Refrigeration – Intermediate fluid container transferring heat to heat... – Flow line connected transfer fluid supply and heat exchanger
Reexamination Certificate
2000-06-08
2002-01-01
Doerrler, William C. (Department: 3744)
Refrigeration
Intermediate fluid container transferring heat to heat...
Flow line connected transfer fluid supply and heat exchanger
C062S065000, C062S335000
Reexamination Certificate
active
06334332
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a low temperature waste crushing system for crushing waste tire, plastics, etc., by taking advantage of cold shortness, specifically a system effectively utilizing a cascaded refrigerating system.
2. Description of the Related Art
A crushing method taking advantage of cold shortness in which iron and steel materials, etc., are cooled by, for example, very low temperature cooling medium such as liquid nitrogen below their cold shortness transition temperature to reduce them to a brittle state like glass, and crushed, is disclosed in Japanese Unexamined Patent publication No. Sho 51-39452.
Similarly, in the case of waste tire and plastics and the like, it is enough to cool them below their cold shortness transition temperatures which are about −70° C.~−75° C. for crushing Presently, almost all of the cooling method adopted is to cool them to a very low temperature by spraying liquid nitrogen (−196° C.) on them before crushing.
The conventional crushing system at low temperature using the low temperature liquid nitrogen is shown in FIG.
3
. It is composed of a material supplying section
50
, a heat sink for supplying liquid nitrogen, a liquid nitrogen freezer
52
in which the material
50
a
of about 20° C. supplied from the material supplying section
50
is cooled to be reduced to the frozen material
52
a
of about −130° C. by spraying with liquid nitrogen
51
a
of about −196° C. supplied from the heat sink
51
, and a crushing section
53
in which crushed product
53
a
of about −75° C. is obtained by crushing the frozen material
52
a.
In the liquid nitrogen freezer
52
, liquid nitrogen is sprayed on the material
50
a
and the nitrogen gas gasified through spraying is exhausted to the atmosphere by an exhaust blower or the like not shown in the drawing. In the crushing section
53
, the frozen material
52
a
of about −130° C. is raised in temperature by the heat generated at crushing to be reduced to the crushed product
53
a
of about −75° C.
The conventional method using liquid nitrogen, has the advantage that liquid nitrogen is comparatively cheap and easy to handle. However, it has a problem which makes it not the best system for environmental hygiene because the nitrogen gas used for freezing the waste material for low temperature crushing is exhausted to the atmosphere. Further, in the case liquid nitrogen is used, there is a problem that a stepwise cooling of high efficiency is not possible and that a heat sink of −196° C. is used for obtaining a frozen material of about −75° C. or lower which is the glass transition temperature of the material.
Moreover, a cooling mechanism for absorbing the heat generated in crushing is not provided at the crushing section Thus, the frozen material is heated at crushing, and necessitates a setting and securing of the frozen temperature which takes the change of quality of the material due to temperature rise at the crushing into consideration.
To solve these problems of the prior art, an art is disclosed in Japanese Unexamined Patent Publication No. Hei 7-88461. Here, a system for crushing waste household electrical appliances and the like at low temperature by utilizing refrigeration is shown. Firstly, liquid nitrogen is supplied from the lower temperature side and lumps of metal are cooled to below −100° C. by the latent and sensible heat of liquid nitrogen. Then plastic materials are cooled to −40° C. by the sensible heat of the gasified nitrogen. Further, the flon used for flon refrigerating cycle is cooled to −20° C. by the sensible heat of the nitrogen gas after cooling the plastic materials, and the nitrogen gas having finished cooling is introduced to a crushing device to be used as anti-explosion purge gas.
However, also in this prior art, the nitrogen gas used for freezing for crushing at a low temperature is finally exhausted to the atmosphere. Therefore, as is the case with the aforementioned art, this prior art can not be said to be a superior system from the viewpoint of environmental hygiene.
SUMMARY OF THE INVENTION
The present invention was made in light of the problems mentioned above, and an object is to provide a low temperature crushing system without using liquid nitrogen, which reduces burden to the environment in comparison with the prior art of cooling with liquid nitrogen.
Another object of the present invention is to provide a crushing system at freezing low temperature, which enables bringing efficiency to cooling by adopting stepwise cooling along with effective removal of the heat generated at crushing.
The present invention is a low temperature crushing system having a low temperature freezing section, for cooling material below its cold shortness transition temperature (glass transition temperature at which low-temperature embrittlement occurs) by receiving the supply of refrigeration from a heat sink and a crushing section for crushing the material cooled in the low temperature freezing section by taking advantage of cold shortness, and characterized in that
the heat sink is configured as a binary refrigerating cycle combining two different refrigeration cycles, the first refrigerating cycle for obtaining the first refrigeration (hereinafter referred to as higher temperature refrigeration) higher in temperature than the cold shortness transition temperature and the second refrigerating cycle for obtaining the second refrigeration (hereinafter referred to as lower temperature refrigeration) lower in temperature than the cold shortness transition temperature,
the low temperature freezing section is configured as a dual step cooling section, the preceding and succeeding step, each of which received refrigeration of different temperatures, and
the preceding step of the dual step cooling section is supplied with the higher temperature refrigeration of the first refrigerating cycle and the succeeding step is supplied with the lower temperature refrigeration of the second refrigerating cycle.
The binary refrigerating cycle is preferably configured as a cascaded binary refrigerating cycle combining two different cycles, the first refrigerating cycle for obtaining the higher temperature refrigeration and the second refrigerating cycle for obtaining the lower temperature refrigeration by introducing the higher temperature refrigeration to its condenser.
Further preferably, the cascaded binary refrigerating cycle comprises a higher temperature condensing unit configured as the first refrigerating cycle which uses ammonia as a refrigerant and a lower temperature condensing brine unit configured as the second refrigerating cycle which uses a refrigerant of hydrocarbon group such as ethane and methane,
the higher temperature condensing unit supplies a part of the latent heat of vaporization of ammonia refrigerant to the load of the preceding step of the dual step cooling section and at the same time introduces the remainder to the condensing part of the lower temperature condensing brine unit to make the condensing part a cascade condenser, and
the lower temperature condensing brine unit supplies to the load of the succeeding step of the dual step cooling section the low temperature brine cooled in a brine cooler to which the ethane refrigerant condensed in the cascade condenser is supplied.
The two step cooling section suitably comprises:
a pre-cooling room in which the waste material is pre cooled by the first cooling air which is produced by supplying the higher temperature refrigeration of the first refrigerating cycle to the air cooler of the preceding step and is higher in temperature than the cold shortness transition temperature; and
a lower temperature cooling room in which the pre-cooled waste material is cooled to a temperature lower than the cold shortness transition temperature by the second cooling air which is produced by supplying the lower temperature refrigeration to the air cooler of the succeeding step and is lower in temp
Hirano Yukio
Hirao Yasuhiro
Ito Kazutoshi
Matsuda Seiichiro
Yamamoto Makoto
Doerrler William C.
Mayekawa Mfg. Co., Ltd.
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