Refrigeration – Processes – Circulating external gas
Reexamination Certificate
2000-04-24
2001-09-25
Doerrler, William (Department: 3744)
Refrigeration
Processes
Circulating external gas
Reexamination Certificate
active
06293113
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. § 119 of German Patent Application No. 199 19 877.2, filed on Apr. 30, 1999, the disclosure of which is expressly incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cooling system for removing excess process heat and/or machine heat from a paper or cardboard machine.
2. Discussion of Background Information
A device similar in general to the one discussed above is known from International Publication No. WO 97/44523, in which a cooling system of a paper mill uses a cooling tower to reduce the use of cooling water. The cooling tower, in addition to the fresh water flowing through it, takes over a substantial share of the heat removal in the paper mill.
However, one problem of the above-noted device is that, when using such cooling systems in a paper machine, the coolant liquids provided for the cooling function in the machine are usually oily, oil-containing, or other liquids with a high boiling point which may, to an extent, also serve lubrication purposes or are at least intended to protect against corrosion. Generally, these coolant liquids can be harmful to the environment and can also be detrimental to the paper manufacturing process if they reach the process cycle of the paper machine.
SUMMARY OF THE INVENTION
The present invention provides an improved cooling system which offers increased protection against contamination of the process water of a paper or cardboard machine as well as of the waste water that leaves the facility.
According to the invention, a cooling system is provided for removing excess process heat and/or machine heat from a paper or cardboard machine. The cooling system includes at least one closed primary cooling cycle (primary cycle) which removes the excess heat, and each primary cycle has at least one primary fluid/water heat exchanger for transferring the heat to at least one closed secondary cooling cycle (secondary cycle). Each at least one closed secondary cooling cycle includes at least one secondary water/water heat exchanger for transferring the heat of the secondary cycle to a tertiary cooling water path of the paper or cardboard machine. The tertiary cooling water path of the paper or cardboard machine includes a tertiary water/water heat exchanger, as well as a cooling water inlet and a cooling water outlet to and from the tertiary water/water heat exchanger.
An exemplary embodiment of the cooling system according to the invention ensures that, even in the case of leakage of the primary heat exchanger, the cooling fluid (e.g., oil) originating from the primary cycle cannot get into the process water or the waste water. In this manner, an interruption of production due to impurities in the process water or damage to the environment by waste water that is contaminated or polluted with chemicals can be effectively prevented.
An advantageous feature of the cooling system according to the invention provides for the tertiary cooling water path to be a component of a tertiary cooling water cycle (tertiary cycle) and to have a cooling tower that releases the excess heat into the ambient air. Besides providing ecologically advantageous protection against contamination of the environment, this measure also reduces the use of fresh water and, thus, achieves a lower use of natural resources.
In a further embodiment of the cooling system, the tertiary cooling water cycle has a cooling water collection tank through which the cooling water is supplied to the cooling tower and, optionally, can be supplied to the production process. Additionally or alternatively, the tertiary cooling cycle can be provided with an intermediate tank for the cooling water between the cooling tower and the secondary heat exchanger. Naturally, individual units such as the heat exchanger, the tank, and the cooling tower can be interconnected by conduits for transporting the cooling fluid and, optionally, have corresponding feed devices.
These hydraulic buffers, which can be formed as unpressurized, open tanks, can be used to intercept operational fluctuations in the cooling cycle in a simple manner.
Moreover, it is noted that the features of the instant invention can be utilized, not only in the combinations shown in the exemplary embodiments, but also in other combinations or by themselves without departing from the spirit and scope of the invention.
The present invention is directed to a cooling system for removing at least one of excess process heat and excess machine heat from one of a paper and cardboard machine. The cooling system includes at least one closed primary cooling cycle arranged to remove excess heat, at least one closed secondary cooling cycle arranged to remove the excess heat from the at least one closed primary cooling cycle, and at least one primary heat exchanger coupled to each at least one primary cooling cycle for transferring the excess heat from the at least one closed primary cooling cycle to the at least one closed secondary cooling cycle. The cooling device also includes a tertiary cooling water path having a cooling water feed line and a cooling water return line coupled to the one of the paper and cardboard machine, and at least one secondary heat exchanger coupled to the second cooling cycle for transferring the excess heat from the at least one closed secondary cooling cycle to the tertiary cooling water path.
According to a feature of the instant invention, the at least one primary heat exchanger can be arranged within each of the at least one closed primary cooling cycle, and the at least one secondary heat exchanger can be arranged within the at least one closed secondary cooling cycle.
In accordance with another feature of the invention, the primary heat exchanger can include a fluid/water heat exchanger, and the fluid/water heat exchanger can include oil.
According to a further aspect of the invention, the secondary heat exchanger can include a water/water heat exchanger.
In accordance with still another aspect of the present invention, the at least one closed primary cycle can include oil as a heat carrier
Further, a tertiary cooling water cycle can include the tertiary cooling water path and a cooling tower. The cooling tower may be adapted to transfer the excess heat from the tertiary cooling water path to ambient air. The cooling tower can include a fan for transferring the excess heat into the ambient air. The tertiary cooling water cycle can also include a cooling water collection tank coupled to the cooling tower, and the cooling water collection tank can be arranged to supply cooling water to the cooling tower. The cooling water collection tank may be arranged to supply cooling water to a manufacturing process in the one of the paper and cardboard machine. Further, the tertiary cooling water cycle can also include all intermediate tank positioned between the cooling tower and the secondary heat exchanger, in which the intermediate tank includes an inlet for fresh water.
According to still another feature of the present invention, the at least one closed primary cooling cycle can be arranged to cool machine components. The machine components can include at least one of bearings and press rolls.
The instant invention is directed to a process of cooling one of a paper and cardboard machine with an apparatus that includes at least one closed primary cooling cycle, at least one closed secondary cooling cycle, at least one primary heat exchanger coupled to each at least one primary cooling cycle, a tertiary cooling water path comprising a cooling water feed line and a cooling water return line coupled to the one of the paper and cardboard machine, and at least one secondary heat exchanger coupled to the second cooling cycle. The process includes removing excess heat with the at least one closed primary cooling cycle, transferring the excess heat from the at least one closed primary cooling cycle to the at least one closed secondary cooling cycle via the at
Doerrler William
Drake Malik N.
Greenblum & Bernstein P.L.C.
Voith Sulzer Papiertechnik Patent GmbH
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