JPS6182870A - Energy conservation process in continuous painting line of steel sheet - Google Patents

Abstract

PURPOSE:To produce painted steel sheets having stable quality by controlling generated heat obtd. by utilizing fume to be generated from a painted steel sheet in a drying furnace as heat source comparing to the necessary heat, automatically. CONSTITUTION:Generated fume from painted film of painted steel sheets 2B in a drying furnace 7 is burnt in a combustion furnace 10, and hot waste gas generated by the combustion of the fume is utilized as heat source for the drying furnace 7 and pretreating devices of the painting work. In this stage, the amt. of fuel to be fed to a burner of the combustion furnace 10 is controlled automatically so as to result coincidence of generated heat from the hot waste gas to the heat required for drying furnace 7 and for the pretreatment. By this constitution, the temp. opf the drying furnace and the pretreating devices are kept at appropriate temps. Thus, painted steel sheets having stable quality are obtd.

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention collects and incinerates fumes generated from the paint film of painted steel sheets in the drying furnace of a continuous steel sheet painting line, and feeds the high-temperature exhaust gas back to the drying furnace. The present invention relates to an energy-saving method for using the heat source as a heat source as well as a heat source for painting pretreatment equipment. ``Prior Art'' In general, in a continuous steel plate coating line, as shown in FIG. The copper plate is passed through a tank 4, and a chemical conversion film layer is formed on the surface of the copper plate 2A to be coated using the chemical solution in the chemical solution tank 4. After that, it is dried in a dryer 5, and then passed through a coater 6 to be coated. The coated steel plate 2B is passed through a drying oven 7 to be dried, and then wound up on a take-up reel 8. When the painted steel plate 2B is dried in the drying oven 7, fume is generated from the coating film due to evaporative decomposition of the resin and solvent in the coating. Conventionally, the fume generated in the drying oven 7 is collected from the drying oven 7 via an intake fan 9 to an incinerator 10, as shown in FIG. 3, for example, and is incinerated in the incinerator 10. A part of the high-temperature waste (700 to 800°C) of the fume incinerated in the incinerator 10 is transferred to the drying furnace 7.
The remaining high-temperature exhaust gas is used as a heat source for the hot water boiler 11, and the rest is used as a heat source for the hot water boiler 11.
It becomes exhaust gas at a relatively low temperature of ~200°C and is released to the outside air. The hot water boiler 1] includes a pump

Water from the hot water tank 13 is circulated through [2 and the primary circulation pipe 13a], and is heated by the high-temperature exhaust gas as a heat source to the hot water boiler 1], and the water in the hot water tank 13 is heated to the required temperature. As a result, heat is stored in the hot water tank 13. Thermal energy stored in the hot water tank 13 is transferred to the pump 1
4 and the heat exchanger 15 through the secondary circulation line 13b, and the heat exchanger 15 from the coating pretreatment equipment, for example, the chemical liquid tank 4 via the pump 16 and the circulation line 4a.
It is used as a heat source for heating the chemical liquid that is being circulated to the plant. "Problems to be solved by the invention" By the way, the conventional energy saving method, in other words,
Regarding the means of utilizing high-temperature exhaust gas from hume incineration in the incinerator 10, when the hume collected from the drying oven 7 to the incinerator 10 is incinerated in the incinerator 10, the production volume and production type (plate thickness) of the coated steel sheet 2B are , paint film thickness, paint type, paint solvent type), the amount of fume collected per unit time from the drying furnace 7 to the incinerator lO, and the drying furnace 7 and painting pretreatment equipment, -
For example, without considering the required heat consumption per unit time in the chemical liquid tank 4, fuel is supplied to the burner of the incinerator 10 at a set flow rate proportional to the maximum amount of fume recovery per unit time based on conventional operational experience. 10a was being supplied to incinerate Huyum. In the production of painted steel sheet 2B, the following types of painted steel sheet 2
It is extremely rare that the amount of heat generated in high-temperature exhaust gas per unit time when producing B under specified manufacturing conditions is almost in equilibrium with each required amount of heat consumed per unit time. Depending on the type, the amount of heat consumed per unit time is often significantly insufficient or excessive compared to the amount of heat generated by high-temperature exhaust gas per unit time. As mentioned above, if the required amount of heat consumed per unit time is significantly reduced compared to the amount of heat generated by high-temperature exhaust gas per unit time due to a change in production type, the amount of heat generated by high-temperature exhaust gas becomes excessive. Therefore, the temperature of the drying oven 7 and the chemical liquid temperature in the chemical liquid tank 4 become higher than necessary, and the coated steel plate 2
This may have an adverse effect on the product quality of E and the chemical conversion treatment properties of the chemical liquid, and will result in wasteful consumption of burner fuel. Furthermore, as mentioned above, if the required amount of heat consumed per unit time increases significantly compared to the amount of heat generated by the high-temperature exhaust gas per unit time, the amount of heat generated by the high-temperature exhaust gas becomes too small, and therefore the drying furnace 7 The temperature and the temperature of the chemical solution in the chemical solution tank 4 fell below the required level, which could have an adverse effect on the product quality of the coated steel sheet 2B and the chemical conversion treatment properties of the chemical solution. Therefore, conventionally, workers have to check the temperature of the chemical liquid in the chemical liquid tank 4, the temperature of the drying furnace 7, the temperature of the incinerator 10, and the temperature of the hot water tank 13.
The temperature of hot water inside the incinerator 10 was measured, and the flow rate of fuel supplied to the burner 10a of the incinerator 10 was manually adjusted based on the measurement results. Therefore, in response to changes in the required heat consumption of the drying furnace 7 and the chemical liquid tank 4 due to changes in the production volume of coated steel sheets 2B and production types, the burner 10a can be used in a short time and accurately.
Since it is not possible to adjust the flow rate of fuel supplied to the steel sheet, there is a problem in that it is difficult to manufacture coated steel sheet 2B with stable quality. "Means for Solving the Problems" The present invention is intended to solve the problems of the conventional art, and its configuration will be explained below based on FIG. 1. As shown in FIG. 1, the fume generated from the coating film of the coated steel sheet 2B in the drying furnace 7 of the continuous steel sheet coating line is collected and incinerated in the incinerator 10, and the high-temperature exhaust gas is sent to the drying furnace 7. In addition to being used as a feedback heat source, the high temperature per unit time in the incinerator 10 is used as a heat source for heating the chemical liquid Pg4, for example, via the hot water boiler 1, the hot water tank 13, and the heat exchanger 15. The amount of heat generated in the exhaust gas, the amount of heat consumed per unit time in the drying furnace 7, the hot water tank 13, the chemical liquid tank 4, etc., the production amount of the coated steel sheet 2B, and the appropriate drying temperature of the drying furnace 7 determined by the product type and chemical conversion. The comparator 17 compares and calculates each set value of the appropriate liquid temperature of the liquid tank 4, and based on the comparison calculation value, calculates the amount of heat consumed per unit time required by the drying oven 7 and the chemical liquid tank 4. - The amount of fuel supplied to the burner 10a of the incinerator IO is controlled via the controller 18 so that the amount of heat generated from the high-temperature exhaust gas matches. Note that the amount of heat consumed per unit time of the drying oven 7 is calculated by the comparison calculator 17 from the change in the temperature on the supply side of the high-temperature exhaust gas and the change in the temperature on the hume recovery side in the drying oven 7. Further, the amount of heat consumed per unit time of the hot water tank 13 is calculated from the temperature change of the circulating water in the primary side circulation pipe 13a and the temperature change of the circulating water in the secondary side circulation pipe 13b in the hot water tank 13. It is calculated by Further, the amount of heat consumed per unit time in the chemical liquid tank 4 is calculated by the comparison calculator 17 from the temperature change of the circulating chemical liquid on the inlet and outlet sides of the circulation pipe 4a in the chemical liquid tank 4. "Effects of the Invention" As described above, according to the present invention, the fume generated from the paint film of coated steel sheets in the drying furnace of a continuous steel sheet coating line is collected and incinerated in the incinerator, and the high-temperature exhaust gas is dried. In order to use the incinerator as a feedback heat source and also as a heat source for painting pretreatment equipment, the amount of heat generated by the high-temperature exhaust gas per unit time in the incinerator is determined by a drying furnace adapted to the production volume and product type of coated steel sheets. and the amount of heat consumed per unit time required by the painting pretreatment equipment.
Since the amount of fuel supplied to the burner of the incinerator can be automatically controlled, the amount of heat consumed in the drying oven and painting pretreatment equipment can be adjusted to the required value G with a fast response speed when changing the production volume of coated steel sheets and production types, etc. can be rubbed,
Therefore, the temperature of the heat source for the drying oven and painting pretreatment equipment can always be adjusted to the appropriate level, making it possible to produce coated steel sheets of stable quality and optimizing the amount of burner fuel consumed in the incinerator. can.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the method of the present invention, Fig. 2 is a schematic explanatory diagram showing a general example of a continuous coating line for steel plates, and Fig. 3 is a block diagram showing a conventional energy saving means in a continuous coating line for steel plates. It is a diagram. 2 people... Steel plate to be painted 2B... Painted steel plate 4.
...Chemical liquid for painting pretreatment 1a 7...Drying oven i
o...Incinerator 11...Hot water boiler 13...
Hot water tank 15... Heat exchanger 17... Comparison calculator 18... Controller

Claims (1)

[Claims] The fumes generated from the paint film of coated steel sheets in the drying furnace of the continuous painting line are collected in the incinerator and incinerated, and the high-temperature exhaust gas is used as a feedback heat source to the drying furnace and as a heat source to the painting pretreatment equipment. When using the incinerator, calculate the amount of heat generated by the high-temperature exhaust gas per unit time in the incinerator, the amount of heat consumed per unit time in the drying furnace and painting pretreatment equipment, the amount of production of coated steel sheets, and the amount of drying that is appropriate for the product type. Compare and calculate the appropriate temperature settings for the furnace and pre-painting treatment equipment, and based on the calculated value, generate high-temperature exhaust gas in the incinerator that corresponds to the amount of heat consumed per unit time required by the drying furnace and pre-painting treatment equipment. An energy saving method for a continuous coating line for steel plates, which is characterized by controlling the amount of fuel supplied to an incinerator burner so as to maintain the amount of heat.