JPS6021765B2 - Gas temperature and flow rate control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an automatic control device for keeping the flow rate and temperature of gas, particularly heated gas, constant.

(Prior art) Conventionally, the temperature of a heat treatment furnace (coating machine, drying furnace) is 120 to
2000○, and the temperature control range is ±5℃, but the exhaust gas contains harmful gas (flammable gas) and a lot of tar substances, and although it saves energy when it is circulated through slag treatment, it also contains a lot of impurities. This has an adverse effect on the product and reduces the yield of the product.

Therefore, as a method of removing impurities, we installed a removal device using a catalytic type, direct combustion method, etc., and tried to recirculate the purified gas (air) through this device to the heat treatment furnace. Due to its own oxidation and decomposition heat, temperature fluctuations are large, and even if the exhaust gas is purified, it cannot be used. For this reason, when using recirculation,
The main fuel system is controlled within a range that does not affect the heat treatment temperature, or a portion of the high-temperature exhaust gas is discharged, and only the temperature is controlled (in this case, a heat exchanger is provided).

), but in order to reuse the entire amount of purified exhaust gas, it is difficult to use it unless both the temperature and flow rate are controlled. In other words, in order to adjust both the flow rate and temperature, it is necessary that the gas flowing out to the detection part on the outflow side be in a constant state, but if the gas is unstable as a whole, it is impossible to detect and control is difficult. be. Another drawback is that in order to keep this constant, a device having a long distance in the direction of gas flow is required.
(Problems to be Solved by the Invention) The present invention improves the above-mentioned subordinates, reduces the installation cost when using recirculation, reduces the overall capacity of the device, and reduces temperature fluctuations. The aim is to enable recirculation by controlling the flow rate and temperature within ±3%, and also by controlling the flow rate and temperature within 3%.

(Means for solving the problem) Therefore, the gas (air) from which impurities flowing in from the heat treatment furnace and the gas (air) supplied from the outside are uniformly mixed approximately in the middle of the inside of the equipment, and the gas (air) supplied from outside is mixed uniformly. In addition to setting the temperature of the amalgam, a partition wall is provided to keep the flow rate constant, and gas with a constant temperature and flow rate flows out to the outflow side, making it easy to detect and adjust the temperature.

Note that the gas on the inflow side has a certain pressure. (Function) With the above configuration, when pressurized gas flows in from the inflow side of the device, gas is simultaneously replenished from the air supply side.
After being uniformly mixed to form a gas at a predetermined temperature, a mass equal to the amount of air supplied is discharged from the exhaust pipe, and this gas is discharged from the outflow side as a flow in a fixed direction, at a constant temperature, and at a constant flow rate. Since the temperature can be detected under the same conditions at any position on the outflow side, the air supply and exhaust amounts can be adjusted by detecting this at any position.

(Example) This will be explained using an example shown in the drawings.
Reference numeral 1 denotes a main body of the device, and the inside of the device 1 is divided into two sections, and the central portion of each section is provided with an air supply pipe 2 for introducing new air from the outside and an exhaust pipe 3 for partially exhausting air.

The left side of the device 1 is an inflow side A, and the right side is an outflow side B, in which air flows in the direction of the arrow. 4 is a temperature detection section provided on the outflow side B, which uses a thermocouple with a CA wire 230 protection tube.

Reference numeral 5 denotes a butterfly damper provided in the air supply pipe 2, which is operated by a proportional control motor 6.

7 is a mixing chamber where the air sent from the heat treatment furnace (drying furnace) is purified, flows in from the inflow side A, and is mixed with the air supplied from the air supply pipe 2. During mixing, the inside of the mixing chamber 7 is Since the pressure is maintained, the introduction from the air supply pipe 2 is a natural introduction.

Therefore, the pressure in the mixing chamber 7 is approximately 1 to 1 Ag (water column) due to the pressure loss between the butterfly damper 5 and the fine adjustment damper 8.
The negative pressure must be greater than or equal to 9 is a control room;
The exhaust pipe 3 for partial exhaust is provided in the upper part, and a butterfly damper 12 and a fine adjustment damper 13 operated by a proportional control motor 6 are provided to keep the discharge flow rate on the outflow side constant. , the amount of flow supplied from the air supply pipe 2 is discharged.

A partition wall is provided between the adjustment chamber 9 and the mixing chamber 7 as a uniform mixing and constant flow section, and in this embodiment, it is constituted by a deflecting plate 10 made of a non-perforated steel plate and a perforated plate 11. The deflector plate 10 occupies approximately 25% of the area from the upper end in the vertical direction, and blocks the sheet pass (passage from the air supply pipe 2 to the exhaust pipe 3) during air supply and exhaust, and prevents the mixing direction of both gases from perpendicular to each other. The perforated plate 11 occupies the entire area in the vertical direction from the lower end of the baffle plate 10, and is used to close the mixing chamber 7 when the pressure of the incoming gas is high or when the gas is at a high temperature.
Since it is difficult to achieve uniform mixing in the perforated plate 11, the purpose is to convert the dynamic pressure of the gas flow into static pressure and make the blowing velocity distribution from the perforated plate 11 uniform. When the flow rate changes due to fluctuations in outside temperature and an error occurs in the set temperature, and the flow rate needs to be adjusted, fine adjustment is difficult with just the butterfly dampers 5 and 12, so the fine adjustment damper 8 of the air supply and exhaust system is used. .13 was used to improve the setting accuracy.

With this configuration, if a temperature change occurs in the gas in front of the inflow side A, the temperature of the gas is changed to the outflow side B.
The temperature detection unit detects the temperature, feeds it back to the temperature indication adjustment system of the device control system, operates the control damper 5 of the air supply pipe 2 by the proportional control motor 6, and introduces both gases into the mixing chamber 7. Perform mixed diffusion.

The gas introduced from the air supply pipe 2 through the baffle plate 10' is not directly connected to the exhaust pipe 3 and exhausted, but instead flows into the mixing chamber 7.
This is to guide the supply air into the tank and mix it uniformly. The gas (air) that has reached a uniform temperature is ejected from the holes in the perforated plate 11, but is forced to maintain a constant flow rate. The gas discharged from the side has a uniform predetermined temperature and a predetermined flow rate in all parts of the outflow side. FIG. 3 schematically shows the recirculation system for inserting this diamond counterfeit.

1 is an apparatus of the present invention, C is a heat treatment furnace such as a drying furnace, D is a catalyst device, 8 is a fan, F is a valve, and G is a heat treatment furnace C.
This is a pipe that guides exhaust gas to the catalyst device D, and the gas flowing through this pipe G contains impurities.

The line is a pipe for recirculating gas at a set temperature and flow rate into the heat treatment furnace C. The exhaust gas containing impurities generated from the heat treatment furnace C has its impurities removed in the catalyst device D, but as mentioned above, it is discharged at a high temperature due to the heat of oxidation and decomposition. 1 into the inflow side A.

Then, supply air (oo~40qo) from the outside,
After uniform mixing, the mixture is discharged from the outflow side as a constant flow in a fixed direction. Therefore, if this is recirculated and sent to the drying oven, since the temperature is constant, there is no need to control the heating of the drying oven by just setting the temperature, and the exhaust gas can be reused. The device can be extremely small. (Effect of the invention) As described above, this invention consists of
'I' The capacity of the device is small, the mixing and diffusion times are short, and the return to the set value is short (actually measured in 7 minutes).

[o- Since the air supply and exhaust pipes are provided, the temperature setting can be adjusted and set to any desired temperature.

1. Since exhaust gas can be recirculated with high accuracy (±3%), product yield is improved.

B: Since the set value fluctuates only slightly, consumption of fuel for heating gas in a drying oven or the like can be suppressed as much as possible.

Since the entire device can be made smaller, the cost can be lower than that of conventional devices. It has excellent effects such as.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional side view of an embodiment of the present invention, FIG. 2 is a front view of the intermediate wall section, and FIG. 3 is a recirculation system equipped with the device of the present invention. 1... Device body, 2... Air supply pipe, 3... Exhaust pipe, 4
...Temperature detection section, 5, 12 ... Butterfly damper, 6 ... Proportional control motor,
7... Mixing chamber, 8, 13... Fine adjustment damper, 9... Adjustment chamber, 10... Deflector plate, 11... Porous Plate, A...Inflow side, B
... Outlet side, C ... Drying oven, D ...
...Catalyst bag counterfeit, E...Fan, F...
・Valve, G, day...Pipeline. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 Equipped with a supply and exhaust pipe whose supply and exhaust volume is adjusted by a temperature detection section installed on the outflow side, and a gas flow uniformly mixed inside the device,
A constant flow partition is provided to uniformly mix the gas from the inflow side and the gas supplied from the air supply pipe, and the same flow rate as the air supply is discharged from the exhaust pipe. A gas temperature and flow rate control device that controls fluctuations in the flow rate at a constant level on the outflow side.