Equipments and the Chemical Process Industry
Mr N. Radia
COO-Soda Ash Operations,
GHCL

The use of potent chemicals to generate reactions in raw material and convert them into finished products aptly sums up the chemical process industry. Any lapse in the selection, monitoring, maintenance, and institution of safeguards in the chemical process industry carries the risk of causing long term and often irreversible damages to humans and the environment including flora and fauna. This article will focus on equipments used in the chemical process industry and emphasize on why selecting the right equipment is critical not only in productivity but also on ensuring safety.

Equipment Selection

Selection of the right equipment is the key to an efficient and safe operation. Due diligence must be taken in equipment selection to avoid any undesirable outcome in the various stages of operations.

Equipments can be divided into proprietary & non- proprietary. Equipments such as pumps, compressors, filters, centrifuges & dryers, cooling towers, Mixers, Agitators, valves, furnaces etc that are designed and manufactured by specialist firms and are available for purchase off the shelf constitutes proprietary equipments. These equipments are available in standard sizes and come in different capacities.

Non-Proprietary equipments on the other hand includes but is not limited to chemical reactor, vessels, multistage separators such as fractionators and other special equipment not amenable to complete standardization. These equipments are custom designed for particular processes like reactors, distillation columns, and heat exchangers.

There are several considerations during the equipment selection and design process for the overall satisfactory performance and reliability of the equipment. Some of the more important points to be considered are:
1. Ease of operation and control & types of process controls
2. Optimum processing conditions & design of equipment
3. Availability of trained operators to operate the equipments.
4. Reliable methods for fabrication & adherence to international codes like ASME during fabrication of equipment
5. Appropriate material of construction
6. Strength and rigidity of components
7. Satisfactory performance of mechanisms
8. Ease of Maintenance and repairs
9. Safety requirements compliance in case of human failures, failures due to control systems, failure in utility systems, process streams, environmental events (wind, water. Earthquake etc.), Fire Hazard.
10. From point of view of fabrication machinability, weldability, malleability is considered relevant properties.
11. From mechanical properties point of view composition, structure, specific weight, thermal conductivity, expansibility, and resistance to corrosion need to be considered.
12. The layout and design of the equipment must aim to minimize the risk of errors and permit effective cleaning and maintenance in order to avoid cross contamination, built up dust or dirt and in general any adverse effect on the quality of product.

Monitoring

Continuous monitoring of equipment and plant is standard practice in chemical process plants. Monitoring is important in the chemical process industry as equipments are prone to deterioration and varying operating conditions also take a toll on these equipments. Standard operating procedures such as start up and shut down in a chemical process factory can significantly alter stream compositions and operating conditions that are much different than under normal operation and calls for constant monitoring.

When a manufacturing plant is in operation, adherence to process such as material identification as per specification, heat treatment of high thickness material, proper welding of joints with qualified welder as per ASME standards, dimensional checking along with hydrostatic / pneumatic tests etc needs to be constantly monitored. Also adherence to preventive practices such as following proper start up procedures so as to eliminate damage due to thermal shock, maintaining proper log sheet during operation, analyzing process deviations and corrective actions on the same needs to be monitored.

Maintenance Management systems can come in handy in ensuring a comprehensive maintenance of the actual machines. An ideal maintenance management system must incorporate features such as, equipment data base up-to-date in SAP, maintenance scheduling, monitoring of preventive compliance, maintain equipment history, static vessel thickness, corrosion management, condition based monitoring which covers vibration measurement of rotary equipments, thermography of furnace, Dye penetrate tests etc.

Performance Indicators For Production And Maintenance

Performance indication foe equipments deployed in the chemical process industry can be tracked on several indexes such as Finance - Budgeting from corporate level down to each cost Centre besides tracking and monitoring the actual, budgeted and forecast which can be updated throughout the year. Actual performance can also be tracked against targeted performance in the manufacturing process. Such tracking also acts as an enabler for continuous improvement initiatives. There are several proven performance measurement models such as DMAIC (Define, Measure, Analyze, Improve and Control) that can be adopted. OEE (Overall equipment effectiveness) and cost per unit production are other metrics that can be used to track performance. Performance tracking on the corporate side can be done through asset or capital based metrics like performance to share holder value, such as RONA (Return on net assets) or ROCE (Return on capital employed)

Reliability of equipment can also be gauged by measuring MTBF for equipment reliability, ratio of unplanned work, inventory turn rates and store house effectiveness etc. Defects if any identified prior to failure are indicative of the effectiveness of programs. Programmed results can also be tracked through score cards.

Gap analysis can also be carried out to identify areas where performance gaps exist (between current level and industry best practices) in area, availability, yield, quality, and cost. Maintenance reliability can be further checked using several KPI's such as availability, utilization, mean time between failures (MTBF) etc. Significant returns can be achieved with focus on identifying performance gaps, greatest opportunities for improvement.

Reliability

Dependability is the best indicator of reliability, which is an indicator of the probability that an item can perform its intended function for a specified interval under stated conditions. To track reliability in the business context, the annual cost of unreliability incurred by the facility can be quantified and measured. Downtime, cutbacks, and slowdowns are how failure is measured in most continuous process industries. Any improvement in reliability will have a positive impact on reducing the cost of unreliability and thereby generates more profit and get more business.

Reliability of equipments used in the chemical process industry can be improved by following good maintenance practices, deploying best-in-class operating procedures etc. Reliability can also be augmented by adopting Total productive maintenance (TPM), a practice which ropes in production personal into appropriate maintenance tasks for both equipment and processes. It promotes effective use of equipment and loss prevention through preventive maintenance efforts with the involvement of all people from top to bottom in organization. Root cause analysis to define, segregate and identify problems with people, procedures or hardware can also be used to prevent recurrence of a failure and conform to reliability principles. Reliability is observed when mean time between failures (MTBP) is large compared to mission time & it should be harmonized with cost issues.

Alternate Equipments (Stand By Equipments)

The purpose of maintaining standby equipments is to enable continuous operations/production. It minimizes interruptions in operations which help to sustain productivity and norms which in turn affect the cost of production.Standby equipments are mostly rotary equipments like pumps, fan, compressors, vacuum pumps etc... Being rotary equipments it involves bearing lubrication, bearing /impeller replacement after certain hours of operation, maintenance of associated electrical and instrumentation system. The equipment life depends on serviceability. Hence frequency of maintenance is higher than static vessels.

Protective Measures

Implementing protective measures are required to ensure safe operation of equipments such as piping systems. These measures could include engineering protections against possible failures such as thermal insulation, armor guards, barricades, and damping for protection against severe vibrations. Automatic shut off mechanism or flow controllers in the event of a piping failure such as block valves or excess flow valves can also be incorporated.

Plant must minimize the potential harm to personnel and property in case of accidents arising out of: a) Human failure b) Failure of equipment or control instruments c) Failure of utilities or key process streams c) Environmental events (wind, water, earthquake so on). Examples of common safe practices are pressure relief values, vent systems, flare stacks, venting of steam in case excessive build up and release of fire water to area of fire, escape hatches in explosive areas, dikes around tanks storing hazardous materials, turbine drives as spares for electric motors in case of power failure. In chemical processing plants of any significant size, loss prevention reviews are held periodically by representative departments.

New Advancements

Advancement in manufacturing is furthered by the use of advanced materials such as carbon fiber and grapheme to produce stronger, lighter, or more durable products having high corrosion resistance used in new generation large aircraft. And like wise by the development of genetically engineered crops, bio-remediation (microbes) to clean up spills etc in the field of Biotechnology. In Nano-technology, engineering and technology conducted at the nano-scale to produce products such as disease targeted drugs and lighter sporting equipment. Nano- technology also holds promise in the development of chemical sensors when reduced to molecular dimensions makes it possible to detect very low level of arsenic in drinking water.

Highly intelligent platforms create the foundation for continuous optimization by visualizing operating processes at chemical plants in real time and this creates a basis for concrete and well supported decisions and helps to increase performance and reduce operating costs by 8 % and production increase by 10 %, this helps in achieving sustainable competitiveness. The development of green process have led to the production of low smoke candles, macro molecular hazard free paint coating additives, biologically derived diesel fuel, non-yellowing eye glass lenses using Iso sorbide poly carbonates etc.

Development of smaller ( i.e. Intensified ) process equipment with production rates equivalent to those of current equipment can result in significant material utilization, reduced energy and capital requirements, and safer equipment design, intensification reduces size by taking advantage of small dimension effects of heat and mass transfer phenomena and by combining multiple unit operations into a single unit ( e.g. Reactive distillation).