JPS592840B2 - Automatic water washing device for rotary regenerative heat exchanger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic water washing device for a rotary regenerative heat exchanger attached to a boiler, flue gas denitrification or desulfurization equipment, and is a rotary regenerative heat exchanger that can perform water washing even while the boiler is operating. The purpose of this invention is to provide an automatic water washing device for a heat storage rotating body of a container.

A rotary regenerative heat exchanger is normally attached to a boiler and stores the heat of the boiler exhaust gas in a rotating body, preheating the boiler combustion air to save heat and labor.Recently, from the perspective of preventing air pollution, , it is required to further install a denitrification or desulfurization device in the boiler to remove nitrogen oxides or sulfur oxides from the boiler exhaust gas.

However, the products of such denitrification or desulfurization equipment accumulate on the rotary heat storage body built in the rotary regenerative heat exchanger, and the adverse phenomenon of clogging the body occurs very clearly.

To remove deposits on the rotating body, water is usually sprayed from a nozzle installed on the heat exchanger to wash away the deposits on the rotating body. The heated or heated fluid that passes through the rotating heat storage body at a constant speed causes the water sprayed for rinsing to scatter, causing failures due to corrosion or blockage of the boiler or attached dust collector, etc., or during operation due to rinsing water. In order to prevent breakdowns due to thermal shock caused by temperature differences in the heat exchanger, boiler operation is generally stopped and flushing is performed during that time.The frequency of flushing is once a year. That was enough.

However, from the viewpoint of air pollution prevention mentioned above, the installation of denitrification or desulfurization equipment has come to be required, and the amount of deposits generated from chemicals in such pollution prevention equipment has increased, and the frequency of water washing required has also increased. It is extremely uneconomical to stop the operation of the boiler every time the boiler is flushed, and there is a strong desire to develop a flushing device that can operate even while the boiler is running.

The present invention has been developed and proposed in response to such demands.

The automatic water washing device for a rotary regenerative heat exchanger according to the present invention is installed in a rotary regenerative heat exchanger and detects the differential pressure between the inlet and outlet of the passing exhaust gas flow, and detects the pressure difference between the inlet and the outlet of the passing exhaust gas flow, A differential pressure detection device that detects blockages caused by objects, a boiler load detection device that detects the boiler load from the boiler fuel flow rate and corrects the value obtained by the differential pressure detection device, and a rotating device built into the heat exchanger. A rotation detection device detects the number of rotations of the body, and a corrected differential pressure detection device instructs to switch the electric motor for driving the rotating body to an air motor based on the value obtained by the corrected differential pressure detection device. It consists of a control device that instructs and operates the water washing device according to the number of washers.

Next, details of one embodiment of the automatic water washing device for a rotary regenerative heat exchanger according to the present invention will be explained with reference to the drawings.

Figure 1 is a flow sheet showing the layout of boiler ancillary equipment to which this invention should be applied; 1 is the boiler, 2 is the
is a dry denitrification device, 3 is a rotary regeneration type heat exchanger, 4 is a dust collector, 5 is a chimney, and 6 is a blower. Combustion air is sucked from the atmosphere by the blower 6, passes through a duct 7, and is transferred to a rotary regeneration type heat exchanger. After being introduced into the heat exchanger 3 and preheated, it is sent into the boiler 1 through the duct 8 in the direction of the arrow.

On the other hand, the exhaust gas from the boiler 1 passes through the duct 9 and comes into contact with ammonia in the dry denitrification device 2, where nitrogen oxides in the exhaust gas are reduced and removed.Then, the exhaust gas is sent to the rotary regenerative heat exchanger 3, which has a built-in After the combustion air is preheated, the combustion air is sent to the dust collector 4, where the dust is completely collected and purified, and then released into the atmosphere through the chimney 5. It is something that will be done.

As already mentioned, the exhaust gas from the boiler 1 contains dust such as soot, which is deposited on the heat storage rotor built in the rotary regenerative heat exchanger 3. S injected ammonia is present in the exhaust gas
It reacts with O3 and H2O in a rotating body at a temperature of about 250-150°C to form a molten (NH4)2SO4 or NI(,H
8O4 is generated, which accumulates in the form of mud on the heat storage plate of the heat exchanger rotating body, and finally ends up clogging the heat storage plate. As usual, there is no need to stop the operation of the boiler (an automatic flushing device that can flush the boiler with water is required).

10 is a differential pressure detection device, which is one of the components of the present invention, which detects the static pressure at the exhaust gas inlet and outlet of the heat exchanger, detects an increase in pressure drop from the differential pressure, and detects the blockage due to deposits on the rotating body. Detects the occurrence of the phenomenon.

It is not always possible to accurately detect a blockage phenomenon of a rotating body only by detecting a pressure loss using the differential pressure detection device.

This is because the pressure drop changes due to a change in the flow rate of exhaust gas due to a change in the load on the boiler 1.

Therefore, in order to accurately detect the blockage phenomenon, in the present invention,
Boiler fuel flow meter 11 to detect boiler load
The flow rate of fuel in the boiler is detected, the value obtained by the differential pressure gauge 10 is corrected, and when the corrected pressure loss value exceeds a predetermined value, a signal indicating the occurrence of blockage is sent to the control device 12.

The control device first turns off the power to the electric motor 13 for driving the rotating body of the heat exchanger 30 to stop it, and then instructs the air on-off valve 14 to open and sends air to the air motor 15. Activate it.

The rotation speed of the rotor of the heat exchanger suddenly decreases when the air motor drive is switched, and the rotation detection device 16 detects that the rotation speed has become 1/15 rpm, and the signal instructs the water flow closing valve 17. Then, the valve is opened, water is supplied to the nozzle 18, and washing of the rotating body is started.

The control device 12 is equipped with a timer (not shown), and the required time for flushing is normally set within one hour, and when the predetermined time has elapsed, the boiler closes the water flow valve and closes the air valve as described above. A signal is sent to the valve and electric motor power supply to stop the water washing and restore normal operation in the reverse order described above.

As mentioned above, the reason for switching the drive of the rotating body of the heat exchanger and the electric motor to an air motor during washing is to reduce the number of revolutions of the rotating body and to reduce the amount of dissolved deposits caused by washing by reducing the rotation speed of the rotating body to a low speed of 1/15 rpm. This is to prevent scattering and adhesion to the inside of the heat exchanger and auxiliary equipment, thereby preventing staining and corrosion.

Fig. 2 is an enlarged side view of the rotary regenerative heat exchanger and its auxiliary equipment for ease of understanding. 3 is the rotary regenerative heat exchanger, and 19 is the heat storage rotor built in it. , 13 is a driving electric motor, 15 is an air motor, 18 is a rotating body washing nozzle, 20 is an exhaust gas duct, 21 is a boiler combustion air duct, and other equipment is the same as that shown in FIG. .

Since the present invention has the above-described structure, it is possible to automatically wash the rotary regenerative heat exchanger with water without stopping the operation of the boiler, so it is extremely effective in terms of heat saving and pollution prevention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow sheet showing the arrangement of an automatic water washing device for a rotary regenerative heat exchanger according to the present invention, and FIG. 2 is an enlarged side view thereof. Incidentally, the symbols of the main parts in the figure are as follows. 1...Boiler, 2...Dry denitration equipment, 3...Rotary regenerative heat exchanger, 4...
Dust collector, 5...Chimney, 6...Blower
17...Duct, 8...Duct, 9.
...Duct, 10...Differential pressure detection device, 1
1...Boiler fuel flow meter, 12...
Control device, 13...Electric motor for driving rotating body, 14...Air opening/closing valve, 15...Air motor, 16...Rotation detection device, 17・・・
...Water flow valve closed, 18...Nozzle, 19...
... Heat storage rotating body, 20 ... Exhaust gas duct,
21...Boiler combustion air duct.

Claims (1)

[Claims] 1. In a rotary regenerative heat exchanger attached to a boiler, flue gas denitrification or desulfurization equipment, a differential pressure detection device installed in the heat exchanger, and a boiler load that corrects the differential pressure value obtained by the device. A detection device, a rotation detection device that detects the rotation speed of the rotating body of the heat exchanger, instructs the electric motor for driving the rotating body to be switched to the air motor based on the value obtained by the differential pressure corrected within the detection device, and further controls the rotation of the rotating body. A rotation system comprising a control device that instructs and operates a water washing device according to a predetermined rotational speed obtained by a detection device, thereby automatically washing the rotating body of the heat exchanger with water while the boiler is operating. Automatic water washing equipment for regenerative heat exchangers.