the high-temperature condensed water sprayed with flash steam is very easy to burn the field operators. In winter in the north, due to the low ambient temperature, it is easy to form a fog curtain, which affects the sight of pedestrians. In summer, it is an accomplice to the high temperature of the environment.

(2) Reduce the emission of smoke and harmful gases.

The recovery of waste heat is accompanied by the reduction of heating. For coal-fired boilers, it means that coal consumption is reduced, smoke emission is reduced, and harmful gases CO2 and SO2 are also reduced accordingly.

(3) Improve the overall level of energy utilization in China.

Because the application of steam thermal system is very common, it is widely used in almost all kinds of industries. At the same time, the recovery of condensed water is limited by specific production conditions and recovery technical conditions, and the recovery rate is generally low. Therefore, the energy efficiency can be greatly improved by implementing the energy-saving transformation of condensed water recovery, which is very important to alleviate the pressure of energy demand and environmental pressure in China.