Shock Pulse Generator

 

Overview

The Shock Pulse Generator (SPG), developed and manufactured by Swiss company Explosion Power GmbH, is an online boiler cleaning equipment automatically generating Shock Pulses (SP) by pressurized gas combustion. The innovative technology has proven its outstanding performance at worldwide more than 400 different installations in 20+ countries since 2009. Plant operators confirmed significant prolongation of boiler operating periods and increased efficiency, thus contributing to a sustainable and economic plant operation. Leading plant suppliers decided to apply SPG-technology to new build plants, additionally profiting from the sophisticated system design and the compact geometry.

Boiler cleaning by means of Shock Pulse Generators means:

  • Permanent and automated boiler cleaning, thus lower exhaust temperature and higher boiler efficiency, improved CO2 plant performance
  • No steam consumption, no thermal abrasion or damaging of boiler tubes
  • Higher plant availability by longer boiler traveling period, less cleaning needs during maintenance stops
  • Reduction of heat transfer surface area for same steam capacity
  • Saving of boiler house volume by reduced space requirement
  • Investment cost saving by reduced number of cleaning devices
  • High degree of operational safety – boiler remains closed during operation (contrary to manual explosive cleaning as for example Bang&Clean® )
  • Quick and easy installation by modular and compact type series
  • High industrial standard (CE-certification based on Pressure Equipment Directive, clearly defined ATEX zones, PLC system monitoring, PROFIBUS/MODBUS compatible)

Fields of application of the Shock Pulse Generator-Technology are:

  • Waste to Energy plants (incl. refuse derived fuel boilers)
  • Industrial boilers (biomass / various fuels)
  • Sludge incineration plants
  • Hazardous waste incineration plants (incl. chemical plants)
  • Waste heat boilers (coking plants, metallurgic factories etc.)
  • Coal fired power plants
  • Black liquor boilers
  • Filters and spray absorbers
  • Cement plants

SPG-technology hence is installed to all boiler regions and therefore replaces existing boiler cleaning equipment as soot blowers, shot ball systems, water canons, rapping systems, sonic horns and shower cleaning systems (SCS).

Design

Shock Pulse Generators are manufactured in Switzerland, from special high pressure and high temperature resistant stainless-steel qualities and other high quality components. Quality assurance includes hydrostatic pressure tests as well as explosion tests. Shock Pulse Generators are CE-certified as pressure equipments of Category II and III respectively. The Shock Pulse Generator is available within two different type series, the EG10 and the Twin type series. A design description of both type series as well as a table with technical information can be found in the following picture series.

Function EG10 Series

The Shock Pulse Generator was developed in 2009 and since then has proven its outstanding performance. As with manual explosion cleaning processes, the Shock Pulse Generator cleans the boiler by pressure waves. The pressure waves are created by a shock combustion of a mixture of burnable gas (Natural Gas or Methane) and pure oxygen. Contrary to manual processes, this shock-combustion is carried out automatically and outside of the boiler, in an pressure resistant device. The resulting supersonic pressure wave is introduced into the boiler by means of a valve and a discharge tube. The combustion gas, the boiler tubes and walls are put into a short oscillation, similar to a rapping system, so that deposits are cleaned off. The following steps are performed during one cycle for the EG10 type series:

Filling

After release by the control, the dosing tanks of the Shock Pulse Generator are filled with Oxygen and Natural Gas. The two gases remain completely separated from each other and are not ignitable.

Transfer

The piston is pressed against the valve seat by Nitrogen pressure and closes the discharge opening gastight. By opening the transfer solenoid valves, the two gases flow through the transfer valves, non-return valves and flame backstroke barriers into the combustion chamber, where they are mixed and therefore ignitable.

Ignition

The combustion is ignited by a glow plug. The pressure increase in the pre combustion chamber to approx. 350 bar moves the piston backwards. The piston therefore opens the discharge and the supersonic shock pulse of the main combustion chamber is introduced into the boiler.

Shock Pulse

The discharge nozzle transfers the shock pulse into the boiler, where it propagates first linear, then spherical. Flue gas, boiler tubes and walls are put into a short oscillation, so that deposits are cleaned off.The effective depth and cleaning effect can typically cover up to 10 m, with best cleaning results for boiler tubes and walls capable of oscillation.

Closing of valve

After the pressure wave was discharged from the Shock Pulse Generator, the piston is pressed against the discharge opening by the Nitrogen gas spring and closes the generator gas tigth. The Shock Pulse Generator is then ready for the next pulse cycle.

Function Twin Series

The Shock Pulse Generator was developed in 2009 and since then has proven its outstanding performance. As with manual explosion cleaning processes, the Shock Pulse Generator cleans the boiler by pressure waves. The pressure waves are created by a shock combustion of a mixture of burnable gas (Natural Gas or Methane) and pure oxygen. Contrary to manual processes, this shock-combustion is carried out automatically and outside of the boiler, in an pressure resistant device. The resulting supersonic pressure wave is introduced into the boiler by means of a valve and a discharge tube. The combustion gas, the boiler tubes and walls are put into a short oscillation, similar to a rapping system, so that deposits are cleaned off. The following steps are performed during one cycle for the Twin type series:

Filling

After release by the control, the Shock Pulse Generator is filled with Oxygen and Natural Gas. The two gases are mixed during filling by means of a static mixer.

System Tightness Test

The two pistons are pressed against the valve seats by Nitrogen pressure and close the discharge openings gastight. The two gases are in the combustion chamber in a mixed state and hence combustible. The complete system is tested for gas tightness by the PLC. The filling valves are closed.

Ignition

The combustion is ignited by a glow plug. The pressure increase in the pre combustion chamber to approx. 350 bar moves the pistons backwards. The pistons therefore open the discharge nozzles and the supersonic shock pulses of the main combustion chamber are introduced into the boiler where they overlapp.

Shock Pulse

The discharge nozzles transfer the shock pulses into the boiler, where they overlap and then propagate first in a linear, then in a spherical manner. Flue gas, boiler tubes and walls are put into a short oscillation, so that deposits are cleaned off. The effective depth and cleaning effect can typically cover up to 10 m, with best cleaning results for boiler tubes and walls capable of oscillation.

Closing of valve

After the pressure waves were discharged from the Shock Pulse Generator, the pistons are pressed against the discharge openings by the Nitrogen gas spring and close the generator gas tigth. The Shock Pulse Generator is then ready for the next pulse cycle.

Installation

The Shock Pulse Generator system consists of:

  • Shock Pulse Generators, mounted at the outside of the boiler wall on a boiler nozzle, introducing the shock pulse trougha discharge nozzle into the boiler
  • Control cabinet, controlling shock pulse cycles, connected to distributed control system (DCS)
  • Pressure regulating units, reducing gas cylinder pressure of natural gas/methane, oxygen and nitrogen to 40 bar
  • Valve panel, preassembly of valves, pressure transmitters and junction box

The gas supply for Shock Pulse Generators is easily carried out by means of gas cylinders or small bundles with 200 bar pressure. The pipes distributing the gas to the Shock Pulse Generators should exhibit a minimal inner diameter of 10mm and are operated at a maximum pressure of 40 bar (e.g. material V2A, nominal inner diameter DN10, nominal pressure PN63). If Natural Gas is available from the grid, a small compressor can be installed. Additionally, a Nitrogen Gas Cylinder is necessary for the gas spring of the piston. The Shock Pulse Generator is mounted at the outside of the boiler wall. The discharge nozzle is introduced into the boiler by means of a boiler nozzle and is shortened to the same length as the boiler inside wall. The Shock Pulse Generator is hung movable to a crane rail and connected to the boiler flange (DN125 PN16 or DN200 PN6) directly or by means of a spring package. The spring package dampens the recoil towards the boiler wall. The Shock Pulse Generator can be mounted horizontally at the boiler wall or vertically at the boiler roof.

Safety and Control

We attach great importance to the safety of the Shock Pulse Generator technology. The control of Shock Pulse Generators is carried out by single or multiple control cabinets, which are equipped with PLC and Touch screen-Interface. In case of deviation of standard operation the generator will be shut down automatically.
Different standards are available for the signal exchange with the DCS and also with the manufacturer or the maintenance partner.

  • The Shock Pulse Generator is safe and harmless
  • CE-certification and EU-Conformity declaration according pressure equipment directive PED, Category II (type approval module B, production approval C1)
  • All parts and components are constructed high pressure resistant
  • Installation of gas distribution according to local regulation
  • The mixing of the flammable gas mixture is only carried out in the pressure resistant Shock Pulse Generator
  • PLC controller surveys important process data and stops the Shock Pulse Generator, if a deviation from setting values occurs
  • Automated, no need for operation or actions by the operating crew
  • Prior to each shock pulse the alarm horn is blown and a flash light is operated
  • Loudness of pulse bang outside of the boiler approx. 120 dBa, short peak
  • No danger to create leaks in boiler tubes because of shock pulses (experience also from Bang&Clean®)
  • No use, transport and storage of explosives (Dynamite)
  • Profibus, Modbus or hardwired (24VDC) signal exchange

Within the framework of a growing Industry 4.0 standardization, Explosion Power GmbH developed a web platform (i.e.SPGLogView) and remote access hardware (i.e.SiteManager) for the whole Shock Pulse Generator fleet. The new remote access hardware is installed as a standard for all new projects since March 2016 and is also available for all existing installations. Control cabinets equipped with a SiteManager
Send operational data of connected Shock Pulse Generators daily to the GateManagerTM, located at Explosion Power’s head office (see scheme above). Each SiteManagerTM communicates solely with the GateManager, to which it was linked to during the setup procedure. The operational data is made accessible to the respective customer and service partner over the SPGLogView web interface. Additionally, the control cabinet’s HMI can be accessed for remote support. The customer is asked each time for his approval, before any remote access is carried out.