ESP Troubleshooting Guide

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Electrostatic precipitators (ESP's) are used to reduce particulate emissions from blast furnaces, sintering operations in the steel industry, and for fly ash control from industrial and utility boilers. ESPs have been designed to collect particles with diameters of from 0.1µm to 10µm; collection efficiency is considered high, sometimes exceeding 99%. The ability of ESP's is to handle large exhaust gas volumes at temperatures between 175 and 700C.

An electrostatic precipitator contains the following:

• Discharge electrodes

• Collection electrodes

• Electrical system  

• Rappers

• Hoppers

• Shell                         

The discharge electrode is usually a small-diameter metal wire. This electrode is used to ionize the gas that charges the particles and to create a strong electric field. The collection electrode is either a tube or a flat plate with an opposite charge relative to that of the discharge electrode. The collection electrode collects charged particles. The electrical system consists of high voltage components used to control the strength of the electric field between the discharge and collection electrodes. The rapper imparts a vibration or shock to the electrodes, removing the collected dust. Rappers remove dust that has accumulated on both collection electrodes and discharge electrodes. Occasionally, water sprays are used to remove dust from collection electrodes. These precipitators are called water –walled ESPs. Hoppers are located at the bottom of the precipitator. Hoppers are used to collect and temporarily store the dust removed during the rapping process. The shell structure encloses the electrodes and supports the entire ESP.

 Electrostatic Precipitator Troubleshooting Guide

 

Symptom	Cause	Solutions
Corrosion Damage	Air Leakage	- Replace leaking door gaskets - Replace damaged rapper penetration seals - Replace damaged hammer drive seals - Repair leaking duct work test ports - Repair/replace leaking expansion joints - Repair leaking weld seams - Repair holes in casing - Check for reduced gas temperature
	Poor insulation design	- Re-insulate ESP hot roof to penthouse corners - Check/replace/install new hopper heaters
Deposits on Plates & Electrodes	Improper or poor rapping	- Verify rapper / vibrator systems operating - Inspect for binding or broken rapper shafts - Inspect for bound collecting plates
	Moisture / Condensation	- Check for air leakage, repair as noted above - Check for improper or poor insulation
	Change in gas chemistry	- Check for air leakage, repair as noted above - Check for reduced gas temperature - Check for change in operating conditions, fuels
Stack puffing (re-entrainment)	Improper or poor rapping	- Verify rapper / vibrator systems operating - Inspect for binding or broken rapper shafts - Inspect for bound collecting plates - Adjust control rapping schedule & intensity
Heavy dust buildup	Gas flow distribution	- Check for damage to inlet and outlet nozzles, baffles, louvers and perforated plates - Modify turning vanes or baffles
Control tripping	Grounding	- Clean insulators of all dust & condensation to prevent tracking - Check insulators for cracking - Check plate & electrodes for clearances & straightness - Check for broken wires - Check hopper level

Outlook on Cogeneration or CHP (Combined Heat and Power Plant)

Following survey was sent us to present our views on the subject of Cogeneration or CHP (Combined Heat and Power Plant). Our view/response is in red color.

Cogeneration or CHP (combined heat and power) is the simultaneous production of electricity and heat using a single fuel/ mix such as bagasse, natural gas, coal, waste gas, biomass, liquid fuels and renewable gases. The heat produced from the electricity generating process (for example from the exhaust systems of a gas turbine) is captured and utilised to produce high and low level steam. The steam can be used as a heat source for both industrial and domestic purposes and can be used in steam turbines to generate additional electricity (combined cycle power).

1. Average capacity of boiler used in CHP application? (In terms of MW or Tons per hour) –

Varies as per individual plant needs

2. Which industry generally uses boilers having a heat output greater than 80 MW or 100-120 Tonne/hour? (Sugar, Paper. Petrochemical etc)

Iron & Steel, Aluminum & Sponge iron

3. In my research I came to know that the sugar industry has the maximum potential but the boilers used are in the range of 20-30 MW. So I am unsure where these high capacity boilers can be used.

Sugar industry normally uses CHP plants of 20-30 MW capacities.

4. What are the types of boilers used in CHP applications? Are there any other boiler besides those mentioned that are used in the CHP applications?

Some of the types that I have come across are:
a. Multi-fuel for coal, peat, biomass and waste.
b. Waste to energy type – Wastes (MSW - Municipal Solid Waste, others) as fuel.
c. Gas based ones (HRSG, Heat Recovery Steam Generators).

These are the main classification what you have mentioned. It is o.k

5. What is the most common type of boiler used in CHP application in India? (As per your estimate)

Fluidized bed boilers – AFBC/CFBC& HRSG

6. Please indicate the type of design used in each case (e.g. fluidized bed, moving grate, others-please specify)

a. Multi-fuel for coal, peat, biomass and waste

FBC boilers and stoker fired boilers

b. Waste to energy type – Wastes (MSW - Municipal Solid Waste, others) as fuel

Mostly AFBC

c. Gas based ones (HRSG, Heat Recovery Steam Generators)

HRSG

d. Others

7. What are the typical pros and cons of the different types of boilers –

a. Multi-fuel for coal, peat, biomass and waste

In India, we use indigenous and imported coal, lignite, pet coke, biomass, washery rejects or solid waste as the fuel and the type of fuel to be used is dictated by the heating value, cost and distance from its source.

Stoker fired boilers are becoming outdated now thus leaving the choice limited to AFBC or CFBC. For small capacity boilers (say, below 50 TPH), AFBC type is preferred for techno-economical reasons.

b. Waste to energy type – Wastes (MSW - Municipal Solid Waste, others) as fuel

AFBC type is only used.

c. Gas based ones (HRSG, Heat Recovery Steam Generators)

The locations where availability of natural gas is competitive to other solid fuels, cogeneration plants employing gas turbines and HRSGs are favoured.

Heat recovery from waste gases (in industries of steel, sponge iron, copper, etc. ) is made through conventional water tube boilers to generate steam for process needs or power.

d. Others

8. What would be your specific considerations, if any, for choosing a boiler design, and steam conditions (e.g. higher the steam pressure, the better it is) ? i.e. critical things you would want to know from a CHP system owner/buyer, before selling a boiler.(e.g. fuel choices available to the client) ?

The various factors that we consider are:

• The total power requirement (for steam/heat calculations)

• Power for sale or just internal consumption

• Type of fuels available

• Steam/heat requirement of the main process (pressure and temperature)

• Investment available

• Expansion plans

9. What are the most common types of fuels available in India, based on your ideas about the industry ?

We have witnessed following types of fuels in our works:

• Coal – Domestic, Imported, Washery reject

• Lignite

• Pet coke

• Gas – Natural gas, Bio-gas, Waste gas

• Biomass –

o Agricultural wastes –Rice Husk, Paddy Husk, Chicory (coffee beans), date palms, dry leaves, trees, wood extracts etc.

o Industrial wastes – Paper pulp, Rubber extracts

10. What are the key trends affecting the co-generation industry in India?
(Major growth drivers and restraints)

Growth drivers:

o To reduce power and other energy costs.

o To improve productivity and reduce costs of production through reliable uninterrupted availability of quality power from Cogeneration plant.

o Cogeneration system helps to locate manufacturing facility in remote low cost areas.

o Improves energy efficiency, and reduces CO2emissions therefore it supports sustainable development initiatives.

o The system collects carbon credits which can be traded to earn revenue.

o Due to uninterrupted power supply it improves working conditions of employees raising their motivation. This indirectly benefits in higher and better quality production.

o Cogeneration System saves water consumption & water costs.

o Improves brand image and social standing.

o Cogeneration is the most efficient way of generating electricity, heat and cooling from a given amount of fuel. It saves between 15-40% of energy when compared with the separate production of electricity and heat.

o Cogeneration helps reduce CO2 emissions significantly. It also reduces investments into electricity transmission capacity, avoids transmission losses, and ensures security of high quality power supply.

o A number of different fuels and proven, reliable technologies can be used.

o A concurrent need for heat, electricity and possibly cooling indicates suitable sites for cogeneration.

o The initial investment in cogeneration projects can be relatively high but payback periods between 3-5 years might be expected.

o The payback period and profitability of cogeneration schemes depends crucially on the difference between the fuel price and the sales price for electricity.

o Global environmental concerns, ongoing liberalization of many energy markets, and projected energy demand growth in developing countries are likely to improve m