Siemens Energy Power Plant Operations & Environmental Chemistry Lecture

Flashcards cover plant overview, regulations, water & fuel systems, treatment processes, environmental analyses, combined-cycle fundamentals, and key laboratory methods to reinforce concepts for the upcoming exam.

How many units does the Santa Rita power plant have and in what year was it commissioned?

Four units (10, 20, 30, 40); commissioned in 2000.

Which Siemens-operated plant is the only one equipped with a condensate polisher?

San Gabriel (Unit 70).

What is the main function of a condensate polishing plant?

To remove corrosion products and ionic impurities from condensate before it returns to the steam cycle.

Name the two core cultural principles promoted by Siemens Energy.

Zero Harm Culture and Ownership Culture.

Which Philippine law regulates plant effluents?

Republic Act 9275 – Philippine Clean Water Act.

Which pollutants are routinely measured under the Philippine Clean Air Act (RA 8749) in Siemens plants?

Nitrogen oxides (NOx), sulfur oxides (SOx), carbon monoxide (CO), and particulates.

Under RA 6969, which agency implements hazardous-waste regulations?

EMB – Environmental Management Bureau.

In the KKS coding system, what plant does prefix ‘01’ refer to?

San Lorenzo.

What pipe-color code represents natural gas in the plant?

Yellow.

Where does Siemens’ Batangas complex source its natural gas?

Malampaya field (Palawan) and LNG imports.

Which system (code) reduces natural-gas pressure from Malampaya before use?

EKT – Gas reducing system.

What analytical method is ideal for measuring trace (ppm-level) water in fuel oil?

Karl Fischer coulometric titration (acceptable ≤0.1 % water).

Which calorimetric device is used to determine the heating value of fuels?

Bomb calorimeter (ASTM Heat of Combustion test).

What are the two deep-well demineralized-water treatment trains called?

Santa Rita Demin and San Lorenzo Demin plants.

Which resin removes positively charged ions in demineralization?

Cation resin (regenerated with HCl or H₂SO₄).

What is the purpose of a degasser column in demineralization?

To strip CO₂ and reduce carbonic acid formation, lowering alkalinity.

List the main steps of the Santa Rita ion-exchange demin line.

LCF → ACF → Cation → Degasser → Anion → Mixed Bed → Storage.

What does MMF stand for and what is its role at San Lorenzo?

Multimedia Filter; removes suspended solids/turbidity before RO.

At San Lorenzo, what is the typical regeneration interval of a mixed bed?

Approximately 464 hours.

During sewage treatment, what biological process occurs in the anoxic tank?

Denitrification: conversion of nitrate (NO₃⁻) to nitrogen gas (N₂).

Which chemical is dosed before effluent discharge for disinfection?

Sodium hypochlorite (NaOCl).

What system (code PUS) does Siemens use to generate sodium hypochlorite on-site?

Electrochlorination system using seawater.

Differentiate continuous and shock dosing in electrochlorination.

Continuous: normal flow with two dosing pumps; Shock: higher one-time injection (2 dosing pumps + 1 seawater pump) when tank is near full.

Why is acid washing (with dilute HCl) performed on the electrochlorination system?

To remove mineral scale (CaCO₃, Mg(OH)₂) formed during electrolysis.

What is the acceptable residual-chlorine limit at water outfall UQJ?

< 0.5 ppm (mg/L).

Which reagent powder is used in the field colorimetric test for residual chlorine?

DPD free-chlorine reagent powder pillow.

In titration of available chlorine, what titrant is used?

0.1 N Sodium thiosulfate (Na₂S₂O₃).

State the formula for computing available chlorine concentration from titration.

Conc (ppm) = (volume of titrant mL) × 35453 × Normality / volume of sample mL.

Why must residual-chlorine tests be done on-site immediately?

Residual chlorine dissipates rapidly, leading to falsely low readings if delayed.

What environmental significance does measuring True/Apparent Color have?

It indicates dissolved organic matter and suspended particles suggesting treatment efficacy or pollution.

Outline the gravimetric steps for Total Suspended Solids (TSS) measurement.

Filter 250 mL sample → dry filter at 103-105 °C → weigh until constant mass.

Define Biochemical Oxygen Demand (BOD) in 5-day testing.

Amount of oxygen microorganisms consume to oxidize organic matter over 5 days at 20 °C.

What four nutrients are added to prepare BOD dilution water?

Phosphate buffer, MgSO₄, CaCl₂, FeCl₃ (9 mL each per 9 gallons).

Contrast BOD and COD.

BOD measures biologically oxidizable matter; COD measures chemically oxidizable matter (biodegradable and non-biodegradable).

Which heavy-metal parameter is assessed with Program 90 using Chromaver 3?

Hexavalent Chromium (Cr⁶⁺).

What is the method name for ammonia determination in water samples?

Spectrophotometry with LCK/TNTplus vials (15-minute reaction).

Which method assesses orthophosphate in environmental samples?

Molybdovanadate colorimetric method (Program 480P).

What can high nitrate levels in water cause in infants?

Blue-baby syndrome (methemoglobinemia).

What variable does a Continuous Emission Monitoring System (CEMS) track quarterly for calibration?

Stack gas pollutants such as SO₂, NOₓ, CO, PM, CO₂, O₂.

Explain the efficiency benefit of a Combined Cycle Power Plant.

It reaches ~64 % efficiency by using a gas turbine (Brayton) and a steam turbine (Rankine) in series, extracting more energy from the same fuel.

What equipment recovers exhaust heat to generate steam in combined cycle plants?

Heat Recovery Steam Generator (HRSG) with HP, IP, LP sections.

Why is ammonium hydroxide dosed in the water-steam cycle?

Acts as an alkalizing agent to raise pH and minimize corrosion.

What chemical scavenges dissolved oxygen in the steam cycle?

Hydrazine (N₂H₄) or other oxygen scavengers.

At what ammonia-tank level should operators report to avoid pump shutdown and corrosion risk?

When level falls below 500-600 mm (or specified low-level mark).

State the treatment philosophy applied to the water-steam cycle.

AVT-O (All Volatile Treatment – Oxidizing).

Why is silica tightly controlled in steam-cycle water?

Silica deposits on turbine blades, lowering heat transfer and causing efficiency loss.

Which four reagents are used in the molybdenum-blue silica test?

HCl (1+1), 10 % ammonium molybdate, 10 % oxalic acid, 10 % ascorbic acid.

Purpose of oxalic acid in the silica test?

Eliminates phosphate interference and reduces yellow complex intensity.

What color indicates iron presence with the ferrozine method?

Purple complex at pH ≈ 3.5.

When should HP drum blowdown be initiated regarding iron levels?

When iron concentration reaches 200 ppb or higher.

In chloride photometric testing, which reagent forms turbidity?

0.5 % silver nitrate solution reacts with Cl⁻ to form AgCl precipitate.

Why is nitric acid added before silver nitrate in chloride analysis?

To acidify, keep chloride ions in solution, and prevent metal precipitation that could interfere.

What is a safe chloride taste threshold in water when sodium is the main cation?

Approximately 250 mg/L can impart salty taste.

What is the accepted reason for injecting phosphate into boiler water?

Maintains high pH, complexes hardness ions, and scavenges free oxygen radicals.

Describe the endpoint color change when titrating NaOH with HCl using phenolphthalein.

Solution changes from pink (basic) to colorless (acidic).

Provide the formula for calculating %NaOH purity from titration.

%NaOH = (N × V × 20) / S, where N = normality of HCl, V = volume titrant (mL), S = sample weight (g).

Why are pH and temperature monitored together in steam-cycle samples?

Temperature influences pH readings and affects corrosion, scaling, and correct chemical dosing.

What does high conductivity in condensate imply?

Presence of dissolved ions/impurities; potential contamination or resin breakthrough.

Name three sampling points routinely checked in the water-steam cycle.

Feedwater, HP Drum, Saturated Steam (others: IP Drum, LP Drum, PGB, LCA).

What is the primary energy-loss consequence of scaling inside boilers?

Reduced heat-transfer efficiency, requiring more fuel to achieve steam pressure.

Explain how poor water chemistry can damage turbine blades.

Impurities like silica or sodium deposit on blades, causing erosion, imbalance, and reduced output.

During multimedia filtration, what chemical coagulant is often added?

Poly-Aluminum Chloride (PAC).

What device in the plant carries label code UGV and what does it handle?

UGV – sewage/domestic wastewater system.

What does UBH separate from wastewater?

Oil and grease (oil-water separator).

Which pipe color denotes fire-water supply?

Red.

Why is reverse-osmosis membrane cleaning triggered?

Rise in differential pressure and conductivity indicating fouling.

Define «shock dosing» in electrochlorination.

A high-rate, short-duration NaOCl injection when hypochlorite tank reaches set point.

List two reasons ambient-air monitoring is performed around power plants.

To assess long-term pollutant levels for compliance and protect public health.

Which thermodynamic cycle is associated with gas turbines?

Brayton cycle.

What is the role of a mixed-bed resin after separate cation/anion beds?

Polishes water, removing residual ions to achieve highest purity.

Why must hydrazine be carefully controlled despite its benefits?

It is toxic; over-dosing poses health and environmental risks.

What is the primary nutrient ratio maintained in sewage treatment (C:N:P)?

Carbon : Nitrogen : Phosphorus balance to support microbial growth.

How does lanthanum chloride aid phosphate removal in wastewater?

Forms insoluble LaPO₄ precipitate, acting as a coagulant.

What parameter is measured first in colorimetric analysis to zero the instrument?

The blank sample (usually deionized or sample without reagent).

In nitrate TNT testing, what color indicates nitrate presence?

Yellow complex after 5-minute reaction.

What does the acronym HRSG stand for?

Heat Recovery Steam Generator.

Why is saturated steam usually superheated before entering turbines?

To prevent moisture carry-over, which causes blade erosion and efficiency loss.

Name the environmental sample point coded UGH.

Rainwater collection/diversion system.

What main pollutants does the flow-gas ‘stack’ release after complete combustion?

Primarily CO₂, water vapor, and trace NOx/SOx within permit limits.

State the regeneration chemicals for cation and anion resins respectively.

Cation: dilute HCl or H₂SO₄; Anion: caustic soda (NaOH).

What conductivity trend indicates resin exhaustion in a mixed bed?

A sudden rise in effluent conductivity.

Which system label (code) represents the seawater intake line?

UQA.