JP6167650B2 - Plate heat exchanger and maintenance method thereof - Google Patents

Description

  The present invention relates to a plate heat exchanger and a maintenance method thereof, and more particularly to a plate heat exchanger and a maintenance method thereof that can prevent contamination of a plate surface due to oil contained in a heat exchange medium.

Conventionally, a coke oven gas (hereinafter referred to as “C gas”) generated when coal is charged into a coking chamber of a coke oven and dry-distilled (hereinafter referred to as “C gas”) contains a lot of fuel components such as hydrogen, methane, carbon monoxide, Since it has a high calorific value exceeding 20000 kJ / m ³ , it is recovered from the carbonization chamber via a riser pipe and reused as fuel gas for blast furnaces, coke ovens, heating furnaces, and boilers. Since the coke oven gas contains components such as tar, sulfur compounds and nitrogen compounds in addition to the above-mentioned carbon monoxide, the coke oven gas is usually used as a fuel gas after purification to remove them.

  As described above, C gas is generated by dry distillation of coal. However, since C gas at the time of generation is very high and has a large volume of 1000 ° C., it is difficult to purify it as it is. Therefore, the generated C gas is first sent to the cooling process of the C gas refining equipment to lower the temperature, and after cooling to about 35 ° C, unnecessary solid oil, nitrogen compounds and sulfur compounds are removed as fuel gas Sent to the purification process.

In the process until the purification of the C gas is completed, water in which the ammonia compound is dissolved is discharged. This waste water is collected as cold water, and is used, for example, in the cooling step to cool the C gas at the beginning of generation. However, surplus water is discarded after being treated. FIG. 1 is a diagram illustrating a treatment flow of surplus water. First, the excess safe water 1 and the distillation steam 20 are supplied to the ammonia stripper 2, the ammonia is removed as a gas component and exhausted, and the safe water from which the ammonia has been removed is discharged as de- water 3. Is done. The ammonia gas exhausted here is incinerated in a combustion furnace.

  On the other hand, the deaerated water 3 discharged from the ammonia stripper 2 is supplied to the activated sludge facility 6 and subjected to the activated sludge treatment, and then discharged outside the factory. In order to prevent the bacteria in the sludge from being killed, it is necessary to cool to about 40 ° C. However, since the deaerated water 3 discharged from the ammonia stripper 2 has a high temperature of about 100 ° C., the deaerated water 3 is introduced into the heat exchanger 5 by the pump 4 before being supplied to the activated sludge facility 6. Cool to about 40 ° C.

The heat exchanger 5 for cooling the deaerated water 3 includes a multi-tube type (for example, see Patent Document 1), a spiral type (for example, see Patent Document 2), and a plate type (for example, see Patent Document 3). However, a plate-type heat exchanger is generally used because of its excellent heat transfer performance and efficient heat exchange. In this plate heat exchanger, a plurality of heat transfer plates are stacked via a sealing material, a first space in which a high-temperature heat exchange medium flows between the heat transfer plates, and a low-temperature heat exchange medium. A plurality of second spaces to be circulated are alternately formed, and a plurality of first spaces and a plurality of second spaces are in communication with each other, a high-temperature heat exchange medium that circulates through the first spaces, and a second It is configured to exchange heat with a low-temperature heat exchange medium circulating in the space.

  However, when the deionized water 3 is supplied to the plate heat exchanger and cooled, oil such as tar contained in the deanized water 3 is solidified as the deanized water 3 is cooled, and the heat exchanger 5 is configured. As a result, the surface of the heat exchanger 5 adheres and becomes dirty, causing problems such as blocking the inside of the heat exchanger 5 and pitting the plate. Therefore, before supplying the deaerated water 3 to the heat exchanger 5, the deaerated water 3 is subjected to a pretreatment such as oil-water separation to remove the oil contained in the deaerated water 3 in advance. Alternatively, a spare heat exchanger (not shown) is separately provided and the deaerated water 3 is supplied to the spare heat exchanger, and then supplied to the heat exchanger 5.

JP-A-6-221792 JP-A-5-264181 Japanese Patent Laid-Open No. 5-71886

However, even if the treatment such as the oil-water separation is performed, the oil component cannot be sufficiently removed from the dewatered water 3, and the plate is still dirty or the exchanger 5 is blocked. Further, the method for cost for preliminary heat exchanger not only occur, but not to perform fundamental cope with oil contained in de ammonia liquor 3, pre heat exchange to provide a pre-heat exchanger bowl itself oil contamination is caused by contained in de ammonia liquor 3, it is not turned at all to solve the problem has been a problem.

Thus, there has been a demand for establishment of a method capable of preventing contamination of the plate surface due to oil contained in a heat exchange medium such as low water.
SUMMARY OF THE INVENTION An object of the present invention is to provide a plate heat exchanger that can prevent contamination of the plate surface due to oil contained in the heat exchange medium and a maintenance method thereof.

  As a result of intensive investigations on how to solve the above problems, the inventor provides a plurality of laminated oil adhesion prevention sheets on the surface of the heat transfer plate constituting the plate heat exchanger that contacts the heat exchange medium. Has been found to be effective, and the present invention has been completed.

That is, the gist of the present invention is as follows.
(1) heat transfer plates of the plurality of sheets are stacked through a sealing material, between the heat transfer plates cross, and the second space to the first space and the heat exchange medium to be a heat exchange medium containing oil circulates flows Are formed alternately, and the plurality of first spaces and the plurality of second spaces are respectively communicated, and the heat exchange medium that flows through the second space and the heat exchange medium that flows through the first space. In the plate heat exchanger for exchanging heat with the medium, each of the heat transfer plates prevents the oil from adhering to the heat transfer plate on the surface of the heat transfer plate on the first space side. have a stacked plurality of oil adhesion preventing sheet, several sheets of oil adhesion preventing sheet plurality is that it is laminated between sheets is adhered by the adhesion with not using an adhesive, the sheet material Pre-characteristic Door heat exchanger.

(2) The plate heat exchanger according to (1), wherein the oil adhesion prevention sheet is a fluororesin sheet.

(3) In maintaining the plate heat exchanger according to (1) or (2), the plate type of each of the heat exchange medium and the heat exchange medium during operation of the plate heat exchanger. The temperature at the time of inflow and outflow to the heat exchanger is periodically measured, and after each measurement, the measured temperature at the time of inflow and outflow of the heat exchange medium and the heat exchange medium, and the heat exchange medium And calculating the heat transfer coefficient of the heat transfer plate from the flow rate of the heat exchange medium, and when the calculated heat transfer coefficient is below a predetermined value, the operation of the plate heat exchanger is stopped and disassembled, A maintenance method for a plate heat exchanger, wherein the oil adhesion prevention sheet on a heat transfer plate is peeled off to remove the oil adhered to the oil adhesion prevention sheet.

According to the plate heat exchanger of the present invention, a plurality of laminated oil adhesion prevention sheets for preventing oil adhesion are provided on the surface of the heat transfer plate that contacts the heat exchange medium containing oil. Therefore, adhesion of oil to the heat transfer plate can be prevented, and as a result, pitting corrosion of the heat transfer plate and blockage of the heat exchanger can be prevented.
Further, according to the plate heat exchanger maintenance method of the present invention, the heat transfer performance of the heat exchanger is periodically monitored, and when the heat transfer performance is below a predetermined level, the heat exchanger is operated. In order to remove the oil adhering to the oil adhesion preventing sheet by stopping, the heat exchanger can be operated under high heat transfer performance.

It is a figure which shows the processing flow of surplus cheap water. It is a figure which shows an example of the heat exchanger plate which comprises the plate type heat exchanger which concerns on this invention. It is a figure explaining the flow of the to-be-heat exchange medium and heat exchange medium in the plate type heat exchanger which concerns on this invention.

(Plate heat exchanger)
Hereinafter, the present invention will be described in detail with reference to the drawings. The plate-type heat exchanger according to the present invention includes a first space and a heat exchange medium in which a plurality of heat transfer plates are stacked via a sealing material, and a heat exchange medium containing oil flows between the heat transfer plates. And a plurality of first spaces and a plurality of second spaces are connected to each other, and the heat exchange medium flowing through the first space and the heat flowing through the second space are alternately formed. It is a plate-type heat exchanger that exchanges heat with an exchange medium. Here, it is important that each of the heat transfer plates has a plurality of laminated oil adhesion prevention sheets that prevent oil from adhering to the heat transfer plate on the surface of the heat transfer plate on the first space side. is there.

  FIG. 2 is a view showing an example of a heat transfer plate constituting the plate heat exchanger according to the present invention. The heat transfer plate 11 shown in this figure has a substantially rectangular shape, and at its four corners, there are two passage holes 12 through which a high-temperature heat exchange medium containing oil, such as water-safe, circulates. And two through holes 13 through which a low-temperature heat exchange medium that receives heat from the heat exchange medium flows.

  A plurality of the heat transfer plates 11 are stacked via the sealing material 14, and as a result, the first space 16 and the heat exchange medium 17 in which the heat exchange medium 15 containing oil flows between the heat transfer plates 11. A plurality of second spaces 18 that circulate are alternately formed. The plurality of formed first spaces 16 and the plurality of second spaces 18 are communicated with each other through the passage holes 12 or 13, and flow through the heat exchange medium 15 and the second space 18 that flow through the first space 16. The heat exchange medium 17 is configured to exchange heat.

  In the present invention, each of the heat transfer plates 11 is attached to the heat transfer plate 11 on the surface of the heat transfer plate 11 on the first space 16 side through which the heat exchange medium 15 containing oil flows. A plurality of stacked oil adhesion prevention sheets 19 to be prevented are provided. The oil adhesion prevention sheet 19 is a sheet that prevents the heat exchange medium 15 containing oil such as tar from adhering to the surface of the heat transfer plate 11.

  As the oil adhesion prevention sheet 19, a sheet made of an arbitrary material can be used as long as the oil contained in the heat exchange medium 15 can be prevented from adhering to the surface of the heat transfer plate 11.

  The oil adhesion preventing sheet 19 is preferably thin, and can be several tens of μm, for example. Further, the number of stacked sheets 19 is not particularly limited, and an appropriate number of sheets may be stacked. It is preferable not to use an adhesive for laminating the sheets 19, but to laminate the sheets by adhering them due to the adhesion of the sheet material.

  FIG. 3 is a view for explaining the flow of the heat exchange medium 15 and the heat exchange medium 17 in the plate heat exchanger according to the present invention. As shown in this figure, an oil adhesion preventing sheet 19 is provided on the surface of each heat transfer plate 11 on the first space 16 side through which the heat exchange medium 15 containing oil flows. On the other hand, the oil adhesion prevention sheet 19 is not provided on the surface of each heat transfer plate 11 on the second space 18 side through which the heat exchange medium 17 flows.

  As described above, the oil adhesion preventing sheet 19 can prevent oil such as tar contained in the heat exchange medium 15 from directly adhering to the surface of the heat transfer plate 11, and thus pitting corrosion of the heat transfer plate. And blockage in the heat exchanger can be prevented.

  In the plate heat exchanger of the present invention described above, the oil adhesion preventing sheet 19 preferably has wettability on the surface in contact with the heat exchange medium 15. Thereby, the oil contained in the heat exchange medium 15 can be prevented from adhering to the oil adhesion preventing sheet 19 itself, and the maintenance cycle of the heat exchanger can be increased.

  As such an oil adhesion preventing sheet 19, it is preferable to use a fluorine resin sheet such as polytetrafluoroethylene, polychlorotrifluoroethylene, or polyvinylidene fluoride because of its good wettability and easy peeling.

(Maintenance method for plate heat exchanger)
Next, a maintenance method for the plate heat exchanger according to the present invention will be described. First, during the operation of the plate heat exchanger according to the present invention described above, the temperatures at the inflow and outflow of the heat exchange medium 15 and the heat exchange medium 17 into the respective plate heat exchangers are periodically measured. To do. This measurement cycle can be set to one month, for example.

  After each of the above measurements, the heat transfer coefficient of the heat transfer plate 11 is calculated from the measured inflow and outflow temperatures of the heat exchange medium 15 and the heat exchange medium 17 and the flow rates of the heat exchange medium 15 and the heat exchange medium 17. To do.

  When the calculated heat transfer coefficient falls below a predetermined value, the operation of the plate heat exchanger is stopped and disassembled, and one oil adhesion prevention sheet 19 on each heat transfer plate 11 is peeled off to adhere the oil content. The oil adhering to the prevention sheet 19 is removed.

  Thus, the heat transfer performance of the heat exchanger is regularly monitored, and when the heat transfer performance is below a predetermined level, the heat exchanger is stopped and the oil adhering to the oil adhesion preventing sheet 19 is removed. In order to eliminate, the plate heat exchanger can be operated under high heat transfer performance.

DESCRIPTION OF SYMBOLS 1 Raw safe water 2 Ammonia stripper 3 Dehydrated water 4 Pump 5 Heat exchanger 6 Activated sludge equipment 11 Heat transfer plate 12, 13 Passing hole 14 Sealing material 15 Heat exchange medium 16 1st space 17 Heat exchange medium 18 2nd space 19 Oil adhesion prevention sheet 20 Steam for distillation

Claims (3)

The heat transfer plates of the plurality of sheets are stacked through a sealing material, between the heat transfer plates cross, and a second space alternately first space and the heat exchange medium to be the heat exchange medium circulates flows containing oil The plurality of first spaces and the plurality of second spaces are respectively formed and communicated, and the heat exchange medium that circulates through the first space and the heat exchange medium that circulates through the second space. In a plate heat exchanger that exchanges heat between
Each of the heat transfer plate, the first space-side surface of the heat transfer plates, have a plurality of oil adhesion preventing sheet which is laminated to prevent adhesion to the heat transfer plate of the oil, the The plate-type heat exchanger, wherein the plurality of oil content adhesion prevention sheets are laminated by adhering sheets according to the adhesion of the sheet material without using an adhesive .   The plate heat exchanger according to claim 1, wherein the oil adhesion prevention sheet is a fluororesin sheet. In maintaining the plate heat exchanger according to claim 1 or 2,
During the operation of the plate heat exchanger, the temperatures of the heat exchange medium and the heat exchange medium when flowing into and out of the plate heat exchanger are periodically measured, and measured after each measurement. The heat transfer coefficient of the heat transfer plate is calculated from the inflow and outflow temperatures of the heat exchange medium and the heat exchange medium, and the flow rates of the heat exchange medium and the heat exchange medium. When the heat coefficient is lower than a predetermined value, the operation of the plate heat exchanger is stopped and disassembled, and the oil adhering prevention sheet on each heat transfer plate is peeled off to remove the oil adhering to the oil adhering prevention sheet. A maintenance method for a plate heat exchanger, characterized in that it is removed.

Images