JPS5835397A - Method for changing over number of circulations through passages in finned multi-pipe type heat exchanger - Google Patents

Abstract

PURPOSE:To maintain a predetermined flow velocity in a passage at a heat-transmitting part and prevent a heat exchanger from generating a malfunction or an accident, by a method wherein the number of circulations through the passage in a heat exchanger is changed over at a predetermined value of the change ratio of operating conditions of the heat exchanger. CONSTITUTION:At the time of operating under a rated load, at gated partition walls 11-14 provided in an inlet chamber 6' for a heat-transmitting medium (sea water) at an end of the heat exchanger and a turning-back chamber at the other end, only a valve 11' is closed and the other valves are opened. As a result, the cooling sea water W1 of about 30 deg.C used as the heat- transmitting medium eneters the chamber 6', passes through about one half of cooling pipes 1, turns back in the chamber 7' at the other end, passes through the rest of the pipes 1, enters a downstream-side partitioned chamber partitioned by the valve 11', and flows out as sea water W2 heated to about 38 deg.C. At the time of operating under 75-50% load, the flow rate q1 of sea water is set to be 1/2-1/4W1, the valve 11' is opened, the other valves 12'-14' are closed, and the number of circulations of q1 through the passage is set at 4. Accordingly, the flow velocity of the sea water in the passage becomes 2q1/W1 times, namely, 1-1/2 times of that under the rated load, so that a flow velocity higher than the scaling limit can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention provides a heat exchanger that is installed as a part of a system when the load heat exchange amount or the rate of change in the heat exchange fluid flow rate is large beyond a certain level. Exchanger performance 2
It concerns a rational method for making functions follow it.

Heat exchangers change the temperature of the heat medium and exchange fluid, respectively.

Appropriate constituent materials depending on usage conditions such as pressure and flow rate.

It goes without saying that there are heat transfer coefficients and flow velocities at each part. Conventionally, the conventional method is to make the heat medium flow rate follow changes in the operating conditions of the heat exchanger, but if the rate of change exceeds a certain limit, it goes without saying that the performance 9 functions of the heat exchanger will be adversely affected. Depending on the physical properties of the fluid and heat medium being handled, there are many cases in which serious failures such as overall or local overheating, inadequate cooling, salting out, or local blockage occur.

This invention converts the number of circulations in the internal flow path at a constant value of the rate of change in the operating conditions of the heat exchanger.
To provide a practical method that can prevent malfunctions and accidents by maintaining an appropriate flow rate in a heat transfer section, such as doubling or quadrupling the number of circulations in the flow path in response to a halving of the flow rate. It's something.

A specific example will be explained below. FIG. 1 is an explanatory diagram conceptually showing a conventional type of supercharger intercooler for a diesel engine as a main marine propulsion engine.

High-temperature air of 200'0 degrees Celsius compressed by an exhaust turbine supercharging device, etc. flows into the intercooler air inlet 4 as shown in A1, is cooled by the seawater cooling tube bundle 1, increases its density, becomes about 50 degrees Celsius, and becomes air. It flows out from the outlet 5 in the direction of A2.

On the other hand, as a heat medium, cooling seawater w1 of about 30°O enters the inlet chamber 6 from the tube joint 9, passes through about half of the cooling tubes 1, and is intermediately collected in the turning chamber 7 at the other end, where it is turned back.

It flows through the remaining half of the cooling pipes 1, enters the downstream partition chamber partitioned by the partition wall 8, and flows out w2 which has received heat of about 38° C. from the pipe joint 1o. 2 and 3 indicate tube plates, which serve as dividing walls between the air side and seawater side.

Since seawater is generally used as a cooling medium, it is an absolute requirement to prevent build-up in the cooling pipes.
The maximum seawater temperature within the jurisdiction is approximately 45℃.

Currently, it is necessary to maintain the flow velocity in the pipe at about 0-5 rv's or higher. In recent years, energy conservation has become an increasingly urgent issue, and the cruising speed of ships has become lower and lower, and we are now in an era where ships are cruising at about 50% of their rated output.

Therefore, the rate of change from the rating at that time will be significant as shown below, and continuous operation at a partial load will be required, with the amount of perfusion being reduced by almost half and the amount of heat exchanged being approximately %. If the above request is met using the conventional method, the amount of cooling seawater W will be approximately
The flow velocity in the pipe decreases compared to the rated value, resulting in a fall below the 2-force limit speed, making continuous operation extremely dangerous. Therefore, at present, the seawater volume W1 is kept at a certain value higher than that.

The current situation is that a compromise is being taken to deal with the air M, which has become lower than necessary. This invention solves the above-mentioned current problems. The explanatory diagram of FIG. 3 will be explained.

Figure 2 shows rated load, Figure 3 shows 75 to 50% of 2 rated load.
FIG. 6 is an explanatory diagram of a case where the number of passage circulations at a rated load is switched between at a partial load and at a rated load.

At the time of rated load, as shown in Fig. 2, the heat exchanger was provided at the heat medium seawater population M6' and the other end turned back N7'. Partition walls with respective openings 11.12. Among 13 and 14, valve 11'
Since the valves 12', 13', and 14' are opened, the flow of seawater w1 is exactly the same as in FIG. 1. in this case.

The size of each valve opening, i.e. the flow capacity, is determined by the valve 14'
The other valves 11', 12' and 13' are for W1/2.Please note that the opening shape, size, position of attachment to the partition wall, etc. The selection shall be made rationally.

When the load is 75 to 50 inches, open and close the outer valve shown in Figure 3.

The number of circulations in the seawater channel has been converted to twice that in Figure 2. That is, when the seawater flow rate q1 is (3A -%) Wl, the valve 11' is opened, and the other valves 12', 13' and 14 are opened.
The number of circulations in the flow path for q+ is 4. In this case, the seawater velocity in the pipe is W at the rated load, X 2, and e
'(Hk (3A~K) Wl) The flow velocity in the pipe is (1~A) of the flow velocity at rated load, and it is possible to make the flow velocity higher than the limit of the bonding force in the pipe.If necessary, the number of circulations of seawater in the pipe can be changed. 6. It is also possible to use casing 8 or 8 with the same idea as above.

Therefore, the load range is not limited to 50%, and it is possible to provide a heat exchanger with stable functions even when the load is reduced as necessary. These conversion valves.

Rotating shafts 11 and 12τ13' and 14', respectively, are installed at positions eccentric to the opening of the upstream chamber of the partition wall, and the shaft ends, which pass through the heat exchanger wall in an airtight manner, are rotated manually or automatically or with other power to rotate the front and back of the partition wall. Due to the fluid pressure difference, there is no difficulty in opening and closing the valves as closed-handed valves, and if necessary a suitable switching device can also be integrated into the heat exchanger. These valves can be easily closed by the fluid pressure acting on each part, and have a structure with ample space in the opening/closing eccentric shaft and in the closing direction, so that it is easy to maintain watertightness between the valve seat and the valve seat. It is. It should be noted that a small amount of leakage from the valve seat does not impair the original purpose in any way. The valve has a structure that allows it to be closed easily, making it easy to touch the valve seat and making the opening/closing machine simple and compact.The valve can also be kept airtight even against slight vibrations, making it suitable for relatively small indoor installations. It has the practical advantage of being equipped with minimal fluid resistance.

The method for converting the number of times the heat medium circulates through the flow path has been described above, but the method for converting the number of times the heat exchange fluid circulates through the flow path can also be performed in the same manner as described above.

Some of the effects of this invention have been described above, but by providing a method that can change the number of circulations in the flow path of a finned multitubular heat exchanger at any time without stopping its operation within the container. This also results in the ability to expand the operating range of the entire system including the heat exchanger, leading to the advantage of being able to select the optimal operating conditions from among them without restriction. The effect of providing a method that can stably obtain performance 1 function of a finned shell-and-tube heat exchanger over a wide range from the rated load to the lowest partial load 1 is considerable.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram conceptually showing a conventional type of intercooler of a supercharging device of a diesel engine as a main engine for marine propulsion;
Fig. 2 is a conceptual explanatory diagram of an intercooler having the same purpose as Fig. 1 in which the method of the present invention is implemented at rated load, and Fig. 3 shows that the intercooler t-c in Fig. 2 is loaded with 50 cm. FIG. 2 is a conceptual explanatory diagram when the number of circulations in the heat medium seawater flow path is converted to 4. 1...Seawater cooling tube bundle, 2,3...
tube plate. 4...Intercooler air inlet 5...Intercooler air outlet. 6.6'...Cooling seawater inflow chamber. 7.7'... Cooling seawater turning room, 8-. Conventional partition wall. 11, 12. 13.14...Partition wall provided with an opening in the method of this invention. 11:12z13;14'... Opening/closing valve for the partition wall opening in the method of this invention. 11τ12? 13τ14'., Rotating shaft for opening and closing the on-off valve in the method of this invention. A1...High temperature inlet air, A2...Cooled low temperature air. Wl...Inflow cooling seawater, Wl...Outlet seawater. al...High temperature inlet air during partial load. a2...cooled down! cold air. ql...Inflow cooling groove X during partial load, q2...
・Outlet seawater. Patent applicant: Kiyoshi Konaka - ■Suction Gas Engine Manufacturing Co., Ltd.

Claims (2)

[Claims] (1) A multi-tubular heat exchanger with fins is characterized in that openings that can be opened and closed are provided in the flow path circulation partition walls of the inflow and outflow chambers for the heat exchange fluid and/or the fluid to be heat exchanged. A method for converting the number of circulations in a finned multitubular heat exchanger. (2) In Paragraph 1 of Section 4I, the valve body that opens and closes the opening provided in the partition wall of the fluid inflow and outflow base is operated by a rotating shaft located at an eccentric position on the upstream side of the partition wall opening, so that it can be closed easily. A method for converting the number of circulations in a finned multitubular heat exchanger configured to open and close as a valve.