GB2323432A - Air cooled condensing and drying systems - Google Patents

Abstract

A drying unit for wet raw materials is shown in the accompanying drawings. The wet material (2) is supported upon a raised grid (9) provided within a storage area (1). Fans (7) are provided in walls of the storage area (1) below the level of the grid (9). Condensing bundles (5) are positioned adjacent the fans (7) outside the storage area (1). In use, the fans (7) draw ambient air through the condenser bundles (5) and into the storage area (1). The air, heated by the condenser bundles (5), passes through the grid to dry the wet material (2).

Description

AIR COOLED CONDENSING AND DRYING SYSTEMS Introduction The waste incineration industry is growing rapidly. A branch of this industry specialises in the disposal of refuse of biological origin. As the incineration process creates an excess of heat, power generation is becoming more and more important and compulsory. The most common way to produce power is with a steam turbine forming a so-called steam cycle. An environmentally friendly solution for the condensation process of the steam after it leaves the turbine is the air cooled condenser. The air cooled condenser is the actual outlet of the excess heat from the process which cannot be used. The quantity of this heat from the total heat balance lies normally between 35% and 60%.

One of the restrictions given by the authorities to run an incineration plant with power generation is that no visible plume or mists may emit from the stacks, which are formed by the humidity of the gases leaving the process. When these gases with a high water content cool down by the ambient air, mists will form. The exhaust fumes from these processes normally have an extremely high content of water, especially after the fumes have been cleaned. This patent application will combine certain process steps in order to overcome the problem of visible plumes or mists leaving the stack.

Novelty The actual process of condensing steam is considered to be common knowledge. The technology necessary for mixing gases is already used in the industry, however, this application combines these steps into a process which has not been used before. In this process, the relative warm air (32-350C) from the condensing process is used to dry the relative wet exhaust fumes out of the process to a mixture which has a relative humidity low enough to guarantee that no visible plume will ever occur. The existing technologies do have to be modified slightly, for instance, the air cooled condenser will have an induced draught mechanical fan which sucks the air through the exchanger and blows the warm air into a mixing area where the wet exhaust fumes are injected.

With the help of special designer diffusers the two gas flows are mixed to an ideal mixture. As the system is flexible in its layout other processes, whereby material like gases or solids have to be dried, can also be catered for.

The advantages are based on the fact that the process of drying the exhaust fumes coming from the combustion process do not require additional energy. The energy or warm air from the condenser which is normally rejected into the atmosphere is now used to solve a problem. The fact that the design of the total concept consists of a variety of existing processes which are modified is a guarantee for success.

Advantages An extra advantage of the concept is the noise emission of the entire unit to the environment; + 50% of the mechanical draught fans of the system will be located inside the unit, therefore preventing noise emissions to the environment. This phenomenon will decrease the total noise emission of the system. In most cases only half the quantity of warm air from the air cooled condenser is needed, leaving another 50% of the total quantity of warm air to be used for other similar processes. Also, other fuel systems creating even more humidity in the fumes could now be catered for.

The units as proposed can be built in two layers as can be seen from the sketch. The objection is to dry exhaust fumes, however, with minor modifications this could easily be used for drying solids like the refuse to be incinerated.

Competition.

As this development is very new the competition as far as we know is not yet active in this field. The market at this moment will however force everybody in steps towards an environmentally friendly and energy saving process, especially with the present move to generating power from waste without extreme high investments.

Claims (1)

1. CLAIMS:

   1. Apparatus for drying wet raw materials as hereinbefore described with reference to sheet 1 of the accompanying drawings.