Clair’s Aid for capacity enhancement

Clair’s Aid for capacity enhancement

Introduction:

We received an order from a leading cement client from Kurnool, Andhra Pradesh. It was for a Gas cooling system for capacity enhancement equipment for pollution control at their Kurnool Works site. We successfully installed a FD Cooler where the application was for a 16 MVA Furnace fumes collection with a gas inlet volume of 3,55,000Cu.mtr/Hr.

Data/ Table:

Table 1: Technical Specifications of the FD Cooler

S. No	Description	Unit	Value
1	Gas Inlet Volume	Cu.mtr/Hr	3,55,000
2	Gas temperature at HE Inlet	^oC	260
3	Gas temperature at HE Outlet	^oC	130
4	Gas outlet volume at operating temperature	Cu.m/Hr	2,78,000
5	Dust concentration in gases	gms/N.Cu.m	2
6	Number of passes for flue gases	Nos	3
7	Tube diameter and length	mm	150 diameter, 6000 long, 3.15 thick
8	Total number of tubers	Nos	1175
9	Total heat transfer area	sqm	3,544
10	Tube material	Not Applicable	MS
11	Pressure drop across the HE	mm WC	120
12	Cooling air volume	Cu.m/Hr	7,50,000
13	Cooling air inlet temperature	^oC	50
14	Number of cooling air fans	Nos	2
15	Capacity of cooling air fans	Cu.m/Hr	4,50,000 @ 65mm WC
16	Motor capacities of cooling air fans	KW	150 and 110
17	Expected power consumption of HE	KW	205
18	Dust disposalequipment	Not Applicable	Rotary air lock valve and screw conveyor
19	Total weight of HE with tubes	Tons	206

Observations:

Clair took up the challenge and following solution was proposed and implemented:

The FD Cooler offered is a Gas to Air Heat Exchanger
Since the Gas to Air heat transfer is very low compared to any other heat exchanger, the care is taken tom select appropriate heat transfer coefficient
Since the flue gases contain the dust, the probable dust coating on tubes is considered in deciding the heat transfer area required
The tube diameter selected is 150mm considering the dust concentration of the flue gases and the large diameters avoids the problem of choking the tubes
Multi pass heat exchanger is designed for efficient cooling of the gases
Tube velocities are above 10m/ sec for better heat transfer and for avoiding dust deposition in the tube
Gas flow in tubes in every pass is maintained from top to bottom to avoid dust deposition in the tubes
Top entry of each is designed for uniform gas distribution in the tubes and also to avoid excessive dust deposition on the tube sheet
Tubes are arranged in triangular pitch for better contact between cool air and tubes
Centrifugal fans are selected as cool air fans for better efficiency
Inlet plenums are provided to distribute the cool air across the tubes uniformly
Two fans are provided with damper controls to regulate the cool air quantity depending on the flue gas quantity and temperature. With the regulation we can avoid cooling of gases below dew point and also results in power saving
Hoppers are provided for each pass. The dust is extracted from the hopper with the help of a screw conveyor. RAL is provided with the screw conveyor to avoid air leakage into the system
Zero speed switches are provided from the screw conveyor and RAL to indicate stoppage and give alarm

Clair successfully implemented and commissioned the installation of New FD Coolerat the site and was our first heat exchanger installation in 2005 delivering an efficient capacity handling of 1,82,000 Nm³/Hr at 260^oC.