Energy-Efficiency Improvement Opportunities. A Case of a Textile Mill

Table of Contents

1. INTRODUCTION
1.1 BACKGROUND OF STUDY
1.3 INDUSTRY PROFILE

2 ENERGY AUDIT

3. RECOMMENDATION

REFRENCES

1. INTRODUCTION

1.1 BACKGROUND OF STUDY

The conservation of energy is an essential step we can all take towards overcoming the mounting problems of the worldwide energy crisis and environmental degradation. In particular, developing countries are interested to increase their awareness on the inefficient power generation and energy usage in their countries. However, usually only limited information sources on the rational use of energy are available.

The rational use of energy calls for a broad application of energy conservation technologies in the various industrial sectors where energy is wasted. One of these energy intensive industrial sectors to be considered to improve efficiency through the introduction of modern energy conservation technologies is the textile industry. The textile industry is one of the major energy consuming industries and retains a record of the lowest efficiency in energy utilization. About 23% energy is consumed in weaving, 34% in spinning, 38% in chemical processing and another 5% for miscellaneous purposes.

The need of energy management has assumed paramount importance due to the rapid growth of process industries causing substantial energy consumptions in textile operations. Conservation of energy can be affected through process and machine modification, new technologies and proper chemical recipes. The possibilities of utilizing new energy resources are yet to be explored. But initial cost of production will increase in step with cost of oil, which makes development of such sources doubtful in terms of cost incurred.

1.2 PROBLEM STATEMENT

Controlling the cost of production at best possible level is one of the essential requirements for the textile industry to compete successfully in the market. Hence, Textile industries are expected to initiate suitable measures such as profitable product-mix, higher productivity, modernization of machinery for energy savings and cost control to improve profitability. Energy management and saving policies have turned into subject of interest for textile manufacturers. There are a variety of energy-efficiency opportunities that exist in every textile plant, many of which are beneficial. However, even cost effective options are not put into action in textile plants mostly because of inadequate information on how to execute energy-efficiency measures. With this observation, an exhaustive energy investigation has been conducted in a textile industry. A detailed energy analysis is carried out on individual systems to assess the energy saving potential. Annual energy consumption and annual energy savings from the individual equipment along with department wise energy consumption details are presented.

1.3 INDUSTRY PROFILE

Bahir Dar Textile Share Company (BDTSC) is established in 1961 with a purpose of producing 100% woven cotton fabric. Like the other textile mill in BDTSC also the energy expense is in list of major expenditure. A proper management of energy in the enterprise will be focal measure of its performance. Optimizing the energy use in the factory will enable it to be competent and to remain in the market.

The target of this project work is to identify the main energy dissipative units and to find a possible solution to tackle the recognized troubles. A thorough chemical, thermal and electrical performance assessment of corresponding units has made to discover inadequately functioning units. A systematic approach is followed to examine electrical energy consumption of electrical units and compared it with standard and their original design. Furthermore, causes of dissipation are analyzed. Subsequently, based on the evaluation results, economically and environmentally viable measures have been suggested to enhance the competency of the every unit that forms the whole when combined. In addition to unit wise approach, system based approaches has been adopted on units functioning in integrated manner.

1.3 OBJECTIVE

- Identifying areas of improvement and formulation of energy conservation measures through system improvements and optimization of operations.

Specific Objective

- Assessing present pattern of energy consumption in different centers of operations
- Relating energy inputs and production output
- Identifying potential areas of thermal and electrical energy economy.
- Highlighting wastage in major area
- Fixing of energy saving potential targets for different departments
- Implementation suggestions of energy conservation and realization of savings

2 ENERGY AUDIT

Energy Audit is the key to a systematic approach for decision making in the area of energy management. It attempts to balance the total energy inputs with its use, and serves to identify all the energy streams in a facility. It quantifies energy usage according to its discrete functions. It is an effective tool in defining and pursuing a widespread energy management program.

As per the Energy Conservation Act, 2001, Energy Audit is defined as "the verification, monitoring and analysis of use of energy including submission of technical report containing recommendations for improving energy efficiency with cost benefit analysis and an action plan to reduce energy consumption".

TYPES OF ENERGY AUDIT

The nature of energy audit conducted depends on the type of industry, the depth to which the study is needed, potential and magnitude of cost reduction desired etc. The energy audit can be classified into the following types:

Preliminary energy audit

Preliminary energy audit, which is also known as walk through energy audit (or) diagnostic audit, is a relatively quick exercise and uses existing (or) easily obtained data. The scope of preliminary energy audit is to

- Establish energy consumption in the organization
- Obtain related data such as production for relating energy consumption
- Estimate the scope for energy savings
- Identify the most likely and easiest areas for attention
- Identify immediate especially no/low improvements for energy savings
- Set up a baseline (or) reference point for energy consumption
- Identify areas for more detailed energy study or measurements Preliminary energy audit can be completed in a day or two depending on the size and activities of the industry. This audit does not require sophisticated measuring instruments or software tools.
- Audit

Targeted energy audit is conducted on the particular energy system or process within an industry to minimize the energy intensity in a particular operational area. This often results from preliminary energy audit. Necessary data are provided by the industry by collecting data from calibrated online instruments (or) measured by the auditor wherever possible. This type of audit normally targets energy intensive equipments like air compressors, refrigeration and air conditioning, boilers, heat exchangers, pumps, fans and lighting systems. Therefore, targeted energy audit involves detailed survey of the target subjects, analysis of the energy flows and cost associated with the targets. The final outcome is the recommendation regarding action to be taken to improve the energy performance of the energy system.

Detailed Energy Audit

Detailed energy audit is a comprehensive audit which results in a detailed energy measures implementation plan for an industry, since it accounts for the energy use of all major equipment. It considers the interactive effects of various projects and offers the most accurate estimate of energy saving and cost. It includes detailed energy cost saving calculations and project implementation cost.

One of the key elements in the detailed energy audit is the energy balance in the industries. This is based on the inventory of the energy using system, assumptions of current operating conditions, measurements and calculation of energy use. The detailed energy audit is carried out in three steps.

- Pre audit phase
- Audit phase and
- Post audit phase >

Pre audit phase

In this phase, an initial study of the industry is carried out for proper planning to conduct the audit effectively. A one or two day visit to the site is required to meet the personnel concerned to familiarize with the manufacturing activities and to access the procedures necessary to carry out the energy audit. During this visit, the following activities are carried out in general.

- Detailed discussion with the senior management personnel to
- understand the need, aims and objectives to conduct the energy audit. To explain the kind of information that is required during the actual audit period.
- To get guidelines for economic analysis particularly budget provision details of earlier audit conducted and the status of implementation of energy conservation already recommended by previous audit team.
- Analyze the major energy consumption data and discuss elaborately with the relevant personnel.

The outcome of the visit needs to finalize an energy audit team and expertise required, actual expectation of the management, identification of potential areas for energy saving, identification of the type of instruments, the level of accuracy required and the schedule to carry out the detailed energy audit.

Audit phase

Depending upon the nature and complexity of the manufacturing activity, this can take a minimum of 3 days to several weeks or months to complete the audit. It involves the investigation and establishment of material, energy balances for specific energy system and process equipment. This is a well planned operation or check extended over periods of time. The information to be collected during the energy audit includes

- Sources of energy supplies
- Energy cost and tariffs
- Generation and distribution of compressed air, steam, chilled water etc.
- Process and material flow diagrams
- Internal electrical distribution diagrams (single line diagram)
- Energy consumption details of equipment, running hours, failure rates,
- and production details
- Potential for fuel substitution, process modification and the use of
- cogeneration systems
- Review of ongoing energy management procedures and energy
- awareness training programs

Apart from the above, information related to the baseline data ofthe following are also to be collected.

- Quantity and type of raw materials
- Technology, process used and equipment used
- Capacity, utilization efficiencies and yield
- Percentage rejection in reprocessing
- Quantity of type of waste
- Consumption of fuel, water, steam, electricity, compressed air and chilled water etc.

However, the type and natural data solely depend on the nature of the manufacturing process and the type of industry. As part of the audit, interview with supervisors and equipment operators must be conducted, as they have information related to the actual operating condition of the equipment. The maintenance manager is often the primary person to talk about equipment conditions, the efficiency level and associated operational problems.

Post audit phase

After the completion of the detailed energy audit, the energy action plan is prepared. These plans list-out all the energy conservation measures which are to be implemented first and suggest an overall implementation schedule. Detailed energy audit is incomplete without monitoring and associated feedback. Monitoring consists of collecting and interpreting data towards the goals set out in the energy action plan. Electrical and fuel power consumption must be evaluated and monitored on a regular basis to ensure the predicted energy savings. If the gap between planned objective and actual achievement is large, reasons should be analyzed and corrective actions should be initiated to achieve the goals. In this way, the complete energy audit cycle is completed in an industry.

3 RECOMMENDATION

ENERGY-EFFICIENCY IMPROVEMENT OPPORTUNITIES IN ELECTRIC MOTORS

When considering energy-efficiency improvements to a facility’s motor systems, a systems approach incorporating pumps, compressors, and fans must be used in order to attain optimal savings and performance. In the following, considerations with respect to energy use and energy saving opportunities for a motor system.

Motor management plan

A motor management plan is an essential part of a plant’s energy management strategy. Having a motor management plan in place can help companies realize long-term motor system energy savings and will ensure that motor failures are handled in a quick and cost effective manner. In the Motor management plan following key points included.

- Creation of a motor survey and tracking program.
- Development of guidelines for proactive repair/replace decisions.
- Preparation for motor failure by creating a spares inventory.
- Development of a purchasing specification.
- Development of a repair specification.
- Development and implementation of a predictive and preventive maintenance program.

1. Maintenance

The purposes of motor maintenance are to prolong motor life and to foresee a motor failure. Motor maintenance measures can therefore be categorized as either preventative or predictive. Preventative measures, include voltage imbalance minimization, load consideration, motor alignment, lubrication and motor ventilation.

2. Energy-efficient motors

Energy-efficient motors reduce energy losses through improved design, better materials, tighter tolerances, and improved manufacturing techniques. With proper installation, energy-efficient motors can also stay cooler, may help reduce facility heating loads, and have higher service factors, longer bearing life, longer insulation life, and less vibration.

3. Rewinding of motors

In some cases, it may be cost-effective to rewind an existing energy-efficient motor, instead of purchasing a new motor. As a rule of thumb, when rewinding costs exceed 60% of the costs of a new motor, purchasing the new motor may be a better choice. When repairing or rewinding a motor, it is important to choose a motor service center that follows best practice motor rewinding standards in order to minimize potential efficiency losses.

4. Proper motor sizing

It is a persistent myth that oversized motors, especially motors operating below 50% of rated load, are not efficient and should be immediately replaced with appropriately sized energy-efficient units. In actuality, several pieces of information are required to complete an accurate assessment of energy savings. They are the load on the motor, the operating efficiency of the motor at that load point, the full-load speed (in revolutions per minute [rpm]) of the motor to be replaced, and the full-load speed of the downsized replacement motor.

5. Adjustable speed drives (ASDs)

Adjustable-speed drives better match speed to load requirements for motor operations, and therefore ensure that motor energy use is optimized to a given application. As the energy use of motors is approximately proportional to the cube of the flow rate33, relatively small reductions in flow, which are proportional to pump speed, already yield significant energy savings.

6. Power factor correction

Power factor is the ratio of working power to apparent power. It measures how effectively electrical power is being used. A high power factor signals efficient utilization of electrical power, while a low power factor indicates poor utilization of electrical power. Inductive loads like transformers, electric motors, and HID lighting may cause a low power factor.

7. Minimizing voltage unbalances

A voltage unbalance degrades the performance and shortens the life of three-phase motors. A voltage unbalance causes a current unbalance, which will result in torque pulsations, increased vibration and mechanical stress, increased losses, and motor overheating, which can reduce the life of a motor’s winding insulation.

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