| Waste Throughput | Daily waste treatment capacity and annual operating hours | 300–3,000 tonnes/day; 7,000–8,000 h/year | Determines the available steam flow and the required turbine-generator capacity. | State the normal, minimum, and maximum waste throughput, including planned maintenance periods. |
| Waste Heating Value | Lower heating value of the municipal solid waste | Approximately 6–12 MJ/kg | Higher heating value generally produces more steam, while low heating value may require auxiliary firing or reduced load. | Provide seasonal design values, including minimum, average, and maximum LHV based on a representative waste analysis. |
| Boiler Steam Production | Steam flow rate supplied to the turbine | Approximately 20–150 t/h per plant, depending on capacity | The turbine must operate efficiently across the expected steam-flow range without excessive throttling losses. | Specify continuous, maximum, and minimum steam flow, plus allowable flow fluctuation. |
| Main Steam Pressure | Pressure at the turbine inlet, normally measured upstream of the stop valve | Commonly 3.5–6.5 MPa(a) | Inlet pressure affects turbine output, stage design, moisture formation, and plant efficiency. | Define normal and design pressure, pressure tolerance, and the expected pressure drop between the boiler and turbine. |
| Main Steam Temperature | Temperature at the turbine inlet | Commonly 380–450°C | Higher temperature can improve efficiency but requires suitable materials, sealing, lubrication, and control systems. | Provide normal temperature, minimum allowable temperature, maximum temperature, and start-up limitations. |
| Exhaust Pressure | Pressure at the turbine exhaust or condenser inlet | Condensing service: approximately 5–15 kPa(a) | Lower exhaust pressure usually increases power output but requires adequate cooling capacity and condenser performance. | Specify design back pressure, seasonal cooling-water or air temperature, and allowable exhaust-pressure rise. |
| Turbine Configuration | Condensing, extraction-condensing, back-pressure, or combined configuration | Condensing and extraction-condensing are common for electricity-focused WTE plants | The configuration must match the plant’s electricity, district-heating, process-steam, or flue-gas-treatment requirements. | Identify whether the plant needs electricity only, controlled steam extraction, district heating, or process steam. |
| Rated Generator Output | Continuous electrical output at the design steam condition | Approximately 5–50 MW for many medium-sized WTE plants | Generator size must match turbine output, auxiliary consumption, grid-export targets, and future operating margins. | Define gross output, net export output, power factor, overload duration, and expected auxiliary power demand. |
| Electrical Frequency | Grid frequency and generator rated speed | 50 Hz or 60 Hz; typical synchronous speeds include 3,000/3,600 rpm or 1,500/1,800 rpm | Frequency determines generator speed, pole number, synchronization requirements, and compatibility with the local grid. | Provide grid frequency, voltage, allowable frequency variation, and the required generator speed. |
| Generator Voltage | Rated terminal voltage and connection arrangement | Common medium-voltage levels include 6.3 kV, 10.5 kV, or 11 kV | Voltage must coordinate with the plant switchgear, step-up transformer, protection system, and grid interconnection point. | Specify generator voltage, insulation level, neutral grounding method, short-circuit requirements, and transformer interface. |
| Grid Connection | Export limit, synchronization method, protection, and dispatch requirements | Project- and utility-specific | Grid-code compliance affects excitation, governor response, voltage regulation, protection, and commissioning tests. | Obtain the utility’s grid-connection code and list required functions such as under-frequency, over-voltage, and anti-islanding protection. |
| Cooling System | Water-cooled or air-cooled condenser; cooling temperature and flow | Selection depends on water availability, ambient conditions, and local environmental constraints | Cooling conditions strongly influence exhaust pressure, annual energy production, condenser size, and operating stability. | Provide design ambient temperature, cooling-water temperature or dry-bulb temperature, water quality, and seasonal conditions. |
| Steam Quality | Steam dryness, carryover risk, chemistry, and cleanliness | Dry saturated or superheated steam; moisture at final stages must be controlled | Water droplets and contaminants can cause erosion, deposits, corrosion, and efficiency loss in turbine stages. | Define steam purity limits, sodium and silica limits, conductivity, dissolved oxygen, and boiler carryover controls. |
| Operating Flexibility | Minimum stable load, ramp rate, start-up frequency, and load-following capability | Often designed for approximately 40–100% load operation, subject to the final design | WTE plants experience variable waste quality and steam production, so flexible operation helps maintain reliable generation. | Specify minimum load, ramp-up and ramp-down rates, hot and cold start times, and permitted daily starts. |
| Annual Availability | Target operating availability and planned outage duration | Typically targeted above 8,000 operating hours/year where site conditions permit | Availability directly affects waste-treatment continuity, power revenue, and compliance with waste-disposal obligations. | Define the annual availability target, planned outage window, critical spare parts, and service response requirements. |
| Steam Extraction Requirements | Extraction pressure, temperature, flow, and control range | Project-specific; commonly linked to district heating or process-steam demand | Extraction changes the power output and must be coordinated with turbine stage design and control valves. | List each extraction point, normal and maximum flow, pressure tolerance, temperature requirement, and priority of heat supply. |
| Control and Protection | Digital turbine control, overspeed trip, emergency stop, vibration monitoring, and interlocks | Designed according to applicable electrical, pressure-equipment, and machinery standards | Independent protection and reliable control are essential for safe operation during steam, electrical, or cooling-system disturbances. | Specify control-system architecture, overspeed protection, trip logic, vibration limits, bearing-temperature monitoring, and data interfaces. |
| Material and Corrosion Resistance | Materials for steam-path components, casing, valves, condenser, and auxiliary systems | Selected according to steam temperature, chemistry, chloride exposure, and operating environment | WTE facilities can have challenging water chemistry and corrosive environments, making material selection important for service life. | Request material grades, corrosion allowances, surface treatments, welding procedures, and inspection documentation. |
| Efficiency and Heat Rate | Gross and net electrical efficiency or specific steam consumption | Project-specific; net efficiency is commonly lower than gross efficiency because of plant auxiliaries | Net efficiency provides a more realistic comparison because fans, pumps, flue-gas treatment, and waste handling consume power. | Compare guaranteed net output and heat rate at design, average, minimum, and seasonal operating conditions. |
| Installation and Maintenance | Foundation loads, equipment dimensions, lifting access, inspection access, and maintenance intervals | Determined by turbine size, speed, casing arrangement, and site layout | Installation constraints and maintenance access affect project cost, outage duration, and long-term availability. | Provide available equipment-room dimensions, crane capacity, transport limits, foundation data, and maintenance philosophy. |
| Standards and Documentation | Applicable design, testing, electrical, pressure, and quality-assurance standards | May include relevant IEC, ISO, ASME, EN, and local utility requirements | Clear standards prevent disputes over performance testing, safety requirements, manufacturing quality, and acceptance criteria. | List mandatory local codes, factory-test requirements, performance-guarantee conditions, drawings, manuals, and certificates. |
