Soot removal process and assembly in cooling sectors and recuperators
Soot removal process at or inside a synthesis gas- and/or CO-containing gas production apparatus using as feed gases carbon dioxide, steam, hydrogen and/or a hydrocarbon-containing residual gas and using electrical energy in RWGS processes, electrolyses for electrochemical decomposition of carbon dioxide and/or steam, reforming operations and/or synthesis gas production processes with at least one gas production unit, an electrolysis stack and/or a heater-reactor combination for performing an RWGS reaction and at least one cooling sector/recuperator for CO-containing gas and/or synthesis gas, and also a soot removal assembly. Formation of soot can be suppressed or prevented during gas cooling and soot that is nevertheless deposited can be removed again from the heat exchanger surface.
1. A soot removal process inside a synthesis gas-production apparatus using electrical energy in a synthesis gas operation having at least one electrolysis stack and at least first and second recuperators connected in parallel, each recuperator having a cooling side and a heating side, the cooling side for transferring thermal energy from CO-containing gas produced in the electrolysis stack and the heating side for receiving the transferred thermal energy, the process comprising:
introducing CO-containing gas produced in the electrolysis stack into the cooling side of the first and second recuperators,
introducing a feed gas stream comprising at least one of carbon dioxide and steam into the heating side of the first and second recuperators and heating said feed gas stream by transfer of thermal energy from the cooling side of the first and the second recuperators,
removing deposited soot from the cooling side of the first recuperator by temporarily operating the first recuperator in a soot removal operation by interrupting the flow of CO-containing gas from the electrolysis stack through the first recuperator, while continuing the flow of CO-containing gas from the electrolysis stack through the second recuperator such that synthesis gas operation is not interrupted in the electrolysis stack,
heating the first recuperator by feeding into the cooling side at least one of a CO 2 containing gas and an oxygen containing gas stream heated to an ignition temperature of soot by means of a temporarily connectable additional heater,
reacting the soot deposits in the first recuperator with said at least one of a heated CO 2 -containing gas and oxygen containing gas stream flowing through the cooling side of the recuperator in an opposite direction to the flow direction during synthesis gas operation, and
supplying the reaction gas of the soot removal operation from the cooling side of the first recuperator to the cooling side of the parallel arranged second recuperator.
2. The soot removal process according to claim 1 , wherein
a control valve is provided which is adapted to completely close a gas flow of one of the recuperators.
3. The soot removal process according to claim 2 , wherein the control valve regulates the two partial streams such that the temperatures of the parallel gas flows are approximately equal after the recuperators.
4. The soot removal process according to claim 1 , wherein the temporarily connectable additional heater heats the CO 2 /air-containing gas to a temperature above the ignition temperature of soot.
5. The soot removal process according to claim 1 , wherein in synthesis gas operation the synthesis gas is divided into two streams and in that each of the streams is recupratively cooled against feed gas streams of CO 2 and H 2 Og and then cooled with final coolers operating with cooling water.