JP3186865B2 - Cleaning method for one-pass evaporation plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a one-pass type evaporating plate, and more particularly to a method for cleaning a plurality of one-pass type evaporating plates and a heating plate which is stacked on the evaporating plate by a gasket. The present invention relates to a stationary cleaning method for a plate-type heat exchanger composed of plates.

[0002]

2. Description of the Related Art As a device for concentrating a liquid to be processed, a plate-type heat exchanger is used in which a plurality of one-pass evaporation plates and heating plates are alternately stacked via a gasket. FIG. 3 shows a plate heat exchanger (1), a separator for gas-liquid separation (2), a condenser (3), a vacuum generator (4), a liquid supply pump (5), and a concentration pump comprising a removal pump (6). 2 shows the overall structure of the device (10). This concentrator (1
The plate heat exchanger (1) used in (0) has an inlet (7) for the liquid to be concentrated at the bottom of the plate as shown in FIG.
A), the outlet for the concentrated liquid (7B), and the outlet for the drain (8) are opened, and the heating vapor inlet (11) and the inlet for the liquid to be concentrated (7A) are directed upward at the top of the plate. The upper end of the extending liquid passage (9) is opened, and the first gasket (12) is used to introduce the heating vapor inlet (11) and the drain outlet (8), and to introduce the liquid to be concentrated. A one-pass type evaporating plate (13), which is shut off between the opening (7A) and the outlet (7B) of the liquid to be concentrated, and a second communicating with the heating vapor inlet (11) on the evaporating plate (13) side. And a heating plate (not shown) having a second drain outlet communicating with the drain inlet (8) on the side of the evaporation plate (13) and the first gasket (12). The second steam inlet and the second drain outlet on the heating plate side Concentrating means is formed by laminating every other via a second gasket (not shown) provided with a seal pattern communicating with the outlet.

Next, as a background art of the method of the present invention, a concentration operation by the above-mentioned concentration device (10) will be described with reference to FIG.

[0004] An exhaust port (2A) above the separator (2) is connected to a vacuum generator (4) via a condenser (3). After starting the vacuum generator (4) and generating a negative pressure suction force in the plate type heat exchanger (1), the liquid supply pump (5) is started and the lower part of the heat exchanger (1) is introduced. The liquid to be concentrated (14) heated to a predetermined temperature is introduced from the port (7A). The liquid to be concentrated (14) introduced into the heat exchanger (1) flows upward in the flow path (9), overflows from the upper end opening thereof, makes a U-turn, and then turns the one-pass evaporation plate (13). It flows downward while dispersing in the form of a thin film along the heat transfer surface, and during this time, the heat energy supplied from the heating plate side evaporates the water in the liquid to be concentrated. The liquid to be concentrated (14) concentrated to a predetermined concentration by evaporating water flows out from the outlet (7B) and is supplied to the separator (2). The solid content and the gas component in the liquid to be concentrated (14) are separated into gas and liquid by utilizing the centrifugal action of the separator (2), and the evaporation vapor is discharged from the exhaust port (2A). The evaporative vapor is liquefied by being cooled in the condenser (3) and discharged out of the system. On the other hand, the liquid to be concentrated (14) remaining at the lower part of the separator (2) is taken out of the concentrator (10) by the take-out pump (6).

[0005] While the above concentration operation is being performed, an inlet (11) provided above the plate heat exchanger (1).
The heating steam (15) introduced from below flows downward along the surface of the heating plate as shown by reference numeral (15) in FIG.
The liquid to be concentrated (14) flowing down along the heat transfer surface of the evaporation plate (13) is heated to evaporate water. The heated steam (15) that has released heat energy becomes drain and discharges (8)
And is discharged out of the system from the lower part of the heat exchanger (1).

During the above-mentioned concentration operation, the temperature of the liquid to be concentrated (14) flowing along the heat transfer surface depends on the negative pressure suction from the vacuum generator (4), that is, the effect of the reduced pressure suction. Receiving drops. For this reason, the liquid to be concentrated (14) flowing on the evaporation plate (13) is maintained in a so-called flash evaporation state in which the liquid evaporates rapidly, and the liquid to be concentrated (14) sent out from the flow path (9). Is distributed almost uniformly over the entire area in the height and width directions above the evaporating plate (13), and flows down along the heat transfer surface of the evaporating plate (13) while maintaining this thin-film dispersion state. I do.

[0007] The liquid to be concentrated (14) is concentrated in this way. When a predetermined operation time has elapsed, the heat transfer surface of the evaporation plate (13) is added to the heat exchanger (1). It is necessary to perform a washing treatment to remove solids, scale, and the like attached to the surface. As a washing method, there is a disassembly / wash / reassembly method. In general, considering the complicated structure of the heat exchanger (1) and time and labor required for disassembly and assembly, the evaporating plate (13) is used. ) And the heating plate without disassembling, and as shown in FIG. 4B, hot water or a cleaning chemical (2) is placed inside the heat exchanger (1) in an assembled state.
A stationary cleaning method is adopted in which 1) is injected to dissolve and remove solids and the like adhering to the heat transfer surface.

In the stationary cleaning method, after the concentration of a predetermined amount of the liquid to be concentrated (14) is completed, hot water or a cleaning chemical (21) is introduced into the heat exchanger (1) through the inlet (7A). There are two types of cleaning: introduction and cleaning under the atmospheric pressure at the heat transfer surface of the evaporating plate (13) under atmospheric pressure, and cleaning under a negative pressure, in which the cleaning operation is performed while using a cleaning solution instead of the liquid to be concentrated. .

[0009]

When the cleaning method under the atmospheric pressure is adopted, since the heat exchanger (1) is only kept at the atmospheric pressure, the hot water or the cleaning chemical is flash-evaporated. A state is not achieved and dispersion is hindered. For this reason, the hot water and the cleaning chemical (21) do not spread over the entire heat transfer surface of the evaporating plate (13), and a dry area is generated as shown in FIG. Solids and scale (16) remain attached to the upper part of the heat transfer surface near the upper end opening.

In the cleaning operation under a negative pressure, the cleaning can be performed almost completely, that is, it flows along the heat transfer surface of the evaporation plate (13) by utilizing the negative pressure suction from the vacuum generator (4). A mixture of heated steam and hot water or a cleaning chemical is maintained in a flash-evaporated state, thereby improving the dispersion function and removing solids and scale (16) adhering to the top of the evaporating plate (13). As described above, washing under a negative pressure consumes power for generating a negative pressure and energy of heating steam, requires a concentration operation, and is accompanied by a problem of an increase in washing cost.

[0011]

The present invention as described above SUMMARY SUMMARY In order to achieve the above, a plurality of one-pass type evaporator plate, Ri Do from laminated heating plate every one via a gasket to the one-pass type evaporator plate , The above one-pass type steam
The heating plate is for heating which is surrounded by a gasket at the upper end.
Having a vapor inlet and a liquid to be concentrated toward the inlet;
In the stationary washing operation of the plate heat exchanger having the upper end outlet of the flow path opened, the concentration of the one-pass evaporating plate is reduced.
After introducing air into the liquid supply line to the contraction liquid flow path and dispersing the air in the cleaning liquid, the mixture of the air and the cleaning liquid may be used to remove solids or the like adhering to the upper surface of the heat transfer surface of the evaporation plate. An object of the present invention is to provide a one-pass type evaporating plate cleaning method characterized by cleaning and removing scale.

[0012]

[Function] When performing stationary cleaning on a heat exchanger in which a plurality of one-pass evaporation plates and heating plates are alternately stacked via a gasket, air is injected into a liquid supply line of the one-pass evaporation plate. The cleaning liquid and air are simultaneously supplied to the heat transfer surface of the evaporation plate. Despite not using a vacuum generator, hot water or cleaning chemicals blow out vigorously on the upper heat transfer surface of the evaporating plate, which tends to dry when air is injected, as if flash evaporation. Are distributed over the entire area. As a result, no dry area is generated on the heat transfer surface of the one-pass type evaporation plate, and the cleaning effect is greatly improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In the following description, the same constituent members as those shown in FIGS. 3 and 4 showing the prior art are denoted by the same reference numerals, and the description of the same items will be omitted.

An air introduction pipe (18) is connected in a branched state to a liquid supply line (19) connecting the liquid supply pump (5) and the inlet (7A) of the liquid to be concentrated (14).

At the time of stationary cleaning, air of 0.2 to 0.3 kg / cm ² G is supplied from the air introduction pipe (18) to the liquid supply line (19).
The air (20) is injected into the heat exchanger (1) through the inlet (7A) together with the cleaning chemical or hot water (21). The mixture of the air (20) and the cleaning chemical or hot water (21) flows upward in the flow path (9) and blows out from the upper end opening onto the upper heat transfer surface of the one-pass evaporation plate (13). The state of dispersion of the cleaning chemical or hot water (21) on the upper heat transfer surface of the evaporating plate (13) was visually checked, and air (20) was mixed in the cleaning chemical or hot water (21). ,
As in the case of flash evaporation, a cleaning chemical or hot water (21) spouts vigorously as in flash evaporation, and is dispersed over the entire heat transfer surface of the evaporation plate (13) as shown in FIG. I found out. It was confirmed that the dispersion behavior of the cleaning chemical or the warm water (21) similar to the flash evaporation was maintained even when the supply amount was narrowed. on the other hand,
When the supply of air (20) was interrupted, it was confirmed that a dry area was generated above the heat transfer surface despite the increase in the amount of liquid supply.

[0016]

According to the present invention, by performing the cleaning operation by injecting the air (20) into the cleaning chemical solution or the hot water (21), the conventional primary cleaning using the cleaning chemical solution or the hot water (21) alone becomes a problem. Of dry area above the heat transfer surface of the evaporating plate (13) and the solid content and scale (16) caused by this
Defective removal is avoided. In addition, since the decompression operation under the supply of heated steam, which was conventionally required in the secondary cleaning, becomes unnecessary, according to the present method, the same effect as the negative pressure cleaning can be obtained in the warm water cleaning (under normal pressure). Energy (steam) for evaporating is unnecessary, and only steam for raising the temperature is sufficient.

Further, since the concentration operation is involved in the washing under negative pressure, the operating temperature is limited, and it is advantageous that the washing can be set to an arbitrary temperature in the case of washing with hot water.

The energy saving effect varies depending on the configuration and capacity of the apparatus, but the amount of steam required for negative pressure cleaning is about 1 because steam is used only for raising the temperature of the cleaning liquid being held.
/ 10 or less.

[Brief description of the drawings]

FIG. 1 is a flow sheet of a concentrator used in the method of the present invention.

FIG. 2 is a partial front view of a one-pass evaporation plate.

FIG. 3 is a flow sheet of a concentrator used in a conventional method.

FIG. 4A is a front view illustrating the entire structure of a one-pass evaporation plate, and FIG. 4B is a partial front view thereof.

[Explanation of symbols]

 Reference Signs List 1 Heat exchanger 7A Inlet for concentrated liquid or cleaning chemical 7B Outlet of concentrated liquid or cleaning chemical 9 Flow path 13 One-pass type evaporation plate 18 Air introduction pipe 19 Supply line 20 Air 21 Cleaning chemical or hot water

Claims (1)

(57) [Claims] 1. A plurality of sheets of one-pass type evaporator plate, Ri Do from laminated heating plate every one via a gasket to the one-pass type evaporator plate, the one-pass type
The evaporating plate is surrounded by the gasket at its upper end
It has an inlet for steam for heating and has a cover facing the inlet.
In the stationary cleaning operation of the plate-type heat exchanger having the upper end outlet of the concentrated liquid flow path opened , air is introduced into a liquid supply line to the concentrated liquid flow path of the one-pass type evaporation plate , and the air is introduced into the cleaning liquid. A method for cleaning a one-pass evaporating plate, comprising: dispersing and then removing a solid content and scale adhering to an upper portion of the heat transfer surface of the evaporating plate with a mixture of the air and the cleaning liquid.