In this project, the waste heat is recovered from the heat treatment furnace, and the waste heat is used to heat the hot water in the pretreatment process. It not only saves the consumption of natural gas, reduces the operation cost of enterprises, brings economic benefits for enterprises, but also indirectly reduces the energy consumption index of unit output value, and reduces smoke emissions and environmental pollution, which is of great significance for energy saving and environmental protection. The policy of energy conservation, emission reduction and development of circular economy will be used to accelerate the pace of technological innovation and promote the rapid, effective and sustainable development of enterprises.
General introduction
The flue gas heat treatment furnace waste heat from the combustion proceeds, the flue gas passes through the heat exchanger, the low temperature water tank gradually heating, back to the water storage tank, heat exchanger using hot water heat exchange will pretreatment bath tank in tank heating process corresponding to the required temperature, to replace the original bath combustion heater, which can save energy and reduce environmental pollution.
1 system composition
1.1 work flow
The flue gas heat exchanger, water storage tank, water pump, heat exchanger, bath bath pump, circulating pump, sump tank
1.2 configuration description
Flue gas heat exchanger: 2
Hot water pump: 2 sets
Water tank: 2, 1 35 tons, 1 45 tons.
Slot liquid exchanger: 5.
Circulation pump: 5 sets, one open and one 10 sets
Slots pump: 5 sets, one open and one 10 sets
Control system: 1 sets, control cabinet box, various high and low voltage electrical components, PLC, temperature control instrument and so on.
Other spare parts: hot water pipe, pipe fittings, 316 stainless steel pipe fittings, pipeline
2 technical indicators
Temperature requirements for 5 grooves in the pretreatment process
1) hot water bath: 40-60 C
2) pre degreasing trough: 50-80 C
3) degreasing tank: 50-80 C
4) slots: 30-50 degrees centigrade
5) the passivation tank: 27-55 C
According to the temperature requirements in the upper table, we determine the temperature of the two storage tanks, the temperature of the 35 ton tank should reach 80-85 degrees, and the temperature of the 45 ton tank should reach 60-80 degrees, so as to achieve the temperature requirement of the tank.
3 material selection
Material selection of 3.1 five slots heat exchanger
(1) the concentration and composition of the solution of the five slots are different, listed below:
1) hot water bath: tap water
2) predegreasing trough: concentration 5-10%
The composition of the original liquid is as follows
Borate (Borate) <4g/l
Carbonate (Carbonate) <4g/l
Phosphate (Phosphate) <6g/l
Alkali (alkali) <4g/l
Surface active agent (surfactants) <2.5g/l
3) degreasing tank: the composition and concentration are the same as the pre degreasing groove.
4) surface adjustment slot: concentration 1.5%-3%
Components of the original liquid (unit: g/l)
Sulphuric acid (Sulfate Acid) <12
Fluoride (fluoride) <6
5) passivating tank: chromium free passivating agent, concentration 1-6%
Components of the original liquid (unit: g/l)
Zirconium (Zirconium) <1
Fluoride (fluoride) <1
Organic matter (organic materials) <3
(2) because of the high requirements for the material of the heat exchanger, the material of the five slot liquid heat exchanger is as follows:
1) hot water bath: 316L
2) pre degreasing slot: 316L
3) defat tank: 316L10
4) slots: 254SMO10
5) the passivation slot: 254SMO10
Selection of material for heat exchange pump with 3.2 tank and slots
There are 20 pumps for heat exchange between the tank and the tank. There are 10 circulating pumps and 10 slot pumps.
The slots pump should be made of 316L special material.
Selection of material for 3.3 pipeline
Galvanized pipe hot water pipe with steel pipe fittings. A 316L pipe is used in the slot pipe.
4 functional characteristics
According to the temperature and capacity of each tank, and the number of tank fluids added every hour, the heat source needed to heat the tank is continuously replenishing the loss of heat and achieving a certain equilibrium point.
According to the difference of the temperature of the tank slots, it is divided into two storage tanks.
The water storage of a tank is 45 tons, and the temperature is 60-80. The tank is heated to the bath of hot water, the tank and the bath of the passivation tank. Because of the hot water tank overflow 1000KG hour hot water, big water, temperature fluctuations, water volume of 45 tons of water storage tank washing water can meet the temperature requirements, but also can satisfy the temperature adjustable table slot, passivation tank requirements, and the tank tank temperature reaches the equilibrium and stability.
The water storage of another tank is 35 tons, and the temperature is 80-85. The tank is heated to the pre degreasing tank and the trough liquid of the degreasing tank. Because the temperature stability of the pre degreasing tank and the degreasing tank is high, and the temperature range is narrow, it is necessary to ensure that the outlet temperature of the flue gas heat exchanger reaches above 85 degrees, so as to ensure the temperature of the storage tank.
The heating of the tank liquid is heated by the hot water of the storage tank through the tank liquid heat exchanger. The heat exchanger of the tank can ensure the temperature of the bath, and will not mix the hot water with the bath liquid, that is, it achieves the function of heating the bath and keeping the bath liquid clean. The heat exchanger of different materials is selected to ensure the long term use of the heat exchanger because of the different composition of the liquid.
The flue gas heat exchanger heat the flue gas to heat exchange water, and also heat the tank cycle, and it has reached the use temperature of the tank. All water storage tanks, heat exchangers, hot water pipes, and slots pipes are insulated. The automatic control system is used to monitor the water storage tank, the flue gas heat exchanger, the trough liquid heat exchanger, the tank liquid and so on, and the water level of the reservoir.
