Coolers belong to the technical equipment which has been successfully employed for a long time in many industries. In former applications, their main function was the heating of materials by utilizing the heat withdrawn from other materials to be cooled. The stove pipe of the good old iron stove is an example of a “classic cooler”. The hot flue gases are cooled in the stove pipe and the stove pipe in turn serves to heat the room. The principle applied today is often similar. On the one side, we have a fluid, such as flue gas which due to its composition is not suitable, or only with reservations, for further utilization, either because it contains aggressive components (SO2, NOx, etc.) or undesirable solids (soot, dust). On the other side we have a fluid to be upgraded by supplying heat. The application is different when the temperature of the off-gas is too high for further treatment or for a downstream process.
GEA keeps your process cool
Coolers can be used for the most diverse fluids. The equipment described here is the one employed for producing temperature changes in gases.
The heat transfer takes place through a wall which is arranged between the hot gas and the cold gas. The wall has the function of a boundary for mass exchange. The amount of heat that can be exchange between hot gas and cold gas depends, among other factors, on the available surface area. The general term for this type of cooler is therefore surface cooler.
In the following, only gas/gas (air) tube coolers will be dealt with. The types of construction may be classed into cross flow, counterflow and parallel flow coolers or mixed forms of the mentioned flow arrangements.
GEA not only engineers and constructs gas coolers, but also commands the pertinent technology, offering the flowing services:
For each specific cooler problem we study:
With this arrangement, the process gas and the cold gas flow in parallel.
As a result, a higher thermal load originates for the partitions (cooling tubes). This has an advantage in that the heat transfer rate is high, this being demonstrated by the high cold gas outlet temperature. On the other hand, the engineering design for this solution is rather complex, above all in view of the high temperature gradient between the process gas and cold in the inlet area.
In this case, the process gas is passed through the cooler in opposite direction to the cold gas.
This arrangement provides for a substantially lower thermal load of the partitions (cooling tubes) than with the parallel flow arrangement. As a result of the reduced temperature gradient, the heat transfer is less efficient, this being demonstrated by a substantially lower cold gas outlet temperature compared with the parallel flow principle. The engineering design is relatively simple, and this arrangement provides for gentle cooling.
Cross flow arrangement means that the process gas passes through the cooler at an angle of 90° to the flow direction of the cold gas.
As a result of this arrangement, the thermal load imposed on the partitions (cooling tubes) is between that of the parallel flow and of the counterflow principle. The temperature gradient obtained between the process gas and the cold gas is normally in between that of the other two systems.
The engineering design for this arrangement is not too elaborate, offering as a rule the most economical solution.
The flow arrangements described before can be combined in a number of mixed forms. Such mixed flow arrangements are especially applied to double-pass and multi-pass tube coolers.
Rapid cooling of quenching of gas streams is used in a number of essential applications in the process industries. The selection and sizing of spray nozzles are the most critical decisions in the system design. GEA quench tower design consists of an open vessel in which liquid is sprayed to contact the gas. The gas enters the bottom of the tower through a side nozzle and flows upwards, counter-current to liquid that has been sprayed from the top of the tower. By the time the gas has reached the top gas outlet, it has been cooled to its adiabatic saturation temperature.
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