JPH11322810A - Reflux condenser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vertical type shell-and-tube reflux condenser without any fear of sticking of a polymer to all the condensing tubes and with the substantial absent deviation in flow rate of a fluid to be condensed among the respective condensing tubes. SOLUTION: This reflux condenser 1 is provided with a structure for fitting orifice mouthpieces 4 in the form of a headed cork stopper having a through-hole bored in the central axis direction into inlets of the upper parts of condensing tubes 2, forming orifices 5, forming a liquid reservoir part in a stepped part between the top surface of a horizontal partition plate 6 and the tops of the heads of the orifice mouthpieces 4 and overflowing a cooling medium introduced from a cooling medium feed pipe 3 installed in the upper part of the condenser 1 from the liquid reservoir part to the top openings of the head parts of the orifice mouthpieces 4 in the shell-and- tube type condenser 1 equipped with a condenser tube bundle comprising many substantially vertical straight tubular heat exchanger tubes and supported on a pair of the upper and lower horizontal partition plates 6... and capable of making a fluid which to be condensed and fed from the upper part of the condensing tubes 2 flow in the downward direction through the interior of the condensing tubes 2 and condensing the fluid to be condensed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a reflux condenser, for example, to a reflux condenser used for cooling an .alpha.-olefin or a solvent vapor generated in the polymerization of an .alpha.-olefin.

[0002]

2. Description of the Related Art Conventionally, a general multi-tube vertical or horizontal reflux condenser or the like has been used for cooling vaporized vapor generated when an α-olefin is polymerized, and passes through the reflux condenser. The heat of polymerization is intended to be removed by indirectly cooling the condensable fluid by a cooling medium and returning the condensed liquid to the inside of the polymerization tank. In order to prevent a decrease in heat transfer coefficient due to the adhesion of the reaction product polymer to the heat transfer surface of the condenser, which is a problem when using this type of reflux condenser, the upper part of the tube plate on the inlet side of the vertical condenser is prevented. A method of spraying a condensate of the vapor prepared in advance is known (for example, see Japanese Patent Publication No. 7-17705).

[0003]

However, in the method of spraying the condensed liquid onto the upper part of the condenser, it is difficult to uniformly spray the condensed liquid on each condenser tube when the condenser is enlarged, and the position of the condensed liquid is difficult. However, there is a problem that the effect of washing the adhered polymer becomes insufficient and a condensing tube having a reduced heat transfer coefficient is generated. Also, even in the initial operation state where the adhesion of the polymer is small, when a vertical condenser is used, the starting point is that the average gas linear velocity in the pipe is extremely low, and the gas flow rate passing through each condensation pipe is biased. This eventually causes a condensing tube in which the downward flow is obstructed and the heat removal performance cannot be obtained. In the present invention, reflux does not cause a polymer to adhere to all the condenser tubes, does not impair the heat transfer coefficient, and has substantially no gas flow deviation between the condenser tubes as described above. It is intended to provide a condenser.

[0004]

That is, the gist of the present invention is as follows.
A condensing tube bundle composed of a number of substantially vertical straight heat transfer tubes is supported by a pair of upper and lower horizontal separators, and condensed fluid supplied from the upper portion of the condensing tube flows downward in the condensing tube. In a multi-tubular condenser that is circulated and condensed, an orifice base having a shape like a cork with a head having a through-hole formed in the center axis direction is fitted to the upper inlet of the condenser tube to form an orifice, In addition, a liquid reservoir is formed at a step between the upper surface of the horizontal diaphragm and the upper end of the head of the orifice base, and the cooling medium introduced from the cooling medium supply pipe provided at the upper part of the condenser receives the liquid from the liquid pool through the head of the orifice base. A reflux condenser characterized by a structure that overflows to the upper end opening,
The inner surface of the condensing tube can be efficiently cleaned, and thereby has a feature that the polymer can be prevented from adhering to the inner surface of the condensing tube.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
FIG. 1 is an explanatory view showing a part (upper) longitudinal section of the reflux condenser of the present invention, and FIG. 2 is an explanatory view showing a pilot facility incorporating the reflux condenser of the present invention. In the reflux condenser 1 of the present invention, an orifice base 4 shaped like a cork with a head having a hole with an inner diameter smaller than the inner diameter of the condenser tube is fitted to the upper inlet of each condenser tube 2. Except for this, there is no significant difference from the vertical multi-tube reflux condenser as described above, that is, a generally used vertical multi-tube heat exchanger. The position of the upper end of the head of the orifice base 4, that is, the height protruding from the upper surface of the horizontal partition 6 is not particularly limited, and may be any height at which a sufficient liquid reservoir can be formed on the horizontal partition 6. Good. Generally speaking, a condenser having a height of about 0.1 to 10 times the diameter of the condenser tube is used. Further, the diameter of the hole of the orifice base 4 may be any as long as a required flow velocity can be obtained. Generally speaking, one having a diameter ratio of about 0.3 to 0.7 times the inner diameter of the condenser tube is used. The shape of the hole of the orifice base may be various, such as a cylindrical head or a prismatic head, but is not particularly limited. In short, it is sufficient if there is a head projecting from the horizontal partition plate to form a liquid pool portion, and the thin portion has a shape that fits into the condensation tube.

The cooling medium introduced from the upper part of the horizontal diaphragm 6 is a liquefied α-olefin introduced into a polymerization tank as a raw material of the polymer, for example, ethylene, propylene, butene or the like, or generated by heat of polymerization. A part of the condensed liquid of the vaporized vapor is used, and the cooling medium is introduced onto the horizontal partition 6 from the cooling medium introduction nozzle 3 shown in the figure. Although no special specifications such as dispersing the liquid to be introduced are required at the tip of the nozzle 3, it is desirable to introduce the liquid to a position where there is no condensation tube immediately below. The cooling medium introduced from the nozzle 3 onto the horizontal partition 6 forms a liquid pool at a step between the horizontal partition 6 and the upper end opening of the orifice base 4. The projecting length from the horizontal diaphragm 6 to the upper end of the head of the orifice base 4 is designed to be uniform. The liquid overflows to the upper end opening of the orifice base, and all the inner surfaces of the condensing tubes are liquid. It flows down while forming a film, and flows down to the outlet while washing from the upper end of the inner surface of the condenser tube.

[0007]

EXAMPLES Next, specific embodiments of the present invention will be described with respect to the effect of cleaning the inner surface of the condenser tube of the reflux condenser according to the present invention, but the present invention is not limited to the following examples unless the gist is exceeded. It is not limited by.

Example 1 The effect of the present invention was verified by experiments using a pilot facility shown in FIG. In FIG. 2, a raw material liquefied propylene, a molecular weight modifier such as hydrogen, and a polymerization catalyst were supplied to a polymerization tank 9 to carry out continuous polymerization. The vaporized vapor gas due to the heat of reaction is first introduced into the condenser 1, which liquefies the gas which is easily condensed in the vessel, and separates the gas into gas and liquid by the next drum 7.
And a non-condensable gas is heated by a blower 8 and returned to the polymerization tank 9 to remove heat. The liquefied propylene as a raw material is introduced into the condenser from the cooling medium introduction nozzle 3 of the condenser 1, a liquid pool is formed on the horizontal partition plate 6, and the liquid is fitted to the upper inlet of each of the condenser tubes 2. (Die hole diameter D1 / condenser tube inner diameter D2 = 0.
The liquid was allowed to overflow to the opening at the upper end of the head of 5), and the inner surface of the condenser tube was caused to flow down while forming a liquid film. The specifications of the condenser 1 include a shell inner diameter of 450 mm, a condenser tube length of 3 m, and the number of condenser tubes;
240 polypropylene tubes, outer diameter of the condensing tube: 19 mm, and the inner volume of the polymerization tank 9 was 3 m ³ to produce polypropylene at 500 kg / H. At this time, the heat generated by the polymerization was 250 Mcal / H.
Almost all of the heat was removed using the condenser 1. After continuously producing polypropylene for 3 months under these conditions,
When the condenser 1 was opened and inspected, adhesion of a solid polymerization product was hardly observed on the inner surface of the heat transfer tube.

[Comparative Example 1] In the above pilot facility, the same conditions as those of the embodiment were used except that an ordinary condenser having no orifice cap fitted to the inlet of the condenser tube was used as the condenser 1. When the polymerization reaction was carried out, the overall heat transfer coefficient of the condenser was remarkably reduced after about three months of operation, and an open inspection revealed that solid polymerized products adhered to almost all of the inner surfaces of the condenser tubes.

[0010]

According to the method of the present invention, it is possible to prevent a component such as a polymer contained in the gas to be condensed from adhering to the inner surface of the condenser tube. Also, the condenser specification can be freely designed by changing the hole diameter of the orifice base. And α
-In the production of an olefin polymer, it can be maintained for a long period of time without impairing the heat removal capacity of the reflux condenser, and is particularly valuable in industrial production.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a vertical cross section of an upper part of a reflux condenser of the present invention.

FIG. 2 is an explanatory diagram of a pilot facility to which the reflux condenser of the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reflux condenser 2 Condenser tube 3 Cooling medium introduction nozzle 4 Orifice base 5 Orifice 6 Horizontal partition plate 7 Gas-liquid separation drum 8 Blower 9 Polymerization tank 10 Pump

Claims (1)

[Claims] 1. A condensing tube bundle comprising a plurality of substantially vertical straight tube heat transfer tubes supported by a pair of upper and lower horizontal diaphragms, and condensing a fluid to be condensed supplied from an upper portion of the condensing tube. In a multi-tube type condenser that circulates through the pipe in the downward direction and condenses it, an orifice base shaped like a cork stopper with a head with a through hole in the center axis direction is fitted to the upper inlet of the condenser pipe. An orifice is formed, and a liquid pool is formed at a step between the upper surface of the horizontal partition plate and the upper end of the head of the orifice base. The cooling medium introduced from a cooling medium supply pipe provided at the upper part of the condenser receives the liquid pool. The reflux condenser has a structure that overflows from the upper end opening of the orifice base.