Welded plate heat exchangers for compressed air - Krashin-Shalev Metal Industries

Background

In the 1990s, a customer from a wind tunnel aeronautical testing facility, sought to replace two American heat exchangers installed the 1960s, which, for about 30 years, failed to meet the full performance required for the growing needs of the facility he had been operating. In analyzing the internal structure of the American heat exchangers, we have discovered the potential for significant improvement that can be carried out without changing the equipment’s dimensions. At Krashin-Shalev, we have designed and manufactured the two replacement heat exchangers, which were installed in 1995 and 1996. After our heat exchangers had been meeting all of the customer’s expectations, we’ve received a remarkable thank-you note from him due this achievement. The customer came back to us in 2011 with another mission.

Cold-grade heat exchanger

The objective

An additional facility, which is larger in scope is added to the existing one. The design of the new facility included a huge air compressor, among the largest available from the leading manufacturers. After the release of hot compressed air from the compressor, it was necessary to dry it out by cooling it to the lowest possible temperature and reheating it to highest possible temperature. In addition, it was necessary to avoid heavy investments in "Shell & Tube" heat exchangers. Therefore, it was decided to concentrate on designing efficient and compact welded heat exchangers.

The challenge

By beginning the practical planning of the mission, it became very quickly clear, that the presumptive goals of energy saving did not allow the use of traditional "Shell & Tube" heat exchangers. The size and cost of heat exchangers of the old technology, would not justify a hefty monetary investment and in additional space allocation in the cramped facility.

The Project’s Solution

For the implementation of the project’s objective, it was decided to split the process of the facility into two stages:

Stage 1: To cool the air by means of the “heat recovery” method with the help of cold air that flows out of the cold-grade heat exchanger. Stage 2: The cold-grade heat exchanger - a heat exchanger that cools the air down by means of the glycol brine, to an even lower temperature. This method ensures the purpose of the process, to dry out the air on the one hand, and conserving energy for first-degree cooling and of reheating, on the other. With strenuous efforts contemplating about the many design alternatives and in different operational regimes, the choice for the welded heat exchangers, which were at the forefront of this new technological capability, was formulated. Another requirement of the process was a high periodicity of the load. To address this issue, we have introduced improvements to the internal structure of the heat exchangers. We have commissioned in late 2013 these heat exchangers from TRANTER, which Krashin-Shalev represents in Israel (since 1985).

The outcome

The heat exchanger duo was put into operation in 2014 and has been operating successfully and efficiently at the facility to the full satisfaction of the customer ever since!