Energy Conservation In Textile

ENERGY CONSERVATION IN TEXTILE INDUSTRY LEARNINGS FROM INDIAN EXPERIENCE -Satyadeo Purohit, Director, Forbes Marshall The Textile Industry in India is one of the largest process industry (and one of the oldest) in terms of number of plants. With an increase in competition and the removal of quota system, most of the Textile process houses were forced to look at cost reduction to survive. The priorities for cost reduction were originally determined in the early/middle ‘90s based on the proportion of cost attributed to different components like raw material, utilities, man power, financial costs etc. At that point of time the priority was reduction in raw material costs as it contributed almost 50% in the total cost. Next in priority was the combined utility – i.e. electricity, fuel for steam / thermic fluid, water and compressed air. Within the utilities the focus was much more on electricity to begin with – as the cost of electricity was increasing and the availability was unreliable. This focus in late ‘90s yielded a very good result coupled with opportunity provided by opening of markets and availability of raw materials (dyes, chemicals etc.) at very low rates (especially from China). Cost of fuel for generating Steam / Thermic fluid in the meantime continued to grow steeply, nearly offsetting the benefits of reductions achieved in other areas. This brought focus to this utility and brought in the limelight the limited knowledge and bench marks available for the industry to take concrete actions to curtail the growing costs. Forbes Marshall, a pioneer in the field of Steam Energy Conservation, has worked with the textile industry over the last 60 years especially in India, Srilanka and Bangladesh, apart from other countries. Along with Confederation of Indian Industry, Forbes Marshall initiated a bench marking exercise for specific fuel consumption in Textile Industry. The findings are elaborated herewith, to have uniformity of data and draw representative conclusions. We are presenting here case studies in India with similar plants, processes and end products We surveyed 49 industries in Tirupur region and 10 industries in Bhilwara region Tirupur Region Utility Best Average

Fuel (Firewood) Kg/kg 1.57 2.75

Utility Best Average

Fuel (Lignite) Kg/mtr 0.29 0.36

Bhilwara Region

Percentage Reduction in Fuel Bill Industry

Steam Generation

Distribution & Utilization

Capacity Utilization

Total

3.0%

Condensate & Flash Recovery 5.0%

Textile – Bhilwara Textile –

7.0%

N.A.

15.0%

12.0%

7.0%

7.0%

N.A.

26.0%

Tirupur Looking at the data available above and the work we at Forbes Marshall, have done with Textile Industry in the last 60 years, we are briefly putting down opportunities for energy savings – with influencing factors / causes and remedies in the design of utility or operation of the process. We are classifying the entire steam and condensate loop into 3 segments.  Steam Generation & Distribution  Steam Utilization – based on the type of process  Condensate and flash steam recovery. I)

Steam Generation & Distribution Sr. No. 1.

Influencing Factor

Cause

Action

Poor boiler efficiency

- Fluctuating process loads – improper loading on boiler - Absence of diagnostics to take immediate corrective action

- Proper selection of boilers- capacity, burner turndown etc.

2.

3.

II)

Higher distribution losses

- Capacity & type of steam generator - Improper line sizing

- Boiler sequencing & load management - Diagnostics – steam & oil flow meters, stack loss monitoring with online efficiency display.

-Improper insulation

- Designing the distribution network optimally; proper line sizing & without extra provisions for expansions

-Improper line routing & condensate removal from steam lines.

- Proper condensate removal from steam lines; Diagnostics – Pressure & temperature gauges, steam flow meters etc.

Steam Utilization :-

Process’s in Textile Industry can be segregated into following segments & opportunities identified separately for each –  Batch wet processing under pressure  Batch wet processing – Atmospheric  Continuous Processing Main opportunity for Energy Savings in Batch Wet processing under pressure – Sr. No. 1.

2. 3.

Area Reduction in liquor ratio

Reduce & maintain process time Reduce batch / process time

Actions - Based on process requirement - Operating practices – how precisely are the ratios controlled practically; are proper measurements in place? - Properly sized & selected temperature controls - Proper condensate removal from HEX area - proper pressure of steam

4 . 5.

Reduce reprocessing

- instantaneous hot water availability - proper diagnostics & control on the process parameters

Insulate

- hot areas

Recover heat from Dye liquor & - Customized systems - Diagnostics Cooling water Main opportunity for Savings in Batch Wet Processing – Atmospheric: Jiggers, Winches, Washing etc. 6.

Sr. No. 1

Area

2

Effluent heat recovery

Avoid overheating

Actions -

Proper temperature control Proper selection of steam pressure Proper steam injection system (direct + indirect) Diagnostics Customized systems for heat recovery.

For continuous processing, the areas are similar with further focus on flow characteristics, counter flow operation, improved washing action, automation of process etc. Other process’s like drying cylinders etc. the issues related to energy conservation revolves around proper conditioning of steam and condensate removal from heat exchange areas – a) Reduce steam pressure b) Removal of air for steam systems c) Proper steam trapping d) Proper selection & maintenance of rotary joints & syphons. III)

Condensate & Flash Recovery –

Condensate heat in most energy conscious plants is being recovered back to boiler feed tank or for use in the process. However, a major opportunity exists in recovering the flash steam heat which is universally wasted. Systems designed to recompress the atmospheric or low pressure flash steam to a reusable pressure can be designed specifically for this purpose. Overall the opportunity to conserve energy in steam systems in Textile Industry is tremendous, however to avail of the benefits we need to be specific with data such as operating hours, parameters, benchmarks etc. For all of above to happen, the starting point is to have a diagnostics and monitoring mechanism in place for all key parameters. Also simultaneously a well designed and installed steam system may not yield adequate results unless proper operating practices including enhancing the Energy Awareness at all levels in the organization is systematically implemented.

A Case Study on Specific Fuel Consumption Approach for Value Addition; Terry Towel Plant in Western India Forbes Marshall did an Energy Audit at a Terry Towel plant in western India. The plant was manufacturing of Towels with a capacity of 300 MT/month. The plant had two 6.0 TPH capacity Boilers of 10.54kg/sq cm (WP). The plant had been in operation for the last 10 years. In the Pre-Audit Scenario it was discovered that the average furnace oil (F.O.) consumption was 1011KL, with a steam consumption of 130 TPD. The average Steam to Fuel ratio (S: F) was 11.8 with a Feed Water (FW) temperature of 70-90ºC (Live steam in Condensate return). The average Condensate Return from recoverable condensate was 59% (67 TPD) with O2 content in the flue gasses between 4% and 6% and Stack temperature in the range of 220º-240ºC. Distribution of Steam Consumption was as below; Equipment

Direct Steam Indirect Steam Consumption Consumption

Yarn Dyeing

10 TPD

50-55 TPD

Loop Dryer

20 TPD

Sizing

5 TPD

New VDR

15 TPD

Old VDR

5 TPD

Fabric Dyeing 20 TPD Total

30 TPD

95-100 TPD

Post Audit, based on our findings we devised a phase wise implementation to reduce FO consumption thereby reducing costs.

Phase- 1; Correct Steam Trapping Pre- Audit

Distribution of Steam Consumption

After Implementation

Total No. of Steam Traps

83 Nos.

No. of leaking Traps

43 Nos.

Nil

Water logged Traps

2 Nos.

Nil

Cold Traps

8 Nos.

83 Nos.

Nil

Equipment

Direct Steam Consumption

Indirect Steam Consumption

Yarn Dyeing

10 TPD

40 TPD

Loop Dryer

16 TPD

Sizing

4 TPD

New VDR

12 TPD

Old VDR

Not in use

Fabric Dyeing

20 TPD

Total

30 TPD

72 TPD

The Drop in Fuel consumption after implementation was observed to be, 1.5 KL per day

Phase-2; Implementation of Condensate Recovery: After implementing Condensate Recovery, the total Condensate being recovered was 68 TPD with total flash steam recovered and used for hot water generation being between 4-5 TPD. 90% of recoverable steam condensate is being recovered with the help of 3 sets of Flash Vessels and Steam Operated Pumps maintaining an average FW temperature of 65ºC and causing a Drop in Fuel Consumption of 0.5KL per day. Phase-3; Online Boiler Efficiency Monitoring: On implementation of the online Boiler Monitoring System, the average O2 percent in flue gasses has dropped to a consistent 3% with Stack Temperature dropping to 200º to 210ºC. This has increased the efficiency by 3% and caused the average daily fuel consumption to drop by 0.3 to 0.5 KL per day. Thus in the Post Implementation Scenario; Now Average F.O. consumption 8.0-8.5 KL Average Steam Consumption 96-100 TPD Average S:F ratio 12.1 Average FW Temp (No Live steam 65ºC in condensate return) Average Condensate Return from 90% recoverable condensate 3% Average O2 % in flue gas Average Stack Temp 200º -210ºC

Earlier 10-11 KL 130 TPD 11.8 70º-90º C 59 % 6% and 4% 220º-240ºC

Yet there are more opportunities to bring down the fuel costs. Below are a few things we can still work on;  Blow Down Heat Recovery System  Auto Temp. Control in yarn/fabric dyeing  Pressure controls  Proposal for Re Audit accepted and order is in process  Objective to save 1KL per day fuel more

Satyadeo Purohit, Director can be contacted on [email protected]