| Waste Minimization at a Chemical Manufacturing Plant | Lithuania | 1993 | Full scale |
MANUFACTURE OF CHEMICALS AND CHEMICAL PRODUCTS # 27
Background
Kedainiai Chemical Plant, located about 100 kilometers northwest of Vilnius, is one of the largest chemical plants in Lithuania. The company manufactures sulfuric acid, phosphoric acid, monoammonium phosphate (MAP) and aluminum fluoride. Intermediate and finished products are exported to Eastern and western European countries and Japan. The plant employed 1,384 people in 1994.
The cleaner production measures were initiated under World Environment Center's Industrial Waste Minimization Program.
Cleaner Production Principle
Process modification; New technology
Cleaner Production Application
A.
In the manufacture of monoammonium phosphate (MAP) at Kedainiai, ammonia and phosphoric acid are reacted under controlled pH conditions. Failure to maintain pH at optimum levels results in process upsets and excessive emissions of unabsorbed ammonia into the atmosphere. In the past, pH levels were measured every 20 minutes using pH paper. The accuracy of pH measurements using this method was poor. Therefore, to ensure that the pH levels were sufficient, the reaction was controlled at a higher pH level than necessary. This was accomplished by over formulation of the product resulting in excess ammonia concentrations in the final MAP product.
During the waste minimization project, methods for obtaining more accurate and timely pH measurements were investigated. It was determined that a laboratory pH meter would provide pH measurements more quickly and accurately than the previous method.
B.
The production processes at Kedainiai are supported by a thermoelectric power plant using four oil-fired boilers, each burning 50 tons per hour of fuel. The boilers generate steam to drive turbines for electricity and also provide steam and hot water for process requirements and domestic use. Oil-fired burners generate soot and carbon which coat the steam generating heat exchanger pipes. This in turn reduces the heat transfer between the hot flue gas from the boiler and the cold water running through the heat exchanger pipes. Poor heat transfer results in energy losses. To keep the heat exchanger surfaces clean, soot build-up is removed periodically by a blast of steam in a procedure called boiler "blow down." In the past, the effectiveness of the blow down was determined by measuring the salinity of the blow down water in a laboratory. Because the results of this analysis were not immediately available, they could not be used to effectively control the blow down process and reduce the energy losses occurring due to poor heat transfer in the heat exchanger.
During the waste minimization project, alternative methods for analyzing salinity of the blow down water were investigated. A decision was made to install a conductivity meter which could instantaneously measure the water salinity. As a result of the project, frequent measurements of blow down water salinity are available allowing boiler operators to clean the heat exchanger effectively and maintain it in good condition.
C.
The production processes at Kedainiai are supported by a thermoelectric power plant using four oil-fired boilers, each burning 50 tons per hour of fuel. The boilers generate steam to drive turbines for electricity and also provide steam and hot water for process requirements and domestic use. Water fed to the boiler is pre-treated to remove dissolved oxygen. High levels of dissolved oxygen in water cause corrosion and deposits on the inside of the piping in the steam generating heat exchangers. This in turn reduces the heat transfer between the hot flue gas from the boiler and the cold water running through the heat exchanger pipes. Poor heat transfer results in energy losses. The deposits must be manually removed by maintenance personnel. Pipes and fittings that are severely damaged must be replaced. This process is both expensive and time consuming. Therefore, effective removal of dissolved oxygen from water is critical to extend heat exchanger life, lower maintenance costs, and reduce energy losses from inefficient heat transfer. In the past, dissolved oxygen levels were measured periodically in a laboratory. Because the results of this analysis were not immediately available, they could not be used to effectively control the water treatment process.
During the waste minimization project, alternative methods for analyzing dissolved oxygen in the boiler feed water were investigated. A decision was made to install a portable dissolved oxygen meter in the water treatment plant.
D.
The production processes at Kedainiai are supported by a thermoelectric power plant using four oil-fired boilers, each burning 50 tons per hour of fuel. The boilers generate steam to drive turbines for electricity and also provide steam and hot water for process requirements and domestic use. Utilities are distributed to the facility through an extensive network including over ten kilometers of steam, hot water, vacuum and air supply lines. Many of these supply lines are old and require continuous maintenance for repair of leaks. In the past, plant personnel conducted visual and audible inspections for leaks and conducted repairs when leaks were detected. However, many leaks went undetected due to inaccessibility of piping and high background noise levels in the process areas. Excessive steam and water losses resulted form undetected leaks in piping. In addition, vacuum and high pressure air leaks resulted in increased power demand and higher fuel consumption.
During the waste minimization project, alternative methods for leak detection were evaluated. It was determined that an ultrasonic leak detector could quickly locate steam, water, and air leaks from a distance of up to 3 meters and could also detect vibrations from bearings that are misaligned or in need of repair. Use of the ultrasonic leak detector not only detects small leaks but also eliminates hazards associated with manual inspections of high pressure, high temperature lines.
E.
The production processes at Kedainiai are supported by a thermoelectric power plant using four oil-fired boilers, each burning fifty tons per hour of fuel. The boilers generate steam to drive turbines for electricity and also provide steam and hot water for process requirements and domestic use. The fuel oil burned in the boilers contains as much as 2.5 percent sulfur. The burners are old and lack the controls necessary to assure efficient burning of fuel. This results in excessive fuel consumption and significant emissions of sulfur dioxide to the atmosphere.
During the waste minimization project, an investigation was undertaken to improve the efficiency of the boilers. It was determined that a combustion gas analyzer would provide useful information to operators to enable more efficient boiler operation. For example, a combustion gas analyzer could be used to measure the oxygen and carbon monoxide in the boiler exhaust on a regular basis. This information in turn could be used by operators to adjust the air/fuel ration for optimum burning efficiency. To implement the project, a portable stack gas analyzer was purchased and installed.
F.
Phosphate rock and sulfur are two raw materials used in kedainiai's processes. Phosphate rock is imported from Russia and sulfur is imported from the Ukraine. Some of these raw materials contain radioactive contamination. Because customers do not accept finished products that are radioactive, Kedainiai must monitor their raw materials for radioactivity. In the past, the facility sent samples periodically to an outside laboratory for analysis.
During the waste minimization project, methods for more rapid detection of radioactivity in raw materials were evaluated. A decision was made to purchase and use a portable radioactivity meter on-site to screen raw materials for radioactive contamination before they are used in production. The meter can also be used to check and certify that final products are free of radioactivity before shipment to customers.
Environmental and Economic Benefits
A.
Installation of a pH meter has resulted in fewer process upsets and ammonia emissions to the atmosphere. Better process control has also improved process efficiency and reduced the amount of ammonia consumed in the MAP reaction for a savings of 30 tons/year.
The pH meter was supplied by Orion, Hillsboro, Oregon, United States at a cost of $700, paid for by the United States Agency for International Development (USAID). There is a yearly savings of $4,400 and a payback period of two months.
B.
The project resulted in lower fuel consumption (30 tons/yr) and decreased emissions of sulfur dioxide (0.6 ton/yr) and nitrogen oxides (0.24 ton/yr).
The conductivity/ TDS meter CDH-42 was supplied by OMEGA International, Stanford, Connecticut, United States at a cost of $900, paid for by the United States Agency for International Development. There is a yearly savings of $1,700 and a payback period of less than seven months.
C.
The project resulted in more efficient boiler operation, lower maintenance costs, and decreased fuel consumption.
The dissolved oxygen meter was supplied by OMEGA International, Stanford, Connecticut, United States, at a cost of $2,000, paid for by the United States Agency for International Development. There is a yearly savings of $4,600 and a payback period of less than six months.
D.
As a result of the project, plant personnel have been able to reduce losses from leaks in utility lines and reduce equipment maintenance costs. In addition, the facility reduced fuel consumption by 52 tons/year and emissions of sulfur dioxide and nitrogen oxides.
The Ultraprobe 2,000 leak detecting system was supplied by UE Systems, Elmsford, New York, United States at a cost of $5,000, paid for by the United States Agency for International Development. There is a savings of $7,200 a year and a payback period of less than nine months.
E.
As a result of the project, the facility reduced its fuel consumption by 360 tons/year and emissions of sulfur dioxide and nitrogen oxides.
The portable stack gas analyzer, Model 33 was supplied by Testo Term Company, Flanders, New Jersey, United States at a cost of $10,000 which was paid by the United States Agency for International Development. There is a yearly savings of $22,000 with a payback period of less than six months.
F.
The portable radioactivity meter supplied by Technology Associates at a cost of $1,000, was paid for by the United States Agency for International Development. There is a saving of $26,000 a year; the payback period was two weeks.
As a result of the project, the plant increased its export sales and improved worker and customer health and safety by reducing exposure to radioactive materials.
Constraints
None mentioned.
Contacts
Review Status
This case study was taken from the WEC publication "Economic and Environmental Benefits of Industrial Waste Minimization in Estonia, Latvia and Lithuania" (1995). It was edited for the UNEP IE ICPIC diskette in June 1997.
Subsequently the case study has undergone a technical review by Dr Prasad Modak at Environmental Management Centre, Mumbai, India, in September 1998.